Fast Pyrolysis of Palm Kernel Shell Biomass in Fluidized Bed Reactor

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題名:	Fast Pyrolysis of Palm Kernel Shell Biomass in Fluidized Bed Reactor
作者:	歐識賢;Firdaus,Ahmad Hanif
貢獻者:	機械工程學系
關鍵詞:	生質能;棕梠殼;生質油;熱裂解;Biomass;palm kernel shell;fast pyrolysis;bio-oil
日期:	2014-08-04
上傳時間:	2014-10-15 17:19:44 (UTC+8)
出版者:	國立中央大學
摘要:	摘要在這篇論文中，以流化床反應器及陶瓷球作為流化介質，且以CO2 作為流化氣體去熱裂解棕梠殼(PKS)，研究的目的為找出反應器溫度 (350~500 ºC)、流化氣體流速 (5-15 liter/min)及昇熱速率 (1, 5, 10 K/min) 對熱裂解後各項產物(生質油、生質氣體及生質能碳)含量的影響。PKS的產物含量分析是依照美國材料和試驗協會(ASTM)標準辦法分析。在這次研究成果顯示，生質油在反應器溫度為500 ºC且CO2流量為10 liter/min能得到最大的產量 (20.43 wt.%)，而在這樣的操作條件下，生質能碳為35.96 wt.%而生質氣為43.61 wt.%。且生質能碳的含量會隨著反應器溫度和CO2流量增加而減少，反之生質氣體含量則是會隨著反應器溫度和CO2流量增加而增加。從TGA分析可以觀察到，重量損失分成三個部分。首先發生在100 ºC到220 ºC此階段為水氣及雜質的蒸發。再者是在240 ºC到400 ºC為纖維素及半纖維素的分解和最後400 ºC到900 ºC為木質素的分解。DTGA的部分，可以觀察到兩個很明顯的峰值，第一個為揮發掉半纖維素的可揮發物質，第二個為揮發掉纖維素的可揮發物質。而在DTGA中隨著昇溫速率的提升，會使這兩個峰值往右提升，在1 K/min第一和第二個峰值發生在 280 ºC and 380ºC 在 5 K/min 發生在 305 ºC and 390 ºC 及 310 ºC and 405 ºC 在 10 K/min。在探討生成物的組成成分，生質油部分碳氫氮氧成分分別為:67.70 wt.%、9.70wt.%、0.9wt.%和 21.7wt.%，在生質能碳的部分擁有較高的碳含量，大概在62.87wt.%左右，其他元素組成則有，2.54wt.%的氫、0.56wt.%的氧、0.01wt.%的硫和10.80wt.%的氧，PKS成分分析部分，有 23.18wt.%是灰燼、3.30wt.%是水氣、17.86wt.%是揮發物及58.96wt.%為碳化物，且PKS擁有相當高的熱值，約為23.56MJ/kg。當使用CO2當流化氣體時，所產出的生質氣體成分組成，跟先前研究做出來的結果相符，大部分產出物為CO2(超過50 vol.%)，剩下主要為CO還有少量的CH4 和H2 關鍵字:生質能、棕梠殼、生質油、熱裂解;ABSTRACT In this thesis, palm kernel shell (PKS) biomass are pyrolyzed in a fast pyrolysis system using fluidized bed reactor and ceramic balls as fluidizing medium, with CO2 as fluidization gas. The purpose of this research is to find the effect of operating parameters, such as reactor temperature (350º - 550ºC), fluidizing gas flow rate (5-15 liter/min) and heating rates (1, 5, 10 K/min) on the yield of each pyrolysis product (bio-oils, gas, and char). The composition of PKS biomass and their product are investigated according to ASTM (American Society for Testing and Materials) standard methods. The result shows that the maximum bio-oil yield is 20.4 wt.%, occurred at 500ºC and the ﬂow rate of CO2 is 10 liter/min, the other product are char with 36.0 wt.% and gas with 43.6 wt.%. Char decreases with increasing reactor temperature and CO2 flow rate. A opposite, the gas product increases with increasing reactor temperature and CO2 flow rate above 10 liter/min. From TG (thermogravimetry) and DTG (differential thermogravimetry) analysis, the weight loss are generally divided into 3 parts. First, occurred from 100ºC to 220ºC, presented the moisture and extractive evaporations. The second weight loss occurred at 240ºC - 400ºC, the thermal decomposition of cellulose and hemicellulose and the third, the weight loss above 400ºC until 900ºC is mainly due to the decomposition of lignin. The DTG curves have two peaks. The ﬁrst peak is assigned to devolatilization of hemicellulose, while the second peak is cellulose. The effects of the heating rate on the DTG curve and maximum decomposition rate are investigated. At higher heating rates, individual conversions are reached at higher temperatures. For the heating rate of 1 K/min, the first and second peak occurred at 280 ºC and 380ºC. For 5 K/min, they occurred at 305 ºC and 390 ºC. They occurred at 310 ºC and 405 ºC for 10 K/min. The maximum of the decomposition rate is also slightly shifted towards higher temperature. CHNO content of bio oils are 67.70 wt.%, 9.70 wt.%, 0.90 wt.%, and 21.70 wt.%, respectively. Bio-char have high carbon content, around 62.87 wt.%, other elemental compositions are 2.54 wt.% of hydrogen, nitrogen with 0.56 wt.%, 0.01 wt.% for sulfur, and oxygen with 10.80 wt.%. Proximate analysis of PKS bio char gets 23.18 wt.% of ash, 3.30 wt.% of moisture, also HHV, volatile matter, and fixed carbon with 23.56 MJ/kg, 17.86 wt.%, and 58.96 wt.%, respectively. When using CO2 utilized as ﬂuidization gas, the gas product has compositions similar to previous study, and consists mostly of CO2 (Over 50 vol.%), followed by CO, and little amount of CH4 and H2. Keywords: Biomass, palm kernel shell, fast pyrolysis, bio-oil
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