Environmental Engineering Reference
In-Depth Information
Table 7.2.2
Designing a membrane
CO
2
N
2
Knowns
Feed fl ux
Φ
F
Flue gas from the power
plant
Composition of feed
x
CO
2
,
F
1-
x
CO
2
,
F
Pressure of retentate
p
R
Our purchased pumps
and compressors
Pressure of permeate
p
P
Material property of our
membrane
Permeance of CO
2
P
CO
2
P
N
2
Unknowns
Stage cut
Θ
=
Φ
p
/
Φ
F
Area of the membrane
A
Design or optimization
parameters
Thickness of the
membrane
L
Composition of permeate
x
CO
2
,
P
1-
x
CO
2
,
P
Using the ratio
α
we can
eliminate an unknown
Composition of retentate
x
CO
2
,
R
1-
x
CO
2
,
R
(
x
CO
2
,
R
and
x
CO
2
,
P
, respectively). Hence, with three equations and fi ve
unknowns, in the next section we show how to further specify two of
these unknowns in our design (see
Table 7.2.2
).
In the remainder of this chapter, we will use the “
ideal separation
factor
.” The separation factor for a binary mixture is defi ned as:
x
/x
CO ,
P
N ,
P
α
=
2
2
CO ,
N
x
/x
22
CO ,
RNR
,
2
2
The numerator of this equation may be evaluated using equations given
above.
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