Staged electrolyte membrane

Claim 2

A process of separating oxygen from a feed gas stream including a mixture of oxygen and at least one other gas to produce enriched oxygen permeate and oxygen-depleted retentate gas, the process comprising: introducing the feed gas into a first gas chamber of a first process stage of at least two process stages arranged in a series feed relationship, the first chamber being separated from a second gas chamber by a first electrolyte membrane; selecting a first oxygen flux through the first membrane and providing a first electrical current to and a first voltage across the first membrane to drive oxygen substantially at the first flux to obtain oxygen depleted retentate gas from the first chamber and enriched oxygen permeate from the second chamber; delivering oxygen-depleted retentate gas from the first process stage to a third gas chamber of a second process stage, the third chamber being separated from a fourth gas chamber by a second electrolyte membrane; and selecting a second oxygen flux through the second membrane and providing a second electrical current to and a second voltage across the second membrane to drive oxygen substantially at the second flux to obtain oxygen depleted retentate gas from the third chamber and enriched oxygen permeate from the fourth chamber, the second current being smaller than the first current and the second voltage being larger than the first voltage.

Claim 3

The process of claim 1 wherein less than six stages are utilized.

Claim 4

The process of claim 1 wherein the second voltage is at least ten percent larger than the first voltage, both voltages being calculated according to the Nernst Equation.

Claim 5

The process of claim 1 wherein the second stage is one of at least two stages successive to the first stage, and each successive stage utilizes a voltage an least ten percent larger than the voltage the preceding stage, all voltages being calculated according to the Nernst Equation.

Claim 6

The process of claim 4 wherein each successive stage utilizes a smaller current than the current of the preceding stage.

Claim 7

The process of claim 5 wherein the power consumed by each successive stage is less than fifty percent of the power consumed by the preceding stage.

Claim 8

The process of claim 1 wherein at least one of the stages has at least two modules, each module including an electrolyte membrane.

Claim 9

The process of claim 7 wherein the modules within the stage are connected electrically in series and are connected in a parallel feed arrangement.

Claim 10

The process of claim 7 wherein the modules within the stage are connected electrically in series and are connected in a series feed arrangement.

Claim 11

The process of claim 1 wherein the electrolyte membrane in one of the stages is formed of a different material than is present in the membranes in the other stages.

Claim 12

The process of claim 1 wherein the feed gas is air.

Claim 13

The process of claim 1 including withdrawing the enriched oxygen permeate from the second and fourth gas chambers of the first and second stages as an oxygen-containing product stream, and withdrawing the oxygen-depleted retentate gas from the second process stage as a retentate product stream.

Claim 14

The process of claim 1 wherein the composition of the retentate gas obtained from the third chamber is less than about five percent oxygen.

Claim 15

The process of claim 1 wherein the feed gas is heated to a temperature between 400° C. and 1200° C.

Claim 16

A process of separating oxygen from a feed gas stream including a mixture of oxygen and at least one other gas to produce enriched oxygen permeate and oxygen-depleted retentate gas, the process comprising: introducing the feed gas into a first gas chamber of a first process stage of at least three process stages arranged in a series feed relationship, the first chamber being separated from a second gas chamber by a first electrolyte membrane; selecting a first oxygen flux through the first membrane and providing a first electrical current to and a first voltage across the first membrane to drive oxygen substantially at the first flux to obtain oxygen depleted retentate gas from the first chamber and enriched oxygen permeate from the second chamber; delivering oxygen-depleted retentate gas from the first process stage to a third gas chamber of a second process stage, the third chamber being separated from a fourth gas chamber by a second electrolyte membrane; selecting a second oxygen flux through the second membrane and providing a second electrical current to and a second voltage across the second membrane to drive oxygen substantially at the second flux to obtain oxygen depleted retentate gas from the third chamber and enriched oxygen permeate from the fourth chamber, the second current being smaller than the first current and the second voltage being larger than the first voltage; the second stage being one of at least two stages successive to the first stage, each successive stage utilizing a voltage at least ten percent larger than the voltage of the preceding stage, all voltages being calculated according to the Nernst Equation; each successive stage utilizing a smaller current than the current of the preceding stage; and at least one of the stages having at least two modules, each module including an electrolyte membrane.

Claim 17

A process of separating oxygen from a feed gas stream including a mixture of oxygen and at least one other gas to produce enriched oxygen permeate and oxygen-depleted retentate gas, the process comprising: introducing the feed gas into a first gas chamber of a first process stage of at least three process stages arranged in a series feed relationship, the first chamber being separated from a second gas chamber by a first electrolyte membrane; selecting a first oxygen flux through the first membrane and providing a first electrical current to and a first voltage across the first membrane to drive oxygen substantially at the first flux to obtain oxygen depleted retentate gas from the first chamber and enriched oxygen permeate from the second chamber; delivering oxygen-depleted retentate gas from the first process stage to a third gas chamber of a second process stage, the third chamber being separated from a fourth gas chamber by a second electrolyte membrane; selecting a second oxygen flux through the second membrane and providing a second electrical current to and a second voltage across the second membrane to drive oxygen substantially at the second flux to obtain oxygen depleted retentate gas from the third chamber and enriched oxygen permeate from the fourth chamber, the second current being smaller than the first current and the second voltage being larger than the first voltage; the second stage being one of at least two stages successive to the first stage, each successive stage utilizing a voltage at least ten percent larger than the voltage of the preceding stage, all voltages being calculated according to the Nernst Equation; each successive stage utilizing a smaller current than the current of the preceding stage; and at least one of the stages having at least two modules, each module including an electrolyte membrane.

Claim 18

The process of claim 15 wherein each electrolyte membrane includes a cathode connected to a retentate side and an anode connected to a permeate side of the membrane, the cathode and anode being energized to drive oxygen substantially at an oxygen flux selected for that membrane.

Claim 19

The process of claim 16 wherein the modules within at least the first and second process stages are connected electrically in series and are connected in a parallel feed arrangement.

Claim 20

The process of claim 16 wherein the modules within at least the first and second process stages are connected electrically in series and are connected in a series feed arrangement.

Claim 21

The process of claim 16 wherein the power consumed by each successive stage is less than fifty percent of the power consumed by the preceding stage to that successive stage.

Claim 22

The process of claim 16 wherein the electrolyte membrane in one of the stages is formed of a different material than is present in at least one of the membranes in at least one of the other stages.