淮南煤氧化动力学过程及其微观结构演化特征研究

发布时间：2018-05-17 23:10

  本文选题：活性官能团 + 动力学特征　； 参考：《西安科技大学》2017年博士论文

【摘要】：研究煤氧化过程的微观机理是控制和预防煤自然发火的重要方法。本文通过理论分析、实验研究和统计计算三种手段相结合的方法,对淮南矿区6个煤矿的典型煤样在氧化自燃过程的微观特征和宏观特性,以及两者之间的关联性进行了详细的分析,研究了在高温氧化过程中,煤分子中官能团变化规律及氧化气体产物的动力学特性,为淮南煤自燃灾害的早期预测预报提供了指导,并对在自燃过程中采取科学的防治措施提供了重要的理论依据。采用元素分析、工业分析、比表面积及孔径分布分析、导热特性、XRD微晶结构参数分析、红外光谱分析等测试技术,分析了淮南煤的物理化学结构特性,掌握了煤样的煤质组成以及内部结构特征。结果表明淮南煤质的特点为低灰分、较高挥发分;比表面积较小,孔径以中孔为主,常温状态下较难发生氧化;煤样的热扩散系数随着温度的升高不断减小,比热容和导热系数随着温度的升高不断增大;微晶结构中芳香环缩合程度中等,层片结构较为有序,煤中主要含有高岭石、地开石、方解石、石英和菱铁矿等矿物成分;煤样表面分子结构中官能团种类相似但数量不同,均能检测到羟基、脂肪烃、芳香烃、含氧官能团。通过原位漫反射傅里叶红外光谱分析了煤氧化过程中微观结构特征及其变化规律,对四类官能团中的21种基团随温度变化的特性进行分析发现,羟基在升温反应过程中不断减少,脂肪烃先增大后减小,芳香烃中Ar-CH基团比较稳定,呈现先增大后减小的现象,而C=C基团一直缓慢减少,含氧官能团在燃点温度之前不断增大,直至燃点温度之后含量才有所减少。通过西安科技大学自主研发的高温程序升温实验系统,测试了在升温至500℃过程中的淮南煤氧化释放的气体产物变化规律,并根据指标气体增长率分析法测算出五个特征温度点,将整个氧化升温过程分为四个阶段,分别是临界温度阶段、干裂-活性-增速温度阶段、增速-燃点温度阶段和燃烧阶段。实验证明,在临界温度阶段,CO和CO2气体缓慢增长,超过该温度阶段直至增速-燃点温度阶段,碳氧类气体含量迅速增长,燃烧温度阶段气体浓度有所下降,继而由于稳定官能团的断裂,继续上涨。CH4、C2H6和C2H4气体在干裂-活性-增速温度阶段之前均增长缓慢,之后才开始急剧增长,到燃烧温度阶段达到峰值。利用高温程序升温实验数据,采用两种不同的动力学方法,对四个不同阶段的动力学特性进行计算研究,反应所需活化能随温度阶段的递进先降低后增大,燃烧阶段所需活化能大于增速-燃点温度阶段。此外,通过差示扫描法对氧化过程中的放热性进行了计算。通过分析微观特性与宏观表征,选取灰色关联性分析中的相对关联度分析,对淮南煤氧化升温的四个温度阶段中氧化释放的气体和放热量与14种不同活性基团之间的关联度大小进行统计分析,推断出影响各个阶段气体和热量释放的主要官能团,分析发现,前三阶段中,羰基是影响宏观气体释放和热量产生的主要官能团,脂肪烃和芳环结构是燃烧阶段中产生气体和热量的主要官能团,且C=C结构在燃烧阶段才开始大量参与反应,释放气体产物。
[Abstract]:The microscopic mechanism of coal oxidation process is an important method to control and prevent coal spontaneous combustion. Through theoretical analysis, experimental research and statistical calculation, the micro and macro characteristics of the typical coal samples in the 6 coal mines in Huainan mining area and the correlation between them are carried out in this paper. The three methods are combined with the method of theoretical analysis, experimental research and statistical calculation. In the process of high temperature oxidation, the change law of the official energy group and the kinetic characteristics of the oxidation gas product are studied in the process of high temperature oxidation. It provides guidance for the early prediction and prediction of the Huainan coal spontaneous combustion disaster, and provides the important theoretical basis for the scientific prevention and control measures in the process of spontaneous combustion. Analysis of surface area and pore size distribution, thermal conductivity, XRD microcrystalline structure parameter analysis, infrared spectrum analysis and other testing techniques, analyzed the physical and chemical structure characteristics of Huainan coal, mastered the coal composition and internal structure characteristics of coal samples. The results show that the characteristics of coal quality in Huainan are low ash, high volatile, smaller specific surface area, and pore size. The thermal diffusion coefficient of coal samples decreases with the increase of temperature, and the ratio of heat capacity and thermal conductivity increases with the increase of temperature. The condensation degree of aromatic rings in the microcrystalline structure is moderate and the structure of the layer is more orderly. The main coal in the coal is kaolinite, calcite, calcite, quartz and rhombus. Minerals such as mineral components; the surface molecular structure of coal samples is similar but the number is different, all can detect hydroxyl, fatty hydrocarbon, aromatic hydrocarbon, oxygen containing functional group. Through in situ diffuse reflectance Fourier transform infrared spectroscopy, the microstructure characteristics and change rules of coal oxidation process are analyzed, and 21 groups in the four category functional groups vary with temperature. The analysis of the characteristics shows that the hydroxyl group decreases continuously during the heating reaction process, and the fatty hydrocarbons increase first and then decrease. The Ar-CH group in aromatic hydrocarbons is more stable, showing the phenomenon of first increasing and then decreasing, while the C=C group has been slowly decreasing, and the oxygen containing functional groups continuously increase before the ignition temperature, and the content decreases after the ignition temperature. After the high temperature programmed temperature experiment system developed by Xi'an University of Science And Technology, the change law of gas products released from Huainan coal oxidation in the process of heating up to 500 C was tested, and five characteristic temperature points were calculated according to the index gas growth rate analysis method. The whole oxidation heating process was divided into four stages, which were the critical temperature stage, respectively. It is proved that at the critical temperature stage, CO and CO2 gas increase slowly at the critical temperature stage, and the content of carbon and oxygen gas increases rapidly at the stage of the temperature and the temperature stage, and the gas concentration in the combustion temperature stage decreases, and then the stable functional group breaks down. Crack, continue to rise.CH4, C2H6 and C2H4 gas increase slowly before the dry cracking activity growth temperature stage, and then begin to increase rapidly and reach the peak in the combustion temperature stage. By using the high temperature temperature programmed experimental data, two different kinetic methods are used to calculate and study the dynamic characteristics of the four different stages. The activation energy is first reduced and then increased with the progressive of the temperature stage. The activation energy needed in the combustion stage is greater than that of the ignition point temperature. In addition, the heat release of the oxidation process is calculated by differential scanning. The relative degree analysis in the grey correlation analysis is selected by analyzing the microscopic and macroscopic characterization, and the coal oxygen in Huainan is selected. The correlation degree between the oxidizing gas and the release of heat and the 14 different active groups in the four temperature stages is statistically analyzed, and the main functional groups that affect the release of gas and heat at various stages are deduced. The analysis shows that the carbonyl groups are the main functional groups that affect the release of macro gases and the production of heat in the first three stages. The fatty hydrocarbon and aromatic ring structure are the main functional groups that produce gas and heat during the combustion stage, and the C=C structure begins to take part in the reaction and release the gas products at the combustion stage.
【学位授予单位】：西安科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD752.2
，

本文编号：1903283