| Recent developments in liquid-liquid and solid-liquid separation reveal that the conventional two-phase hydrocyclone is an indispensable tool in petroleum and allied industries. This is attributable to its simplicity of operation and numerous diverse applications. In spite of the many advantages it offers, the hydrocyclone suffers a major drawback in the separation of multiple-phase immiscible mixtures. Occurrence of these mixtures, as dispersions of oil and solids within liquids, can be epidemic and environmentally undesirable. In resolving this impediment, the author developed a three-phase liquid-solid-liquid separation hydrocyclone by hydrodynamically incorporating a transverse aperture into a two-phase design.; Investigation into mathematical relationship between parametric and performance groups was pursued to develop a model of the three-phase hydrocyclone treating both dilute and concentrated slurry systems. An experimental program was designed to include fluid flow visualization and separation tests which were conducted on the fixed-dimension three-phase hydrocyclone. Using dye injection, the visualization tests revealed that the flows for dilute slurry system were coherent over a significant portion of the hydrocyclone axis and that negligible radial mixing occurred between the secondary and outer helical flows and vice versa for concentrated slurry system. During a stable vortex, a jet-like flow on the axis occurred from the spigot region to the overflow to a maximum amplitude of 2.65 mm.; In order to assess ultimately the performance of the three-phase hydrocyclone under different operating conditions, knowledge of the fluid velocity distribution inside the hydrocyclone was required. To determine the velocity spectra, a computational fluid dynamics approach was used. The developed Navier-Stokes equations in vorticity-stream function formulation form were identified as parabolic and elliptic. Employing Forward difference in Time and Central difference in Space (FTCS), the differential equations were converted into difference equations for numerical solution. The computed tangential velocity profiles behaved asymptotically as they approached the hydrocyclone wall yielding steep velocity gradients in that region and thus maximum effective viscosity. The computed and experimental velocity spectra results were in concordance. A unique aspect during validation of the results was that the computed and experimental tangential velocity profiles compared well better than the axial velocity profiles. (Abstract shortened by UMI.)... |
