CFD study of sand erosion in pipeline

Abstract

Pipeline erosion remain a major headache for petroleum industry with its underlying safety threats and financial integrity. The main objective of this research paper is to investigate sand erosion behaviour in 76.2 mm diameter with Computational Fluid Dynamics (CFD). According to literature, simulation erosion by fine sand particles (<50 μm) tend overpredict the erosion result; transportation of sand particles in elbow are under the influence of fluid particles; slight altered geometries produce significantly different erosion results. Thus, CFD analysis with Eulerian-Lagrangian approach is utilised to solve continuous phase with Navier-Stokes equations, while secondary phase with particle force balance. Reynolds Stress Model along with low Reynolds number correction is used to model the turbulence behaviour of continuous fluid phase to address viscous boundary effect at near wall region and secondary flows in elbow for more accurate results. Validation results of this study shown that assumption of constant size for every sand particle led to more than 10% overprediction of maximum erosion rate. Overprediction had been successfully reduced to less than 5% by fitting actual size distribution of particle into Rosin Rammler equation to model the particle size. In addition, effect of sand size, flow orientation, elbow bending angle and fluid type were investigated. The following conclusion had been made: power law relationship observed between erosion rate and sand size; 30 μm particle produced a local maximum erosion at the trendline due to combination effect of sliding and direct collision; horizontal oriented flow shown asymmetric erosion behaviour due to effect of gravity; erosion with increasing elbow angle from 30° to 90° showed increasing erosion rate; water sand erosion was focused at the side of the elbow rather than the outer radius indicated erosion was highly dependent on carrier fluid properties.