Liquid phase activity coefficients and standard state hypothetical liquid fugacities for hydrocarbons

Abstract

One method of predicting vaporization equilibrium ratios for the components of a multicomponent mixture is through the use of standard state liquid fugacities, standard state vapor fugacities, liquid phase activity coefficients, and vapor phase activity coefficients. The relationship among these variables will be shown.It is the purpose of this paper to present a method for evaluating the fugacities of the components of a multicomponent liquid mixture which is i n equilibrium with its vapors; t o present a method for evaluating the standard state fugacities of hypothetical liquids and to disclose these values for methane and ethane up to a reduced temperature of 1.6 and values for propane up t o a reduced temperature of 1.3; to Present the coincident derived values of the vaporization ' I parameters; and to show correlations of these equilibrium constants, Z factors, a-nd solubility values.The following definitions apply to the nonideal behavior of liquids and vapors:When the vapors and the liquid of a multicomponent mixture are in equilibrium at a given temperature and pressure, ( f i ) , and (fi). are equal. At equilibrium then through Equations (1) and ( 2 ) The ratio of the standard state fugacities is usually expressed as and is named the vaporization eqziilibrium constant. Equation (

The Corresponding States Principle—a Review of Current Theory and Practice

“…The technique of defining them is to extrapolate reduced correlations for liquid fugacities into regions above TB = 1 and likewise to extrapolate generalized vapor fugacities to predict hypothetical vapor states below Tb -1. Extrapolations of liquid fugacities above the critical and vapor fugacities below it have been made by Lewis and Kay (73), Souders, Selheimer, and Brown (130), Gamson and Watson (28), Prausnitz (99), Prausnitz, Edmister, and Chao (100), Hoffmann et al (45,46), and Lyckman, Eckert, and Prausnitz (76).…”

“…and '4<'>" E f f ^0)4'°'0)^(cos du)n3W(rh rt)dn dn (45) contribution at all to the thermodynamic properties. This term consists of all terms in Equation 39 except the one for which l\, fa, and m are all zero, and these terms all vanish when integrated over all values of the coordinate angles.…”

“…The reduced p2a term arises chiefly from the three-body second term in Equation 45 and only slightly from the perturbation. The other terms are defined in Table III.…”