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