Chemical Engineering & Technology, Vol.27, No.7, 769-776, 2004
Radial particle profiles in a liquid-solid CFB with varying viscosity
Flow structure was characterized in a 76 mm diameter by 2.0 m high liquid-solid circulating fluidized bed (LSCFB) with different viscous liquids ranging from 1.0 mPa(.)s to 4.8 mPa(.)s. Measurements of mean and local solids holdup were carried out in the axial and the radial direction, respectively. The results showed that a uniform axial and a nonuniform radial distribution of the time-averaged solids holdup appeared in the LSCFB. The viscosity of the liquid phase reduces the nonuniform distribution of solid particles in the radial direction. By examining the instantaneous data signals, flow behavior in a viscous system was found to be more uniform and less vigorous. To further understand the hydrodynamics in a LSCFB, Hurst's resealed range (R/S) analysis was also adopted to analyze its stochastic characteristics and the local flow properties.