Turbulent Flames Speeds and Laminar Burning Velocities of Dusts using the ISO 1 m³ Dust Explosion Method

The ISO 1 m³ dust explosion vessel was instrumented with thermocouples acting as flame detectors. These were used with methane/air gas explosions to show that the explosion flame was spherical in the constant pressure phase of the explosion and that a reliable flame speed and burning velocity could be obtained. This technique was used to determine the turbulent burning velocity using the same method of compressed air injection as used in the ISO 1 m³ dust explosion tests. This enabled the mean turbulent flame enhancement factor of the air injection system used in the ISO 1m³ equipment to be determined as 4.0. The mean flame speed was measured for dusts and these were shown to correlate linearly with the Kst for that dust. The turbulence factor determined from gas explosions was used to derive the laminar flame speed for the dusts and then using the adiabatic constant pressure expansion ratio the laminar burning velocity was derived. This gave peak laminar burning velocities in the 0.15 – 0.55 m/s range for the dusts investigated: corn flour, lycopodium, walnut, Kellingley coal, pistachio nuts. These were in good agreement with other measurements in the literature.