NDA » NDA Study Material » General Knowledge » Mineral and Power Resources-Thermal Plants

Mineral and Power Resources-Thermal Plants

Thermal plants generate electricity through the combustion of water into steam which rotates turbine blades thus converting kinetic energy to electricity.

Thermal plants are used for generating electrical energy from heat energy. The process of combustion involves solid fuel like coal that is further utilized for converting water into steam, having very high temperatures and pressure. Big turbine blades attached to a generator are rotated with the stream produced, while the generator plays the role of conversion. The turbine impeller containing kinetic energy is converted to electrical energy. Water fed into the boiler tanks needs to be treated well as impurities and dissolved oxygen can corrode surfaces of tanks or other pieces of equipment.  

Thermal Plants

Thermal plants are utilized for the generation of thermal power using steam power, burning oil, coal, LNG, and several other substances are used for combustion. Thermal power plants help in meeting fluctuating demands of electricity needs so that the overall output gradually increases. In today’s digitalized world, where every process is getting automated through IT tools or other machine learning programs, several advanced pieces of equipment are also used in such plants in order to reduce the workforce and increase overall power generating efficiency of already used equipment. Thermal power plants are the sources of electricity in several countries, like Japan, where a high amount of fluctuations in electricity demand is met through them.   

Procedure 

Fuel which is needed in thermal plants for the combustion process is transported via trains from mines to the storage area of the plant. Crushers make the big-sized particles to small size before feeding them to the boiler furnace, where a huge amount of heat is produced. Again there is a boiler drum, where water is stored for vaporization. Before storing in the drum, it has been ensured that the water is free of any impurities, and viruses. A required amount of air is also required to be inserted in the boiler drum, after which combustion heat is allowed to convert water to steam having high temperature and pressure. In the whole process, flue gases present in boiler exhaust bearing high temperature are produced, which reduces the efficiency of the boiler. This is termed wastage of heat that can be utilized in other ways, like the normal water which is fed to the drum can be preheated. Flue gases need to be purified before releasing directly into the atmosphere; they can be passed through filter bags or dust collectors for doing the same.  The fuel needs to be stored properly in the storage area so that it is able to provide the plant with continuous supply, even during times when there is a shortage of fuel. The very first step of the whole process involves the generation of power where fuel is supplied to the breaker house with a conveyor belt, and with the help of gravitation, lighter dust particles and other impurities are separated. After that the crusher breaks the particles into smaller pieces, having a size of 50mm or less. Huge volumes of water are fed to the plant for converting into steam, which is used to rotate the turbine blades and other accessories. Water that is being fed to the drum is usually derived from the river, and it has numerous dirt particulates. These dirt particles need to be treated, as they corrode the surface of the equipment reducing efficiency and overall life. Further scaling of equipment can take place, leading to overheating of the pressure parts along with explosions. Hence, the water needs to be purified before being fed to the boiler, like alum can be used for removing suspended matters, where gravity separation can be seen. The ion exchange process is used for softening water because of the presence of bicarbonates and carbonates of magnesium and sodium hardness water. Boiler tubes may get fouled, or even corrode due to the presence of dissolved oxygen in water, so oxygen scavengers in deaerator tanks are utilized for removing dissolved oxygen. 

Advantages and disadvantages of Thermal power plant

A hydroelectric station is costlier as compared to a thermal power plant, due to the high initial cost as well as more space consumption. Thermal plants can be utilized to generate comparatively high amounts of power, and the cost of generation is also found to be lower as compared to other electricity generation plants like diesel power stations. Again fuel cost is lower in this case; however, due to the production of pollutants from combustion, the air pollution rate goes high. The maintenance cost of the overall system is much costlier, as skilled personnel are essential. Requirement for land areas is more in this case as storing fuel and ash requires huge spaces. Large water sources are essential as huge amounts are required for producing electricity that can meet the requirements of a huge population.  

Conclusion 

Thermal plants are used for the purpose of electricity, as they have a great contribution in meeting fluctuating demands like in Japan. Primary air fan, mobrey plug, fusible plug, fluidized bed combustor, dust collection system, turbine, steam boiler, water treatment plant, and fluid storage plant are the major parts. The basic procedure involves the combustion of fuel like coal which converts water into steam, which is used in rotating turbines. These turbines are attached to a generator that converts kinetic energy to electricity, which is collected and transferred to the required place. The overall efficiency is found to be 35% to 40%.