Study On Desolidification Performance Of FCC Slurry Under The Coupling Action Of Electric Field And Flow Field

The presence of catalyst particles in the fluid catalytic cracking slurry(FCCS)affects the secondary utilization and advanced processing of the catalytic oil slurry.Therefore,it is necessary to desolidify the FCC slurry to produce high value-added products.At present,the commonly used desolidification methods are sedimentation separation method,filtration separation method,centrifugal separation method and electrostatic separation method.Because the catalytic cracking oil slurry has the characteristics of high viscosity,high density and poor fluidity,and most of the catalyst particles have a particle size of less than 10 μm,it is suitable for the purification of FCC slurry by electrostatic separation.Based on the COMSOL finite element analysis software,this paper simulates and analyzes the factors that affect the electrostatic desolidification performance of FCC slurry under the coupling action of electric and flow fields.And use the self-made electrostatic separation device to conduct experimental research,which provides a theoretical reference for improving the electrostatic separation efficiency of catalytic cracking oil slurry.In this paper,three factors that affect the efficiency of electrostatic desolidification of catalytic cracking oil slurry are studied: electric field characteristics,flow pattern and packing method.Firstly,a combination of numerical simulation and experiment is used to study the influence of packing method on separation efficiency.Based on the "effective contact point" model proposed by the research group,the parameter η is derived,and the size of η is solved by the formula to determine the adsorption capacity of the separation unit to particles under different stacking methods.The packing is arranged according to four stacking methods: simple cubic stacking,body-centered cubic stacking,hexagonal closest stacking and face-centered cubic stacking.The separation efficiency under the four separation units is obtained through simulation and experiment,and the change trend of the theoretical value of η obtained by the formula is the same,and the results show that the hexagonal closest stacking and the facecentered cubic stacking have better separation performance among the four stacking methods.Secondly,conduct a numerical simulation study on the electric field characteristics.The results show that as the arrangement angle of the filler balls increases,the polarization charge density at the contact point decreases,the polarization electric field weakens,and the adsorption effect on the catalyst particles becomes worse.When the applied voltage is constant,the adsorption capacity of the applied non-uniform electric field to particles is stronger than that of the uniform electric field.The cylindrical inner electrode generates a larger average electric field strength than the prismatic inner electrode,so the separator using the cylindrical inner electrode has higher separation efficiency.Finally,the influence of flow pattern on separation efficiency is simulated and analyzed.Since particles are subject to large drag in the moving flow field,the separation efficiency of particles in the moving flow field is lower than that in the static flow field.The drag force of particles in the flow field of anti gravity direction is less than that in the flow field of gravity direction,so the separation efficiency of particles in the flow field of anti gravity direction is higher.The particle velocity formula in each flow field is obtained by solving the motion equation of particles.It is found that there is a positive correlation between particle velocity and drag force in static flow field and there is no correlation between particle velocity and force in unidirectional flow field.The particle separation efficiency increases with the increase of applied voltage in each flow field,and decreases with the increase of inlet velocity in moving flow field.