Thermal power plant and its Working Principle

A thermal power station is known as power plant in which the prime mover is steam drive. Water is made to enter into the system and then heated, later which turns into the steam. The steam spins in a steam turbine which efforts an electrical generator.

The Basic Components Of  The Thermal Power Station Are

  • Boiler
  • Steam turbine
  • Generator
  • Condenser
  • Cooling towers
  • Circulating water pump
  • Boiler feed pump
  • Forced or induced draught fans
  • Ash precipitators

These are the main components in the thermal power plant


A boiler is a closed vessel in which the water or fluid is heated

Steam turbine

A steam turbine is a device which extracts thermal energy from the pressurized steam. The energy must be used to organize mechanical work on a rotating output shaft.


A generator is a device which is used to convert the mechanical form of energy into the electrical energy.


A condenser is a device used to converts the gaseous substance into the liquid state substance with the help of cooling.


Cooling towers

A cooling tower is a heat rejection device, which discards the waste heat into the atmosphere with help of the cooling water stream to a lower temperature.

Circulating water pump

Circulating pump is a special device used to circulate the liquids, gases and slurries present in the closed circuit. The main purpose of the circulating pump is circulating the water in a cooling system or hydronic heating.

Boiler feed pump

A boiler feed pump is a specific type of pump which is used to feed the water into the steam boiler. The condition of water supply depends on the boiler produce the condensation of the steam.

Forced draught fans

Forced draught fans are used to provide a positive pressure to a system.

Induced draught fans

Induced draught fans are used to provide a negative pressure or vacuum in a slack or system

Ash precipitators

Precipitators are devices used to remove the fine particles like smoke and dust. By using the force of induced electrostatic charge minimally close the flow of gases through the unit.

Working Principle Of Thermal Power Plant:

Water is used as the working fluid in the thermal power plant. We can see coal based and nuclear power plants in this category. From the working of the power plant energy, later from the fuel gets transferred into the form of electricity. With the help of high pressure and high steams a steam turbine in a thermal power plant is rotates, the rotation must be transfer to the generator to produce power.

When turbine blades are rotated with the high pressure and high temperature at that case the steam loses its energy. So it results in the low pressure and low temperature at the outlet of the turbine. Steam must be expanded upto the point where it reaches the saturation point. So from the steam, there is no heat addition or removal that takes place. Entropy of the steam remains same. So we can notice the change in the pressure and volume and temperature along with the entropy diagrams. If the condition comes to the low pressure and low temperature steam back to the original state, from that we can produce continuous electricity.

To compress the gaseous state liquids at that case large amount of energy is required. So before the compression we need to convert the fluids into liquid state. For this purpose condenser is required and heat is rejected to the surroundings and converts the steam into liquid state. During this process the temperature and volume of the fluid changes take place hardly, so it turns into liquid state. And the fluid turns to the original state. To bring the fluid to the original state external heat is added. To the heat exchanger heat is added which is called as boiler. Then the pressure of the fluid must remain same. In heat exchanger tubes it expands freely. Due to increase in temperature the liquid state is transformed into the vapour state and the temperature remains same. So know we complete the thermodynamic cycle in the thermal power plant. It is known as Rankine cycle. By repeating the cycle we can produce the power continuously.

With the help of boiler furnace heat is added to the boiler. Then the fuel must reacts with the air and produces heat. The fuel must be either nuclear or coal. In this process if we use coal as a fuel we can observe lot of pollutants before ejects in to the air clean or removed the particles and send into surroundings. The process is done in various steps. By using the electro static precipitator the ash particles are removed. So with the help of the stack clean exhaust must be send outside.

Characteristics of steam power plant:

  • It gives high efficiency
  • Cost is low
  • Water requirement is reduced
  • Environmental impact like air pollution is reduced
  • Higher availability and reliability
  • Ability to burn coal mainly high ash content

Advantages of thermal power plant:

  • Compare to the hydroelectric plant the initial set up cost must be low
  • Near to the load centers the power plants are located, for that the transportation cost is low and transmission is reduced.
  • In hydroelectric power plant the quality depends upon the nature like rives and rains.
  • We cannot observe the situation in the thermal power plant.
  • Construction must be takes place in very less period compare to the remaining power plants.

Disadvantages of Thermal power plant:

  • We are using nonrenewable energy resources in this process
  • It cannot be used as a peak load plant; part load efficiency must decreases rapidly along with decreasing load.
  • The coal plants are located far away from the power plants so it is difficult to transport the fuel to the plant
  • The power generation cost is high compare to the hydroelectric power plant
  • The released smoke produces the pollution in the surroundings.
  • The life time must be 25 years and for hydropower plant it is 35 years

Click Here To Know More About: Turbines & Types of turbines