高压天然气管道喷射火焰长度和伤害范围研究

Investigation of flame length and damage range of high-pressure natural gas pipeline

喷射火会对周围人员和设施造成损坏,导致事故升级。天然气管道泄漏后发生喷射火不仅造成资源的浪费,还会造成环境污染,对生命财产安全造成严重危害。为研究长输高压天然气管道泄漏喷射火的危害,本文基于气体燃烧学和流体力学理论对天然气管道喷射火进行计算流体动力学(CFD)模拟,探究了泄漏孔径、泄漏压力和延迟点火时间等因素对管道喷射火焰长度和热辐射伤害范围的影响。结果表明,燃烧初期,在初始点火能量的作用下,喷射火焰长度随着燃烧的进行呈线性增加。当达到一定值后由于热量的扩散和供给不足会出现一段时间的不稳定状态,直至扩散的热量和喷射火燃烧产生的热量达到一个平衡状态,燃烧处于稳定状态。天然气管道喷射火焰前端会先形成球状火焰,然后逐渐发展为稳定的喷射火焰,火焰长度经历了快速上升、动态波动和稳定3个阶段。随着泄漏孔径和泄漏压力的增加,火焰长度随之增加,但其增加幅度逐渐变小。泄漏压力越大,喷射火焰轮廓越明显。热辐射水平伤害范围随着泄漏孔径和泄漏压力的增加而增大,其中泄漏孔径的影响高于泄漏压力,且轻伤范围增长最快。压力为10 MPa时轻伤范围和死亡范围分别为2 MPa时的1.55倍和1.72倍,泄漏孔径为100 mm的轻伤范围和死亡范围分别为20 mm时的2.03倍和3.08倍。随着延迟点火时间的增加,点火初期火焰长度和热辐射伤害范围显著增大,延迟点火时间对燃烧稳定后火焰长度和伤害范围的影响较小。

Jet fire may cause damage to people and facilities, which will lead to the escalation of accident. Jet fire caused by natural gas pipeline leakage could cause not only the waste of resources, but also the environmental pollution and serious damage to life and property. In order to study the hazard of jet fire in long distance natural gas pipeline with high pressure, CFD simulation based on gas combustion science and fluid mechanics mechanism was carried out to investigate the influence of leakage diameter, leakage pressure and ignition delay time on the length of flame and the damage range of thermal radiation. The results showed that at the initial stage of jet fire, the length of jet flame increases linearly with the combustion process under the action of initial ignition energy. There will be an unstable state for a period of time due to heat diffusion and insufficient supply, jet fire reaches an equilibrium state until the heat generated by the diffusion and the combustion of the jet fire reaches an equilibrium state. The front of the gas pipeline jet fire forms a spherical flame firstly, and then develop into a stable flame gradually. The length of jet flame has experienced three stages of straight rise, dynamic fluctuation and stability. The flame length increases with the increasing of leakage diameter and leakage pressure, and the increase amplitude decreases gradually. The flame profile becomes more obviously with the increase of leakage pressure. The damage range of thermal radiation level increases with the increase of leakage aperture and leakage pressure, and the influence of leakage aperture is higher than that of leakage pressure, and the growth of light injury range is the fastest. The ranges of minor injury and death at 10 MPa were 1.55 times and 1.72 times of those at 2 MPa. When the leakage diameter is 100 mm, the ranges of minor injury and death are 2.03 times and 3.08 times of those at 20 mm, respectively. At the initial stage of ignition, flame length and damage range increase significantly with the increasing of ignition delay time. When the combustion reaches stability, ignition delay time has little influence on flame length and damage range.