摘要
为深入探讨落叶松热解机理,获得更多高品位的实用燃料。采用热重法对比分析了落叶松在3组不同升温速率(15～55,110～150,210～250℃·min^(-1))下的热解特性,利用Coats-Redfern方法计算了落叶松在低升温速率(15,25,35,45,55℃·min^(-1))下的活化能值,同时采用傅里叶变换红外光谱(FTIR)分析法对落叶松原物料和不同终止温度下的热解剩余物的化学结构进行了对比分析。结果表明:落叶松的热解过程分为干燥、预热解、热解和炭化四个阶段,主热解反应在200～400℃,随着升温速率的提高,最终失重率没有明显变化,最终固体残留物的质量分数在19%～22%,但是最大热解速率随着升温速率的提高从8.95%·min^(-1)增大到144.35%·min^(-1)。落叶松在低升温速率下热解趋势相似,随着升温速率的升高,TG热解出现热滞后现象,DTG主热解区间所需的温度范围扩大;在两组高升温速率下,整个TG曲线排列不再呈现上述规律,DTG曲线在纤维素和半纤维素热解峰区域仍表现出与低升温速率相同的变化规律。Coats-Redfern法计算落叶松低升温速率下的热解活化能值为81.28～95.61kJ·mol^(-1),拟合曲线表现出了良好的线性关系,表明落叶松的热解为一级反应。在不同低升温速率、相同终止温度下落叶松样品FTIR光谱图整体走势基本一致,随着热解反应的进程,主要基团吸收峰的位置变化不大,但在相同的吸收峰处存在明显的强度变化,部分吸收峰的强度逐渐降低甚至消失,说明此时落叶松的组成及组分含量发生了变化,热解基本完成。本研究为生物质热解工艺提供了理论依据和参考数据。
In order to further study the pyrolysis mechanism of larch and obtain more high-grade usable fuel,the pyrolysis experiments of larch were conducted by thermal gravimetric analyzer(TGA)at three sets of heating rates(15-55,110-150,210-250℃·min^-1),the activation energy values of larch at low heating rates(15,25,35,45,55℃·min^-1)were calculated by Coats-Redfern methods,and fourier transform infrared spectrometer(FTIR)was used to analyze larch raw materials and chemical structure of pyrolysis residues at different termination temperatures.The results showed that the pyrolysis process of larch could be divided into four stages:drying,pre-pyrolysis,pyrolysis and carbonization.The main pyrolysis reaction occurred at 200-400℃.With the heating rate increasing,the final weight loss rates did not change significantly,the mass fraction of the final solid residues were 19%-22%,and the maximum pyrolysis rate increased from 8.95%·min^-1 to 144.35%·min^-1.At low heating rates,the pyrolysis trends were similar.With the increased of heating rate,thermal hysteresis occurred.But at the two high heating rates,the pyrolysis curves no longer presented the above rules.Only the peak areas of cellulose and hemicellulose pyrolysis of the DTG curves showed the same change law with that at low heating rates.The pyrolysis activation values obtained at low heating rates by Coats-Redfern were between 81.28-95.61kJ·mol^-1.The fitting curves showed a good linear relationship,which indicated that the pyrolysis of larch was a first order reaction.The infrared spectra of larch samples showed the same trends at different low heating rates and the same final temperatures.The position of the main absorption peaks changed less with the pyrolysis reaction progress.But the intensity changed obviously at the same absorption peak,and the intensity of some absorption peaks decreased or even disappeared gradually,which showed that the composition and component content of larch had changed and the pyrolysis was basically completed.This study provided a theoretical basis and reference data for biomass pyrolysis process.
作者
陈东雨
黄顺朝
王莹
巴浩楠
高冬笑
牛卫生
CHEN Dong-yu;HUANG Shun-chao;WANG Ying;BA Hao-nan;GAO Dong-xiao;NIU Wei-sheng(College of Engineering,Shenyang Agricultural University,Shenyang 110161,China)
出处
《沈阳农业大学学报》
CAS
CSCD
北大核心
2018年第6期709-716,共8页
Journal of Shenyang Agricultural University
基金
辽宁省自然科学基金项目(2015020648
20180550038)
作者简介
第一作者:陈东雨(1976-),女,博士,副教授,从事生物质能工程研究,E-mail:chdyu@163.com.
