An improved modelling for prediction of grade efficiency of electrostatic precipitators with negative corona

Generally, an increase of turbulent dispersion coefficient due to negative corona has been thought to be detrimental to the performance of electrostatic precipitators. However, in recent years, the experimental investigations performed with negative corona have repeatedly reported about significantly higher collection efficiencies, particularly, for fine particles than predicted by any known models. In this study, the transport of charged particles in an electrostatic precipitator is investigated by numerical solution of the convection/diffusion equation, which takes into account the effects of a fully developed turbulent flow profile, a simple profile for turbulent dispersion coefficient, and a zero-concentration boundary condition at the collecting wall. It is found that the increase of turbulent dispersion coefficient leads to the increase of collection efficiencies of fine particles with small migration velocities in the early stages of collection process. The collection efficiencies of fine particles predicted by the present model are in good agreement with the experimental data of Riehle and Löffler (Powder Technol. 77 (1993) 201) at a turbulent core dispersion coefficient of 50 cm2/s.