Power Point Presentation 40

8/3/2019 Power Point Presentation 40

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POWER PLANTEMERGENECIES

Manoj Barsaiyan


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BOILER


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HIGH FURNACE PRESSURE

One I.D. Fan tripped or Mal-operation

of 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. orflue gas path manhole opened.

Water wall tube rupture/leakage.


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ID FAN LUB. OIL PRESSURE /

BEARING TEMP TROUBLE Lub. oil pressure may be inadequate.

Lub. oil filters may be choked.

Greasing long overdue in fanbearings.

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 millsor choking of mill/raw coal Feederpipe.


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FD FAN TRIPPED

Motor over-loaded

Lub oil pressure trouble.

Bearing temperature trouble. ID fan has tripped.

FD lub. Oil pressure low.


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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 BEARINGTEMPERATURE VERY HIGH.

AIR PRE-HEATER ELECTRIC MOTORTRIPPED.

APH ELECTRIC DRIVE TRIPPED ANDAIR MOTOR FAILS TO START.

AIR PRE-HEATER ON FIRE.


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DRUM LEVEL LOW

Mal-operation of Feed Auto Control or Feed Regulatoror scoop auto.

Tripping of one of working feed pump (standby pumpdoes not start)

Sudden increase of load.

Sudden increase in firing rate, e.g.

starting of mills having sufficient coal left beforeprevious 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 ANELEVATION

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 beingused

Sudden decrease of mill feeder speeds to minimum. Too low or too high windbox pressure causing

unstable combustion.

Water wall tube failure

Malfunction 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 airfailure to power cylinders.


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ONE FEEDER TRIPS

Support energy is removed within 3minutes of feeder starting.

No coal flow alarm comes & lowcurrent 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 closed

Loss 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 MILL TUBE LEAKAGE

Starved water walls due to very low drumlevel.

Sustained flame impingement on water wall

tubes. Blocked tube, scaling of tube, resulting inoverheating of tube metal, pitting,corrosion of tubes.

Soot blower steam impingement (wet

steam impingement or direct impingementof steam). Circulation affected due to opening of low

point drains.


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REHEATER/SUPFRHEATER/ECONOMISER TUBE FAILURE

Sustained high metal temperatures due towaterwall Slagging or forcing boiler at thetime 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 System Continuous watch on ash build up

Reduce load

Stopping of unit


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TURBINE


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TURBINE EMERGENCIES SUDDEN LOAD THROW OFF

SUDDEN INCREASE OF LOAD FROM FULL LOAD

VIBRATION HIGH

TURBINE OVER SPEED

MOT LEVEL LOW

TURBINE BEARING OIL PRESS LOW

BEARING OIL INLET TEMP. HIGH

DIFFERENTIAL EXPANSION HI/LOW

AXIAL SHIFT HIGH LOSS OF VACUUM

LOSS OF BARRING GEAR OR BARRING GEARFAILS TO START


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HOTWELL LEVEL LOW

Excessive flow to D/A from Hotwell

Some 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 valve

Malfunctioning of DM make up valve.

Condenser tube leakage Too 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 properlyfunctioning.

High level in condenser LOSS OF CIRCULATING WATER PUMP

Air leak into system

Condenser tube choking CW inlet water temp hi.


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BOILER FEED PUMP

BFP RE-CIRCULATION VALVE FAILSCLOSED.

BFP LOSS OF LUB. OIL PRESSURE

BFP BEARING VIBRATION HIGH

BFP HYDRAULIC COUPLING OUTLET OILTEMPERATURE IS GOING HIGH.

BFP SUCTION PRESSURE IS FALLING LOW. BOILER FEED PUMP MASTER SPEED

CONTROLLER FAILS HIGH.


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GENERATOR


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Generator emergencies

Stator Water Flow Low Stator Water Conductivity High Hydrogen Pressure Low/Hydrogen leakage Hydrogen Purity Low

Seal Oil Differential pr low Liquid in Generator Generator Stator Cooling Water Leakage Damper Tank Level Low Rotor Temperature High

Stator Winding Temperature High Loss of Excitation Generator Transformer Cooling System Trouble Generator 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 ofair 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 ofDG set ,charging of

EMCC and then changing over ofemergency drives.

6.Open the incomer breakers of switchgears and transformers (motorbreakers tripped on no voltage ).

7.After normalization of EMCC TVDC,BVDCAND BDDC power supply will restore.So care must be taken so thatcondenser/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 TOTHE BOARD.


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THANK YOU

Power Point Presentation 40

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