CFD Simulations of the Effect of Dust Diameter on the Dispersion in the 20 L Bomb

Prevention and mitigation measures for dust explosion are based on the knowledge of the thermokinetic parameters which characterise flammability such as Minimum Explosible Concentration, MEC, and explosion behaviour such as maximum explosion pressure, P-MAX, and deflagration index, K-St. Measurements of these parameters are performed in spherical vessels (20 L sphere or 1 m(3) sphere). The main issues in performing such measurements are related to the dust dispersion and to the turbulence level reached inside the sphere. Also, the dispersion and then concentration of the dust/air mixture in the vessel significantly affects the flame propagation, if stratification and sedimentation occurs. In this work we use a previously validated CFD 3D model to simulate the dust dispersion inside the sphere at different dust diameters. Results show that on increasing the dust diameter the dust is mainly concentrated at the vessel walls and the dust paths are different from those of the fluid flow.