单轴应力对煤自燃特性参数和导热系数的影响研究

摘要

为探究单轴应力作用下煤氧化和传热特性,利用自制荷载加压煤自燃特性参数测定装置对炉体内长焰煤煤样进行程序升温.结合程序升温过程中煤临界温度Tc和Tg,对其进行阶段划分:阶段1为30℃ ~Tc;阶段2为Tc~Tg.计算了不同单轴应力下2个阶段煤表观活化能和平均耗氧速率.根据能量守恒得出程序升温过程煤导热系数随温度的变化,进一步分析煤导热系数与单轴应力的关系.结果表明:阶段1单轴应力为4 MPa时为临界轴压,煤表观活化能最大,平均耗氧速率最小;阶段2煤表观活化能和平均耗氧速率随单轴应力增大均呈抛物线变化,单轴应力为2.7 MPa时为临界轴压,煤表观活化能最大,平均耗氧速率最小;阶段1和2煤导热系数随温度升高均先减小后增大,并且煤导热系数随单轴应力增大呈三次函数变化.%In order to study the characteristics of oxidation and heat transfer of coal under the uniaxial stress,the temperature programmed experiments were carried out on the coal samples of long flame coal by using the self-developed measurement device for the spontaneous combustion characteristic parameters of coal based on the load pressure. Combined with the critical temper-atures Tcand Tgof coal in the temperature programmed process,its stage division was carried out,namely the stage 1 was from 30℃ to Tc,and the stage 2 was from Tcto Tg. The apparent activation energy and the average oxygen consumption rate of coal in two stages under different uniaxial stress were calculated. The variation of thermal conductivity of coal with temperature in the temperature programmed process was obtained according to the energy conservation,then the relationship between the ther-mal conductivity of coal and the uniaxial stress was analyzed. The results showed that in stage 1,the uniaxial stress of 4 MPa was the critical axial compression,and at this point,the apparent activation energy of coal was the largest,the average oxygen consumption rate was the least. While in stage 2,the apparent activation energy and the average oxygen consumption rate of coal presented the parabolic variation with the increase of uniaxial stress,the uniaxial stress of 2.7 MPa was the critical axial com-pression,and at this point,the apparent activation energy of coal was the largest,the average oxygen consumption rate was the least. Both in stage 1 and stage 2,the thermal conductivity of coal decreased first and then increased with the increase of tem-perature,and the thermal conductivity of coal presented the cubic function variation with the increase of uniaxial stress.