Modelling of catalytic gas-solid fluidised bed reactors

Flow regimes in gas-solid fluidisation are presented on a broad scale from captive smooth fluidisation to dilute transport. The parameters useful to identify each transition are critically presented. The description of catalytic gas-solid fluidised beds is considered starti ng from simplified two-phase models; a third phase given by clouds and wake s is then introduced to justify their effect in promoting solids circulatio n. Different hydrodynamic features have been used in the literature to desc ribe the dense and the dilute phase, according to the mixing effect of bubb les. Circulating fluidised bed modelling is approached according to the definiti on of a hydrodynamic regime. The numerous models appearing up to now in lit erature are presented, from earlier homogeneous models to the latest contin uous radial profile and clustering models. The development of spouted beds as chemical reactors is given from the firs t fundamental approach, followed by the experimentation in the late 1970s, ending with more complex descriptions that take into account all the spoute d bed zones. A concluding chapter on model selection offers general criteria to tackle t he mathematical description which predicts the performance of catalytic rea ctors in the different regimes. (C) 1999 Elsevier Science B.V. All rights r eserved.