Difference of hydrodynamics for a VPE with and without mass transfer and effect of agitation level on extent of mass transfer

Abstract

Liquid-liquid extraction offers an alternative separation technique, other than distillation, that uses a solvent for the separation of liquid constituents (Pratt, 1983). The vibrating plate extractor (VPE) is a mechanically agitated column that offers many advantages to conventional extraction equipment. Besides the dimensions of the column (diameter and height) and plate design, the VPE has many variables that may be appropriately adjusted to achieve the desired results viz. amplitude and frequency of vibrations, tray spacing, individual flow rates and the final throughput. The first part of the paper investigates the difference in hydrodynamics of the column due to the mass transfer process showing that the hydrodynamics (dispersed phase holdup, droplet size and size distribution) cannot be investigated without mass transfer in order to predict the behaviour during mass transfer. The second part of this paper is devoted to the investigation of the effect of agitation level on the extent of mass transfer.