CFD modeling of black powder particles deposition in 3D 90-degree bend of natural gas pipelines

Black powder deposition is the common problem in the natural gas transmission networks that occurs in some parts of the pipelines, especially in the bends. In this work, the flow of natural gas-particles was simulated within the Eulerian-Lagrangian framework in an industrial 90-degree bend based on the 3D computational fluid dynamics (CFD) tool. The shear stress turbulence (SST) model was applied to simulate the fully developed turbulent gas flow. The size range of the black powder particles was considered within 1-100 mu m with Stokes number (Stk) in the range of 0.001-11.25 to include the low and high inertia particles. The results showed that the penetration efficiency of the smaller black powder particles is higher than larger ones and follow the flow streamlines easily without significant deposition on the inner walls. In addition, the particle penetration efficiency in the bend curvature, is considerably less than other straight parts of the pipe, revealing that the particle deposition occurs significantly in those region. It was also observed that the penetration parameter is independent of the number of black powder particles. The effects of the natural gas flow velocity and pipe diameter size on the particle deposition were also investigated. According to the obtained results, increasing the gas flow velocity leads to a decrease in the particles penetration efficiency, consequently increase the particle deposition. The accuracy of the model verified via some available particle deposition data in the literature.