Use of energetic electrons in a particle precharger and in a sulfur dioxide reactor

Abstract

Electrons energized by corona discharge to produce the necessary ionization for particle charging have been used in electrostatic precipitators for decades. This paper reports the use of an electron beam to release and energize electrons which produce copious charging currents in a bench precharger. Results have been obtained for various values of electron beam energy, beam current, electric field strength, current density, and exposure time in measurements of charging efficiency for large conducting spheres and 1 and 3 ..mu..m diameter PSL particles. After matching the beam energy and geometry in the bench precharger, particle charges greater than five times the theoretical ionic charging value were measured in the bi-electrode precharger. The increased charge can be explained by space-charge enhancement of the electric field and/or free electron charging. The use of very hgh energy electron beams for the removal of SO/sub 2/ and NO/sub x/ from flue gases has been previously established elsewhere. Since the energy regime for the electrons required for the production of oxidizing radicals is the order of 10 eV, a device which operates in a lower energy regime is attractive. A positive streamer corona device has been constructed and used to energize electrons for the purpose of producing oxidizing radicals. The performance of a pulse energized electron reactor (PEER) has been evaluated. More than 90% of the SO/sub 2/ has been removed from a test gas stream containing air, water vapor and 1666 ppM of SO/sub 2/. The power efficiency of the PEER device is greater than that for DC discharge or high energy electron beam treatment