27-09-2012, 12:32 PM
Farakka Super Thermal Power Station
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INTRODUCTION
Farakka Super Thermal Power Station is situated at a distance of 300 km away from Kolkata in North Bengal in the tusks of nature. It is spread on both side of holy Ganga covering total area of 4330 acres. Its coal source is eastern coalfield from the Rajmahal coalmines by the assistance of merry go round. Farakka NTPC gets water from feeder canal of the Farakka Barrage Project. One more Unit of 500 MW is yet to come by next year.
Basic understanding of thermal power generation
In a thermal power plant, the thermal energy of the superheated steam is used to drive the generator, which in turn produces electricity. The superheated steam is produced from any fossil fuel like coal, crude oil etc. Since coal is available in plenty and in cheap, we use coal as the primary fuel in the thermal power plants. The coal is pulverized, grinded and powdered before it is used in the boiler. The pulverization of coal increases the surface area of the coal, which helps in the smooth combustion of the coal. The coal is feed to the boiler where it is fired to produce heat. Initially, a small quantity of crude oil is used for the purpose. The water is passed through the pipes fitted in the walls of the boiler. The water is heated to produce steam, which is further reheated to produce superheated steam. The superheated steam at an exceedingly high temp. And pressure drives the turbine. The turbine rotates following which the generator, which is coupled to the turbine, also rotates producing electricity.
Working Principle of the boiler:
Firstly DM water is fed to the Economizer coil. Here DM water is slightly heated .Then it is passing to the Penthouse and fed to the boiler drum. In the boiler drum water and steam both are stored. In the boiler drum there consists a separator which separates the stem to the water. Due to the firing of the coal powder which is coming to the eight mills, producing flue gas. Then flue gas is passing to the coils. There consist of three coils, (a) platen super heater, (b) re heater, © Final super heater. So flue gas is first passing to the platen super heater. Then it is passing to the final super heater. Then it is passing to the re heater. So the coil is being heated. The temperature of the flue gas is decreasing & it is fed to the economizer coil. Then the steam to which is separated to the boiler drum is passing to the coils. Finally the super heated steam which is called the main steam is fed to the HP Turbine.
water treatment plant and storage
Since there is continuous withdrawal of steam and continuous return of condensate to the boiler, losses due to blow down and leakages have to be made up to maintain a desired water level in the boiler steam drum. For this, continuous make-up water is added to the boiler water system. Impurities in the raw water input to the plant generally consist of calcium and magnesium salts which impart hardness to the water. Hardness in the make-up water to the boiler will form deposits on the tube water surfaces which will lead to overheating and failure of the tubes. Thus, the salts have to be removed from the water, and that is done by a water dematerializing treatment plant (DM). A DM plant generally consists of cation, anion, and mixed bed exchangers. Any ions in the final water from this process consist essentially of hydrogen ions and hydroxide ions, which recombine to form pure water. Very pure DM water becomes highly corrosive once it absorbs oxygen from the atmosphere because of its very high affinity for oxygen