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采用分子动力学方法,模拟了273.15K下聚乙烯醇(PVA)对甲烷水合物的分解作用.研究发现,PVA浓度为2.7wt%时,水分子始终在其平衡位置附近波动,扩散系数仅为1.04×10-11m2/s;PVA浓度为5.2wt%时,水合物笼型结构坍塌,水分子以液态水的形式存在,甲烷分子从孔穴中逸出,聚乙烯醇的羟基在分子内部形成氢键,形成团簇,产生空间位阻,阻止了水分子再生成水合物,水分子的扩散系数1.61×10-9m2/s;PVA浓度为7.6wt%时,甲烷水合物周围有部分笼型结构被破坏,部分甲烷分子从孔穴中逸出,水分子扩散系数为3.55×10-10m2/s.得出聚乙烯醇对甲烷水合物的分解作用大小为:5.2wt%>7.6wt%>2.7wt%,为PVA溶液促进甲烷水合物分解实验研究提供参考.
The molecular dynamics simulation was used to simulate the decomposition of methane hydrate at 273.15K.The results showed that when the concentration of PVA was 2.7wt%, the water molecules always fluctuated near their equilibrium position, and the diffusion coefficient was only 1.04 × 10-11m2 / s. When the concentration of PVA is 5.2wt%, the hydrate cage structure collapses, and the water molecule exists in the form of liquid water. The methane molecules escape from the pores. The hydroxyl groups of the polyvinyl alcohol form hydrogen in the molecule Bond to form a cluster, resulting in steric hindrance to prevent the water molecules from being regenerated into hydrates. The diffusion coefficient of water molecules is 1.61 × 10 -9 m 2 / s. When the PVA concentration is 7.6 wt%, some cage structures around the methane hydrate Was destroyed, part of the methane molecules escaped from the pores, and the water molecule diffusion coefficient was 3.55 × 10-10m2 / s. The results showed that the decomposed effect of polyvinyl alcohol on methane hydrate was 5.2wt%> 7.6wt%> 2.7wt %, For the PVA solution to promote methane hydrate decomposition experimental study provide a reference.