Preparation And Applications Of New Natural Gas Hydrate Kinetic Inhibitor PVCL And Copolymer

Natural gas hdrate is a cage-like crystalline compound similar to the ice. Hydrate will bring much disadvantages to the produce of natural has once, it forms,which can block gas pipeline and make transportation stop so as to bring economics loss to enterprise and country.In a general way, use the traditional thermodynamic inhibitors, such as methanol, ethanol and electrolytes and so on, to prevent the hydrate formatting. However, high consumption is the primary disadvantage of this technique. Weight ratio may reach to 40-50%. High cost used to inhibit the formation of natural gas hydrate and environmental hazard that follow. Therefore, a new dynamic inhibitor with low consumption and high efficiency and innoxious has been studied to replace the thermodynamic inhibitor.New hydrate inhibitor (PVCL) is synthesized With VCL as raw material and AIBN as initiator by radical polymerization by the free-radical polymerization in aqueous solution. The structures are characterized by means of IR and ~1HNMR and its low critical soluble temperature (LCST) is determined by 721 type spectrophotometer. The effects of various factors, such as amount of the initiator and solwent, reaction time and temperature, on the molecular weight and polymerization yield are investigated. By optimizing the reactive conditions, average molecular weight of PVCL from 10000 to 300000 can be gotten and the yield is over 90%. One series copolymer of PVCL is synthesized. Copolymer include: VCL/AM copolymer,VCL/MAM copolymer,VCL/VP copolymer,VCL/VP/AM copolymer and VCL/VP/MAM copolymer. Inhibition performance of PVCL and these copolymers as dynamic inhibitor were detected.Experiment is reacted in a small testing device which can be used to detect the performance of gas hydrate inhibitors(volume of reaction kettle is 1.072L, maximum working pressure is 20MPa, temperature range is -15℃～100℃). In the seabed under the conditions of temperature and pressure (277.15 K and 8.27 MPa, in the undercooling for 15 K), the gas mixture as a response to gas hydrate formation is composed by methane 92.03 percent, ethane 3.01 percent and propane 4.96 percent. Inspected the different concentrations, mixing different speed, different molecular weight homopolymer PVCL size of the inhibitory effect of the hydrate and its suppression of the copolymer are compared. The results show that: Concentration of the inhibitor in the following two percent, with the increase of concentration, enhances the effect of inhibiting. The greater mixing speed is conducive to hydrate formation, and lead to inhibition of weakening. With the increase of molecular weight, the suppression performance significantly enhances. When the concentration of PVCL homopolymer is one percent and the molecular weight is 300,000, the longest time of inhibiting the gas hydrate formation can reach 17.5 h. Copolymer inhibition performance studies show: The inhibition performance of copolymers is better than that of homopolymer and the terpolymer are the best which can reach 40 h above.