A new fluid-solid contacting technique known as transfer data were obtained for a benzoic acid-water system, and correlations in terms of mass transfer factors and over-all void fractions (for both packed and fluidized sections) are presented. Previous mass transfer correlations for fixed and fluidized beds are critically evaluated with respect to the limitation and applicability and are discussed in relation to semifluidized-bed mass transfer correlations.
Semifluidization is a type of fluidsolid contact operation in which the expansion of a fluidized bed is partially restricted. Under such conditions the porosity of a semifluidized bed is intermediate between the rigidly packed bed and the completely fluidized bed.
Some of the characteristics of a semifluidized bed, such as the simultaneous formation of a packed section and a fluidized section in the bed, were reported in a previous communication (9). The purpose of this paper is to report the results of experimental work on the mass transfer aspect in a semifluidized bed of a solid-liquid system.
Aside from its practical significance in mass transfer operations, the study of rate of mass transfer is of general significance because it often leads to better understanding of other aspects of chemical engineering operations and heat transfer. Since the mechanism of interphase mass transfer in a fluidized bed is already complicated (4, 2 4 ) , no particular attempts were made to analyze the data in the light of the rigorous theories of interphase mass transfer. Rather, emphasis was placed on the empirical A WATLR TANK (I ?W? C ILOIYLTER