Mass transfer investigation in a horizontal–vertical pulsed packed extraction column

Abstract

In this study, hydrodynamic parameters and the mass transfer coefficient were investigated in a pilot version of a horizontal–vertical pulsed packed extraction column using a toluene–acetone–water system. The effects of the operational parameters on the volumetric overall mass transfer coefficient and hydrodynamic parameters away from the flooding point were studied, and it was found that the volumetric overall mass transfer coefficient, mean drop size and disperse phase holdup were significantly affected by the pulse intensity. However, the dispersed and continuous phase flow rates have a weaker effect. On the other hand, by increasing the pulse intensity the mean drop size and volumetric overall mass transfer coefficient were reduced and increased, respectively, in both sections of the column, but the disperse phase holdup displayed different behavior in the horizontal and vertical sections. By increasing the pulse intensity, the disperse phase holdup was first reduced and then increased in the horizontal section; however, an incremental trend was observed in the vertical section. The effect of the dispersed phase flow rate was significant for all the investigated parameters, but weaker. For instance, all the investigated parameters were increased by enhancing the dispersed phase flow rate. In contrast, the continuous phase flow rate has sometimes had no significant effect, for example, on the mean drop size in both sections of the column. Finally, two empirical correlations for the prediction of the volumetric overall mass transfer coefficient based on the continuous phase were derived in terms of the Sherwood number, Reynolds number and other dimensionless numbers. Good agreement between predictions and experiments was found for all operating conditions that were investigated.