Abstract: Different environmental conditions are set and the diffusion law of combustible gas for different oil types in different tank structures is studied by numerical simulation. The results show that the maximum leakage of light oil reaches 65.8 times and 48.2 times of heavy oil in fixed-roof and external floating-roof tanks, respectively. For light oil, the leakiness of fixed-top tank is much larger than that of floating-roof tank structure, and compared with fixed-top tank, the leakiness of internal floating-roof tank and external floating-roof tank is reduced by about 98% and 35% respectively.The storage safety of all three tank structures for heavy oil is relatively high. The higher the temperature is, the faster the combustible gas diffusion is, and the amount of combustible gas leakage increases by 10%, 23% and 28% at 0, 20 and 40 ℃, respectively, compared with -20 ℃. Ambient wind affects the rate of combustible gas volatilization and dilution, the greater the wind speed, the more obvious the effect, and the strongest effect of positive wind on the volatilization and dilution of combustible gas.

Key words: storage tanks, oil leakage, combustible gas diffusion, oil type, environmental conditions