INVESTIGATION ON BUBBLE CHARACTERISTICS IN A GAS-FLUIDIZED BED

To characterize the bubble behavior in a fluidized-bed reactor experim ents were carried out with a capacitance probe. The probe consisted of two measuring tips with a distance of 10 mm. Cross correlation of the two time-averaged signals could not be used to determine the bubble r ising velocity because of the log-normal bubble Size distribution. The refore, a statistical method was developed to analyze and fit the expe rimentally determined time-averaged signals. Quartz sand powders with mean sieve particle sizes of 106, 165, 230 and 587 mu m were used as f luidizing powders. The theoretical equivalent bubble diameter calculat ed with the equation of Darton et al. (1977) was found to be about 2.7 times the determined radial averaged mean pierced bubble length. A st able bubble height h of about 60 cm was determined for the powder wit h an average particle size of 106 mu m. Combined with other data it is argued that h increases with increasing particle size. (C) 1997 Else vier Science Ltd.