Effect of ring baffle configurations in a circulating fluidized bed riser using CFD simulation and experimental design analysis

Abstract The non-uniformity of solid particle distribution in a circulating fluidized bed riser is an important problem for this type of reactor, since it leads to a poor system mixing and low chemical reaction conversion. The aim of this study was to explore the effect of ring baffle configuration parameters on the system mixing using computational fluid dynamics simulation to predict the hydrodynamic phenomena. Factorial experimental design analysis was also used for statistical interpretation of the relationship between the ring baffle configuration and the hydrodynamic phenomena. The results revealed that the ring baffle configuration had a significant effect on the system mixing and hydrodynamics. From the analysis of variance, the standard deviation of radial solid volume fraction and the averaged solid particle concentration in the system were significantly affected by the baffle opening area, the space between the baffles and the interaction between these two terms, whilst the number of baffles and the interaction between the baffle opening area and the number of baffles also effected the averaged solid particle concentration in the system, with the interaction between baffle opening area and the space between baffles being the key parameter. In addition, regression models for each response variable were obtained. With respect to the system hydrodynamics, incorporation of the ring baffle improved the system mixing and eliminated the backflow near the wall with improved heat and mass transfers.

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