Method for increasing efficiency and reducing emissions in a steam reforming plant

Patent metadata

Field	Value
Publication number	US-11629051-B2
Application number	US-202117377625-A
Country	US
Kind code	B2
Filing date	Jul 16, 2021
Priority date	Jul 16, 2021
Publication date	Apr 18, 2023
Grant date	Apr 18, 2023

Abstract

A method for decreasing the SFFC of a steam reforming plant, including establishing a base operating mode. Then modifying the base operating mode by introducing the shift gas stream into a solvent based, non-cryogenic separator prior to introduction into the pressure swing adsorption and introducing the compressed hydrogen depleted off-gas stream in a membrane separation unit, wherein the membrane is configured to produce the hydrogen enriched permeate stream at a suitable pressure to allow the hydrogen enriched permeate stream to be combined with carbon dioxide lean shift gas stream, prior to introduction into the pressure swing adsorption unit without requiring additional compression. Thereby establishing a modified operating mode. Wherein said pressure swing adsorption unit has a modified overall hydrogen recovery. Wherein said modified operating mode has a modified hydrogen production, a modified hydrogen production unit firing duty, a modified SCO2e, and a modified SFFC.

First claim

What is claimed is:

1. A method for decreasing the SFFC and SCO2e and increasing the SCO2c of a steam reforming plant, comprising:
a. introducing a hydrocarbon stream and a steam stream into a steam methane reformer, thereby producing a raw syngas stream, wherein the hydrocarbon stream has a hydrocarbon stream pressure,
b. introducing the raw syngas stream into a high temperature water gas shift converter, thereby producing a shift gas stream, and
c. introducing the shift gas stream into a pressure swing adsorption unit, thereby producing a hydrogen product stream

thereby establishing a base operating mode,
wherein said pressure swing adsorption unit has a base overall hydrogen recovery,
wherein said base operating mode has a base hydrogen production, a base hydrogen production unit firing duty, a base SCO2e, a base SCO2c, and a base SFFC,

the method further comprising:
d. introducing the shift gas stream into a solvent based, non-cryogenic separator prior to introduction into the pressure swing adsorption unit, thereby producing a saturated carbon dioxide stream, and a carbon dioxide lean shift gas stream,
e. combining the carbon dioxide lean shift gas stream with a hydrogen enriched permeate stream and introducing the combined gas stream into the pressure swing adsorption unit, thereby producing a modified hydrogen product stream, which contains not more than 90% of the total hydrogen produced by the syngas generation and water gas shift steps, and a hydrogen depleted off-gas stream, which contains not less than 10% of the total hydrogen contained within the shift gas stream, wherein the hydrogen depleted off-gas stream is compressed to a pressure greater than 25 psi greater than the hydrocarbon stream pressure,
f. introducing the compressed hydrogen depleted off-gas stream in a membrane separation unit, thereby producing a hydrogen enriched permeate stream and a hydrogen depleted retentate stream, wherein the membrane is configured to produce the hydrogen enriched permeate stream at a suitable pressure to allow the hydrogen enriched permeate stream to be combined with carbon dioxide lean shift gas stream, prior to introduction into the pressure swing adsorption unit without requiring additional compression, and wherein the hydrogen depleted retentate stream is combined with the hydrocarbon stream prior to admission into the steam methane reformer as the process feed stream,

thereby establishing a modified operating mode,
wherein said pressure swing adsorption unit has a modified overall hydrogen recovery,
wherein said modified operating mode has a modified hydrogen production, a modified hydrogen production unit firing duty, a modified SCO2e, and a modified SFFC
wherein the modified SCO2e is at least 7% less than the base SCO2e,
wherein the modified SCO2c is at least 12% greater than the base SCO2c.

2. The method of claim 1 , wherein the modified overall hydrogen recovery for the pressure swing adsorption unit is not less than 98 mol % or an improvement of not less than 10 base points over the base overall hydrogen recovery.

3. The method of claim 2 , wherein the modified overall hydrogen recovery for the pressure swing adsorption unit is not less than 99 mol %.

4. The method of claim 1 , wherein the difference between the modified hydrogen production and the base hydrogen production comprises a delta hydrogen recovery,
wherein the difference between the modified hydrogen production unit firing duty and the base hydrogen production unit firing duty comprises a delta hydrogen production unit firing duty.

5. The method of claim 4 , wherein the base hydrogen production may be achieved with the modified operating mode by reducing the base hydrogen production unit firing duty by the delta hydrogen production unit firing duty, thereby a modified SFFC that is not less than 1% lower than the base SFFC.

6. The method of claim 5 , wherein the modified SFFC that is not less than 2% lower than the base SFFC.

7. The method of claim 1 , wherein the syngas stream is introduced into a low temperature water gas shift reactor following the high temperature water gas shift reactor and prior to introduction to the solvent based, non-cryogenic separator, thereby reducing the off-gas stream carbon dioxide content and increasing the syngas carbon dioxide content.

8. The method of claim 7 , wherein the solvent based non-cryogenic separator produces a flash gas at not more than 200 psig, containing CO2, hydrogen, carbon monoxide, and methane, which is combined with the hydrogen depleted off-gas stream, thereby producing a further modified SCO2e, wherein the further modified SCO2e is at least 8% less than the base SCO2e, and producing a modified SCO2c, wherein the modified SCO2c is at least 5% less than the base SCO2C.

9. The method of claim 8 , wherein the flash gas has a pressure of not more than 30 psig.

10. The method of claim 7 , wherein at least a portion of modified hydrogen product stream is combined with the hydrocarbon stream and introduced into the steam methane reformer as the fuel gas stream, thereby resulting in a further modified SCO2e, wherein the further modified SCO2e is at least 20% less than the base SCO2e, and producing a modified SCO2C, wherein the modified SCO2c is at least 20% greater than the base SCO2C.

11. The method of claim 7 , wherein the hydrocarbon feedstock is more carbon rich than methane, thereby maximizing the SCO2c from syngas.

12. The method of claim 1 , wherein the modified hydrogen production is achieved with the base hydrogen production unit firing duty, and wherein the modified hydrogen production is at least 10% greater than the base hydrogen production.

13. The method of claim 12 , wherein the modified hydrogen production is at least 15% greater than the base hydrogen production.

14. The method of claim 1 , wherein the membrane separation unit recovers more than 50 mol % of the hydrogen contained in the hydrogen depleted off-gas steam.

15. The method of claim 14 , wherein the membrane unit recovers at least 70% of the hydrogen contained in the hydrogen depleted off-gas steam.

16. The method of claim 1 , wherein the hydrogen enriched permeate stream at least 50 mol % hydrogen.

17. The method of claim 16 , wherein the hydrogen enriched permeate stream is at least 70 mol % hydrogen purity.

18. The method of claim 1 , wherein the modified SCO2e is at least 9% less than the base SCO2e.

19. The method of claim 1 , wherein the modified SCO2c is at least 14% greater than the base SCO2c.

Assignees

• Air Liquide

Inventors

• Guerif Pierre-Philippe
• Stroffolino Iv Joseph T
• Guillard Alain

Classifications

• B01D53/229

  Integrated processes (Diffusion and at least one other process, e.g. adsorption, absorption) · CPC title

• B01D53/047

  Pressure swing adsorption · CPC title

• C01B3/52

  by contacting with liquids; Regeneration of used liquids · CPC title

• C01B2203/0405

  Purification by membrane separation · CPC title

• C01B2203/86

  Carbon dioxide sequestration · CPC title