回收蒸煮處理纖維之性質與再利用

Abstract

臺灣生活垃圾中有近40 %有機纖維，包含無法回收紙類廢棄物與庭園廢棄物，本研究選用都市常見之生活垃圾與廢棄之稻草為材料，將都市生活垃圾透過蒸煮，取出其中有機纖維之成分，一方面藉由焙燒(Torrefaction)提升其能源密度，一方面抄造成板，探討後續多元化利用；廢棄稻草則同樣經由焙燒來提升其能源密度，並將發酵後稻草與都市生活垃圾中取出的有機纖維混合抄造成板。另本研究亦利用基辛格法(Kissinger method)、大澤法(Ozawa method)及直接藉由阿瑞尼士(Arrhenius)反應速率關係式，探討稻草焙燒前後之活化能差異，以瞭解產物之熱穩定性。 焙燒為經過250-290 °C等不同溫度處理，並持溫60-90 min。生質物經焙燒處理後可視為生質煤，接續進行元素分析(Ultimate analysis)及熱值(High heating value, HHV)和熱重分析(Thermogravimetric analysis, TGA)等。造粒(Pelletization)方式採環模式擠壓造粒機進行，抄造紙板則採用CNS11212物理試驗用手抄紙方式，利用手抄紙機混合不同比例之垃圾與發酵後稻草抄造成垃圾纖維板，並檢測纖維板之物理強度。 本研究結果發現，垃圾纖維中之纖維素含量將近70 %，木質素含量則≦10 %，如此組成分影響造粒，致使顆粒堅牢度(Pellet durability index, PDI)不符一般使用需求。由元素分析結果觀之，焙燒後各種生質物碳含量增加、氫及氧含量降低，使生質物性質趨近燃煤，尤其在270 °C、持溫60-75 min效果最好，在提升能源密度及節省成本之考量上，均為最佳條件。而透過基辛格法、大澤法與阿瑞尼士反應速率關係式等3種方式計算活化能，前兩者結果相近，但後者則有顯著差異。抄造成纖維板後，其力學表現除內聚強度外，抗彎強度、螺釘保持力及抗拉強度皆隨著稻草纖維比例的增加而下降。

Nearly 40 % of organic fibers in urban waste in Taiwan, contains unrecoverable paper waste and garden waste. In this study, urban waste and waste straw were used as materials. Organic fibers were taken out by autoclaving, then made to fiberboards. On the other hand, the energy density was increased by torrefaction. Waste straw also enhances its energy density through autoclaving, and mixes the fermented straw with the organic fibers taken out from urban waste to make fiberboards. In addition, this study also uses the Kissinger method, Ozawa method and the Arrhenius equation to investigate the difference in activation energy after autoclaving of waste straw to understand the thermal stability of the product. The torrefection is taken at temperatures of 250 to 290 °C, and maintaine the temperature for 60 to 90 minutes. The biomass can be regarded as raw coal after torrefection, and subsequent experiment with ultimate analysis, high heating value and thermogravimetric analysis. The pellets were manufactured by ring die pellet mill, and the fiberboards is made according to CNS11212 which is the method of preparation of handsheets for physical testing. The fiberboards were mixed with different proportions of urban waste and fermented straw, and the physical strength of them were detected. The results showed that the cellulose content in the waste fiber is nearly 70 %, and the lignin content was below then 10 %. Such composition affected the pelletization, resulting in the pellet durability index did not meet the general needs. According to the results of elemental analysis, the carbon content increased while the hydrogen and oxygen content decreased after torrefection, and the properties of biomass were approached to coal, especially at 270 °C that remains 60 to 75 minutes, and the energy density was improved as well. Also it was the best condition for cost-saving. The activation energy was calculated by three methods, Kissinger method, Ozawa method and Arrhenius equation. The results of first two were almost the same, but the results of Arrhenius equation were significantly different. The mechanical properties like bending strength, screw holding capacity and tensile strength decreased as the amount of straw fibers increase, only internal bond strength shows the opposite way.