Abstract :
In electrostatic precipitators (ESPs) the electric field is responsible for producing ions in the vicinity of the corona wires, charging particles, and transporting charged particles to the collecting plate. In standard Cottrell-type precipitators, these functions are performed by applying a dc voltage between corona electrodes and collecting plates. Because ion production requires a high electric field strength near the cathode while particle transport is optimized in a uniform field, this arrangement is always a compromise, and sometimes a poor one. Energizing precipitators with both a dc base voltage and superimposed pulse voltage, on the other hand, provides for a separation of the functions; particle transport being performed by the dc base voltage and ion production by the pulse voltage. Besides offering improved control, pulsed energization provides for inherently better performance of ESPs, due in part to enhancement of particle charge as a result of ion density concentration and also to a more uniform corona current distribution along the length of the corona wire. This paper discusses these aspects of pulse charging as well as its effect on back corona, a phenomenon which degrades performance of ESPs for high resistivity dust conditions. Laboratory and full scale field tests of pulse energized ESPs are also described and analyzed. These tests show that the application of fast pulses to ESPs results in considerable improvement of collection efficiency.
