Adsorption processes with intermediate product recovery using two adsorption zones

• US 5,106,396 A
• Filed: 12/03/1990
• Issued: 04/21/1992
• Est. Priority Date: 12/28/1989
• Status: Expired due to Fees

• Current Assignee: Telephone Products Incorporated
• Original Assignee: Michael J. Mitariten
• Inventors: Mitariten, Michael J.
• Primary Examiner(s): SPITZER, ROBERT H
• Application Number:
  US07/620,999
• Time in Patent Office: 505 Days
• Field of Search: 55/25-28, 55/62, 55/68, 55/74, 55/75, 55/33, 55/73
• US Class Current: 95/99
• CPC Class Codes: B01D 2253/102 Carbon
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2256/16 Hydrogen
• CPC Class Codes: B01D 2256/20 Carbon monoxide
• CPC Class Codes: B01D 2257/104 Oxygen
• CPC Class Codes: B01D 2257/502 Carbon monoxide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/7025 Methane
• CPC Class Codes: B01D 2257/80 Water
• CPC Class Codes: B01D 2259/40001 Methods relating to additional, e.g. intermediate, treatment of process gas
• CPC Class Codes: B01D 2259/40015 with two sub-steps
• CPC Class Codes: B01D 2259/4003 with two sub-steps
• CPC Class Codes: B01D 2259/40037 with two sub-steps
• CPC Class Codes: B01D 2259/40045 with two sub-steps
• CPC Class Codes: B01D 2259/40052 Recycled product or process gas
• CPC Class Codes: B01D 2259/40056 Gases other than recycled product or process gas
• CPC Class Codes: B01D 2259/40066 Six
• CPC Class Codes: B01D 2259/40067 Seven
• CPC Class Codes: B01D 2259/40071 Nine
• CPC Class Codes: B01D 2259/40081 Counter-current
• CPC Class Codes: B01D 2259/4009 : using hot gas
• CPC Class Codes: B01D 2259/402 : using two beds
• CPC Class Codes: B01D 2259/403 : using three beds
• CPC Class Codes: B01D 2259/4061 : using five beds
• CPC Class Codes: B01D 53/0462 : Temperature swing adsorption
• CPC Class Codes: B01D 53/261 : by adsorption
• CPC Class Codes: Y02C 20/20 : of methane
• CPC Class Codes: Y02C 20/40 : of CO2

Abstract

Adsorption processes are provided for the separation of a feedstream containing less readily, intermediately, and more readily adsorbable components using first and second adsorption zones. The second adsorption zone utilizes a cycle that includes a cocurrent displacement step and the intermediately adsorbable components are recovered therefrom by countercurrent depressurization. The first adsorption zone is purged with a stream from the second adsorption zone to recover the more readily adsorbable components. The processes are particularly suitable for recovering carbon monoxide from feedstreams containing hydrogen, carbon monoxide and other compounds such as methanol and higher alcohols, methane, dimethyl ether, dimethyl ketone, water, carbon dioxide, oxygen and mixtures thereof. The processes are particularly applicable to methanol reforming processes wherein hydrogen and carbon monoxide product streams are recovered from a methanol reactor effluent stream also containing components selected from methanol, methane, dimethyl ether, carbon dioxide, oxygen and water.

Claims

1. An adsorption process for the separation of a feedstream containing a less readily adsorbable component, an intermediately adsorbable component and at least one more readily adsorbable component, with recovery of the intermediately adsorbable component as a desired product, in an integrated adsorption system having first and second adsorption zones arranged in series, said process comprising the following process steps:

a) passing the feedstream to the first adsorption zone at a first zone adsorption pressure and temperature in which the at least one more readily adsorbable component is adsorbed, and recovering a first zone adsorption effluent stream depleted in the at least one more readily adsorbable component relative to the feedstream;

b) passing the first zone adsorption effluent stream to the second adsorption zone maintained at a second zone adsorption pressure in which the intermediately adsorbable component is adsorbed, and recovering a second zone adsorption effluent stream comprising the less readily adsorbable component and depleted in the intermediately adsorbable component relative to the feedstream;

c) cocurrently displacing the less readily adsorbable component contained within said second adsorption zone with a displacement gas having a concentration of the intermediately adsorbable component which is higher than that of the feedstream and recovering a displacement effluent stream comprising the less readily adsorbable component;

d) heating the first adsorption zone to a first zone desorption temperature that is higher than the first zone adsorption temperature by passing a heated purge gas comprising at least a portion of the displacement effluent stream from the second adsorption zone comprising the less readily adsorbable component through the first adsorption zone and recovering a first zone purge effluent stream comprising the at least one more readily adsorbable component; and

e) countercurrently depressurizing the second adsorption zone to a second zone desorption pressure that is at or above atmospheric pressure and recovering a second zone desorption effluent stream enriched in the intermediately adsorbable component relative to the feedstream.

2. The process of claim 1 further comprising the step of cocurrently depressurizing the second adsorption zone to a second zone cocurrent depressurization pressure either before, simultaneously with, or after cocurrently displacing the less readily adsorbable component contained within the second adsorption zone, and recovering a second zone cocurrent depressurization effluent stream comprising the less readily adsorbable component.

3. The process of claim 2 wherein the heated purge gas comprises at least a portion of the second zone cocurrent depressurization effluent stream.

4. The process of claim 1 wherein the heated purge gas comprises at least a portion of the second zone adsorption effluent stream, the displacement effluent stream or mixtures thereof.

5. The process of claim 1 wherein the temperature of the heated purge gas is from about 100°

to 700°

F.

6. The process of claim 1 further comprising the step of countercurrently depressurizing the first adsorption zone to a first zone desorption pressure that is at or above atmospheric pressure and recovering a first zone desorption effluent stream comprising the at least one more readily adsorbable component.

7. The process of claim 1 further comprising the step of cocurrently depressurizing the second adsorption zone to provide an equalization gas for repressurizing an adsorber bed in the second adsorption zone.

8. The process of claim 1 wherein the first adsorption zone comprises at least two adsorber beds.

9. The process of claim 1 wherein the second adsorption zone comprises at least three adsorber beds.

10. The process of claim 1 wherein the less readily adsorbable component is hydrogen.

11. The process of claim 10 wherein the intermediately adsorbable component is carbon monoxide.

12. The process of claim 11 wherein the at least one more readily adsorbable component comprises compounds selected from the group consisting of methanol, methane, dimethyl ether, dimethyl ketone, water, carbon dioxide, oxygen and mixtures thereof.

13. An adsorption process for the separation of a feedstream containing hydrogen, carbon monoxide and at least one other component selected from the group consisting of methanol, methane, dimethyl ether, dimethyl ketone, carbon dioxide, oxygen, water and mixtures thereof, in an integrated adsorption system having first and second adsorption zones arranged in series, said process comprising the following process steps:

a) passing the feedstream to the first adsorption zone at a first zone adsorption pressure and temperature in which the at least one other component is adsorbed and recovering a first zone adsorption effluent stream comprising hydrogen and carbon monoxide;

b) passing the first zone adsorption effluent stream to the second adsorption zone at a second adsorption zone pressure in which carbon monoxide is adsorbed, and recovering a second zone adsorption effluent stream comprising hydrogen;

c) cocurrently displacing hydrogen contained within the second adsorption zone with a displacement gas having a concentration of carbon monoxide which is higher than that of the feedstream, and recovering a displacement effluent stream comprising hydrogen;

d) cocurrently depressurizing the second adsorption zone to a second zone equalization pressure to provide an equalization gas;

e) further cocurrently depressurizing the second adsorption zone to a second zone blow-down pressure to provide a provide-purge gas comprising hydrogen;

f) countercurrently depressurizing the second adsorption zone to a second zone desorption pressure that is at or above atmospheric pressure and recovering a second zone desorption effluent stream comprising carbon monoxide;

g) countercurrently purging the second adsorption zone with a first purge gas comprising hydrogen and recovering a second zone purge effluent stream comprising carbon monoxide;

h) partially repressurizing the second adsorption zone by introducing the equalization gas therein until the pressure is approximately equal to the second zone equalization pressure;

i) further repressurizing the second adsorption zone to the second zone adsorption pressure;

j) heating the first adsorption zone to a first zone desorption temperature that is higher than the first zone adsorption temperature by passing a second purge gas comprising at least a portion of the displacement effluent stream from the second adsorption zone comprising hydrogen through the first adsorption zone at an elevated temperature and recovering a first zone purge effluent stream comprising the at least one other component; and

k) cooling the first adsorption zone to the first zone adsorption temperature.

14. The process of claim 13 wherein the first zone adsorption pressure is from about 100-500 psig.

15. The process of claim 14 wherein the second zone adsorption pressure is from about 100-500 psig and is approximately equal to the first zone adsorption pressure.

16. The process of claim 14 wherein the first zone adsorption temperature is from about 0°

to 400°

F.

17. The process of claim 14 wherein the first zone desorption temperature is from about 100°

to 700°

F.

18. The process of claim 14 further comprising the step of countercurrently depressurizing the first adsorption zone to a first zone desorption pressure that is at or above atmospheric pressure and recovering a first zone desorption effluent stream comprising at least one more readily adsorbable component.

19. The process of claim 18 wherein the first zone desorption pressure is from about 0-50 psig.

20. The process of claim 13 wherein the displacement gas comprises at least one of the second zone desorption effluent stream or the second zone purge effluent stream.

21. The process of claim 20 wherein the displacement gas is compressed to approximately the second zone adsorption pressure prior to displacing hydrogen from the second adsorption zone.

22. The process of claim 21 wherein the second zone equalization pressure is from about 75-250 psig.

23. The process of claim 22 wherein the second zone blow-down pressure is from about 30-100 psig.

24. The process of claim 23 wherein the second zone desorption pressure is from about 0-50 psig.

25. The process of claim 13 wherein the feedstream comprises from about 50-80 mol. % hydrogen, from about 10-40 mol. % carbon monoxide and from about 1-10 mol. % of the at least one other component.

26. The process of claim 13 wherein the second zone adsorption effluent stream and the second zone displacement effluent stream combined have a product purity of at least 85 mol. % hydrogen.

27. The process of claim 26 wherein the second zone desorption effluent stream and second zone purge effluent stream combined have a product purity of 95 mol. % carbon monoxide.

28. The process of claim 13 wherein the first adsorption zone contains at least three adsorber beds and the second adsorption zone contains at least five adsorber beds.