Study on gas-phase water content in methane-hydrate phase equilibrium
In the process of natural gas extraction and transportation,the presence of trace amounts of gaseous water may lead to hydrate formation with small gas molecules,resulting in pipeline blockages,so it is necessary to remove water from natural gas through dehydration.To establish appropriate parameters for the maximum permissible water content in natural gas,it is crucial to measure and calculate the gas-phase water content in gas-hydrate phase equilibrium accurately.Under the conditions of pressure from 3.44 MPa to 6.00 MPa and temperature from 270.00 K to 274.00 K,the gas-phase water content of methane-hydrate phase equilibrium was studied by experimental measurements and model predictions.The results show that compared with pressure dew point,atmospheric dew point and gas-phase water content volume ratio change regularly with temperature and pressure.Gas-phase water content decreases with the decrease of temperature and the increase of pressure.On the basis of experiments,a thermodynamic model of gas-phase water content in methane-hydrate phase equilibrium was established based on thermodynamic phase equilibrium theory.The average relative deviation between the predicted values and experimental values is 2.33%.This method achieves in situ measurement of gas-phase water content in methane-hydrate phase equilibrium system,and the established model is faster and more accurate than the method of obtaining the saturated water content in methane-liquid water phase equilibrium by looking up the diagram and extrapolating to the hydrate zone.
hydratemethanephase equilibriumgas phase water contentthermodynamic model
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