Properties, Minimum Fluidization, and G eldart Groups

This chapter identifies the key particle and fluid properties that affect the ability to fluidize particles and that play a major role in determining the properties of fluidized beds. It is important to characterize these properties, or at least to consider whether each could be relevant, when deciding whether or not a given process might benefit from fluidization, as well as when designing, operating, and modelling fluidized bed processes. The chapter considers different methods of measuring and predicting both the minimum fluidization velocity and the bed voidage at minimum fluidization, two very important quantities affecting the properties of fluidized beds. It introduces the Geldart powder groups for particles fluidized by gases. The Geldart powder groups are widely used in discussing, characterizing, and explaining gas fluidization.