Use of an electrostatic precipitator with wet-porous electrode arrays for removal of air pollution at a precision manufacturing facility

Abstract

This study analyzed the concentrations and size distributions of ultrafine particles, as well as their chemical components and morphologies, in the context of manufacturing processes, focusing on injection molding and tool repair. The concentrations of water-soluble gases such as sulfur dioxide (SO2), which is an undesirable emission, were measured during the manufacturing process. To remove particles and gaseous pollutants from manufacturing sites simultaneously, we improved the recently introduced electrostatic precipitator (ESP) system, in which wet-porous electrodes (WPEs) are used. The modified novel ESP consisted of an ionization part, for particle charging, and a collection part, installed in the working chamber of a manufacturing facility along with the WPE array to maintain a high-humidity environment using a water bucket. The proposed ESP could be also be coupled with laminar flow modules that are typically mounted in manufacturing facilities and used to maintain a clean environment during working processes. To evaluate the performance of the proposed ESP, the removal efficiencies of airborne particles and SO2 gas were investigated under operating conditions, with an applied electric field strength in the collection part of the ESP and flow velocities in the working chamber. The collection efficiency of the WPE-ESP was improved by increasing the electric field strength of the collection plates, and the maximum total collection efficiency of the system was similar to 99.5% for a 13.3 kV/cm collection environment under 0.4 m/s conditions. The proposed system also removed SO2 at 88.5-92.5% under flow conditions of 0.4-2.0 m/s. Furthermore, this system shows potential for increasing energy efficiency in workplaces due to the extremely low pressure drop.