Effects of fluid flow split on black powder distribution in pipe junctions

• Extreme fluid flow splits at junctions generate complex turbulent structures.
• Large particles undergo a slight settling effect with distance.
• High fluid flow rates in the branch entrain higher fractions of particles.
• Downward branches receive higher fractions of particles due to gravity.
• The general trend is altered due to the turbulent structures and particle settling.

In this study, CFD is used to investigate an important local phenomenon when populations of particles are split within junctions of gas piping networks. The particle-laden turbulent flow is studied using the k–ε turbulence model and the Discrete Phase Model DPM. The phase split is obtained for different working conditions including the effect of the particle diameter, the angle and the orientation of the branch. Particular attention is given to the effects of the flow rate of the gaseous phase when imposed at the outlets of the junction to replicate the flow control in real installations using valves.The fluid flow split yields different flow rate fractions in the two sides of the junctions which generates complex flow topologies affecting the solids split remarkably. The straight prolongation of the main pipe is called the main while the other side of the junction is the branch with different angles and orientations. Under extreme cases of fluid flow split, vortices form at the entrance of the main and alter the trend of solids split remarkably. In addition, large particles undergo a slight settling affecting their spatial distribution upstream of the junction which adds a degree of complexity to the solids split.

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