PROJECT:FAMILIARIZATION OF POWER PLANT ALONG WITH ITS VARIOUS ASPECTS

Under the guidance of Mrs. Santosh Sahran AEE/C&I-I

Submitted by:Eesha GuptaECE-505-2K9

HPGCL (Haryana Power Generation Corporation Limited) was incorporated

as company on March 17, 1997 and was given the responsibility of operating and maintenance of State's own generating projects. One of them is Rajiv Gandhi Thermal Power Plant (RGTPP), Khedar.

It was commissioned on August 24, 2010.

It has two units each with a generating power of 600 MW. This means that total generation of the plant per day is 1200

MW.

HOW DOES ELECTRICITY REACH THE CUSTOMER

At present 60% of total electricity production in India is from Coal Based Thermal Power Station. A coal based thermal power plant

converts the chemical energy of the coal into electrical energy. This is achieved by raising the steam in the boilers, expanding it through

the turbine and coupling the turbines to the generators which converts mechanical energy into

electrical energy.

WHY COAL ?

•Abundantly available• Low cost

• Technology for generation well developed

• Easy to mine, transport and store

• Economically possible to set up coal based plants

• Produces high energy upon combustion

MAJOR

COAL MINES IN

INDIA

But there are certain disadvantages related to coal

• Non-renewable and fast depleting• Lowest energy density per unit volume,

meaning that the amount of energy generated per cubic meter is lower than any

other fossil fuel• High coal transportation costs due to the

bulk of coal• Produces large number of pollutants

• Coal dust is an extreme explosion hazard, so transportation and storage must take special

precautions to mitigate this danger

Coal

Chemical Energy

Super Heated Steam

Pollutants

Thermal Energy

Turbine Torque

Heat Loss In Condenser

Kinetic Energy

Electrical Energy

Alternating current in Stator

Mech. Energy LossASH

Heat

Loss

Elec. Energy Loss

COAL TO ELECTRICITY……..

BASIC OPERATION

BASIC OPERATION• The coal is brought and crushed to powder. This

is feed to furnace for producing heat• In Boiler drum the water is converted to steam.• In Super heater the moisture content is removed

from the steam and that steam is called super heated steam

• The superheated steam rotates the shaft of the High pressure turbine

• The Exhausted steam is sent to reheater and the steam then rotates the Intermediate pressure(IP)

Turbine•The steam from the IP turbine is then feed to low

pressure turbine.• The turbine shaft is connected to the Generator,

which produces Electric Power.• The power generated is then Transmitted.

RANKINE CYCLE – THE WORKING PRINCIPLE OF THERMAL POWER PLANTS ALL OVER THE WORLD

Starting at 1, the water at room temperature is boiled at constant

temperature in the boiler. This process has a T constant for it is the boiling of water which takes at a constant temperature.

Here we are increasing the entropy of by phase change. The end product is steam.

The steam must be  heated to higher temperatures. This phase is called super

heater and this phase is mainly executed in ‘super heater’. The source of heat for the

super heater is the hot flue gases obtained in the boiler after burning coal. This

explains the phase 2-3 in the T-S curve. in the next process, the super heated steam is

allowed to expand in the turbine. As, the high pressure steam is allowed through a

small nozzle ,steam acquires kinetic energy.

This kinetic energy of the steam will exert required force on the turbine blades. This

process is a constant entropy process. Now the output of the turbine is low pressure

and low temperature steam. This accounts for the phase 3-4 of the cycle. Now steam is changed to hot water in condenser without any temperature change. This accounts for the phase 4-5 of the cycle. The step 5-6 is a

pump which is used to circulate water. During this process, a little temperature

change can be observed. Finally, the cooled water cannot be directly sent into boiler.

Hence, the water should be heated to higher temperature. This is done in economizer

which uses heat from flue gases. Thus this accounts for the 6-1 phase of the Rankine

cycle.

SIMPLIFIED DIAGRAM

1. Cooling tower2. Cooling water pump

3. Transmission line4. Step-up transformer5. Electrical generator

6. Low pressure steam turbine7. Condensate pump8. Surface condenser

9. Intermediate pressure steam turbine

10. Steam Control valve11. High pressure steam turbine

12. Deareator13. Feed heater/heater

14. Coal conveyor15. Coal hopper

16. Coal pulverizer17. Boiler steam drum

19. Superheater20. Forced draught (draft)

fan21. Reheater

22. Combustion air intake23. Economiser

24. Air preheater25. Precipitator

26. Induced draught (draft) fan

27. Flue gas stack

COMPONENTS

COAL HANDLING SYSTEM

It contains many components:

• Coal wagon• Wagon tippler• coal hopper• crusher

• magnetic separator• dryer

• coal mill• pulveriser• storage

Coal hopper

Coal mills

Coal bunker

Back to slide no. 43

BOILER

A Boiler or steam generator essentially is a container into which water can be fed and steam can be taken out at desired pressure (172-180 kg), temperature (540°C) and flow. This calls for application of heat on the container. For that the boiler should have a facility to burn a fuel and release the heat. The functions of a boiler thus can be stated as:-• To convert chemical energy of the fuel into heat energy• To transfer this heat energy to water for evaporation as well to steam for superheating.

• Light diesel oil (LDO)• Heavy fuel oil (HFO)

Light diesel oil is fuel of intermediate viscosity. Preheating may be necessary in some equipment for burning and, in colder climates, for handling. It is also costly. Heavy fuel oil is a fuel more viscous than Light diesel oil but intended for similar purposes. Preheating is usually necessary for burning and, in colder climates, for handling. It is less costly than LDO

KINDS OF OIL USED IN FURNACE

FLAME MONITOR

FURNACE AND ITS ALLEVATION POINTS

There are five alleviation points in a furnace from where oil firing is done. Initially LDO is used at BC and FG. Thereafter HFO is

used at remaining levels.

Combustion Reactions

Carbon reaction 2C + O2 =2CO [Eco=60kJ/mol]C + O2 =CO2 [Eco2=140kJ/mol]

Reaction at 1200oC4C + 3O2 =2CO + 2CO2 (Ratio 1:1)

Reaction at 1700oC3C + 2O2 = 2CO + CO2 (Ratio 2:1)

Hydrogen reaction2H2 + O2 = 2H2O 61095 BTU/lb

Sulfur reactionS + O2 = SO2 3980 BTU/lb

(undesirable)

Super heater : The steam is super heated in order to make it

hold more energy and transfer it to the turbine. This job is accomplished by the super heater.

Super heater is showed in the boiler schematic. The flue gases coming out of the

boiler are used to super heat the steam.

Economizer : The water entering into the boiler must have a

temperature compatible with the boiler temperature. So, the heat left with the flue gases after superheater is used to heat the

water in the economizer. The economizer has convoluted tubes in which water flows and the

flue gases flow over these tubes in a closed structure.

ReheaterPower plant furnaces may have a reheater section containing tubes heated by hot flue gases outside the tubes. Exhaust steam from the high pressure turbine is rerouted to go inside the reheater tubes to

pickup more energy to go drive intermediate or lower pressure turbines.

Ash handling systemThe disposal of ash from a large capacity power station is of same

importance as ash is produced in large quantities. Ash handling is a major problem.

i) Manual handling: The ash is collected directly through barrows from the ash outlet door from the boiler into the container from

manually.

ii) Mechanical handling: Mechanical equipment is used for ash disposal, mainly bucket elevator, belt conveyer.

iii) Electrostatic precipitator: From air preheater this flue gases (mixed with ash) goes to ESP. The precipitator has plate banks (A-F)

which are insulated from each other between which the flue gases are made to pass. The dust particles are ionized and attracted by charged

electrodesBack to slide 43

TURBINES

In thermal Power Plant generally 3 turbines are used to increase the efficiency.

High Pressure Turbine(HPT): The superheated steam is directly fed to this turbine to rotate it.

Intermediate Pressure Turbine(IPT): The out put from the HPT is reheated in a reheater(RH) and used to rotate IPT .

Low Pressure Turbine(LPT): The Exhausted steam from the IPT is directly fed to rotate the shaft of LPT.

*All the turbines are connected to a single shaft which is connected to the Generator.

GENERATORSThe Synchronous Generator is used to Generate power by

connecting the shaft of the Turbine to the shaft of the generator which cuts the magnetic flux producing mf.

The Generated Voltage will generally 11KV to 20 KV max. here 20KV

The Generated Voltage is stepped up by connecting Step up transformer (here 400KV) and is transmitted and is also used for

Auxiliary purposes.

Unit Auxiliary Transformer: This transformer is used to step down the produced voltage and use for Auxiliary purpose.

BOILER FEED PUMP

Boiler feed pump is a multi stage pump provided for pumping feed water to economiser. BFP is the biggest

auxiliary equipment after Boiler and Turbine. It consumes about 4 to 5 % of total electricity generation.

AIR PREHEATER

The heat carried out with the flue gases coming out of economiser are further utilized for preheating the air before supplying to the combustion chamber. It is a

necessary equipment for supply of hot air for drying the coal in pulverized fuel systems to facilitate grinding and

satisfactory combustion of fuel in the furnace

CONDENSOR

The condenser condenses the steam from the exhaust of the turbine into liquid to allow it to be pumped. If the condenser can be made cooler, the pressure of the exhaust steam is reduced and efficiency of the cycle increases. Below shown is surface

condensor which is used in RGTPP, Khedar

COOLING TOWER

The cooling tower is a semi-enclosed device for evaporative cooling of water by contact with air. The hot water coming out

from the condenser is fed to the tower on the top and allowed to tickle in form of thin sheets or drops. The air flows from bottom of the tower or perpendicular to the direction of water flow and

then exhausts to the atmosphere after effective cooling.

COOLING TOWER

DEAERATORIt is used to remove air which is entrapped in the water

molecules. It is very important part because the entrapped air affects boiler drum badly and leads to

corrosion.

DEAERATOR

Principle behind deareation: gas solubility decreases as temperature rises till saturation temperature is

achieved. Therefore when steam interacts with water it rises the temperature of water till saturation

temperature.

There are total three pumps attached to Deareator. They are Motor Driven Boiler Feed Pump (MDBFP) on standby and two TDBFP (Turbine Driven Boiler Feed

Pump). MDBFP is costly and uses electricity for its operation. Therefore it is used in the starting only. TDBFP is very economical and is turbine driven. Tappings are taken from HP turbines and LP turbines. Steam from those

tappings is used to drive TDBFP.

FEED HEATER

Two types of feed heater are there:High pressure heaterLow pressure heater

H P Heater is installed after Boiler feed pump and it heats the feed water by exchanging heat with the steam that is extracted from

the H.P. Turbine from different stages at different pressure.

L P heater is installed after condensate extraction pump and in the same way it heats the water but it takes the steam

extraction from the L.P. turbine.

Atmospheric air from PA fan is mixed with coal and fed in

the furnace. FD fan supports combustion

ID fan is the outlet or exhaust. Already present air

in furnace is sucked by ID fan and thrown out.

FANS

Three kinds of fans are there:• Primary air fan• Forced draft fan• Induced draft fan

PRIMARY AIR FAN CYCLE

Cool air

Cool air

FORCED DRAFT FAN

INDUCED DRAFT FAN

MAJOR EVENTS OF PLANT:

• Coal flow• Water flow• Steam flow• Ash handling

WATER FLOW

STEAM FLOW

SWAS DEPARTMENT(Steam and Water Analysis System)

Different samples of water and steam are taken for testing its various aspects.

• Silica analyzers• Phosphate analyzers• Chloride analyzers• Hydrazine analyzers• Sodium analyzers• Cation conductivity• Specific conductivity• Ph transmitters

• Dissolved oxygen transmitters

There are ten HIS (Human Interface Station) in each unit. These HIS are:• Engineering station (one)

• Historians (two)• SOE – Sequence of Events (one)• Performance calculation (one)• Operation systems (five)

 In addition to HIS, we have twenty three FCS

(Field Control Station) in each unit. 

DCS SYSTEM

The termination pannel contains electronic cards which are responsible for every type of

communication process.

• AI card (analog input)• AO card (analog output)• DI card (digital input)• DO card (digital output)

MEASUREMENTS TAKEN IN POWER PLANT

• Temperature• Pressure• Level

• Analysis of water, steam and flue gases• Others

TEMPERATURE MEASUREMENTS:

•Steam at superheater inlet and outlet•Feed water at economizer inlet•Air preheater•Reheater outlet•Furnace•Coal mill inlet and outlet•P A fan, I D fan•L P, H P heaters

PRESSURE MEASUREMENTS:

•Boiler•Furnace•Coal mill•Furnace•Boiler drum

STEAM MEASUREMENTS:

•Reheated steam at outlet of reheater (LHS)•Reheated steam at outlet of reheater (RHS)•Saturated steam (RHS)•Saturated steam (LHS)•Super heated steam (RHS)•Super heated steam (LHS)

WATER MEASUREMENTS:

•Feed water at economizer inlet•Boiler water (left side)•DM water•HP heater drain•LP heater drain•Electric generator cooling water•Deareator