低阶煤自燃氧化热分析动力学研究
发布时间：2018-07-28 08:45
【摘要】：煤的自燃氧化是一个复杂的动力学过程,深入分析与掌握煤氧化的动力学规律,对研究煤自然着火有着非常重要的意义。以三种低阶煤为研究对象,两种高阶煤为对比煤样,选用Redfern-Coats积分方程对煤自燃最概然机理函数进行推断,得出了低阶煤在失水脱附阶段属于一级化学反应,吸氧增重阶段属于三维扩散机理函数。经过计算发现,低阶煤的活化能低于高阶煤种,而且随着温度的升高,反应程度加深,活化能增大,指前因子也随之增加。通过对煤样的产热速率进行分析发现,煤的低温氧化都经历了吸热然后再放热的过程,产热速率随温度的升高而增加,低阶煤的初始放热温度较低,而总放热量却高于高阶煤种。利用程序升温氧化系统和傅里叶红外光谱仪,通过对煤氧化过程中的气体产物和官能团的变化情况的分析发现,在氧化过程中最先出现的是CO气体,缓慢氧化阶段CO气体产量较少,曲线平缓。随着温度的升高气体产量逐渐增加,烃类气体也逐渐产生。低阶煤分子结构中的脂肪烃和含氧官能团含量明显大于变质程度高的煤,而且这两种基团活性较高,在氧化过程中变化明显。经研究推断出CO直接来源于醛基,而烃类气体主要是由脂肪链的断裂产生。低阶煤结构复杂,稳定性差,在反应过程中易于分解,生成大量气体,自燃危险性较大。煤的氧化是多步反应,不同步骤之间相互竞争又相互联系,反应速率随温度升高逐渐加快,参与反应的分子数量也随之增加。
[Abstract]:The spontaneous combustion oxidation of coal is a complicated dynamic process. It is very important to analyze and master the kinetic law of coal oxidation. Taking three kinds of low-rank coal as the research object and two kinds of high-order coal as contrast coal samples, the Redfern-Coats integral equation is used to infer the most probable mechanism function of coal spontaneous combustion, and it is concluded that the low-rank coal is a first-order chemical reaction in the desorption stage of water loss. The phase of oxygen absorption and weight gain belongs to three dimensional diffusion mechanism function. The results show that the activation energy of low-rank coal is lower than that of high-order coal, and with the increase of temperature, the degree of reaction deepens, the activation energy increases and the pre-exponential factor increases. Through the analysis of the heat production rate of coal samples, it is found that the low temperature oxidation of coal goes through the process of endothermic and then exothermic, the heat production rate increases with the increase of temperature, and the initial exothermic temperature of low rank coal is lower. However, the total heat release is higher than that of high-order coal. By using the temperature programmed oxidation system and Fourier transform infrared spectrometer, it is found that CO gas is the first one to appear in the oxidation process by analyzing the changes of gas products and functional groups in the process of coal oxidation. At the stage of slow oxidation, CO gas production is less and the curve is smooth. With the increase of temperature, the production of hydrocarbon gas increases gradually. The content of aliphatic hydrocarbons and oxygen-containing functional groups in the molecular structure of low-rank coal is obviously higher than that in high-grade metamorphic coal, and the activity of these two groups is higher, and the changes are obvious during the oxidation process. It is inferred that CO is directly derived from aldehyde group, while hydrocarbon gas is mainly produced by the breakage of fatty chain. The structure of low rank coal is complex, the stability is poor, it is easy to decompose in the reaction process, produce a large amount of gas, and the danger of spontaneous combustion is great. The oxidation of coal is a multi-step reaction. The reaction rate increases with the increase of temperature and the number of molecules participating in the reaction increases.
【学位授予单位】：华北理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD752.2
[Abstract]:The spontaneous combustion oxidation of coal is a complicated dynamic process. It is very important to analyze and master the kinetic law of coal oxidation. Taking three kinds of low-rank coal as the research object and two kinds of high-order coal as contrast coal samples, the Redfern-Coats integral equation is used to infer the most probable mechanism function of coal spontaneous combustion, and it is concluded that the low-rank coal is a first-order chemical reaction in the desorption stage of water loss. The phase of oxygen absorption and weight gain belongs to three dimensional diffusion mechanism function. The results show that the activation energy of low-rank coal is lower than that of high-order coal, and with the increase of temperature, the degree of reaction deepens, the activation energy increases and the pre-exponential factor increases. Through the analysis of the heat production rate of coal samples, it is found that the low temperature oxidation of coal goes through the process of endothermic and then exothermic, the heat production rate increases with the increase of temperature, and the initial exothermic temperature of low rank coal is lower. However, the total heat release is higher than that of high-order coal. By using the temperature programmed oxidation system and Fourier transform infrared spectrometer, it is found that CO gas is the first one to appear in the oxidation process by analyzing the changes of gas products and functional groups in the process of coal oxidation. At the stage of slow oxidation, CO gas production is less and the curve is smooth. With the increase of temperature, the production of hydrocarbon gas increases gradually. The content of aliphatic hydrocarbons and oxygen-containing functional groups in the molecular structure of low-rank coal is obviously higher than that in high-grade metamorphic coal, and the activity of these two groups is higher, and the changes are obvious during the oxidation process. It is inferred that CO is directly derived from aldehyde group, while hydrocarbon gas is mainly produced by the breakage of fatty chain. The structure of low rank coal is complex, the stability is poor, it is easy to decompose in the reaction process, produce a large amount of gas, and the danger of spontaneous combustion is great. The oxidation of coal is a multi-step reaction. The reaction rate increases with the increase of temperature and the number of molecules participating in the reaction increases.
【学位授予单位】：华北理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD752.2
【参考文献】
相关期刊论文 前10条
1 魏琰荣;肖翠微;王乃继;王永英;;补连塔煤低温氧化特性的热重研究[J];洁净煤技术;2016年01期
2 邓军;张丹丹;张，
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