Water vapor electrolysis apparatus

Abstract

The present invention provides a steam electrolysis apparatus capable of heating the cell stack as uniformly as possible. [Solution] The steam electrolysis apparatus comprises a cell stack group 101G, which consists of multiple cell stacks in which electrolytic cells, each comprising a hydrogen electrode, an electrolyte, and an oxygen electrode, are electrically connected via interconnectors, and a heating tube 3 provided outside the cell stack group 101G through which a heat transfer medium flows. The heating tube 3 is provided at a predetermined distance from the cell stack group 101G. The heating tube 3 is arranged in a spiral shape so as to surround the cell stack group 101G.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a steam electrolysis device. BACKGROUND ART

[0002] As a technology for realizing a low-carbon and decarbonized society, development of hydrogen production technology utilizing high-temperature thermal energy generated by a high-temperature gas reactor is being carried out. One of the hydrogen production methods that can utilize high-temperature thermal energy is SOEC (Solid Oxide Electrolysis Cell).

[0003] Patent Document 1 discloses that as a method for transferring nuclear heat from a high-temperature gas reactor to SOEC, a flow path for flowing helium gas guided from the high-temperature gas reactor is formed on the outside of a cylindrical cell stack to heat each cell stack. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0004] PATENT DOCUMENT 1 Japanese Unexamined Patent Application Publication No. 2023-20282 SUMMARY OF INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] However, in Patent Document 1, since a helium gas flow path is provided for each cell stack, the structure may be complicated and the cost may increase. In addition, since the flow of helium is not clearly specified, the helium flow inside the cartridge is unregulated, and an unexpected flow (such as a circulating flow) may occur, which may prevent efficient heating.

[0006] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a steam electrolysis device capable of heating a cell stack as uniformly as possible. MEANS FOR SOLVING THE PROBLEMS

[0007] A steam electrolysis apparatus according to one aspect of the present disclosure comprises a group of cell stacks, each consisting of an electrolytic cell comprising a hydrogen electrode, an electrolyte, and an oxygen electrode, which are electrically connected via an interconnector; and a heating section provided outside the group of cell stacks through which a heat transfer medium flows. [Effects of the Invention]

[0008] The cell stack can be heated as uniformly as possible. [Brief explanation of the drawing]

[0009] [Figure 1] This is a partially enlarged longitudinal cross-sectional view showing a portion of the cell stack of an SOEC according to the first embodiment of this disclosure. [Figure 2] This is a longitudinal cross-sectional view showing an SOEC cartridge. [Figure 3] This diagram shows a schematic configuration for supplying heat from a high-temperature gas reactor to a heating tube. [Figure 4] This is a perspective view of the main part of the cartridge, showing the spirally shaped heating tube. [Figure 5] This is a perspective view of the main part of a cartridge showing a winding heating tube, which is a second embodiment of the present disclosure. [Figure 6] This is a perspective view showing a modified example of Figure 5. [Figure 7] This is a side view showing a modified example of Figure 6. [Figure 8] This is a plan view of Figure 7. [Figure 9] This is a third embodiment of the present disclosure, and is a perspective view of the main part of a cartridge showing a heating tube in a collapsible shape. [Figure 10] This is a side view showing a modified example of Figure 9. [Figure 11] This is a perspective view of the main part of a cartridge showing a heating section using a radiant panel, which is a fourth embodiment of the present disclosure. [Figure 12] Figure 11 is a perspective view showing the radiation panel. [Figure 13]This is a perspective view showing a modified example of Figure 12. [Modes for carrying out the invention]

[0010] [First Embodiment] The first embodiment of this disclosure will be described below. This explanation uses cylindrical solid oxide electrolytic cells as an example of a cell stack for solid oxide electrolytic cells (SOECs) that constitute a steam electrolysis apparatus. However, this is not necessarily the only option; for example, a flat-plate cell stack may also be used. Although the electrolytic cells are formed on a substrate, the electrodes (hydrogen or oxygen electrodes) may be formed thickly and serve as both the substrate and the electrodes. Below, an embodiment of the structure and materials of a cylindrical solid oxide electrolytic cell according to this disclosure will be described with reference to the drawings.

[0011] For the sake of clarity, the positional relationships of each component described using the terms "upper" and "lower" relative to the paper surface refer to the vertically upward and vertically downward directions, respectively. Furthermore, in this embodiment, components that achieve similar effects in both the vertical and horizontal directions do not necessarily have to be limited to the vertically up and down directions on the paper surface; for example, they may correspond to the horizontal direction perpendicular to the vertical direction.

[0012] First, a cylindrical cell stack using a base tube will be described as an example according to the present embodiment with reference to FIG. 1. When a base tube is not used, for example, the fuel electrode may be formed thick to double as the base tube, and the present invention is not limited to the use of a base tube. In addition, although the base tube in the present embodiment is described using a cylindrical shape, the base tube only needs to be tubular, and the cross section is not necessarily limited to a circular shape, and may be, for example, an elliptical shape. A cell stack such as a flat cylinder (Flat tubular) obtained by vertically crushing the peripheral side surface of a cylinder may also be used. Here, FIG. 1 shows one aspect of the cell stack according to the embodiment. The cell stack 101 includes, as an example, a cylindrical base tube 103, a plurality of electrolysis cells 105 formed on the outer peripheral surface of the base tube 103, and an interconnector 107 formed between adjacent electrolysis cells 105. The electrolysis cell 105 is formed by laminating a hydrogen electrode 109, a solid electrolyte membrane 111, and an oxygen electrode 113. In addition, the cell stack 101 includes, on the oxygen electrode 113 of the electrolysis cell 105 formed at the most distal end in the axial direction of the base tube 103 among the plurality of electrolysis cells 105 formed on the outer peripheral surface of the base tube 103, a lead film 117 electrically connected via the interconnector 107, and includes a lead film 117 electrically connected to the hydrogen electrode 109 of the electrolysis cell 105 formed at the other most distal end. The gas supplied to and discharged from the hydrogen electrode 109 often contains hydrogen in addition to the water vapor used for electrolysis, but in the following description, to avoid confusion, the supply gas containing hydrogen is referred to as "supply water vapor", and the hydrogen gas containing water vapor discharged from the hydrogen electrode is referred to as "generated hydrogen".

[0013] The base tube 103 is made of a porous material, and contains, for example, CaO-stabilized ZrO2 (CSZ), a mixture of CSZ and nickel oxide (NiO) (CSZ+NiO), Y2O3-stabilized ZrO2 (YSZ), MgAl2O4, or the like as a main component. The base tube 103 supports the electrolysis cell 105, the interconnector 107, and the lead film 117, and diffuses the supply water vapor supplied to the inner peripheral surface of the base tube 103 through the pores of the base tube 103 to the hydrogen electrode 109 formed on the outer peripheral surface of the base tube 103.

[0014] The hydrogen electrode 109 is composed of an oxide of a composite material of Ni and a zirconia-based electrolyte material, and for example, Ni / YSZ is used. The thickness of the hydrogen electrode 109 is 50 μm to 250 μm, and the hydrogen electrode 109 may be formed by screen-printing a slurry. As the solid electrolyte membrane 111, YSZ that has gas-tightness making it difficult for gas to pass through and high oxygen ion conductivity at high temperatures is mainly used. This solid electrolyte membrane 111 transfers oxygen ions (O²⁻) generated at the hydrogen electrode to the oxygen electrode. The film thickness of the solid electrolyte membrane 111 located on the surface of the hydrogen electrode 109 is 5 μm to 100 μm, and the solid electrolyte membrane 111 may be formed by screen-printing a slurry. The oxygen electrode 113 is composed of, for example, a LaSrMnO₃-based oxide or a LaCoO₃-based oxide, and the oxygen electrode 113 is formed by applying a slurried material using screen printing or a dispenser. The oxygen electrode 113 may also have a two-layer structure. In this case, the oxygen electrode layer (oxygen electrode intermediate layer) on the solid electrolyte membrane 111 side exhibits high ionic conductivity and is composed of a material with excellent catalytic activity. The oxygen electrode intermediate layer may be composed of Sm-doped ceria exhibiting high ionic conductivity, and the oxygen electrode layer (oxygen electrode conductive layer) on the oxygen electrode intermediate layer may be composed of a perovskite-type oxide such as Sr- and Ca-doped LaMnO₃.

[0015] By applying a negative voltage to the hydrogen electrode 109 and a positive voltage to the oxygen electrode 113, at the hydrogen electrode 109, the water vapor contained in the supplied water vapor receives electrons and is electrolyzed to generate hydrogen molecules and oxygen ions (O²⁻) (see the following reaction formula (1)). The generated hydrogen is extracted to the outside together with the supplied water vapor. On the other hand, oxygen ions pass through the solid electrolyte membrane 111 due to the potential difference, move to the oxygen electrode 113, release electrons, and become oxygen molecules (the following see reaction formula (2)). The generated oxygen is discharged to the outside together with the oxidizing gas supplied to the oxygen electrode. H₂O + 2e⁻ → H₂ + O²⁻ ···(1) 2O²⁻ → O₂ + 4e⁻ ···(2)

[0016] Oxidizing gases do not directly participate in the electrolytic reaction, but they supply the heat necessary for the electrolytic reaction (endothermic reaction) and dissipate excess heat generated during the electrolytic reaction. Typically, these gases contain approximately 15% to 30% oxygen, and air is the most suitable choice. However, other gases such as mixtures of combustion exhaust gas and air, mixtures of oxygen and air, and inert gases such as nitrogen can also be used.

[0017] The interconnector 107 is composed of a conductive perovskite-type oxide represented by M1-xLxTiO3 (where M is an alkaline earth metal element and L is a lanthanide element), such as SrTiO3, or lanthanum chromite (LaCrO3), and is screen printed as a slurry. The interconnector 107 has a dense film to prevent mixing of the supplied water vapor and the oxidizing gas. Furthermore, the interconnector 107 has stable durability and electronic conductivity under both oxidizing and reducing atmospheres. In adjacent electrolytic cells 105, the interconnector 107 electrically connects the oxygen electrode 113 of one electrolytic cell 105 to the hydrogen electrode 109 of the other electrolytic cell 105, thereby connecting adjacent electrolytic cells 105 in series.

[0018] The lead film 117 is required to possess electronic conductivity and have a thermal expansion coefficient close to that of the other materials constituting the cell stack 101. Therefore, it is composed of a composite material of Ni and zirconia-based electrolyte material such as Ni / YSZ, or M1-xLxTiO3 (where M is an alkaline earth metal element and L is a lanthanide element) such as SrTiO3. This lead film 117 applies the DC power necessary for the electrolytic reaction to the ends of the cell stack 101 to multiple electrolytic cells 105 connected in series by an interconnector 107. Furthermore, the surface on the oxidizing gas side may be protected with an airtight, oxidation-resistant material to prevent oxidation of metal materials such as Ni.

[0019] Next, the SOEC cartridge according to this embodiment will be described with reference to Figure 2. Here, Figure 2 shows one embodiment of the solid oxide electrolytic cell (SOEC) cartridge according to this embodiment.

[0020] As shown in Figure 2, the cartridge 203 comprises a plurality of cell stacks 101, a water vapor electrolysis chamber 215, a water vapor supply header 217, a generated hydrogen discharge header 219, an oxidizing gas (air) supply header 221, and an oxidizing gas discharge header 223. The cartridge 203 also comprises an upper tube sheet 225a, a lower tube sheet 225b, an upper insulator 227a, and a lower insulator 227b. In this embodiment, the water vapor supply header 217, the generated hydrogen discharge header 219, the oxidizing gas supply header 221, and the oxidizing gas discharge header 223 are arranged as shown in Figure 2, so that the supplied water vapor and oxidizing gas flow in opposition to each other on the inside and outside of the cell stack 101. However, this is not necessarily required, and for example, the gas may flow parallel to each other on the inside and outside of the cell stack 101, or the oxidizing gas may flow in a direction perpendicular to the longitudinal direction of the cell stack 101. The cartridge 203 is composed of one or more cartridges 203, insulation material, a storage container, etc., forming a module (not shown). The module is a device that maintains an operating state suitable for hydrogen production.

[0021] The steam electrolysis chamber 215 is a region formed between the upper insulator 227a and the lower insulator 227b. This steam electrolysis chamber 215 is the region where the electrolytic cells 105 of the cell stack 101 are located, and it is the region where water vapor is electrolyzed to produce hydrogen. The temperature near the center of the cell stack 101 in the longitudinal direction of this steam electrolysis chamber 215 may also be monitored by the temperature measurement unit 620 (such as a temperature sensor or thermocouple), and during steady-state operation, the atmosphere becomes high-temperature, approximately 700°C to 1000°C.

[0022] The steam supply header 217 is the region enclosed by the upper casing 229a and upper tube sheet 225a of the cartridge 203, and is connected to a steam supply branch pipe (not shown) by a steam supply pipe 231a provided on the upper part of the upper casing 229a. The multiple cell stacks 101 are joined together by the upper tube sheet 225a and the upper sealing member 237a, and the steam supply header 217 guides the steam supplied from the steam supply branch pipe (not shown) via the steam supply pipe 231a into the base pipe 103 of the multiple cell stacks 101 at a substantially uniform flow rate, thereby substantially equalizing the hydrogen generation performance of the multiple cell stacks 101.

[0023] The generated hydrogen discharge header 219 is the region enclosed by the lower casing 229b and lower tube sheet 225b of the cartridge 203, and is connected to a generated hydrogen discharge branch pipe (not shown) by a generated hydrogen discharge pipe 231b provided in the lower casing 229b. In addition, multiple cell stacks 101 are joined together by the lower tube sheet 225b and the lower sealing member 237b, and the generated hydrogen discharge header 219 collects the generated hydrogen that passes through the inside of the base tube 103 of the multiple cell stacks 101 and is supplied to the generated hydrogen discharge header 219, and guides it to the generated hydrogen discharge branch pipe (not shown) via the generated hydrogen discharge pipe 231b.

[0024] The oxidizing gas supply main pipe (not shown) branches off a predetermined flow rate of oxidizing gas corresponding to the operating temperature of the module to oxidizing gas supply branch pipes (not shown), supplying it to multiple cartridges 203. The oxidizing gas supply header 221 is the region surrounded by the lower casing 229b, lower tube sheet 225b, and lower insulator 227b of the cartridge 203, and is connected to an oxidizing gas supply branch pipe (not shown) by an oxidizing gas supply pipe 233a provided on the side of the lower casing 229b. This oxidizing gas supply header 221 guides the oxidizing gas supplied from the oxidizing gas supply branch pipe (not shown) via the oxidizing gas supply pipe 233a to the steam electrolysis chamber 215 via an oxidizing gas lower penetration section 235a, which will be described later.

[0025] The oxidizing gas discharge header 223 is the region enclosed by the upper casing 229a, upper tube sheet 225a, and upper insulator 227a of the cartridge 203, and is connected to an oxidizing gas discharge branch pipe (not shown) by an oxidizing gas discharge pipe 233b provided on the side of the upper casing 229a. This oxidizing gas discharge header 223 guides the exhaust oxidizing gas supplied from the steam electrolysis chamber 215 to the oxidizing gas discharge header 223 via the oxidizing gas upper penetration section 235b (described later) to an oxidizing gas discharge branch pipe (not shown) via the oxidizing gas discharge pipe 233b.

[0026] The upper tube sheet 225a is fixed to the side plate of the upper casing 229a between the top plate of the upper casing 229a and the upper insulator 227a, such that the upper tube sheet 225a, the top plate of the upper casing 229a, and the upper insulator 227a are substantially parallel to each other. The upper tube sheet 225a also has a number of holes corresponding to the number of cell stacks 101 provided in the cartridge 203, and each cell stack 101 is inserted into a hole. This upper tube sheet 225a airtightly supports one end of each of the cell stacks 101 via either or both of the upper sealing member 237a and the adhesive member, and also isolates the water vapor supply header 217 from the oxidizing gas discharge header 223.

[0027] The upper insulator 227a is positioned at the lower end of the upper casing 229a such that the upper insulator 227a, the top plate of the upper casing 229a, and the upper tube sheet 225a are substantially parallel, and is fixed to the side plate of the upper casing 229a. The upper insulator 227a is also provided with multiple holes corresponding to the number of cell stacks 101 provided in the cartridge 203. The diameter of these holes is set to be larger than the outer diameter of the cell stacks 101. The upper insulator 227a includes an oxidizing gas upper penetration portion 235b formed between the inner surface of these holes and the outer surface of the cell stacks 101 inserted into the upper insulator 227a.

[0028] The upper insulator 227a separates the steam electrolysis chamber 215 from the oxidizing gas exhaust header 223, preventing the atmosphere around the upper tube sheet 225a from becoming too hot, which would reduce its strength and increase corrosion due to the oxidizing agent contained in the oxidizing gas. In addition, to suppress thermal deformation of the upper tube sheet 225a and other components due to temperature differences as they are exposed to the high temperatures inside the steam electrolysis chamber 215, a metal material with high temperature resistance, such as a Ni-based alloy, may be used. The upper insulator 227a guides the exhaust oxidizing gas, which has passed through the steam electrolysis chamber 215 and been exposed to high temperatures, through the upper oxidizing gas penetration section 235b to the oxidizing gas exhaust header 223.

[0029] According to this embodiment, the structure of the cartridge 203 described above causes the supply steam and the oxidizing gas to flow in opposition to each other on the inside and outside of the cell stack 101. As a result, the exhaust oxidizing gas exchanges heat with the steam supplied to the steam electrolysis chamber 215 through the inside of the base tube 103, and is cooled to a temperature at which damage to the upper tube sheet 225a, etc., made of metal material, can be prevented by stress before being supplied to the oxidizing gas discharge header 223. In addition, the supply steam is heated by heat exchange with the exhaust oxidizing gas discharged from the steam electrolysis chamber 215 and supplied to the steam electrolysis chamber 215. As a result, steam preheated to the temperature required for the electrolytic reaction can be supplied to the steam electrolysis chamber 215 without the use of heaters or the like.

[0030] The lower tube sheet 225b is fixed to the side plate of the lower casing 229b between the bottom plate of the lower casing 229b and the lower insulator 227b, such that the lower tube sheet 225b, the bottom plate of the lower casing 229b, and the lower insulator 227b are substantially parallel to each other. The lower tube sheet 225b also has a number of holes corresponding to the number of cell stacks 101 provided in the cartridge 203, and each cell stack 101 is inserted into a respective hole. This lower tube sheet 225b airtightly supports the other end of each of the cell stacks 101 via either the lower sealing member 237b or the adhesive member, or both, and also isolates the generated hydrogen discharge header 219 from the oxidizing gas supply header 221.

[0031] The lower insulator 227b is positioned at the upper end of the lower casing 229b such that the lower insulator 227b, the bottom plate of the lower casing 229b, and the lower tube sheet 225b are substantially parallel, and is fixed to the side plate of the lower casing 229b. The lower insulator 227b is also provided with multiple holes corresponding to the number of cell stacks 101 provided in the cartridge 203. The diameter of these holes is set to be larger than the outer diameter of the cell stacks 101. The lower insulator 227b includes an oxidizing gas lower penetration portion 235a formed between the inner surface of these holes and the outer surface of the cell stacks 101 inserted through the lower insulator 227b.

[0032] The lower insulator 227b separates the steam electrolysis chamber 215 from the oxidizing gas supply header 221, preventing the atmosphere around the lower tube sheet 225b from becoming too hot, which would reduce its strength and increase corrosion due to the oxidizing agent contained in the oxidizing gas. In addition, to prevent thermal deformation of the lower tube sheet 225b due to temperature differences when it is exposed to the high temperature inside the steam electrolysis chamber 215, a metal material with high temperature durability, such as a Ni-based alloy, may be used. The lower insulator 227b guides the oxidizing gas supplied to the oxidizing gas supply header 221 through the lower oxidizing gas penetration section 235a to the steam electrolysis chamber 215.

[0033] According to this embodiment, the structure of the cartridge 203 described above causes the generated hydrogen and the oxidizing gas to flow in opposition to each other on the inside and outside of the cell stack 101. As a result, the generated hydrogen that has passed through the inside of the base tube 103 and through the steam electrolysis chamber 215 undergoes heat exchange with the oxidizing gas supplied to the steam electrolysis chamber 215, and is cooled to a temperature at which damage to the lower tube sheet 225b, etc., made of metal material, due to stress is prevented, and then supplied to the generated hydrogen discharge header 219. In addition, the oxidizing gas is heated by heat exchange with the generated hydrogen and supplied to the steam electrolysis chamber 215. As a result, the oxidizing gas heated to the temperature necessary for the electrolytic reaction can be supplied to the steam electrolysis chamber 215 without using a heater or the like.

[0034] Figure 3 schematically shows a configuration in which multiple cell stacks 101 (hereinafter referred to as "cell stack group 101G") provided on the cartridge 203 are heated from the outside. The cell stack group 101G is configured in which multiple cell stacks 101 are densely arranged in parallel, extending in the vertical direction as shown in Figure 2. Here, we will describe the case in which the cell stack group 101G is composed of multiple cylindrical cell stacks, but the cell stack may also be made up of stacked flat cylindrical or plate-shaped cells other than cylindrical ones.

[0035] As shown in Figure 3, the cell stack group 101G is heated by the heating tube (heating section) 3 using the nuclear heat of the high-temperature gas reactor 5. The outer circumference of the cell stack group 101G and the heating tube 3 are spaced apart, and a predetermined space is formed between them.

[0036] The primary helium gas used as a coolant in the high-temperature gas reactor 5 circulates between it and the intermediate heat exchanger 7. Secondary helium gas (heat transfer medium) circulates between the intermediate heat exchanger 7 and the heating tubes 3. Therefore, secondary helium gas heated in the intermediate heat exchanger 7 flows through the heating tubes 3.

[0037] Between the downstream end of the heating tube 3 and the upstream end of the intermediate heat exchanger 7, there is a secondary heat utilization device 9 that further utilizes the heat of the secondary helium gas after it has been used for heat utilization in the heating tube 3, and a helium circulator 11 that circulates the secondary helium gas.

[0038] The high-temperature gas reactor 5 is capable of generating thermal energy of 900°C or higher. Alternatively, a heliostat-type solar thermal concentrator may be used as a heat source instead of the high-temperature gas reactor 5. Furthermore, a heat storage device capable of storing high-temperature heat may also be provided.

[0039] Figure 4 shows an example of a heating tube 3 that heats the outer circumference of a cell stack group 101G. As shown in the figure, the cell stack group 101G is arranged with multiple cell stacks 101 extending vertically so that the outer shape is approximately a rectangular parallelepiped. A single heating tube 3 is provided spirally at a predetermined pitch so as to wind around the outer circumference (four sides in the figure) of the cell stack group 101G. For example, the heat transfer medium (secondary helium gas) flows in from the upper end (one end) 3a and flows out from the lower end (the other end) 3b. The direction of the heat transfer medium flow may be reversed.

[0040] The outer circumference of the cell stack group 101G and the heating tube 3 are spaced apart, and a predetermined space is formed between them. The heating tube 3 is provided between the upper insulator 227a and the lower insulator 227b.

[0041] The cell stack group 101G is heated by radiation through a single spiral heating tube 3 wound around its outer circumference. As a result, part of the heat required for the endothermic electrolytic reaction is supplied from the heating tube 3.

[0042] According to this embodiment, the following effects and advantages are achieved. The cell stack group 101G, which consists of multiple cell stacks 101 arranged in a row, is heated from the outside by a heating tube 3. This allows the entire group of cell stacks 101 to be heated from the outside, simplifying the heating structure and eliminating imbalances in the flow of the heat transfer medium compared to heating each cell stack 101 individually with a heat transfer medium.

[0043] By positioning the heating tube 3 at a predetermined distance from the cell stack group 101G, the cell stack group 101G is heated by radiation. This allows the cell stack group 101G to be heated uniformly.

[0044] By arranging the heating tubes 3 in a spiral pattern around the cell stack group 101G, the cell stack group 101G can be heated efficiently. Furthermore, since the heating section for the entire outer surface of the cartridge can be basically composed of a single heating tube 3, the structure around the cartridge 203 is simplified, and the number of connections with the heat transfer medium (secondary helium gas) circulation system can be minimized.

[0045] Furthermore, this embodiment can be modified as follows. For example, the heating tube 3 can be made into a double or more helical shape, such that there is another helix on the outside of the inner helix. This allows the heating tubes 3 to be arranged more densely, thus enabling more uniform heating of the cell stack group 101G. In this case, the heating tube 3 may be composed of two or more tubes, forming independent heat transfer fluid channels.

[0046] Furthermore, the heating tube 3 may be made into a double or more spiral shape as described above, with the outer spirals positioned between the pitches of the inner spirals. This allows the outer spirals to fill the pitches between the inner spirals, enabling a more uniform supply of radiant heat to the cell stack group.

[0047] [Second Embodiment] Next, a second embodiment of this disclosure will be described with reference to Figure 5. This embodiment differs from the arrangement of the heating tube 3 shown in Figure 4 of the first embodiment. The other configurations are the same as in the first embodiment, so their description will be omitted.

[0048] As shown in Figure 5, the heating tube 3 has a zigzag shape formed in a meandering manner. One heating tube 3 is provided on each of the four sides of the cell stack group 101G.

[0049] The heating tube 3 is formed by repeatedly serpentine units consisting of a first straight section 3c, a second straight section 3d parallel to the first straight section 3c, and a folded section 3e connecting one end of the first straight section 3c and the second straight section 3d within the same plane. The direction in which the first straight section 3c and the second straight section 3d extend is the same as the direction in which the cell stack 101 extends (up and down direction).

[0050] By making the heating tube 3 a zigzag shape in this way, the cell stack group 101G can be heated on a predetermined surface. Furthermore, since the heating tubes 3 are folded in a zigzag pattern and can be arranged on a flat surface, they offer excellent manufacturability and ease of installation, and make it easier to achieve manufacturing accuracy.

[0051] Furthermore, the winding heating tubes 3 do not need to be provided on all four sides of the cell stack group 101G; they only need to be provided on at least one side.

[0052] Furthermore, as shown in the modified example in Figure 6, the direction in which the first linear section 3c and the second linear section 3d extend may be perpendicular to the direction in which the cell stack 101 extends (up and down direction).

[0053] Furthermore, as shown in Figures 7 and 8, two zigzag-shaped heating tubes 3 may be stacked on top of each other. Figure 7 is a side view of a modified zigzag shape shown in Figure 6, and Figure 8 is a plan view thereof. In this case, as explained in the modified spiral heating tube 3 of Figure 4, it is preferable to arrange the outer heating tubes 3-o between the pitches of the inner heating tubes 3-i. This fills the pitch of the inner heating tubes 3-i, allowing for more uniform heating.

[0054] [Third Embodiment] Next, a third embodiment of this disclosure will be described with reference to Figure 9. This embodiment differs from the arrangement of the heating tube 3 shown in Figure 4 of the first embodiment. The other configurations are the same as in the first embodiment, so their description will be omitted.

[0055] As shown in Figure 9, the heating tube 3 has a header shape. Specifically, the heating tube 3 comprises a first header 3f, a second header 3g provided parallel to the first header 3f, and a plurality of heat transfer tubes 3h provided between the first header 3f and the second header 3g, each arranged in parallel. The first header 3f and the second header 3g extend in the vertical direction, and each heat transfer tube 3h extends in a direction perpendicular to the first header 3f and the second header 3g (a direction perpendicular to the cell stack 101). The spacing (pitch) of each heat transfer tube 3h is set to be equal. Both ends of each heat transfer tube 3h are in communication with the first header 3f and the second header 3g, respectively, and for example, heat transfer fluid flows from the first header 3f through each heat transfer tube 3h to the second header 3g. Of course, the reverse flow is also possible. One header-shaped heating tube 3 is provided on each of the four sides of the cell stack group 101G.

[0056] By shaping the heating tube 3 in this manner, the cell stack group 101G can be heated on a predetermined surface. Furthermore, since the heating tubes 3 are arranged in a header shape and can be placed on a flat surface, they offer excellent manufacturability and ease of installation, and it is easier to achieve high manufacturing accuracy.

[0057] Furthermore, the heating tubes 3, which are shaped like headers, do not need to be provided on all four sides of the cell stack group 101G; they only need to be provided on at least one side.

[0058] Furthermore, as shown in the modified example in Figure 10, the first header 3f and the second header 3g may be extended horizontally, and each heat transfer tube 3h may be extended vertically.

[0059] [Fourth Embodiment] Next, a fourth embodiment of this disclosure will be described with reference to Figure 11. This embodiment differs in that it uses a radiant panel 13 instead of the heating tube 3 shown in each of the embodiments described above. The other configurations are the same as in the first embodiment, so their description will be omitted.

[0060] As shown in Figure 11, in this embodiment, a radiant panel 13 is used instead of the heating tube 3 of each of the above embodiments. The radiant panel 13 has a structure in which a high-temperature heat transfer medium flows within the panel and is spaced apart from the cell stack group 101G at a predetermined distance. The radiant panel 13 is provided between the upper insulator 227a and the lower insulator 227b and is provided so as to cover one side of the cell stack group 101G. The radiant panel 13 is provided on the side of the cell stack group 101G.

[0061] As shown in Figure 12, the radiant panel 13 has an inner wall portion 13a and an outer wall portion 13b, and is equipped with a heating channel 13c through which a heating medium flows in the vertical direction. The radiant panel 13 is heated by the heat from the heating medium. The inner wall portion 13a faces the cell stack group 101G. The heating medium flows through the heating channel 13c as indicated by the arrows in the figure. However, the flow of the heating medium may be reversed, or the heating channel may be in the horizontal direction. Alternatively, the structure can incorporate a heat transfer tube through which a heat transfer medium flows, instead of the heating channel 13c. By using a heat transfer tube, the thickness of the inner wall portion 13a can be reduced even when a high-pressure heat transfer medium flows through it.

[0062] According to this embodiment, by using a radiant panel 13 as the heating element, radiant heat can be transmitted more uniformly to the cell stack group 101G.

[0063] Furthermore, since the temperature of the entire surface of the radiant panel 13 is made uniform by heat conduction from the heat transfer tubes, there is less risk of localized heating. In addition, since the radiant panel 13 is integrated as a panel structure, it is easy to attach to the cartridge 203.

[0064] As shown in Figure 13, the heating tube 3 may be formed in a zigzag pattern inside the radiant panel 13 to form a single flow path, resulting in one inlet and one outlet for the heat transfer medium. The direction of the heat transfer medium flow may be from top to bottom, as indicated by the arrows in the figure, or conversely, from bottom to top.

[0065] Alternatively, radiant heat in the rear direction may be suppressed by installing a reflector or insulating material on the back of the radiant panel 13.

[0066] The steam electrolysis apparatus described in each of the embodiments described above can be understood, for example, as follows.

[0067] A steam electrolysis apparatus according to a first aspect of this disclosure comprises a cell stack group (101G) in which a plurality of cell stacks (101) are arranged, each cell stack (101) in which an electrolytic cell (105) consisting of a hydrogen electrode, an electrolyte, and an oxygen electrode is electrically connected via an interconnector, and a heating section (3) provided outside the cell stack group through which a heat transfer medium flows.

[0068] The cell stacks, arranged in a grid, are heated from the outside by a heating element. This allows multiple cell stacks to be heated together from the outside, simplifying the heating structure compared to heating each cell stack individually with a heat transfer medium. It also allows for a more uniform distribution of the heat transfer medium flow.

[0069] In the steam electrolysis apparatus according to a second aspect of the present disclosure, the heating unit (3) is provided at a predetermined distance from the cell stack group (101G) as described in the first aspect.

[0070] By positioning the heating element at a predetermined distance from the cell stack group, the cell stack group is heated by radiation. This allows the cell stack group to be heated uniformly.

[0071] In the third aspect of the present disclosure, the steam electrolysis apparatus, in the second aspect described above, comprises a heating tube (3) through which a heat transfer medium flows.

[0072] By circulating the heat transfer medium through the heating tube, the handling of the heat transfer medium becomes easier.

[0073] In the steam electrolysis apparatus according to the fourth aspect of this disclosure, the heating tube (3) is arranged in a spiral shape so as to surround the cell stack group, as in the third aspect described above.

[0074] By arranging the heating tubes in a spiral pattern around the cell stacks, the cell stacks can be heated efficiently.

[0075] In the steam electrolysis apparatus according to the fifth aspect of this disclosure, in the fourth aspect described above, the heating tube (3) is double-layered, with one heating tube on the outside of the inner heating tube.

[0076] By arranging the heating tubes in a double or double configuration, with one tube on the inside and another on the outside, the heating tubes can be densely packed, thus enabling more efficient heating of the cell stacks.

[0077] In the steam electrolysis apparatus according to the sixth aspect of the present disclosure, the outer heating tubes are arranged between the pitches of the inner heating tubes, as in the fifth aspect described above.

[0078] By positioning the outer heating tubes between the inner heating tubes, the gaps between the inner heating tubes can be filled with the outer heating tubes, allowing for a more effective supply of radiant heat to the cell stack.

[0079] In the steam electrolysis apparatus according to the seventh aspect of the present disclosure, in the third aspect described above, the heating tube (3) has a zigzag shape formed by repeatedly serpentine units consisting of a first straight section (3c), a second straight section (3d) parallel to the first straight section, and a folded section (3e) that connects one end of the first straight section and the second straight section.

[0080] By making the heating section a zigzag shape, the cell stack group can be heated on a predetermined surface.

[0081] In the eighth aspect of the present disclosure, the steam electrolysis apparatus, in the seventh aspect described above, is provided such that the first linear section (3c) and the second linear section (3d) are in the same direction as the steam flowing through the cell stack (101).

[0082] In the steam electrolysis apparatus according to the ninth aspect of this disclosure, the first linear section (3c) and the second linear section (3d) are provided in directions perpendicular to the steam flowing through the cell stack (101).

[0083] In the steam electrolysis apparatus according to the tenth aspect of the present disclosure, in the third aspect described above, the heating tube (3) has a header shape comprising a first header (3f), a second header (3g) provided parallel to the first header, and a plurality of heat transfer tubes (3h) provided between the first header and the second header and arranged in parallel to each other.

[0084] By making the heating section a header shape, the cell stack group can be heated on a predetermined surface.

[0085] In the steam electrolysis apparatus according to the eleventh aspect of this disclosure, in the second aspect described above, the heating section (13) is a radiant panel (13) which is a plate-shaped body through which a heat transfer medium flows.

[0086] By using a plate-shaped radiant panel as the heating element, radiant heat can be transferred more uniformly to the cell stack group.

[0087] A steam electrolysis apparatus according to a twelfth aspect of this disclosure is provided with a reflector or heat insulating material on the back of the radiant panel.

[0088] To prevent the fuel header and external structures located behind the radiant panel from being affected by radiant heating, a reflector or insulating material was installed on the back of the radiant panel.

[0089] In the steam electrolysis apparatus according to the thirteenth aspect of this disclosure, in any of the first to twelfth aspects, the heating section (3, 13) is provided with a plurality of independent heat transfer fluid channels.

[0090] By using a heating section equipped with multiple independent heat transfer fluid channels, the temperature distribution can be precisely controlled.

[0091] In the steam electrolysis apparatus according to the 14th aspect of this disclosure, in any of the first to 13 aspects described above, the heat transfer medium is a fluid in which the coolant of a high-temperature gas furnace (5) is used as the heat source.

[0092] The fluid used as a coolant in high-temperature gas reactors (e.g., helium gas) is kept at a temperature of 800°C or higher (e.g., 900°C). By using this high-temperature fluid, radiant heating can be effectively achieved. [Explanation of Symbols]

[0093] 3 Heating tube (heating part) 3a top edge 3b Bottom edge 3c 1st straight section 3d 2nd straight line 3e Folded section 3f First Header 3g Second Header 3h heat transfer tube 3-i Inner heating tube 3-o Outer heating tube 5. High-temperature gas reactor 7 Intermediate heat exchanger 9 Secondary heat utilization equipment 11. Helium circulator 13. Radiant Panel 13a Inner wall section 13b Outer wall 13c heating channel 101 Cell Stack 101G Cell Stack Group 103 Base tube 105 Electrolytic Cells 107 Interconnector 109 Hydrogen electrode 111 Solid electrolyte membrane 113 Oxygen electrode 117 Lead film 203 Cartridge 215 Steam Electrolysis Room 217 Water vapor supply header 219 Hydrogen-generated emission header 221 Oxidizing gas supply header 223 Oxidizing gas emission header 225a Upper tube plate 225b Lower tube sheet 227a Upper insulation 227b Lower insulation 229a Upper casing 229b Lower casing 231a Steam supply pipe 231b Hydrogen generated discharge pipe 233a Oxidizing gas supply pipe 233b Oxidizing gas exhaust pipe 235a Lower penetration for oxidizing gas 235b Upper penetration for oxidizing gas 237a Upper sealing member 237b Lower sealing member 620 Temperature measurement unit

Claims

1. A group of cell stacks arranged in a row, each consisting of an electrolytic cell comprising a hydrogen electrode, an electrolyte, and an oxygen electrode, which are electrically connected via an interconnector, A heating section is provided on the outside of the aforementioned cell stack group, through which a heat transfer medium flows, A steam electrolysis device equipped with the following features.

2. The steam electrolysis apparatus according to claim 1, wherein the heating unit is provided at a predetermined distance from the cell stack group.

3. The steam electrolysis apparatus according to claim 2, wherein the heating section comprises a heating tube through which a heat transfer medium flows.

4. The steam electrolysis apparatus according to claim 3, wherein the heating tube is arranged in a spiral shape so as to surround the cell stack group.

5. The steam electrolysis apparatus according to claim 3, wherein the heating tube is double-layered, with one heating tube on the outside of the inner heating tube.

6. The steam electrolysis apparatus according to claim 5, wherein the outer heating tubes are arranged between the pitches of the inner heating tubes.

7. The steam electrolytic apparatus according to claim 3, wherein the heating tube has a zigzag shape formed by repeatedly serpentine units consisting of a first straight section, a second straight section parallel to the first straight section, and a folded section connecting one end of the first straight section and the second straight section, within the same plane.

8. The steam electrolysis apparatus according to claim 7, wherein the first linear section and the second linear section are provided in the same direction as the steam flowing through the cell stack.

9. The steam electrolysis apparatus according to claim 7, wherein the first linear section and the second linear section are provided in directions perpendicular to the steam flowing through the cell stack.

10. The steam electrolytic apparatus according to claim 3, wherein the heating tube has a header shape comprising a first header, a second header provided parallel to the first header, and a plurality of heat transfer tubes provided between the first header and the second header, each arranged in parallel.

11. The steam electrolysis apparatus according to claim 2, wherein the heating section is a radiant panel incorporating a heating channel through which a heat transfer medium flows.

12. The steam electrolysis apparatus according to claim 11, wherein a reflector or insulating material is provided on the back of the radiant panel.

13. The steam electrolysis apparatus according to claim 1, wherein the heating section comprises a plurality of independent heat transfer fluid channels.

14. The steam electrolysis apparatus according to any one of claims 1 to 13, wherein the heat transfer medium is a fluid in which the coolant of a high-temperature gas furnace is used as a heat source.

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