Mixing behaviors of granular materials in gas fluidized beds with electrostatic effects

Abstract

The discrete element method combined with computational fluid dynamics was coupled to an electrostatic force model for computational studies of mixing behaviors in gas fluidized bed systems with electrostatic effects. Due to the presence of strong electrostatic forces between particles and walls, there was a high tendency for particles to be adhered to the walls or other particles near the walls within the fluidized bed, resulting in less vigorous fluidization. This in turn resulted in lower mixing efficiencies in comparison with fluidization in the presence of weaker electrostatic effects. Particle-wall electrostatic forces were on average stronger than both fluid drag forces and particle-particle collision forces when strong electrostatic effects were present, and this accounted for the difficulty with which particles adhered to walls could be removed and transferred to other locations within the bed. Such transfers of particles were necessary for mixing to occur during fluidization but required strong electrostatic forces to be overcome. © 2013 American Chemical Society.