Electrolysis method and electrolysis system comprising recirculating flushing media

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 2 , CO) is formed at the cathode ( 43 ) of the electrolysis cell ( 4 ) and oxygen (O 2 ) is formed at the anode ( 45 ) of the electrolysis cell ( 4 ),

at least partially transporting away the oxygen (O 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 2 )

at least partially separating the first flushing medium/oxygen mixture ( 60 —O 2 ) in a separating device ( 12 ) into the constituents oxygen (O 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 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 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 2 , CO) occurs by flushing via at least one second flushing medium ( 50 ), and wherein the flushing medium/product gas mixture ( 50 —H 2 /CO) is separated in a separating device ( 11 ) into the components product gas (H 2 , CO 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 2 /CO) or the flushing medium/product gas mixture ( 50 —H 2 /CO) or the product gas (H 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 2 , CO) out of the method, wherein the at least second flushing medium ( 50 ) is inert with respect to the product gas (H 2 , CO).

3. The electrolysis method according to claim 1 , wherein less than 100% of the reactants ( 30 ) are converted into product gas (H 2 , CO), so that an at least partial removal of the product gas (H 2 , CO) takes place via the unreacted reactants ( 30 ), wherein the product gas/reactant mixture (H 2 /CO— 30 ) is at least partially separated in a separating device ( 11 , 12 ) into the constituents product gas (H 2 , CO) and reactant ( 30 ), wherein there occurs a recirculation of the separated reactant ( 30 ) or product gas-reactant mixture (H 2 /CO— 30 ) and an at least partial discharge of the separated product gas (H 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 2 O) and carbon dioxide (CO 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 2 , CO) formed are hydrogen (H 2 ) and carbon monoxide (CO) at the cathode ( 43 ) of the electrolysis cell ( 4 ) and oxygen (O 7 ) is formed at the anode ( 45 ) of the electrolysis cell ( 4 ),

at least partially transporting away the oxygen (O 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 2 )

at least partially separating the first flushing medium/oxygen mixture ( 60 —O 2 ) in a separating device ( 12 ) into the constituents oxygen (O 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 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 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 2 ) produced by electrolysis and for the removing from the cathode space ( 3 ) a product gas (H 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 2 ), wherein the at least first flushing medium ( 60 ) is recirculated via the at least one flushing circuit ( 15 , 16 ) and the oxygen (O 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 2 ).