The velocity and the axial dispersion of solids within a bed (50 mm in inner diameter, 3600 mm in height) with high gas velocity were analyzed by impulse response of tracer particles. FCC-particles (“group A” powder according to Geldart classification) were employed for the present investigation.
Local particle velocity at the axis of the bed increased with increased gas velocity, while the fraction of solids decreased. The axial dispersion coefficient within the bed ranged from 1 to 900 cm2/s. This result suggested unsteady and random behaviour of solids within the fast fluidized bed. Local slip velocity at the axis of the bed was mostly larger than the terminal velocity of a single particle.
1989 The Society of Chemical Engineers, Japan