Electrolysis method and electrolysis system comprising recirculating flushing media

Abstract

An electrolysis method comprising an electrolysis cell (4), which method uses at least one recirculating flushing medium (50, 60). The invention further relates to an electrolysis system, in particular for carrying out the electrolysis method.

Claims

1. An electrolysis method with an electrolysis cell (4), operated within a temperature range of 300 C. to 1500 C., comprising the steps of: supplying a reactant (30) to the electrolysis cell (4), wherein a product gas including hydrogen and carbon monoxide (H.sub.2, CO) is formed at the cathode (43) of the electrolysis cell (4) and oxygen (O.sub.2) is formed at the anode (45) of the electrolysis cell (4), at least partially transporting away the oxygen (O.sub.2) by means of at least one first flushing medium (60) supplied continuously to the electrolysis cell (4), wherein the first flushing medium (60) is inert to oxygen (O.sub.2) at least partially separating the first flushing medium/oxygen mixture (60O.sub.2) in a separating device (12) into the constituents oxygen (O.sub.2) and the at least first flushing medium (60), recirculating by reintroducing the separated at least first flushing medium (60) into the electrolysis cell (4) and discharging the separated oxygen (O.sub.2), wherein the electrolysis cell (4) is a solid oxide electrolyte cell (SOEC), a solid oxide cell (SOC), or a reversible solid oxide cell (rSOC), wherein, for flushing, as the at least first flushing medium (60), an inert gas or a noble gas, at the working temperature and working pressure of the electrolysis, is used, and wherein this is passed through a closed anode flushing circuit, and wherein the at least partial separation of the oxygen (O.sub.2) from the first flushing medium is accomplished with at least one of a separation membrane, a porous separation structure, a sorbent, a pressure change adsorption assembly and a temperature change adsorption assembly.

2. The electrolysis method according to claim 1, wherein an at least partial transport away of the product gas (H.sub.2, CO) occurs by flushing via at least one second flushing medium (50), and wherein the flushing medium/product gas mixture (50H.sub.2/CO) is separated in a separating device (11) into the components product gas (H.sub.2, CO.sub.2) and the at least one second flushing medium (50), wherein the separated least one second flushing medium (50) or flushing medium/product gas mixture (50, H.sub.2/CO) or the flushing medium/product gas mixture (50H.sub.2/CO) or the product gas (H.sub.2, CO) is re-circulated by reintroducing into the electrolysis cell (4) and an at least a partial discharge of the separated product gas (H.sub.2, CO) out of the method, wherein the at least second flushing medium (50) is inert with respect to the product gas (H.sub.2, CO).

3. The electrolysis method according to claim 1, wherein less than 100% of the reactants (30) are converted into product gas (H.sub.2, CO), so that an at least partial removal of the product gas (H.sub.2, CO) takes place via the unreacted reactants (30), wherein the product gas/reactant mixture (H.sub.2/CO30) is at least partially separated in a separating device (11, 12) into the constituents product gas (H.sub.2, CO) and reactant (30), wherein there occurs a recirculation of the separated reactant (30) or product gas-reactant mixture (H.sub.2/CO30) and an at least partial discharge of the separated product gas (H.sub.2, CO) from the method.

4. The electrolysis method according to claim 1, wherein the electrolysis cell is operated in a temperature range of from 600 C. to 1000 C.

5. An electrolysis method with an electrolysis cell (4), operated within a temperature range of 300 C. to 1500 C. comprising the steps of: supplying a reactant (30), wherein water (H.sub.2O) and carbon dioxide (CO.sub.2) are used as the reactant (30) in the form of a gas, steam and/or gaseous vapour, to the electrolysis cell (4), wherein product gasses (H.sub.2, CO) formed are hydrogen (H.sub.2) and carbon monoxide (CO) at the cathode (43) of the electrolysis cell (4) and oxygen (O.sub.7) is formed at the anode (45) of the electrolysis cell (4), at least partially transporting away the oxygen (O.sub.7) by means of at least one first flushing medium (60) supplied continuously to the electrolysis cell (4), wherein the first flushing medium (60) is inert to oxygen (O.sub.2) at least partially separating the first flushing medium/oxygen mixture (60O.sub.2) in a separating device (12) into the constituents oxygen (O.sub.7) and the at least first flushing medium (60), recirculating by reintroducing the separated at least first flushing medium (60) into the electrolysis cell (4) and discharging the separated oxygen (O.sub.2), wherein the electrolysis cell (4) is a solid oxide electrolyte cell (SOEC), a solid oxide cell (SOC), or a reversible solid oxide cell (rSOC), wherein, for flushing, as the at least first flushing medium (60), an inert gas or a noble gas, at the working temperature and working pressure of the electrolysis, is used, and wherein this is passed through a closed anode flushing circuit, and wherein the at least partial separation of the oxygen (O.sub.2) from the first flushing medium is accomplished with at least one of a separation membrane, a porous separation structure, a sorbent a pressure change adsorption assembly and a temperature change adsorption assembly.

6. The electrolysis method according to claim 1, wherein prior to reintroduction into the cathode flushing circuit (15)/anode flushing circuit (16) a heating or compressing of at least the first (60)/second (50) flushing medium is carried out.

7. The electrolysis system for carrying out an electrolysis method according to claim 1, wherein the electrolysis cell system has at least three separate pressure chambers including an anode space (5), a cathode space (3), which together form the electrolysis cell (4), and a container space (2), and wherein the anode space (5) and the cathode space (3) are arranged within the container space (2); for supplying a reactant (30) into the cathode chamber (3) and for supplying at least one first flushing medium (60) into the anode space (5) in each case at least one media feed line (31, 51) is provided; for removing from the anode space (5) the at least first flushing medium (60) and the oxygen (O.sub.2) produced by electrolysis and for the removing from the cathode space (3) a product gas (H.sub.2, CO) which is formed by the electrolysis, in each case at least one output line (32, 52) is provided; either the anode space (5) or the cathode space (3) is connected to the container space (2), so that a flow of gas between the two connected chambers (5-2/3-2) is possible and at least one flushing circuit (15, 16) is provided, so that at least the anode space (5) can be flushed with the first flushing medium (60).

8. The electrolysis system according to claim 7, wherein downstream of the electrolysis cell (4) in the at least one flushing circuit (15, 16) at least one separating device (11, 12) is provided for separating the at least first flushing medium (60)/oxygen (O.sub.2), wherein the at least first flushing medium (60) is recirculated via the at least one flushing circuit (15, 16) and the oxygen (O.sub.2) is removed from the electrolysis system via a line (54).

9. The electrolysis system according to claim 7, wherein within the container space (2) multiple electrolysis cells (4) with anode spaces (5) and cathode spaces (3) are provided, wherein the anode spaces (5) are connected to each other and the cathode spaces (3) are connected to each other, so that a plurality of cathode spaces (3) are connected to one another to form a common cathode space and a plurality of anode spaces (5) form a common anode space.

10. The electrolysis system according to claim 7, wherein for supplying the gas into the anode chamber (5) and/or the cathode chamber (3) pressure control units (23, 33, 34, 53) are provided, by means of which the respective pressure in the pressure chambers (2, 3, 5) can be adjusted.

11. The electrolysis system according to claim 7, wherein two flushing circuits (15, 16) are provided, so that the anode space (5) is flushable with a first flushing medium (50) and the cathode space (3) is flushable with a second flushing medium (60) and/or the reactants (30).

12. The electrolysis system according to claim 7, wherein for recirculation by means of the at least one flushing circuit (15, 16), a recirculation blower and/or a jet pump and/or heater/heat exchanger (14, 14) is provided.

13. The electrolysis system according to claim 7, wherein during the start-up and/or shutdown operation of the electrolysis cell (4) a temporary connection between the anode space (5) and the cathode space (3) is provided and can be switched, so that a gas flow between the two connected chambers (3, 5) during the period of the electrolysis is possible during the start-up and/or shutdown operation.

14. The electrolysis system according to claim 8, wherein a cooling device for cooling the media (30, 50, 60) supplied to the separating device (11, 12) is provided, wherein the heat which can be extracted there can be used recuperatively for heating the medium(s) to be fed.

15. The electrolysis system according to claim 7, wherein the media supply line(s) (51) and or discharge line(s) (52) for the anode terminate in the container space (2) when the anode space (5) is connected to the container space (2).

16. The electrolysis system according to claim 7, wherein the media supply line(s) (31) and or discharge line(s) (32) for the cathode terminate in the container space (2) when the cathode space (3) is connected to the container space (2).

17. The electrolysis system according to claim 7, wherein the first (60) and the second flushing medium (50) are identical.

18. The electrolysis system according to claim 7, wherein the first (60) and the second flushing medium (50) are nitrogen (N.sub.2).

Description

(1) Preferred embodiments of the present invention, the structure, function and advantages thereof, are explained in more detail below with reference to the figures, in which there is shown in:

(2) FIG. 1 an embodiment of the method according to the invention in which a flushing of cathode and anode as well as a differential pressure control between the individual pressure chambers is performed on an electrolyser module schematically shown in the cross-section;

(3) FIG. 2 schematically an embodiment of the method according to the invention with a pressure control at an electrolysis cell by a permanent connection of two pressure chambers;

(4) FIG. 3 schematically an embodiment of the method according to the invention, in which a pressure control is performed at an electrolysis cell by connecting a cathode chamber with an anode space of the electrolysis cell in a startup and/or shutdown operation of the electrolysis method; and

(5) FIG. 4 schematically a further embodiment of the method according to the invention in which for pressure control a cathode compartment and an anode compartment of an electrolysis cell are permanently connected to the process output.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) In the figures, described in detail in the following, the same reference symbols designate the same features of the present invention, wherein an already described description of the respective identically designated feature also applies to the following figures.

(7) FIG. 1 illustrates an embodiment of the present invention according to a first aspect of the method according to the invention by means of an electrolyser module 1, which is shown schematically in cross-section.

(8) The illustrated electrolyser module 1 has an electrolysis cell 4 with a cathode 43, an anode 45 and an electrolyte 44 located between the cathode 43 and the anode 45. For the sake of clarity, only a single electrolysis cell 4 is shown for the electrolysis module 1. In practice, however, the electrolyser module 1 typically consists of a stack of electrolysis cells 4.

(9) A cathode compartment 3 is provided at the cathode 43. An anode space 5 is located at the anode 45. A container space 2 is provided around the cathode 43, the anode 45, the cathode space 3 and the anode space 5. The electrolysis cell 1 can also be enclosed by further containers or container elements (not shown). In other variants, not shown, of the present invention, several cathode spaces 3 and/or several anode spaces 5 and/or several container spaces 2 can also be provided.

(10) The electrolysis cell 4 used in the example of FIG. 1 is a solid oxide electrolysis cell (SOEC) which uses a solid oxide, such as a ceramic, as an electrolyte 44. As material for the cathode 43 and/or the anode 45, for example, nickel or various ceramics can be used. However, the active principle according to the invention also functions in alkaline, acidic or polymer electrolyte electrolysis cells.

(11) The electrolysis cell 4 shown in FIG. 1 operates at high temperatures between 600 and 1000 C., for example at approximately 850 C. In other embodiments of the present invention, the method according to the invention can also be used at other, lower or even higher temperatures.

(12) A reactant 30 in the form of a reactant gas or reactant steam is fed to the cathode 43 of the electrolysis cell 4 via at least one feed line 31. In the exemplary embodiment of FIG. 1, steam is used as reactant 30. In other exemplary embodiments of the present invention which are not shown, carbon dioxide (CO.sub.2) and/or another gas or gas mixture which can be cleaved by means of electrolysis can also be used as reactant 30. A mixture of steam and CO.sub.2 can also be used as reactant 30. The reactant 30 does not have to have absolute purity but can also comprise components of other gases.

(13) Between the cathode 43 and the anode 45, a voltage is applied in the electrolysis method carried out in the electrolysis cell 1, which causes oxygen ions (O.sub.2) of the reactant 30 to decomposed in the electrolysis and to be led from the cathode 43 to the anode 45 via the electrolyte 44. At the cathode 43, a reduction of the reactant 30 takes place for this purpose. When steam is used as the reactant 30, gaseous hydrogen (H.sub.2) is formed at the cathode 43, and when carbon dioxide is used as the reactant 30, gaseous carbon monoxide (CO) is formed at the cathode 43. An oxidation takes place at the anode 45. In both cases, gaseous oxygen (O.sub.2) is formed at the anode 45.

(14) In the electrolysis method illustrated in FIG. 1, the electrolysis cell 4 thus serves to convert water or steam into hydrogen and oxygen. In particular, the hydrogen formed is suitable as an energy carrier. For example, it can be further processed into hydrocarbon(s), such as methanol, in subsequent process steps, as described, for example, in the publication DE 10 2006 035 893 A1.

(15) In the embodiment of FIG. 1, a flushing of the cathode 43 as well as the anode 45 is carried out at the respective electrode 43, 45. In other variants of the present invention (not shown), flushing can also be provided only at the anode 45 or only at the cathode 43. The flushing takes place in each case with a flushing medium 50, 60, which can be the same or else different at the cathode 43 and the anode 45.

(16) Preferably, but not necessarily, the flushing medium 50 used is an inert gas such as, for example, nitrogen, which does not react chemically with the product gas formed at the respective electrode 43, 45. In the electrolysis method according to the invention steam, carbon dioxide, oxygen and/or air can be used as flushing medium 60 on the cathode 43, and steam and/or carbon dioxide as flushing medium 50 at the anode 45.

(17) Both the cathode flush medium 50 used at the cathode 43 and the anode flushing medium 60 used at the anode 45 are each guided in a flushing circuit, the cathode flushing circuit 15 and the anode flushing circuit 16, respectively.

(18) The cathode flushing medium 50 is fed into the electrolysis module 1 via the same supply line 31 of the cathode 43 of the electrolysis cell 4, via which also the reactant 30 is supplied to the cathode 43. In another exemplary embodiment of the present invention, the cathode flushing medium 50 can also be fed to the cathode 43 via a separate supply line. The reactant 30 and the cathode flushing medium 50 are pressurized by a compressor 13. The pressurized reactant-cathode flushing medium mixture 30+50 is subsequently heated in a heater 14 to the operating temperature of the electrolysis cell 4. The reactant-cathode flushing medium mixture 30+50, which is at working pressure and working temperature, is then fed into the cathode chamber 3.

(19) Within the cathode chamber 3, the reactant 30 and the cathode flushing medium 50 are passed to the cathode 3. By means of the reduction reaction taking place at the cathode 43, the reactant 30, that is to say the steam supplied in the exemplary embodiment shown, is at least partially converted to hydrogen.

(20) The cathode flushing medium 50 with its flow accompanies the hydrogen formed at the cathode 43, including the unreacted reactant 30. In other embodiments of the electrolysis method according to the invention, in which carbon monoxide is formed instead of or in addition to hydrogen at the cathode 43, the cathode flushing medium 50 carries the carbon monoxide formed at the cathode 43 as well as the unreacted carbon dioxide. In the embodiment of FIG. 1, a cathode flush medium/carbon mixture 30+50+H.sub.2 containing steam is thus produced in the cathode chamber 3, or a cathode flushing medium/carbon monoxide mixture 30+50+CO containing carbon dioxide in other variants of the electrolysis method.

(21) The cathode flushing medium/hydrogen mixture 30+50+H.sub.2 can then be fed to a separating device 11. The separating device 11 can, for example, separate hydrogen of the cathode flushing medium/hydrogen mixture 30+50+H.sub.2 from the further media 30+50 of the cathode flushing medium/hydrogen mixture 30+50+H.sub.2. However, it is also possible, for example, to separate the steam from the cathode flushing medium/hydrogen mixture 30+50+H.sub.2 by means of a condensation device (not shown in FIG. 1).

(22) In variants of the electrolysis method according to the invention, in which instead of or in addition to hydrogen, carbon monoxide is generated at the cathode 43, a carbon monoxide separation can be used instead of the hydrogen separation in which, for example, carbon monoxide of the cathode flushing medium/carbon monoxide mixture 30+50 is separated from the further media 30+50. The separated hydrogen or the separated carbon monoxide can then be discharged via a separate line 36. Typically, the recovered hydrogen or carbon monoxide is subsequently further processed.

(23) However, a substance separation need not absolutely be carried out with the method according to the invention.

(24) The cathode flushing medium/hydrogen mixture 30+50+H.sub.2, modified or unchanged with regard to its composition by substance separation, or the cathode flushing medium/carbon monoxide mixture 30+50+CO, which is altered or unchanged with respect to its composition by substance separation, is subsequently again fed within the cathode flushing circuit 15 to the cathode compartment 3. This can, as exemplarily illustrated by means of the electrolysis module 1, take place via the same supply line 31, via which also fresh reactant 30 or fresh cathode flush medium 50 is supplied to the cathode chamber 3. It is to be emphasized that the schematic system shown in FIG. 1 illustrates only the principle of the electrolysis method according to the invention, whereby numerous modifications may be made to the line routing, the number and arrangement of the lines, the line connections, the employed fittings, compressors, heaters, heat exchangers, blowers, etc.

(25) The anode flushing medium 60 is fed to the anode space 5 via a feed line 51. The anode flushing medium 60 is here first elevated in a compressor 13 to a working pressure of the electrolysis cell 1. Thereupon, the anode flush medium 6 is heated by a heater 14.

(26) In other embodiments of the present invention (not shown), compressors 13 and heaters 14 or compressors 13 and heaters 14 can also be provided in reverse order. In addition, heat exchangers can also be used instead of or in addition to the heaters 14, 14. It is also possible to dispense with heaters, heat exchangers and/or compressors.

(27) The anode flushing medium 60 which is raised to the working pressure and working temperature of the electrolysis cell 4 is fed to the anode chamber 5 via the line 51. Within the anode chamber 5, the anode flushing medium 60 flows past the anode 45. In this case, the flow of the anode flush medium 60 entrains the oxygen formed at the anode 45. The oxygen-enriched anode flush medium 60, after flowing by the anode 45, is fed, in this illustrative example, to an extractor or separator 12. Oxygen and anode flush medium 60 are at least partially separated from each other by means of the separation device 12. The separated oxygen is discharged via a line 54 to the outside.

(28) The oxygen-depleted anode flushing medium/oxygen mixture is returned to the anode space 5 via the anode flushing circuit 16.

(29) At least one recirculation blower can be used in the cathode flushing circuit 15 and/or in the anode flushing circuit 16, which promotes conveyance of at least one reactant of the electrolysis and/or at least one product gas of the electrolysis and/or at least one flushing medium of the electrolysis from the process output to the process input of the electrolysis cell 4. For promoting recirculation, the compressors 13, 13 described above can also be used.

(30) For separating individual media from the gas mixtures resulting from the process according to the invention, different devices and/or methods can be used in the present invention. For example, the separating device used can have at least one separation membrane and/or a porous separation structure, to which the mixture to be separated is guided and which is permeated by the medium to be separated at a different rate from the other medium contained in the mixture.

(31) Furthermore, it is possible to provide a separating device with at least one sorbent, to or into which the respective mixture is passed, the sorbent adsorbing the medium to be separated more strongly or more weakly than the other medium contained in the mixture. As a sorbent, for example, a separating liquid can be used.

(32) A pressure and/or alternating adsorption process, a cryogenic gas separation and/or a chemical separation can also be used to separate the components of the gas mixture formed in the respective rinse circuits. In order to chemically separate the constituents of the particular mixture from one another, for example, burning can be used.

(33) The at least one cathode compartment 3, the at least one anode compartment 5 and the at least one container compartment 2 of the electrolyser module 1 are each formed as separate pressure chambers, i.e., as spaces in which the internal pressure of the respective compartment can be formed or adjusted separately from the internal pressure of the other compartments. In this way, at least three separate pressure chambers are present on the electrolysis module 1 according to FIG. 1: at least one cathode chamber 3, which contains water vapor, hydrogen and the cathode rinse medium 50, which can also be water vapor and/or hydrogen; at least one anode space 5, which has oxygen and the anode rinsing medium 60 in its interior, and the surrounding pressure vessel 2 of the electrolysis module 1.

(34) The container space 2 is filled via a line 21 with a gaseous medium such as, for example, nitrogen or another inert gas. The gas can be discharged from the container space 2 via a line 22.

(35) Since the thin ceramic membranes of the electrolyte 44 of the electrolysis cell 4, which are used in the example, are sensitive to differential pressures in the range of some 10 . . . 100 mbar, a very precise regulation of the volume flows of the supplied media is necessary to adjust the internal pressures in the different pressure chambers of the electrolysis module 1 in consideration of the mass flow in of the electrolysis cell 4.

(36) In addition, the pressure within the pressure vessel 2 must be adjusted close to the pressure of the cathode space 3 and the anode space 5 in order to keep the material stress inside the container space 2 as low as possible. The phase of the system start is particularly critical when all three pressure chambers 2, 3, 5 of the electrolysis module 1 have to be brought from ambient pressure into the operating pressure of the electrolysis cell 4 synchronously.

(37) The present invention includes various variants to enable such pressure matching.

(38) For example, in the electrolyser module 1 of FIG. 1, valves 23, 33, 53 are provided in the line 22 leading from the container space 2, the line 32 emerging from the cathode space 3, and the line 52 emerging from the anode space 5. An generic valve for regulating the absolute pressure of the electrolysis module 1 can be used by the valves 23, 33, 53, while the two other valves can be used to regulate the differential pressure to the line with the absolute pressure control.

(39) In FIGS. 2 to 4, only the components and media lines relevant to the pressure control are shown for a simplified representation of the pressure control principles used according to the invention. The pressure control principles illustrated in FIGS. 1 to 4 can be applied to different types of electrolysis cells together with or independently of the electrode flushings discussed with reference to FIG. 1.

(40) FIG. 2 shows an embodiment of the electrolysis method according to the invention on the basis of a schematically illustrated electrolysis cell 1a. In the electrolysis cell 1a, a connection between the pressure vessel 2 and the anode space 5 is provided via a line 25. Via the line 25, flushing medium can be directed into the interior of the container chamber 2 through the line 51 leading to the anode chamber 5. As a result, the same pressure as in the anode space 5 is established in the container space 2, so that the differential pressure control used in FIG. 1 between the container space 2 and the anode space 5 can be dispensed with here.

(41) FIG. 3 shows an embodiment of the electrolysis method according to the invention on the basis of a schematically illustrated electrolysis cell 1b. In the electrolysis cell 1b, in which the container space 2 is connected to the anode compartment 5 via a line 25, a connection of the cathode compartment 3 with the anode compartment 5 is produced in a start-up mode and/or a shut-down mode of the electrolysis cell 4. This connection is realized by a valve 34 provided between the media feed lines 31 and 51. Thus, a pressure equalization can be established between the cathode chamber 3 and the anode chamber 5 in the start-up operation and/or the withdrawal operation of the electrolysis cell 4 via a supply of flushing medium. In this way, the differential pressure control between the cathode chamber 3 and the anode chamber 5 used in the electrolysis module 1 of FIG. 1 can be dispensed with in the start-up operation and/or the starting-up operation of the electrolysis cell 4, and all the pressure chambers 2, 3 are evenly brought to a certain pressure level. In this embodiment of the method according to the invention, the absolute pressure can be regulated via the valves 33 and 53 or via only one of the valves 33, 53, the other being closed.

(42) FIG. 4 shows an embodiment of the electrolysis method according to the invention on the basis of a schematically illustrated electrolysis cell 1c. The electrolysis cell 1c is based on the electrolysis cell 1b from FIG. At the method startup, in the case of the electrolysis cell 1c, the line 32 leading from the cathode chamber 3 and the line 52 leading from the anode chamber 5 are connected. A separating device 11 is provided in the line 32 leading from the cathode compartment 3, wherein, in the example shown, hydrogen is separated from the gas mixture formed at the cathode 43 by the separating device 11 and the separated hydrogen is discharged via a line 36. Due to the permanent connection between the cathode chamber 3 and the anode space 5 at the process output, the differential pressure control applied in the electrolysis module 1 from FIG. 1 between the cathode chamber 3 and the anode chamber 5 can be omitted. Only one absolute pressure regulator is required, which in the embodiment of FIG. 4 is realized by the valve 33 at the process outlet.

(43) As shown in FIG. 4, a further separation device 11 can follow the separating device 11 for hydrogen, in which the remaining steam 30 can be wholly or partially separated from the cathode flushing medium 50, whereupon the separated steam 30 can be recirculated and is fed to a process gas inlet of the electrolysis cell 1c. Furthermore, oxygen can also be separated from the anode flush medium 60 by a further separating device 12 from the gas mixture located in the line 52. The connection of the two lines 52 and 32 after the respective separating devices 11, 11, 12 essentially contains the flushing media 50, 60. If a flushing medium is used only on the anode side or only on the cathode side of the electrolyte module 1, 1a, 1b, 1c, or if the same flushing medium is used on both sides, this flushing medium can also be recirculated.

REFERENCE LIST

(44) 1, a, 1b, 1c electrolysis modules 2 container space 3 cathode space 4 electrolysis cell 5 anode space 6 anode flushing medium 11,11 separating device 12 separating device 13, 13 compressors 14, 14 heater/heat exchanger 15 cathode flushing circuit 16 anode flushing circuit 21 line 22 line 23 pressure control unit 25 line 30, 30 reactant 31 media supply 32 line 33 pressure control unit 34 pressure control unit 36 line 43 cathode 44 electrolyte 45 anode 50, 50 second flushing medium 51 media feed line 52 line 53 pressure control unit 54 line 60, 60 first flushing medium CO carbon dioxide H.sub.2, CO product gas H.sub.2/CO30 product gas/reactant mixture H.sub.2 hydrogen H.sub.2O water N.sub.2 nitrogen O.sub.2 oxygen RSOC reversible solid oxide cell SOEC solid oxide electrolysis cell SOC solid oxide cell 50H.sub.2/CO flushing medium/product gas mixture 60O.sub.2 flushing medium/oxygen mixture