Emergency management in.ppt

7/28/2019 Emergency management in.ppt

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Emergency management in

Thermal Power PlantsOperational Emergencies

Preventive & Corrective Actions


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In preparing for battle I have

always found that plans are

useless

..but planning is indispensable.

Dwight T Eisenhower

The thirty-fourth President of

the United States (1953-1961).


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Happening other than normal

Or which are not easily controlled automatically

Hence, calls for human interference

It can cause

Loss of generation

Property

Life

Immediate corrective action reduces the extent of

damage

What is an emergency?


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Types Of Emergency

Accidents

Fires

Equipment failures

Operation related emergencies

Disasters


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Any abnormal situation may lead to :

Equipment damage or Failure

Unit Outage

Station Outage

And affecting significantly Safety to Human beings and Equipment

Forced Outage (Down time) / Partial loading

Efficiency

O & M cost

Impact


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Need to face emergencies in PowerPlant can not be over emphasized:It has direct bearing on:

1) Safety of man & machine.2) Bottom line of Company,

specially in ABT regime.


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Emergency situation can arise due tosituations external or internal to theplant:

Grid disturbances have often led tototal station shut down an example ofcause external to the Plant.

Failure of equipments, systemdeficiencies or significant deviation inprocess parameters are at the root ofemergencies.


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Emergencies covered in disaster management planis not covered in scope of deliberation.

Areas where emergency situation does arise are,broadly speaking:

1) Steam Generator.

2) Turbo-generator.

3) Switchyard

4) Common systems:a) CWb) RWc) CLWd) Compressed Aire) Ash Handling etc.


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FACTS.. Most of the emergencies if handled ably

and judiciously, can mitigate and in

some cases can prevent the adverseimpact.

With advancements in C & I, goodprotection systems are in place for theautomatic handling of emergencies,never the less the role of operating

personnel is the prime.


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ACCIDENTS

Accidents during: Erection stage

O & M stage

Accidents due to: Equipment failure

Human Error


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Emergency situations for Boiler:

1) Loss of Auxiliary :

a) ID, FD, PA Fans b) CC Pump

c) Multiple Mill Tripping

d) Scanner Air Fan.

e) Stalling of APH & Fire in it.

f) Abnormal drum level


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Emergency situations for Boiler (Contd):

2)Combustion Related:

a) Furnace Pressurization

b) Ash Build-up in furnace

c) Structural deficiencies.

d) Evacuation problems in ESP.


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Furnace Pressurization Causes:

Presence of un-burnt fuel. Mismatch in ID Fan & FD/PA Fan loading.

Tube leakage.

Remedial measures:

Ensuring ignition energy for fuel being put into thefurnace.

Ensuring oxidizing atmosphere in furnace allowingair/fuel lead-lag circuit to work as per logic.

Healthiness of post purge trip circuit Not altering turn-down ratio prescribed for oil &

coal burners.

Healthiness of furnace pressure control links etc.


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Slagging & Ash Build upCauses:

1) Improper fuel or air distribution in furnace

presence of high heat flux zone.2) Fouled furnace.

Remedial Measures:

1) Pockets of reducing atmosphere in furnaceto be eliminated, which reduces ashfusion temperature considerably.

2) Clean air flow test, dirty pitot tube test.

3) Coal specific fuel air damper setting.


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Emergencies in Turbine1)Loss of Auxiliary BFP, CEP, ECW, Vacuum

Pumps, Oil Pumps etc.

2) Loss of Circulating Water.3) Abnormal Process parameters.

A) High vibration

B) Abnormal Thermal expansions

C) Over speeding4) Other Emergencies:

A) Water carry over into turbine.

B) Seizure stoppage of barring.

C) Bursting of steam / water pipe linesD) Hydrogen Gas Leakage

E i G


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Emergency in Generator

1)H2 leakage.

2)Fire in Generator transformer3)Stator Water loss/partial blockage in

windings.

4)Excitation systems malfunction.


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St f B i


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Stoppage of BarringCauses:

1) Inadequate rotor lift.

2) Seizure at glands, inter-stage seals or by brokencomponents or foreign material.

Ensuring requisite lift at bearings by setting correctjacking oil pressure, jacking oil line flexible hosepunctures are common.

Mechanical seizure at seals due to very low seal steamtemp. takes place at gland portion.

Often waiting for turbine to cool down for 70-80 hoursbrings back turbine on barring.

Excessive force used for hand barring may lead to

damage to inter-stage seals or gland seals.


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UNIT DC Failure

Unit DC Failure

Loss of Emergency Drive Loss of Control and Protection

Unit DC System Architecture

Boiler Control

Electrical Protection Switchgear Control

Emergency Services

Turbine Control


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ISLANDING Station Islanded.

Disconnection from the Grid system (locally or atremote sub station)

How to recognize the situation?

Sharp and large rise / fall in frequency

How to successfully operate the island? The island may have more than one station

Generation control (preferably Governor Control)to stabilize frequency

Synchronize with the Grid / adjacent island asquickly as possible

Bl k O t t P St ti


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Black Out at Power Stations AC supply failure UPS healthy? Adds to the distress. DC supply OK? Emergency services established?(Lubes, sealing oil pumps, scanner fans) How fast you need DG supply? Not very critical, itcan wait. Urgency only if DC system has failed. Has DG started? Can you start it and connect?What is your alternative source? Turning gear working? Fire Fighting system alert? NEVER PANIC


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Si ifi t L i '


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Significant Learning'sIssues such as grounding , which do not play arole in normal running and hence accordedlesser importance can be vital to plant safety.

Critical supports such as batteries need to begiven due importance.

Environmental conditions can deteriorate thefunctioning of the otherwise proven design.

Even the most experienced Engineers cancommit mistakes. Documentation / Procedures

help.

SIGNS OF IMMINENT DANGER


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SIGNS OF IMMINENT DANGER(Electrical)

OPERATING REGIME-conditions

EQUIPMENT REGIME-history PERSISTING ALARMS

LOCKOUTS

HOT SPOTS

DC EARTH FAULT

FLASHOVERS

CABLE FIRE


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Emergency management in.ppt

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