Theoretical and experimental study of trapping PM2.5 particles via magnetic confinement effect in a multi-electric field ESP

Abstract

The capture of fine particulate matter (PM2.5) is the central function of dust removal systems in coal-fired power plants. To improve the collection efficiency of multi-electric field electrostatic precipitators (ESPs), a magnetic field was applied to investigate its effect on the dust removal performance of an experimental ESP. Particle image velocimetry (PIV) technology was used to test the effect of magnetic confinement on fluid field distribution and particle trajectory. A numerical model was developed to describe the physical processes occurring in the multi-electric field ESP, including airflow, corona discharge, particle charging and particle dynamics. The effect of magnetic field on the trapping efficiency of PM2.5 under various working voltages was analysed. The PIV experiment and numerical simulation showed that particle trajectories exposed to a magnetic field obeyed the same laws of motion as those not exposed to a magnetic field. The introduction of a magnetic field resulted in more complex spiral movement of particles in the ESP and increased the number of particles deflecting towards the dust collecting plate. Thus, magnetic confinement improved the efficiency of PM2.5 collection in the multi-electric field ESP. Increasing magnetic induction not only improved dust removal to the same extent as that achieved by increasing the voltage but also reduced power consumption. At lower working voltages, weaker magnetic induction intensities or lower collection efficiencies, the magnetic field enhanced the PM2.5 trapping performance more evidently. These results provide a theoretical basis and a technical reference for the design of novel and efficient multi-electric field ESPs to reduce costs and protect the environment.