3D CFD-PBM modeling of the gas–solid flow field in a polydisperse polymerization FBR: The effect of drag model

Abstract

This work investigated a coupled computational fluid dynamics and population balance modeling (CFD-PBM) approach to predict the hydrodynamic behavior of the complex gas–solid two-phase flow in a three-dimensional (3-D) polydisperse propylene polymerization fluidized bed reactors (FBRs). Four different drag models, namely Syamlal–O’Brien, Gidaspow, McKeen and EMMS, were incorporated into the CFD-PBM model for evaluating the different effect of drag force between the gas and solid phases. Simulation results revealed a significant effect of the drag model on gas–solid flow in polydisperse polymerization FBRs. It was found that (1) compared to Syamlal–O’Brien and Gidaspow drag models, McKeen and EMMS drag models could predict a lower bed height, a higher temperature and an obvious core-annulus structure in polymerization FBRs; (2) EMMS drag model outperforms the other three drag models with respect to pressure drop prediction; and (3) the drag coefficient had little influence on the evolution of Sauter number and particle-size distribution.