微波誘發焙燒銀合歡廢材作為生質炭之研究

Abstract

世界對於能源的需求日益增加，但化石燃料面臨短缺，並且排放大量溫室氣體造成全球暖化，因此發展替代能源勢在必行，其中又有核能、太陽能、風力發電以及生質能等方式。而生質能源目前為世界能量供應之第四位，並已有生質酒精、生質柴油、生質炭、生質燃氣等發展，其中生質炭部份的研究，希望將其能量提升，以便和煤炭做混和燃燒發電或替代煤炭，在其他火力發電設備不變之情況下繼續發電。 本研究設法利用銀合歡，此一台灣外來種植物，透過微波誘發焙燒的方式，發展生質碳，分析其固相產物成分，並計算相關耗能，提出未來應用之建議。 微波誘發焙燒方式，採用單模聚焦式微波爐，利用微波加熱樣品，在焙燒條件下，製成生質炭，而焙燒方法為熱處理程序中較低溫之碳化程序，廣義溫度範圍介於200~400°C之間，並輸入氮氣使實驗環境呈現缺氧狀態，生成物以固相為主，即可獲得較多的生質碳。 實驗過程之操作參數，其微波功率設定在100W、150W、200W、250W，並分別以15min、20min、25min、30min進行實驗。結果顯示，微波功率越大，失重率越高，熱值越高，其所含之固定碳成分比例越高，而揮發份比例降低。並且，本實驗結果明顯分為兩個區間，低功率與高功率組，於低功率組(100W、150W)，時間對於樣品之影響較大，而於高功率組(200W、250W)，樣品失重已落於70~80%，顯示拉長時間，對於熱值之貢獻程度較小。就整體表現而言，250Wto30min產物熱值最高，為7085.9cal/g(29.63MJ/kg)，而能量密度也最高，為1.62；200Wto30min產物燃料比最高，但兩者缺點為失重率分別高達82.74%以及78.6%。 近似分析結果，當功率越高固定碳會增加，揮發分會下降，灰分會增加，以結果看來，200Wto30min的固定碳比例最高，揮發分比例最低，灰分也不高。最後，計算產能部份，發現因本實驗設備進料過少，導致焙燒耗能相對很高，為預期生產之能量的105.6倍，因此情假假設後，當進料從8g提升至1000g， 250Wto15min的發電量變為焙燒耗能的3.18倍。

The world's demand for energy is increasing, but we faced the shortage of fossil fuels which emits greenhouse gases and cause global warming. We are in urge to develop alternative energy sources, of which there are nuclear, solar, wind power, biomass energy and other means. The biomass energy is currently the fourth in the world's energy supply, and there are bio-ethanol, biodiesel, bio-char, bio- gas etc. Most of the study about bio-char, is contributing to enhance its energy, so that we can mix coal and bio-char to have mixing combustion for power generation. Or use bio-char to replace coal. In those two situations, we don’t have to change our power plant equipment. Therefore, this study tries to use leucaena which is alien species in Taiwan, to develop bio-char by microwave-induced torrefaction process. Then, analyzing its’ solid product ingredients, calculating the correlation energy, and finally suggests the future applications. In this studying, we use single mode microwave device to processing our microwave-induced torrefaction experiment. The sample was heated by torrefaction condition, which is a carbonization process in a lower temperature( 200 to 400℃) and create an anoxic state by entering nitrogen gas, then finally we can gain more solid phase product(bio-char). The results showed that when the microwave power is increasing, we gain the higher weight loss rate, calorific value , fixed carbon and lower volatile matter. In the result, when operating at 250Wto30min, we gain the highest calorific value for 7085.9cal / g (29.63MJ/kg), and the highest energy density for 1.62; we gain the maximum fuel ration at 200Wto30min, but the disadvantage of them is the highly weight loss rate: the former is 82.74% and the latter is 78.6%. About approximate analysis results, when the power is increase, causing the products’ contain more fixed carbon, less volatile. Finally, we find the energy cost is 105.6 times by energy produce in this experiment. But if we increase our material mass from 8g to1000g, operating at 250Wto15min, the energy-generating capacity will be 3.18 times to the cost.