Predicting sizes of toluene-diluted heavy oil emulsions in turbulent flow. Part 1—Application of two adsorption kinetic models for σEσE in two size predictive models

Predicting oil-in-water emulsion droplet size and stability in turbulent flow is useful for choosing separation processes in heavy oil extraction. In order to study the process, averaged droplet sizes for toluene, n  -heptane and mineral oil were measured during stepped-down turbulent mixing. Droplet sizes were measured for five concentrations of heavy oil in toluene at oil fraction 0.05 in model process water as a function of time during turbulent mixing. Mixing was conducted with a Rushton turbine in a cylindrical tank. Size distributions were measured with the Mastersizer 2000 laser diffraction instrument. Dynamic interfacial tensions σdynσdyn (by drop volume technique, DVT) and static interfacial tensions σσ (by du Nouy ring) as a function of time were measured. Data were fitted with two adsorption kinetic models (diffusion limited Dl, and Langmuir based Lb) to find “equilibrium” interfacial tensions σEσE needed to predict Sauter mean diameter d32d32 in Hinze–Kolmogorov (H–K) and Wang–Calabrese (W–C) models. Data were also analyzed by using a classical breakage–coalescence kinetic model. Results showed that by using σdynσdyn with W–C model the predicted d32d32 changed proportionately with σdynσdyn. For any σEσE the d32d32 predicted using the W–C model was closer to the experimental d32d32 than the d32d32 predicted by the H–K model. The σEσE's obtained by the Dl and Lb models were similar when fitted to DVT data giving identical W–C predicted d32d32. However, only the Dl model fitted the σσ-time data obtained by the du Nouy ring technique and the σEσE in W–C model gave d32d32 closest to experimental d32d32 for droplets of 1–10 wt% heavy oil in toluene. The predicted d32d32 of droplets for the 25-wt% heavy oil was larger than the experimental d32d32. This difference was attributed to interfacial film thickness and decreased elasticity discussed in an earlier publication.