| 摘要: | 稻草(rice straw)、稻?rice hull)、蔗渣(sugarcane bagasse)及椰子殼(coconut shell)為台灣最主要的農業廢棄物，目前的處理/處置方式大多乃採用就地處置、露天焚化及任意棄置，卻也造成空氣污染、溫室效應氣體CO2 排放等環境問題。國內有關將這些生質廢棄物轉化為生質燃油生產之研究則相當有限。熱裂解為一種熱化學程序，可有效地將生質物於缺氧及適當溫度條件下，轉化為生質焦油、焦碳及非凝結性氣體。
本研究探討藉感應加熱快速熱裂解技術轉化國內大宗農業廢棄物為生質燃油之可行性；藉由控制快速熱裂解反應爐的停留溫度、升溫速率、停留時間和氣體流量等四個主要操作條件，在輔以樣品粒徑大小及冷凝收集溫度的試驗條件，來求取生質燃油的最佳產率。研究結果顯示，除了氣體流量大小的影響較不明顯外，其餘操作條件對於生質燃油產率皆有所影響；四個農業廢棄物最佳的生質焦油產率分別是稻草為40.90 %、稻殼為40.57 %、蔗渣為49.83 %和椰子殼為39.66 %。
對冷凝收集的生質焦油產物做其物理/化學特性分析，包括熱值、主要元素、pH值、傅利葉紅外線光譜(FTIR)及氣相層析質譜(GC-MS)，顯示所得之產物熱值偏低、呈現酸性、含氧量偏高，並富含多環芳香族碳氫化合物(PAHs)，若要實際運用所得產物，則須進一步提昇(upgrading)。倒是經快速熱裂解後的焦碳產物，因其熱值可高達6500 kcal/kg，可成為好的固態燃料外，也可進一步活化製造出活性碳。
In Taiwan, rice straw, rice hull, sugarcane bagasse and coconut shell are the most primary agricultural wastes. The current approaches for treatment/disposal of these biomass wastes are the farmland disposal, open burning and arbitrary dumping. However, these methods will generate serious environmental problems, such as air pollution and greenhouse gas (e.g. CO2) emission. With respect to the domestic studies of the biomass fuel production from agricultural wastes, the information published is limited. Pyrolysis, a promising route for biomass utilization, is the thermochemical process that converts biomass into liquid (bio-oil), charcoal and non-condensable gases by heating the biomass at intermediate temperature in the absence of air.
The objective of the research is to study the feasibility of using fast pyrolysis technology with induction heating for manufacturing the bio-fuel from the main agricultural wastes in Taiwan. Under the conditions of controlling holding temperature, heating rate, hold time, inert gas flowrate, sample particle size and condensation temperature, the optimal yield of bio-oil was approached in the present study. The experimental results showed that these operating parameters, exclusive of inert gas flowrate, had significant effect on the yield of bio-oil, which could be obtained at the percentages of 40.90, 40.57, 49.83 and 39.66 for rice straw, rice hull, sugarcane bagasse and coconut shell, properties respectively.
The physical and chemical of bio-oil collected from the cryogenic condensation were further conducted, including heating value, elemental analysis, pH value, Fourier Transform infrared (FTIR) and gas chromatograph-mass spectroscope (GC-MS). The characteristics of bio-oil showed to be low heating value, acidic, high content of oxygenated components and polycyclic aromatic hydrocarbons (PAHs)-rich. Therefore, the bio-oil must be further upgraded while it was practically used. Another product charcoal after fast pyrolysis can become a solid fuel due to its high heating value (about 6500 kcal/kg), or be further activated to produce activated carbon. |
