III. - Equilibria between Liquid and Vapor Solutions of Paraffin Hydrocarbons

Souders, Mott; Selheimer, C. W.; Brown, George Granger

doi:10.1021/ie50269a012

Cited by 25 publications

(16 citation statements)

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“…The reduced-density effect becomes greater as one approaches the gaseous region, but for gases the radial distribution function can be treated effectively by simply expanding it in powers of density. This means that a very important simplification may be employed in evaluating the right side of Equation (21) or Equation (25) for liquid mixtures. The reduced molecular densities of the individual components which appear in the gzj functions each may be replaced, with little error, by the effective pure component value ( a 3 p y ) which appears on the left side of the equations.…”

Section: )mentioning

confidence: 99%

Prediction of vapor‐liquid equilibria from the corresponding states principle

1962

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A new ideal K value is defined which does not depend on the Lewis and Randall ideal solution rule but is derived only from composition dependent pseudo criticals and the corresponding states principle. Properties of the liquid and vapor mixtures are evaluated from either experimentally measured properties of closely related pure substances or from generalized tables of thermodynamic properties. A derivation of an improved pseudocritical expression applicable to liquids which may be approximated by simple spherical molecules is presented. The derivation illustrates the assumptions involved and points the way for a possible extension of the technique to more complex molecules. There are some advantages to this approach. It does not require the troublesome extrapolation of liquid properties into regions where no liquid can exist, a fact which is characteristic of K value calculations from the ideal solution rule. It is especially useful for systems in which an equation of state is not available for all of the components present. It avoids the difficulties in defining combination rules for complicated equations of state. Even for systems including very complex or moderately polar molecules it provides a base for subsequent empirical modification. This base follows the correct isotherm of In K vs. In P up to the actual critical of the system without the difficulties associated with defining a convergence pressure or evaluating the extremely large activity coefficient corrections to the ideal solution rule in the critical region. For mixtures of simple molecules the calculated ideal K value is within about 10% of the experimental value in both the low pressure and in the critical region. The entire calculation may be expressed completely analytically for use on a digital computer and may be coupled with an equilibrium flash calculation so that the ideal K values may be determined from a given overall composition, temperature, and pressure.

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Section: )mentioning

confidence: 99%

Prediction of vapor‐liquid equilibria from the corresponding states principle

1962

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“…The concept of the vapor-liquid equilibrium constant as the ratio of vapor and liquid compositions at equi-Iibrium K = y/x was introduced in 1932 by Souders, Selheimer, and Brown (19). If both phases behave as ideal solutions, and the vapor is an ideal gas, the equilibrium constant is equal to the ratio of the vapor pressure of the pure component to the total pressure of the system K = P"/T.…”

Section: Vinod S Mehra and George Thodosmentioning

confidence: 99%

The prediction of vapor‐liquid equilibrium constants for binary hydrocarbon systems in the critical region

Mehra

Thodos

1962

AIChE Journal

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A series of reduced state correlations for the prediction of equilibrium constants for the components of binary hydrocarbon systems have been developed utilizing experimental vapor‐liquid equilibrium data reported by Kay (7, 8, 9) for the enthane‐n‐heptane, ethane‐n‐butane, and n‐butane‐n‐hepane systems. Each correlation applies for a specific values of τ = Tbh/Tbl, the ratio of the normal boiling points of the two components. Plots of β/β° vs. TR covering the complete range of liquid compositions are presented for values of τ = 1.10, 1.20, 1.40, 1.60, 1.80, and 2.00. The term β° represents the reduced vapor pressure of the pure substance, while β is the ratio of the pseudo vapor pressure of this substance in the mixture, Kπ, to the critical pressure of the mixture. The correlations presented in this study reproduce the experimental data used in their development with an average deviation of 2.3% for forty‐eight points, with the experimental critical constants reported by Kay. The reliability of these correlations has been tested with the propane‐isopentane, methane‐ethane, and ethane‐cyclohexane systems which have τ values in the range included in this study and for which experimental critical constants are available. An average deviation of 5.1% was produced for thirty‐six points. In addition the systems methane‐propane, propane‐benzene, nitrogen‐oxygen, and carbon dioxide‐n‐butane were tested with calculated values for their critical constants and produced average deviations of 8.4, 8.2, 9.4, and 20%, respectively.

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“…For these calculations ami values for the standard state liquid b, ( l e ) fugacities were obtained from the gen-RT eralized data of Lyderson, Greenkorn, Consideration of Equations ( Q ) , (13),and Hougen ( 1 3 ). Note that for the ( I d ) ,(15), and (16) gives less volatile component standard state liquid fugacities of real liquids are involved because the pressure of the system is always equal to or greater than the vapor pressure of the less volatile component.…”

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

et al. 1962

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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 (

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III. - Equilibria between Liquid and Vapor Solutions of Paraffin Hydrocarbons

Cited by 25 publications

References 0 publications

Prediction of vapor‐liquid equilibria from the corresponding states principle

Prediction of vapor‐liquid equilibria from the corresponding states principle

The prediction of vapor‐liquid equilibrium constants for binary hydrocarbon systems in the critical region

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

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