Journal of Energy Engineering (에너지공학)

The Korean Society for Energy (한국에너지학회)
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Investigation of Tar/soot Yield of Bituminous and Low Rank Coal Blends

발전용 역청탄과 저열량탄 혼소시 Tar/Soot의 배출 특성 연구

  • Lee, Byung Hwa (Graduate School of Mechanical Engineering, Pusan Nat'l Univ.) ;
  • Kim, Jin Ho (Graduate School of Mechanical Engineering, Pusan Nat'l Univ.) ;
  • Kim, Gyu Bo (Pusan Clean Coal Center, Pusan Nat'l Univ.) ;
  • Kim, Seng Mo (Pusan Clean Coal Center, Pusan Nat'l Univ.) ;
  • Jeon, Chung Hwan (School of Mechanical Engineering, Pusan Nat'l Univ.)
  • 이병화 (부산대학교 기계공학부 대학원) ;
  • 김진호 (부산대학교 기계공학부 대학원) ;
  • 김규보 (부산대학교 화력발전에너지분석기술센터) ;
  • 김승모 (부산대학교 화력발전에너지분석기술센터) ;
  • 전충환 (부산대학교 기계공학부)
  • Received : 2013.10.19
  • Accepted : 2014.06.02
  • Published : 2014.06.30
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Abstract

Soot and tar which were derived from combustion or pyrolysis processes in Puverized Coal(PC) furnace or boiler have been significantly dealing in a radiative heat transfer and an additional source of NOx. Furthermore, the increasing for the use of a coal with low caloric value gives rise to a lot of tar-soot yield and LOI in a recycled ash for using cement materials. So, the ash with higher tar-soot yield and LOI can not recycle due to decreased strength of concrete. In this study, tar-soot yields and flame structures were investigated using the LFR for a blending combustion with bituminous coal and sub-bituminous coal. Also, The investigation were conducted as each single coals and blending ratio. The coals are used in a doestic power plant. In the experimental results, sub-bituminous coal with high volatile contents shows longer soot cloud length than bituminous coal, but overall flame length was shorter than bituminous coal. Tar-soot yields of sub-bituminous coal is lower than those of bituminous coal. Combustion characteristics are different between single coal and blended coal. Therefore, finding an optimal coal blending ratio according to coal rank effects on tar-soot yields.

미분탄의 연소 또는 열분해 과정으로부터 발생하는 tar-soot는 복사 열전달 및 질소산화물의 추가적인 발생 원인이라는 관점에서 의미 있게 다루어지고 있다. 최근 저열량탄이 증가함에 따라 시멘트의 원료로 재활용되던 석탄회에서 다량의 미연분과 tar-soot가 포함되어 오히려 다시 반입되는 사례가 빈번해지고 있다. 따라서 본 연구에서는 저열량탄 사용 확대에 따른 혼탄연소 조건에서 tar-soot의 배출특성을 살펴보기 위해 반응기로써 LFR(Laminar Flow Reactor)을 적용하였으며, 연료로는 현재 국내발전소에서 사용 중인 역청탄 2종(MOUNTAIN, MACARHTUR)과 아역청탄(KPU)을 이용하여 단탄별 tar-soot 배출특성과 혼소비에 따른 배출특성을 화염의 구조 변화와 함께 측정하였다. 휘발분이 많은 아역청탄의 soot cloud 길이는 역청탄에 비해 길었지만 전체적인 화염 길이는 짧아졌다. 단탄별 실험결과에서는 역청탄의 tar-soot 발생량이 아역청탄의 발생률보다 높았으며 역청탄 중 휘발분 함량이 많은 MOUNTAIN탄이 상대적으로 휘발분 함량이 적은 MACARHTUR탄의 tar-soot 발생률보다 높았다. 혼소시에는 단탄의 연소특성과는 다른 새로운 특성을 나타내었으며 저열량탄과 혼소되는 역 청탄의 종에 따라 tar-soot 발생량이 지배되는 것을 확인하였으나 혼소비에 따른 평균적 특성이 아닌 완전히 차별되는 배출특성을 나타냄에 따라 석탄의 등급에 따라 최적의 혼소비를 찾아서 연소시키는 것이 tar-soot 발생량을 줄일 수 있는 방법임을 의미한다.

Keywords

Acknowledgement

Supported by : 한국에너지기술평가원(KETEP)

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