Abstract: Circulating fluidization, as an efficient and bubble-free contacting technology for gas and solid, is the research frontier of fluidization techniques. By a cold simulation apparatus with a riser of 10.6 m height and inner diameter of 100 mm, the effect of volume of pre-lifting gas as well as inlet jet gas on solid flux in circulating fluidized bed was studied. Especially, a comparative study of the solid flux with inlet nozzle at different positions as well as the difference of gas-solid flow behavior between region in the bottom and adjacent to nozzles was conducted. The gas distribution and flow structures in pre-lifting section in riser were described. The results show that pre-lifting gas and jet injection gas are the two important driving forces in pushing particles upward in riser. With the increase of jet inlet height, the effect of pre-lifting gas on solid flux becomes more obvious; the lower nozzle position shows the better performance in overall solid flux, solid holdup as well as gas-solid contact in nozzle region; Multiple gas countercurrent contact along with internal circulation flow as well as local vortex in bottom region of riser promote effectively the radial particle mixing and solid flux.

Key words: circulating fluidized bed, solid flux, nozzle, flow behavior