Transport emulsions preparation

Emulsion Preparation. Preparing a transport emulsion is a fundamentally simple operation that includes the steps of forming a water-brine solution of the emulsion-stabilizing composition followed by a shearing process in which the crude oil and aqueous phases are metered to a specific mixing device. 

Crude oil and brine pumps may be centrifugal or positive displacement, but must be capable of providing steady flow to the mixing device because emulsion properties are highly dependent on the resulting crude-oil-brine ratio. Surfactant may be dissolved in the brine phase on a batch or continuous basis. Static mixers provide a simple method for the preparation step because they require no moving parts, are easy to scale up, and provide an mixing intensity that is suited to preparation of transport emulsions. 

Emulsion Pipeline Operations. Prediction of pipeline pressure gradients is required for operation of any pipeline system. Pressure gradients for a transport emulsion flowing in commercial-size pipelines may be estimated via standard techniques because chemically stabilized emulsions exhibit rheological behavior that is nearly Newtonian. The emulsion viscosity must be known to implement these methods. The best way to determine emulsion viscosity for an application is to prepare an emulsion batch conforming to planned specifications and directly measure the pipe viscosity in a pipe loop of at least 1-in. inside diameter. Care must be taken to use the same brine composition, surfactant concentration, droplet size distribution, brine-crude-oil ratio, and temperature as are expected in the field application. In practice, a pilot-plant run may not be feasible, or there may be some disparity between pipe-loop test conditions and anticipated commercial pipeline conditions. In these cases, adjustments may be applied to the best available viscosity data using adjustment factors described later to compensate for disparities in operating parameters between the measurement conditions and the pipeline conditions. 

A StockweU, SE Taylor, EJ Taylor, EJ Murray, ML Chiri-nos. Tscous crude oil transportation the preparation of bitumen, heavy and extraheavy crude oil in water emulsions. Third UNTTAR International Conference On Heavy Cmde and Tar Sands. Long Beach, CA, 1985. Proceedings, Vol. 4, p 1983. 

Electrolytes in particular can exhibit significant effects on the stability of emulsions prepared with one or more ionic surfactants. There are multiple potential effects, including (1) changes in the role of the surfactant at the various interfaces as a result of changes in their electrical properties, (2) changes in the namre of the interfacial films due to the presence of specific ionic interactions between surfactant and electrolyte, and (3) alterations in the transport properties of the intervening phase due to differences in the osmotic pressure between the two phases. 

Perfluorocarbons. In 1966, it was demonstrated (27) that a laboratory mouse could survive total immersion in a perfluorochemical (PFC) solution. This material, similar to commercial Teflon, is almost completely inert and is insoluble in water. A water-soluble emulsion was prepared that could be mixed with blood (28), and in 1968 (29) the blood volume in rats was completely replaced with an emulsion of perfluorotributylamine [311-89-7], C12F27N. The animals survived in an atmosphere of 90—100% 02 and went on to long-term recovery. However, the 02 content of the perfluorochemicals has a linear dependence on the partial pressure of oxygen, P, as can be seen in Figure 1. The very high 02 tension required to transport physiologic amounts of 02 (12) and the propensity of the perfluorocarbon to be taken up by the reticuloendothelial cells were considered to be severe limitations to the development of clinically useful perfluorocarbon blood substitutes (30). 

Among the applications of membrane emulsification, dmg-delivery system (DDS) is one of the most attractive fields. W/o/w emulsions have been prepared to transport and deliver anticancer drug [4, 63-65]. The emulsion was directly administered into the liver using a catheter into the hepatic artery. In this way, it was possible to suppress the strong side effects of the anticancer drug and also concentrate the dosage selectively to focus on the cancer. The clinical study showed that the texture of the cancer rapidly contracted and its volume decreased to a quarter of its initial size. 

Sulfur-asphalt binders can be prepared by various mechanical means. One conventional method is to combine liquid sulfur and asphalt at 285°-300°F in a Gifford Wood colloid mill. A rotor stator gap setting of 0.02 in. at 7000 rpm for 8 min will prepare satisfactory emulsions. This emulsion is immediately mixed with preheated aggregate. The laboratory binder was prepared by TTI (Texas Transportation Institute) scientists in cooperation with SNPA (Societe Nationale des Petroles d Aquitaine) scientists and is believed to be comparable with the binders prepared by the turbine in the field trials. The need for dispersing sulfur in the asphalt is discussed by Garrigues (9) and by Kennepohl et al., Deme, and McBee et al. elsewhere in this volume. 

Membrane reactors using biological catalysts can be used in enantioselective processes. Methodologies for the preparation of emulsions (sub-micron) of oil in water have been developed and such emulsions have been used for kinetic resolutions in heterogeneous reactions catalyzed by enantioselective enzyme (Figure 43.4). A catalytic reactor containing membrane immobilized lipase has been realized. In this reactor, the substrate has been fed as emulsion [18]. The distribution of the water organic interface at the level of the immobUized enzyme has remarkably improved the property of transport, kinetic, and selectivity of the immobilized biocatalyst. 

The techniques used in the preparation of a stable oil-in-water emulsion for pipeline transportation are illustrated by the results of a field test in which an Athabasca bitumen was emulsified and pumped through a 3-in. x 4000-ft. pipe-loop system for a total distance of approximately 500 miles. The emulsion in this case comprised 75% by weight of the 8.3 API bitumen and 25% of a synthetic brine containing 1.7% NaCl. (API gravity is defined in the Glossary.) The surfactant used was a mixture of two ethoxylated nonylphenol surfactants the first component contained an average of 40 ethylene oxide units per molecule, and the second component contained 100 units. Approximately 1500 ppm of the surfactant mixture, based on the total... 

An innovative technique involving the preparation of a lower-viscosity unstable slurry-emulsion system by mixing water with the oil as a means of conveying crude oil has yet to be proven on a commercial scale. The technical problems and issues limiting the application of this technique (analogous to crude-oil emulsion pipelining) are to sustain the two immiscible liquids in a stable emulsion during transport and to destabilize the emulsion... 

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