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[摘要]：When gasifying biomass in an entrained-flow type gasifier with steam and oxygen at 900-1000 degrees C, cold gas efficiency was high, and consequently, char, gasification byproduct, contained relatively large amounts of carbonated alkali and alkali earth metals. An elemental analysis of this sort of char resulted in substantial error, especially oxygen content, when applying a method developed for analyzing coal, because the carbonated alkali and alkali earth metals were oxidized through heating in air or ashing pretreatment at 815 degrees C. To clarify effects of the pretreatment, 23 kinds of biomass were ashed at 600 degrees C and 3 of them were ashed at temperature ranging from 600 to 900 degrees C. Various kinds of metallic compounds remained after ashing at 600 degrees C, however almost all of them were oxidized or recomposed to be more stable at above 800 degrees C. Potassium compounds vaporized more as ashing temperature rose. The temperature of the melting point dropped, especially under reducing atmosphere, as ashing temperature dropped and the potassium compounds increased. |
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