Analysis Of Viscous Particle Filtration Performance Based On PFC And Fluent-EDEM

Particle viscosity in filtration and dust removal significantly affects the structural characteristics of the filter cake and thus the performance of the filtration system.The particle viscosity will change due to the influence of ambient humidity,but the ambient humidity not only affects the particle viscosity,but also the parameters such as particle density and moisture content will change.At present,the simulation of the filter cake structure often focuses on the influence of a single characteristic of the particles,and the difference of simultaneous changes of multiple parameters caused by particle moisture absorption is not considered enough,and the simultaneous changes of surface viscosity and density of the actual particles after moisture absorption equilibrium lack attention.In this paper,the two-dimensional numerical simulation of particle filtration performance based on PFC(Particle Flow Code)calculation program reveals the influence law of environmental humidity on the deposition morphology,porosity and filtration resistance characteristics of filter cake,and explores the influence of parameters such as particle density and rolling resistance coefficient on particle deposition behavior.And a three-dimensional Fluent-EDEM coupled numerical simulation was constructed to explore the effects of different filtration wind speed,surface energy and particle size on the deposition morphology and filtration performance of filter cake,analyze the influence of viscous particles on filter cake deposition performance,and study the law of pressure drop,porosity and filter cake thickness on the change of viscous particles’filtration performance.The study realizes the visualization of viscous particles in the filtration process,which helps to grasp the mechanism of the effect of particle viscosity on the filtration performance.The main contents of this paper are as follows:(1)The formation process of filter cake was numerically simulated by PFC calculation program,and the influence law of relative humidity of air on the deposition morphology,porosity and filtration resistance characteristics of filter cake was revealed.The results show that:the relative humidity is mainly reflected in the density and surface viscosity of the particles,the higher the relative humidity,the higher the moisture content of the particles,the higher the density and the higher the surface viscosity(corresponding to the rolling resistance coefficient in PFC);the higher the density or the lower the viscosity of the particles,the more obvious the bridging phenomenon of particle deposition,the weaker the dendritic deposition phenomenon,which makes the filter cake structure more dense,the smaller the porosity and the higher the total filtration resistance.The porosity of 0.34 and total filtration resistance of 115 Pa for roll resistance factor 1.0 are 1.22 and 2.14 times of roll resistance factor 0.1,respectively.(2)The density and viscosity of different particles vary with the degree of humidity,resulting in different trends in the characteristics of the filter cake formed by different particles with the increase of humidity.With the increase of relative humidity,the porosity of the filter cake formed by PVA1788,polyacrylamide and talc under investigation increased continuously,while the total filtration resistance decreased continuously;the porosity of the filter cake formed by DM828 particles showed a change of decreasing and then increasing,while the total filtration resistance increased and then decreased(at RH=30%,the corresponding particle porosity was the smallest,0.32 The total filtration resistance is 687 Pa).Analysis of the particle filtration performance with the increase in the relative humidity of the environment has three changes(filtering resistance as an indicator,porosity and filtering resistance are inversely correlated):(a)filtering resistance first increases and then decreases,such law corresponds to the particles have hygroscopicity,and high moisture absorption,filtering has reached moisture absorption equilibrium;(b)filtering resistance decreases,the corresponding particles have hydrophobic and not easy to reach moisture absorption equilibrium;(c)filtering resistance increases,the corresponding particles are non-hygroscopic,and their density and viscosity are less affected by humidity.(3)The coupled three-dimensional numerical simulation model of Fluent-EDEM was constructed,and the model parameters were calibrated by the stacking angle experiment;and the particle filtration experimental system was further constructed,and the accuracy of the model was verified by the parameters of filter cake thickness and filtration resistance,indicating that the established simulation method of coupled gas-solid two-phase flow is feasible and can accurately reflect the particle filtration deposition process.(4)The spatial and temporal distribution of the flow field in the filter system during the process of filter cake formation was studied by coupled Fluent-EDEM 3D numerical simulation,and the effects of filtration wind speed,particle viscosity(surface energy),particle size and sphericity on the particle filtration performance were investigated,and the deposition law of particles was analyzed.The analysis found that the filter cake porosity decreased with the increase of filtration wind speed and increased with the increase of particle viscosity and particle size;the pressure drop increased with the increase of filtration wind speed and particle sphericity,and decreased with the increase of particle viscosity and particle size.For particles with a particle size of 10μm and a surface energy of 0.04 J/m~2,0.03 m/s is the optimal filtration air velocity.