Experimental Study On Thermal Effect During Gas Hydrate Process

The generative process of gas hydrate is an exothermic process, however, gas hydrate may only grow quickly in a low-temperature environment, so the heat generated in the hydration process affects the growth of gas hydrate, therefore, it is necessary to carry out research on the thermal effect in the gas hydration process. On basis of this purpose, the paper carried out a lot of experimental researches on the thermal effect in the gas hydration processes under different experimental systems and attained the following achievements:The paper tested the thermal conductivity of gas hydrate on the basis of the theory of transient hot-wire method. The research shows that the thermal conductivity of gas hydrate increases following the rise of temperature within a specified temperature scope. From the aspect of material thermophysical property, the paper also demonstrated the feasibility of storing and transporting gas in the means of natural-gas-hydrate(NGH) storage and transport after hydrated separation of the coal mine gas.The experiments researched the hydration process of gas under specified initial conditions and different experimental systems, Temperature Field—Time curves were drafted for the hydration process of gas. Additionally, in combination with the experimental data, the derived calculation model on the heat generated in the hydration process of gas and the derived calculation model on growth speed were utilized to calculate the generative heat and growth speed in the gas hydration process under different systems.The temperature-field characteristic parameters in the gas hydration process under different experimental systems were analyzed, it was found that the temperature of each kind of reaction system quickly rose to the highest value and then gradually dropped to the temperature of experimental environment. The mean temperature of the upper layer of temperature field was the highest, the highest temperature value was the highest and the speed of temperature rise was the fastest; secondly for the medium-layer temperature field; the average temperature of the lower layer of temperature field was the lowest, the highest temperature value was the lowest and the speed of temperature rise was the slowest.The concentration of methane in gas affects the generative heat in the gas hydration process, distribution of system temperature field and growth speed. Under the same experimental conditions, the gas with high methane concentration released more heat in the hydration process, the temperature of the entire temperature field and the temperature of each layer of temperature field were all higher, the growth speed in the entire process was also larger.The influence mechanisms of different accelerants in the gas hydration process were analyzed. It was found by the analysis that, the addition of the accelerants improved the thermodynamic conditions of generating gas hydrate, shortened the induction time of generating gas hydrate, increased the generative speed of gas hydrate, promoted the generation of gas hydrate, further increased the generative heat within unit time in the generative process of gas hydrate and changed the thermal effect of the entire gas hydration process. In addition, the research also shows that, when the concentration of THF was 1mol/L and the concentration of SDS was 0.5mol/L,the growth speed of the hydration system was the largest, the generative heat was the most and the temperature of the hydration system temperature field was the highest.Gas hydration process is a three-dimensional and unstable heat conduction process containing internal heat source, heat is transferred to such low-temperature areas as liquid phase area and gas phase area from the hydrate area in the means of heat conduction and heat convection. The paper conducted a mathematic description for the heat conduction process of gas hydration, established a temperature field equation on the gas hydration and solved the equation theoretically, in addition, the distribution features of the temperature field in actual process were compared and the result shows that both are anastomotic.