褐煤自燃倾向测定及其低温氧化反应过程研究

褐煤的自燃是一个缓慢的低温氧化过程,搭建煤自燃倾向测定实验台,采用篮热法测定不同煤种的自燃倾向,求得不同煤自燃的动力学参数,并采用热重和傅里叶红外光谱(FTIR)揭示其低温氧化反应机理,分析褐煤自燃倾向的影响因素。实验发现,水分含量的高低会影响自燃发生的时间,但不影响煤种最终的自燃倾向。褐煤的自燃倾向性是与煤的低温氧化反应性直接联系的:褐煤在低温氧化反应过程中,主要发生烷基侧链断裂,然后氧化反应放热,造成热量的积累。煤中烷基侧链基团含量越高,芳香烃含量越低,其氧化反应性越强,更易发生自燃;煤样比表面积决定了对氧的吸附能力,吸附能力越强,其低温氧化反应性越高,越容易发生自燃。

Study on spontaneous combustion propensity and low-temperature oxidation process of lignite

The spontaneous combustion is a slow low-temperature oxidation process.A lab-scale experiment for spontaneous combustion propensity has been established.Basket heating method was used to investigate the oxidation process of four kinds of lignite and the kinetics of spontaneous combustion was determined.Thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR) were combined to study low-temperature oxidation reaction mechanism.It is found that moisture content can postpone the occurrence of spontaneous combustion without the influence of intrinsic propensity.The spontaneous propensity is directly related with low-temperature oxidation reactivity:as temperature increases，the side chain will be oxidized into oxygenated groups，and more side chain and less aromatics is favorable to the propensity；the specific surface area determines oxygen absorption ability.The stronger of oxygen absorption ability，the higher of spontaneous combustion propensity.