Characteristics and Applications of Micro Fluidized Beds (MFBs)

Fluidized beds (FBs) are commonly employed by many practical applications, and continuous optimization of FBs is necessary to improve their application performance. However, it is uneconomical and impractical to conduct the parametric investigation and kinetic studies based on a large-scale FB. Accordingly, the micro fluidized beds (MFBs), with excellent mass/heat transfer and sufficient mixing between phases, serve as the suitable platform for understanding the reaction behaviors and extracting kinetics on a laboratory scale. In this review, a global view of the properties of the whole MFBs family (including gas-solid, liquid-solid and gas-liquid-solid MFBs) are comprehensively presented. The differences and correlations of hydrodynamics (e.g. enhanced wall effect) between MFBs and full-scale FBs are discussed, and modified correlations for predicting the minimum fluidization velocity (umf) and hydrodynamic features (e.g. flow regimes and residence time) of MFBs are summarized. Additionally, the application of MFBs in the areas of kinetic studies, rapid reactions and pharmaceutical engineering are also discussed. Finally, the parameter correlation between MFBs and full-scale FBs is discussed critically, and scaling up/scaling out strategies for guiding the design of industrial FBs are proposed. The conclusions of this review serve the purpose of a bridge to link the findings from lab-scale MFBs with the design and optimization of industrial FB reactors.