Method for exhaust gas treatment in a solid oxide fuel cell power plant

• US 20060115691A1
• Filed: 12/10/2003
• Published: 06/01/2006
• Est. Priority Date: 12/10/2002
• Status: Abandoned Application

• Current Assignee: AKER Engineering As
• Original Assignee: AKER Engineering As, Statkraft Development AS (Government of Norway)
• Inventors: Hilmen, Anne-Mette, Ursin, Rord Peter
• Application Number:
  US10/538,167
• Publication Number:
  US 20060115691A1
• Time in Patent Office: Days
• US Class Current: 429/411
• CPC Class Codes: B01D 53/22 by diffusion manufacturing semi-permeable membranes B01D67/00; form, structure or properties of semi-permeable membranes B01D69/00; material for semi-permeable membranes B01D71/00
• CPC Class Codes: C01B 2203/00 Integrated processes for the production of hydrogen or synthesis gas reactors or details thereof B01J2208/00 - B01J2219/00
• CPC Class Codes: C01B 2203/0233 the reforming step being a steam reforming step
• CPC Class Codes: C01B 2203/0405 Purification by membrane separation
• CPC Class Codes: C01B 2203/0475 the impurity being carbon dioxide
• CPC Class Codes: C01B 2203/0495 the impurity being water
• CPC Class Codes: C01B 2203/066 with fuel cells
• CPC Class Codes: C01B 2203/0833 Heating by indirect heat exchange with hot fluids, other than combustion gases, product gases or non-combustive exothermic reaction product gases
• CPC Class Codes: C01B 2203/1241 Natural gas or methane
• CPC Class Codes: C01B 2203/127 Catalytic desulfurisation
• CPC Class Codes: C01B 2203/148 involving a recycle stream to the feed of the process for making hydrogen or synthesis gas
• CPC Class Codes: C01B 2203/84 Energy production
• CPC Class Codes: C01B 2203/86 Carbon dioxide sequestration
• CPC Class Codes: C01B 3/501 by diffusion
• CPC Class Codes: F02C 6/10 supplying working fluid to a user, e.g. a chemical process, which returns working fluid to a turbine of the plant
• CPC Class Codes: H01M 8/04014 Heat exchange using gaseous fluids; Heat exchange by combustion of reactants
• CPC Class Codes: H01M 8/04097 with recycling of the reactants H01M8/04119, H01M8/04104 take precedence
• CPC Class Codes: H01M 8/0668 Removal of carbon monoxide or carbon dioxide
• CPC Class Codes: H01M 8/0675 Removal of sulfur
• CPC Class Codes: H01M 8/0687 Reactant purification by the use of membranes or filters
• CPC Class Codes: H01M 8/243 : Grouping of unit cells of tubular or cylindrical configuration
• CPC Class Codes: Y02E 20/14 : Combined heat and power generation [CHP]
• CPC Class Codes: Y02E 60/50 : Fuel cells
• CPC Class Codes: Y02P 20/129 : Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
• CPC Class Codes: Y02P 20/151 : Reduction of greenhouse gas [GHG] emissions, e.g. CO2
• CPC Class Codes: Y02P 30/00 : Technologies relating to oil refining and petrochemical industry

Abstract

The invention relates to anode exhaust gas treatment methods for solid oxide fuel cell power plants with CO2 capture, in which the unreacted fuel in the anode exhaust (301) is recovered and recycled, while the resulting exhaust stream (303) consists of highly concentrated CO2. It is essential to the invention that the anode fuel gas (102) and the cathode air (205) are kept separate throughout the solid oxide fuel cell stacks (1). A gas turbine (202,207) is included on the air side in order to maximise the electrical efficiency.

Claims

1. A method for treatment of gas exiting the anode side (301) of a solid oxide fuel cell stack (1) fuelled with a carbon containing fuel (100) in a power producing process,

characterized in that the anode gas and cathode gas are kept separated by a seal system in the SOFC stack (4) and that the main part of the H₂ and CO in the anode exhaust (351) is separated from the CO₂ in said exhaust (301) by a separation process based on H₂ selective membranes (350).

2. A method according to claim 1,

characterized in that the anode exhaust (359) is treated such that most of the CO₂ is not emitted to the atmosphere.

3. A method according to claim 1,

characterized in that steam (361) is injected on the permeate side of the hydrogen selective membranes (350).

4. A method according to claim 1,

characterized in that the recovered H₂ (355) is fed back to the main SOFC stack (1) and used as fuel.

5. A method according to claim 1,

characterized in the recovered H₂ (355) is used to heat the oxygen depleted air (206) entering the expander (207).

6. A method according to claim 1,

characterized in that the recovered H₂ (355) is used to heat the air entering the SOFC stack (205).

7. A method according to claim 1,

characterized in that the recovered H₂ (355) is exported as a sales product.

8. A method according to claim 1,

characterised in that recovered H₂ (355) is fed to the desulphurisation unit (101) to provide necessary hydrogen for hydrodesulphurisation.

9. A method for treatment of gas exiting the anode side (301) of a solid oxide fuel cell stack (1) fuelled with a carbon containing fuel (100) in a power producing process,

characterised in that the anode gas and cathode gas are kept separated by a seal system in the SOFC stack (4), that the main part of the H₂ and CO in the anode exhaust (301) is separated from the CO₂ in said exhaust by a separation process based on compressing (312), drying (319) and cooling (321) to a pressure and temperature where most of the CO₂ is in liquid form (322) and subsequently is separated from the H₂ and CO in a conventional gravity based separation process (323).

10. A method according to claim 9,

characterised in that the anode exhaust (301) is treated such that most of the CO₂ is not emitted to the atmosphere.

11. A method according to claim 9,

characterised in that the recovered H₂ an CO (329) is fed back to the main SOFC stack (1) and used as fuel

12. A method according to claim 9,

characterised in that the recovered H₂ an CO (329) is removed in order to avoid build-up of gases which are non-condensable and non-combustible.

13. A method according to claim 9,

characterised in that the recovered H₂ an CO (329) is fed to the desulphurisation unit (101) to provide the necessary hydrogen for hydrodesulphurisation.