Page 256 - Adsorption Technology & Design, Elsevier (1998)

Selected adsorption processes 231

tR

0 '~ ................ ,I' . Time
d=4o-

Figure 7.20 Gaussian elution signal obtained from an instantaneous pulse injection
(source: Villeremaux 1981, p. 114).

7.9 FUTURE DEVELOPMENTS

In view of the rapid growth in new patents for adsorption based processes, it
is not surprising that a number of new developments are being examined and
assessed prior to possible commercial application.
The first point to be made in this regard is in relation to the relative
rapidity of cycle times in pressure swing processes compared with those for
thermal swing processes. Further reduction in the cycle time of PSA
processes produces greater cycle efficiency with increased rates of produc-
tion of the desired component. Sircar and Hanley (1995) of Air Products and
Chemicals Inc., described a model rapid pressure swing adsorption (RPSA)
process in which the rates of adsorption and desorption were expressed in
terms of a linear driving force (q.v. Section 4.4) and equal times were
allocated to adsorption and desorption. The ratio of the net rate of
adsorption, R, to the steady state adsorption capacity, q*, was shown to be"

R/q* = ~ . 1 + e -k' ' (7.26)