A four-zone drag model based on cluster for simulating gas-solids flow in turbulent fluidized beds

Abstract Gas-solids drag model is crucial for the accurate prediction of gas-solids flow in turbulent fluidized bed (TFB). A four-zone drag model based on cluster was proposed to describe the gas-solids interactions in TFB. The model considers the cluster effect in the bottom dense bubbling zone while regards the particles as discrete ones in the top dilute dispersed zone. The structural parameter model was used to calculate the equivalent cluster diameter in the drag model. Validations against experiments show that the drag model can accurately simulate the gas-solids flow characteristics in TFBs with Geldart A and B particles. Besides, the non-uniform flow structures resulting from gas voids and particle clusters were successfully captured with the model. Compared with the bubbling fluidized bed, more small bubbles with a more uniform size distribution exist in TFB and the variation of operating conditions has little effect on gas voids characteristics in TFB.