High pressure testing sand erosion in 3D flow channels and correlation with CFD

Abstract

An experimental approach to accelerated laboratory testing sand erosion in high pressure flow channels of complicated 3D configurations was developed. The channels were designed for erosion-resistant valves in natural gas and oil severe service applications. An analysis of equations of the particle motion in turbulent flow defined a method for scaling the channel dimensions, the erodent size and fluid parameters in order to simulate erosion in the field by using an environmentally-friendly fluid at the laboratory conditions. A testing facility that operated at 40 bar of nitrogen pressure with silica sand as an erodent was built and calibrated. The flow channels were manufactured from organic glass (PMMA) in separate plates that facilitated weight loss measurements in different parts of the channels as well as erosion visualization. The particular grade of glass was selected after testing erosion in a range of materials in order to find close resemblance to stainless steel in terms of both the erosion rate angle function and the velocity exponent. The test results were used for validation of a CFD model of the particles motion and for understanding the reliability of the CFD predictions for the valve lifetime assessment. The CFD model was found to reproduce the complicated erosion patterns and actual weight losses on early stages of erosion very well. CFD predictions were reasonably accurate even as erosion progressed if integral values of the computed erosion rate over the erosion scars were used.