Experimental and Numerical Study of Two Phase Flow in a Cylindrical Cyclone Separator
Eyitayo Amos, AFOLABI, J.G.M, Lee
School of Chemical Engineering and Advanced Materials
Newcastle upon Tyne NE1 7RU
Compact separators are now widely used in the petroleum industry as an effective and economical alternative to the conventional vessel type separators which are expensive, heavy and bulky in size. Inspite of the many advantages it offers, the hydrodynamic flow field within the cyclone is characterized as turbulent, highly anisotropic and multiphase in nature. This work presents a three dimensional experimental and computational fluid dynamics (CFD) study of air –water flow field in a 30 mm diameter laboratory based test facility of the Gas- Liquid-Liquid Cylindrical Cyclone separator. Since turbulence inside the cyclone determine the separation of the multiphase flow, it is important to predict the hydrodynamic flow behaviour of the water- air multiphase flow and these can be used to optimize the cyclone design.
Stereoscopic Particle Image Velocimetry and Planar Laser Induced Fluorescence techniques were used to provide detailed three dimensional velocity vector maps across different illuminated planes of the cyclone. These measurements were used to describe the effect of gas bubbles, gas core and the gas – liquid interface on the hydrodynamic flow behaviour in the cyclone. In addition, Eulerian- Eulerian multiphase approach and the Reynolds Stress Turbulence Model (RSM) were applied to simulate the flow field characteristics of cylindrical cyclone. Velocity profiles and turbulence quantities across the cyclone diameter at six different axial planes were measured and compare with the experimental results.
The velocity profiles show greater fluctuations near the region of the inlet and this indicates higher mixing and separation. Then, the flow becomes more stable and less turbulent in other regions far away from the inlet. The tangential velocity profile revealed the formation of forced vortex near the center and free vortex towards the wall of the cyclone. Axial velocity field showed a downward flow near the wall and small upward flow near the center of the test section of the cyclone. Results of the numerical simulations show consistent agreement compared with the stereo- PIV measurements at different axial stations.