氧氣氛對生質物低溫炭化反應之影響

在全球能源耗竭與溫室效應之雙重壓力下，生質物生長和燃燒因具有碳中和之特性，故成為近年崛起之再生新興燃料。理論上，低溫和絕氧之炭化反應可用來改良生質物作為能源材料之相關特性，基於製程上絕氧之技術難度和成本負擔，本研究進行一系列試驗，探討不同氧氣氛對生質物低溫炭化反應之影響。以油棕果纖維、椰殼纖維、尤加利木及柳杉木作為生質物試樣，炭化試驗條件為溫度300℃，炭化時間1小時，以不同比例之氮氣與空氣混合來改變氧氣氛範圍（0-21 vol%）和流量。由試驗結果顯示，生質物炭化反應氣氛中若含有氧氣，對生質物之炭化產物產率、熱值及能量留存率所造成之影響，皆與生質物於炭化過程中所接觸到之氧量呈負向關係；對不同生質物試樣，其影響效應由大至小排序為椰殼纖維、油棕果纖維、柳杉木及尤加利木。炭化纖維類及木質類生質物之低溫炭化氧濃度若分別控制在5及10 vol%以下，氧氣氛對其產物產率及品質之影響屬輕微，故考量炭化製程設計和操作，主張以低氧含量氣體或回收燃燒廢氣作為生質物炭化之直接加熱氣體，應可減輕炭化製程之技術困難度和生產成本。

關鍵字

生質能；生質物；低溫炭化；氧氣氛

並列摘要

In view of global warming effects and diminishing fossil fuel resources, biomass is becoming an important source of renewable energy. The biomass can be upgraded via torrefaction (low temperature carbonization) in an inert atmosphere. The purpose of this study is to evaluate the potential of torrefying biomass with low oxygen concentration. In this research, the oil palm fiber, coconut fiber, eucalyptus and cryptomeria japonica were torrefied at 300℃ for 1 hour under the atmospheres with oxygen concentrations from 0 to 21 vol%.The experimental result indicated that the higher the oxygen concentration, the lower the solid yield, heating value and energy yield of the torrefied biomass samples. Coconut fiber is most sensitive to the oxidative atmosphere, followed by oil palm fiber, eucalyptus and cryptomeria japonica. We also found that the torrefaction of fiber and ligneous biomasses under weak (5 and 10 vol% oxygen) oxidative atmospheres has very slight effects on the yield and qualities of the torrefied biomass. If the torrefaction is carried out under the weak oxidative atmospheres using combustion chamber flue gas as the direct heating media, the torrefaction processes will have higher efficacy thus operation cost.

並列關鍵字

energy ； biomass ； low temperature carbonization ； oxidative atmospheres

國際替代計量

氧氣氛對生質物低溫炭化反應之影響

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