Abstract
In this study, we performed continuous gas separation experiments and thermodynamic simulations using methane, CH_4 + carbon dioxide, CO_2 mixed gas as a model of unconventional natural gas. Long term experimental operation of hydrate-based gas separation was performed.The experiments includes the processes of hydrate formation, transportation, and decomposition. The time evolutions of compositions in gas and hydrate slurry phases were experimentally measured. The experimental time evolution of the compositions was well reproduced by the thermodynamic simulations, which supports the validity of the simulations. In the experiments, target gas was CH_4 + CO_2 mixed gas (0.40 : 0.60 in molar ratio). System pressure was set to 2.2 MPa, experimental temperature was controlled at 274 K. The mole fraction of CH_4 in the gas phase was increased due to a preferential uptake of C02 into the hydrate slurry, and then reached about 0.61 at a steady state. The mole fraction of CO_2 in the slurry was decreased to about 0.77 at the steady state. Comparison of the experimental data and the prediction with the thermodynamic simulations indicates that the deviations of the mole fraction of compositions in the gas and hydrate slurry phases are ± 0.02 and ± 0.05 respectively.
