Hydrodynamic modeling of an industrial turbulent fluidized bed reactor with FCC particles

This study presents a CFD modeling of the hydrodynamics in an industrial turbulent fluidized bed reactor with FCC particles. Considering the mesoscale structure of particle clusters and the impact of reactor temperatures, a gas-solid drag model based on the equivalent diameter of particle clusters is proposed. A CFD model is developed, the model parameters are evaluated, and the gas-solid flow behaviors are explored. Compared with the conventional drag models, the proposed model gives a reasonable hydrodynamic prediction in the industrial turbulent fluidized bed reactor. The hydrodynamics show more sensitive to the drag models than to the flow types, the kinetics theories and the restitution coefficients. There exist two coexisting flow regions in the industrial turbulent fluidized bed: a bottom dense, bubbling region and an upper dilute, dispersed flow region. Moreover, the bed density in the dense phase is much lower than those in the cold experiments. In the dilute phase, particles ascend in the center and descend near the wall, showing a core-annulus flow. In the bottom dense phase, some vortex flows appear, leading to the non-uniform distribution of particle velocity and solid holdup. With increasing the superficial gas velocity, the bed surface rises; and the bed density decreases in the bottom dense phase and increases in the upper dilute phase. (C) 2016 Elsevier B.V. All rights reserved.