Simulation Study On Single Droplets Trapping Micron And Submicron Particles Under Electrostatic Field

In recent years,with the continuous implementation of environmental protection policies,the emission standards for particulate matter from coal-fired sources have been close to or equivalent to gas standards.In order to achieve ultra-clean emission of particulate matter from coal-fired boilers,wet electrostatic precipitators are widely used as terminal treatment equipment.However,they have the disadvantages of uneven water distribution,reduced dust removal efficiency due to corona suppression,and poor economic efficiency due to cost and maintenance costs.On the basis of wet dust removal,upgrading the droplets,which play a major role in cleaning dust collection,into charged mobile traps can effectively make up for the above deficiencies.Under this principle,this paper conducts a simulation study on the process of trapped particles by charged droplets in a turbulent field,which can lay a theoretical foundation for the further application of this technology.First,for spherical particles,this paper selects the standard k-? turbulence model and SIMPLE algorithm,and uses the user-defined function(UDF)to add the Coulomb force to simulate the particle migration behavior and the deposition distribution on the surface of the charged droplets.Secondly,for non-spherical particles,establish the relationship between particle shape and sphericity,and study the effect of particle shape on the collection efficiency.At the same time,the changes of parameters such as shape,particle charge and particle size during particle aggregation are considered,and the effect of particle aggregation on the collection efficiency is studied.For spherical particles,the research results show that the efficiency of charged droplets to capture micron spherical particles is positively correlated with particle size,particle charge and droplet charge,and the relationship with particle motion speed also needs to consider the effect of particle size;The efficiency of capturing submicron particles is negatively correlated with particle size and particle velocity,and positively correlated with particle charge and droplet charge.The results show that the efficiency of charged droplets to capture micron spherical particles is positively related to the sphericity.The closer the particle shape is to the spherical shape,the higher the collection efficiency.Particle aggregation within a certain range of particle motion speeds helps to improve the collection efficiency;The effect of particle aggregation on the collection of submicron spherical particles is negative,that is,particle aggregation will reduce the collection efficiency.Through simulation studies,the following conclusions can be drawn: Increasing the charge of particles and droplets can increase the Coulomb force and improve the collection efficiency of particles;Increasing the sphericity of particles of equal volume can reduce the drag force on them and improve the collection efficiency;Particles ofdifferent sizes have different inertial forces,and only in a certain range of particle movement speed can they have a high collection efficiency.