Abstract: Hazardous chemicals with the properties of flammability and explosion are prone to cause fire and explosion accidents when tank leaks. In order to study the law of heavy-gas concentration diffusion caused by different liquid pools in continuous discharge, this paper uses the SLAB model to simulate the concentration diffusion of liquid pools released by tanks with gasoline, ethanol, methanol, and formaldehyde, respectively. The results show that the concentration tendency for denser-than-air diffusion and slightly denser-than-air diffusion increases firstly and then decreases with the downwind distance. The peak concentration of mixed vapor clouds of methanol and formaldehyde, at the height of 0.3~0.6 m from the ground to the detecting point of flammable gas detector, is higher than their lower explosive limit that is 5.5% and 7.0% respectively, which is more dangerous than heavy gas, and more likely to result in fire and explosion accidents.

Key words: heavy gas diffusion, slightly heavy gas diffusion, SLAB simulation, liquid-pool area, fire and explosion