Page 357 - Pressure Swing Adsorption

334 PRESSURE SWING ADSORPTION 335
APPENDIX C
gas. The basic cycle consisted of pressunzat,on with feed, rinse and produc- mg of reformer recycle gas containing about 75% hydrogen, attaining an
tion of ennched light product, blowctown and recovery of the heavy compo- ultimate purity of 99.999% hydrogen and a recbvery of 80%, and usmg a
nent. They improved the ounty of the light comoonent by conducting the four-bed process with 5A zeolite or activated carbon as the adsorbent. The
oressunzation and rinse m discrete steos In sequential columns. More recent ooeratmg conditions included a pressure range of from 9.7 bar (145 osia) for
patents usually employ a different set of steps. That might make the resem- adsorption and 1 bar (15 psia) for desorpt10n and purging. A patent having
blance difficult to recognize. Nevertheless, a wide variety of other patents similar chams was awarded to Shell et al. in 1974. 52
4
i have borrowed, subtly modified, or reinvented the idea of rinse.'H'- "
I C.2.16 Batta
I C.2.12 Berlin Following up on Berlin's patent 8 for oxygen separatmn from air. another
I The first high-performance PSA oxygen generator was disclosed by Berlin tn applicat1on was filed by Batta that slightly improved the oxygen ountv. It did
8 49
l two applications filed tn 1963 and approved tn 1966-1967. • He claimed not amte match the former patent's recovery, but it employed a pressure
53
oxygen purities up to 93% (for which the balance was claimed to be 7% ratio of onlv about .1 rather than 50 for greater). It was awarded m 1973.
argon), al 53% recovery, but at a pressure ratio of 50 to 1000, and Ile The general concepts cla1mcd had been discovered earlier for other Hp~lica~
suggested a strontium-exchanged X zeolite as the adsorbent. t10ns. For examolc, he suggested a four~bcd process, cocurrcnt hlowdown.
and pressure eaualizatton. These ideas allowed an ultimate puntv of 95 to
96% oxygen and a recovery of 40 to 45% to be achieved, usmg 5A or 13X
C .2 .13 F eldbauer
zeolite as the adsorbent. The operatmg conditions included pressures of 3.2
Shortly after the patent application for PSA hydrogen purification was filed bar (47 osia) for adsorption to 1 bar (15 0s1a) for desorption and purging.
by Stark (see C.2.10), another was filed from the same company that further
extended the separation capability. In particular, Feldbauer filed in 1964 and
0
the patent was awarded in 1967.' The concepts also applied to upgrading of C.2.17 Fuderer and Rudelstorfer
reformer recycle gas, m the range of 40% hydrogen, to attam an ultimate U ntil the mid-1970s PSA systems had generally consisted of four parallel
'
M
.
punty of 96% hydrogen and a recovery of 94%, usmg 5A zeolite, activated beds or fewer. Fuderer and Rudelstorfer, m a patent awarded 111 l 976.
carbon, and/or activated aiumina as the adsorbent. The ooeratmg conditions changed all that with a system of as many as ten parallel beds. For that
mcludcct a oressure range of from 35 bar (500 osig) for adsorption and embodiment, the cycle comprised twenty steps, employing 54 timed valves,
1.4 bar (5 ps1g) for desorption and purging. although any individual column oniy underwent 11 separate steps. !h_eir
application was splitting hydrogen from 1mpunttes such as carbon d1ox1de
and nitrogen. They gave specific pressures, step ·ttmes. pressure ratios, and
C.2,14 Wagner
other process details.
Shortl.Y before the oatent fqr PSA hydrogen purification was awarded to
Stark in 1967, anoth-er patent was filed by Wagner (awarded in 1969 31 ) that
C.2.18 Munzner, Jiintgen, et al.
significantly extended the separnt1on capability. The concepts also applied to
upgrading of reformer recycle gas, using a four-bed process, with a feed of One of the most significant patents m the past 2 decades disclosed a process
about 77.1 % hydrogen and 22.5% CO with traces of other comoonents. The for seoaratmg nearly pure nitrogen from atr by exploiting a carbon molecuiar
2
process attamed an ultimate purity of 99.9999 + % hydrogen and a recovery sieve (CMS) adsorbent m which the diffusion rate differences of oxygen and
of 76.5%, using activated carbon and 5A zeolite as the adsorbents m a nitrogen were dramattc. The ongmal patent was granted m Germany m
compound bed. The operating conditions Included a pressure range of from 1976. 55 Patents were awarded to Munzner et al. m 1977 56 57 and to Jii~,tgen
·
13.4 bar (200 psia) for adsorption and 15 ps1a for desorption and purging. et al. 1981.'" which were assigned to Bcrgwerksverband GmhH. The idea, and
technology were no·t radically new, smce CMS had been introduced sepa~
rately in 1971, 59 and Skarstrom:: had already shown that kinetic seo~rat1ons
C.2. 15 Batta
were possible. The patent by Jiintgen et al., however, showed s1gmficantlv
After the patent application was filed by Wagner m 1967 for PSA hydrogen better performance than the system of Skarstrom: 99.9% mtrogen at a
purification, another was filed by Batta (awarded m 1971 51 ) that slightly recovery of about 40% versus 99% nitrogen at essentially nil recovery. A
nnproved the mherent recovery. Among the patented concepts were: upgrad-· schematic diagram of the process 1s shown m Figure C.4. It is instructive to
I