An electrolyzer for producing hydrogen gas from an electrolyte fluid

Abstract

An electrolyzer (100) for producing hydrogen gas from an electrolyte fluid, comprising: a first header (110) and a second header (120) mutually coupled along a coupling surface (111, 121), a frame (170) arranged between the first and second header (110, 120) and configured to define with the lateral wall (160) of the recesses (150); one or more first channels (180) in fluid communication with a relative inlet channel (130), a reaction chamber (190) in fluid communication with the first channels (180), and second channels (200) in fluid communication with the reaction chamber (190) and outlet channels (140); electrodes (210) arranged in the reaction chamber (190) and mutually spaced apart along the transversal direction (T-T), electrodes (210) being configured to electrolyze the electrolyte fluid entering the reaction chamber (190) from the first channels (180) and to produce hydrogen gas and oxygen gas on a respective electrode (210); the second channels (200) together with the reaction chamber (190) and electrodes (210) being configured to separate hydrogen gas in a first electrolyzed fluid and oxygen gas in a second electrolyzed fluid in a respective second channel (200).

Description

[0001] “An electrolyzer for producing hydrogen gas from an electrolyte fluid” DESCRIPTION

[0002] Field of the invention

[0003] The present invention relates to an electrolyzer for producing hydrogen gas preferably from an electrolyte fluid, particularly focusing on innovations that enhance operational efficiency and longevity under demanding conditions. Specifically, it involves a membrane-less design optimized for operation under supercritical conditions, characterized by high pressures and temperatures, to enhance efficiency and reduce degradation in alkaline electrolyte electrolysis systems.

[0004] State of the art

[0005] Electrolysis is a well-established method for producing hydrogen gas, utilizing various technologies such as alkaline electrolysis, proton exchange membrane (PEM) electrolysis, and solid oxide electrolysis. Alkaline electrolyzers are known for their robustness and cost-effectiveness, while PEM electrolyzers offer high efficiency and fast response times. Solid oxide electrolyzers operate at high temperatures, providing the benefit of co-generating hydrogen and heat.

[0006] Despite their widespread use, these technologies often rely on complex systems involving membranes to manage gas production and purity. Alkaline and PEM systems, in particular, face challenges in scaling and maintaining efficiency, as the membranes are subject to wear and chemical degradation over time. This necessitates frequent maintenance and replacement, adding to operational costs. Advances are being made in materials and design to improve efficiency and reduce reliance on critical components, yet significant hurdles remain in achieving optimal performance and longevity across all types of electrolyzers.

[0007] Problems of the prior art

[0008] Current electrolysis technologies face several significant challenges that hinder their widespread adoption and efficiency. One major issue is the reliance on membranes or separators, which are crucial for maintaining gas purity but are prone to degradation over time. This degradation leads to increased maintenance costs and reduced operational lifespan.

[0009] Additionally, many electrolyzers operate under less-than-ideal conditions, resulting in limited energy efficiency and higher production costs. The materials used in these systems often include critical and expensive components, which further elevate the cost of hydrogen production.

[0010] Another drawback is the scalability of these technologies. While small-scale applications may be feasible, expanding to industrial levels can be challenging due to inefficiencies and the need for extensive infrastructure. Moreover, the environmental impact of using certain materials raises sustainability concerns, as these components may not align with green energy goals.

[0011] Overall, these limitations create barriers to achieving cost-effective, efficient, and sustainable hydrogen production, necessitating new approaches and innovations in electrolyzer design.

[0012] Object of the invention The object of the present invention is to provide an electrolyzer that can obviate the above discussed drawbacks of the prior art.

[0013] In particular, the present invention has the object to provide an improved electrolyzer enhancing efficiency and durability while operating under extreme conditions.

[0014] The aforementioned technical purpose and objects are substantially fulfilled by an electrolyzer which comprise the technical features as disclosed in one or more of the accompanying claims.

[0015] Advantages of the invention

[0016] Advantageously, the electrolyzer of the present invention eliminates the need for a membrane or separator, reducing maintenance requirements and extending operational lifespan.

[0017] Advantageously, the electrolyzer of the present invention operates under supercritical conditions, enhancing voltage efficiency and reducing energy consumption for more cost-effective hydrogen production.

[0018] Advantageously, the electrolyzer of the present invention utilizes advanced materials and design configurations, maintaining high performance under extreme pressures and temperatures, thereby improving durability.

[0019] Advantageously, the electrolyzer of the present invention features a simplified design that facilitates easier scalability and integration into existing systems, promoting broader industrial adoption. Advantageously, the electrolyzer of the present invention addresses sustainability concerns, supporting green energy initiatives with an environmentally friendly solution for hydrogen production. DESCRIPTION OF DRAWINGS

[0020] Further features and advantages of the present invention will result more clearly from the illustrative, non-limiting description of a preferred, non-exclusive embodiment of electrolyzer as shown in the accompanying drawings:

[0021] - Figure 1 : shows perspective view of the electrolyzer according to a first embodiment of the present invention;

[0022] - Figure 2: shows transversal section A-A of the electrolyzer of Figure 1;

[0023] - Figure 3: shows perspective view of the electrolyzer of Figure 1 with some parts omitted to better show others;

[0024] - Figure 4 shows perspective view of the electrolyzer of Figure 1 with some parts omitted to better show others;

[0025] - Figure 5 shows an exploded view of the electrolyzer of Figure 1;

[0026] - Figure 6 shows a transversal section A-A of the electrolyzer of Figure 1 with an indication of the flows streams.

[0027] DETAILED DESCRIPTION

[0028] For the purposes of the present invention the wording “comprising” does not exclude the possibility that further stages / elements not explicitly listed after said wording are contemplated.

[0029] On the contrary the wording “consisting of’ excludes the above possibility.

[0030] The present invention relates to an electrolyzer globally referred as 100 in the figures. The electrolyzer 100 is used to produce hydrogen from an electrolyte or water.

[0031] Preferably, the electrolyzer 100 can be associated to a hydrogen production plant and terminals.

[0032] It is to be noted that the hydrogen can be produced by electrolysis of water or of electrolyte.

[0033] For the scope of the present invention, electrolyte fluid is considered for the hydrogen production, but the electrolyzer 100 can use also other fluids for hydrogen production.

[0034] Preferably, the electrolyte entering in the electrolyzer 100 can be alkaline type comprising a solution of potassium hydroxide or sodium hydroxide and water. Generally, the overall well-known chemical reaction of the electrolysis is carried out in electrolysis cell consisting in electrodes i.e. anode and cathode. When an electric current is passed across the electrodes, water molecules at the cathode are reduced forming hydrogen. At the same time, the hydroxyl ions at the anode are oxide forming oxygen gas.

[0035] The electrolyzer 100 comprises a first header 110 and a second header 120 mutually coupled along a coupling surface 111, 121 as for example shown in figure 1. Each header 110, 120 extends along a longitudinal direction L-L preferably between a first 112, 122 and second base portions 113, 123.

[0036] Each header 110, 120 has a thickness 80 along a transversal direction T-T perpendicular to the longitudinal direction L-L. Preferably, each header 110, 120 extends between the respective coupling surface 111, 121 and a relative external surface 114, 124 along the transversal direction T-T. The thickness 80 is respectively defined between the coupling surface 111, 121 and external surfaces 114, 124.

[0037] Each header 110, 120 extends along a depth direction D-D perpendicular to the longitudinal direction L-L and to the transversal direction T-T preferably between a first and second surface 115, 125, 116 126.

[0038] The longitudinal direction L-L can be parallel to the ground when the electrolyzer 100 is arranged in a horizontal configuration or transversal to the ground, preferably perpendicular, when the electrolyzer 100 is arranged in a vertical configuration.

[0039] Each header 110, 120 comprises an inlet channel 130 and an outlet channel 140 spaced apart along the longitudinal direction L-L. It is to be noted that each inlet channel 130 is configured to receive the electrolyte to be electrolyzed and the outlet channels 140 are configured to selectively eject a first and second electrolyzed fluids comprising respectively hydrogen and oxygen. According to one embodiment, the inlet channel 130 and the outlet channel 140 are respectively arranged, at the first base portion 112, 122 and at the second base portion 113, 123. Preferably, the inlet channel 130 and the outlet channel 140 are formed in the headers 110, 120 by carving technique, moulding technique, laser cutting, waterjet cutting or milling technique. Preferably, the inlet 130 and outlet channel 140 extend along the depth direction D-D from one of the first or second surface 115, 125, 116 126 for a channel depth in the relative header 110, 120. More preferably, the first depth is smaller than the distance between the first and second surfaces 115, 125, 116, 126. More, preferably, inlet 130 and outlet channel 140 extend from a relative inlet channel opening 131 and outlet channel opening 141 formed on one of the first and the second surface 115, 125, 116, 126.

[0040] It is to be noted that each header 110, 120 has a recess 150 formed in the thickness 80 from the coupling surface 111, 121. Preferably, each recess 150 is formed in a recess area 150a spaced apart from the first and second surfaces 115, 125, 116, 126 along the depth direction D-D and from the first and second end portions along the longitudinal direction L-L. More preferably, the recess area 150a is formed substantially in the middle of the coupling surface 111, 121. Namely, each recess 150 extends along the longitudinal, depth and transversal direction L-L, D-D, T-T.

[0041] It is to be noted that each header 110, 120 is carved by means of known techniques to skilled person in the art to define the recess 150 or alternatively the recesses 150 are directly produced with moulding technology with the headers 110, 120 or according to one of the above-mentioned techniques.

[0042] According to one embodiment, each recess 150 has recess depths measured from the coupling surface 111, 121 along the transversal direction T-T in the thickness 80.

[0043] Namely, each recess 150 comprises a perimetral recess groove 152 having a first recess depth and channel recess 153 having a variable depth. Each recess 150 defines a lateral wall 160. Preferably, the channel recess 153 defines the lateral wall 160.

[0044] According to one embodiment, the recesses 150 when the headers 110, 120 are coupled identify a frame cavity 310 preferably by means of perimetral recess groove 152 identify a housing cavity and by means of channel recess 153 a channel cavity. The housing cavity and the channel cavity define the frame cavity 310.

[0045] According to one embodiment, the electrolyzer 100 comprises retaining assembly 360 configured to mutually retain the headers 110, 120 one to the other preferably along the longitudinal, depth and transverse direction L-L, D-D, T-T.

[0046] The retaining assembly 360 can comprise a plurality of retaining passing through channels 363 formed in each header 110, 120 along transversal direction T-T, first retaining elements 361 configured to be inserted into retaining passing through channels 363 and seconds retaining elements 362 configured to couple with coupling portions 361a of the first retaining elements 361.

[0047] Preferably, each first retaining element 361 is configured to be inserted at least in part into a relative passing through channel 363 in a first opening 363a such that the coupling portion 361a projects from a second opening 363b opposed to the first opening 363a. Namely, each passing through channel 363 extends along an extension direction E-E, for example parallel to the transversal direction T-T, between the first and second opening 363a, 363b. The first retaining element 361 extends between a stopping portion 361b and the coupling portion 361a along a relative extension direction. Namely, each passing through channels 363 comprises header channels 363c formed in each header 110, 120 and configured to be aligned to define the passing through channels 363 allowing the insertion of the first retaining element 361 therein. It is to be noted that each header channels 363c has an inner and outer opening wherein the outer openings define the first opening 363a and the second openings 363b and the inner openings are mutually faced when the headers 110, 120 are coupled.

[0048] The stopping portion 361b is configured to abut against a header portion around the first opening 363a and stop the first retaining element 361 along the extension direction E-E upon insertion. In this way, the second retaining element 362 is configured to engage the coupling portion 361a and mutually lock the first retaining element 361 and the second retaining element 362. According to one embodiment, the first and second retaining element 361, 362 have a nut-screw coupling. For example, the retaining assembly 360 comprises bolts wherein the first retaining elements 361 are screws and the second retaining element are nut 362.

[0049] According to one embodiment, the first and second header 110, 120 are made in a material having exceptional resistance to corrosion and high temperatures, making it ideal for supercritical conditions such as Hastelloy, a nickel-based alloy.

[0050] The electrolyzer 100 comprises a frame 170 arranged between the first and second headers 110, 120 and configured to define with the lateral wall 160 of the recesses 150 a flow distribution for electrolyte and electrolyzed fluids from the inlet channels 130 to the outlet channels 140. It is to be noted that the flow distribution extents along the longitudinal, depth and transversal direction L-L, D-D, T-T.

[0051] Preferably, the frame 170 is configured to define with the lateral wall 160 of the recesses 150 one or more first channels 180, a reaction chamber 190 and second channels 200.

[0052] More preferably, the frame 170 is configured to define with channel recess 153 the first channels 180, the reaction chamber 190 and the second channels 200. The one or more first channels 180 are in fluid communication with a relative inlet channel 130. The reaction chamber 190 is in fluid communication with the first channels 180, and the second channels 200 are in fluid communication with the reaction chamber 190 and outlet channels 140. Preferably, the reaction chamber 190 is arranged between the first channels 180 and the second channels 200 along the longitudinal direction L-L. More preferably, the flow distribution has the reaction chamber 190, the first channels 180 and the second channels 200.

[0053] According to one embodiment, the frame 170 comprises a first wall 220 and a second wall 230 mutually spaced apart along the longitudinal direction L-L defining a middle opening 240.

[0054] Preferably, the frame 170 comprises a frame perimetral portion 171 extending between a first frame base portion 172 and second frame base portion 173 along a first direction X-X which is parallel to the longitudinal direction L-L when the frame 170 is arranged between the headers 110, 120. The frame perimetral portion 171 also extends between a first lateral portion 174 and second lateral portion 175 along a second direction Y-Y perpendicular to the first direction X-X a parallel to the depth direction D-D when the frame 170 is arranged between the headers 110, 120. It is to be noted that the lateral portions 174, 175 connect the first and second frame base portions 172, 173.

[0055] More preferably, the first wall 220 extends from the first frame base portion 172 towards the second frame base portion 173 for a portion of the lateral portions 174, 175. The second wall 230 extends from the second frame base portion 173 towards the first frame base portion 172 for a portion of the lateral portions 174, 175. The first and second walls 220, 230 defines the middle opening 240 which is limited by a portion of lateral portions 174, 175 and wall portion ends of the first and second walls 220, 230 opposed with respect to the first and second frame base portion 172, 173. Namely, the wall portion ends are spaced apart and the lateral portions 174, 175 are free from the walls 220, 230 between the wall portion ends.

[0056] It is to be noted that, when the frame 170 is arranged in the recess cavity the first frame base portion 172 and the second frame base portion 173 are arranged respectively proximate to first base portion 112, 122, and second base portion 113, 123.

[0057] According to the preferred embodiment, each lateral wall 160 of each recess has a first portion 250 and a second portion 260 and a middle portion 270 connecting the first and second portions 250, 260. Namely, the channel recess 153 has the first and the second portion 250, 260 and the middle portion 270.

[0058] The first portions 250 and the first wall 220 define the first channels 180. The second portions 260 and the second wall 230 define the second channels 200. The middle portions 270 define the reaction chamber 190 with the middle opening 240.

[0059] Preferably, the first portions 250 and the first wall 220 define the first channels 180 therebetween. Namely, on one side of the first wall 220 faced to the first portion 250 of a header, the first channel 180 is defined and, on the other side of the first wall 220 faced to the first portion 250 of other header, the other first channel 180 is defined. In details, the first wall 220 is complementary to the first portions 250 to define the first channels 180.

[0060] It is to be noted that on one side of the second wall 230 faced to the second portion of a header the second channel 200 is defined and on the other side of the second wall 230 faced to the second portion 260 of other header the other second channel 200 is defined. The reaction chamber 190 is defined between the middle portion 270 wherein the middle opening 240 is arranged.

[0061] According to one embodiment, the first and second walls 220, 230 are tapered from the relative base frame portion 172, 173 to the end wall portion. Namely, the walls thin toward the middle opening 240.

[0062] According to one embodiment, each first portion 250 of the channel recess 153 is inclined from the reaction chamber 190 towards the perimetral groove 152. Namely, each first portion 250 has a variable depth which reduces from the perimetral groove 152 to the middle portion 270. Preferably, each first portion 250 is counter-shaped to the first wall 220 to define the first channels 180. The middle portion 270 has a depth greater than the depth of the first portion 250 proximate to the middle portion 270. Preferably, the middle portion 270 has a variable depth which increases along the longitudinal direction L-L towards the second end portions 113, 116. Namely, the middle portion 270 and then the reaction chamber 190 widen along the longitudinal direction L-L. Each second portion 260 has a variable depth which increases along the longitudinal direction L-L towards the second base end portions 113, 116.

[0063] According to one embodiment, the first channels 180 are convergent to the reaction chamber 190. The second channels 200 widen from the reaction chamber 190 along the longitudinal direction L-L towards outlet channels 140. The reaction chamber 190 widens along the longitudinal direction L-L from the first channels 180 towards the second channels 200 to cooperate with the second channels 200 in electrolyzed fluids separation. Preferably, the reaction chamber 190 is configured to channel the produced gas, oxygen and hydrogen, in a relative second channel 200 together with unreacted electrolyte fluid. In this way, the reaction chamber 190 allows separation and addressing of oxygen and hydrogen gases in a specific second channel 200 together with unreacted electrolyte fluid.

[0064] According to one embodiment, the frame 170 is made in a non-conductive material for electrical insulation. Namely, the frame electrically isolates one header from the other, preventing unwanted electrical pathways that could short-circuit. For example, the frame is made in sintered ZrO2 or Ni coated with ZrO2.

[0065] According to one embodiment, each header 110, 120 comprises one or more connecting channels 300 configured to put in fluid communication the inlet channel 130 with the first channel 180. Namely, the inlet channels 130 act as manifold to distribute the inlet fluid such as electrolyte to the connecting channels 300. Preferably, the connecting channels 300 are made according to one or more of the above- mentioned techniques.

[0066] According to one embodiment, the frame 170 is arranged in the frame cavity 310 between the first and second header 110, 120. Namely, the perimetral recess grooves 152 defining a housing for the frame 170 configured to retain the frame perimetral portion 171 of the frame 170 within the frame cavity 310 between the header 110, 120. It is to be noted that the base frame portions 172, 173 and the lateral portions 174, 175 have a frame thickness arranged in part in perimetral recess grooves 152 of one header on the other part in the other.

[0067] According to one embodiment, the electrolyzer 100 comprises sealing elements 350 arranged between the frame 170 and each header 110, 120 configured to prevent electrolyte fluid, electrolyzed fluid, and gas leakage. Namely, the sealing elements 350 are arranged between the frame perimetral portion 171 and the perimetral recess grooves 152. Advantages, the material on which the sealing elements 350 are made is chosen for its ability to withstand high pressure and temperature while maintaining great chemical compatibility with medias, ensuring that the system remains sealed while avoiding chemical interactions with the electrolyte or other components. Preferably, the sealing elements 350 are made in Graphite or Grafoil.

[0068] The electrolyzer 100 comprises electrodes 210 arranged in the reaction chamber 190 and mutually spaced apart along the transversal direction T-T. The electrodes 210 define the electrolysis cell within the reaction chamber 190.

[0069] The electrodes 210 are configured to electrolyze the electrolyte fluid entering the reaction chamber 190 from the first channels 180 and to produce hydrogen gas and oxygen gas on a respective electrode 210.

[0070] It is to be noted that the hydrogen gas and oxygen gas are separated in a respective first and second electrolyzed fluid. Namely, the first electrolyzed fluid comprises hydrogen gas and second electrolyzed fluid comprises oxygen gas. In addition, each electrolyzed fluids can comprise electrolyte fluid which is unreacted.

[0071] Preferably, the electrodes 210 comprise an anode 320 and cathode 330 mutually spaced apart along the transversal direction T. The cathode 330 is configured to produce hydrogen gas and the anode 320 is configured to produce oxygen gas. In this way, hydrogen and oxygen are mutually separated preferably in the first electrolyzed fluid and the second electrolyzed fluid.

[0072] It is to be noted that hydrogen and oxygen are produced at the respective cathode 330 and anode 320 and are mutually spaced apart in the reaction chamber 190. Namely, each electrode 210 has first electrode surface 210a faced to the other electrode and opposed second electrode surface. The hydrogen and oxygen are at least produced on the first electrode surface 210a.

[0073] According to one embodiment, the anode 320 and the cathode 330 are respectively spaced apart from the lateral wall 160 along the transversal direction T- T, preferably at the middle portion 270. More preferably, hydrogen and oxygen are produced also on the second electrode surface 210b facing the middle portion 270.

[0074] Thanks to the separation of the electrodes separate flows of hydrogen and oxygen in respective first and second electrolyzed fluid are produced and addressed in a relative channel 200.

[0075] Preferably, the lateral wall 160 at the middle portion 270 has one or more grooves 280 mutually spaced apart along the depth direction D-D and configured to define middle channels 290 for the electrolyte fluids and electrolyzed fluids channelling. Specifically, the middle portion 270 has ribs 281 alternated by the grooves 280 along the depth direction D-D. Each ribs 281 and grooves 280 extends along the longitudinal direction L-L. Such arrangement advantageous provides mechanical support and allows the fluid channelling.

[0076] According to the preferred embodiment, the cathode 330 and the anode 320 are associated with a respective second channel 200 to convey the first and second electrolyzed fluid into a respective second channel 200.

[0077] It is to be noted that the second channels 200 together with the reaction chamber 190 and the electrodes 210 are configured to separate the first and second electrolyzed fluids in a respective second channel 200. Thanks to such separation and conveying allow to avoid membranes and separators between the electrodes to separate hydrogen and oxygen.

[0078] In details, each electrode 210 extends along a first electrode base portion 211 and a second electrode base portion 212 along the first electrode direction C-C parallel to longitudinal direction L-L when arranged in the chamber reaction. For each electrode 210 to the second channel 200 to which is associated, the first electrode base portion 211 is proximate to first channel opening 180a in the reaction chamber 190 and the second electrode base portion 212 is arranged proximate to the second channel opening 200a in the reaction chamber.

[0079] Is this way, the cathode 330 and the anode 320 address the electrolyzed fluid in a relative second channel 200.

[0080] According to one embodiment, the second electrode base portion 212 of each electrode 210 extends at least in part into a relative second channels 200.

[0081] Preferably, the electrodes 210 cooperate with the second walls 230 of the frame 170 and the second portions 260 to divide hydrogen and oxygen produced on a relative electrode 210 and then the separation of the first and second electrolyzed fluids. Preferably, the electrolyte fluid coming from the first channels 180 continuously push the electrolyzed fluids in the relative second channels 200 in a continuous electrolysing process.

[0082] More preferably, as a function of flow rate of the electrolyte fluid and separation of the electrolyzed fluids, each electrolyzed fluid is addressed to the relative second channel 200 proximate to which the relative hydrogen and oxygen are produced by means of electrode 210, middle portion 190 and the second channel 200. Thanks to the separation of the electrolyzed fluids hydrogen and oxygen are separated with a high efficiency and ejected by a relative outlet channel 140.

[0083] According to one embodiment, the electrodes 210 comprise a mesh body 340. Preferably, the electrolyte can distribute on both electrode surface. Preferably, the mesh body 340 is made in INCONEL 625

[0084] According to one embodiment, the electrolyzer 100 is configured to operate under supercritical conditions with pressures greater than 220 bar and temperatures greater than 375 °C. Namely, the electrolyzer 100 operates under supercritical conditions with pressures greater than 220 bar and temperatures greater than 375°C. Namely, the electrolyte fluid enter in the electrolyzer 100 at supercritical conditions. Thanks to the supercritical conditions hydrogen production is improved and the relative production efficiency.

[0085] According to one embodiment, the electrolyzer is configured to operate with an alkaline electrolyte. Namely, the electrolyzer operates with an alkaline electrolyte.

[0086] Preferably, the electrolyzer 100 can be made in materials configured to allow operation under supercritical conditions at pressures greater than 220 bar and temperatures greater than 375°C and eventually to operate with alkaline electrolyte. More preferably, the electrolyzer 100 can be made in materials such as nickel -based alloy for headers 110, 120 and Graphite or Grafoil for sealing elements 350 which allow operation in above cited condition and eventually with alkaline electrolyte.

[0087] It is further object of the present invention an electrolyzer system for hydrogen production. The system comprises at least one electrolyzer 100 as above described fluidically connected in series. The system further comprises a pump unit and heater unit configured to pipe the electrolyte to the electrolyzer 100 which are fluidically connected upstream to the electrolyzer 100, preferably to the inlet channels 130. Preferably, the pump unit and heater are configured to maintain pressure and temperature of the fluid in the electrolyzer 100 in a specific pressure range for a continuous flow of the fluid. The pressure can be greater than 220 bar and the temperature can be greater than 375°C and electrolyte fluid is selected in alkaline electrolyte. Namely, the pump unit and heater unit are configured to supply an electrolyte fluid and to actively maintain the pressure of the electrolyte fluid greater than 220 bar and the temperature greater than 375°C within the electrolyzer 100, enabling operation under supercritical conditions.

[0088] Preferably, the system further comprises a power source configured to supply electric power to the electrodes. Namely, the power source is electrically connected to the electrodes.

[0089] It is further object of the present invention a process of electrolysis of electrolyte fluid carried out in an electrolyzer system above described.

[0090] The process comprises the step a) of introducing the electrolyte fluid into the first channels 180 through the inlet channels 130.

[0091] The process comprises the step b) of conveying the electrolyte fluid into the reaction chamber 190.

[0092] The process comprises the step c) of electrolyzing through the electrodes 210 in the reaction chamber 190 to produce hydrogen gas and oxygen gas on a relative electrode.

[0093] The process comprises the step d) of separating hydrogen gas and oxygen gas respectively in the first and second electrolyzed fluids to address in respective second channels 200. As a function of flow rate of the electrolyte fluid and separation of the electrolyzed fluids, each electrolyzed fluid is addressed to the relative the second channel 200 proximate to which hydrogen and oxygen are produced by means of electrodes 210, middle portion 190 and the second channel 200.

[0094] As shown schematically in figure 6, the electrolyte is inserted into the inlet channels 130 and channelled to the first channels 180 continuous lines. The electrolyte fluid reaches the reaction chamber 190 wherein the electrolysis is carried out. On the cathode and on the anode are formed respectively hydrogen (dashed line on the right) and oxygen (dashed line on the left). Such hydrogen and oxygen are separated in a first and second electrolyzed fluids which can comprise still electrolyte fluid (continuous line in the second channels and reaction chamber) channelled in the two separated channels 200 and then ejected from the outlet channels 140.

[0095] The process comprises the step e) of ejecting from the headers 110, 120 the first and second electrolyzed fluid from relative outlet channels 140.

[0096] Preferably, steps a)-e) maintains pressure and temperatures during steps a)-e) at supercritical conditions as a function of the electrolyte fluid. Namely, the pressure and temperatures during steps a)-e) are at supercritical conditions as a function of the electrolyte fluid. More preferably, steps a)-e) maintains pressure greater than 220 bar and the temperature greater than 375°C and electrolyte fluid is selected in alkaline electrolyte. Namely, the pressure is greater than 220 bar and the temperature is greater than 375°C and electrolyte fluid is selected in alkaline electrolyte.

[0097] It is noted that steps a)-e) maintain the pressure and temperatures during steps a)-e) of the selected in the above condition by means of a pump unit and a heater and the relative electrolyte fluid in combination of the relative electrolyzer configured to operate in such conditions. According to one embodiment, steps a)-e) are out in continuous way

[0098] The project leading to this application is supported by the Clean Hydrogen Partnership and its members. Co-funded by the European Union. Project X-SEED with Grant Agreement number 101137701. (Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the Clean Hydrogen Partnership. Neither the European Union nor the granting authority can be held responsible for them.)

Claims

CLAIMS1. An electrolyzer (100) for producing hydrogen gas from an electrolyte fluid, comprising:- a first header (110) and a second header (120) mutually coupled along a coupling surface (111, 121), each header (110, 120) extending along a longitudinal direction (L- L) and having a thickness (80) along a transversal direction (T-T) perpendicular to the longitudinal direction (L-L) and extending along a depth direction (D-D) perpendicular to the longitudinal direction (L-L) and to the transversal direction (T- T), each header (110, 120) comprising an inlet channel (130) and an outlet channel (140) spaced apart along the longitudinal direction (L-L) and each header having a recess (150) formed in the thickness (80) from the coupling surface (111, 121) and defining a lateral wall (160);- a frame (170) arranged between the first and second header (110, 120) and configured to define with the lateral wall (160) of the recesses (150):- one or more first channels (180) in fluid communication with a relative inlet channel (130),- a reaction chamber (190) in fluid communication with the first channels (180), and- second channels (200) in fluid communication with the reaction chamber (190) and outlet channels (140);- electrodes (210) arranged in the reaction chamber (190) and mutually spaced apart along the transversal direction (T-T), electrodes (210) being configured to electrolyze the electrolyte fluid entering the reaction chamber (190) from the first channels (180) and to produce hydrogen gas and oxygen gas on a respective electrode (210);- the second channels (200) together with the reaction chamber (190) and electrodes (210) being configured to separate hydrogen gas in a first electrolyzed fluid and oxygen gas in second electrolyzed fluid to channel in a respective second channel (200).

2. The electrolyzer (100) according to claim 1, wherein:- the frame (170) comprises a first wall (220) and a second wall (230) mutually spaced apart along the longitudinal direction (L) defining a middle opening (240);- each lateral wall (160) has a first portion (250) and a second portion (260) and a middle portion (270) connecting the first and second portions (250, 260);- the first portions (250) and the first wall (220) define the first channels (180);- the second portions (260) and the second wall (230) define the second channels (200);- the middle portions (270) define the reaction chamber (190) with the middle opening (240).

3. The electrolyzer (100) according to claim 2, wherein the lateral wall (160) at the middle portion (270) has one or more grooves (280) mutually spaced apart along the depth direction (D-D) configured to define middle channels (290) for the electrolyte fluid and electrolyzed fluids channelling.

4. The electrolyzer (100) according to any of claims 1 to 3, wherein- the first channels (180) are convergent to the reaction chamber (190);- the second channels (200) widen from the reaction chamber (190) along the longitudinal direction (L) towards outlet channels (140);- the reaction chamber (190) widens along the longitudinal direction (L) from the first channels (180) towards the second channel (200) to cooperate with the second channels (200) in electrolyzed fluids separation.

5. The electrolyzer (100) according to any of claims 1 to 4, wherein each header (110, 120) comprises one or more connecting channels (300) configured to put in fluid communication the inlet channel (130) with the first channel (180).

6. The electrolyzer (100) according to any of claims 1 to 5, wherein:- the recesses (150) of the first and second headers (110, 120) define a frame cavity (310);- the frame (170) is arranged in the frame cavity (310) between the first and second header (110, 120).

7. The electrolyzer (100) according to any of claims 1 to 6, wherein:- the electrodes (210) comprise an anode (320) and cathode (330) mutually spaced apart along the transversal direction (T-T), the cathode (330) being configured to produce hydrogen gas and the anode (320) being configured to produce oxygen gas;- the cathode (330) and the anode (320) are associated with a respective second channel (200) to convey with the second channels (200) and the reaction chamber (190) the first and second electrolyzed fluid into respective second channels (200). .

8. The electrolyzer (100) according to any of claim 7, wherein the anode (320) and the cathode (330) are respectively spaced apart from the lateral wall (160) along the transversal direction (T).9.The electrolyzer (100) according to any of claims 1 to 8, wherein the electrodes (210) comprise a mesh body (340).

10. The electrolyzer (100) according to any of claims 1 to 9, further comprising sealing elements (350) arranged between the frame (170) and each header (110, 120) configured to prevent electrolyte fluid, electrolyzed fluid, and gas leakage.

11. The electrolyzer (100) according to any of claims 1 to 10, further comprising retaining assembly (360) configured to mutually retain the headers (110, 120) and the frame (170) therebetween.

12. The electrolyzer (100) according to any of claims 1 to 11, wherein:- the electrolyzer is configured to operate under supercritical conditions with pressures greater than 220 bar and temperatures greater than 375°C;- the electrolyzer is configured to operate with an alkaline electrolyte.

13. An electrolyzer system for hydrogen production comprising:- at least one electrolyzer (100) according to any of claims 1-12;- a pump unit and heater unit fluidically connected upstream to the electrolyzer (100) and configured to pipe the electrolyte to the electrolyzer (100);14. A process of electrolysis of electrolyte fluid carried out in the electrolyzer system according to any of claim 13, the process comprising the steps of:a) introducing the electrolyte fluid into the first channels (180) through the inlet channels (130); b) conveying the electrolyte fluid into the reaction chamber (190); c) electrolyzing through the electrodes (210) in the reaction chamber (190) to produce hydrogen gas and oxygen gas on a relative electrode; d) separating hydrogen gas and oxygen gas respectively in a first and second electrolyzed fluid to address in a respective second channel (200); e) ejecting from the headers (110, 120) the first and second electrolyzed fluid from relative outlet channels (140).

15. The process according to claim 14, wherein the steps a)-e) maintain the pressure and temperatures during steps a)-e) at supercritical conditions as a function of the electrolyte fluid.

16. The process according to claim 14, wherein the steps a)-e) maintain pressure greater than 220 bar and the temperature greater than 375°C and electrolyte fluid is selected in alkaline electrolyte.

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