Separation kinetics of an oil-in-water emulsion under enhanced gravity

• Published in: Chemical engineering science Vol. 71; no. 3; pp. 118 - 125
• Main Authors: Krebs, T., Schroën, C.G.P.H., Boom, R.M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 26.03.2012; Elsevier
• Subjects: Applied sciences; bubble; Centrifugation; Centrifugation, cyclones; Chemical engineering; coalescence; Colloid phenomena; drop; droplets; Emulsion; emulsions; Exact sciences and technology; gravity; Hydrodynamics of contact apparatus; Kinetics; Liquid-liquid and fluid-solid mechanical separations; oils; Petroleum; phase transition; plane; Separations; separators; size; stability; surface; surfactants; Emulsion; Kinetics; Colloid phenomena; Centrifugation; Petroleum; Separations; Swirling flow; Surfactant; Droplet; Flow field; Modeling; Hydrocyclone; Crude oil; Coalescence; Colloid particle; Separator; Demulsification
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2011.10.057

The breakup of crude oil emulsions to produce clean oil and water phases is an important task in crude oil processing. We have investigated the demulsification kinetics of a model oil-in-water emulsion in a centrifugal field to mimic the forces acting on emulsion droplets in oil/water separators such as hydrocyclones. The rate of growth of separated oil phase and the change in mean droplet diameter of the emulsion layer was measured as a function of surfactant concentration, centrifugal acceleration and time. Demulsification is enhanced with increasing centrifugal acceleration and time and decreasing surfactant concentration. A kinetic analysis was performed that allows to estimate the characteristic coalescence times between droplets in the emulsion and between a droplet and the separated oil interface. The experimental procedure presented in this work can serve as a simple, but useful test to predict the separation efficiency of emulsions in separators with swirling flow fields. [Display omitted] ► We present a simple method to assess the stability of emulsions in centrifugal flow fields. ► The change in drop size and growth of pure oil phase in an O/W emulsion was measured. ► A kinetic model is presented that allows calculation of characteristic coalescence times. ► The procedure may be of help for the petroleum industry in choosing a separator for a given produced fluid.