Fractionators random dumped packings

Certainly, the hydraulic capacity limit of a packed bed has been reached when the rate of increase of pressure drop with gas flow rate approaches infinity. Likewise, the hydraulic capacity limit of a packed bed has been reached when the liquid holdup volume increases with gas flow rate to approach the void fraction of the bed. It has been demonstrated experimentally that both of the above phenomena occur at substantially the same gas rates in a bed of random dumped packing [10]. 

The Crawford-Wilke flooding correlation for liquid-liquid contactors is shown as Figure 11-7. The values for surface area and void fraction for commonly used random dumped packings are given in Tables 11-4, 11-5, and 11-6. The correlations to predict maximum capacity of liquid-liquid contactors do not provide the same degree of reliability as offered by correlations for gas-liquid columns. 

Void fraction when the packings are dumped at random in the towers. 

---