Effect of powder feeding rate on electric charging and discharging in powder loading

The effect of the feeding rate of particles conveyed pneumatically through a pipeline on electrostatic discharge during powder loading is investigated. Measurement and theoretical calculation results of specific charges in repeated contact with the pipeline wall indicate that the specific charge can reach 63% of the equilibrium specific charge within 1 s. As the powder feeding rate increases, the specific charge decreases owing to an increase in the space density of the particles and a decrease in the number of particles in contact with the pipeline wall. Four types of discharges are observed in the silo during continuous powder loading, which differ in terms of generation time and duration, and no broad bulk surface discharges are observed in the latter half of the loading. Even though the specific charge increases as the powder feeding rate decreases, the frequency of electrostatic discharges is reduced when the net charge is low. [Display omitted] •Effect of feeding rate on electrostatic discharges during powder loading is investigated.•Specific charge decreases with an increase in powder feeding rate.•Four types of discharges generated in silo differed in time of generation and duration.•Electrostatic discharges are mitigated if the net charge is small.