CO Boiler Manual(VP MA 008 028_R0) 1

7/29/2019 CO Boiler Manual(VP MA 008 028_R0) 1

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1600-ME-003 A/B

OPERATING AND MAINTENANCE MANUAL

CO BOILERS

0 RD HL HL LD

REV. PRPD CHKD REVD APPRD APPRD

Document No. 5578-E2-VP-MA-008-028( HPC Doc. No.: 0000-FJ-901 )

COMPANY

Project No.5578-E2-1600-PO-MA-008P/O No.5578

DATE DESCRIPTION

CO BOILER PACKAGE

1600-ME-003 A/B

RUWAIS REFINERY EXPANSION PROJECT

PACKAGE #2 RFCC AND ASSOCIATED REFINING UNITS

12 JUL.12 Issued for Approval

PROJECT :

VENDOR :

EQUIPMENT :


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TAKREER, Ruwais Refinery, Abu Dhabi

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CO BOILERS

1600-ME-003 A/B

0 12/07/2012 First issue RD HL HL

Rev. Date Description By Checked Approved


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SUMMARY

1. FOREWORD ............................................................... ................................................................... .............................. 41.1. DOCUMENTATION ................................................................................................................................................. 41.2. ABBREVIATIONS .................................................................................................................................................... 52. CO BOILER DESIGN BASE ........................................................................................ ........................................ 52.1. SYSTEM DESCRIPTION ........................................................................................................................................... 62.2. FUELS.................................................................................................................................................................... 62.3. BURNERS............................................................................................................................................................... 72.4. WASTE HEAT BOILERTUBE CLEANING SYSTEM................................................................................................... 73. BOILER PACKAGE CONFORMITY FOR PRE-COMMISSIONING INSPECTION ................................. 83.1. INTRODUCTION...................................................................................................................................................... 83.2. STRUCTURAL PARTS ............................................................................................................................................. 83.3. DAMPERS (AND/ORINLET GUIDE VANES) .......................................................... ................................................... 83.4. PRESSURE PARTS (COILS) ..................................................................................................................................... 93.5. REFRACTORY SETTING .......................................................................................................................................... 93.6. PILOT BURNERS .................................................................................................................................................... 93.7. BURNERS............................................................................................................................................................. 103.8. PIPING ................................................................................................................................................................. 103.9. INSTRUMENTATION ............................................................................................................................................. 113.10. STEAM DRUM...................................................................................................................................................... 123.11. FAN,MOTORS AND TURBINES............................................................................................................................. 123.12. SCRSYSTEM....................................................................................................................................................... 133.13. GENERAL ............................................................................................................................................................ 134. COIL AND PIPING PRE-COMMISSIONING ................................................................ ................................. 144.1. COIL AND PIPING CLEANING ............................................................................................................................... 144.2. FUEL PIPING TIGHTNESS TEST............................................................................................................................. 164.3. POST-FLUSHING ACTIVITIES ............................................................................................................................... 165. INITIAL START-UP .......................................................... ................................................................. ................. 175.1. INTRODUCTION :BEFORE START-UP ................................................................................................................... 175.2. GENERAL RECOMMENDATION DURING START-UP ............................................................................................... 175.3. HAZARDOUS OPERATION .................................................................................................................................... 185.4. LINE PURGING..................................................................................................................................................... 195.5. LINES GAS-IN. ......................................................... ................................................................ ............................ 195.6. LEAK-THROUGH CHECKING ................................................................................................................................ 195.7. COBOILERPURGING .......................................................................................................................................... 206. REFRACTORY LINING DRY-OUT ............................................................... .................................................. 216.1. INTRODUCTION.................................................................................................................................................... 216.2. DRY-OUT PROCEDURE......................................................................................................................................... 217. STEAM DRUM BOILING-OUT......................................................................................................................... 258. CO BOILER START-UP ............................................................... .............................................................. ........ 278.1. INTRODUCTION.................................................................................................................................................... 278.2. START-UP PROCEDURE ........................................................................................................................................ 278.3. COBOILERCAPACITY CHANGES ........................................................................................................................ 288.4. SCRSYSTEM ....................................................................................................................................................... 299. SHUTDOWN ......................................................... .................................................................... ............................ 31


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9.1. PLANNED SHUTDOWN ......................................................................................................................................... 319.2. TAKING BURNERS OUT OF OPERATION ............................................................................................................... 319.3. EMERGENCY SHUT-DOWN ................................................................................................................................... 329.4. INTERNAL BOILERPRESERVATION ...................................................................................................................... 3310. NORMAL OPERATION ....................................................................... .............................................................. 3510.1. OPERATING VARIABLES ...................................................................................................................................... 3510.2. OPERATING PARAMETERS ................................................................................................................................... 3610.3. TROUBLE SHOOTING............................................................................................................................................ 4011. PREVENTIVE MAINTENANCE ............................................................................................................... ........ 4111.1. INTRODUCTION.................................................................................................................................................... 4111.2. COBOILERPERFORMANCE INSPECTION ............................................................................................................. 4111.3. STRUCTURAL SUPPORTS...................................................................................................................................... 4111.4. EXTERNAL INSPECTION....................................................................................................................................... 4211.5. PROCESS COILS ................................................................................................................................................... 4211.6. TUBE SUPPORTS .................................................................................................................................................. 4311.7. REFRACTORY SETTING ........................................................................................................................................ 4311.8. BURNERS............................................................................................................................................................. 4411.9. INSTRUMENTATION ............................................................................................................................................. 4511.10. FAN,MOTORS AND TURBINES ........................................................................................................................ 4511.11. SOOTBLOWERS AND CONTROL SYSTEM.......................................................................................................... 4511.12. FLUE GAS DUCTING ....................................................................................................................................... 4511.13. AIRDUCTING ................................................................................................................................................. 4511.14. VALVES .......................................................................................................................................................... 4511.15. VESSELS AND FILTERS.................................................................................................................................... 4611.16. PIPING ............................................................................................................................................................ 4611.17. INSPECTION OF CATALYST AND HOUSING INTERIOR...................................................................................... 4711.18. NOTES ON HANDLING CATALYST ................................................................................................................... 4711.19. DISPOSAL OF USED CATALYST ....................................................................................................................... 47


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1. FOREWORD

The purpose of this manual is to provide operating personnel with a reference source and guideduring start-up and long term operation of the CO boilers.

The activities described in this document refer to the following stages of the boiler lifetime:

Pre-commissioning, preparation of the unit to the start-up.

Dry-out of the refractory setting.

Operation of the CO boilers, including start-up and shutdown.

Maintenance

This document shall be referred in conjunction with vendor installation and operating manuals forbought out items like SCR catalyst, Adblue System, Fan, Motors, Turbines, Burners, Sootblowers,etc.

However, this document will not replace the knowledge and experience of the operators. Theyshould be thoroughly familiar with the control of a boiler. Furthermore, this manual should notreplace the instructions of the factory, in particular safety instructions.

The operator should be aware of the potential danger of this equipment, in order to act always inthe way of safety.

1.1. Documentation

In addition to this manual, the operator should be familiar with the following documents:

Piping and Instrumentation Diagrams

16A0-FD-801 : CO Boiler Steam generator 1/2

16A0-FD-802 : CO Boiler Steam generator 2/2

16A0-FD-803 : Steam generator sootblowers arrangement

16A0-FD-804 : Steam supply for Steam generator sootblowers

16A0-FD-805 : Air distribution for Steam generator sootblowers

16A0-FD-806 : CO Boiler Combustor fuel skid

16A0-FD-807 : CO Boiler Combustor

16A0-FD-808 : SCR for CO Boiler - Ammonia tank

16A0-FD-809 : SCR for CO Boiler - Ammonia pump skid

16A0-FD-810 : SCR for CO Boiler - Ammonia vaporization skid 1/2

16A0-FD-811 : SCR for CO Boiler AIG and SCR reactor

16A0-FD-812 : Economizer sootblowers arrangement

16A0-FD-813 : Steam supply for Economizer sootblowers

16A0-FD-814 : Air distribution for Economizer sootblowers

16A0-FD-815 : SCR for CO Boiler - sootblowers

16A0-FD-816 : Instrument and plant air supply

16A0-FD-818 : Utilities cooling water


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16A0-FD-819 : SCR for CO Boiler Ammonia vaporization skid 2/2

Process Data Sheets

16A2-FJ-001: CO BOILER 1600-ME-003 datasheet

16A3-FJ-002: SCR system datasheet

16A1-FJ-201: Burner and combustor datasheet

16A2-FJ-301: Steam drum datasheet

16A1-FJ-302: Fuel gas knockout drum datasheet

16A2-FJ-701: Sootblower datasheet 16A3-FJ-701: SCR sootblower datasheet

16A1-FJ-721: FD fan datasheet

16A3-FJ-721: Dilution air blower datasheet

16A1-FJ-723: Lubrification oil system datasheet

16A1-FJ-781: Special purpose steam turbine datasheet

Refer to Project Master Document List for all applicable HPC documents and drawings

Operating and Maintenance Manual f rom Equipment Manufacturers

Please refer to Vendor Data Book.

1.2. Abbreviations

ESD : Emergency Shut-Down MP/LP : Medium/Low Pressure

HC : Hydro Carbon MW/LW : Medium Weight / Low Weight

HR : Heat Release P&ID : Piping & Instrumentation Diagram

K.O. : Knock-Out (drum) PLC : Programmed Logic Controller

LHV : Lower Heating Value SCR : Selective Catalytic Reduction

HHV : Higher Heating Value

2. CO BOILER DESIGN BASE

This manual covers the preparation to start-up (precommissioning), the operation and themaintenance for the following equipment items and appurtenances:

2 CO BOILERS 1600-ME-003 A/B

Built for:

TAKREER

RUWAIS REFINERY, ABU DHABI


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2.1. System description

The CO Boilers are used to ensure complete combustion of carbon monoxide (CO) contained inregenerator off gas. It is introduced in the combustion chamber by means of ports; and mixed withadditional fuel gas and combustion air so that a combustion temperature of 1000C is reached.

There are four forced draft gas burners sized at 120% design heat release.

Each burner is equipped with a forced draft intermittent pilot.

Combustion air is taken from atmosphere and routed to burners by means of two FD fans, one isnormally operating (driven by steam turbine) and the other one is spare (driven by electric motor).

The hot flue gases that are the product of combustion are then cooled down in the boiler section,where heat is recovered to produce per boiler up to 435 t/h of 42.1-kg/cmg steam at 381C.

The waste heat boiler section consists of a first coil of screen evaporator, aimed at protecting thesuperheater coil from very high flue gas temperature. The screen is arranged in four rows of 19vertical tubes.

Then the superheater consists of 3 sections of 3 rows of 30 vertical tubes each, where saturatedsteam coming from the steam drum is superheated to desired temperature (381C). A spray-typedesuperheater located between second and third section is used to control the outlet temperature.First section metallurgy is carbon steel, and second and third sections are made of P11, towithstand high metal temperatures.

Downstream the superheater, there are 72 rows of 38 vertical tubes each (main boiler), circulatedwith saturated water going upwards and being partly evaporated.

After that, ammonia is injected into the flue gas and reacts with catalysts loaded on SCR reactorhousing where NOx are converted to N2 and water.

The last coil recovering heat is the economizer, where boiler feed water is preheated from 171Cto 240C at design case. It is composed of 60 rows of 32 horizontal tubes each.

All those coils are connected to the steam drum located on top of the tube banks. Preheated BFWfeeds the steam drum as well as some saturated steam coming from 1600-D-004 and 1600-E-004.Saturated drum water naturally flows in downcomers and is partially vaporized in screen andevaporator coils. The mixture steam+water is brought back to the drum by means of the risers.

Saturated steam located on top portion of the drum goes to the superheater coil, after its moistureis removed by the cyclones and the demister inside the drum.

2.2. Fuels

Main burners and pilots are designed to fire any fuel gas described in the below table.

FUEL GAS Start up Normal gas Max LHV Min LHV Normal gas with gasco ethane

Molecular Weight

(kg/kmole)

18.17 16.88 14.68 16.63 20.88

LHV (kcal/kg) 10950 10769 11537 10165 10706


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2.3. Burners

The combustor is equipped with 4 identical M-36 Low NOx type burners operating in forceddraught conditions and located in end wall and firing horizontally. Each burner is equipped with anintermittent and forced air gas-pilot burner. Pilot burner is only used to ignit the main flame.

Turndown is 3:1.

Burners are designed for 120% heat release (i.e. 31.227 Gcal/h per burner).

Burners are equipped with automatic air doors.

Pollutant emissions will be within expected limits over the full operating range provided excess airis also controlled over this range. Expected values are:

Max.CO emission in dry FG: 100 mg/Nm3 @ 3%O2Max.NOx emission in dry FG: 50 mg/Nm3 @ 3%O2

Heat release for pilot burners is 0.378 Gcal/h per pilot with an operating pressure of 0.14 kg/cmg.

Each burner is equipped with two redundant ultra-violet, self-checking flame detectors (UVscanners).The scanners are mounted on each side of the burner and are used to monitor the gasflame. During initial start-up one of the scanners detects the igniter (pilot) flame. After successfulburner light off, the pilot is interrupted and both scanners are sensing the main flame.

Pilot burners are ignited per the operator request from local start-up panel upon the pilot headervalves confirmed open. The pilot automated block valve opens, associated ignition transformer isenergized and ignition transformer spark will ignite the pilot gas.

2.4. Waste Heat Boi ler Tube Cleaning System

Each waste heat boiler section is equipped with 87 retractable steam lances for blowing catalystparticles deposits off the convection tubes. Lances are placed on 7 horizontal rows of 7 lanceseach for vertical tubes, 2 horizontal rows of 4 sootblowers each for SCR system, and 6 horizontalrows of 5 sootblowers each for economizer section.

The sootblowing sequence is fully automatic after the start push button is pressed on local panel.First the steam generation boiler is cleaned, with three sootblowers running simultaneously since

there are three supply lines. Then the sootblowing sequence in the SCR is started, with one inoperation at a time. Eventually, the economizer section is cleaned, with three sootblowers runningsimultaneously.

It is recommended to carry out CO boiler sootblowing once a shift, but the operator shall adapt thefrequency, depending on the fouling observed on site.


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3. BOILER PACKAGE CONFORMITY FOR PRE-COMMISSIONING INSPECTION

3.1. Introduction

Checking the plant for conformity to the design is an extremely important stage of the pre-commissioning activities. It consists in controlling that:

The boiler has been erected as designed and specified. This involves the checking of the boileragainst design drawings, standards, data-sheets, and Piping and Instrumentation Drawings (P&I-D).

Components and equipment are free of defects and are operational. Run tests have been or arecarried out when possible, temporary wedges have been removed, clearance is given for thethermal expansion of the tubes, etc ...

Review must be performed according to a punch list. All defects detected should be reported onthe list and corrected before start-up.

A careful and organised preparation of this activity will lead to a quick and successful start-up. Onthe contrary, insufficient checking or preparation would most certainly lead to serious problems andto a delayed start-up and a delayed operation of the unit.

3.2. Structural Parts

a) Generally inspect the boiler structure and verify that it is in accordance with the designdrawings, check that all field work has been completed, that members are actually bolted orwelded together wherever they should be (punch list).

b) Verify that terminals are either free to expand with no interference with the structure (expansionis calculated) or anchored as per design drawings.

c) Verify that all air ducting joints and expansion joints are fitted properly and that all temporaryshipping and bracing pieces are removed, so that joints can operate freely.

d) Check that all instrument connections on casing which are not being used are plugged andsealed-off. Check also that their position will allow a normal use such as introducing through it asample tube without interfering with the steel structure.

e) Check that the ways through the casing for boiler tubes, which are fitted with seals or bellowsmade of reinforced woven fabric to prevent flue gas leak to the atmosphere, are set so theywould not be damaged when the thermal expansion will take place.

f) It must be possible to see the fire box through inspection holes.

3.3. Dampers (and/or Inlet Guide Vanes)

a) Check the damper operation over full travel, and see whether damper pointer corresponds withdamper blade position.


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b) For dampers controlled by pneumatic operators, verify that the blades move in the correctdirection and over full stroke. This should be done from the control room and by hand. Whenchecking the control loops, establish what the hysteresis of the positions due to the tolerancesis. Hysteresis at zero position of 3% is acceptable meaning that for zero on the signal, theposition must be full close and that for getting a first movement of the blade, it is acceptable thatthe signal is 3%. It is mandatory that the dampers are tight shut when the control signal is setfor 0% opening. The adjustment of the closed position must be achieved with the air pressureon, allowing the positioner to take its own zero position.

c) Flue gas and combustion air dampers are equipped with minimum adjustable mechanical stopsin order to have a minimum flow passing through the dampers. For start-up of FD fan, damper

shall be 100% closed (see 3.10) and mechanical stop position shall be adjusted accordingly.

3.4. Pressure Parts (Coils)

a) Check that inlet / outlet coils are located correctly, in accordance with the cold position indicatedon the design drawings.

b) Check that sufficient clearance is available to accommodate coil movements due to thermalexpansion. Take particular care of following critical points :

All construction wedges have been removed. Also remove yellow bolting used for transport

inside header box on end tube sheets.

Remove all dirt, which could accumulate into the annulus around the tube guides. Nothingmust prevent the tubes to expand.

Check that clearance accommodate also for creeping over time when it is required.

c) Check that all tube supports and guides are properly installed, tubes are resting on the supportsand locking-pins or bracing have been removed.

d) Check that skin thermocouples in superheater section are placed according to their expectedlocation, and that they are welded properly. Check that the cable loop will be able to follow thethermal expansion or creeping of the coil.

3.5. Refractory Setting

a) After erection, not all refractory areas will be accessible for inspection. Those areas should havebeen inspected prior to removing the scaffoldings. However, wherever possible, visualinspection should be done again.

b) Verify integrity of the refractory, make sure that all construction joints are packed and that thereis no exposed casing or structure.

c) Verify that the joints are properly made in the floor brickwork, which tends to expand with thetemperature.

3.6. Pilot Burners


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Pilot burners are fed with forced air coming from the combustion air duct. Gas is admitted througha small orifice. It is necessary to check every pilot to see that the gas orifices are not obstructed.

3.7. Burners

a) All burner components must be free of construction debris. Verify that all protection covers orplastic wrapping have been removed. Dismantle and verify that all pilot burner orifices, tips ofgas lances are clean with no obstruction. Reassemble according to supplier instructions.

b) Verify the burner layout with the data sheets and constructor drawings. Check in particular thecorrect location of the burner gas tips and port orientation with respect to the tile. There shouldbe no direct impact of the flames onto the next nozzles. Impact on the tile is acceptable only if it

is per design.

c) Make sure that air dampers or registers operate freely over the designed range and thathandles indicate the right position.

d) Verify that burner tiles are installed properly and are not broken. Space between tile and wallrefractory must be sealed with loose ceramic fibre.

e) Check that internal insulation is well tied back to the burner casing.

f) Burner mounting flange must be airtight (with mastic or gasket)

g) When burners are fixed onto the casing with a gasket or a sealing material, check that the

electric continuity of the burner is however properly achieved.

h) Verify the position of the flame scanner(s) for their ability to actually detect the flame(s). For anUV flame detector make the test to introduce a tube through the UV cell holder and checkthat the tube can go through all the way up out of the tile. Check that the tube does not interferewith the expected pilot flame path. Ask the supplier to come and make the necessaryadjustments if required.

i) For the ignition rods: check that the distance between the rod and the holder used as groundingis suitable to provide a strong spark; too large a gap would weaken the spark.

j) Only the top ignition rods must be in the flame.

3.8. Piping

a) Check over the complete piping system for compliance with piping layout drawings or isometricsand P&ID. In particular check that the valve type corresponds to the design (gate, plug, ball,etc) and that lines which are self-draining on the P&ID are actually so.

b) Ensure that all valves, pressure and temperature instruments and other accessories areconnected in the proper location and position.

c) Control valves must be checked for their direction according to the direction of flow. Check thatall valves are operational and verify valve stem stroke. Check that the valves are free from anydirt and debris which could impede their movement or damage the seats.

d) Safety quick acting valves (if any) must have been bench-checked for their closing time.Certificate must be available. Check that the valves are free from any dirt and debris whichcould impede their movement or damage the seats.


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e) Relief valves setting (if any) must have been bench-tested before installation. Certificate mustbe available.

f) Supports anchor points and support structures should be checked to see if they can effectivelysupport the line or block it.

g) All parts, which will expand on heating, must be checked for correct installation of guides andpossibility to expand in the right direction.

h) Check strainers on fuel lines. The sieves must be 0,8 mm on square pitch of round wire mesh.

i) Any temporary blinds are to be removed for the washing or blowing operation described below.

j) Check that cables ensuring electrical continuity on connecting flanges are in place.

k) Check that orientation of the steam traps is correct.

3.9. Instrumentation

a) Check the presence and the location of all instruments, for correct installation, and forcompliance with the process data sheets and the Piping and Instrumentation Diagram.Basically, pressure instruments on fuel gas lines must be draining to the gas line. The draughtgages must be draining to the firebox or, if the gage is at grade, equipped with a drain, which is

normally open during operation and closed only to read the draught at the gage.b) All instruments, even when tested and calibrated in the workshop, must be calibrated again and

tested.

c) Check instrument nozzles and impulse lines for having no significant leak under normalpressure.

d) Check thoroughly the wiring and the cable connection of the instruments. Thermocouples havea polarity.

e) Check that control valves operate properly and that they move to the correct position on airfailure or on signal failure.

f) When checking the sequence of the safety block-and-bleed valves, verify they move properlyand that the limit switches correctly show the position. The valves on the line must open whenthe bleed-valve is fully closed, and they must be closed before the bleed-valve opens itself.Check the positions on air failure. Check that, when the block-valves are initially open and thebleed-valve closed, if the air fails on the bleed-valve, this valve does open and the two block-valves close.

g) Instrument loop testing: Instrument loop testing is an integrated electro-pneumatic final testingof all the transmitters, transducers, differential pressure transmitters, relays, solenoids valves,pneumatic valves, etc, to ensure that the instrumentation operates as designed. It is a simulatedtest run for temperature, pressure and flow recording instruments :

Test signals are sent to alarms and to safety functions so as to check that alarms and safety

trips come up as designed, at panel and on the site.


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3.10. Steam Drum

a) Check that all functional aspects of steam drum, particularly internals, are properly installed andfree of foreign materials.

b) Internal gaskets must be checked to ensure they are fitted where specified, and that they are ofthe correct material.

c) Cyclones must be checked to ensure they are properly secured.

d) Check the ground system, fire protection system including fire proofing of structures, if any

e) Check whether correct relief valve is installed

f) Check completion of connected piping and ensure removal of blind gasket from nozzles

g) Check manhole cover and gaskets

h) Check vents and drains locations

i) Check pressure and temperature and level measurements

j) Check platforms and ladders

k) Check manway davit, if applicable

3.11. Fan, Motors and Turbines

a) Bearing lubrication is checked.

b) Fan drains must be closed and flanged or plugged.

c) Connecting sleeves must be aligned with the ducting. Gaskets and fabric must be airtight.

d) FD fan 1600-ME-003A-K1 A/B shall be started with closed damper in order to have an inputcurrent during start-up phase that is acceptable for the motor.

e) On motor, the nameplate information should be checked to ensure the replacement motor hasthe correct electrical characteristics for the application (voltage, RPM, Current, frequency etc).Electrical connections shall be checked. Delta arrangement shall be selected. Earthing shall bechecked good.

f) Check that accessible rotary parts are protected with a cover.

g) Fan rotation must be checked during at least two hours to make sure that there is no vibration

and that lubrication operates well with no abnormal temperature elevation of the bearings.

h) In case of any problem with the equipment the vendor must be involved.


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i) Vendor documents to be referred for Turbines.

j) Refer Fan and Motor vendor documents for further instructions.

3.12. SCR System

A thorough SCR system check should be carried out with particular attention paid to thefollowing:

Check power supply at all users.

Check instrument and plant air supply at all users.

The PLC, DCS and CEMS system must be ready and operable.

All interlocks, permissives, and trips must be checked and functioning.

Vents and drains in piping and at instruments CLOSED to the liquid or vapor ammoniaside.

All ammonia supply lines shall be clean and clear for transport of liquid ammonia anddiluted ammonia vapor.

All vessels are clean, dry, air-free, closed, and ready to receive ammonia. This is normallyaccomplished by nitrogen purging the vessels following cleaning.

Check that all control and monitoring instruments are properly connected, calibrated, and checked forproper function.

Visual check should be carried out as to the position of all manual valves.

3.13. General

a) All construction materials such as unnecessary scaffolding, ladders, tools, insulating materials,pipe spool drops, structural steel drops, wood forms and boards are to be removed for theoperator's safe movement around the boilers.

b) Check that no foreign materials are left over the tube banks of the convection sections, whichmay impair the good operation.

c) Clean out the fire chamber.

After final inspection, all man ways and access doors are closed.


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4. COIL AND PIPING PRE-COMMISSIONING

This concerns fuel gas lines, and other utility linesexcept all the lines connected to the steam drum(refer to boiling out chapter).

4.1. Coil and Piping Cleaning

4.1.1. General Principles

Cleaning is to remove rust scales and grease or oil remaining from fabrication or shipment.

In the case of carbon steel and low alloys piping several methods are suitable for this purpose,depending on the case encountered:

a) When grease/oil is not detrimental to the operation, lines can simply be blown out with air orsteam. Blowing out must be achieved against target plates in order to check the effectivenessand to manifest the end of the blowing.

b) Steam shall be preferred whenever possible for efficiency reasons since it is hot. Do not usesteam for piping not designed at least for 100C.

c) Washing (even hot washing) is used when specific chemical cleaning or grease and oil removalis required. Do not use hot washing for piping not designed at least for 100C.

d) When piping is known or suspected of being really dirty after construction (identified byinspection...), a water washing by circulation, or once-through, is recommended.

e) When steam or air blowing can damage the piping (polished tubes for instance), visualinspection and hand cleaning or washing will be preferred.

4.1.2. Blow-out of Fuel Piping

Blow-out must be conducted preferably in the direction of the flow. However for fuel piping which isdesigned as a manifold distributing through smaller lines to several burners it is more convenient to

blow out in the reverse way. Blowing should never be done through the nozzles of the burners, butburners being disconnected, from each line connection to the pipe work.

For this operation, non-return check valves internal or valves themselves are removed. Air orsteam is successively connected to all branches and discharge through the piping to atmosphereat battery limit, valves of the BL being removed.

Instruments must be isolated from the cleaning process or simply removed. Control valves orificesand small size ports, spuds, etc must be removed.

If required, control valves must be replaced by spool pieces made of recovered materials.

For large lines, air blowing can use cardboard bursting method to create the proper conditions offlushing. Cardboard leaves are put one over the other and total thickness must not build more than

4-bar pressure.


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When steam is used, large flow rates will be set out. Heat will help to scale rust. However, for fuelgas piping, which is not designed for that operation, low pressure steam should be used for steam-out to limit expansion of the lines.

For cleaning work, a number of connections will receive temporary gaskets.

For fuel lines, air can also be used. It will be discharged to atmosphere but not to the combustionchamber and not through burner nozzles as recommended above.

After flushing, the final wire mesh must be put in the pilot line strainers.

4.1.3. Blow out of Steam/Water Lines

Steam traps will be removed and line will be flushed with steam, after the line has been disconnectedfrom the boiler for this operation.Measuring orifice plates, dirt traps and non-return check valves must be removed and replaced byspool piece or bypassed. Thermocouples and local thermometers must be removed and the spigotsblanked off.It is desirable to perform the flushing process with the same medium that is subsequently used inoperation. In order to achieve a genuine cleaning effect it should generally be ensured that the flushingvelocity is greater than the flow velocity intended during operation.

Blow out of superheater coil and HP steam header is efficient when temperature is increased suddenlyand let cool down slowly. HP steam is sent to the coil during 3 minutes and discharged through atemporary valve. Let the coil/pipe cool down, open the drains to remove condensate, and start again

until the target plate is deemed clean.

Flushing the system requires technically clean water feed to the boiler through the previously pre-cleaned feed water line (water without phosphate or natrium dosing).

Activities:- Open all vent valves.- Twice fill up the boiler with de-aerated water from the boiler feed pump.- Open all boiler drain valves.

The purpose of this cleaning is to remove water-soluble contamination and rinsing the drain and ventlines.

ATTENTION:During flushing the demister package in Steam Drum must be removed!

Steam traps are then fitted again and checked for proper operation as soon as steam lines havebeen commissioned.

Snuffing steam lines are to be flushed with steam, after the line has been disconnected from thecombustion chamber for this operation.

The steam systems must preferably be tried (fluid circulation) before firing and drying out theboiler.


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4.1.4. Plant Air and Instrument Air.

These utility lines must be flushed clean, not to transport dirt to the instruments and other linesduring the tightness test.

4.2. Fuel Piping Tightness Test

4.2.1. General

After final hydrotest and cleaning / flushing, all connections are to be fitted with final gaskets. Alltemporary gaskets are to be removed.

Piping joints must then be tested for tightness with air or nitrogen, depending on the process.

4.2.2. Procedure

2 - 3 bars service air or instrument air or nitrogen (when full dryness of the medium is required)should be applied and soap-test (or a microphone) carried out to detect the possible leaks at joints.Flanges are enveloped with tapes and soap test performed on a tiny hole in the tape.

4.3. Post-Flushing Activities

Restore all piping and equipment to their normal operating configuration.

Open all instrumentation root valves associated with the system.

Reinstall control valves.

Install flow and restriction orifice plates.

After reinstatement, perform a final system check using the latest revision of the P&IDs.


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5. INITIAL START-UP

5.1. Introduct ion : Before Start-up

Before start-up operators must be aware of the potential risks.

Operators must also be familiar with the documentation, in particular the safeguarding andcorresponding logic diagrams and this manual.

The chief operator will establish detailed procedures in order that all the personnel use the same

procedure.Initial start-up or any start-up occurring after a shutdown for maintenance, must be conducted withthe same precautions.

First start-up means using the instrumentation, valves, transmitters, analysers, etc and theburners in the boiler for the first time. A special attention must be paid to the equipment on thisoccasion. As the programmed start-up sequence is experienced for the first time the steps shall beclosely followed by the operators.

5.2. General Recommendation during Start-up

During first start-up, it is mandatory to watch how thermal expansion proceeds and if piping and

coils remained on their supports.Possibility of condensation in the fuel lines must be checked with respect to atmosphericconditions and avoided. Line must be drained frequently checking for water or condensates.Condensates of light hydrocarbons (C4, C5+) can be hazardous (flash), draining must beundertaken with precaution.

Burner operation shall also be carefully and constantly watched to identify any abnormaloccurrence: flame impingement, wrong flame shape, flame instability, nozzle plugging, cokeformation, etc... Flame detectors must give reliable indication of the presence or absence of theflame.

First start-up needs that fresh refractory concrete is dried out slowly according to a specificprogram (see section 6. Refractory lining dry-out). During and after dry-out refractory should be

directly inspected through observations doors or from the inside after boiler has cooled down inorder to detect possible cracks.

Initial start-up (but also any start-up after maintenance on the piping) is also the opportunity tocheck piping tightness in true operating conditions. Temperature can modify flange tightness aspiping expands and moves, tightness for hydrogen contained in fuels is more difficult than for anyother gas. Possible presence of H2S in fuels also creates a potential hazard.

Since all devices and instruments are being used for the first time in real conditions, it is ofparamount importance to check their actual operation and response constantly, until sufficientconfidence is gained. Quick material and thermal balances will help to detect abnormal recordings.

Calibrations of instruments and analysers shall be requested as often as deemed necessary.

It comes naturally up that first start-up must be conducted slowly and, if possible, stepwise to allowtimely checking and observation.


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Personnel must be trained and in possession of the present manual and those given by thesuppliers of the auxiliary equipment. Before burner ignition, a start-up schedule will be issuedgiving the main steps and general guidelines to all the start-up team so that co-ordination isensured.

In case of abnormal occurrence, it is of paramount importance that operators can react in the rightway within the shortest time.

During first start-up or start-up after maintenance, some water may remain in the fuel piping, whichshall be drained at low points as often as necessary. Draining water must be hazardous as it mayhappen that liquid hydrocarbons can also be present instead of or with water.

5.3. Hazardous OperationBefore starting up the personnel must be aware of the potential risks.

Hazardous conditions can arise for the following reasons:

Accumulation of fuel gas in the firebox is likely to create an explosion when the spark forthe ignition is set. Depending on gas composition and Oxygen proportion in the mixture,this explosion can be immediate or a little delayed waiting for more gas or more air orhigher temperature. A fire in the firebox can, as temperature increases, cause an explosionfar up in the boiler section, breeches or flues where flammable gas could have beentrapped. Such a situation is prevented if the operating rules of this manual and a propermaintenance are conducted.

Excessive dampness of the refractory can be the cause of refractory cracking during start-up if the temperature is not increased sufficiently slowly and if low temperature step(150C) is not effectively respected.

Quick start-up is likely to cause excessive stresses on tubes and supports.

Over pressure in the fire chamber and boiler section can cause personnel injury or materialdamage as hot flue gas would leak out of sight doors, not blanked-off connections,unpacked tube seals, etc

Steam out by snuffing steam, if used in excess in a cold boiler and if the line is not purgedbefore admitting steam to the boiler, can dampen the refractory material and damage it.

Large failures of refractory materials covering the inner surface of the boiler casing areusually cause of casing bulging and structure deformation. In some cases, stability of theboiler can be impaired.

Flows through the coils are in a certain way protecting the tubes from excessivetemperature. Too low a flow rate with respect to heat flux can be the cause of tubeoverheating.

External fouling of convection tubes can cause the following trouble :

- Excessive hot flue gas will flow to the down-stream equipment.

Inside tube fouling increases the tube wall temperature which can eventually reach themaximum allowed for the material. No greater value shall be admitted without checking the

tubes can withstand it. An incomplete combustion resulting from a lack of air can be observed on the burners

running with fuel pressures higher than that of design.


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The block valves downstream from the exit of the superheater must be open to prevent anyoverpressure of the fluid (by thermal dilatation) contained in the coils.

5.4. Line Purging

At first start-up, lines can contain air or other gases which may not be compatible with the utility orprocess fluids. Main cases are listed below with the corresponding purging procedures :

Fuel gas lines: before admitting fuel gas into the line to the burners it may be necessary to purgethe line with nitrogen in case fuel gas is containing more than 15 vol. % H 2. Otherwise air purgingis acceptable.

Steam lines: If the steam lines go to a condenser, it is mandatory to purge air conveniently so asto get a complete condensation of the steam once in operation.

5.5. Lines Gas-in.

Before starting, fuel lines must be gassed in. It means that the normal operating fluid isintroduced in the lines.

Line is pressurised with the fluid five times successively and air or nitrogen contained in the line isvented to atmosphere or to a flare in safe location.

This operation is necessary for fuel gas lines in order to avoid any delay for ignition when a burner

is started.

5.6. Leak-through Checking

This concerns both fuel gas lines to pilot and burners.

Before starting a boiler it is necessary that all gas valves are closed. It is also necessary to checkthat there is no leak to the combustor through the burner valves.

The operator can ascertain that valves are closed but he cannot say whether they leak or not. Theoperator is helped by a logic sequence programmed in the control system or a dedicated PLC isthen used.

The logic sequence, when existing, is usually called Leak test.

The system, which involves pressure indication, verifies that:

a) the manual valves of the pilots and of the burners themselves are well closed and are notleaking to the combustor

b) the ESD valves take their right position and do not leak.

Test (a) can be done with the fuel gas itself or using a separate supply of nitrogen considered as asafe medium in this application.

Test (b) can be achieved only with fuel gas from the supply. This test can be omitted when ESDvalves are removed to be checked on a test bank. (e.g for sour gas line)


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5.7. CO Boi ler Purging

As fuel gas is used for the leak test, boiler must be purged with ambient air before burners arelighted to evacuate all gas that could have been sent to the fire box and accumulate during thetest.

Purging of chamber shall be performed with forced draught fan maintaining a flow rate of 195000kg/h for 10 minutes. All burner air dampers shall be open, as well as FD fans inlet and outletdampers.

Purging efficiency can be confirmed by checking the atmosphere of the chamber with a portablegas detector.


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6. REFRACTORY LINING DRY-OUT

6.1. Introduction

Concrete or castable refractory drying is compulsory and must take place before boiler start-up sothat all attention can be given to the process at start-up stage.

Dry-out must then be scheduled taking into account two parameters:

1) A wet refractory is sensitive to frost and it should be dried before cold season when externaltemperature can drop below 5 C with wind effect likely to cause some icing on the surfaces.

2) In some circumstances refractory can require to be dried shortly after curing in order to blockfurther alteration of the concrete by ambient air (e.g. reaction with CO2 contained in atmosphericair).

The following procedure shall be taken as a general guideline. Freedom is given to team on field toadapt it according to site conditions. As matter of fact, simulation of heat exchanges in drying-outrefractory conditions is tricky to carry out and flue gas temperature forecast is impossible todetermine beforehand.

6.2. Dry-out Procedure

6.2.1. Dry-out Principle

Procedures will be adapted to the refractory types, considering the whole CO boiler and looking forlimitation that may be due to a specific part of the refractory lining, coil or supports materials, andthermal expansion.

Dry-out is to eliminate excess of water by vaporisation. The dry-out philosophy for this job is topurge the boiler with a large flow of dry and hot air. Air will be heated by fuel gas combustion, tothe different stages of the dry-out curve (see below). Dry-out will be carried out with the largest airexcess possible, in order to bath the refractory in relatively dry stream. It is obtained by openingfully both the air dampers on each operating burner and the FD fan dampers on both sides. Airflowcan be reduced only for sake of operating burner flame stability.

Fuel gas only shall be used for all dry-out sequence.

6.2.2. Temperature Limitations

Dry-out sequence shall be suitable to the following boiler material design temperatures:

- Coil tubes: design tube temperature value for SA335 Gr. P11 tubes is 435C (superheatercoil), design tube temperature value for SA106GrB tubes is 329, 387, 302, 257C (screenboiler, SSH, boiler and economizer coils, respectively). Note: these limit temperatures meanthe drying-out must be done with boiler tubes filled in with water.

- Refractory anchors: maximum anchor tip temperature (refer to API 560/ISO13705, August2007 edition) is 455C for carbon steel (flue gas at convection section exit), and 760C for18Cr/8Ni stainless steel, and 1038C for TP330 stainless steel. Nevertheless those values

can temporarily be exceeded for a few hours dry-out sequence.


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- Radiant and convection tubes supports and guides: maximum temperature is 1121C forInconel 601, 925C for 25Cr/20Ni (A351 Gr.HK40) material, 778C for 18Cr/8Ni materialand 480C for CS material.

- Refractory: all refractory materials in the CO boilers are designed to withstand boileroperation at very high flue gas temperatures and do not represent a limiting issue for dry-out temperature. Maximum design temperature (refer to refractory datasheet) is 1650C forFirecrete 3X insulating concrete, 1538C for Kaolite 2800 insulating concrete, 1260C forKaolite 2300 insulating concrete, and 1100C for Block607.

In any case, when the concrete lining is not more than 50 mm, the flue gas temperature shall notbe more than 450C.

6.2.3. Procedure

Note: temperature steps as recommended by HEURTEY are displayed in the sketch below:REFRACTORY DRY-OUT CURVE.

Flue gas temperature as seen on dry-out curve is the average flue gas temperature in chamberwhich can be deduced from measurements by TE-326AX/BX/CX/327X transmitters located in thecombustion chamber. Note that it is commonly hard to follow exactly these curves and that theyshould be used as an approximate guideline.

As much as possible, casing temperature monitoring shall be carried out in various locations of COboiler (one spot on each side of combustion chamber, one spot on each side of boiler section, onespot on flue gas duct to stack) with an optical thermometer. Atmospheric conditions (airtemperature, wind, moist, sun, day or night) as close as every measured spot shall also be noteddown for each set of measurement (measurement frequency: every 2 or 3 hours). Casingtemperature trend will give an indication of water withdrawal in the refractory layers: oncetemperature is stabilized in one spot after last plateau (see below), it can be assumed that all waterhas been vaporized and removed in the refractory. However, due to high sensitivity to atmosphericcondition variations, casing temperature trend shall not be used as a criterion to lead the dry outsequence (e.g. stop the sequence before end of last plateau if stabilization is being observed inevery spots). Last plateau could possibly be extended in case that stabilization has not occurredyet provided that atmospheric conditions are being constant awhile.

Convection section flue gas temperature (TE-306X) will also give relevant indication of waterremoval through the temperature profile that should end up almost straight at the end of the dry-outsequence.

The steps described hereafter are then recommended, following the start-up procedure describedin section 8. CO Boiler Start up

The ESD signals from the process fluid interlocks must be bypassed during the dry-out phase inorder to allow opening the main valves and fire the burners.

Initially the Leak test and the Purge of the normal Start-up procedure are followed.

The fuel gas used for the dry-out must be in compliance with the job specification. It must bechecked and analysed for its compatibility with the pilot burners, i.e. fuel LHV and MolecularWeight are to be known.


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Possibility of condensation in the line must be checked with respect to atmospheric conditions andavoided. Line must be drained frequently checking for water or condensates. Condensates of lighthydrocarbons (C4, C5+) can be hazardous (flash), draining must be undertaken with precaution.

On the burners: fuel gas lances, oil barrels and safety devices shall be removed to protect themfrom pilot flame heat. Steel plate shall be screwed on the gas lance connection. Service air shallbe plugged. Valves to gas to burner shall be closed. It is recommended to blind off the lines forsafety.

Start-up procedure is then followed :

Pilot gas and fuel gas lines are filled in with fuel gas up to the burner cock valves by asuccession of five pressurisations and venting to atmosphere of the lines once closed backat the inlet of the fuel skid. Pressure must be set at normal level for pilot fuel and minimumlevel for main fuel. Safety valves are forced to open from the PLC for these purging cycles.Then safeguarding system is set back to normal.

Drains (for fuel system, steam system) are opened after each pressurization to removewater or condensates and then closed again.

Air dampers of all the burners are wide open.

Leak test is performed.

Combustion chamber is purged with Forced Draught fan: flow rate of 195000kg/h for 10minutes. When purge is over, air flow rate shall be reduced to proceed to pilot light off.

All pilot burners are lit.

If first step of 150C is not reached, all burners are successively lit at their minimumliberation (see minimum pressure indicated on burner curve) before increasing the power tofollow the dry out chart. The airflow is increased to the maximum rate compatible with theflame stability.

Chamber temperature (TE-326AX/BX/CX/327X) is increased at 25C / hr rate. The dry-outchart is followed to the 150 C plateau. If necessary air flow is adjusted to control the rampup and the plateau.

At the end of first plateau, average chamber temperature shall be increased to 450C at arate of no more than 25C by increasing fuel flow rate. Stabilisation of the average box fluegas temperature shall be awaited (via TE-326AX/BX/CX/327X transmitters). The 24-hoursecond plateau of refractory dry out can start. In order to maintain chamber temperature allalong the plateau duration, air flowrate shall be the adjusting variable.


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When second plateau and steam drum boiling out (if any, see next chapter) are over,temperature of the chamber shall be decreased at a 50C/hr rate. When the chambertemperature is back to around 200C, burners and then pilots are stopped (in case of nonsub-sequent boiler start-up). The boiler is then left to cool down to atmospheric conditionswith all dampers (burners and flue gas) still fully open. FD Fan is stopped after an air purgingtime of about 5 minutes.

After dry-out a visual inspection must be carried out, minding a sufficient low flue gastemperature. Please refer to maintenance actions described in section 11. PREVENTIVEMAINTENANCE.

0 8 16 24 32 40 4 8 5 6 64 72

0

60 0

50 0

40 0

30 0

20 0

10 0

70 0 COMBU STOR FLUE GAS TEM PERATURE C

Time in Hours

18 hours at

150C

25 to 30C / hr

25 to 30C / hr

50 to 70C / hr

24 hours at 450C


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7. STEAM DRUM BOILING-OUT

Through boiling-out with strongly alkaline solutions, impurities contained in the steam drum will bewashed. Conversion of the iron oxides into a protective layer of magnetite Fe204 will be initiated.

The boiling-out is done during the dry-out of the flue gas path (See chapter 6). The demisterpackage must still be removed.

During the boiling-out, the heating shall be only made from the gas side.

After closing all drain valves, fastening of all loose parts and removal of installed blind flanges, thesteam drum is to be filled with treated feedwater (T=20C) up to bottom of the drums manhole.

Per 1 m3 water content:

0.5 kg trisodium phosphate Na3PO4

(with 20% P2O5 content) dissolved in clear water

are introduced by all means into the steam drum through the manhole.

Be careful: When working with chemicals, wear rubber gloves and face shield.

Commercial trisodium phosphate has a max. P2O5 content of 20% - so that per 1 m3 water content0.5 kg Na3PO4 have to be added to the water in order to obtain a P 2O5 content of 100 ppm.

When the boiler water temperature reaches 100C, let steam flow freely through the open drumvent for two hours during the 150C step of the dry-out (see previous chapter).

Then close all vents except on superheater outlet header. This should correspond to the beginningof the ramp up to the second dry out plateau (450C). Superheater drains should be closed whenno water discharge can be observed through them.

A boiling out time of 48 hours is necessary during which the first blow-down (one half a gage glass)is carried out at 4 bar after approximately 6 hours. Further blow-down is carried out after approx. 4hours. If last blow-down is not of clear appearance, continue boiling out until blow-down is clear.

If, during boiling-out, steam amount sent to the atmosphere is deemed too much (estimated: 42t/h), operator should increase drum pressure to 10-15 kg/cmg and/or reduce air flow to FD fans.

Samples of the blow-down shall be taken for:

visual inspection for signs of oil or contamination

pH measurement > 9

After each blow-down, boiler should be refilled to normal water level and chemicals should beadded to reach the original concentration. In case the water level drops to the low water levelmark, more water is to be fed in. The temperature of the feedwater in the steam drum should beabout the same as the drum shell. If the temperature difference is bigger than approx. 50C thewater is only to be fed in very slowly.


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After boiling-out, the whole content of the boiler system is to be discharged and the system to berinsed at least 2 3 times. The first refilling of the system should be carried out with feedwater at atemperature of 100C to avoid thermal stresses. Further re-fillings should be carried out withnormal water at ambient temperature. The rinsing procedure may be stopped as soon as the P-value of the boiler water is 50 ppm. After this, it is absolutely necessary to open the steam drumand to remove possible dirt deposits. The steam drum internals must be checked and demistermay now be installed.


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8. CO BOILER START-UP

8.1. Introduction

Depending on the time between dry-out and start-up, a short re-drying may be scheduled.

Start-up of the CO Boiler after dry-out must follow the plant start-up schedule and procedure.

Actual start-up must follow the programmed sequence. Refer to appropriate documents (functionalanalysis, logic diagrams, control philosophy...).

A general guideline specific to the CO Boiler can be found hereafter, given as a help to the

operator.

8.2. Start-up Procedure

8.2.1. Lines

Lines are gassed in and drained.

Installed heat tracing (steam or electrical, if any) should be turned on.

8.2.2. Fuel Analys is

Nature of the fuel gas must be known before light off, so that if there is any deviation from thespecification, consequence can be appraised.

8.2.3. Leak Test

See the functional analysis and the programmed sequence. This procedure should involve pilotand main gas.

8.2.4. Purging

The boiler is purged with air after leak test. See section 5.7. CO Boiler Purging and functionalanalysis for description of sequence.

8.2.5. Boi ler Start up

Ensure that demister package has been installed.

Ensure that all drum manways are properly installed with the manway cover centred and the entirewidth of the gasket installed between the manway ring and cover.

Before starting the pilots, fill the system with treated water (min 20C) to the start up level, i.e. 203mm above bottom line.

Blowdown the gage glass and observe the return of liquid to ensure that the glass is clear andfunctioning properly. Test drum water chemistry and feedwater oxygen levels.

Start up pilot and burners at minimum firing (see below 8.2.6 and 8.2.7)


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As heat is being absorbed by the boiler, the drum level will begin to rise. This drum swell is due towater dilatation and to the change in volume from water to a water/steam mixture. The feedwatercontrol valve and blowdown valve are to be closed initially, but must be opened and closed asnecessary to maintain the drum water level between LWA and HWA.

The steam drum vent valves and superheater drain valves are to be closed after the drum pressurereaches 1 kg/cmg.

Operator in control room controls the drum pressure increase ( no more than 2 kg/cm per minute)by slightly closing the superheater vent valve PV-300X. Once desired steam pressure is reachedand steam sample is of acceptable quality, the main steam valve must be opened and steam issent to the header.

Once the boiler system begins to stabilize (approx. 1 hour), the drum level control can be returnedto automatic. Close supervision is required to ensure that all systems are operating properly.

The superheater vent valve PV-300X may now be fully closed.

8.2.6. Pilot Burner Ignition

Please refer to the pilot manual procedure and the programmed sequence.

When a pilot does not light, the operator must look for the cause(s) and remedy the problem, whichcan be in the following list :

- sparkling of ignition rod is inefficient;

- a valve is closed on the line. Normally it is possible for operator to hear through the opensight door whether gas is flowing or not;

- fuel gas composition is not adequate, presence of nitrogen or air can be due to inefficientpurging;

- Pressure control valve (PCV-325X) located on fuel gas line to pilots is not delivering thecorrect pressure. It is more likely to happen when a certain number of pilots have been lit,pressure may drop too low due to a malfunction or a limitation of the PCV when anothervalve is opened.

8.2.7. Main Gas Lighting

When pilot lighting is completed, the operator can proceed with the ignition of the burner mainflame. See the functional analysis and the programmed sequence.

The start-up is finished when all the desired burners are in operation at their minimum load (heatrelease). At this stage operator may check that all the operating variables are suitably controlled.The boiler is however susceptible to show its designed performance only within the specifiedoperating range.

8.3. CO Boi ler Capacity Changes

In order to protect the refractory setting and some other parts, heat release must always and in any

circumstances be increased and decreased slowly.


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This ramp-up or ramp-down must be stepwise. It must be controlled by the operator reading fluegas temperature in the combustor (via transmitters TXT-326AX/BX/CX/327) and at cold flue gasduct upstream stack with TT-306X transmitter which should not be allowed to rise faster than 50Cper hour (start up and normal operation).

In any circumstances air flow rate to the burners must always be increased before the firing isincreased and the reverse, firing and fuel rate must be decreased before air flow rate.

Burner flames must frequently be checked; there must be:

a) No flame interpenetration

b) No coking visible around the fuel gas nozzles

During ramp-up, flame aspect, O2 content in flue gas must be looked at in order to check thatburners have sufficient air and operate correctly. Flames must not be weak or pulsating, sign oflack of air. Airflow rate is increased according to the gas rates.

O2 analyser (AT-303X) downstream boiler tubes will provide the indication for the excess air: 2.0 0.05 vol % wet basis are measured for 56% excess air during operation with regen off gas.

8.4. SCR system

Pre-Start Operation

Refer to Adblue system vendor documents for startup instructions on Adblue system.The vendor system will provide Ammonia, as required by SCR system demand.

The SCR catalyst must be warmed to at least 293C to 306C per Minimum Flue GasTemperature shown in HPC data sheet for SCR system. The source of heat for warmingthe SCR catalyst is the flue gas.

At the ammonia injection manifold, open the six (6) butterfly damper valves on the branchmanifolds. This allows dilution air (when started) to flow freely from the Adblue System intothe duct and SCR catalysts.

Follow Adblue system vendor documents for startup instructions on Adblue system, i.e.eUrea storage stank, hydrolyser etc..

Permissives to Start Ammonia Injection

The following permissives must be met before the ammonia injectionsequence may begin:

No ESD signals

Permissive from Adblue system regarding urea pump (running), dilution air blower(running) /air flow/pressure (above minimum), ammonia/air mixture temperature (above


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minimum).

SCR reactor flue gas temperature is above low alarm point

If all of the above conditions exist, Ammonia is ready to be injected.

Ammonia Injection Sequence Start

The system must be in Ready to start (ammonia injection) mode.

Adblue system to be activated to start ammonia flow to Ammonia Injection Grid. Followvendor operating manual.

The PID control for the ammonia flow control valve will be in manual mode at minimumvalue. The operator will increase the output manually from the interface screen until theNOx level reading is at desired level.

If required, the flow through the injection lances may be balanced by watching thedifferential pressure gages (PDG 309AX to FX) and adjusting the adjacent butterfly valves.After completion of the adjustments the operator handles shall be locked in place orremoved.

Running Operation

When the SCR is at steady state operation, the operator will put the ammonia control PID inautomatic mode. The PLC will modulate the level of ammonia flow to maintain the desired NOxlevel set point as conditions change with the SCR.


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9. SHUTDOWN

Shut down of CO Boiler can be:

- planned as part of turnaround shut-downs

- unplanned but performed at normal speed respecting rates as recommended for capacitychange (see section 8.3. CO Boiler Capacity Changes)

- in case of emergency when a sudden and hazardous situation occurs in the plant, the unit orin the boiler itself.

Emergency shut-down must be programmed in the control system. Refer to appropriate document

dealing with the boiler safeguarding.

Following instructions are given as a guide line.

9.1. Planned Shutdown

Before shut down, capacity of the unit must be reduced progressively down to the minimumoperation level that can be achieved with the equipment and the instrumentation.

Once the technical minimum is reached, a special shut down procedure must be applied.

Resetting of the controllers must be disconnected.

Controllers are used in close-loops as long as it is possible when capacity is further reduced.

Regen gas dampers are closed.

Minimum fuel gas pressure is reached with all the burners in operation.

Burners are closed one after the other until there is only one remaining in operation.

Combustion air is reduced according to fuel combustion. More excess-air can be acceptedproviding that flames remain stable and emission of pollutants to atmosphere (black smoke, CO,etc...) are under control.

When fuel pressure is reduced below Safeguarding Low pressure level, main gas line is closedautomatically with safety valve.

At this stage, BFW flow in economizer coil can be interrupted.

Boiler is let cooling down. It is isolated (with shut-off dampers (cold flue gas and burner dampers))for slow cooling after a 5 min. purging time (burners off and dampers open).

All hand valves on the gas lines to burners are closed to prepare for the next start-up.

The operator will close also the Battery-limit block valve of the Pilot line and all other block valves.The safeguarding would have closed the ESD valves and open the bleed valve.

After a 5-min purging, air dampers can be left in their last position and FD fan is stopped.

9.2. Taking Burners Out of Operation

Only one pilot and burner at a time can be taken individually out of operation.


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If more burners shall be taken out of operation, flame detectors trip and logic in the safeguardingsystem have to be bypassed by the operator.

Since fuel gas is delivered at constant pressure for pilots there is no impact on the other pilotswhen one is stopped. Air intakes of the pilot can obviously remain open.

Stopping fuel gas on a main burner would require reducing together gas and air progressively inseveral steps depending on the proportion of the heat release of one burner. When the burner isstopped, its manual fuel gas valve is closed, as well as its air damper in order not to allow airingress.

Moreover, stopping a burner means that the others would take its load because the Mastertemperature controller will force the same total firing load. Consequently, as a FD fan forces air

under flow control in proportion with fuel firing, the same total air quantity will go to the boiler. Inorder that the exact quantity required by the remaining burners goes effectively to those, airdampers must be closed on the burner taken out of operation.

Normal SCR System Shut down

AVS and SCR system

When it is necessary to shut down the SCR system, stop Adblue system according to vendorinstruction manual.

9.3. Emergency Shut-down

9.3.1. Common Features

ESD or emergency shutdown is a collection of programmed logic devices taking care of quickactions for equipment or personnel safeguarding when the operator cannot have time or thepossibility to do it himself.

The operator will have to be familiar with the cause and effect of the system.

The operator is normally alerted by pre-alarms before shut-down and associated alarms aretriggered.

After a safety shut down, the system must be reset by the operator: Causes must have beendeleted by appropriate actions on the causes and interlocks commanding the movement of thevalves must be unlocked.

After a safety shut down, causes must have been deleted by appropriate corrections and theoperator must reset the system before the unit can be started again in order to prevent untimelystarts.

Starting being the most critical phase for a furnace, the operator by his skill must avoid too manyshutdowns.

Proper maintenance of the sensors and actuators involved in the safety systems will provide therequired reliability.


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Maintaining the equipment within the normal operating range is also acting safely.

Achieving required fluid treatment to eliminate potential corrosiveness is required to reach a goodlevel of safety.

Preventive maintenance is required to reach a safe operation. See chapter 11.

Emergency Shutdown of SCR System

When a shutdown condition is detected, SCR system will be shut down by shutting down theAdblue system.

9.3.2. Safety Interlocks

For description of interlocks, please refer to functional analysis document (HPC doc 16A0-FJ-801).

9.4. Internal Boi ler Preservation

Boiler system which is shut down and depressurised for extended periods (more than 24 hours) shouldbe preserved in order to prevent stationary corrosion. The preservation process depends on the

intended period of shut down. Wet and dry preservation can be selected.

9.4.1. Wet Preservation

For short periods of disuse (24 to 48 hours) it is advisable to increase the content of oxygen-bindingagents in the boiler water briefly to twice or three times the amount before shutting down or to maintaina slight pressure in the boiler.

For prolonged stoppages, fill the boiler up to the highest point with water having adequate alkalinity(SK 8.2 between 5 and 10 mmol/l) and excess of oxygen-binding agents (e.g. hydrazine,approximately 0.7 kg/m, with non-aerated water up to 1 kg/m). Thoroughly distribute the chemicals by

thermal or mechanical circulation (at intervals even during the disuse). Once per week, verify thecomposition of the preservation liquid and the filling level of the boiler. Ensure that the pH value is atleast > 8.2, otherwise re-dose.

Prior to restart start-up, analyse the boiler water and correct with chemicals if required.If the water is severely contaminated, entirely or partly drain the boiler water and replace it by freshboiler feed water.

9.4.2. Dry Preservation

If boiler systems is to be shut down for several weeks or months, dry preservation is recommended.To achieve this end, drain the boiler at temperatures of 80 to 100 C, open the manholes andmechanically remove traces of water. Once cooled down, suspend bags with desiccant agent (for

instance silica gel) and close the boiler.

Approximately 0.5 kg of silica gel must be used per m of boiler volume. Initially at shorter, later at


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longer intervals, check to see if the desiccate agent is still able to absorb moisture. This is usuallydetermined by the discolouration of the gel.

Water can be removed from silica gel desiccant agent by heating to 80 120 C and than the agentcan be reused.


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10. NORMAL OPERATION

10.1. Operating Variables

Those are the variables that are to be controlled.

10.1.1. Firing Contro l

Fuel rate is automatically adjusted to obtain the desired flue gas temperature in the combustor(1000C) that ensures complete combustion of CO coming from regen gas. This is achieved by acontrol valve commanded by the temperature controller (TT-327X) directly or through a cascade ona fuel pressure or flow rate controller.

Firing control loops must take care of the possible variations of supply gas pressure, temperature,and density. Several ways are also offered to do it.

Refer to appropriate documents for actual situation: P&IDs and control philosophy.

Burners are sensitive and weak parts of the CO boiler. They must frequently be checked. Thefollowing conditions must be gathered:

- Pilot flames must rest inside the pilot heads which must be red hot.

- No coking visible around the fuel tips.- No coking inside pilot head.

During load changes, flame aspect and O2 content in flue gas (measured with AT-303X) must bechecked so that burners have sufficient air and operate correctly. Flames must not be weak orpulsating, sign of a lack of air.

Air flow rate (excess air) must be increased in the following circumstances:

- Black smoke at stack (or in the chamber)

- Brown flames on gas fuels (flame colours should range from blue to light yellow)

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CO Boiler Manual(VP MA 008 028_R0) 1

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