The Study Of Hydrate Kinetic Inhibiting Mechanism And The Development Of Efficient Kinetic Hydrate Inhibitors

The formation and accumulation of hydrate easily lead to pipe plugging in the transportation process.To prevent hydrate plugging,a large number of thermodynamics reagents were injected into the pipelines.This method could be not only harmful to the environment,but also diseconomic to the department.Because of this,people pay more attention to the low dosage hydrate inhibitors(LDHIs),but the mechanism is still unclear.According to the actual situation,in this work,firstly we used a series of chemical reagents with known molecular structure as hydrate inhibitors.Then we designed and synthesized a series of new reagents.The main contents of this work are as follows:(1)We tested the properties of the reagents with small molecules and polymer molecules by high pressure sapphire cell.We found small molecule reagents are not good in hydrate inhibition and there is no value to apply them for pratical application.Most polymers perform better than small molecule reagents in hydrate inhibition.When the molecules have larger steric hindrance and more hydrophobic groups,the reagent has better performance.By the compound tests we found it is hard to realize the synergistic effect between reagents and sometimes they could accelerate the hydrate formation.(2)Based on the relationship between the structure of reagents and their hydrate inhibiting performance,we designed and synthesized a series of new reagents and tested them as kinetic hydrate inhibitors(KHIs).We found self-made hydrate inhibitor PVP-BP is very good in hydrate inhibition.(3)From the flow loop experiments,we tested the performace of self-made KHIs in pipeline.We found at the subcoling of 8.4 K,no hydrate formation up to 33 hrs with the injection of our self-made KHIs.While at the subcooling of 12.2 K,our inhibitor could also prevent the hydrate growth.Altough the system has a little hydrates under these conditions,it could still flow safely at least 40 hrs.(4)We used glycol ethers solvent to compound with self-made KHIs to study their strengthen law.We found alcohols have three kinds of roles in the system.In addition,we determined the optimum application scheme and found ethylene glycol butyl ether is the potential synergy reagent.Our finding would pave the way for the application of KHIs.(5)As hydrate formed on the gas/liquid surface at first and most hydrate kinetic inhibitors belong to surfactants,we measured the interfacial tension between the hydrate formation gas and the solution with different hydrate inhibitors.We found the lower interfacial tension of the system,the longer induction time the system has.Based on our experimental results,we proposed the inhibition mechanism of KHIs.By comparing the interfacial tension of the system,we could screen the same class of hydrate inhibitors and find the one with good inhibition performace.(6)We systematically evaluated the performace of hydrate inhibitors in oil/water system.In our experiments,different types of emulgators were used to compound with inhibitors and we compared the self-made inhibitors to commercial ones.From the results,we found oil phase could accelerate the hydrate formation.When a little amount of emulgators exist in the system,hydrate formed dramatically and KHIs lost their inhibition ability.Our findings are expected to give a guidance on the KHIs application in oil/water system.