PARTICLE SUSPENSION AND MASS-TRANSFER RATES IN AGITATED VESSELS

This paper reviews and presents new information on three aspects of the behaviour of suspended solid particles in agitated tanks. The first is the minimum rate of stirring N required to keep the particles just suspended (JS) against their tendency to settle to the bottom of the tank. The second is the rate of mass transfer from suspended particles. The third is the relation between these two rates, that is, between N//J//S and the corresponding mass transfer coefficient k//L//J//S. Theoretical and practical aspects of these three problems are discussed here, and it is shown that, starting from basic turbulence theory, one can predict N//J//S as a function of particle concentration c. The reported constancy of the experimental k//L//J//S when the tank geometry is widely varied follows from the theoretical equations of the present paper.