Methane hydrate crystal growth in a porous medium filled with methane-saturated liquid water
Methane hydrate crystal growth in a porous medium filled with methane-saturated liquid water
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DOI：
10.1080/14786430601021652
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发表时间：
2007-03
影响因子：
1.6
通讯作者：
D. Katsuki;R. Ohmura;T. Ebinuma;H. Narita
中科院分区：
文献类型：
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作者：
D. Katsuki;R. Ohmura;T. Ebinuma;H. Narita
用肉眼观察了甲烷预饱和的多孔介质中甲烷水合物晶体的成核、生长和老化过程。多孔介质的孔隙尺寸为1.0 × 102 µm。水合物形成开始时的压力-温度条件分别对应于3.4 K、6.7 K、12.3 K和14.1 K的系统过冷度，其中系统过冷度表示在给定压力下系统温度与三重甲烷-水合物-水平衡温度之差。当过冷度小于或等于6.7K时，水合物晶体在没有液态水层的情况下生长并桥接孔隙空间。刻面晶体可以与多孔介质的壁形成物理结合。在较高的过冷度下，观察到树枝状晶体的分散形成和随后的形态变化为颗粒状晶体。在不存在大量额外甲烷供应的情况下，树枝状晶体的桥接是不可能的，这是因为树枝状晶体的分散空间分布具有比孔隙空间的尺寸小的尺寸。作为在液态水中形成的甲烷水合物的晶体形态中观察到的变化的解释的结果，在多孔介质中观察到的在液态水中的甲烷分子的质量传递的大小上的晶体形态的依赖性是一致的，与先前在散装甲烷-水系统中观察到的。
The nucleation, growth and ageing of methane hydrate crystals were observed visually in a porous medium filled with liquid water presaturated with methane. The pore space dimensions of the porous medium were 1.0 × 102 µm. The pressure−temperature conditions at which hydrate formation was initiated corresponded to system subcoolings of 3.4 K, 6.7 K, 12.3 K and 14.1 K, respectively, where the system subcooling denotes the difference of the system temperature from the triple methane−hydrate−water equilibrium temperature under a given pressure. Faceted (skeletal) hydrate crystals grew and bridged the pore spaces without intervention of a liquid water layer when the subcoolings were equal or smaller than 6.7 K. The faceted crystals may form a physical bonding with the walls of the porous medium. At the higher subcoolings, the dispersive formation of dendritic crystals and subsequent morphological change into particulate crystals were observed. The bridging of the dendritic crystals is unlikely in the absence of a large amount of additional methane supply due to the dispersive spatial distribution of the dendritic crystals that have dimensions smaller than those of the pore spaces. As a result of the interpretation of the observed variation in the crystal morphology of the methane hydrate formed in liquid water, the dependence of the crystal morphology on the magnitude of the mass transfer of methane molecules in liquid water observed in the porous medium was consistent with that previously observed in a bulk methane–water system.