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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)
Studying the dynamic characteristics of urban natural gas pipeline leakage can better predict the consequences of the spread of the leakage gas and the influence range. Through the dynamic leak process and state analysis of urban natural gas pipeline, a model of pipeline leakage calculation was established. According to the variation characteristics of dynamic leakage rate, Green’s function is applied to the fluid diffusion differential equation to obtain a dynamic diffusion synthetic model. Combined with the actual case of mathematical simulation analysis, under different conditions and different states of urban natural gas leakage and diffusion rules and hazardous areas. The results show that the leakage rate, the wind speed and the atmospheric stability affect the leakage of natural gas pipeline in cities. Increasing the wind speed or increasing the leakage ratio will increase the distribution range of natural gas leakage and diffusion concentration. However, when the wind speed exceeds 3 m / s, The diffusion range of natural gas decreases in the downwind direction; the scope of the fire damage increases with the increase of the wind speed, and the damage range of the steam cloud decreases with the increase of the wind speed; when the wind speed is small, the damage range of the steam cloud explosion is greater than Jet fire damage range, and when the pipeline leakage is relatively large, the wind speed is larger, the range of jet fire damage is greater than the scope of damage from the steam cloud explosion emergency evacuation distance should be determined according to different situations. (Figure 6, Table 1, reference 11)