NUMERICAL AND EXPERIMENTAL INVESTIGATIONS OF THE EFFECT OF DISTANCE BETWEEN TWO ELBOWS IN SERIES IN GAS-SOLID FLOWS ON SOLID PARTICLE EROSION

Elbows are important fitting components used to change the flow direction, and they are widely used in pipeline and transport systems. In this work, an experimentally validated Computational Fluid Dynamic (CFD) approach is used to investigate the erosion prediction in gas-solid flows in 3-inch (76.2 mm) standard elbows (r/D = 1.5). The length between the two elbows varies from 2 to 50 times the pipe diameter. First, a mesh independence study was performed to minimize the uncertainty related to the mesh size on erosion predictions in elbows. Second, different erosion models that are available in the literature are utilized for erosion calculations. The presented CFD results are compared with experimental data collected for 76.2 mm elbows. In addition, CFD investigations were performed for gas-solid flow in a high-pressure condition to study the effect of distance between the two elbows in series. The CFD results showed that, for gas-solid flows in low-pressure conditions, the erosion in the first elbow is always higher than the second elbow in a wide range of distances between the two elbows in series with 31 m/s of gas velocity and 300 mu m particle size. The CFD results are compared to the experimental data with 2 and 12D distance between the two elbows with 300 mu m particle size. The results of high-pressure conditions showed that erosion in the second elbow is higher than the first elbow with a 2D distance between the two elbows, and the magnitude of the maximum erosion ratio in the second elbow decreases with increasing the distance between the two elbows.