Analysis of the purification processes of exhaust gases in a plate electrostatic precipitator taking into account particle entrainment from electrodes

Abstract

The purification of smoke emissions from ash in the plate electrostatic precipitators is mainly determined by charging, motion and precipitation of the particles in the corona discharge field (“direct” precipitation) and processes of discharge of the already precipitated particles back to the gap (reentrainment). The final processes are studied in a significantly less degree and this limits the possibility to calculate the operation efficiency of the electrical precipitator. The absence of the clear ideas of the physical processes during the reentrainment became the basis for development of methods of calculation using the test results of the industrial units. The representation of the degree of purification and slippage of the particles in the form of the exponential dependence made it possible to specify the relation between the operation conditions of the electrical precipitators and gas purification parameters. A significant role of the ash layer formation on the collecting electrodes is noted; a physical-mathematical model of the processes related with the particlelayer growth and discharge of particles from the electrodes to the hopper is proposed. Analysis is carried out of the electrical forces, which, along with the forces of gravity, cohesion, and adhesion, being about violation of layer stability. The analysis starts with the simplest case of behavior of the particle layer during a sudden switching-on of the field. The processes in the plate electrical precipitators are then considered.