A CFD-DEM study of a two-joint spouting flow pattern in a multiple rectangular spout fluidized bed

Rectangular spouted beds were expected to solve the scale-up problem of spouted beds by simply adding chambers. In practice, it is common to insert baffles between different chambers to prevent the interaction of different spouts and keep the symmetrical spouting. However, the interaction of multiple spouts on hydrodynamics is not well understood. Therefore, the present study systematically explored the optimal gas-solid mixing performance with the integrated effect of two spouts in the system. The results show that the two spouts would join together and then deflect alternatively when the distance is within a wide range, specifically, 0.04 m ∼ 0.12 m out of a 0.3 m column width. This flow pattern is termed as two-joint spouting. The two-joint spouting demonstrated a significant advantage in both efficiency and product homogeneity for gas-solid mixing. Compared to conventional spouting, the average particle temperature drop after 20 s was 3.5 °C lower, accompanied by a notable reduction in the standard error of particle temperature, which was only half that observed in conventional cases. These results imply that the two-joint spouting mechanism contributes to a more efficacious heat transfer process and fosters enhanced uniformity in temperature distribution across the bed. This work firstly unveils that the two-joint spouting is favorable for gas-solid mixing and provides a new approach for the scale-up of rectangular spouted beds. [Display omitted] •Two-joint spouting flow pattern is identified in a multiple spout fluidized bed.•Two-joint spouting shows advantages in gas-solid mixing efficiency.•Two-joint spouting has good robustness and wide operation range.•Two-joint spouting flow pattern indicates a new way for scale-up.