The thermal power plant uses coal as a fuel. The chemical energy of coal is converted into electrical energy.
By the burning of coal, various pollutants are released from the thermal power plant. These pollutants are listed below;
- Sulphur Dioxide (SO2) and Hydrogen Sulphide (H2S)
- Oxides of Nitrogen (NOX) [Nitric Oxide (NO), Nitrous Oxide (N2O), Nitrogen Dioxide (NO2), Nitrogen Trioxide (NO3)]
- Suspended particulate matter (SPM)
- Thermal pollution
- Carbon dioxide (CO2)
Effects of Pollutants
SO2 and H2S cause irritation of the throat, asthma, suffocation, and lung cancer. In presence of moisture, SO2 causes corrosion of metallic parts.
Oxides of Nitrogen (NOX) irritates the eyes, nose, and throat. It also causes coughing, headache, and damage to the lungs.
Suspended Particulate Matters (SPM) are responsible for respiration problems like cough, cold, and sneezing. It causes cardiac diseases and is responsible for soiling and corrosion of metal parts of power plants.
Carbon dioxide (CO2) is responsible for global warming of the atmosphere (Greenhouse effect). It increases temperature and results in melting polar ice caps with catastrophic flooding of coastal areas.
SO2 and NOX combine with water to form H2SO4 and HNO3 which fall in the form of acid rains in the rainy season. It increases the PH value of the river, lakes, and well water affects the life of fishes, and fertility of the soil, and damages national monuments and buildings.
Hot-cooling water is discharged from power plants into rivers, lakes, or the sea causing thermal pollution. Due to the chemicals released, the water is contaminated. The chlorine residue in hot water is harmful to aquatic life, a life of plants, etc.
Control of Pollutants
Control of SO2
The Sulphur dioxide SO2 can be controlled by;
- Desulphurization of fuels by a chemical process or froth floatation process
- Scrubbers, electrostatic precipitators, or catalytic oxidation
Control of SPM
Suspended Particulate Matters (SPM) are controlled by fabric filters, hydraulic and pneumatic ash handling systems, and electrostatic scrubbers for dust collections.
Control of NOX
Oxides of Nitrogen are reducing the temperature of combustion below 1000˚C since the formation of NOX below 1000˚C is very low.
It can be reduced by reducing time in the high-temperature combustion zone, increasing in A-F ratio from more than 60% to 80%, or using fluidized bed combustion (FBC) technology.
Control of Thermal Pollution
Thermal pollution can be controlled by the construction of separate lakes, cooling towers, and cooling ponds to reject the heat of cooling water into the atmosphere before it is discharged into lakes and rivers.
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