| 초록 |
Natural gas hydrates have been considered as future energy due to the large amount. Replacement method has been studied as a promising production technology which has a dual function of both CH4 production and CO2 sequestration. In this study, the influence of CO2+N2 injection into structure H (sH) hydrate was investigated to reveal the effects of structure transition and feed gas compositions on replacement efficiency. Feed gases with various compositions (CO2 20%, 40%, and 60%) were injected into CH4+methylcyclopentane hydrate for replacement. The efficiency was measured using gas chromatography and the structure transition was confirmed through 13C NMR and powder X-ray diffraction. For the CO2(20%)+N2(80%) replacement, the extent of replacement was quite low (62%) and there was no structural transition. With an increase in CO2 concentration of the feed gas, the larger fraction of structure I (sI) due to the structural transformation was observed. However, the replacement efficiency was found to be highest for the feed gas of CO2(40%)+N2(60%). The overall experimental results can contribute to a better understanding of the replacement mechanism in the sH - CO2+N2 replacement. |
