不同氧气条件下煤自燃参数特征研究

Research on parameters characteristics of coal spontaneous combustion under different oxygen conditions

煤自燃是影响煤相关产业发展的重要灾害之一。为了详细了解煤自燃过程的各参数特征,采用实验与数值模拟结合的方式研究了煤低温氧化的多物理参数耦合特性,通过实验验证数值模型的可靠性,探究了不同氧气条件下的煤自燃演变规律。结果表明:建立的数值模型可以很好地表征煤自燃的多参数耦合特征,氧气体积分数随煤温的增加减小,CO和CO_(2)体积分数随煤温增加而增加;煤氧化反应的气体消耗与产生特征呈现滞后特性;不同氧气条件下的煤氧化反应产生的CO和CO_(2)随氧气体积分数的增加而增加,8 h内的变化量与氧气体积分数呈线性关系,氧气在煤体内部的分布呈现“分层”特征;以2 h为临界时间,煤样的最小温度与平均温度呈现不同的增加趋势,随氧气体积分数的降低,煤体内低温区域向气体入口区域扩张。

Coal spontaneous combustion is one of the important disasters affecting the development of coal-related industries. To understand the characteristics of various parameters of coal spontaneous combustion process in detail, a combination of experiment and numerical simulation was used to study the coupling characteristics of multiple physical parameters of coal low-temperature oxidation, the reliability of the numerical model is verified by the experiment. The evolution law of coal spontaneous combustion under different oxygen conditions is further explored, the results show that the established numerical model can well characterize the multi-parameter coupling characteristics of coal spontaneous combustion. The oxygen volume fraction decreases with the increase of coal temperature, and the CO and COvolume fractions increase with the increase of coal temperature. The gas consumption and production characteristics of coal oxidation reaction show hysteresis characteristics. The CO and COproduced by the coal oxidation reaction under different oxygen conditions increase with the increase of the oxygen volume fraction, and the change within 8 h has a linear relationship with the oxygen volume fraction. The distribution of oxygen inside the coal body presents a “stratified” feature. Taking 2 h as the critical time, the minimum temperature and the average temperature of the coal sample show different increasing trends. As the oxygen volume fraction decreases, the low temperature area in the coal body expands to the gas inlet area.