ABSTRACT

The working state of the gas drainage pipe network is the key to the safe drainage of underground mine gas. In order to quickly and accurately determine whether the pipe network is working normally, the flow law of the gas in the pipeline is studied. A diagnosis method of gas extraction pipeline by pressure gradient method is established. A gas drainage pipe network experimental platform is constructed. And the blockage and leakage of single pipe are carried out. The influence of air leakage of main pipe on negative pressure of branch pipe is studied, as well as the influence of negative pressure change of temporary pumping station on parallel pipe is explored. The method of image photography is proposed to calculate the pipeline flow, and the error is 2.7% compared with the orifice flowmeter. The results show that when the abnormalities exist in the extraction pipeline, the slope of the pressure curve corresponding to the abnormalities increases rapidly, the slope of the downstream curve is slightly larger than the slope of the upstream curve when the pipeline is leaking, and the slope of the downstream curve returns to the same as the slope of the upstream curve when the pipeline is blocked. The closer the location of the vacuum pump is to the air leakage, the faster the negative pressure of the vacuum pump decreases, and the less it affects the negative pressure of the branch circuit. When the downhole temporary pumping station extraction system is connected in series with the permanent pumping station extraction system on the ground, the temporary pumping station’s negative pressure value needs to be set reasonably, seriously affecting the extraction effect of the adjacent extraction pipeline. Finally, monitoring the gas drainage pipeline in Yuwu mine by pressure gradient method, it is found that the pressure drop slope at measuring points 6–7 is abnormal (−3 × 10⁴), and the pressure drop slope of measuring points 7–8 returned to normal (−7 × 10⁵), so it is judged that the drainage pipeline is blocked at 1300–1500 m away from the pump station.

摘要

瓦斯抽放管网的工作状态是煤矿井下瓦斯安全排放的关键。为了快速准确地判断管网是否正常工作，对管道内气体的流动规律进行了研究。建立了一种基于压力梯度法的抽气管道诊断方法。搭建瓦斯抽采管网实验平台。并进行单管的堵塞和泄漏。研究了干管漏风对支管负压的影响，探讨了临时泵站负压变化对平行管的影响。提出了图像摄影法计算管道流量，与孔板流量计相比误差为2.7%。结果表明，当抽气管道存在异常时，异常对应的压力曲线斜率迅速增大，管道泄漏时下游曲线的斜率略大于上游曲线的斜率，当管道堵塞时，下游曲线的斜率恢复到与上游曲线的斜率相同。真空泵的位置越靠近漏气处，真空泵的负压下降越快，对支路负压的影响越小。当井下临时泵站抽气系统与地面永久性泵站抽气系统串联时，需要合理设置临时泵站的负压值，严重影响相邻抽气管道的抽气效果。最后，采用压力梯度法对玉屋矿瓦斯抽采管道进行监测，发现6~7测点压降斜率异常（-3×10⁴ )，测点7-8压降斜率恢复正常(-7×10 ⁵ )，判断排水管道在距泵站1300-1500 m处堵塞。