含动力学抑制剂的四氢呋喃水合物形成过程及盐效应

Formation Process of Tetrahydrofuran Hydrate in the Presence of Kinetic Inhibitors and the Effect of Salt

采用四氢呋喃水合物晶体生长法研究了聚乙烯基吡咯烷酮(PVP)、聚乙烯基己内酰胺(PVCap)两种动力学抑制剂(KHIs)的性能及盐(NaCl)的存在对其性能的影响,结果发现4%NaCl的添加显著提高了抑制剂体系的最大过冷度并延长诱导时间,使得抑制剂在低过冷度下仍具有较好抑制作用,表明盐与两种传统抑制剂具有较强的动力学协同抑制效应。同时,通过紫外可见分光光度计分析不同体系中水合物生长过程液相KHIs浓度随时间的变化规律,发现水合物成核诱导期液相浓度均无明显变化,但随着水合物生长,液相中PVP浓度匀速下降,而PVCap浓度变化不明显。表明抑制剂分子可能通过与水相互作用扰乱整体水结构从而抑制水合物成核,而在生长期则主要通过与水合物晶体结合阻碍水合物生长。相比PVP体系成核后大量的水合物生长,PVCap只需更少的量便可作用于水合物,表现出更好的抑制作用。

In this paper,the performance of two kinetic inhibitors(KHIs),polyvinyl pyrrolidone(PVP)and polyvinyl caprolactam(PVCap),were studied by using the tetrahydrofuran hydrate formation method,as well as the influence of NaCl on their performance.The addition of 4%NaCl significantly increased the maximum subcooling temperature.It prolonged the induction time of the hydrate system with inhibitors,also making the inhibitor still have a good inhibition effect at a low subcooling degree.The results showed that the salt(NaCl)and two traditional inhibitors had a strong synergistic kinetic inhibition effect.At the same time,the concentration variation of KHIs in the liquid with time during hydrate growth was determined by an ultraviolet-visible spectrophotometer.It was found that the concentration did not change significantly during the induction period of hydrate nucleation,while the concentration of PVP in the liquid phase decreased at a uniform rate with the growth of hydrate,while the concentration of PVCap did not change significantly.The inhibitor molecules may inhibit hydrate nucleation by disturbing the overall water structure by interacting with water and inhibit hydrate growth mainly by binding with hydrate crystals during growth.Compared with the large amount of hydrate growth after nucleation of PVP system,PVCap only needs less to act on hydrate,showing a better inhibition effect.