New structure-based model for Eulerian simulation of hydrodynamics in gas-solid fluidized beds of Geldart group “A” particles

The well-documented inaccuracy of conventional two-fluid modeling of hydrodynamics in fluidized beds of Geldart Group A particles is revisited. A new force-balance (FB) sub-grid-scale model, applied to the conventional Wen-Yu drag correlation, analyzes the balance of van der Waals, drag, gravity and buoyancy forces. It predicts formation of agglomerates inside the bed, updating the drag calculations by applying a correction factor to the conventional drag models to account for agglomerate formation. Good predictions were obtained of fluidization regimes and bed expansion, and there was promising agreement with experimental time-average radial voidage profiles reported by Dubrawski et al. (2013). Good quantitative agreement between DEM and two-fluid predictions of minimum bubbling velocity was also observed when the model was used to predict minimum bubbling velocity, in contrast to the predictions from a non-cohesive, Wen-Yu model. Further evaluation studies are required to test the ability of the new model to predict the properties of larger-scale fluidized beds.