System for solid oxide electrolysis

Abstract

The invention relates to a system (1) for solid oxide electrolysis, comprising a plurality of electrolysis units (4) arranged side by side on a mounting surface (3), wherein the electrolysis units (4) each have a base unit (5) and a stack (6) of solid oxide electrolysis cells, wherein the base unit (5) has feedthroughs (7) for fluids which are coupled to the adjacent electrolysis units (4), and wherein the base unit (5) is designed as a heat exchanger (8) such that a first thermal layer is present at a first height of the base unit (5) with respect to the mounting surface (3), and wherein the stack (6) is arranged such that a second thermal layer with a different temperature is present at the lower end of the stack (6).

Description

[0001] The present invention relates to a system comprising a device for solid oxide electrolysis.

[0002] In typical applications, one or more stacks of solid oxide electrolysis cells are usually installed in so-called hotboxes.

[0003] The design results in particular from the usual central gas supply and discharge.

[0004] The gas is supplied to / from the stacks via a so-called base plate with integrated channels.

[0005] Both incoming fluid, especially water vapor, and outgoing gases, such as hydrogen and oxygen, are directed in such a way that they are fed to a heat exchanger, which is located upstream of the base plate in the hotbox when the fluids are supplied.

[0006] This means that the gas lines for the incoming and outgoing gases, as well as any adjacent structural components, are comparatively hot (usually up to 900°C).

[0007] The described arrangement is still not easily scalable with respect to the number of stacks arranged in the hotbox.

[0008] The published state of the art in this regard can be found, for example, in EP 3281245 B1.

[0009] The described arrangement is at least partially modified by the invention according to the claims.

[0010] In particular, a system for solid oxide electrolysis is disclosed.

[0011] The system can be a device.

[0012] The system comprises at least a plurality of electrolysis units. The electrolysis units are preferably arranged side by side and / or at the same height within the system.

[0013] In particular, the electrolysis units can be arranged on the same installation surface, which acts as a support for the electrolysis units.

[0014] The electrolysis units of the system are preferably easily interchangeable as a whole and each comprise a base unit and a stack of solid oxide electrolysis cells (SOEC) arranged perpendicularly to the base unit.

[0015] The base unit and the stack are arranged one above the other in the stacking direction. The base unit can be positioned below or above the stack.

[0016] If the base unit is mounted below the stack, the base unit advantageously also acts as a mechanical support for the stack and can also be referred to as the base of the electrolysis unit.

[0017] If, however, the base unit is attached to the top of the stack, it can function as a mechanical suspension. Alternatively or additionally, a support, such as a support plate, can be provided beneath the stack next to the base unit, on which the stack rests.

[0018] The base unit and the solid oxide electrolysis cells preferably have the same dimensions in directions perpendicular to the stacking direction, which are also referred to here as length and width.

[0019] In the stacking direction, the base unit and the solid oxide electrolysis cells can have different heights, with the solid oxide electrolysis cells preferably all having the same height. More preferably, the base unit and the solid oxide electrolysis cell all have the same height.

[0020] In addition to its mechanical support or suspension function, the basic unit also has at least one passage for fluids, preferably at least two passages for two different fluids, which can thus be conveyed separately.

[0021] It is also possible to have three feedthroughs for three fluids or more feedthroughs.

[0022] The main direction of the feedthroughs runs perpendicular to the stacking direction of the electrolysis cells.

[0023] The feedthroughs are each coupled to the corresponding feedthroughs of the base units of the adjacent electrolysis units, so that the respective fluid can be distributed between the electrolysis units.

[0024] In other words, the basic unit preferably has a feedthrough for a first fluid, which is connected to adjacent feedthroughs to form a continuous pipeline.

[0025] Furthermore, the basic unit preferably has a separate feedthrough for a second fluid, which is also connected to adjacent feedthroughs to form a pipeline for a second fluid, so that the first and the second fluid can flow through as many of the electrolysis units provided in the system as possible via the corresponding pipelines.

[0026] During operation, the fluids are added to or removed from the solid oxide electrolysis cells to enable the electrolysis units to function.

[0027] The basic unit has a feed for the first of the two fluids from the feedthrough to the stack and a discharge for the second of the two fluids from the stack to the feedthrough.

[0028] The basic unit is advantageously designed as a heat exchanger between the supply and the discharge.

[0029] During operation, the supplied first fluid is heated, while the discharged second fluid is cooled.

[0030] In further embodiments, outlets for two fluids to two different feedthroughs (e.g., an oxygen-containing fluid and a hydrogen-containing fluid) can also be provided. This does not change the basic principle of the heat exchanger.

[0031] Preferably, the heat transfer from the second fluid to the first fluid is sufficient to preheat the second fluid sufficiently so that the second fluid has the required temperature to be introduced into the electrolysis unit.

[0032] As an alternative, an additional heater, for example an electric one, can be provided in the base unit to further heat the supplied fluid.

[0033] The base unit can, for example, also be equipped with sensors that detect the temperature of the first fluid before it enters the stack, so that the heater can be switched on or off or regulated as needed, depending on the sensor signal, to further (additionally) heat the first fluid.

[0034] During operation, the temperature in the heat exchanger increases in the direction towards the electrolysis unit and decreases in the direction away from the electrolysis unit.

[0035] The heat exchanger is designed such that, in an active operating state, i.e., during operation of the electrolysis units or during electrolysis, a defined first temperature is established at a first height of the base unit relative to the installation surface, thereby forming a first thermal level, and the stack is arranged such that, in the active operating state, a second temperature is established at the lower end of the stack, thereby forming a second thermal level.

[0036] In this text, height is always defined as a dimension in the direction of the stacking direction of the electrolysis unit.

[0037] The second thermal layer has a temperature that is higher than that of the first thermal layer.

[0038] In particular, the second thermal level is the thermal environment in which the electrolysis reaction takes place in the electrolysis unit, namely in the stack of electrolysis cells.

[0039] The second thermal level therefore represents the temperature that occurs in the solid oxide electrolysis cells during operation. This second temperature ranges between 700 °C and 900 °C, and specifically between 800 °C and 875 °C, for example, 850 °C.

[0040] The first thermal layer has a temperature that is significantly cooler than the temperature of the second thermal layer during operation.

[0041] The cooler first thermal layer allows the electrolysis unit to be mechanically clamped, electrically contacted, and lines for the supply and removal of fluids to be connected, as described above, without having to consider special requirements in the design or material selection due to a very high temperature regime, as prevails in the second thermal layer.

[0042] The first temperature is between 150 °C and 500 °C, and in particular between 200 °C and 400 °C, for example 300 °C.

[0043] According to one interpretation, the first fluid supplied contains at least water vapor, and in particular more water vapor than hydrogen.

[0044] According to one interpretation, the discharged second fluid contains at least hydrogen, in particular hydrogen gas, and in particular more hydrogen than water vapor.

[0045] The water vapor is supplied to the solid oxide electrolysis cells as a reactant in the first fluid, while hydrogen is produced as a product during electrolysis and is removed in the second fluid.

[0046] Additionally, the fluids may contain other gaseous or liquid components.

[0047] For example, the first fluid may contain carbon dioxide and the second fluid may contain, for example, carbon monoxide and / or other carbon-oxygen compounds.

[0048] Furthermore, oxygen is produced as a product of electrolysis, which is preferably released directly into the environment of the electrolysis cells.

[0049] According to one embodiment, the stack has a bottom end and an top end, as well as a plurality of cells arranged between the bottom and top ends. The direction in which the cells are stacked is called the stacking direction, and the corresponding dimension in the stacking direction is called the height.

[0050] According to one embodiment, the base unit and the stack are coupled at its lower end, so that the base unit is designed as a plinth or foot between the mounting surface and the stack.

[0051] The base unit then also serves as a mechanical support, over which the stack stands on the installation surface and is optionally also secured.

[0052] Alternatively, in one embodiment the base unit and the stack are coupled at its upper end, so that the base unit is designed as a suspension for the stack.

[0053] The stack can then be mechanically attached to the suspension and thus be firmly arranged in the existing system.

[0054] In one embodiment, the system can be, in particular, a closed device comprising a pressure vessel in the interior of which the other components of the system are arranged.

[0055] The pressure vessel preferably also has a thermal insulation layer within the inner wall, so that an outer wall of the pressure vessel can be kept cool and the interior of the pressure vessel can be heated to a warmer operating temperature.

[0056] This has the particular advantage that the outer wall of the pressure vessel does not need to be designed for the greatly increased temperatures at which electrolysis takes place.

[0057] The installation surface preferably forms a uniform plane within the pressure vessel, on which the individual electrolysis units are placed.

[0058] The electrical connections and fluid lines in the system are preferably arranged directly above the installation surface. This is particularly advantageous if a comparatively cooler temperature prevails in this area, especially in a lower section of the pressure vessel, than in the upper section of the pressure vessel, which is heated during operation by the stacks of electrolysis cells located there, or which has higher temperatures.

[0059] According to one embodiment, a gas slide valve is provided in the feed, so that the supply of the first fluid from the base unit to the stack is adjustable.

[0060] The interconnected feedthroughs for the fluids of the adjacent electrolysis units preferably form a continuous fluid line. From this continuous fluid line, the first fluid flows through the respective feeds, which are designed as heat exchangers, into the electrolysis cells, as described above.

[0061] By closing a feeder, the fluid supply to an electrolysis unit can be selectively stopped, thus taking this electrolysis unit out of service.

[0062] This can be advantageous, for example, if the system is only to be operated with a portion of the existing electrolysis units, for instance due to capacity constraints or defects.

[0063] According to one embodiment, the base unit and the stack are coupled in such a way that a mechanical, a thermal, or a mechanical and a thermal coupling takes place.

[0064] Mechanical coupling here means, in particular, that the base unit and the stack are firmly connected. Specifically, the base unit functions as a mechanical support, for example as a base or as a suspension for the stack.

[0065] The base unit positions the stack in the system, for example in the device which is limited by the pressure vessel, at a defined location and secures it within the system.

[0066] Thermal coupling, in this context, means that heat can be transferred directly from the stack to the base unit and vice versa during operation. Therefore, no thermal insulation is provided between the base unit and the stack.

[0067] In particular, a surface of the base unit adjacent to the surface of the stack preferably has approximately the same temperature as the adjacent surface of the stack.

[0068] According to one embodiment, the base unit and the stack are mechanically coupled by an externally applied pressure force.

[0069] Where "externally applied" means that the pressure is built up by a device separate from the base unit and the stack.

[0070] In particular, the base unit and the stack are clamped in a clamping device, the clamping device bearing against the outward-facing sides of the base unit and the stack. In other words, the clamping device preferably rests against the electrolysis unit from below and above.

[0071] For this purpose, the clamping device preferably comprises a clamping unit and a plate, as a clamping cover, wherein the plate rests on the outside of the stack, for example at the top of the stack, or alternatively on the outside of the electrolysis unit, for example at the bottom of the base unit.

[0072] The plate can be permanently attached to the electrolysis unit.

[0073] The plate and the clamping unit are connected by at least two rods that are arranged laterally next to the electrolysis unit and are under mechanical tension, so that the rods compress the stack, in particular the individual cells of the stack, and the base unit.

[0074] In other words, the rods are subjected to tension and the electrolysis unit to compression.

[0075] The mechanical tension is applied via the clamping unit, which is preferably located in the area of ​​the cool temperature regime, in particular at the bottom of the electrolysis unit.

[0076] According to one embodiment, the clamping unit is located on the base unit in a cool area outside the area between the stack and the first thermal layer, preferably in an area below the area between the stack and the first thermal layer.

[0077] The clamping device or its clamping unit can, for example, include appropriate screw connections or a spring.

[0078] The clamping unit is connected to the electrolysis unit, so that the stack of solid oxide electrolysis cells between the plate and the base unit is subjected to pressure.

[0079] One advantage of the arrangement in the cooler temperature range is that the mechanical clamping device does not necessarily have to withstand the stress at high temperatures of the electrolysis unit.

[0080] The clamping device may, for example, also include a spring that is not resistant to high temperatures.

[0081] According to one embodiment, the base unit has two halves in the vertical direction, with the first thermal plane being formed in the half of the base unit furthest from the stack.

[0082] The first thermal layer can be defined, in particular, at a position adjacent to the fluid feedthroughs in the base unit. The inlets and outlets, which function as heat exchangers, are arranged between the position of the first thermal layer and the stack of electrolysis cells, the outer end of which defines the second thermal layer.

[0083] According to one embodiment, the feedthroughs are formed in a cool area outside the area between the stack and the first thermal layer, preferably in an area below the area between the stack and the first thermal layer.

[0084] The feedthroughs are therefore no longer part of the heat exchanger, but are located in the area of ​​the previously defined cool temperature regime.

[0085] In particular, the passages for the fluids are thus formed in the base unit between the first thermal level and the installation surface, provided that the base unit is advantageously attached to the bottom of the stack and serves as a base.

[0086] According to one embodiment, the base unit is advantageously designed to absorb an additional surface pressure on the stack of electrolysis cells, from 0 N / mm² (Newtons per square millimeter) up to and including 5 N / mm², in addition to the base unit's own weight.

[0087] As previously described, the basic unit can in further versions additionally have a heater, e.g. an electric heater, which is suitable for heating the fluid, in particular the supplied water vapor-containing fluid, in the feed.

[0088] According to further details, the base unit and the stack are preferably coupled in such a way that an electrical coupling also takes place between the stack and the base unit.

[0089] This means, in particular, that the base unit and the stack are in electrical contact and no electrical insulation is provided between the base unit and the stack.

[0090] According to one embodiment, the electrical contacting on the base unit takes place in a cool area outside the area between the stack and the first thermal layer, preferably in an area below the area between the stack and the first thermal layer.

[0091] This is particularly advantageous because, in this case, no further challenges due to a significantly increased temperature, especially the operating temperature of the electrolysis cells, need to be taken into account when making electrical contacts.

[0092] The electrical peripherals, such as electrical wiring, can thus be advantageously arranged and installed in the cool environment, preferably on or under the installation surface. This effectively prevents, for example, unwanted overheating of electrical components.

[0093] This also saves space and allows for an advantageously compact design of the device.

[0094] The electrical contact serves to transmit direct current and is generally achieved via two contact points, one of which forms the positive terminal (shown with "+" in the figures) and the other the negative terminal (shown with "-" in the figures). Preferably, the first contact point on the stack forms the negative terminal and the second contact point on the base unit forms the positive terminal. However, the contact can also be configured in reverse.

[0095] Preferably, one of the contact points is located on the base unit and one of the contact points is located on the clamping device, for example directly on the clamping unit or on one or both of the bars.

[0096] The end of the stack pointing away from the base unit, preferably the upper end, is then electrically contacted via the preferably electrically conductive clamping device, since the clamping device is in direct mechanical and electrical contact with the corresponding end of the stack.

[0097] The clamping device is electrically insulated from the base unit with which it is also in mechanical contact.

[0098] In particular, according to a special embodiment, the electrical contacting is formed at least partially on the base unit between the first thermal layer and the installation surface.

[0099] A first contact point is then provided on the clamping device as described above.

[0100] A second contact point is provided, for example, at a lower end or on the side of the base unit.

[0101] In particular, an electrically conductive metal sheet can be provided for this purpose, which rests against the bottom of the base unit.

[0102] Alternatively, the second contact point can be formed on mechanical supports laterally on the base unit.

[0103] According to preferred embodiments, the electrical contact on the stack is thus made via the clamping device, wherein the clamping device is electrically in contact with an end of the stack that points away from the base unit, preferably an upper end.

[0104] The invention is described in detail below with reference to the figures. These are exemplary embodiments whose features can be combined in any way according to the invention. The invention is not limited to the exemplary embodiments shown.

[0105] The figures show: Figure 1 Figure 1 shows a schematic representation of an embodiment of the device comprising a pressure vessel, an exemplary electrolysis unit with clamping device, a stack of solid oxide electrolysis cells and a base unit. Figure 2Figure 1 schematically shows a cross-section through a pressure vessel with a vessel wall, insulation, a base, and several electrolysis units. Figure 3 Figure 1 schematically shows a first embodiment of the lower end of an electrolysis unit with the base unit, the clamping device and the electrical contact. Figure 4 Figure 1 schematically shows a second embodiment of the lower end of an electrolysis unit with the base unit, the clamping device and the electrical contact. Figure 5 Figure 1 schematically shows a third embodiment of the lower end of an electrolysis unit with the base unit, the clamping device and the electrical contact. Figure 6 Figure 1 schematically shows an embodiment for connecting the fluid feedthroughs of adjacent electrolysis units. Figure 7 : shows an exemplary embodiment of a specific implementation of the basic unit. Figure 8Figure 1 shows an exemplary embodiment for the specific implementation of the connection of the fluid feedthroughs of adjacent electrolysis units based on the diagram in Figure 2. Figure 7 electrolysis unit shown. Figure 9 : shows a schematic representation of an alternative embodiment with a difference compared to Figure 1 reverse-arranged electrolysis unit.

[0106] In Figure 1 The system is represented by example as device 1.

[0107] The exemplary device 1 comprises a pressure vessel 2.

[0108] Pressure vessel 2 consists of at least one outer vessel wall capable of withstanding a high pressure differential between an internal and an external pressure. "Internal" always refers to the interior of the pressure vessel, and "external" to the area outside the pressure vessel.

[0109] To increase the mechanical strength and durability of the pressure vessel, it is advantageous for the vessel wall to be at approximately ambient temperature, meaning it is hardly heated from the inside of the pressure vessel. This can be achieved by providing insulation on the inside of the vessel wall, which acts as a thermal insulator.

[0110] The insulation can consist of one or more layers.

[0111] Inside the pressure vessel, a mounting surface 3 is provided. The mounting surface 3 can, in particular, be a surface of a mounting device.

[0112] In this example, the mounting surface 3 is arranged horizontally in a lower area of ​​the pressure vessel 2.

[0113] The installation surface 3 is a flat surface that offers a possibility for setting up and securing the electrolysis units arranged in the pressure vessel 2.

[0114] One or more electrolysis units 4 can be arranged on the installation surface 3 and fixed to it by suitable devices such as transport rails.

[0115] The electrolysis units 4 can, for example, be arranged in one or more rows or in a circular arrangement.

[0116] Advantageously, the devices for fluid transport to and from the electrolysis units 4, for electrical connection and electrical contacting of the electrolysis units 4 and for mechanical clamping of the electrolysis units 4 are also provided in the area of ​​the installation surface 3.

[0117] In Figure 1 An exemplary electrolysis unit 4 is shown schematically. The electrolysis unit 4 comprises a base unit 5 and a stack 6 of electrolysis cells in which the actual electrolysis reaction to form the gases hydrogen and oxygen from water (vapor) takes place.

[0118] Stack 6 is in particular a stack of several solid oxide electrolyzer cells (SOECs).

[0119] The stacking direction of stack 6 runs from bottom to top, i.e. perpendicular to the support surface 3.

[0120] In the example, the base unit 5 is arranged below the stack 6 and thus serves as a base or foot for the stack 6, with the stack 6 being arranged on the base unit 5 and attached to the mounting surface 3 via the base unit 5.

[0121] In other examples (see example in Figure 11 below), the base unit 5 can also be provided as a suspension at the upper end of the stack 6, i.e., at the opposite end from the support surface 3. The suspension can then be attached to a suspension device that is alternative to the support surface.

[0122] The basic unit 5 further includes inside passages 7 for the flow of fluids, inlets and outlets for the fluids into or out of the stack 6 of the electrolysis cells and a heat exchanger 8, which is formed between the inlets and outlets of the fluids.

[0123] The exemplary base unit 5 includes the two feedthroughs 7 shown. The feedthroughs 7 are preferably arranged at the lower end of the base unit 5, facing the mounting surface 3. The feedthroughs 7 and the fluids they contain should preferably remain as cool as possible to avoid increased thermomechanical stress and prevent undesirable heating of the fluids, and should therefore be arranged as far away as possible from the warmer stack 6 of the electrolysis cells.

[0124] In one of the two passages 7, a first fluid containing water vapor is conveyed, in a second of the passages 7, a second fluid containing hydrogen is conveyed.

[0125] The water vapor from the first fluid is at least partially broken down into oxygen and hydrogen in the electrolysis cells, and the resulting hydrogen is carried away as a product in the second fluid, while the oxygen escapes, for example, directly into the interior of the pressure vessel and from there into the environment.

[0126] From the first passage 7, which contains comparatively cool water vapor of approximately 150 °C to 500 °C, preferably up to 300 °C, a feed for the first fluid to the stack 6 is provided in the base unit 5, while from the comparatively warm stack 6 with an operating temperature during electrolysis of approximately 700 °C to 900 °C, a discharge for the second fluid with the resulting water vapor to the associated passage 7 for the second fluid is provided.

[0127] Between the stack 6 and the feedthroughs 7, a heat exchanger 8 is configured in the base unit 5 between the appropriately routed inlets and outlets.

[0128] Thus, at least two thermal levels are created in the electrolysis unit 4: a first thermal level A comprises a lower area in the base unit 5 below the heat exchanger 8 and has a comparatively cool temperature of preferably about 150 °C to 500 °C, preferably up to 300 °C.

[0129] A second thermal layer B begins at the bottom of the stack 6, bordering the base unit 5, and exhibits the high operating temperature of the electrolysis cells of approximately 700 °C to 900 °C.

[0130] If the base unit 5 is arranged above the stack 6, the two thermal planes are also arranged in reverse, the first thermal plane at the top in an upper area of ​​the base unit 5, which is directed away from the stack 6, and the second thermal plane below it, starting at the top of the stack 6.

[0131] Further thermal levels can be defined along the heat exchanger between the first and second thermal levels and have corresponding intermediate temperatures.

[0132] The design of the different thermal layers has the advantage that temperature-sensitive devices on the electrolysis unit can each be located in the cooler first thermal layer. Additional high-temperature protection measures are then unnecessary, saving (assembly) effort and costs.

[0133] Since, in this specific case, the fluid feedthroughs 7 are arranged in the cold area of ​​the first thermal level or below the first thermal level, they advantageously do not experience increased thermomechanical stress.

[0134] The penetrations 7 can be designed, in particular, as pipelines comprising pipe sections. The thermomechanical stress on the pipelines or the possible connecting pieces between the pipe sections is therefore lower than in the case where the penetrations 7 are subjected to high thermal stress.

[0135] In the event that the heat exchanger 8 alone is not sufficient to preheat the first fluid or steam sufficiently, a heater, for example an electric heater 9, can also be provided at the upper end of the base unit 5.

[0136] The entire electrolysis unit 4 comprising the stack 6 of solid oxide electrolysis cells and the base unit 5 is mechanically clamped and thus held together by a common mechanical clamping force which applies pressure to the electrolysis unit 4.

[0137] The joint clamping is achieved by a clamping device 10, wherein the clamping device 10 comprises a clamping unit 11, two rods 12 and a plate 13.

[0138] The clamping unit 11 adjusts the mechanical clamping force. The clamping unit 11 is attached to one end of the electrolysis unit 4. At the opposite end, the plate 13 is attached to the electrolysis unit, with the plate 13 and the clamping unit 11 being connected via the rods 12, which run laterally along the electrolysis unit 4 and are accordingly subjected to tensile stress.

[0139] In the present example, the clamping unit 11 is advantageously arranged at the cool end of the electrolysis unit 4, approximately at the level of the first thermal level.

[0140] Therefore, special requirements for the clamping unit 11 due to high thermomechanical stress are eliminated. The clamping unit 11 can be manufactured using standard fixtures and materials suitable for mechanical clamping at temperatures up to 250 °C.

[0141] The plate 13 is then attached to the hot upper end of the electrolysis unit 4, or of the stack 6, so that the base unit 5 and the entire stack 6 are pressed together by the clamping unit, by connecting the plate 13 and the clamping unit 11 through the tensile bars 12.

[0142] The clamping unit 11 can, for example, comprise screw connections or spring assemblies with suitable tension springs to generate the mechanical tension. The clamping unit 11 can also, for example, be designed as an integral component of the base unit 5.

[0143] As in Figure 2As shown, more than one single electrolysis unit 4 can be arranged on the installation surface 3 in a pressure vessel 2.

[0144] In Figure 2 The thermal insulation 14 is also shown, which separates the warm interior of the pressure vessel 2 from the cool vessel wall of the pressure vessel.

[0145] The insulating material can form a flat surface on the lower bottom of the pressure vessel, on which the mounting surface 3 is arranged. Mounting surface 3 is the surface of a mounting device, which, for example, comprises a metal structure with a flat sheet metal end facing upwards.

[0146] The pressure vessel 2 preferably has a cylindrical middle section and curved ends on both sides of the cylindrical middle section.

[0147] Pressure vessel 2 can be used, for example, as in Figure 1 shown standing upright, with the cylinder bases pointing downwards and upwards, or as shown in Figure 2The cylinder is shown lying down, with the cylindrical surface facing downwards and upwards.

[0148] In the Figures 3 to 5 Exemplary possibilities for the electrical contacting of the electrolysis unit 4 are shown.

[0149] In the Figures 3 to 5 For the sake of simplicity, only the base unit 5 and not the stack 6 of the electrolysis cells is shown.

[0150] In Figure 3 This represents a first possibility for electrical contacting and furthermore for mechanical tensioning.

[0151] The base unit 5 here includes a suspension unit 15 for mechanical connection and fastening with the clamping device 10.

[0152] The clamping device 10 comprises the clamping unit 11. In the example, spring assemblies 16 are provided as clamping unit 11 between the rods 12 and the suspension unit 15 to generate the required mechanical tension.

[0153] In the exemplary embodiment of the Figure 3 Furthermore, an electrical insulation 17a, for example made of non-conductive plastic, is provided between the base unit 5, in particular the suspension unit 15 and the clamping device 10, in particular the rods 12 and the spring assembly 16.

[0154] For the electrical contacting of the electrolysis unit 4, it is necessary that the stack 6 of electrolysis cells is contacted from two sides, i.e. from below and above, with different polarities.

[0155] The contact from below is made here via the base unit 5, which in the exemplary embodiment is at least partially electrically conductive.

[0156] The easiest way to connect the base unit 5 is from the outside, on the side of the suspension unit 15. In this example, the positive terminal is connected here.

[0157] The contacting of the upper end of the electrolysis unit 4 is carried out here via the clamping device 11, which is also electrically conductive, in particular via the lower ends of the rods 12, which are connected to the upper end of the stack 6 via the also electrically conductive plate 13 and are in electrical contact.

[0158] In the present example, the negative pole is applied to rods 12.

[0159] The electrical contact design shown here allows the electrical connection of the electrolysis unit 4 to be made entirely at its lower end in an area with comparatively cool temperatures, especially in the area of ​​the first thermal level.

[0160] Thus, the electrical periphery and electrical contacts are preferably only exposed to the temperatures of the first thermal level and do not need to be protected against higher temperatures.

[0161] This simplifies the setup of the device and saves costs. Furthermore, the electrical peripherals, such as power cables, can thus be easily arranged on the third mounting level.

[0162] An electrically insulating insulating plate 17b is also provided between the electrically contacted base unit 5 and the mounting surface 3.

[0163] Furthermore, the installation surface 3 can include a transport rail for easy installation and removal of the electrolysis unit 4.

[0164] The contacts can be made, for example, by welding or screwing at the corresponding points of the electrolysis unit 4.

[0165] The positive and negative terminals can also be reversed. This also applies to the other embodiments.

[0166] The examples of implementation in the Figures 4 and 5 are essentially the same as in Figure 3However, they also show slight differences.

[0167] In Figure 4 is different from Figure 3 The positive terminal is not located directly on the base unit 5, but rather on the lowest cell of the stack 6 of electrolysis cells. The temperature at the point of contact of the positive terminal is therefore warmer than in the embodiment shown in [reference to embodiment]. Figure 3 .

[0168] However, the electrical peripherals can still be advantageously arranged in the lower part of the pressure vessel, close to the base 3. An electrical line to the upper end of the stack 5 must be provided, as in the example above. Figure 3 , not be executed separately, since the rods 13 function as electrical conductors.

[0169] In the example in Figure 4 Additionally, electrical insulation in the form of an insulating plate 17c is provided between the base unit 5 and the stack 6.

[0170] In the example in Figure 5The positive terminal is again contacted directly via the electrically conductive base unit 5.

[0171] For this purpose, the base unit 5 in the illustrated embodiment is contacted directly from below. This can be achieved, for example, via an electrically conductive transport rail on the mounting surface 3. The transport rail is then preferably separated from the mounting surface 3 by an electrical insulating plate 17d.

[0172] In other embodiments, the positive and negative poles can also be reversed.

[0173] The exemplary embodiment in Figure 5 This has the additional advantage that the individual electrolysis units 4 do not need to be individually contacted on the base unit 5, but rather all electrolysis units 4 can be contacted by contacting a transport rail.

[0174] A similar rail can also be provided along the bars 12 to connect the negative pole to all electrolysis units 4 together.

[0175] In Figure 6 Another embodiment is shown. The design of the individual electrolysis units 4 can correspond to the previous embodiments.

[0176] In Figure 6 The figure further shows how the fluid feedthroughs 7 of adjacent electrolysis units 4 are connected to each other, thus forming a continuous pipeline 18.

[0177] For the sake of simplicity, only the base units 5 are shown again.

[0178] The feedthroughs 7 preferably each have connecting pieces 18a. Two adjacent connecting pieces 18a can be simply connected by a connecting piece 18b.

[0179] The connecting piece 18b can, for example, be a pipe flange part.

[0180] Since the entire fluid line is positioned in the cool area in the lower pressure vessel 2, the pipeline 18 and its components advantageously do not need to meet any special requirements regarding high temperature resistance.

[0181] In the Figure 7 and 8 Specific configurations of the basic unit 5 and the feedthroughs 7, in particular also of several basic units 5 arranged side by side, are shown.

[0182] As in Figure 7 The basic unit 5 shown, for example, comprises an electrically conductive metal wall 19 which can be electrically contacted from the outside in order to electrically connect the stack 6.

[0183] Inside the base unit 5, the two feedthroughs 7 for the fluids are provided at the bottom or at one end pointing away from the stack 6.

[0184] At the upper end of the base unit 5, facing the stack 6, connections 20 are provided for fluid transport to and from the stack 6.

[0185] Between the feedthroughs 7 for the fluids and the connections 20 for the fluids, a heat exchanger 8 in the form of a heat exchanger structure integrated in the base unit 5 is preferably formed in the base unit 5; for example as described below.

[0186] The heat exchanger structure is configured in such a way as to ensure the greatest possible heat exchange between the fluid to be cooled, i.e. the fluid containing the hydrogen produced in the electrolysis cells, and the supplied fluid to be heated, which contains at least water vapor as an electrolysis reactant.

[0187] In Figure 8 An example of how to connect several adjacent feedthroughs 7 to form a closed pipeline 18 is shown.

[0188] The feedthroughs preferably have 5 differently dimensioned connection pieces 18a on both sides of the base unit.

[0189] The connecting pieces 18a are advantageously dimensioned such that the outer diameter of a first connecting piece fits into the inner diameter of a second connecting piece. The first and second connecting pieces of the adjacent base units can then be directly inserted into one another, thus forming pipelines 18 for transporting the fluids.

[0190] A connecting piece 18a of a first basic unit 5 and a connecting piece 18a of a last basic unit 5 are then connected to suitable devices for supplying and removing the fluids.

[0191] Positioning the pipeline on the first thermal level prevents an unintentionally high thermomechanical stress, making the described plug-in concept feasible.

[0192] In the plug connection, the interlocking connection pieces 18a preferably have different dimensions.

[0193] The wider of the connectors has such a large inner diameter that the narrower of the connectors, with a correspondingly adapted outer diameter, can be pushed into the wider connector.

[0194] A sealing ring, e.g. a rubber O-ring, can be provided to tightly connect the two joined connectors 18a so that no fluid escapes in any possible gap between the outer surface of the inner and the inner surface of the outer connector.

[0195] The concept of concealment allows the base units 5 to be arranged in the smallest possible space. An arrangement in a row or even in a circle is possible.

[0196] Corresponding connectors or base units with the connectors can also be easily and individually manufactured via additive manufacturing processes.

[0197] Maintenance is advantageously inexpensive and simple due to the straightforward design.

[0198] Alternatively, other concepts for connecting the connecting pieces 18a of the penetrations 7 may be provided; for example, connecting pieces 18b such as pipe flange parts can connect the connecting pieces 18a, as in Figure 6 This is shown. This has the particular advantage of higher thermomechanical resistance.

[0199] Alternatively, screw connections can also be provided between the connection pieces 18a.

[0200] Furthermore, the complex heat exchanger structure can be individually designed and manufactured using additive manufacturing (3D printing). This allows for a simple and customized approach to achieving an optimal balance between low fluid pressure loss and high heat exchanger performance.

[0201] The design can be advantageously chosen in such a way that the base unit can withstand high gas pressure and high (external) mechanical stress or loads.

[0202] Advantageously, the entire structure of the basic unit 5 can be designed and manufactured or printed using additive manufacturing.

[0203] In Figure 9Finally, an alternative embodiment is shown in which the entire electrolysis unit 4 is arranged in reverse, so that the base unit 5 serves as a suspension and is arranged above the stack 6 of electrolysis cells. The entire structure of the electrolysis unit 4, as described above, is then preferably reversed.

[0204] This means that a cold area with the first thermal layer is formed in the upper half of the base unit 5, away from the stack 6. The feedthroughs 7 for the fluids, the electrical contacts, and the clamping unit 11 are located here.

[0205] The heat exchanger 8 is configured below the feedthroughs 7 between the feedthroughs 7 and the stack 6.

[0206] The stack 6 hangs below from the base unit 5, which acts as a suspension. The second thermal layer is formed at the upper end of the stack 6, which borders the base unit 5.

[0207] The base unit 5 and the stack 6 are in turn held together by the clamping device 10 with the rods 12, with the plate 13 closing off the stack 6 at the bottom.

[0208] Instead of or next to a mounting surface, in the alternative embodiment shown a suspension device 21 can be provided to which the base unit 5 is mechanically attached.

[0209] The remaining configurations of device 1 can be set up analogously to the previously shown versions. Reference character list

[0210] 1 Device 2 Pressure vessel 3 Installation area 4 Electrolysis unit 5 Base unit 6 Stack of electrolysis cells 7 Fluid feedthroughs 8 Heat exchanger 9 Optional heater 10 Clamping device 11 Clamping unit 12 Rods 13 Plate 14 Thermal insulation 15 Suspension unit 16 Spring assembly 17a Electrical insulation 17b, 17c, 17d Electrical insulation plates 18 Piping 18a Fittings 18b Connector 19 Metal wall 20 Connections 21 Suspension device First thermal level Second thermal level "+" Positive terminal, electrical contact with positive polarity "-" Negative terminal, electrical contact with negative polarity

Claims

1. System (1) for solid oxide electrolysis, comprising a plurality of electrolysis units (4) arranged side by side on a mounting surface (3), wherein the electrolysis units (4) each have a base unit (5) and a stack (6) of solid oxide electrolysis cells arranged perpendicular to the base unit (5), wherein the base unit (5) has a feedthrough (7) for at least two fluids, which are coupled to the corresponding feedthroughs (7) of the base units (5) of the adjacent electrolysis units (4) so ​​that a distribution of the fluids between the electrolysis units (4) is enabled, and wherein the base unit (5) has a feed for a first of the two fluids from the feedthrough (7) to the stack (6) and a discharge for a second of the two fluids from the stack (6) to the feedthrough (7), wherein the base unit (5) is designed as a heat exchanger (8) between the feedthrough and the discharge.wherein the heat exchanger (8) is configured such that, in an active operating state, a first temperature is established at a first height of the base unit (5) with respect to the installation surface (3), thereby forming a first thermal plane, and wherein the stack (6) is configured such that, in the active operating state, a second temperature is established at the lower end of the stack (6), thereby forming a second thermal plane.

2. System according to claim 1, wherein the supplied first fluid contains water vapor and the discharged second fluid contains hydrogen gas.

3. System according to one of claims 1 to 2, wherein the stack (6) has a lower end and an upper end and a plurality of cells arranged between the lower end and the upper end.

4. System according to claim 3, wherein the base unit (5) and the stack (6) are coupled at its lower end, such that the base unit (5) is formed as a base between the installation surface and the stack (6).

5. System according to claim 3, wherein the base unit (5) and the stack (6) are coupled at its upper end, such that the base unit (5) is designed as a suspension (21) for the stack (6).

6. System according to any one of claims 1 to 5, wherein the base unit (5) and the stack (6) are coupled in such a way that mechanical and thermal coupling takes place.

7. System according to one of claims 1 to 6, wherein the base unit (5) and the stack (6) are mechanically coupled by an externally applied pressure force.

8. System according to claim 7, wherein the base unit (5) and the stack (6) are clamped in a clamping device (10), wherein the clamping device (10) rests against the sides of the base unit (5) and the stack (6) that point outwards.

9. System according to claim 8, wherein the clamping device (10) is arranged on the base unit (5) in a cool area outside the area between the stack (6) and the first thermal layer, preferably in an area below the area between the stack (6) and the first thermal layer.

10. System according to any one of claims 1 to 9, wherein the base unit (5) has two halves in the vertical direction, wherein the first thermal plane is formed in the half of the base unit (5) that is further away from the stack.

11. System according to any one of claims 1 to 10, wherein the passages (7) for the fluids in the base unit (5) are formed in a cool area outside the area between the stack (6) and the first thermal level, preferably in an area below the area between the stack (6) and the first thermal level.

12. System according to claim 11, wherein the feedthroughs (7) for the fluids in the base unit (5) are formed between the first thermal level and the installation surface (3).

13. System according to any one of claims 1 to 12, wherein the base unit (5) has a heater (9) suitable for heating the fluid in the feed.

14. System according to any one of claims 1 to 13, wherein the base unit (5) and the stack (6) are coupled such that an electrical coupling takes place between the stack (6) and the base unit (5).

15. System according to one of claims 8 or 9 and according to claim 14, wherein electrical contact is made on the stack (6) via the clamping device (10), wherein the clamping device (10) is electrically in contact with an end of the stack (6) that points away from the base unit (5), preferably an upper end.

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