Axial mixing and mass transfer investigation in a pulsed packed liquid-liquid extraction column using plug flow and axial dispersion models

In this research work, the volumetric overall mass transfer coefficient based on continuous-phase (K(oc)a) and axial dispersion coefficients of phases (E-c, E-d) in a pilot Pulsed Packed Liquid Extraction Column (PPLEC) have been studied using plug flow model (PFM) and axial dispersion model (ADM). Experiments have been carried out using standard systems of water/acetone/toluene and water/acetone/n-butyl-acetate. Values of K(oc)a evaluated by ADM are greater than those of PFM by about 20% indicating that the axial mixing lowers the performance of PPLEC. It was found that the drop-size distribution is the main cause of the axial mixing in PPLEC. Increase in dispersed phase flow rate (Q(d)), increases all K(oc)a, E-d and E-c and the minimum values of both E-d and E-c and the maximum values of K(oc)a are in pulse intensity ranges of 0.8-1 cm/s. Finally, three empirical correlations are proposed for the prediction of these parameters which are in good agreement with the experimental data. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.