Thermal Power Plant

Thermal Power Plant-

A thermal power plant is a power plant that converts heat energy into electricity. The most standard source of electricity is the thermal power plant or heat power station. Thermal power plant is also known as coal thermal power plant and steam turbine power plant.

Theory of Thermal Power Station-

The thermal power plant or heat power plant operation theory is very easy. A power plant consists mainly of alternators running with the help of a steam turbine. The steam is acquired from boilers with heavy pressure. Bituminous coal, brown coal and peat are generally used as boiler fuel in India. The bituminous coal is used as boiler fuel with unstable material from 8% to 33% and ash content from 5% to 16%. The coal is used in powder form in the boiler to boost thermal efficiency.

At the coal thermal power plant, Due to burning of coal (pulverized coal) in boiler furnaces, the steam is generated at high pressure in the steam boiler. This steam is heated in a superheater for an additional efficiency. This overheated steam then enters the turbine and rotates the blades of the turbine. The turbine is combined with alternator mechanically so that its rotor will rotate with turbine blade rotation. The steam pressure drops immediately after entering the turbine and the resulting steam volume rises.

The steam moves out of the turbine blades into the condenser after transmitting power to the turbine rotor. In the condenser, a pump that condenses the low-pressure wet steam is used to circulate the cold water. Furthermore, this condensed water is provided to a low-pressure water heater where the low-pressure steam raises the temperature of this feed water ; it is heated again at high pressure.

Thermal Power Plant Layout/Diagram-

Thermal Power Plant
  1. The steam has lost its strong pressure after rotating the turbine blades, passes through turbine blades and enters a condenser.
  2. With the help of a pump, the cold water circulates in the condenser condensing the low pressure wet steam.
  3. This condensed water is then provided to a low-pressure water heater where the low-pressure steam raises the temperature of this feed water, then it is heated again in a high-pressure heater where the high steam pressure is used for heating.
  4. The turbine in the thermal power plant functions as the alternator’s prime mover.

Overview of Thermal Power Plant-

Water and steam are the working fluid. This is called steam cycle and feed water.The RANKINE CYCLE is the perfect thermodynamic cycle that strongly resembles the operation of a thermal power station.

The water is backed up in a steam boiler by burning the fuel in the furnace air, and the boiler’s role is to provide dry superheated steam at the desired temperature. The steam thus generated is used to drive the steam turbines. This turbine is combined to a synchronous generator (generally a three-phase synchronous alternator), for producing electrical energy. The turbine exhaust vapor is permitted to condense into water in turbine steam condenser, which generates suction at very low pressure and enables the steam to be expanded to very low pressure in the turbine. The main benefits of the condensing operation are the enhanced quantity of energy obtained per kg of steam, thus improving effectiveness, and the condensate fed into the boiler decreases the quantity of fresh feed water again. A pump (called the boiler feed pump) again feeds the condensate with some new make-up feed water into the boiler. Cooling water condenses the steam in the condenser. Cooling water recycles in the cooling tower. This makes a cooling water circuit.

After filtration of dust, the ambient air is permitted to enter the boiler. The flue gas also goes out of the boiler and is exhausted through stacks into the atmosphere. These makes air and flue gas circuit. Two fans named Forced Draught (FD) fan and Induced Draught (ID) fan maintain the flow of air and also the static pressure inside the steam boiler (called draught).

There are different heat exchangers inside the boiler, viz. Economiser, Evaporator (basically there are water pipes, i.e. downcomer riser circuit), Super Heater (sometimes there are also heaters, air preheaters).

In Economiser, the remaining heat of flue gas heats the feed water to a significant quantity.

The Boiler Drum retains a two-phase combination (steam + water) head for natural circulation through the water pipes.

There is also a Super Heater that also takes heat from flue gas and increases the steam temperature as required.

Advantages and Disadvantages of Thermal Power Station-


  1. Economical other than any generating plant for low initial price.
  2. Land needed less than a hydroelectric power plant.
  3. Since coal is the primary fuel and its price is quite inexpensive than petrol / diesel, the price of generation is therefore economical.
  4. It’s simpler to maintain.
  5. Thermal power plants can be mounted wherever there is transportation and a large amount of water.


  1. Due to fuel, maintenance etc., the operating price for a thermal power station is relatively large.
  2. Large quantities of smoke cause air pollution. These causes Global warming.
  3. The heated water from the thermal power plant has an adverse effect on the water life and disturbs the ecology.

Thermal Power Plant Location-

  1. The power plant must be built in such a location where the price of land is quite sensible.
  2. The land should be such that it must be minimal to acquire private property.
  3. For heat power generation plant condensers etc., a large amount of cooling water is needed, so the plant should preferably be located next to a large source of natural water such as a large river.
  4. One of the main criteria for selecting the place of the plant is the availability of large amounts of fuel at reasonable price.
  5. The plant must be made on plane land.
  6. The soil should be such that the plant and houses should be well and firmly founded.
  7. The place of the thermal power plant should not be much closer to the dense place as smoke, noise vapor, water vapor, etc. are present.
  8. Development of future demand must be broad.
  9. Place for thermal power station ash handling plant should also be accessible very close by.
  10. Very tall power station chimney should not interfere with airship traffic.

Thermal Power plant In India-

More than 65% of India’s energy generation capability comes from thermal power plants, 85% of the country’s thermal power generation is coal based. All of India’s ten largest thermal power plants are coal-fired, with five owned and operated by the state-run National Thermal Power Corporation (NTPC).

Here is the list of The top 10 biggest thermal power plants in India

Vindhyachal Thermal Power Station, Madhya Pradesh4,760MW
Mundra Thermal Power Station, Gujarat4,620MW
Mundra Ultra Mega Power Plant, Gujarat4,000MW
Sasan Ultra Mega Power Plant, Madhya Pradesh3,960MW
Tiroda Thermal Power Plant, Maharashtra3,300MW
Talcher Super Thermal Power Station, Odisha3,000MW
Rihand Thermal Power Station, Uttar Pradesh3,000MW
Sipat Thermal Power Plant, Chhattisgarh2,980MW
Chandrapur Super Thermal Power Station, Maharashtra2,920MW
NTPC Dadri, Uttar Pradesh2,637MW

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