![]() Steam is generated in the boiler of the thermal power plant using the heat of the fuel burned in the combustion chamber. The different components, which are used in thermal power plants, are listed below: Boiler, steam turbine, generator, condenser, cooling towers, circulating water pump, boiler feed pump, induced/forced draught fans, ash precipitators etc Working of the thermal power plant Open system is economical than closed system provided adequate water is available throughout the year. ![]() When the water coming out from the condenser is discharged to river downward side directly, the system is known as open system. When the cooling water coming out of the condenser is cooled again and supplied to the condenser, then the system is known as closed system. To compensate the evaporative loss, the water from the river is continuously supplied. This evaporative loss (this includes evaporation and carryover) is nearly 2 to 5 % of the cooling water circulated in the system. The cooling is effected by partly evaporating the water. When the adequate water is not available, then the water coming out from the condenser is cooled either in cooling pond or cooling tower. Such system of cooling water supply is possible if adequate cooling water is available through the year. The cooling water is taken from the upper side of the river, it is passed through the condenser and heated water is discharged to the lower side of the river. The quantity of cooling water required to condense the steam is considerably large and it is taken from lake, sea or river. This circuit consists of circulating water pump, cooling water pumps and cooling tower. The purification is necessary to avoid the scaling of the boiler tubes. The feed water supplied from external source is passed through the purifying plant to reduce the dissolved salts to an acceptable level. Some of the steam and water is lost passing through different components of the system, therefore, feed water is supplied from external source to compensate this loss. The feed heaters may be of mixed type or indirect heating type. The condensate is heated in the feed heaters using the steam tapped from different points of the turbine. The steam coming out of prime mover is condensed in the condenser and then fed to the boiler with the help of pump. The steam generated in the boiler is fed to the steam prime mover to develop the power. ![]() This circuit consists of boiler feed pump, boiler, turbine and feed heaters. The exhaust gases carrying sufficient quantity of heat and ash are passed through air preheater where the exhaust heat of the gases is given to the air and then it is passed through dust collectors where most of the dust is removed before exhausting the gases to the atmosphere through chimney. The dust from the air is removed by means of using air filter before supplying to the combustion chamber. Air is taken in from the atmosphere to the air preheater through the action of a forced or induced draught fan or by using both. This circuit consists of air filter, air preheater, dust collector and chimney. ![]() layout of steam power plant -Diagram of thermal steam power plant The Indian coal contains 30 to 40% of ash and a power plant of 100MW produces normally 20 to 25 tones of hot ash per hour. Ash resulting from combustion of coal collects at the back of the boiler and is removed to the ash storage yard through ash handling equipment. Coal arrives at the storage yard and after necessary handling, passes on to the furnaces through the fuel feeding device. The handling system consists of belt conveyors, screw conveyors etc. This circuit consists of coal storage, ash storage, coal handling and ash handling systems.
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