Experimental Investigation of Solid Particle Erosion in Successive Elbows in Gas Dominated Flows

When a fluid containing erosive particles flows through two or more elbows mounted in series with short distances between them, the downstream elbows which are installed after the first elbow are exposed to erosion from a flow that is not fully developed. Particle velocities and concentration distributions change due to change of flow direction within the first elbow which may cause the characteristics of erosive wear in the second elbow to be different than the first. In the present study, the erosion magnitude and pattern in two 4-inch standard successive elbows installed with 13D distance from each other are examined experimentally. Utilizing a state-of-the-art ultrasonic technique, erosion measurements are performed in gas-sand and gas-liquid-sand annular flows to investigate the effects of particle size and flow rates. A paint removal study is also performed to capture the erosion patterns in two elbows for different flow conditions. Using two clear elbows, a flow visualization is performed which shows the quality of phase distribution in the two elbows in series in annular and stratified flows. Erosion measurements show the results in the second elbow for this geometry and these flow conditions are less than or in a few cases nearly equal to the first elbow. The location of maximum erosion for all the cases considered is around 45 and 65 degrees from the inlet of the elbow in the first and second elbows, respectively. Two areas are identified in erosion patterns of both elbows. One high intensity particle impact region which is affected primarily by first impact of particles, and another pattern is formed due to impacting particles that have rebounded from the first impact.