烟杆废物热解动力学研究

doi:10.3969/j.issn.1673-5854.2017.05.007

摘要/Abstract

摘要： 通过热重分析（TGA）方法，采用单步和三平行反应模型分别考察烟杆废物的热解动力学。烟杆废物单步热解的平均活化能为182.4 kJ/mol，最适宜的反应机理函数为14级反应机理f（α）=（1-α）¹⁴。能量补偿效应结果显示烟杆废物的热解可以分为3个阶段α=0~0.32、α=0.32~0.80和α=0.80~1，各阶段的指前因子分别为2.88×10¹⁰、4.33×10¹⁴和9.76×10¹⁶s^-1。单步热解过程中伴有表观活化能的变化以及高级数反应的机理，不能合理地描述烟杆废物的热解机理。采用混合韦伯分布活化能模型考察了三平行反应热解动力学，结果显示：混合韦伯分布活化能模型能很好地拟合烟杆废物热解数据，相关系数R²≥0.997 6；3种伪组分的活化能大小符合E₀（木质素，195.26 kJ/mol）> E₀（纤维素，152.54 kJ/mol）> E₀（半纤维素，121.18 kJ/mol）的顺序；半纤维素的热解机理为一级反应f（α）=1-α，纤维素的热解机理属于成核机理，木质素的机理亦呈现级数反应，级数介于n=3~4之间，木质素的热解机理复杂，可能为多步反应。

关键词: 烟杆废物, 热重分析, 热解动力学, 韦伯分布

Abstract: The pyrolysis kinetic of tobacco stem waste(TSW) was investigated by using single reaction model and three-parallel-reaction (TPR) model via thermogravimetric analysis(TGA). In single reaction model, the reaction mechanism of TSW pyrolysis presented as 14th order reaction f(α)=(1-α)¹⁴, with the apparent activation energy of 182.4 kJ/mol. According to the energy compensation effect results, the pyrolysis process of TSW could be divided into three stages which successively covered the conversion range of α=0-0.32, α=0.32-0.80, α=0.80-1 with the pre-exponential factor of 2.88×10¹⁰, 4.33×10¹⁴ and 9.76×10¹⁶, respectively. The single reaction model could not describe the pyrolytic mechanism of TSW reasonably. And then, the pyrolytic kinetic of TSW was investigated by using mixture Weibull distributed activation energy model(DAEM). Results showed that the mix-Weibull DAEM fitted the experimental data very well with correlation coefficients of R²≥0.997 6. According to the results of mix-Weibull DAEM, the apparent activation energy of three pseudo components followed the order of E₀(lignin, 195.26 kJ/mol)>E₀ (cellulose, 152.54 kJ/mol)> E₀(hemicelluloses, 121.18 kJ/mol). The pyrolytic mechanism for pseudo hemicelluloses was first-order reaction f(α)=1-α. And nucleation mechanism could be used to explain the pseudo cellulose pyrolysis. Order-based reaction mechanism was also suitable for pseudo lignin pyrolysis, however, the reaction order was between 3-4, which indicated that the pyrolytic mechanism of pseudo lignin was complex and might be a multiple steps reaction.

Key words: tobacco stem waste, thermogravimetric analysis, pyrolysis kinetics, Weibull distribution

中图分类号:

TQ35

务文涛, 李志华, 赵贝贝. 烟杆废物热解动力学研究[J]. 生物质化学工程, 2017, 51(5): 41-48.

WU Wentao, LI Zhihua, ZHAO Beibei. Kinetic Study of Tobacco Stem Waste Pyrolysis[J]. bce, 2017, 51(5): 41-48.

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