摘要
甲烷可以与水形成由大、小孔穴构成的I型水合物,该过程受温度的影响。采用分子动力学(MD)模拟方法,在等温等容(NVT)模拟条件下,研究了温度变化对水合物晶体及其中大、小孔穴结构及稳定性的影响。通过分子模拟分析晶体构型、氧原子均方位移、甲烷分子位移和相互作用能,结果表明:水合物晶体的稳定性受温度的影响较大,且其主要由大孔穴的稳定性决定;温度对大孔穴的结构及稳定性的影响较大,随着温度的升高,大孔穴稳定性明显降低,笼形结构变形增大,甚至出现坍塌,导致水合物分解;温度对小孔穴结构及稳定性的影响较小,相同条件下水合物中小孔穴的稳定性高于大孔穴的稳定性。研究成果可为水合物形成过程的控制、水合物快速分解、水合物稳定储存等提供理论基础。
Methane may combine with water to form type I hydrate which consists of large or small cavities. That process is influenced by temperature. With molecular dynamics （MD） simulation method, the influence of temperature changes on hydrate crystals, their cavities and stability is discussed, under the simulation condition of constant temperature and constant volume （NVT）. Crystal configuration, mean square displacement of oxygen atom, methane molecular displacement and interaction energy is analyzed through molecular simulation. Result shows that temperature has great influence on the stability of hydrate crystals, and it is mainly decided by the stability of large cavities. The structure and stability of large cavities is greatly affected by temperature. As temperature increases, the stability of large cavities decreases significantly, and the deformation of cavity structure increases. Collapse may even appear which causes the decomposition of hydrate. Temperature has less influence on the structure and stability of small cavities. The stability of small cavity in methane hydrate is better than that of large cavity under the same condition. Research results can provide theoretical basis for the control of methane hydrate formation process, rapid decomposition and stable storage of hydrate. （8 Figures, 1 Table, 31 References）
出处
《油气储运》
CAS
北大核心
2015年第12期1288-1294,共7页
Oil & Gas Storage and Transportation
基金
国家自然科学基金"水合物颗粒聚集动力学及流动安全研究"
51006120
高等学校博士学科点专项科研基金"天然气水合物生长动力学及快速形成机理研究"
20110133110004
关键词
水合物
分子模拟
稳定性
天然气
孔穴
methane hydrate, molecular simulation, stability, natural gas, cavity
