| Gas hydrates are non-stoichiometric crystals composed of small molecular gases and water molecules.With the release of hydration heat,the growth rate of hydrates and the conversion of water to hydrates are severely inhibited.In my research the formation of methane hydrate in ice in water slurry from the phase change of the water-in-oil emulsion was determined by a pressure-volume-temperature(PVT)in a hydrator.The ice particles from the supercooled emulsion provide nucleation centers and promptly remove hydration heat through their phase changes of ice particle.At the same time,the difference in solubility of methane in five paraffins,including hexane,heptane,nonane,decane,undecane,and water increases the driving force of mass transfer.The experimental results show that increasing the pressure can shorten the induction time of hydrate formation and also have a certain influence on the growth time.As the average diameter of water droplets in the emulsion decreases,the total rate of methane hydrate formation increases,and the average diameter also affects the conversions of water and methane during the gas hydration.The solubility of methane in paraffin is also a factor in increasing or decreasing the rate of hydrate formation and conversion of water.The solubilities of methane in different paraffins and their W/O emulsions were determined by the Peng Robinson equation.Finally,in a batch autoclave with an initial temperature of-6°C,different pressures of 6.9,6.7,6.5 MPa,and different average droplet size,water content of 20 vol%,and agitator speed of 700 rpm,methane the hydration rate has increased significantly.The highest hydration rate reached 240.6kmol h-1 m-3,and the methane to hydrate conversion reached 53%,which was greater than the conversion in the slurry of organic phase change material in water. |
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