城市天然气管道动态泄漏扩散特性模拟分析

Simulation of dynamic leakage and diffusion characteristics of urban gas pipelines

对城市天然气管道泄漏的动态特性进行研究,可以更好地预测泄漏气体的扩散危害后果和影响范围。通过对城市天然气管道动态泄漏过程及状态分析,建立了管道泄漏计算模型。根据动态泄漏速率的变化特征,将格林函数应用到流体扩散微分方程中,得到动态扩散的合成模型。结合实际案例进行数学模拟分析,得到不同条件和不同状态下的城市天然气泄漏扩散规律和危险区域。结果表明:管道泄漏比、风速及大气稳定度对城市天然气管道泄漏扩散均有影响,提高风速或增大泄漏比均会加大天然气泄漏扩散浓度分布范围,但当风速大于3 m/s时,天然气向下风方向扩散范围反而减小;喷射火危害范围随风速的增大而增大,蒸汽云爆炸危害范围则随风速的增大而减小;风速较小时,蒸汽云爆炸伤害范围大于喷射火伤害范围,而当管道泄漏比较大、风速也较大时,喷射火伤害范围大于蒸汽云爆炸伤害范围,应根据不同情况确定应急疏散距离。(图6,表1,参11)

Analysis of urban gas pipeline＇s dynamic leakage characteristics can be made to effectively predict the harms and reach of leak gas after diffusion. This paper proposes a leakage calculation model after analyzing the dynamic leakage process and state of urban gas pipeline. According to the changes of dynamic leakage rate, the Green＇s function is applied into the fluid diffusion differential equation to obtain a synthetic model of dynamic diffusion. Combined with mathematical simulation for actual cases, it is recognized how and where a leak gas may diffuse under different conditions and states. The results show that leakage ratio, wind speed and atmospheric stability affect urban gas pipeline＇s leakage and diffusion. Higher wind speed or leakage ratio will further spread the diffusion of leak gas. When the wind speed is greater than 3 m/s, the downwind diffusion will decrease, the harms of jet fire will increase, while the harms of vapor cloud explosion will decrease, as the wind speed increases. When the wind speed is lower, vapor cloud explosion will bring more extensive harms than jet fire, but when a serious leakage occurs at a high wind speed, jet fire will be more harmful than vapor cloud explosion. Therefore, emergency evacuation distance shall be defined depending on circumstances. （6 Figures, 1 Table, 11 References）