Numerical prediction of solid particle erosion under upward multiphase annular flow in vertical pipe bends

Solid particles entrained in the low liquid loading pipelines will cause pits or scratches on the pipe wall, and further lead to wall thinning or even leaks. Annular flow is a common flow pattern in pipeline. The particles in annular flow distribute in the liquid film and the gas core, and there are two existence forms for the solid particles in the gas core: wrapped in droplets and not be wrapped. In this paper, gas-particle slip was considered in a slip model in order to calculate the erosion of the particles wrapped in droplets in the gas core and a no-slip model was proposed to calculate the erosion of other particles in the gas core. The cushion effect of gas-liquid interface and the liquid film on the solid particles was equivalent to wall roughness. Finally, a simplified numerical simulation method considering the cushion effect and the gas-particle slip was developed to predict the erosion rate of vertical pipe bends. It is found that the predictions are in good agreement with the experimental data. The ratio of the solid particles wrapped in droplets to the total number of solid particles in the gas core is 0.626. Additionally, the relationship among liquid entrainment, erosion rate and liquid film thickness is investigated.