Electrostatic capture of submicron particles in fiber beds

The emission of submicron sized particles is the most difficult to effectively control with current state-of-the-art technology. Experiments at Battelle-Northwest led to the discovery that charged particles could be efficiently captured by a thick fiber bed having a high bed-volume to fiber-volume ratio and a very low pressure drop. Interim results are presented for the removal efficiency as a function of particle resistivity, superficial gas velocity, bed depth and aerosol concentration. In general, for bed pressure drops less than 0.5 in H2O efficiencies greater than 90 percent were obtained at 300 ft/min (approximately 152 cms/sec) face velocity over the particle size range of 0.06 to 0.7 μm AMD and a particle resistivity range of 108 to 1012 ohm-cm. The most important variable was the bed face velocity with the collection efficiency varying inversely with velocity. The bed depth and volume void fraction were other significant variables bearing on the efficiency of the system. Empirical equations indicate a 100 percent collection efficiency might be attainable near or somewhat below a bed face velocity of 50 ft/min (approximately 25 cms/sec). However, a more sensitive measurement method would be required for experimental confirmation