Effect of charged water drop atomization on particle removal performance in plate type wet electrostatic precipitator

Abstract

In this study, a lab-scaled wet electrostatic precipitator (WESP) was designed to investigate the particle removal with atomization of charged water drop, instead of traditional water film and mechanically atomized spray. The removal performance was comprehensively evaluated via experiments with controlled applied voltage, gas residence time, dust concentration and continuous operation time. The results demonstrated that supplying the charged droplets enables the WESP to achieve higher discharge current and removal efficiency than the dry type. The minimum removal efficiency of the WESP was elevated to 91.69%–95.88% from 91.52% – 93.89% of the dry ESP, as the electric field intensity increased from 2 kV/cm to 5 kV/cm. The coupled effect of the longer residence time and higher applied voltage significantly improved the grade removal efficiency in the WESP, which increased from 91.86%-95.36% to 97.86%–98.89% as they were enhanced from 2.14 s and 2 kV/cm to 4.04 s and 5 kV/cm, respectively. The removal efficiency first increased and then decreased as the dust concentration increased, while the efficiency drop at high dust concentrations could be effectively improved by prolonging gas residence time. Moreover, injection of charged droplets could also keep the advantage of improving removal efficiency over the dry ESP under continuous operation, and the decrease in removal efficiency after a certain operation time could be largely avoided by applying higher voltage. Particularly, the atomization of charged water drop in the current WESP significantly reduced water consumption, meanwhile maintaining the removal efficiencies at a level comparable with traditional water treated processes.