Flow characteristics in a pilot-scale circulating fluidized bed with high solids flux up to 1800 kg/m² s

Comprehensive study on hydrodynamics is carried out in a pilot circulating fluidized bed riser of 18 m in height with high solids flux ranging from 800 to 1800 kg/m²s and superficial gas velocity of 5, 7 and 9 m/s. Results show that with such high solids flux, solids holdup can be up to 20–30% in the whole riser. When solids flux reaches up to1800 kg/m²s, both solids holdup and particle velocity become more uniform. Few down-flowing particles suggest reduced back-mixing at such operating conditions. Dynamic investigation shows that with high solids flux up to 800 kg/m²s, gas-solids fluctuation is almost the same with the circulating turbulent fluidized bed indicating good gas-solids contact. Therefore, riser reactors with high solids flux and gas velocity have great application potential for processes which usually need short reaction residence time with high capacity of both gas and solids.