On the criteria of solids layer inversion in a liquid-solid fluidized bed containing a binary mixture of particles

Abstract

A simple criterion is proposed for the prediction of solids layer inversion velocity or critical velocity in a liquid-solid fluidized bed containing a binary mixture of particles with solids layer inversion properties. The criterion is established based on the behaviour of the segregation velocity of the particle which locates at the bottom of the bed at low liquid velocities. The criterion is verified satisfactorily with the present experimental results, which were obtained over a wide range of volume ratio of the particles in the binary mixture, and the experimental results reported by Moritoni et al. (1982, Chem. Engng Sci. 37, 1751–1757) and Matsuura and Akehata (paper presented at 50th Annual Meeting of Soc. of Chem. Engrs of Japan, 1985). The criterion is also satisfactorily extended to account for the onset velocity of the particle intermixing state before the point of layer inversion.