1. College of Mining Engineering,Liaoning Technical University,Fuxin　 123000,China; 2. Institute of Engineering and Environment,Liaoning Technical University,Huludao　 125000,China; 3. Faculty of Engineering,Kyushu University,Fukuoka　 819-0385,Japan

为研究堆积褐煤自燃特性,通过开放式恒温实验获得不同体积立方体褐煤(边长分别为0.05,0.1,0.15和0.25 m)内部升温曲线、临界自燃着火点温度(Tc)和表观活化能等特征参数。基于等效氧化暴露时间(EOET)理论,针对实验条件建立均质多孔介质的多场耦合数学模型,并通过实验结果验证了数值模拟的合理性,从而掌握了实验无法获得的温度场、氧浓度场和渗流场的动态分布。通过实验将褐煤升温过程划分为4个阶段。结合实验及数值模拟明确了煤体热量产生与传递、水分蒸发与运移、氧气消耗与运移、自然对流等多种因素的耦合关系,探讨了升温过程中相对EOET与产热加速率的负相关关系。进而对大型煤堆自燃状态进行模拟,验证了煤堆临界自燃着火点温度实验式的合理性。

Spontaneous combustion of stockpiled coal can occur under some appropriate circumstances. The open-en- ded isothermal method was used to investigate the characteristic parameters of lignite,such as the critical self-ignition temperature (Tc ) and apparent activation energy of the cube lignite sample of different size (0. 05,0. 1,0. 15 and 0． 25 m in side length). Multi-fields coupling mathematical model of homogeneous porous media was developed based on the theory of equivalent oxidation exposure time ( EOET) and applied to simulate the self-combustion process of lignite. Thereby the dynamic distribution of temperature,oxygen concentration and seepage field were analyzed system- atically. Heating process of lignite sample in the experiment can be divided into four stages,which are rapid heating stage,slow heating stage,temperature rebounding stage and self-heating stage respectively. Coupling mechanism of heat generation transfer,water evaporation and migration,oxygen consumption and migration and natural convection of coal sample was investigated through combined experiment and simulation. Relationship between relative EOET and heat generation acceleration rate was demonstrated to be a negative correlation. Critical self-ignition temperatures of large- scale coal stockpiles for numerical simulation were in close agreement with the prediction values of empirical function.

ZHANG Hemeng,ZHANG Xiaoming,WANG Yongjun,et al. Study on spontaneous combustion of lignite based on the theory of equivalent oxidation exposure time[J]. Journal of China Coal Society,2018,43(5):1358-1364.