【作者】 张甫仁；

【导师】 杨昭；

【作者基本信息】 天津大学 ， 制冷及低温工程， 2005， 博士

【摘要】 燃气管网系统危险性分析及系统仿真,是目前燃气领域研究的重点和难点,而我国在这两方面的研究,尤其是在燃气管道泄漏及扩散危险性的研究远远落后于国外。因此本课题是国内亟待深入开展的一项前沿应用型课题。本文的主要研究内容如下:以故障树实统双析法对城市燃气管网系统危险源进行了辨识分析,建立了火灾爆炸事故故障树图,提出了基干枝叶链接法实现故障树的智能绘制和参数输入。提出了蒙特卡洛数值模拟方法,简化了传统故障树的复杂计算过程,且模拟结果与理论计算结果最大绝对误差不超过0.4%。在对相关参数进行讨论、分析的基础上,结合现有泄漏模型,建立了非等温条件下的稳态管道泄漏小孔、管道及大孔模型。依据动量和能量守恒方程,以大孔模型泄漏为研究对象,得出了高、低压管道泄漏均只可能有两种泄漏状态存在,而中压泄漏则可能有三种情况存在,从而完善了目前单纯的三状态和两状态模型。在稳态泄漏模型的基础上,以大孔模型为核心,建立了非等温非稳态泄漏的基本模型。通过应用分析,得到了各模型的大致适用范围。以燃气管网泄漏扩散的基础模型和湍流扩散微分方程为基础,结合其相应的初始及边界条件,利用格林函数对该微分方程组进行求解,从而建立了燃气管线动态泄漏扩散模型。以实例为基础,讨论分析了泄漏扩散所造成的各种危险范围。以三大守恒方程为基础,建立了等温和非等温条件下的燃气管网稳、动态仿真理论模型。并根据工程的精度要求,对模型进行了适当的简化。以有限差分法为基础,得到了上述模型的求解方法,通过加入耗散项,改进了求解结果的稳定性,并开发了燃气管网稳、动态仿真程序。通过对北京六环天然气管网进行了实际应用和分析,得到了出口压力和流量综合平均误差分别为1.21%和2.62%的仿真结果。本文以理论分析和计算机仿真为手段对燃气管网系统危险性及系统仿真进行了较为全面的分析和应用研究,所采用的方法和得出的结论可供燃气管网安全性研究及管网优化设计时参考。更多还原

【Abstract】 Hazards analysis and stimulation, are emphases and difficulties of the researchfield of gas network,but in China the research on these two fields, especially in theresearch of the danger of leakage and diffusion of gas pipeline, dropped far behind.So, it is a pressing problem to research on analysis of hazards and stimulation of gasnetwork in China. The main contents of this paper are as follows:The hazard sources of city gas network have been discriminated by using fact-stat.-double-analysis (FSDA) method, and the fault tree of city gas fire and explosionaccident has been established, and intelligent draw and data input of the fault tree hasbeen realized by skeleton-branch-leaf interlinkage (SBLI) method. This simulationand calculation method, which utilizes Monte-carlo method, has predigested thecomplex calculating process of traditional fault tree. Comparing with the traditionaltheory calculation method, the maximal absolute error of this method, which has beenput forward in this paper, is proved to be 0.4%. Based on discussing and analyzing ofcorrelative parameters, and combining the existing models, the steady leakage models(small-hole model, big-hole model and pipe model) of non-isothermal have beenestablished. Through analyzing on the big-hole model by conservation functions ofmomentum and energy, two-state leakage model of high-pressure long pipeline andlow-pressure pipe, three-state leakage model of medium pressure long pipeline havebeen established in this paper. This will perfect the existing simplex three-state andtwo-state leakage model. Based on the steady big-hole leakage model, the unsteadyleakage basal model of non-isothermal has been got. The suitable scopesapproximately of small-hole model,big-hole model and pipe model have been got byanalyzing instance. According to the differential equation of overfall diffusion, andcombining the relevant original and boundary conditions, the diffusion model ofunsteady leakage of gas pipeline has been got by using Green function method tosolve above differential equations. Through application and analyzation on instance,the dangerous area of poisoning, burning and blasting has been discussed. Based onthe three conservation functions, the isothermal and non-isothermal stimulationmodels of gas network have been established. Supposing the data at certain runningconditions, according to the request of precision of engineering, this model has beensimplified in this paper. Based on infinite differential method, the resolving methodhas been got. The stability of this method has been ameliorateed by adding dissipationterms,and the gas network simulation program was developed accordingly. Throughpractical application in natural gas network of Sixth Ring Road in Beijin, thestimulation results, which validate the dependability of this model and its’ resolvingmethod, have 1.21% and 2.62% error differentiating from actual data of pressureand quality separately.Based on theory analysis and computer simulation as main tools,this paperanalyzed and researched on the hazards and the stimulaiton of gas network roundly.The methods and conclusions may be useful to the problems of security and optiumdesign of gas network.更多还原