NUMERICAL ANALYSES OF THE EFFECTS OF BEND ORIENTATION ON SAND EROSION IN ELBOWS FOR ANNULAR FLOW

Sand erosion is a severe problem during the transportation of oil and gas in pipelines. The technology of multiphase transportation is widely applied in production, due to its high efficiency and low cost. Among various multiphase flow patterns, annular flow is a common flow pattern in the transportation process. During the transportation of oil and gas from the hydrocarbon reservoir to the final destination, the flow direction of the mixture in pipelines is mainly changed by the bend orientation. The bend orientation obviously changes the distributions of the liquid film and sand particles in annular flow, and this would further affect the sand erosion in elbows. Computational Fluid Dynamics (CFD) is an efficient tool to investigate the issues of sand erosion in multiphase flow. In the present work, a CFD-based numerical model is adopted to analyze the effects of bend orientation on sand erosion in elbows for annular flow. Volume of Fluid (VOF) method is adopted to simulate the flow field of annular flow, and sand particles in the flow field are tracked by employing Discrete Particle Model (DPM) simultaneously. Then, the particle impingement information is combined with the erosion model to obtain the maximum erosion ratio. The present numerical model is validated by experiments conducted in vertical-horizontal upward elbows. Finally, the effects of various bend orientations on the erosion magnitude are investigated according to the numerical simulations.