Analysis of Collection Efficiency in Wire-Duct Electrostatic Precipitators Subjected to the Applied Magnetic Field

摘要

This paper describes a strongly coupled calculation procedure for the particle dynamics in electrostatic precipitators (ESPs) subjected to the applied magnetic field with the statistical particle size distribution taken into account. The turbulent gas flow and the particle motion under external forces are modeled by using the commercial computational fluid dynamics code FLUENT. Numerical calculations for the gas flow are carried out by solving the Reynolds-averaged Navier–Stokes equations, and the turbulence is modeled by using the turbulence model. An additional source term, which is obtained by solving a coupled system of the electromagnetic field and charge transport equations, is added to the gas flow equation to capture the effect of the electromagnetic field. The particle phase is simulated by using a discrete phase model. Different kinds of particles which follow the Rosin–Rammler distribution were simulated under different conditions, and the influence of the magnetic field density on the capture of a fine particle was investigated. In order to show the dust removal effect, the collection efficiency and the escaped particle size distribution were discussed in case of different applied magnetic fields. The particle trajectories inside the ESP were also given under the effect of both aerodynamic and electromagnetic forces. Numerical results in the wire-duct ESP show that the collection efficiency increases with the increase of the applied magnetic field, that the particle trajectory is more visible to the direction of the dust collection duct, and that the collection efficiency varies smoothly when the absolute value of the applied magnetic field trends to a certain size. Furthermore, the average diameter of escaping particles decreases and the dispersion for dust particles in different sizes increases with increasing applied magnetic field, and particle sizes are linearly decreasing with the magnetic field before the particle diameter is up to-n-n a certain size.