power plant emergenecies

7/29/2019 Power Plant Emergenecies

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26 February 2013 PMI Revision 00 1

POWER PLANT

EMERGENECIES

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Presentation outline

Boiler Emergencies

Turbine Emergencies

Generator Emergencies

Grid Failure


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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. or flue 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 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-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 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 drumdrain Valve

Inadvertant opening of low point drain valves or Emergency drum drainvalve.


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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 onlyoil is being used

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 airfailure,

slag or soot on scanner lenses etc.

Burner tilt mechanism negative extreme due to air failure to powercylinders.


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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 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 drum level.

Sustained flame impingement on water wall tubes.

Blocked tube, scaling of tube, resulting in overheating oftube metal, pitting, corrosion of tubes.

Soot blower steam impingement (wet steam impingement ordirect impingement of steam).

Circulation affected due to opening of low point drains.


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REHEATER/SUPFRHEATER/

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 incoal 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 AshingSystem

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 GEAR FAILS 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 properly functioning.

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 FAILS CLOSED.

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 motorsof 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 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 BDDCpower supply will restore. So care must be taken sothat 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

power plant emergenecies

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