The different behaviour of Geldart A and Geldart B powders in fluidisation is a well documented phenomenon. We have recently shown (1996) that a model based on the kinetic theory analogy is able to predict adequately the flow of sand (Geldart B) in a circulating fluidised bed (CFB) riser, but it predicts poorly the flow of fluid catalytic cracking (FCC) catalyst (Geldart A). In the present work surface forces. responsible for cohesiveness of powders, are inserted into a model based on the kinetic theory analogy (I. ctizia. 1998), and the predictions from the model are compared with experimental data (Bodelin. 1994).
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