Solid Flux in a Circulating Fluidized Bed Riser

This work is aimed at exploring the flow structure of a gas-solid suspension in a circulating fluidized bed (CFB) riser. A cold model of a CFB 6.2 m high and 0.152 m diameter was used, with sand particles of 200 μm volume mean diameter and of density 2646 kg m−3 (i.e. Geldart B particle). A non-isokinetic sampling technique was used to explore the flow structure at five angular and three axial positions along the riser. Although a good symmetric profile of solid flux around the riser was found over a wide range of operating conditions, non-symmetric profiles were also observed. Some distinctive features of the radial profile of solid i.e. the existence of the peaks located around radial positions r/RT = ± 0.6 were found. Although some researchers attributed this peculiarity to the behaviour of Geldart A powder, in this work as well as in some others in the literature, this feature was found for sand particles belonging to Geldart B class.