A theoretical and experimental investigation of continuous oil–water gravity separation

Abstract

In this study, we have developed a mathematical model for a three-phase separator. The model consists of two sections: the inlet section and the separation section, separated by a perforated calming baffle. In the inlet section, two dispersion layers undergo droplet size evolution due to turbulent breakage and coalescence, described by a spatially homogeneous PBE. In the separation section, the two dispersion layers flow alongside each other and interact at an interface. The volumetric flow and velocity profiles are influenced by interfacial coalescence, with considerations for plug and laminar flow assumptions. The model incorporates droplet gravity-driven transport using the Kumar and Hartland model, binary and interfacial coalescence employing a film drainage model, and an effective diffusion term to account for the formation of the dense packed layer which ensures a physical volume fraction range of 0–1. Steady-state and transient numerical solvers are developed to solve the resulting advection–diffusion equations. Additionally, a series of experiments were conducted using a lab-scale multi-parallel pipes separator to investigate the impact of varying volume fractions and flow rates on the separation efficiency of the equipment. The model results are compared with the experimental data which shows relatively good agreement.