Premium
Comparative Study of Flow Structure in Circulating Fluidized Bed Risers with FCC and Sand Particles
Author(s) -
Qi X.B.,
Huang W.X.,
Zhu J.
Publication year - 2008
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.200700485
Subject(s) - nozzle , distributor , materials science , flow (mathematics) , particle (ecology) , fluidized bed combustion , mechanics , fluidization , range (aeronautics) , fluidized bed , composite material , geology , thermodynamics , physics , oceanography
The combined influences of particle properties and nozzle gas distributor design on the axial and radial flow structure in two 100 mm i.d., 15.1 m and 10.5 m long risers with FCC and sand particles were investigated by measuring the axial pressure gradient profiles, and the axial and radial profiles of solids concentration. The results show that the nozzle gas distributor design has significant 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, the upward gas‐solid flow of the sand particles decelerates in various degrees with the disappearing of the nozzle gas distributor effect. The upward gas‐solid flow of the FCC particles, however, occurs without noticeable deceleration within the range of this study. In the acceleration section, the radial distributions of the local solids concentration of the FCC particles are more uniform than those of sand particles under the same operating conditions; while in the fully developed zone, the sand particles have a more uniform radial distribution than the FCC particles. The gas‐solid flow is first developed in the center region, and then extends towards the wall. The overall flow development in the riser mainly depends on the local gas‐solid flow in the wall region.