NUMERICAL EROSION PREDICTION COMPARING STANDARD AND VORTEX-CHAMBER ELBOWS

Carlos Antonio Ribeiro Duarte¹; Francisco de Souza²; Vinicius Fagundes dos Santos¹

¹ Universidade Federal de Uberlândia; ² José

Resumo

Erosive wear is usually a decisive factor for failure of pipelines plants. Industrial processes which require conveying of erosive particles are directly exposed to problems of contamination or leakage. As a result, unnecessary costs are needed by maintenance operations. This industrial concern is responsible for leading researchers to develop new pipe fitting geometries which can reduce the problem of erosion. With this in mind, the erosion prediction in both standard and vortex-chamber elbow with a 90-degree curvature angle are investigated numerically. In order to assess the quality of the numerical predictions of the erosion rate, experimental data were primarily used to validate the erosion and restitution models for the standard elbow, after that, these models were extended to the vortex-chamber elbow. The input parameters for the empirical erosion correlation were obtained from accurate CFD models for the gas-solid flow within the bend. Four-way coupling were evaluated for both elbows. In general, it was found that the effects of inter-particle collisions on the flow and on the penetration ratio cannot be disregarded. Another important finding is that the maximum penetration ratio on the vortex-chamber elbow reduces drastically when compared to standard elbow, indicating that the flow dynamics directly contributes to this reduction. The presence of the vortex chamber at the elbow reinforces the effect that has actually been observed in experiments and is named "cushioning effect". Based on the analysis of the simulation results, it can be concluded that a layer of particles actually protects the elbow from direct particle collisions. Conversely, the inter-particle collisions damps the erosion damage to the surface. This effect is present in many particle conveying systems and, for the vortex-chamber elbow, can be used as a positive mechanism.

Palavras-chave: Elbow Erosion; Vortex Chamber; Mass Loading; Inter-particle Collisions; Cushioning Effect