Flow properties in the entrance and exit regions of a high-flux circulating fluidized bed riser

This work was carried out to study the three-dimensional flow properties in the entrance and exit regions under high-flux conditions by measuring particle velocity and solids concentration profiles in a 10-m-long and 76-mm-i.d. riser, with the solids circulation rate ranged up to 550 kg/m2 s and the superficial gas velocities ranged up to 10.0 m/s, mimicking the industrial high-flux riser reactors. Previous literature offers only a very limited knowledge of the detailed solids flow profiles immediately above the solids feeding level and below the exit at the riser top, all with low solids circulation rates of less than 200 kg/m2 s. The study of entrance and exit regions is very valuable for a better understanding of the solids distribution in the high-flux riser. Asymmetry of the radial profiles of solids concentration and particle velocity at both entrance and exit regions are observed under high-flux conditions. Such asymmetry is much stronger under high-flux conditions than under low-flux conditions.