Study On Concentration Prediction Of Oil-gas Leakage In Storage Tanks

As one of the important equipment in oil storage tanks,affected by the oil-gas corrosion,material aging,oil-gas leakage accident will happen,and then to the terminal security caused a certain.When the concentration of oil-gas is within the explosion limit,there will be the risk of fire and explosion.In addition,affected by the tank farm conditions,the leaked oil-gas will spread to the near ground,leading to human poisoning.In this thesis,the computational fluid dynamics software FLUENT is used to simulate the diffusion process of oil-gas leakage in the tank farm,and the distribution of oil-gas concentration in the tank farm under different environmental wind speed and leakage volume is determined:(1)A numerical model of oil-gas leakage and diffusion of a 10×10~4 m~3 external floating roof storage tank at different liquid levels is established,and the law of oil-gas leakage and diffusion of a single tank is analyzed.The effects of wind speed,the range change of control area above floating roof,liquid level height,Reynolds number and leakage on oil-gas leakage and diffusion are studied.The research shows that the liquid level height,the range change of the control area,Reynolds number and the leakage amount have a greater impact on the risk of oil-gas explosion,while the wind speed has a smaller impact on the oil-gas concentration in the control area above the floating disc.Through dimensionless analysis of numerical calculation results,the distribution function of oil-gas diffusion concentration suitable for different liquid level heights is fitted.Through numerical calculation,the functional relationship of gas leakage diffusion concentration distribution under different liquid level heights of the sealing ring of the external floating roof storage tank is verified.The results show that the prediction formula has high accuracy.(2)The model of oil-gas leakage and diffusion at the top of the tank farm is established,and the law of oil-gas diffusion from the surrounding tanks in the tank farm array is simulated and analyzed.The effects of environmental wind speed,leakage rate(mainly considering leakage velocity and leakage aperture)and Reynolds number on the oil-gas concentration distribution in the leeward diffusion area of the tank farm are studied.Research has found that environmental wind speed and leakage directly affect the migration and diffusion of oil-gas on the leeward side of the tank farm,as well as the overall risk of poisoning concentration caused by oil-gas on the leeward side of the tank farm.Through dimensionless combination of variable parameters and analysis of numerical calculation results,the distribution function of oil-gas diffusion concentration in the control area on the leeward side is fitted,and the effectiveness of this function is verified by simulation results.The results show that the numerical calculation results are in good agreement with the prediction results of the fitting function.Through data analysis and collation,this paper more accurately reflects the law of oil-gas leakage and diffusion in the tank farm,and can calculate the oil-gas concentration value at any time in the generally applicable prediction of tank leakage and diffusion accidents,which is conducive to predicting the tank explosion and human poisoning caused by the oil-gas concentration distribution of tank leakage in the tank farm,and provides a theoretical basis for emergency rescue decision-making.This method is suitable for predicting the concentration distribution of petroleum gas leakage and diffusion in tanks with different layouts and volumes,and can provide guidance for the safe operation and management of tanks.