Removal of Fine Particles From Nonaqueous Media by Cross-Flow Electrofiltration-Hydrodynamics and Mass Transfer

An improved method of removal of fine particles suspended in nonaqueous media by the application of a high-voltage electric field was previous developed. However, to better understand the cross-flow electrofliter for future design improvements, a mathematical analysis of the filter was performed and more experiments were conducted with filter tubes of several porositites. Experiments were conducted with α-Al203, particles suspended in tetralin. Outlet concentrations of the concentrated slurry were measured with a gamma ray densitometer. A description of the flow field in the cross-flow electrofilter was obtained by solving the Navier-Stokes equations for annular flow with suction through an outer porous wall. A perturbation solution for the flow field was then used in a mathematical model which describes the concentration distribution in the electro filter. Numerical solutions were obtained by using the Crank-Nicholson finite difference method. Clear boundary layers near the filter wall were calculated by either the finite difference method or by an approximate technique using the method of characteristics. Cake thicknesses and outlet slurry concentrations were also computed.