METHOD AND PLANT FOR PRODUCING HYDROGEN

Abstract

The invention relates to a method for producing hydrogen, in which, in a non-electrolytic method, a carbonaceous feed material is converted into non-electrolytically produced hydrogen and one or more further non-electrolytically produced products, and furthermore excess steam is provided using the non-electrolytic process. According to the invention at least a part of the excess steam is used at least intermittently to provide feed steam, which is converted by means of steam electrolysis to electrolytic hydrogen and electrolytic oxygen. The present invention also relates to a corresponding plant.

Claims

1. A method for producing hydrogen, in which, in a non-electrolytic process, a carbonaceous feed material is converted to non-electrolytically produced hydrogen and one or more further non-electrolytically produced products, wherein excess steam is furthermore provided using the non-electrolytic process, wherein at least a part of the excess steam is used at least intermittently to provide feed steam, wherein the feed steam is converted by means of steam electrolysis to electrolytic hydrogen- and electrolytic oxygen.

2. The method according to claim 1, in which the non-electrolytic process comprises reforming in the form of steam methane reforming, partial oxidation, autothermal reforming, combined reforming, or dry reforming, and/or the steam electrolysis comprises a steam electrolysis with alkaline electrolytes, in particular with a polysulfone membrane, a steam electrolysis using a solid oxide electrolysis cell, and/or a high-temperature co-electrolysis with carbon dioxide.

3. The method according to claim 1, in which a part of the non-electrolytically produced hydrogen together with the feed steam is supplied to steam electrolysis at least intermittently.

4. The method according to claim 1, comprising a first operating mode and a second operating mode, wherein in the first operating mode, at least the part of the excess steam that is converted by means of steam electrolysis to the electrolytic hydrogen and the electrolytic oxygen is used for providing the feed steam, and in the second operating mode, at least a part of the excess steam is used for providing electrical energy.

5. The method according to claim 1, in which the provision of the feed steam using at least the part of the excess steam comprises transferring heat of the excess steam or further waste heat without a material exchange to water or steam of a steam system associated with the steam electrolysis, in which steam system the feed steam is provided for steam electrolysis.

6. The method according to claim 1, in which the provision of the feed steam using at least the part of the excess steam comprises using at least the part of the excess steam as the feed steam.

7. The method according to claim 1, in which at least a part of the electrolytic hydrogen is used for processing the carbonaceous feed material.

8. The method according to claim 1, in which at least a part of the electrolytic hydrogen is used for reducing a shift catalyst.

9. The method according to claim 1, in which at least a part of the electrolytic oxygen is used thermally and/or materially in the non-electrolytic process.

10. The method according to claim 1, in which waste heat of the non-electrolytic process is used for operating the steam electrolysis and/or waste heat of the steam electrolysis is used for operating the non-electrolytic process.

11. The method according to claim 1, in which apparatuses used in the non-electrolytic process and in the steam electrolysis are used together.

12. The method according to claim 1, in which a flue gas is formed in the non-electrolytic process, wherein at least a part of the flue gas is used as purge gas in the steam electrolysis.

13. A plant for producing hydrogen, with means configured to convert, in a non-electrolytic process, a carbonaceous feed material to non-electrolytically produced hydrogen and one or more further non-electrolytically produced products and to furthermore provide excess steam using the non-electrolytic process, wherein means configured to use at least a part of the excess steam at least intermittently for providing feed steam and to convert the feed steam to electrolytic hydrogen and electrolytic oxygen by means of steam electrolysis.

14. The plant according to claim 13, which is configured to carry out a method a method for producing hydrogen, in which, in a non-electrolytic process, a carbonaceous feed material is converted to non-electrolytically produced hydrogen and one or more further non-electrolytically produced products, wherein excess steam is furthermore provided using the non-electrolytic process, wherein at least a part of the excess steam is used at least intermittently to provide feed steam, wherein the feed steam is converted by means of steam electrolysis to electrolytic hydrogen and electrolytic oxygen.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1 illustrates a method not according to the invention.

[0040] FIG. 2 illustrates a method according to an embodiment of the invention.

[0041] FIG. 3 illustrates a method according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1 schematically illustrates a method not according to the invention, whereas FIGS. 2 and 3 show methods according to embodiments of the invention. The explanations apply likewise to corresponding plants. Plant parts or method steps corresponding to one another in structural or functional terms are in each case denoted by identical reference signs and are not explained repeatedly merely for the sake of clarity.

[0043] FIG. 1 shows a method not according to the invention for producing hydrogen, which method is denoted as a whole by 300. In method 300, a carbonaceous feed material 1, such as natural gas, is fed to a non-electrolytic process 10, for example a steam methane reforming. In the example illustrated here, the feed material 1 is subjected to a processing 40, for example a desulfurization using hydrogen. The correspondingly processed feed material is denoted by 1a. Further material streams which may be supplied to the non-electrolytic process 10 are not illustrated.

[0044] In the non-electrolytic process 10, a product mixture containing hydrogen but in particular also further components, such as carbon monoxide, is obtained and, as illustrated with 1b, is discharged from the non-electrolytic process 10. The product mixture 1b can be subjected, for example, to a heat recovery 50 and, after corresponding cooling, to a hydrogen removal 60 in the form of a material stream 1c. In the hydrogen removal 60, non-electrolytically produced hydrogen is removed in the form of a material stream 2 and, as illustrated here, recycled in a part 2a into the processing 40 of the feed material 1, for example for desulfurization. As illustrated with 2b, further non-electrolytically produced hydrogen can be discharged as product from the method 300. Non-electrolytically formed further products, in particular carbon monoxide, can be discharged in the form of a material stream 3.

[0045] The method 100 illustrated in FIG. 2 according to one embodiment of the present invention comprises the method steps 10, 40, 50, and 60 already explained in FIG. 1 for the method 300. In addition, a steam electrolysis 20 is illustrated here, in which feed steam 5 is converted to electrolytic hydrogen 6 and electrolytic oxygen 7 not illustrated separately here but shown only in FIG. 3. The feed steam 5 can be provided from the non-electrolytic process 10 using, in particular, excess steam 4 likewise not illustrated separately here.

[0046] As illustrated here, a partial flow, denoted by 6a, of the electrolytic hydrogen 6 from the steam electrolysis 20, like the non-electrolytically provided hydrogen 2a according to FIG. 1, but otherwise for the same purpose, is fed into the processing 40 of the feed material 1. A further portion is conducted, as illustrated with 6b, into the hydrogen removal 60, where the electrolytic hydrogen of the partial stream 6b can be processed as needed together with the non-electrolytically provided hydrogen of material stream 1c. In this way, a joint drying can be used, for example. In this case, the electrolytic hydrogen of the partial stream 6b can be converted to the non-electrolytically provided hydrogen 2.

[0047] As illustrated in the form of a dashed material stream 2c, a part of the hydrogen can be recycled to the steam electrolysis 20, for example during startup, for creating reducing conditions.

[0048] The method 200 illustrated in FIG. 3 according to one embodiment of the present invention comprises the method steps 10, 40, 50, and 60 already explained in FIG. 1 for method 300 and in FIG. 2 for method 100. In addition, the steam electrolysis 20 is shown here with a cathode side 21 and an anode side 22 and the electrolytic oxygen 7 formed. The anode side 9 can be purged in particular with a purge gas 9 which can be purged from the non-electrolytic process 10 using exhaust gas or flue gas. A flue gas that is sulfur-free is particularly suitable for this purpose. For this purpose, the feed for a corresponding one of the burners is optionally desulfurized with the feed for the process.

[0049] FIG. 3 furthermore shows a separate steam system 30 in the method 200, which system, as shown in dashed lines, can be supplied either with excess steam 4 from the non-electrolytic process 10 or from the downstream heat recovery 50 or also only with corresponding heat. In this way, either sufficiently pure feed steam 5 can be provided using the excess steam 4 or corresponding heat.

[0050] A supply of steam into the processing 40 is not illustrated separately here, as is not the supply of hydrogen 2c into the steam electrolysis, but it can be provided. The electrolytic oxygen 7 can also be used in the non-electrolytic process 10, either materially or for oxygen-assisted combustion of a fuel.

[0051] As illustrated by dashed lines, steam from the steam system, but also, for example, excess steam 4, can also be used, optionally and if necessary, to generate electrical energy in a generator unit 70.

[0052] It is understood that all features described in isolation with respect to specific figures or exemplary embodiments can also be used in other exemplary embodiments, alone if described in combination, or in combination if described alone.