CFD simulation of gas solid flow in FCC strippers

In this paper, the hydrodynamic characteristics in bubbling fluidized beds (FCC Strippers) were simulated by using computational fluid dynamics (CFD) code (Fluent 6.2.16). The modified Gidaspow drag model based on the effective mean diameter of the particle clusters predicted the expected bubbling fluidization behavior and bed expansion. Compared with the bed densities of 650–900kg/m3 in the empty-cylinder stripper, bed densities in the V-baffled stripper were 600–800kg/m3 at the superficial gas velocity of 0.10–0.20 m/s. The overall trend of the time-averaged bed density at various superficial gas velocities were in agreement with the experimental data. The results illustrated that internal baffles had an important effect on the fluidization hydrodynamics. Internal baffles improved break-up and redistribution of bubbles and intensified the gas–solid contact. The simulation results also indicated that appropriate modification of the internal configuration eliminated the dead flow region in the strippers, and enhanced the gas–solid mixing remarkably, showing benefit for the mass and heat transfer in the fluidized bed.