球罐内甲烷气体泄漏形成的可燃气云规律研究

Flammable gas clouds resulted from the leakage and diffusion of methane in a spherical tank

基于计算流动动力学(CFD)方法,以Fluent软件为平台,以大连新港某球罐区为研究对象,建立真实尺寸的球罐内可燃气体泄漏扩散数值模拟模型,分析甲烷扩散规律及可燃气云尺度。提出采用可燃气云稳定状态时的水平方向长度Lmax、竖直方向高度Dmax作为尺度的衡量参数,用以评估可燃气云区域的大小。探讨初始压力、泄漏孔径、正风向风速对尺度参数Lmax和Dmax的影响规律,并对比可燃气体种类对尺度参数的影响。结果表明:甲烷以临界状态通过泄漏孔时,初始压力对Lmax和Dmax的影响可以忽略;Lmax和Dmax随泄漏孔径增加而线性增大,但随正风向风速增加而线性减小;相同泄漏扩散条件下,氢气泄漏引起的可燃气云范围最大,甲烷次之,丙烷最小。

This article intends to pursue the regularity of the flammable gas clouds resulted from the leakage and diffusion of methane in a spherical tank in hoping to find ways to prevent it from the resulting self-combustion and explosion. Our research has been done based on the computational fluid dynamics（ CFD）method with the help of a Software named Fluent. To make the research results of this paper,we have established a model of the leakage and diffusion of combustible gas from a high-pressure spherical tank by using a set of tank arrangements in Dalian Xingang（ New Harbor） as our case study sample. In our research,we have analyzed the methane gas diffusion regularity and the sphere of the flammable gas clouds in accordance with our observation and investigation of the above said experimental process and the actual results. To proceed with our study,we have further put up forward two dimensional parameters including the largest horizontal distance Lmax,and the largest vertical diameter Dmax with the purpose to evaluate the dimensions of the relatively stable flammable gas clouds. It is based on the above said conditions and actual results,we have made a detailed theoretical and practical discussion on the effects of the initial storage pressure,the discharge diameter and the positive wind velocity on the above mentioned two parameters. What is more,a careful comparison has been made to the effects of different kinds of combustible gases on the dimensions of the self-flammable clouds. The results gained from the comparison indicate that the effects of initial storage pressure on the largest horizontal distance Lmaxand the largest diameter Dmaxcan be neglected in the case of the methane leakage in the critical condition. Both the greatest horizontal distance Lmax and the greatest vertical diameter Dmaxhave been found increasing in the linear direction with the increase of the discharge diameter.However,the greatest horizontal distance Lmaxand the greatest vertical diameter Dmaxhave been found linearly decreasing with the increase of the positive wind velocity. In addition,the range of flammable cloud resulted by the leakage of H2 tends to be the greatest,followed by that of CH4,whereas the range of flammable cloud formed by the leakage of C3H8 has been detected the smallest among all three kinds of combustible gas.