Droplet-Settling vs. Retention-Time Theories for Sizing Oil/Water Separator

Summary This paper discusses two techniques for sizing oil/water separators. Droplet-settling theory, based on Stokes' law governing water-droplet movement through a continuous oil phase, is used to develop sizing equations for both horizontal and vertical separators. Retention-time theory, which calculates theoretical fluid-retention time within the separator by relating liquid flow rates to vessel geometry, is also presented. Published separator data comparing vessel sizes to allowable capacities are analyzed using both sizing techniques.