Hydrodynamics and mass transfer on three-phase distillation trays

Several oil‐water mixtures were contacted by air in a sieve tray distillation column simulator. The oil was mineral spirits with 183–206°C boiling range and 51.8° API gravity. Two sieve tray designs were used, and both hydraulic and mass transfer measurements were made, the latter utilizing acetone as the transferring solute. It was found that gas agitation caused the mixtures to behave as a homogeneous liquid that followed general correlations for pressure drop, liquid holdup, froth height, downcomer liquid level, and fractional entrainment. No unusual problems with foaming or entrainment were observed. Mass transfer efficiency was influenced by oil‐water ratio, with mild minima occurring at about 50 vol % mixtures. It was concluded that, when the immiscible liquids are both present in significant proportions, designers need not avoid formation of a second liquid phase for fear of unusual hydraulic or mass transfer behavior.