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© 2021 American Chemical Society.Spout–fluid beds are widely used in the process industry due to their facilitation of an efficient contact between particles and gas. In this paper, a two–fluid model (TFM) is set up to reproduce the various flow structures encountered during spout–fluid bed operation. The effects of normal restitution model and gas–solid drag model are assessed by comparing simulation results with the experimental and discrete particle modeling (DPM) data of Link et al. [Link et al. Chem. Eng. Sci. 2005, 60, 3425–3442; Link et al. AIChE J. 2008, 54, 1189–1202.]. Simulation results show that application of an effective restitution coefficient in TFM can improve the accuracy of prediction significantly. The drag model of HKL predicts a more reasonable result than models of Huilin–Gidaspow, BVK, and Syamlal and O'Brien. Analysis on relative contributions of kinetic motion, friction, and collision to particle–particle momentum transfer parameters, namely, particle pressure and viscosity, shows that particle–particle momentum transfer in the spout and fountain regions is dominated by kinetic motion and that in the annulus region is dominated by friction. A transition region between spout and annulus regions is proposed. This region can be delineated using a single parameter of dimensionless collisional particle pressure because in this region, particle pressure is dominated by the collisional contribution. With an increasing spout–fluid ratio, the stable spout–annulus–fountain structure gradually shifts to an unstable bubble–slug structure. The effect of collision increases and extends to the entire bed. Meanwhile, the effects of kinetic motion and friction decrease. When slugs are formed, a rebound in the influence of friction is observed, accompanied by a decrease in the influence of collision.
