The effect of static electrification on gas-solid flows in vertical risers

Steady, fully developed gas-particle flow in a vertical riser is analyzed. The model consists of axial momentum balances for the gas and particle phases, a radial momentum balance for the particle phase, and Poisson's equation for the electric field. Each particle carries a prescribed charge. Consequently, a radially varying electric field develops spontaneously, and this drives an electrophoretic flux of particles toward the wall. This is balanced by a diffusive particle flux. At steady state, these fluxes balance and produce a radially nonuniform particle volume fraction distribution. This, in turn, affects the axial momentum balance. The model captures important qualitative features of riser flows: core-annular particle distribution, annular particle downflow at low riser gas velocities, and annular upflow at high gas velocities. Furthermore, the model accurately depicts results on riser flows reported by Bader et al.