Experimental methods and correlation of solid—liquid mass transfer in fluidized beds

Abstract

Solid—liquid mass transfer in gas—liquid—solid fluidized beds is studied experimentally to clarify conflicting results in the literature which may be due to experimental procedure, equipment, or operating conditions. Particle tethering is found to affect measurement of the mass transfer, but the magnitude of the difference is a function of type of tether, column diameter, and flow regime. Effects of phase hold-ups and particle mixing are addressed, as well as liquid and gas superficial velocities. Correlation of the mass transfer coefficient is then discussed in light of the results of this study and the literature. In particular, correlations based on the energy dissipation model are reviewed in detail with respect to their qualitative and quantitative accuracy. A new correlation is then developed to account for the enhancement of the mass transfer due to the energy input to the system by the gas phase over that of the liquid—solid fluidized bed base case. The correlation accurately predicts the trends of the mass transfer with gas and liquid superficial velocities, particle and liquid properties, and phase hold-up.