Experimental Study On Coagulation And Collection Of Fine Particle In Wet Electrostatic Precipitator

Coal is the primary energy source in China.However,the flue gas emitted from coal-fired power plants contains a large amount of fine particles,which is a major source of fine particulate matter pollution in the air,especially harms to the human.Currently,the electrostatic precipitation can not effectively control the emission of fine particles,because ion wind generated during corona discharge will cause strong motion of fine particles in ESP,the fine particles move circularly between the plates in the role of large vortices and are not easily captured.In order to solve the problem,a new technology by using the charged droplets and chemical agglomeration to improve the collection efficiency of the fine particles is proposed in this article.Firstly,the physical and chemical properties of the fly ash were analyzed.Secondly,experiments of charged droplets were carried out by changing water pressure,particle size of droplets,surface tension of the water and so on,and the chemical agglomeration experiments were carried out by changing chemical agglomeration agent type,concentration,pH value and other factors on the effect of chemical agglomeration.Finally,the dust collection experiments were carried out by WESP.The results show that:（1）Dust from Coal-fired power plant is mainly loose spherical particles and irregular bulk.The dust is mainly composed of SiO₂,Al₂O₃ and other oxides with a geometric median diameter of 17.87μm.（2）In WESP,when the water pressure is 0.4MPa,the coagulation effect of the fine particles is the best.（3）When the other conditions are the same,the particle size of the dust increases with the the droplets diameter increases,the major geometric median diameter is 38.59μm.（4）Carboxymethyl Cellulose and xanthan gum have the best coagulation effect on the fine particles of several kinds of chemical agglomeration agents.The fine particles agglomeration effect gets better as the agglomerant concentration increases.Reducing agglomeration solution pH promotes the coagulation effect of fine particles.（5）The highest collection efficiency can reach 99.76%when chemical agglomeration agents added.The experimental researches above show that application of charged droplets and chemical agglomeration technology to wet electrostatic precipitator can improve the collection efficiency of fine particles,and can effectively control the smission by the coagulation of fine particles.