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increase in Apo will affect the liquid flow only slightly; however, if ApL is small compared to Apo, a small increase in Apo will make a large percentage decrease in ApLy causing the holdup to increase and the tower to flood.

Combining the pressure-drop equations,

Setting the ratio (pL — ApG)/Apo equal to b and noting that at flooding Ap0 becomes approximately equal to pL modifies the previous equation to give

At low values of (ug/ul)2pv/pl, the denominator of the right-hand side becomes 1, and the limiting gas velocity is a function of {uq/ul){pv/pl), the tower dimensions, and fL, the latter term being chiefly a function of \xh. It is interesting to note that in this region the gas viscosity is not a factor; but when the last term of the denominator is not negligible, the viscosity of the gas becomes a factor in the limiting gas velocity.

At very high values of this group, the right-hand side reduces to/<?.

Table 16-2

Packing

System

Reference

No. 19 aluminum jack chain .

Heptane-methyl cyclohexane

Air-water

Air-water

Air-water

H2-water

Air-water

COrwater

Air-water

Air-methanol

Water + butyric acid-air Benzene-carbon tetrachloride Benzene-carbon tetrachloride Benzene-carbon tetrachloride Ethanol-water

Quinoline (distillation at 10 mm. Hg abs.)

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