EXPERIMENTAL ANALYSIS OF WET ELECTROSTATIC SCRUBBING FOR THE ABATEMENT OF SUBMICRON PARTICULATE MATTER

Experimental results on wet electrostatic scrubbing of submicronic particles, produced by a model combustion process, are reported. This process should be used to develop new technologies to reduce environmental footprint of industry and transportation, but also for the cleaning of indoor air or virus abatement, and may have application to the recovery of precious by-products in particulate forms (e.g. entrained catalysts in process gas streams). Experiments were carried out in a lab-scale facility that was purposely designed and optimized to perform tests with a train of falling droplets of identical size and charge, which scrubs a closed volume of gas containing pre-charged submicronic particles at opposite polarity. The experimental campaign aimed to assess the effects of droplet and particle charge and number of scrubbing droplets on the efficiency of wet electrostatic scrubbing. Results were interpreted with a model derived from the theory on wet scavenging of aerosol particles in atmosphere showing a good matching between experimental and theoretical data. Experimental results and modeling demonstrated that the process was dominated by electrostatic interactions among droplets and particles. Particle removal efficiency, in the submicronic range, was favored by higher particles and droplet charges, while image charge seem to have a negligible effect on particle abatement when only the droplets are charged. Results allowed assessment of guidelines for the design of wet electrostatics scrubbers for particle abatement, which are discussed in the paper with reference to a specific case study.