特厚高放顶煤开采注氮煤自燃危险抑制特性研究

Study on suppression characteristics of coal spontaneous combustion risk by nitrogen injection in extra-thick and high top coal caving

针对特厚高放顶煤回采工作面采空区遗煤量大、漏风严重等问题,通过程序升温氧化实验和热释放测试实验,对未注氮与注氮条件下的煤体氧化自燃过程气体产物、氧气消耗和热释放特性进行分析;利用数值模拟软件,对不同注氮位置条件下注氮对采空区煤自燃危险区域的抑制性进行分析;并进行注氮方案优化。结果表明:注氮时能抑制煤体氧化自燃反应进程,各气体产物出现的温度点延缓25~30℃,耗氧速率、放热量大幅度降低,未注氮时的放热量是注氮时放热量的5.67倍;不同位置注氮时采空区煤自燃危险区域差异收缩,注氮口2、3、4、5即进风一侧分别距工作面60、80、100、120 m位置注氮时危险区域抑制面积依次占比为12.28%、32.71%、39.71%、44.09%,采空区温度抑制变化主要集中在注氮口附近区域;注氮口2、3联合注氮优化方案能有效抑制47.25%的采空区煤自燃危险区域。

Aiming at the problems of large amount of residual coal and serious air leakage in the goaf of extra-thick and high top coal caving mining face,the gas products,oxygen consumption and heat release characteristics of coal oxidation spontaneous combustion process under the conditions of without nitrogen injection and nitrogen injection were analyzed by temperature programmed oxidation experiment and heat release test experiment.By using numerical simulation software,the inhibition of nitrogen injection on the risk zone of coal spontaneous combustion in goaf under different nitrogen injection positions was analyzed and the nitrogen injection plan are optimized.The results show that the process of oxidation and spontaneous combustion of coal can be inhibited by nitrogen injection.The temperature point of each gas product is delayed by 25-30℃,and the oxygen consumption rate and heat release are greatly reduced.The heat release without nitrogen injection is 5.67 times that of nitrogen injection.When nitrogen is injected at different positions,the risk area of coal spontaneous combustion in goaf is different and contracted.When nitrogen is injected at ports 2,3,4 and 5,that is,the intake side is 60 m,80 m,100 m,120 m away from the working face when nitrogen is injected,the inhibition area of risk area accounts for 12.28%,32.71%,39.71% and 44.09% respectively.The change of temperature inhibition in goaf is mainly concentrated in the zone near the nitrogen injection port.Nitrogen injection ports 2 and 3 joint optimized plan can effectively inhibit 47.25% of the risk area of coal spontaneous combustion in goaf.