Nonlinear dynamics of gas-solid circulating fluidized-bed system

Abstract

The nonlinear dynamics of a gas–solid circulating fluidized bed (CFB) was characterized by the correlation dimension and Kolmogorov entropy of time series of three different system variables with different spatio-temporal scales. Fluctuations of pressure, local bed voidage and heat transfer rate were simultaneously measured by a pressure transducer, an optical transmittance probe and a hot wire probe, respectively, at different axial and radial positions in the riser of 10 m height and 0.1 m i.d. The pressure fluctuation reflected the global hydrodynamic behavior of the CFB and was found to exhibit uniform distributions of the correlation dimension and the Kolmogorov entropy along the riser independent of the circulating solid flux. On the other hand, the correlation dimension and Kolmogorov entropy of local heat transfer and local voidage fluctuations significantly depended on circulating solid flux and axial and the radial positions, reflecting the small-scale spatio-temporal patterns of gas–solid flow induced by cluster and individual particle motions.