Physical mechanisms involved in the transport of slugs during horizontal pneumatic conveying

In dense phase pneumatic conveying, only relatively small amounts of gas are used to transport large volumes of material. Because the complex physical mechanisms involved in the transport of high particle concentrations in a gas phase have still not been fully understood, the design of low velocity pneumatic conveying systems still remains a problem. This work focuses on the identification and description of the main physical mechanisms involved in horizontal slug flow pneumatic conveying. In particular, experimental investigations were carried out on slugs of granular material with respect to velocity, pressure profile, porosity and internal stress states. The results obtained lead to better comprehension of slug formation and stability. Besides, existing models for the prediction of the pressure loss in slug flow pneumatic conveying are reviewed and compared. Based on both experimental results and theoretical investigations, a new approach based on kinetic theory is proposed to predict the pressure loss and allow more reliable design of slug flow pneumatic conveying systems.