Case Study on the Practical Use of Wettable Filters in the Removal of Submicron Particles

Abstract

Chemical and metallurgical industries frequently generate submicron wet/dry sticky particles. Conventional wet scrubbers, usually Venturi scrubbers, are used in such industries with varying degrees of success. These scrubbers may be capable of removing larger particles, but become inefficient when particle size drops below the one-micron level. The main idea of this project was to utilize a wettable filtration system after the scrubber to achieve a high removal efficiency with a relatively low increase in total pressure drop. The use of wettable filtration allows an equilibrium liquid film to develop on each of the filter fibres (Agranovski et al. [1]). This liquid film than acts as the primary filtration zone, removing particles before they reach the filter's surface. The filtered contaminants are then removed from the fibre by a continuous influx of fresh water preventing blockages to the system. The new filtration systems can be incorporated into existing air pollution control systems by utilizing a space inside hollow liquid/air separators commonly used for the baffling of droplets after wet scrubbers. The new wettable filtration system installed at a strip galvanizing plant achieved removal efficiencies of approximately 98.6 % for the total particle loading with a minimal increase in pressure drop.