Method for supplying oxygen-enriched gas to an oxygen-consuming process
In a method for supplying oxygen-enriched gas to an oxygen consuming process, in which the oxygen-enriched gas with a low nitrogen content is generated by supplying an anode-side feed gas comprising CO 2 to the anode side of a solid oxide electrolysis cell, oxygen is generated on the anode side of the solid oxide electrolysis cell. This way, an anode-side product gas is formed, in which the oxygen-enriched gas comprises at least a part. The oxygen-enriched gas has a low nitrogen content, and the temperature of the oxygen-enriched gas exiting the solid oxide electrolysis cell is between 600 and 1000° C. The method has multiple advantages, first of all as regards energy saving.
1. A method for supplying oxygen-enriched gas to an oxygen-consuming process that is an oxy-calcining process, in which at least one operating solid oxide electrolysis cell is provided having a cathode side and an anode side, and
a) a cathode-side feed gas stream comprising steam or CO 2 or a mixture thereof is supplied to the cathode side of the at least one solid oxide electrolysis cell,
b) at least part of the cathode-side feed gas stream is electrochemically reduced in the solid oxide electrolysis cell, thereby forming a cathode-side product gas stream that is enriched in hydrogen, carbon monoxide or a mixture thereof,
c) at least part of the cathode-side product gas stream is supplied to a hydrogen- and/or carbon monoxide-consuming process,
d) an anode-side feed gas stream comprising CO 2 is supplied to the anode side of the solid oxide electrolysis cell, and
e) oxygen is electrochemically generated on the anode side of the solid oxide electrolysis cell, thereby forming an anode-side product gas stream enriched in oxygen, wherein an oxygen-enriched gas comprising at least part of the anode-side product gas stream enriched in oxygen is fed to the oxygen-consuming process,
the oxygen-enriched gas has a low nitrogen content, the content of nitrogen being below 10 vol %, and
the oxygen-enriched gas exiting the solid oxide electrolysis cell has a temperature in the range of between 600° C. and 1000° C.,
wherein a stream of solid material comprising calcium carbonate is fed to the oxy-calcining process.
2. The method according to claim 1 , wherein the temperature of the oxygen-enriched gas exiting the at least one solid oxide electrolysis cell is between 600° C. and 900° C.
3. The method according to claim 1 , wherein the hydrogen or carbon monoxide or the mixture of hydrogen and carbon monoxide is electrochemically generated on the cathode-side of the at least one solid oxide electrolysis cell and the oxygen electrochemically generated on the anode-side of the at least one solid oxide electrolysis cell are generated at a molar ratio of (H2+CO):O2 of 2:1.
4. The method according to claim 1 , wherein the anode-side product gas enriched in oxygen has an oxygen content of 0<O 2 ≤100%.
5. The method according to claim 1 , wherein at least part of the anode-side product gas is recycled and used as at least part of the anode-side feed gas.
6. The method according to claim 1 , wherein the at least part of the cathode-side product gas is recycled and used as at least part of the cathode-side feed stream.
7. The method according to claim 1 , wherein a flue gas stream is obtained from the oxy-calcining process comprising carbon dioxide and is recycled and used as at least part of the cathode-side feed stream and/or the anode-side feed gas that is fed to the solid oxide electrolysis cell.
8. The method according to claim 1 , wherein the hydrogen- and/or carbon monoxide-consuming process includes methanol production processes, ammonia production processes, hydrotreating processes, methanation processes, hydrogenation processes, carbonylation processes, hydroformulation (oxo synthesis) processes, or oxidative carbonylation processes.
9. The method according to claim 1 , wherein the cathode-side feed stream comprises CO 2 and at least part of the CO 2 in the cathode-side feed gas stream and/or in the anode-side feed gas stream originates from one or more of the following:
metallurgy processes, cement production, carbon capture processes, direct air capture processes and carbon-based fuel combustion processes, including combustion of non-fossil fuels, or other processes where CO 2 is generated in one or more streams.
10. The method according to claim 1 , wherein the nitrogen content in the oxygen-enriched stream is less than 1%.
11. The method according to claim 1 , wherein the nitrogen content in the oxygen-enriched stream is less than 0.1%.
12. The method according to claim 1 , wherein the solid oxide electrolysis cell is operating at thermoneutral voltage or within ±0.2 V/cell from the thermoneutral voltage.
13. A plant comprising:
a solid oxide electrolysis cell having an anode side and a cathode side;
an oxygen-consuming unit that is an oxy-calcining unit; and
a hydrogen- and/or carbon monoxide-consuming unit,
wherein the anode side of the cell is in fluid connection with the oxygen-consuming unit and the cathode side of the cell is in fluid connection with the hydrogen- and/or carbon monoxide-consuming unit, and wherein the plant is configured to operate the method according to claim 1 .
14. A plant comprising:
a solid oxide electrolysis cell having an anode side and a cathode side;
an oxygen-consuming unit that is an oxy-calcining unit; and
a hydrogen- and/or carbon monoxide-consuming unit,
wherein the anode side of the cell is in fluid connection with the oxygen-consuming unit and the cathode side of the cell is in fluid connection with the hydrogen- and/or carbon monoxide-consuming unit, and wherein the plant is configured to operate a method for supplying oxygen-enriched gas to an oxygen-consuming process that is an oxy-calcining process, in which at least one operating solid oxide electrolysis cell is provided having a cathode side and an anode side, and
a) a cathode-side feed gas stream comprising steam or CO2 or a mixture thereof is supplied to the cathode side of the at least one solid oxide electrolysis cell,
b) at least part of the cathode-side feed gas stream is electrochemically reduced in the solid oxide electrolysis cell, thereby forming a cathode-side product gas stream that is enriched in hydrogen, carbon monoxide or a mixture thereof,
c) at least part of the cathode-side product gas stream is supplied to a hydrogen- and/or carbon monoxide-consuming process,
d) an anode-side feed gas stream comprising CO2 is supplied to the anode side of the solid oxide electrolysis cell, and
e) oxygen is electrochemically generated on the anode side of the solid oxide electrolysis cell, thereby forming an anode-side product gas stream enriched in oxygen, wherein an oxygen-enriched gas comprising at least part of the anode-side product gas stream enriched in oxygen is fed to the oxygen-consuming process,
the oxygen-enriched gas has a low nitrogen content, the content of nitrogen being below 10 vol %, and
the oxygen-enriched gas exiting the solid oxide electrolysis cell has a temperature in the range of between 600° C. and 1000° C.,
wherein the oxygen-consuming unit and the hydrogen- and/or carbon monoxide-consuming unit is one and the same oxy-calcining unit.
15. The plant according to claim 13 , wherein the plant comprises control means configured to control the flow from the anode side of the solid oxide electrolysis cell to the oxygen-consuming unit.
16. The plant according to claim 13 , wherein the plant comprises control means configured to control the flow from the cathode side of the solid oxide electrolysis cell to the hydrogen- and/or carbon monoxide-consuming unit.
17. The plant according to claim 13 , wherein the oxygen-consuming unit and the hydrogen- and/or carbon monoxide-consuming unit is one and the same oxy-calcining unit.
18. The method according to claim 1 , wherein the content of nitrogen is below 1 vol %.
19. The method according to claim 1 , wherein the content of nitrogen is below 0.1 vol %.