Pneumatic transport of granular materials through a 90° bend

In the present study, a pneumatic conveying system incorporating a 90degrees bend is investigated. This study employs the use of three non-invasive instruments to measure solids concentration and velocity distribution determination in the pneumatic conveying system. They are namely the electrical capacitance tomography (ECT), particle image velocimetry and phase doppler particle analyzer. Pressure transducers were also used to monitor the pressure drop characteristics along the post-bend vertical pipe region. Two different classes of granular materials, polypropylene beads (2600 mum, Geldart class D) and glass beads (500 mum, Geldart class B), were used to investigate the differences in the flow characteristics for granular particles of various Geldart classes. The experimental results show a constant frequency pulsating flow for polypropylene beads in the dense-phase flow regime. This is illustrated by the visualization, ECT and pressure drop data. For dilute-phase flow regime, both polypropylene and glass beads show a continuous annulus flow structure. Numerical simulation using the Euler-Euler method was also conducted using computational fluid dynamics and the fluid and particle flow characteristics were compared with the experimental data obtained in the present study. (C) 2004 Elsevier Ltd. All rights reserved.