Application of Electrostatic Precipitators for The Control of Fumes from Low Odor Pulp Mill Recovery Boilers

Abstract

The cellulose pulping industry has long used electrostatic precipitators to collect soda ash entrained in recovery boiler flue gases. At a collection efficiency of 85 to 95%, the optimum economic situation is reached where capital outlay and operating expenses balance the value of the chemicals recovered over the life of the equipment. In recent years, however, stringent governmental regulation of particulate emissions has necessitated collection efficiencies above 99%. Although economic operation can not be achieved, traditional precipitator design is readily adaptable to these higher collection efficiencies. The pulp and paper industry in the United States has recently embarked upon a program to eliminate the emission of odorous gases from pulp mills. This involves q totally different operation of the kraft pulping liquor recovery process. Low odor operation of the recovery boiler results in a particulate emission with different physical properties than those produced by the traditional process. Electrostatic precipitators of the traditional design are incapable of handling this particulate emission. Fundamental changes in precipitator design and application are therefore necessary.