CO2 하이드레이트의 film형 결정성장 거동에 관한 연구
Characteristics of film-type crystal growth mechanism of CO2 hydrate
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초록
지구 온난화의 대표적인 주범인 CO2를 저감하기 위하여 많은 연구가 진행되고 있다. 특히 가스 하이드레이트형성원리를 이용한 CO2 분리 및 저장 공정이 주목을 받고 있다. 본 연구는 필름형 CO2 하이드레이트의 결정성장 거동에관하여 성장 메커니즘을 규명하였다. 다양한 압력조건에서 반회분식 교반 반응기를 이용하여 CO2 하이드레이트를 형성시켰으며 객체가스의 용해도 차이를 최소화하기 위하여 모든 실험에서 온도는 고정하였다. 공급된 가스는 순도 99.999 %의CO2 가스를 사용하였고, CCD 카메라(Nikon DS-5M/Fi1/2M-U2)가 장착된 광학현미경을 사용하여 관찰 결과를 실시간 기록하였다. 실험에 적용되는 압력에 따라서 하이드레이트 성장형태와 성장속도는 매우 큰 차이를 보였다. 특히 2.0 MPa 이상의 압력에서 가장 큰 변화를 관찰하였으며, 이것은 CO2의 농도 차이와 모세관 힘에 의한 것으로 사료된다.
Abstract
Many researches have been carried out to reduce and/or to capture the major global warming gases. Especially,the hydrate formation mechanisms were intensively investigated for carbon dioxide sequestration and storage process applications. In this study, the characteristics of film-type crystal growth mechanism of carbon dioxide hydrate were comprehensively examined. Carbon dioxide hydrate crystal was formed in semi-batch type stir reactor at various pressure conditions while the temperature was fixed to be constant to reduce and minimize the guest gas solubility effects. A supply gas composition was 99.999 % of Carbon dioxide, the observation data was collected by optical microscope adopted CCD camera (Nikon DS-5M/Fi1/2M-U2). This study revealed that the guest gas pressure changes significantly altered the crystal growth mechanism and film growth rate of carbon dioxide hydrate crystal. The critical pressure of the carbon dioxide hydrate of crystal growth mechanism change was found to be 2.0 MPa. The capillary force and gas concentration gradient also significantly changed the film-type crystal growth mechanism of carbon dioxide hydrate crystal.
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