Liquid‐vapor equilibrium in the system helium‐methane

Heck, C. K.; Hiza, M. J.

doi:10.1002/aic.690130335

Cited by 28 publications

(7 citation statements)

References 6 publications

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“…An example for isothermal data near 124 K is shown in Figure 2. It can be seen that the data sets of Heck and Hiza, 31 DeVaney et al, 32 and Rhodes et al 33 are mostly consistent, but the data of Sinor et al 30 are systematically too high and the data from Fontaine 34 exhibit large internal scatter. As cubic equations of state are known to behave poorly near mixture critical points, 11 the pTxy data for (methane + helium) above 190 K were also eliminated from consideration.…”

Section: ■ Methodsmentioning

confidence: 84%

“…Peng–Robinson equation of state predictions with true critical constants T c = 5.1953 K, P c = 0.22746 MPa, ω = −0.365, and k ij = 0 (dashed lines) and effective critical constants T c = 11.73 K, P c = 0.568 MPa, ω = 0.0, and k ij = 0 (solid lines). Data points from Heck and Hiza . (b) Deviations (log K expt – log K calc ) where K expt values are critically selected data for (methane + helium) (Method section) and K calc values are calculated with the Peng–Robinson equation of state using true critical constants T c = 5.1953 K, P c = 0.22746 MPa, ω = −0.365 and k ij = 0.…”

Section: Resultsmentioning

confidence: 99%

“…As cubic equations of state are known to behave poorly near mixture critical points, 11 the pTxy data for (methane + helium) above 190 K were also eliminated from consideration. This left 128 data points suitable for parameter regression from the data sets of Heck and Hiza, 31 DeVaney et al, 32 and Rhodes et al 33 The objective function used throughout this work was the absolute average deviation (AAD) between the experimental and calculated distribution K factors (K i ≡ y i /x i ) calculated according to…”

Section: ■ Methodsmentioning

confidence: 99%

“…As cubic equations of state are known to behave poorly near mixture critical points, the pTxy data for (methane + helium) above 190 K were also eliminated from consideration. This left 128 data points suitable for parameter regression from the data sets of Heck and Hiza, DeVaney et al, and Rhodes et al…”

Section: Methodsmentioning

confidence: 99%

“…GERG-2008 61 equation of state predictions (blue dashed− dotted lines). Data points from Heck and Hiza 31.…”

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confidence: 99%

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Effective Critical Constants for Helium for Use in Equations of State for Natural Gas Mixtures

2017

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Most of the world’s helium supply is obtained by the cryogenic distillation of natural gas. Modeling the distillation conditions requires equations of state capable of predicting vapor–liquid equilibria over wide ranges of conditions. Equations of state, including cubic equations and multiparameter Helmholtz models, depend on the critical properties of pure substances for predicting various properties of multicomponent fluid mixtures. Predictions for helium are problematic as its critical point (5.195 K, 0.2275 MPa) is influenced strongly by quantum effects; large, empirical interaction parameters tend to be used in equations of state to compensate for these effects. Prausnitz and co-workers proposed an alternative approach using effective critical constants for quantum gases but demonstrated it for only three helium-containing binary mixtures. Here, we demonstrate that the use of an effective critical point at (11.73 K, 0.568 MPa) for helium substantially improves the prediction of VLE by the Peng–Robinson equation of state for 15 binary and 2 ternary mixtures, including the major components of natural gas. This effective critical point for helium was selected from a critical analysis of pTxy data for the (methane + helium) binary. The effective critical constants for helium are compatible with an acentric factor near zero, as expected for a small spherical molecule and similar to the acentric factors of heavy noble gases. The possibility of applying this approach to address recognized limitations of the GERG-2008 equation of state is discussed.

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Section: ■ Methodsmentioning

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Section: ■ Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…GERG-2008 61 equation of state predictions (blue dashed− dotted lines). Data points from Heck and Hiza 31.…”

mentioning

confidence: 99%

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Effective Critical Constants for Helium for Use in Equations of State for Natural Gas Mixtures

2017

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Water Content of Carbon Dioxide – A Review

Grynia

Ambrożek

2019

The Three Sisters

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A correlation for the prediction of interaction energy parameters for mixtures of small molecules

Hiza¹,

Duncan²

1970

AIChE Journal

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Low temperature, phase-equilibria data for binary systems containing hydrogen, helium, and neon were used to develop a correlation relating deviations from the geometric mean combining rule for the characteristic energy parameter to the ionization potentials of the component species. With the exception of oxygen systems, this relatively simple relationship correctly predicts published deviations, determined by different methods, for a number of systems within expected uncertainties. It is shown that consideration of attractive forces only, os done by Hudson and McCoubrey, is inadequate for such predictions.The development of a satisfactory method of relating parameters for unlike molecule interactions to those for like molecule interactions has been hampered in the past by the lack of appropriate data of sufficient accuracy to provide tests for fundamental relationships.Recent measurements provide data of this type for a complete set of nine binary systems containing hydrogen, helium, and neon, with three different light hydrocarbons as the second component. These data are particularly valuable below the normal boiling point temperature of the condensable component, where assumptions made to simplify models representing the gas-phase compositions are most nearly satisfied. It was found that for the neon and helium systems, predictions of gas-phase compositions by means of an expression based on the virial equation and commonly used combining rules are in error by as much as an order of magnitude, even though excellent pure component parameters are used. Based on these results and others critically selected from the literature, a correlation has been developed relating the deviation from the geometric mean combining rule klz to the ionization potentials of the pure components in the binary mixture. E X P E R I M E N T A L VALUES OF k l zA convenient way to represent the gas phase for systems such as these is in the form of enhancement factors, that is, the ratio of partial pressures to the vapor pressure of the condensable component. Enhancement factors (for the case of an incompressible, pure, condensed phase of component 1 and an essentially pure gas phase of component 2 ) can be represented isothermally with the following expression based on the virial equation of state:Owing to assumptions made in the derivation of this expression, it is rigorous only in the solid-vapor region. However, it is also applicable between the triple point and normal boiling point temperatures (where isothermal, liquid-phase compressibility is insignificant) for systems in which the solubility of gas in the liquid is no more than a few percent.Values of the interaction second virial coefficient B I Z were obtained for the binary systems of hydrogen, helium, and neon with ethylene, ethane, and methane by a leastsquares fit of the data, below the boiling point of the condensable components, to Equation (1). For most of the data, terms containing virial coefficients higher than the third were not needed to obtain a fit within experiment...

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Liquid‐vapor equilibrium in the system helium‐methane

Cited by 28 publications

References 6 publications

Effective Critical Constants for Helium for Use in Equations of State for Natural Gas Mixtures

Effective Critical Constants for Helium for Use in Equations of State for Natural Gas Mixtures

Water Content of Carbon Dioxide – A Review

A correlation for the prediction of interaction energy parameters for mixtures of small molecules

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