Interphase mass transfer in an aggregative fluidized bed

Abstract

The experimental technique developed by Chavarie and Grace has been used to measure interphase mass transfer rates for bubbles in a two-dimensional fluidized bed with different sizes of particles from 90 to 39O μm. It is shown that the overall transfer rate, corrected for bubble growth and with negligible effects of adsorption, increases with particle diameter. The best model for the single bubble case assumes that transfer is controlled by diffusion and convection at the bubble interface, given by the penetration theory and by Murray's theory respectively. Agreement between this model and the data is best if corrections for bubble shape are applied and if it is assumed that there is no interaction between the two transfer mechanisms. Measurements of tracer concentrations as bubbles undergo coalescence indicate that there may be some enhancement of transfer due to bubble interaction, but this does not appear to be a major factor for the conditions studied.