報告書番号

V14008

タイトル（和文）

バイオマス残渣の燃料利用技術の探索─褐炭-バイオマス残渣混合ペレットの試作─

タイトル（英文）

Investigation on low-cost utilization technology of biomass residues -Evaluation of brown coal/biomass residues mixure pellets-

概要 （図表や脚注は「報告書全文」に掲載しております）

褐炭採掘地で調達可能なバイオマス残渣として、米糠、ジャトロファ搾油かす、ユーカリチップを選定し、褐炭との混合ペレットを試作し、燃料としての特性を調べた。その結果、混合ペレットの水分を15wt%に調整した場合、褐炭混合率は1割未満に限定されるが、バイオマス残渣の混合により発熱量は大幅に改善された。発熱量の高い褐炭-米糠混合ペレットを対象に、褐炭混合率がペレット性状に与える影響を調べた結果、褐炭混合率の増加に伴いペレットの機械的耐久性注は向上するが、発熱量を維持するためには、褐炭混合率を50 wt%程度に抑える必要があると考えられた。この場合、褐炭の輸送・貯蔵で問題となる自然発火性が抑制される可能性が示唆された。また、この混合ペレットを石炭代替として燃料利用した場合、石炭燃焼に比べて60%のCO2排出削減になると見積もられた。

概要 （英文）

Low-grade coals, such as brown coal, are characterized as low calorific value due to the high moisture content. In addition, the storage and transportation of brown coal are difficult because of their self-igniting. Although their reserves are large, their use is mainly limited to mining areas. For the purpose of upgrading and utilizing brown coal, pelleting with biomass residue was examined. Rice bran, Jatropha extracted residue and Eucalyptus tips, which are available in local mining areas (Australia and Indonesia), were selected as sample biomass residues.
When the moisture content of mixed power was adjusted at 15 wt%, which is a suitable moisture for wood pellets, the coal mixture pellets with rice bran or Jatropha extracted residue formed preferred pellets and their calorific value were improved, though coal ratio was limited to under 10 wt%. On the other hand, pellets with Eucalyptus tips were inferior for moldability. In the case of varied coal ratio, the brown coal/rice bran mixed pellets showed improved moldability; however, the calorific value was decreased as the coal ratio increased. In order to maintain the calorific value of the pellets, the coal mixing ratio was better under 50 wt%. In this case, the ignitability was controlled. If the mixing pellet (brown coal : rice bran = 50:50) was burned as a fuel instead of coal, it was estimated to be a 60% reduction in CO2 emission, compared to the alternative of steam coal.

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