Hot start-Up(Within 8 Hours)

Hot start-Up(Within 8 Hours)

Stopping- Starting of 2nd PAPH

Stopping- Starting of 2nd PAPH

Each unit is provided with two bi-sector type regenerative primary air preheaters to recover the

heat from waste flue gas leaving from the furnace and utilised to preheat the primary air which inturn

used to dry the raw coal and transport pulverised coal powder from mill to the furnace through coal pipes.

Air pre-heater consists mainly rotor housing, cylindrical cellular rotor, guide and Support bearings, oil

systems for guide and support bearings, soot blower system, Stationary water washing devices & fire

fighting devices , auxiliary air motor drive with over-running clutch, oil carryover probe , inspection lights s

etc. The complete rotor is supported by a thrust bearing at the bottom and guided by the radial bearing at

the upper end. An air motor is provided to ensure the continued operation of the air pre-heater, even if

power to electric motor is interrupted. It may also be used to control speed of the rotor during water

washing of heating surfaces.

When ever one APH trips in a running Unit the run back operates & Unit load gets

reduced to 300 MW( 60 %) . Normally 4-5 Mill operation permissive is available with one APH out

of service .

PROCEDURE FOR STOPPING AND ISOLATION OF ANY SECOND PAPH: -

E-1 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. Unit control is in CMC mode.

5. Airflow control is in auto with both FD fans in service.

6. Both PA fans in operation in CAS mode with PA header pressure set at 820mmwc.

7. Both ID fans in service and furnace draft control in auto.

E-2 ENSURE THE FOLLOWING:

1. Running contact of other running PAPH.

2. Revise the station DC as per the planned shut down programme.

3. Availability of PAPH / SAPH soot blowers for operation.

4. Availability of auxiliary drive (air motor) of the PAPH (which is to be stopped).

5. All (4nos) economizer bypass dampers are closed.

6. Availability of atomizing steam and HFO at requisite pressure & temp (oil: 100ºC / 17-18 kg/cm², Steam:

200 – 210ºC / 6.5 kg/cm²).

7. Completion of WB/LRSB operation before starting the load reduction.

8. Best communication between control room and local.

9. Bypass TDBFP – A / B recirculation valve auto-closing protection.

10. Check for the healthiness of the mill outlet temperature low to feeder tripping protection for all running

mills, Normally it is set at 50 deg C.

PAPH STOPPING AND ISOLATION PROCEDURE: -

1. Take the unit control to manual from CMC mode. (Turbine on limit pressure control and Boiler master on

manual).

2. Take fuel master to manual and gradually reduce the load to 400MW by slowly unloading and removing

7th running mill. Check airflow according to the load (1650T/ hr corresponding to 400MW).

3. Take HFO support in one elevation corresponding to any running mill according to the mill combination

(At least 3 oil guns in one elevation).

4. Gradually reduce the load to 300MW by slowly unloading and removing 6th running mill. Check airflow

according to the load (1450T/ hr corresponding to 300MW).

5. Reduce MS pressure set point according to the load during the process of load reduction.

6. 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.

7. Probably keep five consecutive mills in service to ensure stable combustion.

8. Observe and slowly reduce the PA header pressure set to 800mmwc from 850mmwc.

9. Adjust the burner tilt position to maintain MS & HRH temperature up to maximum possible (540C).

10. Gradually close the PAPH (which is to be stopped) air outlet damper from local & lock it mechanically

and simultaneously maintain the flue gas outlet temperature by closing the FG outlet damper of

corresponding PAPH. Adjust the other running PAPH & SAPH A/B FG outlet temperature from remote.

Then isolate the air outlet damper actuator power supply. This activity needs best communication

between control room and local.

11. Check the PA header pressure for any variation while closing air outlet damper and adjust it, if required.

12. Slowly close the air inlet damper from local and lock it mechanically. Isolate the power supply.

13. Observe the mill outlet temperature and accordingly adjust mill loading.

14. Close flue gas inlet damper from local and lock it mechanically. Isolate the power supply.

15. Close flue gas outlet damper from remote fully and lock it mechanically. It can be opened to 10% with the

help of C& I to create negative draft in side the APH if it is required by BMD.

16. Observe the mill outlet temperature and APH flue gas outlet temperatures accordingly adjust the running

PAPH & SAPH – A / B flue gas outlet dampers.

17. Start running PAPH and SAPH – A / B soot blowing. (This is to be done at least twice in a shift as long as

oil guns in service).

18. After stopping the PAPH, Gradually increase the load to approximately 330MW with 5 mills operation by

observing PA outlet temperature, mill outlet temperature and PA header pressure.

19. Remove oil support after stabilisation of load at approximately 330MW with 5 mills operation with safe

mill outlet temperature (Should be >60ºC).

20. Keep PRAPH in service for attending any work outside the APH like air outlet duct fabric compensator

repair work.

21. Stop the PAPH (which is to be stopped) after cooling (air outlet side manhole can be kept open for

cooling) to normal temperature so that maintenance can be done and isolate the power supply of PRAPH

drive motor.

22. Close both main and bypass airlines for air motor.

23. Press the local EPB of the PAPH (which is stopped).

24. Issue PFW after ensuring proper isolation according to PFW procedure.

E-4 PROCEDURE FOR NORMALISATION AND STARTING PRAPH: -

1. Revise the station DC as per the planned programme.

2. Ensure the cancellation of PTW and clearance from maintenance BMD/EMD/C&I, then normalise the

drive motor power supply.

3. Check the PAPH for proper boxup (check all manholes are closed).

4. Check the PAPH by running air motor for any abnormal rubbing.

5. Normalise the drive motor power supply.

6. Release the local EPB.

7. Stop PAPH air motor and start main electric motor.

8. Normalise the air outlet damper power supply. Remove the lock and slowly open the PAPH air outlet

damper from local.

9. Normalise the flue gas inlet damper power supply. Remove the lock and slowly open the PAPH flue gas

inlet damper from local.

10. Slowly Increase the PA header pressure set point to normal (820mmwc) and wait for stabilisation of the

header pressure.

11. Normalise the air inlet damper power supply. Remove the lock and slowly open the air inlet damper from

local. Simultaneously open flue gas outlet damper from remote and maintain the flue gas outlet

temperature and observe PA header pressure while opening air inlet damper.

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. Close TDBFP-A / B recirculation valve (which was kept opened previously) after sufficient loading of both

TDBFPs.

15. Take 7th mill into service and increase the load to full (500MW).

16. Adjust the FG outlet damper positions of PAPH – A / B and SAPH – A / B after stabilization of load.

17. Adjust the burner tilt to maintain M S & HRH temperature up to maximum possible (540C).

18. Normalise the TDBFPs recirculation control valve auto close protection.

19. Put fuel master in auto.

20. Transfer the unit control from manual to CMC mode.

BCW Pump

BCW Pump
STARTING THE BCW PUMP : -
F.1 PRE START CHECKS BEFORE INITIAL STARTING OF THE PUMP
1 Boiler Drum is filled & drum level is maintained on positive side (+200 mm) for starting first
pump.
2 SGECW System & BCW Booster Pump is in service.
3 Emergency over head tank level OK.
4 Ensure that pump & pump cooler is completely vented.
5 Start permissive is available.
6 LP cooling water valves are open and the cooling water flow is > 75 LPM.
7 All other valves must be closed.
8 LP & HP purge lines are charged and purge line valve to motor is in closed condition.
9 Check for any water leakage from pump instruments, cooler vent, pump & motor assembly.
10 With water filled, the insulation resistance measured at the terminal links, using a 1000V
megger must exceed 200 mega ohms.
START PERMISSIVE
1 No Switchgear disturbance.
2 Switchgear Available
3 Drum N2 Vent Valves Closed.
4 Motor Cavity Temp Not high (57° C).
5 Suction Manifold / Casing DT not high (< 38° C).
6 BCW P/P Cooling Water Flow Adequate (> 75 LPM).
7 BCW P/P Not Tripped.
8 Both Discharge v/v Stem open.
9 When a boiler is started from cold, a minimum of two BCW pumps must be operated. It is
normal practice to start all the three pumps before boiler light up
Starting of pumps
1 Start the first pump
2 Motor current will drop from full starting current after few seconds to normal & there is no
hunting in current.
3 Ensuring Drum level is normal start second pump (after starting of pump it tends to dip).
4 Differential pressure should rise immediately to approx. 3.1 kg/sec².
5 Check with local operator about any abnormal sound from pump.
6 Ensure for the standby pump that DT between pump casing & boiler water is within 56° C.
7 Caution –If motor fails to start after 5 seconds, press stop button & do not attempt to
start the pump for 20 minutes.
FOR STANDBY BCW PUMP:
1 Close the service valve in pump jumper line & open the pump discharge by-pass valve. This
ensures that as the boiler heats up, a flow passes from the discharge legs to the pump case &
impeller.
2 Check the motor cavity temperature is not exceeding 49 ° C.
3 In such a case take the pump in service & close pump discharge by-pass valve & open the
pump jumper line service valve.
ISOLATION PROCEDURE
There is no provision to isolate the pump in boiler lighted up condition as no isolation
v/v is provided in suction line, only two manual v/v are provided in the two discharge
lines.
PROTECTIONS
1 PUMP Motor Cavity Temperature Very High with a time delay of 5 sec (> 60 ° C).
2 Discharge Valve Stem-1 not open
3 Discharge Valve Stem-2 not open

BAHP -BALP

BAHP -BALP

Low pressure ash water system caters water at the following areas (BALP pumps):

1. Ash slurry sump makeup.

2. Ring header for seal trough makeup / flushing.

3. Refractory cooling supply.

4. Bottom ash hopper makeup / filling.

5. Bottom ash hopper window spray.

6. Make up to overflow settling bin.

High pressure water pump caters water at the following areas (BAHP pumps):

1. Jet pump fitted below the clinker crusher at the bottom ash hopper.

2. Jetting water requirement for bottom ash hopper.

3. HP line water supply to feeder ejector and slurry box of economizer and economizer

bypass system.

4. HP line to economizer ash transfer hopper for jetting purposes.

5. HP line to jet pump fitted below the economizer ash transfer hopper.

6. HP line bypass connection to bottom ash hopper refractory cooling water and ring

header for seal trough make up / flushing water line.

7. Flushing connections to bottom ash hopper overflow weir boxes.

8. Line for flushing sludge pump discharge lines.

Flushing water pump:

1. The flushing water pumps are provided for slurry disposal line flushing purpose.

Sump jetting water pumps caters at the following areas:

1. Ash slurry sump jetting.

2. Common ash slurry trough jetting arrangement.

Control Fluid system

Control Fluid system
Control fluid (A fire resistant fluid) is used as operating media for oil operated HP & IP stop /
control valves. This control fluid system also supplies control fluid as operating media for LPBP
stop & control valves. The control fluid system contains two 100 % capacity pumps with double
discharge i.e. LP control fluid delivered at 8 bar pressure from the 1st stage of the pump and HP
control fluid delivered at 32 bar pressure from the pump 4th stage, two coolers (one being standby).
There is no common filter, each sub system has got its own Duplex or rotating filters. CF
tank is provided with two oil vapour exhausters, which extracts non condensable gases from the
tank and expels to atmosphere. There is a temperature control valve which Controls oil
temperature by controlling oil flow through the cooler. There is an electrical heater provided in the
control fluid tank to maintain the oil temperature between 55 and 57ºC.
Heater gets ON - If CF temperature in tank < 55ºC or at heater <50ºC.
Heater gets OFF- If CF temperature in tank >57ºC or at heater >65ºC.
Control fluid regeneration system is provided for removal of acids and ageing products
during operation by the continuous filtering through Fuller´s earth and mechanical filters. The
mode of operation of this natural earth treatment is based on a ion-exchange reaction. The
regeneration system is having two pumps, two filters, two Fuller Earth filters, one heater.
FULLER EARTH REPLACEMENT PROCEDURE:
F.1 Isolation procedure of fuller earth for replacement :-
1 Stop the regeneration pumps and isolate the power supply.
2 Close inlet and outlet valves of the fuller earth system.
3 Open vent valves of the fuller earth system for depressurization.
4 Open drain valve of the fuller earth system for draining.
5 Ensure the complete draining of the system.
6 Issue PTW on fuller earth system for fuller earth replacement.
F.2 Normalization procedure of fuller earth after replacement:-
1 Close the drain valves of fuller earth system.
2 Crack open the vent valve of fuller earth system.
3 Slowly open inlet valve and ensure venting.
4 Close the vent valve of fuller earth system after venting.
5 Allow it for soaking about 4-5 hours if new fuller-earth is used.
6 Open outlet valve of fuller earth system.
7 Normalise the regeneration pump power supply.
8 Start regeneration pump and check for any abnormality.
G PROCEDURE FOR FILTER CHANGE-OVER:-
1 Close drain valve of stand-by filter.
2 Open vent valve of stand-by filter.
3 Open equalizing valve and observe the pressure in the pressure gauge mounted on stand-by
filter. Also observe the temperature of the stand-by filter body which will increase.
4 Close the vent valve and equalizing valve after ensuring pressure and temperature of the
standby filter.
5 Slowly change-over the filter by rotating the change-over valve.
6 Open the vent for depressurization and check the pressure.
7 Open the drain valve of the new stand-by filter and ensure the complete draining (Continuous
draining may happen when filter was not properly isolated due to passing in change over valve)
PUMP INITIAL STARTING AND STOPPING PROCEDURE:
1 All PTWs are returned and Clearance from Turbine Maintenance available
2 Pump surroundings are clean & properly illuminated and access to the pump area is adequate.
3 No PTW pending in the Governing system (Main and LP Bypass) & lined up.
4 Control fluid moisture and acidity values are within limits (Moisture: <1000 ppm (mg/kg) / Acidity :
<0.1 mg KOH/Gm).
5 CFT level is more than + 100 mm and that CF temp. is more than 20ºC
6 Start one control fluid pump and stop it after a few seconds to allow for line filling and venting.
7 Then again start the pump and keep in service.
8 Check that the HP & LP pressure are more than 32 ksc and 8 ksc respectively.
9 Check for any abnormality like Abnormal sound, seal leakage, bearing temp. line leakage,
Vibration etc. Stop the pump if any major abnormality is observed.
10 Observe the CFT level after starting the pump. If it drops below zero and maintains there, level
topping up may be required.
11 Similarly check the availability of other pump (Stop the running pump and then start the stand by
pump). Check that the HP & LP pressure are more than 32 ksc and 8 ksc respectively.
12 Check for any abnormality like Abnormal sound, seal leakage, bearing temp. line leakage,
Vibration etc. Stop the pump if any major abnormality is observed.
13 Keep any one pump in service.
14 Observe for any filter choking. If required changeover and clean the filters.
15 Switch on the control fluid heating system and put it in auto.
16 Observe the proper operation of the CF temp. control valve for maintaining the temperature.
17 Switch ‘ON’ SLC CF system and give ‘Run’ command to complete the start-up
TANK DRAINING AND REFILLING PROCEDURE
I.1 CONTROL FLUID TANK DRAINING PROCEDURE
1 Ensure that the unit is under shutdown and there is no requirement of control fluid system
operation.
2 Stop the both control fluid pumps and isolate the power supply.
3 Stop both CF oil vapour exhausters and isolate the power supply.
4 Stop both CF regeneration pumps and isolate the power supply.
5 Ensure the availability of empty clean oil barrels or empty standby thoroughly cleaned tank
prepared for this purpose for emptying the CF tank.
6 Ensure the clearance from TMD for emptying the CF tank..
7 Isolate the deluge valve spray system provided for the system
8 Note down the tank level before starting draining.
9 TMD is responsible for tank draining into the empty barrels.
I.2 CONTROL FLUID TANK FILLING PROCEDURE
1 Ensure the correct quality of the control fluid ((Moisture: <1000 ppm (mg/kg) / Acidity : <0.1 mg
KOH/Gm).
2 Ensure the inspection of the tank is completed and cleanliness of the tank.
3 Ensure the CFT drain valve is closed.
4 Local level gauge is calibrated if required and charged condition.
5 TMD is responsible for tank filling from the barrels.
6 Start CFT filling and monitor the level.
7 Check the Level switches (Operation & resetting) while filling CFT.
8 Fill the CFT level up to 650mm from Top
9 Check oil level in the local level gauge and compare with remote level indication, Attend it if any
deviation appears..
10 CFT filling completed
J CONTROL FLUID PUMP CHANGE OVER
1 Check & note down the running pump discharge pressure.
2 Check & note down the running pump current at UCB & local breaker panel.
3 SLC control fluid in ON condition.
4 Start standby control fluid pump from UCB CRT.
5 Check the discharge header pressure at local and UCB. Ensure that there is an increase in
pressure, which indicates loading condition of the standby pump.
6 Check the current of the running standby pump at UCB and local breaker panel.
7 Stop the previous running pump after ensuring loading condition of the standby pump.
8 Again check the discharge header pressure and current (There may be a dip in discharge
pressure).
CHECKS AND MONITORING DURING NORMAL RUNNING:-
K.1 Local Monitoring:
1 Note down CF tank level. CFP discharge pressure, all filters DP, cooler o/l temp, tank temp,
Waste fluid tank level.
2 Check for any leakages and abnormal sound, foaming condition.
K.2 Remote Monitoring:
1 CF tank level, cross-check it with local reading.
2 CFP discharge pressure, temp after cooler, pump current, see trend of current and pressure to
detect foaming condition.
3 See the moisture content and acidity from daily planning report and take necessary action if any
discrepancy occurs.