A lab-scale system to study submicron particles removal in wet electrostatic scrubbers

• A new method to measure wet electrostatic scrubbing of submicron particles is shown.
• An electrospray in dripping regime is used to scrub charged and uncharged particles.
• Particle scavenging rate can be determined with appreciable precision.
• Atmospheric particle scavenging model correctly describe experimental results.
• Wet electrostatic scrubbing is far more efficient than wet scrubbing for PM<0.5.

This paper describes lab scale experiments that were carried out to determine the scavenging rate of submicron particles in the presence of charged droplets, which helps to study the mechanisms involved in wet electrostatic scrubbing process. The main aim of this study is the need to decouple the effects of particles–droplets interactions from the specific features of the electro-hydrodynamics of a charged spray. To this end, a novel experimental methodology was developed to carry out tests with an electrospray operating in dripping mode to produce a train of uniformly sized and charged droplets. Experiments were performed either with charged or uncharged particles in order to understand the differences between wet electrostatic scrubbing in the presence of electric forces, when both droplets and particles are charged, or in the presence of image charge forces only, when particles are uncharged. The obtained results demonstrate that the particle image charge effect does not lead to appreciable particle abatement, while Coulomb interactions become the dominant particle scavenging mechanism when particles are charged. In this case, the scavenging rate can be described by a first order equation in particles concentration and the experimental results are consistent with theoretical predictions based on the classical model of atmospheric scavenging.