Gas-solid fluidized beds in vortex chambers

This review deals with gas-solid fluidized beds in vortex chambers. High-G fluidization can be achieved in a static geometry and allows significant process intensification. Thin, dense and more uniform particle beds can be obtained at high gas-solid slip velocities, intensifying interfacial transfer of mass, heat and momentum and reducing the gas-solid contact time. Existing fluidized bed processes can be carried out more efficiently and novel processing routes can be developed, e.g., involving cohesive particles or a dispersed liquid phase in relatively high concentrations. The first section of the review discusses the unique hydrodynamic characteristics of gas-solid fluidized beds in vortex chambers. The flow pattern, flexibility in the operating conditions and stability conditions are explained. The design of vortex chambers is dealt with in the second section and is critical for processing both larger and fine particles. The influence of the gas and solids in- and outlet design is focused on and insight is gained from recent theoretical, experimental and CFD studies. In the third section (potential) applications are discussed and process intensification and novel processing routes demonstrated. The fourth and last section presents extensions of the concept. Multizone operation and the integration of other technologies in vortex chambers are considered. (C) 2014 Elsevier B.V. All rights reserved.