Fine particle removal by a two-stage electrostatic precipitator with multiple ion-injection-type prechargers

Abstract

A novel two-stage electrostatic precipitator (ESP) with multiple ion injection type chargers and parallel collection plates was developed and shown to efficiently collect particles from the corrosive waste gas discharged from semiconductor and optoelectronic processes. Multiple carbon brush electrodes for the generation of ions were located outside of the main gas flow, but the injection of clean air and induced voltage between the outer and inner plates of the charging stage carried ions into the main gas flow; thus, gases and particles in the main flow did not corrode or contaminate the charger. The particle collection performance of the ESP was evaluated experimentally for 0.3 μm particles, PM (Particular matter) 10, and PM 2.5 by varying the application voltages to the charging stage, main gas flow rate, and distance of the carbon brush discharge electrode from the main gas flow duct. The novel ESP achieved particle collection efficiency of 89.5% and 99.5% at the best condition when the voltage was applied to only the charging stage and to both the charging and collection stages, respectively. The particle collection efficiency of the charging stage only and the two-stage ESP was characterized according to the corona discharge power and main flow rate based on Deutsch's collection theory. Also, a simplified 2D simulation results show that the electric field is very high not only near outer carbon fibers but also near the outer metallic electrode edge.