神府低阶煤热解脱挥发分行为预测及热解机理研究  

Study on devolatilization prediction and pyrolysis mechanism of Shenfu low-rank coal pyrolysis

作　　者：雷甲玺 江国栋 魏利平[1,2] 李冬 LEI Jiaxi;JIANG Guodong;WEI Liping;LI Dong(College of Chemical Engineering,Northwest University,710069 Xi’an,China;Research Center of Chemical Engineering Applying Technology for Resource of Shaanxi,710069 Xi’an,China;Institute of Modern Physics,Chinese Academy of Sciences,733100 Lanzhou,China)

机构地区：[1]西北大学化工学院,西安710069 [2]陕西省资源化工应用工程技术研究中心,西安710069 [3]中国科学院近代物理研究所,兰州733100

出　　处：《煤炭转化》2023年第3期1-12,共12页Coal Conversion

基　　金：国家自然科学基金项目(21978237);陕西省自然科学基础研究计划项目(2021JLM-19);陕西省重点研发计划项目(2023-YBGY-317)。

摘　　要：煤热解反应过程发生复杂的物理和化学变化,仅凭实验方法难以深入理解其热解反应机理和产物释放规律。以陕北神府矿区不同煤层的三种低阶煤为原料,结合元素分析、13C-NMR波谱分析和吡啶抽提实验,使用FLASHCHAIN竞争协调模型模拟预测不同煤种快速热解的脱挥发分规律,并与升温速率50 K/min,终温1200 K的热解实验进行对比,验证该模型在不同热解条件、对不同煤种的适用性,研究了热解过程中的反应机理和不同结构的变化规律。结果表明:FLASHCHAIN竞争协调模型可以较好地模拟分析低阶煤的快速热解机理。不稳定桥键作为反应的核心,通过其断裂和自发冷凝控制热解产物的释放,并且温度在950 K时不稳定桥键反应速率最大;各碎片在不稳定桥键的作用下控制焦油的逸出,碎片末端的外围基团自发脱除产生非冷凝气体,主要集中在732 K~1050 K进行,而且不受碎片类型的影响;焦油分子的分布受聚合度和温度的影响,轻质焦油分子优先逸出,温度升高导致重质焦油分子的积累。The coal pyrolysis process involves complex physical and chemical changes,and it is difficult to deeply understand the pyrolysis mechanism and the product release law through experimental methods alone.This study analyzed the characteristics of three types of low-rank coal from different seams in the Shenfu mining region of northern Shaanxi province,integrating ultimate analysis,13C-NMR nuclear magnetic resonance spectroscopy analysis,and pyridine extraction experiments.In order to explore the devolatilization patterns of various coal types under rapid pyrolysis,the FLASHCHAIN bridge competitive and coordination model was applied in this work,compared with pyrolysis experiments carried out at a heating rate of 50 K/min and a final temperature of 1200 K.The applicability of this model for different pyrolysis settings and coal types were verified,and the reaction mechanism and coal structural changes during pyrolysis process were studied.The results show that the FLASHCHAIN model can effectively simulate and analyze the rapid pyrolysis mechanism of low-rank coal.As the nucleus of the reaction,the unstable bridge regulate the release of pyrolysis products through its fracture and spontaneous condensation,and the reaction rate of the unstable bridge is the highest at 950 K.Each fragment controls the tar escape under the action of unstable bridge bonds,and peripheral groups at the end of each fragment spontaneously removes to produce non-condensed gases,which mainly occur at 732 K to 1050 K and are not affected by the type of fragments.The distribution of tar molecules is affected by the degree of polymerization and temperature,with light tar molecules escaping preferentially,and the increase of temperature leads to the accumulation of heavy tar molecules.

关 键 词：热解 核磁共振 脱挥发分 预测 FLASHCHAIN模型 

分 类 号：TQ530.2[化学工程—煤化学工程]