Numerical simulation on the fine particle charging and transport behaviors in a wire-plate electrostatic precipitator

Abstract

In this work, an integrated numerical model is presented and validated to investigate the particle charging and transport behaviors in a wire-plate electrostatic precipitator (ESP). Calculations of gas flow, electrostatics field and particle motions are coupled in the model, and the influences of electro-hydrodynamics (EHD) flows are also taken into account. The dynamic charging process of particles was treated with separate field and diffusion charging rates, and the trajectories of particles in the ESP were tracked with a Lagrangian-type method. Numerical results show that electric field strengths and charging ion densities varied largely in the computational domain, and inlet particles were initially charged primarily by diffusion charging mechanism. The particles were then charged to a near-saturation state in the discharging zone, while their transverse velocities showed considerable fluctuations along the trajectories. Numerical results indicate that particles with diameter between 0.2 and 1μm normally exhibited lowest average transverse velocities, and longer residential time could slightly improve the transverse velocities for all sizes of particles. Moreover, increasing voltages could greatly improve the acquired charges and collecting performances for particles larger than 1μm, while higher ion current value was more effective in achieving higher collection efficiencies for sub-micron particles.