不同变质程度煤燃烧特性及动力学参数研究

Research on coal's combustion characteristics and kinetics parameters as a function of its metamorphic degree

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。

For the sake of studying the influence of coal metamorphic grade on the heat release characteristics of coal combustion in coal mine fires,thermogravimetric experiments were carried out on 6 coal samples different from each other in metamorphic degree by using an STA 449 C type synchronous thermal analyzer. DTG curves were obtained by differential calculation of TG curves. Kinetic parameters of combustion reaction were calculated for the 6 coal samples by using Freeman-Carrol model. The results show that the weight loss rate and the maximum weight loss rate decrease gradually with the increase of the metamorphic degree of coal samples,the DTG curves accord with Gauss distribution approximately,that the higher the coal sample moisture content is,the higher the initial exothermal temperature θ（f0） will be,that with the increase of metamorphic degree of coal sample,characteristic temperatures θ1,θ3,θ（s1） and θ4 increase linearly and θ（s0） and θ（f0） decrease linearly that the amount of heat released is an exponential function the degree of coalification,that at the same temperature,there is a negative correlation between the heatquantity and the metamorphic degree,and that there is a positive correlation between the degree of coalification,and the five items,composite combustion characteristic index S,the heat quantity,the filtration activation energy,the ignition activation energy and combustion activation energy.