Computer simulation for assessment of electrostatic hazards in filling operations with powder

This paper presents the computational assessment of electrostatic hazards associated with filling processes with charged powder. Since the particle-in-cell technique has been used in the simulation, the simulation has been able to give the self-consistent solutions for both the motions of charged particles and the electric fields inside vessels. However, in the previous model of the simulation, charge dissipation processes were assumed to be ignored. The assumption caused overestimation in the electrostatic hazards because the charge dissipation processes, i.e., charge relaxation of powder heap and discharges, reduce the electrostatic hazards as long as discharge energies are low. Therefore, in this paper, we propose models of the charge dissipation processes and present a simulation for a vessel of 1 m in diameter and a monodisperse powder of 1 mm in diameter and 1 μC/kg in charge-to-mass ratio. The models gave a much true simulation than the previous and the results of the simulation were comparable with experiments. Under the simulation conditions studied in this paper, all discharges occurred on heap surface. Also, the simulation estimated that incendiary discharges could be produced.