Dimension measurements of hydrodynamic attractors in circulating fluidized beds

Abstract

Experimental measurements of the correlation dimension, Kolmogorov entropy, and Lyapunov exponent of circulating fluidized bed (CFB) chaotic attractors were obtained by recording differential pressure and γ-ray porosity time series along the height of a cold experimental CFB operating with 75 μm diameter fluid catalytic cracking (FCC) catalyst. The attractor dimension did not vary with respect to the type of measurement taken. Both differential pressure and localized γ-ray densitometry measurements showed the existence of a low order hydrodynamic attractor, whose dimension varied between 1.5 and 2.0 over the range of gas velocities and solids fluxes studied. Differential pressure measurements indicated that the attractor dimension decreased slightly in the lower section of the CFB and at higher solids fluxes. Localized radial γ-ray bed porosity measurements indicate that the attractor dimension did not significantly vary across the bed cross-section but did show a tendency to be slightly lower near the riser wall.