Interaction with demulsifiers

Demulsifiers are quite effective at clearing fuel of water-initiated haze. Occasionally, upon clearing the fuel, the water will be removed by interacting with a demulsifier to form an emulsion. This emulsion will precipitate from the fuel and settle to the bottom of a fuel storage tank. This emulsion can plug filters and clog small lines if not removed from the tank with the water bottoms. 

Strong attraction to flie oil/water interface is often dependent on diffusibility and interfacial activity of the demulsifier. This also involves speed of migration to the interface and the ability to compete or interact with the emulsifier by one or more mechanisms. The demulsifier must be relatively soluble in flie continuous phase yet not completely soluble, and able to transport itself to the interface. In some cases, if the interface is stretched, the demulsifier must get there before flie emulsifier can readsorb. The presence of demulsifier in flie dispersed water phase has... 

For these reasons the basic understanding of crude oil and bitumen emulsions and demulsification has received considerable attention. Advances in the knowledge of the physicochemical-mechanical structure of the stable emulsions and their films are being made in our laboratory and elsewhere. The films response to demulsifiers are studied in order to understand the detailed mechanisms of demulsification. This knowledge will provide a more scientific basis for formulating products. The knowledge of surfactant chemistry, the behavior in solutions, the behavior at interfaces, and interactions with the crude-oil solvent base involve a wide interplay of complex processes in designing formulations. 

Compressible resin films will not alone stabilize a crude oil emulsion. Related to this, demulsifiers, which form films of low rigidity and high compressibility, should be the most efficient. When used as demulsifiers, the efficiency depends on the ability of the chemicals to interact with and modify the film built up by asphaltene particles. 

The petroleum industry generally solves the emulsion problem by adding demulsifiers in an ad hoc manner, often based on simple bottle tests. There are many problems associated with this solution. First, the chemical composition of a given well changes with time and can in a worst-case scenario result in a composition totally incompatible with the given demulsifier. Second, little is known about the exact interaction between demulsifiers and other chemical additives (e.g., corrosion inhibitors and flow enhancers ). One may, flierefore, create a new problem by solving another. 

In the following discussions the published experimental findings are presented interrelatedly first in terms of internal oil chemistry at the interface and instabilities based on its composition, secondly in terms of effects of water chemistry, and thirdly in terms of demulsifier interaction. We include the activity of interfacial components involved in the structure of the protective skin, the behavior(s) of this structure with changes to water chemistry or solvency, or the effects of changes in film stmeture itself due to modification of relative proportions of interfacially active components. In some examples, developments in interfacial rheology, which is both a tool for understanding stable films and a means of rationalizing the effects of demulsifiers in demulsification, are discussed interrelatedly. Films may be sensitive to crude oil type, gas content, aqueous pH, salt content, temperature, age, and the presence of demulsifiers. Demulsifier performance is also influenced by many of these variables. 

Some of these studies indicate that HLBis not the only property of the chemical which determines the demulsifier power. Cooper et al. (285) indicated that water reduetion was dependent on the chemical structure of the surfaetant when two surfactants with similar HLBs gave opposite results. The effects of the interaction of the chemical stmcture with emulsion interfaces are the more important factors in demulsification, as these influence the film rheology of the system. 

Chemical destabilization is the mutual topic for the chapters by Angle and by SjOblom, Johnsen, Westvik, Ese, Djuve, Auflem, and Kallevik ( Demulsifiers in the Oil Industry ). These contributions present a comprehensive treatise on chemicals used to promote coalescence, as well as their interaction patterns with different indigenous film-forming components in the cmde oils. The competition between categories of demulsifiers in the bulk and at the W/0 interfaces is central in these chapters. The question of chemical administration to enhance the efficiency of the chemical agents is also raised. The upscaling of the use of the chemicals in actual recovery operations onshore as well as offshore is also reviewed. 

Definition Random copolymer produced by interaction of 17 moles ethylene oxide with 6 moles of propylene oxide Toxicology TSCA listed Uses Solvent in cosmetics lubricant for antiperspirants emollient bodying agent lubricant for textile spin finishes intermediate for prep, of resins, plasticizers, modifiers, and surfactants demulsifier food-pkg. adhesives, animal glues defoamer in food-contact paper/paperboard... 

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