Abstract
Centrifugal separation equipment, such as solid bowl centrifuges, is used to carry out an effective separation of fine particles from industrial fluids. Knowledge of the streams and sedimentation behavior inside solid bowl centrifuges is necessary to determine the geometry and the process parameters that lead to an optimal performance. Regarding a given industrial centrifuge geometry, a grid was built to calculate numerically the multiphase flow of water, air, and particles with a computational fluid dynamics (CFD) software. The effect of internal radial baffles on the multiphase flow was investigated. The results show that the baffles are helpful for the acceleration of the fluid, but they disturb the axial boundary layer, making it irregular, and originate a secondary circulating flow which hinders the sedimentation of small particles.
Highlights
Solid-liquid separation is an important operation, especially in industrial postprocessing
Knowledge of the streams and sedimentation behavior inside solid bowl centrifuges is necessary to determine the geometry and the process parameters that lead to an optimal performance
The results show that the baffles are helpful for the acceleration of the fluid, but they disturb the axial boundary layer, making it irregular, and originate a secondary circulating flow which hinders the sedimentation of small particles
Summary
Solid-liquid separation is an important operation, especially in industrial postprocessing. The plug flow model proposes a constant uniform axial velocity across the annular pool from the surface to the bowl wall. The boundary layer model suggests a thin boundary layer moving with high axial velocity towards the weir located at the interface between the liquid and the air core. This flow pattern in a rotating bowl is known especially for fluid flows with a free surface open to the atmosphere and it has been analyzed in tubular centrifuges by Bass [2] and Gosele [3] and in overflow centrifuges by Glinka [4] and Reuter [5]. Simulations of the flow in some industrial process equipment have been developed using CFD and even some researchers [7–9] have recently attempted to simulate the flow in centrifuges
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