Numerical simulation of gas–solid flow in a conveying vessel

Conveying vessels, which are widely used in pneumatic systems, feature gas–solid flow with intensive inter-phase interactions and complex flow patterns. In this study, a two-fluid model was used to simulate flow behaviors in an experimental vessel. To model the gas phase, a k-ε turbulent model and the particle phase kinetic theory of granular flow were used. Three hydraulic stages were indicated: the rising, static and declining phases. Flow regimes similar to a spouted bed were formed near the wall, which became increasingly stable over time. Unstable flow regimes that consisted of bubbles and slugs were formed near the central part of the vessel. The velocity distributions of the gas and particles, the pressure profile and the secondary flow are described. A fitted curve of the output and input was obtained, and the influences of inlet conditions, such as velocity and pressure, were also investigated.

Graphical abstractThe pneumatic conveying of the powder in the vessel consists of the rising, static and declining phases. Time consumption decreases when the gas velocity at inlet increases, while it hardly changes when the pressure increases. The percentage of declining stage increases when gas velocity increases, which may explain the relatively low solid/gas ratio at high speed.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The process of pneumatic conveying of a novel pilot-conveying vessel was studied. ► The time consumption of the process with different operation condition was studied. ► The flow structure is similar to a combination of bubbling bed and spouted bed. ► The solid/gas ratio at the outlet will decrease if the gas velocity increases.