Impact of solid and gas flow patterns on solid mixing in bubbling fluidized beds

Abstract

Bubbling fluidization has been widely applied in industrial processes as an effective means for providing excellent mixing, good heat and mass transfer. Examples include granulation, coating, mixing, power generation from coal, renewable energy production, gasification and pyrolysis. In this study, we attempted to analyse the impact of solid flow patterns, bed design and operational conditions on solid mixing in a bubbling fluidized bed. The solid mixing behaviour was estimated based on the dispersion coefficient of particles, the active index (AI), and the distribution of particle residence time within the entire bed. In our previous studies, four flow patterns have been founded and classified as patterns A, B, C and D. Results presented from this study indicate that the mixing behaviour in a fluidized bed varies significantly with solid flow patterns which is a result of a combination of operational conditions, properties of bed materials and bed designs. Flow pattern D provides the best mixing in the four flow patterns identified by using the PEPT technique. Pattern A provides the worst solid mixing. Pattern B is a typical solid flow pattern reported in literature, but its mixing behaviour is only better than the Pattern A.