Thermal Power Plant - Emergency situations

1. BOILER EMERGENCYBOILER EMERGENCY
OPERATIONSOPERATIONS

2. BOILER EMERGENCIES –BOILER EMERGENCIES – Various EmergencyVarious Emergency
situations during operation with a special emphasissituations during operation with a special emphasis
on the safety aspect like boiler protection systemson the safety aspect like boiler protection systems
controls and interlockscontrols and interlocks
 Drum level lo and lo-loDrum level lo and lo-lo
 Drum level high and high highDrum level high and high high
 Furnace Draft high and high highFurnace Draft high and high high
 Flame FailureFlame Failure
 Boiler feed pump failureBoiler feed pump failure
 Boiler pressure highBoiler pressure high
 Furnace ExplosionFurnace Explosion
 Water wall / screen tube / evaporator tube failureWater wall / screen tube / evaporator tube failure
 Coal feeder trip / burner tripCoal feeder trip / burner trip

3.  APH tube failureAPH tube failure
 Fan FailureFan Failure
 Super heater tube failureSuper heater tube failure
 High super heater temperatureHigh super heater temperature
 Low Super heater temperatureLow Super heater temperature
 Bed Temperature HighBed Temperature High
 Bed Temperature LowBed Temperature Low
 PA fan tripPA fan trip
 PSH O/L steam temperature highPSH O/L steam temperature high
 Economizer O/L FW temperature highEconomizer O/L FW temperature high
 High negative draughtHigh negative draught
 Hot bed material leakage from PA lines or bed ash drainHot bed material leakage from PA lines or bed ash drain
 O/L steam pressure too lowO/L steam pressure too low
 Back fire in PA linesBack fire in PA lines

4. 1. DRUM LEVEL LOW AND LOW-LOW1. DRUM LEVEL LOW AND LOW-LOW
A.A. CAUSE :-CAUSE :-
 Failure of boiler feed pump.Failure of boiler feed pump.
 Failure of drum level controller.Failure of drum level controller.
 Inadvertent opening of C.B.D.Inadvertent opening of C.B.D.
 Extraordinary change in load.(Sudden reduction in load)Extraordinary change in load.(Sudden reduction in load)
 Water tube failure.Water tube failure.
B.B. EFFECT:-EFFECT:-
 Boiler may damage badly.Boiler may damage badly.

5. C.C. ACTION:-ACTION:-
 Run the boiler if drum level is within safe limit (Lo alarmRun the boiler if drum level is within safe limit (Lo alarm
and lo-lo alarm came). If it goes beyond safe limit allowand lo-lo alarm came). If it goes beyond safe limit allow
boiler to trip.boiler to trip.
 Check FW control valves position in DCS and in field, ifCheck FW control valves position in DCS and in field, if
feed valve is stuck up open parallel line valve or bypassfeed valve is stuck up open parallel line valve or bypass
valve.valve.
 Take care while increasing feed flow that running B.F.P.Take care while increasing feed flow that running B.F.P.
do not trip on feed flow high.do not trip on feed flow high.
 If low level is due to tripping of feed pump start stand byIf low level is due to tripping of feed pump start stand by
pump, if it is on manual.pump, if it is on manual.
 Check position of all MOVs and operate themCheck position of all MOVs and operate them
accordingly.accordingly.
 Check for any abnormal sound from furnace.Check for any abnormal sound from furnace.
 If water level is below safe level, allow to trip the boilerIf water level is below safe level, allow to trip the boiler
on drum level lo-lo to protect the boiler drum and tubes.on drum level lo-lo to protect the boiler drum and tubes.

6. 2. DRUM LEVEL HIGH AND HIGH HIGH :-2. DRUM LEVEL HIGH AND HIGH HIGH :-
A.A. CAISECAISE
 Failure of drum level controller.Failure of drum level controller.
 Extra ordinary increase in loadExtra ordinary increase in load
 Sudden increase in firing rate.Sudden increase in firing rate.
B.B. EFFECT:-EFFECT:-
 Water may enter turbine and serious damages to turbine mayWater may enter turbine and serious damages to turbine may
occur.occur.
 Joint valve on main steam pipe work leaks.Joint valve on main steam pipe work leaks.
 Carry over with sharp fall in super heater temperatureCarry over with sharp fall in super heater temperature

7. C.C. ACTION :-ACTION :-
 Run the boiler if drum level is within safe limit (drum levelRun the boiler if drum level is within safe limit (drum level
high and high high alarm came). If goes beyond limit allowhigh and high high alarm came). If goes beyond limit allow
boiler to trip.boiler to trip.
 Attempt to control with feed valve.Attempt to control with feed valve.
 Check FW control valves position in DCS and in field, if feedCheck FW control valves position in DCS and in field, if feed
valve is stuck up close isolating valve.valve is stuck up close isolating valve.
 Attempt to control drum level by opening C.B.D.Attempt to control drum level by opening C.B.D.
 Close Economizer inlet valve as per requirement and allowClose Economizer inlet valve as per requirement and allow
feed pump to run in Recirculation.feed pump to run in Recirculation.
 If above measures fail trip the feed pump.If above measures fail trip the feed pump.
 If level is due to sudden rise in load. If high level rises aboveIf level is due to sudden rise in load. If high level rises above
normal level – allow boiler to trip on drum level high high.normal level – allow boiler to trip on drum level high high.
 Operate IBD as per requirement...Operate IBD as per requirement...
 Observe Final steam temperature and if it starts dropping,Observe Final steam temperature and if it starts dropping,
close Boiler stop valve immediately.close Boiler stop valve immediately.

8. 3. FURNACE DRAFT HIGH AND HIGH HIGH3. FURNACE DRAFT HIGH AND HIGH HIGH
A.A. CAUSE :-CAUSE :-
 Due to faulty operation of fan control.Due to faulty operation of fan control.
 Disturbed combustionDisturbed combustion
 Un-controlled fuel entryUn-controlled fuel entry
B.B. EFFECT:-EFFECT:-
 Boiler may damage due to high furnace pressure.Boiler may damage due to high furnace pressure.
 Weak parts of furnace (ducting and enclosures) may explodeWeak parts of furnace (ducting and enclosures) may explode
due to high furnace pressure.due to high furnace pressure.
C.C. ACTION :-ACTION :-
 Confirm that the draught indication is correct.Confirm that the draught indication is correct.
 If it is due to faulty operation of I.D./P.A./S.A. fan control,If it is due to faulty operation of I.D./P.A./S.A. fan control,
take it on manual and maintain the furnace in suction.take it on manual and maintain the furnace in suction.
 If furnace pressure has increased beyond limit allow boiler toIf furnace pressure has increased beyond limit allow boiler to
trip on furnace draught high high.trip on furnace draught high high.

9. 4. FLAME FAILURE :-4. FLAME FAILURE :-
A.A. CAUSE :-CAUSE :-
 Dirty Oil BurnerDirty Oil Burner
 Furnace Pressure HighFurnace Pressure High
 Low Combustion AirLow Combustion Air
B.B. EFFECT :-EFFECT :-
 Boiler will trip on flame failureBoiler will trip on flame failure
 Chances of furnace explosion, if unburnt oil / coal mixture entered inChances of furnace explosion, if unburnt oil / coal mixture entered in
furnace.furnace.
 Boiler steam pressure may fall down.Boiler steam pressure may fall down.
 Super Heater Steam Temp. drop sharply.Super Heater Steam Temp. drop sharply.
 Variation observed in drum level. (drum level low)Variation observed in drum level. (drum level low)
C.C. ACTION :-ACTION :-
 Purge the boiler before putting burner back and purge burner as perPurge the boiler before putting burner back and purge burner as per
cycle time given by supplier.cycle time given by supplier.
 Clean the burner tip, if nozzles (holes) are found chocked.Clean the burner tip, if nozzles (holes) are found chocked.
 Check the air fan and maintain air fuel ratio.Check the air fan and maintain air fuel ratio.
 Check the explosion doors, close it if opened.Check the explosion doors, close it if opened.

10. 5. BOILER FEED PUMP FAILURE :-5. BOILER FEED PUMP FAILURE :-
A.A. CAUSE :-CAUSE :-
 Motor protection relay operatesMotor protection relay operates
 Lube oil temperature highLube oil temperature high
 Discharge flow highDischarge flow high
 Motor bearing temperature highMotor bearing temperature high
B.B. EFFECT :-EFFECT :-
 If standby pump is available, it will start on auto or start itIf standby pump is available, it will start on auto or start it
manually.manually.
 If standby pump does not start on auto & manual, drum levelIf standby pump does not start on auto & manual, drum level
may go very low, which may trip the boiler.may go very low, which may trip the boiler.

11. C.C. ACTION :-ACTION :-
 Start the stand by pump, if it does not start on auto. Adjust theStart the stand by pump, if it does not start on auto. Adjust the
load to maintain the drum level as well as to prevent theload to maintain the drum level as well as to prevent the
tripping of this pump on high feed water flow.tripping of this pump on high feed water flow.
 See the proper operation of recirculation valve and C.W.See the proper operation of recirculation valve and C.W.
Valve.Valve.
 Analyze and rectify the fault in the main feed pump. Put it onAnalyze and rectify the fault in the main feed pump. Put it on
auto.auto.
 Restore the bus supply, if it has lost and make the pumpRestore the bus supply, if it has lost and make the pump
available.available.
 Monitors drum level (Increase dumping CV opening, if drumMonitors drum level (Increase dumping CV opening, if drum
level starts dropping).level starts dropping).
 If both the BFP tripped and standby has not taken overIf both the BFP tripped and standby has not taken over
because of any common problem, trip both TG and box – upbecause of any common problem, trip both TG and box – up
the boiler.the boiler.

12. 6. BOILER PRESSURE HIGH6. BOILER PRESSURE HIGH
A.A. CAUSE :-CAUSE :-
 Sudden drop in load / steam flow.Sudden drop in load / steam flow.
 Un-controlled fuel entry.Un-controlled fuel entry.
 Turbine / prime mover trips.Turbine / prime mover trips.
B.B. EFFECT :-EFFECT :-
 Disturbance in drum water level.Disturbance in drum water level.
 Safety valves may life if pressure rise is up to that extent.Safety valves may life if pressure rise is up to that extent.
 Boiler may trip on high pressure.Boiler may trip on high pressure.
C.C. ACTION :-ACTION :-
 Open start up vent valve.Open start up vent valve.
 Control fuel input and drum level.Control fuel input and drum level.
 Check coal feeder feeding rate.Check coal feeder feeding rate.
 Adjust the load on unit, if it has dropped.Adjust the load on unit, if it has dropped.

13. 7. FURNACE EXPLOSIOIN7. FURNACE EXPLOSIOIN
A.A. CAUSE :-CAUSE :-
 Accumulation of unburnt fuel during light up / start up ofAccumulation of unburnt fuel during light up / start up of
boiler.boiler.
 Improper burning.Improper burning.
 Inadequate air.Inadequate air.
 Secondary combustion.Secondary combustion.
B.B. EFFECT :-EFFECT :-
 Furnace explosion can cause extensive damage.Furnace explosion can cause extensive damage.
C.C. ACTION :-ACTION :-
 Always purge the boiler with 40% full load air for about fiveAlways purge the boiler with 40% full load air for about five
minutes. No cut short in purging allowed.minutes. No cut short in purging allowed.
 Adjust fuel air ratio.Adjust fuel air ratio.

14. 8. WATER WALL / SCREEN TUBE / EVAPORATOR8. WATER WALL / SCREEN TUBE / EVAPORATOR
TUBE FAILURETUBE FAILURE
A.A. CAUSECAUSE :-:-
 Starved water wall.Starved water wall.
 Block tube, eroded tube, pitted tube, salt deposits.Block tube, eroded tube, pitted tube, salt deposits.
 Circulation affected due to open low point drains.Circulation affected due to open low point drains.
B.B. EFFECTEFFECT :-:-
 Hissing steam leakage noise from boiler.Hissing steam leakage noise from boiler.
 Unstable flame fluctuating draught.Unstable flame fluctuating draught.
 Bed temperature drops sharply.Bed temperature drops sharply.
 High feed water flow for given steam generation / increase inHigh feed water flow for given steam generation / increase in
make up water.make up water.
 Increase in I.D. Fan loading.Increase in I.D. Fan loading.
 Below screen temperature drops sharply.Below screen temperature drops sharply.
 Flue gas outlet temperature decreased.Flue gas outlet temperature decreased.

15. C.C. ACTION :ACTION :
 Every shift check low point drain valve are fully closed.Every shift check low point drain valve are fully closed.
 Every shift check the furnace listen furnace to detect steamEvery shift check the furnace listen furnace to detect steam
noise.noise.
 At first diagnostics of tube failure, start load reduction; tripAt first diagnostics of tube failure, start load reduction; trip
out unit before damage become serious. Quicker shutdownout unit before damage become serious. Quicker shutdown
reduces extensive damage.reduces extensive damage.
 Try to locate tube at low load .Try to locate tube at low load .
 Don’t allow the drum level to go beyond a danger level.Don’t allow the drum level to go beyond a danger level.
 Start another BFP, if drum level is not maintained byStart another BFP, if drum level is not maintained by
running BFP.running BFP.

16. 9. COAL FEEDER / BURNER FAILURE :-9. COAL FEEDER / BURNER FAILURE :-
A.A. CAUSE :-CAUSE :-
 Electrical supply failedElectrical supply failed
 V.F.D. faultV.F.D. fault
 Bed temperature highBed temperature high
 Furnace draft highFurnace draft high
 Furnace draft lowFurnace draft low
 Drum level highDrum level high
 Drum level lowDrum level low
B.B. EFFECT :-EFFECT :-
 Boiler pressure may fall downBoiler pressure may fall down
 SH steam temp fall sharply.SH steam temp fall sharply.
 Bed temp. will decrease.Bed temp. will decrease.
 Variation in furnace pressure (LOW)Variation in furnace pressure (LOW)
 Variation in drum level (Low)Variation in drum level (Low)

17. C.C. ACTION :-ACTION :-
 Increase feeding in other compartments or boiler.Increase feeding in other compartments or boiler.
 In case of any one DCF tripping, observe final steam pr. AndIn case of any one DCF tripping, observe final steam pr. And
temperature and if require isolate attemparator.temperature and if require isolate attemparator.
 Reduce PA / SA flow to control bed temp.Reduce PA / SA flow to control bed temp.
 Check PA header pr. If it is less increase it.Check PA header pr. If it is less increase it.
 Control furnace draft and drum level.Control furnace draft and drum level.
 Check for reason of DCF tripping.Check for reason of DCF tripping.
 Check electrical fault or emergency stop push button &Check electrical fault or emergency stop push button &
restart coal feeder.restart coal feeder.
 Check VFD fault, if any.Check VFD fault, if any.
 Restart coal feeder after checking cause of Boiler tripping &Restart coal feeder after checking cause of Boiler tripping &
put the burner in service.put the burner in service.
 Take burner support according to requirement.Take burner support according to requirement.
 If the problem persists for longer time and pressure drops,If the problem persists for longer time and pressure drops,
reduce load on turbine.reduce load on turbine.

18. 10. APH TUBE FAILURE10. APH TUBE FAILURE
A.A. CAUSE :-CAUSE :-
 Erosion of tube.Erosion of tube.
 Corrosion of tube.Corrosion of tube.
B.B. EFFECT :-EFFECT :-
 Flue gas temp after APH will fall down.Flue gas temp after APH will fall down.
 Increases in O2 percentage at ESP inlet.Increases in O2 percentage at ESP inlet.
 PA / FD Fan overloaded.PA / FD Fan overloaded.
 Bed temp may be increased.Bed temp may be increased.
C.C. ACTION :-ACTION :-
 Control flue gas temp by passes APH.Control flue gas temp by passes APH.
 Reduce coal feeding to maintain O2 percentage.Reduce coal feeding to maintain O2 percentage.
 Control bed temp.Control bed temp.
 If leakage of tubes are more stop the boiler and plug /If leakage of tubes are more stop the boiler and plug /
replaced.replaced.

19. I.I. ID FANID FAN
A.A. CAUSECAUSE :-:-
 Electrical motor protectionElectrical motor protection
 Fan bearing temp becomes high highFan bearing temp becomes high high
 Motor bearing temp becomes very highMotor bearing temp becomes very high
 Drive fault (MCC fault)Drive fault (MCC fault)
 Boiler tripBoiler trip
B.B. EFFECTEFFECT :-:-
 Furnace may get pressurizedFurnace may get pressurized
 Boiler will trip on boiler furnace pressure high.Boiler will trip on boiler furnace pressure high.
11. LOSS OF FANS11. LOSS OF FANS

20. C.C. ACTION :-ACTION :-
 Check emergency or field stop.Check emergency or field stop.
 Rectify electrical fault, if any.Rectify electrical fault, if any.
 Check cause for boiler trip & normalize it.Check cause for boiler trip & normalize it.
 Check fan / motor-bearing temp.Check fan / motor-bearing temp.
 Restart I.D. Fan after checking cause of tripping andRestart I.D. Fan after checking cause of tripping and
taking corrective actions.taking corrective actions.
 Cut down air flow by operating FD dampers.Cut down air flow by operating FD dampers.
 Slump two compartments.Slump two compartments.
 Reduce load on turbine according to requirement.Reduce load on turbine according to requirement.

21. II.II. P.A. FANP.A. FAN
A.A. CAUSE :-CAUSE :-
 Electrical motor protection.Electrical motor protection.
 Fan bearing temp. becomes high high.Fan bearing temp. becomes high high.
 Motor bearing temp. becomes very high.Motor bearing temp. becomes very high.
 MCC fault.MCC fault.
 Boiler trip.Boiler trip.
 Run feed back off.Run feed back off.
 ID Fan trip.ID Fan trip.
B.B. EFFECT :-EFFECT :-
 Boiler will trip onBoiler will trip on
 Furnace draft lowFurnace draft low
 P.A. flow low.P.A. flow low.

22. C.C. ACTION :-ACTION :-
 Rectify electrical fault, if any.Rectify electrical fault, if any.
 Check cause for boiler trip and normalize it.Check cause for boiler trip and normalize it.
 Check fan / motor-bearing temp.Check fan / motor-bearing temp.
 Restart the P.A. Fan after checking the cause of trippingRestart the P.A. Fan after checking the cause of tripping
and taking corrective actions.and taking corrective actions.
 Check that whether all DCF got tripped or not. OtherwiseCheck that whether all DCF got tripped or not. Otherwise
stop them immediately.stop them immediately.
 Reduce the load on turbine according to requirementReduce the load on turbine according to requirement
 See that the standby fan is started. Otherwise start it andSee that the standby fan is started. Otherwise start it and
increase the PA header pr.increase the PA header pr.
 Check PA lines for jamming and clear them accordingly.Check PA lines for jamming and clear them accordingly.

23. III.III. FD FAN :-FD FAN :-
A.A. CAUSE :-CAUSE :-
 Electrical motor protection.Electrical motor protection.
 Fan bearing temp becomes high high.Fan bearing temp becomes high high.
 Motor bearing temp becomes very high.Motor bearing temp becomes very high.
 MCC fault.MCC fault.
 Boiler trip.Boiler trip.
 Run feed back off.Run feed back off.
 I.D. Fan trip.I.D. Fan trip.
 PA Fan trip.PA Fan trip.
B.B. EFFECT :-EFFECT :-
 Boiler will trip on low furnace draft.Boiler will trip on low furnace draft.

24. A.A. ACTIONS :-ACTIONS :-
 Rectify electrical fault, if any.Rectify electrical fault, if any.
 Check cause for boiler, trip & normalize it.Check cause for boiler, trip & normalize it.
 Check fan / motor-bearing temp.Check fan / motor-bearing temp.
 Stop coal feeding.Stop coal feeding.
 Reduce load on Turbine according to requirementReduce load on Turbine according to requirement
 Observe Bed temperatureObserve Bed temperature
 Restart the FD Fan after checking the cause of tripping andRestart the FD Fan after checking the cause of tripping and
taking corrective actionstaking corrective actions

25. 12. SUPER HEATER TUBE FAILURE :-12. SUPER HEATER TUBE FAILURE :-
A.A. CAUSE :-CAUSE :-
 Sustaining high metal temp due to water wall slugging orSustaining high metal temp due to water wall slugging or
inadequate steam flow and high gas temp during hot start.inadequate steam flow and high gas temp during hot start.
 Erosion on tubes due to high excess air.Erosion on tubes due to high excess air.
 Blocked tubes.Blocked tubes.
 Starvation of tubes.Starvation of tubes.
 Salt deposition due to high water level in drum. Poor qualitySalt deposition due to high water level in drum. Poor quality
of spray water.of spray water.

26. B.B. EFFECT :-EFFECT :-
 Hissing noise notices.Hissing noise notices.
 Flue gas temp drops.Flue gas temp drops.
 High feed water consumption compared to steam flow.High feed water consumption compared to steam flow.
 Over loading on I.D. Fan.Over loading on I.D. Fan.
 Erosion of other tubes and damages to other APH tubes.Erosion of other tubes and damages to other APH tubes.
C.C. ACTION :-ACTION :-
 As soon as leakages noticed start reducing the load and tripAs soon as leakages noticed start reducing the load and trip
the boiler.the boiler.
 Listen the SH region for steam leakage.Listen the SH region for steam leakage.
 Try to locate leakage through manholes before the boiler isTry to locate leakage through manholes before the boiler is
depressurized.depressurized.

27. 13. HIGH SUPER HEATER TEMP13. HIGH SUPER HEATER TEMP
A.A. CAUSE :-CAUSE :-
 High excess air.High excess air.
 Low feed water temp HP Heater not in service at constantLow feed water temp HP Heater not in service at constant
firing / load.firing / load.
 Sudden increase in firing rate to increase steam pressure.Sudden increase in firing rate to increase steam pressure.
 In adequate spray.In adequate spray.
 Lodging of soot on the water walls considerably.Lodging of soot on the water walls considerably.
B.B. EFFECT :-EFFECT :-
 Rise in (+ve) positive turbine expansion.Rise in (+ve) positive turbine expansion.
 Creep rate increase in tube metal, turbine parts, steamCreep rate increase in tube metal, turbine parts, steam
piping.piping.

28. C.C. ACTION :-ACTION :-
 Check feed water temp. If HP heaters are available, put inCheck feed water temp. If HP heaters are available, put in
service and if not reduce the load.service and if not reduce the load.
 Slow down firing rate.Slow down firing rate.
 Reduce excess air, if more.Reduce excess air, if more.
 Check attemparator control valve position in DCS and inCheck attemparator control valve position in DCS and in
field, Take attemparator by – pass into service.field, Take attemparator by – pass into service.
 Increase load on boiler.Increase load on boiler.
 Observe the TG inlet steam temperature.Observe the TG inlet steam temperature.
 Ensure that none of drum safety valve has popped.Ensure that none of drum safety valve has popped.

29. 14. LOW SUPER HEATER TEMP. :-14. LOW SUPER HEATER TEMP. :-
 CAUSE :-CAUSE :-
 Dirty super heaterDirty super heater
 Inadequate air flow.Inadequate air flow.
 High SprayHigh Spray
 Too high feed water temp.Too high feed water temp.
 Sharp increase in load and pressure drop.Sharp increase in load and pressure drop.
 High Drum level.High Drum level.
 EFFECT :-EFFECT :-
 Turbine expansion may be negative.Turbine expansion may be negative.
 May induce thermal stresses in S.H.May induce thermal stresses in S.H.

30. C.C. ACTION :-ACTION :-
 Check air flow – increase, if necessary.Check air flow – increase, if necessary.
 Isolate attemparator and check for passing/opening of attemparatorIsolate attemparator and check for passing/opening of attemparator
by – pass..by – pass..
 Check feed water temp.Check feed water temp.
 Avoid sharp rise in load to boiler pressure drop.Avoid sharp rise in load to boiler pressure drop.
 If, it is due to high drum level – allow unit to trip and open mainIf, it is due to high drum level – allow unit to trip and open main
steam drains.steam drains.
 If main steam temperature drop takes place open steam pipe drains.If main steam temperature drop takes place open steam pipe drains.
 Observe constantly the TG inlet steam temperature. Trip the turbine /Observe constantly the TG inlet steam temperature. Trip the turbine /
prime mover when steam temperature falls.prime mover when steam temperature falls.
 Reduce load on boiler.Reduce load on boiler.
 Check bed temperatures and increase coal feeding accordingly.Check bed temperatures and increase coal feeding accordingly.
 Check for jamming of coal hopper, PA lines and clear themCheck for jamming of coal hopper, PA lines and clear them
accordingly.accordingly.
 Take burner support if required.Take burner support if required.
 Ensure that DCF chain is rotating (no shear pin failure).Ensure that DCF chain is rotating (no shear pin failure).
 Ensure that air flow is sufficient.Ensure that air flow is sufficient.
 Drain bed material slowly, if bed height is more.Drain bed material slowly, if bed height is more.

31. 15. BED TEMP. HIGH :-15. BED TEMP. HIGH :-
A.A. CAUSE :-CAUSE :-
 High CV and low ash coal used.High CV and low ash coal used.
 Low P.A. flow / FD flowLow P.A. flow / FD flow
 Sudden change in loadSudden change in load
 Faulty bed temp thermocouple.Faulty bed temp thermocouple.
 Ash recalculating system troubleAsh recalculating system trouble
B.B. EFFECT :-EFFECT :-
 Chances of clinker formationChances of clinker formation
 Chances of refractory failureChances of refractory failure
 Chances of screen tube failureChances of screen tube failure

32. C.C. ACTION :-ACTION :-
 Control bed temp by recirculation ash throughControl bed temp by recirculation ash through
recirculation feeder.recirculation feeder.
 Charge bed material if bed height permits.Charge bed material if bed height permits.
 Increase P.A. flow up and increase FD flow.Increase P.A. flow up and increase FD flow.
 Constantly observe the wind box pr.Constantly observe the wind box pr.
 Reduce the load by cutting coal feeder.Reduce the load by cutting coal feeder.
 Coal feeders trip, if temp rises above limit and allowCoal feeders trip, if temp rises above limit and allow
boiler to trip, if temp exceeds beyond safe limit toboiler to trip, if temp exceeds beyond safe limit to
save bed from clinker formation.save bed from clinker formation.
 Check the bed temp thermocouple.Check the bed temp thermocouple.
 Check for wind box damper position.Check for wind box damper position.
 Stop the boiler if temperatures still not controlled.Stop the boiler if temperatures still not controlled.

33. 16. BED TEMP LOW :-16. BED TEMP LOW :-
A.A. CAUSE :-CAUSE :-
 High PA with respect to load / high FD flowHigh PA with respect to load / high FD flow
w.r.t. load.w.r.t. load.
 Low CV high ash coal used.Low CV high ash coal used.
 Coal interruption or coal feeder trips orCoal interruption or coal feeder trips or
overfeeding of coal into furnace.overfeeding of coal into furnace.
 Recirculation ash feeder speed may increase.Recirculation ash feeder speed may increase.
 Faulty bed temp. Thermocouple.Faulty bed temp. Thermocouple.
 Water tube / screen tube / evaporator tube failure.Water tube / screen tube / evaporator tube failure.

34. B.B. EFFECT :-EFFECT :-
 Boiler steam flow will reduce.Boiler steam flow will reduce.
 Super heater temp drops.Super heater temp drops.
 Furnace draft will fluctuate.Furnace draft will fluctuate.
C.C. ACTION :-ACTION :-
 Reduce P.A. Fan flow, if excessive / reduce FD. flow, ifReduce P.A. Fan flow, if excessive / reduce FD. flow, if
excessive.excessive.
 Reduce speed of recirculation ash feeder.Reduce speed of recirculation ash feeder.
 Stop bed material supply, if running.Stop bed material supply, if running.
 Check bed temp thermocouple.Check bed temp thermocouple.
 Check any leakage sound from furnace.Check any leakage sound from furnace.
 Check coal feeder and coal supply.Check coal feeder and coal supply.

35. 17.17. PSH O/L steam temperature highPSH O/L steam temperature high
 Increase load on boiler.Increase load on boiler.
 Minimize furnace draught.Minimize furnace draught.
 Check the position of overfeed secondary air dampers andCheck the position of overfeed secondary air dampers and
open them.open them.
 Regulate air flow according to requirement.Regulate air flow according to requirement.
 Increase bed height.Increase bed height.
 Meanwhile confirm that the temperature indication isMeanwhile confirm that the temperature indication is
correct (Attemperator flow will increase)correct (Attemperator flow will increase)

36. 18.18. Economizer O/L FW temperature highEconomizer O/L FW temperature high
 Increase load on boiler.Increase load on boiler.
 Reduce Economizer I/L feed water temperature.Reduce Economizer I/L feed water temperature.
 Minimize furnace draught.Minimize furnace draught.
 Check the position of overfeed secondary airCheck the position of overfeed secondary air
dampers and open them.dampers and open them.
 Regulate air flow according to requirement.Regulate air flow according to requirement.
 Increase bed height.Increase bed height.
 Meanwhile confirm that the temperatureMeanwhile confirm that the temperature
indication is correct.indication is correct.

37. 19.19. High negative draughtHigh negative draught
 Confirm that the draught indication is correct.Confirm that the draught indication is correct.
 Check and control ID fan speed.Check and control ID fan speed.
 Check wind box dampers position.Check wind box dampers position.
 Check ID dampers position.Check ID dampers position.
 Check FD dampers position.Check FD dampers position.
 Check APH online and by – pass dampers position.Check APH online and by – pass dampers position.

38. 20.20. Hot bed material leakage from PA lines orHot bed material leakage from PA lines or
bed ash drain/Back fire in PA linesbed ash drain/Back fire in PA lines
 Observe bed temperatures constantly and chargeObserve bed temperatures constantly and charge
bed material if required.bed material if required.
 Cut down coal feeding to that compartment, let theCut down coal feeding to that compartment, let the
bed temperature be drop down and close wind boxbed temperature be drop down and close wind box
damper.damper.
 Check that air damper of that line is open.Check that air damper of that line is open.
 Clear that line if the leakage is from verticalClear that line if the leakage is from vertical
portion.portion.
 If the leakage increases further, stop the boiler.If the leakage increases further, stop the boiler.

39. 21.21. O/L steam pressure too lowO/L steam pressure too low
 Check for passing or malfunctioning of Boiler safetyCheck for passing or malfunctioning of Boiler safety
valves.valves.
 Check for abnormal sound from furnace.Check for abnormal sound from furnace.
 Check for malfunctioning of Dumping control valve andCheck for malfunctioning of Dumping control valve and
PRDS control valve.PRDS control valve.
 Check and increase the feed water temperature.Check and increase the feed water temperature.
 If pressure goes down further and frequency drops, reduceIf pressure goes down further and frequency drops, reduce
load on turbine.load on turbine.

40. TURBINE EMERGENCIESTURBINE EMERGENCIES

41. TURBINE EMERGENCIESTURBINE EMERGENCIES
• Turbine tripTurbine trip
• Load throw offLoad throw off
• UAT tripUAT trip
• CEP tripCEP trip
• Hotwell level highHotwell level high
• Hotwell level lowHotwell level low
• Vacuum dropVacuum drop
• Fire/smoke at turbine areaFire/smoke at turbine area
• Turning gear tripTurning gear trip
• Oil temperature highOil temperature high
• Bearing temperature highBearing temperature high
• Bearing vibration highBearing vibration high
• Steam pressure high after first stageSteam pressure high after first stage

42. Turbine trip (sharing mode)Turbine trip (sharing mode)
 Safeguard the running unit (Reduce load on turbine ifSafeguard the running unit (Reduce load on turbine if
required and Ensure that CWP, BFP, ACWP, CT Fan,required and Ensure that CWP, BFP, ACWP, CT Fan,
Inst.air compressor are running)Inst.air compressor are running)
 Cut down proportionate coal feeding in boilers.Cut down proportionate coal feeding in boilers.
 Observe boiler drum level and take steps accordingly.Observe boiler drum level and take steps accordingly.
 Control steam pressure by operating PRDS and dumpingControl steam pressure by operating PRDS and dumping
control valves.control valves.
 Start AOP, JOP, TTG.Start AOP, JOP, TTG.
 Investigate the reason of tripping.Investigate the reason of tripping.
 Don’t switch on PEF until unless it is reset and loadDon’t switch on PEF until unless it is reset and load
shedding is switched – off.shedding is switched – off.

43. Turbine trip (Non – sharing mode)Turbine trip (Non – sharing mode)
 Safeguard the running unit (Reduce load on turbine if requiredSafeguard the running unit (Reduce load on turbine if required
and Ensure that CWP, BFP, ACWP, CT Fan, Inst.airand Ensure that CWP, BFP, ACWP, CT Fan, Inst.air
compressor are running)compressor are running)
 Take grid supply after ensuring Generator breaker has opened.Take grid supply after ensuring Generator breaker has opened.
 Observe boiler drum level and take steps accordingly.Observe boiler drum level and take steps accordingly.
 Control steam pressure by operating PRDS and dumpingControl steam pressure by operating PRDS and dumping
control valves.control valves.
 Ensure that extraction MOV is closed.Ensure that extraction MOV is closed.
 Start AOP, JOP, TTG.Start AOP, JOP, TTG.
 Investigate the reason of tripping.Investigate the reason of tripping.
 Don’t switch on PEF until unless it is reset and load sheddingDon’t switch on PEF until unless it is reset and load shedding
is switched – off.is switched – off.
 Maintain hotwell level and ensure that CEP is running.Maintain hotwell level and ensure that CEP is running.

44. Load throw – offLoad throw – off
 Check turbine speed, if it is at alarming level and isCheck turbine speed, if it is at alarming level and is
increasing further, trip the turbine.increasing further, trip the turbine.
 Observe drum level.Observe drum level.
 Slump compartments in boiler according to the amount ofSlump compartments in boiler according to the amount of
load thrown off.load thrown off.
 Take PRDS into service if both extractions are out ofTake PRDS into service if both extractions are out of
service.service.
 Regulate dumping steam according to dumping headerRegulate dumping steam according to dumping header
temperature and condenser vacuum.temperature and condenser vacuum.
 Check for reason of load throw – off.Check for reason of load throw – off.
 If the load throw – off occurs because of any breakerIf the load throw – off occurs because of any breaker
opening, check thoroughly before closing it.opening, check thoroughly before closing it.

45. CEP tripCEP trip
 Ensure that standby pump has taken over.Ensure that standby pump has taken over.
 Check for reason of tripping.Check for reason of tripping.
 Check hotwell level and if it is low, take make – up waterCheck hotwell level and if it is low, take make – up water
into hotwell.into hotwell.
 Open hotwell re – circulation valve fully.Open hotwell re – circulation valve fully.
 Check for passing of condensate valve B or C and isolateCheck for passing of condensate valve B or C and isolate
them accordingly.them accordingly.
 If the tripping is because of overload, check for mechanicalIf the tripping is because of overload, check for mechanical
jamming of pumpjamming of pump..

46. Hotwell levelHotwell level
A.A. Hotwell level highHotwell level high
 Ensure that standby pump has taken over.Ensure that standby pump has taken over.
 Check running CEP (s) load.Check running CEP (s) load.
 Close hotwell re – circulation valve.Close hotwell re – circulation valve.
 Check position of condensate valve B or C and operateCheck position of condensate valve B or C and operate
them accordingly.them accordingly.
B.B. Hotwell level lowHotwell level low
 Take make – up water into hotwell.Take make – up water into hotwell.
 Open hotwell re – circulation valve fully.Open hotwell re – circulation valve fully.
 Check for passing of condensate valve B or C and isolateCheck for passing of condensate valve B or C and isolate
them accordingly.them accordingly.

47. Vacuum dropVacuum drop
 Check gland steam pressure.Check gland steam pressure.
 Check CW temperatures.Check CW temperatures.
 Check hotwell level.Check hotwell level.
 Check the running ejector.Check the running ejector.
 Check for air ingress from all vacuum related lines andCheck for air ingress from all vacuum related lines and
valves.valves.
 Cut down dumping steam.Cut down dumping steam.
 Charge standby ejector if the rate of drop is more.Charge standby ejector if the rate of drop is more.
 If the rate of drop is more, reduce load on turbine.If the rate of drop is more, reduce load on turbine.

48. Fire/smoke at turbine areaFire/smoke at turbine area
 Ensure that vapour extraction fan is running if the fire isEnsure that vapour extraction fan is running if the fire is
because of oil leakage from any bearing.because of oil leakage from any bearing.
 Use CO2 fire extinguisher in case of minor oil andUse CO2 fire extinguisher in case of minor oil and
electrical fires. Don’t use water or other type of fireelectrical fires. Don’t use water or other type of fire
extinguishers.extinguishers.
 In case of major fire, first isolate the source (trip the turbineIn case of major fire, first isolate the source (trip the turbine
and isolate generator from electrical circuit) and thenand isolate generator from electrical circuit) and then
quench it.quench it.

49. Turning gear tripTurning gear trip
 Ensure that jacking oil pressure is sufficient.Ensure that jacking oil pressure is sufficient.
 Ensure that lube oil pressure is sufficient.Ensure that lube oil pressure is sufficient.
 Put turbine on manual barring gear.Put turbine on manual barring gear.
 Check for reason of turning gear trip.Check for reason of turning gear trip.

50. Oil temperature highOil temperature high
 Ensure that the CW temperatures are not on higherEnsure that the CW temperatures are not on higher
side (All CT fans are running).side (All CT fans are running).
 Stop TOPP if it is running.Stop TOPP if it is running.
 Check oil level in Main oil tank.Check oil level in Main oil tank.
 Provide external cooling arrangement.Provide external cooling arrangement.
 Ensure that oil temperature controller is working.Ensure that oil temperature controller is working.
 If the bearing temperatures start increasing, trip theIf the bearing temperatures start increasing, trip the
turbine immediately and provide external coolingturbine immediately and provide external cooling
arrangement for bearings.arrangement for bearings.

51. Bearing temperature highBearing temperature high
 Charge bleed steam.Charge bleed steam.
 Check oil temperature.Check oil temperature.
 Check oil level in Main oil tank.Check oil level in Main oil tank.
 Ensure proper oil flow to the bearing.Ensure proper oil flow to the bearing.
 Check axial shift.Check axial shift.
 Provide external cooling arrangement.Provide external cooling arrangement.
 Reduce load on turbine if temperatures goes on rising.Reduce load on turbine if temperatures goes on rising.

52. Bearing vibration highBearing vibration high
 Confirm that the signal is correct and is matching withConfirm that the signal is correct and is matching with
Bently – Nevada vibration monitoring system.Bently – Nevada vibration monitoring system.
 Confirm the same in field physically.Confirm the same in field physically.
 Ensure proper oil flow to the bearing.Ensure proper oil flow to the bearing.
 Check casing temperature difference.Check casing temperature difference.
 Reduce load on turbine if vibration goes on rising.Reduce load on turbine if vibration goes on rising.

53. Steam pressure high after first stageSteam pressure high after first stage
 Reduce load on turbine if pressure is at alarming level.Reduce load on turbine if pressure is at alarming level.
 Reduce bleed steam.Reduce bleed steam.
 Check control valve position and turbine speed.Check control valve position and turbine speed.

54. CWP trip/ Discharge header pr. lowCWP trip/ Discharge header pr. low
 Ensure that standby pump has taken over.Ensure that standby pump has taken over.
 Monitor condenser vacuum.Monitor condenser vacuum.
 Reduce load on TG.Reduce load on TG.
 Cut down dumping.Cut down dumping.
 Investigate the reason for tripping.Investigate the reason for tripping.
 If both the CWP tripped and standby has not taken overIf both the CWP tripped and standby has not taken over
because of any common problem, trip both TG and isolatebecause of any common problem, trip both TG and isolate
all steam inputs to the condenser.all steam inputs to the condenser.

55. Inst. Air compressor trip/Inst. Air pr. lowInst. Air compressor trip/Inst. Air pr. low
 Ensure that standby compressor has taken over.Ensure that standby compressor has taken over.
 Check conserveir O/L air pr.Check conserveir O/L air pr.
 Monitor boiler drum level, furnace draft, CWPMonitor boiler drum level, furnace draft, CWP
discharge header pr., FD control dampers positiondischarge header pr., FD control dampers position
constantly.constantly.
 Ensure that running compressor is fully loaded.Ensure that running compressor is fully loaded.
 Check for choking of dryer filters.Check for choking of dryer filters.
 Ensure that both dryers power supply is ON.Ensure that both dryers power supply is ON.
 Check for leakages in the system.Check for leakages in the system.