Syed Hassnat Alamgir. Assignment 4

8/3/2019 Syed Hassnat Alamgir. Assignment 4

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SYED HASSNAT ALAMGIRL11F11BSEE0077

BASIC MECHANICAL ENGINEERING

Assignment No. 4

Title: Gas Power Plant & Steam Power Plant

Contents:

1) Introduction of Gas Power Plant

2) Working of Gas Power Plant

3) Major Components of Gas Power Plant

4) Working Cycle & Its P-V & S-T Diagram of Gas Power Plant

5) Gas Power Plant in Pakistan

6) Introduction of Steam Power Plant

7) Working of Steam Power Plant

8) Major Components of Steam Power Plant

9) Working Cycle & Its P-V & S-T Diagram of Steam Power Plant

10)Steam Power Plant in Pakistan


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INTRODUCTION TO GAS POWER PLANT:

A Gas power station is a power station thatburns fuels such as coal, fossil fuels or petroleum (oil) to produceelectricity. Central station gas power plants are designed on a large scalefor continuous operation. In many countries, such plants provide most ofthe electrical energy used.

Gas power stations have some kind of rotating machinery to convert theheat energy of combustion into mechanical energy, which then operatean electrical generator. The prime mover may be a steam turbine, a gasturbine. All plants use the drop between the high pressure andtemperature of the steam or combusting fuel and the lower pressure ofthe atmosphere or condensing vapour in the steam turbine.

400 MW Power Plant GUDDU, DISTT. JACOBABAD Client: WAPDA


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Working of Gas Power Plant:

Gas turbine functions in the same way as the InternalCombustion engine. It sucks in air from the atmosphere, compresses it. The fuel is injected andignited. The gases expand doing work and finally exhausts outside. The only difference is insteadof the reciprocating motion, gas turbine uses a rotary motion throughout.

The three main sections of the Gas Turbine are:

1. Compressor.

The compressor sucks in air form the atmosphere and compresses it topressures in the range of 15 to 20 bar. The compressor consists of anumber of rows of blades mounted on a shaft. This is something like aseries of fans placed one after the other. The pressurized air from thefirst row is further pressurised in the second row and so on. Stationaryvanes between each of the blade rows guide the air flow from onesection to the next section. The shaft is connected and rotates along withthe main gas turbine.


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2. Combustor.

This is an annular chamber where the fuel burns and is similar to thefurnace in a boiler. The air from the compressor is the Combustion air.Burners arranged circumferentially on the annular chamber control thefuel entry to the chamber. The hot gases in the range of 1400 to 1500 C

leave the chamber with high energy levels. The chamber and thesubsequent sections are made of special alloys and designs that canwithstand this high temperature

3. Turbine:

The turbine does the main work of energy conversion. The

turbine portion also consists of rows of blades fixed to the shaft.Stationary guide vanes direct the gases to the next set of blades. Thekinetic energy of the hot gases impacting on the blades rotates the bladesand the shaft. The blades and vanes are made of special alloys and


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designs that can withstand the very high temperature gas. The exhaustgases then exit to exhaust system through the diffuser. The gastemperature leaving the Turbine is in the range of 500 to 550 C.

The gas turbine shaft connects to the generator to produce electricpower. This is similar to generators used in conventional thermal power

plants.


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Major Components of Gas Power Plant:

GAS COMPRESSOR

COMBUSTOR CHAMBER


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GAS TURINE

Working Cycle & Its P-V & S-T Diagram of Gas Power:

WORKING CYCLE


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PV and ST diagram

Gas Power Plant in Pakistan:

BIN QASIM GAS POWER

PLANT


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Introduction of Steam Power Plant:

Thermal Power Plants

contribute maximum to the generation of Power for any country.

Thermal Power Plants constitute 75.43% of the total installed

captive and non-captive power generation in India. In thermal

generating stations coal, oil, natural gas, etc are employed as

primary sources of energy.

Working of Steam Power Plant:

1. Energy Source: Coal, Natural Gas, Diesel, Oil are the major sources of primary energy.Coal fired thermal plants form 55.23% of total installed capacity. They formed almost 83% ofinstalled thermal power generation. The prices of the fuel determines the economics of thermalpower plants.

2. Boiler and Furnace: The fuel is burnt in the furnace to produce steam in the boiler.Pulverized coal is burnt to produce steam. Water from the feed pump, after pre-heating enters theboiler. This water may be obtained from a nearby river or lake. The condensed water from thecooling tower is re-used.

To increase the efficiency of the plant steam is generated at highest possible temperature andpressure. To further increase the efficiency steam is re-heated after it is partially expanded by anexternal heater.

3. Prime Movers: These depend on the fuel used. Coal fired plants use Steam Turbines. Gasfired use Gas Turbine Engines, which are similar to Turbo-Prop engines used in airplanes. Diesel

fired use IC engines.

In case of coal fired plants steam produced in the boiler is passed through an axial flowturbine. The turbine is coupled to the generator and thus energy conversion is achieved. Gas firedare usually operated in combined cycle mode to attain maximum efficiency. In these types in the1st stage gas turbine engines are coupled to the generators.

In 2nd stage the hot gases exhausted from the gas turbines are passed through heatexchangers to generate steam which drives the conventional steam turbine. Alternatively heatfrom the exchanger can be used for industrial purposes.

4. Generators: The prime movers are coupled to the generators to convert mechanical energy

into electrical energy. Modern practice is to design and build generating units having large MWgenerating capacity since their capital cost per kW decreases as the MW capacity is increased.

Increasing the unit capacity from 100MW to 250MW results in saving of about 15% in theircapital cost per kW. Moreover units of this magnitude result in fuel saving of almost 8% perkWh. The cost of installation is also low for such units.


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Presently the max capacity of turbo-generator sets being produced is nearly 1200 MW. InIndia, super thermal power units of capacity 500 MW are being commissioned by BHEL. Alsomany Ultra-Mega Power Plants are being sanctioned to achieve the government s goal of energyfor all.

5. Condenser and Cooling Tower: The steam after passed through the turbines is condensedin a condenser. The water is then supplied to the cooling tower where it is cooled. The water isthen fed to the feeder pump from where it is given to the boilers.

6. Precipitators and Chimneys: The waste gases from the boiler are first passed throughprecipitators to separate the solid dust particles. The fly ash is collected at these precipitators.The gases are then thrown out with the use of Chimneys.

7. Control Room and Switchyard: The control room monitors the overall operation of the

plant. It is provided with controls for real and reactive power flow. It is provided with safety

relays and switchgears.

Major Components of Steam Power Plant:

Steam Turbine


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Boiler for Steam Power Plant

Boiler and condenser of steam power plant


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Working Cycle & Its P-V & S-T Diagram of

Steam:

WORKING CYCLE


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PV AND ST DIAGRAM

Steam Power Plant in Pakistan :


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300 MW Thermal Power Plant, Guddu Thermal Power Plant, WAPDA Power

Plant

Syed Hassnat Alamgir. Assignment 4

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