BOM MPAP June 2005.pdf

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This document and the copyright is owned by Akzo Nobel Engineering bv Arnhem The Netherlands. It may neither be copied nor submitted to third parties for copying, without permission of the company.

dept E-PX

author F. Winkel/fwi

proj. no. 405.014

subject Basic Operating Manual Magadi Soda Ash Plant

Distribution book no. address

1 Mr. Cleary Magadi Soda Company, Kenya

2 Mr. Balasundaran Larsen & Toubro, Chennai, India

3 Mr. Schouwenaars Akzo Nobel Base Chemicals, Amersfoort, The Netherlands

4 Mr. Geuzebroek Akzo Nobel Engineering (E-PX), Arnhem, The Netherlands

5 Mr. van Lotringen Akzo Nobel Engineering (E-PX), Arnhem, The Netherlands

6 File Akzo Nobel Engineering, (E-SI), Arnhem, The Netherlands

Basic Operating Manualdoc. no. 2.187.735 -

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Revisions rev. description Page Date initials

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CONTENTS

1 INTRODUCTION ..................................................................................................... 1.1 2 PLANT OPERATION ............................................................................................... 2.1 2.1 General description of the process .......................................................................... 2.1 2.2 Location, layout and process sections ..................................................................... 2.4 2.2.1 Location ................................................................................................................... 2.4 2.2.2 Plant structure.......................................................................................................... 2.4 2.3 Plant operation and control system.......................................................................... 2.5 2.4 Operating philosophy ............................................................................................... 2.7 3 SPECIFICATION OF RAW MATERIALS, AUXILIARY MATERIALS AND UTILITIES

................................................................................................................................. 3.1 3.1 Specification of raw material .................................................................................... 3.1 3.1.1 Lake Magadi Trona .................................................................................................. 3.1 3.1.2 Fines Bank Material ................................................................................................. 3.2 3.2 Specification of auxiliary materials ........................................................................... 3.3 3.2.1 Lake brine ................................................................................................................ 3.3 3.2.2 Flocculant................................................................................................................. 3.3 3.2.3 Butane...................................................................................................................... 3.3 3.2.4 Trisodium phosphate ............................................................................................... 3.3 3.2.5 Morpholine/Ammonia ............................................................................................... 3.3 3.2.6 Biocide ..................................................................................................................... 3.3 3.2.7 Flocon 100 ............................................................................................................... 3.4 3.2.8 Emulsified silicone (antifoam) .................................................................................. 3.4 3.2.9 Diatomaceous earth................................................................................................. 3.4 3.3 Specification of utilities............................................................................................. 3.5 3.3.1 Heavy fuel oil ........................................................................................................... 3.5 3.3.2 Industrial diesel oil (not used) .................................................................................. 3.5 3.3.3 Steam 15 bar ........................................................................................................... 3.6 3.3.4 Steam 3 bar ............................................................................................................. 3.6 3.3.5 Instrument and plant air ........................................................................................... 3.6 3.3.6 Electric power .......................................................................................................... 3.6

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3.3.7 Process water .......................................................................................................... 3.7 3.3.8 Hot process water .................................................................................................... 3.7 3.3.9 Purge water.............................................................................................................. 3.7 3.3.10 Potable water ........................................................................................................... 3.7 3.3.11 Raw water ................................................................................................................ 3.9 3.3.12 Cooling tower water ............................................................................................... 3.10 4 SAFETY, ENVIRONMENTAL AND HEALTH ASPECTS......................................... 4.1 4.1 Safety....................................................................................................................... 4.1 4.2 Environment............................................................................................................. 4.2 4.3 Health....................................................................................................................... 4.2 4.4 Material Safety Data Sheets .................................................................................... 4.3 5 200 SECTION .......................................................................................................... 5.1 5.1 Process description.................................................................................................. 5.1 5.1.1 Introduction .............................................................................................................. 5.1 5.1.2 Dredging (PFD 100-01, OSBL) ................................................................................ 5.1 5.1.3 Dredge product receiving and reclaim (PFD 200-01)............................................... 5.1 5.1.4 Classification and centrifugation (PFD 200-02)........................................................ 5.2 5.2 Normal operation ..................................................................................................... 5.4 5.2.1 Dredge product receiving (PID 200-02) ................................................................... 5.4 5.2.2 Washery feed cyclones (PID 200-03) ...................................................................... 5.4 5.2.3 Classification (PID 200-04) ...................................................................................... 5.5 5.2.4 CRS wash tank (PID 200-05)................................................................................... 5.5 5.2.5 Classifier overflow (PID 200-06) .............................................................................. 5.6 5.2.6 CRS hydrocyclones and centrifuges (PID 200-07) .................................................. 5.6 5.2.7 CRS centrate (PID 200-08) ...................................................................................... 5.6 5.2.8 CRS stockpile reclaim (PID 200-09) ........................................................................ 5.7 5.2.9 Tailings settler (PID 200-10) .................................................................................... 5.8 5.2.10 Setting list ................................................................................................................ 5.9 5.3 Logic functions ....................................................................................................... 5.11 5.4 Start up .................................................................................................................. 5.16 5.4.1 Initial start up (with empty tanks)............................................................................ 5.16

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5.4.2 Normal start up, washery section (filled tanks) ...................................................... 5.20 5.4.3 Restart from standby.............................................................................................. 5.21 5.5 Shut down .............................................................................................................. 5.23 5.5.1 Going to standby.................................................................................................... 5.23 5.5.2 Normal shut down of washery................................................................................ 5.23 5.5.3 Maintenance shutdown of washery........................................................................ 5.26 5.6 Operator actions, periodic checks.......................................................................... 5.27 5.6.1 Line flushing to prevent settling in lines ................................................................. 5.27 5.6.2 Tank cleaning to remove scale formation .............................................................. 5.27 5.6.3 Checks ................................................................................................................... 5.27 5.6.4 Critical process parameters ................................................................................... 5.28 5.6.5 Sampling and analyses.......................................................................................... 5.28 5.7 Deviating operating conditions............................................................................... 5.29 5.7.1 Turn down capacity ................................................................................................ 5.29 5.7.2 Dry reclaim............................................................................................................. 5.29 5.7.3 CRS reclaim........................................................................................................... 5.31 5.7.4 Centrifuge flushing ................................................................................................. 5.31 5.7.5 Shut down in case of failure of liquor supply from the dredges.............................. 5.32 5.7.6 Failure of dredge product tank 200-TK-005 or related equipment (bypass of

200-TK-005)........................................................................................................... 5.32 5.7.7 Classifier not available ........................................................................................... 5.33 5.7.8 CRS cyclone or centrifuge not available ................................................................ 5.33 5.7.9 Diverting classified slurry to classifier discharge bunker 200-ZC-030.................... 5.34 5.7.10 Lifting of classifying screw ..................................................................................... 5.35 5.7.11 Plugging of washery sieve bend screen 200-SN-020; use of by-pass................... 5.35 5.7.12 Centrifugal pump start/stop and changeover ......................................................... 5.35 5.7.13 Start/stop and changeover of 200-PP-050/051...................................................... 5.37 5.7.14 General procedure for belt conveyor...................................................................... 5.39 5.7.15 Trouble shooting table controls of 200-TK-030...................................................... 5.40 5.7.16 Operation of sump 200-SU-090 ............................................................................. 5.41 6 MILLING AND CALCINING ..................................................................................... 6.1

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6.1 Process description.................................................................................................. 6.1 6.2 Normal operation ..................................................................................................... 6.3 6.2.1 Calcination waste (P&ID 400-15)............................................................................. 6.3 6.2.2 Setting list ................................................................................................................ 6.3 6.3 Logic functions ......................................................................................................... 6.4 6.4 Start-up and shutdown of Dust transport ................................................................. 6.5 6.4.1 Normal start-up ........................................................................................................ 6.5 6.4.2 Normal shut-down.................................................................................................... 6.5 6.5 Start-up and shut-down of dump tank...................................................................... 6.6 6.5.1 Initial start-up ........................................................................................................... 6.6 6.5.2 Normal start-up ........................................................................................................ 6.6 6.5.3 Procedure for emptying tank after dumping............................................................. 6.6 6.5.4 Normal shutdown ..................................................................................................... 6.6 6.6 Operator actions, periodic checks............................................................................ 6.7 6.7 Deviating operating conditions................................................................................. 6.8 6.7.1 Dump tank 400-TK-060............................................................................................ 6.8 6.7.2 Too low liquor feed flow to 200-TK-010 ................................................................... 6.8 6.7.3 Pump failure of 200-PP-011/012.............................................................................. 6.8 6.7.4 High temperature of liquor return from 400-CV-040................................................. 6.9 6.8 Basic operating manual roller mill and calciner section ......................................... 6.10 6.9 Washout procedures roller mill and calciner section.............................................. 6.11 7 CRYSTALLIZATION ................................................................................................ 7.1 7.1 Process description.................................................................................................. 7.1 7.1.1 Introduction .............................................................................................................. 7.1 7.1.2 First stage crystallization (PFD 500-01) ................................................................... 7.1 7.1.3 Second stage crystallization (PFD 500-02).............................................................. 7.4 7.1.4 Second stage monohydrate centrifuges (PFD 500-03)............................................ 7.5 7.1.5 Liquor polishing (PFD 500-04) ................................................................................. 7.5 7.2 Normal operation ..................................................................................................... 7.7 7.2.1 First stage crystallizer (PID 510-01)......................................................................... 7.7 7.2.2 First stage elutriator (PID 510-02)............................................................................ 7.8

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7.2.3 First stage centrifuges (PID 510-03) ........................................................................ 7.9 7.2.4 First stage settler (PID 510-04) ................................................................................ 7.9 7.2.5 First stage settler overflow (PID 510-05)................................................................ 7.10 7.2.6 Guar make-up, transfer and distribution (PID 510-07) ........................................... 7.10 7.2.7 Second stage crystallization feed (PID 520-06) ..................................................... 7.10 7.2.8 Second stage anhydrous reactor (PID520-01)....................................................... 7.11 7.2.9 Second stage crystallizer (PID 520-02).................................................................. 7.12 7.2.10 Second stage elutriator (PID520-03)...................................................................... 7.12 7.2.11 Second stage centrifuges (PID 520-04) ................................................................. 7.13 7.2.12 Second stage thermo compressor (PID 520-05).................................................... 7.13 7.2.13 Second stage centrate tank (PID 520-07).............................................................. 7.13 7.2.14 Second stage settler (PID 520-08)......................................................................... 7.13 7.2.15 Polishing filter feed (PID 520-09) ........................................................................... 7.14 7.2.16 Liquor polishing (PID 520-10) ................................................................................ 7.15 7.2.17 Polishing filtrate and backflush (PID 520-11) ......................................................... 7.15 7.2.18 Condensate (PID 520-12) ...................................................................................... 7.16 7.2.19 Precoat and filter aid (PID 520-13) ........................................................................ 7.16 7.2.20 Hot process water (PID 520-14) ............................................................................ 7.16 7.2.21 Setting list .............................................................................................................. 7.17 7.3 Logic functions ....................................................................................................... 7.24 7.4 Start-up and shutdown of the crystallization unit ................................................... 7.29 7.4.1 Fill system and start rotating equipment ................................................................ 7.29 7.4.2 Start first stage production ..................................................................................... 7.37 7.4.3 Start second stage production ............................................................................... 7.39 7.4.4 Shut-down.............................................................................................................. 7.42 7.5 Going standby and restart...................................................................................... 7.45 7.5.1 Going standby of first stage crystallization circuit .................................................. 7.45 7.5.2 Going on standby of second stage crystallization circuit........................................ 7.45 7.5.3 Restart from stand-by of first stage crystallization unit........................................... 7.47 7.5.4 Restart from standby of second stage crystallization circuit .................................. 7.47 7.6 Operator actions, periodic checks.......................................................................... 7.48

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7.6.1 Water balance........................................................................................................ 7.49 7.6.2 Critical process parameters ................................................................................... 7.50 7.6.3 Sampling and analyses.......................................................................................... 7.52 7.7 Deviating operating conditions............................................................................... 7.53 7.7.1 Buffering of slurry in case of capacity variation of first and second stage.............. 7.53 7.7.2 Guar preparation procedure................................................................................... 7.53 7.7.3 Guar flow rate measuring procedure...................................................................... 7.54 7.7.4 Heating process liquor with start-up heater............................................................ 7.54 7.7.5 Pump failure of filter feed pump 520-PP-060/061.................................................. 7.55 7.7.6 Centrifugal pump start/stop and changeover ......................................................... 7.56 7.7.7 Start/stop and changeover of 510-PP-050/051 and 520-PP-050/051.................... 7.57 7.7.8 Start-up and shutdown of condensate tank 520-TK-045........................................ 7.59 7.7.9 Start-up and shut down of hot water tank 520-TK-091 .......................................... 7.60 7.7.10 Performance monitoring of anhydrous reactor heater............................................ 7.61 7.7.11 Filter regeneration.................................................................................................. 7.62 7.7.12 Precoat preparation ............................................................................................... 7.64 7.7.13 Filter aid system..................................................................................................... 7.65 7.7.14 Flushing of centrifuge............................................................................................. 7.66 7.7.15 Operation of sump 520-SU-095 ............................................................................. 7.66 7.7.16 Operation of sump 520-SU-100 ............................................................................. 7.67 7.7.17 Washout procedure crystallization section............................................................. 7.68 8 FLUID BED DRYING (PFD600-01).......................................................................... 8.1 8.1 Process description.................................................................................................. 8.1 8.2 Normal operation ..................................................................................................... 8.3 8.2.1 Feed to static fluidbed dryer for pure soda ash plant (PID 600-01) ......................... 8.3 8.2.2 Static fluidbed dryer for pure soda ash plant (PID 600-02) ...................................... 8.3 8.2.3 Air supply and air heating for static fluidbed dryer for pure soda ash plant (PID 600-

03)............................................................................................................................ 8.4 8.2.4 Monohydrate dryer dust and condensate discharge (PID 600-04) .......................... 8.5 8.2.5 Setting list ................................................................................................................ 8.6 8.3 Logic functions ......................................................................................................... 8.9

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8.4 Start-up and shutdown of fluid bed dryer ............................................................... 8.11 8.4.1 Normal start-up (from empty bed) .......................................................................... 8.11 8.4.2 Restart from standby.............................................................................................. 8.13 8.4.3 Shut down (empty fluid bed) .................................................................................. 8.13 8.4.4 Going to standby.................................................................................................... 8.14 8.5 Start-up and shutdown Dust transport ................................................................... 8.14 8.5.1 Normal start-up ...................................................................................................... 8.14 8.5.2 Normal shut-down.................................................................................................. 8.14 8.6 Start-up Condensate collection and discharge ...................................................... 8.15 8.6.1 Normal start-up ...................................................................................................... 8.15 8.6.2 Normal shut down .................................................................................................. 8.15 8.7 Operator actions, periodic checks.......................................................................... 8.15 8.7.1 Periodic checks...................................................................................................... 8.15 8.7.2 Critical process conditions ..................................................................................... 8.16 8.7.3 Sampling and analyses.......................................................................................... 8.16 8.8 Deviating operating conditions............................................................................... 8.17 8.8.1 Cleaning of dryer.................................................................................................... 8.17 8.8.2 Too low liquor feed to 520-TK-040......................................................................... 8.17 8.8.3 Pump failure of 520-PP-040/041............................................................................ 8.18 8.8.4 Dust transport ........................................................................................................ 8.18 8.8.5 Washout procedure of fluid bed dryer .................................................................... 8.19 9 EMERGENCY SITUATIONS ................................................................................... 9.1 9.1 Power Failure........................................................................................................... 9.1 9.1.1 Consequences for the washery section 200 ............................................................ 9.1 9.1.2 Consequences for calciner unit 400......................................................................... 9.2 9.1.3 Consequences for dumptank 400 ............................................................................ 9.3 9.1.4 Consequences for Dust transport 400 ..................................................................... 9.3 9.1.5 Consequences for Crystallization section ................................................................ 9.4 9.1.6 Dust transport 600 ................................................................................................... 9.4 9.1.7 Steam boiler............................................................................................................. 9.4 9.2 Process water Failure .............................................................................................. 9.4

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9.2.1 Consequences for the washery section 200 ............................................................ 9.4 9.2.2 Consequences for calciner section .......................................................................... 9.5 9.2.3 Consequences for Dumptank 400 ........................................................................... 9.5 9.2.4 Consequences for first crystallization section .......................................................... 9.5 9.2.5 Consequences for second crystallization section .................................................... 9.5 9.2.6 Consequences for cooling water system ................................................................. 9.5 9.3 Purge water failure ................................................................................................... 9.6 9.4 Cooling water failure ................................................................................................ 9.6 9.5 Steam failure............................................................................................................ 9.6 9.6 Dredge feed failure .................................................................................................. 9.7 9.7 Instrument air and plant air failure ........................................................................... 9.7 9.8 Guar solution failure ................................................................................................. 9.8 9.9 Anti foam solution failure in washery section ........................................................... 9.8 10 COMMISSIONING AND INTIAL START-UP ......................................................... 10.1 10.1 Washery................................................................................................................. 10.1 10.2 Dryer dust transport 400 ........................................................................................ 10.1 10.3 Crystallization......................................................................................................... 10.1 10.4 Dryer ...................................................................................................................... 10.1 10.5 Dryer dust transport 600 ........................................................................................ 10.2 10.6 Condensate tank 600-TK-010................................................................................ 10.2 11 MAINTENANCE..................................................................................................... 11.1 11.1 Maintenance inspection ......................................................................................... 11.1 11.2 Fluid bed dryer inspection...................................................................................... 11.1 11.3 Pump and agitator seals ........................................................................................ 11.2 11.4 Inspection of tanks ................................................................................................. 11.2

APPENDIX 1: TROUBLE SHOOTING TABLE FOR 200-PP-050/051, 510-PP-050/051, 520-PP-

050/051

APPENDIX 2: TROUBLE SHOOTING TABLE WARMAN PUMPS

APPENDIX 3: LIST OF ACRONYMS

APPENDIX 4: UNIT SYSTEM


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1 INTRODUCTION

This manual describes the basic principles of the start-up and operation of the Pure Soda ash plant at Magadi Kenya. The design of this plant is based on process development by Brunner Mond in cooperation with package unit vendors and on the experience with other comparable units (e.g. crystallization, drying). These basic operating procedures have been compiled by Akzo Nobel Engineering and are based on operating experience at Akzo Nobel and the basic design for Magadi pure soda ash plant as reported in the Basic Engineering Package. Furthermore, information from package unit vendors FFEM, HPD, L&T Niro (LTN) and HDO and from some equipment vendors is also included. In this manual, input from package unit vendors of mill&calciner, crystallization and drying are included. This manual, together with the instructions of the different equipment suppliers, will serve as a guideline for: – training of operating personnel – preparing detailed operating instruction – commissioning and first start-up of the plant The manual is divided into 11 chapters: – Chapter 1: Introduction – Chapter 2 – 4: General information on plant operations, specifications of chemicals and

utilities appearing in the process, and safety provisions – Chapter 5 – 8: Process description, process characteristics and detailed information on

normal operation, start-up situations and deviation from normal operating conditions – Chapter 9: Emergency situations of the plant – Chapter 10: Information on first start-up and commissioning of the plant – Chapter 11: Basic information on maintenance of the plant; for detailed information

refer to information from vendors. Operating manuals for section 100 (Dredging), Section 700 (Screening), Section 800 (Storage and load-out), Section 900 (Utilities) and Electrical Power Generation are provided separately from this manual. Other manuals relevant to this plant include: – Analytical Manual – Magadi Soda Company Safety Manual


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2 PLANT OPERATION

2.1 General description of the process

The pure soda ash plant is divided into the following sections: 100 Dredging 200 Washing 400 Milling and flash calcining 500 Crystallizing 600 Monohydrate drying 700 Product screening 800 Product storage and load out 900 Utilities Trona slurry is dredged (see Dredge and mining system basic operating procedures) from lake Magadi and is pumped to the washery (section 200). The prime objective of the washery is to remove as much as possible of the soluble impurities (e.g. NaCl), and insoluble impurities (e.g. organic material) and to produce a relatively dry CRS (Crushed Refined Soda) as feedstock for the Mill & calciner unit. In the washery, insoluble impurities are separated by applying cyclones, a classifier and centrifuge. Also the washery provides liquor for ESP dust recycle, crystallization second stage vent condenser and the boiler scrubber. During occasions when the dredge is incapable of supplying trona, the liquor flow continues and trona can be supplied from a raw trona stockpile via the dry reclaim route. Via this route fines bank material can also be supplied as feed stock. In the calciner section, CRS is ground in the roller mill. Grinding is essential because of the particle size purification process as applied in the crystallization section. The ground material is reacted at elevated temperatures (up to 425°C) to convert the NaHCO3 part of trona into Na2CO3. Dust is separated in an electrostatic precipitator (ESP) and recycled to the process. In order to avoid dust accumulation, it may be necessary to discharge part of this dust to the washery section using lake liquor as the transportation medium. Na2CO3 from the calciner unit is supplied to the first crystallization section to form Na2CO3.H2O. Fixed insolubles (mainly NaF) are then separated in an elutriation leg. Subsequently the product is de-liquored and washed on a centrifuge. A second crystallization step is required to reach the low NaF specification of the final product. In the second stage monohydrate is crystallized to anhydrous Na2CO3 and back to


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Na2CO3.H2O. Fixed insolubles are again separated in an elutriation leg, and subsequently the product is deliquored and washed on a centrifuge. A liquor purge is provided in the first stage crystallization section. This purge serves to keep sodiumsulfate concentration below 3 wt% to prevent contamination of the final product. Sodiumsulfate is formed in small quantities in the calciner section. In the fluid bed dryer the monohydrate is dried and subsequently dehydrated to anhydrous Na2CO3 (dense soda ash), oversize is then removed in the screening section and the product is then transferred to the storage section and rail load-out section.


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2.2 Location, layout and process sections

2.2.1 Location

The plant is located on the Eastern shore line of Lake Magadi, next to an existing plant of Magadi Soda Company. . Elevation m 596 Ambient pressure kPa 94.9 Temperature max. (shade) °C 41

min. (shade) °C 16 Design dry bulb °C 36 Design wet bulb °C 22 Precipitation mm/y 455 Days rainfall d/y 73 Evaporation mm/y 4105 Average design wind km/h 3.6 Maximum wind km/h 161 Seismic zone 2A

2.2.2 Plant structure

In principle all process equipment is located outside in steel structures.


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2.3 Plant operation and control system

For process control, a Distributed Control System (DCS) is installed in the central control room. In each section field operators are present. The DCS shows process data and equipment status. For all sections, except the section 400, mill and calciner section, the desk operator has very limited possibility to remotely start and stop equipment. In general the field operator will be available to start and stop equipment if needed. For the mill and calciner section, the desk operator starts and stops the equipment via the DCS. A boiler control room is provided near the boiler area where the boiler is independently controlled from. The power generation equipment and the dredge are also controlled and operated locally from their own control rooms, although certain critical information is relayed back to the main plant control room for information purposes only. Control logics are described in the functional description and the FLD’s (functional logical diagrams). The DCS shows remote instrument readings of all relevant process parameters. An operator workstation (OWS) is located in the washery section. This OWS provides full access to the washery section. The washery section can be operated by the field operator via the OWS and by the desk operator via a DCS station in the control room. Process interlocks are incorporated within in the DCS and motorstatus’s are also displayed. Alarm is provided for when motors are stopped. All drives are provided with a thermal overload protection, so they need a reset to be started when there is a thermal overload situation. In addition all drives can be turned off by a local switch. Thermal overload and emergency switches are hardwired to the motor control centre (MCC). The DCS is provided with an un-interrupted power supply (UPS), which enables the operator to shutdown the plant safely in case of total loss of electrical power. For the supply of electrical power a connection with the external grid (KP&LC) is available and a total of 5 on-site fuel oil fired power generators (see separate operating procedures). In a normal situation power is supplied by KP&LC and 2 power generators. If one of the power generators fails, depending on the actual remaining capacity, the pure ash plant availability is maximized by shedding load in a prioritized order. The Power management system PMS automatically trips circuit breakers to shed load to allow the system to stay within voltage and frequency limits in the event of utility power failure, or failure of Diesel cycle engine drive Generator (DG). The order of priority (highest first) shall be:


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– Critical drives: items of equipment that need to be maintained in a safe mode of operation and to ensure ease of start up after failure of the electrical power supply.

– Essential drives: All other items of the pure ash plant that are needed for continuous operation, excluding the majority of the washery area.

– Non essential drives: Majority of the new washery area A detailed description of the way the PMS acts on the electrical equipment and procedures for restart is supplied under separate cover. When sufficient power becomes available, the equipment can be restarted by operator (no automatic restart of equipment). Materials management A system for materials management of auxiliary materials is provided under separate cover. In this system the following aspects have been covered: – Materials have to be supplied in suitable packaging, with clear identification and

product specification forms (purchasing) – Procedure for sampling and analyzing of materials – Materials have to be stored on dedicated locations in the storage area – Operators that use the auxiliary materials have to be instructed well on the location of

the materials and the applications.


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2.4 Operating philosophy

The dredge supplies trona slurry to the washery. In case the dredge does not supply trona (unexpected failure or scheduled maintenance), the dredge pump will continue to supply liquor. In this case trona will be supplied to the dredge product tank from the raw trona stockpile, via the dry reclaim route. There is a small buffer between washery (200 section) and the roller mill & calciner (section 400) in the roller mill feed bin 200-BN-085. In case the washery is out of operation, CRS can be supplied from the CRS stockpile by front end loader to this bin. When the above route is used to feed the roller mill, the liquor feed to the washery has to be maintained, because liquor is required for ESP dust recycle and for cooling of second stage vent condenser. Product from the calciner section is directly introduced to the first stage crystallizer. This means that failure of either of these sections, results in a production stoppage of both sections. The product from the first stage crystallizer is collected in the second stage crystallizer feed tank 520-TK-005. This tank provides the possibility to run the second stage for a limited time without running the first stage crystallizer. When the first stage is running without the second stage, then the solids concentration in the feed tank will increase. This can only carried out be for a short duration in order give the operating team sufficient time to put the first stage in stand-by mode. Also dilution with filtrate from the 1st stage centrifuge is not desirable, which would lead to product quality issues. Turndown of washery The washery can be turned down to 50% of normal operating capacity in case one of the centrifuges is not in operation. If required, additional feed to the mill can be supplied with CRS from CRS stockpile. As the product from the classifier can be partly diverted to intermediate stockpile 200-ZC-030, the dredge feed can continue at 100% rate, but the operator has to remove product from stockpile 200-ZC-030 whilst operating in this mode. As mentioned previously liquor supply rate has to be maintained in order to supply liquor at the required flow rates to the ESP dust recycle and second stage vent condenser. Turndown of mill and calciner unit The equipment within the Mill and calciner unit all run at the same capacity. In case the first stage crystallizer operates with one centrifuge, then the unit will run at 50% capacity. However, running the calciner unit below 70% can be problematic (decreased conversion). If this situation occurs in practice, optimum condition will have to be found in order to maximize rate in an effort to maintain product quality (increase feed over the one running centrifuge as much as possible to keep the calciner running at as high possible capacity).


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Turndown of crystallizer First stage crystallizer can be turned down to 50% of normal rate in case one centrifuge is not running. The calciner has to reduce capacity as well (see above). Feed tank 200-TK-005 provides time to decrease the second stage capacity to 50% also (stop one centrifuge). If the second stage is running at 50%, the first stage will have to be reduced to 50% as well and in this case the tank provides time for the operators to respond. At turndown the removal of impurities will be less efficient which lowers product quality. Turndown of fluid bed dryer The dryer has no real buffer capacity and it will be turned down to 50% if crystallizer is turned down. Buffering time of main buffer tanks of the process: Tag number Equipment name Operating

volume

Normal Operating

capacity 1)

Buffering time 2)

200-TK-005 Dredge product tank 120 m3 93 m3 11 minutes

200-TK-030 CRS wash tank 130 m3 95 m3 22 minutes

200-ZC-040 CRS stockpile 5000 ton 5000 ton 47 hours

200-BN-085 Roller Mill feed bin 100 m3 50 m3 60 minutes

520-TK-005 Second stage cryst. Feed tank 269 m3 190 m3 2 hours

800-BN-020

A/B/C

Product Silo 5000 ton in

total

4 days

1) Normal operating capacity is defined as follows: from normal operating level to low level 2) Buffering time is defined as follows:

• For stockpiles and bunkers: from empty to full

• For tanks from normal liquid level to low liquid level


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3 SPECIFICATION OF RAW MATERIALS, AUXILIARY MATERIALS AND UTILITIES

Unless specified otherwise the specified pressures are absolute at ground level.

3.1 Specification of raw material

3.1.1 Lake Magadi Trona

Composition (dry basis): typical max. min. Na2CO3.NaHCO3.2H2O wt% > 91.95 Na2SO4 wt% nil NaCl (occluded) wt% < 0.05 Insolubles total wt% < 6.0 10 1.0 free wt% < 5.65 fixed wt% < 0.35 NaF wt% < 2.0 3.0 0.5 The typical composition is given on a 24 hour time weighed average basis. The maximum composition is for a maximum of 1 hour on a maximum of 1 occasion per 24 hour period. Specific gravity - 2.15 Bond work index (metric) - 5.2 Hardness moh 2.5 to 3 Screen analysis cumulative (weighed average): 9.5 mm wt% 0.58 8.0 mm wt% 0.58 6.7 mm wt% 6.16 5.7 mm wt% 10.33 4.0 mm wt% 16.45 3.4 mm wt% 20.50 1.0 mm wt% 54.19 0.595 mm wt% 68.11 0.420 mm wt% 76.73 0.125 mm wt% 92.71 0.050 mm wt% 95.41 < 0.050 mm wt% < 5.0 Supply as 80 wt% solids by front-end loader or as about 20 wt% slurry by pipeline. Composition of liquor: see lake brine.


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3.1.2 Fines Bank Material

Composition (dry basis): Na2CO3.NaHCO3.2H2O wt% > 85 Insolubles total wt% < 15 NaF wt% < 0.5 Moisture wt% < 5 Screen analysis <100 µm wt% 25 Percent of feedstock wt% < 10 Supply by front-end loader.


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3.2 Specification of auxiliary materials

3.2.1 Lake brine

Composition: wet dry season Na2CO3 wt% 14.0 18.0 NaHCO3 wt% 0.5 0.1 Na2SO4 wt% 0.1 0.1 NaCl wt% 9.0 12.0 NaF wt% 0.3 0.3 Specific gravity - 1.20 1.30 pH - 11 11 Temperature °C 35 35 Viscosity mPas 6 6

3.2.2 Flocculant

Solution of 0.5 wt% guar gum. Viscosity mPas 400 Supply of guar gum by 50 kg bags (HOLD).

3.2.3 Butane

Quality: LPG with 60 % butane and 40 % propane. Used as oil burner ignition fuel. Supplied in 22.5 kg gas bottles.

3.2.4 Trisodium phosphate

Used as antiscalant. Supply by 50 kg bags

3.2.5 Morpholine/Ammonia

Added to boiler make-up water and condensate. Supply by 20 liter bottles.

3.2.6 Biocide

Added to cooling tower water. Supply by 20 liter bottles.


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3.2.7 Flocon 100

Added to boiler make-up water. Supply by 20 liter bottles.

3.2.8 Emulsified silicone (antifoam)

Type: Dow Corning Silicone (B). Concentration wt% 100 Supply by 200 liter carboy.

3.2.9 Diatomaceous earth

Type: Celite Hyflo Supercel Density kg/m3 160 < 100 µm wt% 95 Median cake pore size µm 7 pH - 10 Supply by 20 kg bags.


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3.3 Specification of utilities

3.3.1 Heavy fuel oil

Higher heating value MJ/kg 43 Nitrogen content for design wt% 0.25 Sulphur content (max.) wt% 3.7 Viscosity at 50 °C (max.) cSt 180 Flash point PMCC (min.) °C 65 Pour point (max.) °C 24 Density @ 20 °C kg/m3 985 Water content vol% 0.75 Solids content wt% 0.15 Metal analysis: K ppm wt 2.9 Ca ppm wt 34 Fe ppm wt 28 Ni ppm wt 9 Cu ppm wt 8 Pb ppm wt 2 V ppm wt 12 Supply by pipeline.

3.3.2 Industrial diesel oil (not used)

Higher heating value (min.) MJ/kg 44.8 Sulphur content (max.) wt% 1.8 Viscosity at 40 °C (max.) cSt 10 (IP test method) Flash point PMCC (min.) °C 66 Pour point (max.) °C 12 Density @ 20 °C (max.) kg/m3 915 Water content (max.) vol% 0.25 Sediment content wt% 0.02 Ash (max.) wt% 0.02 Carbon residue (max.) wt% 0.45 Strong acids No. mg KOH/g - Total acid No. (max.) mg KOH/g 0.5 Asphaltenes (max.) wt% 2.9 Supply by barrel for start-up.


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3.3.3 Steam 15 bar

Generated ISBL. Process design temperature °C 210 Process design pressure bar 15.5 Mechanical design temperature °C 236 design pressure bar 18.5 Supply by pipeline.

3.3.4 Steam 3 bar

Generated ISBL. Process design temperature °C 150 Process design pressure bar 3 Mechanical design temperature °C 210 design pressure bar 6 Supply by pipeline.

3.3.5 Instrument and plant air

Generated ISBL. Dust and oil free. Dewpoint °C - 20 Process design pressure bar 7 Minimum pressure bar 5.5 Mechanical design temperature °C 50 design pressure bar 8

3.3.6 Electric power

24 V dc for instrument power 110 V 1 ph. 50 Hz 240 V 1 ph. 50 Hz 415 V 3 ph. 50 Hz 5.5 kV 3 ph. 50 Hz for > 150 kW.


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3.3.7 Process water

Quality: Fish-springs water Composition: Na2CO3 wt% 0.83 NaHCO3 wt% 0.66 Na2SO4 wt% 0.011 NaCl wt% 0.63 NaF wt% 0.014 SiO2 ppm 200 Suspended solids ppm 270 pH - 9.4 Temperature °C 30 Specific gravity - 1.012 Supply by pipeline via pipeline.

3.3.8 Hot process water

Generated ISBL. Quality and composition: see process water Temperature °C 90 Pressure bar 7 Supply by pipeline.

3.3.9 Purge water

Generated ISBL. Quality: Filtered process water. Pressure bar 10 Supply by pipeline.

3.3.10 Potable water

Quality: treated raw water. Composition (analysis 2001-06-25 and 2001-07-25): HCO3

- mg/l 49 SO4

2- mg/l 11.54 CO2 mg/l nil CO3

2- mg/l < 6.00 Cl- mg/l 10.79 F- mg/l 0.34


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PO43- -P mg/l 0.62

Na+ mg/l 3.4 NH4

+ mg/l 0.28 NO3

- mg/l 2.48 Mn ppm 0.027 Cd ppm 0.020 Cr ppm nil Pb ppm nil Cu ppm nil Zn ppm 0.336 Fe ppm 0.193 Mg ppm 2.783 Ca ppm 4.759 K ppm 2.798 Total Si ppm 15.0 Hg ppm < 0.001 Se ppm <0.01 As ppm <0.05 Ba ppm <0.001 Total dissolved solids wt% 0.02 Fixed suspended solids wt% < 0.001 Total alkalinity mg/l 0.049 pH - 7.24 Conductivity µS 200 Total Coliforms MPN/100 ml nil E. Coli MPN/100 ml nil Pressure bar Temperature °C 30 Supply by pipeline.


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3.3.11 Raw water

Composition: Composition (design conditions): HCO3

- ppm 61 SO4

2- ppm 8.08 CO2 ppm 10 CO3

2- ppm < 6.0 Cl- ppm 600 F- ppm 15 PO4

3- -P ppm 1.87 Na+ ppm 100 NH4

+ as N ppm 0.6 NO3

- as N ppm 0.6 Mn ppm 0.1 Cd ppm 0.015 Cr ppm nil Pb ppm nil Cu ppm nil Zn ppm 0.024 Fe ppm 1.4 Mg ppm 2.76 Ca ppm 2.74 K ppm 12 Total Si ppm 15.0 Hg ppm < 0.001 Se ppm <0.01 As ppm <0.05 Ba ppm <0.001 Total dissolved solids ppm 1500 Total suspended solids ppm 56 Total hardness (as CaCO3) ppm 90 Total alkalinity ppm 50 pH - 7.35 Conductivity µS 230 Total Coliforms MPN/100 ml 200 E. Coli MPN/100 ml 60 Pressure bar 8 Temperature °C 30 Supply by pipeline.


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3.3.12 Cooling tower water

Generated ISBL from raw water. Pressure supply bar 5.5 Max. pressure drop bar 1 Temperature supply °C 30 Max. return temperature °C 45 Mechanical design temperature °C 50 design pressure bar 10 Supply and return by pipeline.


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4 SAFETY, ENVIRONMENTAL AND HEALTH ASPECTS

4.1 Safety

– Storage of raw materials and finished products There are no special requirements for the materials used in the plant. The storage of fuel oil for the calciner is existing. However, new intermediate storage between the existing storage and the plant will be provided. Auxiliary materials (like filter aid or guar) in bags or other types of packaging have to be stored in an ordered fashion. All materials have to be labeled clearly to prevent using in the wrong application.

– Lay out

The degree of hazards according the DOW’s F&EI is in the range of light. For the layout of the plant no special arrangements are foreseen in terms of safety distances.

– Fire safety No flammable/combustable materials, except for small amounts of fuel oil and LPG, are present in the plant. There will be fire extinguishing provisions (hydrants).

– Area classifications

Storage area of LPG will is a classified area. LPG is used in burner of steam boiler and calciner burner. In the vicinity of the burner, area classification for instrumentation and other equipment is not applicable. No other flammable liquids or gases are used in the process area, therefore no area classification is executed based on flammable vapors. The way of processing guar gum and the limited amounts indicates that an area classification to prevent dust explosions is not needed.


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4.2 Environment

The Plant is designed is in accordance with the requirements of the World Bank’s Pollution Prevention & Abatement Handbook, 1998 Edition, the U.S Occupational Safety and Health Administration and the American Conference of Governmental Industrial Hygienists. Emission limits for new sources are: Particulates mg/Nm3 50 SO2 mg/Nm3 2000 NOx mg/Nm3 460 1 Nm3 is 1 m3 (dry) at 1 atm. and 0 °C. The the stack of the calciner section and of the fluid bed dryer will be equipped with opacity monitoring equipment. Upper noise threshold limits dictate the level of ear protection required. These have been ascertained and for the near field as a guidance the following actions are required, based on the daily personal exposure (LEP,d): – LEP,d < 85 dB(A):There is a general duty to reduce risk of hearing damage to the lowest

level reasonably practical, but it is not necessary to provide warning signs or ear protectors.

– 85 dB(A) < LEP,d < 95 dB(A): Provide adequate information, instruction and training on the risks associated with noise and how personnel can obtain ear protectors if they are exposed to this noise range and provide appropriate ear protectors to employees.

– LEP,d > 95 dB(A): Demarcate the area by providing warning signs and ear protectors for personnel protection, implement reasonably practical noise attenuation that can be applied to the works.

4.3 Health

Safety showers and eye-washers are placed at appropriate locations and a map is included within the safety regulations identifying them.


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4.4 Material Safety Data Sheets

Following Material Safety Data Sheets are included: 1. Sodium Carbonate Anhydrous 2. Sodium Carbonate Monohydrate 3. Celite Hyflo Supercel 4. Guar Gum 5. Antifoam 6. Nalco 19S Pulv Oxygen Scavanger 7. Nalco Transport-Plus 2801 8. Morpholine 9. Sodium Fluoride 10. Sodium Phosphate

Brunner Mond PO Box 4 Winnington Northwich Cheshire CW8 4DT Tel +44(0)1606 724000 Fax +44 (0)1606 781353 www.brunnermond.com

safety data sheet

SODIUM CARBONATE

Product Name : SODIUM CARBONATEChemical Name : Sodium CarbonateAlternative Name : Soda Ash – Light, Dense, Heavy, GranularChemical Formula : Na2CO3

Manufacturing Sites : Northwich East & West, DelfzijlCompany Address : Brunner Mond

PO Box 4 Mond House Northwich Cheshire CW8 4DT

Emergency Telephone Number : +44 (0) 1606 781000

• Sodium CarbonateCAS Number : 497 – 19 – 8EC Number : 207 – 838 – 8ID Number (Annex 1) : 011 – 005 – 00 - 2

• Irritating to eyes, respiratory tract and skin.

•

General• In all cases of doubt, or when symptoms persist, seek medical attention.

Inhalation• Remove to fresh air, keep warm and at rest.

Skin Contact• Remove contaminated clothing• Wash skin with plenty of water• Launder clothes before re-use

Eye Contact• Irrigate eye thoroughly with eye wash solution or clean water for at least 10 minutes.• Eyelids should be held away from the eyeball to ensure thorough rinsing.• Obtain medical attention if necessary.

Ingestion• DO NOT induce vomiting• Wash out mouth with water and give plenty of water to drink (at least 300 ml.)• Obtain medical advice if necessary.

1. IDENTIFICATION OF THE SUBSTANCE AND COMPANY

2. COMPOSITION/INFORMATION ON INGREDIENTS

3. HAZARDS IDENTIFICATION

4. FIRST AID MEASURES


safety data sheet

IDENTIFICATION/PRODUCT NAME : SODIUM CARBONATE (p.2)_______________________________________________________________________________________________

Flash Point• Not applicable

Extinguishing Media• All extinguishing products are allowed

Special Hazards• Non-combustible

Hazardous Decomposition Products (under fire conditions)• Not applicable

Personal Precautions• See personal protection measures given in Section 8

Environmental Precautions• Prevent discharges into the environment (rivers, water courses, sewers etc.)• See Section 13 for disposal details

Methods for clean up• Clear up spillages by suitable means avoiding dust formation• Collect as much as possible in a suitable clean container, preferably for re-use, otherwise for disposal.• Wash the spillage area with large quantities of water.

Handling• Avoid dust formation• Operate in a well ventilated area, atmospheric levels should be controlled in compliance with the

occupational exposure standard• Do not breathe dust• Avoid contact with skin and eyes

Storage• Store in a cool dry place ( in humid conditions the product will absorb moisture from the atmosphere and this

will eventually cause caking and loss of free flowing properties)• Do not store together with acids

Fire and Explosion Prevention• Non-combustible

Engineering Controls• Provide adequate ventilation• Avoid inhalation of dusts

5. FIRE-FIGHTING MEASURES

6. ACCIDENTAL RELEASE MEASURES

7. HANDLING AND STORAGE

8. EXPOSURE CONTROLS/PERSONAL PROTECTION


safety data sheet

IDENTIFICATION/PRODUCT NAME : SODIUM CARBONATE (p.3)

Occupational Exposure Limits• Not listed by H&SE (Guidance Note EH40) or ACGIH (Ref.UK EH40 – Limits for Nuisance Dust)

Recommended Limits: OES 10mg/m3 (total dust) (8hr TWA) 5mg/m3 (respirable dust) (8hr TWA)

Respiratory Protection• In the case of high dust levels wear suitable respiratory protective equipment, ie. dust mask or respirator

Hand Protection• Wear suitable chemical resistant protective gloves for frequent or prolonged operations

Eye Protection• Suitable eye/face protection

Skin and Body Protection• Protective clothing is required, overalls as a minimum

Appearance Powder, granules OxidisingProperties None knownColour White Vapour Pressure Not applicableOdour Odourless Specific Gravity 2.53Melting Point 851º c Bulk Density Light ash approx.

550kg/m3

Dense ash approx.1000kg/m3

Flash Point Not applicable Solubility in water 71 g/l @ 0º c471 g/l @ 32º c

Flammability Non flammable Solubility in other Solvents Not availableAuto ignition temp. Not applicable pH value 11.4 (1% w/w soln @20ºcExplosive properties None known Partition Coefficient

(n-octanol/water)Not applicable

Explosion Limits Not applicable Relative vapour density (air = 1) Not applicableViscosity Not applicable

Stability• Stable under recommended storage and handling conditions ( see Section 7)

Conditions to avoid• Contact with acids unless under controlled conditions• Contact with lime and moisture produces caustic soda• Humidity and moisture can cause caking of product

Materials to avoid• Aluminium and zinc• Fluorine• Sulphuric and other acids• Lithium• Phosphorus pentoxide

9. PHYSICAL AND CHEMICAL PROPERTIES

10. STABILITY AND REACTIVITY


safety data sheet


Hazardous decomposition products• Negligible, carbon dioxide gas can be emitted• Carbon dioxide is liberated on reaction with acids

Acute Toxicity• Oral LD 50, rat : 4090 mg/kg.• : Sodium carbonate is a permitted food additive, however in large doses corrosion of the mucous membranes of the gastrointestinal tract may occur.

• Inhalation LC 50, rat : 2300 mg/m3/2hr. : High concentrations of dust may irritate the nasal membranes and respiratory tract.

Eye Irritation• : Irritating to eyes• : May cause corneal damage, permanent damage is unlikely.

Skin Irritation• : May cause irritation• : Repeated and / or prolonged contact will remove natural grease resulting in dryness and cracking

Long Term Exposure• Prolonged or repeated inhalation of high dust concentrations may cause ulceration of the nasal septum,

which may in time progress to perforation or complete destruction of the nasal cartilage.

Other Toxicolgical Information• Not teratogenic

Acute Ecotoxicity• Fish, Lepomis macrochirus : 96hr - LC50 : 300mg/l• Daphnia magna : 48hr - EC50 : 265mg/l• Algae, Nitszcheria linearis : 5 day - EC50 : 242mg/l

Bio-degradeability• Aerobic/Anaerobic degradation Not applicable ( inorganic compound )

Product• Must be disposed in accordance with local, state or national regulations• Do not dispose of with acids

Packaging• Must be disposed in accordance with local, state or national regulations• Contact the manufacturer about recycling

• Not classified as hazardous for transport.

11. TOXICOLIGICAL INFORMATION

12. ECOLOGICAL INFORMATION

13. DISPOSAL CONSIDERATIONS

14.TRANSPORT INFORMATION


safety data sheet


• Land TransportADR Class Not restricted ADR item number Not relevantRID Class Not restricted RID item number Not relevantTREM-card Not relevant UN Number NoneHazard identification number None Substance identification number NoneProper shipping name None

• Sea TransportIMO/IMDG Not restricted Class Not relevantPacking group None UN number NoneEMS Not relevant MFAG Not relevantMarine pollutant NoProper shipping name Not relevant

• Air TransportICAO-TI/IATA-DGR Class Not restricted UN number NoneProper shipping name None Packing number None

• Sodium Carbonate is classified as irritant for supply and packages

EC Labelling• Chemical description : Anhydrous Sodium Carbonate

• Requirements according to Annex-1 of EC Directive 67/548/EEC

• Meets the requirements of CHIP

EC Number 207 – 838 – 8 Symbols Xi Irritant (R)isk phrase(s) R36 : Irritating to eyes (S)afety phrase(s) S22 : Do not breathe dust

S26 : In case of contact with eyes, rinse immediately With plenty of water and seek medical advice

National Legislation/Regulations• Water Hazard Class : WGK 1, VwVwS (Germany) of 17.05.1999, Annex 2• TSCA Inventory : Listed

The information only concerns the above mentioned product and is not necessarily valid if used with otherproduct(s) or in any process. It does not constitute a hazard assessment and should not be used in place of theuser’s own assessment of workplace risks as required by other health and safety legislation. The information is toour best present knowledge correct and complete and is given in good faith but without warranty.

The following sections contain revisions or new statements: 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15

Date of Issue : 21/10/2002 Revision: 03

15. REGULATORY INFORMATION

16.OTHER INFORMATION


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5 200 SECTION

5.1 Process description

5.1.1 Introduction

The washery serves to remove a large portion of impurities from the dredged trona, resulting in crushed refined soda (CRS). In this chapter the process of the washery is described. In order to have a complete picture also the OSBL dredging is described in this chapter.

5.1.2 Dredging (PFD 100-01, OSBL)

Refer to separate dredging operating manual for detailed operating instructions.

No.3 Dredger supplies ~50 tph solids to the existing soda ash plant

No.4 Dredger is shut down and provides a standby spare

No.5 Dredger provides ~200 tph solids which is enough to meet the new pure ash plant requirements and the shortfall between the requirements of the old soda ash plant and the output of No.3 Dredger.

5.1.3 Dredge product receiving and reclaim (PFD 200-01)

The dredged trona is transported to the upgrading facility (washery) in lake liquor slurry. The typical analysis of the solids is: 92% trona, 2% sodium fluoride, and 6% water insolubles. The insoluble impurities can be substantially rejected by size-based separation techniques. Sodium fluoride is not amenable to size-based separation. In the new washery, the dredged slurry will be fed to the agitated dredge product tank 200-TK-005 with a capacity of 120 m3. The slurry will be pumped by washery feed cyclone pump 200-PP-005/6 from the dredge product tank to the washery feed cyclone 200-CY-005, where a large portion of the fine muds (80%) and fine trona (10%) is removed. The underflow from the washery feed cyclone, containing 107 t/h of solids, will flow to the washery sieve bend screen 200-SN-020 which removes the >8 mm material. The cyclone overflow is collected in the washery feed cyclone overflow tank 200-TK-010 and pumped by the washery feed cyclone overflow pump 200-PP-010/011 to the tailings tank 900-TK-250. Part of this overflow is used as cooling brine for the second stage vent condenser 520-HX-020 (section 500). The overflow liquor is also used to collect ESP dust. For this purpose washery feed cyclone overflow pump 200-PP-012/011 pumps the


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overflow liquor to ESP dust conveyor 400-CV-040 where it picks up the ESP dust. From here the resulting slurry is returned to 200-TK-010. In the event that the dredge is unable to meet the solid feed requirements, a dry handling system will receive material from a front-end loader to allow feeding from a stockpile. The dredge product tank can also receive fines bank material. Trona and fines bank material will be reclaimed from the stockpiles by front-end loader with a maximum capacity of 115 t/h solids. The front-end loader discharges onto raw trona reclaim conveyor 200-CV-010 via the raw trona reclaim hopper 200-BN-010. Raw trona reclaim screen 200-SN-010 removes lumps >32 mm from the raw trona. The raw trona is further transported by raw trona undersize conveyor 200-CV-015 and slurried in the dredge product tank. Metal contamination is removed by magnet 200-MA-015, which is located on top of the undersize conveyor. Lumps are transported via raw trona oversize chute 200-CH-010 to the raw trona oversize bunker 200-ZC-015.

5.1.4 Classification and centrifugation (PFD 200-02)

Crushed Refined Soda (CRS) centrifuge centrate and CRS hydrocyclone overflow liquors are used as required to assist the transport of the solids across the washery sieve bend screen 200-SN-020. The screen oversize (> 8 mm) will be open-circuit crushed in feed delumper 200-CR-025 and then re-combined with the screen undersize, and fed by launder to the spiral classifier 200-CI-030. The spiral classifier further separates impurities by gravity settling. The incoming solids will contain an estimated 1.1 wt% insolubles. This will be reduced to about 0.4 wt% by the classifier. Operating at a separation size of 150-175 microns, the classifier will produce a 75 wt% solids product and overflow slurry containing about 1.3 wt% solids. The spiral classifier product will be delivered to the CRS wash tank 200-TK-030 or diverted via the classifier bypass conveyor 200-CV-030 to a stockpile if problems occur in the downstream equipment. The classifier is expected to reject 67% of the remaining insolubles, while recovering about 95% of the trona. No separation of sodium fluoride is allowed for in the classifier. A portion of the classifier overflow (255 m3/h) will be pumped to the tailings settler 200-TK-050 and flocculated. The tailings settler will produce about 250 m3/h of clear brine primarily for CRS wash tank density control. The coagulant, guar gum, is used to create flocks and promote settling in the tailings settler. Guar gum will be added as a 0.3 wt% solution at a dosage of 100 g/t of solids. The settler overflow pumps 200-PP-060/1 distribute the brine to the CRS wash tank, the washery sieve bend, the classifier discharge chute, the spiral classifier and the boiler scrubber. The settler underflow,


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containing 0.7 t/h of solids at 20 wt% solids density, will be pumped by tailings settler underflow pumps 200-PP-050/1 to the tailings tank 900-TK-250. The tailings settler overflow brine will dilute the spiral classifier product from 75% to 30% solids in the CRS wash tank. The tank, with a volume of 125 m3, will receive 110 t/h of solids and will provide about 30 minutes of surge capacity to smooth fluctuations in solids flow from the dredge. The CRS wash tank slurry will be pumped by CRS hydrocyclone feed pumps 200-PP-030/1/2 to CRS hydro-cyclones 200-CY-065/6. The hydro-cyclones provide further insolubles rejection, whilst pre-thickening the slurry to 60 wt% solids. The overflow from the hydro-cyclones is fed together with the CRS centrifuge centrate to the classifier by CRS centrate pump 200-PP-070/1. The underflow from the CRS hydro-cyclones is directed to the CRS centrifuges 200-CF-070/1. The centrifuges are designed to provide a 93 wt% solids cake. The cake will be washed with 2-4 displacements of process water to reduce the sodium chloride and insolubles. Centrate liquor will be pumped via the CRS centrate tank 200-TK-070 to the spiral classifier. The product CRS cake product will contain 5 to 6 wt% moisture with the following solids analysis: 97.5% trona, 2% sodium fluoride, up to 0.45% insolubles, and about 0.05% sodium chloride. The washery is sized to produce 104.3 ton/h dry base CRS. This will generate more CRS than the downstream equipment can process. It will therefore be necessary to continuously divert a portion of the CRS by CRS stockpile conveyor 200-CV-090 to Intermediate CRS stockpile 200-ZC-090. From this stockpile CRS is transported to CRS stockpile 200-ZC-040 by front end loader. CRS will be reclaimed from the stockpile as required. From conveyor 200-CV-090 running in opposite direction, CRS is transported via CRS conveyor 200-CV-075 to CRS conveyor 200-CV-080. CRS conveyor belt 200-CV-080 will transfer the CRS to the roller mill feed bin 200-BN-085. From this bin the CRS is fed to the roller mill (section 400) via roller mill belt weigh feeder 200-FD-085. Any metal contamination is removed by magnet 200-MA-080, which is located at the top of CRS conveyor 200-CV-080.


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5.2 Normal operation

5.2.1 Dredge product receiving (PID 200-02)

Dredge product tank 200-TK-005 normally receives trona slurry from dredge No. 5. This tank handles most of the product from this dredge. The excess is supplied to the existing plant. When the dredge is supplying only liquor then raw trona is fed via the dry reclaim system. In this case, the capacity is turned down to ~93 % of the design capacity because the dry reclaim capacity is 115 ton/h compared to 123.8 ton/h from the dredge. 200-TK-005 is provided with agitator 200-AG-005, which runs at fixed speed. The level in 200-TK-005 is measured by 200-LICSA-0101. The level is controlled by adjusting the slurry excess to existing plant, based on the signal from this indicator. Variations in flow will be small due to the way in which slurry is provided to 200-TK-005 by fixed speed pump from pumping tank located ~150 m away. The washery feed cyclone pump 200-PP-005/006 transports the trona slurry from 200-TK-005 to the washery feed cyclone 200-CY-005. 200-PP-005/006 are frequency controlled. The speed of the pumps is set by operator with 200-HIC-0001/0002. The speed of these pumps determines the capacity of the washery section. Because the density in this tank can vary considerably, an additional high level sensor 200-LSA-0102 and density measurement 200-DIA-0101 are installed.

5.2.2 Washery feed cyclones (PID 200-03)

Washery feed cyclone 200-CY-005 receives trona slurry from the washery feed cyclone pump. The underflow of this cyclone goes to washery sieve bend screen 200-SN-020 via washery sieve bend feed chute 200-CH-020. The cyclone has to be able to process a variable solids concentration feed. The solids concentration varies as a consequence of the dredge process. Also the cyclone has to be able to handle only liquor in case the dredge does not supply trona. This is done by an adjustable apex, adjusting the underflow via 200-HIC-0201. When properly installed the setpoint 0f 200-HIC-0201 does not need to be adjusted when there is a variation in solids concentration. This can be realized by providing a pressure controller on the air supply to the apex, which keeps the pressure at a set value. In this way the apex will automatically reduce the opening in case the solids concentration in the feed decreases and vice versa.


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The overflow goes to washery feed cyclone overflow tank 200-TK-010. The level in this tank is measured by 200-LICSA-0201. From this tank the thin slurry is pumped to vent condenser 520-HX-020 and tailings tank 900-TK-250. The flow to 520-HX-020 is controlled by the outlet temperature of 520-HX-020 and the flow to 900-TK-250 is controlled by the level of 200-TK-010. In addition the thin slurry is pumped to collect ESP dust. This flow returns to 200-TK-010 and is not controlled. This flow causes the tank content temperature to increase a few degrees Celsius and also increase in solids content. To prevent overheating and plugging, the ESP dust recycle has to be shut down when there is no feed of liquor from the cyclone.

5.2.3 Classification (PID 200-04)

Trona slurry is supplied to washery sieve bend screen 200-SN-020. Oversize particles (> 8 mm) are crushed in feed delumper 200-CR-025. The absorbed power of the delumper EI-I-0306 is displayed on the DCS. Classifier overflow liquor can be supplied to facilitate transport of solids through the screen and the crusher. Also settler overflow can be recycled to the washery sieve bend chute 200-CH-020. Slurry from the washery sieve bend screen and from the feed delumper is discharged into the primary classifier 200-CI-030. This classifier has a classifying screw. The following parameters can be adjusted by the operator to control the underflow concentration, separation efficiency of insolubles and cut size: – speed of the screw – height of the overflow weir – liquor flow rate. A higher overflow weir provides more time to settle and particles that flow over the weir are smaller. So this reduces the cut size. A higher liquor flow rate creates a higher overflow, less settling time, so increased cut size (more product loss). A higher screw speed increases turbulence and suspension of solids so better impurities separation but also more product in the liquor overflow and increased cut size.

5.2.4 CRS wash tank (PID 200-05)

Classified slurry is diluted in CRS wash tank 200-TK-030 with tailings settler overflow liquor from 200-PP-060/061. The flow of tailings settler overflow liquor is controlled by the slurry density within 200-TK-030 (200-DICSA-0401). This flow is switched off


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automatically (by closing 200-DCV-0401) when the level in 200-TK-030 200-LISA-0401 becomes high. This flow is restored automatically when the level reduces. At high high density or high level the supply of feed from the classifier is switched off automatically (classifier outlet is diverted to 200-ZC-030) and at low density or at low level the supply of classifier feed is restored automatically; see section 5.2.3. Classified slurry in 200-TK-030 is suspended by CRS wash tank agitator 200-AG-030, which is driven by 200-EM-0401. This drive is started and stopped locally by hand. The absorbed motor power is displayed on the DCS via EIA-I-0401, and an alarm is generated on the DCS if a high condition is reached. The CRS hydrocyclone feed pumps 200-PP-030/1/2 transport the CRS slurry from 200-TK-030 to the CRS hydrocyclones 200-CY-065/6. Each hydrocyclone is fed by a dedicated pump. 200-PP-031 acts as common spare pump. 200-PP-030/1/2 are frequency controlled. The speed of the pumps is adjusted by hand on DCS.

5.2.5 Classifier overflow (PID 200-06)

Overflow from the classifier is discharged into classifier overflow tank 200-TK-040. From this tank the brine is transported to deaerator 200-DE-050, dredge product tank 200-TK-005, washery sieve bend screen 200-SN-020 and the feed delumper 200-CR-025. The level in the overflow tank is kept between limits by controlling the flow to 200-TK-005. The flow to the deaerator is controlled by the level in tailings settler overflow tank. Liquor can be supplied to 200-SN-020 and 200-CR-025 by operation of a manual valve.

5.2.6 CRS hydrocyclones and centrifuges (PID 200-07)

CRS slurry is transported to CRS centrifuges 200-CF-070/1 via CRS hydrocyclones 200-CY-065/6. Process water is supplied to the centrifuge continuously to wash the cake. Centrifuges are offline flushed at a certain frequency. Centrifuge washing is described in section on deviating operating conditions. The centrifuges produce a de-liquored cake and centrate liquor.

5.2.7 CRS centrate (PID 200-08)

Centrate from centrifuges 200-CF-070/1 is collected in CRS centrate tank 200-TK-070. To reduce foam formation in the system emulsified silicone is dosed to the centrate tank by gravity flow. The flow rate of this is measured with 200-FI-0704 and the normal setpoint is provided on the setting list.


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Centrate is pumped from 200-TK-070 to the washery sieve bend feed chute 200-CH-020 by CRS centrate pump 200-PP-070/1. The flow is controlled by the level of the CRS centrate tank 200-LICSA-0701. At low low level the CRS centrate pumps are automatically tripped. In case the feed to both centrifuges is diverted back to the CRS wash tank 200-TK-030, pump 200-PP-070/071 has to be stopped, to prevent pumping against a closed head. Stopping the feed to both centrifuges has therefore to be avoided.

5.2.8 CRS stockpile reclaim (PID 200-09)

CRS coming from CRS centrifuges 200-CF-070/1 is collected on CRS centrifuge cake collection conveyor 200-CV-070 and transported to the roller mill or to an intermediate CRS stockpile via CRS stockpile conveyor 200-CV-090 (two-way conveyor). The moisture content of the CRS is monitored with a moisture analyzer 200-MIA-0801. In case of high moisture samples of each centrifuge cake are taken to determine which centrifuge is causing high moisture. CRS stockpile conveyor 200-CV-090 has two directions. At high level in the roller mill feed bin 200-BN-085 (200-LISA-0801), the direction is switched towards the intermediate CRS stockpile 200-ZC-090. The feed automatically switches back when the level is low. CRS conveyors 200-CV-075 and 200-CV-080 transport the CRS centrifuge cake to roller mill feed bin 200-BN-085. 200-CV-080 can also be fed by front end loader with CRS from the CRS stockpile 200-ZC-040 to CRS chute 200-BN-080 (see deviating process conditions). In case the level in 200-BN-085 is high (200-LISA-0801), the centrifuge cake will be diverted automatically to the intermediate CRS stockpile as described above. The capacity of the intermediate stockpile is approx. 20 tons, which gives approx. 10 minutes for full operating capacity of washery, starting with an empty stockpile. Roller mill feed bin 200-BN-085 has a total capacity for 60 minutes and is provided with level indication and low and high level switch 200-LISA-0801. A separate level switch 200-LA-0802 is installed above the high high level of 200-LISA-0801 (in case of failure of 200-LISA-0801). 200-LA-0802 generates an alarm and the operator has to take further action. From 200-BN-085 the CRS is transported to the roller mill by roller mill belt weigh feeder 200-FD-085. The transport of CRS is weighed and controlled by 200-FICA-0801, which adjusts the speed of 200-EM-0806. 200-FD-085 is started and stopped by the roller mill control system.


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5.2.9 Tailings settler (PID 200-10)

Classifier overflow liquor is mixed with guar coagulant in the tailings settler deaerator 200-DE-050, which transfers the mixed feed to tailings settler tank 200-TK-050. The flow of classifier overflow liquor is controlled by the level of the tailings settler overflow tank 200-LICSA-0902. The flow of guar supply is controlled with the speed of pump 510-MP-070/071 (see section 510). Process water supply to the deaerator has to be closed during normal operation. Tailings settler tank 200-TK-050 is equipped with tailings settler rake mechanism 200-TM-050. The settler rake motor (200-EM-0901) is provided with torque measurement EISA-I-0901. At high high torque a lifting mechanism is activated, which is hydraulically driven by the main drive. (See vendor’s operating procedures for further details on operating of lifting mechanism, e.g. lifting the rake manually for restarting after shut-down). The underflow from the tailings settler is pumped by 200-PP-050/051 to tailings tank 900-TK-250. Part of the underflow is recycled to the deaerator. The speed of these pumps is manually controlled by 200-HIC-0901/2. The operator adjusts the speed is based on the sludge level of the settler, given by 200-LI-0901. Setpoint for 200-LI-0901 is provided on the setting list. High level in the settler can mean a lot of sludge inside the settler, or poor separation (high turbidity). When turbidity is high, several vague discs are seen. When the level is high, the operator has to check the turbidity by sample and analysis and take the appropriate action. The overflow from the tailings settler is collected in the tailings settler overflow tank 200-TK-060. The level of this tank 200-LICSA-0902 controls the feed of classifier overflow to the settler. Tailings settler overflow pumps 200-PP060/1 pump the overflow liquor to washery sieve bend chute 200-CH-020, CRS wash tank 200-TK-030, to primary classifier 200-CI-030 and to boiler scrubber 900-DC-035. The flow to the CRS wash tank is controlled by the density within this tank. The flows to the sieve bend and to the classifier are controlled manually. The flow to the boiler scrubber is controlled in the boiler system.


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5.2.10 Setting list

Instrument Unit Normal Alarm Trip/Switch

200-DIA-0101 kg/m3 1380 L 1330

H 1430

200-DICSA-0401 kg/m3 1440 L 1390

H 1490

HH 1550

HH 1550

200-EIA-I-0101 kW 65 H 75

200-EISA-I-0301 kW TBD HH TBD HHTBD

200-EI-I-0306 kW TBD

200-EIA-I-0401 kW 73 H 85

200-EISA-I-0601/02 kW 50 H 63 HH 70

200-EISA-I-0901 kW check H TBD

HH TBD

HH TBD

200-FICA-0401/0402 m3/h 130 145 (check)

200-FICA-0601/02 m3/h 5.4 L 2.5

200-FI-0704 l/h 0.5

200-FICA-0801 kg/h 106700 101000

200-HIC-0201 % TBD

200-HIC-0301/02 RPM TBD

200-HIC-0901/02 RPM TBD

200-KIS-0601/0606 TBD TBD

200-LICSA-0101 % 90 LL 15

L 35

H 95

LL 15

200-LSA-0102 % HH 100 HH 100

200-LICSA-0201 % 90 LL 15

L 25

H 95

LL 15

200-LISA-0401 % 85 LL 15

HH 100

LL 15

L 60 (check)

H 95


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200-LICA0501 % 90 L 15

H 95

200-LSA-0603/0604 TBD TBD L TBD

200-LICSA-0701 % 90 LL 15

L 25

H 95

LL 15

200-LISA-0801 mm 1) LLL -1000

LL -500

HH 4000 (check)

LLL -1000

LL -500

L 1000

H 3100

200-LSA-0802 mm 2) HH 1600-3200 2)

200-LICSA-0902 % 90 LL 15

L 25

H 95

LL 15

200-LI-0901 mm 3) 2000 (4 discs

visible)

200-SSA-0001 L TBD L TBD








200-TISA-0601/0602 °C 55 H 60 HH 65

200-XISA-0601/0602 mm/s 6 H 9 HH 14

Guar 0.5% dosing g/ton solids 100

Purgerators on instrument

connections

l/h 20

Purgerators on pump seals l/h 50

1) as measured from bottom weld line of cylindrical section

2) Instrument can be mounted on different nozzles, ranging from 1600 to 3200 as measured from bottom weld

line of cylindrical section

3) as measured from bottom weld line of cylindrical section


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5.3 Logic functions

In this section the logic functions that act on equipment and the automatic actions of valves are described. Logical functions that act on equipment are for example: – Start conditions and running conditions – Process switches – Safety switches (dry run protection on pumps, speed alarm on conveyors) Also the way equipment can be started and stopped is provided in this table. This is apart from a thermal overload which is provided on all motors. The thermal overload shuts off the motor directly (hardwired from MCC). Logic functions acting on equipment:

Type Equipment/Action Start Stop Signal description

Start/

Running

condition

Switch/

Interlock

200-CV-010 Locally by

hand

Locally by

hand and

automatic

– 200-SN-010 in operation

– time delayed 200-SSA-0001

activated

– emergency stop 200-HZA-

0001 activated

– Misalignment 200-GA-0001

X

Stop

Stop

Alarm

200-SN-010 Locally by

hand

Locally by

hand and

automatic

– 200-CV-015 running X


hand

Locally by

hand and

automatic

– HH current on 200-EISA-I-

0101 of 200-AG-005

activated


activated


0002 activated


Stop

Stop

Stop

Alarm

200-AG-005 Locally by

hand

Locally by

hand

HH current 200-EIA-I-0101

activated

Alarm


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Start/

Running

condition

Switch/

Interlock

200-PP-005/006 Locally by

hand

Locally by

hand and

automatic

LL level of 200-LICSA-0101

activated

Stop

Dregde feed to

200-TK-005

HH level of 200-LSA-0102

activated

Divert to

wash-out

paddock

200-PP-

010/011/012

Locally by

hand

Locally by

hand and

automatic

LL level of 200-LICSA-0201

activated

Stop

200-CR-025 Locally by

hand

Locally by

hand

- - -

200-CI-030 Locally by

hand

Locally by

hand and

automatic

– Not valid: 200-GA-030 is

directed to 200-TK-030 and

density 200-DICSA-0401 is

high high


directed to 200-TK-030 and

agitator 200-AG-030 is out

of operation (time delayed)


directed to 200-ZC-030 and

200-CV-030 is out of

operation

X

X

X

200-GA-030

Drive to direction

of 200-TK-030

By hand

on DCS

and

automatic

By hand on

DCS and

automatic

– density 200-DICSA-0401 is

not high high

– level 200-LISA-0401 is not

high

– agitator 200-AG-030 is in

operation

X

X

X


low

– level 200-LISA-0401 is low

Start

Start

– limit switch 200-GBS-0301A

activated

Stop


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Start/

Running

condition

Switch/

Interlock

200-GA-030

Drive to direction

of 200-ZC-030

By hand

on DCS

and

automatic

By hand on

DCS and

automatic

– 200-CV-030 in operation X


high high

– level 200-LISA-0401 is high

– agitator 200-AG-030 is out

of operation

Start

Start

Start

– limit switch 200-GBS-0301B

activated

Stop


hand

Locally by

hand and

automatic


activated


0301 activated


Stop

Stop

Alarm

200-PP-

030/031/032

Locally by

hand

Locally by

hand and

automatic

– LL level of 200-LISA-0401

activated

Stop


hand

Locally by

hand

– - - -

200-CF-070./071 Locally by

hand

Locally by

hand and

automatic

– 200-CV-090 running

– HH current on 200-EISA-I-

0601/0604

X

Switch feed

to bypass


hand

Locally by

hand and

automatic

– LL level of 200-LISA-0701

activated

Stop


hand

Locally by

hand and

automatic

– 200-CV-090 in operation


activated


0801 activated


X

Stop

Stop

Alarm


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Start/

Running

condition

Switch/

Interlock

200-CV-090

Drive to direction

of 200-CV-075

By hand

on DCS

and

automatic

By hand on

DCS and

automatic

– 200-CV-075 in operation

– low level on 200-LISA-0801

– high level on 200-LISA-0801


activated


0807 activated


X

Start

Stop

Stop

Stop

Alarm

200-CV-090

Drive to direction

of 200-ZC-090

By hand

on DCS

and

automatic

By hand on

DCS and

automatic

– high level on 200-LISA-0801

– low level on 200-LISA-0801


activated


0807 activated


Start

Stop

Stop

Stop

Alarm


hand

Locally by

hand and

automatic


activated


0803 activated


Stop

Stop

Alarm


hand

Locally by

hand and

automatic


activated


0802 activated


Stop

Stop

Alarm

200-FD-085 Locally by

hand

Locally by

hand and

automatic

– 400-AL-010 in operation

– feed release signal from

roller mill package


activated


0806 activated

X

X

Stop

Stop


hand

Locally by

hand

– - - -

200-TM-050 Locally by

hand

Locally by

hand

– HH torque on 200-EISA-I-

0901

Lift rake


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Start/

Running

condition

Switch/

Interlock


hand

Locally by

hand and

automatic

– LL level of 200-LICSA-0902

activated

Stop

Automatic actions of valves: Valve Action Cause 200-LCV-0501 Close – HH level of 200-LSA-0102 200-XSV0601 Close – 200-CF-070 out of operation

– flushing of 200-CF-070

– 200-CV-070 out of operation

200-XSV-0602 Open – 200-CF-070 out of operation



200-XSV-0604 Close – 200-CF-071 out of operation



200-XSV-0605 Open – 200-CF-071 out of operation



Green light at 200-

BN-080

On – 200-LISA-0801 high switch is not activated

Red light at 200-

BN-080

On – 200-LISA-0801 high switch is activated


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5.4 Start up

5.4.1 Initial start up (with empty tanks)

For this procedure, the following assumptions are made: As a start condition all manholes/inspection holes are closed. – All tanks in the washery section are empty. – Utilities and auxiliaries are available and ready for use. The following utilities and

auxiliaries are required for this process section: • Process water • Purge water • Guar solution • Anti foam emulsion • Instrument air • Electrical power

– No.5 dredge is available, first providing a flow of brine containing few or no solids, for filling up the system and then providing slurry.

– Connections to tailings tank 900-TK-250 and the tailings tank itself have to be available for use

– If the settler is empty, a temporary connection to 200-DE-050 can be made from top outlet of 200-CY-005 or 200-PP-010/011/012. This is not included in the procedures described below.

In the procedure, first the tanks are filled with lake brine, containing few or no solids, from the dredge. When the system is filled up with brine liquor circulation is started and subsequently solids are introduced in the washery section. In detail, the procedure involves the following steps: 1 Check free rotation of all pumps. Check that all pump suction lines are closed.

Check that the discharge line of each pump is open, in order to keep purging with purge water and to prevent pressurizing the system and line damage. Pumps should be lined up as follows:

• 200-PP-005/06: flow to 200-CY-005 • 200-PP-010/11/12: flow to 200-TK-250 (check that bypass of 200-LCV-0201 is

closed), lines to 520-HX-010 and 400-CV-040 remain closed • 200-PP-030/31: flow to 200-TK-030 (via CRS slurry return)


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• 200-PP-040/41: flow to 200-TK-005 (check that bypass of 200-LCV-0501 is closed)and 200-DE-050 (check that bypass of 200-LCV-0902 is closed), lines to 200-SN-020 and 200-CR-025 remain closed

• 200-PP-050/51: flow to 900-TK-250 and bypass back to 200-DE-050. • 200-PP-060/61: flow to 200-TK-030 (check that bypass of 200-DCV-0401 is closed)

and 200 GA-030, lines to 200-CH-020, 200-CI-030 and 900-DC-035 remain closed • 200-PP-070/71: flow to 200-CH-020 (check that bypass of 200-LCV-0701 is closed)

2 Open all the purge water connections to instruments and pumps. Open also the process connections of these instruments at the same time and check if purges have the correct flow. Specifically for installed spare pumps: check that purge water can be discharged to a process connection.

3 Make sure all flushing connections are closed. 4 Check underflow of washery feed cyclone 200-CY-005 to be directed through

screen 200-SN-020 (by-pass is closed) 5 Start supply of lake brine (without solids) from the dredge to the dredge product

tank, 200-TK-005. 6 Start agitator 200-AG-005 when level is above 10% in 200-TK-005. 7 Check that cyclone bottom outlet (200-HCV-0201) is fully open and that diverter

200-GA-030 is directed towards 200-TK-030. (200-GBS-0301A active) 8 If level in 200-TK-005 is above 50 %, start feed pump 200-PP-005. Set pump speed

at … RPM. Enable level controller (200-LICSA-0101) of 200-TK-005. 9 Check that there is liquid flow to both 200-CH-020 and to 200-TK-010 10 When the level is above 50 % in 200-TK -010, start pump 200-PP-010. Enable level

controller (200-LICSA 0201) and adjust manually, so that a constant level is maintained in 200-TK-010. Switch to automatic level control when the tank is at normal level.

11 As soon as classifier starts to overflow, and sufficient liquid level is present in 200-TK-040 start 200-PP-040/041 with destination at deaerator 200-DE-050. Activate level control and adjust manually (LICSA-0501; check that bypass is closed), so that a constant level is maintained in 200-TK-040. Keep flow through 200-LCV-0501 as low as possible and preferably lead flow to 200-DE-050, while filling 200-TK-050.

12 Start guar metering pump 510-MP-070/071 and check guar dosing rate (refer to setting list).

13 Fill settler 200-TK-050. 14 When level in 200-TK-060 is above 25 %, start pump 200-PP-060/061. Open valves

to 200-GA-030 and to 200-TK-030 (200-DCV-0401), adjust 200-DCV-0401 manually. Activate level controller and adjust manually (200-LICSA 0902) in order to maintain constant level in 200-TK-060; maintain manual control until solids are added.

15 Start agitator 200-AG-030, when level is above 15 % in 200-TK-030.


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16 Check slurry discharge from 200-PP-030/031/032 is directed via cyclone bypass (200-XSV-0601 and 0604 closed and 200-XSV-0602 and 0605 open). Start two pumps of 200-PP-030/031/032. Check that flow is present at 200-FI-0401/02 and outlet of CRS recycle. Adjust flow by hand with 200-HIC-0402/03/04 in such a way that a constant level can be maintained in 200-TK-030.

17 Start 200-CV-090 in the direction of intermediate stockpile 200-ZC-090 18 Start-up centrifuge (oil system etc., start centrifuge; info from vendor) 19 Direct slurry to cyclone inlet (open 200-XSV-0601 and 200-XSV-0604 and close

200-XSV-0602 and 200-XSV-0605) 20 Check that 200-TK-070 is being filled from the cyclone overflow outlet and CRS

centrate outlet. As soon as sufficient level is present in 200-TK-070, start pump 200-PP-070/071. Activate level controller (200-LICSA-0701) so that a constant level in 200-TK-070 is maintained.

21 Switch level control 200-LICSA-0501 to automatic. 22 Provide liquor to boiler scrubber 900-DC-035 from 200-PP-060/061.

At this moment the washery section is filled with liquid completely and liquor circulation is

running. The next procedure can now be followed in order to deliver trona slurry from the

dredge.

23 Control liquor flow to sieve bend 200-SN-020 and crusher 200-CR-025 with manual

regulator valves. Start crusher 200-CR-025. 24 Open up feed to 200-CH-020 and 200-CI-030 from 200-PP-060/061 25 Start classifier screw. See supplier information for exact procedure. Check that 200-

GA-030 is directed towards 200-ZC-030 (GBS-0301B active). 26 Start 200-CV-075, direct 200-CV-090 to 200-ZC-090, start 200-CV-070 27 Provide washing water to centrifuges 200-CF-070/071. By adjusting the set point of

200-FICA-0601/02. 28 Start 200-PP-050. 29 Start taking in slurry from the dredge. 30 When classifier operates stable, divert 200-GA-030 towards 200-TK-030

(200-GBS-0301A active) Now slurry is flowing to the centrifuges, and the centrifuge cake is being diverted to

intermediate stockpile 200-ZC-090.

31 Make sure roller mill feed bin 200-BN-085 is ready for use. 32 If CRS from centrifuge is of good quality, start 200-CV-080 and 200-CV-075. Set

direction of 200-CV-090 towards 200-CV-075


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33 Weigh feeder 200-FD-085 to the roller mill section can be activated, when there is sufficient CRS in bin 200-BN-085 (200-LISA-0801 > L) and when there is a feed release signal from the roller mill section. When high level switch 200-LISA-0801 is activated, 200-CV-090 is set back into the direction of 200-ZC-090 again.

When washery is operating, following items should now be checked: 34 Activate automatic density control in 200-TK-030 and stop controlling DICSA-0401

manually. 35 Check that all automated level controls in tanks are on automatic. 36 Adjust flow of pumps 200-PP-030/31/32, if necessary. 37 Adjust slurry flow from 200-CY-005 (200-HCV-0201), if necessary. (depends on

particle size distribution) 38 Check sludge level in settler 200-TK-050 (200-LI-0901) and adjust settler underflow

pump 200-PP-050/051 if required. 39 Check position of manual gate on 200-BN-080 during CRS feed from stockpile (time

of emptying should keep pace with 200-BN-085) Before the mill and calciner section comes into operation, the following start-up sequence for the dust conveyor system applies. 40 Place setpoint of 200-LICSA-0201 to a high value. Check suction valve of spare

pump is closed 200-PP-010/011/012. Open suction valve and close discharge valve, start up 200-PP-011/012 and open discharge valve. Open flow to 400-CV-040 as fast as possible considering the level in 200-TK-010. ESP dust conveyor 400-CV-040 requires pressure, otherwise backflow can occur in ESP Dust Hopper 400-BN-040. (Note: The line volume is significant compared to the tank volume of 200-TK-010).

41 As soon as circulation line is filled, (return flow to 200 TK-010), put level control on normal setpoint and let system transport air for some time before adding dust.


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5.4.2 Normal start up, washery section (filled tanks)

This procedure differs from the case in section 5.4.1 in that all tanks in the washery are filled up already. For this procedure, the following assumptions are made: – All tanks in the washery section are filled with liquid. – Utilities and auxiliaries are available and ready for use. The following utilities and

auxiliaries are required for this process section: • Process water • Purge water • Guar solution • Anti foam solution • Instrument air • Electrical power

– No.5 Dredger is available, first providing a flow of brine containing few or no solids, for system start-up and thgen slurry for operation.

– Connections to tailings tank 900-TK-250 and the tailings tank itself should be available for use during the start-up procedures.

In the procedure, first liquid circulation is started up in the washery section. When the system is circulating, dredger slurry is introduced. In detail, the procedure involves the following steps: 1 Check free rotation of all pumps. Check that all pump suction lines are closed. 2 Check that the discharge line of each pump is open, in order to keep purging with

purge water and to prevent pressurizing the system and line damage. Pumps should be lined up as follows:

• 200-PP-005/06: flow to 200-CY-005 • 200-PP-010/11/12: flow to 900-TK-250 (check that bypass valve of 200-LCV-0201 is

closed), lines to 520-HX-010 and 400-CV-040 remain closed • 200-PP-030/31/32: flow to 200-TK-030 (via CRS slurry return) • 200-PP-040/41: flow to 200-DE-050 (check that bypass of 200-LCV-0902 is closed)

and to 200-TK-005 (check that bypass of 200-LCV-0501 is closed), lines to 200-SN-020, to 200-TK-005 and 200-CR-025 remain closed

• 200-PP-050/51: flow to 900-TK-250 and bypass back to 200-DE-050. • 200-PP-060/61: flow to 200-TK-030 (check that bypass of 200-DCV-0401 is closed)

and 200 GA-030, lines to 200-CH-020, 200-CI-030 and 900-DC-035 remain closed • 200-PP-070/71: flow to 200-CH-020 (check that bypass of 200-LCV-0701 is closed)

3 Check that all purge water connections to instruments and pumps are open and have the correct flow. Check also that the process connections of these instruments


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are open at the same time. Specifically for installed spare pumps: check that purge water can be drained to a process connection.

4 Make sure all flushing connections are closed 5 Start 200-PP-060/61. Adjust flow to 200-CH-020 manually. 6 Start pump of 200-PP-040/041. Adjust flow to 200-DE-050 manually (200-LICSA-

0902). 7 Start guar dosing (510-MP-070/71) and check guar dosing rate (refer to setting list). 8 Start 200-AG-005 and 200-AG-030 if stopped 9 Check slurry discharge from 200-PP-030/031/032 is directed via cyclone bypass

(200-XSV-0601 and 0604 closed and 200-XSV-0602 and 0605 open). Start 2 pumps of 200-PP-030/031/032. Check that flow is present at 200-FI-0401/02 and outlet of CRS recycle. Adjust flow with 200-HIC-0402/03/04 in such a way that a constant level can be maintained in 200-TK-030

10 Start 200-PP-070/71. Adjust level in 200-TK-070 by hand (200-LICSA -0701). 11 Start 200-CV-090 in the direction of intermediate stockpile 200-ZC-090 12 Start-up centrifuge (oil system, main drive etc.; info from vendor) 13 Direct slurry to cyclone inlet (open 200-XSV-0601 and 200-XSV-0604 and close

200-XSV-0602 and 200-XSV-0605) 14 Open 200-DCV-0401 and adjust flow. Close supply from 200-PP-060/61 to 200-CH-

020. 15 Start pump 200-PP-010/11. Adjust level (200-LICSA 0201), so that a constant level

is maintained in 200-TK-010. Check that cyclone bottom outlet (200-HCV-0201) is fully open.

16 Start 200-PP-005/006. 17 Start lake liquor brine intake from No5. dredger. 18 Check bypass valve of 200-LCV-0501 is closed. Adjust flow from 200-PP-040/41 to

200-TK-005 (200-LICA-0501). Now No5. dredger can start delivering trona slurry as described in procedure for initial start-up (see step 23 in section 5.4.1).

5.4.3 Restart from standby

The washery is on standby according to procedure 5.5.1 whilst the rest of the plant is in operation. Liquor is being supplied from the No5. dredger. 1 Start supplying trona from the dredge 2 After 10 minutes trona slurry arrives in 200-TK-005 (time will increase as No.5

dredger moves further from 200-TK-005). This can be monitored with the density meter 200-DIA-0101. Increase underflow opening 200-HIC-0201 of 200-CY-005.


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3 In case classifier is directed to 200-ZC-030, continue to do so until a stable operation of the classifier is reached.

4 Increase settler underflow pump 200-PP-050/051 speed to normal speed. 5 Divert classifier slurry to 200-TK-030. 6 Open washwater to centrifuges (200-FICA-0601/0602) 7 Reduce position of 200-DCV-0401 (still on manual). When the density inside

200-TK-030 is approaching its set point, switch 200-DCV-0401 to automatic. 8 Check CRS is being discharged from the centrifuges and that the moisture content

is OK. When sufficient CRS is being produced, front end loaders can stop CRS supply to the roller mill feed bin 200-BN-085.


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5.5 Shut down

5.5.1 Going to standby

Solids supply from No5. dredger is stopped and liquor supply continues in order to keep the rest of the plant in operation. 1 Stop solids supply from the dredge. 2 After 10 min. the solids concentration of the dredge product decreases

(200-DIA-0101. Opening of 200-HCV-0201 decreases automatically as the solids concentration of the cyclone feed decreases.

3 For the pumps 200-PP-005/006 and 200-PP-010/011/012 there is no change in operation.

4 When the classifier is empty of solids, reduce speed of 200-PP-050/051 to minimum 5 The liquor for the boiler scrubber continues. Liquor supply from cyclone 200-CY-005

and wash water from centrifuges supply this amount. Adjust position of 200-HIC-0201 to allow sufficient liquor passing through the underflow outlet.

6 When cake supply from centrifuges decreases, start CRS supply to 200-BN-080 from CRS stockpile in order to keep the rest of the plant working (see procedure CRS reclaim, section 5.7.3)

7 Solids concentration inside 200-TK-030 decreases. Take 200-DICSA-0401 on manual and control the level with the supply of liquor and the speed of 200-PP-030/031/032.

8 Slurry from CRS wash tank is gradually washed out towards the centrifuge. Eventually, when there are no more solids in the classifier and 200-TK-030, process water supply to the centrifuges can be stopped. Liquor circulation continues

5.5.2 Normal shut down of washery

In case the rest of the plant remains in operation, the solids supply from the dredge is stopped and liquor supply is maintained. Dredge product tank 200-TK-005 and washery feed cyclone overflow tank 200-TK-010 with corresponding pumps and cyclone are kept running. With liquor supply to 200-TK-010 started via bypass line, also 200-TK-005 with corresponding pump can be stopped. CRS is reclaimed from CRS stockpile 200-ZC-040 and supplied to the weigh feeder system. In this way the ESP fines conveying system and crystallization section can continue running. However, when the washery circulation system is shut down, liquor supply to the boiler scrubber has to be shut down when 200-TK-060 is empty (approx. 1 hour buffer). This has to be checked with operating procedures of the boiler scrubber.


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At the end of this procedure, the shut down of dredge product tank and overflow tank is described. 1 Stop solids supply from the dredge and or dry reclaim and maintain liquor supply. 2 After approx. 10 minutes only liquor is fed to 200-TK-005 (time will change with

position of dredge). Reduce position of 200-HIC-0201. 3 Switch 200-DCV-0401 to manual control and keep level in 200-TK-030 constant 4 When classifier 200-CI-030 is empty of trona, stop screw drive. 5 Start feeding CRS from stockpile to 200-BN-080 (see CRS reclaim, section 5.7.3) 6 When 200-TK-030 is empty of trona, stop centrifuges 200-CF-070/71 (procedure

from vendor) and stop process water supply (200-FICA-0601/02) 7 Underflow valve 200-HIC-0201 of 200-CY-005 closes automatically when no more

solids are supplied to the cyclone. 8 Stop 200-PP-050/51. 9 Stop 200-PP-030/31/32 and 200-AG-030 if required. 10 Stop 200-PP-070/071. 11 Stop 200-CR-025. 12 Stop 200-PP-060/061 when low level in 200-TK-060 (this will stop liquor supply to

boiler scrubber). 13 Stop Guar supply (510-MP-070/71). 14 Stop 200-PP-040/041. 15 Stop 200-CV-070, 200-CV-090, 200-CV-075. 16 Start flushing lines (particularly slurry lines) as soon as possible after stopping a

pump. 17 If settler remains full, keep rake mechanism 200-TM-050 running. 18 When done, keep all purgewater to instrument connections open and running.

If the rest of the plant (section 400 to 800) remains in operation and 200-TK-005, 200-AG-005, 200-PP-005/006 or 200-CY-005 has to be taken out of operation, than the liquor bypass to 200-TK-010 can be used: 19 Open bypass line to 200-TK-010 20 Close liquor feed to 200-TK-005 When the rest of the plant is shut down, liquor flow from dredge can be stopped and the intake part of the washery can be stopped: 21 Calciner section and other down stream units are stopped. Stop 200-CV-080 and

roller mill belt weigh feeder 200-FD-085 22 Stop dust supply to 400-BN-040 (400 section) and stop 200-PP-011/012 23 Stop liquor supply from dredge to 200-TK-005 24 Stop 200-PP-005/006 (and 200-AG-005 if required)


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25 Stop 200-PP-010/11


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5.5.3 Maintenance shutdown of washery

When the washery needs to be shut-down and drained, first the solids supply from the dredge is stopped. Liquor is supplied continuously until all trona is washed out of the slurry tanks 200-TK-005/030 and the classifier. Then the tank levels of the largest tanks (200-TK-005, 200-TK-030 and 200-TK-060) can be reduced if needed in case of draining. At the end of this procedure liquor supply from the dredge is also stopped, which can only be done if calciner section and crystallization section are shut down as well. 1 Stop solids supply from the dredge and or dry reclaim system and maintain liquor

supply. 2 After approx. 10 minutes only liquor is fed to 200-TK-005. Reduce position of 200-

HIC-0201 3 Switch 200-DCV-0401 to manual control and keep level in 200-TK-030 constant 4 Divert 200-GA-030 to 200-ZC-030 5 When classifier 200-CI-030 is empty of trona, stop screw drives. 6 When 200-TK-030 is empty of trona, stop centrifuges 200-CF-070/71(procedure

from vendor) and stop process water supply (200-FICA-0601/02) 7 Reduce level in 200-TK-005 (set point 200-LICSA-0101) 8 The opening of 200-HIC-0201 reduces automatically, which reduces the level in the

washery. 9 Stop roller mill belt weigh feeder 200-FD-085 10 Stop dust supply to 400-BN-040 (400 section) 11 Stop 200-PP-060/061 (stop liquor supply to boiler scrubber) 12 Stop liquor supply from dredge. 13 Stop 200-PP-005/006 and 200-AG-005 14 Stop 200-PP-010/11/12 15 Stop 200-PP-050/51 16 Stop 200-PP-030/31/32 and 200-AG-030 17 Stop 200-PP-070/071 18 Stop 200-CR-025 19 Stop Guar supply (510-MP-070/71) 20 Stop 200-PP-040/041 21 Stop 200-CV-070 , 200-CV-090, 200-CV-075, 200-CV-080 22 Start flushing lines as soon as possible after stopping a pump 23 Settler remains full. Keep rake mechanism 200-TM-050 running. 24 Tanks can be drained as required. Drained liquor is collected in the sump

200-SU-090. Pump capacity of 200-PP-090 is 35 m3/h. 25 Keep purgewater to instrument connections open and running as far as possible.


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5.6 Operator actions, periodic checks

5.6.1 Line flushing to prevent settling in lines

Especially for vertical slurry lines with high concentration (200-PP-005/6, 200-PP-030/031) the line has to be flushed as soon as possible after the pump has been stopped. Flush the line in top-down direction. Connect wash water via a hose to a flushing connection on the line and open valve fully. Open a drain valve to a safe location. The amount of flush water to be used is approx. 3 times the line volume. After flushing, close the flushing line valve and disconnect the hose. For pumps, close suction valve, and leave discharge valve open, in order to provide a way-out for purge water on the pump seals.

5.6.2 Tank cleaning to remove scale formation

The open tanks need to be checked periodically to detect growth of crusts of scale on tank wall, agitator shafts etc. which will have to be washed away. This is especially expected on Dredge product tank (200-TK-005), Washery feed cyclone overflow tank (200-TK-010) and CRS wash tank (200-TK-030).

5.6.3 Checks

– Check purge flow rates instruments are set according to the required setting (see setting list).

– Check centrifuge cake visually on 200-CV-070 for high moisture – Check pump seals:

• Purge flow rate is set according to setting list • Check that water is dripping from the seal. If no dripping is visible or if a continuous

flow is visible, maintenance attention by a qualified person is required. – Check liquor flow to sieve bend 200-SN-020 and crusher 200-CR-025 are right – Check sump 200-SU-090 (e.g. automatic level switch 200-LSA-0402)


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5.6.4 Critical process parameters

Location Parameter Tag or analysis Target / setpoint

200-PP-005/006 Pump speed 200-HIC-0001/0002 TBD

200-TK-005 Density 200-DIA-0101 1350-1400 kg/m3 (15-

20 wt%)

200-CY-005 Cyclone underflow solids

concentration

Sample (SC207) 60 wt%

200-CY-005 Cyclone overflow solids

concentration and particle

size

Sample (SC206)

3 – 4 wt%

max. size 120 µm

200-CI-030 Classifier feed solids

concentration


200-CI-030 Classifier underflow solids

concentration and free

insolubles (organics)

Sample (SC209)

75 wt%

0 wt%

200-CI-030 Classifier overflow solids

concentration and particle

size

Sample (SC211)

2 wt%

D90 cut size 175 µm

200-TK-030 Density 200-DICSA-0401 1440 kg/m3 (30 wt%)

200-PP-030/031/032 Pump speed 200-HIC-0402/0403/0404 TBD

200-TK-050 Settler sludge level 200-LI-0901 4 discs visible

510-MP-070/071 Settler guar supply Calibration tube 100 g/ton solids

200-TK-050 Settler overflow solids

concentration

Sample (SC216) < 0.1 wt%

clean

200-TK-050 Settler underflow solids

concentration


200-CF-070/071 Cake moisture 200-MI-0801 and Sample < 6 wt%

200-CF-070/071 Centrifuge wash water flow

rate

200-FICA-0601/0602 5 m3/h

5.6.5 Sampling and analyses

See Analytical Manual.


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5.7 Deviating operating conditions

5.7.1 Turn down capacity

The plant design incorporates a turn down capacity of 50 %. This is an exceptional situation and should only occur when one centrifuge is out of operation for a prolonged period of time. During this scenario, the dredge has to supply a normal amount of liquor, but reduced amount of solids. Alternatively, the dredge supplies a normal amount of solids and the excess solid is diverted to the classifier discharge bunker 200-ZC-030. The automated controls are designed for operating at turn down capacity. The procedure below describes the capacity reduction from normal capacity to 50% of the capacity. 1 Adjust slurry flow through washery feed cyclone underflow control 200-HCV-0201 2 Keep one centrifuge operating. Stop one feed pump (200-PP-030 or 031 or 032)

Stop one centrifuge and flush the centrifuge. After flushing: stop process water flow to the centrifuge. Flush the discharge line to the cyclone that has been stopped.

3 Adjust flow of antifoam and guar (depending on the expected duration of the turn down situation)

4 Adjust the speed of settler underflow pump 200-PP-050/51 in such a way that the sludge level stays correct.

5.7.2 Dry reclaim

5.7.2.1 Process description (PID 200-01)

The dry reclaim route can be used when No.5 dredger does not supply trona to 200-TK-005. The washery is designed for 115 ton/h from dry reclaim route. A front end loader supplies 1.7 or 3.7 m3 raw trona at a time, so number of front end loadings is approx. 68 or 33 per hour. Material from the fines bank can be supplied to the washery via dry reclaim route. Fines are allowed at 10% maximum of the total feed, which is 12.4 ton/h (approx. a front loader every 8 minutes). Depending on the actual performance of the washery, the dredge solids feed has to be reduced by approx 9 ton/h (a front end loader each 11 minutes) in order to operate within the design conditions. In this way a relatively constant feed of solids is supplied to dredge product tank 200-TK-005. Oversize fraction screening section is also collected on the raw trona stockpile.


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Above raw trona undersize conveyor 200-CV-015 a magnet 200-MA-015 is installed. This magnet has to be inspected periodically and cleaned. If the magnet has to be removed for cleaning, then raw trona / fines bank supply MUST be stopped until the magnet is back in place. Make sure the magnet is positioned correctly, otherwise it will not effectively catch metal parts in the raw / trona fines bank feed. Raw trona reclaim conveyor 200-CV-010 transports the dry feed, which is delivered by front-end loader to raw trona reclaim hopper 200-BN-010, to raw trona reclaim screen 200-SN-010. Raw trona reclaim screen 200-SN-010 rejects lumps larger than 32 mm to raw trona oversize chute 200-CH-010. Smaller particles are allowed to pass the screen to raw trona undersize conveyor 200-CV-015. Raw trona undersize conveyor 200-CV-015 transports the smaller particles to dredge product tank 200-TK-005.

5.7.2.2 Operating procedure

In the dry reclaim case, the liquor inlet from the dredge into dredge product tank 200-TK-005 remains open. There is no solids supply from the dredge, therefore trona supply will be started from stockpile 200-ZC-010. For starting solids supply via the dry reclaim route the following steps are required: 1 Raw trona undersize conveyor 200-CV-015 is started. 2 Raw trona reclaim screen 200-SN-010 is started. 3 Raw trona reclaim conveyor 200-CV-010 is started. 4 Raw trona from stockpile 200-ZC-010 is supplied by front loader to reclaim hopper

200-BN-010. The rate at which solids are added is to be controlled by the front end loaders.

The speed of the conveyors is fixed and is designed for 115 ton/h. The manual gate of the raw trona reclaim hopper has to be opened sufficiently to have the bin emptied in between front end loader loadings. The output flow of the washery is measured on 200-FICA-0801. The density in the dredge product tank 200-TK-005 as read on 200-DIA-0101 has to be checked to ensure the correct amounts of liquor and solid are being added, see setting list. When returning to the normal operating situation, execute by stopping the equipment in step 1 to 4 in reverse order.


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If high level switch 200-LSA-0102 HH in 200-TK-005 is activated, then stop dry reclaim route.

5.7.3 CRS reclaim

CRS conveyor 200-CV-080 transports the CRS centrifuge cake to roller mill feed bin 200-BN-085. 200-CV-080 can also be fed by front end loader with CRS from the CRS stockpile 200-ZC-040 to CRS chute 200-BN-080. For a feed of 107 ton/h of CRS, front end loadings are required once per minute for the 1.7 m3 front end loader, and once per two minutes for the 3.5 m3 front end loader. Check position of manual gate in order to empty BN-080 sufficiently fast. Two colored lights at 200-BN-080 inform the operator when to load CRS into 200-BN-080: – Green light: 200-LISA-0801 H(S) is not activated: start supplying CRS – Red light: 200-LISA-0801 H(S) is activated: stop supplying CRS

5.7.4 Centrifuge flushing

During normal operation, the flushing of the centrifuges with process water is necessary at a certain frequency. Centrifuge flushing is activated via a timer switch (200-KIS-0601 and 0606), which activates flush water supply (open 200-KSV-0603 or 200-KSV-0606). Flushing is stopped again by the same switch. Only one centrifuge can be flushed at a time. When flushing centrifuge 200-CF-070 the slurry flow to hydrocyclone 200-CY-065 is redirected to the CRS wash tank by opening 200-XSV-0602 and closing 200-XSV-0601 (pump remains in operation). When the slurry is redirected the flush valve 200-KSV-0603 is opened. When flushing is complete 200-KSV-0603 is closed, 200-XSV-0601 is opened and 200-XSV-0602 is closed. In the same way when flushing centrifuge 200-CF-071 the slurry flow to hydrocyclone 200-CY-066 is redirected to the CRS wash tank by opening 200-XSV-0605 and closing 200-XSV-0604 (pump remains in operation). When the slurry is redirected the flush valve 200-KSV-0606 is opened. When flushing is complete 200-KSV-0606 is closed, 200-XSV-0604 is opened and 200-XSV-0605 is closed. If the density in 200-TK-030 becomes too high, the classified slurry is diverted to 200-CV-030 automatically. If the slurry is diluted sufficiently again, 200-GA-030 is set in the direction of 200-TK-030 automatically (see section 2.3.3).


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If the level in 200-TK-030 becomes too high, 200-DCV-0401 is closed. Control valve 200-DCV-0401 is automatically opened when the level has reduced (see section 2.3.4).

5.7.5 Shut down in case of failure of liquor supply from the dredges

Failure of liquor supply from the dredge results in shut down of liquor supply to the ESP fines conveying system and the crystallizer vent condenser. This means a total plant shut down. If the liquor supply to the ESP fines conveying system is running without supply of liquor from the cyclone, the temperature will increase and the solids will accumulate. For the washery, the procedure is described in this section. If liquor from the dredge fails, dredge product tank 200-TK-005 and washery feed cyclone overflow tank 200-TK-010 with corresponding pumps and cyclone are shut down. The remaining washery section can remain in circulation for short duration outages. For prolonged shut-down, the circulation can be stopped. 1 Put calciner on standby (unit 400) and stop weigh feeder 200-FD-085. 2 Other units further down stream go to standby 3 Stop ESP fines supply to 400-BN-040 (unit 400) 4 When level in 200-TK-005 is low, stop 200-PP-005/006 and 200-PP-010/11/12 5 Put washery on standby (see section 5.5.1) 6 When level in 200-TK-060 is low, provide additional process water to the system to

keep feeding the boiler scrubber, or stop 200-PP-060/061 This is the stage where the washery runs in stand-by mode: i.e. full circulation, no feed and no CRS delivery. Slurry from CRS wash tank is gradually washed out towards the centrifuge. The liquid loss has been minimized. In case of a longer failure, the washery can be shut down (see section 5.5.2).

5.7.6 Failure of dredge product tank 200-TK-005 or related equipment (bypass of 200-TK-005)

A failure of one of the elements of the dredge product tank system results in interruption of slurry supply to washery and liquor supply to the calcination and crystallization. In order to be able to continue operation of the calcination and crystallization sections a bypass line from the dredge feed line to 200-TK-010 is provided. The procedure below applies to a sudden severe failure that requires immediate interruption of slurry supply from the dredge. If the dredge product system shutdown is scheduled, then skip first steps and proceed with step 5.


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1 Open valve to wash-out 2 Close inlet valve to 200-TK-005 3 Take second stage crystallization to standby (500 unit) 4 Stop ESP dust supply to 400-BN-040 (400 unit) 5 Make sure only liquor is being supplied from the dredge product line 6 Open bypass valve to 200-TK-010 7 Dump sufficient surplus of liquor at the dredge product tank washout valve ensuring

that the supply of liquor to 200-TK-010 is in balance with the capacity of 200-PP-010/011/012. The amount dumped will vary depending upon where the liquor is being provided from. The separate lake liquor pump provides ~420 m3/h whilst the dredge pump provides ~750 m3/h.

8 Re-start second stage crystallization (500 section) 9 Re-start ESP fines to 400-BN-040 (400 section) 10 Put washery in standby mode (see section 5.5.1) 11 When level in 200-TK-060 is low, provide additional process water to the system to

keep feeding the boiler scrubber, or stop 200-PP-060/061 This is the stage where the washery operates in stand-by mode: i.e. full circulation, no feed and no CRS delivery. Slurry from CRS wash tank is gradually washed out towards the centrifuge. The liquid loss has been minimized. In case of a longer failure, the washery can be shut down (see section 5.5.2).

5.7.7 Classifier not available

In case classifier 200-CI-030 is not available, there are two ways to proceed: – Interrupt slurry supply from dredge to 200-TK-005 – Allow continuation of slurry feeding to the classifier In the first scenario, second stage crystallization has to go on standby and ESP fines supply to washery have to be interrupted until the dredge supplies only liquor to 200-TK-005. In the second scenario there is no disturbance of the down stream process, but more cleaning of classifier area is required.

5.7.8 CRS cyclone or centrifuge not available

In case the route from CRS wash tank 200-TK-030 to conveyor belt 200-CV-090 can not be used for some reason the following procedure applies: 1 Put washery in standby mode (section 5.5.1) 2 Start feeding CRS to 200-BN-080 (see procedure CRS reclaim 5.7.3)


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3 Divert classifier slurry to bunker 200-ZC-030 4 Stop 200-PP-030/030/031 5 Stop wash water supply on centrifuges 6 Stop centrifuges (see procedure from vendor) 7 Flush lines 8 Open liquor line from 200-PP-060/061 to 200-CH-020 9 Stop 200-PP-070/071 10 Balance liquor feed from cyclone 200-CY-005 underflow with liquor supply to boiler

scrubber 900-DC-035.

5.7.9 Diverting classified slurry to classifier discharge bunker 200-ZC-030

The classified slurry is directed normally to CRS wash tank 200-TK-030. The slurry is diverted to bunker 200-ZC-030 in the following cases: – High level or density in tank 200-ZC-030 – tank 200-TK-030 or subsequent equipment is out of operation – CRS from centrifuge is out of specification and is not suitable as feed to calciner or

CRS stockpile. Diverted classified slurry is transported by classifier bypass conveyor 200-CV-030 to the classifier discharge bunker 200-ZC-030. Apart from disturbances as described above, the classifier discharge bunker can be used to collect washed trona in the following cases: 1 One centrifuge in operation (for example extensive centrifuge cleaning) 2 In case both centrifuges are temporarily not running, during start-up or shut down

operation The capacity of the stockpile is 100 ton. The feed rate at 50% capacity is approx. 75 ton/h, and at 100% capacity 150 ton/h. So the buffer time when starting with an empty bunker is 1.5 hours at 50% capacity and 45 minutes at 100% capacity. The content of the stockpile has to be transported to the raw trona reclaim hopper 200-BN-010, or to the raw trona stockpile 200-ZC-010 if the dry reclaim route is not in operation. During normal operation conveyor 200-ZC-030 is not needed and is therefore not running. When the slurry needs to be diverted to stockpile 200-ZC-030, the conveyor belt is started, and subsequently the diverter 200-GA-030 can be activated. As the diversion of slurry to the stockpile is expected to be for a limited time, the dredge supply and washery remain in operation.


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5.7.10 Lifting of classifying screw

Next to the main drive the classifying screw has a separately driven lifting device. In this way the classifier spiral can be easily raised for start-up, shut-downs and periodic inspections or maintenance. The drive 200-EM-0304 can be started and stopped locally by hand. At high power consumption 200-EISA-I-0301 the screw is lifted automatically.

5.7.11 Plugging of washery sieve bend screen 200-SN-020; use of by-pass

In case the screen is plugged, the slurry feed can be diverted via a by-pass route allowing the screen to be cleaned. A consequence of using the by-pass is that the slurry is no longer screened and particles larger than 8 mm are forwarded to the classifier and centrifuge. The centrifuge is designed for particles up to 8 mm and larger particles can cause plugging. Therefore, if the by-pass is used, then the slurry from the classifier has to be diverted to the stockpile to prevent plugging of the centrifuge. Furthermore, severe plugging of the screen can cause the screen to overflow and more liquor will proceed to the crusher 200-CR-025, and power consumption will increase. An alarm is generated when this happens alerting the operator to this issue.

5.7.12 Centrifugal pump start/stop and changeover

5.7.12.1 Centrifugal pump start/stop

The general procedure for a normal start and stop is described here. For switching over from running to spare pump, see procedure below section 5.7.12.2. This is applicable for centrifugal pumps. For positive displacement pumps refer to procedure in section 5.7.13. Start of pump 3 Open purge water supply shut-off valve and check flow rate (drain valve or

discharge or suction valve MUST be open to have flow of purge water) 4 Check the valves in the discharge line of the pump is set up for the right destination 5 Check suction and/or discharge valve of spare pump is closed. 6 Close drain valve and open suction valve (if pump is empty allow to fill up by venting

on discharge side of the pump). 7 Check discharge valve is closed, start pump and open discharge valve. Stop pump 8 Close discharge valve and stop pump. 9 Close suction valve.


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10 Open flush valve on discharge line upstream of discharge valve, open discharge valve and flush through discharge valve.

11 Close discharge valve and open suction valve and flush through suction valve. 12 Close suction valve, open drain valve and close flush water valve. 13 Drain pump and leave drain valve open. 14 Close purge water shut-off valve.

5.7.12.2 Use of installed spare pump

For most application an installed spare pump is provided. This can be used in case of failure or maintenance of the running pump or for routine pump changeovers. Separate procedures are provided for each of the above. The procedure applies to centrifugal pumps. See procedure in section 5.7.13.2 for positive displacement pumps. Procedure in case running pump has failed: 15 Close discharge valve of the pump that failed and put local switch in off position. 16 Open purge water supply shut-off valve and check flow rate (drain valve or

discharge or suction valve MUST be open to have flow of purge water) 17 Close drain valve and open suction valve of spare pump (if pump is empty allow to ill

up by venting on discharge side of the pump). 18 Check discharge valve is closed, start spare pump and open discharge valve 19 For maintenance, flush and drain pump that failed as described in section 5.7.12.1. Procedure to changeover with running pumps: 20 Open purge water supply shut-off valve and check flow rate (discharge or suction

valve MUST be open to have flow of purge water) 21 Check discharge valve of spare pump is closed, close drain valve and open suction

valve (if pump is empty allow to fill up by venting on discharge side of the pump) 22 Start spare pump and open discharge valve. 23 Close discharge valve of the original running pump and stop the pump. 24 Flush and drain pump as described in section 5.7.12.1. Note 1: As soon as the running pump is stopped, backflow can occur (there are no check valves installed). Therefore, first close discharge valve of the running pump and then stop this pump. Note 2: Close the purge water supply before the pump is isolated, to prevent high pressure in pump and piping.


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5.7.13 Start/stop and changeover of 200-PP-050/051

5.7.13.1 Start/stop of 200-PP-050/051

The general procedure for a normal start and stop is described here. For switching over from running to spare pump, see procedure below section 5.7.13.2. This is applicable for 200-PP-050/051. For centrifugal pumps refer to procedure in section 5.7.12. The pump has to be filled to provide lubrication of the stator (not for priming purpose). When the pump is stopped sufficient liquid is normally trapped between the pumping elements to provide the necessary lubrication for restarting. However, if the pump has been left standing for a long time or has been dismantled, it must be refilled and given a few turns before starting, to get sufficient lubrication between the rotor and the stator. Start of pump if line and pump are empty: 1 Fill up suction line (open bottom valve of settler and drain valve at pump suction) 2 Fill up pump with water hose via plug on top of the pump and give it a few turns with

provided tool If line and pump are full, proceed with: 1 Check purge water supply is open and check flow rate (discharge or suction valve

has to be open to have flow of purge water) 2 Check the valves in the discharge line of the pump are set up for the right

destination 3 Check discharge valve of spare pump is closed. 4 Open suction and discharge 5 Start pump Stop pump 1 Keep pump running during flushing. Connect process water hose on suction flushing

connection and open flush valve. 2 Close valve in suction line and flush through pump and discharge valve. 3 Stop pump and close discharge valve. 4 Open suction valve and flush through suction valve. 5 Close flush valve and keep suction valve open to allow purge water to flow through

the seal. Note 1: Never run the pump dry, not even for a few revolutions. Note 2: Never run pump with a closed suction or discharge valve. Note 3: Do not vary the flow rate by throttling suction or discharge valve


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5.7.13.2 Use of installed spare 200-PP-050/051

An installed spare pump is provided. This can be used in case of failure or maintenance of the running pump or for routine pump changeovers. Separate procedures are provided for each of the above. The procedure applies to 200-PP-050/051. See procedure in section 5.7.12 for centrifugal pumps. Procedure in case running pump has failed: 1 Close discharge valve of the pump that failed and put local switch in off position. 2 Open suction and discharge valve of spare pump 3 Start spare pump 4 For maintenance, close purge water supply and flush the pump and the enclosed

suction and discharge line sections. Procedure to changeover with running pumps. 1 Open suction valve and discharge valve of spare pump and start spare pump 2 Keep pump running during flushing. Connect process water hose on suction flushing


the seal. Note 1: Backflow does not occur when the running pump is stopped for positive

displacement pumps Note 2: Close the purge water supply before the pump is isolated to prevent high

pressure in pump and piping.


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5.7.14 General procedure for belt conveyor

Start-up Before starting the belt conveyor check for foreign objects, no personnel are near the belt, alignment, and that no safety interlocks activated. Start the belt with the local on/off switch Shut down: If possible the conveyor should be completely discharged before shutting down.


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5.7.15 Trouble shooting table controls of 200-TK-030

Because various control loops play role in this section, a trouble shooting table is included. This table refers to section 5.2.3 and 5.2.4.

Event Automated action Cause Recovery action

200-LISA-0401 H(S) Close 200-DCV-0401 and

divert classifier feed to 200-

ZC-030

Pump 200-PP-030 runs

too slow

Increase pump speed

Pump failure Start the spare pump

One cyclone/centrifuge

out of operation

Reduce classifier feed (feed from

dredge, or divert to 200-ZC-030)

Leakage via reverse

flow of standby pump

Check valve positions

Line blockage Isolate line section and flush the line

Valve 200-DCV-0401

fails open

Close valve 200-DCV-0401 locally and

control flow rate with manual bypass

valve

High flow from classifier Check dredge supply capacity

200-LISA-0401 L(S) Open 200-DCV-0401 and

restore classifer feed to

200-TK-030

200-LISA-

0401LLL(S)

Pump stop Pumps run too fast. Restart pump and reduce speed.

Low feed from classifier Check upstream equipment.

200-DICSA-0401

HH (SA)

Divert classifier feed to

200-ZC-030

Not sufficient liquor

supply from 200-PP-060

(200-DCV-0401 fully

open)

Check liquor supply from 200-PP-060

(pumps, valve positions).

Monitor level of 200-ZC-030.

When density decreases, activate

classifier discharge diverter 200-GA-

030 to 200-TK-030

Too high solids flow

from classifier (200-

DCV-0401 fully open)

Check dredge supply capacity.

Monitor level of 200-ZC-030.

When density decreases, activate

classifier discharge diverter 200-GA-

030 to 200-TK-030

200-DICSA-0401 L

(S)

Restore classifer feed to

200-TK-030


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5.7.16 Operation of sump 200-SU-090

Sump pump 200-PP-090 is started automatically by level switch 200-LS-0402. For start-up: 1 Make sure deaerator 200-DE-050 and settler 200-TK-050 are ready for receiving

liquor or slurry from the sump. 2 Open discharge valve of 200-PP-090 3 Set pump operating switch in automatic (check)

For shut down:

1 Set pump switch on off (check) 2 Close discharge valve of 200-PP-090

Note: Flushing of line is required after pumping slurries.


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6 MILLING AND CALCINING


To produce soda ash the CRS cake must be dried and calcined. The complete chemical reaction is shown below. 2 Na2CO3. NaHCO3

.2H2O(Trona) → 3 Na2CO3(Calcine) + 5 H2O (g) + CO2(g) A two stage calcination system is included in the process. The CRS cake is simultaneously ground and dried in roller mill 400-ML-010. A roller mill is the preferred grinding device because of energy efficiency, close control of particle size (reduced generation of super fines), and reduced iron contamination of the product. Grinding is essential to the process because the subsequent recrystallization process physically separates impurities based upon their particle size. The roller mill is the first stage of calcination. The wet CRS is heated to about 100°C, fully drying and partially calcining it. The hot air used for conveying and drying is supplied from the flash calciner cyclone. The roller mill grinds the product between hydraulically activated vertical rollers and a horizontal rotating table. The ground material falls off the table and into a louvered section, in which it contacts the mill air. The solids are pneumatically conveyed to variable speed impact classifier 400-CI-015 that rejects oversized material back to the center of the table for regrinding. The fine material (less than 105 micron) is carried to roller mill cyclone 400-CY-020 that collects about 85 - 90% of the solids in the underflow. The roller mill cyclone gases are blown by roller mill fan 400-FN-020 to ESP cyclone 400-CY-025 to be combined with the mill bypass gas and the roller mill dust cyclone underflow. The mill gas flow is controlled by roller mill fan damper 400-DA-010. Damper 400-DA-020 is positioned in the mill bypass gas line to provide additional flow balancing capability. The gas leaving the ESP cyclone will be at a temperature of about 130°C. It is estimated that the solids leaving the ESP cyclone will be > 30% calcined. The ESP cyclone and roller mill fan appear to add complication to the system, but provide significant cost and operational benefits. The roller mill size is significantly impacted by airflow. To match the mill size with the grinding requirements, it is necessary to bypass about 45% of the hot gas around the mill. The higher temperature of the combined gas stream supports additional calcination in the ESP cyclone. In addition, the ESP cyclone provides dust recovery that reduces the load on the electrostatic precipitator (ESP). The roller mill fan provides two important functions. The fan balances the pressure between the mill discharge and the bypassed gas. In addition, the fan reduces the vacuum on the ESP, reducing cost and air in-leakage.


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The ESP cyclone underflow is discharged into flash calciner 400-FD-050 just above the air-cooled grid plate 400-CK-050. There the hot combustion gases from the flash calciner burner 400-BU-050, mixed with the colder gas (recycled from the ESP exit) to produce a mixed gas at 700 to 730°C, are introduced. This gas and the solids react almost instantaneously, quenching the temperature to 400 to 450°C. The flash calciner conveying velocity is near 15 m/s, and the retention is about 2 seconds. This contact time is sufficient to fully calcine the solids and to heat them to 400°C. The high temperature ensures > 99% calcination, while eliminating organics that can be detrimental in the crystallization process. Calcined product is separated from the hot gases in flash calciner cyclone 400-CY-060 and transported by gravity via crystallizer feed airlocks 400-AL-060 and 400-AL-065 to calcined feed chamber 510-CH-010. During washouts and off-spec conditions the product stream can be diverted to dump tank 400-TK-060, where it is mixed with water for discharge to the lake. ESP 400-EP-030 consists of four high voltage electrical fields. Static charge is induced on the surface of the particles allowing their collection on charged plates. The accumulated dust is periodically removed from the plates by a rapping system. The ESP will reduce the exhaust gas dust loading to below 50 mg/Nm3. Dust losses will be less than 10 kg/h. Sulfur dioxide generated during the combustion of the heavy fuel oil reacts with the roller mill product in the calciner to produce sodium sulfate. More than 98% of the sulfur dioxide will be removed during calcination. The chemical reaction is shown below. SO2 (g) +½ O2 (g) + Na2CO3(s) → Na2SO4(s) + CO2 (g) 3 SO2 (g)+3/2 O2 (g)+2 Na2CO3.NaHCO3.2H2O(s)→ 3Na2SO4(s)+3 CO2(g) + 5 H2O (g) The sodium sulfate generated will dissolve in the crystallization process and will ultimately be purged to the lake. Cleaned air with a temperature of about 125 °C is transported by ESP ID fan 400-FN-030 to stack 400-ST-030, where the air is checked for particulates. Part of the air is recirculated by dilution air fan 400-FN-035 to be mixed with the calciner burner gases. When the ESP has a misoperation, the air can contain too much particulate material to be used for dilution and the dilution air fan suction will change to outside air Dust collected in the ESP is transported by ESP collection screw conveyor to roller mill ESP airlock 400-AL-040 and ESP dust bleed airlock 400-AL-030. Via the roller mill ESP airlock the dust is discharged into a pneumatic transport system, which brings the dust back to the flash calciner. The pneumatic transport system consists of ESP dust pneumatic conveyor blower 400-GB-040, ESP dust pneumatic conveyor 400-PN-040, ESP dust bin 400-BN-010, ESP dust collector 400-DC-010 and ESP dust collector airlock 400-AL-045. Remaining dust, which is not discharged into the pneumatic conveying


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system, is discharged via the ESP bleed dust airlock 400-AL-030 into ESP dust hopper 400-BN-040, where it is mixed with air and sucked into ESP dust conveyor 400-CV-040. The ESP dust conveyor is driven by washery feed cyclone overflow liquor and transports the dust to the washery feed cyclone overflow tank, from which it is ultimately discharged to the lake. All cyclones are equipped with 2 air cannons (400-AC-020/1, 400-AC-025/6 and 400-AC-060/1). In addition vibrators are mounted on the cyclones and the cyclone discharge lines (400-VB-020/1/2/3/4, 400-VB-025/6/7/8/9 and 400-VB-060/1/2).


6.2.1 Calcination waste (P&ID 400-15)

Dust transport Dust from 400-AL-030 falls into the ESP dust hopper (400-BN-040). Liquor is supplied by 200-PP-011/012. Solids and entrained gas are sucked into the jet conveyor 400-CV-040 and transported to the washery feed cyclone overflow tank. ESP bleed shut-off gate 400-GA-041 is closed when 400-LSA-1401 detects high level and when 200-PP-011 and 200-PP-012 are out of operation (so when flow to 400-CV-040 stops). 200-PP-011 is spare for both 200-PP-010 and 200-PP-012. Supplying hot ESP dust to the liquor causes the liquor temperature to increase due to the sensible heat increase by introduction of hot ESP dust and the heat of dissolution. Calciner exhaust stack Off-gasses from the calciner unit are vented through calciner exhaust stack 400-ST-030. The dust content is monitored with 400-QIA-1401. If an alarm is generated, the ESP system has to be checked.

6.2.2 Setting list


400-FISA-1401 m3/h 100 L 90 L 90

400-QIA-1401 mg/m3 <18 1) H 18

mg/Nm3 <50 2) H 50

1) At 127°C and 0.95 bara

2) at 0°C and 1.013 bara


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6.3 Logic functions

In this section the logic functions describing automatic actions of valves are described. Logical functions that act on equipment are for example: – Start conditions and running conditions – Process switches – Safety switches (dry run protection on pumps, speed alarm on conveyors) Thermal overload is provided on all electric motors. The thermal overload shuts off the motor directly (hardwired from MCC). Table: automatic actions of valves Valve Action Cause 400-GA-041 Close – 400-LSA-1401 H activated

– 200-PP-011 or 200-PP-012 out of operation

400-XSV-1401 Open – 200-PP-011 or 200-PP-012 out of operation 400-XSV-1402 Open – Signal from 400 section, prior to divert soda ash to

the dump tank


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6.4 Start-up and shutdown of Dust transport

6.4.1 Normal start-up

1 The Calciner is not yet running, or is not supplying ESP dust to 400-BN-040. 2 Check 400-GA-041 is closed 3 Check manual drain valve upstream of 400-CV-040 is closed. The automated drain

valve 400-XSV-1401 has to be closed by the operator (reset on DCS). 4 Check 200-TK-010 has sufficient level and that No.5 dredger supplies sufficient

liquor. 5 Check automated drain 400-XSV-1401 valve is closed (reset on DCS) 6 Start selected pump (200-PP-011 or 200-PP-012) 7 If pump is running well, then 400-GA-041 can be opened. 8 Now ESP dust can be supplied to 400-BN-040 by starting 400-AL-030

6.4.2 Normal shut-down

1 Stop the ESP dust stream from the ESP 2 Close 400-GA-041 (to prevent moisture entering the dust system) 3 Stop running pump 200-PP-011 or 012. 400-XSV-1401 will be opened automatically

when the pump stops. 4 400-XSV-1401 can stay open. The valve has to be closed by the operator (reset on

DCS).


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6.5 Start-up and shut-down of dump tank

6.5.1 Initial start-up

1 Open 400-XSV-1402 and read flow rate on FISA 1401. Check the recorded amount with the setting list.

2 Verify the sprayers provide an even water curtain.


1 Check that 400-TK-060 does not contain solids from previous dumpings. Liquid level (rain water) should be at nozzle N2 (1 m level). If water level is below nozzle N2, add water via manual valve.

2 Check that manual valve in process water supply line upstream of 400-FISA-1401 is open and manual valve in bypass line of 400-XSV-1402 is closed.

6.5.3 Procedure for emptying tank after dumping

Before dumping product into the dumptank, the sprayers are activated (400-XSV-1402 is opened). The valves stays open after dumping and are required to be closed by the operator. 1 When dumping is complete, close 400-XSV-1402 and check there is no dust

emission. 2 Liquid is flowing out of nozzle N2 3 If needed additional water is added via manual valve, in order to dissolve remaining

solids. Agitation with air lance can be applied. 4 When all solids are dissolved, the tank can be emptied via nozzle N1.

6.5.4 Normal shutdown

No real actions for shutdown. Manual valve upstream of 400-FISA-1401 can be closed. Tank can be emptied via nozzle N1 or drain nozzle.


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1 Dump tank level: when not in use, the dump tank level should be at nozzle N2. If too low, then supply water to fill to this level. If too high, then line 100-SLS1-102, connected nozzle N2, is plugged, or sump or ditch is flooded.

2 ESP Dust Hopper: check air inlet opening is free 3 Sampling and analyses: see Analytical Manual.


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6.7.1 Dump tank 400-TK-060

Product from the calciner section is passed to the dump tank in case of emergency shut down. A spraying system is installed on the dump tank to reduce dust emissions from the dusty calciner product. The tank contains a certain level of water to dissolve and cool down the dumped solids. Before crystallizer feed diverter 400-GA-060 is allowed to switch over, water supply to the dump tank via 400-XSV-1402 has to be opened to give a sufficient flow rate (400-FISA-1401). The water flow rate continues as long as required. There is no level indication on the dump tank. When starting with an empty tank, the capacity of the dump tank will give approx. 1 hour of use. When 400-GA-060 is closed, the water flow can be stopped. Operator to close 400-XSV1402. Liquid will flow out via nozzle N2 when the level reaches 1 m level in the tank and the liquid is collected in sump 200-SU-090. Any remaining solids will have to be dissolved with process water, that can be added via manual valve. Agitation with air lance can be applied if needed. The tank can be emptied by opening valve on nozzle N1.

6.7.2 Too low liquor feed flow to 200-TK-010

If there is no feed flow or too small a flow from the washery feed cyclone to 200-TK-010, the temperature will increase beyond what is acceptable. The liquor streams to the vent condenser 520-HX-010 and to the tailing tank 900-TK-250 will also rise in temperature, resulting in poor operation of the vent condenser. The return temperature to 200-TK-010 is monitored with 400-TIA-1401. When the temperature is too high (see setting list), an alarm is generated, and the cause of the high temperature has to be investigated or otherwise dust bleed has to be shut off. If there is no feed flow from the washery feed cyclone the level in 200-TK-010 will go down and 200-LCV-0201 closes. After a few minutes 200-LICSA-0201 reaches LL level and the pumps 200-PP-011/012 are switched off automatically.

6.7.3 Pump failure of 200-PP-011/012

When 200-PP-012 goes out of operation, following automated responses are activated: – 400-GA-041 is closed, 400-AL-030 is stopped and 400-SC-040 is stopped. – 400-XSV-1401 is opened. In this way liquor cannot enter the calciner system, and will drain out of bin 400-BN-040. When 200-PP-012 is out of operation and 200-PP-011 goes out of operation the same actions will follow. Before restart, it has to be verified that the bin 400-BN-040 is empty of liquid and dry.


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Valve 400-XSV-1401 has to be closed by the operator (reset action on the DCS).

6.7.4 High temperature of liquor return from 400-CV-040

The return temperature to 200-TK-010 is monitored with 400-TIA-1401. When the temperature is too high (see setting list) an alarm is generated, and the cause of the high temperature has to be found or otherwise dust bleed has to be shut off.


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6.8 Basic operating manual roller mill and calciner section

Functional Specification for a Roller Mill and Flash Calciner System Prepared for: Larsen & Toubro Limited FFE Contract No. (03-51573-727) DOC Ref: 2076-FF-400-PR-MS-001 Prepared by:

FFE Minerals USA Inc. 3235 Schoenersville Road Bethlehem, PA 18017 USA Tel. (610) 264-6900 Revision 2

FFE Minerals USA Functional Specification for a Roller Mill and Flash Calciner System Document No. 8.500933

Revision 2

ii Lake Magadi – Functional Specification – Rev 2

Document Information

Document Number 8.500933 Title Functional Specification for a Roller Mill and Flash Calciner System Contract Number 03-51573-727 Originating Author Michael Prokesch, FFE Minerals USA

Document Revision History

Rev. Date Designed Checked: Approved Description

1 30Nov04 MEP General Revisions as per Oct04 Hazop

2 05May05 MEP

Revisions as per P&IDs Rev 10, FLS Mill Control Review, Airtek ESP Review, and Vendor Documents Received to Date

Reference Documents

FFE Doc./ Dwg. # Document / Drawing Description

8.500742 Sheet 4 PID – Rev 10 - Roller Mill

8.500742 Sheet 5 PID – Rev 10 - Flash Calciner, Dust Return Circuit

8.500742 Sheet 6 PID – Rev 10 - Roller Mill Cyclone, ESP Cyclone

8.500742 Sheet 7 PID – Rev 10 - ESP, Stack, Dilution Air Circuit, Dust Conveying

8.500742 Sheet 8 PID – Rev 10 - Air Heater, Fuel Skids

8.500742 Sheet 9 PID – Rev 10 - Mill Drive Lubrication Circuit

8.500742 Sheet 10 PID – Rev 10 – Mill Roller #1 Lubrication Circuit



8.500742 Sheet 13 PID – Rev 10 – Upper Mill Body Water Spray Supply

8.500742 Sheet 14 PID – Rev 10 - ESP

8.500742 Sheet 15 PID – Rev 10 – Mill Hydraulic Circuit

FFE Minerals USA Functional Specification for a Roller Mill and Flash Calciner System Document No. 8.500933 Revision 2

Lake Magadi – Functional Specification – Rev 2

Document Format

This document begins with a description of the overall process. The entire process is then divided into groups and each is described in a separate section. The following table provides an overview of the document structure. Each group section includes a functional description of operation, equipment/instrument summary, control loop descriptions, alarm table and interlock table. Group Name Description

Process Overview Includes a description of the overall roller mill and calciner process.

Calciner Group The equipment that performs the high temperature calcination work and delivers product to the crystallizer circuit. The main components in the group include the fuel skid, valve stand, air heater, flash calciner and calciner collection cyclone.

Burner Management System

The stand-alone PLC-based system that controls the safety interlocks for the air heater burner system.

Roller Mill Group The equipment that receives the wet CRS feed and produces a fine, dry, pre-calcined feed for the Calciner Group.

Process Air Group All fans and dampers utilized for combustion and process air flow control.

ESP Group The equipment that removes particulate from the calciner system off gas stream.

Cleaning Group This group includes equipment utilized to promote stable material flow through cyclones and material transfer ducts (air cannons, rappers and vibrators).

Dust Handling Group Transports ESP dust to the calciner group for calcination.

Water Spray Group Provides water to the roller mill for the purpose of bed stabilization and temperature control.

Roller Mill Hydraulics Group Controls roller mill grinding pressure and roll position.

Lubrication Group Provides lubrication to the mill drive, rollers and classifier.


Revision 2

iv Lake Magadi – Functional Specification – Rev 2

Table of Contents

DOCUMENT INFORMATION..................................................................................ii Document Revision History ............................................................................................................................................. ii Reference Documents........................................................................................................................................................ ii Document Format ............................................................................................................................................................. iii

1 PROCESS OVERVIEW .......................................................................................... 1 1.1 Normal Cold Start Sequence ...................................................................................................................................... 3 1.2 Normal Stop Sequence ................................................................................................................................................ 5 1.3 Emergency Shutdown Sequence................................................................................................................................ 6

2 CALCINER GROUP.............................................................................................. 7 2.1 Functional Description................................................................................................................................................ 7

2.1.1 Burner Start Sequence....................................................................................................................................... 8 2.1.2 Burner Preheat Sequence................................................................................................................................ 10 2.1.3 System Idle Sequence ...................................................................................................................................... 11 2.1.4 CRS Feed Start ................................................................................................................................................. 12 2.1.5 CRS Capacity Increases................................................................................................................................... 13 2.1.6 Emergency Cooling Air .................................................................................................................................. 13

2.1.6.1 Combustion Air Fan Failure............................................................................................................................... 13 2.1.6.2 Dilution Air Fan Failure...................................................................................................................................... 13 2.1.6.3 ESP ID Fan Failure ............................................................................................................................................. 14 2.1.6.4 Dual Fan Failure................................................................................................................................................... 14 2.1.6.5 Complete System Power Loss............................................................................................................................ 14

2.1.7 Calciner Cyclone Discharge Tipping Valve ................................................................................................. 14 2.1.8 Tipping Valve Full Open Position Option.................................................................................................. 15 2.1.9 Calciner Cyclone Discharge Diverter Valve ................................................................................................ 16 2.1.10 Calciner Cyclone Discharge Rotary Valve ................................................................................................. 16

2.2 Equipment/Instrument Summary ........................................................................................................................... 16 2.3 Control Loops............................................................................................................................................................. 20

2.3.1 Calciner Exit Temperature Control .............................................................................................................. 20 2.4 Alarms .......................................................................................................................................................................... 21 2.5 Interlocks ..................................................................................................................................................................... 23

3 BURNER MANAGEMENT SYSTEM..................................................................... 25 3.1 Functional Description.............................................................................................................................................. 25

3.1.1 BMS Function Summary ................................................................................................................................ 25 3.2 Definitions ................................................................................................................................................................... 37 3.3 Definitions of Limits.................................................................................................................................................. 37 3.4 Timer Settings ............................................................................................................................................................. 39

4 ROLLER MILL GROUP...................................................................................... 40 4.1 Functional Description.............................................................................................................................................. 40

4.1.1 Roller Mill Preheat ........................................................................................................................................... 40 4.1.2 CRS Feed Start ................................................................................................................................................. 41

FFE Minerals USA Functional Specification for a Roller Mill and Flash Calciner System Document No. 8.500933 Revision 2


4.1.3 CRS Capacity Increases................................................................................................................................... 43 4.1.4 Classifier Speed ................................................................................................................................................ 43 4.1.5 Mill Feed Rotary Valve ................................................................................................................................... 43 4.1.6 Normal Roller Mill Shutdown ....................................................................................................................... 44 4.1.7 Emergency Roller Mill Shutdown ................................................................................................................. 44


4.3.1 Roller Mill Gas Flow Control ........................................................................................................................ 47 4.3.2 Mill Outlet Gas Temperature Control.......................................................................................................... 47 4.3.3 Mill Table Speed Control................................................................................................................................ 47

4.4 Alarms .......................................................................................................................................................................... 49 4.5 Interlocks ..................................................................................................................................................................... 50

5 PROCESS AIR GROUP.........................................................................................51 5.1 Functional Description.............................................................................................................................................. 51

5.1.1 Fan Group Start ............................................................................................................................................... 51 5.1.2 Individual Fan Start ......................................................................................................................................... 52 5.1.3 System Shutdown............................................................................................................................................. 52


5.3.1 Calciner Exit Pressure Control ...................................................................................................................... 55 5.3.2 Roller Mill Gas Flow Control ........................................................................................................................ 55

5.4 Alarms .......................................................................................................................................................................... 56 5.5 Interlocks ..................................................................................................................................................................... 57

6 ESP GROUP ..................................................................................................... 58 6.1 Functional Description.............................................................................................................................................. 58

6.1.1 ESP Start ........................................................................................................................................................... 58 6.1.2 ESP Normal Shutdown .................................................................................................................................. 59 6.1.3 ESP Emergency Shutdown ............................................................................................................................ 59 6.1.4 ESP Dust Screw............................................................................................................................................... 59 6.1.5 ESP Dust Purge Valve .................................................................................................................................... 60 6.1.6 ESP Hopper Rappers...................................................................................................................................... 61 6.1.7 ESP Outlet/Stack Gas Opacity ..................................................................................................................... 61 6.1.8 ESP Field Loss ................................................................................................................................................. 61

6.2 Equipment/Instrument Summary ........................................................................................................................... 61 6.3 Control Loops............................................................................................................................................................. 62 6.4 Alarms .......................................................................................................................................................................... 62 6.5 Interlocks ..................................................................................................................................................................... 62

7 CLEANING GROUP ........................................................................................... 63 7.1 Functional Description.............................................................................................................................................. 63

7.1.1 Air Cannons...................................................................................................................................................... 63 7.1.1.1 Individual Cannon Operation - Manual ........................................................................................................... 64 7.1.1.2 Group Cannon Operation - Manual ................................................................................................................. 64 7.1.1.3 Group Cannon Operation - Timed................................................................................................................... 65

7.1.2 Rappers .............................................................................................................................................................. 65 7.1.2.1 Individual Rapper Operation ............................................................................................................................. 65 7.1.2.2 Group Rapper Operation ................................................................................................................................... 66 7.2 Equipment Description............................................................................................................................................. 66


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vi Lake Magadi – Functional Specification – Rev 2

7.3 Control Loops............................................................................................................................................................. 67 7.4 Alarms .......................................................................................................................................................................... 67 7.5 Interlocks ..................................................................................................................................................................... 67

8 DUST HANDLING GROUP................................................................................. 67 8.1 Functional Description.............................................................................................................................................. 68

8.1.1 Dust Feed Start Sequence............................................................................................................................... 68 8.1.2 Dust Feed Stop ................................................................................................................................................ 68 8.1.3 Dust Feed Emergency Stop ........................................................................................................................... 68 8.1.4 Dust Bin Filter Cleaning Circuit.................................................................................................................... 69

8.2 Equipment Description............................................................................................................................................. 69 8.3 Control Loops............................................................................................................................................................. 70 8.4 Alarms .......................................................................................................................................................................... 70 8.5 Interlocks ..................................................................................................................................................................... 70

9 WATER SPRAY GROUP.......................................................................................71 9.1 Functional Description.............................................................................................................................................. 71

9.1.1 Mill Table Water Spray.................................................................................................................................... 71 9.1.2 Mill Body Water Spray Circuit ....................................................................................................................... 71

9.2 Equipment Description............................................................................................................................................. 71 9.3 Control Loops............................................................................................................................................................. 72 9.4 Alarms .......................................................................................................................................................................... 72 9.5 Interlocks ..................................................................................................................................................................... 72

10 ROLLER MILL HYDRAULIC GROUP ................................................................ 73 10.1 Functional Description............................................................................................................................................ 73

10.1.1 Normal Start ................................................................................................................................................... 73 10.1.2 Raise Rollers ................................................................................................................................................... 73 10.1.3 Lower Rollers ................................................................................................................................................. 74 10.1.4 Grinding Pressure Control ........................................................................................................................... 74

10.2 Equipment Description........................................................................................................................................... 75 10.3 Control Loops........................................................................................................................................................... 76 10.4 Alarms ........................................................................................................................................................................ 76 10.5 Interlocks ................................................................................................................................................................... 76

11 LUBRICATION GROUP..................................................................................... 77 11.1 Functional Description............................................................................................................................................ 77

11.1.1 Roller Mill Main Drive Lubrication System .............................................................................................. 77 11.1.2 Roller Mill Roller Lubrication System ........................................................................................................ 78 11.1.3 Roller Mill Grease System ............................................................................................................................ 78 11.1.4 Classifier Drive Lubrication System ........................................................................................................... 78 11.1.5 Classifier Grease System............................................................................................................................... 78

11.2 Control Loops........................................................................................................................................................... 78 11.3 Equipment Description........................................................................................................................................... 78 11.4 Alarms ........................................................................................................................................................................ 81 11.5 Interlocks ................................................................................................................................................................... 83

12 EXTERNAL SYSTEM INTERLOCKS ................................................................... 83 12.1 CRS Weigh Feed Belt (200-FD-085)..................................................................................................................... 84


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1 PROCESS OVERVIEW The roller mill and flash calciner circuit serves to convert Crushed Refined Soda (CRS) supplied from the washery to a calcined soda ash product in a form suitable for further processing in the crystallizer circuit. The CRS is composed primarily of sesquicarbonate (97.4%) with minor amounts of sodium fluoride, sodium chloride and other inerts. The calciner process supports drying to remove 6% free water, grinding to reduce the particle top size to approximately 105 microns, and calcining the CRS at a maximum temperature of 400°C to convert the sesquicarbonate to an intermediate decimite phase followed by final conversion to sodium carbonate (soda ash). In addition to the chemical decomposition supported by the flash calciner, the temperature supports a partial decomposition of organic carbon present in the feed material. Minimizing the product residual bicarbonate level is important to maximizing the efficiency of the crystallizer circuit, and the organic carbon reduction is required to improve the color of the final pure ash product. The CRS is supplied by a transport system from the washery to a weigh feed system. This feed system (200-FD-085) meters the wet CRS to the roller mill system (400-ML-010) through a rotary airlock (400-AL-010). The feed chute between the rotary airlock and the mill body is heated utilizing mill inlet gas passed through a heating jacket in order to minimize the potential for material flow problems. The CRS drops onto the mill table where it is crushed between the rotating table and the three vertical rolls. A hydraulic system exerts a force onto the roll support arms to generate the pressure between the vertical rolls and horizontal table required to support the communition process. The centrifugal force exerted on the particles by the rotating table forces the particles to the periphery of the mill housing where they are entrained by the hot process gas from the calciner (400-FD-050) entering the mill housing through the louver section. The louvers serve to develop a gas velocity sufficient to limit CRS particles from falling below the table level and into the mill plenum. Particles that do enter the plenum are discharged from the bottom of the mill through manual gate valves. Coarse particles disengage from the gas stream and fall back onto the mill table while finer particles are carried to dynamic classifier 400-CI-015 located in the top section of the mill. The speed of the classifier is adjusted via a variable-frequency drive to permit the minus 105 micron particles to pass through the classifier rotor and exit the mill while deflecting the >105 micron particles back onto the mill table. Energy from the process gas stream supports the vaporization of all free water in the CRS and supports about 25% calcination of the sesquicarbonate in the roller mill. Additional water may be added onto the mill table delivered from 900-PP-060 to improve the dynamics of the material load on the table in order to limit instabilities that create mill vibration. Water may also be delivered to the mill freeboard section in a finely atomized form via water spray system 400-PP-010. The purpose of this spray is for the control of the mill off gas temperature, particularly during operation at reduced system capacities due to the need to maintain a level of process gas flow at the mill exit equivalent to 90% of the normal operating level. Maintaining this flow level at a reduced system capacity results in an excess of energy in the mill that will damage the classifier if the gas temperature is not limited to 110°C. Off gas from the roller mill system enters the mill cyclone (400-CY-020). The bulk of the particulate is disengaged from the process gas stream and discharged from the bottom cyclone cone through a rotary airlock (400-AL-020). Calciner off gas is pulled through the roller mill and mill cyclone by the roller mill fan (400-FN-020). Fan inlet damper 400-DA-010 is adjusted to maintain a target pressure drop across the mill cyclone to ensure sufficient gas flow through the mill. Vibrators (400-VB-020/021/022) and air cannons (400-AC-020/021) are positioned on the cyclone cone to prevent material from bridging across the cone and provide a smooth, continuous flow of solids to the next stage of the process. Additional vibrators (400-VB-023/024) are mounted on the underflow duct to minimize the potential for solids flow problems.


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2 Lake Magadi – Functional Specification – Rev 2

Off gas from the roller mill fan is combined with the calciner off gas bypassed around the mill, and then the roller mill cyclone underflow stream is introduced to this combined gas stream. This reintroduction of the milled solids into the off gas stream makes effective use of the energy in the mill bypass stream by supporting about 50% calcination of the sesquicarbonate still present and about 25% calcination of the decimite. This stream is directed to the ESP cyclone (400-CY-025) for particulate separation. The particulate underflow passes through the ESP cyclone rotary airlock (400-AL-025) and then enters flash calciner 400-FD-050 via a splash plate to promote good solids distribution into the calciner gas stream. The ESP cyclone and underflow ducting include vibrators (400-VB-025/026/027/028/029) and air cannons (400-AC-025/026) to promote stable solids flow as described for the mill cyclone. The ESP cyclone underflow material is entrained by calciner gas at a temperature of 730°C. The rapid decomposition of the sesquicarbonate and decimite components quenches the calciner gas to a temperature below 550°C. The stainless steel calciner section provides for a total gas residence time of about 2.5 seconds in order to support a reduction in the bicarbonate content to <0.4% and heat the solids to a temperature of 400°C. It is critical to the availability of the calciner to minimize the contact between solids and the hot calciner walls in the feed inlet zone in order to limit the potential for coating formation. The soda ash product is disengaged from the calciner process gas stream in the calciner collection cyclone 400-CY-060, and discharged through the actuated double tipping valve 400-AL-060. Crystallizer feed diverter 400-GA-060 is positioned below the airlock to direct cyclone cleanout material away from the crystallizer circuit during cleaning operations or when feed to the crystallizer must be stopped immediately. During normal operation, calciner product passes vertically downward through the diverter valve and is then discharged through rotary valve 400-AL-065. This rotary valve is utilized to stabilize the flow of material into the calciner and dampen material slugs generated by the action of the double tipping valve. The ducting below the feed airlock is maintained at a negative pressure by the crystallizer vent fan to prevent saturated gas from the crystallizer from condensing in the ducting and creating buildup problems. Air cannons (400-AC-060-061) and vibrators (400-VB-060/061/062) are included on the calciner cyclone cone to promote stable material flow if required. Hot gas for the calciner operation is generated using flash calciner burner 400-BU-050 and the combustion of heated heavy fuel oil. The fuel rate is adjusted to control the calciner collection cyclone process gas overflow temperature at 425°C, and the ratio of fuel to the air supplied by primary combustion air fan 400-FN-050 is controlled by the Process Control System to generate a maximum gas temperature of 1600°C. This gas exits the calciner burner and enters a mixing chamber where it is combined with stack gas supplied by dilution fan 400-FN-035 to yield a final mix temperature of 730°C. The design of the refractory-lined mix chamber is such that the tangential entry of the relatively cool stack gas limits the refractory surface temperature to reduce the potential for the deposition of fine soda ash that is present in the stack gas. The stack gas first passes through a jacket on the calciner burner to provide cooling of the chamber prior to be introduced into the mix chamber. The velocity in the jacket is such that particulate present in the dilution air stream will remain suspended as opposed to settling out and accumulating in the jacket. The 730°C calciner inlet gas passes through air-cooled grid plate 400-CK-050 supplied with cooling air from grid plate cooling fan 400-FN-055. The primary function of the grid plate is to distribute the calciner inlet gas across the full cross section of the calciner below the feed inlet location. This even distribution eliminates gas recirculation zones that would draw the calciner feed material down into the hottest zone of the calciner and promote buildup formation. The air cooling serves to limit the temperature of the top surface of the


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plate in order to prevent sticking of material that does come in contact with the plate. The cooling air exiting the grid plate is vented into the calciner above the feed inlet location. The off gas from the calciner system (overflow stream from the ESP cyclone) is cleaned using a 4-field electrostatic precipitator (400-EP-030). The cleaned off gas passes through roller mill ESP ID fan 400-FN-030. The ID fan damper 400-DA-030 is adjusted to maintain a neutral gas pressure in the top of the flash calciner vessel. A portion of the ID fan outlet gas is directed to the stack while the balance is pulled by dilution air fan 400-FN-035 for use in the calciner. In the event that a problem with the ESP results in a stack particulate concentration >50 mg/Nm3, tempering tee 400-DA-034 is opened to introduce ambient air to the calciner inlet and prevent high concentrations of particulate from entering the high-temperature calciner inlet. Dust collected in the ESP is discharged through screw conveyor 400-SC-040. The discharge from the screw is normally passed through rotary valve 400-AL-030 and conveyed to a dust recovery circuit (provided by others). In the event that dust is to be reprocessed in the flash calciner, rotary valve 400-AL-040 is activated and the dust output is conveyed to dust bin 400-BN-010 using blower 400-GB-040. A manual valve positioned above 400-AL-040 controls the flow of dust into this circuit while the balance of the dust is discharged through 400-AL-030. All material collected in the dust bin is discharged through rotary valve 400-AL-045 and into the calciner.

1.1 NORMAL COLD START SEQUENCE

1. Inspect the calciner system for signs of material blockages, coatings or accumulation on the grid plate or in the calciner plenum. Clear as required. Inspect all mechanical equipment and lubrication levels as per the maintenance manual.

2. Select “Start Roller Mill Roller Lubrication System” in the PCS. This will energize the oil heating elements. This command should be initiated at least one hour prior to the target start time to provide adequate time for fluid heating and to avoid potential delays. This is not required for a hot restart. Start the ESP hopper heaters.

3. Start the mill classifier lube circuit.

4. Select “Start Process Air Group” in the PCS. This start sequence will place the associated dampers in their “start” position (fully closed) and fully open the tempering tee (if closed) to provide for 100% ambient air intake. Automatic starting of the following fans will commence in sequence: ESP ID fan, dilution air fan, combustion air fan, grid cooling fan and mill fan. The operator may also start these fans manually after ensuring appropriate interlocks are satisfied (dampers closed and the temperature tee fully open).

5. Select “Pilot Only” or “Oil Firing”.

6. Select “Purge Start” in the PCS. This will send a purge start command to the Burner Management System. The Process Control System will position the ID fan damper, dilution air fan damper, combustion air fan damper, mill bypass damper, mill fan damper and mill inlet shutoff damper at specified open limits to support the purge process. Once all necessary limits are satisfied in the fuel skid, valve stand and calciner system, the BMS will proceed with the specified system purge.

7. Once the purge process is complete, the PCS will position the ID fan, dilution air fan and combustion air fan dampers to their low fire positions, close the mill fan damper and close off the mill inlet damper. Once in position, the BMS will light the pilot. If the pilot flame is proved and


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“Pilot Only” is selected, no further action will be performed. If “Oil Firing” is selected, ignition of the main oil burner will proceed immediately following pilot ignition.

8. The PCS will make adjustments to the fuel rate and air/fuel ratio to preheat the air heater chamber. This sequence will ensure proper preheating of the chamber refractory lining and establish a calciner off gas temperature of 300°C (System Idle condition).

9. Start the ESP dust purge rotary valve and hopper discharge screw conveyor.

10. Select “Start All ESP Fields” in the PCS. The PCS will send a command to the local ESP PLC to energize all fields.

11. Start all cyclone discharge valves (3 rotary valves and 1 tipping valve). Set the product diverter valve to direct calciner product to the crystallizer circuit.

12. Approximately one hour before the CRS feed start target, start the following mill system components:

a. Start the roller mill main drive lubrication system. This will start the circulating lube pump.

b. Start the roller mill hydraulic group. The hydraulic pump will run until the rollers are moved to there upper position and then de-energize.

c. Set the classifier speed to 50% and then initiate a start command. Once started, adjust the classifier speed to the normal level. The classifier grease system is energized by the PCS once the classifier drive is started.

13. Open the mill inlet damper and then open the mill fan inlet damper to a position of 3%. Hold this setting while the mill is preheated to a freeboard temperature of 80°C. Once 80°C is obtained, either close the damper to hold or immediately proceed with a feed start.

14. Initiate a “Start CRS Feed” command. Upon receiving this command, the Process Control System will perform the following actions:

a. Activate the mill off gas temperature control loop (105°C set point).

b. The PCS will issue the prompt “Mill Pre-charge Required”. If the mill table is void of material (inspect if necessary), select “Yes”. The PCS will proceed to start the CRS feed system and deliver CRS to the mill table for a period of approximately 30 seconds (time TBD during commissioning).

c. The mill fan damper is opened to a preset position to develop the required process gas flow to the mill.

d. The mill main drive is started at the specified speed set point. The roller mill grease system is started automatically.

e. The rollers are lowered to the mill table.

f. The CRS feed system is started at 70% of normal capacity.

g. The hydraulic pump is started if necessary to obtain the target grinding system pressure.

h. Increase the ID fan damper opening.

i. Increase fuel flow and combustion air fan output.

j. Increase the dilution fan damper opening.

k. After 20 minutes the mill roller lubrication pumps are started.


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15. The mill table water spray may now be started if required to stabilize the mill operation and reduce vibration.

The calciner system is now in a “Feed Start” mode. This mode of operation can be continued or proceed to the next step to increase capacity.

16. Allow the system to stabilize (1-2 minutes). Engage the following control loops allowing for appropriate system response and stabilization before initiating the subsequent control loop:

a. Mill flow

b. Calciner off gas temperature

c. Calciner inlet temperature

d. Calciner exit pressure

17. Slowly close the tempering tee to recirculated stack gas to the calciner system. This should be performed over a period of several minutes to allow the system controllers to respond.

18. If normal system operation has required the use of vibrators and air cannons to maintain stability, activate the cleaning groups.

19. Increase the CRS feed rate in 5-10 mtph increments until the target production rate is achieved. Stabilize and then adjust control loop set points if needed to obtain target operating conditions.

20. If ESP dust is to be returned to the calciner, set the speed of the dust feed rotary valve to minimum and then initiate a start command for the Dust Handling Group. If the calciner system is operating at full capacity, reduce the CRS feed rate prior to increasing the dust feed rate to the calciner.

1.2 NORMAL STOP SEQUENCE A normal stop sequence is engaged either upon receiving a command from the operator or when a condition upstream or downstream of the calciner system requires a feed stoppage (i.e. low CRS level in the calciner feed bin, loss of crystallizer vent flow, etc).

1. Initiate a “Feed Stop” command. Upon receiving this command, the Process Control System will perform the following automatic adjustments:

a. Ramp CRS feed rate down to 70% of normal operating capacity,

b. Reduce calciner exit temperature to 300°C,

c. Stop CRS feed and the mill feed rotary valve,

d. Close mill fan damper and mill inlet damper,

e. Raise mill rollers,

f. Stop the main mill drive,

g. Move the tempering tee to the fresh air intake position and adjust the system for System Idle conditions,

h. De-energize air cannons, rappers and vibrators,

2. If the stop sequence is initiated due to a failure of the crystallizer vent fan, the diverter on the calciner cyclone discharge duct will be repositioned to divert solids to the soda ash dump bin. If


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safety interlocks prevent access to this bin, the calciner will proceed with an emergency shutdown sequence.

3. The system can be idled at these conditions until a feed start is required. If a full shutdown is required, initiate a burner stop command. This command will stop fuel flow to the air heater and place the system in a cool down mode. Once the air heater chamber refractory temperature decreases to <150°C, all fans can be stopped. The Process Control System will send a stop command to the ESP to de-energize all fields and stop the screw conveyor five minutes after the last process fan has been stopped, or the ESP may be de-energized by the operator. Calciner discharge valves will continue to operate until manually stopped by the operator.

1.3 EMERGENCY SHUTDOWN SEQUENCE Emergency shutdown of the calciner system is required to protect plant personnel, prevent equipment damage due to the failure of key components in the system, in response to the presence of process conditions that will lead to equipment damage, and/or the need to immediately stop the flow of hot soda ash into the crystallizer circuit when the soda ash dump bin is not available. This mode of shutdown puts extra stress on the equipment and as such is implemented for emergencies only. Responses to the following scenarios are described below:

1. Local emergency stop command: a. Stop CRS feed and mill valve, b. Stop mill water spray(s), c. De-energize air cannons, vibrators and rappers, d. Stop Mill fan and close mill fan and mill inlet dampers, e. Raise mill rollers, stop mill drive and classifier drive, f. Stop fuel flow to air heater, g. Stop all valves and dust transport to calciner (if active), h. Place ID fan, dilution fan and combustion fan dampers in their “Low Fire” settings to

maintain cooling airflow to the system. i. Open the tempering tee for ambient air intake.

2. Combustion air fan failure: a. Stop fuel flow to the air heater, b. Start the cooling air fan and open the valve on the duct leading to the burner, c. Stop CRS feed and mill valve, d. Stop mill water spray(s), e. De-energize air cannons, vibrators and rappers, f. Stop mill fan and close mill fan and mill inlet dampers, g. Raise mill rollers, stop mill drive and classifier drive, h. Stop all valves and dust transport to calciner (if active), i. Place ID fan and dilution fan dampers in their “Low Fire” settings, j. Open the tempering tee for ambient air intake.

3. Dilution air fan failure: a. Stop fuel flow to the air heater, b. Close the dilution air fan inlet damper, c. Start the cooling air fan and open the valve on the duct leading to the air heater cooling

jacket, d. Stop CRS feed and mill valve,


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e. Stop mill water spray(s), f. De-energize air cannons, vibrators and rappers, g. Stop mill fan and close mill fan and mill inlet dampers, h. Raise mill rollers, stop mill drive and classifier drive, i. Stop all valves and dust transport. j. Place ID fan and combustion air fan dampers in their “Low Fire” settings.

4. High/high temperature: a. Stop fuel flow to air heater, b. Stop CRS feed and mill valve after a 2 minute delay, c. Stop mill water spray(s), d. De-energize air cannons, vibrators and rappers, e. Stop mill fan and close mill fan and mill inlet dampers, f. Raise mill rollers, stop mill drive and classifier drive, g. Stop all valves and dust transport, h. Place ID fan, dilution fan and combustion fan dampers in their “Low Fire” settings to

maintain cooling airflow to the system. i. Open the tempering tee for ambient air intake.

5. High/high CO: a. De-energize ESP fields, b. Stop fuel flow to air heater, c. Stop CRS feed and mill valve, d. Stop mill water spray(s), e. De-energize air cannons, vibrators and rappers, f. Stop mill fan and close mill fan and mill inlet dampers, g. Raise mill rollers, stop mill drive and classifier drive, h. Stop all valves and dust transport, i. Place ID fan, dilution fan and combustion fan dampers in their “Low Fire” settings to

maintain cooling airflow to the system. j. Open the tempering tee for ambient air intake.

2 CALCINER GROUP The Calciner Group consists of the Fuel Skid (400-BU-050-F1), Valve Stand (400-BU-050-V1), Burner (400-BU-050), Air Heater Chamber (400-FU-050), Flash Calciner (400-FD-050), Air-cooled Grid Plate (400-CK-050), Calciner Collection Cyclone (400-CY-060), Calciner Cyclone Dual Tipping Valve (400-AL-060), Calciner Cyclone Discharge Diverter Valve (400-GA-060), Calciner Cyclone Discharge Rotary Valve (400-AL-065) and Burner Cooling Air Fan Circuit (400-FN-054). These components are referenced on the following C&ID drawings:

• 8.500742 SHT. 5 (400-02) • 8.500742 SHT. 8 (400-05)

2.1 FUNCTIONAL DESCRIPTION The Calciner Group controls the delivery and combustion of fuel in the air heater to provide the hot process gas required to support the calcination process, accepts ground CRS from the mill circuit, may accept fines from the ESP dust handling circuit, performs the high temperature calcination work and delivers calcined


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soda ash to the crystallizer . Select components on the fuel skid and valve stand are controlled by the Burner Management System to satisfy safety protocols during purge and ignition sequences once a start command is received from the Process Control System. After the burner ignition sequence is complete and a flame is successfully detected, control of components in the Calciner Group resides in the Process Control System until a burner stop is initiated by the Burner Management System as a result of a safety or process interlock action. A description of the Burner Management System logic is included in Section 3.

2.1.1 BURNER START SEQUENCE The operator first selects “Pilot Only” or “Oil Firing” on the main PCS display. If “Pilot Only” is selected, the Burner Start sequence will stop once a pilot flame is proved by the BMS. If the “Oil Firing” switch is selected by the operator, the full Burner Start sequence will be performed unless stopped by the operator or by the BMS as the result of an interlock or a safety action. The PCS defaults to a “Pilot Only” setting whenever the operation of the main burner is stopped. Once the Burner Start sequence is stopped at pilot ignition as the result of a “Pilot Only” setting, the Burner Start sequence can be resumed upon an operator “Oil Firing” selection. A “Stop” command given by the operator at any time in the sequence will be treated by the BMS as a safety or interlock failure and reset to the beginning of the sequence. A “Start Purge” sequence is initiated from the Process Control System (PCS). Upon receiving a “Start Purge” command from the operator, the PCS and BMS will perform the following:

1. The BMS checks for operation of the combustion air, mill, dilution air and ESP ID fans via motor contacts and pressure switches: 1.1. Combustion air fan: EM0461 contact and PSA-0462. 1.2. Mill fan: EM0223 contact and PS-0202. 1.3. Dilution air fan: EM0323 contact and PS-0302. 1.4. ESP ID fan: EM0321 contact and PS-0301.

2. Check the air heater refractory temperature 400-TIS-4069: 2.1. If <500°C, prompt “Install Low Capacity Oil Nozzle” 2.2. If >500°C, prompt “Install High Capacity Oil Nozzle”

3. Wait for a “Correct Nozzle Installed” confirmation from the operator , 4. Check for a ready signal from the BMS, 5. The PCS will move dampers in sequence until they are in their “Purge” positions as indicated by the

following switch closures: 5.1. ID Fan Damper (400-DA-030), position switch 400-GBS-0310A 5.2. Combustion Fan Damper (400-DA-050), position switch 400-GBS-0460A 5.3. Dilution Air Fan Damper (400-DA-035), position switch 400-GBS-0302A 5.4. Mill Air Fan Damper (400-DA-010), position switch 400-GBS-0261A 5.5. Mill Bypass Damper (400-DA-020) fully open, position switch 400-GBS-0163A 5.6. Mill Inlet Damper (400-DA-015) fully open, position switch 400-GBS-0165 Once these positions are satisfied a ready signal will be issued by the PCS to the BMS.

6. BMS will check the following damper position limits: 6.1. ID Fan Damper (400-DA-030), position switch 400-GBS-0310A 6.2. Combustion Fan Damper (400-DA-050), position switch 400-GBS-0460A 6.3. Dilution Air Fan Damper (400-DA-035), position switch 400-GBS-0302A 6.4. Mill Air Fan Damper (400-DA-010), position switch 400-GBS-0261A 6.5. Mill Bypass Damper (400-DA-020) fully open, position switch 400-GBS-0163A

6.5.1. If satisfied within 10 minutes, proceed with sequence


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6.5.2. If not satisfied within 10 minutes, alarm in BMS and display in PCS 6.5.3. If not satisfied within 60 minutes, alarm in BMS, reset sequence in PCS and reset BMS

7. BMS oil flow control valve 400-TCV-0131 Low Fire position check: (position switch 400-GB-0414) 7.1. If valve in position, proceed and lock out PCS control 7.2. If valve out of position, alarm to PCS and recheck position:

7.2.1. The PCS repositions valve and satisfies limit within 10 minutes, proceed with sequence and lock out PCS control

7.2.2. Limit not satisfied within 10 minutes, reset sequence in the PCS and BMS 8. Purge interval timing in BMS. Ready signal sent to PCS following purge completion, 9. PCS will re-position dampers in sequence for Low Fire until the following position switches are

closed (the mill bypass damper remains in its full open position): 9.1. ID Fan Damper (400-DA-030), position switch 400-GBS-0310C 9.2. Combustion Fan Damper (400-DA-050), position switch 400-GBS-0460C 9.3. Dilution Air Fan Damper (400-DA-035), position switch 400-GBS-0302C 9.4. Mill Fan Damper (400-DA-010), position switch 400-GBS-0261B 9.5. Mill Inlet Damper (400-DA-015) fully closed, position switch 400-GBS-0165.

10. PCS Low Fire damper position check: 10.1. All switches closed – send a ready signal to the BMS 10.2. All switches not closed – alarm and wait for resolution before proceeding 10.3. “Stop” command from operator – reset sequence in PCS and send reset command to the BMS

11. PCS combustion air flow rate check (400-FFIC-0460): 11.1. If within +/-10% of target set in PCS (TBD during commissioning), send ready signal to the

BMS 11.2. If flow is outside this range, display “Combustion Air Flow Out of Range” and check flow

indication every 30 seconds and compare to target: 11.2.1. If within +/-10% tolerance, send ready signal to the BMS 11.2.2. If outside tolerance, wait 30 seconds and then recheck

11.3. “Stop” command from operator – reset sequence in PCS and send reset command to the BMS 12. BMS pilot ignition sequence:

12.1. Start igniter, 12.2. Open pilot gas valves 400-XSV-0440 and 400-XSV-0441, 12.3. Stop igniter, 12.4. Scanner detection of pilot,

12.4.1. If “Pilot Only” selected at start of sequence, stop sequence and hold 12.4.2. If “Oil Firing” selected at start of sequence, proceed

12.5. No pilot detection by scanner – Burner Start sequence reset in the BMS and PCS 13. BMS main burner ignition sequence

13.1. Open steam shutoff valve 400-XSV-0422, 13.2. Open oil shutoff valve 400-XSV-0442, 13.3. Close oil bypass shutoff valve 400-XSV-0444, 13.4. Stop pilot gas flow, 13.5. Scanner detection of main burner, Burner Start sequence complete. Proceed to Preheat

sequence 13.6. No main burner detection by scanner – Burner Start sequence reset in the BMS and PCS

If ignition sequences are successful, the BMS sends a Burner On signal to the PCS and releases its interlock on fuel control valve 400-TCV-0131 for PCS control during the Preheat and/or System Idle sequences. If the ignition sequence is not successful, the BMS will issue an alarm to the PCS and reset. The operator must now issue a “Start Purge” command in the PCS.


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2.1.2 BURNER PREHEAT SEQUENCE Following successful ignition of the main burner, the PCS will make adjustments to the air/fuel ratio in the air heater to increase the chamber temperature as per refractory preheat specifications. In the case of a cold system start where refractory dry-out is required, PCS program adjustments will be required to permit manual operation of oil flow control valve 400-TCV-0131 and combustion air damper 400-DA-050. Dry-out instructions are provided in the Operating Manual. Once the preheat sequence is complete, the Burner Idle sequence will establish a calciner off gas temperature of about 300°C. If the air heater refractory temperature (400-TIS-0469) is less than 200°C at the time that the main oil burner operation is proved by the BMS, the automated preheat sequence includes the following:

1. Maintain Low Fire settings until the rate change in the Air Heater outlet temperature 400-TIA-0468 drops below 5°C/minute.

2. Increase the combustion air flow to TBD Nm3/h by opening combustion air fan damper 400-DA-050. Increase oil flow (400-TCV-0131) to increase the temperature at 400-TIA-0468 by 65°C above the temperature present just prior to the fan damper adjustment and hold this temperature for 1 hour. Continue these 65°C step changes until a temperature of 1000°C is obtained at 400-TIA-0468. Hold for 1 hour and then proceed with the System Idle sequence.

3. Adjust the dilution air fan damper position (400-DA-035) during the preheat cycle to limit the calciner inlet temperature (400-TISCA-0140) to 325°C.

4. Adjust the ID fan inlet damper (400-DA-030) to maintain a pressure of -25 mm WG at the calciner exit (400-PICA-0130).

Once the oil flow rate reaches 25 lpm, the PCS will stop further fuel rate changes and prompt the operator to “Install Large Oil Nozzle”. If the large nozzle is already installed, the operator will simply select “Large Oil Nozzle Installed” and then the PCS will continue with the preheat sequence. If a nozzle change is required, the following must be performed:

1. Select “Change Oil Nozzle” is made by the operator when the technician is ready to perform the action,

2. The PCS sends a “Change Oil Nozzle” signal to the BMS. The BMS proceeds to light the pilot and then close valve 400-XSV-0442 to stop oil flow and returns a ready signal to the PCS. The PCS displays “Proceed with Nozzle Change”,

3. The PCS moves the oil control valve 400-TCV-0131 and fan dampers to their Low Fire positions, 4. After the nozzle installation is complete, the operator selects “Nozzle Change Complete”. The PCS

sends a “Resume Main Burner Operation” signal to the BMS, which in turn proceeds with the balance of the Main Burner start sequence.

5. The PCS receives a ready signal from the BMS and adjusts 400-TCV-0131 for an oil flow rate of 25 lph and holds this rate for 1 hour.

6. The PCS resumes the preheat sequence at 65°C per hour. If the refractory temperature (400-TI-0469) is greater than 200°C and less than 815°C, the PCS will engage in the following automated preheat sequence following successful ignition of the main burner:

1. Increase the combustion air flow to TBD Nm3/h by opening combustion air fan damper 400-DA-050. Increase oil flow (400-TCV-0131) to increase the temperature at 400-TIA-0468 by 65°C above the temperature present just prior to the fan damper adjustment and hold this temperature for 1 hour. Continue these 65°C step changes until a temperature of 815°C is obtained at 400-TIA-0468. Hold for 1 hour and then proceed with the System Idle sequence.


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2. Adjust the dilution air fan damper position (400-DA-035) during the preheat cycle to limit the calciner inlet temperature (400-TISCA-0140) to 325°C.

3. Adjust the ID fan inlet damper (400-DA-030) to maintain a pressure of -25 mm WG at the calciner exit (400-PICA-0130).

If the refractory temperature (400-TI-0469) is greater than 815°C at the time that the main burner is ignited, no preheat sequence is performed. The PCS will proceed with a System Idle sequence. The system preheat sequences may proceed as long as the following conditions are satisfied:

1. Emergency Stops are not engaged 2. No high temperature states existing:

a. Calciner inlet (400-TICSA-0140) b. Calciner outlet (400-TICSA-0131,400-TIZA-0161) c. Roller mill outlet (400-TICSA-0004) d. ESP outlet (400-TISA-0302)

3. ESP ID Fan running (400-FN-030) 4. Combustion Air Fan running (400-FN-050) 5. Dilution Air Fan running (400-FN-035) 6. Grid Cooling Air Fan running (400-FN-055) 7. Tempering Tee in full open position (400-GIS-0328) for ambient air intake 8. No high CO at the ESP inlet (400-QISZA-0301)

If conditions 2, 6 and 8 are not satisfied, the preheat sequence will be held at current conditions until the problems are resolved. The remaining conditions will result in a main burner shutdown. If a failure occurs with the operation of the combustion air fan or dilution air fan after the system is hot, the PCS will perform the functions described in Section 2.1.6.

2.1.3 SYSTEM IDLE SEQUENCE Once the Burner Preheat sequence is completed or a chamber refractory temperature (400-TI-0469) greater than 815°C is detected at the time of main burner ignition, the PCS will proceed with an automatic System Idle sequence. This sequence will move the fan dampers and oil flow controller to preset positions to establish the conditions required before a “CRS Feed Start” command can be made. The sequence includes the following (actual positions to be determined during system commissioning):

1. Move the ESP ID fan inlet damper (400-DA-030) to an open position of TBD%, 2. Move the dilution air fan damper (400-DA-035) to an open position of TBD%, 3. Increase the oil flow rate to TBD lpm. The PCS will automatically adjust the combustion air flow

rate to obtain the normal operating air/fuel ratio in the air heater. A constant air/fuel ratio will be maintained by the PCS until a system shutdown or “Pilot Only” command is issued.

System Idle operation may continue indefinitely as long as the following conditions are satisfied:

1. Emergency Stops are not engaged 2. No high/high temperature states existing:

e. Calciner inlet (400-TICSA-0140) f. Calciner outlet (400-TICSA-0131,400-TIZA-0161)


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g. Roller mill outlet (400-TICSA-0004) h. ESP outlet (400-TISA-0302)

3. ESP ID Fan running (400-FN-030) 4. Combustion Air Fan running (400-FN-050) 5. Dilution Air Fan running (400-FN-035) 6. Tempering Tee in full open position (400-GIS-0328) for ambient air intake 7. No high high CO at the ESP inlet (400-QISZA-0301)

If a condition in the above list is not satisfied, the main burner will be shutdown by the BMS.

2.1.4 CRS FEED START A “CRS Feed Start” command can be issued by the operator once the following preconditions are satisfied:

1. A minimum calciner collection cyclone off gas temperature of 275°C (400-XY-0131) is attained under System Idle conditions,

2. There is not a low CRS level indication in CRS feed bin 200-BN-085. 3. Roller mill start conditions are satisfied (see Section 4), 4. Cyclone discharge valves are started and operating (400-AL-060, 400-AL-065, 400-AL-020 and 400-

AL-025), 5. The calciner cyclone discharge diverter gate 400-GA-060 is in a closed position (400-GBS-0154B) to

direct solids to the crystallizer circuit, (NOTE: A manual over ride is to be provided to enable a feed start during system testing when the diverter gate is in an open position)

6. All ESP (400-EP-030) fields are energized, 7. Mill Bypass Damper 400-DA-020 is 100% open.

Once the “CRS Feed Start” command is issued, the PCS will position fan dampers to support the higher firing rate required and to satisfy roller mill flow requirements (see Section 4 for roller mill response information) and heat load imparted as a result of CRS drying, heating and calcination. The PCS will move oil flow valve (400-TCV-0131) to a set position to provide an HFO flow rate of TBD lpm. The system will continue to operate with the preset conditions specified for a CRS Feed Start until (1) process interlocks are satisfied that permit feed rate increases (all control loops engaged and tempering tee set for stack gas recirculation), (2) a feed stop/System Idle is requested by the operator, (3) a burner stop and system shutdown is requested by the operator, (4) a mill fault requires a feed stop/System Idle, or (5) a main burner stop is required due to one or more of the following actions/conditions:

1. Emergency Stops are engaged 2. High/high temperature states existing:

i. Calciner inlet (400-TICSA-0140) j. Calciner outlet (400-TICSA-0131,400-TIZA-0161) k. Roller mill outlet (400-TICSA-0004) l. ESP outlet (400-TISA-0302)

3. ESP fields de-energized (400-EP-030) 4. ESP ID Fan not running (400-FN-030) 5. Combustion Air Fan not running (400-FN-050) 6. Dilution Air Fan not running (400-FN-035)


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2.1.5 CRS CAPACITY INCREASES The CRS feed rate may be increased manually by the operator once all control loops are engaged. These control loops include:

1. 400-CTL-01: Calciner exit temperature (Calciner Group) 2. 400-CTL-02: Calciner inlet temperature (Process Air Group) 3. 400-CTL-03: Mill Flow (Process Air Group) 4. 400-CTL-04: Calciner pressure (Process Air Group)

In addition, no active alarm conditions can be present in the calciner system. The CRS rate may be increased in increments selected by the operator, up to a maximum rate of 106 mtph (as indicated by weigh belt feeder 200-FD-085). This maximum rate is password protected in the PCS and provides protection against over-feeding the system. An over-feeding situation will result in low temperature alarm conditions, air heater over-fueling, instability and an eventual feed stop condition.

2.1.6 EMERGENCY COOLING AIR The Calciner Group includes an emergency cooling air circuit to protect the burner and air heater chamber in the event that flow is lost from the combustion air fan and/or the dilution air fan. Engaging of the emergency cooling air circuit will occur if the air heater refractory temperature (400-TI-0469) is >200°C and either the combustion air fan or dilution air fan stop. The circuit can be de-energized by the operator manually once 400-TI-0469 drops below 150°C.

2.1.6.1 COMBUSTION AIR FAN FAILURE If the PCS detects a loss of contact for Combustion Air Fan 400-FN-050 motor 400-EM-0461 or pressure switch 400-PS-0402 opens due to low pressure when 400-TI-0469 is >200°C, the following actions are performed by the PCS:

1. Cooling Air Fan 400-FN-054 is immediately energized, 2. Valve 400-XSV-0471 opened, 3. Damper 400-DA-050 is closed, 4. The dilution and ESP ID air fan dampers are moved to their purge positions.

In addition, the BMS will detect this loss of contact and/or pressure switch status change and immediately stop fuel flow to the main burner. The automatic response by the PCS will supply cooling air to the burner to protect it from high temperature damage. If the Combustion Air Fan is re-energized successfully or a manual shutdown command is issued by the operator (400-TI-0469 <150°C), valve 400-XVS-0471 will be closed and then the cooling air fan stopped.

2.1.6.2 DILUTION AIR FAN FAILURE If the PCS detects a loss of contact for Dilution Air Fan 400-FN-035 motor 400-EM-0323 or pressure switch 400-PSA-0302 opens due to high pressure when 400-TI-0469 is >200°C, the following actions are performed:


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1. BMS: Fuel flow to the combustion chamber is stopped, 2. PCS: Cooling Air Fan 400-FN-054 is immediately energized, 3. PCS: Valve 400-XSV-0470 opened, 4. PCS: Damper 400-DA-035 is closed, 5. PCS: The combustion and ESP ID air fan dampers are moved to their purge positions.

These actions will supply cooling air to the air heater cooling jacket to protect the inner air heater shell from high temperature damage. If the Dilution Air Fan is re-energized successfully or a manual shutdown command is issued by the operator (400-TI-0469<150°C), valve 400-XVS-0470 will be closed and the cooling air fan stopped.

2.1.6.3 ESP ID FAN FAILURE If the PCS detects a loss of contact for ESP ID Fan 400-FN-030 motor 400-EM-0321 or pressure switch 400-PS-0301 opens due to high pressure, operation of the combustion air fan and dilution air fan will continue with their dampers moved to their Low Fire positions to provide cooling air to the burner and cooling jacket. Valve 400-XSV-0472 on the Emergency Vent and the ESP ID fan damper 400-DA-030 will be opened 100% to alleviate system backpressure resulting from the loss of the ID fan. Valve 400-XSV-0472 will be closed by the PCS when ESP ID Fan operation is again confirmed.

2.1.6.4 DUAL FAN FAILURE If the PCS detects failures of both the Combustion Air Fan and the Dilution Air Fan and the air heater refractory temperature 400-TI-0469 is >200°C, Cooling Air Fan 400-FN-054 will be immediately energized and valves 400-XSV-0470 and 400-XSV-0471 opened. The BMS immediately stops fuel flow to the main burner. These actions will supply cooling air to the burner and the air heater cooling jacket to protect both areas from high temperature damage. If both fans are re-energized successfully or a manual shutdown command is issued by the operator (400-TI-0469 <150°C), valves 400-XVS-0470 and 400-XVS-0471 will be closed and then the cooling air fan stopped.

2.1.6.5 COMPLETE SYSTEM POWER LOSS In the event that all power is lost to the calciner system and the air heater refractory temperature 400-TI-0469 is greater than 500°C, steam will be supplied to the main burner and air heater cooling jacket to minimize the potential for thermal damage. Valve 400-XSV-0424 and valve 400-XSV-0425 will fail in an open position to direct steam to the two locations, and valve 400-XSV-0472 on the Emergency Vent will fail open to vent the steam to atmosphere. As soon as power is restored to critical items (up to 20 minutes), Cooling Air Fan 400-FN-054 will be energized, steam valves 400-XSV-0422 and 400-XSV-0425 will close, and then valves 400-XSV-0470 and 400-XSV-0471 will open. Valve 400-XSV-0426 on the emergency steam purge line will be closed by the PCS when 400-TI-0469 is <450°C and opened when >500°C to permit steam flow to the air heater during a power loss condition only if required.

2.1.7 CALCINER CYCLONE DISCHARGE TIPPING VALVE The calciner cyclone discharge dual Tipping Valve 400-AL-060 is started manually by the operator via the PCS. This valve may be started at any time except when an emergency stop is engaged or the unit is locked out for maintenance work. In either of these two cases, the PCS shall indicate that the valve is not available for operation. A permissive for a “CRS Start Feed” command cannot be issued until this valve is operating.


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The valve timing sequence is set in the PCS as per supplier specifications and cannot be changed by the operator. The following sequence is performed during normal start, run and stop cycles for the dual tipping valve unit:

1. Check for emergency stop and maintenance lock out. If not present, continue to step 2, 2. Check that the upper and lower valves are in their closed positions. If either closed limit is not

satisfied (400-GS-0151 and 400-GS-0152), issue an alarm indicating “position limits not satisfied”. If limits are satisfied, display a start permissive on the PCS screen,

3. The operator manual selects the tipping valve icon and selects “Start”, 4. The PCS energizes Solenoid A to direct instrument air to the low side of the cylinder and open the

high side to ambient. This extends Cylinder A and moves the upper valve into its open position. If the open limit switch (400-GS-0151) is not satisfied within 2 seconds after energizing Solenoid A, issue an alarm indicating “position limit not satisfied” and remove the start permissive.

5. Energize Solenoid A for a total period of 6 seconds after the open limit is satisfied and then de-energize Solenoid A. This will open the low side of the cylinder to ambient and pressurize the high side. This retracts Cylinder A and moves the upper valve to its closed position. If the closed limit switch is not satisfied within 2 seconds after de-energizing Solenoid A, issue an alarm indicating “position limit not satisfied” and remove the start permissive.

6. Three seconds after the upper valve reaches its closed position, energize Solenoid B to direct instrument air to the low side of the cylinder and open the high side to ambient. This extends Cylinder B and moves the lower valve into its open position. If the open limit switch (400-GS-0152) is not satisfied within 2 seconds after energizing Solenoid B, issue an alarm indicating “position limit not satisfied” and remove the start permissive.

7. Energize Solenoid B for a total period of 6 seconds after the open limit is satisfied and then de-energize Solenoid B. This will open the low side of the cylinder to ambient and pressurize the high side. This retracts Cylinder B and moves the lower valve to its closed position. If the closed limit switch is not satisfied within 2 seconds after de-energizing Solenoid A, issue an alarm indicating “position limit not satisfied” and remove the start permissive.

8. Three seconds after the lower valve reaches its closed position limit, repeat the cycle until a stop command is received from the operator, an emergency stop is activated or the local maintenance switch is engaged.

9. When the valve is stopped for whatever reason, de-energize both solenoids so that the upper and lower valves return to their closed positions.

2.1.8 TIPPING VALVE FULL OPEN POSITION OPTION The start menu for the tipping valve also provides an option to position the valve in a fully open position. In this situation, both solenoids are energized to force the valves into a full open position and then held until a close command is given by the operator. This option may be exercised during a cyclone cleaning operation, to impact material flow stability during operation, improve air cannon cleaning effectiveness, etc. This option cannot be exercised in the following situations:

1. An emergency stop is active 2. The unit is locked out for maintenance 3. The diverter is open to the crystallizer (it must be open to the dump tank)


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2.1.9 CALCINER CYCLONE DISCHARGE DIVERTER VALVE The calciner cyclone discharge Diverter Valve 400-GA-060 is utilized to divert calciner product away from the crystallizer during cleanout operations or when a failure of the Crystallizer Vent Fan forces an immediate stoppage of material flow to the crystallizer. The diverter permits an immediate stoppage of solids flow to the crystallizer without necessitating a sudden calciner system shutdown. A permissive for a “CRS Start Feed” command cannot be issued until this valve is in its closed position as indicated by position switch 400-GBS-0154A. The operation of this valve is permitted in the following scenarios:

1. Manual positioning by the operator when the CRS feed system is inactive, 2. Automatic positioning by the PCS when a failure of the crystallizer vent fan occurs.

Both modes of operation are contingent upon availability of Material Dump Bin 400-TK-060. This bin may be locked out for safety reasons during discharge and cleaning operations. If the bin is locked out, then a crystallizer vent fan failure will result in an immediate stoppage of the CRS feed system. If the bin is available, the diverter valve is positioned automatically by the PCS to direct material to the dump bin, and then the calciner system is moved into a hot idle mode or normal shutdown mode by the operator.

2.1.10 CALCINER CYCLONE DISCHARGE ROTARY VALVE The calciner cyclone discharge Rotary Valve 400-AL-065 is utilized to stabilize the flow of solids into the crystallizer wetting section. This valve may be started at any time except when an emergency stop is engaged or the unit is locked out for maintenance. In either of these two cases, the PCS shall indicate that the valve is not available for operation. A permissive for a “CRS Start Feed” command cannot be issued until this valve is operating. The following sequence is performed during normal start, run and stop cycles for the rotary valve:

1. Check for emergency stop and maintenance lock out. If not present, display a start permissive on the PCS screen,

2. The operator manually selects the rotary valve icon and selects “Start” from the menu, 3. The PCS send a start signal to the motor starter for 400-EM-0125, 4. The PCS checks for a valve motion confirmation from 400-SSA-0101. If this is not received within 5

seconds after receiving a motor start confirmation from the starter, the motor is de-energized and an alarm is displayed,

5. Once a successful start is achieved, the valve is de-energized via: a. A loss of motion detection, b. Motor fault, c. Emergency shutdown action, d. Opening of Diverter Valve 400-GA-060 to the dump bin,

2.2 EQUIPMENT/INSTRUMENT SUMMARY The Calciner Group consists of the following components and attached instruments and equipment: Calciner Group


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Description PCS Display Reference Tag

Fuel Skid 400-BU-050-F1

Butane Pressure Regulator 400-PC-0400

Butane Pressure Indicating Gage 400-PI-0401

Butane Pressure Switch (Minimum pressure indication) 400-PSA-0402

Butane Pressure Switch (High pressure indication) 400-PSA-0403

Butane Flow Orifice (Local check only) 400-FP-0404

Butane Pressure Indicating Gage 400-PI-0407

HFO Pressure Indicating Gage 400-PI-0408

Instrument Air Pressure Indicating Gage 400-PI-0404

Instrument Air Low Pressure Switch 400-PSA-0405

HFO Pressure Regulator 400-PC-0409


HFO Pressure Switch (Minimum pressure indication) 400-PSA-0411

HFO Pressure Switch (High pressure indication) 400-PSA-0412

HFO Minimum/Maximum Temperature Switch 400-TIS-0413

HFO Circuit Heat Tracing X 400-EA-0401

HFO Heat Tracing Temperature Controller 400-TC-0401

HFO Flow Transmitter X 400-FIT-0401

HFO Flow Control Valve 400-TCV-0131

HFO Flow Control Valve Open/Closed Position Switch X 400-GBS-0414


Purge Steam Pressure Regulator 400-PC-0416

Purge Steam Pressure Indicating Gage 400-PI-0417

Atomizing Steam Pressure Indicating Gage 400-PI-0419

Emergency Steam Purge On/Off Valve (Temperature Controlled) 400-XSV-0426

Burner Emergency Steam Purge Valve (Fail Open) 400-XSV-0425

Burner Emergency Steam Purge Valve Open/Closed Position Indicator

X 400-GBS-0425

Air Heater Jacket Emergency Steam Purge Valve (Fail Open) 400-XSV-0424

Air Heater Jacket Emergency Steam Purge Valve Open/Closed Position Indicator

X 400-GBS-0424

Atomizing Steam Flow Indicator 400-FI-0418

Atomizing Steam Shutoff Valve 400-XSV-0422

Atomizing Steam Shutoff Valve Open/Close Position Switch X 400-GBS-0422


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Valve Stand 400-BU-050-V1

Butane Shutoff Valve #1 400-XSV-0440

Butane Shutoff Valve Open/Close Position Switch X 400-GBS-0440

Butane Shutoff Valve #2 400-XSV-0441

Butane Shutoff Valve Open/Close Position Switch X 400-GBS-0441

HFO Supply Shutoff Valve 400-XSV-0442

HFO Supply Shutoff Valve Open/Close Position Switch X 400-GBS-0442


HFO Recirculation Shutoff Valve 400-XSV-0444

HFO Recirc Shutoff Valve Open/Close Position Switch X 400-GBS-0444

Purge Steam Shutoff Valve 400-XSV-0445

Purge Steam Shutoff Valve Open/Close Position Switch X 400-GBS-0445

Atomizing Steam Pressure Regulator 400-PC-0446

Atomizing Steam Low Pressure Switch 400-PSA-0420

Burner 400-BU-050

Pilot Flame Scanner 400-XISA-0463

Main Flame Scanner 400-XISA-0469

Air Heater 400-FU-050

Outlet Gas Temperature Indicator X 400-TISA-0468

Cooling Jacket Outlet Air Temperature Indicator X 400-TIA-0467

Refractory Temperature Indicator X 400-TIS-0469

Vent Stack Valve 400-XSV-0472

Vent Stack Valve Open/Close Position Switch X 400-GBS-0472

Cooling Air Fan 400-FN-054

Burner Cooling Air Valve 400-XSV-0471

Burner Cooling Air Valve O/C Position Switch 400-GBS-0471

Air Heater Jacket Cooling Air Valve 400-XSV-0470

Air Heater Jacket Cooling Air Valve O/C Position Switch 400-GBS-0470

Burner Cooling Air Pressure Indicator 400-PI-0454

Air-Cooled Grid Plate 400-CK-050

Cooling Air Flow Indicator X 400-FIA-0137

Air Inlet Pressure Gauges 400-PI-152A-F

Air Outlet Temperature Transmitters with Local Indication X 400-TIA-A-F

Flash Calciner 400-FD-050

Calciner Inlet Temperature Control/Indicator X 400-TISCA-0140


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Calciner Inlet Pressure Indicator X 400-PIA-0139

Grid Plate Differential Pressure Indicator X 400-PDA-0138

Calciner Temperature Indicator X 400-TI-0101




Calciner Exit Pressure Control/Indicator X 400-PICA-0130

Calciner Inlet Carbon Monoxide Analyzer X 400-QISZA-0180

Calciner Load Cells (Optional) X 400-WIA-0135

Calciner Collection Cyclone 400-CI-060

Off Gas Temperature Indicator X 400-TI-0131A

Off Gas Temperature Indicator X 400-TI-0131B

Off Gas Temperature Indicator X 400-TI-0131C

Off Gas Temperature Indicator X 400-TI-0131D

Off Gas Temperature Control/Indicator X 400-TICSA-0131

Off Gas Emergency Temperature Shutoff X 400-TIZA-0162

Off Gas Pressure Indicator/Switch X 400-PISA-0161

Cyclone Load Cells (Optional) X 400-WIA-0148

Solids Discharge Temperature Indicator X 400-TIA-0150

Cone Pressure Indicator X 400-PIA-0147

Dual Tipping Valve 400-AL-060

Upper Tipping Valve Control Solenoid Valve 400-KSV-0151

Lower Tipping Valve Control Solenoid Valve 400-KSV-0152

Upper Tipping Valve Open/Close Position Switch X 400-GS-0151

Lower Tipping Valve Open/Close Position Switch X 400-GS-0152

Diverter Valve 400-GA-060

Diverter Valve Position Control 400-XSV-0154

Diverter Valve Position Switch X 400-GBS-0154A/B

Diverter Underflow Pressure Indicator X 400-PA-0156

Rotary Valve 400-AL-065

Rotary Valve Motion Switch X 400-SSA-0101

Rotary Valve Cooling Water Flow Control Valve 400-TCV-0157

Rotary Valve Cooling Water Temperature Controller X 400-TICS-0157


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2.3 CONTROL LOOPS

2.3.1 CALCINER EXIT TEMPERATURE CONTROL The calciner exit temperature control loop (400-CTL-01) may be placed in automatic by the operator once a “CRS Feed Start” has been performed and stable system operation is observed. This is a cascading control loop in that the combustion air is increased to satisfy a request for a temperature increase immediately followed by an increase in the fuel flow rate to satisfy the air/fuel ratio set point. When a calciner outlet temperature decrease is called for, the fuel flow rate is first decreased followed by a decrease in the combustion airflow to satisfy the air/fuel ratio set point. The default temperature for this loop is 425°C, but this may be adjusted by the operator to maintain the target soda ash product temperature as indicated at 400-TIA-0150. The PCS will not allow this control loop to be engaged unless a “CRS Feed Start” condition is detected (CRS Feed Belt 200-FD-085 operating). Once successfully engaged, the calciner temperature control loop will look at the maximum calciner cyclone off gas temperature indicated (400-TI-0131A-D). This function helps protect the system against improper control response due to an erroneous reading resulting from a damaged thermocouple, coating formation, etc. The PCS will consider the four temperature indications (400-TI-0131A-D) and select the maximum temperature reading for the purpose of control (400-XY-0131). Once a maximum temperature is selected, a temperature indication at another position must exceed the selected position by 5°C before a different thermocouple position will be selected for control purposes. This is required to avoid unnecessary switching. If more than one thermocouple should indicate the same temperature level, the PCS shall select the first thermocouple in the A-B-C-D sequence. If the temperature is below the set point value, the PCS will increase the opening of the combustion air fan damper 400-DA-050. As an increase in the air flow rate is indicated, the PCS will immediately adjust the position of the oil flow control valve 400-TCV-0131 such that the flow rate indicated by 400-FIT-0401 satisfies the required air/fuel ratio. If the temperature indication is above the set point value, the PCS will reduce the flow rate of fuel followed by a reduction in combustion air flow to hold the air/fuel ratio. The control loop should be tuned to limit calciner cyclone off gas temperature fluctuations to +/-5°C. The PCS will compare the actual air/fuel ratio to the set point level. If the air/fuel ratio deviates from the set point level by more than -5% at any time, the fuel control valve will be frozen by the PCS until the combustion air damper positioning and flow rate have the opportunity to respond. Once the deviation is less than -2%, oil flow rate adjustment may resume. If the air/fuel ratio deviates from the set point level by more than +5% at any time, the combustion air damper will be frozen by the PCS until the fuel oil control valve positioning and flow rate have the opportunity to respond. Once the deviation is less than +2%, oil flow rate adjustment may resume. If the air/fuel ratio deviates from the set point by more than +/-10%, the PCS shall freeze both valves and issue an alarm. This logic minimizes the potential for an over-fueling scenario that will result in carbon monoxide formation and burner shutdown on high-high CO at the calciner inlet. The air/fuel ratio is set in the PCS and may be changed by the operator after password protection is satisfied. This protection is required to prevent accidental or incorrect adjustment to the air/fuel ratio which will lead to dangerous operating conditions and poor system performance. If during the process of adjusting the fuel firing rate the grid cooling air outlet temperature (400-TIA-0152A-F) exceeds 435°C, an alarm will be issued by the PCS. The operator will respond by instructing an opening of the grid cooling air fan manual damper to increase the cooling air flow through the grid plate and/or a redistribution of cooling air using the manual valves positioned on the individual air supply ducts.


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This control loop is automatically deactivated if the Calciner Group is moved into Low Fire or System Idle modes, or the system is shutdown.

2.4 ALARMS

Alarm Condition Alarm Trigger

Device Analog Set

Point Debounce

Value

Burner Management System Fault See Section 3 - -

Heating Jacket Current High 400-EA-0401 - 10 sec

Air Heater Outlet Gas Temperature High 400-TIA-0468 >1650°C 0 sec

Air Heater Jacket Outlet Air Temperature High 400-TIA-0467 >300°C 0 sec

High 400-QISZA-0180 0.5% 0 sec Calciner Inlet CO Level

High High 400-QISZA-0180 1.2% 0 sec

High 400-TISCA-0140 >750°C 0 sec Calciner Inlet Gas Temperature

High High 400-TISCA-0140 800°C 2 sec

Grid Cooling Air Temperature High 400-TIA-0152A-F >435°C 5 sec

High 400-PICA-0130 >25mm WG 10 sec Calciner Exit Pressure

Low 400-PICA-0130 <-50mm WG 10 sec

High 400-TICSA-0131 >435°C 0 sec Calciner Cyclone Exit Gas Temperature High High 400-TICSA-0131 450°C 15 sec

Calciner Cyclone Exit Gas Temperature High High 400-TZA-0162 455°C 0 sec

Low 400-PISA-0161 <-200mm WG 5 sec

High 400-PISA-0161 >0mm WG 5 sec Calciner Cyclone Exit Gas Pressure

High High 400-PISA-0161 200mm WG 5 sec

High 400-PIA-0147 -25mm WG 10 sec Calciner Cyclone Cone Pressure

High High 400-PIA-0147 0mm WG 10 sec

High 400-TIA-0150 405°C 15 sec Calciner Cyclone Solids Discharge Temperature Low 400-TIA-0150 390°C 15 sec

Calciner Cyclone Discharge Leg Pressure Low 400-PA-0156 -50mm WG 10 sec

Calciner Weight (Optional) High 400-WIA-0135 TBD TBD

Cyclone Weight (Optional) High 400-WIA-0148 TBD TBD

Combustion Air Fan Motor Failure 400-EM-0461 - -

Combustion Air Fan Damper Position – Closed Limit Not Satisfied 400-GBS-0460A - -

Combustion Air Fan Damper Position – Purge Limit Not Satisfied 400-GBS-0460B - -


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Combustion Air Fan Damper Position – Low Fire Limit Not Satisfied 400-GBS-0460C - -

Dilution Air Fan Damper Position – Closed Limit Not Satisfied 400-GBS-0302A - -

Dilution Air Fan Damper Position – Purge Limit Not Satisfied 400-GBS-0302B - -

Dilution Air Fan Damper Position – Low Fire Limit Not Satisfied 400-GBS-0302C - -

ESP ID Fan Damper Position – Closed Limit Not Satisfied 400-GBS-0130A - -

ESP ID Fan Damper Position – Purge Limit Not Satisfied 400-GBS-0130B - -

ESP ID Fan Damper Position – Low Fire Limit Not Satisfied 400-GBS-0130C - -

Mill Fan Damper Position – Closed Limit Not Satisfied 400-GBS-0261A - -

Mill Fan Damper Position – Purge Limit Not Satisfied 400-GBS-0261B - -

Mill Inlet Damper Position – Closed Limit Not Satisfied 400-GBS-0165

Cooling Air Fan Motor Failure 400-EM-0452 - -

Vent Stack Position – Closed Limit Not Satisfied 400-GB-0472 - -

Vent Stack Position – Open Limit Not Satisfied 400-GB-0472 - -

HFO Flow Rate Check – Out of Spec Software - -

Air/Fuel Ratio Check – Out of Spec Software - -

Grid Cooling Air Fan Motor Failure 400-EM-0124 - -

Low 400-FI-0137 1000 m3/h 0 sec Grid Cooling Air Flow

Low Low 400-FI-0137 500 m3/h 0 sec

Calciner Inlet Gas Pressure High 400-PIA-0139 >305mm WG 5 sec

Grid Plate Differential Pressure High 400-PDA-0138 >250mm WG 2 sec

Upper Tipping Valve – Closed Limit Not Satisfied 400-GS-0151 - 5 sec

Upper Tipping Valve – Open Limit Not Satisfied 400-GS-0151 - 5 sec

Lower Tipping Valve – Closed Limit Not Satisfied 400-GS-0152 - 5 sec

Lower Tipping Valve – Open Limit Not Satisfied 400-GS-0152 - 5 sec

Diverter Gate – Closed Limit Not Satisfied 400-GBS-0154B - 2 sec

Diverter Gate – Open Limit Not Satisfied 400-GBS-0154A - 2 sec

Rotary Valve Motor Failure 400-EM-0125 - -

Rotary Valve – Rotor Motion Not Detected 400-SSA-0101 - 5 sec


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2.5 INTERLOCKS All interlocks required for the system are listed in tabular format. The output device is listed in the left-hand column. Interlock Conditions are listed in the middle column as “AND” Boolean top to bottom, “OR” Boolean left to right. The Interlock Type is listed in the right column. In local control mode devices are operated locally using start/stop, open/close push buttons. In Manual control each device is started and stopped from the HMI, using device manual control pop-up screen. In group control mode all the devices in a particular group start and stop, based on sequential start and stop logic. In Individual group control all devices in a group are started and stopped individually by the operator; when their start and stop logic is satisfied. Safety Interlock will shutdown device in local, manual, or group control mode. The failure of a Start interlock will not allow the device to be started in group control mode or in individual group control mode. The failure of a Process interlock will cause the system to stop after the system has been started in group control mode or in individual group control mode. The failure of an interlock will cause the equipment to shut-down or execute other interlock related actions.

Interlock Type Equipment/Action Signals

Safety Start Process

X X

Z X Sample: (X AND Y AND Z); Z to start, X AND Y to run, X for safety shutdown Y X

BMS “Burner On” Signal X

Refractory Temperature (400-TI-4069) <815°C X Preheat Sequence

Tempering Tee in Full Ambient Intake Position X X

Air Heater Refractory Temperature >815°C (400-TI-4069) X


No High High Temperature Conditions X System Idle Sequence

Tempering Tee in Full Ambient Intake Position X X

Calciner Cyclone Outlet Temperature (400-XY-0131) >275°C X


ESP Fields Energized (400-EP-030) X X

Mill Bypass Damper (400-DA-020) Full Open X

Mill Start Permissive X

CRS Feed Start Sequence

CRS (200-BN-085) Bin Level NOT Low X


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Interlock Type Equipment/Action Signals


All System Valves Operating and Diverter Gate Open to Crystallizer Circuit X X

Diverter Valve (400-GA-060) to Dump Tank

Dump Tank Available (400-TK-060) as indicated by Water Flow Switch 400-FSIA-1401 (400-XSV-1402 Open)

X

Combustion Air Fan NOT Operating (400-EM-0461)

Dilution Air Fan NOT Operating (400-EM-0323)

X X Cooling Air Fan (400-FN-054) Start

Air Heater Outlet Temp >200°C (400-TIA-0468) X X

Combustion Air Fan Running (400-EM-0461)

X Cooling Air Fan (400-FN-054) Stop Dilution Air Fan

Running (400-EM-0323)

Air Heater Outlet Temp <200°C (400-TIA-0468)

X

Combustion Air Fan NOT Operating (400-EM-0461) X Burner Cooling Air Valve (400-

XSV-0471) Open Cooling Air Fan Running (400-EM-0452) X

Burner Cooling Air Valve (400-XSV-0471) Close

Combustion Air Fan Running (400-EM-0461) X

Dilution Air Fan NOT Operating (400-EM-0323) X Air Heater Cooling Air Valve

(400-XSV-0470) Open Cooling Air Fan Running (400-EM-0452) X

Air Heater Cooling Air Valve (400-XSV-0470) Close Dilution Air Fan Running (400-EM-0323) X

ESP ID Fan NOT Operating (400-EM-0321) X

Emergency Vent Stack (400-XSV-0472) Open Air Heater Outlet Temp >200°C (400-TIA-

0468) X

Emergency Vent Stack (400-XSV-0472) Close ESP ID Fan Running (400EM-0321) X

Air Heater Jacket Emergency Steam Purge Valve Open (400-XSV-0425)

No System Power X

Burner Emergency Steam Purge Valve Open (400-XSV-0425) No System Power X

Emergency Steam Supply Valve Open (400-XSV-0426)

Air heater refractory temperature (400-TIS-0469) >500°C X

Emergency Steam Supply Valve Closed (400-XSV-0426)

Air heater refractory temperature (400-TIS-0469) <450°C X


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3 BURNER MANAGEMENT SYSTEM The Burner Management System (BMS) is comprised of a PLC control system positioned local to the burner system.

3.1 FUNCTIONAL DESCRIPTION The Burner Management System is a local PLC controller utilized to ensure safety protocols are followed during the pilot and main burner ignition processes. Operation of the main burner cannot be performed by the PCS until a signal is received from the BMS indicating that combustion related components satisfy various limit requirements and a successful purge cycle has been completed. Once main burner ignition and flame is proved by the BMS, this system continues to monitor the presence of the main burner flame. If flame status should change at anytime, the BMS will stop the flow of fuel to the burner and alarm the PCS. Communication between the BMS and PCS is performed over a serial bus. A permissive signal for starting along with error messaging is handled across this bus.

3.1.1 BMS FUNCTION SUMMARY The following table summarizes the functions of the BMS, its interaction with the PCS, and operator input requirements:

OPERATOR INTERFACE SYSTEM OPERATION

Notes: The burner management system is designed to be operated from either the local panel or the PCS; however, the PCS must enable local operation. This procedure assumes that the operator is at the local panel and that the local operation has been enabled. All pushbuttons referred to n this document have parallel commands fro the PCS. See PCS documentation for information on enabling local control from the PCS.

NORMAL BURNER STARTUP

1.0 Make sure the correct atomizer has been installed in the burner. Generally speaking, the low flow atomizer will be used for a cold start while the full capacity atomizer will be used for hot starts.

1.0

2.0 Press the power on pushbutton. 2.0 This will provide power to the panel. The BMS will indicate “Power On”.


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3.0 Start the following fans: ID Fan Combustion Air Fan Dilution Air Fan Mill Fan Other fans as may be required by the process

3.0 The fan limits for each fan will be satisfied and the BMS will indicate:

“ID Fan On” “CA Fan On” “DA Fan On” “Mill Fan On”

4.0 Open the manual inlet isolation valve on the instrument air.

4.0 The Instrument Air Low Pressure Switch should now be made.

5.0 Make sure that the following “Common Limits” (See Appendix II) are made:

Process Interlocks (from PCS) Process temperature not high Flame Signal Processor is not in fault

5.0 All “Common Limits” (See Appendix II) should now be made.

6.0 Open the following Pilot Gas Valves Pilot gas inlet manual isolation valve Pilot gas outlet manual isolation valve

Note: The limiting orifice valve in the pilot line is set at commissioning and should not require further adjustment. Deviation from the optimum setup, either more open or closed, may cause pilot instability unreliable burner lightoff.

6.0 Pilot Limits (See Appendix II) should now be made and the BMS will indicate “Pilot Limits OK”.

7.0 If “Oil Firing” is to be the selected firing mode (see Step 8), the following pumps, heaters, & valves should be turned on or opened:

Required oil supply pumps Required oil heaters

(Note: Refer to Pump & Heater Set instructions for information on operating the pumps & heaters).

Oil inlet manual isolation valve Oil outlet manual isolation valve Steam inlet manual isolation Steam outlet manual isolation valve Condensate manual valves

7.0 When the oil pump is on the BMS will indicate “Oil Pump On”. When the oil and steam pressures and oil temperature have reached operating levels, “Oil Limits” (See Appendix II) should be satisfied and the BMS will indicate “Oil Limits Ok” (See Appendix II).


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Firing Mode Selection

8.0 The operator should insure that the appropriate limits are satisfied. Once the limits are proven, he should select the firing mode he wants to operate with prior to starting the ignition sequence. There are two choices for Firing Mode Selection. They are:

8.0 The BMS will not allow a mode selection if both “Common Limits” and “Pilot Limits” are not satisfied. The BMS will not allow “Oil Firing” to be selected if “Oil Limits” are not satisfied. If the operator should attempt to make a Firing Mode Selection prior to the required limits being satisfied, the BMS will indicate which limit is preventing further sequencing. Correct the failed limit and make the Firing Mode Selection again.

8.1 Pilot Firing – The system will light the pilot and will not proceed to main fuel firing mode. The pilot will remain lit until “Burner Stop” is pressed, a fault occurs, or an alternate firing mode is selected. This is the default selection. “Pilot Firing” is selected by pressing the “Pilot Select” pushbutton.

8.1 The BMS will indicate “Pilot Select” when “Pilot Firing” is selected.

8.2 Oil Firing – “Oil Firing” is selected by pressing the “Oil Select” pushbutton and can be selected at any point in the sequence. However, the system will not sequence to “Oil Firing” until the system has first sequenced to “Pilot Firing”. With “Oil Firing” selected and “Flame On”, the burner will proceed from “Pilot Firing” to “Oil Firing” and, once the main flame is proven, the pilot will shut off.

8.2 The BMS will indicate “Oil Select” when “Oil Firing” is selected.

Burner Start (From Burner Stop to Pilot Firing)

9.0 Make sure that a Firing Mode has been selected then press the “Burner Start” pushbutton

9.0 The BMS will not allow a “Burner Start” selection until a Firing Mode has been selected. If a “Burner Start” is selected prior to selecting a Firing Mode, the BMS will display “Select Firing Mode”. Make the selection and press “Burner Start” again. This pushbutton will initiate the ignition sequence and the BMS will sequence through all steps of the sequence without further operator interface through the BMS. The steps for ignition are as follows:


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9.1 9.1 When the Burner Start is pressed, the sequence enters “Pre-Purge” and the BMS starts the following timers (see Appendix III):

Pre-Purge Timer

At the same time the BMS sends a signal to the PCS requesting the following damper/valve positions:

ID Fan Damper high CA Fan Damper high DA Fan Damper high DA Bleed Damper Open RM Fan Damper Hi Switch Mill Bypass Damper high Main Control Valve low

9.2 9.2 The BMS will evaluate the status of the following limits (See Appendix II):

Common Limits Purge Damper Limits Purge Limits

If the limits are proven within the “Pre-Purge” timing, the system will proceed to “Purge”. If they are not proven within the “Pre-Purge” timing, the system will go into “Alarm” and the sequence must be restarted beginning at Step 8.

10.0 10.0 While in “Purge” the BMS will evaluate the following limits:

Common Limits Purge Damper Limits Purge Limits

If any of these limits fails, the “Purge Timer” will stop and the system will go to “Alarm”.

10.1 10.1 When the sequence enters “Purge”, the BMS will start the following timers (see Appendix III):

Purge Timer

When the “Purge Timer” times out, the system will go to “Purge Complete”.


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11.0 11.0 When the sequence enters “Purge Complete” the BMS will send the PCS a signal requesting the following damper/valve positions:

ID Fan Damper low CA Fan Damper low DA Fan Damper low Main Oil Control Valve low Atomizing Steam Blocking Valve Open

11.1 11.1 When the sequence enters “Purge Complete”, the BMS will start the following timers (see Appendix III):

Pre-Ignition Timer

This timer will continue to time out until the limits below are satisfied. While in “Purge Complete” the BMS will evaluate the following limits (See Appendix II) :

Common Limits Pilot Valves Closed Limits Main Valves Closed Limits Flame Not On

The sequence will stop and go to “Alarm” if any of these limits fail during “Purge Complete”. The BMS will also evaluate the following limits:

Low Fire Limits Pilot Limits Atomizing Steam Limits

When these limits are all satisfied, the BMS will go to “PTFI”. If these limits are not satisfied before the Pre-Ignition timer times out, the system will go into Alarm and the purge cycle will have to be repeated.


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12.0 12.0 While in “PTFI”, the BMS will evaluate the following limits (See Appendix II):

Common Limits Low Fire Limits Pilot Limits Main Valve Closed Limits

If any of these limits fails, all ignition and valve outputs will go off and the system will go to “Alarm”.

12.1 12.1 When the sequence enters “PTFI”, the BMS will start the following timers (see Appendix III):

Ignition Timer PTFI Timer

At the same time the BMS will energize the ignition transformer and both pilot blocking valves. The Pilot Blocking valves will open. The BMS will de-energize the ignition transformer when the Ignition Timer times out. When the PTFI Timer times out, the BMS will look for flame. With flame present, the system will proceed to “Pilot Firing”. With no flame present, the system will de-energize the pilot blocking valves and go to “Alarm”.

13.0 13.0 When in “Pilot Firing” firing mode, the system looks for the following limits (See Appendix II) to be satisfied:

Common Limits Low Fire Limits Pilot Limits Main Valves Closed Limits Pilot Valves Open Limits Flame On Atomizing Steam Limits



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13.1 13.1 While in “Pilot Firing” firing mode, the system will continue to energize the pilot blocking valves and will continue to monitor for flame. The sequence will remain in “Pilot Firing” indefinitely until there is either a “Burner Stop” request, limit failure, or an alternate firing mode is selected.

13.2 13.2 If “Oil Firing” has been selected, the system will sequence directly to the selected mode as described beginning with Steps 14.0.

Oil Firing from Pilot Firing

14.0 If “Oil Firing” has been selected, the system will automatically proceed from “Pilot Firing” to “Oil Firing”. If “Oil Firing” has not already been selected, make sure the appropriate limits are satisfied (see Step 8.0) and press the “Oil Select” pushbutton.

14.0 With “Oil Firing” selected and with “Flame On”, the system will go to “MTFI”. While in “MTFI”, the system will look for the following limits (See Appendix II) to be satisfied:

Common Limits Low Fire Limits Pilot Limits Oil Limits Pilot Valve Open Limits Flame On Atomizing Steam Limits


14.1 14.1 When the system enters “MTFI”, the BMS will start the following timers (see Appendix III).

MTFI Timer At the same time, the Atomizing Steam Blocking valve will energize. After a short delay (2 seconds), the Oil Blocking Valve and the Oil Recirculation Valve will also energize. The Oil and Atomizing Steam Blocking Valves will open and the Oil Recirculation Valve will close. The pilot valves will remain energized and open. If at the end of “MTFI", flame is still present, the system will go to “Low Fire Hold”. If flame is not present at the end of “MTFI”, all ignition and valve outputs will go off and the system will go to “Alarm”.


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15.0 15.0 While in “Low Fire Hold”, the system will look for the following limits to be satisfied (See Appendix II):

Common Limits Low Fire Limits Oil Limits Main Valve Open Limits Flame On Atomizing Steam Pressure Not Low

15.1 15.1 When the system enters “Low Fire Hold”, the BMS will start the following timers (see Appendix III).

Low Fire Hold Timer At the same time the pilot valves will de-energize and the Pilot Blocking Valves will close. The system will remain in low fire hold to prove flame stability at the minimum fuel valve setting. If the flame is present at the end of low fire hold, the system will go to ‘Oil Operation‘. If flame is not present at the end of low fire hold, the system will de-energize all fuel valves and go to alarm.

16.0 16.0 When in “Oil Operation” the system will look for the following limits (See Appendix II):

Common Limits Oil Limits Main Valves Open Limits Pilot Valves Closed Limits Flame On

If any of these limits fails, all ignition and valve outputs will go off and the system will go to “Alarm”. Note: If the system is also in “Pilot Relight”, Pilot Valves Closed Limits are not required.

16.1 16.1 The system will remain in Oil Operation until an alternate firing mode is selected, a limit failure occurs, or Burner Stop is pressed.


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Note: The operator should observe the burner firing and flame shape to insure that the burning characteristics have not changed. Defects such as plugged nozzles, worn nozzle ports, broken burner tile, and wet steam can cause flame instability. Corrective action should be taken when abnormal conditions are observed.

17.0 If an alternate firing mode is selected while in “Oil Operation”, the system will first re-light the pilot and then (if or when a main fuel is selected) proceed to the alternate fuel.

17.0

17.1 To select “Pilot Firing” while in “Oil Operation”, make sure that the appropriate manual valves are open (as described in Steps 4 & 6) and press the appropriate Fuel Select pushbutton.

17.1 The system will enter “Start Pilot Relight”.

17.2 17.2 While in “Start Pilot Relight” the system will remain in “Oil Operation” and continue to evaluate and react to the status of the appropriate limits.

17.3 17.3 When the system enters “Start Pilot Relight”, the BMS will also start the following timer (see Appendix III):

Start Pilot Relight Timer

At the same time, the BMS will send the PCS a signal requesting the following damper/valve positions:

ID Fan Damper low CA Fan Damper low DA Fan Damper low Main Control Valve low


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17.4 17.4 The system will look for the following limits in addition to the limits required for “Oil Operation”:

Pilot Limits Low Fire Limits

If these limits are proven within the “Start Pilot Relight” timing (see Appendix III), the system will proceed to “Pilot Relight”. If they are not proven within the “Start Pilot Relight” timing, the system will leave “Start Pilot Relight” and revert back to “Oil Operation” only. A message will display indicating that Pilot Relight failed.

18.0 18.0 When the system enters “Pilot Relight”, the BMS will start the following timers (see Appendix III).

Pilot Relight Timer Main Valve Off Timer

18.1 18.1 While in “Pilot Relight” the BMS will evaluate the status of the following limits (See Appendix II):

Common Limits Pilot Limits Oil Limits Flame On

18.2

18.2 When the system enters “Pilot Relight“, the Ignition transformer and the pilot valves are energized as described in Step 12.1. When the “Ignition Timer” times out, the ignition transformer is de-energized. When the “Main Valve Off Timer” times out, the oil and Atomizing Steam valves are de-energized. When the “Pilot Relight Timer” times out, the BMS will look for flame. With flame present, the system will proceed to “Pilot Firing”. With no flame present, the system will de-energize the pilot blocking valves and go to “Alarm”.

STEAM PURGE


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19.0 “Steam Purge” should be initiated prior to a shutdown when it is expected that the air heater will not be re-started for 20 minutes or more. The objective of the “Steam Purge” is to prevent the oil from hardening in the lines and coking in the burner.

19.0

19.1 “Steam Purge” can only be initiated if the sequence is in the “Pilot Firing” state. Relight the pilot as described in Step 17, then press the “Steam Purge” pushbutton.

19.1 If the “Steam Purge” pushbutton is pressed and the system is not in “Pilot Firing”, Steam Purge will not proceed and the BMS will display a message “Steam Purge Cannot Proceed”. When the sequence enters “Steam Purge”, the BMS will start the following timers:

Steam Purge Timer

At the same time the BMS will energize the Steam Purge Blocking Valve and the valve will open. It will remain open until the “Steam Purge Timer” times out.

19.2 19.2 While in “Steam Purge” the system will remain in “Pilot Firing” and continue to evaluate and react to the status of the appropriate limits.

19.3 19.3 The “Steam Purge” will go to completion unless the “Burner Stop” pushbutton is pressed or one of the “Pilot Firing” limits fails.

CHANGING ATOMIZERS

20.0 When the firing rate has increased to a level high enough to install the full capacity atomizer, manually return the firing mode to “Pilot Firing” as described starting with Step 17.

20.0 The BMS will relight the pilot and shutoff the oil.

20.1 Once the sequence is in “Pilot Firing”, the operator can remove the low capacity atomizer and install the full capacity atomizer. (Refer to the burner manual for atomizer change out procedures.)

20.1


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20.2 Once the full capacity atomizer is installed, return the firing mode to oil operation as described starting with Step 14.0.

20.2 The BMS will relight the main fuel and shutoff the pilot.

BURNER STOP

21.0 To stop the burner, press the “Burner Stop” pushbutton momentarily. Note: A “Steam Purge” should be performed if the burner will be down for any length of time.

21.0 The BMS will de-energize all outputs, and the fuel flow to the burner will stop.

ALARMS & FAULTS

22.0 If the system should go into “Alarm”, all outputs will de-energize and the fuel flow to the burner will stop. The BMS will detect and display the limit that caused the fault.

22.0 At the same time, the BMS will send a signal to the PCS indicating which device caused the failure and what sequence state the system was in at the time of failure.

22.1 Correct the cause of the failure. The alarm is be reset by pushing the “Burner Stop” pushbutton momentarily after the alarm has been corrected.

22.1

22.3 If the Flame Signal Processor goes into fault, press and hold the “Burner Stop” pushbutton for more than 3 seconds

22.3 Pressing and holding the “Burner Stop” pushbutton for more than 3 seconds will clear all alarms, reset the Flame Signal Processor, and return the system to “Idle”.

EMERGENCY COOLING STEAM

23.0 No operator interface required 23.0 The BMS will control two Emergency Cooling Steam valves. One is connected to the combustion air at the burner and the second is connected to the dilution air. In the event of a power failure, the output to these will both go off and the valves will fail open allowing cooling steam to enter the combustion chamber and the dilution air plenum. The valves will be closed at all other times.


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3.2 DEFINITIONS

3.3 DEFINITIONS OF LIMITS

AII.1 The following limits must all be proven satisfied to complete “E-Stop Limits OK”.

AII.1 AII.1 E-Stop #1 is closed E-Stop #2 is closed E-Stop #3 is closed

AII.2 The following limits must all be proven satisfied to complete “ID Fan On”.

AII.2 AII.2 ID Fan motor starter running contact (400-EM-0321) ID Fan Low Pressure Switch (400-PS-0301)

AII.3 The following limits must all be proven satisfied to complete “Combustion Air Fan On”.

AII.3 AII.2 CA Fan motor starter running contact (400-EM-0461) CA Low Pressure Switch (400-PSA-0461)

AII.4 The following limits must all be proven satisfied to complete “DA Fan On”.

AII.4 AII.3 DA Fan motor starter running contact (400-EM-0323) DA Low Pressure Switch (400-PS-0302)

DEFINITION OF ACRONYMS

BMS Burner Management System

CA Combustion Air

DA Dilution Air

ID Induced Draft

MTFI Main Trial For Ignition

PCS Process Control System

PTFI Pilot Trial For Ignition

POC Proof of Closure

VCS Valve Closed Switch

VOS Valve Open Switch


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AII.5 The following limits must all be proven

satisfied to complete “Mill Fan On”. AII.5 Mill Fan motor starter run contact (400-EM-0223)

Mill Fan Pressure Switch (400-PS-0202)

AII.6 The following limits must all be proven satisfied to complete “Pilot Valves Closed”.

AII.6 Pilot SSOV #1 POC Switch (400-PSA-0402) Pilot SSOV #2 POC Switch (400-PSA-0403)

AII.7 The following limits must all be proven satisfied to complete “Pilot Valve Open Limits”.

AII.7 Pilot SSOV #1 VOS Switch (400-GB-0440) Pilot SSOV #2 VOS Switch (400-GB-0441)

AII.8 The following limits must all be proven satisfied to complete “Main Valves Closed Limits”.

AII.8 Main SSOV #1 POC Switch (400-PSA-0412) Main Return VOS Switch (400-GB-0444)

AII.9 The following limits must all be proven satisfied to complete “Main Valves Open Limits”.

AII.9 Main SSOV #1 VOS Switch (400-GB-0414) Main Return VCS Switch (400-GB-0444) Atomizing Steam Blocking Valve Open Switch (400-GB-0445)

AII.10 The following limits must all be proven satisfied to complete “Exhaust Gas Path Clear Limits”.

AII.10

ID Fan On Vent Stack Damper Closed (400-GBS-0472) Mill Fan On Mill By-Pass Damper Open Switch (400-GBS-0163A)

AII.11 The following limits must all be proven made to complete “Common Limits”

AII.11 E-Stop Limits OK ID Fan On (400-EM-0321) CA On (400-EM-0461) DA Fan On (400-EM-0323) Exhaust Gas Path Clear Instrument Air Low Pressure OK (400-PSA-0405) Process Interlocks (from PCS) Process temperature not high (400-TSIA-0468) Flame Signal Processor is not in fault (400-XSIA-0469) PLC not faulted

AII.12 The following limits must all be proven made to complete “Purge Damper Limits”

AII.12 ID Fan Damper Hi switch (400-GBS-0310A) CA Fan Damper Hi switch (400-GBS-0460A) DA Fan Damper Hi switch (400-GBS-0302A) RM Fan Damper Hi Switch (400-GBS-0200A) RM Bypass Damper Open Switch (400-GBS-0163A)

AII.13 The following limits must all be proven made to complete “Purge Limits”

AII.13 Pilot Valve Closed Limits (400-GBS-0440/0441) Main Valve Closed Limits (400-GBS-0414/0442) Main Control Valve Low switch (400-GB-0414) Flame Off (400-XISA-0463/0469) Atomizing Steam Valve Closed (400-GB-0422C)

AII.14 The following limits must all be proven made to complete “Low Fire Limits”

AII.14 CA Fan Damper Low switch (400-GBS-0460C) DA Fan Damper Low switch (400-GBS-0302C)


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ID Fan Low Switch (400-GBS-0310C) Main Control Valve Low Switch (400-GB-0414)

AII.15 The following limits must all be proven made to complete “Pilot Limits”

AII.15 Pilot Air pressure not low (400-PSA-0405) Pilot gas pressure not low (400-PSA-0402) Pilot gas pressure not high (400-PSA-0403)

AII.16 One of the following limits must be proven made to complete “Pump Limits” (See Appendix II)

AII.16 Pump 1 Motor starter running contact or Pump 2 Motor starter running contact

AII.17 The following limits must all be proven made to complete “Oil Limits”

AII.17 Pump Limits Oil Low Pressure Switch (400-PSA-0411) Oil High Pressure Switch (400-PSA-0412) Oil Low Temperature Switch (400-TIS-0413) Oil High Temperature (400-TIS-0413) Low Steam Pressure Switch (400-PSA-0420)

AII.18 The following limits must all be proven made to complete “Atomizing Steam Limits”

AII.18 Atomizing Steam Valve Open (400-GBS-0422) Atomizing Steam Pressure Not Low (400-PSA-0420)

3.4 TIMER SETTINGS

Timer Setting

Oil MTFI 15 sec

Ignition Transformer Time 7 sec

Low Fire Hold Time 15 sec

Purge Start 10 min

Purge Time 15 min

MTFI 15 sec

Pre-Ignition Timer 10 min

Pre-Purge Time 10 min

PRIT 10 sec

PTFI Time 10 sec

Purge Time 15 min

Start Pilot Relight 10 min

Steam Purge Timer 30 sec


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4 ROLLER MILL GROUP The Roller Mill Group consists of the Roller Mill (400-ML-010), variable-speed Mill Drive (400-EM-0009), Classifier (400-CI-015), variable speed Classifier Drive (400-EM-0010), Mill Cyclone (400-CY-020) and ESP Cyclone (400-CY-025). These components are referenced on the following C&ID drawings:

• 8.500742 SHT. 4 (400-01) • 8.500742 SHT. 6 (400-03)

4.1 FUNCTIONAL DESCRIPTION The Roller Mill Group receives wet CRS from Section 200 and generates a dry, partially-calcined ground material for processing in the Calciner Group. All functions in the Roller Mill Group are controlled by the PCS. Primary control and monitoring functions associated with the Roller Mill Group are required for the following purposes:

1. Ensure adequate gas flow through the mill for proper transport of solids, 2. Particle size control for proper mill product particle size distribution, 3. Protect the mill and classifier from excessive temperature.

It is suggested that oil heaters in the mill grinding roller lubrication subsystems are energized at least one hour before system startup is planned to ensure fluid temperatures satisfy start interlocks for the Roller Mill Group. Failure to provide this preheat period may result in a delay of mill startup.

4.1.1 ROLLER MILL PREHEAT The roller mill must be preheated before CRS processing can begin. This preheat operation cannot commence until the following have been satisfied:

1. Calciner Group has successfully entered a System Idle mode of operation to remove the interlock on the mill fan inlet damper closed position (400-GIS-0261). System Idle mode is confirmed by the position of the oil control valve 400-TCV-0131.

2. The rollers are in their raised position as indicated by position switches 400-GBS-0007, 400-GBS-0009 and 400-GBS-0011 (mill hydraulic system must be activated),

3. The Table Water Spray control valve (400-FCV-0001) closed limit switch is satisfied (400-GBS-0001),

4. The Upper Mill Water Spray control valve (400-TCV-0004) closed limit switch is satisfied (400-GBS-0002).

The mill preheat process interlock on the mill fan damper is then removed and the operator can manually position the mill fan inlet damper valve at an opening of 3% to supply gas for the mill preheat after the mill inlet damper (400-DA-015) is opened. Once a temperature of 77°C is detected at 400-TICSA-0004, the interlock on mill start associated with the preheat requirement is removed. If a temperature >90°C is detected before the start of the CRS feed system, the PCS will force the mill fan inlet damper and mill inlet damper to a closed position. In the event of a hot mill restart, the temperature at 400-TICSA-0004 may already be >77°C and will satisfy the interlock requirement.


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4.1.2 CRS FEED START The CRS feed is metered into the mill via weigh belt 200-FD-085 through the mill rotary airlock 400-AL-010. Feed to the mill cannot be started until the following conditions are satisfied:

1. The Calciner Group is operating in a System Idle mode, 2. A minimum calciner collection cyclone off gas temperature of 275°C (400-XY-0131) is attained

under the System Idle conditions, 3. There is not a low or low-low CRS level indication in CRS feed bin 200-BN-085, 4. Cyclone discharge valves are started and operating (400-AL-060, 400-AL-065, 400-AL-020 and 400-

AL-025), 5. The calciner cyclone discharge diverter gate 400-GA-060 is in a closed position (400-GBS-0154B) to

direct the calciner product to the crystallizer circuit (there is a password protected provision to override this requirement to enable material discharge to the dump tank during system testing),

6. The ESP fields (400-EP-030) are energized, 7. The ESP dust screw (400-SC-040) and discharge valve (400-AL-030) are operating, 8. The roller mill is preheated to an outlet temperature of >77°C, 9. There are no interlocks preventing the start of the mill system, 10. The classifier drive 400-EU-0010 is running and classifier rotation is confirmed by speed indicator

400-SI-0010, Once all conditions are satisfied and a permissive is given by the PCS for a CRS feed start, the operator provides a “CRS Feed Start” command. The Roller Mill Group engages in the following automatic sequence:

1. Check the status of 400-EM-0524. Start the mill drive lubrication pump motor if not running. 2. Check the status of the Hydraulic Spring System:

2.1. If activated, continue sequence. 2.2. If not active, prompt the operator to start the Hydraulic Spring System. Upon activation the rolls will move to their upper position.

3. Prompt operator “Mill Precharge Required”. Select “Yes” or “No”. 4. Operator response to “Mill Precharge Required”:

4.1. “Yes” – 4.1.1. Start mill rotary airlock 400-AL-010 motor EM0003 if not already operational. Check

for shaft motion at speed sensor 400-SSA-0003: 4.1.1.1. Motion detected within 5 seconds - continue sequence 4.1.1.2. Motion not detected at 5 seconds – alarm and stop sequence

4.1.2. Start CRS feed weigh belt 200-FD-085 at a rate of 75 mtph. Run feed belt for approximately 30 seconds (exact time TBD during commissioning) and then stop.

4.2. “No” – Continue sequence. 5. Start mill rotary airlock 400-AL-010 motor EM0003 if not already running. Check for shaft motion

at speed sensor 400-SSA-0003: 5.1. Motion detected within 5 seconds - continue sequence 5.2. Motion not detected at 5 seconds – alarm and stop sequence

6. Automatically activate the upper roller mill spray temperature control loop (400-CTL-05). 7. Open the mill inlet damper 400-DA-015:

7.1. Open limit 400-GBS-0165 satisfied, continue sequence. 7.2. Open limit 400-GBS-0165 not satisfied, stop sequence and alarm.

8. Open the mill fan inlet damper 400-DA-010 to TBD% open to establish minimum mill airflow requirements. Once the mill cyclone (400-CY-020) differential pressure (400-PDICSA-0200) exceeds


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50 mm WG the interlock is removed on mill drive 400-EU-0009 and the upper roller mill spray temperature control loop (400-CTL-05).

9. Immediately start mill drive 400-EU-0009 and ramp to the set point level at the maximum rate permitted by the drive (RPM set point can be adjusted by operator): 9.1. Drive at target set point – continue sequence 9.2. Drive not at target set point after 30 seconds (may be adjusted during commissioning) – alarm,

stop sequence, close mill inlet damper (400-DA-015) and close mill fan inlet damper (400-DA-010).

10. De-energize Solenoid 6S (400-XSV-1103) in mill Hydraulic Spring System 400-HP-010 as soon as the mill drive is activated to lower the three rolls onto the material bed (this solenoid remains de-energized during normal mill operation). The rate at which the rollers are lowered is adjusted during commissioning such that the rolls engage the material load on the bed as soon as the mill drive reaches the set point speed. 10.1. No high roller indication after 10 seconds - continue sequence. 10.2. High roller indication after 10 seconds - alarm, stop sequence, raise mill rollers (see Section

10.1.2), stop mill main drive (400-EU-0009), close mill inlet damper (400-DA-015) and close mill fan inlet damper (400-DA-010).

11. After a delay of approximately 30 seconds (exact timing TBD during commissioning), start the CRS feed weigh belt 200-FD-085 at a rate of 75 mtph. 11.1. Feed weight belt motor running – continue sequence 11.2. No motor operation detected – alarm, stop sequence, raise mill rollers (see Section 10.1.2), stop

mill main drive (400-EU-0009), close mill inlet damper (400-DA-015) and close mill fan inlet damper (400-DA-010).

12. Remove interlock on the Mill Table water spray. 13. After a delay of 10 seconds (exact delay time TBD during commissioning) following de-energizing of

Solenoid 6S (400-XSV-1103), energize Solenoid 8s (400-XSV-1102) in mill Hydraulic Spring System 400-HP-010 for normal operation. This solenoid remains energized during normal mill operation.

14. Check circuit hydraulic pressure (400-PISA-1107) – this initial adjustment develops a “soft” grinding mode of operation to minimize the potential for grinding instability during initial startup: 14.1. If less than 0.8 x accumulator pressure, start hydraulic pump motor 400-EM-1107 in Hydraulic

Spring System 400-HP-010. Stop motor 400-EM-1107 when the target pressure at 400-PISA-1107 is obtained.

14.2. If greater than 0.8 x accumulator pressure, de-energize Solenoid 5S (400-XSV-1101) until the target pressure at 400-PISA-1107 is obtained.

15. Following a mill operating period of 5 minutes (exact interval TBD during commissioning), adjust the hydraulic pressure to the operator specified set point.

Following a mill operating period of 20 minutes the roller lube system pump (400-LU-011A, 400-LU-011B and 400-LU-011C) motors (400-EM-0605, 400-EM-0612, 400-EM-0704, 400-EM-0708, 400-EM-0804, 400-EM-0808) are started automatically. Roller Mill Group operation under “Feed Start” conditions may continue as long as the following conditions are satisfied:

1. The pressure differential across cyclone 400-CY-020 as measured by transducer 400-PDISCA-0200 is greater than 75 mm WG,

2. Mill vibration is below the high-high limit of 15 mm/s as indicated by 400-XISA-0005, 3. The rollers do not reach their low limits indicated by 400-GBSA-0006, 400-GBSA-0008 and 400-

GBSA-0010,


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4. Mill motor winding and bearing temperatures are below high-high levels (400-TISA-0020-27), 5. Mill motor power draw is below the high-high level (400-EISA-I-0009), 6. Classifier motor power draw is below the high-high level (400-EISA-I-0010), 7. Classifier bearing temperatures are below high-high levels (400-TISA-0001 and 400-TISA-0002).

If any of these limits are exceeded, the Roller Mill Group is shutdown and the Calciner Group is returned to a System Idle mode and the operator is prompted with the option for a complete system shutdown.

4.1.3 CRS CAPACITY INCREASES The CRS feed rate to the Roller Mill Group may be increased manually by the operator once the following control loops are engaged. These control loops include:

1. 400-CTL-01: Calciner exit temperature (Calciner Group) 2. 400-CTL-02: Calciner inlet temperature (Process Air Group) 3. 400-CTL-03: Mill Flow (Process Air Group) 4. 400-CTL-04: Calciner pressure (Process Air Group)

The CRS rate may be increased in increments selected by the operator, up to a maximum rate of 106 mtph. This maximum rate is password protected in the PCS and provides protection against over-feeding the system. An over-feeding situation will result in low temperature alarm conditions, instability and an eventual feed stop condition. PCS will prevent increases to the CRS feed rate if a low temperature condition of <90°C is encountered at the mill outlet (400-TICSA-0004).

4.1.4 CLASSIFIER SPEED The classifier speed set point may be adjusted manually by the operator at any time. An option to password protect this speed set point should be provided given the importance of particle size control in the process.

4.1.5 MILL FEED ROTARY VALVE The mill feed Rotary Valve 400-AL-010 is utilized to maintain an airlock on the mill feed inlet duct. This valve is started automatically when a Start Feed command is issued by the operator unless a local maintenance switch is thrown. In this case, the PCS shall indicate that a Start Feed sequence is not available. Once a Start Feed command is accepted, the operation of the rotary valve is proved by the PCS before starting the CRS feed system (200-FD-085). The following sequence is performed during normal start, run and stop cycles for the rotary valve:

1. Check for emergency stop and maintenance interlocks. If not present, display a start permissive on the PCS screen,

2. The operator manual selects the rotary valve and selects start (Note: the valve will be started automatically by the PCS if not running at the time that a CRS Start Feed command is given),

3. The PCS sends a start signal to the motor starter for 400-EM-0125, 4. The PCS checks for a valve motion confirmation from 400-SSA-0101. If this is not received in 5

seconds, the motor is de-energized and an alarm is displayed, 5. Once a successful start is achieved, the valve is de-energized via:

a. A loss of motion detection,


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b. Motor fault, c. Emergency shutdown action, d. The local maintenance switch is engaged.

4.1.6 NORMAL ROLLER MILL SHUTDOWN A normal Roller Mill Group shutdown will involve the operator manually reducing the CRS feed rate to the minimum level of 75 mtph. Once this reduction has been made, the operator selects “Roller Mill Shutdown”. The PCS performs the following actions in sequence:

1. Close Upper Mill Water Spray valve (400-TCV-0004) and Mill Table Water Spray valve (400-FCV-0001),

2. Deactivate control loop 400-CTL-03. 3. Stop the CRS feed system 200-FD-085 and mill feed rotary valve 400-AL-010, 4. Close the mill fan inlet damper 400-DA-010 and mill inlet damper 400-DA-015, 5. Raise the mill rollers:

a. De-energize Solenoid 8S (400-XSV-1102), b. Energize Solenoid 6S (400-XSV-1103), c. Energize Solenoid 4S (400-XSV-1104), d. Start pump motor 400-EM-1107, e. Stop motor 400-EM-1107 when roller hit their high limit switches 400-GBS-0007, 400-GBS-

0009 and 400-GBS-0011, f. De-energize Solenoid 4S (400-XSV-1104).

6. Stop the main mill drive motor 400-EM-0009. If the mill is to remain idle for an extended period of time, the following actions should be performed by the operator: 1. Stop main drive lube pump motor 400-EM-0524. 2. Stop the classifier drive motor 400-EM-0010. 3. Stop the classifier lube pump motor 400-EM-0015. 4. Stop roller lube system pump (400-LU-011A, 400-LU-011B and 400-LU-011C) motors (400-EM-

0605, 400-EM-0612, 400-EM-0704, 400-EM-0708, 400-EM-0804, 400-EM-0808).

4.1.7 EMERGENCY ROLLER MILL SHUTDOWN The Roller Mill Group will be taken offline in the event that one of the following conditions occurs:

1. A burner stop action by the BMS, 2. Any condition that moves the Calciner Group into a Low Firing/System Idle mode of operation or

shutdown (see Section 2.1) including a “Feed Stop” command from the operator, 3. A high-high mill off gas temperature (400-TICSA-0004), 4. The pressure differential across cyclone 400-CY-020 as measured by transducer 400-PDISCA-0200 is

<50 mm WG for more than 5 seconds, 5. Mill vibration is above the high-high limit of 15 mm/s for >1 second as indicated by 400-XISA-

0005, 6. Any of the three rollers reach their low limits for >5 seconds as indicated by 400-GBSA-0006, 400-

GBSA-0008 or 400-GBSA-0010,


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7. Mill motor winding or bearing temperatures reach high-high levels (400-TISA-0020-27), 8. Mill motor power draw reaches the high-high level (400-EISA-I-0009), 9. Classifier motor power draw reaches the high-high level (400-EISA-I-0010), 10. A classifier bearing temperature reaches a high-high level (400-TISA-0001 or 400-TISA-0002).

When one or more of these conditions occur, the following actions are taken by the PCS:

1. Close Upper Mill Water Spray valve (400-TCV-0004) and Mill Table Water Spray valve (400-FCV-0001),

2. De-energize the mill fan motor 400-EM-0223 and close mill fan inlet damper 400-DA-010, 3. Close the mill inlet damper 400-DA-085, 4. Stop the CRS feed system 200-FD-085 and mill feed rotary valve 400-AL-010, 5. Raise the mill rollers:

a. De-energize Solenoid 8S (400-XSV-1102), b. Energize Solenoid 6S (400-XSV-1103), c. Energize Solenoid 4S (400-XSV-1104), d. Start pump motor 400-EM-1107, e. Stop motor 400-EM-1107when roller hit their high limit switches 400-GBS-0007, 400-GBS-

0009 and 400-GBS-0011, f. De-energize Solenoid 4S (400-XSV-1104).

6. Stop the main mill drive motor 400-EM-0009, 7. Stop main drive lube pump motor 400-EM-0524 one minute after stopping the main mill drive

motor 400-EM-0009. 8. Stop the classifier drive motor 400-EM-0010, 9. Stop the classifier drive lube pump motor 400-EM-0015 one minute after stopping the classifier

drive motor 400-EM-0010, 10. Stop roller lube system pump (400-LU-011A, 400-LU-011B and 400-LU-011C) motors (400-EM-

0605, 400-EM-0612, 400-EM-0704, 400-EM-0708, 400-EM-0804, 400-EM-0808).

4.2 EQUIPMENT/INSTRUMENT SUMMARY The Roller Mill Group consists of the following components and attached instruments and equipment: Roller Mill Group


Roller Mill 400-ML-010

Main Drive Motor X 400-EM-0009

Main Drive Variable Frequency Drive X 400-EU-0009

Main Drive Motor Power Draw X 400-EISA-I-0009

Main Drive Motor Winding Temperatures (6) X 400-TISA-0022-27

Main drive Motor Bearing Temperatures (2) X 400-TISA-0020-21

Mill Louver Differential Pressure X 400-PDICA-0035

Roller #1 High Position Switch X 400-GBS-0007




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Roller #1 Low Position Switch X 400-GBSA-0006



Mill Body Vibration Monitor X 400-XISA-0005

Mill Differential Pressure X 400-PDIA-0001

Mill Feed Rotary Valve Motor X 400-EM-0003

Mill Feed Rotary Valve Speed Switch X 400-SSA-0003

Mill Off Gas Temperature X 400-TICSA-0004

Mill Off Gas Temperature Switch X 400-TSA-0005

Dynamic Classifier 400-CI-015

Drive Motor X 400-EM-0010

Motor Power Draw X 400-EISA-I-0010

Variable Frequency Drive 400-EU-0010

Rotor Speed X 400-SI-0010

Classifier Bearing Temperatures (2) X 400-TISA-0001-02

Mill Cyclone 400-CY-020

Cyclone Differential Pressure X 400-PDICSA-0200

Cone Temperature X 400-TI-0203

Cone Pressure X 400-PIA-0201

Discharge Rotary Valve 400-AL-020

Discharge Rotary Valve Motor X 400-EM-0222

Discharge Rotary Valve Speed Switch X 400-SSA-0260

ESP Cyclone 400-CY-025

Cyclone Differential Pressure X 400-PDIA-0249

Cone Temperature X 400-TI-0243

Cone Pressure X 400-PIA-0244

Discharge Rotary Valve 400-AL-025

Discharge Rotary Valve Motor X 400-EM-0224

Discharge Rotary Valve Speed Switch X 400-SSA-0250

Off Gas Temperature X 400-TISA-0250


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4.3 CONTROL LOOPS

4.3.1 ROLLER MILL GAS FLOW CONTROL The roller mill gas flow control loop (400-CTL-03) may be engaged by the operator once a “CRS Feed Start” has been performed and stable system operation is observed. The default differential pressure value for this loop is 104mm WG, but this may be adjusted by the operator (minimum set point of 85 accepted by the PCS) to control the mill off gas temperature at desired levels as indicated at 400-TICSA-0004. The PCS will not allow this control loop to be engaged unless a “CRS Feed Start” condition is detected. Controller response:

1. If the actual cyclone differential pressure is less than the set point value: a. Slowly open mill fan damper 400-DA-010 until the set point is satisfied.

2. If the actual differential is greater than the set point value: a. Slowly close the mill fan damper 400-DA-010 until the set point is satisfied.

This control loop is deactivated only by the PCS when the roller mill is shutdown or by the operator.

4.3.2 MILL OUTLET GAS TEMPERATURE CONTROL The roller mill outlet gas temperature control loop (400-CTL-05) activated by the PCS during the “CRS Feed Start” sequence. This loop adjusts the position of flow control valve 400-TCV-0004 to control the flow rate of water delivered to the upper mill water spray in order to control the mill off gas temperature measured at 400-TISCA-0004. The default set point for this control loop is 100°C, but this value may be increased by the operator up to a maximum temperature of 110°C. Controller response:

1. If the roller mill off gas temperature 400-TISCA-0004 is less than the set point value: a. Slowly close water flow control valve 400-TCV-0004 until the set point is satisfied or fully

closed. 2. If the mill off gas temperature 400-TISCA-0004 is greater than the set point value:

a. Slowly open water flow control valve 400-TCV-0004 until the set point is satisfied or fully open.

This control loop is automatically deactivated only by the PCS when the mill system is stopped.

4.3.3 MILL TABLE SPEED CONTROL The roller mill table speed control loop (400-CTL-06) may be used by the operators at their discretion. The function of this loop is to stabilize the material loading in the mill as indicated by the mill louver differential pressure (400-PDICA-0035) by adjusting the speed of the mill table. As the material loading in the mill increases, the louver pressure drop increases. This control offers the benefit of reducing the potential of a low mill loading situation that will allow the rollers to move to a low level position and force a mill shutdown. Likewise, it also limits the potential for a high mill loading situation that will lead to operating instability, poor grinding performance and possible mill drive overload. The differential pressure set point is set by the operator. Controller response:

1. If the roller mill louver differential pressure 400-PDICA-0035 is greater than the operator set point:


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a. Increase the mill table speed via variable frequency drive 400-EU-0009. 2. If the roller mill louver differential pressure 400-PDICA-0035 is less than the operator set point:

b. Decrease the mill table speed via variable frequency drive 400-EU-0009. This control loop can be deactivated at the discretion of the operator.


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4.4 ALARMS


Device Analog Set Point Debounce Value

Low Low 66°C 0 sec

Low 77°C 0 sec

High 100°C 0 sec Mill Off Gas Temperature

High High

400-TICSA-0004

115°C 0 sec

Mill Off Gas Temperature High High 400-TSA-0005 115°C 0 sec

High 400-XISA-0005 12 mm/s 0 sec Mill Vibration

High High 400-XISA-0005 15 mm/s 1 sec

Roller #1 Position Low 400-GBSA-0006 - 5 sec



Low Low 400-PDICA-0035 <200mm WG 0 sec

Low 400-PDICA-0035 <400mm WG 0 sec

High 400-PDICA-0035 >700mm WG 0 sec Mill Louver Pressure Differential

High High 400-PDICA-0035 >800mm WG 0 sec

Low 400-PDIA-0001 <300mm WG 0 sec Mill Differential Pressure

High 400-PDIA-0001 >800mm WG 0 sec

High 400-TISA-0022-27 >120°C 0 sec Main Mill Motor Winding Temperatures High High 400-TISA-0022-27 160°C 0 sec

High 400-TISA-0020-21 >85°C 0 sec Main Mill Motor Bearing Temperatures High High 400-TISA-0020-21 90°C 0 sec

High 400-EISA-I-0009 >TBD kW 5 sec Main Mill Motor Power Draw High High 400-EISA-I-0009 TBD kW 5 sec

High 400-EISA-I-0010 >TBD kW 5 sec Classifier Motor Power Draw High High 400-EISA-I-0010 TBD kW 5 sec

High 400-TISA-0001-02 93°C 0 sec Classifier Rotor Bearing Temperatures High High 400-TISA-0001-02 99°C 0 sec

Mill Feed Rotary Valve Speed Switch Low 400-SSA-0003 - 5 sec

High 400-PDICSA-0200 >150mm WG 0 sec

Low 400-PDICSA-0200 <75mm WG 0 sec Mill Cyclone Differential Pressure

Low Low 400-PDICSA-0200 <50mm WG 5 sec

Mill Cyclone Cone High 400-PIA-0201 >(-700)mm WG 0 sec


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Pressure High High 400-PIA-0201 >(-500)mm WG 0 sec

Mill Cyclone Rotary Valve Speed Low 400-SSA-0260 - 5 sec

ESP Cyclone Differential Pressure High 400-PDIA-0249 >200mm WG 5 sec

Low 400-TISA-0250 <100°C 0 sec

High 400-TISA-0250 >310°C 0 sec ESP Cyclone Overflow Temperature

High High 400-TISA-0250 325°C 2 sec

ESP Cyclone Rotary Valve Speed Low 400-SSA-0250 - 5 sec

High 400-PIA-0244 >(-75)mm WG 0 sec ESP Cyclone Cone Pressure High High 400-PIA-0244 >(-25)mm WG 0 sec

4.5 INTERLOCKS

Interlock Type Equipment Signals


X X

Z X

Sample: (X AND Y AND Z); Z to start, X AND Y to run, X for safety shutdown Y X

No Active Alarms in the Roller Mill Group, Roller Mill Hydraulic Group or Lubrication Group

X

Rollers in High Position (400-GBS-0007,0009,0011) X

Roller Mill Lubrication Pump 400-EM-0524 Running X X

Roller Mill Outlet Gas Temperature 400-TICSA-0004 >77°C X

Roller Mill Outlet Gas Temperature 400-TICSA-0004 >66°C X

Mill Cyclone dP 400-PDICSA-0200 >50 mm WG X X

Motor Power Draw NOT High High (400-EISA-I-0009) X

Motor Bearing Temps NOT High High (400-TISA-0020-21) X

Main Mill Drive (400-EM-0009)

Motor Winding Temps NOT High High (400-TISA-0022-27) X


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No Active Alarm Conditions in the Classifier and Classifier Lubrication Circuits X

Rotor Bearing Temps NOT High High (400-TISA-0001-0002) X

No Classifier Lubrication Circuit High High Temperature Alarms X

No Classifier Lubrication Circuit Low Low Pressure Alarm X

No Classifier Lubrication Circuit Low Low Flow Alarm X

Classifier Mill Drive (400-EM-0010)

Motor Power Draw NOT High High (400-EISA-I-0010) X

Mill Upper Water Spray Control Loop Mill Cyclone dP >50mm WG X X

5 PROCESS AIR GROUP The Process Air Group consists of the Combustion Air Fan (400-FN-050), Combustion Air Fan Damper (400-DA-050), Roller Mill Inlet Damper (400-DA-015), Roller Mill Fan (400-FN-020), Roller Mill Fan Damper (400-DA-010), ESP ID Fan (400-FN-030), ESP ID Fan Damper (400-DA-030), Dilution Air Fan (400-FN-035), Dilution Air Fan Damper (400-DA-035), Grid Cooling Air Fan (400-FN-055) and Mill Bypass Damper (400-DA-020). These components are referenced on the following C&ID drawings:

• 8.500742 SHT. 5 (400-02) • 8.500742 SHT. 6 (400-03) • 8.500742 SHT. 7 (400-04) • 8.500742 SHT. 8 (400-05)

5.1 FUNCTIONAL DESCRIPTION The Process Air Group controls the flow rate of air into the calciner system, the recirculation of air from the stack to the calciner inlet, the flow of cooling air to the grid plate, mill air flow, and the calciner exit pressure. A group start may be performed when all fans are idle or individually by the operator. Starting of a fan is contingent upon its damper being closed and no related safety interlocks present. All control of the components in the Process Air Group is performed by the PCS.

5.1.1 FAN GROUP START A fan group start may be requested by the operator when all fans are off, tempering tee (400-DA-034) is open for ambient air intake and there are no interlocks present. The following actions are performed by the PCS when a “Fan Group Start” command is received:


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1. Close dampers 400-DA-050, 400-DA-010, 400-DA-030, and 400-DA-035. Check closed contacts at switches 400-GIS-0261, 400-GBS-0130B, 400-GBS-0302B, and 400-GBS-0460B.

2. Move tempering tee 400-DA-034 in its full open position such that switch 400-GIS-0328 is closed. 3. Move mill bypass damper 400-DA-020 to its full open position as indicated by 400-GI-0163. 4. Start ESP ID fan 400-FN-030 motor 400-EM-0321. Wait 60 seconds after contact is proved. 5. Move the ESP ID fan damper 400-DA-030 to 5% open. 6. Start dilution air fan 400-FN-035 motor 400-EM-0323. Wait 60 seconds after contact is proved. 7. Start mill fan 400-FN-020 motor 400-EM-0223. Wait 60 seconds after contact is proved. 8. Start combustion air fan 400-FN-050 motor 400-EM-0461. Wait 60 seconds after contact is proved. 9. Start grid cooling air fan 400-FN-055 motor 400-EM-0124.

5.1.2 INDIVIDUAL FAN START All fans may be started individually once the tempering tee (400-DA-034) is open for ambient air intake. Once one or more fans are started, the “Fan Group Start” option is not available. Once a fan is started, the operator may manually adjust the position of the fan’s associated damper until a “Start Purge” command is issued by the operator. The PCS will take over full control of all dampers after this command is issued. The following sequence occurs when an individual fan is started. This example utilizes the ESP ID fan, but the same sequence pertains to all fan starts except for the grid cooling air fan. This fan has a manual damper that does not require closure before starting the fan.

1. Select the ESP ID fan (400-FN-030) icon on the display, 2. Select “Start” from the menu, 3. The PCS checks the position of damper 400-DA-030. If not closed as per a contact in switch 400-

GBS-0130B, the PCS will actuate the damper and move it to its closed position until the contact is made,

4. The PCS sends a start command for the motor controller and checks for a contact in motor 400-EM-0321 to confirm operation,

5. The PCS waits 60 seconds and then releases control of the damper to the operator.

5.1.3 SYSTEM SHUTDOWN The following sequence applies to the Process Air Group during a system shutdown situation:

1. Mill fan 400-FN-020 motor 400-EM-0223 is de-energized, 2. Mill fan inlet damper 400-DA-010 and mill inlet damper 400-DA-015 are closed, 3. Combustion air fan damper 400-DA-050 is moved to a position of 20% open, 4. Dilution air fan damper 400-DA-035 is moved to a position of 20% open, 5. ESP ID fan damper 400-DA-030 is moved to a position of 20% open, 6. Tempering tee 400-DA-034 is moved to 100% ambient air intake.

This arrangement supplies required cooling air to the burner and air heater jacket at the minimum allowable air flow rate.

5.2 EQUIPMENT/INSTRUMENT SUMMARY The Process Air Group consists of the following components and attached instruments and equipment:


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Process Air Group


Combustion Air Fan 400-FN-050

Fan Motor X 400-EM-0461

Fan Motor Winding Temperatures (6) X 400-TISA-0482-87

Fan Motor Bearing Temperatures (2) X 400-TISA-0480-81

Fan Speed Switch X 400-SS-0401

Modulating Damper 400-DA-050

Damper Positioner Motor 400-EM-0460

Damper Position Controller X 400-FCV-0460

Damper Position Indication X 400-GIS-0460

Damper Purge Position Switch X 400-GBS-0460A

Damper Closed Position Switch X 400-GBS-0460B

Damper Low Fire Position Switch X 400-GBS-0460C

Combustion Air Flow Measurement X 400-FFIC-0460

Fan Outlet Pressure Switch 400-PSA-0462

Dilution Air Fan 400-FN-035


Fan Motor Power Draw X 400-EIA-I-0323



Fan Bearing Temperatures (2) X 400-TISA-0331-32

Fan Inlet Pressure Switch X 400-PS-0302





Damper Position Controller X 400-TCV-0140




Dilution Air Flow Measurement X 400-FIA-0301

Tempering Tee 400-DA-034

Motor Actuator X 400-HIC-0328


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Motor X 400-EM-0328

Position Indication X 400-GIS-0328

Position Switches O/C X 400-GBS-0328A/B

ESP ID Fan 400-FN-030





Fan Vibration X 400-XISA-0312-13



Fan Inlet Pressure Switch 400-PS-0301



Damper Position Controller X 400-PCV-0130




Roller Mill Fan 400-FN-020





Fan Vibration X 400-XISA-0221-22



Fan Inlet Pressure Switch X 400-PS-0202



Damper Position Controller X 400-PDCV-0200



Damper Differential Pressure X 400-PDIA-0262

Mill Bypass Damper 400-DA-020

Bypass Damper Positioner Motor 400-EM-0121


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Mill Bypass Damper Position Controller X 400-HIC-0163

Mill Bypass Damper Position Indication X 400-GI-0163

Mill Bypass Damper Position Indication X 400-GBS-0163A

Mill Bypass Temperature X 400-TI-0160

Roller Mill Inlet Damper 400-DA-015


Damper Position Switches O/C X 400-GBS-0165

Grid Cooling Air Fan 400-FN-055


Manual Fan Damper 400-DA-055

Fan Inlet Flow Indicator X 400-FI-0137

5.3 CONTROL LOOPS

5.3.1 CALCINER EXIT PRESSURE CONTROL The pressure level at the calciner exit location (400-PICA-0130) is controlled by adjusting the position of the ESP ID fan inlet damper (400-DA-030). This pressure control loop (400-CTL-04) may be engaged by the operator once a “CRS Feed Start” has been performed and has stabilized. The default pressure value for this loop is -13mm WG, but this may be adjusted by the operator (minimum set point of -5mm WG accepted by the PCS). The PCS will not allow this control loop to be engaged unless a “CRS Feed Start” condition is detected. Controller response:

1. If the actual calciner exit pressure is less than the set point value: b. Slowly close the ESP ID fan damper 400-DA-030 until the set point is satisfied.

2. If the actual calciner exit pressure is greater than the set point value: c. Slowly open the ESP ID fan damper 400-DA-030 until the set point is satisfied.

5.3.2 ROLLER MILL GAS FLOW CONTROL The roller mill gas flow control loop (400-CTL-03) may be engaged by the operator once a “CRS Feed Start” has been performed and stable system operation is observed. The default differential pressure value for this loop is 104mm WG, but this may be adjusted by the operator (minimum set point of 75 accepted by the PCS) to control the mill off gas temperature at desired levels as indicated at 400-TICSA-0004. The PCS will not allow this control loop to be engaged unless a “CRS Feed Start” condition is detected. Controller response:

1. If the actual cyclone differential pressure is less than the set point value: d. Slowly open mill fan damper 400-DA-010 until the set point is satisfied.

2. If the actual differential is greater than the set point value: e. Slowly close the mill fan damper 400-DA-010 until the set point is satisfied.


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This control loop is deactivated only by the PCS when the roller mill is shutdown or by the operator.

5.4 ALARMS



Mill Fan Damper Pressure Differential

High (400-CTL-03 Activated) 400-PDIA-0262 500 mm WG 5 sec

High 400-XISA-0221-22 >12 mm/s 0 sec Mill Fan Vibration

High High 400-XISA-0221-22 15 mm/s 1 sec

High 400-TISA-0225-26 100°C 0 sec Mill Fan Bearing Temperature High High 400-TISA-0225-26 110°C 0 sec

High 400-TISA-0227-28 85°C 0 sec Mill Fan Motor Bearing Temperature High High 400-TISA-0227-28 90°C 0 sec

High 400-TISA-0229-34 120°C 0 sec Mill Fan Motor Winding Temperature High High 400-TISA-0229-34 160°C 0 sec

Mill Fan Motor Power Draw High 400-EIA-I-0223 870 kW 2 sec

High 400-TISA-0480-81 85°C 0 sec Combustion Air Fan Motor Bearing Temperature High High 400-TISA-0480-81 90°C 0 sec

High 400-TISA-0482-87 120°C 0 sec Combustion Air Fan Motor Winding Temperature High High 400-TISA-0482-87 160°C 0 sec

Combustion Air Fan Pressure Switch

Open Following a Start Command 400-PSA-0461 - 5 sec

High 400-XISA-0312-13 >12 mm/s 0 sec ESP ID Fan Vibration

High High 400-XISA-0312-13 15 mm/s 1 sec

High 400-TISA-0312-13 100°C 0 sec ESP ID Fan Bearing Temperature High High 400-TISA-0312-13 110°C 0 sec

High 400-TISA-0314-15 85°C 0 sec ESP ID Fan Motor Bearing Temperature High High 400-TISA-0314-15 90°C 0 sec

High 400-TISA-0316-21 120°C 0 sec ESP ID Fan Motor Winding Temperature High High 400-TISA-0316-21 160°C 0 sec

ESP ID Fan Power Draw High 400-EIA-I-0321 825 kW 2 sec

Low 400-PIA-0326 <-100mm WG 5 sec ESP ID Fan Outlet Pressure High 400-PIA-0326 >100mm WG 5 sec

High 400-TISA-0327 140°C 2 sec ESP ID Fan Outlet Temperature High High 400-TISA-0327 150°C 5 sec


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High 400-TISA-0331-32 100°C 0 sec Dilution Air Fan Bearing Temperature High High 400-TISA-0331-32 110°C 0 sec

High 400-TISA-0333-34 85°C 0 sec Dilution Air Fan Motor Bearing Temperature High High 400-TISA-0333-34 90°C 0 sec

High 400-TISA-0335-40 120°C 0 sec Dilution Air Fan Motor Winding Temperature High High 400-TISA-0335-40 160°C 0 sec

Dilution Air Fan Power Draw High 400-EIA-I-0323 350 kW 2 sec

5.5 INTERLOCKS



X X X


Motor Bearing Temps NOT High High X

Motor Winding Temps NOT High High X

Fan Bearing Temps NOT High High X

Fan Vibration NOT High High X

Inlet Damper in Closed Position X

Fan Motor Operation (400-EM-0223,0321,0323,0461)

Tempering Tee (400-DA-034) Open Switch Contact (400-GIS-0328) X

Process Fan Group Start Sequence Fan Motors (400-EM-0223, 0321,0323,0461) De-energized X

Mill Fan Motor Running (400-EM-0223) Mill Exit Temperature NOT High High (400-TICSA-0004) X

Calciner Operating in a System Idle Mode X

Mill Table Water Spray Valve Closed (400-GBS-0001) X

Mill Body Water Spray Valve Closed (400-GBS-0002) X

Mill Damper (400-DA-010) Manual Positioning

Mill Outlet Temperature NOT High (400-TICSA-0004) X X


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6 ESP GROUP The ESP Group consists of a 4-compartment Electrostatic Precipitator (400-EP-030), ESP Dust Screw (400-SC-040) and ESP Dust Purge Valve (400-AL-030). These components are referenced on the following C&ID drawings:

• 8.500742 SHT. 7 (400-04) • 8.500742 SHT. 14 (400-11)

6.1 FUNCTIONAL DESCRIPTION The ESP Group removes the fine particulate present in the process gas stream following final solids collection in the ESP cyclone. The dust is drawn to statically-charged plates located in four compartments placed in series. This dust cake is periodically removed from the plates by a mechanical rapping system and, upon release, falls into the lower collection hopper. A horizontal screw collected the material and delivers it to two potential discharge locations. The first discharge location delivers the dust to a pneumatic conveying circuit (400-GB-040), which transports the dust to a collection hopper in preparation for calciner injection. Dust discharged from the second location is transported to a conditioning/wetting circuit. A carbon monoxide monitor is placed in the calciner plenum. The ESP field power is reduced in the event of a high CO alarm and shutdown when a high-high level is reached. These precautions are taken to protect the ESP from damage caused by CO combustion in the unit. A second monitor is positioned downstream of the ESP in the stack to detect the presence of particulate. The presence of a high concentration of particulate stops the recirculation of stack gas to the calciner system to prevent coating problems in the air heater and calciner inlet areas. The operation of the ESP electrodes, heaters and rappers are controlled within a local PLC called a PIACS-DC controller (Precipitator Integrated Automatic Control System for DC Powered Units). The PIACS-DC requires simple start commands from the PCS to begin normal operation. Adjustments to the operation of the electrodes and the cleaning circuit are performed locally via the PIACS-DC controller. A description of these adjustments and the function of the PIACS-DC are described in the ESP operating manual. The control of the ESP discharge screw and dust purge valve is handled by the PCS.

6.1.1 ESP START The ESP Dust Screw 400-SC-040 and Dust Purge Rotary Valve 400-AL-030 must be energized before the ESP fields can be energized. However, once energized, the fields will not be de-energized if a Dust Screw or Rotary Valve failure occurs. Approximately 6-12 hours before a CRS feed system start is planned the following start commands are issued via the PCS:

1. PIACS heating group (hopper heaters are energized). 2. ESP purge air fan (400-GB-030)

Once the calciner system is in idle mode and ESP outlet gas temperature is greater than 100°C (interlock requirement), a start command can be issued to energize the ESP fields. Energizing of the ESP fields is


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performed by the PIACS local PLC upon receiving a single “Start” command from the PCS. The local PIACS controller will energize all fields simultaneously at a reduced current and ramp to the target power settings as per the specified ramp function (required to minimize inrush current). The PIACS will return a confirmation signal as each field is successfully energized. The field shall be highlighted in the PCS display once this confirmation is received to give the operator a clear indicator of which fields are active. Once started, the PIACS controller will adjust field conditions and rapper operation to optimize the overall performance of the ESP. Once the PCS receives conformation that all fields are energized, the PCS sends a start command to the PIACS system to activate the electrode cleaning rappers. The actual rapper operation is then controlled by the PIACS.

6.1.2 ESP NORMAL SHUTDOWN The ESP fields may be de-energized by the operator from the PCS when the CRS feeder (200-FD-085) is NOT running. If any fan in the Process Air Group or Calciner Group is active at the time that an operator Stop command is received, the operator will be prompted to confirm that field shutdown is desired before sending a Stop request to the ESP PLC. The plant personnel may consider preventing a shutdown of the ESP until all fans have been de-energized in order to minimize the potential for significant stack particulate emissions. The shutdown sequence includes:

1. Send a Stop command to the PIACS system from the PCS to de-energize all fields. 2. Stop the Purge Air Fan (400-GB-030) and Hopper heaters (400-EE-1001/1031/1051/1071/1091) if

the ESP is to be shutdown for more than 24 hours. 3. Maintain operation of the electrode rappers for 2 hours following de-energizing of the fields to

ensure a thorough clean down. a. If a Stop command is attempted by the operator within 2 hours following field shutdown,

the PCS issues a confirmation request.

6.1.3 ESP EMERGENCY SHUTDOWN The ESP fields will be de-energized in the following situations:

1. A high high carbon monoxide signal from the CO monitor 400-QISZA-0180, 2. A shutdown request is automatically sent by the PCS in the event of a high high temperature

indication at the outlet of the ESP (400-TISA-0302). The electrode rappers, hopper heaters, dust screw and dust purge valve will continue to operate until manually stopped by the operator or the dust slurry system is taken offline.

6.1.4 ESP DUST SCREW The ESP Dust Screw 400-SC-040 is utilized to convey dust out of the ESP hoppers and deliver the material to two possible transport routes. This screw can only be started after Dust Purge Rotary Valve 400-AL-030 is operating and there are no emergency stops active. A permissive for a start of the ESP fields cannot be issued until this screw is operating. The following sequence is performed during normal start, run and stop cycles for the screw:


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1. Check for emergency stop or maintenance setting at the PIACS. If not present, display a start

permissive on the PCS screen, 2. Check for operation of Dust Purge Rotary Valve 400-AL-030:

a. If 400-SSA-0330 indicates operation, continue sequence. b. If 400-SSA-0330 indicates that 400-AL-030 is not active, stop sequence and alarm.

3. The operator manually selects the ESP Dust Screw and selects start, 4. The PCS sends a start signal to the motor starter for 400-EM-0306, 5. The PCS checks for screw shaft motion confirmation from 400-SSA-0305:

a. If received in <5 seconds, confirm operation and highlight screw icon on PCS display to denote operation.

b. If not received in 5 seconds, the motor is de-energized and an alarm is displayed. 6. Once a successful start is achieved, the screw is de-energized via:

a. Stop command from the operator, b. A loss of shaft motion detection at 400-SSA-0305, c. Motor fault signal from motor starter (400-EM-0306), d. Emergency shutdown action, e. Dust Purge Rotary Valve 400-AL-030 is stopped.

6.1.5 ESP DUST PURGE VALVE The ESP Dust Purge Valve 400-AL-030 is utilized to transfer dust provided by the ESP Dust Screw to the transport system in the Dust Slurry Circuit (400-BN-040). This valve can only be started after interlocks associated with the ESP dust slurry circuit are satisfied. In addition, there must no be an emergency stop action. The following sequence is performed during normal start, run and stop cycles for the rotary valve:

1. Check for an emergency stop interlocks. If not present, display a start permissive on the PCS screen, 2. Check interlocks to the dust wetting system:

a. If satisfied, continue sequence. b. If not satisfied, stop sequence and alarm.

3. The operator manually selects the ESP Dust Purge Valve and selects start, 4. The PCS sends a start signal to the motor starter for 400-EM-0330, 5. The PCS checks for shaft motion confirmation from 400-SSA-0330:

a. If received in <5 seconds, confirm operation and highlight valve icon on PCS display to denote operation.

b. If not received in 5 seconds, the motor is de-energized and an alarm is displayed. 6. Once a successful start is achieved, the valve is de-energized via:

a. Stop command from the operator, b. A loss of shaft motion detection at 400-SSA-0305, c. Motor fault signal from motor started (400-EM-0306), d. Emergency shutdown action, e. Dust wetting circuit interlock status changes.


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6.1.6 ESP HOPPER RAPPERS The ESP hopper rappers (400-KSV-1001-1008) are started as a group by the operator. A start permissive is not available until the ESP Screw Conveyor 400-SC-040 is operating as confirmed by speed switch 400-SSA-0305. During the start sequence, the operator can adjust the rapper on duration and dwell time. Once the group is started, the rappers are energized in series subject to the specified duration and dwell time. The operating cycle continues until a stop command is received from the operator or the ESP Screw Conveyor stops as indicated by 400-SSA-0305.

6.1.7 ESP OUTLET/STACK GAS OPACITY The gas opacity monitor is used to continuously monitor the ESP outlet gas stream for the presence of particulate. When the particulate level exceeds 50 mg/Nm3, the PCS adjusts the position of Tempering Tee 400-DA-034 for 100% ambient air intake. Once this action occurs, a close command is required by the operator to move the Tempering Tee position for stack gas recirculation.

6.1.8 ESP FIELD LOSS In the event that one of the ESP fields becomes inactive while the CRS feed system is running, Tempering Tee 400-DA-034 is immediately opened for 100% ambient air intake. If more than one field becomes inactive then the CRS feed system is stopped and the calciner is moved into a Hot Idle mode.

6.2 EQUIPMENT/INSTRUMENT SUMMARY The ESP Group consists of the following components and attached instruments and equipment: ESP Group


Electrostatic Precipitator 400-EP-030

Automatic Voltage Control (Fields A,B,C,D) 400-HS-1014,30,67,87

TRPC Panels (Fields A,B,C,D) N/A

Hopper Heaters (5) 400-EE-1001,31,51,71,91

Hopper Heater Temperature Probes (5) 400-TE-1017,46,64,84,89

Hopper Level Probes (4) X 400-LSA-1016,45,65,85,90

Hopper Rappers (8) 400-KSV-1001,02,03,04, 05,06,07,08

Purge Fan 400-GB-030

Purge Fan Motor X 400-EM-1030

Purge Fan Flow Switch 400-FSA-1099

PIACS-DC PLC N/A

Inlet Pressure X 400-PI-0300

Outlet Temperature X 400-TISA-0302

ESP Dust Screw 400-SC-040


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Screw Motion Switch X 400-SSA-0305

Screw Motor X 400-EM-0306

ESP Dust Purge Rotary Valve 400-AL-030

Rotor Shaft Motion Switch X 400-SSA-0330

Valve Motor X 400-EM-0330

ESP Dust Gate Valve 400-GA-040

Solenoid Valve 400-KSV-0301

Position Indicating Switches O/C X 400-GS-0301

Opacity Monitor X 400-QIA-1401

6.3 CONTROL LOOPS There are no control loops associated with the operation of the ESP in the PCS. `

6.4 ALARMS


Device Analog Set Point

Debounce Value

High 400-QIA-1401 40mg Nm3 equivalent 0 sec ESP Outlet Opacity Level

High High 400-QIA-1401 >50mg Nm3 equivalent 0 sec

High 400-TISA-0302 300°C 0 sec Outlet Gas Temperature


Screw Shaft Speed Low 400-SSA-0305 - 5 sec

Inlet Gas Pressure Low 400-PIA-0300 -600 mm WG 2 sec

Dust Valve Speed Low 400-SSA-0329 - 5 sec

Dust Purge Valve Speed Low 400-SSA-0330 - 5 sec

Bin Dust Level High 400-LSA-1016, 45,65,85 - 10 sec

ESP Common Alarm ESP PIACS PLC

400-XA-1000/1030/1050/1070

- -

6.5 INTERLOCKS

Equipment Signals Interlock Type


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X X X


CO Level (400-QISZA-0180) NOT High X

CO Level (400-QISZA-0180) NOT High High X

Outlet Temperature (400-TISA-0302) NOT High High X

Outlet Temperature (400-TISA-0302) >100°C X X

Purge Air Fan (400-GB-030) Running X X

Electrode Rappers On X X

Energize ESP Fields

ESP Dust Screw (400-SC-040) Motor (400-EM-0306) Running X

Manual Shutdown of ESP Fields CRS Feed Belt 200-FD-085 NOT Running X

ESP Dust Screw (400-SC-040) Motor (400-EM-0306) Operation Rotary Valve 400-AL-030 Running X X

Dust Purge Rotary Valve (400-AL-030) Motor (400-EM-0330) Operation

Ready Signal from Dust Slurry System X X

ESP Rappers ESP Dust Screw 400-SC-040 Running X X

7 CLEANING GROUP The Cleaning Group includes the Air Cannons (400-AC-020/021/025/026/060/061) and Rappers (400-VB-020/021/022/023/024/025/026/027/028/029/060/061/062) mounted on the cyclone cones and discharge ducts for the purpose of maintaining stable solids flow through the system. Several modes of operation are available for these devices. Components are referenced on the following C&ID drawings:

• 8.500742 SHT. 5 (400-02) • 8.500742 SHT. 6 (400-03)

7.1 FUNCTIONAL DESCRIPTION

7.1.1 AIR CANNONS Air cannons are utilized to clear material deposits from the cyclone cones by injecting a sudden burst of compressed air. Six air cannons are installed for initial system startup, but provisions must be made to accommodate the control of 6 additional air cannons should they be required based on commissioning


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evaluations. The cannons remain charged with compressed air at all times unless the manual air supply valves are closed. The PCS highlights the air cannon icon on the display at the time that the solenoid is being energized. If set for automatic timed firing, the active cannon icons are highlighted appropriately. The air cannons may be operated in several different modes as determined by the operator. This specification does not require the operation of the ESP ID fan to enable air cannon firing. This interlock should be considered as the operation of the ESP ID fan will place the system under suction and minimize the potential for nuisance dust emissions when an air cannon is fired.

7.1.1.1 INDIVIDUAL CANNON OPERATION - MANUAL Each individual air cannon may be selected for firing if an air cannon group operation is not active. This operation involves:

1. Operator selects the desired air cannon on the PCS display, a. If no emergency stop active, proceed. b. If an emergency stop is active, indicate that the air cannon is not available.

2. From the menu, “Cannon Fire” is selected. 3. The PCS energizes the solenoid for a period of 5 seconds, which allows compressed air

present in the piston retention chamber to exit to atmosphere. When this occurs, the piston moves to an open position and the compressed air in the tank is discharged into the cyclone.

4. The solenoid is de-energized, which permits the return spring to force the piston into its closed position, pressurizes the piston retention chamber.

5. Compressed air automatically flows into the air cannon tank through the unrestricted supply line.

6. The PCS prevents re-firing of the air cannon for 10 seconds to permit ample time for the tank to recharge. Any other air cannon in the group may be selected immediately and fired.

7.1.1.2 GROUP CANNON OPERATION - MANUAL A group firing of all or select air cannons may be performed. This operation involves:

1. Operator selects any air cannon on the PCS display, a. If no emergency stop active, proceed. b. If emergency stop is active, indicate that the air cannons are not available.

2. From the menu, the “Group Cannon” box is checked. This is repeated for all air cannons to select/deselect and generate the target active group.

3. Once selections are made, “Group Cannon Fire” is selected from the menu that is displayed when any air cannon icon is selected.

4. The PCS energizes the solenoids for the following air cannons in sequence allowing for a 10 second delay between the actuation of each cannon in the sequence. If an air cannon in the sequence is not checked, the PCS will skip to the next selected cannon without delay. The sequence includes:

a. 400-AC-020 b. 400-AC-021 c. 400-AC-025 d. 400-AC-026 e. 400-AC-060 f. 400-AC-061


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5. The manual firing sequence may be repeated after 10 seconds has elapsed from the firing of the last cannon in the selected sequence.

6. The selected air cannons in the group may be changed after the sequence has been completed.

7.1.1.3 GROUP CANNON OPERATION - TIMED A group firing of all air cannons may be performed at a specified interval. This operation involves:

1. Operator selects any air cannon on the PCS display, a. If no emergency stop active, proceed. b. If emergency stop is active, indicate that the air cannons are not available.

2. From the menu, the “Group Cannon” box is checked. This is repeated for all air cannons to select/deselect and generate the target active group.

3. The firing interval is specified at any time during this selection process. Once set for one air cannon, the interval is utilized for all air cannons. The minimum time interval that may be set by the operator is 5 seconds.

4. Once selections are made, “Group Cannon Timed Fire” is selected from the menu that is displayed when any air cannon icon is selected.

5. The PCS energizes the solenoids (5 second duration) for the following air cannons in sequence allowing for a 10 second delay between the actuation of each cannon in the sequence. If an air cannon in the sequence is not checked, the PCS will skip to the next selected cannon without delay. The sequence includes:

a. 400-AC-020 b. 400-AC-021 c. 400-AC-025 d. 400-AC-026 e. 400-AC-060 f. 400-AC-061

6. The PCS will repeat the sequence as soon as last cannon in the sequence has been fired and the time interval has elapsed.

7. The operator may stop the timed operation at any time. Once stopped, a start command will start the sequence at the beginning.

Timed automatic firing of the air cannons can only be performed when CRS Feed Belt 200-FD-085 is operating.

7.1.2 RAPPERS Rappers are utilized to promote material flow via high amplitude/low frequency vibrations. Thirteen rappers are installed for initial system startup, but provisions must be made to accommodate the control of 9 additional units should they be required based on commissioning evaluations. The PCS highlights the rapper icon on the display at the time that the solenoid is being energized. If set for automatic timed firing, the active devices are highlighted appropriately. The rappers may be operated in several different modes as determined by the operator:

7.1.2.1 INDIVIDUAL RAPPER OPERATION Each individual rapper may be selected for operation if a group operation is not active. This operation involves:


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1. Operator selects the desired rapper on the PCS display, a. If no emergency stop active, proceed. b. If emergency stop is active, indicate that the rapper is not available.

2. From the menu specify continuous operation or timed. If timed, specify on and off times. 3. From the menu, “Start” is selected. 4. The PCS energizes the solenoid at a frequency of 20 cycles/min (operator adjustable within

10-60 cycles/min), which allows rapper to cycle at a rate of 20 cycles/min. If timed operation is selected, the device will cycle until the on time expires, remain inactive as specified by the off time, and then repeat the sequence.

The device remains active until a Stop command is received from the operator or an emergency stop action occurs.

7.1.2.2 GROUP RAPPER OPERATION The operator may specify a group of rappers and start them as a group. This operation involves:

1. Operator selects the desired rappers on the PCS display, a. If no emergency stop or lockout active, proceed. b. If emergency stop is active, indicate that the rappers are not available.

2. From each individual menu, specify continuous operation or timed. If timed, specified on and off times.

3. Repeat steps 1 and 2 for all devices that are to be a part of the group. Timed settings may be different for each device. Specify the sequence in which the devices will be activated.

4. Once the group is formed, select “Start Group” from any device menu. 5. The PCS energizes the devices in the order specified. If continuous operation is specified,

then all group devices are started simultaneously and energized as per the specified on time. 6. The devices remain active until a Stop command is received from the operator or an

emergency stop action occurs.

7.2 EQUIPMENT DESCRIPTION The Cleaning Group consists of the following components and attached instruments and equipment: Cleaning Group


Air Cannons on 400-CY-060 Cone X 400-AC-060/061

Solenoid Valves 400-XSV-0144/45

Vibrators/Rappers on 400-CY-060 Cone X 400-VB-060/061/062

Solenoid Valves 400-XSV-0141/42/43





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Vibrators/Rappers on 400-CY-020 Discharge Duct X 400-VB-023/024






Vibrators/Rappers on 400-CY-025 Discharge Duct X 400-VB-028/029


7.3 CONTROL LOOPS There are no control loops associated with the operation of the Cleaning Group.

7.4 ALARMS There are no alarms associated with the operation of the Cleaning Group.

7.5 INTERLOCKS



X X


Manual Fire Air Cannons No Emergency Stop X

Auto Timed Firing of Air Cannons CRS Feed Belt 200-FD-085 Running X X

Activate Vibrators/Rappers No Emergency Stop X

8 DUST HANDLING GROUP The Dust Handling Group includes the ESP Screw Conveyor Airlock (400-AL-040), Dust Gate (400-GA-040), Dust Return Blower (400-GB-040), Dust Inlet Tee (400-PN-040), Convey Line, Dust Return Bin (400-BN-010), Bin Vent Filter (400-DC-010) and Dust Return Bin Airlock (400-AL-045). The Group transports dust from ESP 400-EP-030 to the Dust Return Bin 400-BN-010, and then meters the dust into Calciner 400-FD-050. Components are referenced on the following C&ID drawings:

• 8.500742 SHT. 5 (400-02) • 8.500742 SHT. 7 (400-04)


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8.1.1 DUST FEED START SEQUENCE 1. The operator selects Dust Return Bin Airlock 400-AL-045 on the PCS display. 2. The PCS provides “Start” permissive if the system is in a production mode as determined by all

interlocks being satisfied for manual increases to the CRS feed rate. 3. The operator selects “Start” from the menu. The PCS sends a start command to the motor starter

for 400-EM-0103. a. If rotor shaft movement is detected by motion sensor 400-SSA-0105 within 5 seconds,

confirm valve operation. b. If no motion is detected by 400-SSA-0105 within 5 seconds, stop sequence and alarm.

4. The operator adjusts the speed of 400-AL-045 via 400-EU-0103 to obtain the target dust flow rate. A password protected valve speed limit may be specified in the PCS to prevent overfeeding the system with dust.

5. When the dust level in Dust Return Bin 400-BN-010 is at a low level as indicated by level switch 400-LS-0105, a start command is sent to motor 400-EM-0313 on Dust Return Blower 400-GB-040.

6. Once the PCS confirms a blower start, motor 400-EM-0329 is started on ESP Screw Conveyor Airlock 400-AL-040:

a. If rotor shaft movement is detected by motion sensor 400-SSA-0329 within 5 seconds, confirm valve operation.

b. If no motion is detected by 400-SSA-0329 within 5 seconds, stop sequence and alarm, c. The operator may adjust the speed setting for this valve at any time.

7. Once valve operation is confirmed, the PCS opens Dust Gate 400-GA-040. 8. Once the Dust Bin level reaches a high level as indicated by level switch 400-LS-0104, the PCS

performs the following: a. Close Dust Gate 400-GA-040, b. After 10 seconds, stop ESP Screw Conveyor Airlock 400-AL-040 motor 400-EM-0329, c. Wait 30 seconds and then stop Dust Return Blower 400-GB-040 motor 400-EM-0313, d. Wait 15 minutes and then stop Dust Return Bin Airlock 400-AL-045 motor 400-EM-0103.

9. Steps 5-8 are repeated by the PCS once the Dust Bin level switch 400-LS-0105 indicates a low dust level.

10. If the low level switch 400-LSA-0105 remains closed for more than 60 seconds, an alarm is issued by the PCS.

8.1.2 DUST FEED STOP 1. The operator selects Dust Return Bin Airlock 400-AL-045 on the PCS display and selects “Stop”

from the menu. 2. If the dust convey circuit is active, dust transport to the dust feed bin 400-BN-010 will continue until

a high level is indicated by 400-LS-0104.

8.1.3 DUST FEED EMERGENCY STOP 1. In the event of an Emergency Stop or interlock action as a result of CRS feed stoppage, the PCS

performs the following sequence: a. Stop Dust Return Bin Airlock 400-AL-045 motor 400-EM-0103 b. Close Dust Gate 400-GA-040, c. After 10 seconds, stop ESP Screw Conveyor Airlock 400-AL-040 motor 400-EM-0329, d. Wait 30 seconds and then stop Dust Return Blower 400-GB-040 motor 400-EM-0313.


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8.1.4 DUST BIN FILTER CLEANING CIRCUIT The automatic cleaning of the Dust Bin Filter (400-DC-010) is handled by a local control unit that supports two modes of cleaning: timed cleaning or on demand cleaning. The choice of cleaning mode is made by manually actuating a toggle switch located on the front of the panel. When timed cleaning is selected, supplying power to the unit will activate pulse cleaning of the filter as per the frequency specified at the local panel. When “on demand” cleaning is selected on the local panel, the pulse circuit is energized when the filter differential pressure exceeds the local set point value (typically 100mm WG). There is no interface between the local panel and the PCS.

8.2 EQUIPMENT DESCRIPTION The Dust Handling Group consists of the following components and attached instruments and equipment: Dust Handling Group


ESP Screw Conveyor Airlock X 400-AL-040

Motor X 400-EM-0329

Variable Frequency Drive X 400-EU-0329

Motion Switch X 400-SSA-0329

ESP Dust Gate Valve X 400-GA-040

Solenoid Valve 400-KSV-0301

Position Indicating Switches O/C X 400-GS-0301

Dust Return Blower X 400-GB-040

Motor X 400-EM-0313

Outlet Pressure Switch X 400-PSA-0341

Outlet Pressure Indicator 400-PI-0342

Outlet Temperature Switch X 400-TSA-0343

Pressure Relief Valve 400-SV-0344

Dust Inlet Tee 400-PN-040

Dust Return Bin 400-BN-010

High Level Switch X 400-LS-0104

Low Level Switch X 400-LS-0105

Bin Pressure Relief Valve 400-SV-0101

Bin Vent Filter 400-DC-010

Filter Differential Pressure Switch 400-PDIS-0101

Pressure Regulator – Bag Cleaning Air 400-PC-0103

Pressure Indicator – Cleaning Air 400-PI-0102

Pulse Timer 400-KIS-0101


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Cleaning Air Solenoid (4) 400-KSV-0101

Dust Return Bin Airlock X 400-AL-045

Motor X 400-EM-0103

Variable Frequency Drive X 400-EU-0103

Motion Switch X 400-SSA-0105

Motor Speed Indication X 400-SI-0106

8.3 CONTROL LOOPS There are no control loops associated with the operation of the Dust Handling Group.

8.4 ALARMS



ESP Screw Rotary Airlock No Motion 400-SSA-0329 - 5 sec

Blower Outlet Pressure High 400-PSA-0341 0.5 bar 2 sec

Blower Outlet Temperature High 400-TSA-0343 80°C 0 sec

Dust Bin Rotary Airlock No Motion 400-SSA-0105 - 5 sec

8.5 INTERLOCKS



X X


Dust Bin Rotary Valve CRS Feed Belt 200-FD-085 Running X X

ESP Screw Rotary Airlock Blower 400-GB-040 Running X X

Dust Bin Rotary Valve 400-AL-045 Running X

Dust Return Blower Dust Bin 400-BN-010 Level NOT High (400-LS-0104) X X

Dust Gate 400-GA-040 ESP Screw Rotary Airlock 400-AL-040 Running X X


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9 WATER SPRAY GROUP The Water Spray Group includes the Mill Table Water Spray and the Mill Body Water Spray Circuit (400-PP-010). The Group provides water for grinding bed stabilization and mill outlet temperature control. Components are referenced on the following C&ID drawings:

• 8.500742 SHT. 4 (400-01) • 8.500742 SHT. 13 (400-10)


9.1.1 MILL TABLE WATER SPRAY The mill water spray may be activated at the operator’s discretion once the CRS Feed System 200-FD-085 is running for a minimum of 60 seconds. The water flow can be started after this delay when the operator selects the mill water spray icon and issues a “Start” command. When this command is received, the PCS opens flow control valve 400-FCV-0001 to the specified flow rate. This rate can be modified at any time by the operator. Water flow will continue until stopped manually by the operator or a CRS Feed System stop (200-FD-085). The start menu for the mill table water spray includes an option to select “Auto Start”. If this is checked, the table water spray flow control valve 400-FCV-0001 will be opened to provide the set point flow rate 60 seconds after the CRS Feed Belt 200-FD-085 is started. The flow rate measured by 400-FICA-0001 is compared to the set point value. If the actual flow deviates from the set point flow by more than 25% an alarm is issued by the PCS. This deviation alarm protects against a failure of control valve 400-FCV-0001 which may flood the mill with water and lead to mechanical damage.

9.1.2 MILL BODY WATER SPRAY CIRCUIT The mill body water spray is controlled by loop 400-CTL-05. When this loop is activated and required interlocks are satisfied, the PCS adjusts the position of flow control valve 400-TCV-0004 to maintain the target mill off gas temperature at 400-TICSA-0004. There are no provisions to manually adjust the water spray rate. The PCS automatically starts Pump 400-PP-010 when the control loop is activated. The flow rate of water indicated by meter 400-FIA-0002 is compared against the flow versus position curve for flow control valve 400-TCV-0004. If a deviation of greater than 25% is determined, an alarm is issued by the PCS. This deviation provides an indication of nozzle blockage or control valve failure.

9.2 EQUIPMENT DESCRIPTION The Water Spray Group consists of the following components and attached instruments and equipment: Water Spray Group


Mill Table Water Spray n/a

Flow Control Valve X 400-FCV-0001


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Flow Rate Indicator X 400-FICA-0001

FCV Closed Position Switch X 400-GBS-0001

Water Shutoff Valve 400-FSV-0040

Mill Body Water Spray n/a

Water Inlet Screen Differential Pressure Transmitters X 400-PDA-0901/02

Water Inlet Screen Differential Pressure Indicator 400-PDI-0901/02

Water Tank 400-PP-010-A

Water Low Level Switch X 400-LSA-0903

Pump 400-PP-010

Pump Motor X 400-EM-0905

Pump Outlet Pressure Indicator 400-PI-0906


Flow Rate Indicator X 400-FIA-0002

Flow Control Valve X 400-TCV-0004

TCV Closed Position Switch X 400-GBS-0002A

TCV Position Indication X 400-GIS-0002

Spray Nozzle Inlet Pressure Indicator 400-PI-0002

9.3 CONTROL LOOPS The Mill Body Water Spray circuit is controlled by 400-CTL-05. This control loop description is provided in 4.3.2.

9.4 ALARMS



Screen Differential Pressure High 400-PDA-0901/02 Factory Set Point 5 sec

Tank Water Level Low 400-LSA-0903 Factory Set Point 5 sec

Mill Table Water Spray Flow Deviation High/Low 400-FICA-0002 +/-25% 5 sec

Mill Upper Body Water Spray Flow Deviation High/Low 400-FIA-0002 +/-25% 5 sec

9.5 INTERLOCKS


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X X


Mill Table Water Spray Control Valve CRS Feed Belt Motor 200-EB-0806 Running X X

Mill Cyclone dP >50mm WG X X Mill Upper Body Water Spray Control Valve

400-CTL-05 Activated X X

10 ROLLER MILL HYDRAULIC GROUP

10.1 FUNCTIONAL DESCRIPTION The Roller Mill Hydraulic Group consists of components that provide pressurized hydraulic fluid to the roller cylinders for the purpose of raising/lowering the grinding rollers and maintaining the desired degree of grinding force. Operation of the hydraulic pump and solenoid actuation is performed by the PCS. An alarm is issued in the event that the hydraulic pump (400-EM-1107) runs continuously for more than 5 minutes. A local panel is available to permit local control of basic hydraulic group functions (see the roller mill manual for more information). The local panel must be set to Auto to enable remote start by the operator prior to a CRS Feed Start sequence. Roller Mill Hydraulic Group components are referenced on the following C&ID drawings:

• 8.500742 SHT. 4 (400-01) • 8.500742 SHT. 15 (400-12)

10.1.1 NORMAL START The Roller Mill Hydraulic Group is started by the operator prior to performing a CRS feed start. If the CRS feed start command is issued by the operator and the Roller Mill Hydraulic Group is not started, the operator will be prompted to start this group. A start permissive will only be available if the local hydraulic panel is set to Auto mode.

10.1.2 RAISE ROLLERS

The rollers are moved to their raised position automatically by the PCS when the Roller Mill Hydraulic Group is initially started or when the CRS Feed Belt 200-FD-085 is de-energized. This sequence includes:

1. Roller Mill Hydraulic Group start: a. Start hydraulic pump 400-EM-1107. b. Solenoids 400-XSV-1104 (4S), 4000-XSV-1101 (5S) and 400-XSV-1103 (6S) are energized.

Solenoid 400-XSV-1102 (8S) is de-energized.


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c. The pump is stopped by the PCS once the rollers are in their raised positions as indicated by position switches 400-GBS-0007, 400-GBS-0009 and 400-GBS-0011 and 400-PS-1103 closes.

d. Solenoid 400-XSV-1104 (4S) is de-energized to hold the rollers in the raised position. e. If a high position indication from any of the three high position switches is lost (400-GBS-

0007, 400-GBS-0009 and 400-GBS-0011) or switch 400-PS-1103 opens, the hydraulic pump will be started by the PCS and Solenoid 400-XSV-1104 (4S) energized until high level indication is obtained and the pressure switch is closed. The PCS will then de-energize 400-XSV-1104.

2. The CRS Feed Belt 200-FD-085 is stopped as a result of a normal stop, interlock action or emergency action:

a. If hydraulic pump motor is not running, a start command is sent to the starter for hydraulic pump motor 400-EM-1107.

b. Solenoids 400-XSV-1104 (4S), 4000-XSV-1101 (5S) and 400-XSV-1103 (6S) are energized. Solenoid 400-XSV-1102 (8S) is de-energized.

c. The pump is stopped by the PCS once the rollers are in their raised positions as indicated by position switches 400-GBS-0007, 400-GBS-0009 and 400-GBS-0011 and closure of pressure switch 400-PS-1103..

d. Solenoid 400-XSV-1104 (4S) is de-energized to hold the rollers in the raised position. e. If a high position indication from any of the three high position switches is lost (400-GBS-

0007, 400-GBS-0009 and 400-GBS-0011), the hydraulic pump will be started by the PCS and Solenoid 400-XSV-1104 (4S) energized until high level indication is obtained and the pressure switch closes. The PCS will then de-energize 400-XSV-1104.

This sequence can also be performed manually by the operator by selecting “Raise Rollers” from the Roller Mill Start menu. Starting of the main mill drive cannot be performed unless the rollers are in their raised position.

10.1.3 LOWER ROLLERS The rollers may be lowered only when the CRS Feed Belt 200-FD-085 is running. This automatic function is performed as follows: 1. The CRS Feed Belt 200-FD-085 is energized as a result of a “Start CRS Feed” command. 2. After a period of 10 seconds, Solenoid 400-XSV-1103 (6S) is de-energized to lower the three rolls onto

the material bed (this solenoid remains de-energized during normal mill operation). 3. Pressure switch 400-XSV-1104 closes to confirm that the pressure has been relieved from the lift side of

the hydraulic circuit. Solenoid 6S will remain de-energized until the rollers are to be raised.

10.1.4 GRINDING PRESSURE CONTROL The PCS starts and stops the hydraulic pump and energizes/de-energizes solenoids as required to maintain the target mill grinding pressure. The target grinding pressure is specified by the operator within the allowable range as determined by the accumulator pre-charge pressure. The allowable range is entered into the PCS and password protected to prevent operation outside of the acceptable limits. Setting of accumulator pre-charge pressure and the allowable operating range is specified in the mill operating manual. The PCS maintains a roll pressure equivalent of 80% of the set point value for the first 10 minutes of mill


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operation and then increases the pressure to the set point value. This initial operation at a lower pressure improves mill stability and reduces the potential for a low roller position fault. The pressure control sequence performed by the PCS is as follows: 1. Following a delay of 10 seconds after the PCS initiates lowering of the rollers, energize Solenoid 400-

XSV-1102 (8S). This solenoid remains energized during normal mill operation. 2. Check circuit hydraulic pressure (400-PISA-1107):

2.1. If >1.75 bar below 0.8 x Set Point, start hydraulic pump motor 400-EM-1107. Stop motor 400-EM-1107 when the target pressure at 400-PISA-1107 is obtained.

2.2. If >3.5 bar above 0.8 x Set Point, de-energize Solenoid 5S (400-XSV-1101) until the target pressure at 400-PISA-1107 is obtained and then re-energize.

3. After 10 minutes, adjust the hydraulic pressure (400-PISA-1107) to the set point and maintain: 3.1. If >1.75 bar below the set point, start hydraulic pump motor 400-EM-1107. Stop motor 400-EM-

1107 when the target pressure at 400-PISA-1107 is obtained. 3.2. If >3.5 bar above the set point, de-energize Solenoid 5S (400-XSV-1101) until the target pressure at

400-PISA-1107 is obtained and then re-energize.

10.2 EQUIPMENT DESCRIPTION The Roller Mill Hydraulic Group consists of the following components and attached instruments and equipment: Roller Mill Hydraulic Group


Hydraulic Reservoir 400-HP-010A

Reservoir Level Switch X 400-LSA-1110

Reservoir Level Site Indicators 400-LI-1111A/B

Hydraulic Pump 400-HP-010B

Hydraulic Pump Motor X 400-EM-1107


Pump Outlet Filter Differential Pressure X 400-PDA-1101

Pump Outlet Filter Pressure Relief Valve 400-SV-1102

Pump Outlet Pressure Relief Valve 400-SV-1103

Return Line Filter Pressure Relief Valve 400-SV-1101

Return Line Filter Differential Pressure X 400-PDA-1100

Return Line Filter Differential Pressure Indicator 400-PDI-1100

Lift High Pressure Switch X 400-PS-1103

Lift Low Pressure Switch X 400-PS-1104

Lift Pressure Indicator 400-PI-1105

Grinding Pressure Indicator 400-PI-1106

Grinding Pressure Transducer X 400-PISA-1107


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Solenoid 5S 400-XSV-1101




10.3 CONTROL LOOPS There are no control loops associated with the operation of the Roller Mill Hydraulic Group.

10.4 ALARMS

Alarm Condition Alarm Trigger Analog Set

point Debounce Value

Main Hydraulic Pump Tripped 400-EM-1107 Starter - -

Hydraulic Pump Excessive Continuous Operation 400-EM-1107 Contact - 5 min

Supply Filter Clogged 400-PDA-1101 1.7 bar 5 sec

Return Filter Clogged 400-PDA-1100 1.7 bar 5 sec

High 400-PISA-1107 >3.5 bar

Above Set Point

5 sec

Low 400-PISA-1107 1.7 bar Below Set Point 5 sec

Cylinder Pressure

Low Low 400-PISA-1107 0.9 x Set Point 5 sec

10.5 INTERLOCKS



X X X

Z X

Sample: (X AND Y AND Z); Z to start, X AND Y to run, X for safety shutdown

Y X

Raise Rollers Solenoids 400-XSV-1104 & 400-XSV-1103

CRS Feed Belt Motor 200-EB-0806 NOT Running X X


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Lower Rollers Solenoid 400-XSV-1103

CRS Feed Belt Motor 200-EB-0806 Running X X

Hydraulic Pump Start (400-HP-010B)

CRS Feed Belt Motor 200-EB-0806 NOT Running (Raise Rollers)

Grinding Pressure Low (400-PISA-1107) X X

11 LUBRICATION GROUP


The Lubrication Group consists of the Roller Mill Main Drive Lubrication System (400-LU-010), the Roller Mill Roller Lubrication System (400-LU-011A, 400-LU-011B, and 400-LU-011C), the Roller Mill Grease System (400-ML-010A), the Classifier Drive Lubrication System (400-LU-015), and the Classifier Grease System (400-CI-015A).

Lubrication Group components are referenced on the following C&ID drawings:

• 8.500742 SHT. 4 (400-01) • 8.500742 SHT. 9 (400-06) • 8.500742 SHT. 10 (400-07) • 8.500742 SHT. 11 (400-08) • 8.500742 SHT. 12 (400-09)

11.1.1 ROLLER MILL MAIN DRIVE LUBRICATION SYSTEM The main drive lubrication system is started either automatically by the PCS when a “Start CRS Feed” command is issued by the operator, which precedes the start of the main mill drive motor 400-EM-0009, or through a manual start command from the operator. Due to a low temperature interlock (400-TISA-0510), the main mill drive cannot be started until the lubricant temperature is greater than the low temperature shutoff. The normal start sequence includes:

1. “Start” command received from the operator to initiate operation of the Main Drive Lubrication System or a “Start CRS Feed” command received from the operator.

2. The circulation pump motor 400-EM-0524 is started and operation confirmed. 3. The PCS checks the fluid temperature in the reservoir (400-TIS-0526). If low, continue lubrication

system operation to warm the lubricant but do not remove the interlock on the mill drive until the low temperature switch opens.


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11.1.2 ROLLER MILL ROLLER LUBRICATION SYSTEM The three roller lubrication systems are started automatically by the PCS following a mill operating period of 20 minutes. Roller lube system pump (400-LU-011A, 400-LU-011B and 400-LU-011C) motors (400-EM-0605, 400-EM-0612, 400-EM-0704, 400-EM-0708, 400-EM-0804, 400-EM-0808) are started by the PCS and remain operational until the roller mill main drive (400-EM-0009) is de-energized. Electric heating elements 400-EE-0601/0701/0801 are energized by the PCS if low temperature switches 400-TS-0605/0705/0805 are closed, and then are de-energized when the high temperature switch closes.

11.1.3 ROLLER MILL GREASE SYSTEM Roller Mill Grease System (400-ML-010A) pump motor (400-EM-0030) is started automatically by the PCS when the roller mill main drive (400-EM-0009) is energized. The grease pump remains operational until the roller mill main drive (400-EM-0009) is de-energized.

11.1.4 CLASSIFIER DRIVE LUBRICATION SYSTEM Classifier Drive Lubrication System (400-LU-015) is started automatically by the PCS when a classifier drive motor (400-EM-0010) start command is issued by the operator. The operator may also start the circuit manually by selecting the classifier icon on the PCS display and then selecting “Start Classifier Lubrication Pump” from the menu. The normal start sequence includes:

1. “Start” command received from the operator to initiate operation of the Classifier Drive Motor 400-EM-0010 or the Classifier Lubrication Pump motor 400-EM-0015.

2. The circulation pump motor 400-EM-0015 is started and operation confirmed. 3. Continue system operation until the classifier drive motor (400-EM-0010) is de-energized. Continue

circulator pump operation for 5 minutes and then stop the circulator pump motor (400-EM-0015).

11.1.5 CLASSIFIER GREASE SYSTEM Classifier Grease System (400-CI-015A) pump motor (400-EM-0020) is started automatically by the PCS when the classifier drive motor (400-EM-0010) is energized. The grease pump remains operational until the classifier drive motor (400-EM-0010) is de-energized.

11.2 CONTROL LOOPS There are no control loops associated with the operation of the Lubrication Group components.

11.3 EQUIPMENT DESCRIPTION The Lubrication Group consists of the following components and attached instruments and equipment: Lubrication Group


Roller Mill Main Drive Lubrication System 400-LU-010

Fluid Reservoir n/a

Reservoir Temperature Switch X 400-TI-0527


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Reservoir Temperature Indicator 400-TI-0528

Reservoir Level Indicator 400-LI-0526

Reservoir Level Switch X 400-LSA-0525

Circulation Pump & Motor 400-EM-0524



Filter Inlet Pressure Indicator 400-PI-0522

Filter Outlet Pressure Indicator 400-PI-0520

Filter Differential Pressure Alarm X 400-PDA-0521

Filter Outlet Temperature Indicator 400-TI-0519

Oil Temperature Control Valve 400-TCV-0501

Cooling Water Inlet Temperature 400-TI-0506

Cooling Water Inlet Pressure 400-PI-0506

Cooling Water Outlet Temperature 400-TI-0504

Cooling Water Outlet Pressure 400-PI-0504

Pressure Indicator 400-PI-0503

Drive Inlet Fluid Temperature Element X 400-TISA-0507

Drive Inlet Low Pressure Switch X 400-PS-0501

Drive Inlet Low Low Pressure Switch X 400-PSA-0502

Drive Inlet Pressure Indicator 400-PI-0503

Drive Inlet Pressure Indicator 400-PI-0505

Drive Fluid Temperature Element X 400-TISA-0510

Drive Outlet Fluid Temperature Element X 400-TISA-0508

Roller Mill Roller Lubrication System (Rollers 1/2/3) 400-LU-011A/011B/011C

Lube Reservoir n/a

Lube Heating Element 400-EE-0601/0701/0801

Heating Element Temperature Switch 400-TIS-0605/0705/0805

Reservoir Temperature Element X 400-TSA-0604/0704/0804

Reservoir Level Indicator 400-LI-0605/0705/0805

Reservoir Low Level Switch X 400-LSA-0601/0701/0801

Reservoir High Level Switch X 400-LSA-0611/0711/0811

Lube Supply Pump & Motor X 400-EM-0605/0704/0804

Lube Return Pump & Motor X 400-EM-0612/0708/0808

Supply Pump Outlet Pressure Indicator 400-PI-0602/0702/0802

Lube Supply Flow Switch X 400-FIA-0602/0702/0802


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Lube Supply Filter Differential Pressure Indicator 400-PDI-0600/0700/0800

Lube Supply Filter Differential Pressure Transmitter X 400-PDA-0600/0700/0800

Water Supply Filter Differential Pressure Indicator 400-PDI-0610

Water Supply Filter Pressure Alarm X 400-PA-0601

Lube Temperature Controller 400-TCV-0603/0703/0803

Lube Return Flow Switch X 400-FISA-0607/0707/0807

Lube Return Filter Differential Pressure Indicator 400-PDI-0606/0706/0806

Lube Return Filter Differential Pressure Transmitter X 400-PDA-0606/0706/0806

Return Pump Outlet Pressure Indictor 400-PI-0609/0709/0809

Roller Mill Grease System 400-ML-010A

Grease Reservoir n/a

Grease Pump & Motor 400-EM-0030

Grease Level Sensor X 400-LA-0030

Grease Delivery Switching Device X 400-GA-0030

Grease Supply Pressure Relief Valve 400-SV-0030

Classifier Drive Lubrication System 400-LU-015

Lube Reservoir n/a

Reservoir Level Indicator X 400-LI-0005

Circulating Pump & Motor 400-EM-0015

Pump Outlet Pressure Relief Valve 400-SV-0016

Lube Supply Filters n/a

Filter Differential Pressure Transmitter X 400-PDA-0012

Filter Differential Pressure Indicator 400-PI-0012

Heat Exchanger 400-LU-015-H2

Lube Cooling Temperature Control Switch 400-TS-0014A

Lube Cooling Temperature High Alarm X 400-TA-0014B

Lube Temperature Indicator (HT Exch Outlet) 400-TI-0016

Lube Temperature High Temperature Switch X 400-TS-0018

Lube Low Low Pressure Switch X 400-PSA-0017

Lube Supply Pressure Indicator 400-PI-0018

Lube Supply Temperature Indicator 400-TI-0020

Lube Supply Flow Transmitter X 400-FZA-0019

Classifier Grease System 400-CI-015A

Grease Reservoir n/a


Revision 2


Grease Pump & Motor 400-EM-0020

Grease Level Sensor X 400-LA-0020

Grease Delivery Switching Device X 400-GA-0020

Grease Supply Pressure Relief Valve 400-SV-0020

11.4 ALARMS



Roller Mill Main Drive Lubrication System

High 400-LSA-0525 >2200 liters 5 sec Fluid Reservoir Level

Low 400-LSA-0525 <1200 liters 5 sec

Filter Outlet Differential Pressure High 400-PDA-0521 >2.5 bar 5 sec

Circulation Pump Motor Tripped (400-EM-0524) Motor Starter - -

Low 400-TISA-0507 18°C 0 sec

High 400-TISA-0507 47°C 0 sec Fluid Inlet Temperature


Low 400-TISA-0510 18°C 0 sec

High 400-TISA-0510 75°C 0 sec Fluid Temperature


Low 400-PA-0501 <2.8 bar 5 sec Fluid Inlet Pressure

Low Low 400-PSA-0502 <2.5 bar 5 sec

High 400-TISA-0508 56°C 0 sec Fluid Outlet Temperature High High 400-TISA-0508 60°C 0 sec

Roller Mill Roller Lubrication System (Roller 1/Roller 2/Roller 3)

Low 400-LSA-0601/0701/0801 Factory Set Point 5 min

Fluid Reservoir Level High 400-LSA-

0611/0711/0811 Factory Set Point 5 min

Return Fluid Flow Low 400-FSA-0607/0707/0807 2.3 lpm 30 sec

Return Line Filter Differential Pressure High

400-PDA-0606/0706/0806 1.7 bar TBD

Supply Line Filter Differential Pressure High

400-PDA-0600/0700/0800 1.7 bar TBD

Supply Fluid Flow Low 400-FA-0602/0702/0802 2.3 lpm 30 sec


Revision 2


Reservoir Fluid Temperature Low 400-TSA-

0604/0704/0804 27°C 30 sec

Supply Pump Motor Tripped (400-EM-0605/0704/0804) Motor Starter - -

Return Pump Motor Tripped (400-EM-0612/0708/0808) Motor Starter - -

Water Supply Pressure Low 400-PA-0601 TBD -

Roller Mill Grease System

Grease Reservoir Level Low 400-LA-0030 Factory Set Point 0 sec

Distribution Block Sequence Not Complete 400-GA-0030 - 2 min

Grease Pump Motor Tripped (400-EM-0030) Motor Starter - -


Revision 2


Classifier Drive Lubrication System

Fluid Flow Rate Low 400-FZA-0019 4 lpm 2 sec

Fluid Supply Pressure Switch Low Low 400-PSA-0017 0.35 bar 2 sec

High High Alarm 400-TA-0014 90°C 2 sec Fluid Supply Temperature

High High Switch 400-TSA-0018 100°C 2 sec

Filter Differential Pressure High 400-PDA-0012 0.35 bar 2 sec

High 400-EISA-I-0010 TBD TBDPump Motor 400-EM-0010 Power Draw High High 400-EISA-I-0010 TBD TBD

Classifier Grease System

Grease Reservoir Level Low 400-LA-0020 - 0 sec

Distribution Block Sequence Not Complete 400-GA-0020 - 2 min

Grease Pump Motor Tripped (400-EM-0030) Motor Starter - -

11.5 INTERLOCKS



X X


Mill Main Lube Circulating Pump (400-EM-0524)

Reservoir Lube Level (400-LSA-0525) NOT Low X X

Main Mill Drive Running (400-EM-0009) X

Roller Lube Supply Pump (400-EM-0605/0704/0804) Rollers in Lowered Position (400-

XSV-1103 de-energized) for 20 Minutes

X

Roller Lube Return Pump (400-EM-0612/0708/0808)

Roller Lube Supply Pump Running (400-EM-0605) X

Classifier Lube Circulating Pump (400-EM-0015)

Lube Flow (400-FZA-0019) NOT Low Low X

12 EXTERNAL SYSTEM INTERLOCKS This section discusses interlocking of external components (outside of the 400 section) with calciner system components.


Revision 2


12.1 CRS WEIGH FEED BELT (200-FD-085)



X X


Calciner in System Idle Operating Mode X

Calciner in CRS Feed Start Mode X

Rotary Valve 400-AL-010 Operating X X

Calciner Collection Cyclone Off Gas Temperature >275°C (400-XY-0131) X

CRS Feed Bin (200-BN-085) CRS Level NOT Low X

Roller Mill Drive (400-EM-0009) Operating X X

Roller Mill Operating Interlocks Satisfied X

Cyclone Discharge Valves are Operating (400-AL-060, 400-AL-065, 400-AL-020 and 400-AL-025)

X X

Calciner Cyclone Discharge Diverter Gate 400-GA-060 is in a Closed Position (400-GBS-0154B)

X

ESP Fields Energized X X

ESP Dust Screw (400-SC-040) and Discharge Valve (400-AL-030) are Operating

X

Transport System Between ESP Rotary Discharge Valve 400-AL-030 and Bin 400-BN-040 is Operating

X

Mill Bypass Damper 400-DA-020 is 100% Open X

No Active Calciner System Alarms X

CRS Feed Belt Operation at Minimum Feed Rate (70%)

Calciner Cyclone Exit Temperature Control Loop (400-CTL-01) Activated X

Calciner Inlet Temperature Control Loop (400-CTL-02) Activated X

Mill Flow Control Loop (400-CTL-03) Activated X

CRS Feed Belt Manual Rate Adjustments (Increase/Decrease)

Calciner Pressure Control Loop (400-CTL-04) Activated X


Revision 2




Mill Outlet Temperature (400-TICSA-0004) NOT Low (If Low, Cannot Increase)

X X

Mill Outlet Temperature (400-TICSA-0004) NOT High (If High, Cannot Decrease)

X X

Mill Main Motor (400-EISA-I-0009) Power Draw NOT High (If High, Cannot Increase)

X X

Classifier Motor (400-EISA-I-0010) Power Draw NOT High (If High, Cannot Increase)

X X

No Active Calciner System Alarms (Applies to Rate Increases Only) X


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6.9 Washout procedures roller mill and calciner section

MAGADI PURE ASH PROJECT FFEM PROJECT NO. 03-51573 ROLLER MILL AND FLASH CALCINER SYSTEM FFEM DOCU. NO. 5.401354 DOCU. NO. 2076-FF-400-PR-WP-001 DATE: FEB,28,2005 REV. 0 MAGADI WASH DOWN PROCEDURE General Safety – Material within a plugged vessel can remain very hot long after the air heater is shut down. Extreme care must be exercised when washing down any vessel with material inside. Hazards include and are not limited to: steam explosions, hot water discharge, sudden release of buildup and caustic spent wash water. Wash downs should be done as infrequently as possible and only by adequately trained personnel following proper safety procedures. General Safety – It is better to clear blockages with mechanical rappers, air cannons, and compressed air lances before trying to clear blockages with water or steam. NOTE: COMPRESSED AIR AND AIR CANNONS CAN CAUSE LOCAL OVERPRESSURE IN VESSELS. THESE CAN FORCE HOT FINE DUST FROM INSPECTION PORTS AND DOORS LEADING TO SEVER BURNS. Automatic air cleaning devises such as air cannons must be disengaged before opening any access doors or ports. Blow downs should be done by adequately trained personnel following proper safety procedures. Calciner:

1. Stop feed, shutdown and cool system as per the Operating Instructions. 2. Shutdown all fans except the ID fan and prepare system for access as per

the Operating Instructions. Adjust the ID fan inlet damper to obtain 25-50mm suction in the calciner plenum.

3. Open one access hatch on the calciner plenum to permit the discharge of wash water. Exercise caution when opening this hatch as hot material may have accumulated behind the hatch. Personnel should be positioned such that the discharge of hot material through the hatch will not result in personnel injury.

4. Once the hatch is open, clear material away and setup a containment area to collect wash water discharging through the hatch.

5. Open the uppermost inspection port on the calciner. Perform cleaning as required, close port and proceed to the next lowest port. Repeat this procedure until the calciner has been cleaned at all levels above the grid plate.

6. Open one or more hatches above the grid plate level. Clean the lower calciner area, feed inlet splash box, and upper grid surface. Close hatches and secure. This cleaning should be performed without entering the calciner. If entry is required, follow plant procedures for confined space entry and ensure that there are no coatings in the calciner that could break free from the calciner walls and injure personnel.

7. Open the inspection port below the grid plate. Perform a wash down of the lower plate surface if required and then close the port.

8. Open the remaining hatches on the calciner plenum section while exercising caution against hot material that may be accumulated on the back side of the hatch. Wash down the plenum inventory and direct it to the hatch opening where the containment area has been setup. Use tools as required to pull sludge and free standing water from the plenum. Once complete close and secure all hatches.

Calciner Collection Cyclone: 1. Stop feed, shutdown and cool system as per the Operating Instructions. 2. Shutdown all fans except the ID fan and prepare system for access as per

the Operating Instructions. Adjust the ID fan inlet damper to obtain 25-50mm suction at the calciner exit.

3. Position the diverter gate to direct cyclone discharge to the dump tank. 4. Activate cycling of the discharge tipping gates. 5. Open an inspection hatch on the cyclone body. Utilize a high intensity

light source to inspect the cyclone interior. 6. If material is observed above the tipping gates and there is no material

flow to the dump tank, close the inspection hatch and activate the cyclone cone rappers. If this does not initiate material flow, activate the air cannons. Once it is confirmed that all ports on the calciner system are closed and no one is working inside the system, fire the air cannons.

7. Once the cone inventory has been discharged and the cone area has been allowed to cool, proceed with the final wash down.

8. Following completion of the wash down, close and seal all hatches. Calciner Off Gas Ducting:

1. There are no provisions for wash down of this ducting. Roller Mill:


the Operating Instructions. Close the mill inlet shutoff damper (if not already closed) and adjust the ID fan inlet damper to obtain 25-50mm suction at the mill inlet. Close down the mill bypass damper if required to generate the necessary mill inlet suction.

3. Ensure that the mill rollers and table are cool before adding water to the mill as these large castings may crack due to thermal shock.

4. Open the mill body inspection hatch. Wash down the classifier louvers, mill body and upper inlet louver area as required. Once complete, close the hatch.

5. Open the mill plenum inspection hatch. Wash down the plenum area and underside of the louvers as required. Close hatch.

Roller Mill Cyclone:


the Operating Instructions. Adjust the ID fan inlet damper to obtain 25-50mm suction at the roller mill exit.

3. Blank off the material discharge duct and remove the blank to the dump line. Position a collection hopper under the line.

4. Activate the discharge rotary valve. 5. Open an inspection hatch on the cyclone body. Utilize a high intensity

light source to inspect the cyclone interior. 6. If material is observed above the rotary valve and there is no material flow

to the dump bin, close the inspection hatch and activate the cyclone cone rappers. If this does not initiate material flow, activate the air cannons. Once it is confirmed that all ports on the calciner system are closed and no one is working inside the system, fire the air cannons.

7. Once the cone inventory has been discharged and the cone area has been allowed to cool, proceed with the wash down.

8. Following completion of the wash down, close and seal all hatches. ESP Cyclone:


the Operating Instructions. Adjust the ID fan inlet damper to obtain 25-50mm suction at the ESP cyclone inlet.

3. Blank off the material discharge duct and remove the blank to the dump line. Position a collection hopper under the line.

4. Activate the discharge rotary valve. 5. Open an inspection hatch on the cyclone body. Utilize a high intensity

light source to inspect the cyclone interior. 6. If material is observed above the rotary valve and there is no material flow

to the dump bin, close the inspection hatch and activate the cyclone cone rappers. If this does not initiate material flow, activate the air cannons. Once it is confirmed that all ports on the calciner system are closed and no one is working inside the system, fire the air cannons.

7. Once the cone inventory has been discharged and the cone area has been allowed to cool, proceed with the wash down.

8. Following completion of the wash down, close and seal all hatches. ESP Plates/Hopper:

1. Stop feed, shutdown and cool system as per the Operating Instructions.

2. Shutdown all fans except the ID fan and prepare system for access as per the Operating Instructions. Adjust the ID fan inlet damper to obtain 25-50mm suction at the ESP inlet.

3. Activate the ESP fines purge rotary valve and ESP screw. NOTE: The ESP is a source of extremely high electrical voltage capable of severely injuring or killing personnel. The voltage cannot be seen or detected in any way without instrumentation. Only properly trained individuals following all plant and ESP manufacture’s recommendations for safety shall clean the ESP. 4. Open an inspection hatch on the ESP body. Utilize a high intensity light

source to inspect the ESP interior. 5. If material is observed above the screw and there is no material flow to the

ESP fines purge circuit, close the inspection hatch and activate the hopper rappers.

6. Inspect the collection plates. If heavy coatings are observed, close the unit and activate the plate rappers. Permit several rapping cycles, de-energize and then inspect.

7. Once the hopper inventory has been discharged proceed with the wash down.

8. Following completion of the wash down, close and seal all hatches.


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7 CRYSTALLIZATION


7.1.1 Introduction

The crystallization section serves to remove impurities from milled calcined soda ash. The ground calcine is expected to contain 95.4% sodium carbonate, 3.0% sodium fluoride, 0.26% sodium chloride, 0.84% sodium sulfate, and 0.5% insoluble material. The re-crystallization process will include two stages. Both stages are necessary to achieve the required product purity. In the first stage hot, dry anhydrous soda ash is slurried with near-saturated sodium carbonate solution to produce sodium carbonate monohydrate. The anhydrous sodium carbonate dissolves as sodium carbonate monohydrate crystallizes. The operating conditions provide for the growth of well formed sodium carbonate monohydrate crystals while the other impurities either dissolve or remain as very small solid particles. The resulting slurry is then transferred to the first stage elutriator where the fine impurities are flush out the top while the larger monohydrate crystals settle and are separated on the first stage centrifuges. In the second stage process, the sodium carbonate monohydrate crystals from the first stage are combined with saturated liquor and this slurry is transferred to the anhydrous reactor, where it is heated above the transition temperature. The monohydrate crystals dissolve while anhydrous sodium carbonate crystallizes. The anhydrous slurry is then transferred to the second stage crystallizer where it is cooled below the transition temperature, causing the anhydrous crystals to dissolve while monohydrate crystals form. The second stage elutriator separates the fines from the coarse product and the second stage centrifuges recover the monohydrate product. Each time the re-crystallization is performed, insoluble impurities are liberated and separated, resulting in a purer product.

7.1.2 First stage crystallization (PFD 500-01)

The hot calcine will be fed from the flash calciner cyclone via an air lock, calcined feed chamber 510-CH-010 and calcined feed hydrator 510-CY-012 to the first-stage crystallizer 510-EV-010. The positive air flow with the hot calcined ash feed will prevent steam condensation and plugging of the feed ductwork after the air lock. First stage vent fan 510-FN-010 will remove water vapor from the crystallizer and provide a means of crystallizer temperature control. The air and water vapor is exhausted to atmosphere


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through first stage scrubber 510-DC-015 to recover entrained dust and liquor. 510-EV-010 is provided with a wall wash to periodically wash and dissolve any wall accretions. The scrubber sprayers are fed directly with cold process water. In this way water condensation in the scrubber is increased which improves the scrubber efficiency for dust removal. The scrubber liquor discharge is cooled with process water feed to the hot process water tank 520-TK-091. In this way heat is removed from the first stage crystallization system: less water vapor is emitted to atmosphere, and process water feed to the hot process water tank 520-TK-091 is preheated. The first-stage crystallizer is circulated by a bottom entry draft tube agitator 510-AG-010. The agitator induces an internal circulation of slurry up the draft tube and down the annular region outside the draft tube. The incoming ground calcine is sluiced with slurry in the hydrator and combined with the bulk circulating slurry in the crystallizer. The calcine (anhydrous sodium carbonate) dissolves and re-crystallizes as sodium carbonate monohydrate. Control of supersaturation levels through retention time, recirculation rate, and crystal slurry density control allows the crystals to grow to the desired average size of 350 microns. The first stage crystallizer will operate at about 97 to 98°C and 35% solids and will provide two hours of retention time. The crystallization chemistry is shown below. Na2CO3 (calcine) → Na2CO3 (aq) Na2CO3 (aq) + H2O → Na2CO3.H2O (monohydrate) The magma withdrawn from the first-stage crystallizer is pumped to the top of the first stage elutriator 510-SP-025. Overflow liquor from the first stage settler 510-TK-050 is pumped to the bottom of the first stage elutriator by first stage settler overflow pumps 510-PP-060/1. The coarse crystals descend through the elutriator. A net upward velocity of about 6 mm/s is required to remove the fine (less than 105 micron) sodium fluoride and insoluble particles. Some fine (less than 125 micron) sodium carbonate monohydrate will also be lost. The rejected fines overflow the elutriator to the first stage deaerator 510-DE-050. The elutriator will reject approximately 90% of the solid sodium fluoride and 80% of the insolubles. The deaerator separates entrained air that would interfere with liquor clarification. Process water, first-stage elutriated solids, centrate, guar gum and first-stage settler underflow solids combine and gravity flow to the first stage settler feedwell. Guar is added at a dosage of 80 g/t solids. The settler underflow at about 20% solids will be pumped by 510-PP-050/1 to the paddock slurry tank 900-TK-260. It is predicted that the solids in the settler underflow will contain about 80% by weight of sodium fluoride, representing approximately 70% of the quantity entering the process. The first stage settler underflow is


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the main purge of impurities from the first and second stage crystallizer circuit. The high fluoride slurry will be combined with other waste streams in the fluoride slurry tank. The slurry will then be pumped back to a separate isolated area on the lake, where the slurry will be placed in the bottom of the paddock to keep the fluoride containing solids submerged. Water is lost from the first stage crystallizer by evaporation, monohydrate formation, discharge of the first settler underflow and discharge of the settler overflow. To maintain the solution balance it is necessary to replace the lost water with process water. Some of the required water is added to the deaerator to dissolve fine soda ash that would otherwise be lost with the settler underflow. The first stage settler overflows to the first stage settler overflow tank 510-TK-060, where it will combine with liquor pumped from the second stage filter. The volume of liquor pumped from the second stage settler to the first stage is controlled by the liquor inventory in the second stage. Liquor collected in the settler overflow tank is used for density control in the first stage crystallizer, for flushing in the elutriator and for discharge to the tailings tank. The sodium sulfate concentration in the crystallizer liquor must be controlled below about 3% to avoid product contamination. The discharge rate to the tailings tank controls the sodium sulfate concentration in the first stage crystallizer. Crystal slurry at 50 to 60% solids density is withdrawn from the bottom of the elutriator and flows by gravity to the first stage centrifuges 510-CF-035/6. The first stage centrifuges are an important purification step in the process. The removal of soluble impurities achieved during centrifuging and washing allows the second stage crystallization to operate at lower impurity levels than the first stage. The first stage centrifuges will produce 70 t/h of wet crystals at 4% to 5% moisture with an expected analysis of 99.5% sodium carbonate monohydrate, 0.2% sodium fluoride, and 0.08% insolubles. The crystals will be collected in the second stage crystallization feed tank 520-TK-005. Guar is delivered in bags of 50 kg. For the preparation of a guar solution an automated system is used. Guar is brought into powder storage hopper 510-TK-071, from which it is dosed on demand by screw feeder 510-SC-070. Guar solution is prepared by dissolving guar in process water to about 0.3 wt% solution in guar make-up tank 510-TK-070 with the aid of guar make-up agitator 510-AG-070. The resulting viscous solution is transferred to the guar storage tank 510-TK-071 by guar transfer pump 510-PP-070/1. Guar metering pumps 510-MP-070/1 dose the guar solution to tailings settler deaerator 200-DE-050. Guar metering pumps 510-MP-072/3 dose the guar solution to first stage settler deaerator 510-DE-050 and guar metering pumps 510-MP-074/5 dose the guar solution to second stage settler deaerator 520-DE-050.


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7.1.3 Second stage crystallization (PFD 500-02)

The first stage crystallizer achieves a major reduction of sodium fluoride and insolubles but will not reach the targeted 0.02 % purity level for NaF. Two stages of re-crystallization are required. In the second crystallization stage sodium carbonate monohydrate is cycled between the anhydrous and monohydrate crystal forms by heating and then cooling. The theoretical transition temperature from monohydrate to anhydrous sodium carbonate in the absence of impurities is about 109 °C. However, to convert monohydrate to anhydrous crystals at a reasonable rate, the transition temperature should be taken in practice as 112°C. The actual design basis for the second-stage anhydrous reactor of 120°C provides an appropriate operating margin above this transition temperature. In the process the first stage crystal slurry will be heated to 120°C and then cooled by evaporation to 97°C. The heating stage is performed in the second stage anhydrous reactor, while monohydrate crystallization occurs in the second stage crystallizer. The anhydrous reactor 520-EV-010 is a forced circulation type crystallizer. The vessel will operate at about 1.65 to 1.95 bar(a) and will provide two hours of slurry retention time. The required heating is provided by circulating magma through a steam heated, single pass, vertical shell and tube heat exchanger 520-HX-010. Anhydrous sodium carbonate has a steep and inverse solubility. High tube side velocities (>2 m/s) and low shell side steam pressure (2.2 bar(a)) minimizes tube side fouling. A steam driven thermo compressor will be employed to economize on steam use. Condensate from the heat exchanger will flow to the condensate tank 520-TK-045 for return to the boiler. The crystal slurry in the second stage crystallizer feed tank 520-TK-005 is maintained at about 50% solids by recycling centrate and filtrate from the downstream equipment. Slurry from the feed tank is further diluted to 35 wt% with additional filtrate and pumped to the anhydrous reactor 520-EV-010. The anhydrous reactor heats the incoming monohydrate slurry above the transition point, generating an anhydrous slurry of about 28% solids. The product from the anhydrous reactor is transferred to the second stage monohydrate crystallizer 520-EV-020 that is similar in design to the first stage crystallizer. The liquid level within the monohydrate crystallizer provides sufficient submergence above the anhydrous slurry injection point to avoid solution flashing. The evaporation that cools the monohydrate crystallizer occurs at the liquid vapor interface. A mist eliminator in the top of 520-EV-020 removes droplets from the evaporated water. A portion of the overhead vapor flows to the thermo compressor 520-SJ-010, the remainder flows to the condenser 520-HX-020 for water recovery. The condenser will use washery cyclone overflow as the cooling media. The warm slurry stream (50°C) will flow to the tailings tank for disposal to the lake. Non-condensable gases will be exhausted from the condenser by vacuum pump 520-PP-022/3.


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The magma withdrawn from the second-stage crystallizer is pumped to the top of the second stage elutriator 520-SP-025. The monohydrate crystal slurry is elutriated with filtrate from a polishing filter (PFD 500-04). The coarse crystals descend through the elutriator. A net upward velocity of about 6 mm/s is required to remove the fine (less than 105 micron) sodium fluoride and insoluble particles. Some fine (less than 125 micron) sodium carbonate monohydrate will also be lost. The rejected fines overflow the elutriator to the second stage deaerator 520-DE-050. The elutriator will reject approximately 90% of the solid sodium fluoride and 80% of the insolubles. Magma at 50 to 60% density is transferred by gravity from elutriator 520-SP-025 to the second stage centrifuges 520-CF-035/6 (PFD 500-03).

7.1.4 Second stage monohydrate centrifuges (PFD 500-03)

Monohydrate crystals are separated from the brine by centrifuges 520-CF-035/6. These centrifuges will produce 66 t/h of wet crystals at 4% to 5% moisture with an expected analysis of 99.96% sodium carbonate monohydrate , <0.03 % sodium fluoride; and <0.02% insolubles The crystals will be transported to the fluid bed dryer by second stage belt conveyor 520-CV-040. Centrate is collected in second stage centrate tank 520-TK-040. The centrate is used to transport dust from the fluid bed to the second stage feed tank (see section 600). From centrate tank 520-TK-040 the centrate is pumped by second stage centrate pumps 520-PP-040/1 to feed tank 520-TK-005 via the dust system of the 600 section. The surplus of centrate is returned to centrate tank 520-TK-040.. For flushing lines and washing on the monohydrate centrifuges hot water is pumped by hot water pump 520-PP-091/2. This water is heated to 90 °C in hot process water heater 520-HX-091 by low pressure steam. The pressure in the header is maintained by a pressure controller in the return line to hot process water buffer 520-TK-091.

7.1.5 Liquor polishing (PFD 500-04)

Deaerator 520-DE-050 separates entrained air that would interfere with liquor clarification. Guar gum, process water and the second stage elutriated solids combine and gravity flow to the second stage settler 520-TK-050. Guar is added at a dosage of 5 mg/l. The settler underflow at an expected 15% solids will be pumped to the fluoride slurry disposal system. The settler overflow containing an estimated 100 mg/I of suspended solids will flow to the filter feed tank 520-TK-060.


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Two pre-coat filters 520-FL-060/1 are included in the crystallizer train to achieve maximum clarity of recycle liquor. The filters each provide 124 m2 of filtration area and reduce the suspended solids to less than 10 mg/l. The filter elements are vertical leafs consisting of a stainless steel backing cloth that supports a polypropylene media. The actual filter media is, however, fine diatomaceous earth. In operation the filter leafs are initially coated with a thin layer, 3 mm thick, of diatomaceous earth (precoat). Once precoated, the filters are continuously fed with clarified solution by polishing filter feed pump 520-PP-060/1. A small flow of diatomaceous earth slurry at 10% solids is metered into the filter to provide a continuous diatomaceous earth membrane. This addition, termed "filter aid" or "body mix", maintains filtration rates by preventing the fine suspended solids from blinding the filter surface. The filters operate until a pre-determined differential pressure is reached, typically 2.0 bar(a). At that time the filter enters a blowdown and backflush cycle in which the filter chamber drains and collected solids are sluiced off the leaves. The filter cake slurry is pumped to the fluoride slurry tank 900-TK-260 for disposal to the lake. The filters are automated and operate on a batch cycle. The estimated cycle time is 2 to 3 days. This will be controlled by the clarity of the second stage settler overflow. The diatomaceous earth consumption will be determined by the clarity of the filter feed solution. Plate and frame heat exchanger 520-HX-065 will be used to heat the filtered liquor during start-up. The condensate from this start-up heater will flow to the condensate tank 520 TK-045 (500-02). Condensate from all sources will be pumped from the condensate tank to the boiler feed water tank.


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7.2.1 First stage crystallizer (PID 510-01)

The temperature 510-TICA-0001 of first stage crystallizer 510-EV-010 is controlled by the speed of first stage vent fan 510-FN-010. The speed of the fan increases when the temperature is above its setpoint. As a consequence more air is sucked into feed chamber 510-CH-010 and more evaporation of water takes place. The increase in evaporation rate decreases the operating temperature. The operating pressure 510-PIA-0001 follows by the physics of the system. It depends on the operating temperature, the operating capacity, the pressure drop over the hydrator 510-CY-012 and the atmospheric pressure. The density inside the first stage crystallizer is controlled with the feed rate of liquor from settler overflow (510-FCV-0001). As a consequence the liquor feed rate to the hydrator varies with the capacity, because hydrator feed pump 510-PP-010/011 runs at a fixed speed. The level inside the first stage crystallizer is controlled with the speed of slurry pump 510-PP-020/021. The wall of the crystallizer above the slurry surface is kept clean with periodic water spraying. Water is added via an automated timer. In case of insufficient washing, scale can grow on the wall, which can cause plugging or damage pumps if lumps of scale fall into the slurry. Two sets of sight glasses are provided on the crystallizer body. The sight glasses on the cylindrical wall are used to monitor the level. The proper operating level is between the two sight glasses, so the bottom one is submerged while the upper one is exposed. The other two sight glasses are in the top conical section. They are used to view the walls and the incoming slurry from the hydrator. The wall wash frequency is set based on observations through these sight glasses. The dissolved sodium sulfate concentration in the slurry has to be below 3 wt% to prevent crystallization of berkeite (2Na2SO4.Na2CO3) along with the monohydrate crystals. Samples have to be taken every 2 hours (check) to analyze the sodium sulfate content. A too high concentration means more water has to be added to the system, which results in more blow down from 510-TK-060 (via 510-LCV-0401). This is done by increasing the water flow rate to the second stage deaerator (520-FIC-0701). If the concentration is


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below 2.5 wt% (check), then the amount of water can be decreased in order to reduce product loss and water consumption. Most of the water that comes into the process should be added to the second stage deaerator. This will maximize the dissolution of impurities from the final product. The water addition to the first stage deaerator is adjusted to dissolve sodium carbonate monohydrate solids that come from the first stage elutriator overflow and the first stage centrifuge. The first stage scrubber serves to wash out solids from the vapor stream. The scrubber should typically be operated once through. Process water is added (510-FICQA-0003) at a typical rate of 20 m3/h. If the process water addition rate needs to be reduced below 20 m3/h, scrubber effluent should be partially recirculated to maintain the flow to the spray nozzles. Cold process water is added to the scrubber for the following purposes: – To keep the saturation in the scrubber system below 50% – To dissolve sodium monohydrate crystals in the elutriator overflow, which takes place

in the deaerator 510-DE-050. As the required amount of the above purposes fits the circulation rate of the scrubber liquor, cold process water is fed at a fixed rate (510-FICQA-0003), without circulation of liquor. In this way the scrubber is washed with cold water which is beneficial for dust removal. The scrubber effluent liquor is cooled using plate heat exchanger 520-HX-015. Cooling is provided by process water which is feed to the hot process water tank. The process water flow rate through the cooler is fixed. During normal operation more process water is needed for the hot process water tank and is added to 520-TK-091 directly.

7.2.2 First stage elutriator (PID 510-02)

The flow rate of washing liquor from the settler overflow to the elutriator is set with 510-FIC-0101. The flow is distributed with manual valves over two inlet connections. The position of these valves is set during start-up. The flow rate determines the solids concentration in the bottom outlet, as well as the degree of washing, and the loss of product in the top outlet. The level of slurry inside the washing leg is measured with 510-LICSA-0101, which is in fact a pressure differential measurement. The output signal of this controller is the master that sets a certain power consumption 510-EICSA-0201/0204 of the first stage centrifuges


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510-CF-035/36. The centrifuge power consumption is proportional to the amount of solids that are recovered. The slurry outlet valves of elutriator (510-ECV-0201/0204) are opened to a degree that the power consumption meets the set value. The wash liquor flows upward through the elutriator, until the overflow rim at the top. It then flows by gravity to the deaerator. The overflow rim fixes the liquid level in the elutriator.

7.2.3 First stage centrifuges (PID 510-03)

The centrifuges run at a fixed speed. The power consumption 510-EICSA-0201/0202 is recorded and sets the supply rate of slurry (see section 7.2.2). The cake is washed with hot process water at a controlled rate (510-FIC-0201/0202). The centrifuge is flushed periodically (see section 7.7.14)

7.2.4 First stage settler (PID 510-04)

The first stage settler 510-TK-050 is fed via first stage settler deaerator 510-DE-050. In this deaerator first process water is introduced. The amount of process water is flow controlled with a manual setpoint on 520-FIC-0301, based on dissolution of monohydrate. Next the discharge from the first stage scrubber is fed, followed by the discharge streams from the sumps. Subsequently the thin slurry streams of elutriator overflow and centrate are introduced and finally the guar gum and recycle sludge. For a proper distribution the guar gum is sprayed. All streams to the deaerator are introduced at the inlet section in order to provide some residence time. Discharge from sumps is not allowed in case the sumps are contaminated with non product related materials (like filter aid). See PID 520-08 and 520-09. The first stage settler is provided with a rake mechanism 510-TM-050. At high torque, the rake arms are lifted automatically. The sludge underflow from the tailings settler is pumped by 510-PP-050/051 to paddock slurry tank 900-TK-260. Part of the underflow is recycled to the deaerator. The speed of these pumps is manually controlled by 510-HIC-0301/2. Operator adjustment of the speed is based on the sludge level of the settler, given by 510-LI-0301. Setpoint for 510-LI-0301 is provided on setting list. High level (small number of discs can be seen) can mean a lot of sludge inside the settler, or poor separation (high turbidity). When turbidity is high, several vague discs are seen. When the level is high, operator has to check the turbidity by sample and analysis.


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The overflow from the tailings settler is collected in the first stage settler overflow tank 510-TK-060.

7.2.5 First stage settler overflow (PID 510-05)

The overflow from the tailings settler is collected in the first stage settler overflow tank 510-TK-060. Settler overflow liquor is pumped to the calcined feed hydrator 510-CY-012 and to first stage elutriator 510-SP-025 by first stage settler overflow pump 510-PP-060/1. Part of the overflow liquor is discharged via 510-LCV-0401 to 900-TK-250 to control the level in settler overflow tank 510-TK-060.

7.2.6 Guar make-up, transfer and distribution (PID 510-07)

The guar preparation is an automated system. The operator supplies guar to the hopper 510-TK-071 (approx. one 50 kg bag per day).

7.2.7 Second stage crystallization feed (PID 520-06)

First stage centrifuge cake and second stage centrate are discharged into the second stage crystallization feed tank 520-TK-005. The slurry concentration is approx. 50 wt%. The total net buffer capacity is approx. 300 ton slurry. Operating temperature is around 97°C. The tank is agitated with second stage crystallization feed tank agitator 520-AG-005. The slurry density (520-DICA-0002 on P&ID 520-01) of the feed to the anhydrous reactor is approx. 31 wt%. This density is controlled with the flow of filtrate from 520-PP-065/6. The second stage crystallizer feed tank serves as buffer tank between first and second stage. This tank is not under automatic level control. The level and the suspended solids concentration in this tank will vary depending on the relative production rates of the first stage and second stage crystallization circuits. The second stage crystallization feed tank can also provide surge volume for 2 different situations: 1 First stage is not running or on stand-by, while second stage is in operation 2 Second stage is not running or on stand-by, while first stage is in operation


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The normal slurry level to be operated at should provide a buffer time for unexpected interruption of production of both first and second stages. If the tank is operated at 70%-75%, then a buffer capacity of 1 - 1.5 hours is provided for both cases. In case a stand-by mode is scheduled for first or second stage, then the tank can be operated at max or min level, depending on which section will be put on stand-by. A maximum buffer capacity for failure of the first stage of 2.4 hours is created with a full tank (90%). The maximum buffer capacity for adding cake from first stage crystallization of about 2.5 hours is created at a starting level of 55 – 60%.

7.2.8 Second stage anhydrous reactor (PID520-01)

The slurry feed rate to the anhydrous reactor 520-EV-010 is set with 520-FIC-0001, which acts on the pump speed of second stage feed pump 520-PP-005/006. The slurry concentration in feed tank 520-TK-005 is approx. 50 wt%. The slurry is further diluted to 35% with filtrate as controlled with 520-DICA-0002. The operating temperature inside the anhydrous reactor is 120°C. The temperature is controlled with 520-TICA-0001 that adjusts the steam supply to the anhydrous heater 520-HX-010. In order to minimize scaling in the heater 520-HX-010, the following temperature differences have to be within a narrow range: 1 Temperature Rise - slurry outlet and inlet temperature 520-TDIA-0005 (520-TI-

0002/0003) 2 Average Delta T - steam side and average of slurry outlet and inlet temperatures

520-TDIA-0006 (520-TIA-0004/0002/0003) If scale is growing inside the heat exchanger tubes, it adds resistance to heat transfer and requires an increased temperature difference (delta T) in order to maintain capacity. Therefore, the average temperature difference (delta T) will be monitored to detect scaling. If the average temperature difference for a certain capacity increases, it is possible that this is caused by scaling, see further in section 7.7.10. The operating pressure inside is the sum of the saturated vapor pressure of the slurry (1.7 bar(a) at 120°C) and the partial pressure of inert gasses (air) that remain from the initial filling or from accumulating over time. If the operating pressure builds over time, inert gasses should be slowly purged through the manual vent valve at the top (the vent will contain primarily steam). The circulating flow rate of slurry through 520-HX-010 is fixed. The level inside 520-EV-010 is controlled with the flow rate to the second stage crystallizer 520-EV-020 (520-LCV-0001A/B)


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Condensate from the anhydrous heater 520-HX-010 is collected in 520-TK-010 and discharged to the condensate tank 520-TK-045. Vent valves on the shell side of the heater are partially open in order to prevent accumulation of inert gasses.

7.2.9 Second stage crystallizer (PID 520-02)

The second stage crystallizer 520-EV-020 is kept at boiling conditions at a pressure of about 0.8 bar(a), which is -0.16 bar(g). The pressure is controlled by regulating the air inlet (520-PCV-0101) of the vacuum pump system 520-PP-022/023. The corresponding operating temperature is 97°C. Some of the vapor from the boiling crystallizer flows to the suction side of thermo compressor 520-SJ-010 and the balance flows to the second stage vent condenser. The slurry concentration is not directly controlled but is the result of the slurry concentration being fed to the anhydrous reactor. The level inside 520-EV-020 is controlled by the speed of slurry pump 520-PP-020/021. The wall of the crystallizer above the slurry surface and the demister are kept clean with periodic water spraying. Water is added via an automated timer. In case of insufficient washing, scale can grow on the wall, which can cause plugging or damage pumps when it falls into the slurry. The vapor which is not drawn into the thermo compressor is condensed in the second stage vent condenser 520-HX-020. The cooling in the condenser is provided by liquor from the washery and the flow is set via the temperature of the outgoing cooling medium. The vent from the condenser is connected to the inlet of the vacuum pump. The condensate from the condenser flows to the condensate tank 520-TK-045 by gravity.

7.2.10 Second stage elutriator (PID520-03)

The flow rate of washing liquor from the filtrate tank (520-TK-065) is set with 520-FIC-0201. The flow is distributed with manual valves over two inlet connections. The position of these valves is set during start-up. The flow rate determines the solids concentration in the bottom outlet, as well as the degree of washing, and the loss of product in the top outlet. The level of slurry inside the washing leg is measured with 520-LICSA-0201, which is in fact a pressure differential measurement. The output signal of this controller is the master, that sets a certain power consumption 520-EICSA-0301/0304 of the second stage centrifuges 520-CF-035/36. The slurry outlet valves of the elutriator (520-ECV-0301/0304) are opened to a degree that the power consumption meets the set value.


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The wash liquor flows upward through the elutriator, until the overflow rim at the top. It flows by gravity to the deaerator. The overflow rim fixes the liquid level in the elutriator.

7.2.11 Second stage centrifuges (PID 520-04)

The centrifuges run at a fixed speed. The power consumption 520-EICSA-0301/0304 is recorded and sets the supply rate of slurry (see section 7.2.10). The cake is washed with hot process water at a controlled rate (520-FIC-0301/0302). The centrifuge is flushed periodically (see section 7.7.14)

7.2.12 Second stage thermo compressor (PID 520-05)

The pressure of the 15 bar steam supply (520-PICA-0401) is reduced to a fixed value of 14.5 bar(a). This is the drive medium for the thermo compressor. Water vapor from the second stage crystallizer 520-EV-020 and the condensate tank 520-TK-045 are connected to the suction side. The superheated outlet of the thermo compressor is saturated in the desuperheater 520-DS-010.The temperature downstream of the desuperheater is controlled by the supply of condensate. The flowrate of steam to the anhydrous reactor heater 520-HX-010 is controlled by setting the recycle flow to the suction side of the thermo compressor. The pressure is not controlled and is set by the suction conditions of the steam jet and the compressor efficiency.

7.2.13 Second stage centrate tank (PID 520-07)

The centrate is used to transport dust from the fluid bed to the second stage feed tank (see section 600). The surplus of centrate is transferred to the feed tank 520-TK-005. The temperature of the centrate return from the dryer is a few degrees Celsius higher because of heat of dissolution and the high temperature of the dust. Also the solids concentration is higher. To prevent overheating and plugging, the dryer fines recycle has to be shut down when there is no feed of centrate from the centrifuge. The level in the second stage centrate tank 520-LICSA-0601 is controlled by 520-LCV-0601.

7.2.14 Second stage settler (PID 520-08)

Second stage settler 520-TK-050 is fed via second stage settler deaerator 520-DE-050. In this deaerator first hot process water is introduced. The amount of process water is flow controlled by 520-FCV-0701 with a manual setpoint (see setting list), based on dissolution of monohydrate and on the sodium sulfate concentration (see section 7.2.1). Next the discharge from the vacuum pumps is fed. Subsequently the thin slurry stream of elutriator


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overflow is introduced and finally the guar gum and recycle sludge are added. For a proper distribution the guar gum is sprayed. All streams to the deaerator are introduced at the inlet section in order to provide some residence time. The overflow of the settler is a clear liquid. High solids concentration in overflow causes high cake growth on the polishing filters and therefore a shorter operating time. If the overflow liquor is not clear, the following items should be checked: – Sludge level not too high (520-LI-0701) – Check guar dosing rate – Consider an increase of guar supply and/or underflow recycle High level (small number of discs can be seen) can mean a high sludge level in the settler, or poor separation (high turbidity). When turbidity is high, several vague discs are seen. When the level is high the operator has to check the turbidity by sample and analysis. The second stage settler is provided with a rake mechanism 520-TM-050. At high torque, the rake arms are lifted automatically. Sludge from the settler is pumped by 520-PP-050/051. The speed of these pumps is manually controlled by 520-HIC-0701/2. Operator adjustment of the speed is based on the sludge level of the settler, given by 520-LI-0701. Setpoint for 520-LI-0701 is provided on the setting list. The content of the sump 520-SU-095 can be transferred to the first stage settler deaerator 510-DE-050. This is allowed only if the sump contains useable clean liquor or product and is not contaminated with non-product materials like filter aid, guar, mud etc. At high level 520-LS-0702 in sump 520-SU-095 sump pump 520-PP-095, is started automatically and at low level 520-LS-0702 this pump is stopped automatically. Sump agitator 520-AG-095 is started and stopped by hand locally. The agitator is normally kept running.

7.2.15 Polishing filter feed (PID 520-09)

The level of filter feed tank 520-LICSA-0802 provides the set point for filter feed flow controllers 520-FIC-0901/2. In order to let 520-TK-060 act as a buffer and not disturb the filtration process this is a slow control. The level in this tank is kept low during normal operation. When the filter regeneration sequence starts, the level in the tank will increase.


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When regeneration is completed, the tank will be brought back to a low level with increased flow rate. The capacity of this system is sized for the crystallization unit running at 100% capacity, one filter being regenerated, and one in operation. It is not possible to regenerate both filters at the same time, and keeping operating capacity at 100%. Flow rate over the filter has to be constant in order to reduce damage of filter cake. If flow is stopped, then the cake may start to fall off. Therefore, filter feed pumps 520-PP-060/1 are provided with automatic changeover. The content of the sump 520-SU-100 can be transferred to the first stage settler deaerator 510-DE-050. This is allowed only if the sump contains useable clean liquor or product and is not contaminated with non-product materials like filter aid, guar, mud etc. At high level 520-LS-0803 sump pump 520-PP-100 is started and at low level 520-LS-0803 this pump is stopped automatically.

7.2.16 Liquor polishing (PID 520-10)

Both filters are operated in parallel. When the cake thickness increases the pressure drop over the filter will increase. At a differential pressure of 2 bar (520-PDIA-0902/0908) an alarm is generated and the DCS operator can start the regeneration cycle which is partially automated.

7.2.17 Polishing filtrate and backflush (PID 520-11)

The level in filtrate tank 520-LICSA-1001 is controlled with the flow to 510-TK-060. In order to have 520-TK-065 act as a buffer tank this control is slow. The level in this tank is kept high during normal operation. When the filter regeneration sequence starts, the level in the tank will decrease. The capacity of this system is sized for the crystallization unit running at 100% capacity, one filter being regenerated, and one in operation. It is not possible to regenerate both filters at the same time whilst operating at 100% capacity. The filtrate in 520-TK-065 can be diluted with process water. The flow of process water is controlled by 520-FIC-1001. During normal operation 520-FCV-1001 is closed. Filter backflush tank 520-TK-070 is used during filter regeneration. The tank is provided with agitator 520-AG-070 which runs continuously. The filter hold-up and the amount of water for sluicing and backwashing is more than the capacity fo 520-TK-070. Therefore 520-PP-070/071 is started automatically during filter regeneration cycle.


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7.2.18 Condensate (PID 520-12)

Condensate is collected in condensate tank 520-TK-045. The sources for condensate are: – Start-up heaters 510-HX-060 and 520-HX-065 – Hot process water heater 520-HX-091 – Second stage vent condenser 520-HX-020 – Anhydrous reactor heater 520-HX-010, via condensate vessel 520-TK-010 – Fuel oil heater 900-HX-160 Most of this condensate is hot and flashes in this tank. The pressure is kept slightly above atmospheric by 520-PIC-1101, which allows venting to atmosphere if required, and prevents air intake from atmosphere. The majority of the condensate is pumped to boiler feed water tank 900-TK-040. A small amount is pumped to thermo compressor desuperheater 520-DS-010. The level in 520-TK-045 is controlled by 520-LICSA-1101, which directs the surplus condensate to hot process water tank 520-TK-091.

7.2.19 Precoat and filter aid (PID 520-13)

The precoat tank 520-TK-080 is used during regeneration of a filter. After regeneration the tank is refilled with diatomaceous earth and process liquor. The filter aid tank is in use continuously to which diatomaceous earth and process liquor are added periodically.

7.2.20 Hot process water (PID 520-14)

The condensate excess from 520-TK-045 is collected in hot process water tank 520-TK-091. A fixed amount of process water (20 m3/h) is added from 510-HX-015, which is preheated with scrubber liquor. During normal operation approx. 29 m3/h of hot process water is required. The amount of condensate supplied to 520-TK-091 is approx. 3 m3/h. The required additional amount of process water is supplied on level control (520-LICA-1301). If for some reason too small amount of process water is used, the hot process water tank overflows and is collected in sump pit 510-SU-100. This can be pumped to 510-DE-050 (and the amount of water added to the settler can be subtracted from the amount added via 510-FCV-0301). The temperature of the hot process water is controlled by temperature controller 520-TIC-1301 and safe-guarded with 520-TISA-1302.


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The hot process water pressure is controlled by 520-PICA-1301. Hot water is transported via a header. The (discontinuous) users are connected to the header with short connecting lines to prevent a lot of cold water being forwarded from stagnant lines.

7.2.21 Setting list


510-DICA-0001 kg/m3 1530 H 1600

L 1400

510-EIA-0001 kW 75 H 105

510-EIA-0002/0003 kW 15 H 18

510-EIA-0004/0005 kW 11 H 14

510-EIA-0008 kW 130 H 200

510-EICSA-0201/0204 kW 50 H 63 HH 70

510-ES-0202/0205 Local control

510-EISA-I-0301 kW TBD H TBD

HH TBD

HHTBD

510-FICA-0001 m3/h 140 L 50

H 200

510-FIA-0002 m3/h 150 L 80

H TBD

510-FICQA-0003 m3/h 22 L 90% of normal

510-FIA-0004 l/min 1 L 0.5

510-FA-0005..0010 l/min 1

510-FIC-0011..0016 l/h 30

510-FI-0017 m3/h 22

510-FI-0018 m3/h 22

510-FICA-0101 m3/h 160 L 100

510-FI-0102 m3/h 10

510-FIC-0103/0104 l/h 30

510-FICA-0201/0202 m3/h 3.5 L 1

510-FI-0203/0204 (PW) l/h 8

510-FICA-0301 m3/h 4 L 90% of normal

510-HIC-0301/02 RPM TBD TBD TBD

510-KIS-0001 min; n/h 1; 1

510-KIS-0002 min; n/h 1; 4


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510-KIS-0201/0202 min; n/h 1; 4

510-LICSA-0001 % 60 L 35

H 85

HH 90

HH 90

510-LICSA-0002 % 50 LL TBD

L 35

H 85

LL TBD

510-LI-0003 % TBD

510-LICSA-0101 % 50 L 35

H 80

HH 90

HH 90

510-LI-0201/0202

TBD TBD


510-LI-0301 (sludge level) m 2

(corresponds with 1

m clear liquor;3 to 4

discs visible)

510-LICSA-0401 % 80 L 5

H 95

L 5

510-PIA-0001 barg -0.07 L -0.2

H 0.05

510-PI-0002 barg

510-PDIA-0003 mm wc 5) H TBD

510-PI-0201/0202 barg TBD

510-PI-0401 barg 2

510-TICA-0001 °C 97 L 90

H 100

510-TIA-0002 °C 97 L 90

H 100

510-TI-0003 °C 85

510-TI-0004 °C 35

510-TI-0101 °C 93

510-TISA-0201/0202 °C 55 H 60 HH 65

510-TI-0203/0204 °C 55

510-TI-0401 °C 90

510-TI-0402 °C 90


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510-XISA-0201/0202 mm/s 6 H 9 HH 14

Guar dosing g/ton solids 80

Capacity 510-MP-072/073

(0.3% guar solution)

m3/h 0.1

520-DIA-0001 kg/m3 1500 L 1400

H 1600

520-DICA-0002 kg/m3 1500 L 1400

H 1600

520-DI-0101 kg/m3 1500

520-EIA-0001 kW 170 H 200

520-EIA-0002/0003 kW 27 H 36

520-EIA-0101 kW 75 H 105

520-EIA-0102/0103 kW 11 H 14

520-EICSA-0301/0304 kW 50 H 63 HH 70

520-ES-0302/0305 Local control

520-EIA-0307 kW TBD H TBD

520-EIA-0501 kW TBD L TBD

H TBD

520-EISA-I-0701 kW TBD H TBD

HH TBD

HH TBD

520-EIA-I-1201 kW TBD TBD TBD

520-EIA-I-1203 kW TBD TBD TBD

520-FICA-0001 m3/h 150 L 50

520-FIA-0002 l/min 2 L 1

520-FIA-0003/0004 l/min 1

520-FI-0011 m3/h 64

520-FIA-0101 m3/h 140 L 70

520-FI-0102/0103 l/min 10

520-FI-0104..0106 l/min 1 L 0.5

520-FIC-0107..0110 l/h 30

520-FICA-0201 m3/h 160 L 100

520-FI-0202 m3/h 10

520-FIC-0203/0204 l/h 30

520-FICA-0301/0302 m3/h 3.5 L 1

520-FI-0303/0304 (PW) l/h 8


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520-FIQ-0401 ton/h 7.5

520-FIA-0402 kg/h 120 30

520-FIC-0601 m3/h NNF

520-FI-0605 m3/h 93

520-FICA-0701 m3/h 8.2 L 90% of normal

520-FICA-0901/02 m3/h 104 L 80% of normal

H 120% of normal

520-FIC-1001 m3/h NNF

520-FI-1101 m3/h 16

520-FIA-1201 m3/h 2 (Check) L 80% of normal

H 120% of normal

-



Guar dosing: guar

concentration in deaerator

liquor flow rate

mg/l

5

Capacity 510-MP-074/075

(0.3% guar solution)

m3/h 0.35

520-KIS-0101 min; n/h 1; 0.25

520-KIS-0102 min; n/h 0.5; 0.25

520-KIS-0103 min; n/h 0.5; 0.25

520-KIS-0301/0302 min; n/h 1; 4

520-LICSA-0001 % 60 L 35

H 85

HH 90

HH 90

520-LICA-0002 % 60 L 35

H 85

520-LI-0003

520-LICSA-0101 % 60 L 35

H 85

HH 90

HH 90


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520-LICSA-0201 % 50 L 35

H 80

HH 90

HH 90

520-LI-0301/0302

TBD TBD


520-LISA-0501 % Variable LL 20

L 23

H 95

LL 20

520-LA-0502 % H 100 (tank starts

overflowing)

520-LICSA-0601 % 1) 64 L 47

H 77

L 47

520-LI-0701 (sludge level) m 2

(corresponds with 1

m clear liquor;3 to 4

discs visible)

520-LICSA-0802 % 1) 28 2)

85 3)

L L14

L 20

H 95

LL 14

520-LICSA-1001 % 28 3)

85 2)

L 20

LL 24

HH 95

LL 24

H 35

520-LISA-1002 % - (L 24)

H 95

L 24

520-LICSA-1101 % 4) 80 LL 0

L 15

H 95

LL 0

520-LISA-1201 % 85 L 30

HH 95

H 90

520-LISA-1202 % 85 L 30

HH 95

H 85

520-LICSA-1301 % 4) 60 L 9

L 15

H 77

L 9


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520-PIA-0001 barg 1 H 1.5

HH 1.8

520-PI-0002 barg 1.2

520-PDIA-0003 mbar 300 H 400

520-PICA-0101 barg -0.16 L -0.25

H -0.05

520-PDIA-0102 mbar 2.5 H 20

520-PI-0103 mbarg

520-PI-0104/0106 mbarg -160

520-PI-0105/0107 barg 0

520-PI-0301/0302 barg TBD

520-PICA-0401 barg 14.5 ?? L 14 ??

520-PI-0402 barg -0.16

520-PI-0403 barg 1.2

520-PDIA-0902/0908 bar 0.3 (clean; check)

2.0 (end of cycle)

H 2.5

520-PI-0905 barg 4

520-PIC-1101 barg 0.15

520-PI-1102 barg 0.15

520-PICA-1301 barg 4.5 L 3

520-QIA-1101 µS/cm 20 40 -

520-SSA-0301 TBD TBD

520-TICA-0001 °C 120 L 110

H 130

520-TIA-0002 °C 120 L TBD

H TBD

520-TI-0003 °C 121

520-TI-0004 °C 124

520-TDIA-0005 °C 0.7 H 1.0

520-TDIA-0006 °C 3 H 5

520-TIA-0101 °C 97 H 100

L 90

520-TI-0102 °C 37

520-TIC-0103 °C 55

520-TI-0201 °C 93


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520-TISA-0301/0302 °C 55 H 60 HH 65

520-TI-0303/0304 °C 55

520-TI-0401 °C 143

520-TICA-0402 °C 125 H 135

520-TI-0501 °C 98

520-TIA-0601 °C 99 H 102

520-TI-0901/02 °C 96

520-TI-1001 °C Ambient to 96

520-TI-1002 °C 80 - 96

520-TI-1003 °C 96

520-TICA-1301 °C 90 L 85

520-TISA-1302 °C H 95 H 95

520-XISA-0301/0302 mm/s 6 H 9 HH 14

Timer 520-XSV-1201/1202 s 520-XSV-1201

open and 520-XSV-

1202 closed: 15

520-XSV-1201

closed and 520-

XSV-1202 open: 5

1) Presented as percentage of liquid height, measured from bottom of cone

2) At start of filter regeneration cycle

3) At end of filter regeneration cycle

4) Presented as percentage of liquid height, measured from bottom head tangent line

5) mm wc is mm H2O at 4°C


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7.3 Logic functions

In this section the logic functions describing automatic actions of valves are described. The guar make-up sequence is described in section 7.7.2 and the filter regeneration sequence is described in section 7.7.11. Logical functions that act on equipment are for example: – Start conditions and running conditions – Process switches – Safety switches (dry run protection on pumps, speed alarm on conveyors) Thermal overload is provided on all electric motors. The thermal overload shuts off the motor directly (hardwired from MCC). In the table below logic functions acting on equipment are presented.

Type Equipment/Action Start Stop Signal

Start/

Running

condition

Switch/

Interlock

400-GA-060 Manual on

DCS

(check)

and

automatic

Manual on

DCS (check)

and

automatic

– High level on 510-LICSA-

0001

– Vent fan 510-FN-010 is not

running

– If Pump 510-PP-010/011 is

not running

– Agitator 510-AG-010 is not

running

Direct

calcined

feed to

dump tank


hand

Locally by

hand and

automatic

– Low power on 510-EISA-

0002/0003 (after times;

broken belt detection)

- Stop


hand

Locally by

hand

- - -


hand

Locally by

hand and

automatic

– Low level of 510-LICSA-

0002

Stop


hand

Locally by

hand

– High level is activated on

510-LICSA-0101

- Stop

510-FN-010 Locally by

hand

Locally by

hand

- - -


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Start/

Running

condition

Switch/

Interlock

510-CF-035/036 Locally by

hand

Locally by

hand and

automatic

– Hydraulic pump (510-EM-

0202/0205 and 510-EM-

0208/0209) is running

– Air cooler fan (510-EM-


– Low level of 510-LSA-

0203/0204 activated

– High temperature on 510-

TISA-0201/0202

– 510-XISA-0201/0202

X

X

Stop

Stop

Stop


hand

Locally by

hand

– - - -


hand

Locally by

hand

– HH torque on 510-EISA-I-

0301

Lift rake

(local

control)


hand

Locally by

hand and

automatic

– LL level of 510-LICSA-0401

activated

Stop

510-AG-070 Automatic Automatic LL level of 510-LI-001 Stop

510-MP-070 to

075

Locally by

hand

Locally by

hand and

automatic

LL level of 510-LI-002 Stop

510-PP-070/071 Automatic Automatic LL level of 510-LI-001 Stop

–


hand

Locally by

hand and

automatic

– High pressure of 520-PISA-

0001 is activated


0001

– High power on 520-EICSA-

0101/0102 ???


0101

– Agitator 520-AG-020 is not

running

– Low level 520-LISA-0501 is

activated

Stop


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Start/

Running

condition

Switch/

Interlock


hand

Locally by

hand and

automatic


0201

Stop

520-CF-035/036 Locally by

hand

Locally by

hand and

automatic

– Hydraulic pump (520-EM-

0302/0305 and 520-EM-


– Air cooler fan (520-EM-


– Low level of 520-LSA-

0303/0304 activated

– High temperature on 520-

TISA-0301/0302

– 520-XISA-0301/0302

X

X

Stop

Stop

Stop


hand

Locally by

hand and

automatic

– Emergency switch 520-EM-

0307 is activated


activated

Stop


hand

Locally by

hand

- - -


hand

Locally by

hand and

automatic

– LL level of 520-LICSA-0601 Stop


hand

Locally by

hand and

automatic

– High torque on 520-EISA-I-

0701

- Lift rake

(local

control)


hand

Locally by

hand

- - -

520-PP-095 Automatic Automatic – 520-LS-0702 Low

– 520-LS-0702 High

Stop

Start


hand

Locally by

hand and

automatic

- - -


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Start/

Running

condition

Switch/

Interlock

520-PP-060/061 Locally

and on

DCS by

hand and

automatic

Locally and

on DCS by

hand and

automatic

– Running pump stops

(failure, stop switch)

– At least one of valves 520-

XSV-0904 and 520-

XSV0918 has to be open

– 520-LICSA-0802 LL level

X

Start spare

pump

Stop

520-PP-100 Automatic Automatic – 520-LS-0803 Low

– 520-LS-0803 High

Stop

Start


hand

Locally by

hand and

automatic

– 520-LICSA-1001 LL level Stop


and on

DCS by

hand and

automatic

Locally and

on DCS by

hand and

automatic

– Tank level at 520-LISA-1002

L


LL

Start

Stop


and on

DCS by

hand and

automatic

Locally and

on DCS by

hand and

automatic

– Running pump stops

(failure, stop switch)


LL

Start spare

pump

Stop

520-PP-080 Locally by

hand

Locally by

hand and

automatic

- - -


hand

Locally by

hand and

automatic

- - -

520-PP-085 Locally by

hand

Locally by

hand and

automatic

- - -


hand

Locally by

hand and

automatic

- - -


hand

Locally by

hand and

automatic

– Tank level at 520-LICSA-

1301 LL

Stop


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In the table below automatic actions of valves are presented. Valve Action Cause

510-FCV-0001 Close – high level is activated on 510-LICSA-0001

510-KIS-0001/0002 Close – high level is activated on 510-LICSA-0001

510-ECV-

0201/0204

Close – High power on 510-EICSA-0201/0204 is activated

– 510-CF-035/036 is not running

520-DCV-0002 Close – If feed pump 520-PP-005/006 is not running

520-PCV-0401 Close – 520-PP-010 is not running

520-XSV-

0001/0002

Open – 520-PP-005/006 is running

Close – 520-PP-005/006 is not running

Close – 520-LICSA-0001 high level is activated

520-KIS-

0101/0102/0103

Close – High level on 520-LICSA-0101

520-XSV-

0101/0102

Open – 520-PP-022/023 is running

Close – 520-PP-022/023 is not running

520-ECV-

0301/0304

Close – High power on 520-EICSA-0301/0304 is activated

– 520-CF-035/036 is not running

– Conveyor belt 520-CV-040 is not running

520-LCV-0601 Close – Pump 200-PP-005/006 stop

– 520-LSA-0502 HH level activated

520-XSV-1001 Open – One of pumps 520-PP-070/071 is running

520-XSV-1201 Open

Close

– After certain time

– After certain time and 520-XSV1202 is open

520-XSV-1202 Open

Close

– After certain time

– After certain time and 520-XSV1201 is open

520-TCV-1301 Close – High temperature 520-TISA-1302 activated


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7.4 Start-up and shutdown of the crystallization unit

7.4.1 Fill system and start rotating equipment

The start up of the crystallization section is mainly a manual operation. For this procedure, the following assumptions are made:

• Crystallizers, elutriators tanks etc. are empty • Utilities and auxiliaries are available and ready for use. The following utilities and

auxiliaries are required for this process section: • Process water • 15 bar steam supply • 3 bar steam supply • Condensate return (see section 7.7.8) • Hot process water (see section 7.7.9) • Purge water • Guar solution (see section 7.7.2) • Cooling liquor from washery section • Tailing tank 900-TK-250 and paddock slurry tank 900-TK-

260 • • Instrument air • Electrical power

• Instruments are working and calibrated

1 Filling of settler 510-TK-050 and settler overflow tank 510-TK-060. o Bottom valves have to be closed. o Use water supply via 510-FCV-0301 (max. flow is approx. 30 m3/h) and hoses if

needed. Fill the settler until it overflows to the settler overflow tank 510-TK-060. o Continue filling the settler overflow tank until a level of 50% (this corresponds to

40% reading on 510-LI-0401).If the tank is filled up sufficiently, it can be used for filling crystallizer or elutriator. In that case pump 510-PP-060/061 has to be taken into operation:

2 Start first stage settler overflow pump 510-PP-060/061. o Check valve configuration of 510-HX-060/061 and destination lines (open supply

and return valves on heater, throttle heater bypass valve) o When not in use, the pumps should have the suction and discharge valves closed

and the drain valve open. o To start a pump, first ensure the seal purge water is flowing at 1 l/m. o Close the drain valve and open the suction valve. o Start pump and then open the discharge valve. o Only one pump should operate at a time.


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o Check valve configuration of 510-PP-060/061 and destination lines (circulate via crystallizer and elutriator, keep transfer to 900-TK-250 closed).

3 Filling first stage crystallizer 510-EV-010. o Bottom valves have to be closed. o Venting during filling goes via scrubber 510-DC-015 (fan not running) o Use water supply from settler overflow tank with pump 510-PP-060/061 o Filling can also be supplemented using wall wash water supply. o Fill the crystallizer with water until the level is between the lower and upper level

sight glasses, located on the cylindrical wall of the crystallzer. (The level indicator is calibrated for process slurry so the level indication will not be correct on water).

4 Filling of first stage scrubber 510-DC-015. o Bottom valves have to be closed o Venting during filling goes via fan 510-FN-010 (not running). For filling use process water supply via 510-FCV-003. Fill the scrubber with water until the level is midway up the level gauge glass. (The level indicator is calibrated for liquor so the operating density differs slightly from water density)

5 Filling first stage elutriator 510-SP-025 o Bottom valves have to be closed. o Use water supply from settler overflow tank with pump 510-PP-060/061. Fill the

elutriator with water until it starts overflowing (visible at first stage deaerator 510-DE-050).

o Set flow control 510-FICA-0101 to automatic at 160 m3/h (design rate). o Adjust flow to bottom through 510-FI-0102 to ~50 m3/h.

6 Start the first stage crystallizer agitator 510-AG-010 o The crystallizer agitator can be started once the vessel is filled to the proper

operating level. o First ensure the seal purge water is flowing at 0.8 l/m. o Then start the agitator.

7 Start hydrator pump 510-PP-010/011 o Hydrator pump can be started once the first stage crystallizer is filled to the

proper operating level. o When not in use, the pumps should have the suction and discharge valves closed

and the drain valve open. o To start a pump, first ensure the seal purge water is flowing at ~1 l/m. o Close the drain valve and open the suction valve o Start pump and then open the discharge valve o Only one pump should operate at a time.

8 Start first stage scrubber pump 510-PP-015/016


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o Scrubber pump can be started once the scrubber is filled to the proper operating level. The pumps are interlocked with low low level of 510-LICSA-0002 so the level indication must be working properly prior to operating the scrubber pumps.

o Ensure the manual recycle valve to the scrubber spray nozzles is open and the level control valve 510-LCV-0002 is closed.

o When not in use, the pumps should have the suction and discharge valves closed and the drain valve open.

o To start a pump, first ensure the seal purge water is flowing at 1 l/m. o Close the drain valve and open the suction valve. o Start pump and then open the discharge valve. o Only one pump should operate at a time. o The scrubber level control can then be put in automatic.

9 Start first stage scrubber fan 510-FN-010 o Before starting the fan, water should be added to the overflow lutes of both the

first stage crystallizer and the first stage scrubber. This is done by attaching a hose to the drain valves on the lute and then adding water until water comes out the overflow. The water in the lutes prevents air from being drawn through the overflow lines.

o The fan should be started in manual mode at the minimum speed. 10 Start first stage slurry pump 510-PP-020/021


o To start a pump, first ensure the seal purge water is flowing at 1 l/m. o Close the drain valve and open the suction valve. o Start pump and then open the discharge valve. o Only one pump should operate at a time. o Set pump speed manually through 510-LICSA-0001 to show ~40 m3/h flow rate

on 510-FIA-0002. o Set feed to crystallizer through 510-FICA-0001 to ~70 m3/h (~half of design rate). o Put first stage crystallizer level control 510-LICSA-0001 to automatic and select a

level setpoint that maintains the level between the upper and lower level sight glasses on the crystallizer wall.

o If the level in the first stage settler overflow tank is low, additional water can be added to the circuit by starting the process water addition to the first stage scrubber through 510-FICQA-0003 (make sure bypass over 510-FCV-0003 is closed).

o If the level in the first stage settler overflow tank is high, the level controller 510-LICSA-0401 can be put in automatic and the transfer to 900-TK-250 can be opened (ensure bypass valve over 510-LCV-0401 is closed).

11 Start first stage centrifuge 510-CF-035/036 o First ensure that the seal purge water is flowing at ~8 l/h.


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o Ensure the oil level is adequate and then start the hydraulic pump motor o Verify that the oil cooler fan and oil circulation pump have started (these motors

are wired in the MCC to start and stop with the hydraulic pump motor). o After the hydraulic pump has been running for at least one minute, start the main

rotor motor. o During normal operation, both centrifuges will operate at the same time.

However, during start-up or at reduced rates it is only necessary to operate one centrifuge.

o If desired, water can be fed through the running centrifuge and into the first stage settler deaerator. However, since the first stage elutriator overflows to the same place, it is not necessary to run the first stage centrifuges on water.

o To stop the centrifuge, first stop the main rotor motor. After the centrifuge comes to a complete stop the hydraulic pump motor can be stopped.

12 Start first stage settler rake mechanism

13 Filling of anhydrous reactor 520-EV-010 o Bottom valves have to be closed. o Manual 25 mm vent valve on top of the reactor is opened. o Open 150 mm process water valve located on the recirculation pipe and fill the

anhydrous reactor to a level that is approximately 1 meter above the recirculation inlet nozzle. (The level indicator is calibrated for process slurry so the level indication will not be correct on water). The level can be viewed through the top sight glasses.

14 Start the anhydrous reactor pump 520-PP-010 o The anhydrous reactor pump can be started once the anhydrous reactor is filled

to the proper operating level. The allowable operating level ranges from the center line of the recirculation inlet nozzle (N1) to the top of straight side of the vessel.

o First ensure the seal purge water is flowing at ~2 l/m. o Start the pump

15 Filling of second stage crystallizer 520-EV-020 o Bottom valves have to be closed. o Manual 25 mm vent on line from second stage vent condenser is opened to vent

the second stage crystallizer through the condenser. o Fill the second stage crystallizer through anhydrous slurry transfer lines by

opening 520-LCV-0001A/0001B, along with the block valves in these lines. o Only one transfer line is in use at a time. o Put anhydrous reactor level controller 520-LICSA-0001 in automatic and adjust

the level setpoint.


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o Continue adding process water to the anhydrous reactor while water is transferred to the second stage crystallizer. Fill the second stage crystallizer with water until the level is between the lower and upper level sight glasses, located on the cylindrical wall of the crystallizer. (The level indicator is calibrated for process slurry so the level indication will not be correct on water).

16 Start second stage crystallizer agitator 520-AG-020 o The crystallizer agitator can be started once the vessel is filled to the proper

operating level. o First ensure the seal purge water is flowing at 0.8 l/m. o Then start the agitator.

17 Start the second stage slurry pump 520-PP-020/021 o When not in use, the pumps should have the suction and discharge valves closed

and the drain valve open. o To start a pump, first ensure the seal purge water is flowing at 1 l/m. o Close the drain valve and open the suction valve. o Start pump and then open the discharge valve. o Only one pump should operate at a time.

18 Filling of second stage elutriator 520-SP-025 o Bottom valves have to be closed. o Transfer water from the second stage crystallizer using one of the second stage

slurry pumps 520-PP-020/021. The second stage crystallizer level setpoint (520-LICSA-0101) can be adjusted to a point which maintains the crystallizer level between the level sight glasses while water is transferred from the anhydrous reactor.

19 Filling of second stage settler 520-TK-050 and polishing filter feed tank 520-TK-060 o Bottom valves have to be closed o Filling can be accomplished by continuing to supply process water to the

anhydrous reactor and allowing the water to flow through the second stage crystallizer and second stage elutriator. The elutriator will overflow to the second stage settler deaerator and then to the second stage settler and finally to the polishing filter feed tank. Continue filling the polishing filter feed tank until the level is 50%, which is ~40% level indication of 520-LICSA-0802.

20 Start second stage settler rake mechanism 520-TM-050 21 Start polishing filter feed pump 520-PP-060/061 and filling polishing filter

o Ensure filter is ready: check manual valves are set correctly, open feed connection 520-XSV-0904/0918, open overflow valve 520-XSV-0906/0921 and all other valves closed

o This pump has automatic changeover in case the running pump fails: when not in use, the pump suction and discharge valves are open and the drains closed. A check valve prevents back flow via the standby pump.

o To start a pump, first ensure the seal purge water is flowing at ~1 l/m.


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o Close the drain valve and open the suction valve o Ensure valve on tank is open o Start pump and then open the discharge valve o Only one pump should operate at a time. o Put polishing filter feed tank level control 520-LICSA-0802 in automatic at ~40%. o When filter is full, open 520-XSV-0913/0931 and close 520-XSV-0906/0921

22 Filling of the filtrate tank 520-TK-065 o Bottom valves have to be closed. o Filling can be accomplished either by adding process water through 520-FIC-

1001 or by pumping water from the polishing filter feed tank through the polishing filters 520-FL-060/061 using the filter feed pumps 520-PP-060/061. Continue filling the filtrate tank until the level is 50%, which is ~40% level indication of 520-LICSA-1001.

23 Start filtrate pump 520-PP-065/066 o When not in use, the pumps should have the suction and discharge valves closed

and the drain valve open. o To start a pump, first ensure the seal purge water is flowing at ~1 l/m. o Close the drain valve and open the suction valve o Ensure valve on tank is open o Start pump and then open the discharge valve o Only one pump should operate at a time. o Put filtrate tank level control 520-LICSA-1001 in automatic at ~40% (ensure

bypass over 520-LCV-1001 is closed). 24 Start filtrate feed to second stage elutriator via 520-FCV-0201

o Bottom valves have to be closed. o Open manual block valves in transfer line o Set flow control 520-FICA-0201 to automatic at 160 m3/h (design rate). o Adjust flow to bottom through 520-FI-0202 to ~50 m3/h.

25 Start second stage centrifuge 520-CF-035/036 o First ensure that the seal purge water is flowing at ~8 l/h. o Ensure the oil level is adequate and then start the hydraulic pump motor o Verify that the oil cooler fan and oil circulation pump have started (these motors

are wired in the MCC to start and stop with the hydraulic pump motor). o After the hydraulic pump has been running for at least three minutes, start the

main rotor motor. o During normal operation, both centrifuges will operate at the same time.


26 Start second stage belt conveyor 520-CV-040 o Inspect belt conveyor to ensure there are no hazards that result from starting. o Start belt conveyor with local on/off switch


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o Belt conveyor motor is interlocked with second stage centrifuge feed valves 520-ECV-0301/0304 such that valves can only be opened if motor is running.

27 Filling of second stage centrate tank 520-TK-040 o Water can be fed through the running centrifuge and into the centrate tank o First ensure second stage centrifuge is running o Open the block valve in the centrifuge feed line o Set 520-EICSA-0301/0304 to manual and gradually open 520-ECV-0301/0303

(control valves are interlocked to the respective centrifuge rotor motors such that valves will only open if the motor is running and will close if the motor is stopped).

28 Start second stage centrate pump 520-PP-040/041 o Check dust system of 600 section can receive liquor o When not in use, the pumps should have the suction and discharge valves closed

and the drain valve open. o To start a pump, first ensure the seal purge water is flowing at ~1 l/m. o Close the drain valve and open the suction valve o Ensure valve on tank is open o Start pump and then open the discharge valve o Only one pump should operate at a time o Set 520-LICSA-0601 to 40% in automatic. 520-LCV-0601 will open flow to 520-

TK-005. 29 Filling of second stage crystallization feed tank 520-TK-005

o Bottom valves have to be closed. o Filling can be accomplished either by pumping water from the filtrate tank or by

running the second stage centrifuge 520-CF-035/036 and opening the centrifuge feed valve 520-ECV-0301/0304 from the second stage elutriator and then pumping out of the second stage centrate tank 520-TK-040 with second stage centrate pump 520-PP-040/041.

o Fill the tank to 50% level (this corresponds to 30% level on 520-LISA-0501 when on water).

30 Start second stage crystallization feed pump 520-PP-005/006 o When not in use, the pumps should have the suction and discharge valves closed

and the drain valve open. o To start a pump, first ensure the seal purge water is flowing at ~1 l/m. o Close the drain valve and open the suction valve o Start pump (discharge valve will automatically open when pump is started). o Only one pump should operate at a time o Set flow setpoint of 520-FICA-0001 to ~2500 l/m. o Stop adding process water to anhydrous reactor through 150mm water

connection once operating levels in all second stage vessels is adequate. 31 Start second stage crystallization feed tank agitator. 32 Start second stage vacuum pump 520-PP-022/023


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o Close vent valve on condenser vent line. o Close 250 mm suction valve to thermo compresser and ensure thermo

compressor bypass valves are closed. o Fill seal leg on condenser drain line and second stage crystallizer overflow with

water through hose connections. o Ensure vacuum pump seal purge water manual valve is open. o Start vacuum pump and adjust seal water flow to ~8 l/m. o Put pressure control 520-PCV-0101 on automatic. o Open liquor supply to second stage condenser 520-HX-020 and put temperature

control 520-TIC-0103 on automatic. 33 Preheat crystallization circuits

o Condensate tank 520-TK-045 is already in use for hot water system o Once either first stage or second stage crystallization circuits are flowing with

water or brine, the start-up heaters can be used to preheat the system. o Open valves in and out of first stage / second stage mother liquor heater 510-HX-

060 / 520-HX-065 and throttle bypass valve in a way that still sufficient water is circulating.

o Open block valve on 3 bar steam header to mother liquor heater. o Put condensate level control 520-LICSA-1101 in automatic (ensure bypass over

520-LCV-1101 is closed). o Continue heating the first stage crystallization circuit with steam until it is heated

to ~80° C and then close steam valve to mother liquor heater. Open manual bypass valve fully, flush and close process supply and return lines.

o Heat the second stage crystallization circuit with steam until it is heated to ~90° C and then close steam valve to mother liquor heater. The transfer pumps and centrifuges should then be stopped until feed slurry is available from the second stage crystallization feed tank.

34 Standby second stage crystallization circuit The second stage crystallization circuit is put in standby mode until the first stage crystallization circuit is in production mode and the second stage crystallization feed tank contains slurry. o Stop the second stage crystallization feed pump 520-PP-005/006, flush both

sides of the automated on/off valve at the discharge of the pump with hot water for several minutes (this valve closes automatically when the pump stops), close the valve at the feed tank and open the drain valve.

o Stop transfer from anhydrous reactor to second stage crystallizer by closing valve at reactor, flushing line with hot water for several minutes, closing valve at crystallizer, stop flush water and open drain valve of “S2” connection. It may be necessary to set 520-LISCA-0001 to manual to keep the control valve in the line open while flushing.


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o Stop second stage slurry pump 520-PP-020/021, close the valve at the crystallizer, flush the line with water for several minutes, stop the flush water, close the discharge valve and open the drain valve.

o Stop the flow to the second stage centrifuge by closing the valve at the elutriator and flushing the line with water for several minutes. It may be necessary to set 520-EICSA-0301/0304 to manual to keep the control valve open while flushing.

o Stop the second stage centrifuges. o Stop the second stage belt conveyor 520-CV-040.

At this point, the anhydrous reactor and second stage crystallizer vessels are isolated and the following function on:

• Anhydrous reactor pump 520-PP-010 running • Crystallizer agitator 520-AG-020 running • Vacuum pump 520-PP-022/023 running with automatic pressure control enabled • Cooling liquor flow through condenser with automatic temperature control enabled • Filtrate flow to second stage elutriator • Centrate pump 520-PP-040/041 running • Second stage settler rake mechanism running • Polishing filter feed pump 520-PP-060/061 running with automatic level control on

polishing filter feed tank 520-TK-060 • Filtrate pump 520-PP-065/066 running • Condensate pump 520-PP 045/046 running

7.4.2 Start first stage production

Now first stage crystallization circuit is operating with following functions: • Crystallizer agitator 510-AG-010 running • Hydrator pump 510-PP-010/011 running • Scrubber fan 510-FN-010 running • Scrubber pump 510-PP-015/015 running • First stage slurry pump 510-PP-020/021 running with crystallizer level control 510-

LICSA-0001 in automatic. • Liquor circulation to elutriator 510-SP-025 via 510-FCV-0101 at design rate. • Liquor feed to crystallizer via FCV-0001 at ~half of design rate. • Settler overflow pump 510-PP-060/061 running • Feed to centrifuges via 520-LICSA-0101 off • First stage centrifuges 510-CF-035/036 not running • First stage settler rake mechanism 510-TM-050 running.


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1 Open water supply to scrubber and set flow rate via 510-FIC-0003 to ~5 m3/h (25% of design rate) with recirculation valve throttled to obtain ~20 m3/h flow rate on 510-FI-0017 (ensure bypass over 510-FCV-0003 is closed).

2 Open manual valves in process water supply for wall wash and enable wash timers 510-KIS-0001/0002.

3 Put scrubber fan speed control in automatic 510-TICA-0001. 4 Start adding calcined feed from calciner unit The hot (400° C) calcined feed will start increasing the temperature of the first stage crystallization circuit as well as the liquor concentration and density. As the crystallizer temperature approaches the operating setpoint of 97° C, the vent fan will automatically increase speed via temperature controller 510-TICA-0001. 5 As the density increases in the crystallizer, the level setpoint of 510-LICSA-0001

must be increased to maintain the actual level between the upper and lower level sight glasses in the vessel cylindrical wall.

6 Open process water supply to deaerator and set flow rate via 510-FCV-0301 to ~2 m3/h (50% of normal rate) (ensure bypass over 510-FCV-0301 is closed).

7 Start guar pump 510-MP-072/073 and check flow rate. 8 Open manual valves in liquor transfer from settler overflow tank 510-TK-060 to

tailing tank. Put level control 510-LICA-0401 on automatic (ensure bypass over 510-LCV-0401 is closed).

When the crystallizer density increases above 1.30, monohydrate crystals will begin to be produced. These crystals will then start to be transferred to the elutriator. The elutriator level indicator 510-LICSA-0101 would be negative when the liquor is below saturation and give a positive reading when crystals begin to accumulate. As the level indication increases above 10%, one of the centrifuges should be started. 9 Check crystal size and shape. If too many fine crystals are formed, then a portion of

the slurry will be discharged via the elutriator overflow. 10 Start first stage centrifuge 510-CF-035/036

o First ensure that the seal purge water is flowing at ~8 l/h. o Ensure the oil level is adequate and then start the hydraulic pump motor o Verify that the oil cooler fan and oil circulation pump have started (these motors





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11 Open hot water flow to centrifuge via 510-FCV-0201/0202. 12 Start feeding slurry from elutriator to centrifuge via 510-ECV-0201/0204. 13 Ensure that second stage feed tank agitator 520-AG-005 is running. 14 When the first centrifuge is operating near full capacity, start the second centrifuge

operation. 15 Set elutriator level control 510-LICSA-0101 to automatic at ~50% 16 Monitor sludge level in settler. It will take certain time until a sludge layer is

developed. 17 Set valve settings of discharge line of 510-PP-050/051 for recycling to deaerator.

Open suction valve and discharge valve. Start pump 510-PP-050/051. Set the speed according setting list (ratio of frequency and flow rate to be determined during precommissiong/start-up).

18 When a sludge layer of 2 m is formed (510-LI-0301 until disk 4 visible), start discharging sludge to slurry tank 900-TK-260. Keep recycle to deaerator running.

19 When the first stage crystallizer density approaches the design operating point of 1.53, increase the brine feed flow via 510-FICA-0001 to ~140 m3/h and then put the crystallizer density control 510-DICA-0001 to automatic.

7.4.3 Start second stage production

The second stage crystallization feed tank 520-TK-005 will receive the centrifuge cake from the first stage centrifuges 510-CF-035/036. This tank does not have density indication so the initial indication of solids concentration will be the level increase. The initial tank level should be ~50% and when this increases to ~80%, the feed to the anhydrous reactor should be started. This should take 3 to 4 hours with the first stage crystallizer operating at design rate. The anhydrous reactor must be heated to the design operating temperature (120° C) prior to initiating feed. Raising the temperature of the anhydrous reactor using 15 bar steam through the thermo compressor should occur at a rate of ~0.5° C/min. To heat from 90° C to 120° C should take ~1 hour. 1 Open motive steam to thermo compressor 520-SJ-010

ο First ensure anhydrous reactor heater 510-HX-010 has vent valves completely open.

o Open 15 bar steam valve and ensure steam pressure controller 520-PICA-0401 is in automatic.

o Ensure condensate vessel level control 520-TK-010 is working in automatic. o Ensure condensate pump 520-PP-045/046 is running and condensate tank 520-

TK-045 level control via 520-LICSA-1101 is in automatic (and bypass over 520-LCV-1101 is closed).


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o Gradually close vent valves on heater to reduce the amount of steam vent to a small continuous amount.

2 Open water to thermo compressor desuperheater 520-DS-010 and put control valve via 520-TICA-0402 in automatic.

3 When the anhydrous reactor temperature rises above 100° C, steam will vent through the manual vent valve at the top. Gradually close this vent valve in a similar manner to the heater vent valves, leaving a small continuous vent to avoid accumulating non-condensable gasses.

4 When the operating temperature reaches 120° C, start second stage crystallization feed pump 520-PP-005/006 o When not in use, the pumps should have the suction and discharge valves closed

and the drain valve open. o To start a pump, first ensure the seal purge water is flowing at ~1 l/m. o Close the drain valve and open the suction valve o Start pump (discharge valve will automatically open when pump is started). o Only one pump should operate at a time o Set flow setpoint of 520-FICA-0001 to ~150 m3/h. o Adjust flow setpoint as necessary to maintain level in 520-TK-005.

5 Start automatic density control of feed to anhydrous reactor by opening filtrate flow to suction of pump 520-PP-005/006 and putting 520-DICA-0002 in automatic at the design setpoint of 1.50.

6 Start transferring to the second stage crystallizer via 520-LICSA-0001. First open the manual valve at the anhydrous reactor, then open the valve at the second stage crystallizer and finally open 520-LCV-0001 and set to automatic control at the current operating level indication. As the density in the anhydrous reactor increases, the actual level will decrease for the same level indication. The desired operating level is ~1 meter above the recirculation inlet nozzle. The level setpoint should be adjusted to obtain this. NB: the density of water is not sufficient to prevent boiling in the transfer line.

7 Start the second stage slurry pump 520-PP-020/021 o When not in use, the pumps should have the suction and discharge valves closed

and the drain valve open. o To start a pump, first ensure the seal purge water is flowing at 1 l/m. o Close the drain valve and open the suction valve. o Start pump and then open the discharge valve. o Only one pump should operate at a time. o Set the second stage crystallizer level control 520-LICSA-0101 to automatic.

8 As 120° C slurry is transferred to the second stage crystallizer, the operating temperature will rise to ~97° C, where the crystallizer contents will begin boiling. Usually, the operating pressure in the second stage crystallizer will increase when boiling first occurs until the vacuum system is able to draw out all the air. When the


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proper operating pressure is reestablished after boiling commences, the block valve at the suction of the thermo compressor is opened slowly.

9 The manual valves in the bypass line around the thermo compressor are opened and the control valve via 520-TICA-0001 is put in automatic control at the design operating temperature (120° C).

10 Start the automatic wall wash and demister wash 520-KIS-0101/0102/0103. 11 Ensure fluid bed dryer is on standby 12 Start second stage belt conveyor 520-CV-040 When the crystallizer density increases above 1.30, monohydrate crystals will begin to be produced. These crystals will then start to be transferred to the elutriator. The elutriator level indicator 520-LICSA-0201 would be negative when the liquor is below saturation and give a positive reading when crystals begin to accumulate. As the level indication increases above 10%, one of the centrifuges should be started. 13 Start second stage centrifuge 520-CF-035/036

ο First ensure that the seal purge water is flowing at ~8 l/h. o Ensure the oil level is adequate and then start the hydraulic pump motor o Verify that the oil cooler fan and oil circulation pump have started (these motors




14 Open hot water flow to centrifuge via 520-FCV-0301/0302 (or cold water, to be verified during start-up)

15 Start feeding slurry from elutriator to centrifuge via 520-ECV-0301/0304. 16 Start second stage centrate pump 520-PP-040/041


o To start a pump, first ensure the seal purge water is flowing at ~1 l/m. o Close the drain valve and open the suction valve o Ensure valve on tank is open o Start pump and then open the discharge valve o Only one pump should operate at a time o Set 520-LICSA-0601 to 50% in automatic. 520-LCV-0601 will open flow to 520-

TK-005. 17 When the first centrifuge is operating near full capacity, start the second centrifuge

operation. 18 Set elutriator level control 520-LICSA-0201 to automatic at ~50%


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19 Start guar pump 510-MP-074/-75 and check flow rate. 20 Set 520-FICA-0701 for hot water supply to dearator 520-DE-050 (ensure bypass

over 520-FCV-0701 is closed). 21 Set valve settings of discharge line of 520-PP-050/051 for recycling to deaerator.

Open suction valve and discharge valve. Start pump 520-PP-050/051. Set the speed according setting list (ratio of frequency and flow rate to be determined during commissioning/start-up).

22 Monitor sludge level in settler. It will take certain time until a sludge layer is developed.

23 When a sludge layer of 2 m is formed (520-LI-0701 until disk 4 visible), start discharging sludge to slurry tank 900-TK-260. Keep recycle to deaerator running.

24 The water addition rates to the scrubber and both first stage and second stage deaerators can be set in automatic flow control at setpoints shown in the settings table and then adjusted as required.

7.4.4 Shut-down

Purpose of this procedure is to shut down for a longer period of time or for maintenance. Most of the sodium carbonate solids in the crystallization circuits are removed and recovered and the remaining solids are dissolved.

7.4.4.1 Shut-down first stage crystallization circuit

1 Stop feed from calciner. 2 Continue feeding liquor to first stage crystallizer via 510-FICA-0001 while pumping

slurry to elutriator until most of the crystals are discharged from first stage crystallizer 510-EV-010 (this takes approx. 3 – 4 hours). The density controller 510-DICA-0001 will need to be set in manual so that a set flow rate can be maintained via 510-FICA-0001. This flow rate can be increased as the crystallizer density decreases.

3 Stop first stage slurry pump 510-PP-020/021, close valve at crystallizer, flush slurry transfer line, close discharge valve and open drain valve.

4 Stop hydrator pump 510-PP-010/011, close valve at crystallizer, flush slurry transfer line, close discharge valve and open drain valve.

5 Close settler overflow liquor supply to crystallizer via 510-FCV-0001. 6 Stop fan 510-FN-010 and scrubber pump 510-PP-015/016 and close process water

supply via 510-FCV-0003. 7 Take level control 510-LICSA-0101 on elutriator 510-SP-025 on manual, in order to

discharge all solids. When elutriator is empty of crystals, then close elutriator bottom valves 510-ECV-0201/0204.

8 Flush front-side of centrifuge screen with hot process water until all solids are dissolved.


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9 Stop first stage centrifuge and close hot water supply via 510-FCV-0201/0202. 10 Close process water supply to deaerator via 510-FCV-0301. 11 Stop guar pump 510-MP-072/073 12 Stop first stage settler overflow pump 510-PP-060/061 (close discharge valve, keep

suction valve open for seal purging). 13 Stop first stage settler underflow pump 510-PP-050/051. 14 Ensure all lines are flushed. The unit is now stopped, with following functions in operation:

• Crystallizer agitator 510-AG-010 • Settler rake mechanism 510-TM-050 running • Seal water on instruments and pumps

Whenever possible keep liquor in first stage crystallizer and settler. Proceed with washout procedure as required for the shutdown.

7.4.4.2 Shut-down second stage crystallization circuit

1 Maintain flows through second stage crystallization circuit after first stage circuit has been stopped. Objective is to process the remaining sodium carbonate solids in the circuit. The suspended solids concentration in the feed tank 520-TK-005, the anhydrous reactor 520-EV-010 and the crystallizer 520-EV-020 will gradually be reduced as product is recovered on the second stage centrifuges and centrate is recycled to the feed tank.

2 When the density in the anhydrous reactor has dropped below 1.35, close 15 bar steam supply to thermo compressor 520-SJ-010

3 Prior to stopping pump 520-PP-005/006, flush line (because otherwise 520-XSV-0001/0002 is closed). Stop second stage crystallization feed pump 520-PP-005/006, flush both sides of the automated on/off valve 520-XSV-0001/0002 with hot water for several minutes (this valve closes automatically when the pump stops), close the valve at the feed tank and open the drain valve.

4 Stop filtrate supply from filtrate tank 520-TK-065 to slurry feed line (close 520-DCV-0002).

5 Continue slurry transfer from anhydrous reactor 520-EV-010 to 520-EV-020, by putting 520-LICSA-0001 in manual.

6 When level indicator 520-LICSA-0001 shows ~20% or level is below “N1” nozzle, stop slurry transfer from anhydrous reactor by closing valve at reactor, flushing line with hot water for several minutes, closing valve at crystallizer, stop flush water and open drain valve of “S2” connection.

7 Open DN 150 process water connection to anhydrous reactor and fill to high level (top of vessel straight side) or until density indication 520-DIA-0001 shows <1.30.


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8 Stop second stage slurry pump 520-PP-020/021, close the valve at the crystallizer, flush the line with water for several minutes, stop the flush water, close the discharge valve and open the drain valve.

9 When elutriator is empty of crystals, (having level control 520-LICSA-0201 in manual) close elutriator outlet valves 520-ECV-0301/0304.


11 Stop centrifuge and close hot water supply via 520-FCV-0301/0302. 12 Stop second stage belt conveyor 520-CV-040 13 Close 520-FCV-0701 ( hot process water supply to deaerator 520-DE-050) 14 Stop guar pump 520-MP-074/075 15 Stop settler underflow pump 520-PP-050/051

The unit is now stopped, with following functions in operation:

• Anhydrous reactor pump 520-PP-010 • Crystallizer agitator 520-AG-020 • Vacuum pump 520-PP-022/023 with automatic pressure control • Cooling liquor flow through condenser with automatic temperature control • Liquor flow to elutriator via 520-FICA-0201 • Polishing filter feed pump 520-PP-060/061 • Filtrate pump 520-PP-065/066 • Centrate pump 520-PP-004/041 • Settler rake mechanism 510-TM-050 • Second stage crystallization feed tank agitator 520-AG-005 • Condensate pump 520-PP-045/046 • Hot process water pump 520-PP-091/092 • Seal water on instruments and pumps

Whenever possible keep liquor in second stage crystallizer and settler. Proceed with washout procedure as required for the shutdown.


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7.5 Going standby and restart

7.5.1 Going standby of first stage crystallization circuit

Purpose of this procedure is to keep the crystallization circuits ready for fast recovery of production (e.g. during calciner cleaning). 1 Stop feed from calciner 2 Stop first stage slurry pump 510-PP-020/021, close valve at crystallizer, flush slurry

transfer line, close discharge valve and open drain valve. 3 Close settler overflow supply to crystallizer via 510-FCV-0001. 4 Reduce process water supply to scrubber via 510-FCV-0003 to ~2 m3/h, with

throttled recirculation valve. Slurry is kept inside crystallizer with agitator running. Crystals to be transferred from the elutriator to centrifuge. 5 When elutriator is empty of crystals (take level control on manual), then close

elutriator bottom valves 510-ECV-0201/0204. 6 Flush front-side of centrifuge screen with hot process water until all solids are

dissolved. 7 Stop centrifuge and close hot water supply via 510-FCV-0201/0202. 8 Close process water supply to deaerator via 510-FCV-0301. 9 Stop guar supply pump 510-MP-072/073 10 Stop settler underflow pump 510-PP-050/051. Flush lines. Now unit is standby with following functions on:

• Crystallizer agitator 510-AG-010 running • First stage crystallizer wall wash timers 510-KIS-0001/0002 • Hydrator pump 510-PP-010/011 running • Scrubber fan 510-FN-010 running • Scrubber pump 510-PP-015/015 running • Reduced process water to scrubber via 510-FCV-0003 • Liquor circulation to elutriator 510-SP-025 via 510-FCV-0101 • Settler overflow pump 510-PP-060/061 running • Settler rake mechanism 510-TM-050 running • Purge water on instrument and seals

7.5.2 Going on standby of second stage crystallization circuit

1 Close 15 bar steam supply to thermo compressor 520-SJ-010. Keep reactor above 115°C.

2 Prior to stopping pump 520-PP-005/006, flush line(because otherwise 520-XSV-0001/0002 is closed). Stop second stage crystallization feed pump 520-PP-005/006,


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flush both sides of the automated on/off valve 520-XSV-0001/0002 with hot water for several minutes (this valve closes automatically when the pump stops), close the valve at the feed tank and open the drain valve.

3 Stop filtrate supply from filtrate tank 520-TK-065 to slurry feed line (close 520-DCV-0002).

4 Stop slurry transfer from anhydrous reactor 520-EV-010 to 520-EV-020 by closing valve at reactor, flushing line with hot water for several minutes (always flush in two directions), closing valve at crystallizer, stop flush water and open drain valve of “S2” connection. It may be necessary to set 520-LICSA-0001 to manual to keep the control valve open while flushing.

5 Stop second stage slurry pump 520-PP-020/021, close the valve at the crystallizer, flush the line with water for several minutes, stop the flush water, close the discharge valve and open the drain valve.

6 When elutriator is empty of crystals, (having level control 520-LICSA-0201 in manual) close elutriator outlet valves 520-ECV-0301/0304.


8 Stop centrifuge and close hot water supply via 520-FCV-0301/0302. 9 Stop second stage belt conveyor 520-CV-040 10 Close 520-FCV-0701 ( hot process water supply to deaerator 520-DE-050) 11 Stop guar pump 520-PP-074/075 12 Stop settler underflow pump 520-PP-050/051 Second stage crystallizer is now standby with following function running:

• Anhydrous reactor pump 520-PP-010 running • Second stage crystallizer agitator 520-AG-020 running • Second stage crystallizer wall and demister wash timers 520-KIS-0101/0102/0103 • Vacuum pump 520-PP-022/023 running • Cooling liquor on condenser 520-HX-020 running • Filtrate circulation to elutriator 520-SP-025 running • Feed tank agitator 520-AG-005 running • Centrate pump 520-PP-040/041 running • Settler rake mechanism 520-TM-050 running • Filter feed pump 520-PP-060/061 running • Filters 520-FL-060/061 in operation • Filtrate pump 520-PP-065/066 running • Filter aid pump 520-PP-085 running • Condensate pump 520-PP-045/046 running (a certain amount of condensate from

the fuel oil heater is collected in 520-TK-045. Any flash steam will be vented to suction header of steam jet 520-SJ-010. As the jet is not in operation, steam will be transferred via second stage crystallizer 520-EV-020 to the vacuum system.


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• Pre-coat tank agitator 520-AG-080 running • Filter aid tank agitator 520-AG-085 running • Hot water pump 520-PP-090/091 running • Purge water on instruments and seals

7.5.3 Restart from stand-by of first stage crystallization unit

This procedure described situation of restarting after a standby period. 1 Start first stage centrifuges 2 Start feeding calcined feed to crystallizer 3 Set settler overflow liquor supply to crystallizer via 510-FCV-0001 according setting

list. 4 Start first stage slurry pump 510-PP-020/021 and set flow rate according to setting

list. 5 Set process water supply to scrubber via 510-FCV-0003 according to setting list 6 Open bottom valves 510-ECV-0201/0202 of elutriator slightly on manual. Check

crystals are coming out. After some time put ECV’s on automatic. 7 Open hot water flow to centrifuge via 510-FCV-0201/0202. 8 Start process water supply to deaerator via 510-FCV-0301 9 Start guar pump 510-MP-072/073 and check amount. 10 Start settler underflow pump 510-PP-050/051 with valves set for recycle to

deaerator and transfer to slurry tank 900-TK-260

7.5.4 Restart from standby of second stage crystallization circuit

1 Start 15 bar steam supply to thermo compressor 520-SJ-010 2 When anhydrous reactor is ~120° C, start second stage crystallization feed pump

520-PP-005/006 and set rate according to settings list 3 Start filtrate supply from filtrate tank 520-TK-065 to feed tank 520-TK-005 (open

520-DCV-0002). 4 Start slurry transfer from anhydrous reactor 520-EV-010 to 520-EV-020 by opening

520-LCV0001A/0001B 5 Start second stage belt conveyor 520-CV-040 and ensure fluid bed dryer is ready to

receive feed (otherwise 520-CV-040 cannot start).. 6 Start second stage centrifuges 520-CF-035/036 7 Start second stage slurry pump 520-PP-020/021 8 Open hot water supply to centrifuge via 520-FCV-0301/0302. 9 Slowly open elutriator outlet valves 520-ECV-0301/0304 and check crystals are

coming from 520-CF-035/036. After some time put ECV’s on automatic. 10 Start settler underflow pump 520-PP-050/051 11 Start guar pump 520-MP-074/075 and check amount


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12 Open 520-FCV-0701 ( hot process water supply to deaerator 520-DE-050) and set flow rate according setting list (ensure bypass over 520-FCV-0701 is closed)


– Preparation of guar solution: add guar from bags – Flow rate of guar dosing pumps – Check purgerators on instruments are set correctly in accordance with the setting list – Check pump and agitator seals:

• Flow rate of purgerators is according to setting list • Check that water is dripping from the seal. In case no dripping is visible or if a

continuous flow is visible, maintenance attention by a qualified person is required. – Check sump 520-SU-095/100 (e.g. automatic level switch 520-LSA-0702/0803)


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7.6.1 Water balance

The water balance of the first and second stage have to be monitored carefully. Too much water will result in product loss. Not enough water will result in too high a sulfate content in the first stage crystallizer and also product loss when monohydrate in the deaerators is not dissolved. Set points for flows are on the setting list. The settings have to be taken proportional to the actual operating capacity of the unit. Water input: – Process water supply on first stage scrubber (510-FIC-0003) (not proportional but fixed

flow rate) – Process water on first stage deaerator (510-FIC-0301) – Hot process water on first stage and second stage centrifuge (510-FIC-0201/0202,

520-FIC-0301/0302). – Hot process water on second stage deaerator (520-FIC-0701) – Process water on wall wash for crystallizers – Process water to second stage vacuum system (520-FI-0102/0103) – Process water via guar supply; negligible – Hot process water on second stage centrate tank (520-FI-0601); normally not in use – Process water on filtrate tank (520-FI-1001); normally not in use – Purge water on pumps and seals (not proportional but fixed flow rate) – Flushing of lines (not proportional) – Wash-out of crystallizers (incidental, not proportional) – Sight glass flush water Water output: – Evaporation from first stage crystallizer via scrubber to air – Evaporation from second stage crystallizer to condensate – Free moisture and monohydrate water in centrifuge cake – First stage settler underflow (510-HIC-0301/0302) to 900-TK-260 – Second stage settler underflow (520-HIC-0701/0702) to 900-TK-260 – First stage liquor blowdown to 900-TK-250 (via 510-LCV-0401) – Emptying of filter content to 900-TK-260


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7.6.2 Critical process parameters

Location Parameter Tag or analysis Purpose; target or setpoint

510-EV-010 Density 510-DICA-0001 Product quality;

1540 kg/m3 (35 wt%)

510-EV-010 Temperature 510-TICA-0001 Operating parameter;

97°C

510-DC-015 Process water supply 510-FICQA-0003 Prevent scaling of scrubber,

maintain low sodium sulfate

concentration, dissolving

power;

22 m3/h

510-HX-015 Process water supply 510-FI-0018 Reduce vapor stream to 510-

FN-010; 20 m3/h

510-SP-025 Underflow solids

concentration

Content of insolubles in

monohydrate crystals

Content of NaF in


Sample

Sample

Sample

Centrifuge performance;

50 wt%

< 0.1 wt% insolubles

< 0.3 wt% NaF

510-SP-025 Overflow solids

concentration

Sample Product loss;

2 wt%

(510-CF-035/036 Cake moisture Sample not possible Product quality;

5 wt%)

510-CF-035/036 Centrifuge wash water

flow rate

510-FICA-0201/0202 Product quality;

3.5 m3/h per centrifuge

510-DE-050 Process water addition on

deaerator

510-FIC-0301 Water balance, product loss;

4 m3/h

510-TK-050 First stage settler sludge

level

510-LI-0301 Settler performance;

4 discs visible

510-MP-072/073 First stage settler guar

supply


80 g/ton solids

510-DE-050 First stage deaerator

overflow

Sample / Visual Monohydrate in solids

indicates bad performance of

crystallizer/elutriator, or too

small water supply (510-FIC-

0301)

510-TK-050 First stage settler overflow

solids concentration

Sample / Visual Product quality;

< 0.1 wt%


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510-TK-050 First stage settler

underflow solids

concentration

Sample Settler performance;

20 wt%

520-TK-005 Level 520-LISA-0501 Buffering volume; TBD

520-EV-010 Density 520-DICA-0001 Product quality;

1480 kg/m3 (28 wt%)

520-EV-010 Temperature 520-TICA-0001 Operating parameter;

120°C

520-HX-010 Temperature difference of

tube wall and bulk

520-TDIA-0006 Reduce risk of scaling;

1.6°C

520-HX-010 Temperature difference of

slurry outlet and slurry

inlet

520-TDIA-0005 Reduce risk of scaling; 1.2°C

520-EV-020 Pressure 520-PICA-0101 Keep crystallizer at boiling

condition; -0.16 barg

520-EV-020 Solids concentration Sample Product quality;

1550 kg/m3 (39 wt%)

520-SP-025 Underflow solids

concentration

Content of insolubles in


Content of NaF in


Sample

Sample

Sample

Centrifuge performance;

50 wt%

< 0.02 wt% insolubles

< 0.02 wt% NaF

520-SP-025 Overflow solids

concentration

Sample Product loss;

1.5 wt%

520-CF-035/036 Cake moisture Sample Product quality;

5 wt%

520-CF-035/036 Centrifuge wash water

flow rate

520-FICA-0301/0302 Product quality;

3.5 m3/h per centrifuge

520-FL-060/061 Filter pressure drop 520-PDIA-0902/0908 Monitor filtration time;

Filter to be regenerated at 2

bar

520-DE-050 Hot process water

addition on deaerator

520-FIC-0701 Water balance, product loss;

8.2 m3/h

520-TK-050 Second stage settler

sludge level


4 discs visible


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510-MP-074/075 Second stage settler guar

supply


Supply guar to a

concentration of 5 mg/l in the

deaerator liquor flow rate

520-DE-050 Second stage deaerator

overflow

Sample / Visual Monohydrate in solids

indicates bad performance of

crystallizer/elutriator, or too

small water supply (520-FIC-

0701)


overflow solids

concentration

Sample / Visual Too much solids will result in

increased cake growth on

filter and shorter cycle time;

< 0.01 wt%


underflow solids

concentration

Sample Settler performance;

15 wt%


Refer to Analytical Manual.


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7.7.1 Buffering of slurry in case of capacity variation of first and second stage

Feed tank 520-TK-005 provides buffer capacity in case the capacity of the first and second stage crystallization differ. If the operating capacity of both sections differ, the solids concentration in the tank will vary. The normal concentration is approx. 50% (the tank and agitator are designed for 70%). The solids concentration in 520-TK-005 follows from the following parameters: 1 Capacity ratio of first and second stage crystallization 2 Moisture content of cake from first stage centrifuges 510-CF-035/036 3 Solids concentration of slurry feed to second stage centrifuges 4 Moisture content of cake from second stage centrifuges 5 Wash water flow rate on second stage centrifuges

A different operating capacity of both sections has consequences for the operating conditions of the first and second stage. For example, a higher capacity of the first stage has the following consequences: 1 The level in 520-TK-005 increases 2 The solids concentration in 520-TK-005 increases 3 More filtrate is required to dilute the slurry feed to the second stage. As a

consequence the supply of second stage filtrate to first stage crystallization is less, which means less blow down from 510-TK-060, so higher sulfate concentration in first stage. This has to be compensated by adding more water to the second stage deaerator.

7.7.2 Guar preparation procedure

Guar gum is supplied in bags. Make sure the bags contain guar gum. The guar preparation is an automated system. Preparation of 0.3 wt% guar solution in 510-TK-070. 1 The field operator keeps a sufficient guar level inside the hopper 510-TK-071. 2 At low level in 520-TK-070 process water supply valve 510-SV-004 is opened. 3 At normal level following steps are activated:

• Agitator 510-AG-070 is started • Screw feeder 510-SC-070 is started and runs for preset time of timer. • Gate 510-MG-071 is opened and stays open for preset time of timer. (Timer of

screw is set at a longer time in a way that the screw runs empty after closure of gate 510-MG-071)

4 At high level process water supply valve 510-SV-004 will close.


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5 A third timer is set to provide time for ripening of the guar solution. The timer is started when guar addition is completed. When the preset time is past, transfer of solution from preparation tank 510-TK-070 to day tank 510-TK-075 is released.

Transfer of guar solution from preparation tank 510-TK-070 to day tank 510-TK-075. 1 At low level in the day tank 510-TK-075 transfer from preparation tank 510-TK-070

is started (start of 510-PP-070/071). The pump can only start if the guar preparation process is completed (time for ripening is completed and level in 510-TK-070 is not low).

2 Transfer pump 510-PP-070/071 is stopped when low level in preparation tank is reached (preferred operation) or when high level in day tank 510-TK-075 is reached

7.7.3 Guar flow rate measuring procedure

1 The guar dosing pump applicable to the calibrating tube is running 2 Open bottom valve calibration tube. When tube is full, close valve in supply line from

510-TK-075. 3 Measure time to empty the calibration tube. 4 Open valve in supply line from 510-TK-075 and close bottom valve of calibration

tube. Make sure the pump does not run dry. 5 The recorded time in combination with the pumped volume from the calibration tube

gives the guar solution flow rate (vendor info required of the calibration tubes)

7.7.4 Heating process liquor with start-up heater

Section 510 Liquor can be pumped through first stage mother liquor heater 510-HX-060 for heating up during start-up. During normally operation the flow is bypassing the exchanger. The by-pass valve has to be throttled when the heater is used. Open up supply and return liquor valve of the exchanger always completely to prevent overheating of liquor and scaling. The liquor is heated to approx 90°C with 3 bar steam. Steam supply can be adjusted locally by reading the local liquor outlet temperature 510-TI-0402. The recirculation flow rate through the exchanger is significantly smaller than normal circulation rate (respectively 50 and 300 m3/h). If the 510-HX-060 is used for heating during normal operation, then open supply and return liquor valve completely, and throttle bypass slightly, while checking that valve position 510-FCV-0001 and 510-FCV-0101 remain within control range. After using 510-HX-060 the steam supply has to be closed, and the line section has to be flushed to prevent plugging.


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Section 520 Liquor can be pumped through second stage mother liquor heater 520-HX-065 for heating up during start-up. During normal operation the flow is bypassing the exchanger. The by-pass valve has to be throttled when the heater is used. Open up supply and return liquor valve of the exchanger always completely to prevent overheating of liquor and scaling. The liquor is heated to approx 90°C with 3 bar steam. Steam supply can be adjusted locally by reading the local liquor outlet temperature 520-TI-1002. The recirculation flow rate through the exchanger is significantly smaller than normal circulation rate (respectively 50 and 300 m3/h). If the 520-HX-065 is used for heating during normal operation, then open supply and return liquor valve completely, and throttle bypass slightly, while checking that valve position 520-DCV-0002, 520-FCV-0201 and 520-LCV-1001 remain within control range. After usage of 510-HX-060 the line section has to be flushed to prevent plugging.

7.7.5 Pump failure of filter feed pump 520-PP-060/061

Flow rate over filter has to be constant in order to reduce damage of filter cake. In case flow is stopped, the cake might start to fall off. Pumps 520-PP-060/061 are provided with automatic changeover and check valves are installed to prevent back flow through the standby pump. A point worth remembering is that although the filter feed has low solids concentration, check valves still can fail. If this occurs then a consequence is a too low flow rate to the filter and the level in 520-TK-060 will increase. If a check valve fails, the following can be seen: – 520-PP-060 or 061 is running – 520-FICA-0901/0902 low alarm – 520-FCV-0901/02 will travel to full open position – 520-PDIA-0902/0908 not high When the discharge valve of the standby pump is closed, and the flow rate increases to normal value, the cause of low flow must be the check valve which has to be repaired. For switching to the spare pump during operation, refer to procedure 7.7.6.2 below.


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7.7.6 Centrifugal pump start/stop and changeover

7.7.6.1 Centrifugal pump start/stop

The general procedure for a normal start and stop is described here. For switching over from running to spare pump, see procedure below section 7.7.6.2. This is applicable for centrifugal pumps. For positive displacement pumps refer to procedure in section 7.7.7. Start of pump 1 Open purge water supply shut-off valve and check flow rate (drain valve or

discharge or suction valve MUST be open to have flow of purge water) 2 Check the valves in the discharge line of the pump is set up for the right destination 3 Check suction and/or discharge valve of spare pump is closed. 4 Close drain valve and open suction valve (if pump is empty allow to fill up by venting

on discharge side of the pump). 5 Check discharge valve is closed, start pump and open discharge valve. Stop pump 1 Close discharge valve and stop pump. 2 Close suction valve. 3 Open flush valve on discharge line upstream of discharge valve, open discharge

valve and flush through discharge valve. 4 Close discharge valve and open suction valve and flush through suction valve. 5 Close suction valve, open drain valve and close flush water valve. 6 Drain pump and leave drain valve open. 7 Close purge water shut-off valve.

7.7.6.2 Use of installed spare pump

For most application an installed spare pump is provided. This can be used in case of failure or maintenance of the running pump or for routine changeover. Separate procedures are given for pump failure, and for routine pump changeover. The procedure applies to centrifugal pumps. See procedure in section 7.7.7.2 for positive displacement pumps. Procedure in case running pump has failed: 1 Close discharge valve of the pump that failed and put local switch in off position. 2 Open purge water supply shut-off valve and check flow rate (drain valve or

discharge or suction valve MUST be open to have flow of purge water) 3 Close drain valve and open suction valve of spare pump (if pump is empty allow to ill

up by venting on discharge side of the pump).


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4 Check discharge valve is closed, start spare pump and open discharge valve 5 For maintenance, flush and drain pump that failed as described in section 7.7.6.1. Procedure to changeover with running pumps: 1 Open purge water supply shut-off valve and check flow rate (discharge or suction

valve MUST be open to have flow of purge water) 2 Check discharge valve of spare pump is closed, close drain valve and open suction

valve (if pump is empty allow to fill up by venting on discharge side of the pump) 3 Start spare pump and open discharge valve. 4 Close discharge valve of the original running pump and stop the pump. 5 Flush and drain pump as described in section 7.7.6.1. Note 1: As soon as the running pump is stopped, backflow can occur (there are no check valves installed). Therefore, first close discharge valve of the running pump and then stop this pump. Note 2: Close the purge water supply before the pump is isolated in order to prevent high pressure in pump and piping. Note 3: For pumps with automatic changeover, suction valve and discharge valve of the standby pump are open. A check valve prevents back flow through the standby pump. Note 4: Filter feed pump 520-PP-060/061 has automatic changeover. If the pumps are changed over manually, special attention is required not to cause pressure variations on the filter cake. Therefore operate discharge valves slowly when connecting the spare pump and disconnecting running pump.

7.7.7 Start/stop and changeover of 510-PP-050/051 and 520-PP-050/051

7.7.7.1 Start/stop of 510-PP-050/051 and 520-PP-050/051

The general procedure for a normal start and stop is described here. For switching over from running to spare pump, see procedure below section 7.7.7.2. This is applicable for positive displacement pumps 510-PP-050/051 and 520-PP-050/051. For centrifugal pumps refer to procedure in section 7.7.6.


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The pump has to be filled to provide lubrication of the stator (not for priming purpose). When the pump is stopped, sufficient liquid is normally trapped between the pumping elements to provide the necessary lubrication for restarting. However, if the pump has been left standing for a long time or has been dismantled, it must be refilled and given a few turns before starting, to get sufficient lubrication between the rotor and the stator. Start of pump If line and pump are empty: 1 Fill up suction line (open bottom valve of settler and drain valve at pump suction) 2 Fill up pump with water hose via plug on top of the pump and give it a few turns with

tool provided If line and pump are full, proceed with: 3 Check purge water supply is open and check flow rate (discharge or suction valve

has to be open to have flow of purge water) 4 Check the valves in the discharge line of the pump is set up for the correct

destination 5 Check discharge valve of spare pump is closed. 6 Open suction and discharge valves 7 Start pump Stop pump 1 Keep pump running during flushing. Open suction flushing connection and open

flush valve. 2 Close valve in suction line and flush through pump and discharge valve. 3 Stop pump and close discharge valve. 4 Open suction valve and flush through suction valve. 5 Close flush valve and keep suction valve open to allow purge water to flow through

the seal. Note 1: Never run the pump dry, not even for a few revolutions. Note 2: Never run pump with a closed suction or discharge valve. Note 3: Do not vary the flow rate by throttling suction or discharge valve

7.7.7.2 Use of installed spare 510-PP-050/051 and 520-PP-050/051

An installed spare pump is provided. This can be used in case of failure or maintenance of the running pump, or in a certain frequency. Separate procedures are given for routine pump changeover and for pump failure. The procedure applies to positive displacement pumps 510-PP-050/051 and 520-PP-050/051. See procedure in section 7.7.6.2 for centrifugal pumps.


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Procedure in case running pump has failed: 1 Close discharge valve of the pump that failed and put local switch in off position. 2 Open suction and discharge valve of spare pump 3 Start spare pump 4 For maintenance, close purge water supply and flush the pump and the enclosed

suction and discharge line sections. Procedure for changeover with running pumps. 1 Open suction valve and discharge valve of spare pump and start spare pump 2 Keep pump running during flushing. Connect process water hose on suction flushing


the seal Note 1: Backflow does not occur when the running pump is stopped for positive displacement pumps Note 2: Close the purge water supply before the pump is isolated, to prevent high pressure in pump and piping.

7.7.8 Start-up and shutdown of condensate tank 520-TK-045

Start-up 1 Check that boiler feed water tank 900-TK-040 is ready to receive condensate. 2 If hot process water tank is not yet ready to receive condensate keep 520-LCV-1101

closed. 3 If second stage crystallization system is ready to receive flash steam from 520-TK-

045, put 520-PIC-1101 on automatic with setpoint according to the setting list. If second stage crystallization system is not ready to receive flash steam, keep 520-PCV-1101 closed and open manual vent valve on 520-TK-045.

4 Check valve settings of pump 520-PP-045 (520-TCV-0402 on inlet of desuperheater 520-DS-010 closed).

5 Select a pump, keep discharge valve closed, open bottom valve of 520-TK-045 and suction valve of the pump.


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6 When sufficient level has built up inside 520-TK-045, start pump 520-PP-045/046 and open discharge valve.

Shutdown 1 Stop pump 520-PP-045. 2 Close suction valve of 520-TK-045 3 Close the incoming condensate lines and destination lines. 4 Close 520-PCV-1101. 5 Tank will pull vacuum when cooling down which is not a problem as it is designed

for full vacuum. Note: This pump has automatic changeover in case the running pump fails: when not in use, the pump suction and discharge valves are open and the drains closed. A check valve prevents back flow via the standby pump.

7.7.9 Start-up and shut down of hot water tank 520-TK-091

Start-up 1 Fill up process water tank 520-TK-091 with 520-LCV-1301 on manual and put on

automatic when the level is near its setpoint (see setting list) (ensure bypass over 520-LCV-1301 is closed).

2 Open process water supply line from scrubber cooler 510-HX-015. 3 Check position of valves at destinations and start pump 520-PP-091/092 and put

520-PICA-1301 on automatic. 4 Close 520-TCV-1301, open steam supply and condensate return of 520-HX-091 and

put temperature controller 520-TICA-1301 on automatic. Shut down 1 Close steam supply and condensate return of 520-HX-091. 2 Close process water supply line from header and from 510-HX-015. 3 Stop pump 520-PP-091/092. High feed of condensate to 520-TK-091: In case the condensate from 520-TK-045 is not returned to the boiler feed water tank 900-TK-040 but instead is collected in 520-TK-091, significantly less process water is needed and less heating. It is possible that the supply to the hot process water tank 520-TK-091 becomes larger than the requirement, and that the tank overflows. It is therefore important to discharge condensate to the boiler feed water tank.


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7.7.10 Performance monitoring of anhydrous reactor heater

Inside any crystallizer there is a relation between supersaturation and crystal growth. Too high supersaturation gives chances of crystal growth on parts of the crystallizer causing scale (hot surfaces, sharp edges) and increased nucleation, resulting in too small crystals. Inside the anhydrous heater, the growing of crystals on the tube surface can occur if local conditions allow this (high temperature, surface roughness, low flow rate). Special care is taken to create a smooth surface of the inner tube walls (bright annealed) and the slurry velocity is maintained at 2 m/s. These factors are in principal fixed parameters. During operation the temperature is monitored continuously. The following temperature differences are monitored: 1 Steam inlet temperature and slurry outlet temperature (temperature difference of

tube wall and bulk): 520-TDIA-0006 is 1.6°C 2 Slurry outlet temperature and slurry inlet temperature: 520-TDIA-0005) is 1.2°C 3 LMTD (Log mean temperature difference of inlet and outlet streams) (performance

of the exchanger) is 2.1°. The first two temperature differences are controlled with 520-TICA-0001. The LMTD changes as a function of the operating capacity (heat input). If the LMTD increases for a specific operating capacity (heat input) there are some possible causes: – Setpoints of 520-TICA-0402 and 520-TICA-0001 are changed – Scaling and/or plugging inside tubes – Inert accumulation on condensate side – Decreased slurry circulation flow rate – Variation in slurry concentration (specific heat, density, circulating flow rate) The deviation of the LMTD that can be detected as a change, depends on the accuracy (reproducibility) of the temperature indication. If the inaccuracy of the temperature indication is 0.1°C, a deviation of the LMTD of 10% or more can be detected. Following actions should be carried out if LMTD is increased: – Check 520-TICA-0402 and 520-TICA-0001 are set according to the setting list – Check vent of 520-HX-010. The manual vent valve has to be open slightly during

operation to purge inerts. Open vent slightly further and see if it has any effect on the LMTD.

– Check trended data of power consumption of 520-PP-010 (520-EIA-0001) – Check trended data of slurry concentration When no other deviations are found then tubes are probably plugged and a wash out is required. Unfortunately, as the inaccuracy of the temperature indication compared to the


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normal value of the LMTD is rather high, a fair amount of tubes may be plugged by the time it is detected by a change in LMTD.

7.7.11 Filter regeneration

Filter regeneration refers to 4 P&ID’s: 520-09 Filtrate feed 520-10 Liquor polishing 520-11 Polishing filter filtrate storage & distribution 520-13 Precoat and filter aid A break down of the filtration and regeneration cycle is given below: Description Unit Value Applying precoat min 15 Filtration h 47 Emptying filter vessel and cake discharge

min 10

Sluicing min 10 Backwash min 10 Total regeneration time min 45 The precoat system has to be ready to use (see section 7.7.12). Check the availability of process water. In the description below filter 520-FL-060 will be regenerated, filter 520-FL-061 is in operation. The following actions take place: If 520-PDI-0902/0908 reaches its alarm point (2 bar), the operator starts the regeneration cycle when precoat tanks is ready and there is no conflict in operation (other filter regenerating or other large process water consumer taking water). 1 Disconnect 520-FIC-0902 (feed rate of running filter 520-FL-061) from 520-LICSA-

0802. (Level in 520-TK-060 will rise because one filter is regenerating) 2 Freeze valve position of 520-LCV-1001 on 520-PID 520-11. (Level in 520-TK-065

will fall because one filter is regenerating.) 3 Close filter feed and filtrate discharge (valve 520-XSV-0904 and 520-XSV-0913) 4 Open 520-XSV-0924 for draining to 520-TK-070, and if 520-XSV-0924 is open, open

vent/deaeration 520-XSV-0903 5 Waiting time. Duration to be set with timer. (few minutes)


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6 Supply process water for sluicing (open 520-XSV-0907). (Second process water pump will start automatically based on header pressure.) Duration to be set with timer (approx. 10 minutes). Close 520-XSV-0907.

7 Supply process water for backwashing (520-XSV-0908). Duration to be set with timer (approx. 10 minutes)

8 Waiting time for draining. Duration to be set with timer. 9 Close vent 520-XSV-0903 and 520-XSV-0924. 10 Open precoat feed line 520-XSV-0905 and overflow 520-XSV-0906. 11 Field operator to start precoat pump 520-PP-080 locally. 12 When filter is full (set time interval, also visible at tundish), open 520-XSV0925 and

close 520-XSV-0906. 13 Field operator adds 3 bags of diatomaceous earth to 520-TK-080. 14 Precoating to proceed for approx 15 minutes. 15 When precoating is done, following actions to take place:

• open line to filtrate tank 520-TK-065 520-XSV-0913 • close line to precoat tank 520-TK-080 520-XSV-0925 • open filter feed line 520-XSV-0904 • open 520-FCV-0901 20% • close precoat feed 520-XSV0905 and stop 520-PP-080 • ramp setpoint 520-FIC-0901 to 120 m3/h

16 When liquid level in feed tank 520-TK-060 reaches its normal low setpoint, set 520-FIC-0901 to automatic. Reconnect 520-LICSA-0802 (level of 520-TK-060) to 520-FIC-0901 and 0902.

17 When liquid level in filtrate tank TK-065 is at its normal setpoint, unfreeze valve position of 520-LCV-1001.

The total amount of slurry and water as drained to 520-TK-070 is more then the capacity of 520-TK-070. Therefore, filter backflush pump 520-PP-070/071 will be started automatically via level switch 520-LISA-1002 H(S). Agitator 520-AG-070 is kept running continuously. If the regeneration process is disturbed for some reason the filter feed tank 520-TK-060 will become full and the filtrate tank 520-TK-065 will run empty. As a consequence, the production rate of the second stage crystallization section has to be decreased to 50%. In this case liquor supply to the elutriator is reduced to 50% as well, leading to off-spec product. Note: Ensure the bypass over 520-FCV-0901/0902 is closed.


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7.7.12 Precoat preparation

Precoat tank 520-TK-080 is filled with filtrate and process water via 520-XSV-1201. 520-XSV-1201 is opened manually on the DCS and closed automatically, when 520-LISA-1201 reaches target level of 90% (high level switch). When starting with precoat application, the filter and the lines are empty. In total an amount of approx. 25 m3 is required for filling up and the tank level will be reduced from 90% to 30%. The filter hold-up of approx. 21.5 m3 is the actual loss of precoat liquor, which is approx. 28 ton. The filter aid concentration is 0.5 wt%. On a total of 28 ton loss, 140 kg has to be added. Precoat filter aid is added manually from bags. The precoat liquor can be diluted with 10% water to prevent scaling (to be determined during first start-up). The field operator is in attendance when filter regeneration has started. When backwashing is complete, precoat will be applied. There is no waiting time available in the regeneration time. If the precoat is not started at the right time, or if there is any other delay in the filter regeneration, the second stage filtration operating capacity has to be decreased. Following procedure: 1 Manual valves of filtrate and process water are closed 2 Suction valve of precoat pump is open 3 Open 520-XSV-1201 (by desk operator) 4 Read tank level on 520-LISA-1201 5 Open process water supply and add the required amount (set by timer) 6 Close process water valve and open filtrate valve 7 When target level is reached, 520-XSV-1201 will automatically be closed 8 Close manual valve in filtrate feed line. 9 Start agitator locally by hand 10 Add diatomaceous earth through funnel 11 Flush funnel if needed with water hose. 12 Wait for instruction from the DCS operator to start the precoat pump (520-XSV-0905

or 0919 has to be open). 13 Start pump 520-PP-080 14 The pump is stopped when precoating is completed 15 Stop agitator Note: Purge water is supplied to 520-PP-080. To maintain a continuous flow, keep suction valve open and close discharge valve of the pump if pump is not running.


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7.7.13 Filter aid system

This procedure is based on filteraid preparation of once a day. This corresponds to approx. 1 m3 of liquor with 150 kg of filteraid. Filter aid tank 520-TK-085 is filled with filtrate via 520-LSV-1202, which is opened manually on the DCS and closed automatically, when 520-LISA-1202 reaches target level. – Read tank level – Open 520-LSV-1202 – Close 520-LSV-1202 if level increased 5% on the scale (manually) When filling once a day, the operating level varies 5%. Top up the tank until the normal operating level of 85% is reached. In case of longer time intervals of filter aid slurry preparation, it has to be started at the minimum operating level of 30%. Filling procedure: 1 Agitator 520-AG-085 is running 2 Pump 520-PP-085 is running 3 DCS operator to start filling sequence:

a. Read tank level on 520-LISA-1202 b. Open 520-LSV-1202 c. When level increased with 5%. Close 520-LSV-1202

4 Add 150 kg of filter aid through funnel. Clean funnel with water hose if needed.

During filling of the tank, the concentration decreases to some extent when liquor is added before filter aid is added. This has no negative effect on the filter cake if this situation does not exceed duration of 1 hour. This pump is frequency controlled for speed control and the pump runs continuously. In order to keep sufficient velocity in the lines, the filter aid flow is switched on and off with valve 520-XSV-1201/1202. For timer setpoints see setting list. Start-up of filter aid system. This has to be started up shortly after one filter is put in operation. 1 Fill up the tank with liquor, by opening 520-LSV-1202. It closes automatically by high

level switch. 2 Start agitator 3 Add the required amount of filter aid. If 520-TK-080 was completely empty, add

2300 kg of filter aid.


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4 Activate timer for 520-XSV-1201/1202 5 Start 520-PP-085 Shut down filter aid system In case both filters are taken out of operation, filter aid supply has to be stopped. 1 Stop 520-PP-085 2 Close 520-XSV-1201 and 1202 3 Drain return line by opening flush connection at high point near 520-XSV-1201/1202

back to the tank. Also drain and flush pump discharge and suction line. If possible keep purge water supply open and the pump suction valve to allow a positive flow.

Note: If 520-PP-085 fails, back flow from filter occurs when 520-XSV-1201 and 520-XSV-1202 are open. If pump fails, a low flow alarm is generated from 520-FIA-1201. A long duration of back flow will cause a high level in 520-TK-085 (HH alarm on 520-LISA-1202) in which case 520-XSV-1201 and 1202 have to be closed.

7.7.14 Flushing of centrifuge

During normal operation, flushing of centrifuges with process water is necessary once every 8 hours. Flush time is 5 minutes.

7.7.14.1 First stage centrifuges 510-CF-035/036

Slurry feed to centrifuges continues. Open manual washing valves and timer controlled wall wash valve 510-KIS-0201/0202 (put to manual on DCS).

7.7.14.2 Second stage centrifuges 520-CF-035/036

Slurry feed to centrifuges is interrupted (close 520-ECV-0301/0304). Divert the chute diverter below the centrifuges to centrate tank 520-TK-040. Open manual washing valves and timer controlled wall wash valve 520-KIS-0301/0302 (put to manual on DCS). When done, divert the chute diverter to 520-CV-040 and open 520-ECV-0301/0304.


Spilled liquor and slurry can be pumped to first stage deaerator. This is only allowed if liquor or slurry is not contaminated (with non-product materials like filter aid). Sump pump 520-PP-095 is started automatically by level switch 520-LS-0702.


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Agitator 520-AG-095 runs continuously. For start-up: 1 Make sure deaerator 510-DE-050 and settler 510-TK-050 are ready for receiving

liquor or slurry from the sump. 2 Open valve towards 510-DE-050 and close valve towards 900-TK-250.

If the slurry is contaminated, then close towards 510-DE-050 and open valve towards 900-TK-250

3 When sufficient level in the sump, start agitator 520-AG-095 4 Set pump operating switch in automatic (check) For shut down:

1 Set pump switch on off (check) 2 Close discharge valve of 510-PP-095 3 Stop agitator 520-AG-095 Note: Flushing of line is required after pumping slurries and near saturated liquor.


Spilled liquor and slurry can be pumped to first stage deaerator. This is only allowed if liquor or slurry is not contaminated (with non-product materials like filter aid). Sump pump 520-PP-100 is started automatically by level switch 520-LS-0803. Agitator 520-AG-095 runs continuously. For start-up:

1 Make sure deaerator 510-DE-050 and settler 510-TK-050 are ready for receiving liquor or slurry from the sump.

2 Open valve towards 510-DE-050 and close valve towards 900-TK-250. If the slurry is contaminated, then close towards 510-DE-050 and open valve towards 900-TK-250

3 Set pump operating switch in automatic (check)

For shut down:

1 Set pump switch on off (check) 2 Close discharge valve of 510-PP-100 Note: Flushing of line is required after pumping slurries and near saturated liquor.


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7.7.17 Washout procedure crystallization section

HPD, LLC 23562 West Main Street, Route 126 Plainfield, Illinois 60544 USA Tel: 1 (815) 609-2000 Fax: 1 (815) 609-0490 Web site: www.hpdsystems.com

Preliminary Washout Procedures

1 First Stage Crystallizer

1.1 Planned Wash-out Stop solid feed to crystallizer and continue feeding / recycling liquor while drawing off slurry to elutriator and recovering product solids from centrifuges. Physical operating level must be maintained between level sight glasses, although level indication from level transmitter will decline as the density in the crystallizer is reduced. This will require periodically lowering the level set point while maintaining the automatic level control. The typical operating density is 1530 while the density after all solids are removed or dissolved is 1300. After 2 hours of drawing down the density, or at a point when the recovery of solid product from the centrifuges is significantly reduced, begin diluting crystallizer with process water. Again maintain a relatively constant physical level in the crystallizer. During this time, the quantity of liquor in the circuit will increase and may need to be purged. When solids are no longer being recovered by the centrifuges, the centrifuge feed can be stopped and the centrifuges can be washed. When the density in the crystallizer is reduced to 1300, stop the slurry transfer pump, close the isolation valve, flush the line and allow the level in the crystallizers to increase above the upper level sight glass or as high as required to cover any wall scale that developed above the normal operating level. Stop feeding water and allow the crystallizer to be agitated for at least one hour. Monitor the density in the crystallizer during this time. If a significant amount of solid build-up is being dissolved, the density may increase above saturation (1300). If this occurs, additional water must be added and if required liquor removed so that all solid accumulation is dissolved. Once the crystallizer density is maintained below 1300 for at least one hour, the crystallizer can be restarted. First open the isolation valve and start one of the slurry pumps to reduce the physical level in the crystallizer back to the range between the level sight glasses. Then the solid feed can be restarted and the density is rebuilt.

1.2 Emergency Wash-Out In the case where it is not possible to perform the Planned Wash-Out procedure due to equipment or power failure, the crystallizer contents can be dumped through the drain valve. The drain nozzle will usually require flushing with hot process water for several minutes in order to dissolve settled solids. The crystallizer contents are hot (97C) and there is a large volume to drain (300 m3) so the disposition of this material must be thought through before draining is performed. The crystallizer agitator cannot suspend solids once the level is below the top of the draft tube so usually the entire contents must be removed when draining is used. The level transmitter is not able to detect the level below the top of the draft tube so the only indication of level for the remaining 70% of the crystallizer contents is when the vessel is empty and slurry is no longer draining. However, the drain nozzle can become plugged and give a false empty indication so this must be kept in mind when draining and the nozzle should be flushed with hot process water to ensure the crystallizer is empty. Once empty, the equipment repairs can be made and when ready, the crystallizer can be refilled to the operating level with either water or solids-free liquor.

2 Anhydrous Reactor

2.1 Planned Wash-out This wash procedure is used for routine cleaning of heat transfer surfaces of the Anhydrous Reactor Heater. Once refined with operating experience, this procedure should take ~3 hours to perform. The intent is to perform this Quick Wash at frequent enough intervals to prevent complete plugging of any heat exchanger tubes. If tube plugging does occur, the plugged tubes will most likely remain out of service until a complete shutdown is performed with draining the vessel, opening the manways and performing high-pressure water cleaning of the tubes. The initial frequency for performing a Quick Wash is once per week. The frequency can be adjusted based on operating experience. First stop the slurry feed by closing the isolation valve at the Second Stage Crystallization Feed Tank, flushing the line with hot process water and then stopping the slurry feed pump. Stop supplying steam to the Anhydrous Reactor Heater by putting the pressure control valve for the 15 bar steam in manual and closing (520-PCV-0401).

Put level control valve in manual so that slurry withdrawal is continued as the level decreases in the Anhydrous Reactor (520-LCV-0001A/B). Monitor the level in the Second Stage Crystallization Feed Tank. The level will increase in the feed tank as the level decreases in the Anhydrous Reactor. If necessary, stop feeds to the First Stage Crystallizer, flush the slurry transfer lines and recover the remaining product out of the First Stage Elutriator through the First Stage Centrifuges and then allow the First Stage Crystallizer to idle. Brine will also likely need to be purged from the circuit during this time. Continue to draw down the level in the Anhydrous Reactor at normal operating flow rate for ~ one hour or until the level transmitter indicates 20% level (~1 meter below RI nozzle). At this point the DN150 process water line to the Anhydrous Reactor should be opened and the vessel should be filled to a high level. The objective is to reduce the density in the vessel below 1300. Care must be taken to avoid over-filling the vessel and the pressure should also be closely monitored. The vessel should be manually vented from the top vent valve if the pressure increases above 1.5 bar-g. The temperature in the Anhydrous Reactor will decline as the process water is added. When the temperature goes below 115 C, the slurry transfer to the Second Stage Crystallizer must be stopped and the line flushed. If the density is still above 1300 when the vessel is nearly full, it will be necessary to purge material through the drain valve. Once the density is below 1300, the Anhydrous Reactor is allowed to circulate for at least one hour and the density is monitored to ensure that the liquor remains below saturation. After one hour below 1300 density is obtained, the system can be restarted by first applying the steam and heating the contents to 120 C, then begin transferring material to the Second Stage Crystallizer and finally restarting the slurry feed from the Second Stage Crystallization Feed Tank.

2.2 Emergency Wash-Out Whenever possible, the Quick Wash procedure should be used prior to draining the Anhydrous Reactor. This dilutes and dissolves the anhydrous sodium carbonate crystals and reduces the temperature. Attempting to drain anhydrous slurry will result in the instant formation of sodium carbonate monohydrate solids in addition to steam and hot liquor. If equipment failures prevent a Quick Wash from being performed, the next best thing would be to first dilute the anhydrous slurry by opening the DN150 process water connection and filling the Anhydrous Reactor to a high level. Then slurry can be drained through the drain valve. When possible, the Anhydrous Reactor can then be filled with process water to the normal operating level and circulated for at least one hour to dissolve any solid build-up. If significant tube plugging has

occurred, the system will need to be drained of wash water and the high pressure water cleaning system will need to be used to manually clear the plugged tubes.

2.3 High Pressure Water Cleaning After completely draining the system, the manway at the top liquor box of the Anhydrous Reactor Heater is opened along with the manway on the lower section of recirculation piping. The plants “Confined Space Entry” procedure must be implemented before manual cleaning of the tubes can begin. Proper personal protective equipment must be worn by the individuals performing the tube cleaning. The cleaning is performed using the high pressure water cleaning system, consisting of the high pressure pump, high pressure hoses, flexible lance and foot operated valve. The operator of this equipment would stand on the top tube sheet of the heat exchanger and gradually work the flexible lance down into the plugged tube while the high pressure water cuts through the deposited solids. This procedure cleans one tube at a time and can take a substantial amount of time depending on the number of plugged tubes and the nature of the solid deposit. The heat exchanger contains a total of 1378 tubes. When all the tubes are clean, the lower recirculation pipe should be rinsed out and any pieces of solids should be removed through the manway. The manways can then be bolted closed and the system can be re-filled and re-started.

3 Second Stage Crystallizer

3.1 Planned Wash-out The Second Stage Crystallizer is coupled with the Anhydrous Reactor such that it is not possible to wash the Second Stage Crystallizer without also washing the Anhydrous Reactor. The only way to charge a significant amount of dilution water to the Second Stage Crystallizer is through the Anhydrous Reactor. Therefore, a Quick Wash procedure should first be performed on the Anhydrous Reactor and then the Second Stage Crystallizer can be washed. The wash procedure for the Second Stage Crystallizer is similar to the First Stage Crystallizer. The difference is that water is fed through the Anhydrous Reactor.

3.2 Emergency Wash-Out

The emergency wash-out procedure, which is primarily and emergency drain procedure, is the same as the First Stage Crystallizer.


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8 FLUID BED DRYING (PFD600-01)


Monohydrate crystals leaving the second stage centrifuges are fed with belt conveyor 520-CV-040 to dryer feed screw conveyor 600-SC-010. In this conveyor the damp crystals are mixed with dry crystals from the drying section of the fluid bed, supplied via dried product recycle airlock 600-AL-010 and bucket elevator 600-BE-010. The mixed crystals are further transported by dryer feed screw conveyor 600-SC-020 to dryer feed distributor 600-FD-010. Fluid bed dryer 600-FB-010 comprises three baffled compartments containing heat exchanger tube bundles. In the first compartment surface moisture is removed, and the monohydrate is heated to about 85 to 90°C. The first section is a well mixed deep bed for receiving and drying the wet feed material. Dehydration is not desired in this first compartment, as it results in a fragile, low hardness final product and can lead to excessive heat bundle scaling. In the second compartment the solids temperature is increased to 150°C, and dehydration is performed. The second section is for dehydration and has a plug flow design. In the third compartment ambient temperature fluidizing air and circulating water supplied from a cooling tower are used to reduce the product temperature to 80°C. Anhydrous product containing less than 0.1 % moisture will discharge through airlock 600-AL-040 to the dryer product conveyor 700-CV-010 feeding the screening. Fluidizing air will be indirectly steam heated to 180°C prior to delivery to the first two dryer compartments. Air for the first compartment is supplied by dryer air fan 600-FN-010, preheated with condensate in dryer air preheater 600-HX-010 and heated with steam in dryer air heater 600-HX-011. Air for the second compartment is supplied by dryer air fan 600-FN-020, preheated with condensate in dryer air preheater 600-HX-020 and heated with steam in dryer air heater 600-HX-021. The majority of the heat for drying and dehydration is supplied by the steam heated pipe bundles inside the fluid bed. The third compartment will receive ambient air from cooling air fan 600-FN-025. The majority of the cooling capacity is supplied by cooling water that flows through a pipe bundle in the cooling section. The dryer includes the integral baghouse 600-DC-010. The dust that originates from the drying and dehydration section is recovered in the baghouse and is returned directly to the dryer. About 3.5 t/h of dust removed from the cooling section end of the fluid bed dryer is removed separately from the dryer, transported by dryer fines discharge screw 600-SC-030 and recycled to the second stage centrate tank and to the second stage feed tank. This dust is discharged via dryer fines airlock 600-AL-030 to dryer dust hopper 600-BN-


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030. In this hopper the dust is mixed with air and sucked into dryer dust conveyor 600-CV-030, which is driven by second stage centrate. Dedusting air from the inlet of conveyor 700-CV-010 is connected to the dryer dust collector 600-DC-010. Induced draft fan 600-FN-030 will pull the exhaust air from the dryer through the baghouse for discharge to atmosphere. Condensate from the air heaters and the heat exchanger tube bundles is collected in fluid bed dryer condensate tank 600-TK-010, where it flashes to a pressure between 3 and 6 bar absolute. The resulting vapor is discharged into the low pressure steam header. The condensate is discharged via the air preheaters to the boiler feed water tank 900-TK-040, by means of the pressure inside 600-TK-010.


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8.2.1 Feed to static fluidbed dryer for pure soda ash plant (PID 600-01)

Via a chute, centrifuge cake from the crystallization section is fed to dryer feed screw conveyor1 600-SC-010. Part of the dried light ash is recycled from the drying section to this screw conveyor to lower the feed moisture content and to prevent fouling of the screw conveyors and the feed distributor 600-FD-010. The dry ash recycle is provided by airlock 600-AL-010 and bucket elevator 600-BE-010 that run at a fixed speed. Therefore the amount of recycle is fixed, and the ratio of dry crystals to the feed varies with the feed capacity. The mixed crystals are fed to dryer feed screw conveyor2 600-SC-020 that feeds the crystals to the dryer feed distributor 600-FD-010, which distributes the feed evenly over the width of the dryer. The speed of the feed distributor can be adjusted. After testing during commissioning and start-up this is set at an optimal value.

8.2.2 Static fluidbed dryer for pure soda ash plant (PID 600-02)

The mixed crystals are fed to the drying section of the fluid bed dryer. The temperature of the drying section is controlled by 600-TICSA-0101 which controls the steam flow to the steam tube bundles. The air flow through the distributor plate is essential for proper fluidization. The air flow rate is controlled (see P&ID 600-03). In the dehydration section the air flow rate is distributed over 2 segments. The air flow distribution can be adjusted with manual valves. The flow rate for each segment can be determined by use of the pressure drop indicators (600-PDI-0103/0104 and 600-PDI-0105/0106). The total pressure drop across the (clean) distribution plate and the bed is measured and this is a coarse indicator for the bed height and air flow rate in that section. A good indication for the performance of the first two sections of the fluid bed dryer, is the temperature of the soda ash leaving the dehydration section (600-TICSA-0102). Therefore this temperature is an important quality parameter. Cooling of dense soda ash is done partly by the ambient air (from cooling air fan 600-FN-025) required for fluidization and for the major part by circulating cooling water through the tube bundles in the third section of the unit. A correct air flow rate is important for proper fluidization and for proper de-dusting. The amount of air can be controlled with a manual valve, and the pressure drop of the bed (600-PDI-0107/0108) can be used as a measure for the flow rate.


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This cooler section is also used for separation of dust. Dust is entrained in the air to the filter bags and thus carried over beyond the fluid bed part of the unit. The hood of the dryer is operated at a pressure slightly below atmospheric. This is done for dust control (both from the dryer itself and for the rest of the plant). To maintain the required negative pressure in the hood of the dryer, a pressure control valve 600-PCV-0110 is installed in the suction line of dryer ID fan 600-FN-030. The dust entrained in the fluidization air is separated in dust collector 600-DC-010. Dust from the dryer and dehydration section is returned directly from where they are collected. Dust from cooling section is separately discharged by means of dryer fines screw conveyor 600-SC-030 and dryer fines airlock 600-AL-030 to the dryer dust hopper 600-BN-030. This dust discharge system runs at a fixed speed. The filter bags clean the air from the dryer to below the dust level allowed for environmental release to atmosphere. The dust level in the clean air is monitored with a dust detector (opacity measurement) and a broken bag detector is installed. To maintain an acceptable pressure drop across the filter the bags are automatically cleaned by pulsing with compressed air. This is carried out in cycles, a few rows at a time, triggered by a timer. The pressure drop is also monitored and at high pressure drop an alarm is generated so that the operator can start an additional cleaning cycle. Cooled dense ash is discharged from the dryer through dryer product discharge airlock 600-AL-040 to conveyor belt 700-CV-010. The airlock and conveyor run at fixed speed.

8.2.3 Air supply and air heating for static fluidbed dryer for pure soda ash plant (PID 600-03)

Steam (15 bar) is supplied to to air heaters 600-HX-011 and 600-HX-021 for heating fluidization air for drying and dehydration sections. The temperature of the hot air is controlled by the steam flow to the air heaters (600-TCV-0201/0202). The air heaters consist of of a preheating section and a heating section. In the preheating section cold air is heated with the condensate discharge from condensate tank 600-TK-010. Using this condensate air is heated to about 100°C and the condensate is cooled to about 80°C. In the heating section the preheated air is heated with steam to 180°C. The flow distribution of condensate to both preheaters can be adjusted with manual valves, in order to achieve equal the outlet condensate temperatures (600-TI-0203/0204). One of these manual valves should be fully opened. Fluizidization air for drying and dehydration sections is supplied by dryer air fans 600-FN-010 and 600-FN-020. The speed of these fans is controlled by flow meters downstream of the heater (600-FIC-0201/0202). Fluidization air for the cooling section is supplied by cooling air fan 600-FN-025 which runs at fixed speed. The amount of air can be adjusted with a manual valve, and the


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pressure drop of the bed (600-PDI-0107/0108) can be used as a measure for the flow rate.

8.2.4 Monohydrate dryer dust and condensate discharge (PID 600-04)

Dust transport Dust from 600-AL-030 falls into the dryer dust hopper (600-BN-030). A fixed flow of liquor is supplied by centrate pumps 520-PP-040/041. Solids and entrained air are sucked into the jet conveyor 600-CV-030 and transported to the second stage crystallization feed tank 520-TK-005 and to the centrate tank 520-TK-040. Supplying hot dryer dust to the liquor stream causes the liquor temperature to increase due to the sensible heat increase by introduction of hot dryer dust and the heat of dissolution. Condensate storage and discharge Condensate from the fluid bed and from the air heaters is collected and flashes from 15 bar to about 3 bar in 600-TK-010. The pressure in this flash vessel is controlled by 600-PIC-0302. Flash steam is discharged to the 3 bar steam header. Condensate from 600-TK-010 is used in the air pre-heaters and then discharged to boiler feed water tank 900-TK-040. The level in 600-TK-010 is controlled by 600-LICSA-0301.


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8.2.5 Setting list


600-FISA-0101 ton/h 24 LL TBD

L TBD

LL TBD

600-FI-0102 ton/h 14

600-FI-0103 ton/h 6

600-FI-0104 m3/h 75

600-FIC-0201 m3/h 30800

600-FIC-0202 m3/h 50500

600-HIC-0001 %

600-KIS-0101

600-LICSA-0301 % 50 H 90

L 20

LL 5

600-LA-0101 H TBD

600-LA-0102 H TBD

600-LICSA-0301 % 50 LL 5

L 20

H 90

LL 5

600-LI-0302 % 50

600-LSA-0303 mm H 200 3) H 200 3)

600-PIC-0110 mm H2O-g -10

600-PISA-0111 barg 14.5 LL TBD

L TBD

LL TBD

600-PI-0112 barg 14.5

600-PI-0113 barg 14.5

600-PI-0114 barg 4.5

600-PCV-0115 barg 4.5

600-PDI-0101 mm H2O 900 - 1050

600-PDI-0102 mm H2O 250 -300

600-PDI-0103 mm H2O 900 - 1050

600-PDI-0104 mm H2O 250 - 300

600-PDI-0105 mm H2O 900 - 1050

600-PDI-0106 mm H2O 250 - 300

600-PDI-0107 mm H2O 900 - 1050


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600-PDI-0108 mm H2O 250 - 300

600-PDISA-0109 mm H2O 125 - 150 H TBD H TBD

600-PI-0201 barg 14.5

600-PI-0202 barg 14.5

600-PI-0203 mm H2O-g 1285

600-PI-0204 mm H2O-g 1285

600-PI-0205 Barg

600-PDI-0201 (0206?) mm H2O 20

600-PDI-0202 (0207)?) mm H2O 20

600-PDI-0203 (0208?) mm H2O 20

600-PI-0301 Barg 2

600-PIC-0302 Barg 2

600-QIA-0101 mg/m3 <35 1) H 35 (Check)

mg/Nm3 <50 2) H 50

600-QIA-0104 mg/m3 <35 5) H 35 (Check)

<50 2) H 50

600-SSA-0001 TBD TBD L TBD L TBD

600-TICSA-0101 °C 90 H TBD

HH TBD

HH TBD

600-TICSA-0102 °C 150 H TBD

HH TBD

HH TBD

600-TIC-0103 °C 80

600-TISA-0104 °C 210 LL TBD

L TBD

LL TBD

600-TIA-0105 °C 90 H TBD

L TBD

600-TIA-0106 °C 80 H TBD

600-TI-0107 °C 30

600-TI-0108 °C 45

600-TIC-0201 °C 180

600-TIC-0202 °C 180

600-TI-0203 °C 85

600-TI-0204 °C 85

600-TI-0301 °C 200

600-TIA-0302 °C 99 H 101


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Instrument air purgerators l/h 4) 10

1) At 90°C and 0.95 bara

2) at 0°C and 1.013 bara

3) As measured from bottom weld line of cylindrical section

4) At upstream operating conditions

5) at 90°C and 0.945 bara (-50 mm H2O-g)


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8.3 Logic functions

The following table shows logic functions acting on equipment.


Start/

Running

condition

Switch/

Interlock

600-AL-040 Locally by

hand

Locally by

hand and

automatic

– Product conveyor running

700-CV-010

X


hand

Locally by

hand and

automatic

– Dryer dust shut-off gate

600-GA-030 is open

X

600-SC-030 Locally by

hand

Locally by

hand and

automatic

– Rotary valve 600-AL-030 is

running

– Dryer dust shut-off gate

600-GA-030 is open

X

X


hand

Locally by

hand and

automatic

– Product rotary valve 600-

AL-040 running

– Fines screw conveyor 600-

SC-030 running

– Feed distributor 600-FD-010

running

– Feed screw conveyor 600-

SC-020 running


SC-010 running

– Steam flow 600-FISA-0101

LL switch activated

– Steam temperature 600-

TISA-0104 LL switch

activated

– Steam pressure 600-PISA-

0104 LL switch activated

X

X

X

X

X

Stop

Stop

Stop

600-BE-010 Locally by

hand

Locally by

hand and

automatic

– Feed screw 600-SC-010

running


activated

X

Stop


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Start/

Running

condition

Switch/

Interlock


hand

Locally by

hand and

automatic

– Bucket elevator 600-BE-010

running


SC-020 running


SC-010 running


running

X

X

X

X


hand

Locally by

hand and

automatic

– Feed screw conveyor2 600-

SC-020 running

X


hand

Locally by

hand and

automatic


running

X

600-FD-010 Locally by

hand

Locally by

hand and

automatic

– None

600-FN-010 Automatic Automatic – Dryer-FN-030 running X



600-FN-030 Automatic Automatic – None

The following table shows automatic actions of valves. Valve Action Cause

600-TCV-0101 Close HH switch of 600-TICSA-0101 and 600-TIS-0105





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8.4 Start-up and shutdown of fluid bed dryer

8.4.1 Normal start-up (from empty bed)

The fluid bed is empty. The drying section will be filled with dry dense soda ash from bags. The soda ash will be fed to the dryer feed screw conveyor. Before starting check that: – There are no foreign materials in the fluid bed – Unit is dry from washout – All manholes, inspection covers and drain valves are closed Following utility systems have to be ready: – 15 bar steam supply – cooling water supply – boiler feed water tank 900-TK-040 ready to receive condensate – 3 bar steam header ready to receive flash steam – plant air and instrument air supply – electrical supply – condensate system (see procedure in section 8.6.1) – dust transport (see procedure in section 8.5.1) Provide 15 ton (300 bags 50 kg) of soda ash for filling up the drying section. 1 Open all manual dampers at air inlet of drying, dehydration and cooling section of

the fluid bed. 2 Close valves 600-TCV-0101/0102 at steam supply to heating coils 3 Close manual flaps between drying section and dehydration section 4 Close product outlet powder gate in the fluid bed outlet section 5 Start dryer ID fan 600-FN-030 with closed inlet damper and put 600-PIC-0110 on

automatic. (Overpressure on the dryer and dust collector must be avoided in order to prevent dust emission. Therefore, Dryer ID Fan 600-FN-030 has to be running before other fans are started)

6 Directly when 600-FN-030 is running, start dryer air fans 600-FN-010 and 020 at low speed and cooling air fan 600-FN-025 and put flow controllers 600-FICA-0201/0202 on automatic. Gradually increase the setpoint to the value according to the setting list.

7 Open instrument purgerators and set flowrate according to setting list 8 Open valve 600-PCV-0115 of plant air supply and activate air pulsation for cleaning

of dust filter


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9 Start feed distributor 600-FD-010 10 Start dryer feed screw conveyor 600-SC-020 11 Start dryer feed screw conveyor 600-SC-010 12 Start bucket elevator 600-BE-010 13 Start feeding soda ash from bags. 14 Observe 600-PDI-0101/01012. A fluidizing layer is now created in the drying section

of the bed. 15 When bed is filled up to a level that 600-PDI-0101 is approx. 500 mm WC, open

steam control valve 600-TCV-0101 gradually in manual mode with a small opening of 5 or 10% and put in automatic after temperature stabilization at 90°C (max 110°C) (ensure bypass over 600-TCV-0101 is closed).

16 Open steam supply 600-TICSA-0201 to air heater 600-HX-011 on manual such that 90°C bed temperature is reached and put on automatic at the corresponding setpoint of 600-TICSA-0201 (ensure bypass over 600-TCV-0201 is closed).

17 Open slide gate above 600-AL-010 manually 18 Start dried product recycle airlock 600-AL-010 and keep soda ash in circulation 19 Start 700-CV-010 20 Start 600-AL-040

Now unit is ready to receive wet feed and the calciner and crystallization section can be started. 21 Start 520-CV-040. 22 Adjust temperature setpoint of 600-TICSA-0201 as needed to keep the bed

temperature at 90°C. 23 Monitor bed height, and when 600-PDI-0101 exceeds 900 mmWC, the intermediate

powder gate between drying and dehydration section shall be manually opened. In this way the dry monohydrate enters the dehydration section of the bed

24 Put steam to dehydration section steam panel and air heater (600-TICSA-0102 and 600-TIC-0202) to automatic with setpoint of 180°C (ensure bypass over 600-TCV-0102/0202 is closed).

25 Monitor bed height, and when 600-PDI-0103 exceeds 900 mmWC, the intermediate powder gate between dehydration and cooling section shall be manually opened. In this way the dry soda ash enters the cooling section of the bed

26 Open isolation valves of cooling water and put 600-TIC-0103 in automatic mode with a setpoint of 80°C (ensure bypass over 600-TCV-0103 is closed).

27 Check temperature of the sections. The product temperature after the dehydration section (600-TICSA-0102) has to be above 150°C for required conversion. The product outlet temperature has to be 80°C or less.


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28 Check air flow rate in relation to bed height (600-PDI-0107/0108) Adjust with manual control valve if needed (information provided by vendor)

29 Take sample of product to check fluid bed dryer performance (moisture content, particle size distribution and bulk density)

8.4.2 Restart from standby

1 Start 520-CV-040 (steam supply to tube bundles (600-TICSA-0101/0102 will open automatically)

2 Monitor the bed heights (pressure drop transmitters) and open manual flaps between the sections

3 Check temperature of the sections. The product temperature after the dehydration section (600-TICSA-0102) has to be above 150°C for the required conversion. The product outlet temperature has to be 80°C or less.

4 Check air flow rate in relation to bed height (600-PDI-0107/0108) Adjust with manual control valve if needed (information provided by vendor)

5 Take sample of product to check fluid bed dryer performance (moisture content, particle size distribution and bulk density)

8.4.3 Shut down (empty fluid bed)

This procedure describes emptying the fluid bed and complete shut down, for washing down or maintenance activity. Equipment must be emptied completely when stopping for a longer period of time. Moisture inside the system and from migration from outside can cause lump and crust formation. It is assumed the liquor supply for dust removal remains operational. Even when the crystallization unit is on standby, it can still receive the amount of dust that is released during the emptying of the fluid bed. 1 Stop feed from crystallization section (520-CV-040) 2 Continue operation until the bed is empty as much as possible (open

600-HSV-0101and adjust manual flaps according to information from vendor). Monitor bed height with pressure drop indicators.

When bed, hoppers, screw conveyors etc. are empty, the unit can be stopped. 3 Close steam supply to the tube bundles (600-TCV-0101/0102) and to air heaters

(600-TCV-0201/0202) 4 Close cooling water supply to tube bundle (600-TCV-0103) 5 Stop 600-AL-010, 600-BE-010, 600-SC-010, 600-SC-020, 600-FD-010 6 Stop dust recycle system (see procedure in section 8.5.2) 7 Stop 600-AL-040 and 700-CV-010 8 Stop liquor supply from crystallization section (see second stage crystallization)


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9 Stop air fans 600-FN-010, 600-FN-020 and 600-FN-025 10 Stop dryer ID fan 600-FN-030 11 De-activate air pulsation system on filter bags 12 Shutdown condensate system (see procedure in section 8.6.2) 13 Keep instrument air purgerators running, unless required for the purpose of the

shutdown

8.4.4 Going to standby

1 Stop feed by stopping 520-CV-040 2 The steam supply to the pipe bundles (600-TCV-0101/0102) closes automatically 3 Close manual flaps between sections to keep bed height constant

8.5 Start-up and shutdown Dust transport


1 Dryer is not yet running, or is not supplying dust to 600-BN-030. 2 Check 600-GA-030 is closed 3 Check manual drain valve upstream of 600-CV-030 is closed. Check automated

drain valve 600-XSV-0301 is closed (reset on DCS) 4 Check 520-TK-040 has sufficient level, and centrifuge 520-CF-035/036 supply

sufficient liquor. 5 Check position of 520-LCV-0601 on P&ID 520-06 and the status of 520-TK-005. 6 Start selected pump (520-PP-040/041) 7 If pump is running well, then open 600-GA-030 8 Start dryer fines airlock 600-AL-030 9 Start dryer fines screw conveyor 600-SC-030

8.5.2 Normal shut-down

1 Stop dryer fines screw conveyor 600-SC-030 2 Stop dryer fines airlock 600-AL-030 3 Close 600-GA-030 (to prevent moisture entering the dust system) 4 If Crystallization section is kept running, then no further action required.

If crystallization section is stopped also, stop running pump 520-PP-040/041. 600-XSV-0301 will be opened automatically when the pump stops.

5 If crystallization is stopped and 520-PP-040/041 is stopped, then 600-XSV-0301 can stay open. It is closed by a reset action on DCS.


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8.6 Start-up Condensate collection and discharge


1 Make sure condensate can be received in 900-TK-040 2 Set 600-PCV-0302 in automatic mode, with set point according to the setting list. 3 If tank 600-TK-010 is empty, place 600-LICSA-0301 on manual. 4 When steam supply is open on the dryer, condensate will be collected in the tank. 5 If sufficient level is in the tank (approx 50%), open block valve and open

600-LCV-0301 by hand. Bring the level to the desired value (see setting list) and put controller in automatic mode (ensure bypass over 600-LCV-0301 is closed).

8.6.2 Normal shut down

1 If dryer is shut down place 600-LCV-0301 on manual and close it. 2 Take 600-PCV-0302 on manual and close it.


8.7.1 Periodic checks

1 Pressure drop of fluid bed: Drying, dehydration and cooling section have separate pressure drop indicators. Monitor the pressure drop periodically. If the pressure drop is too high (information provided by vendor), the fluid bed has to be cleaned.

2 Pressure drop of inlet air filters of air fans: The dryer air fans and the cooling air fan are provided with air filters. A pressure drop indicator is installed. Monitor the pressure drop periodically. If the pressure drop is too high (information provided by vendor), the filter has to be cleaned.

3 Plant inspection: • Frequent routine checks by field operator for visual inspection

4 During operation small lumps of soda ash will be accumulated at the fluid bed intermediate gates. In order to let these lumps escape, the gate must be quickly opened and closed. After start-up the frequency of this action is twice an hour, during normal operation 4 times per shift.

5 Check for fouling on feed screws and feed distributor, check rotating equipment, check dryer dust hopper air inlet openings are free (every 2 hours)

6 Take samples, see analytical manual


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8.7.2 Critical process conditions

Location Parameter Tag or sample Purpose; target or

setpoint

520-CV-040 Moisture content in dryer feed

from crystallization

Sample Performance of dryer; <

5 wt%

600-FB-010,

drying section

Bed temperature 600-TICSA-0101 Drying process;

90-100°C

600-FB-010,

dehydration

section

Bed temperature 600-TICSA-0102 Dehydration process;

135-150°C

600-FB-010,

cooling section

Bed temperature 600-TIC-0103 Cooling process;

80°C

600-FB-010,

drying section

Bed height 600-PDI-0101/0102 Drying process;

See setting list

600-FB-010,

dehydration

section

Bed height 600-PDI-

0103/0104/0105/0106

Dehydration process;

see setting list

600-FB-010,

cooling section

Bed height 600-PDI-0107/0108 Cooling process; see

setting list

700-CV-010 Product moisture content,

particle size distribution and

bulk density

Sample Quality parameter;

< 0.1 wt%

250 < D50 < 350 µm

> 1000 kg/m3


See Analytical manual.


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8.8.1 Cleaning of dryer

If the pressure drop over the fluid bed increases too much, the fluid bed has to be cleaned with water. Fouling is expected to occur mainly in the first section (drying section), especially in case the feed moisture content is too high. It is expected that this section will need to be cleaned every 3 months, depending on the control of the process. Before cleaning, the dryer has to be empty so must be shut down in accordance with procedure 8.4.3. 1 Open inspection openings and drains. 2 Proceed with cleaning operation (see section 8.8.5) 3 After cleaning, drain the unit well. After draining the unit has to be dried 4 Start dryer ID fan 600-FN-030 and put 600-PIC-0110 on automatic 5 Directly when 600-FN-030 is running, start dryer air fans 600-FN-010 and 020 and

cooling air fan 600-FN-025 and put flow controllers 600-FICA-0201/0202 on automatic.

6 Start-up condensate system (see procedure in section 8.6.1) 7 Turn on the steam supply to air heaters with a setpoint of 70°C After some time the unit can be restarted (proceed with item 6 of procedure 8.3.1) 8 Make sure purgerators are running and flow rate is according setting list 9 Proceed with item 6 of procedure 8.3.1

8.8.2 Too low liquor feed to 520-TK-040

If there is no or low feed from the centrifuges to 520-TK-040, then the temperature will increase in 520-TK-040. The return temperature to 520-TK-040 is monitored with 600-TIA-0302. When the temperature is too high (see setting list), an alarm is generated, and the cause of the high temperature has to be investigated or otherwise the dust supply to the circuit has to be stopped. When there is no feed from the centrifuges, the flow of cake to the dryer will also stop.


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8.8.3 Pump failure of 520-PP-040/041

If one of the two pumps fail the following automated responses are activated: – 600-GA-030 is closed – 600-XSV-0301 is opened. In this way liquor can not enter the dryer system and will drain out of bin 600-BN-030. Before restart, it has to be verified that the bin 600-BN-030 is empty of liquid and dry.

8.8.4 Dust transport

600-GA-030 is closed when 600-LSA-0303 detects high level and when 520-PP-040 and 520-PP-041 are out of operation (so when flow to 600-CV-030 stops). 600-GA-030 can be opened by the operator when: – high level 600-LSA-0303 not activated – 520-PP-040 or 520-PP-041 in operation When both 520-PP-040 and 520-PP-041 are out of operation 600-GA-030 is closed and at the same time 600-XSV-0301 is opened. Valve 600-XSV-0301 has to be closed by the operator (reset action on DCS required). Supplying hot dryer dust to the liquor stream causes the liquor temperature to increase due to the sensible heat increase by introduction of hot dryer dust and the heat of dissolution. Supplying hot dryer dust to the liquor stream causes the liquor temperature to increase due to the sensible heat increase by introduction of hot dryer dust and the heat of dissolution. Therefore the return temperature of the liquor is monitored with 600-TIA-0302. When the temperature is too high (see setting list), an alarm is generated, and the cause of the high temperature has to be investigated or otherwise dust bleed has to be stopped.


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8.8.5 Washout procedure of fluid bed dryer

Operation procedure for Fluid Bed Dryer Cooler for Pure Soda ash plant Document No. MSC/CL/002, Rev.0 Customer: Magadi Soda Company Limited, Kenya DT: 22-2-2005

L&T-NIRO Ltd., 101 GIDC, Ranoli, Baroda – 391 350 Page 1 of 2

WASHING PROCEDURE

Wash-up of the fluid bed plant

It is expected that the fluid bed can be operated continuously for a longer

period. However it is recommended to make some short inspections during the

operation period while feed & fans are stopped.

After a running period of approximately 3 months the fluid bed should be

evacuated for product and inspected. Washing of steam tubes may be

necessary. In practice this stop typical have duration of 3 shifts.

Once in a year long overhaul shut down should be performed. In addition to

periodic inspection and washing we advice to pull out 1 or 2 stream bundles in

the drying as well as the calcining section. This will allow a walk in on the gill

plate for a closer look of this as well as inspection of the steam tubes.

For the pulling of steam bundles a set of mobile trolley to be placed in

extension to the internal rail in order to support the bundle in the outside

position.

Inspection of the plant is mainly a question of inspecting the plant interior due

to possible problems with the performance of the plant. It is absolutely

essential to have prior permission from concerned in-charge.

Note: Never enter the plant interior in case there is no person

available to supervise from the outside.

After washing it is recommended to let the system dry out before feeding is

started.



Washing procedure

1. Shut-down the plant as described the steps in the operation procedure

(document No. MSC/CL/001, Rev.0)

2. Open the blind flange provided at the bottom of plenum chamber of drying,

dehydrating & cooling section of fluid bed.

3. Open all manholes & inspection covers of fluid bed & dust collector

manually.

4. All manual valves in the cooling water line of cooling coils for cooling

section of fluid bed are closed.

5. The manual isolation valve at compressed air header at bag filter should be

closed.

6. Steam supply line to the fluid bed drying & dehydration section of fluid bed

are isolated by providing blind at the header.

7. Close valves TCV 0101 & TCV 0102 in manual mode at steam supply line to

heating coils of drying section & dehydration section. All isolation & bypass

valves of steam line supplied to the heating coils of drying & dehydration

section are manually closed.

8. The upstream & downstream system of the fluid bed drying system is

isolated.

9. All air dampers at air inlet of drying, dehydrating & cooling section of fluid

bed are manually closed.



10.Open intermediate powder gate in the fluid bed from drying to dehydration

section & from dehydration to cooling section.

11.Keep open the slide gate valve above AL-010.

12.Disconnect the heating coils with steam & condensate piping. Place mobile

trolley for the pulling of steam bundles, in extension to the internal rail in

order to support the bundle in the outside position.

13.Pull out heating coil & clean it manually by water jet. Clean all other

heating coils in same manner.

14.Connect flexible water hose at the screw feed (SC-010) & wash the screw

feed. Water should flow through the rotary distributor (SC-020). The feed

screw & rotary distributor (SC-020) may be started during washing.

15.Washing of fines screw (SC-030) & product outlet box can be done by

spraying water from the manhole provided at the product outlet hopper.

∗ ∗ ∗ ∗ ∗ ∗


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9 EMERGENCY SITUATIONS

9.1 Power Failure

During limited power being available to the plant, the power management system (PMS) automatically shuts down certain sections to allow sections with a higher priority to continue operation, depending on the severity of the power failure. The order of priority (highest first) is as follows: – Critical drives: items of equipment that need to be maintained in a safe mode of

operation and to ensure ease of start up after failure of the electrical power supply. – Essential drives: All other items of the pure ash plant that are needed for continuous

operation, excluding the majority of the washery area – Non essential drives: Majority of the new washery area Applying the above logics provides the following response upon different levels of power failure: – Level 1 failure: all non-essential drives are stopped, essential drives and critical drives

remain running – Level 2 failure: all non-essential drives and essential drives are stopped, critical drives

remain running – Level 3 failure (total power failure): all drives are stopped, incl. all utilities The segregation of power supply gives the following general shut-down sequence: In case of level 1 failure, the washery will be shut down (non essential drives). The roller mill can be fed from CRS stockpile and so the calciner, crystallization and drying sections can continue at normal operating capacity (essential drives). In case of larger shortage of power (level 2), the essential drives are stopped as well, so the whole plant is basically shut down however, critical drives remain running. This is especially important to prevent long recovery time because of solids settling and plugging in critical vessels. Therefore the agitators in tanks (incl. settlers and crystallizers) with high concentrated slurries are critical drives. Furthermore the utility supply is classified critical for purge water on seals, steam tracing of anhydrous lines and hot water for flushing. In case of total power failure (level 3), all electrical drives including utilities are stopped. A list of the classification of the drives is provided under separate cover.

9.1.1 Consequences for the washery section 200

Level 1 failure:


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Only non-essential drives are stopped and the plant continues to run (with some disturbances, see section 5.7.6), except the washery section. CRS is supplied to the mill from the CRS stockpile. Liquor from the dredge continues to be supplied to the ESP conveying system and crystallization vent condenser after an interruption to make the supply line from the dredge free of solids. When the supply line is free of solids the liquor will be diverted to 200-TK-010 (pumps 200-PP-010/011/012 keep running). The liquor supply to the boiler scrubber is stopped (200-PP-060/061 is stopped). Level 2: Essential drives are shut-down as well and the whole plant is shut down. For the washery now the liquor supply to 400 and 500 section is stopped, as well as the CRS conveying to the mill. Only the critical drives remain running. Level 3: Critical drives (agitators) are stopped. Note: Of the sections that are stopped as a consequence of an electrical power failure, the signals to the solenoid valves of all air operated control valves and on/off valves is removed, so all valves go to the fail safe position.

9.1.2 Consequences for calciner unit 400

For the combustion chamber 400-FU-050 additional shut down measures are taken. During normal operating conditions the combustion chamber is cooled with combustion air and dilution air. If one or both of these stream fail, additional measures are taken to prevent mechanical damage due to high temperature. This can be achieved by using cooling air fan 400-FN-054 or with steam. Level 1 failure: no consequences Level 2 failure The calciner unit shuts down, except the cooling air fan 400-FN-054 The following responses are activated: – Actions as described in “Local emergency stop command”, see section 1.3 of FFEM,

which stops all equipment – All solenoids are deactivated, a/o fuel oil feed is stopped – The cooling air fan 400-FN-054 is started (when the combustion air fan 400-FN-050 or

dilution air fan 400-FN-035 is not running and the air heater outlet temperature 400-TISA-0468 is > 200°C) and valves 400-XSV-0470/0471 are opened. Emergency stack valve 400-XSV-0472 is opened because ESP ID fan 400-FN-030 is stopped (see FFEM section 2.5)


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Note: Content of cyclone 400-CY-060 is not dumped Level 3 failure: All drives are stopped including the cooling air fan. In this case cooling of the combustion chamber is provided by steam valves that fail to the appropriate positions. The Following responses are activated: – Actions as described in “Local emergency stop command”, see section 1.3 of FFEM,

which stops all equipment – All air operated valves travel to the defined failure positions:

• Fuel oil feed is stopped • Emergency vent stack opens (400-XSV-0472) • Steam supply fails open (400-XSV-0425), valve 400-XSV-0426 maintains its last

position which is open during normal operation. Valve 400-XSV-0426 closes when refractory temperature 400-TIS-0469 is < 450°C

Note: Content of cyclone 400-CY-060 is not dumped

9.1.3 Consequences for dumptank 400

Level 1 and 2 failure: No consequences. Level 3 failure: Diverter 400-GA-060 stays in the direction of the dumptank, if a power failure is initiated after dumping has started. Process water supply is stopped and a dust emission may occur. Prior to the dumping of solids, water is present in the tank at a level of 1 m which serves to cool down the dumped solids. Since also production is stopped and the air cannons, vibrators and airlock 400-AL-060 stop, no further product is transferred to the dump tank.

9.1.4 Consequences for Dust transport 400

Level 1 failure: no consequences. Level 2 failure: The calciner unit shuts down, the dust supply will stop, and process liquor supply will stop. The following automated response is activated: – 400-XSV-1401 will open. In this case 400-GA-041 cannot be closed. Before restart, it has to be verified that the bin 400-BN-040 is empty of liquid and dry.


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9.1.5 Consequences for Crystallization section

Level 1 failure: no consequences. Level 2 failure: The electrical drives are stopped, except the critical drives (agitators etc.). Centrifuges and lines have to be flushed. If this power outage continues then slurry from the elutriator has to be drained. Level 3 failure: Critical drives are also stopped, including purge water supply to the pumps. Lines cannot be flushed and may become blocked.

9.1.6 Dust transport 600

Level 1 failure: No consequences Level 2 failure: The fluid bed dryer has the same electrical priority as the crystallization unit. The dust supply will stop as well as the liquor supply. The following automated responses are activated: – 600-XSV-0301 will open. In this case 600-GA-030 can not be closed. Before restart, it has to be verified that the bin 600-BN-030 is empty of liquid and dry.

9.1.7 Steam boiler

Level 1 failure: Soda ash Plant remains in operation, however, no more liquor supply from washery to boiler scrubber. The hold-up in the scrubber tank is sufficient for 1 hour of operation. Provide make-up to boiler scrubber from other source.

9.2 Process water Failure

9.2.1 Consequences for the washery section 200

The process water is used for washing the centrifuge cake in 200-CF-070/71. Therefore, when a failure in the process water supply occurs, the centrifuges may continue operation. The CRS, however, will not have the required purity. In practice, the higher NaCl can probably be compensated by allowing more bleed in first stage crystallization section. If this is not the case then the slurry from the classifier will have to be diverted towards stockpile 200-ZC-030 (operator action). The roller mill will then have to be fed from CRS


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stockpile and the washery has to be put on standby. In principal solids from the dredgeing section can continue.

9.2.2 Consequences for calciner section

Depending on the moisture content of the CRS feed, the roller mill can run without the water spray. If CRS is too dry, the calciner section has to go on standby.

9.2.3 Consequences for Dumptank 400

Failure of process water will cause a dust emission during dumping. The feed diverter 400-GA-060 automatically diverts towards 400-AL-065 and the dust emission is stopped.

9.2.4 Consequences for first crystallization section

The main consequence of this failure is: – lack of washing on the centrifuges 510-CF-035/36 and the produced crystals do not

have the required purity – lack of cold process water to scrubber sprayers and lack of cooling of the liquor

discharge of scrubber 510-DC-015 Furthermore, for longer time scales, no more dilution of process liquor stream and dissolving of the monohydrate in the deaerator takes place. The crystallization section has to be put on standby and only a limited amount of hot process water is available for flushing of lines.

9.2.5 Consequences for second crystallization section

Main consequences of this failure is a that a limited amount of hot water is available for washing on 520-CF-035/36. Also cooling water on the vacuum pump fails, therefore vacuum pumps have to stop. If process water is interrupted during regeneration of the filter, the regeneration cycle cannot be completed The second stage crystallization section has to be put on standby but only limited amount of hot process water is available for flushing of lines.

9.2.6 Consequences for cooling water system

No more cooling water make-up. If level in cooling tower is too low, it will shut down, see section 9.4.


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9.3 Purge water failure

The purge water pumps are therefore provided with automatic changeover and the purge water pump drives are classified as critical in case of electrical power failure. Failure of both pumps gives immediate damage to pump seals. Also instrument readings will deviate. In case of a short stoppage of purge water (shorter than 1 minute, e.g. short pump failure) the plant can keep running. If this happens, some intervals with increased flow of purge water are needed after resuming normal purge water flow again, in order to clean the pump seals. If purgewater is not available for more than 1 minute, the plant has to be shut down, because otherwise the slurry pump seals are damaged and product will leak through the seals. With respect to shutdown procedure, all pumps with purge water on the seals have to stop as fast as possible. Most pumps can be stopped right away. For some pumps, a precaution has to be taken: 1 200-PP-011/012: first stop dust supply to 400-BN-040, then stop 200-PP-011/012 2 520-PP-040/041: first stop dust supply to 600-BN-030, then stop 520-PP-040/041 3 510-PP-010/011: first divert feed diverter valve 400-GA-060 to dumptank, then stop

510-PP-010/011 Before restart, pump seals and instruments have to be flushed well and crystallizer agitators have to be checked. Seals may have to be replaced, requiring emptying of the crystallizers.

9.4 Cooling water failure

Air compressors will fail as a consequence of cooling water failure. If possible, put process water on the air compressors. If this is not possible, then the plant is shut down because of lack of instrument and plant air, see section 9.7 Cooling water failure results in a shut down of the calciner section (Emergency shutdown, see FFEM section 1.3). Also the fluid bed dryer has to be put on standby.

9.5 Steam failure

Steam failure has the following consequences: – the calciner section has to be shut down (Emergency shutdown, see FFEM section 1.3)


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– second stage anhydrous reactor has to shutdown so this section goes on standby – fluid bed dryer has to stop and be put on standby Close manual isolation valves of steam supply to users. In most cases steam hold-up in boiler and headers will provide heat tracing on anhydrous slurry lines.

9.6 Dredge feed failure

When a complete failure of supply from the dredge and emergency lke liquor pump occurs, the washery will be shut down, and as a consequence, the ESP fines conveying system fails as does the second stage crystallization section goes on stand-by, because of lack of cooling liquor on the second stage vent condenser. Also the liquor supply to the boiler scrubber has to be stopped after some time. When only the solids supply fails, there are no consequences for the calciner, crystallization and washery sections. The dry reclaim procedure has to be applied (see section 5.7.2).

9.7 Instrument air and plant air failure

Instrument air and plant air have a common supply line. If the pressure in the main air line drops, the supply of plant air stops (900-PCV-1111 closes). When the pressure drops further, air driven control valves and on/off valves will open, close or remain in their last position, as presented on the P&ID’s. No control is possible and the plant has to be shut down. The air receivers have a buffer capacity of 2 minutes so if an air compressor can be restarted within this time, then a plant shutdown is avoided. Otherwise, the low pressure switch is activated and all solenoids are de-activated. Now all valves go to the fail safe position, the calciner section is shutdown (see below) and all other electrical equipment is stopped automatically. If plant air pressure is low, without any failures of the compressors, then the consumption is too high. The users that have this high demand have to be located and the air flow reduced. Calciner unit 400: The unit is shutdown according the emergency shutdown procedure FFEM 1.3. Following responses are activated: – The unit is shutdown (emergency stop section 1.3, FFEM) – Content of cyclone 400-CY-060 is not dumped


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– The cooling air fan 400-FN-054 is started – All air operated valves to go the defined failure positions:

• Fuel oil feed is stopped • Emergency vent stack opens (400-XSV-0472) • Steam supply fails open (400-XSV-0425), valve 400-XSV-0426 maintains its last

position, which is open during normal operation. Valve 400-XSV-0426 remains open when refractory temperature 400-TIS0469 is < 450°C

Fluid bed dryer Put the fluid bed dryer on standby: – Stop feed conveyor 520-CV-040. – All valves go to fail safe position (steam valves close, cooling water valve will open,

and inlet damper of 600-FN-030 says put). – The dust conveying system of 600-BN-030 stops as a consequence of the air failure.

Some dust will accumulate.

9.8 Guar solution failure

When a short failure occurs (e.g switching between pumps), the washery and crystallization operations can be continued normally. In the case of longer failures, a build-up of impurities in the washery and crystallization is possible resulting in off-spec product. This means the washery and crystallization sections have to be shut down.

9.9 Anti foam solution failure in washery section

Failure of supply of anti foam can cause excessive foaming. In this case the washery has to be put on standby or even shut down if foaming is excessive. Liquor supply to 520-TK-005 and 520-TK-010 has to continue in order to be able to keep the rest of the plant running.


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10 COMMISSIONING AND INTIAL START-UP

10.1 Washery

During commissioning and 1st startup a number of process characteristics have to be learned. At several positions in the washery section foaming can potentially occur. Antifoam supply is provided on the CRS centrate tank 200-TK-070 and is transferred from there to other parts of the washery.

10.2 Dryer dust transport 400

During 1st start-up it has to be observed if foaming occurs. Tests for commissioning: 1 Install pressure indicators (0 to 5 barg) upstream and downstream of 400-CV-040.

Check pressure drop with running pump (differential pressure is approx. 2.8 bar). Pump discharge pressure is approx. 5.1 barg.

2 Start pump 200-PP-012 and watch inside 400-BN-040: check if liquid runs back into 400-BN-040 initially. Determine if a waiting time is required to dry the bin internally.

3 Stop pump 200-PP-012. Now 400-GA-040 closes and automated drain valve 400-XSV-1401 is opened. Watch inside 400-BN-040 and check if liquid is running back into 400-BN-040. Determine if a special procedure is required for drying.

10.3 Crystallization

Amount of process water needed in precoat liquor.

10.4 Dryer

The speed of the feed distributor can be adjusted (600-HIC-0001). During commissioning and start-up this value is set at an optimal value. During start-up the underflow outlet is kept shut to ensure that the first section remains full during build-up of the bed in the rest of the unit. The operating value for the temperature has to be established in practice. By varying the setpoint for 600-TICSA-0102 and plotting the corresponding moisture content of the final dense ash product, the required bed temperature can be established for the final product moisture specification. In advance, a set value for 600-TICSA-0102 of between 130 and 140°C is to be expected.


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10.5 Dryer dust transport 600

Tests for commissioning: 1 Install pressure indicators (0 to 5 barg) upstream and downstream of 600-CV-030.

Check pressure drop with running pump (differential pressure is approx. 3.4 bar). Pump discharge pressure is approx. 5.7 barg.

2 Start pump and watch inside 600-BN-030: check if liquid runs back into 600-BN-030 initially. Determine if a waiting time is required to dry the bin internally.

3 Stop pump 600-BN-030. Now 600-GA-030 closes, and automated drain valve 600-XSV-0301 is opened. Watch inside 600-BN-030 and check if liquid is running back into 600-BN-030. Determine if a special procedure is required for drying.

10.6 Condensate tank 600-TK-010

1 Safety valve 600-SV-0301 will blow-off in case the dryer produces more LP steam than is used by low pressure steam consumers

2 Check condensate discharge capacity


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11 MAINTENANCE

11.1 Maintenance inspection

Maintenance inspection is required for a number of critical items. The frequency of this inspection is once a day. Below a list of items that have to be checked on each routine tour: 1 Pumps and agitators (vibration, noise) 2 Belt conveyors (tension, vibration, noise) If a spare pump remains idle for a long period of time, it is recommended that the shaft be rotated by a quarter turn on a weekly basis. This ensures that static loads and vibrations are shared equally over all rolling elements, thus avoiding localized deterioration.

11.2 Fluid bed dryer inspection

It is expected that the fluid bed dryer can operate continuously for three months or more. After running for 3 months the fluid bed dryer should be emptied of product and inspected. The washing of the steam tubes externally may be necessary. After washing it is recommended to let the system dry out before feed is re-established. In practice this stoppage has a duration of 3 shifts. Once per a year a maintenance shut down should be performed. In addition to normal inspection and washing 1 or 2 steam bundles may be removed in the drying and the dehydration sections. This will allow an entry into the vessel for a more detailed inspection (a/o inspect the gill plate). Special equipment is provided which allows the tube bundles to be withdrawn, held and replaced. Inspection of the plant is mainly a question of inspecting the plant interior due to possible problems with the performance of the plant. In case of internal inspection, it is absolutely essential to have prior permission from person in charge (confined space entry procedure). Note: There shall always be a person supervising from outside when entering the unit

interior.


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11.3 Pump and agitator seals

Gland seals of the bottom mounted agitators and of most of the pumps are provided with purge water. The purpose is to keep the gland packing free from crystals in between the packing and the shaft. The supply of purge water is controlled with a purgerator with flow indication. In case the seal tightening is not correct (no dripping of water, or too much water coming from the seal), maintenance attention is required.

11.4 Inspection of tanks

Periodic inspections of tanks are required: – Items to check are wind and water line scaling on wall and agitator shaft and scaling in

vent outlets which will have to be cleaned as required. – Corrosion – Fixation of internals – Instrument connections and probes

Appendix 1 Basic Operating Manual doc. no. 2.187.735 -

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APPENDIX 1: TROUBLE SHOOTING TABLE FOR 200-PP-050/051, 510-PP-050/051, 520-PP-050/051


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APPENDIX 2: TROUBLESHOOTING TABLE WARMAN PUMPS


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APPENDIX 3: LIST OF ACRONYMS

Abbreviation Explanation

CRS Crushed Refined Soda

DCS Distributed Control System

(for process control)

ESP Electrostatic Precipitator

FLD Functional Logical Diagram

MCC Motor Control Centre

PFD Process Flow Diagram

P&ID Piping and Instrumentation

Diagram

PMS Power Management System

UPS Uninterrupted Power Supply


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APPENDIX 4: UNIT SYSTEM

The units used are according to the SI system, related units as stated below may be used. Pressure : Pa, bar, mbar *) Temperature : °C Rate of flow : Nm3/h, m3/h, kg/h, t/h *) Length : mm, m, km *) Area : m2 Volume : m3 Quantity of heat : J, kJ, MJ, GJ *) Density : kg/m3 *) Power/heat flow : W, kW, MW, GJ/h *) Specific heat : kJ/kg.°C *) Viscosity : mPa.s *) Voltage : V, kV, mV *) Electrical current : A, mA *) Power consumption : kWh, MWh *) Time : s, h Mass : kg, ton *) Thermal conductivity : kW/m.°C *) Electrical conductivity : Ω-1m-1, µS/cm *) *) µ = micro = 10-6 m = milli = 10-3 k = kilo = 103 M = mega = 106 G = giga = 109

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