柳杉與粗甘油之混合造粒及氣化研究

生質柴油轉酯化製程中會伴隨產生大量之粗甘油，因此如何提高粗甘油副產物利用價值，並減少對環境的衝擊，乃成為近幾年來重要之研究課題。本研究主要分為 2 個部份，先以環模造粒機對以不同比例粗甘油混合柳杉造粒並探討柳杉顆粒、粗甘油與混合顆粒如熱值、整體密度、顆粒堅牢指數等基本性質。再於30 kWth氣泡式流體化床氣化試驗系統進行混合氣化，以探討氣化溫度、空氣等值比、混合比例及注入蒸氣對混合氣化之合成氣組成、合成氣低熱值及合成氣中焦油含量的影響。造粒結果顯示隨粗甘油混合比例增加，顆粒熱值上升。此外，添加粗甘油造粒更可使顆粒之容積密度些微提升，但添加比例超過15%後，容積密度有下降的趨勢。混入粗甘油造粒可使原料與模孔間摩擦力降低，故加入粗甘油可降低造粒耗能。添加粗甘油增加氫鍵量，使顆粒堅牢指數及產率大幅提升，其中以添加比例10%為最佳，但混合粗甘油超過15%後，顆粒堅牢指數及產率明顯下降，主因為粗甘油使木屑表面鈍化，並使混合木料與環模之摩擦力下降，而阻礙木屑間的固體架橋所致。混合氣化結果顯示，隨著粗甘油比例的增加，合成氣中、CH4、H2、焦油皆有上升的趨勢，CO與低位熱值有先增後減的趨勢，CO2則有相反的現象發生。此外，在有添加20%粗甘油的條件下，有發生燒結現象，這是因為Na+含量過高，造成床區燒結及去流體化等問題。綜合實驗結果，最適之柳杉混合粗甘油造粒比例為10%。

關鍵字

生質能源；粗甘油；柳杉；成型顆粒；混合氣化

並列摘要

Crude glycerol is the principal by-product of biodiesel production. About 10% crude glycerol will be produced during the production of biodiesel. Therefore, it’s very important to utilize crude glycerol for increasing the economic viability and decreasing environmental impacts. This study provides a considerable way to utilize crude glycerol, and investigates ring-die pelletizer to densification of sawdust mixed with crude glycerol in various adding levels. Gasification also present on this study. A 30 kWth bubbling fluidized bed gasifier to investigate the effect of using different crude glycerol mixed ratios pellet to co-gasified on syngas compositions, the lower heating value, and tar content, etc. The mixed pellets results showed that increase higher heating value increased with crude glycerol ratio, and crude glycerol also benefit to pellets bulk density, but decrease after loading 15(wt%). Crude glycerol can reduce the friction between the press channel and raw materials, so adding crude glycerol can reduce pellets energy consumption granulation. It is possible that crude glycerol provides many hydrogen bonds between the wood polymers are substituted with bonds to fatty acid molecules, thereby reducing the strength of the pellet. However, a required amount of crude glycerol could improve inter-particular attraction. The pellet durability index (PDI) and productivity increase in adding crude glycerol ratio of 10(wt%), but decreased after adding 15 (wt%). After gasification of above pellets, the CH4, H2, tar content and lower heating value of syngas decrease with increasing the crude glycerol ratio, but CO and lower heating value content of syngas increased firstly then decreased with increasing the mixed ratio.