Electrolysis cell system including recirculating product gas stream for cooling the cell

• US 3,905,884 A
• Filed: 11/20/1974
• Issued: 09/16/1975
• Est. Priority Date: 11/20/1974
• Status: Expired due to Term

• Current Assignee: Daniel W. Beal, David P. Bloomfield, Edmund K. Parenti Jr, Paul E. Grevstad
• Original Assignee: Daniel W. Beal, David P. Bloomfield, Edmund K. Parenti Jr, Paul E. Grevstad
• Inventors: Parenti, Edmund K. Jr., Bloomfield, David P., Grevstad, Paul E., Beal, Daniel W.
• Primary Examiner(s): Andrews, R. L.
• Application Number:
  US05/525,610
• Time in Patent Office: 300 Days
• Field of Search: 204/274,278,129 136/86R,86C
• US Class Current: 205/349
• CPC Class Codes: C25B 1/04 by electrolysis of water
• CPC Class Codes: H01M 8/186 by electrolytic decomposition of the electrolytic solution or the formed water product
• CPC Class Codes: Y02E 60/36 Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
• 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 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

An electrolysis cell system includes a compact electrolysis cell comprising gas diffusion electrodes on each side of an aqueous electrolyte retaining matrix. A portion of the hydrogen gas produced by the cell has water added thereto and is recirculated through a thermal exchange portion of the cell to remove waste heat from the cell and create a temperature gradient thereacross. The amount of water introduced into the recirculating gas stream is controlled to maintain a predetermined temperature of the gas stream emerging from the thermal exchange portion of the cell. The stream leaves the thermal exchange portion of the cell and reenters the cell in the gas space adjacent one of the electrodes. In a preferred embodiment the water added is sprayed into the recirculating gas stream and the heat laden stream emerging from the thermal exchange portion of the cell passes through a condenser where water vapor in the stream is converted to liquid and where heat is removed from the stream; the water vapor partial pressure of the stream reentering the cell is controlled by keeping the temperature of the stream leaving the condenser within a certain temperature range.

Claims

1. An electrolysis cell system for producing oxygen and hydrogen comprising:

an electrolysis cell including a pair of gas diffusion electrodes spaced apart, aqueous electrolyte matrix means in the space between said electrodes, means forming a gas space on the nonelectrolyte side of each electrode, one of said gas spaces including inlet means and outlet means, said cell Also including a thermal exchange portion having entrance means and exit means;

means for recirculating a portion of one of said product gases from said outlet means, through said thermal exchange portion, to said inlet means and back through said gas space;

means for introducing sufficient water into said recirculating product gas to maintain the temperature of said gas exiting from said thermal exchange portion exit means at a predetermined first temperature;

condenser means disposed in said recirculating gas stream between said thermal exchange portion exit means and said gas space inlet means for removing heat from said recirculating gas stream exiting from said thermal exchange portion and for condensing vaporized water entrained within said recirculating gas; and

means for establishing a desired partial pressure of water vapor in said recirculating gas reentering said gas space inlet means.

2. The electrolysis cell system according to claim 1 including means causing the water within said recirculating gas to enter said thermal exchange portion in droplet form to create a temperature gradient across said cell.

3. The electrolysis cell system according to claim 2 wherein said electrolysis cell system is arranged and constructed so that the temperature of said cell decreases from said inlet means to said outlet means across said cell, and wherein said means for establishing a desired partial pressure of water vapor in said recirculating gas entering said gas inlet means includes (A) thermal sensing means for sensing a second temperature of said recirculating gas leaving said condenser, and (B) means responsive to said thermal sensing means for maintaining said second temperature within a range which will result in the desired partial pressure of water vapor in said recirculating gas entering said inlet means.

4. The electrolysis cell system according to claim 3 wherein said condenser means includes means for carrying a coolant into indirect heat exchange relationship with said recirculating gas and wherein said means responsive to said thermal sensing means for maintaining said second temperature within a range which will result in the desired partial pressure of water vapor in said recirculating gas as it reenters said inlet means includes (A) bypass means for bypassing said coolant around said condenser means, and (B) bypass valve means responsive to said thermal sensing means for controlling the proportion of flow of coolant through said condenser means and said bypass means.

5. The electrolysis cell system according to claim 4 including pump separator means in said recirculating gas stream said condenser means and said gas space inlet means for separating out liquid water entrained in said recirculating gas, and means in operable relationship with said pump separator means for taking said separated liquid water out of said recirculating gas and reintroducing it into said recirculating gas between said gas space outlet means and said thermal exchange portion entrance means.

6. The electrolysis cell system according to claim 2 wherein said means for introducing water includes first thermal sensing means for sensing the temperature of the recirculating gas exiting from said thermal exchange portion exit means, pressurized water supply means, first control valve means responsive to said first thermal sensing means for permitting the proper amount of water to pass from said supply means into said recirculating gas to maintain the temperature of said recirculating gas exiting from said thermal exchange portion exit means at said predetermined first temperature.

7. The electrolysis cell system according to claim 6 wherein said recirculating product gas is hydrogen and said electrolysis cell is a base cell.

8. The electrolysis cell system according to claim 6 wherein said electrolysis cell system is arranged and constructed so that the temperature of said cell decreases from said inlet means to said outlet means across sAid cell, and wherein said means for establishing a desired partial pressure of water vapor in said recirculating gas as it enters said gas inlet means includes (A) second thermal sensing means for sensing a second temperature of said recirculating gas leaving said condenser, and (B) means responsive to said second thermal sensing means for maintaining said second temperature within a range which will result in the desired partial pressure of water vapor in said recirculating gas as it enters said inlet means.

9. The electrolysis cell system according to claim 7 including pump separator means in said recirculating gas stream between said condenser means and said gas space inlet means for separating out liquid water entrained in said recirculating gas, and means in operable relationship with said pump separator means for taking said separated liquid water out of said recirculating gas and reintroducing it into said recirculating gas between said gas space outlet means and said thermal exchange portion entrance means.

10. IN THE PROCESS OF GENERATING HYDROGEN GAS AND OXYGEN GAS IN AN ELECTROLYSIS CELL WHEREIN THE CELL INCLUDES A PAIR OF GAS DIFFUSION ELECTRODES SPACED APART, MATRIX MEANS FOR RETAINING AN AQUEOUS ELECTROLYTE IN THE SPACE BETWEEN SAID ELECTRODES, MEANS FORMING A HYDROGEN GAS SPACE ON THE NONELECTROLYTE SIDE OF ONE OF SAID PAIR OF ELECTRODES AND AN OXYGEN GAS SPACE ON THE NONELECTROLYTE SIDE OF THE OTHER OF SAID PAIR OF ELECTRODES, AND A THERMAL EXCHANGE PORTION, THE STEPS OF:

SUPPLYING CURRENT TO SAID CELL, RECIRCULATING A PORTION OF ONE OF SAID PRODUCT GASES FROM ITS RESPECTIVE HAS SPACE THROUGH SAID THERMAL EXCHANGE PORTION AND BACK THROUGH SAID GAS SPACE, INTRODUCING WATER INTO SAID RECIRCULATING PRODUCT GAS FOR REMOVING HEAT FROM SAID CELL, SAID WATER BEING INTRODUCED IN AN AMOUNT SUFFICIENT TO MAINTAIN THE TEMPERATURE OF SAID STREAM EXITING FROM SAID THERMAL EXCHANGE PORTION AT A PREDETERMINED TEMPERATURE, CONSENSING VAPORIZED WATER ENTRAINED WITHIN SAID RECIRCULATING GAS IT EXITING FROM SAID THERMAL EXCHANGE PORTION AND PRIOR TO ITS BEING REINFOFUCED INTO SAID GAS SPACE FOR REMOVING HEAT THEREFROM, AND ESTABLISHING A DESIRED PARTIAL PRESSURE OF WATER VAPOR IN SAID RECIRCULATING GAS AS IT REENTERS SAID GAS SPACE.

11. The process according to claim 10 including the step of causing the water within said recirculating gas to enter said thermal exchange portion in droplet form to create a temperature gradient across said cell.

12. The process according to claim 11 wherein said step of recirculating a portion of one of said product gases includes flowing said product gas through said thermal exchange portion in a direction counter to the flow of said recirculating gas through its respective gas space so that the temperature of said cell decreases across said cell in the direction of the flow of said recirculating gas through its respective gas space.

13. The process according to claim 12 wherein said step of establishing a desired partial pressure of water vapor in said recirculating gas as it reenters said gas space includes the step of maintaining the temperature of said recirculating gas as it reenters said gas space within a range which will result in said desired partial pressure of water vapor.

14. The process according to claim 13 wherein said step of condensing includes the step of carrying a coolant through a heat exchanger into indirect heat exchange relationship with said recirculating gas.

15. The process according to claim 14 wherein said step of maintaining said desired partial pressure of water vapor in said recirculating gas as it reenters said gas space includes bypassing an appropriate portion of said recirculating gas around said indirect heat exchanger thereby removing less heat from said recirculating gas.

16. The process according to claim 15 includng maintaining substantially equivalent product gas pressures in said gas spaces of said cell and wherein said step of recirculatiNg a portion of one of said product gases includes recirculating a portion of said hydrogen produced by said cell.

17. The process according to claim 12 including the step of separating the condensed liquid water entrained in the recirculating gas from the water in vapor form prior to said gas reentering said gas space, bypassing said separated liquid water around said gas space, and reintroducing it into said recirculating gas before said recirculating gas enters said thermal exchange portion.

18. The process according to claim 11 wherein said step of recirculating a portion of one of said product gases includes recirculating a portion of said hydrogen produced by said cell.

19. The process according to claim 11 wherein the step of causing the water to enter said thermal exchange portion in droplet form includes passing all liquid water within said recirculating gas and water added to said recirculating gas through a sprayer positioned immediately upstream of said thermal exchange portion.