| Explosion venting technology is one of the main measures of dust explosion disaster control,which is widely used in all kinds of production equipment and auxiliary equipment with explosion risk.In order to avoid the secondary hazards of dust explosion of equipment and facilities involved in dust explosion,it is often necessary to release shock wave,high-temperature flame and explosion products to a safe area with the help of explosion venting duct.It is very likely that the explosion disaster propagation process will be changed and the safety effect of explosion venting will be greatly affected.However,the existing researches mainly focus on the traditional common way of explosion venting,the research on the mechanism of explosion relief by duct is less,and the safety effect of explosion relief by duct is lack of scientific and accurate evaluation basis,which restricts the practical application of this explosion venting technology in dust explosion-proof engineering.Based on this,with the help of a self-designed small-sized cylindrical explosion venting experimental device,dust explosion venting experiments were carried out with corn starch as the explosion medium,in this paper,the difference of explosion venting dynamics among three different ways of explosion venting,such as common explosion venting disc,straight duct and bent duct is studied,it provides a scientific basis for the optimum design of the explosion venting duct.First of all,the experiment of ordinary venting plate was carried out to study the venting process under different opening pressure of venting surface.The results show that there is a positive correlation between the maximum venting pressure and the opening pressure.By observing the flame propagation,it is found that there is a negative correlation between the number of venting and the opening pressure.When the opening pressure is small,the vessel will have three indirect venting at most.The second and third venting flames increase in the spread range and existence time.Secondly,the explosion propagation process in the vessel and in the duct is studied through the explosion venting experiment of the straight duct.It is found that,similar to the conventional venting mode,there is a positive correlation between the maximum venting pressure inside the vessel and the opening pressure of the venting surface.Compared with the general venting,the maximum venting pressure and the maximum rate of pressure rise in the vessel increase with the existence of the duct,and the pressure curve in the duct presents the typical "three-peak structure" which is caused by the membrane breaking shock wave,the second explosion and the flame burning in the vessel.There is a positive correlation between the secondary explosion strength and the opening pressure of the venting surface.Finally,the effect of the structure characteristics of the bent duct on the explosion venting process is studied by conducting the explosion venting experiment of the bent duct.The results show that the maximum venting pressure is positively and negatively correlated with the bent angle and the bend distance.Compared with different ways of explosion venting,it is found that the secondary explosion intensity in the duct will be increased when the bend structure reduces the explosion venting efficiency of the explosive products in the vessel.Therefore,in the design of bent duct parameters,not only the influence of the duct structure on the pressure inside the vessel,but also the strength of the bend duct should be fully considered,as far as possible to choose a small bend angle,bent distance large bent duct. |
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