不同程度预氧化煤传热特性

Transfer characteristics of coal under different preoxidation degree

选用气煤,预先在程序升温装置中分别氧化升温至80,120,150和200℃,原煤作为对照组,探究煤复燃的热量传递规律。采用激光导热仪FLA457分别测量空气气氛中原煤与预氧化煤在30~300℃内的热物性参数,对热物性参数进行拟合分析,并探究其对温度的敏感性。结果表明:在30~300℃内,随着温度的升高,煤样热扩散系数先减小后增大,比热容逐渐增大并趋于平稳,导热系数逐渐增大。煤样的热扩散系数变化率以及导热系数变化率呈现出先减小后增大的趋势,比热容变化率逐渐减小。在相同温度下,随着预氧化温度的增加,热扩散系数先增大后减小,导热系数逐渐减小,并且原煤的比热容和导热系数均大于预氧化煤的比热容和导热系数。此外,比热容对温度的敏感性最大。实验结果对于煤火灾害防治具有一定的指导意义。

The gas coal was adopted to oxidize at 80,120,150 and 200℃in a temperature-programmed oxidation apparatus,with raw coal acting as the control group,to explore the heat transfer law of coal after-combustion.Laser pyrometer apparatus FLA457 was employed to examine the thermophysical parameters of raw coal and preoxidation coal under air atmosphere within the range of 30~300℃.The thermophysical parameters were fitted and the sensitivity of thermophysical parameters on temperature were analyzed.The results indicated that when the temperature increased within the range of 30~300℃,thermal diffusivity firstly decreased and then increased,specific heat capacity gradually increased and then tended to be steady,and thermal conductivity gradually increased.With the elevating temperature,the change rate of thermal diffusivity and thermal conductivity showed an increasing trend following a decrease,and the change rate of specific heat capacity gradually decreased.At fixed temperature,with the increase of peroxidation temperature,thermal diffusivity firstly increased and then decreased,thermal conductivity declined,and specific heat capacity of raw coal was bigger than that of preoxidation coals.Furthermore,the sensitivity of specific heat capacity on temperature was the biggest.Those results provide a certain theoretical basis and guiding significance for the prevention of coal fire disaster.