Experimental studies were carried out in a gas-solid fluidized bed with a diameter of 20 cm, into which highly humid air was sent to form successive single bubbles larger than 4 cm by use of a solenoid valve.
Overall rate constant of mass transfer between single bubble and solids in emulsion was found to decrease with increasing bubble diameter. Comparison of the above experimental data with a theoretical equation proposed by Kunii and Levenspiel taking account of the solids dispersed in bubble showed that the contribution of the dispersed solids was nearly controlling and that most of the mass transfer between bubble and solids in the above fluidized bed was carried out by solids dispersed in bubble, even though the volume fraction of the dispersed solids to the bubble was as small as 4×10-4.
