氣體水合物技術在天然氣水合物開采

1、摘 要氣體水合物技術在天然氣水合物開采、蓄冷、二氧化碳分離及深海儲藏、氣體儲運、海水淡化等領域具有潛在的廣闊應用前景。氣體水合物技術的應用與氣體水合物生成驅動力、生成速率、生成過程等生成動力學基礎問題密切相關。目前，國內外氣體水合物生成動力學的研究尚處于初級階段，氣體水合物生成過程中生成驅動力存在許多爭議。本文在分析與比較前人氣體水合物生成驅動力公式的基礎上，選擇摩爾吉布斯自由能變表征氣體水合物生成驅動力，并對氣體水合物生成過程中生成驅動力做了初步研究，具體研究內容和結果如下：（1）通過計算等溫條件下純水中純組分氣體（甲烷、乙烷、丙烷、二氧化碳和硫化氫）的生成驅動力和3.5%NaCl溶液中甲烷

2、和二氧化碳水合物生成驅動力，理論分析二氧化碳置換海底甲烷氣體的動力學可行性，并就壓力、溫度等參數(shù)對氣體水合物生成驅動力的影響做了定量分析。結果表明：氣液系統(tǒng)水合反應摩爾吉布斯自由能變隨壓力的增大非線性減小，即單位壓力的增加對生成驅動力的貢獻不一樣，壓力對甲烷和二氧化碳水合物生成驅動力的影響可分為兩個階段。（2）利用自行設計的一套可視化實驗裝置觀測了丙烷水合物在純水、1950 ppm十二烷基硫酸鈉（SDS）溶液、400ppm十二烷基苯磺酸鈉（SDBS）溶液中的生長過程，研究了水合反應中壓力、溫度、水合物的生長厚度、反應速率、生成驅動力等參數(shù)變化。通過對比純水和表面活性劑溶液中的水合物生成實驗，發(fā)

3、現(xiàn)有/無表面活性劑溶液中的水合物生成情況有很大區(qū)別：無表面活性劑存在時，水合物首先在兩相界面生成，水合反應緩慢且不充分；添加表面活性劑后，水合物生長速度加快，水合物完全生成。顯然，表面活性劑可以有效的降低水合反應物兩相界面張力，減小了氣液界面的比表面積，使氣體分子更容易進入液相中，促進了氣體水合物的生成。（3）根據(jù)理論計算得到的驅動力數(shù)值與實驗所得的水合反應速率數(shù)據(jù)，擬合以常數(shù)、冪函數(shù)和雙曲線函數(shù)的線性組合函數(shù)表征的氣液系統(tǒng)水合物生成動力學模型。純水中氣-液界面上水合物層的厚度呈階梯性生長，水合反應速率與驅動力都存在先增長后保持穩(wěn)定的趨勢，并且兩者隨著反應的進行呈常數(shù)、冪函數(shù)和雙曲線函數(shù)的線性

4、組合擬合函數(shù)趨勢變化。本文認為靜態(tài)條件下水合物生長緩慢且不充分并且水合物在生長后期存在穩(wěn)定階段的原因取決于鎧甲效應、水合反應相變熱以及壓力對一定溫度和容積條件的氣液系統(tǒng)水合物結晶過程影響的綜合效果。本文的創(chuàng)新點和意義在于：（1）首次得到以摩爾吉布斯自由能變表征的靜態(tài)條件下氣液系統(tǒng)丙烷水合反應驅動力數(shù)據(jù)；（2）首次得到了丙烷水合物層生長過程中溫度、壓力、厚度，水合反應速率及生成驅動力等動力學重要參數(shù)，并擬合氣液系統(tǒng)中丙烷水合物生長動力學模型；力學生長啊e formation driving force ormation in （3）歸納并完善靜態(tài)條件下氣體水合物生長規(guī)律，補充靜態(tài)條件下純水中水合

5、物生長過程中存在穩(wěn)定階段。 氣液系統(tǒng)水合反應規(guī)律為界面水合反應和水合物技術工業(yè)化應用的研究提供了一定的理論基礎，具有極大地參考意義。關鍵詞：氣體水合物；生成動力學；驅動力；丙烷；氣液系統(tǒng)AbstractThe technology of gas hydrate has extensive application foreground in the fields of gas hydrate exploitation, store up cool,carbon dioxide storage deposited in seabed, natural gas transportation by t

6、he form of solid, sea aqueous solution desalination and other areas of industry. The application of gas hydrate is tight related to formation driving force, formation velocity and other foundation problem.Presently, the research of gas hydrate kinetics still at primary state.There are many disputes

7、on the question of driving force. This passage characterizes driving force of gas hydrate formation by the use of molar Gibbs free energy difference, preliminary study formation driving force during gas hydrte growth. Material contents and results as follow:(1) It gets the driving force of gas hydra

8、te formation of simple component gas (methane, ethane, propane, carbon dioxide and sulfureted hydrogen) and methane and carbon dioxide in 3.5% sodium chloride solution in pure aqueous solution on the condition of isothermal. It analyses theoretically kinetic feasibility, which using carbon dioxide s

9、ubstitute methane in seabed. It also quantitative analyses the impacts of pressure and temperature on driving force of hydrate reaction. The results indicates that molar Gibbs free energy difference of hydrate reaction does not minish with pressure as linearity for gas and liquid system. The gradien

10、t of molar Gibbs free energy difference changes along with pressure increase.That is the contribution of increase of unit pressure for driving force has changed. It can be plot out two trends for methane and carbon dioxide hydrate formation driving force.(2)It observes the hydrate growth process for

11、 gas and liquid system, taking propane for example, using a suit of experiment installation and experiment measure, which designed by self. The experiment proceed in pure water，sodium dodecyl sulfate of 1950ppm, sodium dodecyl benzene sulfonate of 400ppm. It attends the changing of pressure and temp

12、erature during the whole reaction and important parameters of thickness, reaction velocity, driving force etc. There is great difference on hydrate interface formation reaction if surface active agent exist.When there is not surface active agent, hydrate formation just happen at the interface layer.

13、 Hydrate reaction slow and insufficiency. When appending surface active agent, it grows mass hydrate and reaction thoroughly. It forms solid hydrate entirety indeed. By all appearances, surface active agent can reduce interfacial tension of two kinds of reactant, minish specific suiface area between

14、 interface of gas and liquid effectively, which make gas molecule enter into liquid phase easily, promote hydrate formation.The thickness of gas and liquid interface hydrate layer growth as ladder in pure water. )e question of ollow:ce during gas hydrte growth.(3)It fits kinetics model using linear

15、combines function of constant, power function and hyperbolic function, based on academic calculation numerical value of driving force and hydrate reaction velocity from experiment. The thickness of hydrate layer growth as ladder.There are both increase firstly then keep steady on hydrate reaction ve

16、locity and driving force. They both change as linear combine function of constant, power function and hyperbolic function during reaction.It believes that the reason of hydrate growth slowly and insufficiency at state of static lie on the compositive effect of loricae effect, heat of transformation

17、of hydrated reaction, the influence of pressure on hydrate crystal process in gasous-liquid system with a given condition of temperature and pressure.The innovation point and significance is:(1)The data of hydrate reaction driving force at static state of gas and liquid system were obtained for the

18、first time, which using mol Gibbs free energy change express;(2) The important dynamics parameters of temperature, pressure, thickness, hydrate reaction velocity and driving force during process of peopane hydrate layer growth were obtained for the first time. It fits propane hydrate growth dynamics model of gas and liquid system;(3) The gas hydrate growth disciplinarian at static state was concluded and perfected. It renews that thereis tranquilization phase in hydrate growth process at static state in pure water。The law of hydrate r