陕北侏罗纪煤低温氧化反应性及动力学研究

发布时间：2018-11-16 15:52

【摘要】：我国陕北地区的侏罗纪煤层变质程度较低,在开采过程中自燃危险性高,不但威胁着煤矿的安全生产,而且造成严重的环境污染和资源浪费。本论文采用理论分析、实验研究和数学计算相结合的方法,针对陕北侏罗纪煤的低温氧化过程,研究其氧化反应性及宏观动力学特性,确定陕北侏罗纪煤氧化自燃过程中的关键活性基团,对其自燃机理以及防治新技术的研究具有重要的理论指导意义。采用工业分析仪、元素分析仪、物理化学吸附仪、X-射线衍射仪、扫描电子显微镜和傅里叶红外光谱仪等,系统研究了陕北侏罗纪煤的煤质、元素组成、微晶结构、比表面积、孔径分布、微观形态及官能团分布特征,从物理化学结构与氧吸附特性角度分析了对陕北侏罗纪煤自燃的影响;利用热重与红外联用实验,研究了陕北侏罗纪煤氧化和热解过程的质量与气体产物变化,得到其低温氧化过程可以分为水分蒸发及气体脱附失重和吸氧增重两个阶段,确定了两个阶段的自燃特征温度及气体产生规律;基于多升温速率的FWO和Kissinger方法,分别计算了陕北侏罗纪煤低温氧化过程两个阶段的动力学参数,得到在水分蒸发及气体脱附失重阶段表观活化能随温度的升高而降低,平均活化能为30~60 kJ/mol,在吸氧增重阶段随温度的升高而增加,平均活化能为80~120kJ/mol,利用Bagchi法分别确定了两个阶段的动力学模式函数;采用差示扫描量热实验,研究了陕北侏罗纪煤氧化与热解过程的热效应变化,得到了低温氧化过程两个阶段的热效应特性,以及吸、放热速率的变化规律;并采用原位漫反射傅里叶红外光谱仪,测试了陕北侏罗纪煤热解和氧化过程的主要官能团变化特征,确定了陕北侏罗纪煤低温氧化过程两个阶段的活性基团及其变化规律。基于Pearson相关系数和灰色关联分析方法计算了陕北侏罗纪煤氧化过程活性基团与表观活化能变化的相关性,得到陕北侏罗纪煤不同活性基团对低温氧化过程两个阶段影响不同。采用Pearson相关系数的正负性和灰色关联度,定量表征了不同活性基团对氧化过程的影响程度,确定了陕北侏罗纪煤样低温氧化过程水分蒸发及气体脱附阶段的关键活性基团为游离羟基、羧基、羰基和C=C结构,吸氧增重阶段的关键活性基团为脂肪烃甲基和亚甲基、C-O醚键等,从关键活性基团反应性角度微观解释了陕北侏罗纪煤氧化动力学及热效应特性。
[Abstract]:The metamorphism of Jurassic coal seams in northern Shaanxi is relatively low, and the spontaneous combustion is dangerous in the mining process, which not only threatens the safe production of coal mines, but also causes serious environmental pollution and waste of resources. In this paper, the oxidation reactivity and macroscopic kinetic characteristics of Jurassic coal at low temperature were studied by the methods of theoretical analysis, experimental study and mathematical calculation. The determination of the key active groups in the process of coal oxidation spontaneous combustion in the Jurassic of northern Shaanxi is of great theoretical significance for the study of the mechanism of spontaneous combustion and the study of new technologies for prevention and control. The coal quality, elemental composition and microcrystalline structure of Jurassic coal in northern Shaanxi were systematically studied by means of industrial analyzer, elemental analyzer, physicochemical adsorption instrument, X-ray diffraction instrument, scanning electron microscope and Fourier transform infrared spectrometer. The effects of specific surface area, pore size distribution, micromorphology and functional group distribution on the spontaneous combustion of Jurassic coal in northern Shaanxi were analyzed from the point of view of physical and chemical structure and oxygen adsorption characteristics. The mass and gas product changes in the process of coal oxidation and pyrolysis in the Jurassic of Northern Shaanxi were studied by thermogravimetric and infrared experiments. The results show that the oxidation process at low temperature can be divided into two stages: water evaporation, gas desorption weight loss and oxygen absorption weight gain. The characteristic temperature of spontaneous combustion and the law of gas production in two stages are determined. Based on the FWO and Kissinger methods with multiple heating rates, the kinetic parameters of the low temperature oxidation process of Jurassic coal in Northern Shaanxi were calculated, respectively. The apparent activation energy decreased with the increase of temperature in the stages of water evaporation and gas desorption. The average activation energy is 30 ~ 60 kJ/mol, and the average activation energy is 80 ~ 120kJ / mol at the stage of oxygen absorption and weight gain. The kinetic model functions of the two stages are determined by Bagchi method. By using differential scanning calorimetry (DSC), the thermal effects of the oxidation and pyrolysis of Jurassic coal in northern Shaanxi were studied. The characteristics of the thermal effects in the two stages of the low temperature oxidation process, as well as the variation of the rate of heat absorption and heat release were obtained. The characteristics of the main functional groups in the pyrolysis and oxidation process of Jurassic coal in northern Shaanxi were measured by in situ diffuse reflectance Fourier transform infrared spectrometer. The active groups in the two stages of the low temperature oxidation process of the Jurassic coal in northern Shaanxi and their changing rules were determined. Based on Pearson correlation coefficient and grey correlation analysis method, the correlation between active groups and apparent activation energy of Jurassic coal oxidation process in northern Shaanxi was calculated. It was concluded that different active groups of Jurassic coal had different effects on the two stages of low temperature oxidation process. The positive and negative correlation coefficient of Pearson and the grey correlation degree were used to quantitatively characterize the influence of different active groups on the oxidation process. The key active groups of water evaporation and gas desorption of Jurassic coal samples in North Shaanxi were determined as free hydroxyl groups, carboxyl groups, carbonyl groups and C C structures, and fatty hydrocarbon methyl and methylene groups as key active groups during oxygen absorption and weight gain. From the point of view of reactivity of key active groups, the oxidation kinetics and thermal effect characteristics of Jurassic coal in Northern Shaanxi were microscopically explained by C-O ether bond.
【学位授予单位】：西安科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TD752.2

【相似文献】