High pressure cyrogenic process and system for producing ammonia products

• US 8,889,093 B2
• Filed: 09/16/2010
• Issued: 11/18/2014
• Est. Priority Date: 09/16/2010
• Status: Active Grant

• Current Assignee: Kellogg Brown & Root LLC (KBR Incorporated)
• Original Assignee: Kellogg Brown & Root LLC (KBR Incorporated)
• Inventors: Malhotra, Avinash, Gosnell, James H., Jing, Yue
• Primary Examiner(s): Silverman, Stanley
• Assistant Examiner(s): BOVA, JUSTIN M
• Application Number:
  US12/883,743
• Publication Number:
  US 20120070364A1
• Time in Patent Office: 1,524 Days
• Field of Search: 252/372, 423/351, 423/359, 626/00, 629/31, 62617-620
• US Class Current: 423/359
• CPC Class Codes: C01B 2203/046 Purification by cryogenic separation
• CPC Class Codes: C01B 2203/068 Ammonia synthesis
• CPC Class Codes: C01B 3/506 at low temperatures
• CPC Class Codes: C01C 1/0405 from N2 and H2 in presence of a catalyst
• CPC Class Codes: F25J 2200/02 in a single pressure main column system
• CPC Class Codes: F25J 2200/72 Refluxing the column with at least a part of the totally condensed overhead gas
• CPC Class Codes: F25J 2210/20 H2/N2 mixture, i.e. synthesis gas for or purge gas from ammonia synthesis
• CPC Class Codes: F25J 2240/02 Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
• CPC Class Codes: F25J 2240/30 Dynamic liquid or hydraulic expansion with extraction of work, e.g. single phase or two-phase turbine
• CPC Class Codes: F25J 3/0219 Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature
• CPC Class Codes: F25J 3/0276 separation of H2/N2 mixtures, i.e. of ammonia synthesis gas in general C01B3/00
• CPC Class Codes: Y02P 20/52 using catalysts, e.g. selective catalysts

Abstract

Systems and methods for producing ammonia and/or ammonia products. The ammonia and/or ammonia products can be produced by compressing a gas mixture comprising nitrogen, hydrogen, methane, and argon to produce a compressed gas mixture having a pressure of from about 1,000 kPa (130 psig) to about 10,400 kPa (1,495 psig). All or a portion of the compressed gas mixture can be selectively separated at cryogenic conditions to produce a first gas comprising nitrogen and hydrogen, and a second gas comprising methane, argon, residual hydrogen and nitrogen. At least a portion of the first gas can be reacted at conditions sufficient to produce an ammonia product.

Claims

1. A method for producing ammonia, comprising:

methanating a gas comprising about 4 mol % to about 64 mol % nitrogen, about 35 mol % to about 95 mol % hydrogen, about 0.1 mol % to about 0.9 mol % carbon monoxide, and about 0.1 mol % to about 0.9 mol % carbon dioxide to produce a gas mixture comprising about 10 mol % to about 50 mol % nitrogen, about 55 mol % to about 75 mol % hydrogen, and about 0.5 mol % to about 10 mol % methane;

introducing the gas mixture to a compressor to produce a compressed gas mixture having a pressure of about 1,000 kPa to about 20,800 kPa, wherein the compressed gas mixture has the same composition as the gas mixture entering the compressor;

selectively separating the compressed gas mixture at cryogenic conditions to produce a first gas comprising about 10 mol % to about 40 mol % nitrogen and about 60 mol % to about 90 mol % hydrogen, and a second gas comprising about 5 mol % to about 30 mol % methane, about 1 mol % to about 10 mol % argon, residual hydrogen, and about 40 mol % to about 85 mol % nitrogen; and

reacting at least a portion of the first gas at conditions sufficient to produce an ammonia product.

2. The method of claim 1, wherein selectively separating all or a portion of the compressed gas mixture at cryogenic conditions comprises:

expanding at least a portion of the compressed gas mixture to produce a cooled gas mixture;

stripping at least a portion of the cooled gas mixture under a reflux to produce a purified gas mixture and a liquefied waste, wherein a first portion of the purified gas mixture is removed to produce the first gas;

expanding at least a portion of the liquefied waste to produce a cooled waste gas; and

condensing a second portion of the purified gas mixture using the cooled waste gas to produce the reflux and a warmed waste gas, and withdrawing at least a portion of the warmed waste gas to produce the second gas.

3. The method of claim 2, wherein at least a portion of the liquefied waste is expanded to produce mechanical energy.

4. The method of claim 3, further comprising generating electrical power using the mechanical energy.

5. The method of claim 1, wherein the hydrogen-to-nitrogen molar ratio of the first gas ranges from about 2.2:

1.0 to about 3.2;

1.0.

6. The method of claim 1, further comprising drying at least a portion of the gas mixture prior to compressing the gas mixture.

7. The method of claim 1, further comprising drying at least a portion of the compressed gas mixture prior to separating the compressed gas mixture.

8. The process of claim 1, further comprising drying at least a portion of the first gas prior to reacting at least a portion of the first gas at conditions sufficient to produce an ammonia product.

9. The process of claim 1, wherein the compressed gas mixture is cooled using at least a portion the first gas.

10. The process of claim 1, wherein the compressed gas mixture is cooled using at least a portion of the second gas.

19. The method of claim 1, further comprising:

converting one or more hydrocarbons in the presence of one or more oxidants and steam, to produce a first mixture comprising carbon dioxide, carbon monoxide, hydrogen, nitrogen, argon, water, and methane;

converting the first mixture in the presence of water, forming a second mixture comprising hydrogen, nitrogen, methane, argon, carbon dioxide and residual carbon monoxide; and

separating at least a portion of the carbon dioxide from the second mixture to provide the gas to be methanated.

20. The method of claim 1, wherein the compressed gas mixture has a pressure of from about 10,400 kPa to about 20,800 kPa.

11. A method for producing ammonia, comprising:

methanating a gas comprising about 4 mol % to about 64 mol % nitrogen, about 35 mol % to about 95 mol % hydrogen, about 0.1 mol % to about 0.9 mol % carbon monoxide, and about 0.1 mol % to about 0.9 mol % carbon dioxide to produce a gas mixture comprising carbon monoxide, carbon dioxide, about 10 mol % to about 50 mol % nitrogen, about 55 mol % to about 75 mol % hydrogen, and about 0.5 mol % to about 10 mol % methane;

introducing the gas mixture to a compressor to produce a compressed gas mixture having a pressure of about 1,000 kPa to about 20,800 kPa, wherein the compressed gas mixture has the same composition as the gas mixture entering the compressor;

selectively separating the compressed gas mixture to produce a first gas having a hydrogen-to-nitrogen molar ratio of from about 2.2;

1 to about 3.2;

1, and a second gas comprising about 1 mol % to about 10 mol % argon, about 40 mol % to about 85 mol % nitrogen, carbon monoxide, and carbon dioxide, wherein the selective separation occurs at a temperature of from about −

200°

C. to about 0°

C.; and

reacting at least a portion of the first gas at conditions sufficient to produce an ammonia product.

12. The method of claim 11, wherein selectively separating all or a portion of the compressed expanded gas mixture at cryogenic conditions to produce the first gas comprises:

expanding at least a portion of the compressed gas mixture to produce a cooled gas mixture;

stripping at least a portion of the cooled gas mixture under a reflux to produce a purified gas mixture and a liquefied waste, wherein a first portion of the purified gas mixture is removed to produce the first gas;

expanding at least a portion of the liquefied waste to produce a cooled waste gas; and

condensing a second portion of the purified gas mixture using the cooled waste gas to produce the reflux and a warmed waste gas, and withdrawing at least a portion of the warmed waste gas to produce the second gas.

13. The method of claim 12, wherein at least a portion of the liquefied waste is expanded to produce mechanical energy.

14. The method of claim 13, further comprising generating electrical power using the mechanical energy.

15. The method of claim 11, wherein the compressed gas mixture is cooled using at least a portion the first gas.

16. The method of claim 11, wherein the compressed gas mixture is cooled using at least a portion of the second gas.

17. The method of claim 11, further comprising drying at least a portion of the gas mixture prior to compressing the gas mixture.

18. The method of claim 11, further comprising drying at least a portion of the compressed gas mixture prior to cryogenically separating the compressed gas mixture.