Methods and systems for making ammonia in a double ammonia converter system

• US 9,643,856 B2
• Filed: 08/05/2014
• Issued: 05/09/2017
• Est. Priority Date: 08/07/2013
• Status: Active Grant

• Current Assignee: Kellogg Brown & Root LLC (KBR Incorporated)
• Original Assignee: Kellogg Brown & Root LLC (KBR Incorporated)
• Inventors: Singh, Shashi Prakash, Nahar, Akhil Jain, Noe, Stephen Allen
• Primary Examiner(s): LANGEL, WAYNE A
• Application Number:
  US14/452,469
• Publication Number:
  US 20150044121A1
• Time in Patent Office: 1,008 Days
• Field of Search: None
• CPC Class Codes: B01J 19/00 Chemical, physical or physico-chemical processes in general; Their relevant apparatus
• CPC Class Codes: C01B 2203/0233 the reforming step being a steam reforming step
• CPC Class Codes: C01B 2203/0283 containing a CO-shift step, i.e. a water gas shift step
• CPC Class Codes: C01B 2203/043 Regenerative adsorption process in two or more beds, one for adsorption, the other for regeneration
• CPC Class Codes: C01B 2203/0445 Selective methanation
• CPC Class Codes: C01B 2203/047 the impurity being carbon monoxide
• CPC Class Codes: C01B 2203/0475 the impurity being carbon dioxide
• CPC Class Codes: C01B 2203/068 Ammonia synthesis
• CPC Class Codes: C01B 2203/141 At least two reforming, decomposition or partial oxidation steps in parallel
• CPC Class Codes: C01B 2203/142 At least two reforming, decomposition or partial oxidation steps in series
• CPC Class Codes: C01B 2203/143 Three or more reforming, decomposition or partial oxidation steps in series
• CPC Class Codes: C01B 2203/146 At least two purification steps in series
• CPC Class Codes: C01B 3/025 Preparation or purification of gas mixtures for ammonia synthesis
• CPC Class Codes: C01B 3/12 by reaction of water vapour with carbon monoxide
• CPC Class Codes: C01B 3/38 using catalysts
• CPC Class Codes: C01C 1/04 Preparation of ammonia by synthesis in the gas phasepreparation or purification of gas mixtures for ammonia synthesis C01B3/025
• CPC Class Codes: C01C 1/0405 from N2 and H2 in presence of a catalyst
• CPC Class Codes: C01C 1/0458 Separation of NH3 during purge gas treatment C01C1/0476
• CPC Class Codes: Y02P 20/129 Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
• CPC Class Codes: Y02P 20/52 using catalysts, e.g. selective catalysts

Abstract

Methods and systems for making ammonia are provided. The method can include heating a first compressed syngas to produce a heated first syngas. The heated first syngas and a second compressed syngas can be combined to produce a combined syngas. The combined syngas can be reacted within a first ammonia converter and a second ammonia converter to produce an ammonia product. Heat from the ammonia product can be transferred to a first heat transfer medium to produce a first cooled product and a second heat transfer medium. Heat from the first cooled product can be transferred to a third heat transfer medium to produce a second cooled product. Heat from the second cooled product can be transferred to the combined syngas to produce a third cooled product. The third cooled product can be separated to produce a purified ammonia product and a recycle gas.

Claims

1. A method for producing ammonia, comprising:

compressing a first syngas and a second syngas to produce a first compressed syngas and a second compressed syngas;

heating the first compressed syngas to produce a heated first syngas at a temperature of about 60°

C. to about 350°

C.;

combining the heated first syngas and the second compressed syngas to produce a combined syngas at a temperature of about 60°

C. to about 200°

C.;

reacting the combined syngas in a first ammonia converter to produce an effluent;

reacting the effluent in a second ammonia converter to produce an ammonia product;

transferring heat from the ammonia product to a first heat transfer medium to produce a first cooled product at a temperature of about 150°

C. to about 375°

C. and a second heat transfer medium;

transferring heat from the first cooled product to a third heat transfer medium to produce a second cooled product;

transferring heat from the second cooled product to the combined syngas to produce a third cooled product; and

separating the third cooled product to produce a purified ammonia product and a recycle gas.

2. The method of claim 1, wherein the first compressed syngas is at a pressure of about 9,000 kPa to about 20,000 kPa, and wherein the second compressed syngas is at a pressure of about 9,000 kPa to about 20,000 kPa.

4. The method of claim 1, wherein the effluent has an ammonia concentration of about 10 mol % to about 28 mol %.

5. The method of claim 4, wherein the effluent has a hydrogen concentration of about 45 mol % to about 65 mol % and a nitrogen concentration of about 10 mol % to about 30 mol %.

6. The method of claim 1, wherein the ammonia product has an ammonia concentration of about 10 mol % to about 30 mol %, a hydrogen concentration of up to about 0.5 mol %, and a nitrogen concentration of up to about 0.3 mol %.

7. The method of claim 1, wherein the second heat transfer medium is at a temperature of about 100°

C. to about 600°

C. and a pressure of about 50 kPa to about 20,000 kPa.

8. The method of claim 1, further comprising transferring heat from the ammonia product to the recycle gas to produce a heated recycle gas and a cooled ammonia product.

9. The method of claim 1, wherein at least a portion of the recycle gas is compressed with the second syngas to produce the second compressed syngas.

10. The method of claim 1, wherein the first compressed syngas has a water concentration of up to about 1 mol % and the second compressed syngas has a water concentration of up to about 1 mol %.

11. The method of claim 1, further comprising reforming a hydrocarbon to produce the syngas, wherein at least a portion of the recycle gas is combined with the hydrocarbon prior to reforming the hydrocarbon.

12. The method of claim 1, further comprising separating a raw syngas and at least a portion of the recycle gas in a pressure swing adsorption unit to produce the syngas.

3. The method of claim I, wherein the second compressed syngas is heated in the second ammonia converter by indirect heat exchange.

13. A method for producing ammonia, comprising:

compressing a first syngas and a second syngas to produce a first compressed syngas and a second compressed syngas;

heating the first compressed syngas to produce a heated first syngas at a temperature of about 60°

C. to about 250°

C.;

combining the heated first syngas and the second compressed syngas to produce a combined syngas at a temperature of about 60°

C. to about 200°

C.;

reacting the combined syngas in a first ammonia converter to produce an effluent having an ammonia concentration of about 10 mol % to about 20 mol %;

reacting the effluent in a second ammonia converter to produce an ammonia product having an ammonia concentration of about 15 mol % to about 30 mol %;

transferring heat from the ammonia product to a first heat transfer medium to produce a first cooled product at a temperature of about 150°

C. to about 375°

C. and a second heat transfer medium;

transferring heat from the first cooled product to a third heat transfer medium to produce a second cooled product;

transferring heat from the second cooled product to the combined syngas to produce a third cooled product; and

separating the third cooled product to produce a purified ammonia product and a recycle gas.

14. The method of claim 13, further comprising:

cooling the third cooled product to produce a fourth cooled product at a temperature of about 0°

C. to about 45°

C.;

cooling the fourth cooled product to produce a fifth cooled product at a temperature of about −

30°

C. to about 30°

C.; and

separating the fifth cooled product to produce the purified ammonia product and the recycle gas.

15. The method of claim 13, wherein heat is transferred from the fourth cooled product to the recycle gas to produce the fifth cooled product at a temperature of about −

30°

C. to about 30°

C. and a heated recycle gas at a temperature of about 10°

C. to about 70°

C.