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 in series and placed side by side on a base (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 electrolysis units (4) adjacent in the series.

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 flow to / from the stacks is 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 arranged side by side in the system and preferably at the same height.

[0013] The electrolysis units form at least one series, i.e., several electrolysis units are preferably arranged in a line, or alternatively in a different type of chain.

[0014] In particular, the electrolysis units can be arranged on the same installation surface, which acts as a support for the electrolysis units.

[0015] 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 electrolyzer cells (SOECs) arranged perpendicularly to the base unit.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] It is also possible to have three feedthroughs for three fluids or more feedthroughs.

[0023] The main direction of the feedthroughs runs perpendicular to the stacking direction of the electrolysis cells.

[0024] The feedthroughs are each coupled to the corresponding feedthroughs of the base units of the adjacent electrolysis units in the series, so that the respective fluid can be distributed at least between the electrolysis units of a series.

[0025] In other words, the basic units of a series of electrolysis units preferably each have a feedthrough for a first fluid, which are connected in series to form a continuous pipeline.

[0026] 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 arranged in series as possible via the corresponding pipelines.

[0027] During operation, the fluids are added to or removed from the solid oxide electrolysis cells to enable the electrolysis units to function.

[0028] 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.

[0029] The basic unit is advantageously designed as a heat exchanger between the supply and the discharge.

[0030] During operation, the supplied first fluid is heated, while the discharged second fluid is cooled.

[0031] 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.

[0032] 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.

[0033] As an alternative, an additional heater, for example an electric one, can be provided in the base unit to further heat the supplied 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] 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.

[0039] The first thermal layer has a temperature that is significantly cooler than the temperature of the second thermal layer during operation.

[0040] 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.

[0041] The first temperature is between 150 °C and 500 °C, and in particular between 200 °C and 400 °C, for example 300 °C.

[0042] According to one interpretation, the first fluid supplied contains at least water vapor, and in particular more water vapor than hydrogen.

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

[0044] 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.

[0045] Additionally, the fluids may contain other gaseous or liquid components.

[0046] 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.

[0047] Furthermore, oxygen is produced as a product of electrolysis, which is preferably released directly into the environment of the electrolysis cells.

[0048] The system can include multiple rows of electrolysis units.

[0049] According to one interpretation, each series of electrolysis units comprises at least a first, a last and one or more middle electrolysis units.

[0050] According to one interpretation, a series of electrolysis units comprises a first and a last electrolysis unit.

[0051] A middle electrolysis unit is an electrolysis unit that is arranged between the first and the last electrolysis unit, so that the fluids are passed through the middle electrolysis unit on their way from the first to the last electrolysis unit in the series.

[0052] The feedthroughs of each middle electrolysis unit are connected to the feedthroughs of the electrolysis units arranged before and after it in the series.

[0053] The feedthroughs of the first electrolysis unit are each connected to the feedthroughs of the electrolysis unit arranged after it in the series, and the feedthroughs of the last electrolysis unit are each connected to the feedthroughs of the electrolysis unit arranged before it in the series, or vice versa.

[0054] The first and last electrolysis units are outer electrolysis units, which are characterized by the fact that they are not among the middle electrolysis units defined above.

[0055] The first and last electrolysis units are connected to other electrolysis units at least on one side via the feedthroughs, as previously defined.

[0056] In addition, external connections for the supply and discharge of fluids, such as hoses or pipes, can be provided on those passages of the outer electrolysis units that are not connected to middle electrolysis units, i.e., those that "point outwards".

[0057] According to one embodiment, however, the external connections for supplying and removing the fluids are only attached to a first electrolysis unit.

[0058] The last electrolysis unit in each row preferably has only one connection piece per feedthrough.

[0059] In this configuration, the first fluid containing the electrolysis reactants (reactant fluid) is conveyed along a first pipeline from a feed point into the first electrolysis unit. In the first electrolysis unit, a portion of the reactant fluid is fed into the electrolysis cells, while the remainder flows through the feedthroughs of the intermediate electrolysis units.

[0060] In the middle electrolysis units, a portion of the fluid is fed into the electrolysis cells, and a portion of the fluid flows on to the last electrolysis unit and is fed to the electrolysis cells there.

[0061] The proportion of fluid flowing into the electrolysis cells in each electrolysis unit can be adjusted by appropriate fittings, such as gas slides, taps or valves.

[0062] In the final electrolysis unit, a second fluid containing the electrolysis products (product fluid) from the electrolysis cells is discharged into a second feedthrough. This fluid is then conveyed back to the first electrolysis unit via a second pipeline, passing through the feedthroughs of the middle electrolysis units. Product fluid discharged from each electrolysis unit is added to this flowthrough.

[0063] Finally, the first electrolysis unit is equipped with a discharge device for removing the product fluid.

[0064] More than two pipelines, e.g., two separate pipelines for product fluids, may also be provided. Electrolysis units from different series may also have a different number of feedthroughs, which are then connected to form pipelines accordingly.

[0065] According to one embodiment, the system has several rows with multiple electrolysis units, with the passages for the fluids between the rows not being connected.

[0066] This allows the rows of electrolysis units to be operated separately, for example, depending on the required production capacity. Alternatively, the rows of electrolysis units can also be used to produce different products.

[0067] Alternatively, electrolysis units from multiple rows can be interconnected via suitable feedthroughs or external connections. Suitable feedthroughs can, for example, have a T-shape / Y-shape or an X-shape / cross-shape.

[0068] Preferably, the electrolysis units of different series are designed to be flexibly connected or disconnected from one another, so that sections consisting of several series of electrolysis units can be operated modularly. For this purpose, the previously described suitable feedthroughs can be provided, which are either designed to be decoupled or which can be opened and closed by control devices.

[0069] 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.

[0070] 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.

[0071] The base unit then also serves as a mechanical support, over which the stack stands on the installation surface and is optionally also secured.

[0072] 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.

[0073] The stack can then be mechanically attached to the suspension and thus be firmly arranged in the existing system.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] The installation surface preferably forms a uniform plane within the pressure vessel, on which the individual electrolysis units are placed.

[0078] The pressure vessel preferably has a cylindrical central section and curved ends or walls on both sides of the cylindrical central section. Such a shape can withstand high pressure loads.

[0079] The pressure vessel can be oriented, for example, in a standing position, with the cylinder axis arranged parallel to the stacking direction, or in a lying position, with the cylinder axis arranged orthogonally to the stacking direction.

[0080] A horizontal orientation is particularly preferred, especially if it results in a larger footprint for a greater number of rows of electrolysis units. The total number of electrolysis units can also be advantageously increased in this way.

[0081] The installation surface is then preferably rectangular, extending along a cylindrical cross-sectional surface.

[0082] The rows are arranged on the rectangular installation surface in such a way that at least the outer electrolysis units are located close to an outer edge of the rectangular installation surface and are therefore easily accessible, for example for maintenance purposes.

[0083] Advantageously, rails, in particular transport rails, can be provided on the installation surface, on which the electrolysis units can be driven into the system and can be attached to or on the installation surface.

[0084] A separate transport rail can be provided for each row, so that the electrolysis units of different rows can be transported, removed or added separately from the system or the interior of the pressure vessel.

[0085] 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.

[0086] 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.

[0087] Connections for fluid transport between the rows can also be designed so that they can be opened and closed by means of gas valves in order to connect or decouple the rows.

[0088] The gas valve can be designed, for example, as a slide valve, a ball valve, or a shut-off valve.

[0089] 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.

[0090] By closing a feed, for example by means of a gas valve, the fluid supply to an electrolysis unit can be selectively stopped and this electrolysis unit can thus be taken out of service.

[0091] This can be advantageous, for example, if the system is only to be operated with a portion of the electrolysis units available in a series, for example due to capacity constraints or defects.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] According to one embodiment, the base unit and the stack are mechanically coupled by an externally applied pressure force.

[0098] Where "externally applied" means that the pressure is built up by a device separate from the base unit and the stack.

[0099] According to one embodiment, the feedthroughs of the base units of the adjacent electrolysis units are directly mechanically coupled to one another.

[0100] This means that the feedthroughs of the base units touch each other and, by linking the feedthroughs of adjacent base units together, form a closed pipeline between the base units.

[0101] For this purpose, the feedthroughs preferably have connection pieces, for example in the form of pipe connection pieces, on one or on two, preferably oppositely oriented outer sides of the base unit.

[0102] According to a preferred embodiment, the base unit has first connecting pieces and second connecting pieces, wherein the first connecting piece and the second connecting piece or the first connecting pieces and the second connecting pieces each project in different directions away from the base unit.

[0103] In particular, a base unit can be provided with two first connection pieces for the supply of two fluids and two second connection pieces for the discharge of two fluids.

[0104] To transport two fluids through the base units, in particular a first fluid containing the reactants for electrolysis and a second fluid containing the products for electrolysis, two feedthroughs are preferably provided, each of which has at least one first connection piece and one second connection piece.

[0105] If branches to other series are provided, a penetration can also have several first or second or other types of third connections that form a closed piping system.

[0106] Preferably, the connectors are dimensioned so that a first connector can be inserted or plugged into a second connector, or vice versa, so that the respective connectors can be concealed from each other.

[0107] For this purpose, the outer diameter of the first connector is preferably dimensioned such that the first outer diameter fits into the inner diameter of the second connector, i.e., is smaller than the inner diameter of the second connector or vice versa.

[0108] The fit between the connecting pieces can be, in particular, a clearance fit, a transition fit, or an interference fit or press fit.

[0109] Preferably, it is a game pass or a transition pass.

[0110] Preferably, the connecting pieces are pushed or plugged together in such a way that they are movable relative to each other and can thus compensate for thermomechanical stresses and deformations as well as movements of the pipe connecting pieces relative to each other.

[0111] The connection between the two nested pipes can be additionally sealed using an ordinary sealing ring / O-ring.

[0112] The sealing ring / O-ring is preferably made of a sliding material or has a sliding surface. The sealing ring can, for example, contain or consist of a plastic material. This ensures that the movement of the nested pipes relative to each other is not restricted by the seal, and the thermomechanical compensation function of the push-fit connection is maintained. Such a seal can therefore also be described as a piston seal or a movable seal.

[0113] The simple setup of the pipeline by inserting the connecting pieces and the simple sealing using ordinary O-rings is particularly possible if the pipelines are not located in an area where the high temperatures are close to the operating temperature of the electrolysis.

[0114] Rather, the pipeline is preferably located in an area of ​​the first thermal layer with significantly cooler temperatures.

[0115] To withstand higher temperatures in particular, alternative or additional connection concepts between the fittings used to assemble the pipeline may be provided. For example, options for screw connections between the individual fittings may be included. The fittings may also feature flanges for connection.

[0116] Furthermore, designs are also possible in which the feedthroughs of the basic units of the adjacent electrolysis units are mechanically coupled to each other via intermediate pieces, in particular a compensator.

[0117] Compensators are pipe components that are, for example, elastically expandable and compressible, and thus can react to (thermo-)mechanical deformations and movements of the base units relative to each other and compensate for these movements and deformations.

[0118] The compensators can be screwed, welded or otherwise connected to the bushing connectors.

[0119] Another option, especially if it is ensured that the pipe sections in the cool area of ​​the first thermal level are hardly subjected to thermal stress and move little against each other, are fixed and rigid connections between the connecting pieces, for example by direct screwing, welding or interposed rigid pipe flange pieces.

[0120] In the case of screw connections, the connecting pieces can also have external or internal threads themselves in order to be screwed directly together.

[0121] In particular, the connecting pieces may be additively manufactured printed parts that can have suitable individually designed shapes.

[0122] The seal between the connecting pieces is preferably designed as described above, so that the seal remains tight at least at temperatures up to 500 °C, preferably up to 900 °C, in order to prevent leakage of fluids.

[0123] In some embodiments, the base unit and the stack are clamped in a (common) 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 both above and below.

[0124] 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.

[0125] The plate can be permanently attached to the electrolysis unit.

[0126] 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.

[0127] In other words, the rods are subjected to tension and the electrolysis unit to compression.

[0128] 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.

[0129] 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.

[0130] The clamping unit is connected to the electrolysis unit, so that the electrolysis unit is subjected to pressure between the plate and the clamping unit.

[0131] 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.

[0132] According to one embodiment, the base unit has two halves in the vertical direction, with the first thermal layer being formed in the half of the base unit furthest from the stack. The first thermal layer can, in particular, be defined at a position adjacent to the fluid passages 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.

[0133] The feedthroughs are preferably 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, in order to realize the previously described piping.

[0134] The feedthroughs are therefore no longer part of the heat exchanger, but are located in the area of ​​the previously defined cool temperature regime.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] For electrical contact of the electrolysis unit, it is necessary that the stack of electrolysis cells is contacted from two sides, i.e. from below and above, with different polarities (+ / -).

[0139] The contact from below is advantageously made directly via the base unit, which is at least partially electrically conductive for this purpose, for example by means of an electrically conductive metal wall.

[0140] 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.

[0141] This is particularly advantageous because, in this case, no further stresses due to a significantly increased temperature, especially the operating temperature of the electrolysis cells, need to be taken into account when making electrical contacts.

[0142] 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, for example, advantageously prevents unwanted overheating of electrical components.

[0143] 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.

[0144] 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.

[0145] The clamping device, which is preferably electrically conductive, then electrically contacts the end of the stack that points away from the base unit, i.e., preferably the upper end, since the clamping device is in direct mechanical and electrical contact with the corresponding end of the stack. The clamping device is electrically insulated from the base unit, with which it is also in mechanical contact.

[0146] Preferably, all contact points of electrolysis units arranged in a row are electrically contacted simply by means of a common busbar or cable that runs along the entire row.

[0147] This allows electrical contacts to be easily established with all electrolysis units using a single constructive element.

[0148] 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.

[0149] A first contact point is then provided on the clamping device as described above.

[0150] A second contact point is provided, for example, at a lower end or on the side of the base unit.

[0151] In particular, an electrically conductive metal plate or busbar can be provided for this purpose, which rests against the bottom of the base unit. Preferably, the busbar or plate rests simultaneously against all electrolysis units arranged in a series, so that they are connected in parallel.

[0152] Alternatively, the second contact points can be located on the side of the base unit on mechanical supports. Here, the base units can, for example, be connected together via a busbar running along the row.

[0153] Alternatively, the electrically conductive base units can also be directly coupled to each other, i.e., in electrical contact with each other.

[0154] For example, the respective base units have electrically conductive metallic outer walls which are advantageously positioned so that they touch each other; or the base units each have correspondingly protruding contact devices, wherein the contact devices of two adjacent base units touch each other.

[0155] In other versions, the base unit and the stack are electrically isolated from each other.

[0156] The stack of electrolysis cells is then electrically contacted separately by providing two contact points, the positive and negative poles, at the top and bottom of the stack.

[0157] The contacting at the top of the stack can be carried out via the bars of the clamping device as described previously, so that the electrical periphery can still be advantageously positioned in the first thermal plane, as described previously.

[0158] The lower end of the stacks can then be directly contacted, for example, by busbars or cables running along the row.

[0159] An electrical insulation is preferably provided between the base unit and the stack.

[0160] The contacts between the electrical periphery and the electrolysis units can be established, for example, by screws or welding.

[0161] 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.

[0162] The figures show: Figure 1 Figure 1 shows a schematic representation of an embodiment of the device, comprising an exemplary electrolysis unit with clamping device, a stack of solid oxide electrolysis cells and a base unit. Figure 2 Figure 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 an embodiment for connecting the fluid feedthroughs of adjacent electrolysis units using separate connecting pieces. Figure 4Figure 1 schematically shows an embodiment for connecting the fluid feedthroughs of adjacent electrolysis units by means of a direct plug connection. Figure 5 : shows an exemplary embodiment of a specific implementation of the basic unit. Figure 6 Figure 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 5 electrolysis unit shown. Figure 7 : shows in plan view an exemplary arrangement of several rows of electrolysis units in a pressure vessel. Figure 8 : shows, from a perspective viewpoint, an exemplary arrangement of several rows of electrolysis units in a pressure vessel.

[0163] In Figure 1 The system is represented by example as device 1.

[0164] The exemplary device 1 can include a pressure vessel which is in Figure 1 However, this is not shown for the sake of simplicity.

[0165] Furthermore, a mounting surface 3 is provided, possibly inside the pressure vessel. The mounting surface 3 can, in particular, be the surface of a mounting device.

[0166] In this example, the installation surface 3 is arranged horizontally.

[0167] The installation area 3 is a flat surface that offers a possibility for setting up and securing the electrolysis units.

[0168] 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.

[0169] The electrolysis units 4 can, for example, be arranged in one or more rows, in particular along uniform straight lines.

[0170] In the area of ​​the installation surface 3, 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 advantageously provided.

[0171] 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.

[0172] Alternatively, other gases can also be added and removed, especially carbon-oxygen compounds such as carbon dioxide, carbon monoxide, etc.

[0173] Stack 6 is in particular a stack of several solid oxide electrolyzer cells (SOECs).

[0174] The stacking direction of stack 6 runs from bottom to top, i.e. perpendicular to the support surface 3.

[0175] 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 being attached to the mounting surface 3, in particular the transport rail, via the base unit 5.

[0176] In other examples, 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] The water vapor from the first fluid is at least partially broken down into oxygen and hydrogen in the electrolysis cells, and the hydrogen produced 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] Further thermal levels can be defined along the heat exchanger between the first and second thermal levels and have corresponding intermediate temperatures.

[0187] The design of the different thermal layers has the advantage that temperature-sensitive devices on the electrolysis unit can be positioned in the cooler first thermal layer. Additional high-temperature protection measures are then unnecessary, saving (assembly) effort and costs.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] As in Figure 2As shown, more than one single electrolysis unit 4 is preferably arranged on the installation surface 3 in a pressure vessel 2.

[0199] 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.

[0200] This prevents unwanted heating of the container wall, which can impair its mechanical strength.

[0201] 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.

[0202] The pressure vessel 2 preferably has a cylindrical middle section and curved ends on both sides of the cylindrical middle section.

[0203] Pressure vessel 2 is preferred, as shown in Figure 2 shown, arranged lying down, with the cylindrical surface facing downwards and upwards.

[0204] In Figure 3 Another embodiment is shown.

[0205] The design of the individual electrolysis units 4 can correspond to the previous embodiments.

[0206] In Figure 3 Figure 7 shows how the fluid feedthroughs of adjacent electrolysis units 4 are connected to each other, thus forming a continuous pipeline 15.

[0207] For the sake of simplicity, only the base units 5 are shown again.

[0208] The feedthroughs 7 preferably each have connecting pieces 15a. Two adjacent connecting pieces 15a can be simply connected by a connecting piece 15b.

[0209] The connecting piece 15b can, for example, be a pipe flange part.

[0210] Preferably, the connecting piece 15b is a compensator component. A (pipe) compensator, or the specific compensator component used, has the advantage of being elastic with respect to elongation and compression.

[0211] In particular, it is a compressible, hose-like connector.

[0212] The compensator preferably has flanges at both ends which can be connected to matching flange ends of the connecting pieces 15a, for example by screw connections or welding.

[0213] Additional seals may be provided at the usual discretion to prevent leaks at the joints.

[0214] Since the entire fluid line is positioned in the cool area in the lower pressure vessel 2, the pipeline 15 and its components advantageously do not need to meet any special requirements regarding high temperature resistance.

[0215] This is also the case in Figure 4The advantageous construction shown is possible in which a first narrow connecting piece 15a2 with a small outer diameter is inserted into a second wide connecting piece 15a1 with a comparatively larger inner diameter.

[0216] Preferably, the diameters of the connecting pieces 15 are dimensioned such that the connecting pieces fit together as precisely as possible or that sufficient clearance is provided to create a leak-proof seal. Such a seal can, for example, consist of a sealing ring such as an O-ring.

[0217] In the Figures 5 to 7 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.

[0218] As in Figure 5 The basic unit 5 shown, for example, comprises an electrically conductive metal wall 16 which can be electrically contacted from the outside in order to electrically connect the stack 6.

[0219] 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.

[0220] At the upper end of the base unit 5, facing the stack 6, connections 17 are provided for fluid transport to and from the stack 6.

[0221] Between the feedthroughs 7 for the fluids and the connections 17 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.

[0222] 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.

[0223] Warm and cold fluid flows are guided in such a way as to achieve the largest possible exchange surface for heat transfer between the fluids.

[0224] The complex heat exchanger structure can be advantageously designed and manufactured individually 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.

[0225] 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.

[0226] Advantageously, the entire structure of the basic unit 5 can be designed and manufactured or printed using additive manufacturing.

[0227] In Figure 6An example of how to connect several adjacent feedthroughs 7 to form a closed pipeline 15 is shown, as schematically illustrated by the Figure 4 explained.

[0228] The feedthroughs preferably have 5 differently dimensioned connection pieces 15a (15a1,15a2) on both sides of the base unit.

[0229] The connecting pieces 15a are advantageously dimensioned such that the outer diameter of a first connecting piece 15a1 fits into the inner diameter of a second connecting piece 15a2. This allows the first and second connecting pieces of the adjacent base units to be directly inserted into one another, thus forming pipelines 15 for transporting the fluids.

[0230] A connecting piece 15a of a first basic unit 5 and a connecting piece 15a of a last basic unit 5 are then, for example, connected to suitable devices for supplying and removing the fluids.

[0231] The last connecting piece 15a of the last base unit 5 can also be closed or otherwise sealed, so that all the remaining fluid from the pipeline 15 is conveyed into the electrolysis cells of the stack 6.

[0232] The last base unit 5 can alternatively only have one connector 15a.

[0233] Positioning the pipeline on the first thermal level prevents an unintentionally high thermomechanical stress, making the described plug-in concept feasible.

[0234] In the Figures 7 and 8 It is shown again in detail how a plurality of electrolysis units 4 are arranged in the pressure vessel 2, which is preferably a horizontal cylinder.

[0235] In the Figures 7 and 8 In the examples shown, a total of 17 electrolysis units 4 are arranged in four rows of five electrolysis units 4 on a rectangular base 3.

[0236] The distances in both dimensions of the installation area 3 between the adjacent electrolysis units 4 are identical. This allows all electrolysis units 4 to be connected to each other, if desired, by means of identically dimensioned connecting pieces 15a, in order to form continuous fluid lines 15 at least along the rows of electrolysis units 4.

[0237] The fluid lines are each open on one side towards a base surface of the cylinder, here on the right in the figure, in order to connect them to the outside.

[0238] Preferably, a row 30, 31, 32, 33 of electrolysis units 4 is arranged on a common transport rail.

[0239] The rows are preferably aligned along the cylinder height, i.e., perpendicular to the cylinder's base. This makes it possible to insert or remove rows of electrolysis units 4 from the pressure vessel 2 from a side corresponding to the cylinder's base.

[0240] The individual rows can preferably be operated largely independently of each other.

[0241] Alternatively, it is also possible to provide cross connections 34 between individual rows in the pipelines that connect the electrolysis units of different rows. These cross connections 34 can optionally be opened and closed by means of gas valves. Reference character list

[0242] 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 Piping 15a Fittings 15a1 First fitting 15a1 Second fitting 15b Flange connector 16 Metal wall 17 Connections 30 First row of electrolysis units 31 Second row of electrolysis units 32 Third row of electrolysis units 33 Fourth row of electrolysis units 34 Cross-connections First thermal level Second thermal level

Claims

1. System (1) for solid oxide electrolysis, comprising a pressure vessel (2) which has inside at least one mounting surface (3) and a plurality of electrolysis units (4) which are mounted in at least one row (30) perpendicularly on the mounting surface (3), wherein the electrolysis units (4) each have a base unit (5) and a stack (6) of solid oxide electrolysis cells arranged perpendicularly on 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 electrolysis units (4) adjacent in the row (30), so that the fluid can be distributed between the electrolysis units (4), and wherein the base unit (5) has a feedthrough 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).

2. System (1) according to claim 1, wherein the base unit (5) is designed as a heat exchanger (8) between the supply and the discharge.

3. System (1) according to one of claims 1 to 2, wherein each row (30, 31, 32, 33) has at least one first, one last and one or more intermediate electrolysis units (4), wherein the one or more intermediate electrolysis units (4) are arranged between the first and the last electrolysis unit (4) so ​​that the fluids are directed from the first to the last electrolysis unit (4), wherein the feedthroughs (7) of each intermediate electrolysis unit (4) are connected to the feedthroughs of the electrolysis units (4) arranged before and after it in the row.

4. System (1) according to one of claims 1 to 3, wherein the system has several rows (30, 31, 32, 33) with several electrolysis units (4), wherein the passages (7) for the fluids between the rows (30, 31, 32, 33) are not connected.

5. System (1) according to any one of claims 1 to 4, 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, 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 mounting surface (3) and the stack (6).

6. System (1) according to any one of claims 1 to 4, 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, wherein the base unit (5) and the stack (6) are coupled at its upper end, such that the base unit (5) is configured as a suspension for the stack (6).

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

8. System (1) according to any one of claims 1 to 7, wherein the feedthroughs (7) of the base units (5) of the adjacent electrolysis units (4) are directly mechanically coupled to one another.

9. System (1) according to one of claims 1 to 8, wherein the feedthroughs (7) of the base units (5) of the adjacent electrolysis units (4) are mechanically coupled to one another via intermediate pieces (15b), in particular a compensator.

10. System (1) according to any one of claims 1 to 9, wherein the feedthroughs (7) of the base units (5) of the adjacent electrolysis units (4) are firmly coupled to one another by welding or screwing.

11. System (1) according to one of claims 1 to 9, wherein the feedthroughs (7) of the base units (5) of the adjacent electrolysis units (4) are movably coupled to one another by means of interlocking and / or piston seals.

12. System (1) according to one of claims 1 to 11, wherein the heat exchanger (8) in the base unit (5) 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 (A), 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, thereby forming a second thermal plane (B).

13. System (1) according to claim 12, wherein the feedthroughs (7) for the fluids in the base unit (5) are formed outside the area between the stack (6) and the first thermal level (A).

14. System (1) 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 any one of claims 1 to 14, wherein the respective base units (5) are electrically coupled to each other.

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