The relationship between fluidized bed electrostatics and entrainment

Existing methods of predicting entrainment from gas-fluidized beds, based exclusively on hydrodynamic variables and mechanisms, show extremely wide discrepancies in their predictions and often deviate by many orders of magnitude from experimental values. Based on simultaneous measurement of electrostatic charges in the freeboard region and entrainment, this paper will show that inter-particle electrostatic forces on relatively fine particles can be at least of the same order of magnitude as the gravity forces that must be overcome for entrainment to take place. Moreover, incorporation of a term for inter-particle electrostatic force leads to substantial improvement in the ability to correlate our experimental entrainment data. These results show that it is essential to consider electrostatic forces when predicting entrainment from gas-fluidized beds