Investigation of microwave-assisted pyrolysis of biomass with char in a rectangular waveguide applicator with built-in phase-shifting
Investigation of microwave-assisted pyrolysis of biomass with char in a rectangular waveguide applicator with built-in phase-shifting
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DOI：
10.1016/j.apenergy.2019.114217
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发表时间：
2020-02
期刊：
影响因子：
11.2
通讯作者：
Candice R. Ellison;Ryan Hoff;C. Marculescu;D. Boldor
中科院分区：
文献类型：
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作者：
Candice R. Ellison;Ryan Hoff;C. Marculescu;D. Boldor
生物质快速热解是将生物质热化学转化为化学品和生物燃料（生物油和合成气）的一种很有前途的技术。微波加热可以提高工艺效率。研究了微波吸收剂和微波功率对热解过程温度、产物收率和产物组成的影响。设计了一种新型的微波系统，该系统具有连续滑动短路，从而实现相移，以减轻低损耗负载中的驻波效应。采用4 × 3全因子实验设计，在不同的微波输入功率（600、900、1200和1500 W）和不同的生物炭添加量（0、10和20%）下，对松木屑进行了热解实验。在没有微波吸收剂的帮助下，松木锯屑无法通过介电加热达到热解温度，即使在1500 W功率下也仅达到200 °C。热解产率与吸收功率而不是输入功率相关，因为温度与吸收功率相关性更强。添加生物炭被发现有显着影响的吸收功率和热解温度，增加4倍，从0%到10%的炭，但是，没有显着差异时，发现炭混合物从10增加到20%。炭的产率随着吸收的微波功率的增加而降低，而不凝性气体增加，这表明随着工艺温度的增加，热裂解为不凝性气体的增加。发现无水生物油产率随着吸收功率而增加。从微波热解的松木屑的液体产品主要是由酚类，在所有吸收功率的产率变化不大。随着吸收功率的增加，由于木质素分解的增加，羰基官能团和呋喃减少，而多环芳烃增加。观察到最大的净能量产率热解运行在900 W施加的微波功率和20%的焦炭。
Fast biomass pyrolysis is a promising technique for thermochemical conversion of biomass into chemicals and biofuels (bio-oil and syngas). Microwave heating can increase process efficiency. The effect of microwave absorber and microwave power level are studied for their effect on pyrolysis process temperature, product yields, and product composition. A novel microwave system was designed with a continuous sliding short enabling phase shifting to mitigate standing wave effects in the low loss load. Pyrolysis experiments on pine sawdust were carried out at varying microwave input powers (600, 900, 1200, and 1500 W) and with varying amounts of biochar added to the feedstock (0, 10, and 20% by weight) in a 4 × 3 full factorial experimental design. Pine sawdust without the aid of microwave absorber failed to reach pyrolysis temperatures by dielectric heating, only reaching 200 °C even at 1500 W power. Pyrolysis yields were correlated to absorbed power rather than input power as temperature is more strongly correlated to absorbed power. Addition of biochar was found to have a significant effect on the absorbed powers and resulting pyrolysis temperatures, increasing temperatures 4 fold from 0% to 10% char, however, no significant difference was found when char mixture was increased from 10 to 20%. Yields of char decreased with increasing absorbed microwave power, while non-condensable gas increased, indicating increased thermal cracking to non-condensable gases with increasing process temperature. Water-free bio-oil yields were found to increase with absorbed power. The liquid product from microwave pyrolysis of pine sawdust is composed primarily of phenols, with little changes in yield at all absorbed powers. Carbonyl functional groups and furans decreased while polyaromatics increased with increasing absorbed power due to the increased decomposition of lignin. The greatest net energy yields were observed for pyrolysis run at 900 W applied microwave power and 20% char.