Pyrotechnic process for providing very high purety hydrogen and associated device

1. A pyrotechnic process for providing very high purity hydrogen, comprising:

combusting at least one solid pyrotechnic charge capable of generating hydrogen-containing gas for the production of a pressurized hot hydrogen-containing gas that contains at least 70% by volume of hydrogen;

purifying at least one portion of said pressurized hydrogen-containing gas, by passing through a metallic hydrogen separation membrane maintained at a temperature above 250° C., in order to obtain, at the outlet of said membrane, a hydrogen-containing gas that contains at least 99.99% by volume of hydrogen, and

cooling at least one portion of said hydrogen-containing gas produced, before its purification thereof,

wherein a portion of the amount of heat produced by the combustion of said at least one solid pyrotechnic charge capable of generating hydrogen-containing gas is used for heating said metallic separation membrane,

said portion of the amount of heat produced by the combustion of said at least one solid charge capable of generating hydrogen-containing gas being transferred to said metallic separation membrane via a solid material, which acts as a thermal bridge, and

wherein a portion of the amount of heat extracted during said cooling is used for heating said metallic separation membrane.

2. The process as claimed in claim 1 , further comprising filtrating at least one portion of said hydrogen-containing gas produced in order to strip it at least partly of the solid combustion residues that it contains, said filtration being carried out upstream of the purification thereof.

3. The process as claimed in claim 1 comprising, successively, producing said hydrogen-containing gas, filtrating at least one portion of said hydrogen-containing gas in order to strip it at least partly of the solid combustion residues that it contains, cooling said at least one portion of said hydrogen-containing gas that has been filtered and purifying said at least one portion of the hydrogen-containing gas that has been filtered and cooled.

4. The process as claimed in claim 1 , wherein said at least one solid pyrotechnic charge capable of generating hydrogen-containing gas is a pyrotechnic charge consisting of at least one pyrotechnic product containing, for at least 96% of its weight, at least one inorganic oxidizing component and at least one hydrogen-containing reducing component selected from inorganic hydrides, borazane and polyaminoboranes.

5. The process as claimed in claim 4 , wherein said at least one hydrogen-containing reducing component selected from inorganic hydrides is selected from inorganic borohydrides.

6. The process as claimed in claim 4 , wherein said at least one hydrogen-containing reducing component is selected from borazane and polyaminoboranes.

7. The process as claimed in claim 4 , wherein said at least one inorganic oxidizing component is selected from perchlorates, dinitramides, nitrates and metal oxides.

8. The process as claimed in claim 4 , wherein said at least one pyrotechnic product contains:

from 40% to 80% by weight of said at least one hydrogen-containing reducing component, and

from 20% to 60% by weight of said at least one inorganic oxidizing component.

9. The process as claimed in claim 4 , wherein said at least one pyrotechnic product contains more than 50%, by weight of said at least one hydrogen-containing reducing component.

10. The process as claimed in claim 1 , wherein the process is carried out for supplying at least one fuel cell.

11. A pyrotechnic device for providing very high purity hydrogen, suitable for carrying out the process as claimed in claim 1 , comprising:

at least one combustion chamber, provided with at least one delivery orifice, suitable for the arrangement and the high-pressure combustion, within it, of a solid pyrotechnic charge capable of generating hydrogen-containing gas, and also for the delivery of pressurized hot hydrogen-containing gas via said at least one delivery orifice;

at least one metallic hydrogen separation membrane, suitable for the purification of hydrogen-containing gas, having an inlet face, and an outlet face; said metallic hydrogen separation membrane being arranged in a reservoir so that an empty volume is created in said reservoir upstream of its inlet face;

means for delivering the purified gas;

said combustion chamber(s) and metallic hydrogen separation membrane(s) being connected via at least one pipe so that hydrogen-containing gas delivered from said combustion chamber(s) is sent to at least one metallic hydrogen separation membrane and being arranged within a thermally insulated enclosure, said thermally insulated enclosure containing a solid material that provides a thermal bridge between said combustion chamber(s) and metallic separation membrane(s); said delivery means being capable of ensuring the delivery of gas, purified within said metallic hydrogen separation membrane(s), out of said thermally insulated enclosure; and

means for cooling the gas, arranged downstream of the at least one combustion chamber and upstream of the at least one metallic separation membrane, said cooling means consisting of at least one portion of the at least one pipe that connects the at least one combustion chamber with the at least one metallic separation membrane, said portion winding around said at least one metallic separation membrane.

12. The device as claimed in claim 11 , further comprising at least one annular combustion chamber arranged around at least one metallic separation membrane.

13. The device as claimed in claim 11 , wherein said at least one metallic separation membrane is a membrane made of palladium or made of an alloy that contains palladium.

14. The device as claimed in claim 11 , further comprising means for filtering the gas, that are capable of stripping it of at least one portion of the solid combustion residues that it contains, arranged downstream of the at least one combustion chamber and upstream of the at least one metallic separation membrane.

15. The device as claimed in claim 11 , wherein the device is arranged upstream of at least one fuel cell.

16. The process as claimed in claim 1 , wherein the metallic hydrogen separation membrane is maintained at a temperature between 300° C. and 600° C.

17. The process as claimed in claim 1 , wherein the solid material, which acts as a thermal bridge, has a high thermal conductivity from 50 W/m·K to 380 W/m·K.

18. The process as claimed in claim 5 , wherein said at least one hydrogen-containing reducing component selected from inorganic hydrides is selected from alkali metal and alkaline-earth metal borohydrides.

19. The process as claimed in claim 5 , wherein said at least one hydrogen-containing reducing component selected from inorganic hydrides is selected from sodium, lithium and magnesium borohydrides.

20. The process as claimed in claim 6 , wherein said at least one hydrogen-containing reducing component consists of borazane.

21. The process as claimed in claim 7 , wherein said at least one inorganic oxidizing component is selected from ammonium perchlorate, ammonium dinitramide, strontium nitrate and iron oxide.

22. The process as claimed in claim 8 , wherein said at least one pyrotechnic product contains:

55% to 75% by weight of said at least one hydrogen-containing reducing component, and

25% to 45% by weight of said at least one inorganic oxidizing component.

23. The process as claimed in claim 9 , wherein said at least one pyrotechnic product contains more than 70% by weight of said at least one hydrogen-containing reducing component.

24. The device as claimed in claim 11 , wherein the solid material providing a thermal bridge between said combustion chamber(s) and metallic separation membrane(s) has a high thermal conductivity from 50 W/m·K to 380 W/m·K.

25. The device as claimed in claim 14 , wherein said means for filtering the gas are arranged upstream of the cooling means.