Mass transfer between bubbles and the dense phase in gas fluidized beds

Abstract

Mass transfer between a bubble and the dense phase in gas fluidized beds of Group A and Group B particles was proposed based on previous experimental results and literature data. The mass transfer coefficient between bubbles and the dense phase was determined by kbe=0.21db. A theoretical analysis of the mass transfer coefficient between a bubble and the dense phase using diffusion equations showed that the mass transfer coefficient between a bubble and the dense phase is kbe∝εmfDub/db in both three- and two-dimensional fluidized beds. An effective diffusion coefficient in gas fluidized beds was introduced and correlated with bubble size as De=13.3db2.7 for Group A and Group B particles. The mass transfer coefficient kbe can then be expressed as kbe=0.492εmfubdb1.7 for bubbles in a three-dimensional bed and kbe=0.576εmfubdb1.7 for bubbles in a two-dimensional bed.