GIEC OpenIR  > 中国科学院广州能源研究所
Alternative TitleStudy on the Phase Equilibrium of Natural Gas Hydrate in the Porous Media
Thesis Advisor李小森
Degree Grantor中国科学院广州能源研究所
Place of Conferral广州能源研究所
Degree Name硕士
Keyword天然气水合物 多孔介质 相平衡
Abstract天然气水合物作为一种潜在的替代能源,已经受到人们越来越多的关注,据估计,地球上天然气水合物的储量相当于已知所有化石燃料的两倍。多孔介质中天然气水合物的相平衡研究对于了解海洋中水合物的特性具有重要的意义,为未来海洋水合物的开采提供基本的理论依据。 本课题包括理论模拟与实验两个部分,其中在理论模拟部分,对不同的研究者提出的热力学模型及预测结果进行了分析比较,并利用两种热力学方法(基于逸度相等的方法与基于活度相等的方法)预测了不同多孔介质中气体水合物的平衡分解条件,对于非水合物相,逸度方法采用Trebble-Bishnoi(TB)方程,而活度方法则使用Soave-Redlich-Kwong(SRK)方程,对于水合物相,两种方法都利用了van der Waals-Platteeuw模型结合Llamedo等关于毛细管力作用模型来模拟。两种方法的预测结果与实验结果吻合,逸度方法的预测效果要好于活度方法。 在实验部分,自行研制开发了气体水合物热、动力学实验系统。本实验系统可分别进行纯水合物及多孔介质中气体水合物的热力学与动力学实验。该系统包括热动力学模拟模块、稳压供液模块、稳压供气模块、温度控制模块、压力控制模块和计量模块。热动力学模拟模块为一可变容积的可视反应釜,反应釜最大有效容积为500cm3,最大工作压力为20MPa;温度控制模块为一高精度的恒温水浴,精度可达±0.1K;反应釜中的温度由铂电阻测量,精度为±0.05K,压力由压力传感器测量,精度为±0.02MPa。本实验所用气体为纯甲烷气体,纯度达到99.9%。 在进行多孔介质中的水合物相平衡实验前,先分别利用观察法与画图法对甲烷水合物在纯水中的相平衡条件进行了测量,实验结果与文献中的数据吻合的很好,表明了实验系统是可靠的。在多孔介质中甲烷水合物相平衡实验中,采用了平均孔径12.9nm的硅胶。分别在不同的压力下使用逐步升温法与连续升温法进行了实验,不同的升温方法对实验的结果也会有较大的影响。实验的结果表明,由于毛细管力的影响,水合物在多孔介质中的生成压力会有较大的升高。同时利用上述模型对该实验体系进行预测,预测的结果与实验数据相当吻合。
Other AbstractAs a potential energy source, the natural gas hydrate is attracting more and more attention. As estimated, the hydrate resource on the earth is twice as great as the combined fossil fuel reserve. Phase equilibrium studies of natural gas hydrate systems in porous media are of significance for understanding the characteristics of the hydrate in marine deposits, and provide the data and theoretical reliability for their future exploitation. We employed two thermodynamic approaches, based on equal fugacities and based on equal activities, to predict the gas hydrate equilibrium dissociation conditions in the porous media. For the non-hydrate phase, we used the Trebble-Bishnoi equation in the fugacity approach and the Soave-Redlich-Kwong equation in the activity approach. For the hydrate phase, the van der Waals-Platteeuw model incorporated with the capillary model of Llamedo et al was used in both approaches. The predictions are found to be in satisfactory to execllent agreement with the experimental data. The predictive ability of the fugacity approach is better than that of the activity approach. In order to measure natural gas hydrate equilibrium conditions, the experimental apparatus was designed and developed. Both of equilibrium conditions of the bulk hydrate and the hydrate in the porous media can be measured with this apparatus. The equilibrium cell of this apparatus is a visible and volume-variable cell with a movable piston. The maxium volume of the cell is 300cm3, and its highest pressure is 20MPa. The cell pressure was measured using absolute pressure transducer (0-20MPa) with the accuracy about ±0.02MPa. The cell temperature was measured using a Pt100 RTD with the accuracy of ±0.05K. The gas used is methane with purity of 99.9%. Before the experiment of the hydrate phase equilibria in the porous media was done, the experiment in bulk hydrate was carried out. The results are in good agreement with experimental data in the literature. This shows that the apparatus in this work is reliable. In the experiments of methane hydrate phase equilibria in porous media, the silica gel with 12nm mean pore diameter was used. The experiments were carried out using the step-heating method and the continuous heating method. The results show that the equilibrium pressure of the hydrate in porous media is higher than that in the bulk, and the equilibrium pressure increase with the decrease of the mean diameters of the pores. The heating method will also affect experiment results. In addition, the fugacity model was employed to calculate equilibrium dissociation condtion for the above system. The predicted results have a good aggrement with the experimental data.
Document Type学位论文
Recommended Citation
GB/T 7714
张郁. 多孔介质中天然气水合物相平衡研究[D]. 广州能源研究所. 中国科学院广州能源研究所,2007.
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