基于动网格的采空区自燃“三带”时空演化规律研究

Research on Temporal and Spatial Evolution Law of Spontaneous Combustion"Three Zones"'in Goaf Based on Dynamic Mesh

针对回采过程中采空区自燃“三带”动态变化的难题,以马道头矿8105工作面为例,采用FLUENT动网格模型的动态层法建立动态采空区模型,分析推进过程中采空区氧气体积分数分布规律及自燃“三带”动态演化过程,探讨了埋管注氮、托管注氮的防灭火效果。结果表明:采空区自燃“三带”分布随推进距离的增加阶段性变化,回采初期自燃“三带”不断延伸,中后期“三带”分布趋于稳定;推进过程中埋管注氮管口逐渐偏离设计位置导致防灭火效果降低,托管注氮管口始终处于最佳设计位置可有效降低自然发火危险性。确定推进状态下自燃“三带”分布对采空区遗煤自燃预防工作具有指导意义。

Aiming at the problem of dynamic change of spontaneous combustion"three zones"in goaf during the advancing process,taking 8105 working face of Madaotou mine as engineering background,dynamic layer method of FLUENT dynamic mesh model is used to create dynamic model.The distribution law of oxygen concentration in goaf during advancing process and evolution process of spontaneous combustion"three zones",furthermore fire prevention effect of nitrogen injection by buried pipes and managed nitrogen injection are discussed.The results show that distribution of spontaneous combustion"three zones"in goaf changes with increasing advancing distance,the scope of spontaneous combustion"three zones"in early stages of propulsion continue to extend,in middle and later phases of propulsion tends to be stable.During advancement process,the position of nitrogen injection port of buried pipe gradually deviates from design position,which decreases fire prevention effect.Managed nitrogen injection always is best design position,thus can effectively reduce risk of spontaneous combustion.Determining the"three zones"distribution range of spontaneous combustion in the propulsion state has reference significance for the prevention of spontaneous combustion of coal leftover in goaf.