Activity Coefficients of Gases

Newton, Roger Hale

doi:10.1021/ie50303a014

Cited by 77 publications

(32 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Newton (19) was the first to suggest that hydrogen and helium could be brought into line with other gases by replacing their true critical constants with effective critical constants. Newton's procedure considerably improves P-V-T correlations for hydrogen and helium at above room temperature but gives poor results at lower temperatures.…”

Section: Applications To Systems Containing Hydrogenmentioning

confidence: 99%

Correlation and prediction of vapor‐liquid equilibria with the redlich‐kwong equation of state

1970

View full text Add to dashboard Cite

ent research:1. Theoretical rate equations have been derived for liquid phase mass transfer accompanied by first-order complex chemical reactions. The kinetics considered is a combination of consecutive, reversible, and parallel chemical reactions.2. The film-penetration model has been shown to be a general model among the theories considered. I t takes the film theory and the surface renewal theory as the lower and upper limits, respectively, in the theoretical predictions.3. The ratio of chemical to physical mass transfer coefficients is smaller than that for mass transfer with a firstorder irreversible reaction. The theories deviate significantly for cases where the reversible reaction is strong, and the diffusivities of the intermediate product and the reactant are quite different.

show abstract

Section: Applications To Systems Containing Hydrogenmentioning

confidence: 99%

Correlation and prediction of vapor‐liquid equilibria with the redlich‐kwong equation of state

1970

View full text Add to dashboard Cite

show abstract

“…Nevertheless, it seems clear that numerical results based on an ideal gas model are only speculative below 300øC; only the results given here for •emperatures above 600øK (327øC) are considered as reasonable approximations •o the actual behavior of •he system. Although there are no data available for fugaci•y coeiticients of the various species in mixtures, values of 7• for individual species have been compiled as functions of temperature and pressure for CO• [Kennedy, 1954;Robie, 1962], CO [Newton, 1935], H20 [Anderson, 1964], H2 [Shaw and Wones, 1964], and CH• [Douslin et al, 1964]. A closer approximation to the actual behavior of •he gas phase could be made by assuming tha5 values of • in the mixture are the same as the values for the pure species at the same temperature and pressure (Lewis and Randali's rule; see Denhigh, [1957]).…”

Section: Ideal Behavior O• the Gas Phasementioning

confidence: 99%

“…Available data on the fugacity coefficients of the pure species indicate that, above 500øK, values of • lie within the range 0.7-3.0. This variability will be reduced because the fugacity coefficients appear in (7) as ratios, and values of "Yi will tend to be similar for the same temperature and pressure [Newton, 1935].…”

Section: Ideal Behavior O• the Gas Phasementioning

confidence: 99%

Some geological implications of equilibrium between graphite and a C‐H‐O gas phase at high temperatures and pressures

French¹

1966

Reviews of Geophysics

271

110

View full text Add to dashboard Cite

The occurrence of graphite as a common accessory mineral in meteorites and in terrestrial metamorphic and igneous rocks gives particular importance to the study of equilibrium between graphite and a coexisting gas phase. By using a simplified model in which T, Pgas, and fO2 are independently specified for the system C‐H‐O, values of PCO2, PCO, PH2O, PH2 and PCH4 in a gas phase in equilibrium with graphite have been calculated for a wide range of geologically possible conditions by means of a high‐speed computer. The numerical results support the following general conclusions: (1) The assumption that Pgas = PH2O + PCO2 is significantly in error for many graphite‐bearing mineral assemblages. (2) Methane, CH4, may be a significant to dominant constituent of the gas phase in many possible geological environments involving moderate reduction; in particular, the occurrence of graphite with reduced minerals such as fayalite, wüstite, and iron is indicative of a methane‐rich gas phase. (3) Under metamorphic conditions, pure water is not stable with graphite, but graphite can coexist with a gas phase rich in CO2. (4) Original graphite in a sediment will stabilize increasingly reduced mineral assemblages during progressive thermal metamorphism. (5) The presence or absence of even small amounts of graphite can explain PO2 gradients observed over short distances or between adjacent layers in metamorphic rocks. (6) It is possible that the terrestrial atmosphere could have evolved by conversion of original methane to water and CO2 by reaction with graphite and other accessory minerals within the primordial earth at temperatures of 600° to 1000°C. Material requirements for such a conversion are not unreasonable, and the process itself is consistent with many proposed models for the origin of the earth.

show abstract

“…12−15 In practice, to compensate for this limitation, binary interaction parameters between quantum gases and other compounds tend to be set much larger than normal. 16,17 As discussed by Prausnitz and co-workers 13,14 and recognized much earlier, 12 the corresponding states approach works well for classical gases but fails for gases whose critical properties are influenced by quantum phenomena. This problem is most severe for helium because it has one of the lowest critical temperatures of any gas (5.1953 K).…”

Section: ■ Introductionmentioning

confidence: 93%

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

2017

View full text Add to dashboard Cite

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.

show abstract

Activity Coefficients of Gases

Cited by 77 publications

References 2 publications

Correlation and prediction of vapor‐liquid equilibria with the redlich‐kwong equation of state

Correlation and prediction of vapor‐liquid equilibria with the redlich‐kwong equation of state

Some geological implications of equilibrium between graphite and a C‐H‐O gas phase at high temperatures and pressures

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

Contact Info

Product

Resources

About