A Numerical Simulation Of The Flow Field In A Catalytic Cracking Cyclone Fast Separation System

In this paper,the CFD method is used to simulate the internal flow field of super vortex quick separation system(SVQS)for catalytic cracking unit to deeply analyze the internal flow field characteristics.The influence of operating parameters on its separation performance are systematically studied,and the dimensions of the device are optimized,which provided a theoretical reference for the design and operation optimization of SVQS.By comparing the calculated results with the measured values,the Reynolds stress transport model(RSM)is used to simulate the gas phase flow field.And Discrete Random Walk model is used to simulate the solid phase.The simulation results show that the flow field of the ejection segment and the separation segment of SVQS is presented as a "double vortex" flow and the tangential velocity is dominant.The distribution of flow field in gas outlet section is disordered,and vortices are easily produced.The centrifugal force and the inertia of large size particles are larger,and the trajectories of large particles are longer,which can be easily captured by solid phase exit.Trajectories of small particles are highly random,which are easy to be entrapped by upward flow to the gas outlet,even be brought to the exit of the vortex head to enter the next separation circular loop,resulting in the low separation efficiency of fine particles in SVQS.In addition,the influences of the squirting speed of the vortex head,the mass concentration of the inlet particles and the wall roughness on the performance of SVQS are studied.And the structure optimization of the fast subsystem is carried out.According to the optimization scheme,the pressure is calculated and analyzed,and the optimized structure calculation is in good agreement with the experimental results,which can provide reference for the engineering design.