地下综合管廊天然气管道泄漏分析

Analysis of natural gas pipeline leakage in underground pipe gallery

结合保山市的地下综合管廊工程,采用数值模拟方法对该工程的燃气泄漏流速、浓度分布以及泄漏量和泄漏持续时间进行研究。结果表明,小孔泄漏的天然气其流速随时间的变化没有显著的变化,且速度随孔径的变化也不显著,但泄漏速度随着压力的增加而明显增加,向上、向下泄漏的流速差别不大,模拟值与理论值相对误差在3.5%以内。当天然气在综合管廊内扩散时,其浓度出现颈缩现象,因此报警器的安装高度应尽量靠近管廊顶部或底部。管道在泄漏放散时,若无振荡,则压力越高泄漏放散持续时间越短,泄漏孔径越小泄漏持续时间越长,管径越大管道越长,泄漏持续时间就越长;若出现振荡,泄漏放散持续时间延长,其是正常泄漏放散持续时间的2~3倍。

This paper uses the underground pipe gallery(UPG)project in Baoshan City to study gas leak mechanisms in the UPG project,including gas leak velocity and concentration distribution,the leakage volume,as well as the duration of leaks by numerical simulations.The results reveal that the leak velocity of natural gas does not change significantly with time and pore size but increases significantly with the rising pressure.There is not much difference in the upward and downward leak velocity,and the relative error between the simulated values and the theoretical values is within 3.5%.When natural gas spreads in UPG,its concentration demonstrates the phenomenon of necking,and thus leak detection sensors should be installed as close to the top or bottom of UPG as possible.During a gas leak in UPG,the simulation also demonstrates that without oscillations,the duration of the leak increases with the pipeline size and length but decreases with the increase in leak pore size and pressure.With oscillations,however,the duration of the leak is 2-3 times longer than a normal leak.