High-efficient removal of airborne oil mist in a wire-plate electrostatic precipitator

Abstract

Electrostatic precipitators (ESPs) are widely used by machining industries to remove oil mist due to the high efficiency, low pressure drop and low energy consumption. In this paper, the effects of oil mist concentration, relative humidity and oil film thickness on the collection efficiency of ESPs were studied. The experimental results showed that discharge current and collection efficiency both decreased with increasing oil mist concentration, and the collection efficiency of fine oil droplets decreased more obviously than that of large-size oil droplets. When the oil mist concentration increased from 100 mg/m3 to 300 mg/m3, collection efficiency of oil droplets with a size of 0.33 μm dropped from 87.13% to 73.53%, while the efficiency for the droplet size of 1.25 μm only dropped from 90.7% to 84.1%. Increasing the relative humidity caused a considerable decline in discharge current due to the decrease in ion mobility, but an appropriate increase in humidity was conducive to the improvement of collection efficiency. The stable status of oil film thickness on electrode plate was obtained (about 10 μm in the current study), and the stable current density decreased almost 11% due to the oil film. Compared with the oil droplets deposited on the electrode wires, the oil droplets deposited on the plate caused more decrease of collection efficiency of ESPs. The decrease in collection efficiency effected by the electrode plate with oil film was twice that of the electrode wires with oil contamination.