Study On Natural Gas Hydrate Formation With Different Reactors

Natural gas hydrates are crystalline compounds, which belong to a group of solids called clathrates. The hydrates can contain 150-180 volumes (standard temperature, pressure) of natural gas per volume of hydrate. It provides possibility to study on hydrate storage and transportation technology. But equipments for hydration process in hydrate storage and transportation are still smaller scale, which cannot be main means for natural gas transportation instead of liquefied natural gas. Therefore it is necessary to study on storage and transportation technology, especially for hydration process. Hydration process belongs to diffusion control with exothermic reaction.Therefore, how to improve gas-liquid rate of mass transfer and how to enhance reaction heat transfer are main problems in reactors' choice. On the one hand, increasing stirring and adding additive are generally adopted to improve diffusion rate. On the other hand, heat exchange set is installed in reactor inside and outside to enhance heat transfer. In addition, different operation methods should be considered to gain larger reaction driving force in a reactor appointed.Firstly, semi-continuous continuous tank reactor as a conventional reactor is applied to investigate methane hydration process. Three experiments, constant-pressure & lower-temperature hydration process, low-temperature & constant-pressure hydration process, non-stirring hydration process, are carried out to investigate which process is best for gas hydrate formation in 1L semi-CSTR. The experimental results show that low-temperature and constant-pressure hydration process is better than the other two processes because its operation period is shorter and storage capacity is larger than the other two. Therefore, low-temperature & constant-pressure process is the best storage method, which is adopted in further investigation. The interrelation between consumption of methane gas and experimental conditions (stirring conditions, additive and load coefficient) are obtained in semi-CSTR. At 5.0MPa, the appropriate stirring time and stirring velocity are 30min and 320rpm, respectively; Sodium dodecylsulfate is better additive than others from references and experimental investigation; appropriate load coefficient is 0.289. At this time, higher storage capacity, above 159Vg·V_H^-1, can be achieved and higher hydration rate, 0.43V_g·V_H^-1·min^-1, can be gained. Besides, some basic data of fluid mechanics, for example stirring Reynolds number, Froude number and stirrer power, are calculated during methane hydration process, which is applied to evaluate stirrer capacity and provide some basic data...