| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 102 === In this study, an apparatus which can be operated at high pressure and low temperature conditions was built and operated to measure the carbon dioxide hydrate of thermodynamics phase equilibrium and kinetics formation rate. In the thermodynamic part, this study used isochoric method to measure the carbon dioxide-hydrate-liquid water phase equilibrium boundary curve. In kinetics parts, using the pressurization in isochoric system to measure the formation rate and the amount of carbon dioxide hydrate. In this research, 1,3-Dioxane, Acetamide, and Cyclopentanol were chosen as additives.
In thermodynamic experimental results showed that the addition of 1,3-Dioxane in carbon dioxide system had effective promotion effects on formation of carbon dioxide in comparison with pure water system at a given pressure, and they could broaden the hydrates stability region. Furthermore, the promotion effect could increase as the concentration of additives increased. With the concentration of 20 wt% 1,3-Dioxane additives, the dissociation temperatures were increased about 7.8 K. With 20 wt% Acetamide, the equilibrium temperature decreased about 5 K at given pressure in comparisoon to that of pure water system. In addition, the hydrate dissociation conditions for brine systems with 3.5 wt% NaCl were also measured in this study. The promotion effect for carbon dioxide hydrate formation in brine environment was also observed with 1,3-Dioxane. However, the promotion effects in the presence of 1,3-Dioxane additives in the salt system was less than those in the pure water system. On the other hand, the inhibition effects were observed when adding Acetmaide in brine system, the equilibrium conditions shifted to higher pressure and lower temperature in comparison with pure water system.
Although the promotion effect of adding Cyclopentanol in carbon dioxide hydrate system was not good. It seemed that Cyclopentanol could increase the formation rate and decrease the induction time of carbon dioxide hydrates in thermodynamic experiments, so Cyclopentaonl was chosen as additive in kinetic experiments. The kinetic results proved Cyclopentaonl could reduce the induction time of forming carbon dioxide hydrates in comparison with pure water system, and the initial rate of hydrate formation was effectively increased by adding Cyclopentanol. In conclusion, Cyclopentaonl was effective kinetic promoter to form carbon dioxide hydrates in this work.
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