低瓦斯自燃采空区注氮工艺优化研究

Study on process optimization of nitrogen injection in low gas spontaneous combustion goaf

为了分析注氮口埋深和注氮流量对采空区氧化带范围的影响,优化低瓦斯自燃煤层采空区注氮防灭火工艺,采用数值模拟和现场实测相结合的方法,分别模拟了未注氮,注氮流量为设计量且注氮口埋深为15 m、30 m、45 m、60 m和75 m,注氮口埋深为45 m且注氮流量为0.50倍、0.75倍、1.00倍、1.25倍、1.50倍和1.75倍设计量时采空区氧化带范围;现场实测了注氮口埋深为45 m且注氮流量为设计量时采空区氧化带范围。研究结果表明:随着注氮口埋深增加氧化带面积逐渐减小,注氮口埋深分别为15 m、30 m、45 m、60 m和75 m时,氧化带面积为未注氮时的100.8%、96.1%、90.5%、95.0%和79.1%;随着注氮流量增加,氧化带面积逐渐减小,注氮流量为0.50倍、0.75倍、1.00倍、1.25倍、1.50倍和1.75倍设计量时,氧化带面积为未注氮时的95.8%、93.4%、90.5%、87.1%、83.3%和79.2%;增加50%的注氮流量,氧化带面积减小7.9%,减少50%的注氮流量,氧化带面积增加5.9%。现场实测结果与数值模拟结果基本一致。对于9202工作面,合理的注氮口埋深为30~60 m,最佳注氮口埋深为45 m,注氮流量为设计量的1.00~1.50倍比较合适,最优注氮流量为设计量的1.25倍。

In order to analyse the impact of nitrogen injection port depth and flow rate on the range of the oxidation zone in the goaf,and to optimize the nitrogen injection fire prevention process in low gas spontaneous combustion goafs,a method combining numerical simulation with on-site measurement is adopted.Simulations are conducted for various scenarios:without nitrogen injection,with nitrogen injection at the designed flow rate and nitrogen injection port depths of 15 m,30 m,45 m,60 m,and 75 m;with nitrogen injection port at a depth of 45 m and nitrogen injection flow rates of 0.50,0.75,1.00,1.25,1.50,and 1.75 times the designed nitrogen injection flow rate.On-site measurements are taken with nitrogen injection port at a depth of 45 m and the designed flow rate.The results show that as the nitrogen injection port depth increases,the area of the oxidation zone gradually decreases.With nitrogen injection port depths of 15 m,30 m,45 m,60 m,and 75 m,the area of the oxidation zone is 100.8%,96.1%,90.5%,95.0%,and 79.1%of the area without nitrogen injection,respectively.As the nitrogen injection flow rate increases,the area of the oxidation zone also decreases,with flow rates at 0.50,0.75,1.00,1.25,1.50,and 1.75 times the designed flow rate,the area of the oxidation zone is 95.8%,93.4%,90.5%,87.1%,83.3%,and 79.2%of the area without nitrogen injection,respectively.An increase of 50%in nitrogen injection flow rate reduces the area of the oxidation zone by 7.9%,while a reduction of 50%increases it by 5.9%.The on-site measurement results are generally consistent with the numerical simulation results.For the 9202 working face,a reasonable nitrogen injection port depth is between 30 m and 60 m,with the optimal depth being 45 m,and a suitable nitrogen injection flow rate is between 1.00 and 1.50 times the designed flow rate,with the optimal flow rate being 1.25 times the designed flow rate.