Erosion Mechanics and Erosion Rate Prediction in Hydrate-Sand Slurry

Summary The complexity of pipeline systems and variable flow patterns in multiphase flow with hydrate particles (HPs) makes it challenging to understand and to mitigate erosion. Considering a sand-water flow erosion test in an elbow, a set of ice-sand-water erosion tests were conducted in a spinning slurry. The mass loss rate (LR) and erosion rate (ER) were compared with different test parameters. Furthermore, the ER of oil-gas-hydrate-sand slurry in four types of elbow (90° bend, 120° bend, V-bend, and N-bend) was predicted using a computational fluid dynamics (CFD) simulation software. The addition of 5% mass fraction of sand particles (SPs) significantly increased LR of ice slurry with a mixed flow speed of 500 rev/min. In the investigated cases, LR of Group B (ice-sand slurry) was 100 times higher than LR of Group A (ice slurry) on average. When the ice content was increased from 12.5% to 25%, the LR increased by 100%. A certain mass fraction of ice cubes also increased the LR of the sample in the sand-containing water flow. In general, as the ice concentration increased, the LR also increased. With an initial gas volume fraction φ of 10% to 25%, the flow patterns of slurry were simulated from layered flow in an elbow. Given the alternating transformation of bubbles and liquid columns, particles obtained more energy from the flow, resulting in higher ER and more eroded areas, especially in the N-bend. The 120° bend layout was the most erosion resistant among the tested bends, having the lowest ER average and an ER maximum at φ = 15–20%.