mass transfer in multiphase systems - Greenleaf University

MASS TRANSFER IN MULTIPHASE SYSTEMS: VOLATILE ORGANIC COMPOUND
REMOVAL IN THREE-PHASE SYSTEMS
With the Henry’s Law constants and partition coefficients available, some interesting
predictions can be made, e.g., if the ratio H A /k D is large, meaning a volatile compound with small
affinity towards the solid, good separation is predicted and the converse is also true. The semivolatiles
like PCBs are poor candidates for the stripping process based on their large partition
coefficients and small Henry’s Law constants. Examining Eq. 43 it is seen that the so-called
stripping factor is similar to resistances, a mass transfer and an equilibrium resistance. It is
interesting to note that the partition coefficient is a factor of the mass transfer resistance.
Λ
A
1
s
1
PK aM k H
oa
s s D A
(42)
Of course, with no stripping air, the chief assumption is no longer valid and there is no net mass
transfer since:
X
A
X
(43)
i
A
In addition the ratio of the two stripping factors is instructive. The relation in Eq. 44 converges
to 1.0 as the particle size approaches zero and/or for very small k D ’s.
lim 1
(44)
D p 0
Therefore the methods within this paper are useful in assessing stripping viability in
solid-liquid-gas systems. The ratio shown in Eq. 44 could be used to estimate the time required
for a solids containing system compared to a known liquid system for example.
38