Study Of Experiments And Thermodynamics And Kinetic Models Of Natural Gas Hydrate Formation In The Diverse And Complex Systems

The research and development of various new techniques as well as the utilization about gas hydrate are the research hot-point and developing direction ar present. Kinetic and phase equilibrium of natural gas hydrate are the key to solve problems.Simulation experiment is one of the most important areas in the gas hydrates research, kinetic research is base on it.With these researches we can know the hydrates nucleation mechanism, form conditions of gas hydrates better. Thermodynamic study is provided theoretical support to develop gas separation technology by using the different of hydrate phase equilibrium points. Hydrate formation conditions and mechanism in the diverse and complex systems is researched in this article, then establish and derive the new hydrate thermodynamics model and kinetics model.Firstly, research and application actualities of natural gas hydrate technology at home and abroad are summarized. Industrial value of NGH technology is analyzed in the field of long-distance storage and transmission of natural gas, gas storage and separation, automobile's fuel, seawater desalination, organic solution concentration, CO2 hydrate storage in blue water and extinguishing, refrigerating and cold storage, biological engineering and new material, direct burning, battery and disposal of hazardous materials. Research and development of NGH technology are predicted. Then, Current status of the research of hydrate thermodynamics and kinetics are summarized and concluded.Secondly, effects of the compound additives on natural gas hydrate formation in two different types of system were studied experimentally. Two compound additives, i.e. the mixtures of anionic surfactant sodium dodecylbenzenesulfonate(SDBS) with sodium chloride or methylcyclohexane (MCH), were investigated. It was found that NaCl+SDBS solution system with SDBS concentration of 255mg/kg and NaCl concentration similar to seawater took the shortest induction time, which was the best concentration of the compound additive for hydrate formation. This NaCl+SDBS solution could promote hydrate formation and took shorter induction time compared to the solutions with NaCl, MCH or SDBS as a one component additive.Based on Chen-Guo model, the thermodynamic hydrate formation conditions in the diverse and complex systems are researched. In different conditions of gas composition, liquid hydrocarbon and surface active agent mixture system, Salts and liquid hydrocarbon mixture system, methanol and salts mixture system, are summarized and built these three thermodynamic models. The equilibrium points are calculated by compiler language, and equilibrium points graphical are analyzed and summarized.On the basis of the researches on the generating conditions,mechanism of gas hydrate and experimental phenomena,the new kinetics model considering the compound accelerator affecting are built. A program which can compute the model is designed by compiler language. The induction time in the conditions of different solution and different gas is respectively calculated. The result in good agreement with the experimental data and the theory showing obtained that the calculated data are validated. The results show that the models can express completely the process of NGH formation,and provide the theory and model for its industry application.