洁净煤技术

2021, v.27;No.132(02) 161-169

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生物质三组分在O_2/CO_2气氛下的着火行为研究
Ignition behaviors of the three components of biomass in O_2/CO_2 atmosphere

程偲哲;邹春;姚青;娄春;王树森;经慧祥;梅媚;
CHENG Sizhe;ZOU Chun;YAO Qing;LOU Chun;WANG Shusen;JING Huixiang;MEI Mei;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;Key Laboratory of Healthy &Intelligent Kitchen System Integration of Zhejiang Province;Ningbo Fotile Kitchen Ware Company;

摘要(Abstract):

生物质的富氧燃烧技术结合了生物质燃烧与富氧燃烧的优点,既能减少化石燃料的使用,又易实现CO_2捕集。富氧燃烧的最显著特点是气氛中的氧气体积分数大于21%,其对生物质着火行为的影响至关重要。纤维素、半纤维素和木质素是生物质的3种主要组分,研究其在富氧条件下的着火及燃烧行为,可为生物质的着火及燃烧行为研究提供重要依据。利用滴管炉结合高速摄像机,研究了粒径74~154μm的纤维素、半纤维素和木质素在温度1 273 K,氧气体积分数21%、30%、50%、70%和100%的O_2/CO_2气氛中的着火行为,并利用辐射能测温技术计算着火图片中的颗粒温度。结果表明,随着O_2体积分数增加,纤维素、半纤维素由联合着火以及木质素由均相着火均转为非均相着火,纤维素、半纤维素、木质素着火机理发生转化的O_2体积分数分别为30%、70%和50%。纤维素着火对O_2体积分数变化敏感,氧气体积分数超过30%时,纤维素焦率先发生着火。半纤维素和木质素的升温速率随氧气体积分数的升高而提高,半纤维素是由于挥发分在燃烧过程中随着氧气体积分数的增加,其燃烧比例减弱,焦燃烧比例增加,而木质素因为氧气体积分数的升高强化了木质素焦燃烧。半纤维素和木质素燃烧时间均随氧气体积分数的升高而缩短,两者都是由于氧气体积分数升高强化了焦的燃烧。另外,在较高氧气体积分数下木质素焦会发生熔融并膨胀,形成明显的膨胀火焰。
The oxy-fuel combustion of biomass technology combines the advantages of oxy-fuel combustion and biomass combustion,which can not only reduce the consumption of fossil fuels,but also easily achieve CO_2 capture. The most significant feature of oxy-fuel combustion is that the oxygen concentration in the atmosphere is more than 21%,which has a significant effect on the ignition behavior of biomass. Cellulose,hemicellulose,and lignin are the three main components of biomass. Therefore,studying the ignition and combustion behavior of these three components under oxy-fuel conditions is the basis for the study of biomass ignition and combustion. In this work,a drop tube furnace combined with a high-speed camera were utilized to study the ignition behaviors of cellulose,hemicellulose,and lignin particles of 74-154 μm at the temperature of 1 273 K under O_2/CO_2 atmosphere with oxygen concentration of 21%,30%,50%,70%,and100%. The radiant energy analysis technology was used to calculate the temperature of particles in the ignition picture. The results show that cellulose and hemicellulose change from hetero-homogeneous ignition to homogeneous ignition and lignin changes from homogeneous ignition to heterogeneous ignition with the increase of O_2 concentration. The ignition mechanisms of cellulose,hemicellulose,and lignin change at 30%,70%,and 50% oxygen concentration,respectively. The ignition of cellulose is sensitive to the change of O_2 concentration. When the _2 concentration exceeds 30%,the cellulose char ignites firstly. The heating rates of hemicellulose and lignin increase with the increase of O_2 concentration. For hemicellulose,it can be attributed to that the burning proportion of hemicellulose volatiles decreases and the burning proportion of hemicellulose char increases with the increase of O_2 concentration during the combustion process. For lignin,it is because the combustion of lignin char is enhanced with the increase of oxygen volume fraction. Moreover,the combustion time of hemicellulose and lignin decreases with the increase of O_2 concentration,both of which are due to the enhancement of their char combustion with the increase of oxygen content. Furthermore,the lignin char will melt and expand under higher oxygen concentration,forming an obvious expanding flame.

关键词(KeyWords): 纤维素;半纤维素;木质素;氧气体积分数;着火行为
cellulose;hemicellulose;lignin;O_2 concentration;ignition behaviors

Abstract:

Keywords:

基金项目(Foundation): 国家自然科学基金资助项目(51776081)

作者(Author): 程偲哲;邹春;姚青;娄春;王树森;经慧祥;梅媚;
CHENG Sizhe;ZOU Chun;YAO Qing;LOU Chun;WANG Shusen;JING Huixiang;MEI Mei;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;Key Laboratory of Healthy &Intelligent Kitchen System Integration of Zhejiang Province;Ningbo Fotile Kitchen Ware Company;

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DOI: 10.13226/j.issn.1006-6772.CCUS20091402

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