COMBUSTIBLE GAS MEASUREMENT

• US 3,607,084 A
• Filed: 12/02/1968
• Issued: 09/21/1971
• Est. Priority Date: 12/02/1968
• Status: Expired due to Term

• Current Assignee: Ihor B. Karpowycz, Robert J. Mackey
• Original Assignee: Ihor B. Karpowycz, Robert J. Mackey
• Inventors: Mackey, Robert J., Karpowycz, Ihor B.
• Primary Examiner(s): Wolk, Morris D.
• Assistant Examiner(s): Reese, R. M.
• Application Number:
  US04/780,476
• Time in Patent Office: 1,023 Days
• Field of Search: 23/232,232E,254,254E,255,255E,2.2,288.3 73/27 252/462,472 117/227,231
• US Class Current: 436/152
• CPC Class Codes: B01J 35/33 Electric or magnetic properties
• CPC Class Codes: F01N 3/00 Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust electric control F01N9/00; monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00 ; collecting or removing exhaust gases of vehicle engines in workshops B08B15/00, on highways E01C1/005
• CPC Class Codes: G01N 27/16 caused by burning or catalytic oxidation of surrounding material to be tested, e.g. of gas
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y10T 436/204998 Inorganic carbon compounds
• CPC Class Codes: Y10T 436/21 Hydrocarbon
• CPC Class Codes: Y10T 436/218 Total hydrocarbon, flammability, combustibility [e.g., air-fuel mixture, etc.]
• CPC Class Codes: Y10T 436/22 Hydrogen, per se
• CPC Class Codes: Y10T 436/255 including use of a solid sorbent, semipermeable membrane, or liquid extraction

Abstract

The measurement of combustible gases comprises passing a stream of gas containing the combustible gases over a conductive metal wire coated with a thin catalytic coating of a mixture of thorium oxide and black palladium powder and/or black platinum powder. Electrical current is passed through the conductor wire to raise the temperature of the wire to a first temperature at which the oxidation of the combustible gases is initiated in the presence of the catalytic effect produced by the coating. The oxidation of the combustible gases substantially elevates the temperature of the conductor wire, changing its electrical resistance, the amount of heat generated during oxidation being directly proportional to the quantity of combustible gases in the gas stream. The metal conductor wire is preferably formed of a base metal in which the change in resistivity between the first and elevated temperatures is substantially equal to or greater than the change in resistivity of platinum between those temperatures.

Claims

2. The method of claim 1 where said powdered platinum group metal is a metal selected from the group consisting of black platinum, black palladium and mixtures thereof.

3. The method of claim 1 wherein the temperature change is sensed by heating a base metal conduct or from said first temperature to substantially said second temperature and measuring the change in electrical resistivity of said metallic conductor between said first and second temperatures.

4. The method of claim 3 wherein said metallic conductor is a base metal selected from the groUp consisting of titanium, stainless steel, and a nickel alloy.

5. The method of claim 4 wherein said stainless steel is T 434 and said nickel alloy is 70% nickel and 30% iron.

6. The method of claim 3 wherein said base metal conductor is a metal in which the change in electrical resistivity between said first and second temperatures is substantially equal to or greater than the change in resistivity of platinum between said temperatures.

7. The method of claim 1 wherein said metal oxide is thorium oxide.

8. The method of claim 1 wherein said volume of gases are exhaust gases from a combustion engine and said combustible gases generally comprise at least one of CO, H2and CxHn.

9. An element for measuring the quantity of combustible gases in a volume of gas comprising, a metallic conductor, and a rigid coating on said conductor comprising a catalytic mixture of a metal oxide and a powdered metal of the platinum group.

10. The measuring element of claim 9 wherein said metallic conductor is a metal in which the change in electrical resistivity when the metal is heated over a given temperature range is substantially equal to or greater than the change in resistivity of platinum when platinum is heated over said given temperature range.

11. The measuring element of claim 9 wherein said metallic conductor is a base metal selected from the group consisting of titanium, stainless steel, and a nickel alloy.

12. The measuring element of claim 11 wherein said stainless steel is T 434 and wherein said nickel alloy is 70% nickel and 30% iron.

13. The measuring element of claim 9 wherein said powdered platinum group metal is a metal selected from the group consisting of black palladium, black platinum and mixtures thereof.

14. The measuring element of claim 9 wherein said metal oxide is thorium oxide.

15. A system for measuring the quantity of combustible gases in a volume of gas comprising:

a chamber for containing the volume of gas, a pair of electrically conductive metallic wires located in said chamber in the volume of gas, electric power supply means for supplying an electric current flow through said wires, a coating on one of said wires substantially entirely covering the surface of said wire exposed to said volume of gas, said coating comprising a catalytic mixture of a metal oxide and a powdered metal of the platinum group, heating means for elevating the temperature of said volume of gas to a first temperature at which the combustible gases in the volume of gas are oxidized in the presence of said catalytic mixture of metal oxide and platinum group metal, and measuring means for measuring the electrical resistance change in said one wire caused by the elevation in temperature of said wire from said first temperature to a higher temperature due to the heat of combustion produced by the oxidation of the combustible gases.

16. The system of claim 15 wherein said measuring means comprises a Wheatstone bridge, said pair of metallic wires comprising one of the resistances therein.

17. The system of claim 15 wherein said metallic wire is a metal in which the change in electrical resistivity between said first and higher temperatures is substantially equal to or greater then the change in resistivity of platinum between said temperatures.

18. The system of claim 15 wherein said wire is a base metal selected from the group consisting of titanium, stainless steel and a nickel alloy.

19. The system of claim 15 wherein said powdered platinum group metal is selected from the group consisting of black palladium, black platinum and mixtures thereof.

20. The system of claim 19 wherein said metal oxide is thorium oxide.

21. The system of claim 15 wherein said heating means comprises said conductive metallic wire, said power supply means heating said metallic wire to substantially said first temperature to initiate the Oxidation of the combustible gases.