添加N-甲基甲醯胺和4-甲基嗎啉對於甲烷水合物分解狀態與生成動力學影響之實驗量測

Measurements for the Dissociation Conditions and Formation Kinetics of Methane Hydrate in the Presence of 4- Methlymorpholine and N-Methylformamide

邵琬淳(Wan-Chun Shao)

指導教授 ： 陳延平

國立臺灣大學/工學院/化學工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.01055

摘要

本研究延續採用先前已建立之高壓設備裝置，並利用等容溫度循環法量測甲烷水合物分解之熱力學三相相平衡曲線 (H-Lw-V)，探討不同添加劑以及濃度對於甲烷水合物系統熱力學相平衡數據的影響。在水合物動力學部份，以等容先降溫後升壓之方法量測甲烷水合物，探討在不同變因下對於水合物的生成行為有何影響。
本研究選用添加劑為N-甲基甲醯胺 (N-Methylformamide) 及4-甲基嗎啉 (4-Methylmorpholine)，實驗結果顯示當N-甲基甲醯胺及4-甲基嗎啉存在時，使甲烷水合物相平衡曲線往低溫高壓移動，縮小水合物穩定形成的溫壓區域，達到熱力學抑制的效果，且此抑制效果亦隨著添加劑濃度增加而提升，添加30 wt% N-甲基甲醯胺時，約可抑制9 K；添加30 wt% 4-甲基嗎啉，約可抑制6 K。在水合物生成動力學部分，以壓力為變因，固定系統溫度的方式進行動力學實驗，並以過飽和梯度視為實驗趨動力。本研究以四氫呋喃(Tetrahydrofuran) 來進行實驗。實驗結果顯示，當趨動力越大時，水合物生成之誘導時間有越短的趨勢，水合物前半段的生成速率有較快的趨勢，平衡時甲烷所消耗的總量也有增加的趨勢，可以提升水合物的生成量。另外，動力學實驗以4-甲基嗎啉之水合物系統進行實驗量測，探討驅動力對甲烷水合物生成行為的影響。實驗結果顯示，系統初始驅動力較高，可縮短誘導時間，亦可提升水合物的生成量，對於水合物初始生成速率則無明顯的影響。

關鍵字

甲烷水合物 ； 熱力學相平衡 ； 等容溫度循環法 ； 水合物生成動力學 ； 4-甲基嗎啉 ； N-甲基甲醯胺 ； 四氫呋喃

並列摘要

In this study, an apparatus which can be operated at low temperature and high pressure conditions was set up to measure the hydrate-liquid water-vapor (H-Lw-V) three-phase dissociation conditions of methane hydrate in the presence of additives by employing the isochoric method. The certain additives to system of methane + water were investigated for their effects on the phase boundary of methane hydrate. Also, the kinetic behavior of methane hydrate was investigated in an isochoric system to see how factors (e.g. sub-cooling temperature, experimental pressure) would affect the formation kinetics of methane hydrate.

In this work, N-methylformamide and 4-methylmorpholine were chosen as additives. The addition of N-methylformamide and 4-methylmorpholine in methane hydrate system shifted hydrate phase boundaries to higher pressure and lower temperatureand thus the hydrate stability region was reduce. Furthermore, the inhibition effect increased when the concentration of N-methylformamide and 4-methylmorpholine in hydrate system increased. With 30 wt% N-methylformamide, the equilibrium temperature decreases about 9.05 K at given pressure in comparison to that of pure water system. With 30 wt% 4-methylmorpholine, the equilibrium temperature decreases about 6.85 K at given pressure in comparison to that of pure water system.

In the formation kinetics of methane hydrate, tetrahydrofuran was chosen as additive. With increasing degree of supersaturation, the results showed that tetrahydrofuran could shorten the induction time needed for hydrate formation. In addition, the kinetic experiment also chose 4-methylmorpholine as additive.

並列關鍵字

methane hydrate ； isochoric method ； dissociation condition ； formation kinetics ； tetrahydrofuran ； N-methylformamide ； 4-methylmorpholine

參考文獻

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