CFD simulation of turbulent flow field, feeding and dispersion of non-spherical dust particles in the standard 20 L sphere

In the work presented in this paper, the role of particle shape in turbulence generation, and dust feeding and dispersion in the standard 20 L explosion sphere has been investigated. To this end, CFD simulations were performed by taking into account only the effect of the shape factor on the drag coefficient, whereas the effect of the particle geometry and the interaction between non-spherical particles and rebound nozzle were fully neglected. Numerical results have shown that the turbulence level and the dust dispersion established inside the sphere are strongly dependent on the shape factor. Interestingly, as the shape factor is decreased, thus moving from spherical shape to fibrous shape, the model predicts that the fraction of dust actually fed into the vessel increases. Conversely, literature experiments have shown that the degree of partial feeding increases in going from spherical particles to fibrous particles. This suggests that the experimentally observed partial feeding can be attributed only to the geometrical interaction between the non-spherical dust particles and the holes of the rebound nozzle. As a consequence, in order to improve the feeding efficiency for non-spherical dust particles into the 20 L explosion vessel, a proper design of the nozzle is required