Dispersed-Phase Holdup and Characteristic Velocity in a Pulsed and Nonpulsed Disk-and-Doughnut Solvent Extraction Column

The dispersed-phase holdup and characteristic velocity, which are important hydrodynamic performance parameters for solvent extraction columns, were measured and compared to literature correlations under pulsing and nonpulsing conditions using a 75 mm diameter disk-and-doughnut column. The results show that the dispersed-phase holdup increased with increasing dispersed-phase flow rate, while there was no noticeable change in holdup with the continuous-phase flow rate. With increasing pulsation intensity from zero, the dispersed-phase holdup decreased at first and then increased. A minimum holdup was found in the transition from the mixer-settler to the emulsion regime, and it increased with increasing dispersed-phase velocity. The experimental holdup and minimum holdup were correlated over a range of pulsation rates to within 13.3% and 8.8%, respectively. The characteristic velocities under different pulsation conditions were calculated from the measured holdup for the pulsing conditions. The characteristic velocities decreased with increasing pulsation intensity and were correlated to within 3.5%.