工作面反风时采空区场量分布变动的数值模拟

Numerical simulation of the change process of field variables distribution in goaf caused by air reversing in working faces

  • 摘要: 结合华兴煤矿1318炮放面实例,运用数值模拟手段,描绘了工作面反风时采空区流场内漏风流,氧、CO和瓦斯各组分气体,以及温度等的分布变动过程,给出了反风时沿工作面边界各组分气体涌出量的变化规律.模拟在反风后,场内各组分气体含量分布重心发生倒置,原上游高温区被冷却,下游低温区逐渐转变为新的高温区,使采空区的温度上升过程重新回到一个相对较低的温度起点,使自燃升温得到一定的延缓.反风后,场内CO气体涌出量经历突降—回跳上升—缓慢衰减—再逐渐增加的跳动过程,瓦斯涌出量在经历大幅度突降和回跳后,其增幅度不大.用埋管抽放的办法能够防止因反风导致工作面内有害气体超限,同时给出了反风的实施条件,即必须确保采空区无明火.

     

    Abstract: Based on No.1318 shooting case in Huaxing Coal Mine,the changing process of air leakage flow,components (oxygen,CO and methane),and temperature in the flow field of goaf during air reversing were solved and described,and the changing rule of gas emission volume of different components along the boundaries of the working face while air reversing was given.It is simulated that after air reversing the content distribution centers of different components are reversed,the upper high temperature area is cooled down while the lower area with low temperature becomes a new high temperature area,making the temperature rising process in goaf at a low start point,which is favorable for slowing down the rising velocity of temperature and thus preventing spontaneous combustion of coal from taking place.During air reversing,the emission volume of CO has a jumping process of sudden decrease→increase→slow attenuation→gradual increase.After this process,the increase range of gas emission volume becomes slowed.By burying pipes to extract gas,harmful gases within the working face could be prevented from exceeding limit during air reversing.At the same time,the condition to realize air reversing is given,namely there is no naked flame in goaf.

     

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