Reducing gas generators and methods for generating a reducing gas

1. A reducing gas generator, comprising:

an oxidant system configured to generate from air an oxidant having a variable oxygen content, and configured to provide an oxygen content of the oxidant at a selected value greater than that of ambient atmospheric air;

the oxidant system including a first merging chamber configured to receive an oxygen-rich gas and a nitrogen-rich gas, and a valve controlling an amount of the nitrogen-rich gas received in the first merging chamber for mixing with the oxygen-rich gas, such that the oxidant is discharged from the first merging chamber with the oxygen content at the selected value;

a second merging chamber in fluid communication with the oxidant system and a source of a hydrocarbon fuel, wherein the second merging chamber is configured to receive the hydrocarbon fuel and the oxidant and to discharge a feed stream containing both the hydrocarbon fuel and the oxidant; and

a reformer in fluid communication with the second merging chamber and including a catalytic reactor, wherein the reformer is configured to receive the feed stream from the second merging chamber, to reform the feed stream into a reducing gas, and to discharge the reducing gas;

a temperature sensor positioned downstream of an inlet to the reformer so as to measure at least one of a temperature of catalyst in the catalytic reactor and a temperature of reducing gas output by the catalytic reactor; and

a control system in communication with the temperature sensor, the control system being programmed to control a flow rate of the feed stream, and to control both they oxygen content for the oxidant, via controlling the valve responsive to signals from the temperature sensor, and an oxidant/fuel ratio of the feed stream to maintain a predetermined control temperature while achieving a desired flammables content of the reducing gas output by the reducing gas generator;

wherein the desired flammables content is in the range of approximately 45% to 80% by volume.

2. The reducing gas generator of claim 1 , wherein the oxidant system includes a nitrogen separator having a nitrogen separation membrane configured to extract nitrogen from air supplied thereto, and to discharge the balance of the air supplied as an oxygen-rich gas to the first merging chamber.

3. The reducing gas generator of claim 2 , wherein the oxygen-rich gas has an oxygen content in the range of approximately 21% to 50% by volume.

4. The reducing gas generator of claim 2 , wherein the nitrogen separator is also configured to discharge a nitrogen-rich gas, the nitrogen-rich gas having a nitrogen content greater than that of ambient atmospheric air.

5. The reducing gas generator of claim 4 , further comprising at least one valve configured to combine the nitrogen-rich gas with the oxygen-rich gas to form the oxidant.

6. The reducing gas generator of claim 1 , wherein the reformer is a catalytic reactor.

7. A reducing gas generator, comprising:

an oxidant system configured to provide an oxidant, and configured to provide an oxygen content of the oxidant having a value that exceeds the oxygen content of ambient atmospheric air, wherein the oxidant system is configured to provide the oxidant without the use of stored oxygen;

the oxidant system further including a first merging chamber configured to receive an oxygen-rich gas and a nitrogen-rich gas, and a valve controlling an amount of the nitrogen-rich gas nitrogen-rich gas received in the first merging chamber for mixing with the oxygen-rich gas, such that the oxidant is provided from the first merging chamber with the oxygen content at the selected value;

a second merging chamber in fluid communication with the first merging chamber and a source of a hydrocarbon fuel, so as to discharge a feed stream containing both the hydrocarbon fuel and the oxidant;

a reformer including a catalytic reactor, and being configured to receive the feed stream, to reform the oxidant and fuel into a reducing gas, and to discharge the reducing gas;

a temperature sensor positioned downstream an inlet to the reformer so as to measure at least one of a temperature of catalyst in the catalytic reactor and a temperature of reducing gas output by the catalytic reactor; and

a control system in communication with temperature sensor, the control system being programmed to control a flow rate of the feed stream, and to control both the oxygen content of the oxidant, via controlling the valve responsive to signals from the temperature sensor, and an oxidant/fuel ratio of the feed stream to maintain a predetermined control temperature while achieving a desired flammables content of the reducing gas output by the reducing gas generator;

wherein the desired flammables content is in the range of approximately 45% to 80% by volume.

8. The reducing gas generator of claim 7 , wherein the oxidant system is configured to generate the oxidant from ambient atmospheric air.

9. The reducing gas generator of claim 7 , wherein the oxidant system is configured to provide a variable oxygen content in the oxidant in a range having a maximum value that exceeds the oxygen content of air.

10. The reducing gas generator of claim 7 , wherein the oxidant system is configured to provide a selectable oxygen content of the oxidant in a range of approximately 21% to 50% by volume.

11. The reducing gas generator of claim 7 , wherein the oxidant system is configured to provide a selectable oxygen content in the oxidant in a range of approximately 5% to 50% by volume.

12. The reducing gas generator of claim 7 , wherein the oxidant system includes a nitrogen generator having a nitrogen separation membrane operable to extract nitrogen from air, and wherein the nitrogen generator is configured to discharge the balance of the air supplied thereto as the oxygen-rich gas.

13. The reducing gas generator of claim 12 , wherein the nitrogen generator is also configured to discharge a nitrogen-rich gas, the nitrogen-rich gas having a nitrogen content greater than that of ambient atmospheric air.