GAS-DENSITY EFFECT ON MASS-TRANSFER IN THE SLURRY BUBBLE-COLUMN

Gas holdups and volumetric mass transfer coefficients were studied in a bubble column varying the gas density by a factor of up to 300. The gas density effect increased with the gas velocity. A maximum effect w as reached where the gas holdup (in water and in 0.8 M sodium sulfate solution) varied with the gas density to the power of 0.28. The corres ponding effect on the volumetric mass transfer coefficient k(L)a' was described with a power of 0.46. The same strong influence on k(L)a' ho lds also for highly viscous pseudoplastic xanthan gum solutions and co ncentrated slurries of kieselguhr (less than or equal to 12.5 vol%) an d alumina (less than or equal to 18 vol%). (C) 1997 Elsevier Science L td.