含低剂量抑制剂的四氢呋喃水合物生成过程

Formation of Tetrahydrofuran Hydrate with Low Dosage Hydrate Inhibitor

在-5℃以下和常压条件下,以四氢呋喃(THF)水溶液(THF与水质量比为21∶79)为基础,采用金相显微镜研究了THF水合物的生成过程。实验结果表明,含有0.5%(w)抑制剂VC-713时,在9.4℃过冷度下需要温度突降才能激发生成THF水合物;THF水合物生成时先呈条状或枝状晶枝,之后水合物在晶枝之间填充,最终在观察区域内THF水合物呈絮状;实验条件下THF水合物形成迅速,在75 s内全部生成;随着过冷度和晶核的增加,初期生成THF水合物的反应速率较慢,随后反应速率迅速加快;不含抑制剂VC-713时,THF水合物可在9.4℃过冷度下迅速生成,水合物晶枝出现后,迅速以已有晶枝为中心扩展至整个观察区域。

Below -5 ℃ and at atmospheric pressure, the crystallization of tetrahydrofuran（THF） aqueous solution（mass ratio of THF to water 21 ： 79）, pure or containing 0.5%（w） hydrate inhibitor VC-713, was investigated by means of an optical microscope. The results show that in the presence of inhibitor VC-713, only sudden temperature drop can induce the THF hydrate crystallization at 9.4 % supercooling. Firstly, THF hydrate crystals with strips and dendrites form, then the spaces between the dendrites are filled with the hydrates, and finally flocculent hydrate crystals are observed. Under the experimental conditions THF hydrates form rapidly within 75 s. With the increase of both the supercooling and the hydrate nucleus, the crystallization velocity rapidly heightens during the observation. Without any inhibitors THF hydrates could form quickly at the subcooling of 9.4 ℃ and then expand around the existing dendrites.