This article explains the basics of the working of a coal fired thermal power plant.
More than half of the electricity generated in the world is by using coal as the primary fuel.
The function of the coal fired thermal power plant is to convert the energy available in the coal to Electricity.
Coal power plants work by using several steps to convert stored energy in coal to usable electricity that we find in our home that powers our lights, computers, and sometimes, back into heat for our homes.
image provided by the Tenesee Valley Authority
How Coal Power Plants Produce Electricity
The conversion from coal to electricity takes place in three stages.
Stage 1
The first conversion of energy takes place in the boiler. Coal is burnt in the boiler furnace to produce heat. Carbon in the coal and Oxygen in the air combine to produce Carbon Dioxide and heat.
Stage 2
The second stage is the thermodynamic process.
- The heat from combustion of the coal boils water in the boiler to produce steam. In modern power plant, boilers produce steam at a high pressure and temperature.
- The steam is then piped to a turbine.
- The high pressure steam impinges and expands across a number of sets of blades in the turbine.
- The impulse and the thrust created rotates the turbine.
- The steam is then condensed and pumped back into the boiler to repeat the cycle.
Stage 3
In the third stage, rotation of the turbine rotates the generator rotor to produce electricity based of Faraday’s Principle of electromagnetic induction.
Check out this series describing the layout of thermal power plants.
Key Facts About Coal-Fired Electricity Production
In practice to effect these three stages of conversion, many systems and sub systems have to be in service. Also involved are different technologies, like combustion, aerodynamics, heat transfer, thermodynamics, pollution control, and logistics.
As an example consider these facts for typical coal fired power plant of capacity 500 MW.
- Around 2 million tons of coal will be required each year to produce the continuous power.
- Coal combustion in the boiler requires air. Around 1.6 million cubic meter of air in an hour is delivered by air fans into the furnace.
additional facts can be found on page 2