Numerical Simulation Of Bipolarly Charged Electrostatic Precipitator For Collecting Inhalable Particles

Purification of inhalable particles is one of worldwide hot issues. To research and develope an efficient feasible inhalable particles removal technology is of great significance. One of the important increasing sourses of inhalable particles in atmosphere environment is the coal combustion of boilers, and there is no mature countermeasure at home and abroad presently. The mass collection efficiency of traditional electrostatic precipitator(ESP) is up to 99%, but right inhalable particles capture rate is relatively lower. The main reason for this is that the size of inhalable particles is too small, resulting in a poor charge capacity, so the electric field is difficult to capture them. At present, a theory of efficient removal method is using particles agglomeration properties to let inhalable particles agglomerate and grow into larger particles, and then indirectly achieve inhalable particles removal.With the agglomeration energy consumption ratio, the complexity of agglomeration process,the availability of secondary pollution, and other aspects considered, electrostatic agglomeration is the most feasible agglomeration way. Based on the comparative study of a variety of electrostatic agglomeration mechanisms, this thesis considers the feasibility of the current numerical simulation, finally selects a three-stage electrostatic precipitator that combines with agglomeration device of bipolarly charged particles without external electric field as the simulated targets, and gives the kernel function models of the events of electrostatic agglomeration and deposition.Using ESP and flue gas parameters from a typical coal-fired boiler as initial conditions, this thesis adopts the event-driven constant volume method(EDCV) and the selected kernel object models to carry out the numerical simulation. According to the simulation results, the effects of three factors on collection efficiency are discussed, which include the electrical agglomeration device,the electric field strength in dust collection stage and the horizontal average flow velocity. The conclusion shows: ESP that combines with an electrical agglomeration device remarkably improves the collection efficiency of inhalable particles, and the collection efficency of submicron particles gets to 92%, which increases about 10%; the increase of the electric field strength and the decrease of the horizontal average flow velocity will improve the collection efficiency.