Capture of submicrometer particles in a pressurized electrostatic precipitator

Abstract

This study investigated the influence of gas pressure on the submicrometer particle capture performance of an electrostatic precipitator (ESP). Current-voltage characteristics and particle capture performance of the ESP were studied in air and in simulated flue gas (SFG) under 1, 2, and 3 atm. Using negative corona and air as the feed gas, the penetration of most particles of 40–400 nm in diameter decreased from 8 × 10−4 − 2 × 10−2 to 2 × 10−4 − 1 × 10−2 as pressure increased from 1 atm to 3 atm at constant current; and increased from 3 × 10−5 − 1 × 10−3 to 2 × 10−4 − 1 × 10−2 as pressure was elevated when the voltage was held roughly constant. Similar type of disparity under different pressures was also observed for positive corona and for SFG. Experiments set up to capture fly ash in the ESP showed that with constant current, higher pressure resulted in a higher initial charge fraction of the particles from the furnace, which could facilitate the penetration of fly ash particles. A semiempirical model was developed based on the Deutsch–Anderson equation and experimental data under 1, 2, and 3 atm to calculate the particle penetrations under high pressure. The total charge number on a particle (n') is calculated by incorporating the effects of current (I) and pressure (P) on relative weights of the diffusion charging number (ndiff) and field charging number (nfield), that is, n' = B1(I,P)ndiff + B2(I,P)nfield, where B1(I,P) and B2(I,P) are both empirical coefficients dependent on current and pressure. Experimental penetrations under 1.5 and 2.5 atm validated this model over the particle diameter range in 100–400 nm. Copyright © 2016 American Association for Aerosol Research