Solubilities of Hydrocarbon Gases

In the case of three-phase equilibria, it is also necessary to account for the solubility of hydrocarbon gases in water. This solubility is proportional to the partial pressure of the hydrocarbon or, more precisely, to its partial fugacity in the vapor phase. The relation which ties the solubility expressed in mole fraction to the fugacity is the following ... 

Solubility of hydrocarbon gases in water expressed as Henry s constants. 

K.W. Miller, L. Hammond and E.G. Porter, The solubility of hydrocarbon gases in lipid bilayers, Chem. Phys. Lipids 20 (1977) 229-241. 

ITU Ituno, S., Ohzono, M., Iwai, Y., and Arai, Y., Solubilities of hydrocarbon gases in polybutadiene, Kobunshi Ronbunshu, 42, 73, 1985. 

Significance of the Solubility of Hydrocarbon Gases in Water 5.3.1. Why Significant... 

The solubility of hydrocarbon gases in water has attracted attention because of the gas hydrates, hydrophobic effects in protein chemistry, and the reflection of the structure of water. 

Wishnia, A., 1962, The solubility of hydrocarbon gases in protein solutions, Proc. Natl. Acad. Sci. USA 48 2200. 

The WAG process has been used extensively in the field, particularly in supercritical CO2 injection, with considerable success (22,157,158). However, a method to further reduce the viscosity of injected gas or supercritical fluid is desired. One means of increasing the viscosity of CO2 is through the use of supercritical C02-soluble polymers and other additives (159). The use of surfactants to form low mobihty foams or supercritical CO2 dispersions within the formation has received more attention (160—162). Foam has also been used to reduce mobihty of hydrocarbon gases and nitrogen. The behavior of foam in porous media has been the subject of extensive study (4). X-ray computerized tomographic analysis of core floods indicate that addition of 500 ppm of an alcohol ethoxyglycerylsulfonate increased volumetric sweep efficiency substantially over that obtained in a WAG process (156). 

The following table presents the solubilities of several gases in water at 25 "C under a total pressure of gas and water vapor of 1 atm. (a) What volume of CH4(g) under standard conditions of temperature and pressure is contained in 4.0 L of a saturated solution at 25 °C (b) Explain the variation in solubility among the hydrocarbons listed (the first three compounds), based on their molecular structures and inter-molecular forces, (c) Compare the solubilities of O2, N2, and NO, and account for the variations based on molecular structures and intermolecular forces, (d) Account for the much larger values observed for H2S and SO2 as compared with the other gases listed, (e) Find several pairs of substances with the same or nearly the same molecular masses (for example, C2H4 and N2), and use intermolecular interactions to explain the differences in their solubilities. 

Depending on the temperature at which the procedure is carried out, an intense red color appear in the zones of bubble collapses, and remains stable, unless the temperature is increased, for about 30 min. We determined that the color is observed only if NO" is in excess in the zone of reaction. We deduce this is the case when NO" is injected into 02-saturated hydrocarbon. As pointed out before, the solubility of diatomic gases from the second period in hydrocarbons is 20—30 mM at ambient conditions (51). The colored patches remaining after NO" injection are about 10 mm long and 1 mm wide, therefore comprise a volume of ca. 10 pi. Typical initial bubble diameter is about 4—6 mm, the initial volume approximately 0.1 ml, which corresponds to 4 pmol of NO" at ambient temperature. After bubble collapse, the NO" concentration is about 100 mM in the reaction zone and therefore in excess over O2. The colored reaction product does not yield any... 

The solubility of common gases in hydrocarbon liquids is determined to meet requirements of aerospace industry. This test method is based on the Clausius-Clapeyron equation, Henry s law, and the perfect gas law. The results are important in the lubrication of gas compressors where dissolved gas may cause erosion due to cavitation. In fuels, dissolved gases may cause interruption of fuel supply and foaming in tank. The liquid density is determined experimentally. Using this density, the Ostwald coefficient is taken from a chart and used for e calculation of the Bunsen coefficient (solubility of gas). The solubility of the gas or mixture of gases and Henry s law constant are also calculated. 

Several models that include the effect of pressure on viscosity are outlined herein. For applications at high pressures, one may also require estimates of the viscosity of liquid hydrocarbons and their mixtures with dissolved gases (such as with CO2, Nj, H2S, etc.) because, due to the high solubility of such gases in hydrocarbon mixtures at elevated pressures, there is a very large reduction in the mixture viscosity. Indeed, such behavior is part of the basis for enhanced oil recovery by miscible gas injection. Even though the effect of dissolved gases is beyond the scope of this chapter, some comments about this are included due to the importance of this subject. 

Gibb CLD, Gibb BC. Templated assembly of water-soluble nano-capsules Inter-phase sequestration, storage, and separation of hydrocarbon gases. J Am Chem Soc 2006 128 16498-9. 

Most hydrocarbon gases are more soluble in cold oil than in hot oil and may lower the viscosity to a dangerous level. The problems of thrust-bearing failures during startup due to low-viscosity oil can be eliminated by equipping the reservoir with oil heaters to raise the oil to the normal operating temperatures before starting the machine. 

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