Process for purifying a synthesis gas
The present invention provides for a pressure swing adsorption (PSA) process for the substantial removal of H 2 O and CO 2 from a synthesis gas to obtain a multicomponent product gas substantially free of H 2 O and CO 2 with high recovery of the product gas. Further, the present invention provides an integrated process that achieves sufficiently high H 2 and CO recoveries such that compression and recycling of the syngas purification PSA tailgas is not necessary to be economically advantageous compared to the conventional processes.
1. An integrated process for the individual recovery of at least a purified H 2 -rich gas and a purified CO-rich gas from a hydrocarbon feedstock comprising:
a. introducing a hydrocarbon feedstock into a syngas generating unit and generating a superatmospheric pressure syngas stream consisting essentially of at least H 2 , CO, CH 4 , CO 2 , and H 2 O;
b. feeding the generated superatmospheric pressure syngas stream to a pressure swing adsorption (PSA)-based purification process unit to produce a superatmospheric pressure syngas stream substantially free of H 2 O and CO 2 ,
c. routing the superatmospheric pressure syngas stream substantially free of H 2 O and CO 2 to a separation system producing at least a H 2 -rich stream and a CO-rich stream; and
d. wherein the PSA-based purification process unit is purged with high-purity N 2 stream for a first portion of a purge phase and with H 2 -containing gas substantially free of H 2 O and CO 2 for a second portion of the purge phase.
2. The integrated process of claim 1 , wherein the syngas generation system is selected from a steam reformer, an autothermal reformer, or a partial oxidation reactor.
3. The integrated process of claim 1 , wherein the hydrocarbon feedstock is natural gas.
4. The integrated process of claim 1 , wherein the high-purity Na stream used during the first portion of the purge phase is generated by a cryogenic air separation unit.
5. The integrated process of claim 1 , wherein a portion of the superatmospheric pressure syngas stream substantially free of H 2 O and CO 2 obtained from the PSA-based purification process unit is used as the H 2 -containing gas during the second portion of the purge phase.
6. The integrated process of claim 1 , wherein a portion of a H 2 O and CO 2 free syngas stream originating in the separation system is used as the H 2 -containing gas during the second portion of the purge phase.
7. The integrated process of claim 1 , wherein a portion of the H 2 -rich product gas obtained from the separation system is used as the H 2 -containing gas during the second portion of the purge phase.
8. The integrated process of claim 1 , wherein the separation system is comprised of at least a cryogenic separation unit and a second PSA unit.
9. The integrated process of claim 1 , wherein the H 2 -containing gas during the second portion of the purge phase originates from within the PSA-based purification process unit.
10. The integrated process of claim 1 , wherein the separation system is comprised of at least membrane system for obtaining a purified H 2 -rich gas and a purified CO-rich gas.
11. The integrated process of claim 1 , wherein the waste gas from the pressure swing adsorption (PSA)-based purification process unit is used as a low-pressure fuel stream.
12. The integrated process of claim 1 , wherein the waste gas from the pressure swing adsorption (PSA)-based purification process unit is recycled to the syngas generation unit as a low-pressure fuel stream.
13. The PSA process of claim 4 , wherein the high-purity N 2 stream is extracted from a high-pressure column of the cryogenic air separation unit.
14. A PSA process for purifying a super-atmospheric pressure syngas stream containing at least H 2 , CO and CO 2 and H 2 O which comprises introducing a super-atmospheric pressure syngas stream to a pressure swing adsorption (PSA) process system having a plurality of adsorbent-containing beds that selectively remove substantially all H 2 O and CO 2 while discharging a super-atmospheric pressure syngas stream that is substantially free of H 2 O and CO 2 , wherein the PSA process system is purged with a high-purity N 2 gas stream substantially free of H 2 O and CO 2 for a first portion of a purge phase and with a H 2 -containing gas stream substantially free of H 2 O and CO 2 for a second portion of the purge phase.
15. The PSA process of claim 14 , wherein a portion of the superatmospheric pressure syngas stream substantially free of H 2 O and CO 2 obtained from the pressure swing adsorption (PSA)-based purification process unit is used as the H 2 -containing gas during the second portion of the purge phase.
16. The PSA process of claim 14 , wherein the H 2 -containing gas during the second portion of the purge phase originates from within the PSA-based purification process unit.
17. The PSA process of claim 14 , wherein the H 2 -containing gas during the second portion of the purge phase originates externally from the PSA process.