(Gas-)liquid-solid circulating fluidized beds and their potential applications to bioreactor engineering

Compared with conventional fluidized beds, circulating fluidized beds have many advantages including better interfacial contacting and reduced backmixing (Lim et al., 1995). While there are many reports on the gas-solid circulating fluidized systems, liquid-solid and gas-liquid-solid circulating fluidized bed systems have been scantily studied. However, extending current knowledge obtained in gas-solid systems to liquid-solids and gas-liquid-solid three-phase systems is shown to open new horizons for applications of circulating fluidized bed technology and expected to lead to the development of highly efficient liquid-solid and gas-liquid-solid reactors, especially for the ever growing field of biotechnology. In order to fully appreciate the potential of those two types of liquid phase circulating fluidized beds, recent progress is reviewed in this article. Their potential applications to biochemical processes are also discussed.