不同变质程度煤自燃特性及低温氧化动力学分析

为了研究不同变质程度煤在低温氧化自燃过程中的特性,以及煤样变质程度对煤自燃过程的影响,利用程序升温试验系统研究了不同变质程度煤在低温氧化阶段气体与特征温度变化规律。通过计算其耗氧速率、放热强度,分析了耗氧速率、放热强度与温度之间的对应关系。同时分析了煤样变质程度对CO、CO₂气体及耗氧速率、放热强度的影响规律。根据程序升温的试验条件和阿伦尼乌斯公式建立了CO与温度的计算模型,分析了该方程的线性回归直线斜率,计算了不同变质程度煤低温氧化活化能,分析并印证了煤样变质程度与活化能之间的关系。根据不同煤质工业分析指标试验结果,进一步阐述了各煤种主要煤质工业分析指标的差别,分析了主要指标与煤程序升温试验自燃氧化参数的相关性,同时分析了主要工业分析指标对各特征参数的影响。结果表明:煤在低温氧化自燃过程所产出的CO和CO₂气体释放量、耗氧速率及放热强度均随温度升高而呈指数级增长;随煤样变质程度增加,CO和CO₂气体、耗氧速率、放热强度变化较小;煤的变质程度越高,特征温度和活化能越大;煤样自燃的可能性越小,危险性越小;结合煤样工业分析与活化能发现,水分、灰分、挥发分含量与活化能呈负相关。

Kinetic analysis of the low tempera-ture spontaneous oxidation combustion of the coal seams due to the different metamorphism extents

The present paper is aimed at investigating the characteristic features of the coal seam low-temperature oxidative spontaneous combustion at the different metamorphism degrees and the impact of the degrees of the coal samples on the spontaneous combustion process. And,for such a purpose,we have managed to apply a self-designed temperature-programmed experimental system in the paper,and simultaneously traced the gas and coal characteristic temperature changes at low temperature oxidation with the different degrees of deterioration. And,consequently,we have also analyzed the corresponding relations between the oxygen consumption rate,the exothermic intensity and the related temperature through calculating its oxygen consumption rate and the exothermic intensity. Besides,we have also analyzed the influence of the deterioration degree of the coal samples on the CO,CO₂ gas,the oxygen consumption rate and exothermic intensity. It is just based on the above said experimental conditions of the program warning and the Arrhenius equation that we have established a computational model of CO and temperature through the linear regression linear slope of the equation based on the low-temperature oxidative activation energy of coal with the different degrees of metamorphosis calculated and the relationship between the degree of metamorphosis and activation energy of the coal samples being validated. And,consequently,we have further elaborated the differences between the main coalseam quality indicators for each coal species and their relevance to the specific coal quality industrial analytic indicators,as well as the correlation between the main indicators and the spontaneous combustion oxidation parameters of the coal program warming test. And,furthermore,we have also analyzed the impact of the main industrial analytic indicators on each of the characteristic parameters. Thus,the experimental results we have gained can demonstrate that the gas emission of CO and CO₂,the oxygen consumption rate and the exothermic intensity of the coal in the low-temperature oxidative spontaneous combustion process tend all to increase exponentially with the rise of the temperature.Nevertheless,with the increase of the deterioration degree of the coal sample,less change would take place with the oxygen consumption rate and the exothermic intensity of CO,CO₂ gas,it can be found that,the higher the degree of the metamorphism of the coal,the higher the characteristic temperature and the more energetic the activation energy would be. Hence,correspondingly,the less coal-like spontaneous combustion would be taking place so as to make the activation energy less dangerous. Thus,it can be seen that the combination of the proximate analysis of the coal samples and the activation energy can help to reveal that the moisture,ash and volatile fraction ought to be correlated negatively with the activation energy.