Collect. Czech. Chem. Commun. 1995, 60, 1-33

Operation Regimes of Fluidized Beds

Miloslav Hartmana, Zdeněk Beranb, Karel Svobodaa and Václav Veselýa

a Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 165 02 Prague 6-Suchdol, Czech Republic
b Department of Chemical Engineering, Technical University Brno, 637 00 Brno, Czech Republic


The state of the art has been reviewed in the analysis and description of flow or contacting pattern in gas-solid contacting units where a gas flows upwards through a bed of solids. The flow regime or contacting mode varies widely, depending on the particle size, particle density, gas density, gas viscosity, gas velocity and column geometry. The influence of such variables is reflected in the particle classification schemes and regime diagrams to cover the operation regions of common gas-solid reactors and contactors. In general, fluidized beds can be operated in six different regimes: particulate (homogeneous) fluidization, bubbling fluidization, slugging fluidization, turbulent fluidization, fast fluidization and pneumatic conveying. The bubbling beds can be further classified into three different modes of contacting: fast bubble regime, slow bubble regime and rapidly growing bubble regime. Characteristic features of all the regimes as well as the transitions between them are discussed. Current research interests, supported by practical needs, are oriented toward the operation conditions and contactor geometry of high velocity units.