Study on Hydrate Phase Equilibrium Diagram of Methane Containing System Based on Thermodynamic Model
Natural gas hydrate is a potential energy source in the future, which widely occurs in nature and industrial activities, and its formation and decomposition are identified by phase equilibrium. The calculation of multicomponent gas phase equilibrium is more complex than that of single component gas,...
| Published in: | Frontiers in Energy Research |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
Frontiers Media SA
2021
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.3389/fenrg.2021.743296 https://www.frontiersin.org/articles/10.3389/fenrg.2021.743296/full |
| Summary: | Natural gas hydrate is a potential energy source in the future, which widely occurs in nature and industrial activities, and its formation and decomposition are identified by phase equilibrium. The calculation of multicomponent gas phase equilibrium is more complex than that of single component gas, which depends on the accurate model characterized by enthalpy and free energy. Based on the Kvamme-Tanaka statistical thermodynamic model, theoretical and experimental methods were used to predict and verify the phase equilibrium of pure methane hydrate and carbon dioxide hydrate in the temperature range of 273.17–289.05 K. The phase equilibrium curves of methane-containing gases such as CH 4 +CO 2 ,CH 4 +C 2 H 6 ,CH 4 +H 2 S and CH 4 +CO 2 +H 2 S under different mole fractions were drawn and analyzed, and the decomposition or formation enthalpy and free energy of hydrate were calculated. The results show that, the phase equilibrium curves of the methane containing systems is mainly related to the guest molecule type and the composition of gas. The evolution law of phase equilibrium pressure of different gases varies with composition and temperature, and the phase splitting of CO 2 at the quadruple point affects the phase equilibrium conditions. Due to the consideration of the interaction between the motion of guest molecules and the vibration of crystal lattice, the model exhibits a good performance, which is quantified in terms of mean square error (MSE) with respect to the experimental data. The magnitudes of MSE percent are respectively 1.2, 4.8, 15.12 and 9.20 MPa 2 for CH 4 +CO 2 , CH 4 +C 2 H 6 , CH 4 +H 2 S and CH 4 +CO 2 +H 2 S systems, and the values are as low as 3.57 and 1.32 MPa 2 for pure methane and carbon dioxide, respectively. This study provides engineers and researchers who want to consult the diagrams at any time with some new and accurate experimental data, calculated results and phase equilibrium curves. The research results are of great significance to the development and utilization of gas ... |
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