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삼화 원탄과 무회분탄의 촉매(K₂CO₃) 가스화 반응성 비교 연구
공용진(Yongjin Kong),임정환(Junghwan Lim),임영준(Youngjoon Rhim),전동혁(Donghyuk Chun),이시훈(Sihyun Lee),유지호(Jiho Yoo),이영우(Young-Woo Rhee) 한국청정기술학회 2014 청정기술 Vol.20 No.3
석탄의 가스화는 촉매 도입 시 온순 조건에서 가능하나, 석탄 내 회분에 의한 비활성화에 의해 반복적인 촉매 활용이 힘들다. 이에 본 연구에서는 삼화 원탄에서 회분을 제거하여 삼화 무회분탄(ash-free coal, AFC)을 제조한 후 가스화 반응성을 원탄과 비교하여 알아보았다. 우선 원탄을 대상으로 고정층 반응기에서 수증기 공급량, 공간 속도(space velocity), 온도 및 촉매를 변수로서 가스화 조건을 결정하였다. 고체상 혼합법으로 다양한 촉매 도입 시, 유동성을 갖는 K₂CO₃가 가장 높은 활성을 보였다. 무회분탄은 원탄보다 낮은 반응성을 보였으며, 이는 용매(1-methylnaphthalene, 1-MN)를 이용한 고온 추출 및 건조 공정 중에 소모된 산소 기능기 함량과 증가된 탄화도(carbonization)에 기인한다. K₂CO₃ 가 혼합된 무회분탄의 반응성은 급격히 증가하여 낮은 온도 (700 ℃)에서도 높은 전환율을 보였다. 이때 H₂/CO와 CO₂/CO 비율도 증가하는데, 이는 촉매에 의해 수성가스전환(water-gas shift) 반응이 활성화됨에 기인한다. 본 연구에서는 무회분탄의 저온 촉매 가스화 반응을 통해 석탄 가스화 공정의 경제성이 개선될 수 있음을 확인하였다. Catalytic gasification of raw coals at mild condition is not realized yet mainly due to deactivation of catalysts via their irreversible interaction with mineral matters in coal. In this work, the gasification behavior of ash-free coal (AFC) was compared with that of the parent raw coal. In order to modify the gasification conditions, the raw coal gasified with fixed variables (water supply, space velocity, temperature, catalysts) in a fixed bed reactor. When catalysts are added by physical mixing method with coal, K₂CO₃ was the most effective additives for steam gasification of coal. However, the activity of ash-free coal (AFC) was much less reactive than raw coal due to high temperature extraction in a 1-methylnaphthalene under 30bar at 370 ℃ for 1 h, almost removed oxygen functional groups, and increased carbonization. The addition of K₂CO₃ in AFC achieved higher conversion rate at low temperature (700 ℃). At that time, the molar ratio of gases (H₂/CO and CO₂/CO) was increased because of water-gas shift reaction (WGSR) by addition of catalysts. This shows that catalytic steam gasification of AFCs is achievable for economic improvement of gasification process at mild temperature.
최호경(Hokyung Choi),김상도(Sangdo Kim),유지호(Jiho Yoo),임정환(Jeonghwan Lim),임영준(Youngjoon Rhim),이시훈(Sihyun Lee) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.40
This paper describes the potential application of ash-free coal to direct carbon fuel cell (DCFC). DCFC can be made of typical fuel cell components and generates the electric energy by direct electrochemical oxidation of carbon, replacing hydrogen with solid carbon fuel. Carbon is mostly originated from coal, which is readily available, easily transportable, and economical. However, employing coal as a carbon source has been excluded, mainly due to its high ash content. The ash-free coal, produced by solvent extraction of combustibles from raw coal, can be applicable as carbon fuel to DCFC. The successful adaption may cut the fuel cost to one third of usual hydrogen fuel cells. In addition, 80% of power generation efficiency can be achieved and CO₂ emission from the conventional coal-fired power plant can be reduced by 90%.