Abstract: Aiming at the problem of casualties caused by gas leakage and dispersion in chemical enterprises, the numerical simulation of gas dispersion under three kinds of obstacles was carried out by using Fluent software. The results show that the influence of obstacles on the gas concentration in the upwind side of the leakage source is far less than that on the downwind side. In the early stage of the leakage, obstacles and leakage rate are the dominant factors of the concentration of the vinyl chloride gas at the downwind side; during the middle period of the leakage, the concentration of the vinyl chloride gas at the downwind side is temporarily stable under the combined action of gravity, initial velocity and ambient wind speed; In the later stage of the leak, the ambient wind speed replaced the leakage rate and became the dominant factor of the concentration of vinyl chloride in the downwind side. As the obstacles have big hindrance on the ambient wind speed, the more obstacles, the slower the concentration reduction.

Key words:  , fire control, vinyl chloride , leakage diffusion, numerical simulation, obstacle ,  ,