Absorption-adsorption system for purifying cryogenic gases

• US 4,043,770 A
• Filed: 12/19/1975
• Issued: 08/23/1977
• Est. Priority Date: 12/20/1974
• Status: Expired due to Term

• Current Assignee: Linde AG (Linde Plc)
• Original Assignee: Linde AG (Linde Plc)
• Inventors: Jakob, Fritz
• Primary Examiner(s): Wyse, Thomas G.
• Assistant Examiner(s): Spitzer, Robert H.
• Application Number:
  US05/642,602
• Time in Patent Office: 613 Days
• Field of Search: 55/62, 55/73, 62/17, 62/18, 62/23
• US Class Current: 95/93
• CPC Class Codes: B01D 2256/16 Hydrogen
• CPC Class Codes: B01D 2257/502 Carbon monoxide
• CPC Class Codes: B01D 2257/702 Hydrocarbons
• CPC Class Codes: B01D 2259/40001 Methods relating to additional, e.g. intermediate, treatment of process gas
• CPC Class Codes: B01D 2259/402 using two beds
• CPC Class Codes: B01D 53/04 with stationary adsorbents B01D53/025 takes precedence
• CPC Class Codes: F25J 2200/70 Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
• CPC Class Codes: F25J 2200/76 Refluxing the column with condensed overhead gas being cycled in a quasi-closed loop refrigeration cycle
• CPC Class Codes: F25J 2205/04 in the feed line, i.e. upstream of the fractionation step
• CPC Class Codes: F25J 2205/30 using a washing, e.g. "scrubbing" or bubble column for purification purposes
• CPC Class Codes: F25J 2205/40 using hybrid system, i.e. combining cryogenic and non-cryogenic separation techniques
• CPC Class Codes: F25J 2205/60 using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
• CPC Class Codes: F25J 2245/02 Recycle of a stream in general, e.g. a by-pass stream
• CPC Class Codes: F25J 2270/02 Internal refrigeration with liquid vaporising loop
• CPC Class Codes: F25J 2270/24 Quasi-closed internal or closed external carbon monoxide refrigeration cycle
• CPC Class Codes: F25J 3/0223 H2/CO mixtures, i.e. synthesis gas; Water gas or shifted synthesis gas production of carbon monoxide containing gas in general C01B32/40, C10J, C10K; production of hydrogen containing gas C01B3/00
• CPC Class Codes: F25J 3/0233 separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0252 separation of hydrogen production of hydrogen containing gas in general C01B3/00, e.g. separation of hydrogen or hydrogen containing gases form gaseous mixtures at low temperatures C01B3/506
• CPC Class Codes: F25J 3/0261 separation of carbon monoxide production of carbon monoxide containing gas in general C01B32/40, C10J, C10K

Abstract

A semi-pure gas such as hydrogen containing a minor quantity of a gaseous impurity such as methane, is further purified by:

A. passing said semi-pure gas at a temperature substantially above the condensation temperature of said gaseous impurity through a first adsorber loaded with said gaseous impurity to desorb and entrain said gaseous impurity, thereby regenerating said first adsorber;

B. cooling resultant desorption gas containing said gaseous impurity to below the condensation temperature of said gaseous impurity to partially liquefy said gaseous impurity;

C. separating said liquefied gaseous impurity from equilibrium gas containing residual amounts of said gaseous impurity; and

D. passing said equilibrium gas through a second adsorber previously regenerated as in step (a), and removing at least a portion of said residual amounts of gaseous impurity to yield a purified gas.

Claims

1. In the purification of semi-pure gas containing a minor quantity of a gaseous impurity, the steps comprising:

a. passing said semi-pure gas at a temperature substantially above the condensation temperature of said gaseous impurity through a first adsorber loaded with said gaseous impurity to the extent of having a pressure of gaseous impurity emanating from the adsorbed impurity higher than the partial pressure of said gaseous impurity in the semi-pure gase, to desorb and entrain said gaseous impurity, thereby regenerating said first adsorber;

b. cooling resultant desorption gas containing said gaseous impurity to below the condensation temperature of said gaseous impurity to partially liquefy said gaseous impurity;

c. separating said liquefied gaseous impurity from equilibrium gas containing residual amounts of said gaseous impurity; and

d. passing said equilibrium gas, at a temperature below said condensation temperature of said gaseous impurity in step (b), through a second adsorber previously regenerated as in step (a), and removing at least a portion of said residual amounts of gaseous impurity to yield a purified gas.

2. A process according to claim 1, said pure gas being a hydrogen, said semi-pure gas being hydrogen-containing gas, and said gaseous impurity being methane.

3. A process according to claim 2, comprising the further steps of cooling a crude hydrogen-containing gas in indirect heat exchange relationship with purified hydrogen gas and scrubbing resultant cooled crude hydrogen-containing gas with liquid methane to yield scrubbed semi-pure hydrogen gas which is subjected to steps (a), (b), (c) and (d).

4. A process according to claim 3, said cooling in step (b) being conducted in indirect heat exchange with liquid carbon monoxide.

5. A process according to claim 4 wherein said scrubbed semi-pure hydrogen gas is heated in indirect heat exchange with gaseous carbon monoxide prior to step (a).

6. A process according to claim 5 comprising the further steps of passing said equilibrium gas from step (c) through a third absorber to cool same, and recooling said equilibrium gas prior to being subjected to step (d), said recooling being conducted in indirect heat exchange with liquid carbon monoxide.

7. A process according to claim 4 comprising the further steps of passing said equilibrium gas from step (c) through a third adsorber to cool same, and recooling said equilibrium gas prior to being subjected to step (d), said recooling being conducted in indirect heat exchange with liquid carbon monoxide.

8. A process according to claim 3 wherein said scrubbed semi-pure hydrogen gas is heated in indirect heat exchange with gaseous carbon monoxide prior to step (a).

9. A process according to claim 2, said cooling in step (b) being conducted in indirect heat exchange with liquid carbon monoxide.

10. A process according to claim 2, said temperature of said semi-pure gas in step (a) being at least 10°

C. above the methane condensation temperature.

11. A process according to claim 10, wherein the adsorption step (c) is conducted at a temperature 5°

to 60°

C. lower than the desorption step (a).

12. A process according to claim 10, wherein the adsorption step (c) is conducted at a temperature 10°

to 35°

C. lower than the desorption step (a).

13. A process according to claim 2, said temperature of said semi-pure gas in step (a) being at least 25°

to 45°

C. above the methane condensation temperature.

14. A process according to claim 1 comprising the further steps of passing said equilibrium gas from step (c) through a third adsorber to cool same, and recooling said equilibrium gas prior to being subjected to step (d).

15. A process according to claim 1, wherein the adsorption step (c) is conducted at a temperature 5°

to 60°

C. lower than the desorption step (a).

16. A process according to claim 1, wherein the adsorption step (c) is conducted at a temperature 10°

to 35°

C. lower than the desorption step (a).

17. In the purification of semi-pure gas containing a minor quantity of a gaseous impurity, the steps comprising:

a. scrubbing crude gas with liquid to yield scrubbed semi-pure gas containing said liquid in gaseous form as said gaseous impurity;

b. passing resultant semi-pure gas at a temperature substantially above the condensation temperature of said gaseous impurity through a first adsorber loaded with said gaseous impurity to the extent of having a pressure of gaseous impurity emanating from the adsorbed impurity higher than the partial pressure of said gaseous impurity in the semi-pure gas;

c. cooling resultant desorption gas containing said gaseous impurity to below the condensation temperature of said gaseous impurity to partially liquefy said gaseous impurity;

d. separating said liquefied gaseous impurity from equilibrium gas containing residual amounts of said gaseous impurity; and

e. passing said equilibrium gas at a temperature below said condensation temperature of said gaseous impurity of step (c) through a second adsorber previously regenerated as in step (b), and removing at least a portion of said residual amounts of gaseous impurity to yield a purified gas.

18. A process according to claim 17, said pure gas being hydrogen, said semi-pure gas being hydrogen-containing and said gaseous impurity being methane.

19. A process according to claim 18, said temperature of said semi-pure gas in step (b) being at least 10°

C above the methane condensation temperature.

20. A process according to claim 19, wherein at least about 40% of the methane is liquefied in step (c).

21. A process according to claim 19, wherein at lease 40 to 60% of the methane is liquefied in step (c).

22. A process according to claim 19, wherein the adsorption step (d) is conducted at a temperature 5°

to 60°

C. lower than the desorption step (b).

23. A process according to claim 19, wherein the adsorption step (d) is conducted at a temperature 10°

to 35°

C. lower than the desorption step (b).

24. A process according to claim 18, said temperature of said semi-pure gas in step (b) being at least 25°

to 45°

C. above the methane condensation temperature.

25. A process according to claim 17, wherein the adsorption step (d) is conducted at a temperature 5°

to 60°

C. lower than the desorption step (b).

26. A process according to claim 17, wherein the adsorption step (d) is conducted at a temperature 10°

to 35°

C. lower than the desorption step (b).