煤自燃发火潜伏期不同温度下耗氧特性的研究

Study on oxygen consumption characteristics of coal under different temperatures in latent period of spontaneous combustion

为了探究地层温度的升高对采空区自燃倾向性的影响,对处于自燃潜伏期的煤展开耗氧特性和CO释放特性的研究。通过对长平矿3#煤分别进行20~60℃的封闭耗氧实验,得到了自燃潜伏期不同温度下煤的氧浓度以及CO浓度随时间变化的曲线。对氧浓度变化曲线和CO浓度变化曲线进行拟合分析得到了不同温度下煤的氧气消耗和CO生成速度,同时得到了氧浓度衰减系数和CO浓度增长系数。封闭耗氧实验结果表明:从20~60℃氧气消耗速度逐渐增大并且氧浓度衰减系数呈指数增长,CO浓度增长系数也逐渐增大并且同样呈指数增长,煤的窒熄带氧浓度临界值从20~60℃逐渐由16.8%降低到12.4%。为探究不同温度下采空区煤的自燃发火危险性,将封闭耗氧实验结果的参数应用到采空区CFD数值模拟仿真中,模拟得到随着温度升高采空区窒熄带临界氧浓度位置由200 m增长到380 m。结果表明:常温下不易自燃的煤在较高的环境温度下表现出了较强的氧气消耗和CO释放能力,并且采空区自然氧化带随着温度的升高动态变宽,增大了采空区的自燃发火危险性。

In order to investigate the effect of the increasing stratigraphic temperature on the spontaneous combustion tendency of goaf,the oxygen consumption characteristics and the CO release characteristics of coal in the latent period of spontaneous combustion were studied.The curves of oxygen concentration and CO concentration changing with time for coal under different temperatures in the latent period of spontaneous combustion were obtained through the closed oxygen consumption experiments from 20℃ to 60℃ on 3# coal in Changping Mine,and the fitting analysis was carried out on these curves to obtain the oxygen consumption rate and CO generation rate of coal under different temperatures,meanwhile,the attenuation coefficient of oxygen concentration and the growth coefficient of CO concentration were obtained.The experimental results showed that the oxygen consumption rate increased gradually and the attenuation coefficient of oxygen concentration presented an exponential increase from 20℃ to 60℃,as well as the growth coefficient of CO concentration.The critical value of oxygen concentration for the smothering quenched zone of coal decreased gradually from 16.8% to 12.4% with the temperature from 20℃ to 60℃.To investigate the spontaneous combustion risk of coal in goaf under different temperatures,the parameters from the results of closed oxygen consumption experiments were applied in the CFD numerical simulation of goaf,it showed that the position of critical oxygen concentration for the smothering quenched zone of goaf increased from 200 m to 380 m with the increasing temperature.The results showed that coal which is difficult to occur spontaneous combustion at room temperature also exhibited the stronger oxygen consumption and CO release capacity at higher ambient temperature,and the natural oxidation zone of goaf widened dynamically with the increase of temperature,which increased the spontaneous combustion risk of goaf.