Plug Formation and Dissociation of Mixed Gas Hydrates and Methane Semi-Clathrate Hydrate Stability
Gas hydrates are known to form plugs in pipelines. Hydrate plug dissociation times can be predicted using the CSMPlug program. At high methane mole fractions of a methane + ethane mixture the predictions agree with experiments for the relative dissociation times of structure I (sI) and structure II...
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University of Canterbury. Chemical and Process Engineering
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ftdatacite:10.26021/3369 2023-05-15T17:12:06+02:00 Plug Formation and Dissociation of Mixed Gas Hydrates and Methane Semi-Clathrate Hydrate Stability Hughes, Thomas John 2008 https://dx.doi.org/10.26021/3369 https://ir.canterbury.ac.nz/handle/10092/1579 unknown University of Canterbury. Chemical and Process Engineering Copyright Thomas John Hughes https://canterbury.libguides.com/rights/theses Gas Hydrates Clathrates Semi-Clathrate Dissociation DSC calorimetry CreativeWork article 2008 ftdatacite https://doi.org/10.26021/3369 2021-11-05T12:55:41Z Gas hydrates are known to form plugs in pipelines. Hydrate plug dissociation times can be predicted using the CSMPlug program. At high methane mole fractions of a methane + ethane mixture the predictions agree with experiments for the relative dissociation times of structure I (sI) and structure II (sII) plugs. At intermediate methane mole fractions the predictions disagree with experiment. Enthalpies of dissociation were measured and predicted with the Clapeyron equation. The enthalpies of dissociation for the methane + ethane hydrates were found to vary significantly with pressure, the composition, and the structure of hydrate. The prediction and experimental would likely agree if this variation in the enthalpy of dissociation was taken in to account. In doing the plug dissociation studies at high methane mole fraction a discontinuity was observed in the gas evolution rate and X-ray diffraction indicated the possibility of the presence of both sI and sII hydrate structures. A detailed analysis by step-wise modelling utilising the hydrate prediction package CSMGem showed that preferential enclathration could occur. This conclusion was supported by experiment. Salts such as tetraisopentylammonium fluoride form semi-clathrate hydrates with melting points higher than 30 ℃ and vacant cavities that can store cages such as methane and hydrogen. The stability of this semi-clathrate hydrate with methane was studied and the dissociation phase boundary was found to be at temperatures of about (25 to 30) K higher than that of methane hydrate at the same pressure. Article in Journal/Newspaper Methane hydrate DataCite Metadata Store (German National Library of Science and Technology) |
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Gas Hydrates Clathrates Semi-Clathrate Dissociation DSC calorimetry |
spellingShingle |
Gas Hydrates Clathrates Semi-Clathrate Dissociation DSC calorimetry Hughes, Thomas John Plug Formation and Dissociation of Mixed Gas Hydrates and Methane Semi-Clathrate Hydrate Stability |
topic_facet |
Gas Hydrates Clathrates Semi-Clathrate Dissociation DSC calorimetry |
description |
Gas hydrates are known to form plugs in pipelines. Hydrate plug dissociation times can be predicted using the CSMPlug program. At high methane mole fractions of a methane + ethane mixture the predictions agree with experiments for the relative dissociation times of structure I (sI) and structure II (sII) plugs. At intermediate methane mole fractions the predictions disagree with experiment. Enthalpies of dissociation were measured and predicted with the Clapeyron equation. The enthalpies of dissociation for the methane + ethane hydrates were found to vary significantly with pressure, the composition, and the structure of hydrate. The prediction and experimental would likely agree if this variation in the enthalpy of dissociation was taken in to account. In doing the plug dissociation studies at high methane mole fraction a discontinuity was observed in the gas evolution rate and X-ray diffraction indicated the possibility of the presence of both sI and sII hydrate structures. A detailed analysis by step-wise modelling utilising the hydrate prediction package CSMGem showed that preferential enclathration could occur. This conclusion was supported by experiment. Salts such as tetraisopentylammonium fluoride form semi-clathrate hydrates with melting points higher than 30 ℃ and vacant cavities that can store cages such as methane and hydrogen. The stability of this semi-clathrate hydrate with methane was studied and the dissociation phase boundary was found to be at temperatures of about (25 to 30) K higher than that of methane hydrate at the same pressure. |
format |
Article in Journal/Newspaper |
author |
Hughes, Thomas John |
author_facet |
Hughes, Thomas John |
author_sort |
Hughes, Thomas John |
title |
Plug Formation and Dissociation of Mixed Gas Hydrates and Methane Semi-Clathrate Hydrate Stability |
title_short |
Plug Formation and Dissociation of Mixed Gas Hydrates and Methane Semi-Clathrate Hydrate Stability |
title_full |
Plug Formation and Dissociation of Mixed Gas Hydrates and Methane Semi-Clathrate Hydrate Stability |
title_fullStr |
Plug Formation and Dissociation of Mixed Gas Hydrates and Methane Semi-Clathrate Hydrate Stability |
title_full_unstemmed |
Plug Formation and Dissociation of Mixed Gas Hydrates and Methane Semi-Clathrate Hydrate Stability |
title_sort |
plug formation and dissociation of mixed gas hydrates and methane semi-clathrate hydrate stability |
publisher |
University of Canterbury. Chemical and Process Engineering |
publishDate |
2008 |
url |
https://dx.doi.org/10.26021/3369 https://ir.canterbury.ac.nz/handle/10092/1579 |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_rights |
Copyright Thomas John Hughes https://canterbury.libguides.com/rights/theses |
op_doi |
https://doi.org/10.26021/3369 |
_version_ |
1766068864159842304 |