Effect of turbulence on the separation of liquid-liquid dispersions in batch settlers of different geometries

The separation of batch dispersions is affected by the initial turbulence p resent in the settler which reduces the initial sedimentation rate and the onset of interfacial coalescence. As the turbulence decays, these rates gra dually increase, giving rise to sigmoidal sedimentation and coalescence pro files. A model is presented which describes the separation of a dispersion of height H-0 and holdup epsilon(0) with an initial drop diameter phi(0), a nd interfacial coalescence time tau(d) allowing for the turbulence decay ti me t(d) and coalescence incubation time t(0). For a given holdup epsilon(0) , the drop diameter phi(0) and initial turbulence are themselves functions of the mixing conditions. The model is used to describe experimental data f or both water-in-oil and oil-in-water dispersions for different liquid-liqu id systems ranging from a heavy crude to a water-like model oil. The effect of physical properties, holdup, initial turbulence, and settler geometry i s investigated.