Experimental investigation into the vented hybrid mixture explosions of lycopodium dust and methane

Abstract

Vented hybrid mixture explosions were conducted in a 20-L chamber with different venting diameters and static activation pressures. Simultaneously, the maximum explosion pressure and the maximum rate of pressure rise of hybrid mixtures were also determined. It was found that the addition of methane to lycopodium dust led to an increase in both the maximum explosion pressure and the maximum rate of pressure rise and a decrease in the optimum dust concentration. Both the maximum explosion pressure and the maximum rate of pressure rise of hybrid mixtures were higher than those of lycopodium dust, but lower than those of methane. Similarly, the addition of methane to lycopodium dust led to an increase in the maximum reduced pressure, and the maximum reduced pressure increased with increase of the methane concentration. This effect was more pronounced for small vents and high static activation pressures. The maximum reduced pressure of the hybrid mixture was higher than that of lycopodium dust, but lower than that of methane. This was consistent with the relationship of the maximum explosion pressure between the three different systems. However, the increase in the maximum reduced pressure of lycopodium dust taken by the additional methane was obviously higher than that in the maximum explosion pressure, indicating that the influence of methane on the maximum reduced pressure of lycopodium dust was more significant. Adding methane to lycopodium dust increased the longest vented flame length and decreased the duration time of the external flame. Similar to the maximum reduced pressure, the longest flame length of the hybrid mixture was longer than that of lycopodium dust, but shorter than that of methane. However, it is the converse for the duration time of the external flame.