- 學位論文
南台灣狼尾草低溫碳化燃料粒生產之經濟評估
Economic Assessment for the Production of Torrefied Pennisetum Pellets in Southern Taiwan
摘要
由於經濟的高度發展對能源需求增加，而石化燃料逐漸匱乏，因此再生尾草因生長快及熱值高，具高度的潛能成為未來生物質燃料之來源，在亞洲許多國家如菲律賓、印度及泰國政府已鼓勵農民種植狼尾草。台灣近年糖廠紛紛停業，可否轉型為生質能源廠值得探討。因此本研究的目的為模擬台糖善化廠之蔗田改為種植狼尾草，而經由乾燥、碳化及製造成燃料粒，探討其熱值的轉變及製成燃料粒之經濟可行性評估，並加入敏感度分析以評估各種參數對於成本回收年限之影響。 製造燃料粒過程乾燥及碳化，耗費大量能源，需借助外界燃料，以補碳化氣熱能之不足，其所需添加燃料量視生物質之含水率及物性而定。本研究利用Aspen Plus來模擬低溫碳化過程，以突破因碳化氣組成複雜，模擬困難之瓶頸，提出利用低溫碳化前後之元素分析（Ultimate element analysis）資料轉換成可輸入Aspen Plus之資料而計算出燃燒氣（flue gas）溫度及在低溫碳化、乾燥設備上能量之回收，並估算所需提供外界燃料之量。 燃料粒售價依據德國家庭用之木材燃料粒售價，並依熱值調整後作為收入，評估其回收年限為6.4年。但若將狼尾草燃料粒用於與煤混燒，因目前煤價低廉，惟將污染排放與排碳量之環境效益計入，並立法施行，狼尾草燃料粒才有可能取代部分燃煤。敏感度分析指出，曝曬後含水率、熱值與燃料粒售價對回收年限的影響最大，因此，將進工廠之含水率降低、選擇高熱值之品種及燃料粒售價提升，將有助縮短回收年限。
並列摘要
The demanding of study on biomass as the alternative energy for coal is rapid increasing owing to the fast growth of energy requirement in recent years. pennisetum has great potential to become future energy source because its high productivity and high heating value. In Asia, Philippine, India and Thai land government have encouraged farmers to increase the cultivation of pennisetum. This paper studied the Shanhua Sugar mill of Taiwan Sugar Corporation as an example to explore the feasibility of transformation from a sugar mill to energy farm of cultivation pennisetum. The process from plantation, transportation, dryer, torrefaction and pelletizaion to get the final pellet product was examined. In the torrefaction process, dryer and torrefier are the two units which consume most of the energy. This study used the experimental data of ultimate element analysis of pennisetum before and after the torrefaction to get the required data as input to Aspen Plus software to resolve the problem due to the complicated compositions of the gases from the torrefier. This method can be applied to other torrefaction applications such as sewage sludge. The pay-off period is around 6.4 years if the selling price of pellet is based on the wood pellet price of Germany used in the household with the price adjusted with heating value. However the economic is not feasible if the selling price based on coal. Some major different factors affecting the pay-off period are also studied. The results indicate that the water content, heating value and selling price are the major factors affecting the feasibility of production pennisetum as an alternative bioenergy.