低温氧化下低阶煤表面活性结构行为变化对其自燃规律影响研究

Coal spontaneous combustion is the major threat to the safety of coal mines and coal transport. There are still many problems to be solved because of the complexity and diversity of coal, especially the process and characteristics of low-rank coal spontaneous combustion. The problems of low-rank coal spontaneous combustion, in particular, abundant lignite and quality improved lignite will be studied in this project. The coal surface structure characteristic will be observed by using scanning electronic microscope (SEM) and mercury intrusion method. The oxygen adsorption and diffusion process of coal will be carried out to get the mechanism model of oxygen diffusion. The TG-FTIR technology will be employed to imitate coal oxidation in air, in which weightlessness and heat release, characteristic temperature and activation energy kinetic parameters will be also determined. The different stage of oxidation will be analyzed and the information of coal surface activated structures will be acquired from FTIR spectra of released gas in oxidation process. According to experimental equipment of coal oxidation at low-temperature, the technology of FTIR and the method of chemical titration will be used to find the change in molecular structure before and after coal oxidized in different temperature, in which the quantitative variation law of coal surface structure will be also obtained. Based on the analysis of heat release and oxygen adsorption, the effect of surface structures of low-rank coal on the law of coal spontaneous combustion will be discussed, which is important to understand the mechanism of coal spontaneous combustion and prevent coal spontaneous combustion.

煤炭自燃是威胁煤矿和煤运安全的重大灾害之一，由于煤自身的复杂性和多样性，自燃机理和低温氧化过程仍有很多问题急需解决，尤其是易自燃的低阶煤的自燃过程、特性研究。本项目针对低阶煤，特别是我国大量存在的褐煤及提质后褐煤自燃的问题，拟通过扫描电镜和孔结构分析仪观察煤表面结构特征，通过煤氧吸附扩散实验获得氧气扩散机理模型；采用热重-红外技术模拟煤在空气中的氧化，分析煤氧化不同阶段及通过释放气体红外谱图获得煤表面活性结构的信息，测定煤在氧化过程中失重及放热，分析特征温度点，计算活化能及动力学参数等；通过煤低温氧化实验装置借助红外光谱分析技术及化学滴定法，测定煤在不同温度下氧化前后分子结构变化情况，获得煤的表面活性结构在氧化中的定量变化规律，依据煤在不同反应阶段吸氧及放热情况，探讨低价煤表面活性结构对煤自燃的影响规律，对认识煤自燃机理，运用自燃规律预测和防治低阶煤自燃具有重要的理论意义。

本项目针对低阶煤，特别是我国大量存在的褐煤及提质后褐煤自燃的问题，从氧扩散机理、煤氧复合反应动力学、褐煤程序升温指标气体与表面活性结构变化四方面开展了相关研究，深入探讨了煤自燃机理。主要的工作包括：.（1）通过煤氧扩散装置研究了氧气在松散煤体内的扩散传质过程及影响因素；（2）通过静态法测定了煤样的耗氧速率；结合差示扫描量热法（DSC）对煤样低温氧化过程放热强度进行计算，建立预测褐煤最短自然发火期的数学模型。（3）采用煤自燃程序升温系统模拟煤样的低温氧化过程，分析煤低温氧化过程不同阶段氧气消耗情况及指标气体的释放规律，计算了活化能及动力学参数等；（4）通过红外光谱实验得到褐煤表面活性结构在低温氧化过程中变化规律，并考察其对低温氧化反应的影响。.本项目选取低煤化程度的煤为研究对象，研究其低温氧化自燃过程，重点探讨煤表面活性结构在自燃过程中的变化及对自燃的影响，这对认识煤自燃机理，运用自燃规律预测和防治低阶煤自燃具有重要的理论意义。