Study On Dispersion And Deflagration Of Flammable Gas

During the transportation, storage, processing and using of flammable gases, the cloud explosion may happen and make great damage to people and property loss if the mixture of flammable gas and air is accidentally ignited. Supported by the National Basic Research Program of China (973), the study on dispersion and deflagration of flammable gas was finished.In this paper, a physical model was founded from the real scene. The process of dispersion and deflagration of flammable gas was simulated by FLUENT6.2. Through using similarity criterion to the experimental physical model, the experimental research on dispersion of flammable gas was achieved.CFD method was applied to study the continuous release and dispersion. Taking propane as an example, the effect of factors(such as the releasing velocity of flammable gas,wind velocity,obstacle) on the dispersion of flammable gas was analyzed. On the basis of numerical simulation, it can be concluded that: The dispersion distance of the flammable cloud in the leeward direction will be longer if the releasing velocity of the flammable gas is bigger or the wind velocity is smaller; When the obstacle is low ,the flammable gas will get across it, while, when the obstacle is high ,the cloud will detour it; When releasing happens in the leeward of the obstacle, affected by the eddy behind the obstacle, a lot of flammable cloud will stay behind the obstacle, The nearer the releasing point is to the eddy center, the more serious the effect is.According to the situation of deflagration, this paper simplified the model into a two-dimensional model with uniform distribution. Through analyzing the data, it can be concluded that: The overpressure of one point can be expressed by a formula: (?)P =kR₀²/r, R₀ refers to the radius of the flammable cloud and r refers to the distance between this point and the ignition center; The overpressure rises first and then falls finally with the concentration of the flammable gas increasing; If we set a baffle near the cloud, the overpressure will be potentiated , The nearer the baffle is to the cloud ,the more serious this effect will be.