【作者】 王建；

【导师】 喻健良；

【作者基本信息】 大连理工大学 ， 安全技术及工程， 2013， 硕士

【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。更多还原

【Abstract】 There are many deflagration accidents resulting from combustion gas leakage and diffusion in large tank area, which causing huge economic loss and casualties. Although there are a lot of research reports about combustible gas diffusion and deflagration in tank area, However, existing research only focuses on combustible gas leakage diffusion regularity or deflagration intensity of combustible gas in open or restricted space, which have not been combined the deflagration intensity of irregular shape of gas cloud due to combustible gas leakage and diffusion, resulting in research achievements cannot provide clear technical guidance for accident model that deflagration comes from combustible gas leakage diffusion.In this paper, the CFD model was adopted to study the law of combustible gas leakage and diffusion in storage tank area and the formation regularity of irregular shape combustible gas cloud from leakage has been paid attention. The main research contents and conclusions of this paper are as follows:(1) The numerical simulation model of combustible gas leakage diffusion and deflagration in large spherical tank area was established. The geometric model was meshed and mesh independent solution was determined for diffusion model. At last, the model effectiveness validations were made on diffusion and deflagration model.(2) The leakage diffusion regularity of combustible medium was studied in tank area. Two parameters is presented in this paper, namely the horizontal maximum distance Lmax and height direction maximum diameter Dmaxto evaluate the range size of combustible gas cloud from gas leak quantitatively. Results show that, when storage tank pressure is IMPa and150mm diameter circular leak hole located spherical tank equator without considering wind speed, methane concentration is symmetry along horizontal direction when gas diffuses and the horizontal maximum distance Lmax is10.95m and remains stable when leakage time is1s, at2s, the height direction maximum diameter Dmax is8.8m reaching stable. The diffusion regularity of methane, hydrogen, propane were compared, it shows that, the risk of hydrogen is greater than the methane and propane.(3) The influence of tank pressure, leakage aperture size and location, wind speed on the range of combustible gas cloud due to methane diffusion were researched respectively. Results show that, tank pressure has little effect on combustible gas flammable range. The Lmax and Amax measuring combustible gas cloud range increases with increasing of leakage diameter, the horizontal maximum distance Lmax and height direction maximum diameter Dmax are17.14m and13.5m respectively on the condition of leakage diameter is200mm, the risk of deflagration becomes bigger when leakage aperture is set at the bottom of tank. Lmax and Dmax decreases with increasing of wind speed and Lmax and Dmax are8.71m and1.53m when wind speed is12m/s.(4) Based on the methane flammable range, the maximum diameter method, actual diffusion area method, center of gravity height sphere method and equal volume ball method were adopted to research maximum deflagration overpressure of irregular gas cloud from methane leakage and diffusion. The results showed that, when storage tank pressure is1MPa and150mm diameter circular leak hole located spherical tank equator without considering wind speed, the maximum overpressure are230kPa,151kPa,125kPa and130kPa respectively corresponding to the four kinds of simplified methods. The explosion overpressure obtaining from equal volume ball method is most close to the actual overpressure of combustible gas cloud, so equal volume ball method can be chose to evaluate the irregular gas cloud explosion intensity(5) The equal volumetric ball method is used to evaluate the deflagration intensity after methane leakage and diffusion under different aperture leakage and wind speed. The results show that, deflagration intensity increases as leakage aperture diameter increases and wind speed decreases.更多还原