19.石炭の熱分解過程から放出される金属の挙動と炭素含有率との関係

抄録

Six Chinese coals were subjected to pyrolysis in N_2 at the temperatures ranging from 1200 to 1450℃. Emission of metals and their combination with the organic carbon were studied by investigating the properties of sub-micron particles formed from coal pyrolysis. The sub-micron particles were size-segregated by low-pressure-impactor; each size was characterized for its elemental composition, microstructure, etc. Finally, the emission of individual metal was linked with its existence in raw coals. The results indicated that, a multi-mode distribution was formed for most of the metals during coal pyrolysis. At least three peaks, 0.06 or smaller, 0.2 and 2.5μm were formed. The smallest one was assigned as those formed by the decomposition of organically bound metals in raw coals, the medium size was caused by the release of included inorganic metals in the char, whereas the largest one was to large extent linked with the excluded inorganic metals in raw coals. The emission degree as well as the magnitude of each peak in the particle size distribution varies with the elemental type greatly. The influence of reaction temperature was significant too.