EP-4739814-A1 - ELECTROLYZER

Abstract

The present invention refers to an electrolyzer (1) for the production of hydrogen from an alkaline electrolyte. The electrolyzer (1) comprises a first header (11) and a second header (12) between which a plurality of elementary cells (20) and a plurality of bipolar plates (5, 5', 5'') are stacked. Each bipolar plate (5) separates two adjacent elementary cells. According to the invention, each of said bipolar plates (5, 5',5'') comprises two plate-form components (5A, 5B) coupled together and configured so as to define one or more inner cavities (66) for the circulation of a cooling fluid. Furthermore, each bipolar plate (5, 5', 5'') comprises an inlet section (SI) and an outlet section (SV) respectively for the inlet and outlet of said cooling fluid in said one or more inner cavities (66).

Inventors

• CARMINATI, ELENA
• GOZZO, Andrea
• IACOPETTI, LUCIANO

Assignees

• Industrie De Nora S.p.A.

Dates

Publication Date

20260513

Application Date

20240704

Claims (1)

1. CLAIMS 1) Electrolyzer (1) for the production of hydrogen from an alkaline electrolyte, in which said electrolyzer (1) comprises: a first header (11) and a second header (12) made of metallic material; a plurality of elementary cells (20) and a plurality of bipolar plates (5, 5', 5") arranged between said headers (11, 12), wherein said elementary cells (20) are separated from each other by one of said bipolar plates (5, 5', 5"); clamping elements (3) that mechanically connect said headers (11, 12) so that said elementary cells (20) and said bipolar plates (5, 5', 5") remain stably stacked between said headers (11, 12); wherein each of said elementary cell (20) comprises: an anodic portion (20A) including an anode electrode (21 A) and an anodic frame (22A) defining a chamber (200A) in which said anode electrode (21A) is at least partially housed, said anodic portion (20A) including at least one sealing plate (26A) interposed between said anodic frame (22A) and one of said bipolar plates (5, 5’, 5”), said anodic portion further comprising an anodic spacer (23 A) made of metallic material and interposed between said one of said bipolar plates (5) and the anode electrode 21 A; a cathodic portion (20B) including a cathode electrode (21B) and a cathodic frame (22B) defining a chamber (200B) in which said cathode electrode (21B) is at least partially housed, said cathodic portion (20B) including at least one sealing plate (26B) interposed between said cathodic frame (22B) and another of said bipolar plates (5, 5’, 5”), the cathodic portion (20B) further comprising a cathodic spacer (23B) made of metallic material and interposed between the cathode electrode (21B) and said another of said bipolar plates (5), a separator element (2) that separates said anodic portion (20A) from said cathodic portion (20B); at least a further sealing plate (26C) interposed between the anodic frame (22A) of the anodic portion (20A) and the cathodic frame (22B) of the cathodic portion (20B); said electrolyzer (1) further comprising: a first distribution channel (11 A) of said alkaline electrolyte and a first collection channel ( 1 IB) of a first reaction product comprising mainly oxygen, wherein for each of said elementary cells (20), said channels (11 A, 11B) are hydraulically connected to said chamber (200A) of said anodic portion (20 A) by means of grooves (9A, 9A’) defined by said anodic frame (22A); a second distribution channel (12A) of said alkaline electrolyte and a second collection channel (12B) of a second reaction product comprising mainly hydrogen, wherein, for each of said elementary cells (20), said second distribution channel (12A) and said second collection channel (12B) are hydraulically connected to said chamber (200B) of said cathodic portion (20B) by means of grooves (9B, 9B’) defined by said cathodic frame (22B); and being characterized in that each of said bipolar plates (5, 5', 5") comprises two plateform components (5A, 5B) coupled together and configured to define one or more internal cavities (66) for the circulation of a cooling fluid, wherein, each bipolar plate (5, 5', 5") comprises an inlet section (SI) and an outlet section (SV) respectively for the inlet and outlet of said cooling fluid into said one or more internal cavities (66), said electrolyzer (1) further comprising: a delivery channel (4A) of said cooling fluid hydraulically connected to said inlet section (SI) of each of said bipolar plates (5, 5', 5"); and a return channel (4B) of said cooling fluid hydraulically connected to said outlet section (SV) of each of said bipolar plates (5, 5', 5"). 2) Electrolyzer (1) according to claim 1, wherein said delivery channel (4A) comprises an inlet (41A) and said return channel (4B) comprises an outlet (41B), wherein said inlet (41A) and said outlet (41B) are both positioned at one of said headers (11,12). 3) Electrolyzer (1) according to claim 2, wherein said first distribution channel (11A) and said second distribution channel (12A) of said electrolyte respectively comprise a first inlet (111A) and a second inlet (112A) positioned on one of said headers (11, 12) opposite to that on which said inlet (41A) of said delivery channel (4A) and said outlet (41B) , of said return channel (4B) are positioned, wherein said first collection channel (11B) and said second collection channel (12B) of said reaction products comprise a first outlet (11 IB) and a second outlet (112B) respectively that are positioned on said one of said headers (11, 12). 4) Electrolyzer (1) according to any one of the preceding claims, wherein, for each of said elementary cells (20), each frame (22A, 22B) comprises: a first distribution aperture (31 A, 33B) and a first collection aperture (32A, 34B) that are hydraulically connected to with the chamber (200A, 200B) defined by the relative frame (22A, 22B) by means of said grooves (9A, 9A’, 9B, 9B’), wherein said first distribution aperture (31 A, 33B) and said first collection aperture (32A, 34B) are defined in diagonally opposite positions; a second distribution opening (33A, 3 IB) and a second collection opening (34A, 32B) that are not hydraulically connected to the chamber (200A, 200B) defined by the relative frame (22A, 22B); wherein said second distribution opening (33 A, 33B) and said second collection opening (34A, 32B) are defined in diagonally opposite positions; a delivery (35A, 35B) and a return opening (36A, 36B) intended to be passed through, during the use of the electrolyzer (1), by said cooling fluid. 5) Electrolyzer (1) according to claim 4, wherein: said sealing plates (26 A, 26B, 26C) comprise six openings (41, 42, 43, 44, 45, 46) each configured and positioned in a compliant manner to a corresponding opening (31 A, 32A, 33A, 34A, 35A, 36A- 3 IB, 32B, 33B, 34B, 35B, 36B) of each of said frames (22A, 22B). each bipolar plate (5, 5', 5')) includes six apertures (51, 52, 53, 54, 55, 56) each configured and positioned in a compliant manner to one of said six apertures (31 A, 32A, 33A, 34A, 35A, 36A- 3 IB, 32B, 33B, 34B, 35B, 36B) of each of said frames (22A, 22B) and to one of said six apertures (41, 42, 43, 44, 45, 46) of each of said seal plates (26 A, 26B, 26C). 6) Electrolyzer (1) according to claim 5, wherein following the stacking of said elementary cells (20) between said headers (11, 12): one of said distribution apertures (31 A or 3 IB) of each of said frames (22A, 22B), a corresponding first aperture (41) of each of said sealing plates (26A, 26B, 26C) and a corresponding first aperture (51) of each of said bipolar plates (5, 5', 5") define as a whole said first distribution channel (11 A) of said electrolyte; the other of said distribution apertures (33A or 33B) of each of said frames (22A, 22B), a corresponding second aperture (43) of each of said holding plates (26A, 26B, 26C) and a corresponding second aperture (52) of each of said bipolar plates (5, 5', 5") define as a whole said second distribution channel (12A) of said electrolyte; one of said collecting apertures (32A or 32B) of each of said frames (22A, 22B), a corresponding third aperture (42) of each of said sealing plates (26 A, 26B, 26C) and a corresponding third aperture (53) of each of said bipolar plates (5, 5', 5") define as a whole said first collecting channel (11B) of said electrolyte; the other of said collecting apertures (34A, 34B) of each of said frames (22A, 22B), a corresponding fourth aperture (44) of each of said sealing plates (26 A, 26B, 26C) and a corresponding fourth aperture (54) of each of said bipolar plates (5, 5', 5") define as a whole said second collecting channel (12B) of said electrolyte; said delivery opening (35A, 35B) of each of said frames (22A, 22B), a corresponding fifth opening (45) of each of said sealing plates (26A, 26B, 26C) and a corresponding fifth opening (55) of each of said bipolar plates (5, 5', 5") define as a whole said first delivery channel (4A) of said cooling fluid intended to pass internally through said bipolar plates (5, 5', 5"); and finally said return aperture (36A, 36B) of each of said frames (22A, 22B), a corresponding sixth aperture (46) of each of said seal plates (26 A, 26B, 26C) and a corresponding sixth aperture (56) of each of said bipolar plates (5, 5', 5") define as a whole said return channel (4B) of said cooling fluid exiting said bipolar plates (5, 5', 5"). 7) Electrolyzer (1) according to any one of the preceding claims, wherein each component (5A, 5B) of said bipolar plate (5) comprises a flat part (501A, 501B) and a molded part (502A, 502B) surrounded by said flat part (501A, 501B), in which, for each of said components (5A, 5B), said molded part (502A, 502B) is recessed with respect to a reference plane (PR) on which said flat part (501A, 501B) develops, wherein said components (5A, 5B) are connected at the their flat parts (501A, 501B) so as to be symmetrical with respect to a contact plane coincident with said reference plane (PR), and wherein the molded region (502A) of said first component (5A) is facing said molded region (502B) of said second component (5B), said one or more internal cavities (66) of said bipolar plate (5, 5') being defined between mutually facing molded regions (502, 502) of said components (5A, 5B). 8) Electrolyzer (1) according to claim 7, wherein for each of said components (5A, 5B) said molded portion (502A, 502B) comprises at least one area (502') with a of substantially wavy shape defined by grooves (S) alternating with ridges (CR), and wherein as a result of the connection of said components (5A, 5B), each of said ridges (CR) of said molded part (502A) of said first component (5A) contacts a corresponding ridge (CR) of said molded part (502B) of said second component (5B), and wherein, as a result of said connection, said internal cavities (66) for circulation of said cooling fluid are defined between two mutually facing grooves (S) of said molded parts (502A, 502B) of said components (5 A, 5B). 9) Electrolyzer (1) according to claim 7, wherein for each of said components (5A,5B), said molded portion (502A, 502B) comprises a recessed portion (503A, 503B) with respect to said reference plane (PR) and a plurality of protrusions (504A, 504B) that develop from said recessed portion (503A, 503B) beyond said reference plane (PR), and wherein, as a result of the connection of said components (5A, 5B), said recessed portion (503 A) of the molded portion (502A) of said first component (5 A) remains arranged on a side opposite to that wherein the recessed portion (503B) of the molded portion (502B) of said second component (5B) is located, wherein between said recessed portions (503A, 503B) is defined said at least one inner cavity (66) for the circulation of said cooling fluid, and wherein said the protrusions (504A) of said first component (5 A) contact the inner surface of said recessed portion (503B) of said second component (5B) and said protrusions (504B) of said second component (5B) contact the inner surface of said recessed portion (503A) of said first component (5A). 10) Electrolyzer (1) according to any one of claims 1 to 9, wherein said components (5A, 5B) comprise two flat metal plates, each of which comprises an inner surface (51 A) and an outer surface (5 IB) opposite said inner surface (51 A), and wherein each of said metal plates comprises a plurality of grooves (65) that develop in the thickness of the plate from the corresponding inner surface (51 A), and wherein said components (5A, 5B) are coupled so that the inner surface (51 A) of one component (5A) results in contact with the inner surface (51 A) of the other component (5B), and wherein, as a result of said contact, the grooves (65) of one component (5A) face corresponding grooves of the other component (5B), wherein a pair of mutually facing grooves defines an inner cavities (66) for the circulation of said cooling fluid, said outer surface (5 IB) of said metal plates being flat.

Description

ELECTROLYZER DESCRIPTION FIELD OF THE INVENTION The present invention falls within the field of manufacturing of devices for the production of hydrogen by means of water electrolysis. In particular, the invention relates to an electrolyzer for the production of hydrogen and oxygen preferably, but not exclusively, starting from an alkaline electrolyte (for example from a liquid, solution of potassium hydroxide). PRIOR ART Over the last few years, the demand for hydrogen has significantly increased in various production areas, such as the production of electricity without polluting emissions. Hydrogen is easily stored and transported, for example through pipelines like those used for gas, and therefore can be made easily available for different applications. For the production of hydrogen, the use of electrochemical reactors, also called electrolyzers, is known, in which the electrolysis of water is carried out, i.e., the dissociation thereof into hydrogen and oxygen under the effect of an electric current. The existence of different types of electrolysis is equally well known, including alkaline water electrolysis, polymer membrane electrolysis and ceramic membrane electrolysis. A plant for the production of hydrogen at an industrial level, based on the electrolysis of alkaline water, typically comprises an electrolyzer including a plurality of elementary cells stacked between two headers and locked through the use of clamping means (typically screws) which exert a traction force between the two headers. The dissociation reaction of alkaline water takes place in each of the elementary cells, which very frequently consists of an electrolyte based on potassium hydroxide (also commonly known by the name "potash"). In each elementary cell there is an anodic portion and a cathodic portion separated by a separator element. The anodic portion and the cathodic portion respectively comprise an anode electrode and a cathode electrode between which the separator element is placed. The anodic portion comprises an anode chamber in which an anode electrode is at least partially housed. Similarly, the cathodic portion comprises a cathode chamber in which a cathode electrode is partially housed. The anode and cathode chambers are defined by a specific frame shared between the two chambers or by a dedicated frame for each chamber. A separator element involved in the electrolysis process according to widely known principles is arranged between the two electrodes (anodic and cathodic). A bipolar plate made of metallic material is arranged between two adjacent elementary cells, comprising one face/side in electrical contact with the cathode electrode of the cathodic portion of a cell, and with the opposite face/opposite side in electrical contact with the anode electrode of the anodic portion of another adjacent cell. For each cell, between each frame and the adjacent bipolar plate, as well as between the frames of each chamber (if they are separate), sealing plates are typically provided, normally made of polymeric material. Typically, the frames of the elementary cells, the sealing plates and the bipolar plates comprise openings arranged and configured so as to define, following the stacking of the cells between the electrolyzer headers, a first potash distribution channel, a second potash distribution channel, a first collection channel for a first reaction product and a second collection channel for a second reaction product, where said reaction products consist of a biphasic solution consisting of reaction gas (hydrogen or oxygen) and unreacted electrolyte/potash. The first distribution channel and the first collection channel are hydraulically connected, through the respective frames, with the anodic section of each elementary cell, while the second distribution channel and the second collection channel are hydraulically connected, through the respective frames, with the cathodic section of each elementary cell. Through the distribution channel (first or second), the corresponding portion (anodic or cathodic) of each elementary cell is supplied with potash. For each elementary cell, the gas (hydrogen or oxygen) which is generated following the electrolysis reaction and/or any non-dissociated potash exit from the respective portion (cathodic or anodic) of the cell and flow into the corresponding collection channel (first or second). Figure 1 is a general diagram of a plant (600) of known type in which an electrolyzer (E) with the structure just described above is placed. In such a plant (600), a first circuit (Cl) and a second circuit (C2), that feed the electrolyzer (E), are identified. Each of these circuits comprises a delivery branch (RM1, RM2), hydraulically connected with a corresponding distribution channel, and a return branch (RR1, RR2) hydraulically connected with the corresponding collection channel of the electrolyzer. A circulation pump (Pl, P2) is arranged for each circuit (Cl, C2), along the delivery branc