Numerical Investigation of Erosion Mitigation Method for Multiphase flow Pipelines

Abstract

Erosion which can lead to leakages, interruptions and expensive repairs is a major concern in piping systems. Design modification is a promising technique for mitigating erosion and extending the lifespan of piping systems. In this study, computational fluid dynamics (CFD) was used to explore the erosion behaviour of different elbow designs in the multiphase air-sand, and water-sand flows to identify the optimal elbow design for mitigation erosion. The elbow designs considered were the standard 90-degree elbow, the 18-degree gored elbow, the 22-5-degree gored elbow, and the 30-degree gored elbow. The results showed that the 22.5-degree gored elbow consistently decreased the erosion rate by 0.68 to 0.95 times (5-32%) across various flow conditions, indicating its potential for erosion mitigation in multiphase air-sand flows. The 18-degree and 30-degree gored elbows show less consistent results, with both erosion reduction and increase observed. In water-sand flows across all the operating conditions, the erosion rate of gored elbows was enhanced compared to the standard 90-degree elbow. The 30-degree gored elbow showed consistently worsened erosion, while the 18-degree gored elbow showed the least erosion increase relative to the baseline. The standard 90-degree elbow was the least effective at reducing erosion in air-sand flows, but it had the highest erosion resistance in multiphase water-sand flows. Regression analysis revealed that flow rate, air velocity, and elbow design significantly affected erosion rate in air-sand flow. The 22.5-degree gored elbow exhibited the highest erosion resistance, while the standard 90-degree elbow had the lowest resistance for the Oka erosion model. Conversely, in water-sand flow, elbow design had the most significant effect on erosion, followed by flow rate and water velocity, respectively. The standard 90-degree elbow has the highest erosion iv resistance, while the 30-degree gored elbow has the lowest erosion resistance. Sand size had minimal impact on the erosion rate in both flows.