Electrocoalescence of water droplets in sunflower oil using a novel electrode geometry

Abstract

Electrocoalescence is an energy-efficient and environmentally-friendly process for breaking water-in-oil emulsions. It has been used extensively in the oil and petroleum industries. However, the current technology requires long residence times, giving rise to bulky vessels for industrial scale operations and making it less attractive for offshore application. It is also highly desirable to develop compact devices for down-the-well use. In this study, the performance of a novel electrode geometry, a ladder-shaped set of electrodes through which the emulsion flows, is assessed for enhancing the electrocoalescence, hence providing the potential for a compact design. The electrodes are formed into a V shape, with the apex pointing towards the direction of flow. This configuration enables nesting a series of electrodes in a compact form.

Contactless Method of Emulsion Formation Using Corona Discharge

“…The motion of the smaller trapped droplets is governed by an effect of the electric field, which is known as electrophoretic (EP) force . After several bounces between the top surface of the oil and the ground electrode, the electrocoalescence increases the size of the droplets. , Considering Coulomb’s law, the larger droplets with a larger surface area need more EP force to continue their bouncing behavior and their speed of reciprocation will decrease . The EP force could be easily calculated using F EP = E · Q , where E is the intensity of the electric field and Q is the charge on the surface of the droplets.…”

Separate Reclamation of Oil and Surfactant from Oil-in-Water Emulsion with a CO2-Responsive Material

“…The oil droplets adsorbed onto PU@PDEAEMA also presented in a demulsified state (Figure c). Although magnetic stirring can improve oil droplet coalescence to some extent, , the adsorbent still plays a dominant role in the demulsification of the emulsified crude oil. These phenomena indicate that both the residual oil droplets in the emulsion and those abstracted by PU@PDEAEMA coalesced into bigger oil droplets during the adsorption.…”

“…This result supports our hypothesis that the electrostatic attraction between the adsorbent and the surfactant is important. Under magnetic stirring, drop–drop collision and coalescence will occur, which usually are more evident as the stirring duration is extended. , Furthermore, the abstraction of SDBS by PU@PDEAEMA through electrostatic attraction weakens the Marangoni effect at the oil/water interface, which stabilizes oil droplets; , thus, the droplet–droplet interaction will be improved . Subsequently, the water film between oil droplets becomes metastable, and the drainage time of the water film will be reduced.…”

“…The contact time between oil droplets probably will also be prolonged due to reduced electrostatic repulsion. The water film drainage model has been used in the literature to describe the coalescence efficiency with an empirical formula of (λ is the coalescence efficiency, t drainage is the time needed for water film drainage till coalescence, and t contact is the contact time of oil droplets). , According to this equation, the coalescence efficiency increases with reduced water-film drainage time and increased contact time of oil droplets, ,, which can explain the demulsification and coalescence of tiny oil droplets upon PU@PDEAEMA addition and prolonged stirring (Scheme b). When CO 2 is sparged into the water, the tertiary amine groups in PDEAEMA will be fully protonated.…”

Coalescence of Binary Droplets in the Transformer Oil Based on Small Amounts of Polymer: Effects of Initial Droplet Diameter and Collision Parameter

“…Furthermore, in the field of the coalescence of water droplets in the oil phase, the different research approaches can roughly be divided into two groups. On the one hand, from a driving method of view, electric fields [ 23 ] or coupling of electric and magnetic fields [ 24 ] are often used to promote droplet coalescence. On the other hand, some literature focuses on the addition of polymers to promote droplet coalescence, which has recently evolved rapidly, because it can change the water-oil interfacial tension [ 25 ].…”