Hydrogen production plant and methods for operating it

Abstract

Hydrogen production plant (10), comprising several electrolysis devices (11) configured for producing hydrogen from water, comprising a water circuit (13) configured to supply water to the electrolysis devices (11) and to discharge water and oxygen from them, wherein the water circuit (13) comprises a water storage tank (17) from which water can be supplied to the electrolysis devices (11), wherein the water circuit (13) comprises a pump (16) configured to pump the water from the water storage tank (17) towards the electrolysis devices (11), wherein the water circuit (13) comprises an oxygen separator (18) configured to separate oxygen from the water discharged from the electrolysis devices (11) upstream of the water storage tank (17).The oxygen separator (18) has at least one first, horizontally extending separator tube (19) to which water and oxygen can be supplied from the electrolysis devices (11), wherein water can be directed from a first end (19a) of the first separator tube (19) towards the water storage tank (17), and wherein oxygen can be directed from a second end (19b) of the first separator tube (19) towards an oxygen outlet (20). The first separator tube (19) has a roof wall (22) inclined towards the second end (19b) such that oxygen flows along the inclined roof wall (22) towards the second end (19b).

Description

[0001] The invention relates to a hydrogen production plant and a method for operating it.

[0002] DE 10 2017 108 413 A1 discloses an electrolysis device with a cell stack consisting of several cell stack elements, wherein the cell stack elements of the cell stack form several electrolysis cells. Furthermore, the electrolysis device known from this prior art has a force application unit by which a force can be exerted on the cell stack to compress the cell stack elements of the cell stack in a fluid-tight manner. The force application unit has opposing end plates between which the cell stack is arranged and compressed. Connections are provided on the end plates of the electrolysis device, namely water supply connections, water discharge connections, and hydrogen connections. Water is supplied to the electrolysis device via the water supply connections, and water and oxygen are discharged from the electrolysis device via the water discharge connections.The hydrogen connections serve to remove or pass through the hydrogen obtained during electrolysis from the electrolysis device.

[0003] A hydrogen production plant has several electrolysis units and a water circuit, with the electrolysis units integrated into the water circuit. The water circuit is designed to supply water to the electrolysis units and to remove water and oxygen from them. The water, which is deionized water, is stored in a reservoir within the water circuit and pumped from the reservoir to the electrolysis units.

[0004] For the purposes of this document, the term "water cycle" is not to be understood strictly as a closed water cycle. The water cycle is open insofar as water "used" in the electrolysis process can be replenished and / or contaminated water can be removed, and in particular, treated. "Cycle" is to be interpreted in such a way that at least some of the water circulated in the hydrogen production plant can be reused and recirculated.

[0005] In order to reuse deionized water, which is discharged from the electrolysis units along with the oxygen produced during electrolysis, for subsequent electrolysis, the oxygen must be separated from the discharged water. For this purpose, a hydrogen production plant's water circuit includes an oxygen separator.

[0006] EP 2 163 290 A1 discloses a separator for the operation of an electrolyzer. The separator disclosed therein has a cyclone separator. A mixture of water and oxygen can be supplied to the separator via a first connection. The oxygen can be separated using the cyclone separator, with water leaving the separator via a first connection and oxygen via a second connection.

[0007] CN 2 21 141 894 U discloses a hydrogen production plant according to the preamble of claim 1.

[0008] DE 10 2024 100 840 A1, DE 10 2022 116 183 A1, US 2021 / 0 292 919 A1, WO 2019 / 238 218 A1 and WO 2020 / 254 211 A1 disclose further state of the art.

[0009] There is a need to make oxygen removal in the oxygen separator of a hydrogen production plant more efficient. The object of the invention is to provide a hydrogen production plant with a corresponding oxygen separator that allows efficient removal of oxygen from the water discharged by the electrolysis devices, and a method for operating the same.

[0010] This problem is solved by a hydrogen production plant according to claim 1 and a method for operating the same according to claim 13.

[0011] The main idea behind the invention is to integrate the oxygen separation function into existing water circulation pipes, thus minimizing the additional effort required for oxygen separation.

[0012] According to the invention, the oxygen separator has at least one first, horizontally extending separator tube to which water and oxygen can be supplied starting from the electrolysis devices, wherein water can be directed from a first end of the respective first, horizontally extending separator tube in the direction of the water storage tank, and wherein oxygen can be directed from a second end of the respective first, horizontally extending separator tube in the direction of an oxygen outlet.

[0013] The first horizontal separator tube is advantageously designed so that a substantially stratified flow state prevails within it, between the gas phase (oxygen) and the mixed phase (oxygen-enriched water) or liquid (water). Furthermore, an approximately laminar flow can be achieved for each flow layer, thus minimizing backmixing.

[0014] In the area of ​​the first horizontal separator tube, oxygen is effectively separated from the water discharged by the electrolysis devices. The water flows towards the first end of the first horizontal separator tube, and the oxygen flows towards the opposite second end. Thus, oxygen and water flow in opposite directions.

[0015] According to the invention, the first horizontal separator pipe has a roof wall inclined towards its second end, along which oxygen flows towards that end, and preferably also a bottom wall inclined towards its first end, along which water flows towards that end. In one embodiment, the first horizontal separator pipe has a circular cross-section that is advantageously constant along its length. A circular cross-sectional geometry is cost-effective and mechanically stable compared to other cross-sectional shapes. In another embodiment, the first horizontal separator pipe has a rectangular cross-section that is particularly constant along its length. A rectangular cross-sectional geometry allows for better utilization of available space and consequently a more compact design.In the case of a rectangular design of one or each separator pipe, it is advantageous for the long sides of the rectangle to form the roof wall or bottom wall, and the short sides to form the side walls of the separator pipe, since this minimizes the distances that gas bubbles have to travel in order to be able to pass from the mixing phase into the gas phase.

[0016] Both embodiments allow for a particularly advantageous separation of oxygen from water in the area of ​​the respective first, horizontally extending separator tube. Other cross-sectional geometries of the separator tubes are possible.

[0017] Preferably, the oxygen separator has at least a second, horizontally extending separator tube to which water and oxygen can be supplied from the electrolysis devices, wherein water can be directed from a first end of the respective second, horizontally extending separator tube towards the water storage tank, and wherein oxygen can be directed from a second end of the respective second, horizontally extending separator tube towards an oxygen outlet.

[0018] The second horizontal separator pipe is expediently designed in such a way that it has a substantially stratified flow state or a laminar flow.

[0019] In particular, the first end of each first separator pipe and the second end of each second separator pipe are connected on both the water and oxygen sides. This further improves oxygen separation. In this improved design, oxygen is removed from the water both in the area of ​​the at least one first separator pipe and the at least one second separator pipe, as well as in the area of ​​the pipes connecting them on both the water and oxygen sides. The second, horizontal separator pipe is advantageously arranged below the first horizontal separator pipe.

[0020] Preferably, the second, horizontally extending separator pipe has a roof wall inclined towards its second end, along which oxygen flows towards its second end, and / or a bottom wall inclined towards its first end, along which water flows towards its first end. In particular, the second, horizontally extending separator pipe has a rectangular cross-section that is constant along its length. This improves oxygen separation in the area of ​​the second, horizontally extending separator pipe.

[0021] The term "inclined" refers to an inclination relative to the horizontal. Horizontal refers to a perpendicular line or surface opposite the gravity vector. The phase separation of the oxygen separator according to the invention therefore occurs passively by means of gravity.

[0022] By performing oxygen separation in this way, the liquid phase (water) and the gas phase (oxygen) of the two-phase mixture leaving the respective electrolyzer devices can be separated from each other at an early stage. The distance along which water and oxygen travel together is minimized. Thus, the liquid phase is separated from the gas phase at an early stage. Since the phases are largely separated from each other as soon as the water enters the storage tank, the required separation efficiency in the water storage tank is low. The residence times required in the water storage tank for the separation of the remaining gas components can therefore be reduced. The water storage tank can thus be made smaller.Furthermore, by separating the oxygen early, the total volume of gas in the system can be reduced, thereby reducing the risk of explosion in the event of hydrogen passing into the water circuit.

[0023] The terms "roof wall" and "bottom wall" are to be interpreted functionally. With a circular cross-sectional geometry, "roof wall" refers to the upper gas-carrying half of the separator pipe, and "bottom wall" to the lower fluid-carrying half of the separator pipe.

[0024] Preferably, several electrolysis devices are coupled via a common, vertically extending pipe to at least one first, horizontally extending separator pipe. This also serves the efficient separation of oxygen from the water discharged by the electrolysis devices.

[0025] Preferably, the vertically extending pipes serve as additional separator pipes, wherein the vertically extending pipes are coupled at their upper end to a respective first horizontally extending separator pipe, and wherein the vertically extending pipes are preferably coupled at their lower end to a respective second horizontally extending separator pipe. This also serves to further improve oxygen separation in the area of ​​an oxygen separator. Alternatively, the vertical separator pipe(s) can be fluid-tightly sealed at their lower vertical end.

[0026] The vertical pipes can preferably be designed as vortex separators. Vortex separators are defined as separators in which the gas and liquid phases of the two-phase mixture are at least partially separated by centrifugal forces. This is achieved by introducing the two-phase mixture in such a way that a rotating magnetic field is created, causing the lighter components (gas) to be carried further outwards towards the pipe wall than the heavier components (water).

[0027] Against this background, variants of the invention can also be understood as two-, three- or more-stage oxygen separation, wherein the vertical tubes form a first stage, the first or second horizontal tubes a second or third stage and the water reservoir a fourth stage for oxygen separation.

[0028] Pipe cross-sections are advantageously selected in relation to the transport volume such that, on average, more than 30%, and preferably more than 50%, of the internal volume of the horizontal separator pipe(s) carries the gas phase (oxygen) during operation, while the remaining volume is filled with water or the still unseparated two-phase mixture. In other words, the separator pipes are dimensioned larger than would actually be necessary for the pure fluid flow of the two-phase mixture of oxygen and water.

[0029] It is advantageous, alternatively or additionally, to select the pipe cross-sections of the horizontal separator pipes such that the pipe cross-section is at least 1.5, 2 or greater than the sum of the incoming pipe cross-sections leading into the horizontal separator pipe, i.e. the vertically running pipes 21 or the sum of the incoming pipes 15 in the embodiments listed below.

[0030] Advantageously, the angle of inclination of the bottom wall and / or the roof wall of one or the first and / or second horizontal separator pipes is inclined between 1° and 5°, preferably at 2-3°, relative to the horizontal in the direction of water flow. This inclination ensures a flow velocity independent of the pump pressure. In particular, the horizontal separator pipes are self-emptying in the event of a pump failure in the water circuit.

[0031] The angles of inclination of the roof wall and the floor wall can be identical. In this case, the cross-sectional shape is constant along the length of the separator pipe. However, the angles of inclination of the roof wall and the floor wall can also be different. The cross-sectional shape along the length of the separator pipe then tapers; for example, in the case of a circular cross-section, it becomes conical or funnel-shaped.

[0032] By designing the separator tubes as described above, and in particular by specifying the tube diameters, it is possible, among other things, to advantageously influence the flow within the tubes, namely to achieve a stratified and essentially laminar flow rather than a turbulent flow. In a laminar flow, the separation of the liquid and gas phases occurs faster and more completely than in a turbulent flow.

[0033] In a convenient embodiment of the invention, at least 30% of the pipelines, and preferably more than 50%, of the pipelines connecting the electrolysis devices and the water storage tank are designed as separator pipes with substantially laminar flow.

[0034] Another aspect of the invention relates to a method for operating a hydrogen production plant according to the invention.

[0035] The present invention relates in particular to electrolysis devices of the PEM (Polymer Exchange Membrane) type, which are characterized in particular by the fact that (pure) water is used as the electrolyte, wherein this (pure) water is only supplied to the water side of the electrolysis cells of the electrolysis devices, while no electrolyte water is supplied to the hydrogen side of the electrolysis cells of the electrolysis devices, but essentially only hydrogen is removed.

[0036] Preferred embodiments of the invention are set forth in the dependent claims and the following description.

[0037] Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being limited thereto. The drawing shows: Fig. 1a to 1c schematic representations of a first hydrogen production plant according to the invention, Fig. 2 a schematic representation of a second hydrogen production plant according to the invention, Fig. 3a to 3c schematic representations of a third hydrogen production plant according to the invention, Fig. 4a to 4b schematic representations of a fourth hydrogen production plant according to the invention.

[0038] Fig. Figure 1a schematically shows a hydrogen production plant 10 with several electrolysis devices 11, which are set up to produce hydrogen H2 from water H2O using electric current. In the Fig. In the embodiment shown in Figure 1, the electrolysis devices 11 are arranged in six cascades 12, each consisting of four electrolysis devices 11. The number of cascades 12 and the number of electrolysis devices 11 per cascade 12 are purely illustrative.

[0039] The electrolysis devices 11 are supplied with water for hydrogen production via a water circuit 13 of the hydrogen production plant 10 (simplified in the figures). The water circuit 13 may, in particular, include technical devices for water treatment, which are preferably arranged downstream of the water storage tank 17 described in more detail below and upstream of the pump 16 described in more detail below. Furthermore, the electrolysis devices 11 for hydrogen production are connected to an electrical current source or voltage source (not shown) of the hydrogen production plant 10 to supply the electrolysis devices 11 with electrical power for hydrogen production.

[0040] The basic structure of an electrolysis device 11 is known. An electrolysis device 11, here of the PEM type, has several cell stack elements arranged to form a cell stack, the cell stack being arranged and pressed between end plates.

[0041] The end plates of the electrolysis devices 11 each have at least one water supply connection 14, at least one water outlet connection 15, and at least one hydrogen connection (not shown). Water (H₂O) can be supplied to the respective electrolysis device 11 via the water supply connection 14, and water (H₂O) and oxygen (O₂) can be discharged from the respective electrolysis device 11 via the respective water outlet connection 15. Hydrogen (H₂) produced during electrolysis can be discharged from the respective electrolysis device 11 via the at least one hydrogen connection (not shown). The water not used in the electrolysis device by electrolysis, which circulates in the water circuit 13, serves for cooling.

[0042] As already explained, the water is supplied via the water circuit 13, the water circuit 13 comprising a water storage tank 17, a pump 16 for conveying the water from the water storage tank 17 towards the water supply connections 14 of the electrolysis devices 11 and an oxygen separator 18 for separating the oxygen O2 from the water H2O discharged from the water discharge connections 15 of the electrolysis devices 11.

[0043] The oxygen separator 18 in the exemplary embodiment of the Fig. 1a a first, horizontally extending separator pipe 19, to which water H2O and oxygen O2 can be supplied starting from the electrolysis devices 11, namely starting from the water discharge connections 15 of the electrolysis devices 11.

[0044] Starting from a first end 19a of the first, horizontally extending separator pipe 19, water H2O can be directed towards the water storage tank 17. Starting from a second, opposite end 19b of the first, horizontally extending separator pipe 19, oxygen O2 can be directed towards an oxygen outlet 20.

[0045] Such a horizontally oriented separator tube provides a large phase separation surface (i.e., a large contact area between the mixed phase and the gas phase) where the gas and water phases are separated. This large separation surface allows for faster separation than with a smaller one. In particular, the average distance a gas bubble in the two-phase mixture must travel to reach the separation surface is shorter and therefore faster compared to a vertically oriented separator vessel, such as the illustrated storage tank 17. Furthermore, phase separation occurs throughout the entire residence time of the two-phase mixture or water in the horizontal separator tube 19. Pathways in the water circuit downstream of the electrolysis devices where no phase separation occurs are minimized.

[0046] The electrolysis devices 11, grouped into a cascade 12, are each connected by their water discharge connections 15 to a common, vertically running pipe 21, from which water H2O and oxygen O2 are supplied to the Fig. can be fed into the first, horizontal separator pipe 19 shown in 1a.

[0047] The first, horizontally extending separator tube 19 is arranged, viewed vertically, above the electrolysis devices 11 and thus above the cascades 12, and extends along the cascades 12, so that therefore in Fig. 1a the electrolysis devices 11 of the cascades 12 are all coupled to the first horizontal separator pipe 19 via their respective vertically and horizontally extending pipes 21, namely between the two ends 19a, 19b of the respective first horizontally extending separator pipe 19.

[0048] The in Fig. The first, horizontally extending separator pipe 19 shown in Figure 1a has, according to the invention, a roof wall 22 inclined towards the second end 19b, along which oxygen O2 can flow towards the second end 19b and from the second end 19b towards the oxygen outlet 20. Furthermore, in Fig. 1a The horizontally extending separator pipe 19 has a bottom wall 23 inclined towards the first end 19a of the separator pipe 19, along which water H2O flows towards the first end 19a by gravity and from the first end 19a of the separator pipe 19 towards the water storage tank 17. The inclination of the top wall 22 and bottom wall 23 is particularly preferred for effective separation of oxygen O2 from the water H2O. Oxygen and water flow in opposite directions through the first separator pipe 19. Although the separator pipe 19 can in principle have any cross-section, such as a round, polygonal and rectangular cross-section, it is preferred that the Fig. 1a shows the first, horizontal separator pipe 19, which has a rectangular cross-section, whereby the cross-section between the two ends 19a, 19b does not change, i.e., it is constant.

[0049] The water storage tank 17 is positioned vertically relative to the first, horizontally extending separator pipe 19 such that water levels 24 and 25 within the water storage tank 17 and within the separator pipe 19 are at the same geodetic or geometric height. The water level 24 in the water storage tank 17 and the water level 25 in the respective first horizontally extending separator pipe 19 lie in a common horizontal plane.

[0050] Between the first end 19a of the in Fig. A droplet separator 26 is connected between the first, horizontally running separator pipe 19 shown in 1a and the storage tank 17, in which further oxygen can be separated from the water in the area of ​​the droplet separator 26 in order to ultimately introduce water with the lowest possible oxygen content into the storage tank 17 via an introduction device 27 positioned in the water storage tank 17.

[0051] Any oxygen that may still be present in the water within the water storage tank 17 can rise within the water storage tank 17 and be directed via a discharge line 28 towards the oxygen outlet 20.

[0052] Water can be discharged from the water storage tank 17 via a water outlet 29 and supplied to the water supply connections 14 of the electrolysis devices 11 via the pump 16, wherein a vortex breaker 30 works together with the water outlet 29 to supply the water to the electrolysis devices 11 without vortices starting from the water storage tank 17.

[0053] In the area of ​​the water storage tank 17, a detection device 31 for detecting the fill level 24 or water level within the water storage tank 17 is shown.

[0054] The first horizontal separator pipe 19 transitions at its second end 19b into a vertical riser pipe 32, with the oxygen outlet 20 being located at the vertically upper end of this riser pipe 32. The discharge pipe 28 also opens into this riser pipe 32. Further droplet separators are arranged within the riser pipe 32, namely a coarse droplet separator 33 and a fine droplet separator 34, in order to recover as much water as possible.

[0055] The vertically extending pipes 21 can perform an additional separation function for the oxygen upstream of the first, horizontally running separator pipe 19. Fig. Figure 1c shows a detail from the oxygen separator 18 in the area of ​​the outlet of the water discharge connection 15b into the pipe 21. In the area of ​​this outlet, an eddy current generator 35 is arranged, which introduces the water discharged from the water discharge connection 15 of the respective electrolysis device 11 into the vertical pipe 21, forming an eddy flow, in order to begin oxygen separation in the area of ​​the vertically running pipe 21 and to further improve it.

[0056] Fig. Figure 2 shows a second embodiment of a water production plant 10, which differs from the embodiment of the Fig. 1a to 1c differs essentially in that several first, horizontally extending separator pipes 19 are present, which are arranged vertically one above the other and in turn extend between the respective first end 19a and the respective second end 19b along the cascades 12. While in Fig. 1a all electrolysis devices 11 of a cascade 12 are connected via a common vertical pipe 21 to the common first, horizontally running separator pipe 19, are in Fig. 2 the electrolysis devices 11 of a cascade 12 are connected to the electrolysis devices 11 of other cascades 12, which are arranged in the same vertical position, to an individual first horizontal separator tube 19 with their respective water discharge connections 15.

[0057] Starting from the first ends 19a, the water H2O flows within the first, horizontally extending separator pipe 19 towards the water storage tank 17, within which an individual sub-chamber 38a is formed for each of the separator pipes 19 to receive the water flowing over the respective separator pipe 19 towards the water storage tank 17. Oxygen separated within the water storage tank 17 can rise via vent lines 36 and flow via line 28 to the oxygen outlet 20. From the individual receiving chambers 38a, the water can flow via a line 37 into a sub-chamber 38b of the water storage tank 17, in which the water is stored. This water can then be drawn from the water storage tank 17 by the pump 16 and supplied via the water circuit 13 to the water supply connections 14 of the electrolysis devices 11.

[0058] Fig. Figures 3a to 3c show a further embodiment of a hydrogen production plant 10 according to the invention, which is a further development of the embodiment of the Fig. 1a to 1c. In the exemplary embodiment of the Fig. In sections 3a to 3c, the hydrogen production plant 10, namely the oxygen separator 18, has, in addition to the first horizontal separator pipe 19 extending above the electrolysis devices 11 of the cascades 12, a second horizontal separator pipe 39 extending below the electrolysis devices 11 of the cascades 12. Water and oxygen can be supplied to this second horizontal separator pipe 39 from the electrolysis devices 11, just as to the first horizontal separator pipe 19, via the vertical pipes 21 from the water discharge connections 15 of the electrolysis devices 11. Water can be directed from a first end 39a of the second horizontal separator pipe 39 towards the water storage tank 17.Starting from an opposite second end 39b of the second, horizontally running separator tube 39, oxygen can be conducted towards the oxygen outlet 20.

[0059] According to Fig. 3a The first, horizontally extending separator pipe 19 is connected to the second, horizontally extending separator pipe 39 such that the first end 19a of the first separator pipe 19 is connected to the second end 39b of the second separator pipe 39 on both the water and oxygen sides. A vertically extending connecting pipe 40 connects the two separator pipes 19 and 39 at their ends 19a and 39b on the water side, and a vertically extending connecting pipe 41 connects the separator pipes 19 and 39 at their ends 19a and 39b on the oxygen side. Thus, water can flow from the first separator pipe 19 towards the second separator pipe 39 via the connecting pipe 40, and oxygen can flow from the second separator pipe 39 towards the first separator pipe 19 via the connecting pipe 41.Oxygen separated in the area of ​​the first separator pipe 19 flows directly from the first separator pipe 19 towards the oxygen outlet 20. Oxygen separated in the area of ​​the second separator pipe 39 flows from the second separator pipe 39 first via the connecting pipe 41 into the area of ​​the first separator pipe 19 and from there to the oxygen outlet 20.

[0060] In other words, virtually the entire piping of the water circuit 13 thus performs an oxygen separation function. Pipe sections that only perform the function of fluid transport (without oxygen separation) are reduced to a minimum.

[0061] In Fig. 3a A control valve 42 is arranged between the droplet separator 26 and the feed device 27, via which the fill level 24 in the water reservoir 17 and thus also the fill level 25 in the first separator tube 19 can be adjusted.

[0062] The second separator pipe 39, like the first separator pipe 19, has a sloping top wall 44 and a sloping bottom wall 43. Oxygen can flow over the sloping top wall 44, which is inclined towards the second end 39b of the second, vertically extending separator pipe 39. Water can flow over the sloping bottom wall 43 towards the first end 39a of the second separator pipe 39. Oxygen and water flow through the second separator pipe 39 in opposite directions.

[0063] The second separator tube 39 is designed in a cross-section that is in particular identical to that of the first separator tube 19, and therefore preferably has a rectangular cross-section that is constant over its length.

[0064] In the exemplary embodiment of the Fig. 3a to 3c the vertically running pipes 21 are connected to both separator pipes 19, 39, namely at an upper end of the respective vertically running pipe with the first, horizontally running separator pipe 19 and at a lower end of the respective vertically running pipe 21 with the second, horizontally running separator pipe 39.

[0065] Fig. 4a, Fig. Figure 4b shows a modification of the water production plant 10 of the Fig. 3a to 3c, wherein the embodiment of the Fig. 4a, Fig. 4b of the embodiment of the Fig. 3a to 3c differs by the water-side connection of the horizontally running separator pipes 19, 39 in the area of ​​their ends 19a, 39b. The design of the Fig. 4a, Fig. 4b is structurally simpler than the design of the Fig. 3a to 3c, the design of the Fig. However, 3a to 3c has advantages with regard to the separation of the water flow from the oxygen flow.

[0066] While in Fig. 3a to 3c the connecting pipe 40 at the bottom walls 23, 43 of the separator pipes 19, 39 and the connecting pipe 41 at the roof walls 22, 44 of the separator pipes 19, 39, engages in Fig. 4a, Fig. 4b the connecting pipe 40 laterally to the separator pipes 19, 39 and the connecting pipe 41 to the roof walls 22, 44 of the separator pipes 19, 39. Reference symbol list 10 hydrogen production plants 11 Electrolysis device 12 Cascade 13 Water cycle 14 Water supply connection 15 Water drainage connection 16 pump 17 water storage tanks 18 oxygen separators 19 separator pipe 19a first end 19b second end 20 Oxygen outlet 21 pipe 22 Roof wall 23 Floor wall 24 water levels 25 water levels 26 droplet separators 27 Insertion device 28 Drain line 29 Water outlet 30 vortex breakers 31 Recording device 32 riser pipe 33 Coarse droplet separators 34 fine droplet separators 35 Eddy current generator 36 vent lines 37 Management 38a Subchapter 38b Subchapter 39 separator pipe 39a first end 39b second end 40 connecting pipe 41 Connecting pipe 42 Control valve 43 Floor wall 44 Roof wall

Claims

[1] Hydrogen production plant (10), with several electrolysis devices (11) designed to produce hydrogen from water using electric current, whereby oxygen is also produced during the production of hydrogen, with a water circuit (13) which is set up to supply water to the electrolysis devices (11) and to remove water and oxygen from the electrolysis devices (11), wherein the water circuit (13) has a water storage tank (17) from which water can be supplied to the electrolysis devices (11), wherein the water circuit (13) includes a pump (16) which is configured to pump the water from the water storage tank (17) towards the electrolysis devices (11), wherein the water circuit (13) includes an oxygen separator (18) which is configured to separate oxygen from the water discharged from the electrolysis devices (11) upstream of the water storage tank (17), characterized by , that the oxygen separator (18) has at least one first, horizontally extending separator tube (19) to which water and oxygen can be supplied starting from the electrolysis devices (11), starting from a first end (19a) of the respective first horizontal separator pipe (19) water can be directed towards the water storage tank (17), Starting from a second end (19b) of the respective first, horizontally running separator tube (19), oxygen can be directed towards an oxygen outlet (20), The respective first horizontal separator pipe (19) has a roof wall (22) inclined towards the second end (19b) of the same, such that oxygen flows along the inclined roof wall (22) towards the second end (19b) of the same. [2] Hydrogen production plant according to claim 1, characterized by , that the respective first horizontal separator pipe (19) has a bottom wall (23) inclined towards the first end (19a) of the same, such that water flows along the inclined bottom wall (23) towards the first end (19a) of the same. [3] Hydrogen production plant according to claim 1 or 2, characterized by , that the respective first separator pipe (19) has a rectangular cross-section of constant length with long and short sides, the long sides of the rectangle forming the roof wall (22) and bottom wall (23). [4] Hydrogen production plant according to any one of claims 1 to 3, characterized by , that several electrolysis devices (11) are fluidically coupled via a common, vertically extending pipe (21) to a respective first, horizontally extending separator pipe (19). [5] Hydrogen production plant according to any one of claims 1 to 4, characterized by , that the oxygen separator (18) has at least a second, horizontally extending separator tube (39) to which water and oxygen can be supplied from the electrolysis devices (11), Starting from a first end (39a) of the respective second, horizontally running separator pipe (39), water can be directed towards the water storage tank (17), oxygen can be directed from a second end (39b) of the respective second horizontal separator tube (39) towards the oxygen outlet (20). [6] Hydrogen production plant according to claim 5, characterized by , that each second horizontal separator pipe (39) is connected to each first horizontal separator pipe (19) in such a way that the first end (19a) of each first separator pipe (19) and the second end (39b) of each second separator pipe (29) are connected on both the water side and the oxygen side. [7] Hydrogen production plant according to claim 5 or 6, characterized by , that the respective second horizontal separator pipe (39) has a roof wall (44) inclined towards the second end (39b) of the same, such that oxygen flows along the inclined roof wall (44) towards the second end (39b) of the same. [8] Hydrogen production plant according to any one of claims 5 to 7, characterized by, that the respective second horizontal separator pipe (39) has a bottom wall (43) inclined towards the first end (39a) of the same, such that water flows along the inclined bottom wall (39) towards the first end (39a) of the same. [9] Hydrogen production plant according to any one of claims 5 to 8, characterized by , that the respective second separator tube (39) has a rectangular cross-section that is constant over its length. [10] Hydrogen production plant according to claim 4 and according to any one of claims 5 to 9, characterized by , that the vertically running pipes (21) serve as additional separator pipes, the vertically extending pipes (21) are coupled at an upper end to a respective first horizontally extending separator pipe (19), the vertically running pipes (21) are coupled at a lower end to a respective second horizontally running separator pipe (39). [11] Hydrogen production plant according to any one of claims 1 to 10, characterized by , that the water storage tank (17) is arranged at such a vertical height that a level of water (24) in the water storage tank (17) and a level of water (25) in the respective first horizontal separator pipe (19) lie in a common horizontal plane. [12] Hydrogen production plant (10) according to any one of claims 1 to 11, characterized by , that the inclination angle of the roof wall (43) and the bottom wall (44) of one or the first and / or second horizontal separator pipes (19, 39) is between 1° and 5° relative to the horizontal in the direction of water flow. [13] Method for operating a hydrogen production plant (10) according to one of claims 1 to 12, wherein the water is circulated in the water circuit (13), the water circuit comprising, in the direction of flow, the pump (16), the water supply lines (14) to the electrolysis devices (11), the water outlets (15), the first horizontal separator tube (19) and the water storage tank (17), characterized by , that a layered flow of fluid phase and gas phase forms in the horizontal separator tube (19). [14] Method according to claim 13, characterized by, that a vertical separator tube (21) is arranged between the water outlets (15) of the electrolysis devices (11) and the horizontal separator tube (19), wherein the tubes (19, 21) are each arranged such that the oxygenated water flows first in a vortex manner in the vertical separator tube (21) and subsequently in a laminar flow in the horizontal separator tube (19) for efficient oxygen separation.

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