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Comparative Studies on K2CO3-based Catalytic Gasification of Samhwa Raw Coal and Its Ash-free Coal

삼화 원탄과 무회분탄의 촉매(K2CO3) 가스화 반응성 비교 연구

  • Kong, Yongjin (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Lim, Junghwan (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Rhim, Youngjoon (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Chun, Donghyuk (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Lee, Sihyun (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Yoo, Jiho (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Rhee, Young-Woo (Graduate school of Engergy Science and Technology, Chungnam National University)
  • 공용진 (한국에너지기술연구원 청정연료연구실) ;
  • 임정환 (한국에너지기술연구원 청정연료연구실) ;
  • 임영준 (한국에너지기술연구원 청정연료연구실) ;
  • 전동혁 (한국에너지기술연구원 청정연료연구실) ;
  • 이시훈 (한국에너지기술연구원 청정연료연구실) ;
  • 유지호 (한국에너지기술연구원 청정연료연구실) ;
  • 이영우 (충남대학교 에너지과학기술대학원)
  • Received : 2014.06.17
  • Accepted : 2014.08.02
  • Published : 2014.09.30

Abstract

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, $K_2CO_3$ 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 $370^{\circ}C$ for 1 h, almost removed oxygen functional groups, and increased carbonization. The addition of $K_2CO_3$ in AFC achieved higher conversion rate at low temperature ($700^{\circ}C$). At that time, the molar ratio of gases ($H_2/CO$ and $CO_2/CO$) 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.

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 $K_2CO_3$가 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. $K_2CO_3$ 가 혼합된 무회분탄의 반응성은 급격히 증가하여 낮은 온도 ($700^{\circ}C$)에서도 높은 전환율을 보였다. 이때 $H_2/CO$$CO_2/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.

Keywords

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