The Risk Analysis Of Natural Gas Tank Leakage Diffusion And Numerical Simulation

Natural gas has been widely used in people's life,the security of its storage increasingly becomes the focus of attention,through theoretical analysis and numerical simulation on gas leakage accident study,we can grasp the scope of its diffusion process,regularity and damage,provide some guidance basis for fire control and disaster mitigation.This paper mainly uses the method of the combine of theoretical analysis and numerical analysis.Theoretically analyzing the risk of storage tank,and using the DOW chemical index evaluation method to evaluate the safety of tank area,analyzing possible accidents and the influence factors of the accidents,combined with actual situation,determining the related parameters,using Gaussian plume model to calculate the gas hazard range under different leakage aperture.Using FLACS software to simulation,according to the influence factors of analysis,contrasting different leakage rate,temperature and wind speed,acquiring the change of natural gas storage tank leakage diffusion,simulating the whole process of leakage diffusion,selecting typical accident scene,acquiring the range of leakage diffusion and the change of the explosion overpressure,and providing the emergency disposal scheme.According to the physical and chemical properties of natural gas,identify hazards,and tank area has been constitute a major hazard,using the DOW method for tank area safety evaluation,calculated that hazard radius is 54.8m,hazard area is 9439.5 m2.Analyzing influe--nce factors and selecting rectangle hole leakage,leakage location is in the tank bottom H =2.5 m,selecting difffusion coefficient according to the atmospheric stability,with Gaussian plume model,we can get when leakage aperture is 101 mm,80 mm and 20 mm,maximum damage range respectively is 15m,9 m and 5 m.Simulating the state of the gas leak in different time,the gas diffusion process mainly includes turbulent jet,rising buoyancy and turbulent diffusion.With natural gas 5%lower explosive limit as a dangerous border,in a typical meteorological conditions,the gas hazard area up to 56 m,in the direction of the wind,maximum value up to 7.5m against the wind,and 46.5m in down wind,dangerous area is 1591 m2,the harm of whole space volume is 40462 m3;In summer condition,gas hazard area up to 34 m,dangerous area is 949 m2,the harm of whole space volume is 18997 m3;In winter condition,maximum width of cloud is 30 m,the longest length is 28 m,15 m in a downwind direction,13 m against the wind,gas hazard area up to 38 m,the largest damage volume is 26847m3.Through igniting at different times and different locations,the result is that overpre--ssure is under 1Mpa,which is work pressure of tank,at the same time less than 100 Kpa which can cause harm to human body,in this simulation conditions,it will not break surrounding tank,and cause more badly accidents.