LABORATORY RESEARCH ON COLLECTION OF PARTICLES REENTRANIED FROM CORONA ELECTRODE

At the exit of electro static precipitator, among the escaped particles there have not only neutralized particles, but also particles that remaining negative and positive charges. Sometimes positively charged particles can account for 30%~50% of the total particles escaped. They are formed probably from the reentrainment by corona electrode rapping or from back corona effects. In view of this phenomena, for strengthen the corona electrode capability of capturing positively charged particles; new types of corona electrodes were investigated. It has multi- function of corona discharge, reducing back corona, prevent reentrainment and collect the positively charged particles. Different types and geometries of corona electrodes were proposed; all of them were featured to add a channel shaped wind buffer, which has the same voltage with the corona wire and located between subsequent corona wires. These buffers can reduce gas flow scouring reentrainments, collect positively charged particles and restrain back corona by electrostatic shielding effect. Bench scale laboratory tests were made to explore their discharging characteristics, current density distributions, etc. Two- dimension flow mathematics models were set up and boundary conditions were confirmed. Using k- eequation, the pure air turbulent flow fields of corona electrodes with and without wind buffers were studied.