Elevated pressure operation of molten carbonate fuel cells with enhanced CO2 utilization

Patent metadata

Field	Value
Publication number	US-11616248-B2
Application number	US-202217867324-A
Country	US
Kind code	B2
Filing date	Jul 18, 2022
Priority date	Nov 30, 2018
Publication date	Mar 28, 2023
Grant date	Mar 28, 2023

Abstract

Molten carbonate fuel cells (MCFCs) are operated at elevated pressure to provide increased operating voltage and/or enhanced CO2 utilization with a cathode input stream having a low CO2 content. It has been discovered that increasing the operating pressure of a molten carbonate fuel cell when using a low CO2-content cathode input stream can provide unexpectedly large increases in operating voltage while also reducing or minimizing the amount of alternative ion transport and/or enhancing CO2 utilization.

First claim

The invention claimed is:

1. A method for producing electricity, the method comprising:
introducing an anode input stream into an anode of a molten carbonate fuel cell;
introducing a cathode input stream comprising O 2 , H 2 O, and CO 2 into a cathode of the molten carbonate fuel cell; and
operating the molten carbonate fuel cell at a cathode pressure of 1 kPa-g or more, an average current density of 80 mA/cm 2 or more, and a measured CO 2 utilization of 70% or more to generate electricity, an anode exhaust comprising H 2 , CO, and CO 2 , and a cathode exhaust comprising CO 2 , 1.0 vol % or more O 2 , and 1.0 vol % or more H 2 O, wherein a calculated CO 2 utilization calculated based on the average current density is greater than the measured CO 2 utilization by 5.0% or more.

2. The method of claim 1 , wherein the cathode input stream comprises 5.0 vol % or less of CO 2 , or wherein the cathode exhaust comprises 1.0 vol % or less of CO 2 , or a combination thereof.

3. The method of claim 1 , wherein the molten carbonate fuel cell is operated at an anode pressure of 1 kPa-g or more, or wherein the cathode pressure is 10 kPa-g or more, or a combination thereof.

4. The method of claim 3 , wherein the anode pressure is 1 kPa-g to 300 kPa-g, or wherein the cathode pressure is 1 kPa-g to 300 kPa-g, or a combination thereof.

5. The method of claim 3 , wherein the anode pressure is 10 kPa-g to 500 kPa-g, or wherein the cathode pressure is 10 kPa-g to 500 kPa-g, or a combination thereof.

6. The method of claim 1 , wherein a fuel utilization in the anode is 60% or more, or wherein a fuel utilization in the anode is 55% or less.

7. The method of claim 1 , wherein an anode pressure and the cathode pressure differ by 0.5 kPa-g or less.

8. The method of claim 1 , wherein a voltage drop across the cathode is 0.4 V or less, or wherein the electricity is generated at a voltage of 0.55 V or more, or a combination thereof.

9. The method of claim 1 , wherein a H 2 concentration in the anode exhaust is 5.0 vol % or more, or wherein a combined concentration of H 2 and CO in the anode exhaust is 6.0 vol % or more, or a combination thereof.

10. The method of claim 1 , wherein the molten carbonate fuel cell is operated at a thermal ratio of 0.25 to 1.0.

11. A method for producing electricity, the method comprising:
introducing an anode input stream into an anode of a molten carbonate fuel cell;
introducing a cathode input stream comprising O 2 and 5.0 vol % or less CO 2 into a cathode of the molten carbonate fuel cell; and
operating the molten carbonate fuel cell at a cathode pressure of 1 kPa-g or more, an average current density of 80 mA/cm 2 or more, and a measured CO 2 utilization of 70% or more to generate electricity, an anode exhaust comprising H 2 , CO, and CO 2 , and a cathode exhaust comprising a CO 2 content of 1.0 vol % or less, wherein a calculated CO 2 utilization calculated based on the average current density is greater than the measured CO 2 utilization.

12. The method of claim 11 , wherein the calculated CO 2 utilization is greater than the measured CO 2 utilization by 2.0% or more.

13. The method of claim 11 , wherein the molten carbonate fuel cell is operated at an anode pressure of 1 kPa-g or more, or wherein the cathode pressure is 10 kPa-g or more, or a combination thereof.

14. The method of claim 13 , wherein the anode pressure is 1 kPa-g to 300 kPa-g, or wherein the cathode pressure is 1 kPa-g to 300 kPa-g, or a combination thereof.

15. The method of claim 13 , wherein the anode pressure is 10 kPa-g to 500 kPa-g, or wherein the cathode pressure is 10 kPa-g to 500 kPa-g, or a combination thereof.

16. The method of claim 11 , wherein an operating voltage of the molten carbonate fuel cell at a cathode pressure of 0 kPa-g is 0.75 V or less, when operated at an average current density of 80 mA/cm 2 or more with a difference of 1.0% or less between calculated CO 2 utilization and measured CO 2 utilization, and wherein the cathode pressure is 100 kPa-g to 500 kPa-g.

17. The method of claim 11 , wherein a fuel utilization in the anode is 60% or more, or wherein a fuel utilization in the anode is 55% or less.

18. The method of claim 11 , wherein an anode pressure and the cathode pressure differ by 0.5 kPa-g or less.

19. The method of claim 11 , wherein a voltage drop across the cathode is 0.4 V or less, or wherein the electricity is generated at a voltage of 0.55 V or more, or a combination thereof.

20. The method of claim 11 , wherein a H 2 concentration in the anode exhaust is 5.0 vol % or more, or wherein a combined concentration of H 2 and CO in the anode is exhaust is 6.0 vol % or more, or a combination thereof.

Assignees

• Exxonmobil Technology & Engineering Company
• Fuelcell Energy Inc

Inventors

• Rosen Jonathan
• Shen Eric B
• Geary Timothy C

Classifications

• H01M8/0491

  of fuel cell stacks · CPC title

• H01M8/04753

  of fuel cell reactants · CPC title

• H01M8/04805 Primary

  of fuel cell exhausts · CPC title

• Y02E60/50

  Fuel cells · CPC title

• H01M8/0488

  of fuel cell stacks · CPC title