A Numerical Study On Oil Vapour Dissipation Of Dome-roof Oil Tank

In the petroleum industry,dome-roof oil storage tank is often used to store crude oil of small capacity,which plays an important role in the collection,transportation,and storage of crude oil.As it is well known,during the daily operation of dome-roof tank,it is necessary to exchange oil gas with the outside automsphere through breather valve on tank’s top to banlance the pressure in the tank.In the process of ‘big breathing’ and‘small breathing’,the oil vapour discharged from the dome-roof tank will not only cause oil loss,reduce the economic benefits of the tank but also pollute the environment.When the concentration of the oil gas discharged from the exhalation valve is high,it may also induce severe accidents such as combustion and explosion.Therefore,the study on the oil gas dissipation characteristics of the dome-roof oil storage tank is of great significance to reduce the tank loss,protect the environment and ensure the safe production.In this paper,the dissipation characteristics of oil gas discharged from the dome-roof oil storage tank in the process of ‘large breathing’ and ‘small breathing’ are studied numerically.Firstly,the natural gas dissipation simulation process based on FLUENT software is studied and verified by classical examples.Then,the numerical calculation model of dissipation of discharged oil gas from a single dome-roof tank is established.To study effects of wind speed and ‘breathing’ mode,oil gas dissipation processes at six wind levels and under ‘large breathing’ and ‘small breathing’ are simulated and the gas concentration around the tank is analyzed in detail.Subsequently,to study the effect of wind field interference,computational model of oil gas disppsipation from two neighbor dome-roof tanks at three gap distances are established.Comparing the oil gas concentration at the same location,effect of gap distance on the gas dissipation feature around two dome-roof tanks is revealed.Finally,based on the numerical results from on-tank and two-tank models,some suggestions are proposed to prevent accidents caused by excessive oil gas concentration around the dome-roof tank.