Thermal Power Station: 5 Important Subsystems

Thermal Power Station

Thermal Power Plant or station is one of the main sources of electrical power plant and extensively used and This thermal power plant is typically referring as Thermal or steam-turbined power plant fueled by mainly fossil fuels (such as coal, diesel, petroleum or natural gas or sync gas has been used).

Theory of Thermal Power Station.

Usually, steam is produced from high-pressure boiler by utilizing heat generated from fossil fuel. In India, to run the thermal power plant, most commonly used coal is in form of bituminous or brown type, though less qualified peat one also utilized used.  In the power plant water generally used in steam generator where steam is generated, flows thru the turbine (which drives an electrical generator), and rotates the generator’s rotor and after that steam is condensed and recirculated in closed loop cycle.

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A Coal Based Thermal Power station image credit : pixabay free images

Advantages and Disadvantages of Thermal Power Station


  • This has low initial cost and it’s power generation cost is also economical in comparison to other methods.
  • Maintenance is easier comparatively.
  • Land required less in comparison to hydroelectric power plant, this may instal in any location having sufficient fuel , water and power demand. 


  • The running cost is higher because of high-fuel price, pollution free instruments installation, periodic maintenance requirements.
  • Overall efficiency is low ( 30%).
  • Source of pollution, responsible for Global warming.

Components of Thermal Power plant:

Components of Thermal Power plant
Components of Thermal Power plant image credit : pixabay free images


Image Credit: Unknown author, Reed water tube boiler cross sections, marked as public domain, more details on Wikimedia Commons


The economizer is located below the LPSH in the boiler and above preheater.

Advantages of Economizer are

1) Fuel economy: –overall efficiency of the boiler plant has improved.

2) Reducing the size of the boiler: – as the feed water is pre-heated in the Economizers sections and will enter the boiler tube at the higher temp, So boiler overall size will decrease for this.

Air Pre-heater:

Preheating is used for drying the wet fuel i.e., coal. Hot air has been supplied or recirculated flue gas from economizer has been utilized for this purpose.


This usually contain multiple metal tube- based section in surrounding flue gas outside the tubes will flow. Exhaust steam from the high-pressure turbine is re-routed to re-heater tube and produces more energy for turbine blade to rotate.

Steam turbines:

This is steam driven turbine. The steam turbine is divided into 2-types.

  • Impulse turbine.
  • Impulse-reaction based turbine.


The purposes of a condenser are: –

  • To provide a cost-effective heat rejection temperature for generated steam.
  • To convert exhaust steam into the water for the reserve to save feed water requirement.
  • To introduce water in the system.

The big surface based condensers is employed mostly even though there is one direct contact type also available.

Boiler feed pump:

The boiler feed pump (BFF) is a multi-stage pump utilized for feedwater pumping to Economizer. This is an auxiliary equipment having high power requirement for operation.

Cooling tower:

The tower is an significant device in thermal power plant for cooling the coolant by means of conduction and convection.

Fan or draught system:

At a boiler, it is vital to evacuate hot gases formed in the furnace thru the several area boilers to provide better control. The air needs to be supplied to the furnace for more effective combustion of fuel. This is provided by utilizing chimney or big fan type device.

  • i) Natural draught.
  • ii) Mechanized draught.

There are 3 types of draughts system-

  • Forced draught system.
  • Induced draught system.
  • Balanced draught system.

Ash handling system

Cyclonic separation method is utilized to separate particulates matter from air, gas.

Electrostatic precipitator: 

From the air preheater, this flue gases (blended with ash) moves to ESP. Here electrodes employed to ionize ash or smoke particulate and collects those dust particles. The electrodes are kept in around 60KV. Hammering is performed to the plates, and so that fly ash collects at the base and comes down. This fly ash is nowadays used in cement manufacturing plants, special type ash brick productions.

Manual handling:

Here, ash is collected manually from bottom ash collecting doors.

Mechanical handling:

Mechanical handling equipment may also utilize for ash disposal, mainly employed in bucket elevator and belt conveyor.


The steam mechanical energy has been utilized to produce electricity generation by utilizing Faraday’s principle of electro-magnetic induction.

Chimney of Thermal Power Plant.

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A Photograph of Chimney of Thermal Power Plant. image credit : pixabay free images

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