Apparatus and method for measuring the composition of gases using ionically conducting electrolytes

• US 6,309,534 B1
• Filed: 03/21/2000
• Issued: 10/30/2001
• Est. Priority Date: 07/03/1997
• Status: Expired due to Term

• Current Assignee: Foseco International Limited (Vesuvius Plc)
• Original Assignee: Derek John Fray, Ramachandran Vasant Kumar
• Inventors: Fray, Derek John, Kumar, Ramachandran Vasant
• Primary Examiner(s): Tung, T.
• Application Number:
  US09/446,850
• Time in Patent Office: 588 Days
• Field of Search: 204/402, 204/400, 204/421-429, 204/431, 204/432, 205/783.5, 205/784, 205/784.5, 205/785, 205/775
• US Class Current: 205/775
• CPC Class Codes: G01N 27/407 for investigating or analysing gases G01N27/411 takes precedence

Abstract

The subject method and apparatus pertains to the accurate determination of a composition of gases, over a very wide range of compositions. The subject invention can utilize an ionic electrolyte (1), which separates gases of different compositions, a source of potential difference (2) which is applied across the ionic electrolyte, means for reversing the current, and means (3) for measuring the respective currents. The ratio of currents is a function of the ratio of the gas compositions on opposite sides of the electrolyte. By varying the applied potential, the sensitivity of the apparatus can be increased.

Claims

1. An apparatus for measuring the composition of a gas, comprising an electrolyte separating a gas from a known composition of gas;

means for applying a potential difference across the electrolyte to generate a first current;

means for reversing the potential difference across the electrolyte to generate a second current;

means for measuring the first current associated with the potential difference across the electrolyte;

means for measuring the second current associated with the reversed potential difference across the electrolyte; and

means for determining the ratio of the first current and the second current.

2. The apparatus according to claim 1, wherein the electrolyte is solid.

3. The apparatus according to claim 1, wherein the electrolyte is liquid.

4. The apparatus according to claim 3, wherein the liquid electrolyte is contained within a ceramic structure.

5. The apparatus according to claim 1, wherein the electrolyte conducts oxygen ions.

6. The apparatus according to claim 1, wherein the electrolyte is zirconia stabilized with calcium oxide, magnesium oxide or yttrium oxide.

7. The apparatus according to any of claim 1, wherein the electrolyte conducts hydrogen ions.

8. The apparatus according to claim 7, wherein the electrolyte is a perovskite.

9. The apparatus according to claim 8, wherein the electrolyte is strontium cerate or calcium zirconate.

10. The apparatus according to claim 7, wherein the electrolyte is strontium cerate or calcium zirconate.

11. A method for measuring the composition of a gas, comprising separating a gas from a known composition of gas with an electrolyte, applying a potential difference across the electrolyte to generate a first current measuring the first current associated with the potential difference across the electrolyte, reversing the potential difference across the electrolyte to generate a second current, measuring the second current associated with the reversed potential difference across the electrolyte, and determining the ratio of the first current and second current.

12. The method according to claim 11, wherein the magnitude of the applied potential is given by the Nernst equation for the gas with respect to the known composition of gas.

13. The method according to claim 12, wherein the gas composition on one side of the electrolyte is maintained at one concentration.

14. The method according to claim 12, wherein the gas of known composition is air.

15. The method according to claim 11, wherein the gas composition on one side of the electrolyte is maintained at one concentration.

16. The method according to claim 15, wherein the gas of known composition is air.

17. A method according to claim 11, wherein the gas of known composition is air.

18. The method according to claim 11, wherein the electrolyte is solid.

19. The method according to claim 11, wherein the electrolyte is liquid.