Experimental measurements of the correlation dimension, Kolmogorov ent
ropy, and Lyapunov exponent of circulating fluidized bed (CFB) chaotic
attractors were obtained by recording differential pressure and gamma
-ray porosity time series along the height of a cold experimental CFB
operating with 75 mu m diameter fluid catalytic cracking (FCC) catalys
t. The attractor dimension did not vary with respect to the type of me
asurement taken. Both differential pressure and localized gamma-ray de
nsitometry measurements showed the existence of a low order hydrodynam
ic attractor, whose dimension varied between 1.5 and 2.0 over the rang
e of gas velocities and solids fluxes studied. Differential pressure m
easurements indicated that the attractor dimension decreased slightly
in the lower section of the CFB and at higher solids fluxes. Localized
radial gamma-ray bed porosity measurements indicate that the attracto
r dimension did not significantly vary across the bed cross-section bu
t did show a tendency to be slightly lower near the riser wall.