Numerical investigation of a new technique to reduce pipeline elbow erosion employing branching path with flow control of butterfly valves and orifices

Abstract

A numerical erosion study was performed using Computational Fluid Dynamics (CFD) integrated with a Discrete Phase Model (DPM) on a standard 90° elbow, branch pipe elbow, and the effects of using a butterfly valve and orifice to control the flow. The butterfly control valve was studied at 20°, 40°, 60°, and 80° rotation angles around its axis, as well as at an orifice with a hole plate diameter of 20 %, 40 %, 60 %, and 80 % of the pipe diameter. In this study, the Euler-Lagrange approach was used to model two-phase flow with one-way coupling. After the fluid phase and non-spherical solid particles entered the pipe, the geometry erosion was calculated using the confirmed particle restitution model and erosion model. The numerical results showed that the branching pipe passes 30.9 % of the flow through the branching part, which reduces elbow erosion by 4.7 %. For this purpose, the use of the control valve and the orifice before the elbow increases the passage of the maximum two-phase flow of gas-particles up to 89.7 % and 96.4 %, respectively, in the branching path of the straight pipe. This leads to less impact of particles on the wall of the elbow compared to the complete passage of the flow in the path of the elbow. Therefore, the erosion damage in the elbow part of the branch pipe with 4 cases of the butterfly control valve is 61.1 %, 56.2 %, 24.7 %, and 4.5 % and the branch pipe with orifice 4 cases is 64.8 %, 54.9 %, 46.4 %, and 19.9 % compared to the normal state is reduced, which led to the improvement and replacement of the branching straight pipe path with only the elbow path.