综合管廊中掺氢天然气泄漏安全性分析

Safety Analysis of Hydrogen-Blended Natural Gas Leakage in Comprehensive Pipe Gallery

为了解掺氢等多因素耦合对管道输送中掺氢燃气泄漏扩散的影响,针对3种常见燃气输送场景中的地下综合管廊,从其受限空间易导致燃气云积聚爆燃的特性出发,考虑不同泄漏方向、掺氢比、管道压力等影响因素,使用Fluent软件对综合管廊内可能出现的泄漏场景进行模拟,研究了其内部燃气的分布特性,并对报警探针位置及其间距设置进行了安全性分析。模拟结果表明:泄漏口朝向会严重影响贴壁燃气分布,二次流近壁区的燃气积聚更加明显,在侧壁距顶部30 cm处安装探针能有效降低报警延迟;当掺氢体积分数为20%时,泄漏速度提高了9.03%,导致泄漏口近端的燃气积聚加剧而泄漏口远端的风险略微增加;燃气泄漏5 s时的爆炸浓度(燃气摩尔分数大于4%)区间距离为1.54 m,添加10%、20%的氢气可使该距离分别增加16.2%(1.79 m)、36.4%(2.10 m);当管道压力增加至0.8、1.2、1.6 MPa时,达到报警浓度的时间分别缩短了18.9%、28.3%、32.1%。研究可为综合管廊内掺氢天然气的输运安全提供参考。

In order to understand the impact of various coupled factors,such as hydrogen blending,on the dispersion of hydrogen-blended gas leakage in pipeline transportation is studied based on the underground comprehensive pipe galleries in three common gas transmission scenarios.The study starts from the feature that confined space is prone to cause gas cloud accumulation and combustion,with consideration given to factors such as different leakage directions,hydrogen doping ratios,and pipeline pressures,and the simulation of potential leakage scenarios within the comprehensive pipe galleries is conducted using Fluent software.The distribution characteristics of internal gases are examined,and a safety analysis of alarm probe positioning and spacing is performed.The simulation results show that the distribution of gas is significantly influenced by the directions of the leakage port,with a more obvious accumulation of gas observed in the near-wall region of secondary flows.The installation of probes at a distance of 30 cm from the top of the side walls effectively reduces alarm delays.With a 20%hydrogen blending,the leakage rate increases by 9.03%,leading to an intensification of gas accumulation near the leakage port and a slight increase in risk at the distant end of the port.The explosion concentration range(gas concentration>4%)at 5 seconds of gas leakage is found to be 1.54 m,and the addition of 10%and 20%hydrogen increases this distance by 16.2%(1.79 m)and 36.4%(2.10 m),respectively.Furthermore,as pipeline pressure increases to 0.8,1.2,1.6 MPa,the time required to reach the alarm concentration is respectively shortened by 18.9%,28.3%,32.1%.Valuable insights for the safe transportation of hydrogen-blended natural gas in comprehensive pipe galleries[JP]can be provided by this study.