HISTORY OF PULSE ENERGIZATION IN ELECTROSTATIC PRECIPITATION

The history of modern, high frequency pulse energization in electrostatic precipitation is reviewed viewed from its beginning stemming from microsecond radar pulse generator development (1941-1945) to early research and development leading to first tests on field precipitators (1947-1952), thence to later developments (1970-present) by a number of investigators in U.S.A., Europe and Japan. This work produced a variety of basic pulse energization circuits and technology used in research, development and field demonstration studies on full-size ESPs. Interest and activity in pulse energization to avoid the deleterious effects of back corona for dusts in the range 1011-1013 ohm cm remains high worlwide. The tecnology has been accepted as a viable, reliable, and effective method for significantly improving the performance of existing electrostatic precipitators, and reducing the size and cost of new ESP designs treating difficult high resistivity dusts. Over 100 commercial pulsers in many countries worldwide have been installed since 1981 and are now extant for high efficiency dust collection in major industries such as cement, power generation lime kilns and steel. Pulse energization technology now centers in three major areas: pulse widths in the nanosecond range, in the nominal 1-2 μs range, and in the range 50-200 μs - the first two using spark gap switches to achieve very fast voltage rise times and the third generally using solid-state thyristor switching. Of special current interest is use of submicron high voltage pulses for pre-charging and for generating an active corona plasma for chemical reactions to remove SO2 and NOx from boiler flue gases. A brief section on ESP fundamentals and application factors with pulse energization, as well as an extensive bibliography, are included. © 1990.