High-voltage electrolysis device

Abstract

A high pressure electrolyser for generating hydrogen and oxygen is provided, the high pressure electrolyser comprising a plurality of electrolysis units arranged in series, each unit comprising a conductive metal body consisting of an assembly of interconnected horizontal and vertical tubes, the body forming an electrode connectable to a DC power source, the assembly comprising three horizontal tubes and at least two vertical tubes, each of the vertical tubes housing an elongated central electrode and a tubular membrane, each vertical tube together with the central electrode, membrane and electrode forming an electrolysis cell, the electrolysis cells within each unit being connected in parallel, each unit further comprising at least two vertical tubes not housing a central electrode, a first vertical tube connecting the lower horizontal tube to a first upper horizontal tube and a second vertical tube connecting the lower horizontal tube to a second upper horizontal tube.

Description

[Technical field]

[0001] The present invention generally relates to a device for generating hydrogen and oxygen comprising a high-pressure electrolyzer, the electrolyzer including a plurality of high-pressure electrolysis units arranged in series. The present invention also relates to a method for producing high-pressure hydrogen at pressures of 100,000 KPa or more, and by-product oxygen, without the need for a separate compressor to compress the generated hydrogen gas. [Background technology]

[0002] The electrolytic production of hydrogen is well known, see for example WO2004 / 076721 and the U.S. patent publications cited therein.

[0003] As described in the introduction to WO2004 / 076721, known electrolysis devices, also referred to in the art as "electrolyzers", use a liquid electrolyte to generate hydrogen and operate as follows: Two electrodes are placed in a bath of liquid electrolyte, such as a solution of potassium hydroxide (KOH). A wide range of potassium hydroxide concentrations may be used, but typically a KOH solution with a concentration of about 25 to 30% by weight is used. The electrodes are separated from each other by a separator membrane that selectively allows liquid to pass but not gas. When a voltage, typically about 2-3 volts, is applied between the electrodes, a current flows through the electrolyte between the electrodes. Hydrogen gas is produced at the cathode and oxygen gas is produced at the anode. The separator membrane keeps the hydrogen and oxygen gases separated as the generated gas bubbles rise through the liquid electrolyte. Above the liquid electrolyte is a breakaway space that is made up of two separate chambers or sections isolated from each other by an airtight barrier separating them into two separate sections, one chamber or section receiving hydrogen gas and the other receiving oxygen gas. The two gases are removed separately from their respective sections of the disengagement space for storage or venting.

[0004] Currently available electrolysers are primarily low pressure electrolysers of stacked design, where the electrolyser is assembled from prefabricated components. Due to the nature of the stacked design, the pressure is limited to approximately 30 bar.

[0005] High pressure electrolyzers have begun to attract great interest due to their advantages over low pressure electrolyzers in that they are suitable for use in high pressure applications, transportation and storage without the need for downstream compressor stages. Various designs of high pressure electrolyzers have been described in the art, which are often based on polymer electrolyte membrane ("PEM") technology. See, for example, WO2011 / 012507A1. However, a significant drawback of PEM technology is that it requires expensive rare metal material catalysts, and the catalyst layer in the electrolysis cell degrades faster than alkaline electrolysis at various load requirements.

[0006] WO2021 / 029768A1 discloses a high-pressure alkaline electrolysis device, comprising an assembly of conductive metal tubes and pipes constituting either the anode or the cathode, in a channel arrangement of interconnected vertical and horizontal pipes and tubes closed at their outer ends, except for the pipes for the water inlet and hydrogen and oxygen outlet connections, the inner surface of the channel arrangement being coated with an electrically insulating coating, and counter electrodes constituting the cathode or anode, respectively, are disposed in the vertical pipes, enclosed by a cylindrical membrane, and supported and connected by an electrode support rod installed in the horizontal pipe at the top of the housing. The high-pressure electrolysis device further comprises one or more tightly isolated electrical conductors for power supply from the outside to the inside of the electrolysis device.

[0007] WO2004 / 076721A2, which corresponds to EP1597414B1, discloses an electrolyzer cell for the electrolysis of water, comprising a cathode of generally tubular configuration within which is disposed an anode separated from the cathode by a separator membrane of generally tubular configuration, which divides an electrolyte chamber into an anode subchamber and a cathode subchamber. The electrolyzer apparatus includes an array of individual cells, each of which is applied with a potential via leads by a DC generator. Hydrogen gas evolved from the electrolyte in the cells is removed by a hydrogen gas removal line and a hydrogen manifold line. By-product oxygen is removed from the cells by an oxygen gas removal line and an oxygen manifold line.

[0008] NL2023212 discloses a high-voltage electrolysis device comprising a large block of conductive metal constituting either the anode or the cathode, an arrangement of interconnected vertical and horizontal cylindrical channels closed at their outer ends except for channels for the water inlet and hydrogen and oxygen outlet connections, the inner surface of the channel arrangement being partially coated with an electrically insulating coating, and counter electrodes constituting the cathode or anode, respectively, are disposed in the vertical channels and enclosed by a cylindrical membrane, and are supported and connected by an electrode support rod mounted in a horizontal channel at the top of the housing.

[0009] EP 3 498 886 A1 discloses an electrolysis system for carrying out oxidation and reduction reactions, comprising two or more groups of electrolysis cells connected in parallel, each electrolysis cell being formed by at least one pair of electrodes and an electrolyte between the electrodes, said assembly of electrolysis cells defining an electrolysis cell; an energy source providing an electric signal to the electrolysis cell, the electric signal received by the electrolysis cells forming the electrolysis cell corresponding to a direct current pulse, the cells of each electrolysis cell being configured to operate in a charge transient state of each cell during the direct current pulses, and in a discharge transient state of each cell during the times between the direct current pulses, said charge and discharge transient states being defined by the structure of each electrolysis cell in the form of a cylindrical plate capacitor.

[0010] U.S. Patent No. 3,984,303 discloses an electrolytic cell for producing halogen gases and alkali metal hydroxides, the electrolytic cell having a hollow tubular cathode member with a hollow tubular anode member concentrically disposed within the cathode, each electrode member having a liquid-permeable wall allowing circulation of electrolyte. The anode is covered on its outer surface with an electrically conductive tubular membrane of a material selectively permeable to the passage of ions and impermeable to the hydrodynamic flow of the electrolyte, the tubular membrane being attached to the outer surface of the anode, thereby separating the anode and cathode surfaces. Such cells can also be connected in series to form larger multi-cell electrolytic cells.

[0011] There remains a need for a simple, efficient and cost-effective high pressure electrolyser for hydrogen production and other industrial processes that is compact, flexible, modular, scalable and low maintenance. It is an object of the present invention to provide such a high pressure electrolyser. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] WO2004 / 076721 [Patent Document 2] WO2011 / 012507A1 [Patent Document 3] WO2021 / 029768A1 [Patent Document 4] EP1597414B1 [Patent Document 5] WO2004 / 076721A2 [Patent Document 6] NL2023212 [Patent Document 7] EP3498886A1 [Patent Document 8] U.S. Patent No. 3,984,303 [Non-patent literature]

[0013] [Non-Patent Document 1] http: / / www.wermac.org / pipes / pipe_vs_tube.html Summary of the Invention

[0014] In one aspect of the present invention, there is provided a high pressure electrolysis unit for generating hydrogen and oxygen, the high pressure electrolysis unit comprising: a body of conductive metal consisting of an assembly of interconnected horizontal and vertical tubes, said body constituting an electrode: anode or cathode, connectable to a DC power source; The assembly includes three horizontal tubes, a first tube defined as a lower horizontal tube constituting the bottom of the body, and two other tubes defined as a first upper horizontal tube and a second upper horizontal tube, respectively, in adjacent distance to each other at the top of the body; the assembly includes at least two vertical pipes, the vertical pipes being arranged in a row and having a lower outer end and an upper outer end, the lower outer end being connected to the lower horizontal pipe, and the upper outer end being sealed; the vertical pipe extends from the lower horizontal pipe, then interconnects with the second upper horizontal pipe and the first upper horizontal pipe, and further extends beyond the first upper horizontal pipe, the upper exterior forming a top of the body; each of said vertical tubes contains an elongated central electrode electrically isolated therefrom and defining a counter electrode, a cathode or an anode, each central electrode extending from a lower portion of a respective vertical tube and projecting through a seal beyond the upper outer end of said vertical tube, said central electrodes being connectable to a DC power source; a separator membrane of tubular configuration is placed within each vertical tube concentrically between the cathode and the anode, extending from the region between the junction of the vertical tube with the lower horizontal tube and the lower outer end of the central electrode to the region between the second upper horizontal tube and the first upper horizontal tube, dividing the cell into an anode subchamber and a cathode subchamber, said separator membrane being tight against the passage of gas but allowing the passage of liquid and liquid-borne ions; Between the two horizontal tubes of the body, an airtight seal is placed between the separation membrane and the inner wall of the vertical tube, and the airtight seal also supports the membrane; Each central electrode defines an electrolytic cell together with the inner wall of the vertical tube surrounding the central electrode, the tubular membrane, and the electrolyte between the electrodes; The body further includes at least two additional vertical tubes that do not house a center electrode, a first vertical tube connecting the lower horizontal tube to the first upper horizontal tube and a second vertical tube connecting the lower horizontal tube to the second upper horizontal tube.

[0015] In another aspect of the present invention, there is provided a high pressure electrolyser comprising a plurality of high pressure electrolysis units as defined above, electrically connected in series.

[0016] In yet another aspect of the present invention, there is provided a high-pressure electrolyzer comprising a plurality of high-pressure electrolysis units as defined above, and further comprising a cooling and drying unit.

[0017] In a further aspect of the present invention there is provided a device comprising a high pressure electrolyser comprising a plurality of high pressure electrolysis units as defined above and one or more pressure vessels.

[0018] These and other aspects of the present invention will be more fully outlined in the detailed description that follows with reference to a specific embodiment thereof, namely, the production of hydrogen and oxygen by high pressure electrolysis of water, although those skilled in the art will recognize that the present invention may be utilized in other embodiments.

[0019] Conventional and well-known devices such as pressure and flow sensing devices, and controls for operating valves and pumps, have been largely omitted from the description as such devices and their uses are well known in the art. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic front view showing one embodiment of a high-voltage electrolysis unit according to the present invention. [Diagram 2] FIG. 2 is a schematic side view of the electrolysis unit of FIG. [Diagram 3] FIG. 2 is a schematic perspective view of another embodiment of a high-voltage electrolysis unit according to the present invention. [Figure 4] FIG. 13 is a detailed view of the upper part of the vertical tube, with the elongated electrodes attached. [Diagram 5] FIG. 2 shows a partial longitudinal view of an electrolysis cell according to the prior art and a cross-sectional view and a perspective view of an embodiment of an electrolysis cell forming part of a high pressure electrolysis unit according to the present invention; [Figure 6] FIG. 1 is a perspective view of an embodiment of a high-voltage electrolysis unit according to the present invention. [Figure 7] FIG. 1 is a schematic side view of an embodiment of four high voltage electrolysis units according to the present invention in a series arrangement. [Figure 8] FIG. 1 is a perspective view of an embodiment of an electrolyser comprising multiple (16) high-pressure electrolysis units according to the invention in a series arrangement and connected to an evolved gas cooling and drying device. [Figure 9] FIG. 9 is a schematic diagram of the electrolytic cell of FIG. [Figure 10] FIG. 10 is a more detailed schematic diagram of the cooling device of FIG. [Figure 11] 4 is a flow chart of an embodiment of a cooling device for evolved gas in an electrolytic cell according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention.

[0022] The high pressure electrolysis unit according to the invention comprises a body consisting of an assembly of interconnected horizontal and vertical tubes of high pressure, heat resistant, electrically conductive material, without a laminated design. This assembly is used as a containment vessel for the high pressure electrolysis process. High operating pressures are possible and no compression is required for product gas storage and distribution, resulting in increased overall efficiency due to the elimination of the need for downstream product gas compression.

[0023] The terms "tube" and "pipe" are often used interchangeably in the art, although there are differences between them. See, for example, http: / / www.wermac.org / pipes / pipe_vs_tube.html. As used herein, "tube" and "pipe" are collectively referred to as "tube" unless otherwise stated. A person skilled in the art will have no problem understanding which materials are required when applying the design according to the present invention.

[0024] The body of the electrolysis unit constitutes the electrodes: anode or cathode, which are connectable to a DC power source. In a preferred embodiment, the assembly of interconnected horizontal and vertical tubes comprises three horizontal tubes. One tube, hereafter referred to as the lower horizontal tube, constitutes the bottom of the body. The other two tubes, hereafter referred to as the first and second upper horizontal tubes, are at an adjacent distance from each other and form part of the top of the body.

[0025] The assembly of interconnected horizontal and vertical tubes includes at least two, and preferably a plurality of vertical tubes, for example, 3 to 20 to 50 or more vertical tubes. A preferred number of vertical tubes ranges from 15 to 50 per electrolysis unit. The vertical tubes, having lower and upper outer ends, are arranged in a row, with the lower outer ends connected to the lower horizontal tube. The vertical tubes extend from the lower horizontal tube, are interconnected with a second upper horizontal tube and a first upper horizontal tube, and further extend beyond the first upper horizontal tube. The upper outer ends of the vertical tubes form the top of the body and are sealed. In a preferred embodiment, the upper outer ends of the vertical tubes are threaded to facilitate maintenance of the unit and assembly of other components into the vertical tubes. The vertical tubes may be closed with readily available pressure fittings known in the art, such as threaded pressure fittings.

[0026] The vertical tubes are adapted to house elongated electrodes spaced from the walls of the tubes. In a preferred embodiment, each of the vertical tubes houses an elongated central electrode that extends upwardly from a lower portion of the vertical tube and projects beyond the upper outer end of the vertical tube through a seal at said upper outer end. The elongated central electrodes constitute counter electrodes, cathodes or anodes, respectively, relative to the body electrodes, which are connectable to a DC power source. In a preferred embodiment, the elongated central electrodes are solid, cylindrical bar or rod-type electrodes.

[0027] The body is filled with a liquid electrolyte, for example a solution of potassium hydroxide (KOH) in demineralized water. A wide range of potassium hydroxide concentrations may be used, but typically a KOH solution with a concentration of about 25 to 30% by weight is used. The electrodes, i.e. the vertical tubes that are part of the conductor and the central electrode, are exposed to the liquid electrolyte and in contact with it generate gas during operation.

[0028] A separation membrane of tubular configuration is placed in each vertical tube surrounding the central electrode, thus dividing the concentric space within the vertical tube into an anode subchamber and a cathode subchamber, the separation membrane sealing against the passage of gas but allowing the passage of liquid and liquid-borne ions. The separation membrane is supported at the top and extends from the region between the connection of the vertical tube with the lower horizontal tube and the lower outer end of the central electrode to the region of the vertical tube between the second upper horizontal tube and the first upper horizontal tube. In a preferred embodiment, the separation membrane is open at the bottom. In another preferred embodiment, the membrane is a ZIRFON® separation membrane.

[0029] Airtight seals are placed between the separation membrane and the inside wall of the vertical tube between the two upper horizontal tubes. These seals also support the membrane. The top of the center electrode is preferably electrically isolated around its circumference and across the area of ​​the two upper horizontal tubes upward from the seal, preventing gas generation within the two upper horizontal tubes and allowing for high quality of the produced gas.

[0030] Each central electrode, together with the inner wall of the vertical tube in which it is placed, the separator membrane, and the electrolyte between said electrodes, defines an electrolytic cell. In a preferred embodiment, the inner wall of the vertical tube constitutes the anode (+) and the central electrode constitutes the cathode (-) of the electrolytic cell.

[0031] In certain preferred embodiments, the body further comprises at least two vertical tubes that do not house a central electrode. A first vertical tube connects the lower horizontal tube to the first upper horizontal tube and a second vertical tube connects the lower horizontal tube to the second upper horizontal tube. These additional tubes are advantageous for recirculation of electrolyte and improve removal of evolved gases from the electrolysis cell.

[0032] In a preferred embodiment, the high pressure electrolysis unit according to the invention comprises a plurality of two or more electrolysis cells, e.g. 3, 4, 5, 6, 7, 8 or up to 50 cells, which are connected in parallel. In a further preferred embodiment, the tops of the central electrodes are electrically interconnected outside the vertical tube, e.g. by a conductive profile which is then connected to a DC power source.

[0033] In operation, hydrogen gas is produced at the cathode of each electrolysis cell and oxygen gas is produced at the anode. A separation membrane keeps the hydrogen and oxygen gases separate as the generated gas bubbles rise through the liquid electrolyte. Above the liquid electrolyte is a breakaway space consisting of two sections separated from each other by an airtight seal; one section, the first upper horizontal tube, receives hydrogen gas and the other section, the second upper horizontal tube, receives oxygen gas. The two gases are removed separately from each tube for cleaning and drying, storage, transportation, or venting.

[0034] Each electrolysis unit comprises at least one, and preferably two, gas withdrawal connections in liquid and gas flow communication with the respective two upper horizontal tubes for removing from said tubes the gases generated in the electrolysis cells and collected in said tubes, and in addition each unit comprises a connection for a feed conduit for supplying liquid electrolyte or demin-water, preferably to the lower horizontal tube of the unit.

[0035] In a further aspect of the present invention, a high-pressure electrolyser is provided, comprising a plurality of high-pressure electrolysis units, as defined and described above, connected in series. The combined electrolysis units are preferably arranged in an electrically isolated adjacent array, for example in the manner illustrated in Figures 7 and 8. As illustrated in Figure 6, the units are electrically connected as follows: the anode (+) of the body of the first unit is connected to a DC power source, the cathode (-) of the central electrode of the first unit is connected to the body of the second adjacent electrolysis unit, the central electrode of the second electrolysis unit is connected to the body of the next adjacent electrolysis unit, and so on until the last central electrode (-) is connected to a DC power source. The total voltage difference of the series-connected units is equal to the number of units multiplied by the voltage drop of one unit, and is in the range of 2-3 Vdc. The current is equal to the number of parallel cells multiplied by the current through one cell, which depends on the detailed design of the cell and the voltage applied to the cell.

[0036] The high pressure electrolyser according to the present invention comprises at least two electrolysis units, but preferably a plurality, for example at least 10 units, more preferably at least 50 to 150 units. In a preferred embodiment, the electrolysis units are further connected by a common feed conduit for the liquid electrolyte and demineralized water, and a gas withdrawal conduit for hydrogen and oxygen gases.

[0037] The wall thickness of the body of the high pressure unit according to the invention is determined by the desired generated pressure, the material properties such as the yield strength and electrical conductivity of the metal from which the body is made. In general, the wall thickness may vary in the range of about 0.65 to 1.60 cm. Usually, the length of the vertical tube of the high pressure unit ranges from 500 to 2000 mm, and may further extend to 4000 mm. Usually, the diameter of the center electrode is about 30 mm, and may further extend to 100 mm. These values ​​are merely indicative and should not be construed as limiting the invention in any way.

[0038] In a further aspect of the invention, one or more cooling and drying units are provided forming part of the high pressure electrolysis device according to the invention, the cooling and drying units being connected to the outlet conduits for the produced hydrogen gas and oxygen gas.

[0039] In a preferred embodiment, the produced hydrogen and oxygen gases are conveyed to a cooling and drying device where they are cooled by a cooling medium, e.g., cooling water. After cooling, the oxygen gas is depressurized to atmospheric pressure, which further reduces the temperature due to the thermodynamic behavior of oxygen. Then, oxygen at ambient conditions is used to further cool the hydrogen gas, which is still under high pressure. The gas cooling unit is designed such that the condensed water is returned to the electrolysis unit. Condensation of water vapor in downstream systems is avoided. Thus, cooling the hydrogen gas below ambient temperature dries it to a saturation temperature below atmospheric conditions, preventing water condensation in downstream systems.

[0040] In another aspect of the invention there is provided one or more pressure vessels forming part of the electrolysis device according to the invention, the pressure vessels preferably being releasably connected to a cooling and drying unit for storing the dried and purified gas.

[0041] The electrolytic cell according to the invention has several advantages over similar electrolytic cells of the prior art, which are inter alia related to a) high pressure environment, b) gas-liquid separation, c) natural circulation and removal of product gas from the electrolytic cell by gravity effect, d) isolation of the central electrode, e) simplified maintenance of the device, and f) cooling of product gas.

[0042] For high pressure environments, the pressure containment vessel is also one of the electrodes. The coaxial anode / cathode configuration allows for very high pressure hydrogen generation with a practical wall thickness of conventional materials in the containment body provided by the anode. The conventional stacking concept allows for large currents to flow through the system due to the large plates. The perimeter of the plates is also the perimeter that needs to be kept tight. The electrolyzer is designed such that the circumference of the anode / cathode configuration and the openings of the first and second upper horizontal tubes is significantly smaller than the perimeter of the plates in the stacking concept, resulting in a smaller area for possible leakage of flammable gases.

[0043] Higher pressure in the electrolysis unit results in less gas in the electrode area, which in turn results in a larger electrolyte volume, lower electrical resistance and improved efficiency.

[0044] The capability of the apparatus and method of the present invention to enable hydrogen (and oxygen) production at pressures up to 1000 bar or more exceeds the highest pressure of previously known electrolysers. The apparatus and method of the present invention can produce such high pressure hydrogen without the need for a separate compressor to pressurize the product hydrogen gas. The device according to the present invention allows high pressure hydrogen production in a unique manner that reduces component costs and system complexity, resulting in readily available equipment. The device is scalable to any production capacity.

[0045] With regard to gas-liquid separation, the circulation of liquid electrolyte and generated gases is improved by the assembly of horizontal and vertical tubes according to the invention, in particular by two additional vertical tubes connecting the lower horizontal tube with the first and second upper horizontal tubes, respectively. These additional vertical tubes allow downstreaming of electrolyte by hydraulic phenomena in the other vertical tubes due to gas generation in the electrolysis cell. Generated gases are removed from the electrode surfaces by natural ventilation, which improves the capacity of the system. No active circulation system is required. A collection header is included in the electrolysis cell according to the invention to allow or improve natural circulation and gas separation in the high pressure electrolysis unit.

[0046] Regarding the circulation of electrolyte and removal of product gas from the electrolysis cells, the horizontal and vertical tube assemblies of the electrolysis unit of the present invention are designed to eliminate the need for an active circulation system to remove product gas from the electrodes, improving the capacity of the system. Natural ventilation is established by the vertical tubes, which do not house the central electrode and are therefore left open to allow downstream of electrolyte due to hydraulic phenomena in the vertical cells resulting from gas generation in the electrolysis cells. The prior art does not mention these features.

[0047] Regarding the isolation of the central electrode, it is preferred that the central electrode is a solid rod-type electrode. The upper part of the electrode is electrically isolated, preventing gas generation in the collection header, i.e. the two upper horizontal tubes, and allowing high quality gas production. This is an improvement compared to, for example, EP3498886A1, where no measures are disclosed to prevent gas generation in the collection header.

[0048] Regarding maintenance of the device, the outer top of the vertical tube housing the central electrode is preferably threaded and provided with a releasable threaded pressure fitting. Furthermore, the central electrode and surrounding separation membrane are preferably top-supported only, facilitating removal of the central electrode and membrane for maintenance or replacement. Thus, maintenance of the device is simplified, more efficient and less expensive.

[0049] With regard to cooling the product gas, the gas cooling unit of the present invention cools the hydrogen gas to dry it to a saturation temperature below atmospheric conditions, thereby preventing the condensation of water in downstream systems. The prior art is silent on this feature.

[0050] The apparatus and methods of the present invention can be utilized to generate high pressure hydrogen in locations such as: service stations for hydrogen fuel cell vehicles; local energy producers or distributors for retail sale of hydrogen fuel via high pressure canisters; industrial plants such as (petro)chemical plants, power plants, office buildings, etc., for on-site energy storage and / or use as a chemical feedstock, for use in fuel cell or internal combustion engine based heat and / or power production.

[0051] Turning now to the drawings, and with particular reference to Figs. 1-3, there is shown an embodiment of a high pressure electrolysis cell unit with four parallel electrolysis cells, which is made up of an assembly of three horizontal interconnecting tubes 1b, 1c, 1d and four vertical interconnecting tubes 1a arranged in a row, plus two additional vertical tubes 1e and 1f, all made of conductive metal, constituting a conductive body 1 enclosing a pressurized containment vessel of electrolyte and gas. The lower horizontal tube of the body is provided with an inlet 11 for liquid electrolyte or water, and the two upper horizontal tubes 1d, 1c are provided with two gas outlets 12, 13 for the exit of the product gases hydrogen and oxygen, respectively. The body 1 is connectable to a DC power source, in this embodiment an anode (+). The vertical tubes are designated by reference numeral 1a. Each of these tubes contains an electrolysis cell and encloses a counter electrode 2, defined in this embodiment as a cathode (-) centrally located within the vertical tube 1a. The lower horizontal pipe 1b is connected to the vertical pipe 1a at its lower outer end and distributes the electrolyte evenly among the cells forming part of the electrolysis cell unit. The second upper horizontal pipe 1c and the first upper horizontal pipe 1d are at adjacent distances above the vertical pipe 1a and are interconnected with the vertical pipe and equipped with oxygen and hydrogen separation and collection headers (separating electrolyte and gas). Pipes 1e, 1f are downcomers and return excess electrolyte from the horizontal headers 1c, 1d, respectively. The cylindrical membrane 3 is supported by a membrane support and sealing fixture 4, which is concentrically arranged around the central electrode 2 and is tightly fitted to the vertical pipe 1a between the horizontal headers 1c and 1d. The central electrode 2 is supported by a pressure-tight and electrically isolated fixture 5, which is arranged inside the vertical pipe 1a. An electrically conductive connection profile 6 electrically interconnects the counter electrodes 2 arranged in parallel at the top of the assembly, outside the electrolysis cell unit 1. An electrical isolation ring 7 separates the body of the electrolysis cell unit 1 from the electrodes 2 and the conductive connection profile 6 .

[0052] FIG. 4 shows the upper part of the electrolysis cell in more detail, in particular the relative arrangement of the body 1, separation membrane 3 and support and sealing fixture 4, with the electrode 2a, electrode separator 2b, electrode sealing fixture 5 and separator ring 7.

[0053] FIG. 5 shows on the left a schematic diagram of a prior art stack electrolyser cell, while on the right a cross section of a cell according to the invention, namely a vertical tube 1 a equipped with a central electrode 2 and a membrane 3 .

[0054] FIG. 6 shows a three-dimensional view of an embodiment of a high-voltage electrolysis unit with 17 electrolysis cells arranged in parallel, as described in FIGS. 1 to 3.

[0055] Figure 7 is a schematic diagram of four high voltage electrolysis cell units, as described in the previous figures, connected in series. The body 1 of one unit is connected to the central electrode 2 of the adjacent unit by various types of electrical connection profiles 6a, 6b, and 6c. The bodies of each unit are electrically isolated from each other by electrical isolation pads 8.

[0056] FIG. 8 is a perspective view of an embodiment of an electrolytic cell comprising a plurality (16) of high-voltage electrolysis units in a series arrangement and a device for cooling and drying the generated gas connected thereto.

[0057] Figure 9 is a schematic diagram of a part of an electrolysis plant module showing the electrolyzers and the cooling and drying unit of Figure 8, the device including a feed conduit 41 for (demineralized) water, a main extraction conduit 43 for the reaction product hydrogen and a main extraction conduit 42 for the oxidation reaction product (oxygen). Also shown is a feed conduit 44 for the cooling medium. This scheme makes it possible to design one or more modules for the feeding of each unit of cells to meet the current and voltage needs according to the present invention.

[0058] FIG. 10 shows an isometric view of an embodiment of the present invention including a cooling and drying system.

[0059] FIG. 11 shows a schematic diagram of an embodiment of the invention including a cooling and drying system comprising heat exchangers 51, 52 and 53 for hydrogen, heat exchangers 54 and 55 for oxygen, an external cooling system 57 and a pressure reducing station 56.

[0060] operation With the rack empty, all venting devices are placed in the open position and the unit is filled with electrolyte (at the first fill, the electrolyte is a 25-30% solution of potassium hydroxide in demineralized water) until the maximum level in the rack is ensured.

[0061] The electrolysis process is then started by connecting the unit to a DC power source and generating a voltage drop of 2-3V across all electrolysis cells. Hydrogen gas is produced on the surface of the central electrode (cathode) and oxygen is produced on the inner surfaces of the surrounding vertical tubes (anodes). The produced gases rise to the first and second upper horizontal tubes, respectively, for collection and then released to the environment. After some time, when all downstream volumes have been swept away by the produced gases and no air remains in the downstream system, the venting device is closed. Pressure builds up in the system because the volume of produced gases is much larger than the volume of converted water.

[0062] Natural circulation through the downcomer assists in removing the produced gases from the electrolytic cell area and collecting the gases in the header.

[0063] When the operating pressure reaches the gas pressure, the gas pressure control system releases the excess gas to downstream systems such as storage and / or pipeline systems. The water conversion is supplemented with desalinated water when the water level reaches a low or controllable level.

[0064] The produced hydrogen and oxygen gases are cooled by a cooling medium such as cooling water. After cooling, the pressure of the oxygen gas is reduced to ambient pressure, which causes another temperature drop due to the thermodynamic behavior of oxygen. The cold ambient pressure oxygen is then used to further cool the still pressurized hydrogen.

[0065] The cooling system is designed to direct the condensed water vapor back into the electrolyzer cell.

[0066] Cooling the hydrogen gas as described above dries it to a saturation temperature below atmospheric conditions, preventing condensation of water vapor in downstream systems.

[0067] From the above description, those skilled in the art can easily grasp the essential features of the present invention, and can make various changes and modifications to suit various applications and conditions without departing from the spirit and scope of the present invention. Therefore, these changes and modifications are deemed to be within the protection scope of the present invention, as claimed in the appended claims.

Claims

1. 1. A high pressure electrolysis unit for generating hydrogen and oxygen, comprising: a body (1) of conductive metal consisting of an assembly of interconnected horizontal and vertical tubes (1a-1f) constituting electrodes: anode or cathode, connectable to a DC power source; The assembly comprises three horizontal pipes (1b, 1c, 1d), a first pipe defined as the lower horizontal pipe (1b) constituting the bottom of the body, and two other pipes defined as the first upper horizontal pipe (1d) and the second upper horizontal pipe (1c), respectively, which are adjacent to each other at the top of the body; The assembly includes at least two vertical pipes (1 a), arranged in a row, each having a lower outer end and an upper outer end, the lower outer end being connected to the lower horizontal pipe (1 b), and the upper outer end being sealed by a seal (5); the vertical pipe (1a) extends upward from the lower horizontal pipe (1b), then interconnects with the second upper horizontal pipe (1c) and the first upper horizontal pipe (1d), and further extends beyond the first upper horizontal pipe, the upper exterior of which constitutes the top of the body (1); each of said vertical tubes (1 a) houses an elongated central electrode (2) electrically insulated from the vertical tube and defining an opposing electrode: cathode or anode, each central electrode (2) extending from the lower part of the respective vertical tube (1 a), passing through said seal (5) and projecting above the upper outer end of said vertical tube, said central electrodes being connectable to a DC power source; a tubular separation membrane (3) is placed in each vertical tube concentrically between the cathode and the anode, dividing the cell into an anode subchamber and a cathode subchamber, the separation membrane (3) extending from the region between the junction of the vertical tube with the lower horizontal tube (1b) and the lower outer end of the central electrode (2) to the region between the second upper horizontal tube (1c) and the first upper horizontal tube (1d), the separation membrane being tight against the passage of gases but allowing the passage of liquids and ions contained therein; Between the first upper horizontal pipe (1d) and the second horizontal pipe (1c) of the body, an airtight seal (4) is placed between the separation membrane (3) and the inner wall of the vertical pipe (1a), and the seal (4) also supports the membrane (3); Each central electrode (2) defines an electrolysis cell together with the separation membrane (3), the central electrode, the inner wall of the vertical tube (1a) surrounding the central electrode, and the electrolyte provided between the electrodes; The main body (1) further includes two vertical tubes (1e, 1f) that do not house a central electrode, a first vertical tube (1f) connecting the lower horizontal tube (1b) to the first upper horizontal tube (1d), and a second vertical tube connecting the lower horizontal tube (1b) to the second upper horizontal tube (1c).

2. 2. The high-voltage electrolysis unit according to claim 1, wherein upper outer ends of the central electrodes (2) are electrically conductively interconnected, preferably outside the vertical tube (1 a), by means of a profile of electrically conductive material (6).

3. 3. The high-voltage electrolysis unit according to claim 1 or 2, wherein an upper portion of the central electrode (2) is electrically insulated around a periphery above a seal (4) over a portion where the central electrode passes through the two upper horizontal tubes.

4. 3. The high-voltage electrolysis unit according to claim 1 or 2, wherein the seal (4) at the upper outer end of the vertical tube (1 a) and the central electrode (2) are arranged to be releasable, allowing maintenance or replacement of the central electrode (2) and / or the separation membrane (3).

5. 3. A high-voltage electrolysis unit according to claim 1 or 2, wherein the upper end of the vertical tube (1a), which houses the central electrode (2), is threaded (7).

6. 3. The high-pressure electrolysis unit according to claim 1 or 2, wherein the high-pressure electrolysis unit comprises two or more electrolysis cells interconnected in parallel.

7. 3. The high pressure electrolysis unit according to claim 1 or 2, further comprising a fluid supply connection (11) in fluid communication with the electrolysis cell for supplying or filling the electrolysis cell with electrolyte and / or demineralized water.

8. 3. The high pressure electrolysis unit according to claim 1 or 2, further comprising at least one connection (12, 13) for exhausting gas, said at least one connection being in gaseous communication with the electrolytic cell for removing the gas generated in the electrolytic cell.

9. 3. The high-voltage electrolysis unit according to claim 1, wherein the elongated central electrode (2) is rod-shaped.

10. 3. The high-voltage electrolysis unit according to claim 1, wherein the separation membrane (3) is open at a bottom thereof.

11. 3. The high-voltage electrolysis unit according to claim 1 or 2, wherein the separation membrane is a ZIRFON (registered trademark) separation membrane.

12. 3. The high-voltage electrolysis unit according to claim 1 or 2, wherein the main body (1) constitutes an anode (+), the central electrode constitutes a cathode (-), and the vertical tube (+) (1 a), the separation membrane (3), and the central electrode (-) (2) are arranged coaxially.

13. A high-pressure electrolyzer for generating hydrogen and oxygen, comprising a plurality of high-pressure electrolysis units according to claim 1 or 2 connected in series.

14. 14. An apparatus for generating hydrogen and oxygen at high pressure comprising the high pressure electrolyzer of claim 13 in combination with one or more cooling and drying units connected to said high pressure electrolyzer.

15. 14. An apparatus for generating hydrogen and oxygen at high pressure comprising the high pressure electrolyser of claim 13 in combination with one or more containers for storage of the produced hydrogen gas.

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