Studies On The Influence Of Venting Duct On Explosion Venting

Explosion venting is an effective technique method in industries to reduce or avoid the losses caused by explosions. In the early stages of an explosion, weak areas in the walls of plant open at low overpressures, and consequently, much of the explosion is dissipated in the open air. In this way, plant can be protected. But flame and blast ejecting from plant is damage to neighboring structure or equipment or personnel in the vicinity. To avoid potential damage above metioned, vent duct can be used outside of the vent to guide explosion to a safe place. Therefore, it is quite meaningful to study the influence of size and structure of vent duct on venting process, which has guiding significance on design of the vent vessel and the vent duct.In this paper, experimental studies on the explosion venting of aluminium dust is conducted in 1.3L Hartmann tube connected to a vent duct. The experiments under different venting conditions (size and structure of vent duct, dust concentration, partical size, at el) are performed and the perssure-time curves of the internal and external flow field are obtained. The main work and conclusions are as follows:(1) Study on explosion venting with straight duct Experiment is performed with only straight duct, and influence of various factors on venting process is studied. Several conclusions are obtained. The maximum reduced pressure and the maximum rate of pressure rise increases with length of straight duct increasing. Furthermore, the maximum reduced pressure increases with length at logarithmic growth. Vent duct being wider, the maximum reduced pressure is lower. There exists an optimum concentration making the maximum reduced pressure and the maximum rate of pressure rise reach to a maximum. This concentration decreases with diameter of straight duct increasing. The effect of dust particle size on the maximum reduced pressure can be ignored, while the maximum rate of pressure rise increases with particle size decreasing.(2) Study on explosion venting with bend Experimental results suggest that the maximum reduced pressure increases because of bend existing. The closer to vent bend is , the more remarkable influence of bend on venting process is. The more complicated structure of vent duct is, the higher the maximum reduced pressure is. Venting effect of bend is equal to that of straight duct that is two or three times as long as bend. (3) It is studied that abnormal experimental phenomenon ,such as Helmohltz oscillation, double pressure peak and negative pressure peak exceeding overpressure, appears during dust explosion venting. Furthermore, cause is analyzed for all kinds of phenomenon.The new ideas presented in this paper are as follows:(1) Influence of size and structure of vent duct on venting process is studied. Moreover, this paper give quantitative relation for various factors, which is helpful to design of vent duct.(2) Comprehensive compare venting effect for all kinds of vent duct. Sorting of venting effect for all kinds of vent duct is obtained, which can be used as basis for design of vent duct.