Electrostatic charge distribution of particles in gas–solids pipe flow

A model for the tribo-charging in gas–solids pipe flow to analyze the electrostatic charge distribution of particles has been presented. The model is based on the charge transfer caused by particle impacts on the wall surface and takes into account three probability density functions: (i) the number of collisions of a particle with the wall, (ii) initial particle charge, and (iii) the impact electrification factor characterizing the transferred charge. These functions individually affect the electrostatic charge distribution, and hence key parameters on the particle electrification can be determined from the charge distribution. Furthermore, the relevant experiments have been carried out using fly ash particles, 7 μm in count median diameter. The charge distributions, which were measured with the electrical-single particle aerodynamic relaxation time (E-SPART) analyzer, agreed with the theoretical ones, and by analyzing the key parameters determined from the experimental data, the states of the particle electrification were evaluated quantitatively.