Experimental Research On Rapid Synthesis Technology Of Natural Gas Hydrate

also Natural gas hydrate is widely distributed in marine sediments or permafrost regions as one of the most unconventional natural gas on the earth.Meanwhile,the hydrate technology would be widely applied into the oil and gas production,refrigeration,gas storage and transportation,water desalination and C02 sequestration industries.According to the stable conditions of natural gas hydrate,the experimental process of gas hydrate synthesis has been designed under different intensification methods.And according to the characteristics of this experiment,the induction period of methane hydrate has been redefined in the process of experiment.So as to find ways and measures to enhance the production of natural gas hydrate,shorten the induction time of natural gas hydrate and promote the efficient and rapid synthesis of natural gas hydrate.The formation kinetics and mechanism of gas hydrates are studied experimentally under the condition of bubbling and pressure disturbance in this paper.And the driving force of the hydration reaction of the gas and liquid system and the mass transfer rate in the process of gas hydrate formation also are clarified.Based on the formation of gas hydrate in the reactor,a semi empirical physical model of hydrate formation during the bubbling process was established during the experiment.Meanwhile,the expression rate of synthetic in the process of natural gas hydrate formation is deduced,and the influence of mass transfer and hydration process on the formation of natural gas hydrate is systematically studied.In this paper,the effects of pressure fluctuation on the static growth of methane hydrate were studied under different temperature,pressure,pressurization time and pressure difference.The result shows:1)Under the condition of hydrate formation,the pressure fluctuation can effectively promote the forming process of methane hydrate and increase the probability of hydrate formation when methane hydrate is not formation for a long time;2)The pressure fluctuation cannot directly impact the process of Induction nucleation stage,but can result the reaction from nucleation into the rapid growth period in short order after the nucleation of hydrate crystal grows to a certain size.And the impact of process of hydrate is independent of temperature and pressure.The additional pressure will increase the driving force of the formation process,but the magnitude of the driving force is not the main cause of the stagnated hydration reaction start again;3)The pressure fluctuation will break the long-term dynamic equilibrium by the vapor water molecules in the rich liquid hydrocarbon phase and the dissolved methane molecules in the rich water phase,producing phenomenon of flashing.The concentration of water and methane increases at the gas-liquid interface,and the stagnated formation reaction begins again.It’s found that the pressure fluctuation can synthesize hydrate efficiently and rapidly without affecting its structure and low energy consumption,which provides a new idea for the rapid preparation of hydrates in industrialization.The formation process of natural gas hydrate in the vessel was investigated by the recirculating gas hydrates synthesis experimental device.The effects of different pressure fluctuations in the reactor on the induction time of hydrate formation were studyed experimentally during the bubbling process.And compared with the induction time of hydrate formation,using the SDS as surfactants or pure water.The results shows:1)a certain amount of air bubbles in the transparent vessel can obviously shorten the induction time of hydrate formation.2)And in the process of bubbling,the ice crystal is firstly formed at the gas-liquid interface and the reactor wall,untill formed a thin layer of hydrates.3)Meanwhile,the hydrate sheet attached to the surface of the bubble adheres continuously to the lower part of the formed thin hydrate layer.Eventually,the hydrate grows straight down along the liquid direction and fills the entire reactor.By comparing and analyzing the temperature variation curves of the hydrate formation under different pressure fluctuations and overpressure conditions for phase equilibrium in the process of bubbling experiment under 5MPa and 6MPa,it’s found that when the pressure disturbance is within the range of 0.4 to 0.8MPa,the velocity of hydrate formation is the fastest,and the overpressure of the hydrate is smaller when it reaches the phase equilibrium.