Page 334 - Pressure Swing Adsorption

310 PRESSURE SWING ADSORPTION APPENDIX A 311

By wnting tile same equation for component B, an eau1vaicnt l1ut not
Y,
identical expression 1s obtained, which can be solved fo.r the 1nterst1t1al
veiocity ahead of the shock wave m terms of the vei'oc1ty behind n. The result
t, t, ,s Ea. 4.8.

References

Y1NIT
I. H.-K. Rhee, R. Ans, and N. R. Amundson. First Order Part1al Diff'ererma! Equarwm. 1,
Prent1ce-Hall, Englewood Cliffs, NJ (1986).
z
2. A. Acnvos, "Method of Charactensttcs Technique," Ind. Eng. Chem. 48. 703-10 (1956).
(a/
.J. M. C. Bustos and F. Concha, "Boundary Conditions for the Conunuous Sedimentat10n of
Ideal Suspensions," A/Ch£ J. 38, 1135-38 (1992).
Y,
4. V. R. Dabholkar, V. Ba!ako1aiah, and D. Luss, '"Travelling Waves in Multi-Reaction
Systems," Chem. Eng. Sci. 43, -945-55 (1988).
z z, z,
5. A. KJuwick, "The Anatytical Method of Charactenst1cft," Prog. Aero.mace Sci. 19, 197-313
(1981).
6. R. Herman and I. Prigogme, "A Two Fluid Approach IO Town Traffic," Science 204. 148-51
(1979).
Y-!NIT

t
(b/
Figure A.I (a) Composition front for an adsorption step, shown as three instanta-
neous profiles, as It passes through an eiement of adsorbent. (b) Composition front
for an adsorption step, shown as histories recorded at three axial positions within the
adsorbent.

case, a matenal t>alance "around the front" 1s written m the same form as
Eq. 4.1

,(· APyA I + A,vPyA I]+ RT(l - e) AnA I ~ O (A.7)
Al ' AZ I, Al I,
where Al, represents the shift in a sliver observed at a specific time, and 6.lz
represents the shift over a motnent at a given position, and that d.yAi, =
-6.y)z, as shown m the figure. When that substitution is made and the
Ii definition of OA ts applied at constant pressure, the following equation for the
I shock veloc1ty, VsH• is obtained:
llzl
I VsH = tit a1• = OA AyA (A.8)
AvyA
I where the shift ,s taken with respect to position or time, but must be
consistent.

I