Dispersed phase holdup has been measured in a 76 mm diameter pulsed disc and doughnut extraction column for three different liquid-liquid systems. The effects of operational variables such as pulsation intensity and dispersed and continuous phase flow rates on holdup have been investigated and found to be significant. The existence of three different operational regimes, namely mixer-settler, dispersion, and emulsion regimes, was observed when the energy input was changed. The results indicated that the characteristic velocity approach is applicable to this type of extraction column for analysis of holdup in the transition and emulsion regions. Empirical correlations are derived for prediction of the dispersed phase holdup in terms of the physical properties of the system and the operating variables in different operating regimes. Good agreement between prediction and experiments was found for all operating conditions investigated.
Dispersed phase holdup; Pulsed disc and doughnut column; Slip velocity; Characteristic velocity
