Equilibrium Constants for Hydrocarbons in Absorption Oil

Abstract

The economical recovery of the valuable constituents from the effluent ofgas-condensate wells has developed into a problem of balancing the cost ofrecovery against the cost of compressing the residual gas back into theformation. A possible method of extracting the gasoline and distillate from thenatural gas is by oil absorption at high pressures. In order to design andevaluate an absorption plant, fundamental data on the composition of thecoexisting hydrocarbon vapor and liquid phases at various temperatures andpressures are essential. A review of the literature indicated that the necessary data for the design ofsuch plants are lacking. The nearest approach to desired published data is thatof Katz and Hackmuth, who experimentally determined the composition of thecoexisting vapor and liquid phases in a natural gas-crude oil system atpressures up to 3000 lb. per sq. in. and at temperatures from 40? to200?F. This paper presents the results of the experimental determination of theequilibrium distribution of the hydrocarbons methane through hexane betweennatural gas and a typical absorber oil. The ranges of temperature and pressurechosen were from 33? to 180?F. and from 100 to 5000 lb. per sq. inch. Materials The absorber oil was a typical naturally occurring, straw-colored distillatethat had previously been steam-distilled to an initial boiling point of 300?F.The physical and chemical properties, including the results of an Englerdistillation, are presented in Table I. A large volume of this oil was obtainedand it was used throughout the complete set of experiments. The n-hexane was obtained from the Ohio Chemical and Manufacturing Co., Cleveland, Ohio. This liquid had a boiling range of from 149? to I52.6?F., witha density of 0.667 at 60?F. and a molecular weight of 85 by benzenefreezing-point depression. The propane, isobutane, n-butane, isopentane andn-pentane were obtained from the Philgas Department of the Phillips PetroleumCo. Certified analyses of these compounds showed their purity to be in excessof 99.5 per cent and they were not further purified. T.P. 1252