emergency procedure final-1

1. Drum level dropping fast

Likely causes One of the running BFP might have tripped Sudden tripping of one or more Mills/feeder. FW control valve/scoop might have closed/stuck. Malfunction of auto control/scoop regulation. BFP recirculation valve suddenly opened or valve passing Sudden reduction of load. Tube failure in water walls. HPBP in open position for long time under full load condition Inadvertent opening of EBD & low point drains. Drum pressure very high Drum level transmitters faulty.

Plant response Drum level LOW alarm appears. BFP's scoop rises to maximum. FCV opens to 100% Boiler will trip if drum level becomes very low

Parameters of concern / Adverse Effects Drum level very low may affect natural circulation in water wall panel and if drum is empty tubes will melt in no time Deaerator level Hot well level Feed water flow Steam flow SH/RH temp

Immediate expected or desirable operator action. See that standby BFP starts on tripping of running BFP or else Manually start standby BFP when level drops to -100 mm & load the pump immediately.

Check for any malfunction of auto control like scoop/FCV not raising or recirculation open in auto, take control in to manual & regulate it

Close CBD if it is open. Close BFP RC valve MIV if heavy passing is noticed Close HPBP slowly if it is open. Reduce boiler firing when level is about -100 mm

Final Corrective Activity. Check drum level is getting stabilised. Ensure drum level controls are in auto. Check feed water flows matches with steam flow for full load, if deviation is more then check for any leak in boiler area. Ensure for the availability of standby BFP as early as possible. Check for local level gauge & transmitters. Check boiler low point drains & EBD. Check for scoop controls for any linkage failures.

2. Drum level shooting up fast

Likely causes Malfunction of feed control valve or BFP scoop. Scoop /Flow control valve might have stuck. Sudden increase of load Drum level transmitters may be faulty. Sudden increase of firing rate. Sudden opening of HPBP.

Plant response Drum level high alarm will appear. If drum level reaches very high level boiler will trip BFP scoop & FCV position reduces BFP RC valves may open

Parameters of concern / Adverse Effects Drum level very high may cause priming foaming & carry over. If Water is discharged to super heater header hammering may occur

& wet steam may enter MS line Deaerator level Hot well level Feed water flow Steam flow SH/RH temp

Immediate expected or desirable operator action. Open emergency blow down –EBD-valve Reduce HPBP valve position if it is open Reduce boiler firing If drum level is approaching trip value take drum level control on manual & regulate Reduce load for a momentso as to control the water level (if water level is due to upward load surge).

Final correction activity Check drum level is getting stabilised. Ensure drum level controls are in auto. Check feed water flow matches with steam flow. Check for stuck of feed control valves & scoop. Check the level at local, hydrostep and transmitters are matching.

3. Rapid Boiler steam pressure rise

Likely causes Corex calorific value increased drastically. Sudden loading of mill. High firing rate. Feeder hunting. Malfunction of CMC. Sudden dropping of generator load & HPBP not opened

Plant response Throttle pressure high alarm will come HP/LP bypass opens on auto. APH FG I/L O2 low alarm will appears Boiler safety valve may float. Drum level will vary.

Parameters of concern/Adverse effects. Drum pressure sudden raise may cause safety valve lifting Tube leak may start Unit load MS /RH temperature Drum level APH inlet O2 HP/LP bypass

Immediate expected or desirable operator action Take the fuel control into manual mode if it is in CMC & reduce the fuel firing. Trip the malfunctioning feeder/mill & reduce PA airflow through that mill. Check for pressure drop & if it is not holding remove the corex burners. Start standby BFP if drum level is dropping

Final correction activity Check for reseating of safety valve As soon as the pressure starts dropping, restore the correct fuel input. Stop the third running BFP and keep it in standby. Ensure drum level got stabilised. Check for closure of HP bypass. Ensure pressure is stable.

4. Rapid Boiler steam pressure decrease

Likely causes Sudden drop in corex pressure or Calorific value Tripping of mill or feeder or oil elevation Mill getting unloaded HPBP got opened Sudden rise in load. Boiler tube leakage Safety valve not closing after floating

Plant response O2 at APH inlet high alarm MS pressure will drop. Generator load will come down. Drum level will drop.

Parameters of concern/Adverse effects Drum level generator load MS pressure MS/RH temperatures APH FG inlet O2 If rate of pressure drop is more than the given saturation temp. curve boiler drum will subjected to severe thermal shock

Immediate expected or desirable operator action. Check for any mill unloading/ tripping Reduce load set point to hold the MS pressure around 110 kg/cm2. Close HPBP if it is opened Check for safety valve floating Raise boiler firing in case of mill tripping. Take oil elevation in to service if required Check boiler flame Monitor drums levels during this disturbance, if it is dropping very fast, start standby BFP.

Final correction activity. Ensure drum level is stable. If mill is unloaded stop the mill & take other mill into service. Increase to full load based on the fuel. Remove oil if it is introduced if furnace conditions are good or bright.

5. EMRV floating and resetting in succession

Likely causes Improper blow down setting for EMRV/ pressure switch malfunction Fuel in put to boiler varying continuously. Turbine control valve/HPBP valve hunting MS pressure fluctuation

Plant response Drum level will vary. EMRV open/close indication in Control room Drum pressure fluctuation Ms temp and RH temp variation. Turbine control valve may hunt due to varying throttle pressure

Parameters of concern/Adverse effects Drum level MS pressure. Ms temp and RH temp Shock to boiler component Valve may get damaged.

Immediate expected or desirable operator action Reduce the fuel firing if pressure is really high. If MS pressure is less, still EMRV is operating, keep selection switch to "OFF" so that the EMRV will not operate.

Even by putting "off ", valve is still in open condition, its manual isolation valve can be closed.

Final correction activity Ensure for proper re-seating of the valve & put back in auto.

6. RH SV floating and resetting in succession

Likely causes HP bypass opened & valve hunting LP bypass opened & valve hunting HPBP opened & LPBP not opened Improper blow down setting of Safety valve

Plant response HRH steam pressure high alarm will appear. MS and RH temp variation HRH/MS pressure variation Generator load may vary due to turbine control valve hunting

Parameters of concern/Adverse effects Drum level MS and RH pressure HRH temp Shock to boiler component

Immediate expected or desirable operator action If LP bypass not opened even with pressure more than sliding setpoint, reset LPBP trip & see LPBP is opened Take HP/LP bypass valve on manual if it is hunting in auto Reduce MS pressure, if actually high, so that HP bypass will close in auto. Reduce the turbine load until the valve resets

Final correction activity If Blowdown adjustment is required do it in the nearest available opportunity If any control is malfunctioning attend to it

7. MS temperature rising fast

Likely causes Inadequate spray due to malfunctioning of spray control valves. Excess airflow. Burner tilt stuck in up position Leakage in the spray line. Low feed water temperature. Boiler firing raised in top elevation Heavy furnace slagging Spray isolation valve in close condition

Plant response MS temperature high alarm will appear. Spray control valves will go for further opening. If temperature is very high, turbine will trip.

Parameters of concern/Adverse effects MS/RH temperatures MS temp at turbine inlet

HP exhaust temperature. Spray quantity/ FCV differential pressure. Tilt position Metal temp. raise above design value will reduce tube life drastically

Immediate expected or desirable operator action Make burner tilt fully down Take MS spray control to manual & raise spray quantity (stage -1 o/l temp should be around 450°C & stage -2 o/l temp around

505°C) Reduce firing in top elevation If rate of pressure rise is more, then pick up load if margin is there. Reduce airflow based on the O2 percentage. Check spray station is properly lined up

Final correction activity

Start soot blowing, if slagging is more Restore back the temp controls in auto if it has been taken in manual Check for any malfunction of spray control valves & isolate such type of valve. Burner tilt can be kept horizontal.

8. RH temperature rising fast

Likely causes Inadequate spray due to malfunctioning of spray control valves. Excess airflow. Burner tilt stuck in up position Leakage in the spray line. Low feed water temperature. Boiler firing raised in top elevation Heavy furnace slagging HP exhaust temp is high Spray isolation valve in close condition

Plant response RH temperature high alarm will appear. Amount of spray will rise. Turbine will trip if RH temp reaches very high

Parameters of concern/Adverse effects RH temperatures RH temp at turbine inlet HP exhaust temperature. Spray quantity/ FCV differential pressure. Tilt position Metal temp raise above design value will reduce tube life drastically

Immediate expected or desirable operator action Make burner tilt fully down Take RH spray control to manual & raise spray quantity Reduce firing in top elevation

If rate of pressure rise is more, then pick up load if margin is there. Reduce airflow based on the O2 percentage. Check spray station is properly lined up Check HP exhaust temp is normal

Final correction activity Start soot blowing if furnace slagging is there. Keep the burner tilt in horizontal condition. Restore back the control in auto if it has been taken in manual.

9. MS temperature falling fast

Likely causes Tripping of mill Sudden boiler pressure drop Malfunctioning of spray control valves. Spray station passing Less air flow Burner tilt fully down High feed water temperature Soot deposits on SH tubes

Plant response MS temperature low alarm will appear. Turbine will trip if MS temp goes very low.

Parameters of concern/Adverse effects Ms temp Spray quantity Burner tilt

Immediate expected or desirable operator action Close the spray control valves by taking it into manual. Make burner tilt upward. Check airflow &Rise if necessary. Increase firing in top elevation Reduce turbine load if pressure is dropping Close spray station Block valve/ isolation valve if control valve is passing.

Final correction activity Start LRSB operation Observe for improvement in temperature. Restore back the controls in auto (spray control) Check for any malfunction of control valve & isolate it.

10. RH temperature falling fast

Likely causes Tripping of mill Sudden boiler pressure drop Malfunctioning of spray control valves. Spray station passing Less air flow Burner tilt fully down High feed water temperature Soot deposits on RH tubes

Plant response RH temperature low alarm will appear. Turbine will trip if RH temp goes very low 450°C

Parameters of concern/Adverse effects RH temp Spray quantity Burner tilt Load

Immediate expected or desirable operator action Close the spray control valves by taking it into manual Make burner tilt upward Check airflow &Rise if necessary Increase firing in top elevation Reduce turbine load if pressure is dropping Close spray station Block valve/ isolation valve if control valve is passing.

Final correction activity

Start LRSB operation Observe for improvement in temperature. Restore back the controls in auto (spray control) Check for any malfunction of control valve & isolate it.

11. COREX VENT VALVE FAIL TO CLOSE.

(A) INDIVIDUAL CORNER VENT NOT CLOSING

LIKELY CAUSES Inadequate Air supply to the valves Command from DCS to field not extended Feedback problems in nozzle valves

PLANT RESPONSE Down stream pressure will come down as compared with the corresponding valve position.

PARAMETERS OF CONCERN Corex header pressure. CO ppm in the atmosphere.

OPERATOR ACTION Check the valve position at local. Take out pair of corresponding burners.

FINAL CORRECTIVE ACTION Remove pair of corresponding burner & rectify the problem with help of C&I.

(B) COREX C- HEADER VENT VALVE OPENED

LIKELY CAUSES

Inadequate air supply to the valves Command from DCS to field not extended

PLANT RESPONSE Corex pressure will come down at faster rate Corex leak alarm may come

PARAMETERS OF CONCERN Corex header pressure. CO ppm in the atmosphere.

OPERATOR ACTION Take out burners in pairs. Close trip valve

FINAL CORRECTIVE ACTION Find out the root cause & rectify the problem with help of maintenance.

12. COREX TRIP VALVE FAILS TO CLOSE.

LIKELY CAUSES Inst. air supply failure Mechanical failure. Command from DCS to field not extended.

PLANT RESPONSE If the trip valve has failed to close during boiler trip, the corex will vent out from the C hdr vents & chances of increase in CO

PPM will be there. Corex may also enter in the boiler if there is passing in any of the corner nozzle valves.

PARAMETER OF CONCERN CO ppm in atmosphere. Furnace draft. (If the corex trip valve has failed to close during boiler trip accompanied with the failure of closing of any corner

nozzle valves). MS pressure. (If the corex trip valve has failed to close during boiler trip accompanied with the failure of closing of any corner nozzle

valves). Furnace flame. (If the corex trip valve has failed to close during boiler trip accompanied with the failure of closing of any corner

nozzle valves).

OPERATOR ACTION Close UNIT supply goggle valve & Ensure that the C header pressure reduces to atmospheric pressure. Ensure the furnace purge cycle completion.

FINAL CORRECTIVE ACTION Find out the root cause & rectify the problem with help of maintenance.

13. HEAVY ASH BUILD UP IN ONE OF THE HOPPERS.

LIKELY CAUSES Failure to carry out ash evacuation in time. Problems with electronic controller and transformer rectifier of the fields in service. Under voltage tripping of the fields in service. Transformer protection acted of the fields in service. Choked ash lines preventing hopper from being evacuated Moist ash. Rat hole in hopper Struck up of foreign material in the conveying system Failure of heating element-ash may stick to the hopper Insufficient vacuum developed by blower.

Problem with air intake valve Insufficient loading of succeeding fields.

PLANT RESPONSE EP fields trip on low voltage. Build up to high tension emitting system, causing short circuit Buckling of collecting electrode/Dislocation Ash level high alarm will come, will trip the field Dust carry over from chimney. CEMS will indicate high SPM.

OPERATOR ACTION Check ash-handling system. Switch off the field Try to charge possible fields as early as possible Switch over to corex fuel. (If it is going to take longer period to rectify the problem). Reduce coal firing. Manual poking of hopper to be done (ensure that particular field is off) If vacuum is not developing change the blower. Switch on heaters. Check rapping frequency The ash evacuation should be continued due to gravity settlement

PARAMETERS OF CONCERN Stack emission. Tripping of field

FINAL CORRECTIVE ACTION Arrange for ash evacuation. After evacuation charge the field.

14. OIL LEVEL LOSS IN APH BEARINGS

LIKELY CAUSES Leakage in piping Leakage in drain plug, instruments, connections Leakage in threaded joints Leakage through filter vent plug Oil seal damage

PLANT RESPONSE Rapid rise in oil temperature Noise may come if bearing is damaged Bearing temp will raise. If leakage is there near the hot end, may cause fire break-out.

OPERATOR ACTION Find out the leakage point. Stop the oil pump to avoid further loss of oil. Make up the oil level in the bearing housing. Run the stand by oil pump only if the leakage point is not from the common piping. In case of any fire, extinguish it with the help of proper extinguisher at the earliest possible.

PARAMETERS OF CONCERN Oil level Oil temperature Bearing temperature.

FINAL CORRECTIVE ACTION Add oil through the dip stick hole until max oil level mark . Leakage to be arrested. Put the oil system back in to service.

15. AIR-PREHEATER MOTOR TRIPS/ AIR MOTOR DOES NOT START

A. ONE APH MOTOR TRIPS/AIR MOTOR DOES NOT START.

LIKELY CAUSES Motor may trip on overload. Power supply to the motor failed. Air motor failure or solenoid failure No compressed air available. Lube oil system fail. Some foreign material fallen on the APH & got stuck. Seal of the APH has got disturbed.

PLANT RESPONSE Rapid fall of hot air temperature on one side.

Rapid rise of gas temperature of stopped APH. Possibility of deformation of APH. Alarm at ECP/ DCS electrical motor stop- appears. Furnace draft will fluctuate due to ingress of cold FD air. Mill temp will drop as a result of drop in hot PA temperature.

OPERATOR ACTIONS Reduce boiler/generator load to 60% MCR gradually. Attempt for starting the electric motor, if the power has resumed or after resetting the over load. If the air motor has not started because of air solenoid problem open the bypass valve of the solenoid. Isolate affected air heater on the gas side first if all the attempts of starting the air motor or electric motor has failed. (Keep watch on

draft) Isolate the affected APH at airside (keep watch on total airflow) Try to rotate air heater manually. Maintain generator load depending upon the parameters of the running AH. Watch hot air temperatures to mills Cut in oil burners, when load is reduced. Reduce corex to minimum. Checks lube oil system & restore lubrication.

PARAMETERS OF CONCERN Flue gas temp at APH I/L & O/L. Furnace draft. Mill o/l temp / hot PA temperature Secondary air temperature.

FINAL CORRECTIVE ACTION After rectifying the problem of electric motor / air motor, start air / electric motor before normalizing the dampers on air/gas side. If the problem is due to stucking of foreign material, then outage may be required to remove the same.

B. WHEN BOTH APH MOTOR TRIP/AIR MOTORS DO NOT START

LIKELY CAUSES Power supply failure/ motor failure. Compressed air failure

PLANT RESPONSE Rapid fall of hot air temperature Rapid increase in flue gas temperature Possible distortion in air heater rotor Air heaters A/B electrical motor stop & APH rotor stop alarm at ECP/DCS.

OPERATOR ACTION Reduce the fuel firing drastically as early as possible. Parallel attempts to be made for electric/air motor If failed to restore APH rotation within ten minutes, shut down the boiler. Manually rotate APH till alternate arrangement is made.

PARAMETERS OF CONCERN Flue gas temp at APH I/L & O/L. Furnace draft. Mill o/l temp / hot PA ,SA temperatures. Secondary air temperature

FINAL CORRECTIVE ACTION After rectifying the problem of electric motor / air motor, start air / electric motor before normalizing the dampers on air/gas side.

16. SUDDEN INCREASE IN STEAM SILICA

LIKELY CAUSES DM make water silica may be high. Condenser tube leakage. System taken into service after major over haul & maintenance.

OPERATOR ACTION Ask chemist to confirm panel instrument readings of silica by actual analysis. Increase the drum blow down. Reduce drum pressure as per the curve “ silica in boiler water/boiler pressure" taking into account solubility of silica in steam at

elevated pressures. Maintain phosphate concentration in Drum around 5ppm. If the steam quality is affected by the process within the system, shutdown the turbine & start dumping through bypass to improve

the steam quality before rolling the turbine. If steam quality cannot be improved because of the make up water faulty/ condenser tube leakage, shutdown the unit.

PARAMETERS OF CONCERN Silica concentration in drum, steam. Phosphate concentration. Drum pressure.

PLANT RESPONSE Drum silica & steam silica high alarms will appear. Silica carry over in steam>0.02ppm leads to deposits on turbine blades.

FINAL CORRECTIVE ACTION Check &Correct DM make up quality. If condenser tube leakage is there after attending only, boiler to be lighted up.

Hot blowdown is to be given to displace impure water & level to be made up with fresh DM water. After restart of the boiler, don't take condensate into the system into service until quality of condensate is satisfactory.

17. BOILER WATER pH IS FALLING FAST

LIKELY CAUSE Improper phosphate dosing make up water faulty Due to continuous passing in IBD/CBD.

PLANT RESPONSE pH low alarm will appear Leads to accelerated corrosion of boiler tubes and consequent tube failure conductivity of boiler drum also comes down

PARAMETERS OF CONCERN pH of the drum water pH of condensate. Conductivity

OPERATOR ACTIONS Increase phosphate dosing. Check for passing in CBD/IBD. Consult the chemist. Check whole regime of the system.

FINAL CORRECTIVE ACTION Find the root cause of the problem; if it is due to faulty dosing then check concentration of the dose. If it is due to passing get it

arrested. ask chemist to check DM water quality.

18. REPEATED TRIPPING OF COLLECTING RAPPING MOTORS OF ESP

LIKELY CAUSE High ash level in hoppers. Improper setting of motor overload relay

PLANT RESPONSE Inefficient ash collection in ESP. Stack SPM may increase

PARAMETERS OF CONCERN Ash level, field current,SPM

OPERATOR ACTIONS Switch off the motor supply Switch off the fields if tripping on ash level high and empty the hopper. Switch on available /stand by field in the same pass.

FINAL CORRECTIVE ACTION Switch on the field and take rapping motor into service Get over load setting checked rectify the problem.

19. AC Scanner fan tripped & DC failed to pickup

Likely causes DC fan fails to start after AC fan trip Both fan getting over load/electrical fault

Plant response Scanner air to furnace DP low alarm Scanner air fan tripped alarm Inadequate cooling of scanners may cause damage to scanner sensing element

Parameters of concern/Adverse effects

Scanner air to furnace DP low Flame scanner cooling is not taking place

Operator action Try to start fan by resetting overload relay Increase FD fan discharge pressure so that some air will always available for scanner If not happening reduce load to minimum & get the fan started at the earliest. If Scanner air fan could not be restarted even after reasonable time delay trip the boiler

19. ID/FD trip

Probable Causes

ID trip Motor protection acted. Lub oil pressure v.lo 0.2ksc H.C oil pressure v.lo 0.6ksc H.C oil tank temp high 110oc H.C oil cooler o/l temp 90oc Winding temp v.hi 120oc Bearing temp (fan/motor) v.hi (75oc/95oc)

FD trip Motor protection acted. Fan/motor bearing temp v.hi 95oc Winding temp v.hi 120oc

Plant response On ID trip, corresponding stream FD fan will trip. Running ID/FD fans will get loaded to maintain draft and airflow. When in CMC, runback will act and reduce load SP to 90/100MW @ 20MW/min Mill-C will trip (On FD fan trip), if 3 mills are in service.

Parameters to watchFurnace draft, drum level, airflow, ID & FD currents, mill loading, TG load, MS pressure & temperature, RH temperature, WB to furnace DP, O2 at APH i/l.

Operator actionCase1: 3 mills in service without corexMill-C will trip on FD fan trip. After 1-min timer, cut-in oil guns.

Mill-A & B is to be increased to max. Hold pressure at 110ksc by reducing load.Cut-in corex if available & restore load, keeping a watch on ID/FD fan current.Start the tripped ID/FD fan after investigation and raise the load to full.

Case2: 1 mill with corex at 3 elevations1. Remove corex on X3 elevation. Hold pressure at 110ksc by reducing load.2. Start another mill and restore load keeping a watch on ID/FD fan current.3. Start the tripped ID/FD fan after investigation and raise the load to full.

20. APH fire

Likely causes Defective oil burner, leading to deposition of un burnt oil particles on APH heating elements. Soot deposit on APH heating element In effective APH soot blowing. Guide bearing oil leakage in to APH.

Plant response Flue gas/ secondary air temp high alarm should come(presently not commissioned) Flue gas temp after Air heater rises sharply Sec air and primary air temp after APH rises sharply. At worst case APH may get damaged

Parameters of concern. Flue gas temp after Air heater Sec air and primary air temp after APH Damage to APH

Immediate expected or desirable operator action. Reduce boiler load Close Flue gas inlet damper Close PA &Secondary air side inlet & outlet dampers Open APH hopper drain plug Open cold end side & hot end side hydrant valve and quench fire

Final correction activity. Stop the oil guns with smoky flame if they are in service. Isolate APH and open for inspection if fire is extensive

21. FIRE NEAR MILL AREA

LIKELY CAUSES High mill outlet temp. Running mill with less air flow for long time can cause coal accumulation in mill discharge pipe & cause fire High % of volatile mater in coal If mill rejects are more & not removed regularly may cause fire in rejects chamber. Tramp Iron Gate stuck in close position, causing fire in rejects chamber. Coal accumulation in hot air duct Fire conveyed from bunker coal

PLANT RESPONSE : Mill out let temp. high alarm Mill DP & air flow , current variation. Fire coming from reject hopper Red hot mill body/ reject chamber

Parameters of concern Mill puffing Mill o/l temp. Air i/l temp. Mill airflow. Mill DP Mill rejects.

Immediate /expected or desirable operator action Reduce hot air flow to mill & continue to run with more coal. Mill rejects hopper to be cleared If fire is not reduced stop feeder & open Mill inheriting steam valve & Hydrant water valve Stop Mill & release for clearing after fire is quenched

Final correction activity Inspect mill internals and feeder for healthiness.

22. LRSB NOT RETRACTED

LIKELY CAUSES Forward/Reverse motor trip Lance jammed after advancing LRSB clutch de coupled after advancing Electrical supply failure during operation Chain broken.

PLANT RESPONSE

Soot blower not retracted alarm Soot blower overload acted alarm

Parameters of concern Steam jet hitting boiler tubes LRSB getting damaged

Immediate /expected or desirable operator action Reset the module & give retract command from local push button. If it fails to retract even after module is reset, switch-off the

module. Reduce soot blower header pressure to 3- 4Ksc. Disengage the clutch and try to retract manually from handle. If it is retracting do not release handle in the middle ( If handle is to be

released in the middle, first engage the clutch & then only release) . Inform maintenance if it is not retracting manually also. Try retracting with additional assistance for max. one hour. If it could not be retracted within 1hour, reduce pressure to “0” ksc & try again. Still if it is not retracting ask maintenance to insert dummy in steam supply line flange so that other blower operation can be carried

out.

Final correction activity If the lance is deformed change with new one

23. FIRE IN ESP

LIKELY CAUSES OIL/soot deposit on ESP fields Very high un burnt in fly ash & hopper heating element Not switching off ESP transformer fire

PLANT RESPONSE ESP transformer trip. Furnace Draft variation

Parameters of concern ESP O/L temperature ID fan loading Furnace Draft Damage to ESP

Immediate /expected or desirable operator action Trip ESP field Isolate the power supply of all related ESP pass/field. If fire is outside ESP, use extinguisher & douse the fire. If it is inside ESP reduce unit load & close ESP inlet & outlet gate. Inform fire man

Open ESP man holes Open ESP ash hopper drain plugs/man hole Quench the fire with fire hydrant water

Final correction activity Identify the reason and rectify it.

26. ONE OF THE TURBINE CONTROL VALVE FAIL TO CLOSE

A. Symptom /parameter effected

While reducing load, it will not reduce below certain MW even if load set point is less.

Stuck Valve position feed back will show open position control room whereas other valve will go for close.

High speed control acting.

B. Likely cause

Valve mechanically stuck.

Trip mechanism not working.

Oil not getting drained from actuator.

C. Operator action

Immediate action

Reduce turbine load to 100MW if unit is in service.

If turbine has tripped. close MS1.2.3 &4 & depressurise MS & RH line.

Open corresponding MAL drain before & after control valve(Partially).

Subsequent action If valve has stuck. Reduce boiler pressure & shut down the unit for attending the problem.

Final corrective action

Start turbine only after valve problem is attended.

27. ONE PHASE OF THE GT POLES FAIL TO OPEN AFTER UNIT TRIP


Pole Discrepancy alarm will come.

LBB protection will trip all the breaker connected to that bus.

TG speed does not drop after trip.

TG draws current from grid (reverse power).

Negative sequence current in Generator.

LP exhaust temperature may shoot up.

B. Likely cause

Breaker contact mechanically stuck.

C. Operator action

Immediate action

Trip all the 220 kV breaker connected to the particular bus including bus coupler.(If LBB not acted).

Trip field breaker manually. If it did not opened.

Open isolators of GT breaker.

Subsequent action

Normalise supply by charging Lines .STs and Bus coupler.


Attend GT breaker before restarting Turbine.

28. SCANNER FAN TRIPPED & DC FAN FAIL TO START


Scanner air to furnace DP low alarm. Scanner air fans tripped alarm.

B. Likely cause

Dc fan fails to start after AC fan trips. Both fan getting over load/electrical fault.

C. Operator action

Immediate action

Trip the boiler

+

Subsequent action

Try to start fan by resetting overload relay. Increase FD fan discharge pressure so that some air will always available for scanner. If not happening reduce load to minimum & get the fan started at the earliest. If Scanner air fan could not be restarted even after reasonable time delay trip the boiler.


Lightup boiler only after starting scanner air fan.

29. HIGH DIFFERENTIAL EXPANSION IN TURBINE


Difference between shaft & casing expansion more than normal.

Change in axial shift.

High turbine vibration.

B. Likely cause

Positive differential expansion.

More than rated steam pressure & temp. for rolling.

Inadequate soaking during rolling.

Too fast load pickup of load.

Sudden raise in MS/RH temp.

Casing not moving freely over its slide/ restriction for casing expansion.

High gland steam temperature.

Improper drain operation.

Negative differential expansion

Less than rated steam pressure & temperature for rolling.

Sudden drop in MS /RH temperature.

Improper drain operation.

Wet steam entry in to turbine.

C. Operator action

Immediate action

Positive differential expansion

Reduce steam temp if it is more.

Bring machine to soaking speed if it is during rolling.

Reduce turbine loading if it is after synchronisation.

Check and control gland steam temperature.

Check MAL drains are operating properly.

Negative differential expansion

Increase steam temperature if it is less.

increase turbine load if it is after synchronisation.

Check MAL drains are working properly.

Check gland steam temperature.

Check MAL drains are operating properly.

Subsequent action

Maintain steam temperature steady.


30. TURBINE BEARING TEMPERATURE RAISING FAST


Turbine/generator bearing temp. high alarm.

Lub oil return line oil temp. gauge showing more than normal.

Turbine oil cooler inlet/outlet temp. more than normal.

Change in turbine vibration pattern.

B. Likely cause

ACW pump tripped or ACW to lub oil cooler not charged after synchronisation.

High lube oil inlet temperature.

Bearing failure.

Thermostatic valve failure.

Inadequate lub oil flow or pressure.

Excessive bearing vibration.

High axial thrust.

Lub oil cooler not vented properly.

C. Operator action

Immediate action

Trip the turbine if bearing temp reaches 1200C(atleast 2 indications in metal temp overview screen).

If temp is with in 1200C then try the Subsequent action.

Subsequent action

Check lube oil flow & pressure to bearing.

Check Lub oil cooler is charged on ACW side & ACW flow is adequate.

Check return oil temp from each bearing.

Verify babit temperature by other means (to rule out faulty measurement)

If thrust bearing temperature is increasing check for axial shift.

Start Standby AOP if oil pressure is low.

Vent lub oil cooler properly.


Find out reason for bearing temp raise.

31. TURBINE VIBRATION SHOOTS UP


Turbine bearing/shaft vibration high alarm.

Turbine will trip if shaft vibration reaches trip value.

B. Likely cause

Turbine bearing damage.

Rotor eccentricity high/ Shaft distortion.

Turbine blade damage.

Turbine glands rubbing.

Sudden change in steam inlet temperature.

Lube oil temperature too low.

Uneven cylinder expansion/restriction for expansion.

Foundation bolts loose.

Alignment/centering problems.

Change in axial shift.

Sudden MVAR load change.

Improper drain Operation

High grid frequency

Machine coasting down rate too slow after trip.

C. Operator action

Immediate action

Reduce turbine load by load limiter and trip the machine if bearing vibration is >11mm/sec(for Brg No. 6 >18mm/sec.

Subsequent action.

Check locally whether vibration is actually high.

Listen to bearing sounds using a vibration sensing stick.

Maintain steam parameters normal.

Check lube oil pressure and after cooler temperature.

Check any sudden MVR change is there.

Wait for frequency change.

Trip the machine if it does not trip on high vibration.


32. TURBINE STARTS ROLLING ON ESV OPENING


Turbine speed may rise without giving command for rolling.

B. Likely cause

Control valve passing.

Control valve stuck in open position.

C. Operator action

Immediate action

Close ESV by tripping turbine.

Check whether control valves are fully closed (in DCS as well as local).

Check for the EHTC output (has to be zero).

Subsequent action

If all rolling criteria are ok and if only minor passing only is there and speed is reaching to say 800rpm roll to 3000rpm if it is a

hot startup.


Attend valve problem in nearest shut down.

33. HPBP OIL LINE LEAK


Oil leak noticed by personnel. HPBP oil pump continuously running. HPBP oil pressure low alarm. HPBP valve creep opening without open signal.

B. Likely cause

Oil leaking from ferules. Servo valves leaking. Flexible hoses bursting out.

C. Operator action

Immediate action

Isolate leaking oil line/valve.

Switch off HPBP oil pump supply.

Isolate spray line MIV if leak is in spray line.

Subsequent action

If main valve creeping is started due to loss of oil pressure then reduce turbine load slowly to 60 MW.

Bring down boiler pressure to 85Ksc. and get the leak attended.

Trip boiler if HPBP downstream steam temp. could not be maintained.

Close MS-1.2.3 & 4 and depressurise MS line in that case.


If leak is attended charge the line slowly and raise the load

If leak could not be attended trip the boiler after reducing load.

34. CONTROL OIL LINE LEAK


Oil leak noticed by personnel. Control oil tank level low alarm. Control oil pressure dip. Oil leak detected from LPBP/IPSV tray switch. Oil leak detected from Control oil skid tray switch.

B. Likely cause

Oil leaking due to O ring failure. Servo valves leaking. Joint leak/welding failure. Excessive control oil pressure.

C. Operator action

Immediate action

Close isolation valve (at control oil skid) of leaking line if leak is in individual lines.

Reduce turbine load to 100MW.if any turbine valve has closed.

Open corresponding MAL valve partially.

Change over to standby pump if leak is in pumping unit.

If leak is in common block & leak does not stop after change over, reduce turbine load & trip Control oil Pumps immediately.

Subsequent action

Inform fireman and keep fire extinguisher ready if oil is spilled over valve body or steam line.

After attending leaky point charge line very slowly.


Arrange to clean leaked out oil.

35. WATER/OIL DETECTED IN GENERATOR CASING.


Liquid in Generator casing alarm. TG trip on LLD sensing level in Generator bushing top.

B. Likely cause

H2 cooler leakage. DPRV malfunctioning and maintaining higher DP. Defective seals component and oil entering generator casing.

C. Operator action

Immediate action

Open LLD drains after isolation and empty it. See whether oil or water is coming. After draining, normalise and wait for further liquid level sensing. If water is coming reduce generator load & isolate one hydrogen cooler & find out leaky cooler . If oil is coming see seal oil to H2 DP is normal.

Subsequent action

If liquid from drain is continuos plan for unit shut down. If liquid is because of DPR malfunctioning get it attended.


Find out reason for liquid entry in casing and rectify it.

36. WATER HAMMER IN PIPELINE

B. Symptom /parameter effected

Abnormal / intermittent sound in pipe line. Pipeline. Hanger or supporting structure damages. To & pro movement of pipeline.

B. Likely cause

Proper charging procedure not followed.

Sudden entry of steam into water lines.

Sudden entry of steam into improperly drained pipelines.

Improper warm up during charging steam lines.

Faulty drain traps or ill designed drain valves.

Sudden opening of high pressure valves.

C. Operator action

Immediate action

Cut off steam supply to the line in which hammering is occurring.

Subsequent action

Open drains & trap bypass valves of that line.

Wait for full draining/proper warm up.

Slowly open valve and allow steam to come out of drains.

Allow system pressure to build up.

Close drains & put trap in to service.

If it is a water line ensure no steam is entering pipe line.


Follow proper charging procedure.

37. COREX GAS LEAK

Symptom /parameter effected

Alarm at local / DCS will come depending upon location of leak.( 08 static CO detector in blower area, 8 CO detector & 8 H 2 detector

in different elevation on both the boiler & 01 detector in control room AC duct are connected to DCS system in Control room).

Lamp indication with hooter near DM plant water tanks

For > 50 ppm - orangeFor > 100 ppm - red

In addition Siren will be activated from control room for corex leak emergency.

B. Likely cause

Corex leak due to seal pot water seal breaking

Flange. valve gland leakage.

Passing of valves.

Explosion in pipe line.

Leakage from adjacent steel plant process

Major leakage can occur in the unlikely event of natural calamities such as earthquake etc.

C. Operator action

Check CO concentration with portable detectors and confirm with that of control room indications.

If the CO-detected by permanent / portable detectors is reading 200ppm and above, effect local area evacuation and parallel

start reduction of corex in the corresponding unit (if the leakage is sensed in blower area reduction to be done in both the

units). If greater than 400ppm for 15 min, stop A/C plant and remove corex elevation of the corresponding unit. (if the

leakage is sensed in blower area remove the corex completely in both the unit & close the bypass goggle valve and JVSL

double gate valve). And if greater than 500ppm for 30 min, declare emergency by actuating siren for totally evacuation of the

personnel.

Inform safety officer / fire control room in any of the above case.

Check for leakage, all the source of ignition should be kept away, Self-contained breathing apparatus (SCBA) to be used

while checking and attending leak.

In case fire takes place during leak, first the pressure in the supply line should be reduced to shorten the flame & then the fire

should be extinguished. Only after the fire is extinguished, the main gas should be closed completely. Never close the main

valve, when the fire is still there and the pressure in the gas main should not be reduced below 100mmwc.

In case anyone notices an emergency type situation, shift-in-charge should immediately reach the location of emergency with

necessary safety gadgets and assess the situation. He will declare the emergency by informing control room to send coded

siren (15 seconds on & off for 3 minutes). At the same time he will decide about the emergency shut down of the plant

Perform the head count at the assembly point (Old admin. Bldg).

All clear signals (2 min- continuous) siren to be raised if the declarer of emergency clears the emergency after attending the

leakage.

Subsequent action

Purge the corex system with nitrogen & achieve the co ppm less than allowable range of 50 ppm

Find out the exact location of the leakage.

Arrest the leakage point & check for leakage


Take corex in to service only after clearance from safety dept.

38. COREX VENT VALVE FAIL TO CLOSE


Valve fail to close alarm Corex leak alarm Valve close indication not coming in DCS

B. Likely cause

No or inadequate air supply to the valve actuator.

Command from DCS to field not extended.

Valve mechanically stuck in open condition.

C. Operator action

Immediate action

If C- header vent valve fails to close. then remove corex totally from that unit.

Ensure Nitrogen purge valve is open.

If it is corner vent valve. remove that corex pair from service.

Subsequent action

Check instrument air supply is normal to valve actuator.

Arrange to get vent valve closed from maintenance.


Take corex in to service only after the satisfactory valve stroking

39. COREX TRIP VALVE FAILS TO CLOSE.


Valve fail to close alarm. Corex leak alarm. Valve close indication not coming in DCS.

B. Likely cause

Valve Mechanically stuck.

Command from DCS to field not extended.

C. Operator action

Immediate action

Ensure all corner nozzle valves are closed.

Close corex control valve.

Close UNIT supply goggle valve and purge supply line & C header with N2.

Subsequent action


Take corex in to service only after the valve is made operational.

Emergency Procedure

1. APH FIRE

Symptoms / parameter effected

Immediate Operator Action

Likely causeSubsequent operator action


1. Flue gas temp. at APH

outlet goes above

3500C suddenly from

normal value

2. Secondary air temp. at

APH outlet goes above

3500C suddenly from

normal value

3. APH fire sensing

thermocouple gives

alarm (presently not

hooked up)

1. Reduce unit load to 65

MW

2. Close Flue gas inlet

damper of particular

APH.

3. Close ESP inlet damper

of the corresponding

APH.

4. Close PA &Secondary

air side outlet & inlet

dampers of that APH.

Heavy unburnt

deposit on APH.

Poor combustion of

fuel oil.

Not doing APH soot

blowing regularly

especially during oil

elevation was in

service

1. Open APH hopper drain

plug.

2. If the fire is confirmed

open cold end side & hot

end side hydrant valve

and quench fire

3. Continue running APH

with air motor/electrical

Motor if possible.

Isolate APH and release for inspection.

Do APH soot blowing every shift if oil is in service

2. AIR-PREHEATER MOTOR TRIPS/ AIR MOTOR DOES NOT START

A. ONE APH MOTOR TRIPS/AIR MOTOR DOES NOT START.





1. APH Electrical motor

trip alarm.

2. APH rotor stopped

alarm.

3. Rapid rise in flue gas

temperature of tripped

1. Reduce unit load to 65

MW

2. Close Flue gas inlet

damper of particular

APH.

3. Close PA &Secondary

air side outlet & inlet

Motor tripped on

overload.

Power supply to

the motor failed.

Air motor failure

or solenoid

1. If the air motor has not

started because of air

solenoid problem open

the bypass valve of the

solenoid and air motor

will start, If it does not

APH outlet(>3000C)

4. Rapid fall in secondary

& primary air temp at

APH outlet.(<1000C)

dampers of that APH. failure

No compressed

air available after

power failure.

Some foreign

material fallen on

the APH & got

stuck.

start then

2. Attempt for starting the

electric motor if the

power has resumed, or

after resetting the over

load. If neither air motor

nor electrical motor

came in to service then

try to rotate by putting

handle on motor shaft.

(Module to be switched

off before trying this)

B. WHEN BOTH APH MOTOR TRIP/AIR MOTORS DO NOT START





1. APH Electrical motor

trip alarm.

2. APH rotor stopped

1. Confirm from DCS

alarm that both APHs

are tripped

Both Motor

tripped on

overload.

1. If the air motor has not

started because of air

solenoid problem open

alarm.

3. Rapid rise in flue gas

temperature of tripped

APH outlet(>3000C)

4. Rapid fall in secondary

& primary air temp at

APH outlet.

2. Manually Trip the boiler Power supply to

both motors

failed.

Both air motor

failure or

solenoid failure

No compressed

air available after

power failure.

Some foreign

material fallen on

the APH & got

stuck.

the bypass valve of the

solenoid and air motor

will start, If it does not

start then

2. Attempt for starting the

electric motor if the

power has resumed, or

after resetting the over

load. If neither air motor

nor electrical motor

came in to service then

try to rotate by putting

handle on motor shaft.

(Module to be switched

off before trying this)

3. TG barring gear does not established after turbine trip





1. Turbine speed <10 rpm

alarm.

1. Start manual hand

barring when TG shaft

becomes standstill.

Lift oil pressure not

sufficient/filter

choked

Stand by pump NRV

passing

Turning gear

solenoid problem

Lift oil line pressure

regulator problem or

test valve open

Lift oil pump

discharge valves in

closed condition

Lift oil pump relief

valve problem

Leakage in lift oil

line

Bearing lift improper

Turbine internals

rubbing

1. Change over lift oil filter

if it is choked

2. Close standby pump

discharge valve if NRV

is passing

3. If solenoid is faulty

disconnect solenoid

connection near front

bearing pedestal

4. Close regulator test

valve if it is open

5. Open pump discharge

valve if it is close

Hydro motor

problem

4.Both JOPS fails during coasting down





1. Turbine speed <510

rpm and JOP not in

service alarm

2. Turbine speed <10 rpm

alarm.

1. Start JOP manually JOPs not in AUTO

and or SLC not on

AC/DC power failure

Fuses blown out

Pump module

problem

Module tripping on

overload

Pump mechanical

damage

1. Check module fuse

2. Reset module

3. Ensure Lub oil pump is

in service.

5.Boiler flue gas temperature shoots up





1. Flue gas temp at APH

outlet >3000C

2. Secondary air temp at

APH outlet >3000C

3. Reduce boiler load to

bring down flue gas

temp within limits

APH Fire

More Air Flow

Loss of seal trough

water

Inadvertent closure

of any of the APH

inlet/outlet damper.

Improper

operation of

1. Refer APH fire

procedure

4. Reduce Air flow if it is

more

5. Make up seal trough

water if it is broken

6. Check all APH dampers

and open if any damper

is closed.

7. Set SADC correctly

SADC

Boiler tube leakage

Heavy soot deposit in

boiler

8. Refer boiler tube leak

procedure

9. Do soot blowing.

6. Condenser pressure raises on vacuum loss





1. Condenser vacuum low

alarm

2. LP exhaust hood temp

high alarm

3. Condenser pressure

1. Open vacuum breaker

valve manually if

vacuum is less than -

0.2Ksc

2. Open LP exhaust

Vacuum breaker

valve close.

Any Drains to

condenser open.

CW pump not

Close all drain MIV

connected to

condenser.

Close seal steam

supply valve from

If LPT diaphragm is ruptured replace it

Transmitter showing

+ve value

hood spray main/

bypass valve if

exhaust hot temp is

>900C

running.

Seal steam supply

not cut off.

LPBP valve drift

open.

PRDS

Depressurise MS &

HRH lines by opening

MS drain to atmosphere

& HRH vent

7. Emergency DG not starting after Blackout





1. DG trouble/tripped

alarm

1. Ensure DC EOP.JOP.

Seal oil pump.

E-Stop pressed

DG not in auto

1. Release E-stop

2. Start DG manually

Find out cause for DG trouble and rectify it

2. KB bus under voltage

alarm

Scanner air fan are

started

2. Close DG switch gear

bus coupler if other

DG is running

Over crank shutdown

Over speed

shutdown

Started & tripped on

Low oil pressure


Low water tank level


High water

temperature

3. Charge KB bus by

manually closing 415 V

breaker if it is not

closed on auto.

4. Start the AC motors

where DC motors are

running and stop DC

motors

5. Close MS-1 & 2, AS-9,

CRH-105 manually if

DG supply is not

available

6. All other activities of

black out to be

performed.

8. Boiler Tube leakage





1. Acoustic leak detector

alarm

2. Drum level fluctuation

3. Furnace draft

Fluctuation

4. Sound from inside

boiler

5. Not able to maintain

hotwell level even with

makeup valve full open

1. Start reducing unit

load

2. Confirm tube leakage

by observing sound &

boiler parameters.

Wall blower / LRSB

stuck in advanced

condition for long

time.

Sustained high metal

temperature.

Erosion of tubes due

to soot blowing

Erosion on tube due

to high ash content in

coal.

Blocked tubes

Scale

formation/corrosion

inside tubes

Operating boiler with

1. Maintain drum level

normal & if required

start Standby BFP

2. Shut down the unit after

reducing load

3. Box up boiler

4. Drain boiler after

depressurisation and

isolate it

Replace leaky tubes

faulty drum level

transmitter.

Bursting of tube due

to pressure

fluctuation.

Improper setting of

safety valve.

9. Fire near MOT/Control oil system





1. Fire noticed by

personnel.

2. Fire alarm. if actuated

in local by any persons

after observing fire

3. Burning smell

1. If fire is isolated one

quench with

appropriate

extinguisher

2. Inform firemen.

3. If it is big in nature.

Trip the unit.

4. Operate

corresponding deluge

valve.

Electrical short circuit

near MOT

Welding on oil lines

with out safety

precaution

Oil leakage Catching

fire oil spillage on

high temperature

steam line

1. Isolate electrical supply

of affected area if

required.

2. Isolate oil lines if

possible

3. Use hydrant system for

fire fighting.

Replace MOT/control oil if contaminated

5. Stop control oil

system

10.Fire in Coal mill





1. Mill outlet temp. high

alarm

2. Mill outlet temp going

out of range.

1. Close hot air gate &

continue to run mill

with more coal without

overloading.

Excessive mill

temperature.

Excessive

accumulation of pyrites

1. Wait for mill outlet

temp to drop below

500C.

2. Stop feeder.

Clear mill internals Change gear box oil

if carbonising is noticed

3. Mill body & coal pipe

paint peeling off

4. Mill outlet temp. not

coming down after

closing hot air damper

5. Fire coming out in

rejects hopper*.

2. Open mill inheriting

steam valve to cool

the mill

3. Mill rejects hopper to

be cleared

or coal in scrapper

chamber

Foreign material such

as rags. Wood. Paper

collecting in mill.

Running mill with less

air flow for long time

can cause coal

accumulation in mill

discharge pipe &

cause fire

Coal accumulation in

hot air duct

Fire conveyed from

bunker coal

3. Purge mill completely.

4. Stop mill for

inspection.

*Note: Normally fire in

reject hopper will not

contribute to above bowl

fire. Clearing the hopper

will suffice in such cases.

11.Fire in transformers





1. Fire alarm in fire

monitor system

console.

2. Spray system deluge

valve operated alarm

3. Fire noticed from

personnel.

1. If transformer has not

tripped, trip it

manually & isolate it.

Transformer Internal

faults causing fire

Fire from external

source carried to

transformer

1. If Spray system not

operated Open by

pass valve of deluge

valve

2. Inform fireman.

3. Drain transformer oil

to burnt oil pit

4. Prevent fire from

spreading to other

equipment by fire

fighting measures

Release transformer for inspection

12.Fire in cable gallery






monitor system

console.


valve operated alarm.


personnel.

1. Trip the unit. Short circuit.

Cable insulation failure

due to over loading

Fire from external

source

1. Isolate AC supply as

per the condition and

if required trip the

station transformer.

2. If hydrant system not

operated Open deluge

valve bypass

3. Inform fireman

Isolate faulty cables & recharge electrical system.

13. Fire in coal conveyer






monitor system

console.


valve operated alarm.


personnel

1. Switches off Conveyer

supply modules.

2. Inform fireman.

Burning coal loaded on

the conveyer.

Electrical short-circuits.

Fire in the spilled coal

around conveyer.

1. If hydrant deluge

valve not opened

open bypass valve

2. Use the nearest

hydrant point for

additional spray

Remove burnt coal from conveyer.

Repair damaged component

14. Fire in coal bunker





1. Smoke coming out of

bunker opening.

2. Paint peeling off on

1. Stop feeding to that

bunker.

Spontaneous ignition

due stagnant coal in

bunker

1. If possible run the mill

& empty that bunker

at the earliest or

Use nitrogen blanket in bunker for storing coal for longer duration

bunker surface. Coal coming from stock

itself having fire

2. Empty the bunker by

other means

3. Use minimum water

(only if flames are

visible)

15. Fire in ESP





1. Flue gas temp at ESP

outlet is much higher

than ESP inlet temp.

2. Outside fire noticed by

personnel

3. ESP insulation showing

signs of internal fire

1. Reduce unit load to

65MW if fire is inside

ESP

2. Trip ESP field

3. Isolate the power

supply of particular

pass/field.

4. Close particular ESP

inlet & outlet gate

Oil/soot deposit on

ESP fields

Very high unburnt in fly

ash & hopper heating

element Not switching

off

ESP transformer fire

1. If fire is outside ESP,

use extinguisher &

douse the fire.

2. Inform fire man

3. Open ESP man holes

4. Open ESP ash

hopper drain

plugs/man hole

5. Quench the fire with

fire hydrant water

16. Fire in fuel oil storage





1. Fire noticed by

personnel.

2. Fire alarm. if actuated

in local by any persons

after observing fire

3. Burning smell

1. Stop HFO /LFO

pumps

2. Isolate electrical

supply for all related

equipments.

Electrical short circuit

Very high Oil

temperature.

External fire conveyed

to oil tank

Improper earthling

causing spark due to

static current

1. Inform fireman

2. Put hydrant system

with foam into service

& quench fire

3. If it is local fire douse

with extinguisher.

Emergency Procedure

17. Fuel oil leakage

Symptoms / parameter Immediate Operator Action Likely cause Subsequent operator Final corrective

effected action action

1. Oil leak noticed by

personnel

2. Oil pressure low alarm

1. Stop corresponding oil

pump. If leak is in pump

discharge line.

Fuel oil pipe

puncture by any

means.

Any control valve,

isolation valve,

pump gland/flange

leak

Gun leak due to

washer damaged.

1. Isolate leaking point

2. Inform fireman

3. Arrange to clean

leaked oil

Attend leaking

point

18. Generator winding temp raising fast

Symptoms / parameter

effectedImmediate Operator Action Likely cause

Subsequent operator

action

Final corrective

action

1. Generator winding

temp. high alarm.

2. Generator hot gas

temp>600C.

1. Reduce generator MVAR

loading to zero.

2. Reduce generator load

gradually till winding temp.

Raising trend reverses.

High MVAR loading

Overloading of

generator

ACW flow to

hydrogen cooler

low

Hydrogen cooler air

locked

1. Check ACW pressure

at Hydrogen cooler. If

required start standby

ACW pump.

2. Vent hydrogen cooler.

3. Fill hydrogen if

pressure is low.

19. Flash over



Subsequent operator

action

Final corrective

action

1. Observed by personnel

2. Fire alarm

1. Trip the switch gear in

which flash over has

occurred

Loose contacts

Short-circuits

Over load

If flashover is observed in

an equipment, then isolate

that equipment electrically

Insulation failure

Switching/lightning

voltage surges

20. Heater level going high



Subsequent operator

action

Final corrective

action

1. Heater level high alarm 1. If heater is not bypassed in

auto, bypass it on feed

water/condensate side.

2. Take heater level controls

in to manual and open it

fully

Drip control valve

failure.

Failure of drip auto

control due to

wrong level sensing

Heater Tube

leakage/failure

1. Check level locally and

confirm level

transmitter is reading

correct.

2. Open feed water side

IBV /condensate side

valve partially to

confirm whether

heater tube is leaking

If tube leak is

confirmed

isolate heater

totally and

release for

maintenance.

21. High axial shift



Subsequent operator

action

Final corrective

action

1. Axial shift high alarm

2. Turbine will trip at axial

shift very high limit of

0.5mm

3. Overloading of thrust

pads & thrust bearing

1. Reduce load to reduce

axial shift

2. Check all stop valves /

governing valves are

uniformly open

Abrupt change in

load

Sudden drop of

steam temperature

Sudden closure of

1. Maintain steam

parameter steady

2. If turbine has tripped

check vacuum breaker

has opened

3. Check vibrations

/return oil temp raise extraction valves

Too fast pick up of

load

Turbine overload

Silica deposits on

turbine blades

Turbine internal

damaged

GSC fan not

functioning

during coasting down

4. Note coasting down

time

5. If salting is suspected

arrange for early steam

washing of turbine or

other methods of

cleaning

22. Hydrogen leak from generator



Subsequent operator

action

Final corrective

action

1. H2 pressure in

generator casing low

alarm

2. Seal oil system fault

alarm

3. If seal oil pressure is

low standby oil pump

will start.

4. Winding temperature

may increase

5. Hot Gas temperature

may increase

1. If hydrogen pressure

reaches <1 ksc trip

generator & purge

generator with CO2

Seal oil running

pump trips &

standby AC & DC

pump fails to start

Seal oil pressure to

seal is low

DPR malfunction

Hydrogen leakage

developed in

generator system

Seal oil leakage

from

piping/valve/flanges

2. Try to establish seal oil

pressure by starting

stand by pump or by

closing DPRV inlet MIV

if seal oil pressure is

low.

3. If leaking point is

identified, try to isolate

it. If not possible,

23. LRSB not retracting


effectedImmediate Operator Action Likely cause Subsequent operator action

Final

corrective

action

1. LRSB not retracted

alarm

2. Observed from local

1. Reset the module & give

retract command from

local push button. If it

fails to retract even after

module is reset, switch-

off the module.

Forward motor trip

after advancing

Lance jammed after

advancing

LRSB clutch de

coupled after

advancing

Electrical supply

failure during

operation

Chain broken.

1. Reduce soot blower

header pressure to 3-

4Ksc.

2. Disengage the clutch and

try to retract manually from

handle. If it is retracting do

not release handle in the

middle ( If handle is to be

released in the middle, first

engage the clutch & then

only release) .

3. Inform maintenance if it is

not retracting manually

also.

4. Try retracting with

additional assistance for

If LRSB could

not retracted,

ask

maintenance to

insert dummy

in steam supply

line flange so

that other

blower

operation can

be carried out.

max. one hour.

5. If it could not be retracted

within one hour, reduce

pressure to zero ksc & try

again.

24. Lube oil leak/MOT level going low



Subsequent operator

action

Final corrective

action

1. MOT level low alarm

2. Oil pressure low alarm

if oil leak is from oil

supply line to bearing.

3. Oil leak observed from

local

1. If leak is more and could

not be isolated, reduce

load & trip the unit.

2. If leak is less and

confinable. Top up MOT

and inform firemen.

MOT drain is

opened

Lube oil cooler tube

leakage

Lube oil line/ flange

/filter leakage

Leakage from TG

1. Check any drain in

MOT area is open, if

open close it

2. If leakage is before

lube oil pump NRV

change over the pump

(change over will

Stop turbine

lube oil pump

after turbine

comes to

barring gear

and arrange

for attending

4. Oil collected in drain oil

tank/CEP pit

bearings

Seal oil system oil

leakage/seal oil

cooler tube leakage

Charging of

standby oil cooler

Oil entering

generator casing

from seals

Oil draining out

through centrifuge.

happen in auto on lube

oil pressure low)

3. Check centrifuge for

seal break and oil

draining out

4. Check oil channel

5. Check lube oil cooler

water side drain/vent

for presence of oil

6. Check seal oil cooler

water side drain/vent

for presence of oil

7. If any cooler leak is

noticed change over

that cooler.

leak.

Clean oil

leaked out to

avoid fire

hazard

25. Oil spill noticed in bottom ash hopper



Subsequent operator

action

Final corrective

action

1. Oil traces noticed in

bottom ash hopper from

local

2. Oil burner flame not

visible from peep hole

1. If any burner is in service

without flame, trip that

corner immediately

Burner in service

without flame

Oil nozzle valve

passing

Atomising steam/air

pressure very low

Oil specification

different from

designed one.

1. Check for the passing

oil gun & isolate it

2. Check for atomising

steam / air pressure

and adjust it

26. One of the turbine control valve fail to close



Subsequent operator

action

Final corrective

action

1. While reducing load, it

will not reduce below

certain MW even if load

set point is less

2. Stuck Valve position

feed back will show

open position control

room whereas other

valve will go for close.

3. High speed control will

act

1. Reduce turbine load to

100MW(if unit is in

service). If turbine has

tripped. close MS1.2.3 &4

& depressurise MS & RH

line

2. Open corresponding MAL

drain before & after control

valve(Partially)

Valve mechanically

stuck

Trip mechanism not

working

Oil not getting

drained from

actuator

1. If valve has stuck.

Reduce boiler pressure

& shut down unit.

27. One phase of the GT poles fail to open after unit trip



Subsequent operator

action

Final corrective

action

1. Pole Discrepancy alarm

will come

2. LBB protection will trip

all the breaker

connected to that bus

3. TG speed does not

drop after trip

4. TG draws current from

grid (reverse power)

5. Negative sequence

1. Trip all the 220 kV breaker

connected to the particular

bus including bus coupler.

(If LBB not acted)

2. Trip field breaker manually.

if it did not opened.

3. Open isolators of GT

breaker

Breaker contact

mechanically stuck

1. Normalise supply by

charging Line .ST and

Bus coupler.

Attend GT

breaker before

restarting

Turbine

current in Generator

6. LP exhaust temperature

going high

28. scanner fan tripped & DC fan fail to start



Subsequent operator

action

Final corrective

action

Scanner air to furnace DP low alarm

Scanner air fans tripped alarm

1. Trip the boiler Dc fan fails to start after AC fan trips

Both fan getting

over load/electrical

fault

1. Try to start fan by resetting overload relay

2. Increase FD fan discharge pressure so that some air will always available for scanner

3. If not happening reduce load to

Lightup boiler

only after

starting

scanner air

fam

minimum & get the fan started at the earliest.

4. If Scanner air fan could not be restarted even after reasonable time delay trip the boiler

29. seal oil pressure going low



Subsequent operator

action

Final corrective

action

1 Drum level dropping fasta Likely causes

One of the running BFP might have trippedSudden tripping of one or more Mills.Feeder might have tripped.FW control valve might have closed/stucked.Malfunction of auto control/scoop regulation.BFP recirculation might have opened of the running pump.Sudden reduction of load because of malfunction of EHTC.Sudden tube failure in water walls.HPBP might have opened.Inadvertent opening of EBD & low point drains.Drum pressure may be high.Drum level transmitters may be faulty.

b Plant responseDrum level LOW alarm appears.BFP's scoop rises to meet the demand if it is in auto.Boiler will trip on drum level very low.

In extreme case, if water level falls below visible range of gauge glass, may affect the flow through downcomers & may lead to tube failure.

c Parameters of concern.Main steam /reheater temperatures ,drum level,dearator level

d Immediate expected or desirable operator action.See that standby BFP starts on tripping of running BFP or manually start when level drops to -100 mmwc & load the pump to the running pumps scoop.Check for any malfunction of auto control like scoop not raising or recirculation open in auto, take control into manual & make up drum level.Close CBD if it is open.Close HPBP if it is open.Remove corex burners (when level is above (-100 mmwc)).Caution: Do not do any major removal of fuel at drum level (-100 mm & above., like mill tripping, burner removal)

e Final correction activity.Check drum level is getting stabilised.Ensure drum level controls are in auto.Check feedwater flows matches with steam flow for full load, if deviation is more then check for any leak in boiler area.Ensure for the availability of standby BFP as early as possible.Check for local level gauge & transmitters.Check boiler low point drains & EBD.Check for scoop controls for any linkage failures.

2 Drum level shooting up fasta Likely causes

Malfunction of feed controls.Sudden increase of load (due to malfunction of EHTC)Drum level transmitters may be faulty.Sudden increase of firing rate.Scoop /control valves might have stucked.Sudden opening of HPBP.

b Plant response

Drum level high alarm will appears.On drum level high high, boiler will trip.

c Parameters of concern.SH/RH temperatures drum level.

d Immediate expected or desirable operator action.Check the hydrostep level, if it is high take drum level control to manual & match feedwater flow with steam flow.Open emergency drain/CBD drain.Open MS strainer drains.Try to reduce the load so as to control the water level (if water level is due to upward load surge).

e Final correction activity.Check drum level is getting stabilised.Ensure drum level controls are in auto.Check feedwater flow matches with steam flow.Check for stuck of feed control valves & scoop.Check the level at local, hydrostep and transmitters are matching.

3 Rapid Boiler steam pressure risea Likely causes

Corex calorific value might have changed drastically.Sudden loading of mill.High firing rate.Feeder hunting.Malfunction of CMC.Sudden dropping of generator load.

b Plant responseHPBP will open if it is in auto.Reheater safety valve will popup first & then on high steam pressure, reaching in stages may blow EMRV & superheater SV & drum safety valves.Throttle pressure high alarm will appearsAPH FG I/L O2 low alarm will appearsDrum level will vary.

Generator will get more loaded because of pressure correction of EHTC.c Parameters of concern.

MS /RH temperature, Drum level, APH inlet O2, HP/LP bypass,d Immediate expected or desirable operator action.

Take the unit into manual mode if it is in CMC & reduce the fuel firing.For momentary action additional load can be taken Trip the malbehaving feeder/mill & reduce PA airflow through that mill.Check for pressure drop & if it is not holding remove the corex burners.Caution:Donot reduce the fuel when the drum level is around -100mmStart standby BFP when drum level reaches -100mm & rise the scoop to running BFP scoop.

e Final correction activity.Check for reseating of safety valveAs soon as the pressure starts dropping, restore the correct fuel input.Stop the third running BFP and keep it in standby.Ensure drum level got stabilised. Check for closure of HP bypass.Ensure pressure is stable.Bring back the unit load to normal.

4 EMRV floating and reseating in successiona Likely causes

Maloperation of valve.High fuel firing rate.MS pressure fluctuation.Maloperation of turbine control valve.

b Plant responseDrum level will vary.Generator load will vary.Hp bypass will open if it is in auto & may hunt.Ms temp and RH temp variation.

c Parameters of concern.Drum level, Ms temp and RH temp, MS pressure.

d Immediate expected or desirable operator action.Reduce the fuel firing if pressure is really high. If MS pressure is less, still EMRV is operating, keep selection switch to "OFF" so that the EMRV will not operate.Even by putting "off ", valve is still in open condition, its manual isolation valve can be closed.

e Final correction activity.Ensure for proper re-seating of the valve & put back in auto.

5 RH SV floating and reseating in successiona Likely causes

HP bypass might have opened in auto & LP bypass has not opened.Maloperation of valve.Opening /hunting of HP bypass.

b Plant responseHRH steam pressure high alarm will appear.MS and RH temp variationGenerator load will rise.Drum level will vary.

c Parameters of concern.Drum level, MS and RH temperature

d Immediate expected or desirable operator action.If LP bypass not opened, trip reset & open the valve by around 10% & put back in auto.Reduce the MS pressure, if it is actually high, so that HP bypass will close in auto.Reduce the load until the valve re-seat

e Final correction activity.Check for proper seating of the valve.Inform to maintenance isf & it is not re-seating at lower pressure also.

6 Corex CV decreasea Likely causes

Malfunction of COREX process. Variation in corex constituents %.

b Plant responseMs pressure will drop fastGenerator Load will drop.O2 at APH FG inlet will rise & high alarm may appears.

c Parameters of concern.MS pressure, load, APH flue gas inlet oxygen.

d Immediate expected or desirable operator action.Reduce load set point inorder to hold the boiler pressureEnquire EMD Dept about CV variation & if corex is stable then raise the feeding on running mills.

e Final correction activity.Ensure O2 at APH i/t is normalRestore the fuel input to boiler once the CV of corex stabilises.

7 Rapid Boiler steam pressure decreasea Likely causes

Sudden drop in Calorific value or pressure of corex.Tripping of mill or feeder.Sudden rise in load.Disturbed combustion conditions in furnace.Mill might have got unloaded.

b Plant responseMS pressure will drop.Generator load will come down.Drum level will drop.O2 at APH FG inlet will rise.

c Parameters of concern.Drum level, generator load, MS/RH temperatures, APH FG inlet O2.

d Immediate expected or desirable operator action.Check for any mill unloading.

Reduce load set point to hold the MS pressure around 110 kg/cm2.Check boiler flame, take oil elevation into service.(don't take oil when combustion conditions are very poor)Monitor drum levels during this disturbance, if it is dropping very fast, start standby BFP & load the scoop equal to running pump scoops.

e Final correction activity.Ensure drum level is stable.If mill is unloaded stop the mill & take other mill into service.Increase load set point to full load based on the fuel.Remove oil if it is introduced if furnace conditions are good or bright.

8 MS temperature rising fasta Likely causes

Inadequate spray due to malfunctions of spray control valves.Excess airflow.Instrument air pressure may not be adequate.Burner tilt Maloperation.Leakage in the spray line.Low feed water temperature.Ms pressure may be high.Heavy furnace slagging

b Plant responseMS/RH temperature high alarm will appear.Spray control valves will go for further opening.Load will rise for the same pressure.If temperature is very high ,turbine will trip."Positive" turbine expansion

c Parameters of concern.MS/RH temperatures, feedwater flow, drum level, HP exhaust temperature.

d Immediate expected or desirable operator action.Tilt burner down.Control the spray flow in manual so that stage -1 o/l temp will be around 450 deg.C &

stage -2 o/l temp around 505 deg.C, if temp control response is poor in autoIf rate of pressure rise is more, then pick up load if margin is there.Reduce firing rate (preferably top elevation).Reduce airflow based on the O2 percentage.

e Final correction activity.Introduce soot blowing if MS/RH temperatures are still maintaining high & spray quantity is more..Restore back the temp controls in auto if it has been taken in manualCheck for any malfunction of spray control valves & isolate such type of valve.Burner tilt can be kept horizontal.

9 RH temperature rising fasta Likely causes

Inadequate spray due to malfunctions of spray control valves.Cutting in of Top mill into service.Instrument air pressure may not be adequate.Cutting in corex in quick succession.Excess airflow.MS temperature may be high.MS pressure may be high.Leakage in the spray line.Heavy furnace slagging.Burner tilt Maloperation.

b Plant responseRH temperature high alarm will appear.RH metal temperatures high alarm will appear.Amount of spray will rise.Load will rise for the same pressure."Positive" turbine expansion.

c Parameters of concern.RH temp, drum level, feed water flow, feedwater differential pressure.

d Immediate expected or desirable operator action.

Control the spray flow manually at RH inlet around 250 deg.C, if temp control response is poor in auto.Tilt burner down. Check for MIV's open before & after spray control valvesReduce air flow if its more.If rate of pressure rise is more, then pick up load if margin is there.Reduce firing rate.

e Final correction activity.Introduce soot blowing if temperature is maintaining high & spray is high.Keep the burner tilt in horizontal condition.Restore back the control in auto if it has been taken in manual.

10 MS temperature falling fasta Likely causes

Tripping of top elevation millMalfunctioning of spray control valves.Less air flowInstrument air pressure may not be adequate.Low burner tiltMore sprayHigh feed water temperature

b Plant responseMS temperature low alarm will appear.Unit may trip on MS temp very low.Turbine expansion may become Negative.

c Parameters of concern.Ms temp, drum level, feed water flow.

d Immediate expected or desirable operator action.Close the spray control valves by taking into manual.Tilt burner upward.Check airflow &Rise if necessary.Top elevation mill can be taken into service /firing can be raised

Check for MIV open before & after control valves.e Final correction activity.

Initiate LRSB soot blowing if temperatures are maintaining still less.Observe for improvement in temperature.Restore back the controls in auto (spray control)Check for any malfunction of control valve & isolate it.

11 RH temperature falling fasta Likely causes

Less air flowTripping of top elevation millInstrument air pressure may not be adequate.Low burner tilt.More spray.Malfunctioning of spray control valves.

b Plant responseRH temperature low alarm will appear.Negative expansion of turbineUnit may trip on RH temp very low.

c Parameters of concern.MS/RH temp, drum level, feed water flow.

d Immediate expected or desirable operator action.Close the spray control valves by taking in manual.Tilt burner upward.Rise the Airflow.Top elevation mill can be taken into service /firing can be raised.

e Final correction activity.Initiate LRSB soot blowing if temperatures are maintaining still less.Observe for improvement in temperature.Restore back the controls in auto (spray control)Check for any malfunction of control valve & isolate it.

12 One of the Turbine control valve fails to closea Likely causes

Trip SOV may be problem.Trip coil faultyChoking in servo valve portsProblem in control valve linkage.Airlock in control oil systemMechanical problem

b Plant responseLoad huntingLoad cannot be varied as per requirementEHTC controller O/P will reduce very much to maintain same load .Speed fluctuation will occur during synchronising time.

c Parameters of concern.Speeds, Load, pressure, control oil pressure, and drum level, HP exhaust temperature.

d Immediate expected or desirable operator action.Inform immediately to Maintenance dept.Trip the unit ,if there is no any ready solutionCheck control oil pressure.

e Final correction activity.Ensure proper functioning of control valves

13 Control oil circulation pump faileda Likely causes

Pump may be tripped on any electrical protectionsb Plant response

Control oil tank temperature will rise.Control oil pressure may drop because of viscosity reduction.HSU Tank temperature high alarm will appear.

c Parameters of concern.Control oil temperature, HSU header pressure,

d Immediate expected or desirable operator action.

Check pump module along with electrical maintenance.Try to restart the pump as early as possible.

e Final correction activity.Ensure continuous running of the pump.

14 Control oil leakagea Likely causes

Damage in pipe line/pin hole puncture.N2 accumulator diaphragm might have punctured.Control oil pressure may be very high.

b Plant responseStandby pump will pick up on header pressure lowBecause of low pressure ,control valves may go for closeMS pressure may rise.LP bypass malfunction.Unit may trip.

c Parameters of concern.Unit load ,pressure, HSU pressure.

d Immediate expected or desirable operator action.If leakage is heavy, turbine to be tripped on fire protection channel.

If leakage is heavy personal safety to be ensured and fire fighting dept to be informed.

Locate point of leakage.e Final correction activity.

Stop S/B pumpEnsure leakage has been arrested fullyEnsure all the parameters are restored backEnsure control oil pressure is normal.

15 One of the Turbine control valve closesa Likely causes

Trip drain SOV may be problem.Trip coil faulty

Problem in control valve linkage.Mechanical problem.Airlock in control oil systemChoking in servo valve ports.

b Plant responseFirst stage pressure will rise than the normal value, if at all problem is there with IP control valve.HP exhaust temperature will rise.RH pressure will rise than the normal.RH Safety valves may pop.Thrust loading/axial shift may varyLoad huntingLoad cannot be varied as per requirementSpeed fluctuation will occur during synchronising time

c Parameters of concern.Load, pressure, control oil pressure, drum level, HP exhaust temperature, axial shift.

d Immediate expected or desirable operator action.Maintenance dept., to be informed immediatelyCheck for control oil pressureKeep standby pump running in manual mode.If possible reduces load and pressure.Control boiler firing.Control SH & RH temperature.

e Final correction activity.Ensure proper functioning of control valves.Restore back all the parameters.

emergency procedure final-1

Documents

water level

drum level controls

level drops

high level boiler

drum pressure

local level gauge transmitters

time deaerator level

scoop flow control valve