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

摘要

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 (PPM) and axial dispersion model (ADM). Experiments have been carried out using standard systems of water/acetone/toluene and water/acetone-butyl-acetate. Values of K_(oc)a evaluated by ADM are greater than those of PPM 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)O 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.