Dust explosions in vented silos: Simulations and comparisons with current standards

Dust explosions represent a serious hazard to personnel and equipment in industries and silo facilities that handle combustible materials. Venting devices are the most common protective systems employed in silos, although their use may pose problems in large and low-strength silos. The main aim of the present work was to simulate dust explosions in silos using a commercial CFD program, the DESC code, to determine the pressures developed in vented explosions with vent areas of different sizes. Dust cloud characteristics were taken from studies carried out by the FSA (Research Centre for Applied System Safety and Industrial Medicine, Germany) in a 12 m3 silo with a mechanical feeding system. The pressures and associated vent areas in these simulations were compared to those contemplated in two venting standards. The simulated explosion pressures showed the expected trends for the associated vent areas and agreed reasonably well with the values contemplated in NFPA 68 (2007) [5]. However, when the reduced explosion overpressure was low, the vent area contemplated in EN 14491 (2006) [4] was much larger than in the present simulations.

Graphical AbstractSimulations of dust explosions in vented silos were carried out using a commercial CFD code. Cylindrical flat-bottomed silos with mechanical feeding systems have been studied. Initial dust concentration and turbulence level were set to real industrial conditions and different length-to-diameter ratios, vent areas and activation pressures were analysed. Results have been compared to American and European standards on venting.Figure optionsDownload as PowerPoint slideResearch Highlights
► Simulations of dust explosions in vented silos using DESC, a CFD code.
► Simulations agreed quite well with NFPA 68 (2007) [5].
► Large differences between simulations and EN 14491 (2006) [4] when Pred is low.
► Results depend on initial dust cloud conditions.
► Negative pressures can appear during venting process that could lead to buckling.