煤火高温低氧反应的阶段演化模型及关键基团转化机理

The coal fire status in various stages and the after-combustion characteristic is the vital point of development mechanism and scientific controlling coal fire. Aiming at the reaction characteristic of high temperature and low oxygen concentration in the coalfield fires, this project investigates the real-time evolution of the thermodynamic characteristic temperatures and parameters, the functional groups and the characteristic structural parameters during high-temperature combustion of coal under different low oxygen concentrations, ensuring the critical controlling groups for the thermodynamic staged characteristics, basing on which a staged development model of coalfield fires with the integration of both macro and micro levels should be constructed. Besides, the detail reaction pathways which includes the products, reactive intermediates and the critical controlling groups during the structural transformation process of high-temperature coal combustion in different low oxygen concentrations should be researched, which would elucidate the kinetic mechanism of group chain reaction of coal combustion under high temperature and oxygen-depleted condition. Furthermore, the influential effect of oxygen concentration on the staged development model and the critical controlling groups should be investigated to revealing the differential mechanism in the chain reaction pathways. Finally, the staged evolution mechanism of coal combustion in the high temperature and oxygen-depleted coalfield fires should be constructed with the indicator of thermal dynamic characteristics, micro group characteristics and the critical controlling groups and the essential factor of the influential mechanism of oxygen concentration during the development of coalfield fires. These achievements would provide theoretical support for characterizing the coal combustion states in various stages and the after-combustion characteristic, which is meaningful for controlling coal fire and mining safety.

煤火的阶段燃烧状态及复燃特性是煤火高温发展机理与科学治理的关键。本项目针对煤田火区低阶煤高温低氧反应的特点，研究不同氧浓度下煤高温低氧反应的热动力特征温度及参数，基团及结构参数实时变化规律，热动力阶段特征的关键控制基团，建立宏观及微观一体化的火区阶段发展模型；研究不同氧浓度下煤高温反应结构变迁中产物、活性中间体和关键控制基团的详细反应路径及热力学参数，阐明不同氧浓度下火区煤高温反应阶段发展的基团链式反应动力学机理；研究氧浓度对火区阶段发展模型、关键控制基团链循环反应路径的影响规律，揭示氧浓度影响阶段发展的链循环反应差异性机理。最终建立以热动力特性、微观基团特征和关键控制基团链反应机理为指标，以火区阶段发展氧浓度影响机制为因素的煤火高温低氧反应的阶段演化机理。为表征变氧浓度下火区各阶段煤燃烧状态及复燃特性提供理论支撑，对推动煤田火区高效治理和井下煤炭资源安全高效开采具有重要科学意义。

我国煤田火灾十分严重。煤火烧毁大量煤炭资源的同时严重危害着生态环境和地下水资源，煤火的阶段燃烧状态及复燃特性是煤火高温发展机理与科学治理的关键。本项目研究了煤火高温低氧反应的阶段演化模型及关键基团转化机理，提出了煤贫氧燃烧阶段发展的9个结构转化燃烧进程，确定了氧浓度降低煤燃烧过程演变的6类阶段发展类型，揭示了煤贫氧燃烧阶段性发展的过程特性；揭示了氧浓度降低对火区燃烧的着火机制改变、着火能力、燃烧稳定性、最大燃烧强度和表观活化能动力学转变的影响规律，提出了火区煤样贫氧燃烧发展的极限氧浓度区间为1%-3%。. 提出了煤高温反应红外三维实时谱图温度影响、光强波动和初始光强差异的红外三维基线校正方法，阐明了煤热解及贫氧燃烧中基团的实时变化规律及其对氧浓度降低的演化特征，揭示了煤中醚桥键等弱化学键断裂是煤中挥发份初析温度的关键控制基团，脂肪族烃快速降低的起始温度和醚氧键的持续分解影响着煤快速氧化着火的发生，醚氧、脂肪族烃和芳香族烃向含氧羧基、醛基和酮羰基的转化，含氧基团的消耗决定了煤贫氧燃烧的综合燃烧性能；探明了煤阶和氧化时间影响贫氧限制作用的高灵敏性及基团转化机制。. 提出了煤复杂大分子结构模型的构建及评价方法；基于煤热解和不同氧含量燃烧过程的ReaxFF反应力场，提出了以骨架链接桥键断裂，小分子中间体与裂解结构片段交互的煤结构热解过程的反应机理模型；阐明了煤不同氧浓度燃烧改变氧攻击煤结构活性部位和活性桥键自分解比例改变的基团转化动力学机制；揭示了火区低阶煤热解残余及复燃特性，提出了火区低阶煤最短自然发火期预测模型及复合高吸水性树脂阻化剂防治方法。研究成果对推动煤田火区高效治理及防复燃具有重要科学意义。