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열분해 속도에 따른 챠의 표면 및 반응특성변화

Variation in the Surface and the Gasification Properties of Coal Chars with Pyrolysis Rates

HWAHAK KONGHAK, April 1993, 31(2), 235-243(9), NONE
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Abstract

인도네시아산 갈탄과 중국산 역청탄을 질소분위기에서 700℃까지 1℃/min-150℃/min 범위 내의 각각 다른 승온속도로 가열하면서 열분해시킨 후에 얻어진 석탄챠에 대하여 수증기 가스화 반응특성을 비교하였다. 상압의 고정층 반응기에서 가스화 반응을 수행하였는데 반응온도는 800-1000℃,수증기의 분압은 0.26-0.57기압의 범위에서 변화시켰다. 150℃/min의 가열속도하에서 고속 열분해된 챠(fast char)가 25℃/min 이하의 저속에서 열분해된 챠(slow char)보다 항상 빠른 가스화 반응속도를 보였으나 겉보기 활성화 에너지는 각각 114KJ/mol과 113KJ/mol로서 거의 차이가 없었다. 챠의 표면적을 질소, 이산화탄소의 흡착실험으로 측정한 결과 서로 상반된 결과가 얻어졌는데, 이는 시료들의 미세기공구조 차이 때문인 것으로 판단된다. 이산화탄소 흡착을 기준으로 한 표면적은 fast char가 slow char보다 더 컸다. Fast char는 미세기공들이 많이 형성된 것을 기체 획산실험을 통하여 확인 하였는데 fast char가 높은 가스화 반응속도를 보이는 것은 주로 이같은 물질적 특성 때문인 것으로 해석된다.
Indonesian lignite and Chinese bituminous coal were pyrolyzed under different heating rates be-tween 1℃/min and 150℃/min, and the chars obtained thereby were steam-gasified in a fixed-bed micro-reactor at temperatures between 800 and 1000℃ and under the steam partial pressures between 0.26 and 0.57 atmo-spheres. The chars obtained by fast pyrolysis at the heating rate of 150℃/min exhibited higher gasification of gasification of the two samples were almost same : 114KJ/mol and 113KJ/mol. The char surface areas esti-mated by gas adsorption exhibited opposite results depending on the adsorption gas, N2 or CO2. The surface areas estimated from CO2 adsorption were higher for the fast-pyfrolyzed chars than for the slowly-pyrolyzed ones. Formation of many micropores in the fast-pyrolyzed chars, evident from transient pressure change in the adsorption experiment, was responsible for the relatively high gasification rates.

Keywords

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