Effects of inlet particle concentration on the separation performances of a novel FCC riser termination device

摘要

Vortex Quick Separation system (VQS) is a novel FCC riser termination device developed by China University of Petroleum (Beijing), China. Through experimental study, the effects of inlet particle concentration on the separation performances of VQS were investigated. According to the experimental results, the separation efficiency increases and the pressure drop decreases with the increase of inlet particle concentration. The causes of above effects were analyzed by numerical simulation. The gas-solid flow field in VQS was numerically simulated by the use of Reynolds Stress Model (RSM) and Discrete Particle Model (DPM) on the Fluent 6.1 platform. The simulated results are in good agreement with the experimental results, which show the validity of the CFD model. The simulated results show that the gas tangential velocity in outer vortex area decreases with the increase of inlet particle concentrations, which indicates that the particles weaken the vortex energy and swirl intensity of gas phase, and consequently cause the decrease of pressure drop. At the same time, particle sedimentation is strengthened with the increase of inlet particle concentrations, so the upward axial velocity of particle entrainment in inner vortex area becomes lower and the downward axial velocity in outer vortex area becomes higher, which are help to improve the separation efficiency of system. In addition, the turbulent intensity decreases obviously with the increase of inlet particle concentrations and it is help to diminish the particle entrainment and improve the grade efficiency of fine particles in VQS.