Droplet size distributions and batch separation of oil-in-water dispersions created by the two-phase flow through perforated plates

Abstract

The design of liquid/liquid gravity separators requires extensive research and optimization. In this context, the current contribution provides experimental insights into the droplet size distributions and the separation behavior of paraffin oil-in-water dispersions. The investigated dispersions result from the two-phase flow through perforated plates, which are placed inside the dispersion unit of a continuous mixer-settler. The droplet sizes are examined in relation to the geometry and number of perforated plates, the specific energy dissipation rates and the dispersed phase concentrations. A self-similar state, to which all normalized droplet size distributions converge, is approximated using a large sample of experimental data and modeled with suitable probability density functions. Finally, the influence of the Sauter mean diameter and the aforementioned process parameters on batch separation time is examined. It is suggested that the ratio between sedimentation and total separation time is analogous to a power-law decrease of the Sauter mean diameter and that the correlation is characteristic of the perforated plates geometry.