Dilute Gas-Solid Flows in Horizontal and Vertical Bends

Simulations of dilute-phase gas-solid flow in pipe bends of different radii of curvature were conducted using computational fluid dynamics (CFD). The renormalization group k-(epsilon) turbulence model was used for the flow calculations of the continuous phase while the Lagrangian approach was used for calculating the discrete-phase trajectory. The model predictions were first validated with particle concentration and velocity measurements adopted from the literature. Subsequently, the deposition pattern of fine particles in horizontal bends was compared with the model predictions. Other flow quantities such as secondary flow intensity and residence time distribution of the particles in the bend were also investigated. Simulation indicates that the rope formation in vertical bend is stronger for the longer bend radius than that in the shorter radius and inlet turbulence intensity (<10%) does not bring about significant effects on particle concentration through the bend whereas particle size is found to have the highest impact on the extent of flow dispersions observed in the bend with different radii of curvature.