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Sampson CC, Metaxas PJ, Barwood MTJ, Stanwix PL, Johns ML, May EF. Aqueous Solid Formation Kinetics in High-Pressure Methane at Trace Water Concentrations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:4631-4641. [PMID: 36958053 DOI: 10.1021/acs.langmuir.2c03376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Natural gas containing trace amounts of water is frequently liquefied at conditions where aqueous solids are thermodynamically stable. However, no data are available to describe the kinetics of aqueous solid formation at these conditions. Here, we present experimental measurements of both solid formation kinetics and solid-fluid equilibrium for trace concentrations of (12 ± 0.7) ppm water in methane using a stirred, high-pressure apparatus and visual microscopy. Along isochoric pathways with cooling rates around 1 K·min-1, micron-scale aqueous solids were observed to form at subcoolings of (0.3-8.6) K, relative to an average equilibrium melting temperature of (253 ± 1.9) K at (8.9 ± 0.08) MPa; these data are consistent with predicted methane hydrate dissociation conditions within the uncertainty of both the experiment and model. The 36 measured formation events were used to construct a cumulative formation probability distribution, which was then fitted with a model from Classical Nucleation Theory, enabling the extraction of kinetic and thermodynamic nucleation parameters. While the resulting nucleation parameter values were comparable to those published for methane hydrate formation in bulk-water systems, the observed growth kinetics were distinctly different with only a small percentage of the water in the system converting into micron-scale solids over the experimental time scale. These results may help explain how cryogenic heat exchangers in liquefied natural gas facilities can operate for long periods without blockages forming despite being at very high subcoolings for aqueous solids.
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Affiliation(s)
- Catherine C Sampson
- Fluid Science & Resources, Department of Chemical Engineering, School of Engineering, University of Western Australia, 35 Stirling Hwy, Crawley 6009, Australia
- Future Energy Exports Cooperative Research Centre, 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - Peter J Metaxas
- Fluid Science & Resources, Department of Chemical Engineering, School of Engineering, University of Western Australia, 35 Stirling Hwy, Crawley 6009, Australia
| | - Mark T J Barwood
- Fluid Science & Resources, Department of Chemical Engineering, School of Engineering, University of Western Australia, 35 Stirling Hwy, Crawley 6009, Australia
- Future Energy Exports Cooperative Research Centre, 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - Paul L Stanwix
- Fluid Science & Resources, Department of Chemical Engineering, School of Engineering, University of Western Australia, 35 Stirling Hwy, Crawley 6009, Australia
| | - Michael L Johns
- Fluid Science & Resources, Department of Chemical Engineering, School of Engineering, University of Western Australia, 35 Stirling Hwy, Crawley 6009, Australia
- Future Energy Exports Cooperative Research Centre, 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - Eric F May
- Fluid Science & Resources, Department of Chemical Engineering, School of Engineering, University of Western Australia, 35 Stirling Hwy, Crawley 6009, Australia
- Future Energy Exports Cooperative Research Centre, 35 Stirling Highway, Perth, Western Australia 6009, Australia
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Lorenz RD. Raindrops on Titan. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1995; 15:317-320. [PMID: 11539245 DOI: 10.1016/s0273-1177(99)80103-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Some of the aspects of methane precipitation on Titan are considered. In particular, descent velocities are computed. It is found that raindrops fall much slower than on Earth. Additionally, the maximum size of raindrops on Titan is over 9 mm, compared with under 6 mm on Earth. The composition of drops will vary with altitude. Implications of these properties for Titan and the Huygens mission are considered.
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Affiliation(s)
- R D Lorenz
- Unit for Space Sciences, University of Kent, Canterbury, UK
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Rest AJ, Scurlock RG, Wu M. The solubilities of nitrous oxide, carbon dioxide, Aliphatic ethers and alcohols, and water in cryogenic liquids. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0300-9467(90)80041-a] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Hiraoka K. Determination of the stabilities of O3−(N2) , O3−(O2) , and O4−(N2) from measurements of the gas-phase ion equilibria. Chem Phys 1988. [DOI: 10.1016/0301-0104(88)87096-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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