Sparged columns

In gas/liquid/solid sparged columns the situation is somewhat more complicated. Just as in gas/liquid systems, different regimes have to be distinguished. Here the most important variables affecting the axial dispersion coefficient Dc l of the liquid, are dc and uG ... 

Table 3. Liquid phase axial dispersion correlations for sparged columns.

Data on gas phase dispersion in three-phase sparged columns arc scarce. For two-phase systems a few correlations arc available [64, 67, 71, 72] which are shown... 

Table 4. Correlations for gas phase axial dispersion in sparged columns.

Fig. 2 Experimental technique to find the minimum gas velocity for particle suspension in gas-liguid-solids sparged columns.

The Re number, for energy dissipation by the gas phase, e.g., in sparged columns e = UQg, can be used in an equation similar to the Frbssling equation (Sano et al. [l26], SSnger and Deckwer [l27]). The latter authors proposed ... 

Minimum suspension criteria for solids in three phase stirred vessels can be related to those of the two phase stirred vessels. Data on three phase systems are relatively scarce, however. The same holds for three phase sparged columns. Moreover, in laboratory equipment with a large value of L/d it may be difficult to obtain a state of homogeneous particle distribution. More data on the influence of scale of operation on this phenomenon is required. 

Fig. 3. Bubble coalescence data obtained using an air sparged column for a selected range of electrolytes. Three of these electrolytes, HCl, NaClO and NaAcetate are deemed less inhibiting the remainder are called inhibiting.

---