Page 296 - Pressure Swing Adsorption

ii I.
272 PRESSURE SWING ADSORPTION
EXTENSIONS OF THE PSA CONCEPT
273

Compression
ADSORBENT
REGENERATOR
High pressure
flow
DISPLACER
PISTON

COLD
Expons1on

Low pressure
How
MORE ADSORBED \ FEED GAS
PRODUCT MIXTURE
FRACTION
LESS ADSORBED
PRODUCT
FRACTION
(a)
Pigure 7.5 Thermally coupled PSA process. (From Keefer\ with permission.) Net. result. Heol
Mor• odt<>rb•d ----~---
lroctlon L•o Od1orb4,d
Tl TZ lroct1on
(b)
tion. The more strongly adsorbed product 1s removed from the cold end of Figure 7.5 (ConJinued).
the system,. while the less adsorbed species 1s removed as product at the hot
end. The TCPSA system is thus seen to be similar to the pressure-ctriven heat rather than as m h .
1
parametric -pump but with a temperature gradient across the adsorbent bed. energy-effi - t ec amca energy. This Provides- the Potential for an
c1en and _cost-effective system powered by relatively low- rade
Heat and the more strongly adsorbed. component move to the cold end while
wast~d heat. The apphcat10n of a process of this kind to a reactmg syst!m to
the less-adsorbed species moves towards the hot end. The same effect can
:::v10; thcoenTt,CnuPoSuAs separation of the react10n products is an obVious exten-
also be accomplished using two 01stons operated out of phase [Figure 7.S(b)],
conceot.
as in the. ''molecular gate."
In addition to tt1e energy recovery that can be achieved through mechani-
7 ,2.1 Test Results
cal coupling of the compression and expansion steps, this system· also pro-
vides for efficient recovery of the heat of adsorption and offers the possibility Experimental data obta - d f h d .
that the additional energy required to drive the seoaration can be supplied as Ptoctuce oxygen) in a me II o: Y rogen ounficat1on arid air separation (to
sma laboratory TCPSA unit are summarized m
I