沥青在贫氧气氛下的热解动力学实验研究

Experimental study on the pyrolysis characteristics and kinetics of asphalt under poor oxygen concentrations

隧道内沥青热解燃烧通常在贫氧环境下进行。为研究沥青在真实火灾情况下,环境氧体积分数对其热解过程和动力学的影响,利用热重分析仪,对10#铺地基质沥青,在氧体积分数分别为0、7%、15%和21%的氧氮混合气氛下进行热解实验,研究沥青的热解过程,并进行动力学分析。结果表明:沥青在氧体积分数为0(纯N2)的气氛下热解过程只有一个主失重阶段,最终剩余量高;在有氧气氛下热解过程均呈现出3个失重阶段,最终剩余量低于10%;随着氧体积分数的增加,沥青的起始分解温度升高、热解速度增加、高温段失重加剧,低温段活化能小幅降低,反应过程均属于扩散模型;高温段活化能在氧体积分数为21%时最高,反应模型由贫氧时的扩散模型转变为三级简单模型。

Most of the pyrolysis and combustion of asphalt is under the oxygen-poor environment during tunnel fire.In order to study the effects of ambient oxygen concentration on asphalt under real fire,the pyrolysis kinetic characteristics of 10#asphalt under different oxygen volume concentrations(0,7%,15%,21%)were investigated by thermogravimetric(TG)analysis.The pyrolysis process of asphalt under different oxygen concentration was studied,and the kinetic analysis was performed.Results showed that there is only one main weight-loss stage in the pyrolysis process of asphalt in the atmosphere of 0%(N2)oxygen concentration,and the ratio of residual mass is the highest.Presence of oxygen in the atmosphere change the weight-loss stagefrom one to three,and the ratio of residual mass is less than 10%.With the increase of oxygen concentration,the initial decomposition temperature of asphalt and the pyrolysis speed increases,the weight-loss rate in the high-temperature section accelerates,while the activation energy in the low-temperature section decreases.The reaction process basically consistent with the diffusion model.The activation energy in high-temperature section is the highest at 21%oxygen concentration,and the reaction model changes from the diffusion model when the oxygen is poor to the three-stage simple model.