Biomass may ignite due to biological oxidation and chemical oxidation. If this phenomenon (spontaneous ignition) is controlled, it would be possible to produce biochar at a lower cost without the need for an external heat resource. We investigated if selfheating could be controlled by using sawdust and bark chips. When sawdust and bar chips were used under controlled conditions, the bark chips temperature increased to the torrefaction temperature. The ash content of bark chips was approximately 2%d.b. higher than that of sawdust; consequently, the inorganic substances contained in the bark chips might affect the self-heating. Self-heating was suppressed when inorganic substances were removed by washing with water. Therefore, the inorganic substances in the biomass might have affected self-heating. The potassium content of the bark chips was reduced remarkable by washing, and there was a possible influence of potassium on self-heating. Finally, the effect of moisture content on self-heating was investigated to obtain stable reactivity. Thus, at a moisture content of 40%w.b., a steady self-heating behavior may be realized.
木質バイオマスに含まれる無機物が自己発熱へ及ぼす影響
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