High-temperature and high-pressure electrolyser of allothermal operation

1. An electrolyzer for high temperature electrolysis capable of operating in an allothermal mode, comprising:

an enclosure,

at least one electrolysis plate including an anode and a cathode in combination, and

means for heating an active fluid intended to undergo high temperature electrolysis with an operating temperature of at least 750° C.,

wherein the enclosure is capable of maintaining an electrolyte bath under high or very high pressure of several tens of bars, the electrolytic bath being formed by the active fluid, said means for heating is disposed in the enclosure and uses a heat transfer fluid, the active fluid is a gas, the means for heating includes at least one heating plate parallel and adjacent to the electrolysis plate, the heating plate substantially having a same size as the electrolysis plate and includes a metal casing in which a heat exchange body is disposed, including a plurality of channels extending between an end supplied with hot heat transfer fluid and an end connected to cold heat transfer fluid manifold, the heating plate is distinct from the electrolysis plate and not in contact with the electrolysis plate, and the electrolysis plate and the heating plate are immersed in the active fluid.

2. The high temperature electrolyzer according to claim 1 , wherein the heat transfer fluid is a gas under high pressure.

3. The electrolyzer according to claim 1 , wherein the heat transfer fluid is molten metal.

4. The electrolyzer according to claim 1 , wherein the heat transfer fluid is formed by molten salts.

5. The high temperature electrolyzer according to claim 1 , wherein the enclosure includes a lower chamber, a middle box, and an upper chamber.

6. The high temperature electrolyzer according to claim 5 , wherein the electrolysis plate includes a central body formed by an electrically conducting core as a plate, covered on both faces of the central body by the anode, the anode covered with an electrolyte, the electrolyte covered by the cathode and an electrically conducting frame surrounding the central body and exerting a compressive force on layers forming the central body.

7. The high temperature electrolyzer according to claim 6 , wherein an anode pin is connected to the core in order to connect the anode to a source of electric current and the cathode is electrically connected to the frame, which bears a cathode pin, the anode pin and the cathode pin being disposed at ends opposite to each other of the electrolysis plate.

8. The high temperature electrolyzer according to claim 6 , including at least one channel made in the anode and a collecting end piece connected to the at least one channel for bringing a gas produced at the anode to an outside of the electrolyzer, the pressure of the gas produced at the anode being less than that of the electrolyte bath at the cathode, the anode, the electrolyte and the cathode being thereby pressed against each other.

9. The electrolyzer according to the claim 8 , including channels formed by grooves made in the core and reservoirs, one of the reservoirs being connected to the collecting end piece, connected to a main manifold.

10. The high temperature electrolyzer according to claim 9 , including a plurality of electrolysis plates and a plurality of heating plates, the heating plates being disposed between two electrolysis plates.

11. The high temperature electrolyzer according to claim 10 , wherein the electrolysis plates are electrically connected in series, adjacent electrolysis plates being mounted in the enclosure so that an anode pin of an electrolysis plate passes through the lower chamber and an anode pin of an adjacent electrolysis plate passes through the upper chamber.

12. The high temperature electrolyzer according to claim 10 , wherein the electrolysis plates are electrically connected in parallel.

13. The high temperature electrolyzer according to claim 10 , wherein the electrolysis plates are distributed in groups electrically connected in parallel, the groups being connected together in series, the electrolysis plates of a same group being mounted in the middle box so that all the anode pins of these plates pass through the same lower or upper chambers, two adjacent groups having their anode pins not passing through the same chamber.

14. The high temperature electrolyzer according to claim 10 , wherein the electrolysis plates are mounted in the enclosure by slides made on the middle box, an electric insulator being provided between the electrolysis plates and the slides, and wherein the heating plates are also mounted in slides provided on the middle box.

15. The high temperature electrolyzer according to claim 10 , wherein the upper and lower chambers include apertures that let through end pieces for heat transfer fluid that collect the gas produced at the anode and anode and cathode pins and a main passage for the active fluid.

16. The high temperature electrolyzer according to claim 15 , wherein the apertures that let through the anode and cathode pins are covered by a channel that cools electric connections.

17. The high temperature electrolyzer according to claim 15 , wherein the apertures that let through the anode and cathode pins are disposed in a recess of the upper and lower chambers.

18. The high temperature electrolyzer according to claim 15 , wherein a connecting plate is disposed around the anode and/or cathode pins on the upper chamber outside the upper chamber and a connecting plate is disposed around the anode and/or cathode pins on the lower chamber outside the lower chamber.

19. An installation for producing gas by electrolysis including:

at least one electrolyzer according to claim 10 ,

an electric power supply with a given voltage,

wherein the electrolysis plates are grouped in several groups, the electrolysis plates being connected in series within a same group and the groups being connected in parallel, the number of electrolysis plates of each group being selected so that a voltage of each group of electrolysis plates is close to the given voltage of the electric power supply.

20. A method comprising:

producing dihydrogen and dioxygen from water with an electrolyzer, the electrolyzer including

an enclosure,

at least one electrolysis plate including an anode and a cathode in combination, and

means for heating an active fluid intended to undergo high temperature electrolysis with an operating temperature of at least 750° C.,

wherein the enclosure is capable of maintaining an electrolyte bath under high or very high pressure of several tens of bars, the electrolytic bath being formed by the active fluid, said means for heating is disposed in the enclosure and uses a heat transfer fluid, the active fluid is a gas, the means for heating includes at least one heating plate disposed parallel and adjacent to the electrolysis plate, the heating plate substantially having a same size as the electrolysis plate and includes a metal casing in which a heat exchange body is disposed, including a plurality of channels extending between an end supplied with hot heat transfer fluid and an end connected to cold heat transfer fluid manifold, the heating plate is distinct from the electrolysis plate and not in contact with the electrolysis plate, and the electrolysis plate and the heating plate are immersed in the active fluid,

wherein the pressure of the electrolysis bath is substantially equal to or greater than a storage and/or distribution pressure of dihydrogen or dioxygen.

21. The method according to claim 20 , wherein a ratio between a water vapour molar flow rate and a produced dihydrogen molar flow rate has a value from 2 to 5.

22. The high temperature electrolyzer according to claim 1 , wherein the heat transfer fluid is helium gas.

23. The electrolyzer according to claim 1 , wherein the heat transfer fluid is molten zinc.

24. The method according to claim 20 , wherein the pressure of the electrolysis bath is-between 30 bars and 130 bars.