Solid oxide electrolyzer having stacked modules and method for changing stacked modules

Abstract

The invention relates to a stack module having at least one solid oxide electrolysis stack comprising a plurality of stacked solid oxide electrolysis cells, in which the stack module comprises two gas inlet connections and two gas outlet connections. According to the invention, at least one solid oxide electrolysis stack is encapsulated in a metal container, with two gas inlet connections and two gas outlet connections connected to the metal container. The invention further relates to a solid oxide electrolyzer having at least one stacked module and to a method for replacing a stacked module of a solid oxide electrolyzer.

Description

[0001] The present invention relates to a stack module, a solid oxide electrolyzer having the stack module, and a method for replacing the stack module of the solid oxide electrolyzer.

[0002] The stack module includes at least one solid oxide electrolysis stack, the solid oxide electrolysis stack including a plurality of stacked solid oxide electrolysis cells, wherein the stack module includes two gas inlet connectors and two gas outlet connectors.

[0003] The currently known solid oxide electrolyzers with stack modules have hitherto been designed for small production capacities and are mostly used for laboratory-scale or small-scale technology demonstration units. These solid oxide electrolyzers are operated by solid oxide electrolysis experts in a controlled environment because the solid oxide electrolysis cells are highly sensitive.

[0004] In order to upgrade the solid oxide electrolyzer to large-scale industrial production, further improvements are needed to improve the repairability and maintainability in the field of solid oxide electrolyzers and their stack modules, the stack modules having a shorter service life than other components of the solid oxide electrolyzer.

[0005] Therefore, the object of the present invention is to provide an improved solid oxide electrolyzer and stack module.

[0006] The solution to this object according to the present invention lies in that at least one solid oxide electrolysis stack is encapsulated in a metal container, wherein the two gas inlet connectors and the two gas outlet connectors are connected to the metal container.

[0007] By encapsulating the solid oxide electrolysis stack in a metal container, the fragile solid oxide electrolysis stack is protected from shock and contamination. In addition, the complex installation work of installing the sensitive and easily breakable solid oxide electrolysis cells into the solid oxide electrolysis stack and then into the stack module can be carried out in a quality-controlled environment in a specialized manufacturing factory at the solid oxide electrolysis plant supplier. The stack module is then a robust component that can be easily handled by mechanical plant workers locally available at the consumer solid oxide electrolysis plant. Thus, the stack module according to the present invention greatly improves the repairability and maintainability of the solid oxide electrolyzer having at least one stack module.

[0008] According to a particularly preferred embodiment, the two gas inlet connectors and the two gas outlet connectors each include a thermal quick coupler for connecting them to an external gas inlet or outlet. Thus, the thermal quick coupler relates to bolt connectors, compression fitting style connections, pipe joints, threaded connectors, wedge connectors, press fit connectors or similar known high-temperature quick coupler solutions for pipes. By using the thermal quick coupler, the stack module can be quickly and efficiently replaced from the respective solid oxide electrolyzer. For this purpose, no solid oxide electrolysis experts are required on the factory site. Preferably, the thermal quick coupler is configured as a pipe joint. In this way, a very safe connection can be achieved within a short time range.

[0009] According to a preferred embodiment, the solid oxide electrolysis stack is configured to produce hydrogen, carbon monoxide or syngas. Preferably, during the production of hydrogen, carbon monoxide or syngas, the temperature range in the solid oxide electrolysis stack is maintained between 500 °C and 850 °C.

[0010] According to a preferred embodiment, the stack module includes two solid oxide electrolysis stacks that are manifolded through a common manifold, which is part of a metal container and connects the two gas inlet connectors and the two gas outlet connectors thereto. By including two solid oxide electrolysis stacks in one stack module, the total production capacity of one stack module can be increased. In addition, the stack module is still not too large to be difficult to handle. By using a common manifold, the number of necessary components can be reduced. This also applies to the common manifold that is part of the metal container.

[0011] According to another preferred embodiment, the two solid oxide electrolysis stacks are placed in respective encapsulation covers, which together with the common manifold and two lids form a metal container, and the two lids are respectively placed in one of the encapsulation covers to encapsulate the solid oxide electrolysis stacks in the encapsulation covers. This structure of the metal container is simple and efficient to manufacture. In addition, solid oxide electrolysis stacks of different heights can be encapsulated in the same encapsulation cover by adjusting the position of the lid in the respective encapsulation shield. Preferably, the encapsulation cover is cylindrical and open at both ends, and one of the ends can be fixed to the common manifold.

[0012] In a further preferred embodiment, the gasket is placed between two solid oxide electrolysis stacks and the common manifold, and the ceramic fiber pads are placed between the two solid oxide electrolysis stacks and their respective covers in the encapsulation shroud, where the covers are preferably fixed in position in the encapsulation shroud by welding, and the ceramic fiber pads are configured to apply a compressive force to the respective solid oxide electrolysis stacks and thereby to the respective gaskets and the common manifold. In this way, the solid oxide electrolysis stacks bear against the gaskets and thus against the common manifold. Accordingly, the position of the covers in the encapsulation shroud and the nature of the ceramic fiber pads can be set such that the gasket seal between the common manifold and the solid oxide electrolysis stacks remains functional even during different temperature ranges. Preferably, the precise position of the covers is established by applying a certain pressure to the covers and thereby a certain pressure to the ceramic fiber pads, the solid oxide electrolysis stacks, the gaskets and the common manifold, which results in proper compression of the ceramic fiber pads, the solid oxide electrolysis stacks and the gaskets. The covers can then be fixed in position by welding.

[0013] In a particularly preferred embodiment, the two solid oxide electrolysis stacks are arranged on opposite sides of the common manifold, where the two solid oxide electrolysis stacks are preferably symmetrically configured with respect to a plane of symmetry passing through the common manifold, the plane of symmetry being perpendicular to the axis of the encapsulation shroud, where the common manifold is preferably also constructed symmetrically with respect to the plane of symmetry. This arrangement allows for a compact design of the stack module. In addition, the distance that the educt or product gas has to travel in the manifold can be kept short. Another advantage is that when the covers are pressed onto the respective ceramic fiber pads, solid oxide electrolysis stacks, gaskets and common manifold from opposite directions, the common manifold does not experience any deflection because the forces on the common manifold cancel each other out. Accordingly, the common manifold can be designed to be thinner without the risk of manifold deflection and sealing problems between the solid oxide electrolysis stacks and the common manifold.

[0014] According to another preferred embodiment, each stacked solid oxide electrolysis cell comprises two sides, an anode side and a cathode side, wherein the two sides can be supplied with different gas flows, and wherein the stacked solid oxide electrolysis cells are separated by gastight separator plates, wherein the common manifold comprises respective first gas inlets for two solid oxide electrolysis stacks, said first gas inlets being supplied by the first of two gas inlet connectors and guiding a first gas flow into respective voids between the encapsulation shroud and the solid oxide electrolysis stacks, wherein the first gas flow then enters the volume between one of the two sides of the respective solid oxide electrolysis cell and the corresponding adjacent separator plate and then travels through this volume towards a centrally located hole in the respective solid oxide electrolysis stack, from where the first gas flow leaves the common manifold through respective first gas outlets, said first gas outlets being connected to the first of two gas outlet connectors, wherein the common manifold further comprises second gas inlets for two solid oxide electrolysis stacks, said second gas inlets being supplied with a second gas flow through the second of two gas inlet connectors, guiding said second gas flow into respective holes in the respective solid oxide electrolysis stacks, said holes extending upwards through the full stack height, from where said second gas flow enters the other volume between the other of the two sides of the solid oxide electrolysis cell and the corresponding adjacent separator plate and then is transferred through this other volume to another hole at the full stack height, from where said second gas flow leaves the common manifold through second gas outlets, said second gas outlets being connected to the second of two gas outlet connectors. This is an efficient way of supplying reactant gases to and removing product gases from the solid oxide electrolysis cells.

[0015] The invention further relates to a solid oxide electrolyzer comprising a pressure housing and a hot zone insulator within the pressure housing, wherein the hot zone insulator surrounds a hot zone, preferably according to one of the embodiments of the stacked module described above, at least one stacked module of stacked solid oxide electrolysis cells being placed in said hot zone, wherein the pressure housing comprises a lower pressure housing part and an upper pressure housing part connected by a pressure housing flange connector, and wherein the hot zone insulator comprises an insulating bell and a static insulating part, wherein external connectors including electrical connectors, reactant gas pipes and product gas pipes are passed through the lower pressure housing part but not through the upper pressure housing part such that the upper pressure housing part can be lifted away from the lower pressure housing part without further disconnection work when the pressure housing flange connector is opened, and wherein the electrical connectors and product gas pipes are passed through the static insulating part but not through the insulating bell such that the insulating bell can be lifted without disconnection work regarding the electrical connectors and product gas pipes when the upper pressure housing part is removed.

[0016] In this way, since disassembly can be carried out very efficiently, the repairability and maintainability of the solid oxide electrolyzer are greatly improved. In addition, by not using an insulator for a separate component, the accessibility to the component can be improved, and the insulator does not have to be replaced together with the component, but can continue to be used. This is particularly advantageous because the hot zone insulator has a significantly longer service life than the stack module.

[0017] The electrical connectors relate to the power connectors for the stack module and the power connectors for the heater. Preferably, the external connectors also include connectors for additional instruments and data collection. Preferably, these connectors for additional instruments and data collection are passed through the lower pressure housing part and the static insulation part, so that the upper pressure housing part and the insulation bell can be lifted away without disconnecting these connectors for additional instruments and data collection.

[0018] In a preferred embodiment, the external connectors are passed through the static insulation part without passing through the insulation bell, so that the insulation bell can be lifted away without disconnecting when the upper pressure housing assembly is removed.

[0019] In a preferred embodiment, the solid oxide electrolyzer includes a plurality of stack modules, wherein the solid oxide electrolyzer has a capacity of at least 0.3 MW, preferably at least 0.5 MW. By using a solid oxide electrolyzer of this size, the output of the solid oxide electrolyzer is suitable for the production of industrial hydrogen, carbon monoxide or syngas.

[0020] Preferably, the solid oxide electrolyzer includes six stack modules, which are arranged around a common axis of the upper pressure housing part and the insulation bell.

[0021] In a preferred embodiment, the insulation bell opens downward. In this way, the insulation bell encloses a certain volume, which is exposed and easily accessible when the insulation bell is lifted away. The insulation bell can be formed by several parts, which can be lifted away successively. However, preferably, the insulation bell is made of a single piece. Therefore, the lifting of the insulation bell takes less time and is more efficient.

[0022] In another preferred embodiment, the heat exchanger between the reactant gas and the product gas and the heater for the reactant gas are arranged in the hot zone.

[0023] In another preferred embodiment, the insulation bell itself is airtight and structurally stable, wherein the insulation bell preferably consists of an airtight inner lining, a layer of insulating material and an outer structural layer, or consists of a structurally stable insulating material, preferably made of a ceramic lightweight castable material, that is, the insulation bell is completely made of this ceramic lightweight castable material. These are advantageous designs that allow for a durable insulation bell.

[0024] According to yet another preferred embodiment, the position of the static insulation member is fixed relative to the position of the lower pressure housing part, where the hot zone insulation gasket is arranged on the static insulation member and the insulation bell is placed thereon and thereby hermetically insulates the hot zone. In this way, the insulation bell seals the hot zone insulator by its own weight resting on the hot zone insulation gasket.

[0025] In a further preferred embodiment, the pressure housing flange is located at the highest diameter of the solid oxide electrolyzer and preferably at or below the position of the hot zone insulation gasket. Thereby, the interior of the hot zone can be fully exposed for repair and maintenance work.

[0026] In a preferred embodiment, the solid oxide electrolyzer includes a recuperative heat exchange space arranged at least partially around the outside of the hot zone insulator, where a first part of the reactant gas pipeline passing through the lower pressure housing part introduces a first reactant gas into the recuperative heat exchange space, and where the first reactant gas leaves the recuperative heat exchange space via a riser pipe and enters a second part of the reactant gas pipeline, which is guided through the static insulation member to the stack module in the hot zone. This makes the solid oxide electrolyzer more energy-efficient, and further, the pressure housing does not have to experience excessive temperatures.

[0027] In a preferred embodiment, the riser pipe extends through the recuperative heat exchange space along and away from the outside of the hot zone insulator from the connection to the second part of the reactant gas pipeline to a point at or above the top height of the hot zone insulator. In this way, when the upper pressure housing part is removed, the insulation bell can be lifted off without further disconnection work.

[0028] In another preferred embodiment, the riser pipe is guided from the connection to the second part of the reactant gas pipeline into the insulation bell and passes through the insulation bell to the top height of the hot zone insulator, where the riser pipe leaves the insulation bell and enters the recuperative heat exchange space. In this way, the position where the riser pipe leaves the insulation bell can be placed on the axis of the insulation bell, which results in favorable gas flow characteristics in the recuperative heat exchange space and thus causes improved cooling. When removing the upper pressure housing part, only the connection between the riser pipe and the second part of the reactant gas pipeline needs to be opened to be able to lift the insulation bell. Preferably, the connection between the riser pipe and the second part of the reactant gas pipeline is configured as a flange connection. In this way, this connection can be opened quickly and efficiently.

[0029] According to another preferred embodiment, at least one stack module includes two gas inlet connectors and two gas outlet connectors, each of the gas inlet connectors and the two gas outlet connectors including a thermal quick coupler, wherein the thermal quick coupler is connected to a gas connector in a hot zone to direct process gas to and from the at least one stack module. The use of thermal quick couplers further improves serviceability and maintainability as it further facilitates the replacement of the stack module.

[0030] The invention also relates to a method for replacing a stack module of a solid oxide electrolyzer according to one of the above embodiments, wherein the method comprises the steps of disconnecting the upper pressure housing part from the lower pressure housing part by opening the pressure housing flange connection, lifting the upper pressure housing part away from the lower pressure housing part and thereby exposing the insulating bell, lifting the insulating bell away and thereby exposing the stack module, disconnecting the stack module from all connections to the solid oxide electrolyzer, replacing the stack module, reconnecting the stack module to the connections to the solid oxide electrolyzer, and closing the solid oxide electrolyzer by resetting the insulating bell and the upper pressure housing.

[0031] By this method, the stack module can be replaced efficiently in terms of time and cost, as the replacement requires a minimum amount of disconnection work, can be carried out without a solid oxide electrolyzer expert, and components other than the stack module, in particular the insulators, can be reused.

[0032] In a preferred embodiment of the method, the stack module includes two gas inlet connectors and two gas outlet connectors having thermal quick couplers, wherein the step of disconnecting the stack module from all connections to the solid oxide electrolyzer includes disconnecting the thermal quick couplers of the two gas inlet connectors and the two gas outlet connectors, and wherein the step of reconnecting the stack module to the connections to the solid oxide electrolyzer includes connecting the thermal quick couplers of the two gas inlet connectors and the two gas outlet connectors. The thermal quick couplers further improve the time efficiency of the method.

[0033] The embodiments of the invention will be explained in more detail below with reference to the drawings.

[0034] Figure 1 An axial cross-section through a stack module according to an embodiment of the invention is shown,

[0035] Figure 2 An axial cross-section through a solid oxide electrolyzer according to a first embodiment of the invention is shown, the solid oxide electrolyzer having a stack module according to the embodiment shown in Figure 1 the embodiment shown in

[0036] Figure 3 shows a Figure 2 schematic exploded view of an axial section through the solid oxide electrolyzer shown, which shows a method for replacing a stacked module of a solid oxide electrolyzer according to the present invention, and

[0037] Figure 4 shows an axial section through a solid oxide electrolyzer according to a second embodiment of the present invention, the solid oxide electrolyzer having a stacked module according to the Figure 1 embodiment shown in

[0038] Figure 1 shows an axial section through stacked module 1 according to an embodiment of the present invention. Stacked module 1 includes two solid oxide electrolysis stacks 2, which are constructed of a plurality of stacked solid oxide electrolysis cells 3. The two solid oxide electrolysis stacks 2 are arranged on opposite sides of a symmetric common manifold 4, with gaskets (not shown) placed between the respective solid oxide electrolysis stacks 2 and the common manifold 4. The two solid oxide electrolysis stacks 2 are encapsulated in two encapsulation covers 5, and the two encapsulation covers 5, in combination with the common manifold 4 and two lids 6, form a metal container. The two lids 6 are thus in the respective encapsulation covers 5 at opposite ends at the ends of the respective solid oxide electrolysis stacks 2 located at the common manifold 4. A ceramic fiber gasket 7 is placed between the lid 6 and the solid oxide electrolysis stack 2. By fixing the position of the lid 6 relative to the common manifold 4 by welding during application of a certain pressure from the opposite sides, the ceramic fiber gasket 7 is compressed and acts as a spring, which maintains a certain pressure on the solid oxide electrolysis stack 2 and thus on the gasket (not shown). Due to the different thermal expansion coefficients of the encapsulation cover 5 and the solid oxide electrolysis stack 2, the ceramic fiber gasket 7 ensures sealing through the gasket between the solid oxide electrolysis stack 2 and the common manifold 4 over different temperature ranges.

[0039] Stacked module 1 further includes two gas inlet connectors 8, 9 and two gas outlet connectors 10, 11 connected to the common manifold 4. In Figure 1In [the figure], the airflow through the stacking module 1 is indicated by arrows. The first airflow enters the common manifold 4 through the first of the two gas inlet connectors 8, where the first airflow exits the manifold 4 through the first gas inlet, which is directed into the respective gaps between the encapsulation shroud 5 and the solid oxide electrolysis stack 2. The solid oxide electrolysis cell 3 includes two sides, an anode side and a cathode side, where the solid oxide electrolysis cell 3 is separated by an airtight separator plate. The first airflow enters the volume between one side of each of the two sides of the respective solid oxide electrolysis cell 3 and the corresponding adjacent separator plate from the respective gaps, and then travels through this volume towards the centrally disposed hole in the respective solid oxide stack 2, from where the first airflow exits the common manifold 4 through the corresponding first gas outlet in the centrally disposed hole, and the first gas outlet is connected to the first of the two gas outlet connectors 10.

[0040] The second airflow enters the common manifold 4 through the second of the two gas inlet connectors 9, where the second airflow exits the common manifold 4 through the second gas inlet, which is directed into the respective holes in the respective solid oxide stacks 2, and the holes extend upward through the full stack height, from where the second airflow enters the other volume between the other side of the two sides of the solid oxide electrolysis cell 3 and the corresponding adjacent separator plate, and is transferred through this other volume to another hole at the full stack height, from where the second airflow exits the common manifold through the second gas outlet, and the second gas outlet is connected to the second of the two gas outlet connectors 11.

[0041] In addition, the stacking module 1 includes four power connectors 12, which are connected to the solid oxide electrolysis stack 2 to supply power to it.

[0042] Figure 2 An axial cross-section of a solid oxide electrolyzer 13 according to a first embodiment of the present invention is shown, and the solid oxide electrolyzer 13 has a stacking module 1 according to the embodiment shown in Figure 1 [the figure]. Figure 2 This is only schematic, as the solid oxide electrolyzer 13 preferably includes a plurality of stacking modules 1. For example, six stacking modules 1 arranged in a circle around the axis of the solid oxide electrolyzer 13. In addition, the airflow as well as the reactant gas pipes and product gas pipes are in Figure 2 , 3In FIGS. 3 and 4, they are only schematically shown as black arrows. The solid oxide electrolyzer 13 includes a pressure housing, which is divided into an upper pressure housing part 14 and a lower pressure housing part 15 connected by a pressure housing flange connection 16. A hot zone insulator is arranged within the pressure housing, wherein the hot zone insulator surrounds the hot zone 17 in which the stack module 1 is placed, and wherein the hot zone insulator is divided into an insulating bell 18 and a static insulating part 19. In this embodiment, all external connections to the solid oxide electrolyzer 13 (such as reactant gas pipes, product gas pipes, power connections for the stack module, power connections for the heater 20, and connections for additional instruments and data collection) are guided through the lower pressure housing part 15, and in the case where they enter the hot zone 17, through the static insulating assembly 19 and not through the upper pressure housing part 14 and the insulating bell 18. In this way, when the pressure housing flange connection 16 is opened, the upper pressure housing part can be lifted away from the lower pressure housing part 15. The pressure housing flange connection 16 is thus located at the widest diameter of the pressure housing and at the same height as the static insulating part 19. Therefore, when the upper pressure housing part 14 is lifted away, the entire insulating bell 18 is exposed.

[0043] The insulating bell 18 is an integral assembly that is open downward and placed on a hot zone insulating gasket 24 arranged at the static insulating part 19. In this way, the hot zone is sealed by the weight of the insulating bell 18 through the hot zone insulating gasket 24. The insulating bell 18 of this embodiment is constructed of three layers, namely an airtight inner lining 25, an insulating material layer 26, and an outer structural layer 27. With these layers, the insulating bell 18 is airtight, well-insulated, and rigid. Since no connections are guided through the insulating bell 18, when the upper pressure housing part 14 is lifted away, the insulating bell 18 can be lifted away from the hot zone insulating gasket in one piece. By lifting away the insulating bell 18, the stack module 18 is exposed and can be replaced, for example.

[0044] The solid oxide electrolyzer 13 further includes a recuperation space 21 that surrounds the hot zone insulator. One of the reactant gas streams is directed through a reactant gas duct that passes through a first portion of the lower pressure housing section 15 to the recuperation space 21 to recuperate heat from the hot zone insulator and then is directed into a riser tube 28 that is connected by a connector to a second portion of the reactant gas duct, the second portion directing one of the reactant gas streams through the static insulation member 19 into the hot zone 17. The riser tube 28 is directed from the connector to the second portion of the reactant gas duct through the recuperation space 21 between the upper pressure housing section 14 and the insulating bell 18 to a point above the insulating bell 18 where one of the reactant gas streams enters the riser tube 28 from the recuperation space 21. Another of the reactant gas streams is directed directly through the lower pressure housing section 15 and the static insulation member 19 into the hot zone 17. In the hot zone 17, the two reactant gas streams are directed through a heat exchanger 22 to exchange heat with two product gas streams and then are directed through two heaters 20 to be heated to the reaction temperature. The reactant gas streams are then directed into the stack module 1 via two gas inlet connectors of the stack module 1, where the two gas inlet connectors are connected to the reactant gas duct by a thermal quick coupler 23, and two gas outlet connectors of the stack module 1 are also connected by the thermal quick coupler 23 to a subsequent product gas duct that is independent of the stack module 1.

[0045] Figure 3 Shows through Figure 2Schematic exploded view of an axial section of the solid oxide electrolyzer 13 shown, which shows a method of replacing the stack module 1 of the solid oxide electrolyzer 13 according to the invention. Since the stack module 1 in the solid oxide electrolyzer 13 has a shorter lifespan than other components (such as the pressure housing, the hot zone insulator, the heater 20, and the heat exchanger 22), the replacement of the stack module 1 must be carried out several times during the lifespan of the solid oxide electrolyzer 13. To reduce downtime and promote maintainability, the process must be simple, fast, and efficient. This is achieved by the method according to the invention. After opening the pressure housing flange connection 16, the first step of the method is to lift off the upper pressure housing part 14. Since no external connections are guided through the upper pressure housing part 14, this can be done without further disconnection work and is thus very efficient. By lifting off the upper pressure housing part 14, the insulating bell 18 is completely exposed and can also be easily lifted off in the next step, since for the first embodiment of the solid oxide electrolyzer 13 no connections are guided through this insulating bell 18. Thereby, the stack module 1 is completely exposed. By opening the thermal quick coupler 23, the gas connections are separated from the gas inlet connections 8, 9 and the gas outlet connections 10, 11 of the stack module 1, and by separating additional connections, such as the power supply connection, from the stack module 1, the stack module 1 can thus be separated from the rest of the solid oxide electrolyzer 13 and lifted out of its position in the hot zone 17. Since the connection between the stack module 1 and the rest of the solid oxide electrolyzer 13 is simple and easy to open, and due to the metal container of the stack module 1, this can be easily done without a solid oxide expert. Since the new stack module 1 is also supplied in its metal container and has a thermal quick coupler 23, the stack module 1 is ready to be installed in the solid oxide electrolyzer 13. For this purpose, the new stack module 1 is placed in the position of the removed stack module 1 and reconnected to the connections of the rest of the solid oxide electrolyzer 13. Then, the insulating bell 18 is replaced to seal the hot zone 17, and subsequently the upper part of the pressure housing 14 can be reset around the insulating bell 18. By closing the pressure housing flange connection 16, the method of replacing the stack module 1 is completed.

[0046] Figure 4 An axial section of the solid oxide electrolyzer 13 according to a second embodiment of the invention is shown, which solid oxide electrolyzer 13 has a stack module according to the Figure 1 embodiment shown in Figure 2The only difference in the first embodiment of the solid oxide electrolyzer 13 is due to the different arrangement of the gas riser 28 and the resulting changes. The gas riser 28 is led from its connection to the second part of the reactant gas duct into the insulating bell 18 and through the insulating bell 18 to the top height of the insulating bell 18, where the gas riser 28 leaves the insulating bell 18 at a position on the axis of the insulating bell 18 and enters the recuperation space 21. The connection between the second part of the reactant gas duct and the insulating bell 18 is configured as a flange connection. When the upper pressure housing part 14 is removed, this flange connection must be opened in order to lift the insulating bell 18. In addition, disconnection work is not necessary.

[0047] List of reference numerals

[0048] 1 Stack module

[0049] 2 Solid oxide electrolysis stack

[0050] 3 Solid oxide electrolysis cell

[0051] 4 Common manifold

[0052] 5 Encapsulation hood

[0053] 6 Cover

[0054] 7 Ceramic fiber mat

[0055] 8 First gas inlet connection

[0056] 9 Second gas inlet connection

[0057] 10 First gas outlet connection

[0058] 11 Second gas outlet connection

[0059] 12 Power supply connection

[0060] 13 Solid oxide electrolyzer

[0061] 14 Upper pressure housing part

[0062] 15 Lower pressure housing part

[0063] 16 Pressure housing flange connection

[0064] 17 Hot zone

[0065] 18 Insulating bell

[0066] 19 Static insulation component

[0067] 20 Heater

[0068] 21 Recuperation space

[0069] 22 Heat exchanger

[0070] 23 Thermal quick coupler

[0071] 24 Thermal zone insulating gasket

[0072] 25 Airtight inner lining

[0073] 26 Insulating material layer

[0074] 27 Outer structure layer

[0075] 28 Vent pipe

Claims

1. A solid oxide electrolyzer (13) comprising a pressure housing and a hot zone insulator within the pressure housing, wherein the hot zone insulator surrounds a hot zone (17) in which at least one stack module (1) is placed, the stack module (1) having stacked solid oxide electrolysis cells (3), characterized in that, The pressure housing includes a lower pressure housing part (15) and an upper pressure housing part (14) connected by a pressure housing flange connection (16), and wherein the hot zone insulator includes an insulating bell (18) and a static insulating part (19), wherein external connections including electrical connections, reactant gas pipes and product gas pipes pass through the lower pressure housing part (15) but not through the upper pressure housing part (14), such that the upper pressure housing part (14) can be lifted away from the lower pressure housing part (15) when the pressure housing flange connection (16) is opened without further disconnection work, and wherein the electrical connection and the product gas pipe pass through the static insulating part (19) but not through the insulating bell (18), such that the insulating bell (18) can be lifted when the upper pressure housing part (14) is removed without disconnection work regarding the electrical connection and the product gas pipe.

2. The solid oxide electrolyzer (13) according to claim 1, characterized in that, The insulating bell (18) opens downward and is preferably made of a single piece.

3. The solid oxide electrolyzer (3) according to claim 1 or 2, characterized in that, The insulating bell (18) is itself airtight and structurally stable, wherein the insulating bell (18) preferably consists of an airtight inner lining (25), an insulating material layer (26) and an outer structural layer (27), or consists of a structurally stable insulating material, preferably a ceramic lightweight castable material, and the insulating bell (18) is entirely made of this ceramic lightweight castable material.

4. The solid oxide electrolyzer (13) according to any one of claims 1 to 3, characterized in that, The position of the static insulating part (19) is fixed relative to the position of the lower pressure housing part (15), wherein a hot zone insulating gasket (24) is arranged on the static insulating part (19), and the insulating bell (18) is placed thereon and thereby hermetically insulates the hot zone (17).

5. The solid oxide electrolyzer (13) according to any one of claims 1 to 4, characterized in that, The pressure housing flange (16) is located at the highest diameter of the solid oxide electrolyzer (13), and preferably at or below the position of the hot zone insulating gasket (24).

6. The solid oxide electrolyzer (13) according to any one of claims 1 to 5, characterized in that, The solid oxide electrolyzer (13) includes a recuperative heat exchange space (21) arranged at least partially around the outside of the hot zone insulator, wherein a first part passing through the lower pressure housing part (15) introduces a first reactant gas into the recuperative heat exchange space (21), and wherein the first reactant gas leaves the recuperative heat exchange space (21) via a vent pipe (28) and enters a second part of the reactant gas pipe, and the second part passes through the static insulating part (19) and is guided to the stack module (1) in the hot zone (17).

7. The solid oxide electrolyzer (13) according to claim 6, characterized in that The vent pipe extends along and away from the outside of the hot zone insulator from the connection to the second part of the reactant gas pipe through the recuperative heat exchange space to a point at or above the top height of the hot zone insulator, or the vent pipe is guided from the connection to the second part of the reactant gas pipe into the insulating bell and through the insulating bell to the top height of the hot zone insulator, where the vent pipe leaves the insulating bell and enters the recuperative heat exchange space.

8. The solid oxide electrolyzer (13) according to any one of the preceding claims, comprising a stack module (1) having at least one solid oxide electrolysis stack (2), the solid oxide electrolysis stack (2) comprising a plurality of stacked solid oxide electrolysis cells (3), wherein the stack module (1) comprises two gas inlet connectors (8, 9) and two gas outlet connectors (10, 11), Characterized in that The at least one solid oxide electrolysis stack (2) is encapsulated in a metal container, wherein the two gas inlet connectors (8, 9) and the two gas outlet connectors (10, 11) are connected to the metal container.

9. The solid oxide electrolyzer (13) according to claim 8, characterized in that, The two gas inlet connectors (8, 9) and the two gas outlet connectors (10, 11) each comprise a thermal quick coupler (23) connecting them to an external gas inlet or outlet, wherein preferably, the thermal quick coupler is configured as a pipe joint.

10. The solid oxide electrolyzer (13) according to claim 8 or 9, characterized in that, The stack module (1) comprises two solid oxide electrolysis stacks (2), the two solid oxide electrolysis stacks (2) being assembled by the common manifold (4), the common manifold (4) being part of the metal container, and the two gas inlet connectors (8, 9) and the two gas outlet connectors (10, 11) being connected to the common manifold (4).

11. The solid oxide electrolyzer (13) according to claim 10, characterized in that The two solid oxide electrolysis stacks (2) are placed within respective encapsulation covers (5), the encapsulation covers (5) combined with the common manifold (4) and two lids (6) form the metal container, the two lids (6) being placed in one of the encapsulation covers (5) respectively to encapsulate the solid oxide electrolysis stacks (2) within the encapsulation covers (5).

12. The solid oxide electrolyzer (13) according to claim 11, characterized in that Gaskets are placed between the two solid oxide electrolysis stacks (2) and the common manifold (5), and ceramic fiber pads (7) are placed between the two solid oxide electrolysis stacks (2) and the respective lids (6) within the encapsulation covers (5), wherein the lids (6) are preferably fixed to their positions within the encapsulation covers (5) by welding, and the ceramic fiber pads (7) are configured to apply a compressive force to the respective solid oxide electrolysis stacks (2), and thereby to the respective gaskets and the common manifold (4).

13. The solid oxide electrolyzer (13) according to any one of claims 10 to 12, characterized in that, The two solid oxide electrolysis stacks (2) are arranged on opposite sides of the common manifold (4), wherein the two solid oxide electrolysis stacks (2) are preferably configured symmetrically with respect to a symmetry plane passing through the common manifold (4), the symmetry plane being perpendicular to the axis of the encapsulation cover body (5), wherein the common manifold (4) is preferably also constructed symmetrically with respect to the symmetry plane.

14. The solid oxide electrolyzer (13) according to claim 13, characterized in that Each stacked solid oxide electrolysis cell (3) comprises two sides, an anode side and a cathode side, where different gas flows can be supplied to the two sides, and where the stacked solid oxide electrolysis cell (3) is separated by gastight separator plates, where the common manifold (4) comprises respective first gas inlets for two solid oxide electrolysis stacks (2), the first gas inlets being supplied by the first of two gas inlet connectors (8) and introducing a first gas flow into respective voids between the encapsulation shroud and the solid oxide electrolysis stack (2), where the first gas flow then enters the volume between one of the two sides of the respective solid oxide electrolysis cell (3) and the corresponding adjacent separator plate and then travels through the volume towards a centrally arranged hole in the respective solid oxide electrolysis stack (2), from where the first gas flow leaves the common manifold (4) through a respective first gas outlet, the first gas outlet being connected to the first of two gas outlet connectors (10), where the common manifold (4) further comprises a second gas inlet for the two solid oxide electrolysis stacks (2), the second gas inlet being supplyable with a second gas flow through the second of two gas inlet connectors (9), guiding the second gas flow into respective holes in the respective solid oxide electrolysis stacks (2), the holes extending upwards through the full stack height, from where the second gas flow enters the other volume between the other of the two sides of the solid oxide electrolysis cell (3) and the corresponding adjacent separator plate and then being transferred through the other volume to another hole at the full stack height, from where the second gas flow leaves the common manifold through the second gas outlet, the second gas outlet being connected to the second of two gas outlet connectors (11).

15. A method for replacing a stack module (1) of a solid oxide electrolyzer (13) according to any one of claims 1 to 8, wherein the method comprises the following steps: Disconnect the upper pressure housing part (14) from the lower pressure housing part (15) by opening the pressure housing flange connector (16), lift the upper pressure housing part (14) away from the lower pressure housing part (15) and thereby expose the insulating bell (18), lift the insulating bell (18) away and thereby expose the stack module (1), disconnect the stack module (1) from all connectors to the solid oxide electrolyser (13), replace the stack module (1), reconnect the stack module (1) to the connectors to the solid oxide electrolyser (13), and close the solid oxide electrolyser (13) by resetting the insulating bell (18) and the upper pressure housing (14).

Images