Ultrafine Particle Collection Performance of a Two-Stage ESP With a Novel Mixing-Type Charging Stage Using Different Geometries and Electrical Conditions

Abstract

We improved the two-stage electrostatic precipitator (ESP) developed for information technology manufacturing with highly corrosive and explosive gases by adding a novel mixing-type charger to generate unipolar ions outside of the gas duct and inject them into the main gas flow using an additional electric field. The charging stage (100 × 100 × 400 mm3) is composed of a brush-type charger located outside of the upper part of the charging stage and two parallel plates with an additional electric field. Downstream of the charging stage is a typical collection stage with parallel plates and a collection area of 0.1 m2 at 50 L/min. Electrical and particle removal characteristics of the ESP were evaluated using ultrafine particles and varying the thickness, hole size, and electrical connections in the charging stage. The total air flow rate in the ESP during tests was approximately 50 L/min, with a 10:1 ratio of the main and mixing flows. Using our novel mixing-type charging stage and electrical connections, a high voltage of −5 kV was applied between the brush charger and the grounded upper plate, and a positive high voltage was applied to the lower plate in the charging stage. Collection efficiency ranged from 20% to 90% of 60 nm particles over a wide range of electrical potentials between the upper and lower plates of 0–15 kV.