PERFORMANCE IMPROVEMENT OF ELECTROSTATIC PRECIPITATOR: SOME EXPERIMENTAL STUDIES

Emissions standards are becoming more stringer, as a result new retrofit/technique are being applied in the existing power plant in India. Electrostatic Precipitators (ESP) are used to control fly ash emitting from the boilers of the power plants. The coal burned in power plants in India to generate the power are characterized by low calorific value (3500-4500) Kcal/Kg., and high ash content (35-45) %. Thus compared to U.S. and European coals, Indian coal generate about 6 to 7 times more ash for collection for similar electricity generation. Besides, low sulfur content (<0.5), results in the resistivity of fly ash being 100-1000 times higher than that generated elsewhere. Thus ESPs in India, despite being much larger, have lower collection efficiencies than the ESPs in U.S/Europe. In this paper we discuss some methods which are being applied in different power plants in India to improve the collection efficiencies of ESP. The methods, which have met with success, are (a) Pulse charging of ESP unit, (b) Flue gas conditioning by water fogging and ammonia, and (c) coal ash conditioning with sodium salt before feeding to boiler. In some case additional ESP was put in series with the existing one thereby, increasing the total collection area. The paper describes the experiments and analyses the results obtained. 2