ENTRAINMENT OF FCC FROM FLUIDIZED-BEDS - A NEW CORRELATION FOR THE ELUTRIATION RATE CONSTANTS K-I-INFINITY-ASTERISK

Batch and continuous experiments of fluidization have been carried out in columns of diameter 76 and 152 nlm. Gas velocities of 0.1-0.8 m/s were used with mixtures of coarse and fine FCC as the feed materials. The total entrainment nux E-Z and the elutriation rate constants K-i i nfinity are found to depend on the gas velocity in the form of E-Z pr oportional to U-n and K-i infinity proportional to U-m, respectively. The values of n and m depend on the bed compositions and particle siz e; they become smaller at higher gas velocities. For FCC, ii has an av erage value of 4.0 in the velocity range 0.2-0.4 m/s and tends to a va lue of 2 at higher gas velocities. The effect of column diameter depen ds on the gas velocity profiles and is reduced for column diameters ab ove 0.1 m. Empirical correlations to predict K-i infinity and E-Z hav e been developed from the results. (C) 1998 Elsevier Science S.A.