Experimental and CFD investigations of 45 and 90 degrees bends and various elbow curvature radii effects on solid particle erosion

Abstract

Pipeline erosion damage results from solid particles entrained in produced fluids impacting the inner surface walls costing the oil and gas industry hundreds of millions of dollars per year. The failure of pipelines, especially elbows that change the flow direction, is caused mainly by particles that cross the streamlines of flow, impacting pipe bends at high flow velocities. The purpose of this paper is to investigate alternative geometries to standard 90° elbows, where the ratio of elbow curvature radius to the pipe diameter is equal to 1.5 (r/D = 1.5). Paint removal study using water-sand and water-air-sand flows were performed in three 50.8 mm pipe diameter elbows: 90° elbow with a curvature radius of 2.5D and 5D, and a 45° elbow with a curvature radius of 1.5D. The paint study has been used to examine the location of maximum erosion and erosion patterns. In addition, computational fluid dynamics (CFD) simulations were conducted for three different 90° elbows with curvature radii of r/D = 1.5, 2.5, and 5 and a 45° bend with a curvature radius of 1.5D. The numerical simulations were compared with experimental paint removal studies in acrylic elbows. Good agreement has been observed between CFD and experiments for both erosion pattern and location of maximum erosion. Furthermore, the CFD results show that the erosion rate decreases with increasing elbow curvature radius, there is an erosion reduction of 66% when r/D is increased from 1.5 to 5, and it was found that the 45° bend presented approximately two times less erosion than the 90° elbow.