Preliminary Study On Driving Force Of Gas Hydrate Formation In Gasous-liquid System

The technology of gas hydrate has extensive application foreground in the fields of gas hydrate exploitation, store up cool,carbon dioxide storage deposited in seabed, natural gas transportation by the form of solid, sea aqueous solution desalination and other areas of industry. The application of gas hydrate is tight related to formation driving force, formation velocity and other foundation problem.Presently, the research of gas hydrate kinetics still at primary state.There are many disputes on the question of driving force. This passage characterizes driving force of gas hydrate formation by the use of molar Gibbs free energy difference Ag, preliminary study formation driving force during gas hydrte growth. Material contents and results as follow:(1)It gets the driving force of gas hydrate formation of simple component gas (methane, ethane, propane, carbon dioxide and sulfureted hydrogen) and methane and carbon dioxide in 3.5% sodium chloride solution in pure aqueous solution on the condition of isothermal.It analyses theoretically kinetic feasibility, which using carbon dioxide substitute methane in seabed. It also quantitative analyses the impacts of pressure and temperature on driving force of hydrate reaction. The results indicates that molar Gibbs free energy difference of hydrate reaction does not minish with pressure as linearity for gas and liquid system.The gradient of molar Gibbs free energy difference changes along with pressure increase.That is the contribution of increase of unit pressure for driving force has changed. It can be plot out two trends for methane and carbon dioxide hydrate formation driving force.(2)It observes the hydrate growth process for gas and liquid system, taking propane for example, using a suit of experiment installation and experiment measure, which designed by self. The experiment proceed in pure water,sodium dodecyl sulfate of 1950ppm, sodium dodecyl benzene sulfonate of 400ppm. It attends the changing of pressure and temperature during the whole reaction and important parameters of thickness, reaction velocity, driving force etc. There is great difference on hydrate interface formation reaction if surface active agent exist.When there is not surface active agent, hydrate formation just happen at the interface layer. Hydrate reaction slow and insufficiency. When appending surface active agent, it grows mass hydrate and reaction thoroughly. It forms solid hydrate entirety indeed. By all appearances, surface active agent can reduce interfacial tension of two kinds of reactant, minish specific suiface area between interface of gas and liquid effectively, which make gas molecule enter into liquid phase easily, promote hydrate formation.The thickness of gas and liquid interface hydrate layer growth as ladder in pure water.(3)It fits kinetics model using linear combines function of constant, power function and hyperbolic function, based on academic calculation numerical value of driving force and hydrate reaction velocity from experiment. The thickness of hydrate layer growth as ladder.There are both increase firstly then keep steady on hydrate reaction velocity and driving force. They both change as linear combine function of constant, power function and hyperbolic function during reaction.It believes that the reason of hydrate growth slowly and insufficiency at state of static lie on the compositive effect of loricae effect, heat of transformation of hydrated reaction, the influence of pressure on hydrate crystal process in gasous-liquid system with a given condition of temperature and pressure.The innovation point and significance is:(1)The data of hydrate reaction driving force at static state of gas and liquid system were obtained for the first time, which using mol Gibbs free energy change express;(2) The important dynamics parameters of temperature, pressure, thickness, hydrate reaction velocity and driving force during process of peopane hydrate layer growth were obtained for the first time. It fits propane hydrate growth dynamics model of gas and liquid system;(3)The gas hydrate growth disciplinarian at static state was concluded and perfected. It renews that thereis tranquilization phase in hydrate growth process at static state in pure water。The law of hydrate reaction provides academic foundation,which has tremendous referenced significance for hydration interface reaction in gasous-liquid system and the research on technique of hydrate industrialisation application。...