Solid-liquid circulating fluidized bed: a way forward

Solid-liquid circulating fluidized beds (SLCFBs) offer several attractive features over conventional solid-liquid fluidized beds such as efficient liquid-solid contact, favorable mass and heat transfer, reduced back-mixing of phases, and integrated reactor and regenerator design. These unique features have stimulated theoretical and experimental investigations over the past two decades on transport phenomena in SLCFBs. However, there is a need to compile and analyze the published information with a coherent theme to design and develop SLCFB with sufficient degree of confidence for commercial application. Therefore, the present work reviews and analyzes the literature on hydrodynamic, mixing, heat transfer, and mass transfer characteristics of SLCFBs comprehensively. Suitable recommendations have also been made for future work in concise manner based on the knowledge gaps identified in the literature. Furthermore, a novel multistage SLCFB has been proposed to overcome the limitations of existing SLCFBs. The proposed model of SLCFB primarily consists of a single multistage column which is divided into two sections wherein both the steps of utilization viz. loading (adsorption, catalytic reaction, etc.) and regeneration of solid phase could be carried out simultaneously on a continuous mode.