Clean Technology (청정기술)

The Korean Society of Clean Technology (한국청정기술학회)
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Gas Hydrate Phase Equilibria of $CO_2+H_2$ Mixture in Silica Gel Pores for the Development of Pre-combustion Capture

연소 전 이산화탄소 회수기술을 위한 실리카겔 공극 내에서의 이산화탄소+수소 혼합가스 하이드레이트의 상평형

  • Kang, Seong-Pil (Clean Fossil Energy Research Center, Korea Institute of Energy Research) ;
  • Jang, Won-Ho (Department of Environmental Engineering, Kyungpook National University) ;
  • Jo, Wan-Keun (Department of Environmental Engineering, Kyungpook National University)
  • 강성필 (한국에너지기술연구원 청정화석연료연구센터) ;
  • 장원호 (경북대학교 환경공학과) ;
  • 조완근 (경북대학교 환경공학과)
  • Published : 2009.12.31
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Abstract

Thermodynamic measurements were performed to show the possibility of recovering $CO_2$ from fuel gas (the mixture of $CO_2$ and $H_2$) by forming gas hydrates with water where water was dispersed in the pores of silica gel particles having nominal 100 nm of pore diameter. The hydrate-phase equilibria for the ternary $CO_2+H_2$+water in pores were measured and $CO_2$ concentrations in vapor and hydrate phase were determined under the hydrate-vapor two phase region at constant 274.15 K. It was shown that the inhibition effect appeared due to silica gel pores, and the corresponding equilibrium dissociation pressures became higher than those of bulk water hydrates at a specific temperature. In addition, direct measurement of $CO_2$ content in the hydrate phase showed that the retrieved gas from the dissociation of hydrate contained more than 95 mol% of $CO_2$ when 42 mol% of $CO_2$ and balanced Hz mixture was applied. Compared with data obtained in case of bulk water hydrates, which showed just 83 mol% of $CO_2$ where 2-stage hydrate slurry reactor was intended to utilize this property, the hydrate formation in porous silica gel has enhanced the feasibility of $CO_2$ separation process. Hydrate formation as not for slurry but solid particle makes it possible to used fixed bed reactor, and can be a merit of well-understood technologies in the industrial field.

가스하이드레이트를 이용하여 이산화탄소+수소 혼합가스로부터 이산화탄소를 선택적으로 분리, 회수하기 위한 공정개발의 가능성을 살펴보고자 상평형 조건을 측정하였다. 100 nm의 공극 직경을 갖는 실리카겔 공극 내에서 형성되는 가스하이드레이트-물-기체의 삼상평형 하이드레이트 해리조건을 측정하였으며, 274.15 K에서 하이드레이트-기체의 이상조건 상태로 유지한 상태에서 이산화탄소의 농도변화에 따른 기상 및 하이드레이트상의 가스 조성을 분석하였다. 일정한 온도조건에서 기상의 이산화탄소 농도가 증가할수록 평형해리압력은 감소하는 경향을 보였으며, 순수 물에서의 상평형 압력과 비교하면 실리카겔 공극에서의 하이드레이트 상평형은 모세관효과에 의해 생성저해 현상이 발생하였다. 42 mol% 이산화탄소와 58 mol% 수소 혼합가스로부터 얻어지는 가스하이드레이트상의 조성은 이산화탄소 95 mol% 상으로 측정되었는데, 이는 기존의 순수 물을 이용하여 가스하이드레이트를 제조함으로써 이산화탄소를 농축, 분리하는 방법에 비해 매우 향상된 결과를 보여주고 있다. 하이드레이트 슬러리를 제조하여 2단 반응으로 분리하는 기존 방법에 비해 공정을 단순화할 수 있는 이 방법은 고정층 반응기로 쉽게 적용이 가능하므로 유용한 연소 전 이산화탄소 회수방법으로 이용할 수 있을 것으로 기대된다.

Keywords

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