PRE CONDITION OF THE UNIT:
1. Unit is running at full load (500MW) with 7 mills in operation.
2. Both TDBFPs are in service and Feed water control in auto.
3. MDBFP # C is available on auto (Rapid start up mode).
4. Airflow control is in auto with both FD fans in service.
5. Both PA fans in service in CAS mode.
6. Unit control is in CMC mode.
7. Both ID fans in service and furnace draft control in auto.
ENSURE THE FOLLOWING:
1. Revise the station DC as per the planned shut down programme.
2. Bypass FD fan discharge gate close permissive from remote when fan in running condition to trip the fan
on fan running and discharge gate close protection.
3. FD fan trip from ID fan trip and ID fan trip from FD fan trip protections are to be bypassed.
4. Ensure the running contact of other set ID fan & FD fan .
5. Availability of atomizing steam and HFO at requisite pressure & temp (oil: 100ºC / 17-18 kg/cm², Steam:
200 – 210ºC / 6.5 kg/cm²).
6. Completion of WB/LRSB operation before starting the load reduction.
7. Availability of PAPH / SAPH soot blowers for operation.
8. Ensure the power supply healthiness of the ID fan inlet and outlet dampers.
9. Best communication between control room and local.
10. TDBFP- A/ B recirculation valve auto-closing protection is to be taken care
PROCEDURE FOR ID FAN UNLOADING, STOPPING AND ISOLATION:
1. Take the unit control to manual from CMC mode. (Turbine on limit pressure control and Boiler master on manual).
2. Take airflow control to manual.
3. Take fuel master to manual and gradually reduce the load to 400MW by slowly unloading and removing 7th running mill. Adjust airflow according to the load (1650T/ hr corresponding to 400MW).
4. Take HFO support in one elevation corresponding to any running mill according to the mill combination (At least 3 oil guns in one elevation).
5. Gradually reduce the load to 350 MW by slowly unloading and removing 6th running mill. Adjust airflow according to the load (1450T/ hr corresponding to 300MW).
6. Reduce MS pressure set point according to the load during the process of load reduction.
7. Check the loading and suction flow of TDBFP A / B. If suction flow is low corresponding to the speed, Then keep open any one TDBFP- A / B recirculation valve.
8. Probably kept five consecutive mills in service to ensure stable combustion.
9. Adjust the burner tilt position to maintain MS & HRH temperature up to maximum possible (540C).10. Take blade pitch control of corresponding FD fan into manual and slowly unload and, then stop the fan from fan running and discharge gate close protection by giving close command to its discharge gate.
11. Take IGV / speed control of the ID fan (which is to be stopped) into manual and gradually unload the fan by observing furnace draught and running ID fan will take load in auto.
12. Gradually unload the ID fan (which is to be stopped) and stop it. Other ID fan takes some load in auto. If required, It can be further loaded manually by observing the furnace draught, speed and current.
13. Ensure the auto closing operation of ID fan inlet and outlet dampers after stopping the fan. If not closed in auto, immediately close it from local. Then isolate the power supply of suction damper & discharge damper and lock it mechanically.
14. Check the furnace to wind box DP and furnace combustion stability.
15. Adjust the FG outlet damper positions of PAPH – A / B and SAPH – A / B after stabilization of load.
16. Start PAPH – A / B and SAPH – A / B soot blowing. (This is to be done at least twice in a shift as long as oil guns in service).
17. After stopping one of the ID fan, Gradually increase the load up to 350MW with 5 mills operation and simultaneously increase the loading of the running ID fan, which is having reserve margin with both channels in service (Check current, vibration, speed and bearing temperature).
18. Close one of the TDBFPs recirculation valve, which was kept opened previously after sufficient loading of TDBFPs.
19. Remove oil support after stabilisation of load at approximately 350MW with 5 mills operation.
20. Isolate the Main motor channel 1& 2 power supply (Both source breaker ). Depending on the
requirement the control supply to VFD can be isolated .
21. Press the local EPB.
22. Isolate the inlet guide vane (IGV) actuator power supply.
23. Stop lube oil system and isolate as per requirement.
24. Issue PTW after ensuring proper isolation according to PTW procedure.
PROCEDURE FOR NORMALISATION, STARTING AND LOADING OF ID FAN:
1. Ensure the cancellation of PTW and clearance from maintenance BMD/EMD/C&I, then normalise the fan motor power supply. (Both channel 1 & 2)
2. Revise the station DC as per the planned programme.
3. Remove the ID fan suction and discharge damper mechanical locking and normalise the power supply.
4. Normalise the IGV power supply. Release the local EPB.
5. Line up lube oil system and take it into service.
6. Line up and charge cooling water for motor, fan bearings and lube oil coolers.
7. Reset all alarms in VFD room if any thing is pending .
8. Start the ID fan with IGV minimum position and ensure opening of suction and discharge gates .
Gradually load the ID fan by increasing IGV position and speed, simultaneously observe the furnace
draught (Other running ID fan will unload in auto). If required maintain furnace draft by taking draft control into manual.
9. Balance the loading of the two ID fans by adjusting their IGV & Speed and put them in CAS mode.
10. Start second FD fan and load it slowly.
11. Put airflow control in auto.
12. Take 6th mill into service and gradually increase the load to 450MW.13. Adjust the MS pressure set point according to the variation of load.
14. Take 7th mill into service and increase the load to full (500MW).15. Adjust the FG outlet damper positions of PAPH – A / B and SAPH – A / B after stabilization of load.
16. Adjust the burner tilt to maintain M S & HRH temperature up to maximum possible (540C).17. Normalise the TDBFP – A / B recirculation control valve auto close protection.
18. Normalise the FD fan to ID fan trip and ID fan trip to FD fan trip protections.
19. Normalise FD fan discharge gate close permissive from remote when fan in running condition which wasbypassed to trip the fan on fan running and discharge gate close protection.
20. Put fuel master in auto.
21. Take unit control in to CMC mode.
1. Unit is running at full load (500MW) with 7 mills in operation.
2. Both TDBFPs are in service and Feed water control in auto.
3. MDBFP # C is available on auto (Rapid start up mode).
4. Airflow control is in auto with both FD fans in service.
5. Both PA fans in service in CAS mode.
6. Unit control is in CMC mode.
7. Both ID fans in service and furnace draft control in auto.
ENSURE THE FOLLOWING:
1. Revise the station DC as per the planned shut down programme.
2. Bypass FD fan discharge gate close permissive from remote when fan in running condition to trip the fan
on fan running and discharge gate close protection.
3. FD fan trip from ID fan trip and ID fan trip from FD fan trip protections are to be bypassed.
4. Ensure the running contact of other set ID fan & FD fan .
5. Availability of atomizing steam and HFO at requisite pressure & temp (oil: 100ºC / 17-18 kg/cm², Steam:
200 – 210ºC / 6.5 kg/cm²).
6. Completion of WB/LRSB operation before starting the load reduction.
7. Availability of PAPH / SAPH soot blowers for operation.
8. Ensure the power supply healthiness of the ID fan inlet and outlet dampers.
9. Best communication between control room and local.
10. TDBFP- A/ B recirculation valve auto-closing protection is to be taken care
PROCEDURE FOR ID FAN UNLOADING, STOPPING AND ISOLATION:
1. Take the unit control to manual from CMC mode. (Turbine on limit pressure control and Boiler master on manual).
2. Take airflow control to manual.
3. Take fuel master to manual and gradually reduce the load to 400MW by slowly unloading and removing 7th running mill. Adjust airflow according to the load (1650T/ hr corresponding to 400MW).
4. Take HFO support in one elevation corresponding to any running mill according to the mill combination (At least 3 oil guns in one elevation).
5. Gradually reduce the load to 350 MW by slowly unloading and removing 6th running mill. Adjust airflow according to the load (1450T/ hr corresponding to 300MW).
6. Reduce MS pressure set point according to the load during the process of load reduction.
7. Check the loading and suction flow of TDBFP A / B. If suction flow is low corresponding to the speed, Then keep open any one TDBFP- A / B recirculation valve.
8. Probably kept five consecutive mills in service to ensure stable combustion.
9. Adjust the burner tilt position to maintain MS & HRH temperature up to maximum possible (540C).10. Take blade pitch control of corresponding FD fan into manual and slowly unload and, then stop the fan from fan running and discharge gate close protection by giving close command to its discharge gate.
11. Take IGV / speed control of the ID fan (which is to be stopped) into manual and gradually unload the fan by observing furnace draught and running ID fan will take load in auto.
12. Gradually unload the ID fan (which is to be stopped) and stop it. Other ID fan takes some load in auto. If required, It can be further loaded manually by observing the furnace draught, speed and current.
13. Ensure the auto closing operation of ID fan inlet and outlet dampers after stopping the fan. If not closed in auto, immediately close it from local. Then isolate the power supply of suction damper & discharge damper and lock it mechanically.
14. Check the furnace to wind box DP and furnace combustion stability.
15. Adjust the FG outlet damper positions of PAPH – A / B and SAPH – A / B after stabilization of load.
16. Start PAPH – A / B and SAPH – A / B soot blowing. (This is to be done at least twice in a shift as long as oil guns in service).
17. After stopping one of the ID fan, Gradually increase the load up to 350MW with 5 mills operation and simultaneously increase the loading of the running ID fan, which is having reserve margin with both channels in service (Check current, vibration, speed and bearing temperature).
18. Close one of the TDBFPs recirculation valve, which was kept opened previously after sufficient loading of TDBFPs.
19. Remove oil support after stabilisation of load at approximately 350MW with 5 mills operation.
20. Isolate the Main motor channel 1& 2 power supply (Both source breaker ). Depending on the
requirement the control supply to VFD can be isolated .
21. Press the local EPB.
22. Isolate the inlet guide vane (IGV) actuator power supply.
23. Stop lube oil system and isolate as per requirement.
24. Issue PTW after ensuring proper isolation according to PTW procedure.
PROCEDURE FOR NORMALISATION, STARTING AND LOADING OF ID FAN:
1. Ensure the cancellation of PTW and clearance from maintenance BMD/EMD/C&I, then normalise the fan motor power supply. (Both channel 1 & 2)
2. Revise the station DC as per the planned programme.
3. Remove the ID fan suction and discharge damper mechanical locking and normalise the power supply.
4. Normalise the IGV power supply. Release the local EPB.
5. Line up lube oil system and take it into service.
6. Line up and charge cooling water for motor, fan bearings and lube oil coolers.
7. Reset all alarms in VFD room if any thing is pending .
8. Start the ID fan with IGV minimum position and ensure opening of suction and discharge gates .
Gradually load the ID fan by increasing IGV position and speed, simultaneously observe the furnace
draught (Other running ID fan will unload in auto). If required maintain furnace draft by taking draft control into manual.
9. Balance the loading of the two ID fans by adjusting their IGV & Speed and put them in CAS mode.
10. Start second FD fan and load it slowly.
11. Put airflow control in auto.
12. Take 6th mill into service and gradually increase the load to 450MW.13. Adjust the MS pressure set point according to the variation of load.
14. Take 7th mill into service and increase the load to full (500MW).15. Adjust the FG outlet damper positions of PAPH – A / B and SAPH – A / B after stabilization of load.
16. Adjust the burner tilt to maintain M S & HRH temperature up to maximum possible (540C).17. Normalise the TDBFP – A / B recirculation control valve auto close protection.
18. Normalise the FD fan to ID fan trip and ID fan trip to FD fan trip protections.
19. Normalise FD fan discharge gate close permissive from remote when fan in running condition which wasbypassed to trip the fan on fan running and discharge gate close protection.
20. Put fuel master in auto.
21. Take unit control in to CMC mode.
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