注氮条件下采空区氧气浓度分布的数值模拟研究

发布时间：2018-06-16 19:22

本文选题：注氮 + 气体浓度　；参考：《安徽理工大学》2013年硕士论文

【摘要】：本文利用数值模拟方法对不同通风方式下及不同注氮条件下的采空区氧浓度场展开了研究。根据流体力学和多孔介质的基本理论,建立了工作面与采空区统一流场的数学模型,运用计算流体力学的方法,对采空区流场及注氮条件下的氧气浓度分布规律进行了模拟,通过模拟优化了注氮参数。在现场实测及理论分析的基础上,分析了采空区孔隙率分布和气体渗流阻力,采用试算法确定了采空区冒落煤岩的渗透率、孔隙率和粘性阻力等参数。根据氧浓度场划分了采空区自燃“三带”,研究了不同注氮方式下U型、U+L型和Y型通风方式下的采空区自燃“三带”范围的变化特征,结果表明： (1)U型通风方式下,随着注氮量的增加,采空区自燃带范围逐渐缩小,自燃带的位置越靠近工作面。注氮量180.12m3/h时,为抑制遗煤自燃的最低值；注氮口位置距工作面10-30m时,采空区自燃带范围较小,在25m～35m之间,反算得到的安全回采速度低于正常推进速度(2m/d)；注氮口位置距工作面10m时,自燃带范围最小,为25m。 (2)U+L型通风方式时,随着注氮口位置变化,采空区自燃带范围也不一样,注氮口位置距工作面30m时,自燃带范围最小为31m,安全回采速度1.9m/d；随着注氮量的增加,采空区进风侧自燃带宽度收缩明显,而回风侧自燃带宽度变化不大,注氮口位置距工作面30m时的最佳注氮量为180.12m3/h。 (3)Y型通风方式时,未注氮条件下的采空区自燃带宽度达到82m,反算得到的安全回采速度约为3.6m/d。注氮量295.92m3/h时,对于防止Y型通风采空区自燃效果明显；采空区的合理注氮口位置为20-30m,自燃带范围较小为29-32m,而注氮口位置20m时,自燃带范围最小为29m。
[Abstract]:In this paper, the field of oxygen concentration in goaf under different ventilation modes and different nitrogen injection conditions is studied by numerical simulation method. According to the basic theory of fluid mechanics and porous media, the mathematical model of the unified flow field in the face and goaf is established, and the distribution of oxygen concentration in the goaf under the condition of nitrogen injection is simulated by the method of computational fluid dynamics. The parameters of nitrogen injection were optimized by simulation. On the basis of field measurement and theoretical analysis, the porosity distribution and gas seepage resistance in goaf are analyzed, and the permeability, porosity and viscosity resistance of caving coal rock in goaf are determined by trial calculation. According to the oxygen concentration field, the "three zones" of spontaneous combustion in goaf are divided, and the variation characteristics of "three zones" of spontaneous combustion in goaf under different nitrogen injection modes under U type U L type and Y type ventilation mode are studied. The results show that with the increase of nitrogen injection, the range of spontaneous combustion zone in goaf is gradually reduced, and the position of spontaneous combustion zone is closer to the working face. When nitrogen injection amount is 180.12m3/h, it is the lowest value to restrain the spontaneous combustion of residual coal, and when the position of nitrogen injection port is 10-30 m from the working face, the range of spontaneous combustion zone in goaf is relatively small, and the safe recovery speed between 25m~35m and 25m~35m is lower than that of normal advance speed of 2 m / d ~ (-1). When the position of nitrogen injection port is 10 m from the working face, the range of spontaneous combustion zone is the smallest, which is 25m 路2U L type ventilation mode. With the change of the position of nitrogen injection port, the range of spontaneous combustion zone in goaf is different, and when the position of nitrogen injection port is 30 m from the working face, With the increase of nitrogen injection, the width of the spontaneous combustion zone on the inlet side of the goaf shrinks obviously, but the width of the spontaneous combustion zone on the return side does not change much. The optimum nitrogen injection rate is 180.12m3 / h when the position of nitrogen injection port is 30m away from the working face. The width of spontaneous combustion zone of goaf under the condition of no nitrogen injection is up to 82m, and the safe recovery speed is about 3.6m/ d. When nitrogen injection amount is 295.92m3/h, the effect of preventing spontaneous combustion in Y-type ventilated goaf is obvious, the reasonable position of nitrogen injection port in goaf is 20-30m, the range of spontaneous combustion zone is 29-32m, and the minimum range of spontaneous combustion zone is 29m when nitrogen injection port is 20m.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TD752.2

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