储罐区可燃气体泄漏扩散模拟及爆燃灾害评估

发布时间：2018-02-22 11:57

本文关键词： 储罐区泄漏扩散非规则气云爆燃超压数值模拟　出处：《大连理工大学》2013年硕士论文　论文类型：学位论文

【摘要】：大型罐区内因可燃气体泄漏扩散引发的燃爆事故屡见不鲜,造成巨大的经济损失和人员伤亡。尽管有大量关于罐区可燃气体泄漏扩散和燃爆的研究报道,但现有的研究或者关注可燃气体泄漏扩散规律,或者考虑开敞或受限空间可燃气体的燃爆强度,并没有将可燃气体因泄漏扩散形成的非规则形状气云的燃爆强度结合起来研究,导致研究成果无法为因储罐内气体泄漏扩散继而引起燃爆的此类事故模式提供较为明确的技术指导。基于此,本文采用计算流体动力学方法,模拟研究了储罐区内可燃气体泄漏扩散规律,重点关注了气体因泄漏导致的非规则形状可燃气云形成规律,最后对非规则气云的燃爆强度进行评估。本文主要研究内容和结论如下： (1)建立了大型球罐区可燃气体泄漏扩散以及燃爆的数值模拟模型。对几何模型进行网格划分并确定扩散模型的网格独立解,分别对扩散和燃爆模型进行了有效性验证。 (2)研究了罐区内可燃气体的泄漏扩散规律,提出采用两个参数即水平方向最远距离Lmax以及高度方向最大直径Dmax定量评估泄漏气体形成的可燃气云范围大小。结果表明,当无风速且储罐压力1MPa,球罐赤道存在150mm圆形泄漏孔时,甲烷泄漏扩散浓度沿水平方向对称分布；泄漏1s时水平方向最远距离Lmax为10.95m并达到稳定状态；泄漏2s时高度方向最大直径Dmax为8.8m达到稳定。比较研究了甲烷、氢气、丙烷的扩散规律,发现氢气的危险性大于甲烷和丙烷。 (3)研究了储罐压力、泄漏孔大小和位置、风速对甲烷泄漏形成的可燃气云范围的影响规律。结果表明,储罐压力对可燃气云范围影响不明显；衡量可燃气体范围的参数Lmax和Dmax均随泄漏孔径增大而增大,200mm直径泄漏孔水平方向最远距离Lmax和高度方向最大直径Dmax分别为17.14m和13.5m；当泄漏孔位于储罐底部时燃爆风险增大；Lmax和Dmax随风速增大而减小,12m/s风速对应的Lmax和Dmax分别为8.71m和1.53m。 (4)分别采用最大直径法、实际扩散区域法、重心高度球法和等体积球法研究了甲烷泄漏扩散形成的非规则气云燃爆最大超压。结果发现,无风速且储罐压力1MPa,球罐赤道存在150mm圆形泄漏孔时,四种方法的最大超压值分别为230kPa、151kPa、125kPa和130kPa；等体积球法得到的爆炸超压值最接近可燃气云的实际超压,因此可用等体积球法评估非规则气云的爆燃强度。 (5)采用等体积球法评估了不同泄漏孔径和风速下甲烷泄漏扩散后的燃爆强度。结果表明,泄漏孔径越大,风速越小,燃爆强度就越大。
[Abstract]:Igniting accidents caused by flammable gas leakage and diffusion in large tank areas are common, resulting in huge economic losses and casualties. Although there are a lot of research reports on flammable gas leakage diffusion and explosion in tank areas, However, the existing research either pays attention to the laws of flammable gas leakage and diffusion, or considers the ignition intensity of combustible gas in open or confined space, and does not combine the explosion intensity of irregular shaped gas cloud formed by the leakage diffusion of combustible gas. As a result, the research results can not provide more clear technical guidance for the explosion caused by gas leakage and diffusion in the tank. Based on this, a computational fluid dynamics method is used to simulate the leakage and diffusion of combustible gases in the tank area, with emphasis on the formation of irregular gas clouds caused by gas leakage. Finally, the explosion intensity of irregular gas cloud is evaluated. The main contents and conclusions of this paper are as follows:. A numerical simulation model of flammable gas leakage diffusion and explosion in a large spherical tank is established. The geometric model is meshed and the mesh independent solution of the diffusion model is determined. The effectiveness of the diffusion and explosion models is verified respectively. In this paper, the leakage and diffusion law of combustible gas in tank area is studied. Two parameters, namely, the furthest distance Lmax in horizontal direction and the maximum diameter Dmax in height direction, are proposed to quantitatively evaluate the range of gas cloud formed by leaking gas. When there are 150mm circular leakage holes in the equator of the spherical tank with no wind speed and the tank pressure is 1MPa, the methane leakage diffusion concentration distributes symmetrically along the horizontal direction, the furthest distance Lmax in the horizontal direction is 10.95m and reaches a stable state at 1s. The maximum diameters (Dmax) of height reach a stable level of 8.8m during the leakage of 2 s. The diffusion laws of methane, hydrogen and propane are compared and studied. It is found that the danger of hydrogen is greater than that of methane and propane. 3) the effects of tank pressure, leakage hole size and location, and wind speed on the range of gas cloud formed by methane leakage are studied. The results show that the effect of tank pressure on the range of gas cloud is not obvious. The parameters of Lmax and Dmax for measuring the range of combustible gas are increased with the increase of leak aperture. The maximum diameters Dmax in horizontal direction and height direction are 17.14m and 13.5m. when the leak hole is located at the bottom of the tank, the maximum diameter Dmax is 17.14m and 13.5mrespectively, and when the leak hole is located at the bottom of the tank, the blasting wind is ignited. With the increase of wind speed, the Lmax and Dmax of 12m / s wind speed are 8.71m and 1.53mrespectively. The maximum overpressure of irregular gas cloud explosion formed by methane leakage diffusion is studied by using the maximum diameter method, the actual diffusion zone method, the barycenter height sphere method and the equal volume sphere method, respectively. When there are 150 mm circular leakage holes in the equator, the maximum overpressure values of the four methods are 230 KPA 151kPa125kPa and 130kPa. the explosion overpressure obtained by the equal volume sphere method is the closest to the actual overpressure of the gas cloud. Therefore, the deflagration intensity of irregular gas cloud can be evaluated by equal volume ball method. The results show that the larger the leak aperture, the smaller the wind speed, the greater the explosion intensity.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：X937

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