(20d) Development of Regenerable Fine Particulate Air Filters

Air filtration of fine particulate is a critical requirement to keep enclosed spaces clean and habitable or alternatively protect equipment and maintain industrial processes. The process often requires devices that can filter a high flow rate of air with minimal pressure drop over extended periods of time. Traditional high efficiency particulate air (HEPA) filters are made from fibrous materials and they tend to become rapidly caked by both small and large particles, leading to an increased pressure drop and the need for frequent and costly disposal and replacement. Mainstream has examined the integration of hydrocyclones and multi-stage electrostatic precipitators as a sustainable and completely regenerable alternative to traditional HEPA filters for numerous applications where large volumes of extremely fine dust is commonplace.

Traditional hydrocyclones are well-understood momentum-based separation devices that are able to efficiently filter coarse particulates, but become less effective as the particle size decreases due to the reduced drag force and increased levels of diffusion. Furthermore, conventional hydrocyclone modeling ignores surface effects and capture devices that can seal the bottom of the cyclone which become a more important factor as particle size decreases. Electrostatic precipitators work by electrostatically charging electrodes and subsequently the incoming particles and their effectiveness is based on particle resistivity and size and can be efficient at capturing small particles. Mainstream will discuss our recent work on effective integration of these technologies, modeling the extremely fine particulate interactions, as well as the experimental results from numerous applications including fine aerosol capture in biomass processing, and air filtration in enclosed spaces.