干燥煤堆自燃升温特征的数值模拟

The numerical simulation of sponeteanous combustion heating up regulaiton in dry coal plie

为了了解露天煤堆自燃升温过程中温度变化特征,在考虑风压、热压和质量扩散等驱动力的情况下建立了二维干燥煤堆传热传质数学模型,利用FLUENT软件对煤堆内部漏风、氧气与温度各类场信息进行分析.结果表明,煤堆自燃环境的特点是迎风面漏风强度和氧气浓度最高,背风面最低,中间递减,高温区位于迎风坡附近漏风强度适中,氧气充足的蓄热区.风速与孔隙度对煤堆自燃升温速率影响最显著,迎风倾角其次,环境温度对升温速率的影响很小.模拟结果与煤堆升温实验数据在趋势上比较符合,现场可根据计算结果事先大致判定火源位置,缩小侦测范围,以便及时采取措施,提高防火工作效率.

In order to understand the temperature dynamic feature of open coal pile,the 2D Heat and mass transfer mathematical model of coal pile was established under the condition of driving force of air pressure,thermal pressure and mass diffusion. Then the fluent software was used to analyze the seveal field informations such as airleakage,oxygen concentration and temperature. The results show that the high temperature region always lies in windward slope where has appropriate air velocity and sufficient oxygen supply. And it＇s all because the coal pile has the environment characteristic which is that windward slope has the highest air velocity and oxygen supply,which decreases along as distance from windward slope,and leeward slope is the opposite. Air velocity and porosity impact the heating up rate mostly then windward slope angle,and environment temperature has least effect for this. Favourable comparisons between numerical and experimental results justify the suitability of the numerical approach. Hence the fire source position can be decided roughly by numerical results to narrow the detection range,consequently,the efficience of fire protection will improve for timely measurement.