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Energy Conservation in Power plant Electrostatic Precipitator (ESP) by Using Waste Heat Recovered from Boiler

Sundarrajan.S, S.Mohammed Shafee

Energy conservation is the very major concern in recent scenarios, mainly in power plants. The following work is done in accordance with North Chennai Thermal Power Station. In power plants, Electrostatic precipitators (ESPs) are utilized to filter the fly ash from exhaust flue gas before passing it to the atmosphere. The fly ash is collected down in the ESP hoppers, which are provided with heat by the application of heating coils. The function of heating coils is to heat the ESP hoppers and make a free flow of ash while removal from hopper. Power supplied to heat the coils is taken as the auxiliary power consumption from the total power produced in the plant. The main purpose of this work is to eliminate this unwanted auxiliary power consumption so far consumed for the purpose of heating ESP hopper heaters, by replacing the heaters with waste heat recovered from boiler in a conventional thermal power plant. By performing this work, auxiliary power consumed for this entire hoppers can be saved, which can save the supply and add economic advantage to the plant. This can be done by using the hot air source tapped from secondary air duct before the entry into wind box of the boiler. This is atmospheric air which passes through a regenerative Air Preheater (APH) to procure hot air to burn the pulverized coal. Thus taking small mass flow of air by tapping the duct, the heat source can be obtained. The temperature of hot air required, mass flow rate, heat exchanging method, modified hopper design are the main parameters considered and optimised. This new retrofit in the thermal power plants can save enormous amount of power supplied earlier and can add economic benefits to all thermal power stations across our country.