范各庄矿烟煤大分子结构模型构建及其梯度升温热解模拟  

Macromolecular Structure Model of Bituminous Coal of Fangezhuang Mine and Gradient Heating Pyrolysis Simulation

作　　者：战星羽 李伍[2] ZHAN Xingyu;LI Wu(School of Resources and Geoscience,China University of Mining and Technology,221116 Xuzhou,China;Key Laboratory of Coalbed Methane Resource and Reservoir Formation Process Ministry of Education,China University of Mining and Technology,221116 Xuzhou,China)

机构地区：[1]中国矿业大学资源与地球科学学院,江苏徐州221116 [2]中国矿业大学煤层气资源与成藏过程教育部重点实验室,江苏徐州221116

出　　处：《煤炭转化》2022年第5期42-52,共11页Coal Conversion

基　　金：国家自然科学基金面上项目(41972169).

摘　　要：以范各庄矿烟煤为研究对象,采用^(13)C-NMR,FTIR和元素分析等进行化学表征,利用计算机辅助功能,建立了有机分子结构模型。利用Material Studio程序将得到的模型进行退火计算,使模型处于能量最低状态,更接近于室温状态下煤本身的性质。利用ReaxFF MD方法将范各庄矿烟煤分子模型进行梯度升温热解模拟计算,区别于程序升温,梯度升温保证在特定温度点的反应更加充分,比程序升温能够更好地还原实际热解过程。基于模拟结果分析了在热解过程中的不同温度的产物分布,以及焦炭、焦油、气态烃的动态变化过程。结果表明:随着温度升高,反应速率逐渐加快,焦炭产率逐渐下降,焦油产率出现先增大后减小的趋势,气态烃产物逐渐升高,其中的典型气体变化也根据温度的不同呈现出不同的产出形式;在梯度升温热解过程中C_(5)~C_(13)轻焦油与C_(14)~C_(40)重焦油的变化过程均有先升高后减少的变化趋势,但重焦油在二次裂解后,逐渐趋于稳定状态,而轻焦油在较高的温度状态下有小幅度增加的趋势;对模型进行了不同升温速率的升温热解,结果表明升温速率的提高可以加快焦炭的裂解速度,但由于较慢的升温速率可以有更多的反应时间,增加了小分子类物质的碰撞概率,提高了气态烃的产量,而随着升温速率的增加,焦油的二次裂解现象也愈发不明显,这也说明了焦油的二次裂解现象需要在较高的温度环境下并且需要更多的反应时间。The chemical characterization of bituminous coal from Fangezhuang was investigated by ^(13)C-NMR,FTIR and ultimate analysis,and organic molecular structure model was established by computer aided method.The obtained model was annealed by using Material Studio,so that the model was in the lowest energy state,which was closer to the intrinsic properties of coal at room temperature.Gradient heating pyrolysis of the bituminous coal molecular model was simulated by using ReaxFF MD.Different from temperature programmed reduction,the gradient heating ensures that the reaction at a specific temperature is sufficient,and it can better reveal the actual pyrolysis process than temperature programmed reduction.According to the simulation results,the product distribution at different temperatures in the pyrolysis process,as well as the dynamic changes of char,tar,and gas are analyzed.With the increase of temperature,the reaction rate is gradually accelerated,the yield of coke gradually decreases,the yield of tar firstly increases,and the gaseous hydrocarbon product gradually increases.The typical gas compositions also exhibit different output forms depending on the temperature.The changing process of C_(5)-C_(13) light tar and C_(14)-C_(40) heavy tar in the process of gradient heating pyrolysis was analyzed.Both of them have a trend of increasing first and then decreasing,but the heavy tar gradually tends to a stable state after the secondary cracking,while the light tar has a small increasing trend at a higher temperature.In addition,by performing heating pyrolysis with different heating rates on the model,the results show that the increase of heating rate can speed up the cracking rate of char.However,the slower heating rate can increase the reaction time,which improves the collision probability of small molecular species,and increases the production of gaseous hydrocarbons.The secondary reaction of tar is not significant at rapid heating conditions,which shows that the secondary reaction of tar requires a higher temperatur

关 键 词：范各庄矿烟煤 分子模型 分子模拟 梯度升温热解 升温速率 

分 类 号：TQ530.2[化学工程—煤化学工程]