CFD simulations to study parameters affecting dust explosion venting in silos

Resumo

Vented dust explosions in a 16.3m3 silo were simulated using a commercial CFD program. Simulations were carried out for vent panels without inertia and for a silo roof acting as a venting device, with inertia. For the latter, the influence of several parameters on the pressures generated was studied, including characteristics of the initial dust cloud, size and position of the dust cloud, and ignition location. In addition, different vent area sizes and activation pressures were studied. For large vent areas and low overpressures, the results showed that the negative pressures generated could be of the same magnitude as the overpressures. Several peaks in overpressure were identified along the pressure-time curves. The results showed the expected trends and agreed reasonably well with the standards on explosion venting. Although the standards seem to overestimate vent area sizes to some extent, pressures are very dependent on the initial conditions of the dust cloud, and more unfavourable scenarios than those considered in this study could easily arise, producing a stronger explosion and higher pressures. For the venting roof with inertia, the pressures and associated vent areas matched the NFPA 68 extremely well.