| Catalytic slurry can be used to produce high value-added products such as needle coke,carbon black,carbon pole materials,etc.It can also be used as high-quality raw materials such as asphalt modifier,intensifier,heat conducting oil and so on.It has very high comprehensive utilization value.However,the existence of catalyst particles in slurry restricts the high-value utilization of slurry,and the removal of catalyst particles becomes the key to achieve high-value utilization of slurry.At present,the commonly used FCCS desorption methods include gravity settling,filtration separation,cyclone separation,centrifugal separation and electrostatic separation.Among them,the electrostatic method for FCCS desorption has the advantages of high separation efficiency,large processing capacity,low pressure drop,especially suitable for separating small particle size or low solid concentration,and has certain advantages compared with other desorption methods.At present,there are still some deficiencies in the study of FCCS desorption by electrostatic method,especially in the study of numerical simulation.In this paper,a set of electrostatic separation device is designed and built based on the mechanism of electrostatic separation.The separation process of the device is simulated by COMSOL software,the separation efficiency of the electrostatic separator is studied by numerical simulation and experiment.The separation efficiency of electrostatic separator is studied macroscopically,and the distribution characteristics of electric field and particle motion behavior in the device are studied mesoscopically,which provides a theoretical basis for future industrial applications.Through the numerical simulation of the electric field inside the device,it is found that under the condition of complete polarization of the filler,changing the voltage will not affect the non-uniformity coefficient of the electric field,but at the same position in the device,the divergence of the square of electric field intensity and the electric field intensity are positively correlated with the voltage;most of particles are adsorbed near the contact point of the filler,and some fillers do not have adsorbed particles at their contact points.Based on this phenomenon,an "effective contact point" model is proposed as a criterion for whether the contact point can achieve the purpose of adsorbing particles.Through the numerical simulation of particle motion behavior,it is found that with the increase of the radial distance between the particle and the central electrode,the particle trajectory will change,the dielectrophoresis force of the particle will weaken,and the influence of gravity and drag force on the particle motion will be enhanced.The velocity expression of the particle is obtained by solving the particle motion equation,and then the qualitative characterization device is obtained.The results show that the particles can be separated completely theoretically when the dielectrophoresis force is large enough.The influence of structural parameters on separation performance was studied by means of experiment and simulation.It was found that the separation efficiency decreased with the increase of packing diameter.Among the four stacking modes of hexagonal closest stacking,face-centered cubic stacking,body-centered cubic stacking and ordinary cubic stacking,the separation efficiency of face-centered cubic stacking was the highest,which was due to porosity and the number of effective contact points.” Within a certain range,the separation efficiency decreases first and then increases with the increase of inner electrode diameter.The results of this study will provide a theoretical basis for optimizing the structure of electrostatic separator and improving the separation efficiency. |
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