Crystal Growth of Clathrate Hydrate at the Interface between Hydrocarbon Gas Mixture and Liquid Water
Crystal Growth of Clathrate Hydrate at the Interface between Hydrocarbon Gas Mixture and Liquid Water
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DOI：
10.1021/cg101310z
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发表时间：
2011-01-01
影响因子：
3.8
通讯作者：
Ohmura, Ryo
中科院分区：
文献类型：
--
作者：
Saito, Kota;Kishimoto, Masatoshi;Ohmura, Ryo
本文报道了在甲烷+乙烷+丙烷混合气体中，观察到水滴表面笼形水合物晶体的形成和生长。甲烷+乙烷+丙烷气体混合物的组成为（i）99.47：0.51：0.02，（ii）94.1：5.8：0.1，和（iii）90：7：3摩尔比。水合物的成核首先发生在水滴上的随机点处，然后水合物生长形成覆盖水滴的多晶层。我们目视观察构成多晶水合物层的单个晶体，并根据系统过冷Δ T-sub和系统压力对水合物晶体的形态进行分类。结果发现，单个混合气体水合物晶体的尺寸随着Δ T-sub的增加而减小，如对于每个与甲烷、乙烷或丙烷形成的简单水合物所观察到的。单个晶体的尺寸随着混合气体中甲烷摩尔比的增加而减小。混合气体水合物晶体的形貌与单纯甲烷水合物不同。我们还测量了水合物膜传播的横向生长速率。在任何系统中，速率随着Δ T-sub的增加而增加，如在其他水合物形成系统中所观察到的。
This paper reports the visual observations of the formation and growth of clathrate hydrate crystals on the surface of a water droplet exposed to a methane + ethane + propane gas mixture. The compositions of the methane + ethane + propane gas mixtures are (i) 99.47:0.51:0.02, (ii) 94.1:5.8:0.1, and (iii) 90:7:3 molar ratio. The nucleation of the hydrate first occurred at a random point on the water droplet and then the hydrate grew to form a polycrystalline layer covering the droplet. We visually observed the individual crystals that constitute the polycrystalline hydrate layer and classified the morphology of the hydrate crystals depending on the system subcooling Delta T-sub and system pressure. It was found that the size of the individual mixed-gas hydrate crystals decreased with the increasing Delta T-sub as observed for the simple hydrates each formed with methane, ethane, or propane. The size of the individual crystals decreased with the increasing molar ratio of methane in the gas mixtures. The mixed-gas hydrate crystals exhibited a morphology different from that of the simple methane hydrate. We also measured the lateral growth rates of the hydrate-film propagation. In any of the systems, the rates increased with increasing Delta T-sub as observed in other hydrate-forming systems.