Scale‐up of liquid‐liquid dispersions in stirred tanks

Abstract

Abstract A study of local drop size, drop size distribution and holdup fraction was conducted for liquid‐liquid dispersions in three geometrically similar stirred tanks of standard configuration over a range of stirrer speeds and dispersed phase volume fractions. The tanks had diameter ratios 1:2:4, the smallest diameter being 11 cm. Two liquid‐liquid systems were used: n‐heptane‐water and n‐heptane containing different concentrations of di‐(2‐ethylhexyl) phosphoric acid dispersed in an aqueous sulphate solution. No significant local variations of the three parameters investigated were observed at constant stirrer speed and constant dispersed phase volume fraction. Measurements in the three tanks indicated that the rule of equal impeller tip speed provides the best scale‐up criterion for equal interfacial areas per unit volume of dispersion. A correlation was also proposed for the Sauter mean diameter.