Review of (gas)-liquid-solid circulating fluidized beds as biochemical and environmental reactors

Circulating fluidized beds (CFBs) possess many significant advantages over conventional fluidized beds, including enhanced interfacial contact efficiency and reduced back-mixing. Building on the many successful industrial applications of gas-solid CFBs, liquid-solid circulating fluidized beds (LSCFBs) and gas-liquid-solid circulating fluidized beds (GLSCFBs) have recently also received increasing interests due to their massive potential in chemical-biochemical, environmental and pharmaceutical processes. This review summarizes the progress in the past several decades concerning LSCFBs and GLSCFBs, with more emphasis placed on the reported applications, after a general description of the unique features of the two types of CFBs. Most of the examples given in this review are still in laboratory-scale, but useful guidance can be provided to researchers or companies for further study and/or commercial exploration.