高温区域不断移动是造成煤自燃发展的主要原因，因此，研究高温区域的蔓延特征对揭示煤自燃形成演化机理和判定发展趋势有重要的科学意义。本文分析煤自燃过程中高温区域的温度分布和气体变化规律，研究高温区域蔓延行为，为煤自燃高温区域的反演识别提供理论依据。

首先，采用煤质分析、热重和扫描电镜实验对煤样进行了物理化学特性分析。然后，采用自主研发的煤自燃发展演化模拟实验系统对煤自燃升温-降温全过程中不同测点的温度变化进行了监测，确定了高温区域及其蔓延路径。研究表明实验过程中，上部煤样温度变化受环境蓄热和传热的影响，下部煤样温度变化受孔隙和火风压作用影响，导致煤样的高温区域移动呈非线性特征，主要沿炉体中部及东南侧方向蔓延。随深度加深，达到燃点温度时间呈线性变化，达到峰值温度时间则呈现多项式变化。

其次，研究高温区域关键点的氧气浓度、耗氧速率以及CO、C₂H₄等典型煤自燃气体产物的变化规律，掌握了高温区域的气体变化规律。发现升温阶段氧气浓度呈减小趋势，降温阶段氧气浓度呈增大趋势，耗氧速率与氧气浓度变化呈现负相关。升温阶段在30~300℃时CO浓度缓慢增大至30000ppm，C₂H₄气体浓度缓慢增加至400ppm；300~600℃时CO浓度迅速增大至60000ppm，C₂H₄气体浓度迅速增加至1000ppm 600~800℃时CO和C₂H₄浓度达到峰值。降温阶段在400℃时CO浓度降低至5000ppm，在300~200℃时出现复燃现象，使得煤发生二次氧化，导致气体浓度出现波动；C₂H₄气体浓度在600~300℃的过程中快速减小至150ppm，200℃之后则缓慢减少至实验结束。随着深度加深，CO气体浓度逐渐增大，C₂H₄气体浓度逐渐降低。

最后，采用灰色关联度分析方法，研究高温区域蔓延过程中的官能团的迁移规律以及官能团对高温区域气体释放的影响规律，揭示高温区域蔓延的内在原因。随着温度的升高，羟基含量逐渐增大，脂肪烃含量逐渐减少，芳烃C=C含量逐渐降低，烷基醚、芳香醚、多种取代烃等活性官能团含量先增大后降低。得出在燃点温度时官能团的活性和对气体释放的影响达到最大。高温区域向下蔓延过程中，各层煤样的特征温度发生滞后效应，达到特征温度的时间不同，因此，造成影响指标气体产生的活性官能团种类具有多样性。在燃点温度之前，随着深度加深，作用于CO和C₂H₄气体产生的官能团主要有分子内O-H、-CH₃的伸缩振动、Ar-CH面外弯曲振动和酯类C=O；燃点温度之后游离-OH、-CH₂的伸缩振动、芳环C=C和醚类对CO气体释放的影响作用大，-CH₃的伸缩振动、芳环C=C和Ar-CO对C₂H₄气体释放影响作用较大。

The continuous movement of the high temperature area is the main cause of the development of coal spontaneous combustion (CSC). Therefore, the spreading characteristics of high temperature area is of scientific significance to reveal the evolution mechanism of CSC and determine the development trend. This paper analyzes the temperature distribution and gas variation law in the process of CSC. The spread behavior of high temperature area can provide theoretical basis for the inversion identification of high temperature area. First, the physicochemical characteristics of the coal samples were analyzed by coal quality analysis, thermogravimetric experiment (TG), Differential scanning calorimetry experiment (DSC) and scanning electron microscope (SEM) experiments. Then, the CSC development and evolution simulation experimental system is used to monitor the temperature change of different measurement points in the whole process of coal spontaneous combustion heating-cooling. The high temperature region and its spreading path are determined. The study shows that the temperature change of the upper coal sample is affected by environmental heat storage and heat transfer, and the lower coal sample temperature change is affected by pore and fire air pressure. As a result, the high temperature area movement of the coal sample is non-linear, mainly spreading along the middle and southeast direction of the furnace body. With the depth deepening, the time of the ignition temperature changes linearly, and the time of the peak temperature changes in a polynomial manner. Secondly, the oxygen concentration and oxygen consumption rate of the key points of the high temperature area and the change rules of the typical CSC gas products in the high temperature area are studied. Master the law of gas change in the high temperature area. It was found that the oxygen concentration decreased in the heating stage, and increased in the cooling stage, and the oxygen consumption rate was negatively correlated with the change of oxygen concentration. In the heating stage, the CO concentration of 30~300℃ slowly increased to 30,000 ppm, and the C₂H₄ gas concentration slowly increased to 400 ppm; The CO concentration at 300 to 600℃ was increased rapidly to 60000 ppm, and the C₂H₄ gas concentration was rapidly increased to 1000 ppm; The CO and C₂H₄ concentrations peaked at 600 ~ 800℃. During the cooling stage, the CO concentration was decreased to 5000 ppm at 400℃. At 300~200℃, the coal occurs secondary oxidation, resulting in the fluctuation of gas concentration. The C₂H₄ gas concentration was rapidly reduced to 150 ppm between 600 to 300℃, and slowly reduced after 200℃ until the end of the experiment. As the depth deepens, the CO gas concentration gradually increases, and the C₂H₄ gas concentration gradually decreases.

Finally, the grey correlation degree analysis method is used to study the migration rules of functional groups during the spreading in high temperature regions and the influence rules of functional groups on the gas release in high temperature regions. Explain the internal causes of high temperature area spread. With the increase of temperature, the hydroxyl content gradually increases, the content of aliphatic hydrocarbon is gradually reduced, the content of aromatics C=C gradually decreases, and the content of active functional groups such as alkyl ether, aromatic ether, and various substituted hydrocarbons increases first and then decreases. The activity of the functional group and the influence on the gas release are maximized at the ignition temperature. In the process of downward spread of high temperature area, the characteristic temperature of each layer has lag effect, and the time to reach the characteristic temperature is different, therefore, the types of active functional groups affecting the index gas are diverse. Before the ignition point temperature, with the depth, the functional groups produced by CO and C₂H₄ gas mainly include the intramolecular hydrogen bond、methyl shear vibration、various substitution of aromatic hydrocarbons and acetal groups of esters. After the ignition temperature, free hydroxyl group、methylene shear vibration、aromatic ring C=C expansion vibration and ethers influence on CO gas release. Methyl expansion vibration、aromatic ring C=C expansion vibration and aromatic oxide have great effects on C₂H₄ gas release.

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