Effect of Fibrous Coalescer Geometry and Operating Conditions on Emulsion Separation

Emulsions separation through porous fibrous media is a popular and complex process. This research investigates the influence of superficial velocity (0.6–1.8m/min), inflow direction (horizontal, radial), and sandwich filter structure on the phase separation performance of nanocoated coalescing filters. Experiments were performed using three different filters and their different sandwich combinations for 1% isooctane in water emulsions with mean droplet size 5 μm. These filters were coated with hydrophobic–oleophilic nanoparticle to impart suitable wetting and surface roughness functionality. With the increasing superficial velocity, the separation efficiency and quality factor decreases while the pressure drop across the filter increases. A rapid drop in the separation efficiency takes place above the superficial velocity of 1.0 m/min. The separation efficiency does not depend on the inflow direction, but the pressure drop across the filter is about half in the horizontal inflow direction than in radial inflow direction. For high droplet capture, the filter layer facing the influent stream should be made of the finest available fibers while its wettability does not affect the droplet capture. For effective separation of liquid droplets from a fluid stream, a vertically oriented gradient filter preferably wetted by dispersed phase and with increasing fiber size and permeability from influent to effluent is the most favorable structure.