Numerical studies of the influence of particles' size distribution characteristics on the gravity separation performance of Liquid-solid Fluidized Bed Separator

A new CFD model for Liquid-solid Fluidized Bed Separator (LSFBS), namely the Eulerian-Eulerian-Lagrangian/RNG k-ε approach, was put forward and validated. According to the simulated separation results of two cases, the root-mean-square error (RMSE) between predicted partition numbers of all density fractions and corresponding experimental values were 2.47 and 2.83 respectively, demonstrating the CFD model was able to give accurate simulation results. The Rosin-Rammler model was used to describe the size distribution characteristics (SDC) of the feed, with the parameter Dx and n describing the fineness and particles size variation of the feed respectively. Single-factor tests and central composite design were then developed and simulated using the CFD model to investigate the influence of the two aspects of SDC on the separation performance of LSFBS based on density. The simulated separation results indicate that the finer the feed is, the greater the separation density (δ50) and Ep value are; the smaller the particles size variation is, the smaller the δ50 and Ep value are. According to the response surface analysis, the influence of feed fineness on δ50 is larger than that of particles size variation while the influence of feed fineness on Ep is smaller than that of particles size variation; the interactive effect between these two factors has a noteworthy influence on Ep but insignificant influence on δ50.