| Summary: | 碩士 === 長庚大學 === 化工與材料工程學系 === 101 === Gas hydrates, which are usually formed under high pressure and low temperature, are ice-like crystalline solids that are composed of networks of water and small molecules, e.g., methane, ethane and carbon dioxide. The water molecules form large polyhedral cavities, which are occupied and stabilized by small molecules. The emissions of carbon dioxide have recently increased to high levels, leading to significant climatological changes due to the greenhouse effect. To reduce the atmospheric level of carbon dioxide, ocean disposal is proposed. Carbon dioxide can be stored as hydrates with simultaneous conversion of in situ methane hydrates into natural gas.
The hydrate crystallization process is subdivided into the nucleation and growth. The induction time in gas hydrate crystallization is an important characteristic of the kinetics of the process. In this study, the effects of operating parameters, including temperature and pressure, on the induction time of carbon dioxide hydrate formation are investigated using a batch stirred tank reactor. In addition, the effects of some impurities on the induction time of carbon dioxide hydrate formation are also explored. It is found that sodium dodecyl sulfate can reduce the induction time and promote carbon dioxide solubility significantly. On the other hand, low concentration ethanol can reduce the induction time, but high concentration ethanol can increase the induction time and retards carbon dioxide hydrate formation.
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