Separation of Air Components by Countercurrent and Co-Current Gas Permeation

stage cut θ

0.2

flow

countercurrent

co-current

This Demonstration studies enriching the oxygen content of air with a single-stage membrane module. This problem was first treated in [1] and later in [2 and 3]. The binary mixture,

A

(oxygen) and

B

(nitrogen), has an ideal separation factor

α=10

, the ratio of the permeabilities of the two species. The permeability of oxygen is



P

A

=500×

-10

10

3

cm

(STP)cms

2

cm

cmHg

). The membrane is more permeable to oxygen and has a thickness

t=2.54

-3

10

cm

. The stage cut,

θ

, is set by the user. The values of the pressures in the feed and permeate sides are chosen equal to

Ph=190

cmHg and

Pl=19

cmHg, respectively, which give a ratio of pressures,

r

, equal to 10. The feed rate and composition are given by

q

f

=

6

10

3

cm

(STP)/s

,

x

nitorgen

=0.791

, and

x

oxygen

=0.209

. This Demonstration computes the reject and permeate compositions as well as the membrane area for the countercurrent and co-current flow cases..