基于热棒防灭火技术的煤自燃区域热迁移特征

Thermal migration characteristics of coal fire area based on fire prevention technology with heat pipe

为进一步掌握煤自燃蓄热区域的热迁移特征,系统论述煤自燃热棒防灭火技术原理、治理流程和工艺方法,基于自行设计的煤堆-热棒实验测试平台,分析煤堆-热棒-空气系统热阻网络,研究热棒作用下煤堆内部热量迁移行为及效果评估参数。研究结果表明:热棒的强化散热特性能够持续加快煤堆内部热量散失,煤堆-热棒-空气系统的总热阻是4.1937℃/W,热棒工作167 h的散热量为3.30 MJ,煤堆温度最大降幅达到33.2℃,降温率为39.6%。实验条件下热棒对煤堆的有效降温半径为0.37 m,煤堆内各测点温度均被控制在自燃临界温度范围以内,煤堆因自燃引起的温度升高过程受到显著抑制,煤堆氧化升温速率被削弱。随着离热棒边缘距离增大,热棒对煤堆内部温度场的分布影响逐渐减小。工业试验现场地面以下0.40 m和1.70 m这2根热棒安装部位处的温度均在75℃以下,煤自燃受到明显抑制。热棒对于煤自燃高温区域的降温优势明显,对于煤自燃防治工程来说,根据煤自燃灾害"防-控-灭"分区综合治理思想合理设计热棒防灭火技术方案,防止复燃,能够最大限度地提高煤自燃治理工程的有效性和经济性。

For further understanding of the heat transfer behavior of using heat pipe(HP)cooling down the high temperature zone at coal pile caused by self-heating,the principle and treatment method of HP for coal spontaneous combustion prevention were elaborated.Based on the self-designed experiment device,the thermal resistance network of coal-HP-air system was analyzed.The heat transfer behavior and cooling effect of the coal pile were evaluated with HP.The results show that the HP can continuously accelerate the heat loss inside the coal pile.The total thermal resistance of the coal-HP-air system is 4.1937℃/W and the total amount of heat dissipated through HP is 3.30 MJ after 167 h.The maximum temperature drop at the measuring point in the coal pile is about33.2℃ with the cooling rate up to 39.6%.Under experimental conditions,the effective cooling radius of HP is0.37 m at tested coal pile.The temperature of each measuring point at the coal pile is controlled within the critical temperature for spontaneous combustion.The coal temperature rise caused by spontaneous combustion is significantly inhibited,and the rate of the coal oxidation is weakened.In conclusion,HP has obvious advantages and effects on the cooling of high-temperature areas for coal.With the increase of the distance from the edge of the HP,the influence on the distribution of the temperature field inside the coal pile is gradually reduced.Under a typical coal pile wildfire field,the temperatures of the coal pile at 0.40 m and 1.70 m below the ground are controlled below 75℃ using two HPs at the installation site,and the process of spontaneous coal combustion is inhibited.HP has obvious effects on cooling the high-temperature of coal fire zones.For the coal fire control engineering,the technical proposal with HP can be designed based on comprehensive treatment idea"prevention-control-extinguishment".The HP technology can maximize the effectiveness and economy of coal spontaneous combustion control engineering.