Thermal energy is the energy that results from the temperature of a heated substance. Additionally, most thermal power plants use the power of steam to drive turbines. Thermal power plants are usually used in the industrial sector primarily to generate electricity.
As India’s population grows, so does energy consumption, with India consuming about 6% of the world’s primary energy. Looking at the last 69 years since India’s independence, power capacity has grown from the 1,300 MW to 267,000 MW. However, despite this increase in electricity production, demand is outstripping production.
The world’s nearly two-thirds of its electricity needs are met by thermal power plants, also known as thermal power stations. These power plants generate steam by burning fossil fuels like coal, which is subsequently used to turn a steam turbine. As a result, a thermal power plant may also be referred to as a steam power plant. Steam is condensed in a condenser and then sent back into the boiler after going through the steam turbine. The ranking cycle is this. This article outlines the process through which thermal power plants produce electricity. Coal is the principal fuel used by the vast majority of thermal power plants.
Fossil fuels are mainly used in thermal power plants to generate electricity, especially coal, which accounts for 76% of the electricity generated in the country. According to the ministry, coal production in 2021 will increase by 6% compared to 2020. India’s total thermal power generation capacity as of January 2021 is 231,870.72 MW.
Layout of Coal-Based Power Plant:- The layout of the steam power plant consists of the following parts. Those are:
- Coal and Ash Handling Unit
- Steam Turbine
- Feed Pump
- Cooling Tower
Coal and Ash Handling Unit:
Before feeding the coal to the furnace, It is to be converted into the pulverized form and after the combustion, the ash is collected in the ash handling unit.
Coal: Coal is transported from coal mines to the generating station in a thermal power plant that runs on coal. Bituminous coal, often known as brown coal, is typically used as fuel. Either ‘dead storage’ or ‘live storage’ are used to keep the coal. Dead storage, which is used when there is no coal supply, is typically 40 days of backup coal storage. In a boiler building, live storage is a bunker for raw coal. To filter out any iron particles that can cause equipment wear and tear, the coal is cleaned in a magnetic cleaner. The coal from live storage is first broken down into tiny pieces, and then it is put through a pulverizer to turn it into powder. Pulverized coal is made by completely combusting fine powdered coal.
A mixture of pulverized coal and air (usually preheated air) is fed to the boiler and burned in the combustion zone. When the fuel is ignited, a large fireball is formed in the center of the boiler, from which a large amount of heat energy is radiated. It uses heat energy to convert water into high-temperature, high-pressure steam. Steel pipes run along the walls of the boiler, where water is converted to steam. The flue gas from the boiler passes through the superheater, economizer, air preheater and finally to the atmosphere through the chimney.
Superheater:-Superheater tubes are suspended at the hottest point of the boiler. Saturated steam generated in the boiler tubes is superheated to approximately 540°C by the superheater. The superheated high-pressure steam is supplied to the steam turbine.
– An economizer is essentially a feedwater heater that heats the water before it is supplied to the boiler.
– A primary air fan draws air from the atmosphere and heats it with an air preheater. Preheated air containing coal is blown into the boiler. The advantage of preheating the air is improved coal combustion.
– Superheated high-pressure steam is supplied to the steam turbine to rotate the turbine blades. The energy contained in steam is converted into mechanical energy in a steam turbine that acts as the prime mover. As the steam passes through the turbine, its pressure and temperature decrease and its volume expands. Expanded low-pressure steam is discharged in a condenser.
– Extracted steam is condensed in a condenser by cold water circulation. The steam loses both pressure and temperature and turns back into water. Condensation is essential because it requires a huge amount of energy to compress a liquid in its gaseous state compared to the energy required to compress a liquid. Condensation, therefore, increases the efficiency of the cycle.
– The steam turbine is connected to the alternator. When the turbine rotates the generator, it produces electrical energy. This generated voltage is stepped up with the help of a transformer and sent to where it is used.
Feed Water pump:
・The condensed water is returned to the boiler via the water supply pump. Some water may be lost during the cycle and is adequately supplied from an external water source.
This was the basic operating principle of thermal power plants and their typical components. Real heat plants have more complex designs and multiple turbine stages, such as the high-pressure turbine (HPT), intermediate-pressure turbine (IPT), and low-pressure turbine (LPT).
In coal-fired power plants, the chimney plays an important role in the overall operation of the power plant.
A chimney is a tall structure that discharges combustion products and byproducts of the coal combustion process into the atmosphere.