Combusting a hydrocarbon gas to produce a reformed gas

• US 5,861,441 A
• Filed: 02/14/1997
• Issued: 01/19/1999
• Est. Priority Date: 02/13/1996
• Status: Expired due to Fees

• Current Assignee: REG Synthetic Fuels, LLC (Chevron Corp.)
• Original Assignee: Marathon Oil Company (Marathon Oil Corporation)
• Inventors: Waycuilis, John J.
• Primary Examiner(s): Geist, Gary
• Assistant Examiner(s): PADMANABHAN, SREENIVASAN
• Application Number:
  US08/800,642
• Time in Patent Office: 704 Days
• Field of Search: 518/703, 518/704, 252/373, 60/39.12, 60/39.05, 60/39.53
• US Class Current: 518/703
• CPC Class Codes: C01B 2203/0233 the reforming step being a steam reforming step
• CPC Class Codes: C01B 2203/0811 by combustion of fuel
• CPC Class Codes: C01B 2203/82 Several process steps of C01B2203/02 - C01B2203/08 integrated into a single apparatus
• CPC Class Codes: C01B 2203/84 Energy production
• CPC Class Codes: C01B 3/384 the catalyst being continuously externally heated
• CPC Class Codes: C07C 1/0405 Apparatus
• CPC Class Codes: C07C 1/0485 Set-up of reactors or accessories; Multi-step processes
• CPC Class Codes: F23C 2201/301 with different fuels in stages
• CPC Class Codes: F23C 6/047 with fuel supply in stages
• CPC Class Codes: F23R 3/346 for staged combustion
• CPC Class Codes: F23R 3/36 Supply of different fuels

Abstract

A system and process are provided for converting a hydrocarbon gas to a reformed gas containing hydrogen and carbon monoxide. In accordance with a first embodiment, the system includes a primary combustor, compressor and power turbine. The process is practiced by compressing a feed air in the primary compressor to produce a primary air. The primary air is fed with a primary hydrocarbon gas to the primary combustor, producing a reformed gas that drives the primary power turbine. The primary power turbine is linked to the primary compressor, compressing the feed air in an energy self-sufficient manner. In a second embodiment, the system of the first embodiment further includes a secondary combustor, compressor and power turbine. The process is practiced in the same manner as the first embodiment, producing the reformed gas and driving the primary power turbine and compressor. A portion of the primary air is also fed with a secondary hydrocarbon gas to the secondary combustor, producing an off-gas that drives the secondary power turbine and compressor to compress a gas in an energy self-sufficient manner. In a third embodiment, the system is substantially the same as the second embodiment, but reconfigures the compressors and power turbines and further includes an auxiliary secondary power turbine. The process is practiced in the same manner as the first embodiment, producing the reformed gas and driving the primary power turbine and compressor. The off-gas is produced in the same manner as the second embodiment to drive the secondary power turbine, but the secondary power turbine drives an auxiliary primary compressor, compressing the feed air ahead of the primary compressor in an energy self-sufficient manner. The off-gas further drives the auxiliary secondary power turbine to provide additional power for alternate power users.

Claims

1. A process for reforming a hydrocarbon gas comprising:

a) providing a primary hydrocarbon gas divided into a first portion and a second portion and feeding a primary air and said first portion of said primary hydrocarbon gas to a combustion zone of a primary combustor having a reforming zone downstream of said combustion zone;

b) combusting said primary air and said first portion of said primary hydrocarbon gas in said combustion zone to produce a primary combustion gas;

c) feeding said primary combustion gas and said second portion of said primary hydrocarbon gas to said reforming zone and reacting said primary combustion gas therein to produce a reformed gas containing hydrogen and carbon monoxide;

d) driving a primary power turbine with said reformed gas;

e) driving a primary compressor with said primary power turbine; and

f) compressing a feed air in said primary compressor to produce said primary air.

2. The process of claim 1 further comprising feeding water or steam to said combustion zone.

3. The process of claim 1 further comprising dividing said primary air produced from said feed air into a first portion and a second portion and wherein said primary air fed to said combustion zone is said first portion of said primary air.

4. The process of claim 3 further comprising feeding a secondary hydrocarbon gas and said second portion of said primary air as a secondary air to a secondary combustor and reacting said secondary hydrocarbon gas and said secondary air in said secondary combustor to produce an off-gas containing carbon dioxide and water.

5. The process of claim 4 further comprising driving a secondary power turbine with said off-gas.

6. The process of claim 5 further comprising driving a secondary compressor with said secondary power turbine.

7. The process of claim 5 further comprising driving an auxiliary primary compressor with said secondary power turbine to compress said feed air upstream of said primary compressor.

8. The process of claim 5 further comprising driving an auxiliary secondary power turbine with said off-gas after driving said secondary power turbine.

9. The process of claim 4 wherein said secondary combustor has a flame zone and an oxidation zone downstream of said flame zone and further wherein said secondary air and said secondary hydrocarbon gas are combusted in said flame zone to produce a secondary combustion gas.

10. The process of claim 9 further comprising dividing said secondary air into a first portion and a second portion and wherein said secondary air fed to said flame zone is said first portion of said secondary air.

11. The process of claim 10 further comprising feeding said second portion of said secondary air to said secondary combustor downstream of said flame zone and reacting said second portion of said secondary air with said secondary combustion gas in said oxidation zone to produce said off-gas.

23. The process of claim 1 wherein said primary air fed to said combustion zone contains an amount of oxygen which is substantially stoichiometric for combustion of the hydrocarbons in said first portion of said primary hydrocarbon gas fed to said combustion zone.

24. The process of claim 1 wherein said primary air fed to said combustion zone contains an amount of oxygen which is between about 20% deficient to about 20% excess of the amount of oxygen required for substantially complete combustion of the hydrocarbons in said first portion of said primary hydrocarbon gas fed to said combustion zone.

25. The process of claim 1 wherein said primary combustor is substantially free of a catalyst for promoting reforming reactions in said primary combustor.

12. A process for reforming a hydrocarbon gas comprising:

a) compressing a feed air in a primary compressor to produce a primary air;

b) dividing said primary air into a first portion and a second portion and dividing a primary hydrocarbon into a first portion and a second portion;

c) combusting said first portion of said primary air and said first portion of said primary hydrocarbon gas in a combustion zone of a primary combustor having a reforming zone downstream of said combustion zone to produce a primary combustion gas;

d) feeding said primary combustion gas and said second portion of said primary hydrocarbon gas to said reforming zone and reacting said primary combustion gas therein to produce a reformed gas containing hydrogen and carbon monoxide;

e) driving a primary power turbine with said reformed gas;

f) driving said primary compressor with said primary power turbine;

g) feeding said second portion of said primary air as a secondary air to a secondary combustor with a secondary hydrocarbon gas;

h) reacting said secondary hydrocarbon gas and said secondary air in said secondary combustor to produce an off-gas containing carbon dioxide and water;

i) driving a secondary power turbine with said off-gas; and

j) driving a secondary compressor with said secondary power turbine.

13. The process of claim 12 further comprising feeding water or steam to said combustion zone.

14. The process of claim 12 wherein said secondary combustor has a flame zone and an oxidation zone downstream of said flame zone and further wherein said secondary air and said secondary hydrocarbon gas are combusted in said flame zone to produce a secondary combustion gas.

15. The process of claim 14 further comprising dividing said secondary air into a first portion and a second portion and wherein said secondary air fed to said flame zone is said first portion of said secondary air.

16. The process of claim 15 further comprising feeding said second portion of said secondary air to said secondary combustor downstream of said flame zone and reacting said second portion of said secondary air with said secondary combustion gas in said oxidation zone to produce said off-gas.

26. The process of claim 12 wherein said primary air fed to said combustion zone contains an amount of oxygen which is substantially stoichiometric for combustion of the hydrocarbons in said first portion of said primary hydrocarbon gas fed to said combustion zone.

27. The process of claim 12 wherein said primary air fed to said combustion zone contains an amount of oxygen which is between about 20% deficient to about 20% excess of the amount of oxygen required for substantially complete combustion of the hydrocarbons in said first portion of said primary hydrocarbon gas fed to said combustion zone.

28. The process of claim 12 wherein said primary combustor is substantially free of a catalyst for promoting reforming reactions in said primary combustor.

17. A process for reforming a hydrocarbon gas comprising:

a) compressing a feed air in an auxiliary primary compressor to produce an intermediate air;

b) compressing said intermediate air in a primary compressor to produce a primary air;

c) dividing said primary air into a first portion and a second portion and dividing a primary hydrocarbon into a first portion and a second portion;

d) combusting said first portion of said primary air and said first portion of said primary hydrocarbon gas in a combustion zone of a primary combustor having a reforming zone downstream of said combustion zone to produce a primary combustion gas;

e) feeding said primary combustion gas and said second portion of said primary hydrocarbon gas to said reforming zone and reacting said primary combustion gas therein to produce a reformed gas containing hydrogen and carbon monoxide;

f) driving a primary power turbine with said reformed gas;

g) driving said primary compressor with said primary power turbine;

h) feeding said second portion of said primary air as a secondary air to a secondary combustor with a secondary hydrocarbon gas;

i) reacting said secondary hydrocarbon gas and said secondary air in said secondary combustor to produce an off-gas containing carbon dioxide and water;

j) driving a secondary power turbine with said off-gas; and

k) driving said auxiliary primary compressor with said secondary power turbine.

18. The process of claim 17 further comprising feeding water or steam to said combustion zone.

19. The process of claim 17 wherein said secondary combustor has a flame zone and an oxidation zone downstream of said flame zone and further wherein said secondary air and said secondary hydrocarbon gas are combusted in said flame zone to produce a secondary combustion gas.

20. The process of claim 19 further comprising dividing said secondary air into a first portion and a second portion and wherein said secondary air fed to said flame zone is said first portion of said secondary air.

21. The process of claim 20 further comprising feeding said second portion of said secondary air to said secondary combustor downstream of said flame zone and reacting said second portion of said secondary air with said secondary combustion gas in said oxidation zone to produce said off-gas.

22. The process of claim 17 further comprising driving an auxiliary secondary power turbine with said off-gas after driving said secondary power turbine.

29. The process of claim 17 wherein said primary air fed to said combustion zone contains an amount of oxygen which is substantially stoichiometric for combustion of the hydrocarbons in said first portion of said primary hydrocarbon gas fed to said combustion zone.

30. The process of claim 17 wherein said primary air fed to said combustion zone contains an amount of oxygen which is between about 20% deficient to about 20% excess of the amount of oxygen required for substantially complete combustion of the hydrocarbons in said first portion of said primary hydrocarbon gas fed to said combustion zone.

31. The process of claim 17 wherein said primary combustor is substantially free of a catalyst for promoting reforming reactions in said primary combustor.