O2/CO2气氛下生物质三组分的燃烧特性

摘要

O2/CO2 combustion characteristics of cellulose and hemicellulose and lignin were studied using thermogravimetric analyzer.The influence of the combustion atmosphere (O2/CO2 , O2/N2 ),oxygen volume fraction (10%,21% and 40%)and heating rate (10 ℃/min,20 ℃/min and 30 ℃/min)on O2/CO2 combustion characteristics were investigated.The results show that the three-biomass components combustion process appeare varying degrees of delay in O2/CO2 atmosphere compared that in O2/N2 atmosphere and it mainly reflects in the coke combustion stage.The lignin combustion delay is more obvious than that of cellulose and hemicellulose,due to the higher lignin coke content.In O2/CO2 atmosphere,the increase of oxygen volume fraction has less influence on volatile matter combustion,due to the high oxygen content of the three bio-mass components.However,there is a remarkable impact on coke combustion with the increase of oxygen volume fraction,and the coke combustion stage moves to the low temperature zone, the comprehensive combustion characteristics improve significantly.In O2/CO2 atmosphere,the combustion process of three biomass components move towards higher temperature zone with the heating rate increasing.There are significantly increasing of weight loss rate of cellulose and hemicellulose in the stage of volatile separating out;in the stage of coke combustion,the weight loss rate of lignin increase significantly.The comprehensive combustion characteristics of three biomass components improve.Compared with cellulose and hemicellulose,lignin combustion reactivity and combined combustion characteristics are relatively poor.%采用热重分析法对生物质三组分(纤维素、半纤维素和木质素)进行O2/CO2燃烧特性实验,分析了不同气氛(O2/N2和O2/CO2)、氧体积分数(10%,21%和40%)和升温速率(10℃/min,20℃/min和30℃/min)对三组分O2/CO2燃烧特性的影响.结果表明:与O2/N2气氛相比,在O2/CO2气氛下三组分燃烧过程存在不同程度的延迟,主要体现在焦炭燃烧阶段;由于木质素焦炭质量分数较高,因此其燃烧延迟相较于纤维素和半纤维素更加明显.O2/CO2气氛下,由于三组分氧含量较高,氧体积分数增大对三组分挥发分燃烧阶段影响较小;而氧体积分数增大对焦炭燃烧阶段产生了明显的影响,使其向低温区移动,综合燃烧特性明显改善.O2/CO2气氛下,升温速率增大,三组分燃烧过程整体向高温区移动;在挥发分析出燃烧阶段,纤维素与半纤维素的失重速率显著增加,在焦炭燃烧阶段,木质素失重速率显著增加;三组分综合燃烧特性得到改善.相比于纤维素与半纤维素,木质素综合燃烧特性指数较低,综合燃烧特性相对较差.