The Application Of Wet Electrostatic Precipitator In The Purification Of Tail Gas From Fiber Drying

Exhaust emissions produced during the drying process of fiberboard manufacturing,including particulate,fine fiber,dust（including formaldehyde）.Dry cyclone separator is used commonly for separating and dust removal,which is limited by cyclone separator production accuracy,raw material structure and fiber quality grade.There is still a certain number of fine short fiber and dust can not be separated and removed,so that the exhaust emissions do not meet the national comprehensive emission standards for atmospheric pollutants.In order to further enhance the dust removal efficiency of fiber drying tail gas,especially for fine particles,the tail gas treatment system of a fiberboard plant in Wenan County,Hebei Province was studied in this paper.The effects of water curtain dust removal and adding test scale wet electrostatic precipitator on the removal efficiency of particulate matter were tested and compared.The results are as follows:（1）The removal efficiency of the water curtain dust removal equipment（the spray tower）can reach 85.8%,and the removal effect of the particles with particle size above 5μm is higher.After treatment,the concentration of water mist in the tail gas has increased,which needs further treatment and then discharged into the atmosphere.（2）When the electric field wind speed is controlled in the range 1.0～1.2 m/s,the removal efficiency of particulate matter of the dust collector can reach about 95%,and it can meet the requirement of gas flow rate;the working voltage can be controlled at about 30 k V,and when the working voltage is increased,the rising trend of the removal efficiency of particulate matter becomes slower;when the air flow temperature of the dust collector is higher than 60℃,the removal efficiency of particulate matter increases with the increase of temperature;continuous spray washing can improve the removal efficiency of particulate matter,but the amount of spray is higher than 30 m3/h may have the opposite effect.（3）Venturi nozzle was designed before the wet electrostatic precipitator.The effect of overflow and spray flushing on the removal efficiency of dust particles was analyzed by experiments.（4）Efficiency of removing PM_2.5、PM₁₀and fine particles by wet electrostatic precipitator is 69.89%,93.02%and 94.19%,respectively.Compared with water curtain dust removal,the removal efficiency of fine particles with particle size less than 5μm is greatly improved.