Effect of different vent covers on the overpressure and flame propagation characteristics of hydrocarbon fuel-air mixture venting explosion

Abstract

A series of hydrocarbon-air fuel venting explosion experiments were carried out in a 20-L small-scale vent tank, and the effect of four different vent covers with an inherent rupture pressure of 10 kPa on the overpressures and flame propagation characteristics was studied. The results of the experiments showed that all the internal and external overpressure-time profiles have five typical overpressure peaks, induced by burst of the vent cover (△p1), inertia effect (△pneg), burned gas releasing (△p2), external explosion (△p3) and Helmholtz oscillation (△phel), respectively. The dynamic process of the flame was basically tally with the rule of ‘smooth and hemispherical flame-twisted and stretched flame-mushroom cloud-like/ellipsoidal flame-extinguishing flame’, but some differences were still existed due to the specific damage mode of each vent cover. When the vent opening was sealed by different vent covers, the values of internal and external overpressure peaks, maximum rate of overpressure rises, flame front location along different directions, and flame front speed along different directions showed various trends. Specifically, the enhancement effect of the metal cover plate and PE vent cover was significantly weaker than that of the paper vent cover and Al vent cover for the overpressure and vertical flame parameters, while, the enhancement effect of the metal cover plate was found to be greater than the other three for the horizontal flame parameters. Consequently, PE cover had the optimum performance for the explosion venting under the same inherent rupture pressures. These results improve our understanding on gas explosion dynamics in a semi-confined space with a vent cover, and provides the overpressure and flame characteristics of gas venting explosion under different vent boundary conditions from the qualitative and quantitative view.