An Investigation of Wavy Flow Passages on the Performance of Oil-Water Separators
Abstract The purpose of this research is to analyze flow fields within channels bounded by wavy plates and assess the effects of these flow passages on the efficiency of oil-water separators. Results from this study are used to analytically assess an industry accepted result that wavy plate channel surfaces promote a more effective oil-water separation process. For this investigation, an uncoupled, two-dimensional, dispersed-phase, simulation is implemented using a commercially available computational fluid dynamics code. First, the continuous phase (water) velocity field is calculated. For comparison purposes, both fiat and wavy passages are simulated. Next, buoyant oil particles (specific gravity of 0.70 and 0.95) are superimposed as the dispersed phase at the inlet to the channel. Oil droplet diameters of 100, 200, and 300 μm, which are typical droplet diameters encountered in industrial applications, are simulated. The particle trajectories are then determined and observations made of the particle behavior near the channel walls for both channel geometries. Results show that a percentage of the particles are captured in vortices generated in the fluid within the wavy plate corrugations. As more particles are captured within these vortices, the spatial density of oil particles increases thus promoting coalescence. The coalescence results in larger oil particle diameters that, in turn, enhance separation through increased buoyancy. These results appear to substantiate industry observations regarding an increased oil-water separation efficiency using wavy channel passages. Nevertheless, more research is needed to optimize the design of the passages and better understand the coalescence phenomena.