Numerical simulation for erosion effects of three-phase flow containing sulfur particles on elbows in high sour gas fields

Abstract

Sulfur particles carried by high-speed flow impact pipelines, which may cause equipment malfunctions and even failure. This paper investigates the scouring effect of mist gas containing sulfur particles on elbows in highly sour gas fields. The multiphase-flow hydrodynamic model of the 90° elbow was established by using the computational fluid dynamics (CFD) method. The scouring effects of the gas-liquid mist fluid with the water-liquid fraction of 20% and particles with the diameter of 0.01–0.05 mm on elbows were explored within the flow velocity range of 0–20 m/s. In addition, the influences of secondary collision, mean curvature radius to diameter (R/D) ratio, inertial force, drag force, and Stokes number on trajectories of sulfur particles were studied. Moreover, the influences of hydrodynamic parameters of multiphase flow on corrosion inhibitor film were analyzed with the wall shear stress as the reference value. Serious erosion mainly occurred in the extrados of elbow as well as the junction between downstream pipeline and the intrados of elbow, the maximum erosion area occurs at 61.9°. When the incident position of the particle was far away from the top of the inlet plane, the probability of secondary collision became smaller. Furthermore, the erosion rate decreased with the rise in the R/D radio. The maximum erosion rate of elbow increased with the increase in the Stoke number. The maximum erosion rate reached 0.428 mm/a at 0.05 mm particle diameter and 20 m/s fluid velocity. The wall shear stress increased with the increase in fluid velocity and mass flow rate of particle, the fitting function of the wall shear stress curve was the Fourier type. The results indicated that high-velocity particles had a serious erosion effect on elbows and affected the stability of the corrosion inhibitor film. The erosion effect could be retarded by controlling the velocity and diameter of particles. The results provided technical supports for the safe production in highly sour gas fields. Keywords: Sour gas field, Elbow, Sulfur particle, Trajectory, Erosion, Numerical simulation