Experimental Study Of Honeycomb Experimental-scale Wet Electrostatic Precipitator Removing Coal-fired Fine Particulate Matter

Electrostatic precipitators(ESP)are widely used in coal-fired power plants for flue gas purification.Since their collection efficiencies of particulate matters,especially on the fine particulate matters,are relatively lower,it is difficult for power plants to meet the current domestic flue gas emission standard.Wet electrostatic precipitator(WESP)can avoid re-entrainment and back corona and achieve a higher control efficiency with wet scrubbing system instead of traditional rapping methods.The mechanism study on wet electrostatic precipitation is help for exploring the dust particle removal method and providing guides for the design and optimization of wet electrostatic precipitators in the engineering applications.This paper studied wet electrostatic precipitator discharge characteristics and experimental methods removing fine flue gas particles which includes the following three parts.The first part was related to the particle removal mechanism of wet electrostatic precipitators.It mainly introduced the fine particles charged and collecting laws in electrostatic field and the interaction between dust particles and droplets,dust particles and dust particles,which would provide guidance for the experimental study of WESP removing fine particles.The second part focused on the discharge characteristics of WESP under different conditions,including dust cleaning methods,discharge electrode shapes,flue gas dust concentration.The results showed that there was little discharge characteristics difference between the dry cleaning method and the overflow method,but the increasing spray amount made the corona current increase to a certain extent.Under the same operating voltage,the corona current of twelve-angle star discharge electrode was the strongest in the three shapes of discharge electrode and the corona current of six-angle star discharge electrode was secondly.The increasing the flue gas dust concentration made the number of charged dust particles increase,which causes the reduction of free electrons and ions number and make the corona current decrease.The third part studied collection efficiency of fine particles by the WESP on different conditions,such as dust cleaning methods,operating parameters,WESP parameters and power supply voltages.The instrument DGI was used to measure size distribution and dust concentration of particulate matters.The results showed that particle removal efficiency with the spray cleaning method was the highest and followed by the overflow cleaning method.Increasing specific collection area(SCA)and applied voltage can both improve the particle collection efficiencies.When the applied voltage is 18 k V,the collection efficiency increased from 79% to 92% with the increase of specific collection area.It can be found that particles of size 0.5?m-1?m diameter are removed less efficiently from the particle grade efficiency curve.When the particle concentration in the flue gas reached a high value(442.85mg/m3),the wet electrostatic precipitator still showed an excellent collection performance.