Aggregative and particulate fluidization - The two extremes of a continuous spectrum

Solid particles belonging to Geldart Group A, B and D were fluidized in liquids of changing viscosity and in CO2 under ambient to supercritical conditions. Local bed voidage signals were collected and processed in conjunction with global expansion characteristics to give quantitative indexes for evaluating fluidization quality. Results showed that the fluidized state changes progressively from aggregative to particulate when fluidized separately by gas, supercritical fluid and liquids, indicating an infinite number of intermediate states existing between aggregative and particulate fluidization. A discrimination number Dn is proposed to describe the transition from particulate to aggregative. A heterogeneity index delta and a nonideality index f(h) are proposed to quantify, respectively, the local and the global characteristics of the intermediate states. Copyright (C) 1996 Elsevier Science Ltd