Densities of compressed liquid methane, and the equation of state

Goodwin, Robert; Prydz, Rolf

doi:10.6028/jres.076a.010

Cited by 62 publications

(14 citation statements)

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“…For measurement on methane-rich liquid mixtures, pure methane has been used as the calibration fluid. A survey of saturated liquid methane densities indicated that the equation listed by Goodwin and Prydz (1972) as closelyafitting their experimental results should serve as a suitable basis. A preponderance of recent experimental evidence confirms these methane densities to within k0.15% for the tempera-* 101.325 kN m-2 = 1 atmosphere.…”

Section: Calibrationmentioning

confidence: 99%

Experimental liquid mixture densities for testing and improving correlations for liquefied natural gas

Rodosevich

Miller

1973

AIChE Journal

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Liquid molar volumes and excess volumes have been experimentally deterhned for some methane-rich binary and ternary mixtures containing ethane, propane, isobutane, and nitrogen between 91 and 115 K. A gas expansion type system calibrated against pure methane densities was used to make the necessary pure fluid and mixture measurements.The best of the available density correlations predicts the experimental methane-ethane molar volumes within k0.2yo, while larger systematic deviations are found for the methane-propane and methane-isobutane systems. Molar volumes for methane-nitrogen and ternary mixtures containing nitrogen diverge strongly from the correlation predictions at 108 K and higher temperatures. An empirical scheme is proposed for predicting molar volumes of methane-rich liquefied natural gases using reported methaneethane and methane-nitrogen excess volumes. This method predicts all binary and ternary molar volumes from this investigation within &O.l%. JAMES B. RODOSEVICH and REID C. MILLER Deportment of Chemical EngineeringUniversity of Wyoming Laromie, Wyoming 82070 SCOPELong distance transportation of liquefied natural gas (LNG) is increasing rapidly throughout the world. With domestic gas supplies projected to lag behind demands in many countries, the LNG industry should continue to gain importance in the future energy picture. Large scale custody transfer of LNG is posing new technical problems in the gas industry. Accurate liquid mixture densities are required to convert volumetric meter readings into market values, which are based on total heating values. A systematic error in estimated density of as little as 1% may amount to very serious monetary discrepancies ($15,00O/ocean tanker load by current standards).There are only a few published high-accuracy densities for liquid hydrocarbon mixtures containing more than 70 mole yo methane (Klosek and McKinley, 1968;Shana'a and Canfield, 1968). This data has been used in conjunction with mixture data outside this composition range and pure fluid data to develop an empirical density correlation (Klosek and McKinley, 1968; Boyle and Reece, 1971).To date, this LNG density correlation has not been satisfactorily tested. Correlation accuracy is probably a strong function of gas composition and temperature; however, this has never been established by independent experimentation. Two inherent problems need clarification. First, the accuracy of the experimental LNG densities needs to be checked by independent investigation. Additional data for typical compositions should be produced in this effort. Second, the present correlation simply applies a volume reduction correction to the ideal mixture molar volume. This correction is taken to be a function of average molecular weight of the mixture and temperature only, pressure and actual composition being ignored. Such a correlation may be too simple to achieve an accuracy approaching &O.lyo in the density, even for normal LNG variations in composition. A set of experiments designed to test the limits of such a cor...

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Section: Calibrationmentioning

confidence: 99%

Experimental liquid mixture densities for testing and improving correlations for liquefied natural gas

Rodosevich

Miller

1973

AIChE Journal

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“…The pressure and temperature are measured at filling and the density calculated from the PVT surface [10]. The amount of methane , N, is calculated from the volume V (T, P ) as previously determined [3 , 5].…”

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The specific heats, Cs, and Cv, of compressed and liquefied methane

Younglove¹

1974

J. RES. NATL. BUR. STAN. SECT. A.

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The specific heats, C u , of saturated liquid meth ane ha ve bee n meas ured at 66 te mperatures in th e temperature ran ge 95-187 K. Th e s pecific heats at constant volume , C 1', have been measured at 20 dens iti es ran ging from 0.8 to 2.8 times the c ritical de nsity, a t temperatures betwee n 91 and 300 K , and a t pressures to 330 bar (at 280 PVT states in all). Th e un ce rtainty of most of th e meas ureme nts is es t;mated to be less than 0.5 perce nt , except near th e c riti cal point. These meas ure me nts were pe r· form ed prim aril y to provide input data for accurate th e rmod ynam ic pro pe rti es data ca lc ul at io ns for liquid meth a ne. Th ey are beli e ved to be th e most co mpre he nsive s pecifi c heat meas ure me nts avai lable for pure co mpressed gaseous a nd liquid methan e .

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“…Six calibration runs were made on pure methane. The resulting molar volumes were forced to agree with the saturated liquid data of Goodwin and Prydz (1972) by least squares determination of two equipment constants as described previously (Liu and Miller, 1972). Similarly, the methane saturated liquid dielectric constants of Straty and Goodwin (1973) were used to evaluate the stray capacitance ( CS) in Equation (1).…”

Section: Experimental Methodsmentioning

confidence: 99%

Dielectric constants and Clausius‐Mossotti functions for simple liquid mixtures: Systems containing nitrogen, argon and light hydrocarbons

1975

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Dielectric constants and Clausius-Mossotti functions (CM) have been determined for selected pure components, binary mixtures, and ternary mixtures at temperatures between 91 and 115 K and pressures near saturation. Excess Clausius-Mossotti functions (CME) have been calculated from the pure fluid and mixture values.Mixture CME values are found to be generally less than 0.1% of the mixture CM values for systems containing only nonpolar species. Thus, dielectric constant measurements can be conveniently used as substitute density measurements for simple liquid mixtures. Rodosevich and Miller, 1973, 1974;Mollerup and Rowlinson, 1974). However, compositions and temperatures are difficult to measure within the required tolerances. It would often be highly desirable to determine quickly or monitor continuously liquid mixture molar volumes by use of some relatively simple device.Dielectric constant measurements can be used to indirectly determine molar volumes. A particular combination of the dielectric constant and the molar volume, termed the Clausius-Mossotti function (CM), is found to undergo changes of only a few percent as a simple fluid is taken from the ideal gas at high temperatures to the saturated liquid near the triple point. For an ideal gas mixture the CM function is rigorously given by the mole fraction average of the pure component values. If this same relationship is sufficiently accurate for liquid mixtures, that is, if CM" is very nearly zero, then measurements of composition and dielectric constant can be readily used to obtain molar volumes. In addition, if pure component CM values are proportional to heating values for the components of a liquefied natural gas, it will be possible to use dielectric constant measurements alone to convert a total volume measurement directly into total heating value, the basis for sale of such commodities.To test the above conjectures, the present investigation was designed to provide a consistent set of low temperature dielectric constants and Clausius-Mossotti functions for some relatively simple liquids and liquid mixtures, including components and mixtures of interest relative to liquefied natural gas. Previous results are available in the same temperature range for some of the pure components (Ar, N2, and CHI). No previous results appear to be available for the mixtures. CONCLUSIONS AND SIGNIFICANCEThe mixture results indicate that the excess ClausiusMossotti function (CME) is less than 0.1% of the mixture CM value for saturated liquid mixtures composed of simple nonpolar species. For such mixtures a dielectric constant measurement may be used as a substitute for a density measurement, if the composition and pure component CM values are known. This experimental approach Correspondence concerning this paper should be addressed to R. C. Miller. could reduce the effort required to determine the PVT surface for a fluid mixture.Pure component results for propane and isobutane indicate that their small permanent dipole moments are of sufficient magnitude to effect t...

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Densities of compressed liquid methane, and the equation of state

Cited by 62 publications

References 10 publications

Experimental liquid mixture densities for testing and improving correlations for liquefied natural gas

Experimental liquid mixture densities for testing and improving correlations for liquefied natural gas

The specific heats, Cs, and Cv, of compressed and liquefied methane

Dielectric constants and Clausius‐Mossotti functions for simple liquid mixtures: Systems containing nitrogen, argon and light hydrocarbons

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