Numerical simulation of solid-phase split at junctions in particle laden pipe flow

The present study is a part of an industrial research project and consists in simulating a gas-particle flow through junctions under different geometrical and flow conditions. The purpose is to study the effects of the size of particles, the angles of the junction and the flow rate on the flow split. The particles are usually considered as products to transport, such as in pneumatic conveying, where phase split, if necessary, is done in symmetrical Y-junctions to avoid mal-distribution issues. Thus, asymmetrical junctions were, usually, avoided in transportation networks. However, it appeared that the particles can manifest within networks for transportation of gases as contaminants to be eliminated. A typical example is that of Black Powder in gas pipelines in the oil industry. In such piping networks, different types of junctions can be used and it is worth understanding the behavior of particles for unsymmetrical configurations as well. The numerical simulation combines the k-ε and the Discrete Phase DPM turbulence and multiphase models, respectively. Relatively, good agreement in the results between the model and the experiments was obtained. The simulations were extended to Black Powder particles and the corresponding results showed interesting features for different Stokes numbers. The simulation results showed that, for Stokes numbers much smaller than unity (St≤0.2), the solids phase split can be considered to follow the air flow split closely. For intermediate Stokes numbers (St≈1), the particles gain some independence from the gaseous phase. For Stokes numbers slightly higher than unity (St≥5), the orientation plays an important role.