Application of Factorial Analysis to the Study of Vented Dust Explosions in Large Biomass Storage Silos

Dust explosions are a major concern in many industrial facilities and particularly in storage areas of biomass materials. Although venting standards (EN 14491 and NFPA 68) provide satisfactory safety levels for most industrial applications, they present some limitations and there exist situations that they do not contemplate. Vented dust explosions in a 4500 m3 silo for the storage of wood pellets were simulated by computational fluid dynamics. Maximum overpressures were registered and compared. The influence of several parameters including initial turbulence level, dust concentration, ignition location, and vent area was studied. A factorial analysis was carried out to determine the importance of each of the four parameters, along with possible interactions between them. The results showed great variations in the overpressures between the different scenarios simulated. Vent area, ignition location, and dust concentration showed similar effects on the overpressure (around 25%), while initial turbulence had half this effect (13%). One interaction effect out of the eleven possible interactions was identified as relevant for this specific industrial scenario: the combination of the ignition location and the initial turbulence, with an additional effect of 5% on the overpressure. The factorial analysis applied in this study could be of interest to the risk assessment of industrial facilities.