Fire Fighting Systems in Power Stations

7/27/2019 Fire Fighting Systems in Power Stations

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FIRE FIGHTINGSYSTEMS IN POWER

STATIONS



6

Why, Where and How in a

Power Station

Basics of Combustion Process

Fire Tetrahedron

Oxygen

Fuel Heat of Ignition

Chain Reaction to Sustain Fire



7

Sources Of Ignition

Electricity

Smoking

Incendiarism (strike, sabotage)

Cutting & Welding

Friction



8

Classification of Occupancies by TAC

Light Hazard

Ordinary Hazard

High Hazard Electric

Generating

Station



9

Major Fires in Fire Stations

Obra Thermal Power Station

Koradi Thermal Power Station

HVDC Transmission System of Rihand Dadri

Line.



10

Resources of Designer

CODES- National Fire Protection Association(NFPA), Tariff Advisory Committee (TAC), Beuro OfIndian Standards (BIS).

Insurance Agency

Feed Back From Operating Stn. Latest Development in the Field.

Inert Gas System

Addressable Detection System

Multisensor Detectors



11

Fire Risk Areas

Fuel Oil Storage & Handling System.

Coal Storage And Handling System

Cable Galleries

Steam Generator /WHRB

Transformers



12

Fire Risk Areas- contd.

Lub Oil System

Generators

Control Room & CER

Air Pre-heaters

Gas Turbines

Gas Pressure Reducing Station



13

Type Of Detectors

Heat Detectors

Smoke Detectors

Flame Detectors



14

Heat Detectors +/-

Heat Detectors

Advantages

Simplest

Least Expensive Reliable

Lowest False Alarm Rate

Disadvantages

Slowest to Respond



15

Heat Detectors in Power Station

Typical Heat Detectors are:

Quartzoid Bulb Detector

Spot Type Heat Detector

Linear Heat Sensing Cables

Infrared Heat Detector



16

LHSC & Infra-red detectors

LHSC – Heat sensing cable comprises of

two conductors encased in heat sensitive

material Infra-red – Detects moving fires

Responds to “Infra-Red Band” of

Electromagnetic radiation

- Provided on conveyors coming from coal

stockyard

- going to coal bunkers.



17

Use Of Heat Detectors

Used For Detection Of Fires In

Transformers

Coal Handling Plant

Fuel Oil Storage And Handling Plants

Boiler Burner Fronts

Lub Oil Storage Facilities

Battery Rooms



18

Smoke Detectors +/-_

Smoke Detectors

Advantages

Fast Detection

Disadvantages More Costly

Require More Maintenance

Higher False Alarm Rate



19

Other Details of Smoke Detectors

Types Are

Ionisation

Photoelectric

Multisensor

Used In

Control Rooms

Control Equipment Rooms

Office Areas

MCC/Switch Gears Rooms

Cable Galleries



20

Smoke Detectors

Ionisation type Smoke Detector is more

snsitive as compared to Photoelectric type

Detector.



21

Smoke Detectors

Ionisation type Detector

It is Responsive to both Visible and

Invisible products of Combustion with

very early response to Fires in theIncipient Stage

It can Detect Smoke Particles in the 0.01

to 10 Microne range .



22

Ionization Detectors

Detector consists of ionizing chamber with

radio-active source

Smoke/Fire changes current in the ionization

chamber Used for general office application

To avoid the use of radioactive element, these

detectors have now been replaced with Multi-Sensor type detectors.



23

Smoke Detectors

Optical/ Photoelectric

It is responsive to visible smoke

It can detect smoke particles in the

range of 0.5 to 10 microne

It is useful where an ionisation sensor is

too sensitive



24

Photo-electric detector

Sensing element is an optical chamber

On fire/smoke, the light scattered in the

optical chamber varies Smolder fires (Suitable for PVC fire)



25

History of smoke detection

Early version of smoke detector 1896

• Involved two birds in a cage

• When overcome by fumes, would fall into a funnel atthe bottom of their cage.

• The weight of their bodies would activate a circuit and

register an alarm.• Two birds were used so that in the event one died of

natural cause; the detector would not be triggered.

• This was the earliest form of false alarm protection



26

The cross-zoning principle was designed to

avoid pouring expensive extinguishing

chemicals into the room in a false fire scenario.



28

Addressable Analog Detection

System-1

Microprocessor based

Smart & intelligent

Any kind of Detector or Alarm may be

incorporated

Detectors are monitored every 3 seconds

including their status, sensitivity etc.



29

Addressable Analog Detection

System-2

Based on above programmed action can be

taken by panel e.g.

Transmit Alarm

Closing Doors Suppression System

Printing records

Can Analyse & Adjust Sensitivity of Detector



30

Components of Fire Alarm System

Detection

Protection

Annunciation Central Fire Control Panel



31

Fire Protection

Agents

Should be most effective

Safest

Least damaging to particular operation orequipment

Pre-Planned

Equipment in Place



32

Classification of Fires

Class-A

ORDINARY COMBUSTIBLES e.G. Wood,

Paper, Cloth& Plastics

Requires Cooling & Quenching Class-B

Flammable liquid e.g. Gasoline, Oil, Paints

Etc.

Requires Blanketing,Smothering Or Chemical

Inhibition.



33

Classification of fires-contd.

Class - C

Electrical fires

Requires non conducting extinguishing agent

with cooling, smothering or chemical inhibitioncharacteristics



34

Classification of Fires-contd

Class - D

Combustible Metal Fires e.g. Mg., Al, Na, K

ETC.

Requires special Dry Powder which Blanketsthe Fire and Exclude the Oxygen.



35

Common Extinguishing Agents

Water

Oldest

Most Common

Abundant

In-expensive

Readily Available

Excellent Fire Extinguishing Properties



36

Common Extinguishing Agents-contd.

Easily Transported or Moved.

Has Sufficient Surface Tension to allow it to

applied as a

Consolidated Stream Discrete Water Droplets

Fog or Spray



37

Automatic Sprinklers & Electrical Fires

Characteristics of water spray pattern

Little danger of the transmission of hazardous

current

Unlikely that personnel will be in the waterdischarge area when sprinkler activates.



38

Design aspects

Hydrant works as the back bone

Spray/sprinkler system provided for automatic

protection of transformers, coal handling plant,

cable galleries, fuel oil and transfer areas.

Foam protection system for fuel oil tanks,

Total flooding inert gas system for electronic

areas.



39

TO SPRAYSYSTEM

TO HYDRANT

SYSTEM

FIRE WATER

STORAGE TANKS

JP

HP-

MD

SP-

DD

SP-

MD

HP-

MD

HP-

DD

JP- JOCKEY PUMP

HP- HYDRANT PUMP.

SP- SPRAY PUMP

MD- MOTOR DRIVEN.

DD- DIESEL ENGINE

DRIVEN



46

MVW SPRAY SYSTEM

Provided to protect

Cable galleries/cable vault of

Main plant

ESP/ VFD building CHP control room

Switchyard control room

Cable galleries provided in any other area



47

MVW SPRAY SYSTEM-Contd.

Coal conveyors

Transfer points and crusher houses

Fuel oil tanks (NAPHTHA/NGL/HSD)

Fuel oil pump house eqpts. Steam turbine bearing housing



48

HVW SPRAY SYSTEM

Turbine oil tanks,coolers and purifiers

Turbine lube oil pipes

Boiler burner fronts

All transformers in transformer yard andtransformers of 10MVA and above in other

areas in the plant.

Oil canals



49

General comments

Hydrant system is kept pressurised using Hydro-pneumatic tank, air compressors and jockey pumps.

Hydro-pneumatic tank works as a surge tank.

Air compressor helps in maintaining adequate pressure inthe system.

Jockey pump helps in meeting minor losses. Above system would work, if hydrant system is not used

for any other purpose.

It is observed that at site hydrant system is used forcleaning and floor washing.



50

Such a practice is very dangerous

May result in inadequate pressure at place offire in emergency situation.

To overcome this problem Independent service water system with pumps

and piping network is being provided.

Jockey pump of higher capacity is beingprovided. ( earlier it was 20 to 30 Cum./Hr.now it is about 75 Cum./hr.)



52

FIRE PROTECTION OFCONTROL ROOMS AND

CONTROL EQUIPMENTROOMS



53

BACKGROUND

-Devastating fire at OBRA TPS IN OCTOBER1983

-C.E.A. Circulated the measures to be adopted

in fire fighting system in power stations.

-Recommendations-use Halon-1301 in control

room areas by total flooding system.



54

BASIC REQUIREMENT

•These are electronic areas

• Agent requirements•High efficiency

•Non-toxic

•Non-damaging to equipment

•Non-conductor of electricity



55

INTRODUCTION IN NTPC

HALON 1301- Meet all the above

Used as a total flooding agent

OBRA FIRE IN 1983

Cause for introduction of agent in NTPC



56

-HALON-1301, an excellent fire extinguishing

agent,

- For total flooding application

- Safe for use in manned areas

- Harmless to equipment.

-Accordingly, HALON-1301 gas was introduced in

NTPC For protection of CONTROL EQUIPMENT

ROOM (C.E.R.) and UNIT CONTRL ROOM (U.C.R.)

in 1984.

Subsequently all NTPC Projects at that time were

provided with HALON-1301.



57

ENVIRONMENTAL IMPACT

In 1991 due to adverse environmental impact

- further use of HALON was discontinued.



58

HALON PHASE OUT

• In view of environmental considerations, itsuse was reviwed in NTPC in 1991 and it was

decided not to specify HALON System for

ongoing and future projects.

• Accordingly, only portable extingushers

were provided for control room and modular

CO2 Injection system was to be explored for

individual panels in CONTROL EQUIPMENTROOM (C.E.R.)



59

• CO2 Injection system was not found suitable

because of objection raised by panel

manufacturers.

• Hence this system has not been provided in any

NTPC Projects for U.C.R. AND C.E.R.



65

The issue of fire protection system in

control rooms and control equipmentrooms was once again reviewed in NTPC

in 1999



70

National Fire Protection Association (NFPA)

USA has published a code NFPA-2001.

This code covers clean agent fireextinguishing system as an alternative to

HALON.

CLEAN AGENTS NOW AVAILABLE



71

NFPA-2001

NFPA-2001,1996 MADE AVAILABLE FOR

CLEAN AGENT SYSTEMS

HALOCARBONS INERT GASES

CLEAN AGENTS



72

COMPARISON OF CLEAN AGENTS

HALOCARBONS

Physical charact-eristics

CHEMICAL

SPEED OF EXTING-

UISHING Fast since total

agent discharge is in

10 sec.

INERT GAS Physical charact-eristics

INERT GAS

SPEED OF EXTING-UISHING

Relatively slower

since total gas

discharge time is

about 60 sec.



73


HALOCARBONS

Design concen-tration

to extinguish fire

7%

INERT GAS

Concentration required

to extinguish fire

34%



74


HALOCARBONS

CYLINDER STORAGE

4 TIMES MORE THAN

HALON

CYLINDER

PRESSURE

25 TO 40 BAR

INERT GAS

CYLINDER STORAGE

10 TIMES MORE

THAN HALON

CYLINDER

PRESSURE

150 TO 300 BAR



75


HALOCARBONS

GAS DISCHARGE

PRESSURE

5 BAR

VENTING DESIGN

NOT SIGNIFICANT

INERT GAS

GAS DISCHARGE

PRESSURE

25 BAR SPECIAL CARE IS TO BE

TAKEN IN ENCLOSURE

DESIGN WITH RESPECT

TO VENTING



76


HALOCARBONS

Location of cylinder:

should not be more

than 20m away from

the risk

INERT GAS

Can be loacted 150m

away from the risk



77


HALOCARBONS

No. of cylinder banks -

each bank can

serve only one fire risk

Refill cost very high

INERT GAS

One bank can serve a

number of fire risks

using directional valve

Refill cost cheap



78


HALOCARBONS

Undergoes thermal and

chemical decomposition

while extinguishing fire

INERT GAS

Not subject to any

decomposition.



83

Halocarbon is a chemical agent. Hence,

possibility of its use being banned orrestricted in future can not be ruled out .



84

INERT GASES

Normal level of oxygen -21% in atmosphere

To extinguish fire oxygen concentration should be less

than 15%

Oxygen concentration less than 12% is not safe for

human occupancy.

Inert gas reduces oxygen concentration ( to less than

15% but more than 12% and extinguish fire.



88

HALOCARBONS-1

FM-200 - GREATLAKE CHEMICALS, USA

NAF-SIII- NORTH AMERICAN FIRE

GUARDIAN , CANADA, ITALY

FE-13 - Du PONT

CEA-410



91

INERT GASES-1

INERGEN(N2-52%, ARGON -40%, CO2-8%)

ARGONITE (N2-50%, ARGON -50%)

ARGOTEC ( ARGON -100%)

NITROGEN (N2-100%)



92

INERT GASES-1

These are mixture of freely available gases in

atmosphere

System design is proprietary

Refilling is cheaper Requires more cylinders

Directional valves can be used.



94

INERT GASES-3

INERGEN - AVAILABLE FROM TYCO USA,

ANSUL USA, WORMOLD AUSTRALIA.

ARGONITE - GINGE-KERR, DENMARK.

ARGOTEC - MINIMAX, GERMANY NITROGEN - NOHMI BOSAI, JAPAN



97

MONTREAL PROTOCOL

For India - eliminate HALON Consumption

completely by developing safer alternatives

by 2010.



100

TH NK YOU



101



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Fire Fighting Systems in Power Stations