POWER PLANT EMERGENECIES*PMI Revision 00 *

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Presentation outline*PMI Revision 00 *Boiler EmergenciesTurbine EmergenciesGenerator EmergenciesGrid Failure

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BOILER*PMI Revision 00 *

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HIGH FURNACE PRESSURE

One I.D. Fan tripped or Mal-operationof control vanes of I.D./F.D./P.A. Fans or closing of damper Unstable furnace flame conditions. Sudden starting of coal mill. Furnace water seal broken, E.P. or flue gas path manhole opened.Water wall tube rupture/leakage.

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ID FAN LUB. OIL PRESSURE / BEARING TEMP TROUBLELub. oil pressure may be inadequate.Lub. oil filters may be choked.Greasing long overdue in fan bearings.Corresponding alarm will indicate the problem area.

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ID FAN TRIP

Motor over-loaded.Corresponding FD Fan has tripped.Spurious electrical fault.Lub. Oil pressure problem.Bearing temperature problem. Corresponding APH may have tripped.

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FURNACE PRESSURE LOW

I.D. Fan auto control Failure.I.D. Fan vane control mechanism Failure causing vanes to open wide.Sudden decrease in air input or tripping of one F. D. fan.Sudden tripping of one or more mills or choking of mill/raw coal Feeder pipe.

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FD FAN TRIPPED

Motor over-loadedLub oil pressure trouble.Bearing temperature trouble.ID fan has tripped.FD lub. Oil pressure low.*PMI Revision 00 *

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PA FAN TRIPPED

tripping is due to high bearing temp.Boiler has tripped.Lub. Oil pressure may be very low.It will lead to tripping of some mills in service.

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AIR PRE-HEATER

AIR PRE HEATER BEARING TEMPERATURE VERY HIGH.AIR PRE-HEATER ELECTRIC MOTOR TRIPPED.APH ELECTRIC DRIVE TRIPPED AND AIR MOTOR FAILS TO START.AIR PRE-HEATER ON FIRE.

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DRUM LEVEL LOW

Mal-operation of Feed Auto Control or Feed Regulator or scoop auto.Tripping of one of working feed pump (standby pump does not start)Sudden increase of load.Sudden increase in firing rate, e.g.starting of mills having sufficient coal left before previous stopping.Tube repture/puncture of low point drain valves or Emergency drum drain Valve Inadvertant opening of low point drain valves or Emergency drum drain valve.

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HIGH DRUM LEVEL

Mal-operation of feed water control.Sudden decrease in firing rate e.g. tripping of the running mills.B.F.P. Scoop tube position suddenly increased.

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FLAME FAILURE AT AN ELEVATION

Closing of trip valves on H.O. , W.U. Oil/ Ignitor (Causing loss of ignition support energy) Where F.O. is being used as support fuel or when only oil is being usedSudden decrease of mill feeder speeds to minimum.Too low or too high windbox pressure causing unstable combustion.Water wall tube failureMalfunction of flame scanners due to supply failure or scanner air failure, slag or soot on scanner lenses etc.Burner tilt mechanism negative extreme due to air failure to power cylinders.

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ONE FEEDER TRIPS

Support energy is removed within 3 minutes of feeder starting. No coal flow alarm comes & low current relay picks up simultaneously.(Feeder shear pin given way)Mill trips,Feeder motor supply fails

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ONE MILL TRIPS

Mill discharge valves are closedLoss of elevation D.C. supply for more than 2 secs.Support ignition energy is removed Within 3 minutes of feeder starting.Motor protection operates.One P.A. Fan trips (mill in excess of 3 will trip starting from bottom).

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WATER WALL TUBE LEAKAGE

Starved water walls due to very low drum level.Sustained flame impingement on water wall tubes.Blocked tube, scaling of tube, resulting in overheating of tube metal, pitting, corrosion of tubes.Soot blower steam impingement (wet steam impingement or direct impingement of steam).Circulation affected due to opening of low point drains.

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REHEATER/SUPERHEATER/ ECONOMISER TUBE FAILURE

Sustained high metal temperatures due to waterwall Slagging or forcing boiler at the time of hot restart.Erosion on tubes due to high excess air, high ash content in coal dislocated tubes, soot blowing.Blocked tubes causing overheating.Salt deposition due to high water level in drum, poor quality of water.Inadequate flow due to open superheater, reheater drain.

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Problem in Bottom Ashing SystemContinuous watch on ash build upReduce loadStopping of unit*PMI Revision 00 *

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TURBINE*PMI Revision 00 *

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TURBINE EMERGENCIESSUDDEN LOAD THROW OFFSUDDEN INCREASE OF LOAD FROM FULL LOADVIBRATION HIGHTURBINE OVER SPEEDMOT LEVEL LOWTURBINE BEARING OIL PRESS LOW BEARING OIL INLET TEMP. HIGHDIFFERENTIAL EXPANSION HI/LOWAXIAL SHIFT HIGHLOSS OF VACUUMLOSS OF BARRING GEAR OR BARRING GEAR FAILS TO START

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HOTWELL LEVEL LOW

Excessive flow to D/A from HotwellSome leakage in steam/water (feed) circuit (water-wall super heater, Economiser etc.).ACS Xmitter failure/fault.DM make-up may be inadequate.DM make up pump may have tripped.

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HOTWELL LEVEL HIGH.

Malfunctioning of condensate PP valveMalfunctioning of DM make up valve.Condenser tube leakageToo much DM make-up to Hotwell.Hotwell set point too high.ACS transmitter fault.Condensate pumps may have tripped

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LOSS OF VACUUM

Steam ejector not properly functioning.High level in condenserLOSS OF CIRCULATING WATER PUMPAir leak into systemCondenser tube chokingCW inlet water temp hi.

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BOILER FEED PUMP

BFP RE-CIRCULATION VALVE FAILS CLOSED.BFP LOSS OF LUB. OIL PRESSUREBFP BEARING VIBRATION HIGHBFP HYDRAULIC COUPLING OUTLET OIL TEMPERATURE IS GOING HIGH.BFP SUCTION PRESSURE IS FALLING LOW.BOILER FEED PUMP MASTER SPEED CONTROLLER FAILS HIGH.

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GENERATOR*PMI Revision 00 *

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Generator emergencies

Stator Water Flow LowStator Water Conductivity HighHydrogen Pressure Low/Hydrogen leakageHydrogen Purity LowSeal Oil Differential pr lowLiquid in GeneratorGenerator Stator Cooling Water LeakageDamper Tank Level LowRotor Temperature HighStator Winding Temperature HighLoss of ExcitationGenerator Transformer Cooling System TroubleGenerator Rotor Earth Fault.

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GRID FAILURE1.DC lighting ON ( Torch light must be available at least in night shift).2. Ensure starting of emergency DC drives: -Gen Seal Oil pump. -LOP of main TG -Scanner air fan. Then monitor battery voltage and current.3. Ensure starting of air motors of APHs.4. Open vacuum breaker manually.Close MOT oil centrifuge supply vv.Close SB isolation vv.Close gland steam supply vv.

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GRID FAILURE5.Ensure starting of DG set ,charging of EMCC and then changing over of emergency drives.

6.Open the incomer breakers of switch gears and transformers (motor breakers tripped on no voltage ).

7.After normalization of EMCC TVDC,BVDC AND BDDC power supply will restore. So care must be taken so that condenser/FT etc. will not

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MISCELLANEOUS SYSTEMS

LOSS OF STATION AIR PRESSURE.LOSS OF INSTRUMENT AIR PRESSURE.BOILER WATER SILICA HIGH.ELECTRICAL TRIPPING OF SUPPLY TO THE BOARD.

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THANK YOU*PMI Revision 00 *

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