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为研究煤的变质程度对煤矿火灾时期煤燃烧放热特性的影响,选取6种不同变质程度煤样作为试验样品,采用STA-449C型同步热分析仪进行热重(TG)试验。研究煤样的质量变化、放热量变化规律。通过对TG曲线进行一阶微分得到煤样失重速率(DTG)曲线。利用Freeman-Carrol模型计算各煤样的燃烧反应动力学参数。结果表明:失重率和最大失重速率随着煤样变质程度升高逐渐降低,DTG曲线近似符合Gauss分布;初始放热温度T_(f_0)随着煤样水分含量升高而升高;煤样变质程度升高,特征温度点T_1,T_3,T_(s_1)与T_4呈线性增加,T_(f_0)与T_(s_0)呈线性下降趋势变化;放热量随煤变质程度升高呈指数关系变化,相同温度时,煤样变质程度越高放热量越小;煤化程度越高,综合燃烧特性指数S越大,放热量越大,失水活化能、着火活化能与燃烧活化能均升高。
In order to study the effect of coal metamorphism on the combustion and exothermic characteristics of coal during coal mine fires, six kinds of coal samples with different metamorphic grades were selected as test samples and the TG test was carried out by STA-449C synchronous thermal analyzer. Study of the quality of coal samples, the evolution of heat release. The DTG curve of the coal sample was obtained by first derivative of the TG curve. The Freeman-Carrol model was used to calculate the combustion kinetic parameters of each coal sample. The results show that the weight loss rate and the maximum weight loss rate decrease with the increasing degree of coal sample deterioration, and the DTG curve approximates to the Gauss distribution. The initial exothermic temperature T_ (f_0) increases with the increase of coal sample moisture content. T_ (s_0) and T_ (s_0) showed a linear decreasing trend; the exothermic amount changed exponentially with the increase of coal metamorphism, and the same The higher the degree of coal metamorphism is, the smaller the heat release is; the higher the degree of coalification, the larger the overall combustion index S, the larger the heat release, the loss of water activation energy, the ignition activation energy and the combustion activation energy.