DROP SIZE DISTRIBUTION AND HOLDUP PROFILES IN A MULTISTAGE EXTRACTIONCOLUMN

A population-balance-equation model is employed for the analysis of li quid-liquid extraction columns. This model considers drop breakage, co alescence, and exit phenomena for the drop phase caused by drop-drop a nd drop-continuous phase interactions. Drop breakage and coalescence r ates are employed from a previous study on liquid dispersions in stirr ed-tank contactors. A drop exit frequency is developed based on a stoc hastic modeling approach. The model is tested by drop size distributio n and dispersed-phase volume fraction (holdup) data obtained for a mul tistage column contactor of pilot-plant scale. Steady-state drop size distribution and transient holdup measurements are obtained by a photo micrographic technique and an ultrasonic technique, respectively. The model can predict flooding of the column. The effect of mass transfer on the hydrodynamic parameters of the contactor is also examined. The population-balance-equation model can be used for the control of extra ction columns and can be extended to include mass-transfer calculation s for the prediction of extraction efficiency.