Erosion prediction in slurry pipeline tee-junctions

A significant erosion problem is found to occur on steel blanks located inside tee-junctions in a slurry pipeline system. A 3-D computational fluid dynamics (CFD) model is developed to predict the motion of caustic liquor and bauxite particles through a tee-junction using an Eulerian-Eulerian continuum approach in conjunction with the k-epsilon turbulence model. Initial simulations assuming a uniform inlet flow are unable to demonstrate the cause of the observed erosion. However, subsequent modelling with a swirling inlet flow, based on a more thorough assessment of the upstream vessels and piping, results in the prediction of an accumulation of particles on the steel blank at the centre of a slow-moving vortex, the location of which is in excellent agreement with the observed wear on the plant. Furthermore, the predicted wear location is found to be insensitive to the assumed level of inlet swirl and the numerical scheme employed. The multiphase CFD model is also used to assess several potential solutions to the erosion problem, resulting in the replacement of the tee-junctions with a pivoting elbow design which is found to exhibit significantly reduced erosion rates on the plant. These results demonstrate the effectiveness with which CFD techniques can be used in the solution of industrial erosion problems. They also highlight the potential sensitivity of modelling results to inlet boundary condition assumptions and emphasise the need to adequately account for upstream influences when applying CFD techniques to the simulation of industrial flows. alpha 2002 Elsevier Science Inc. All rights reserved.