The correlation of vapor‐liquid equilibria of methane in paraffinic, naphthenic, and aromatic solvents at low temperatures and high pressures

Abstract

Several different approaches, such as the convergence pressure concept, equations of state, the application of the principle of corresponding states, etc., have been tried for the correlation of vapor-liquid equilibria of hydrocarbons for many years. The NGAA Data Book ( 3 0 ) is an example of the application of the convergence pressure concept which was originated by Organick and Brown ( 3 2 ) and later developed by Hadden ( 1 4 ) . The well-known eightparameter Benedict-Webb-Rubin (BWR) equation of state ( 2 ) and the simple two-parameter Redlich-Kwong (R-K) equation of state ( 3 7 ) have been used to some extegt. Leland and co-workers ( 2 2 to 25) have developed a method to predict vapor-liquid equilibria based on the corresponding states principle. A method of correlation with the solubility parameter concept arid certain aspects of the corresponding states theor was given by Chao and tion is restricted to certain systems and limited temperature and pressure conditions. The purpose of this paper is to present a method to predict the phase behavior in binary systems containing methane and a relatively heavy component which can be paraffinic, naphthenic, or aromatic, such as n-heptane, methylcyclohexane, or toluene. Temperatures of interest in this correlation range from 330" to 500"R. and pressures from 100 to several thousand Ib./sq.in.abs. The highest pressure data used were at 3,822 Ib./sq.in.abs. and 492"R. for the methane-nnonane system. Extension of the general approach to multicomponent systems is underway.The method of correlating vapor-liquid equilibria data in this work is based on the separation of the deviations of the K value from ideality into deviations occurring in the vapor phase and liquid phase separately; these deviations are then correlated with thermodynamically consistent expressions. In this method, the vapor phase nonideality is calculated from the modified R-K equation of state (44, 4 5 ) ; the liquid nonideality is calculated with reference to the pure liquid components and the deviations from ideal solution laws. DESCRIPTION OF THE CORRELATIONSeader ( (Yi/+i)

Vapor-liquid equilibria of the methane-methylcyclohexane system at low temperatures and high pressures

“…A study of the comparative magnitudes of the K values of methane in the three solvents «-heptane, methylcyclohexane, and toluene at comparable values of temperatures and pressures has been presented (9). A comprehensive theory correlating the solubility of methane in the same three solvents has also been developed (2,3).…”