Numerical Simulation Of Microparticle Movement And Capture In Electrostatic Precipitator Under The Coupling Of Electric Field And Flow Field

With the rapid development of social industrialization and the improvement of people’s living standards,the quality of atmospheric environment has improved in recent years,but more than 50% of the urban environmental quality is not up to standard.Chinese coal-fired power plants are the main source of particulate pollutants emissions.In coal-fired power plants,electrostatic precipitator(ESP),as a common device for removing particulate pollutants,has an important impact on the capture of micro-particles.Therefore,it is a hotspot and difficulty to actively explore and improve the collection efficiency of ESP for micro-particles.The charging level of particles and the state of airflow have important influence on the trapping of micro-particles in ESP.The numerical simulation method is an important means to visualize the gas-solid coupled flow and particle motion in ESP.In this paper,the user-defined function(UDF)in Fluent is used to couple the electric field,the flow field and the micro-particles motion field in the electrostatic precipitator.By establishing a three-dimensional numerical model,the laws of charge,movement and collection efficiency of micro-particles in ESP under diffusion charge are simulated,and the influence of various factors on the collection efficiency of ESP is analyzed in detail.The results show that:(1)In the range of particle size distribution from 0.05μm to5μm,the dust collect efficiency of ESP decreases first and then increases.There is an obvious penetration window at 0.1μm～1μm,the comprehensive charge effect is the weakest.The ESP has the lowest dust removal efficiency in the range of particle size,and the lowest value is the dust removal efficiency value of 42.2% of the 0.5μm particle size.(2)With the increase of particle size(0.05μm～1μm),the action intensity of diffusion charge on fine particles shows a non-linear downward trend.For particles with particle size less than 0.1μm,the effect intensity of diffusion charge is above 25%.The smaller the particle size,the greater the action intensity.When particle size is larger than0.8μm,the action intensity of diffusion charge tends to zero,the minimum value is0.12% for 1μm particle,and the effect of electric field charge on dust removal efficiency of particles is greater.For the same particle size,the larger the wind speed of electric field,the lower the applied voltage,the greater the influence of diffusion charge on fine particles,the lower the dust collect efficiency.(3)In the range of particle size distribution from 0.1μm to 1μm,two different flow patterns,uniform flow and skew gas flow,were compared.The flow pattern has a great effect on the efficiency of particle dust removal,the dust collect efficiency of skew gas flow is better than that of uniform flow,and the difference between the two can be about 3%;With the increase of wind speed and applied voltage of electric field,the intensity of particles charge on the collect efficiency of micro-particles is larger than that of the flow pattern,and the dust collect efficiency of the two types of skew gas flow and uniform flow is basically the same.