Effect of particles in bubbles on fluidized bed mass and heat transfer kinetics.

Abstract

Experiments in bubbling fluidized beds show that gases which adsorb on solids experience up to ten times more rapid bubble-emulsion interchange than do nonadsorbing gases. We propose that the very small fraction of solids dispersed in and passing through the bubbles are the vehicle for this behavior.A theory is developed which shows that the enhancement in the overall bubble-emulsion interchange coefficient is strongly dependent on the value of the gas–solid adsorption equilibrium constant. The enhancement predictions from theory are then compared with values reported in the literature.This mass transfer phenomenon is then extended to gas–solid heat transfer in fluidized beds. The results indicate that the particles dispersed in bubbles usually play the dominant role in the heat interchange between bubble gas and emulsion gas.