Study On Theoretical Analysis And Application Of System Safety And Stimulation Of Gas Network

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.