Combination effect of nozzle gas distributor and particle properties on gas-solid flow behaviors in CFB risers

The influence of nozzle gas distributor design on the axial and radial flow structure for FCC and sand particles was investigated in two 100 mm i.d., 15.1 m and 10.5 m long risers with nozzle gas distributor separately by measuring axial pressure gradient profiles, axial and radial profiles of solids holdup. Results show that the nozzle gas distributor design has different effects on the axial and radial flow structure for the FCC and sand particles. At lower superficial gas velocity of less than 8.0 m · s^-1, the upward gas-solid flow of the sand particle decelerates to various degrees with the disappearance of nozzle gas distributor effect. The upward gas-solid flow of the FCC particles, however, does not have noticeable deceleration although the nozzle gas distributor design is also used. It is also found that, when the nozzle gas distributor is employed, the radial distributions of local solids holdup of the FCC particles in the acceleration section are more uniform than those of sand particles under the same operating conditions; while in the fully developed zone, the radial distributions of local solids holdup of the sand particles are more uniform than those of the FCC particles under the same operating conditions.