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PHILOSOPHY OF OPERATION
SADELMI – DEMIN PLANT
HOFUF
SECTION ‐ 1 FILTERATION SYSTEM
The plant can be categorized into following four phases.
1. Filtration system 2. First Stage RO 3. Second Stage RO 4. Mixed Bed System
1. FILTRATION SYSTEM: Description: In filtration system, there are three filter feed pumps and an Automatic Media filter. General operation philosophy of Filtration system: The pumps feed the filter and the treated water through the filter will flow towards the first stage RO that is split into two even streams. The filtration system is comprised of the following.
1. Filter Feed Pumps 2. Automatic Media Filter 3. Filter Backwash Pumps 4. Air Blower 5. Dosing Pump
1.1 FILTER FEED PUMPS There are three Filter‐feed pumps as follows. Filter Feed pump – 1 / P1001 Filter Feed pump – 2 / P1002 Filter Feed pump – 3 / P1003 Filter feed pumps operate in two modes: 1.1‐A Automatic Mode: The selector switch of each pump on the local control panel should be in Remote position and HMI Auto position. Filter feed pumps in Auto mode will be running in two cases. CASE – I Filter Feed pumps will run in 2 Duty/ 1 Standby fashion when both the RO first stage streams are in operation (Service Mode). In case of single stream operation, there will be 1 filter feed pump duty and the other two will be standby. Feed pump P1001 is designated for Stream A operation whereas Feed pump 1002 shall be designated for Stream B operation. Incase of failure of pump for any respective stream, the third pump P1003 will take over and there will be a trip indication for the faulty pump. CASE – II When a filter undergoes backwash, the feed pump 1003 shall be running during Rinsing. Interlocks:
a) All filter‐feed pumps will be interlocked with a low level switch in the Raw Water Tank to keep from dry – running.
b) All filter‐feed pumps will be interlocked with overload signal, as in case of overload the pump must stop immediately.
1.1‐B Manual Mode: There are two cases in manual mode.
CASE‐I The pumps can be operated manually either from the control room or the local station. From Control Room: The selector switch is in Remote position on the control panel. The selector switch for the same pump in the HMI will be in manual. The pump will operate as long as the switch remains in manual. Incase of overload or low level in the tank, the pump will stop. From Local Station: The selector switch will be in Local position in the control room, and the pump will operate with start/stop pushbuttons on the local station near by. TIP: The HMI will sense the operation of the pump in Manual as described above through the feedback signal to the PLC. FAULTS AND ALARMS ACKNOWLEDGEMENTS:
1. In case of pump failure during operation for any stream due to overload, the respective standby pump will automatically take over without stopping the plant and there will only be a trip indication on the local panel in the control room. The alarm will be logged.
2. In case, when both streams are continuingly running in auto mode and more
than one pump fails, the fault lamp should be lit and alarm must annunciate. The system will shutdown, all the valves will close.
1.2 AUTOMATIC FILTER The HMI shall include a separate screen for the filter operation that will have two modes of operation for the filter. 1.2‐A Automatic Operation: For Automatic Operation, the filter should be put in Automatic mode from the HMI Filters Screen with the selector (soft) switch. This will allow the two streams of 1st Stage RO to operate in complete Auto mode. For any stream, Filter feed pump and high‐pressure pump should also be in Auto position from the HMI and Remote position from the MCC. 1.2‐B Manual Operation (From HMI): For the manual operation of the Filter, the HMI screen for the Automatic Media filter shall have soft push buttons for each mode of operation of the filter with respect to treatment. In Manual Operation, the filter will be set in Manual mode from the HMI with the soft switch and the desired function will be initiated e.g. Backwash, service, rinse, air scour from the soft push buttons. 1.2‐C Modes of Operation Automatic Filter has six motorized valves:
1. Service Inlet Valve (SIV) VM1001 2. Service Outlet Valve (SOV) VM1002 3. Backwash Inlet Valve (BIV) VM1003 4. Backwash Outlet Valve (BOV) VM1004 5. Rinse Valve (RNV) VM1006 6. Air Scour Valve (ASV) VM1005
We can divide the operation sequence of filter into two modes. This automatic sequence will be applicable only when the soft switch in the HMI screen for the Automatic Media Filter will be in Automatic operation position.
1. Service Mode: 2. Backwash Mode:
a. Drain b. Air Scour c. Backwash d. Rinse
1.2‐C‐1 SERVICE MODE: In this mode, Service inlet valve and service outlet valve will open. Where as, all other valves will be closed.
Service Inlet Service Outlet
Backwash Inlet
Backwash Outlet
Rinse Air Scour
OPEN OPEN CLOSE CLOSE CLOSE CLOSE
1.2‐C‐2 BACKWASH MODE: (Total Duration: 25 Minutes) The filters will be backwashed once the differential pressure switch closes to confirm the difference in pressure between the filter inlet and outlet point. Once the system is in backwash mode, the filter will further go into following four steps.
Step –1 DRAIN: (Duration: 3 Minutes) In this mode, Backwash outlet valve and rinse valve will open. Where as, all other valves will be closed.
Service Inlet Service Outlet
Backwash Inlet
Backwash Outlet
Rinse Air Scour
CLOSE CLOSE CLOSE OPEN OPEN CLOSE
Step –2 AIR SCOUR: (Duration: 3 Minutes)
In this mode, Backwash Outlet valve and Air Scour valve will open. Where as, all other valves will be closed. Air blower shall also run.
Service Inlet Service Outlet
Backwash Inlet
Backwash Outlet
Rinse Air Scour
CLOSE CLOSE CLOSE OPEN CLOSE OPEN
*See Air Blower. Step – 3 BACKWASH: (Duration: 14 Minutes)
In this mode, Backwash inlet valve and Backwash outlet valve will open. Where as, all other valves will be closed.
Service Inlet Service Outlet
Backwash Inlet
Backwash Outlet
Rinse Air Scour
CLOSE CLOSE OPEN OPEN CLOSE CLOSE
* See Filter Backwash Pumps. Backwash pump must run in the duration of step – 3 (backwash).
Step – 4 RINSE: (Duration: 5 Minutes) In this mode, Service inlet valve and Rinse valve will open. Where as, all other valves will be closed.
Service Inlet Service Outlet
Backwash Inlet
Backwash Outlet
Rinse Air Scour
OPEN CLOSE CLOSE CLOSE OPEN CLOSE
During rinse, the filter feed pump as assigned by the present changeover sequence will run. As soon as Rinse finishes the filters will go back to normal (Service) mode. 1.2‐D PROVISION OF MANUAL BACKWASH FROM HMI: The manual backwash from HMI system will be carried out as follows: The filter should be switched to Manual mode from the soft switch in the HMI Screen. The soft‐switch for manual backwash in the SCADA will get the filter and RO stream out from service mode. There will be soft‐pushbuttons for Drain, Air scour, Backwash and rinse in SCADA. During Rinse (Step –4) and Backwash (Step –3) in manual mode, the required pumps will also start/stop manually from the HMI. FAULTS AND ALARMS ACKNOWLEDGEMENTS: There is an open/close (built in limit switch) feedback fed from each valve to the PLC. Every time the valve opens or closes, the limit switch should give feedback within the preset time. Incase of failure of any valve there will be an alarm in the HMI and the system will go out of service. The Alarm screen will flash the faulty valve. The alarm must be acknowledged and cleared before the system goes back to service again.
1.3 FILTER BACKWASH PUMPS There are two Filter‐backwash pumps as follows. Filter Backwash pump – 1 / P1004 Filter Backwash pump – 2 / P1005 Filter‐backwash pumps operate in two modes: 1.3‐A Automatic Mode: The selector switch of each pump on the control panel should be in Remote position and HMI Auto position. Filter backwash pumps will run when the filter is in Backwash Mode (Step –3 Backwash). Backwash pump will operate in One duty / 1 standby fashion. Interlocks:
a. All backwash pumps will be interlocked with a low level switch in the Backwash tank to keep from dry – running.
b. Each backwash pump will be interlocked with overload signal, as in case of overload the pump must stop immediately.
1.3‐B Manual Mode: There are two cases in manual mode. CASE‐I The pumps can be operated manually either from the control room or the local station. From Control Room: The selector switch is in Remote position on the local control panel. The selector switch for the same pump in the HMI will be in manual. The pump will operate as long as the switch remains in manual. Incase of overload or low level in the tank, the pump will stop.
From Local Station: The selector switch will be in Local position in the control room, and the pump will operate with start/stop pushbuttons on the local station. TIP: The HMI will sense the operation of the pump in Manual as described above through the feedback signal to the PLC. FAULTS AND ALARMS ACKNOWLEDGEMENTS:
1. In case of pump failure during operation due to overload or no feedback signal the standby pump will automatically take over without stopping the sequence and there will only be a trip indication on the local panel in the control room. Alarm will be logged.
1.4 AIR BLOWER: There are two Air Blowers as follows. Air Blower / AB3001 Air blower operates in two modes:
1. Automatic Mode 2. Manual Mode
1.4‐A Automatic Mode: The selector switch on the control panel should be in Remote position and HMI Auto position. Air blower will run when a filter is in Backwash Mode (Step –2 Air Scour). In case of failure of the air blower during operation due to overload or by emergency stop. Alarm will annunciate and the fault lamp shall be lit. Interlocks:
a. The air blowers will be interlocked with overload signal, as in case of overload the blower must stop immediately.
1.4‐B Manual Mode: There are two cases in manual mode. CASE‐I The blowers can be operated manually either from the control room or the local station. From Control Room: The selector switch is in Remote position on the local control panel. The selector switch for the same blower in the HMI will be in manual. The blower will operate as long as the switch remains in manual. Incase of overload the blower will stop. From Local Station: The selector switch will be in Local position in the control room, and the pump will operate with start/stop pushbuttons on the local station.
TIP: The HMI system will sense the operation of the blower in Manual as described above through the feedback signal to the PLC. FAULTS AND ALARMS ACKNOWLEDGEMENTS:
1. In case of blower failure during operation due to overload or no feedback signal, there will only be a trip indication on the local panel in the control room. The alarm must annunciate.
SECTION ‐ 2 DOSING PUMPS
2.1 Operation Modes: Dosing pumps shall have a separate HMI screen with respective Auto off Manual Soft switches to allow both Auto and Manual operation modes. Dosing pumps will operate according to the following philosophy.
1. Pre‐chlorination 2. De‐chlorination 3. Acid 4. Antiscalant
2.2 Pre‐chlorination Dosing Pump: The pre‐chlorination dosing pump in Auto mode (HMI Soft Switch) and Remote from the dosing pump control panel will always be interlocked with the filter feed pumps auto operation. Whereas in case feed pumps are running in manual, the dosing pump should also be operated in manual in the same way from the HMI soft switch. 2.3 De‐chlorination & Antiscalant dosing pumps: Following cases shall be considered for the operation of De‐chlorination & Antiscalant dosing pumps. 2.3‐A Case‐1 The de‐chlorination and Antiscalant dosing pumps in Auto mode (HMI Soft Switch) and Remote from the dosing pump control panel will always be interlocked with the high pressure pump Auto operation in the respective stream.
2.3‐B Case‐2 The de‐chlorination dosing pump in Auto mode (HMI Soft Switch) and Remote from the dosing pump control panel will always be interlocked with the Auto operation of the filter feed pumps while the startup flushing or shutdown flushing (details will follow in the next chapter) of the respective RO streams is underway. Whereas in case high pressure pumps are running in manual, the dosing pumps should also be operated in manual in the same way from the HMI soft switch. * For case‐II, the Antiscalant dosing pump will not be considered. 2.4 Acid dosing pumps: Acid dosing pumps in Auto mode (HMI Soft Switch) and Remote from the dosing pump control panel will always be interlocked with the Auto operation of the high pressure pump of the respective stream. Whereas in case high pressure pumps are running in manual, the dosing pumps should also be operated in manual in the same way from the HMI soft switch.
SECTION – 3
FIRST PASS RO STREAMS
3.1 STAGES OF OPERATION: The RO sequence can be broken down to three stages considering startup till shutdown as below:
1. Startup flushing 2. Service 3. Shutdown flushing
The RO system consists of two streams and each includes following automatic components.
1. De‐chlorination dosing Pump (As described in previous Section) 2. Antiscalant Dosing pump (As described in previous Section) 3. Acid dosing pump (As described in previous Section) 4. High Pressure Pump / P1006A , P1007B 5. Feed Motorized Valve / VM1007A, VM1010B 6. Dump Motorized Valve / VM1008A, VM1011B 7. Flush Motorized Valve / VM1009A, VM1012B 8. 1st Pass Break Tank Level Switch / LS2001
3.2 GENERAL OPERATION PHILOSOPHY OF RO SYSTEM: For the normal operation, the Filter Feed pumps are put in auto mode (HMI SOFT SWITCHES) and Remote position on the control panel, the High‐Pressure Pump is also put in auto (HMI SOFT SWITCH) and remote on the control panel, Feed line Motorized valve, Flush Line Motorized Valve are ready to receive open signal and the unit will go in operation.
3.2‐A STARTUP FLUSHING At first, startup flushing occurs for preset time duration (2 min) considering adequate pressure built up before the system goes to service. In startup flushing, only feed pumps run, de‐chlorination dosing pumps will inject SBS, feed line and flush‐motorized valves are open. 3.2‐B SERVICE After startup flushing, the unit goes into Service. High‐pressure pump starts. Antiscalant and Acid dosing initiates whereas the de‐chlorination continuingly remains active. Flush Motorized valve closes. 3.2‐C SHUTDOWN FLUSHING Thus, the system in service keeps topping up the 1st Pass Break tank until the high level is reached. At this moment when the tank is topped up fully as limited by the level switch, the unit goes into Shutdown Flushing. During shutdown flushing the high‐pressure pump stops. Acid and Antiscalant dosing shall be inactive. Feed pump for the respective stream will run continuingly whereas the flush motorized valve will open again. The unit undergoes shutdown flushing for the preset duration (e.g. 4 minutes). After the shutdown flushing the system is ideal until the 1st Pass Break tank (Product tank) level goes down to a preset level. 3.2‐D FAULT SHUTDOWN Fault shutdown occurs in the following three conditions:
a) Very Low/High Pressure
When the pressure in the system is below the low‐pressure set point or above the high‐pressure set point the system will shutdown right away with the fault indication and alarm without shutdown flushing. Feed pumps, High‐pressure pump and all the dosing pumps will stop.
b) HIGH ORP
When the ORP value reaches the upper limit (Preset 375mV), the system will immediately shutdown without shutdown flushing, dump motorized valve will open whereas, feed pumps, high pressure pump and dosing pumps will stop. The feed line Motorized valve closes. There is an alarm with fault indication.
c) Low level Feed Tank
Incase there is low level (20 %) in the Raw Water Tank, the whole system stops immediately without shutdown flushing with Fault Indication and Alarm.
3.2‐E ALARM
Generated Alarm is going to be logged in the HMI system. The nature of alarm can also be interpreted from relative parameters.
3.3 HIGH PRESSURE PUMP There is one high‐pressure pump in each stream as follows. High Pressure Pump – Stream A / P1006A High Pressure Pump – Stream B / P1007B High Pressure pumps operate in two modes: 3.3‐A Automatic Mode: The selector switch of the pump on the local control panel should be in Remote position and HMI Auto position. Interlocks:
a) High Pressure pump will be interlocked with the filter feed pump operation as the filter feed pump must be running when the high pressure pump is in operation.
b) The high‐pressure pump will be interlocked with overload signal, as in case of overload the pump must stop immediately.
3.3‐B Manual Mode: There are two cases in manual mode. CASE‐I The pumps can be operated manually either from the control room or the local station. From Control Room: The selector switch is in Remote position on the control panel. The selector switch for the same pump in the HMI will be in manual. The pump will operate as long as the switch remains in manual. Incase of overload or low level in the tank, the pump will stop.
From Local Station: The selector switch will be in Local position in the control room, and the pump will operate with start/stop pushbuttons on the local station near by. TIP: The HMI will sense the operation of the pump in Manual as described above through the feedback signal to the PLC. FAULTS AND ALARMS ACKNOWLEDGEMENTS:
a) In case of pump failure during operation for any stream due to overload, the respective pump must immediately stop and the stream will be out of service with alarm and fault indication.
b) The alarm must be acknowledged and Reset in order to bring the system back
in operation.
SECTION – 4 SECOND PASS RO STREAMS
4.1 GENERAL DESCRIPTION: The second pass RO operates when the high‐pressure pump is in Auto mode (HMI Soft switch) and the Flush motorized valve is ready to operate automatically for the respective stream. The Second pass RO consists of following automatic components.
1. High Pressure Pumps / P2001A, P2002B 2. Flush Motorized Valve / VM2001A, VM2002B 3. Mixed Bed Feed Tank Level Switch / LS3001
4.1‐A STARTUP Every time the unit starts, the flushing motorized valve will open for 2 minutes startup flushing where as the high pressure pump will remain stopped. After startup flushing, flush‐motorized valve will close and the high pressure pump will start and continue till the Mixed Bed tank is topped up and there is no low level in the 1st pass break tank or until and unless the high pressure pump is switched off from the Automatic operation. 4.1‐B SHUTDOWN There will be two cases in the shutdown of the plant as follows. CASE‐I When the high‐pressure pump is switched from remote to off position or from Auto to off position in the HMI, the high‐pressure pump will immediately stop and the flush motorized opens again for 4 minutes. After 4 minutes the flush‐motorized valve is closed and the system is ideal. CASE‐II The high level is reached in the Mixed bed Tank, the system will undergo the same shutdown sequence as in Case‐I. 4.2 HIGH PRESSURE PUMP
There is one high‐pressure pump in each stream as follows. High Pressure Pump – Stream A / P2001A High Pressure Pump – Stream B / P2002B High Pressure pumps operate in two modes: 4.2‐A Automatic Mode: The selector switch of the pump on the local control panel should be in Remote position and HMI Auto position. Interlocks:
The high‐pressure pump will be interlocked with overload signal, as in case of overload the pump must stop immediately. 4.2‐B Manual Mode: There are two cases in manual mode. CASE‐I The pumps can be operated manually either from the control room or the local station. From Control Room: The selector switch is in Remote position on the control panel. The selector switch for the same pump in the HMI will be in manual. The pump will operate as long as the switch remains in manual. Incase of overload or low level in the tank, the pump will stop.
From Local Station: The selector switch will be in Local position in the control room, and the pump will operate with start/stop pushbuttons on the local station near by. TIP: The HMI will sense the operation of the pump in Manual as described above through the feedback signal to the PLC. FAULTS AND ALARMS ACKNOWLEDGEMENTS:
a) In case of pump failure during operation for any stream due to overload, the respective pump must immediately stop and the stream will be out of service with alarm and fault indication.
b) The alarm must be acknowledged and Reset in order to bring the system back
in operation. 4.3 FAULT SHUTDOWN Fault shutdown occurs in the following three conditions:
a) Very Low/High Pressure
When the pressure in the system is below the low‐pressure set point or above the high‐pressure set point the system will shutdown right away with the fault indication and alarm without shutdown flushing. Feed pumps, High‐pressure pump and all the dosing pumps will stop.
b) Low level Feed Tank
Incase there is low level (20 %) in the 1st Pass Break Tank, the whole system stops immediately without shutdown flushing with Fault Indication and Alarm.
4.3‐A ALARM Generated Alarm is going to be logged in the HMI system. The nature of alarm can also be interpreted from relative parameters.
5. DEMIN SEQUENCE
DEMIN Sequence controls the level of the DEMIN Water Tank. It controls the operation of:
1. Second Pass RO Product transfer Pumps 2. Service/Regeneration Sequence of MB
5.1.1 DEMIN Sequence Start‐up
S. No Description Permissive
1 MB goes to service mode i.e., Service Inlet opens and Service Outlet opens. All other valves remain closed
2 Mixed Bed Feed Pump starts.
There is enough level in the mixed bed feed tank
3 MB goes to Regeneration Sequence Conductivty HIGH
5.1.2 DEMIN Sequence Shutdown
S. No Description Alarms 1 Mixed Bed Feed pump stops 2 Service Inlet and outlet valves of MB will be
closed
DEMIN water tank level High‐High (= 98.7%) (Signal by Others)
5.2 Mixed Bed Exchangers – P&ID REF. ‐ M72235‐01‐001/REV 5 5.2.1 System Description
The Mixed Bed Exchangers receive Water supply from the Mixed Bed Feed Tank through the Mixed Bed Feed Pumps P3001, P3002. The normal operation of the Exchanger shall be in Automatic mode.
Instruments: Conductivity Analyzer TC3002, Flow meter TDPF3001, TDP3001
HMI: Auto‐Off‐Manual Modes, Process Sequence Indications
Alarms: Permeate Conductivity High High.
5.2.2 Controls
AUTO:
In Auto mode the MB Exchanger shall be in Service whenever the demand from DEMIN Water Storage Tank (Product) is activated and liquid level in Mix Bed Feed Tank is above low level. The Exchanger operates in service till the high level signal is received from the DEMIN water tank (By others). The exhausted Exchanger then shifts to standby and goes through process of Regeneration.
MANUAL:
The MB can be put in Service in this mode irrespective of the Mixed Bed Product Demand and the feed pumps shall also be operated in Manual.
Regeneration:
Before MB goes to regeneration operator will be prompted a message to select whether it is to be performed in Auto Sequence or Step Sequence after confirmation the regeneration will takes place.
TC3002 is used to monitor permeate conductivity of MB Exchanger and in case of High High alarm set at 0.2 µS/cm the MB goes to regeneration sequence.
TDPF3001 is used to monitor permeate flow.
5.2.3 Service& Regeneration Sequence Of Mixed Bed Exchanger
S. No. DESCRIPTION TIME MIN.
SI
VD
3001
SO
VD
3002
BWI
VD
3003
BWO
VD
3004
MCI
VD
3005
MCO
VD
3006
RO
VD
3010
AI
VD
3009
CI
VD
3007
ACI
VD
3008
DRIVE
Fluid/Flow
1 Middle Collector Flush 3 O O REGN. PUMP
2 B/W 10 O O REGN. PUMP
3 Chemical Injection 30 O O O ACID, CAUSTIC R. PUMP
4 Chemical Rinse 30 O O O REGN. PUMP
5 Drain Down 10 O O ‐‐‐‐
6 Air Scouring 5 O O AIR BLOWER
7 Refill 2 O O MB FEED PUMP
8 Final Rinse 45 O O MB FEED PUMP
9 Pre‐Rinse 10 O O MB FEED PUMP
10 Service O O MB FEED PUMP
SI: Service Inlet, SO: Service outlet, BWI: Backwash Inlet, BWO: Backwash Outlet, MCI: Middle Collector Inlet, MCO: Middle Collector Outlet, AI: Air Inlet, CI: Caustic Inlet, RO: Rinse Outlet, ACI: Acid Inlet
5.4 MIXEDBED FEED PUMPS There are two mixed bed feed pumps as follows. Mixed Bed Feed pump – 1 / P3001 Mixed Bed Feed Pump – 2 / P3002 Mixed Bed feed pumps operate in two modes: 5.4.1 Automatic Mode: The selector switch of each pump on the local control panel should be in Remote position and HMI Auto position. Mixed Bed feed pumps in Auto mode will be running in two cases. CASE – I Mixed Bed Feed pumps will run in 1 Duty/ 1 Standby fashion when Mixed Bed system is in Service i.e. normal operation. Incase of failure of pump in any case, the alternate (Standby) pump will take over and there will be a trip indication for the faulty pump. CASE – II When a Mixed Bed system undergoes Refill, Final Rinse and Pre Rinse the Mixed Bed Feed pump shall run. Interlocks:
c) Both Mixed Bed feed pumps will be interlocked with a low level switch in the Mixed Bed Feed Tank to keep from dry – running.
d) Both pumps will be interlocked with overload signal, as in case of overload the pump must stop immediately.
5.4.2 Manual Mode: There are two cases in manual mode. CASE‐I The pumps can be operated manually either from the control room or the local station.
From Control Room: The selector switch is in Remote position on the control panel. The selector switch for the same pump in the HMI will be in manual. The pump will operate as long as the switch remains in manual. Incase of overload or low level in the tank, the pump will stop. From Local Station: The selector switch will be in Local position in the control room, and the pump will operate with start/stop pushbuttons on the local station near by. TIP: The HMI will sense the operation of the pump in Manual as described above through the feedback signal to the PLC. FAULTS AND ALARMS ACKNOWLEDGEMENTS: 1 In case of pump failure during operation due to overload, the respective standby pump will
automatically take over without stopping the plant and there will only be a trip indication on the local panel in the control room. The alarm will be logged.
2 In case, when both pumps fail, the fault lamp should be lit and alarm must annunciate. The
system will shutdown, all the valves will close. 5.5 Regeneration Water Pumps (P3003, P3004) 5.5.1 System Description
The Pumps draw water from the Mixed Bed Feed tank and supply to Mixed Bed Exchanger. They shall be operated as 1 Duty and 1 Standby. The normal operation of the Pumps shall be in Automatic mode, where they operate to carry out Regeneration functions of the Mixed Bed Exchanger. Alarms: Conductivity High High
Reference Summary
A One Pump shall start whenever there is a demand from the MB for regeneration is activated/conductivity increases more than 0.2 µS/cm or when the preset amount of treated water is achieved and Auto Mode is selected from HMI.
B Standby pump shall be started automatically when Duty pump is Tripped or Failed to start
C Pumps can be manually started from HMI operator station by selecting the Manual mode or by having selector switch in LOCAL and with Start/stop push buttons.
D Feed tank Low‐Low level interlock is provided if the pumps starts in Auto/Manual Modes
Auto: In Auto mode the Pumps start 1 duty at a time whenever the demand from the Mixed Bed Exchanger is activated. The Pumps start if Exchanger shall go in the Chemical Injection, Chemical Rinse – Regeneration steps. The pumps shall changeover during every fresh start.
Manual Operation:
The Pumps can be operated in Manual mode from HMI Operator station by selecting Manual Mode, keeping the selector switch in Remote on MCC. When started from the HMI the Low‐Low‐level protection LALL shall be active.
Demin Shutdown Logic
Alarm Alarm Tag Preset Values
Time Delay
Action
Mixed Bed Feed Tank LOW LOW LEVEL.
LS3001 10% 2 secondsDemin Sequence
Shutdown
No demand of Product (By Others)
‐ ‐ 2 secondsDemin Sequence
Shutdown
MB permeate conductivity High High
TC3001 0.2
µS/cm 60
seconds MB goes to regeneration
MB Diff Pressure HIGH
TDP3001 5psi 20
seconds MB goes to regeneration