混煤热解动力学模型适应性分析

Adaptability Analysis of Kinetic Model of Blended Coal Pyrolysis

本文选择内蒙烟煤和宁夏石嘴山无烟煤进行混煤的实验研究.利用热重测定混煤的失重曲线和失重速率曲线数据;采用Coats-Redfern积分法和Achar微分法对不同的反应模型求解所选煤样的热解宏观动力学参数,并确定最佳反应模型.热重曲线的分析表明,在混合煤样中,烟煤的比例大于50%时,少量无烟煤的加入对整个体系影响较大;通过对混合煤样的不同反应模型的线性模拟,选择了线性度较好的1级化学反应、2级扩散反应和2级缩核反应模型进行了低温段和高温段模拟,模拟结果表明,无论是积分法还是微分法,烟煤的活化能均低于无烟煤的活化能;微分法和积分法对多种反应模型模拟得到了一致的动力学反应模型,最终确定2级缩核反应模型为最佳模型.

In this paper,an experimental study on blended coals from Inner Mongolia bituminous coal and Ningxia Shizuishan anthracite was presented.The weight loss curves and weight loss rate curve data of the blended coals were determined by thermogravimetry.The pyrolysis kinetic parameters of the selected coal samples were solved by applying the Coats-Redfern integral method and Achar differential method to different reaction models,and the optimal reaction model was determined.The analysis of thermogravimetric curves shows that in the blended coal samples,when the proportion of bituminous coal was higher than 50%,the addition of a small amount of anthracite will have a great influence on the whole system.Through the linear simulations of different reaction models of blended coal samples,the first-order chemical reaction,second-order diffusion reaction and two-stage nucleation reaction models,which presented better linearity,were selected to simulate the low-and high-temperature sections.Simulation results show that when either the integral or differential method was used,the activation energy of bitu-minous coal was always lower than that of anthracite.A consistent kinetic reaction model was obtained by simulat-ing a variety of reaction models using the differential and integral methods,and the second-order nucleation reac-tion model was determined as the best one at last.