添加1,3,5-三氧六環和四氫?喃甲醇對於甲烷水合物分解狀態之實驗量測

• Main Authors: 柯葳沂, Ko, Wei-Yi
• Other Authors: 臺灣大學: 化學工程學研究所, 陳延平
• Format: Thesis
• Language: Chinese; English
• Published: 2010
• Subjects: 甲烷水合物;等容溫度循環法;相平衡;1,3,5-三氧六環;四氫?喃甲醇;鹽水; Methane hydrate;isochoric method;dissociation condition;1,3,5-Trioxane;THFA;brine; Methane hydrate
• Online Access: http://ntur.lib.ntu.edu.tw/handle/246246/252405; http://ntur.lib.ntu.edu.tw/bitstream/246246/252405/1/ntu-99-R97524033-1.pdf

本研究使用一套高壓低溫的設備進行甲烷水合物熱力學性質之量測，主要研究甲烷＋純水＋添加劑之水合物系統的相平衡條件，以等容溫度循環法量測水相-水合物相-氣相共三相平衡之溫壓條件，探討當加入不同種類添加劑或改變添加劑濃度時，對於甲烷水合物相平衡邊界所產生的效應。本研究之動機為期望可以將所量測之數值作為基礎的數據資源，應用在氣體水合物開採、儲存及運輸工業，作為實際工程設計上的重要參考依據。 本研究選用1,3,5-三氧六環(1,3,5-Trioxane)和四氫呋喃甲醇(THFA)作為添加劑，實驗結果顯示當加入1,3,5-三氧六環至甲烷水合物系統中，會使得甲烷水合物相平衡曲線往溫度更高和壓力更低的方向移動，其具有促進甲烷水合物生成之效果，且促進效果隨著1,3,5-三氧六環添加濃度增加而提升，平衡溫度最高可增加約13 K。此外，為了模擬海水的環境，本研究也進行甲烷＋鹽水＋1,3,5-三氧六環之水合物系統相平衡條件的量測，由實驗結果發現當添加1,3,5-三氧六環至鹽水系統中亦有促進甲烷水合物生成之效果，但由於受到鹽分的影響，其促進效果較添加至純水系統時為低，平衡溫度最高可增加約12 K。另外，添加四氫呋喃甲醇則是使甲烷水合物相平衡曲線往溫度更低和壓力更高的方向移動，其具有抑制甲烷水合物生成之效果，同樣地，抑制效果隨著四氫呋喃甲醇添加濃度增加而提升，在給定的壓力下，平衡溫度最高可減少約5 K。 The thermodynamic properties of methane hydrate were measured with an apparatus which operated at high pressure and low temperature conditions. The liquid water-hydrate-vapor (Lw-H-V) three-phase dissociation temperatures and pressures for methane hydrate in the presence of additives were determined by employing the isochoric method. The certain additives to system of water + methane were investigated for their effects on the methane hydrate dissociation conditions. The motivation of this study was to establish the methane hydrate equilibrium database which could be applied on gas hydrate exploitation, storage and transportation. We hope the thermodynamic equilibrium data measured in this work can help for industrial design in the future. In this work, 1,3,5-Trioxane and THFA were chosen as additives. The addition of 1,3,5-Trioxane in methane hydrate system shifted the original hydrate phase boundaries to lower pressure and higher temperature and thus the hydrate stability region was broadened, therefore it had a promotion effect on the formation of methane hydrate. Furthermore, the promotion effect increased when the concentration of 1,3,5-Trioxane in hydrate system increased. With the concentration of 15 wt% 1,3,5-Trioxane additive, the dissociation temperature increased about 13 K at a given pressure in comparison to that of pure water system. In addition, the methane hydrate dissociation conditions for brine systems with 3.5 wt% NaCl were also measured in this study with the addition of 1,3,5-Trioxane. The promotion effect for methane hydrate formation in brine environments was also observed with 1,3,5-Trioxane additive. The dissociation temperature increased about 12 K at most at a given pressure in comparison to that of pure water system. However, the promotion effect in the presence of 1,3,5-Trioxane in the salt system was less than that in the pure water system. On the other hand, the results of adding THFA showed the inhibition effect on the formation of methane hydrate. The addition of THFA in methane hydrate system shifted the original hydrate phase boundaries to higher pressure and lower temperature. Similarly, the inhibition effect increased when the concentration of THFA in hydrate system increased. The dissociation temperature decreased about 5 K at most at a given pressure in comparison to that of pure water system.