
86 Foam Fractionation: Principles and Process Design
5.5 Worked Example: Calculating the Nature
of Foam and Bubble Layers
Recall the worked example of Section 3.5 in which the hydrodynamic condi-
tion of a pneumatic foam was estimated. Under the conditions of μ=1.0mPa.s,
ρ
f
= 1,000 kg.m
−3
, j
g
= 8 mm.s
−1
, r
b
= 0.5 mm, and adopting typical values of the
foam drainage parameters, the liquid ux j
f
was estimated at 0.533 mm.s
−1
and the liquid fraction a relatively wet 0.137. We seek to calculate the liquid
fraction within the bubble swarm and the hindered bubble velocity. It will
be assumed that the liquid feed is added to the very bottom of the ...