Electrolytic cell stack and electrolytic device

Abstract

It suppresses gas leakage from the electrolytic cell stack. [Solution] The electrolytic cell stack comprises a laminate containing multiple electrolytic cells, fasteners provided penetrating the laminate in a first direction for fixing the multiple electrolytic cells, and a flow path provided in contact with the fasteners for the cooling fluid to flow in contact with the fasteners. The temperature of the cooling fluid is lower than the operating temperature of the electrolytic cell stack.

Description

Technical Field

[0001] Embodiments of the present invention relate to an electrolytic cell stack and an electrolysis apparatus.

Background Art

[0002] Electrolytic cells such as solid oxide type electrochemical cells are being developed as fuel cells for power generation, electrolysis apparatuses for hydrogen production, and power storage systems combining these. Since solid oxide type electrochemical cells use solid oxides as electrolytes, for example, they are operated at a high operating temperature (operating temperature) of 600°C or higher and 1000°C or lower, and a large reaction rate can be obtained without using expensive noble metal catalysts. Therefore, when this is operated as a solid oxide type fuel cell (SOFC), high power generation efficiency can be obtained, and when it is operated as a solid oxide type electrolytic cell (SOEC), hydrogen can be produced with high efficiency at a low electrolysis voltage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to suppress gas leakage from the electrolytic cell stack. <​​​​​​​​​​

[0006] [Figure 1] This is a schematic diagram showing an example of the structure of an electrolytic cell stack in an electrolytic device. [Figure 2] This is a schematic diagram showing an example of the structure of an electrolytic cell stack in an electrolytic device. [Figure 3] This is a schematic diagram showing an example of a laminated structure. [Figure 4] This is a schematic diagram illustrating an example of a fastener. [Figure 5] This is a schematic diagram illustrating the first embodiment of the electrolytic device. [Figure 6] This is a schematic diagram illustrating a second embodiment of the electrolytic device. [Figure 7A] This is a schematic diagram illustrating a second embodiment of the electrolytic device. [Figure 7B] This is a schematic diagram illustrating a second embodiment of the electrolytic device. [Figure 8] This is a schematic diagram illustrating a third embodiment of the electrolytic device. [Figure 9] This is a schematic diagram illustrating the thermal deformation of an electrolytic cell stack. [Figure 10] This is a schematic diagram illustrating a fourth embodiment of the electrolytic device. [Figure 11] This is a schematic diagram illustrating a first modified example of the fourth embodiment of the electrolytic device. [Figure 12] This is a schematic diagram illustrating a second modified example of the fourth embodiment of the electrolytic device. [Figure 13] This is a schematic diagram illustrating a third modified example of the fourth embodiment of the electrolytic device. [Modes for carrying out the invention]

[0007] The embodiments will be described below with reference to the drawings. In each of the embodiments shown below, substantially identical components are denoted by the same reference numerals, and their descriptions may be partially omitted. The drawings are schematic, and the relationship between thickness and planar dimensions, the ratio of the thickness of each part, etc., may differ from those in reality.

[0008] In this specification, unless otherwise specified, "connect" may include not only direct connections but also indirect connections.

[0009] (Example of an electrolytic device structure) Figures 1 and 2 are schematic diagrams showing examples of the structure of an electrolytic cell stack in an electrolytic device. Figure 1 is a schematic side view showing an example of the structure of an electrolytic cell stack 10. Figure 2 is a schematic top view showing an example of the structure of an electrolytic cell stack 10.

[0010] The electrolytic cell stack 10 performs an electrolytic reaction using a gas supplied from outside the electrolytic cell stack 10 (supply gas) and can discharge the gas produced by the electrolytic reaction (generated gas). The supply gas is supplied from a gas supply source outside the electrolytic cell stack 10 and contains, for example, water vapor, carbon dioxide gas, and hydrogen gas. The generated gas contains, for example, carbon monoxide gas and hydrogen gas. The electrolytic cell stack 10 comprises a laminate 1, a lower clamping plate 2, an upper clamping plate 3, and a fastener 4.

[0011] The laminate 1 has a plurality of electrolytic cells. The laminate 1 is provided between the lower clamping plate 2 and the upper clamping plate 3. The lower clamping plate 2 is provided, for example, at the lower end of the laminate 1. The upper clamping plate 3 is provided, for example, at the upper end of the laminate 1. The lower clamping plate 2 and the upper clamping plate 3 are, for example, metal plates. The metal plates are conductors. Examples of metal plates include stainless steel (SUS) and nickel (Ni) alloy.

[0012] Figure 3 is a schematic diagram showing an example of the structure of the laminate 1. The laminate 1 has solid oxide electrochemical cells 11. Figure 3 shows a planar stack having a plurality of solid oxide electrochemical cells 11. The laminate 1 is not limited to a planar stack, and may be, for example, a cylindrical stack. The solid oxide electrochemical cells 11 are planar electrochemical cells and fuel electrode-supported cells. The solid oxide electrochemical cells 11 are connected to a power source that can supply voltage or current for carrying out electrolytic reactions, for example.

[0013] The solid oxide type electrochemical cell 11 can be operated at high temperatures, and the electrolysis reaction is carried out, for example, at a temperature of 600°C or higher and 1000°C or lower. The solid oxide type electrochemical cell 11 may be provided, for example, in a heater, and the temperature may be adjusted by a heater that heats the solid oxide type electrochemical cell 11. The solid oxide type electrochemical cell 11 may be provided in an electric furnace that can control the temperature of the solid oxide type electrochemical cell 11.

[0014] A plurality of solid oxide type electrochemical cells 11 are stacked in sequence. The solid oxide type electrochemical cell 11 includes an air electrode 101, an electrolyte 102, a fuel electrode 103, and a support 104.

[0015] The electrolysis reaction by the electrolysis cell stack 10 is carried out, for example, as follows. Gases such as carbon dioxide gas, water vapor, and hydrogen gas are supplied to the fuel electrode 103 side. By the electrolysis reaction at the fuel electrode 103, for example, hydrogen gas can be generated from water vapor, and carbon monoxide gas can be generated from carbon dioxide gas. Gases such as carbon dioxide gas, water vapor, hydrogen gas, and carbon monoxide gas are discharged from the fuel electrode 103 side.

[0016] Gases such as air are supplied to the air electrode 101 side. The air is supplied, for example, to purge oxygen generated during electrolysis. Oxygen can be generated by the electrolysis reaction at the air electrode 101. Air having an oxygen concentration higher than the oxygen concentration in the atmosphere is discharged from the air electrode 101 side.

[0017] The air electrode 101 has, for example, a porous electric conductor. Examples of the porous electric conductor include perovskite type oxides and the like.

[0018] The air electrode 101 further comprises, for example, a catalyst that promotes the electrolytic reaction contained in the generated gas. The catalyst comprises, for example, at least one of the following elements: platinum (Pt), ruthenium (Ru), cerium (Ce), lanthanum (La), cobalt (Co), nickel (Ni), aluminum (Al), and copper (Cu). The catalyst is supported, for example, on the surface of an electrical conductor. The catalyst may also constitute a catalyst layer provided on the surface of the electrical conductor.

[0019] The electrolyte 102 has, for example, an ion conductor that does not conduct electricity. Examples of ion conductors include solid oxides such as stabilized zirconia, perovskite-type oxides, and molded ceria-based solid solutions.

[0020] The fuel electrode 103 has, for example, a porous electrical conductor. Examples of porous electrical conductors include mixed sintered bodies of metal and solid oxides (cermets). Examples of mixed sintered bodies include yttria-stabilized zirconia and scandia-stabilized zirconia.

[0021] The electrolytic cell stack 10 can isolate the atmospheres of adjacent solid oxide electrochemical cells 11, for example, by a separator 121. Furthermore, the atmospheres of the fuel electrode 103 and air electrode 101 of the same solid oxide electrochemical cell 11 can be isolated by providing a partition plate 122 on the dense electrolyte 102 of the solid oxide electrochemical cell 11. The solid oxide electrochemical cell 11 may further have a sealing material 123 between the partition plate 122 and the separator 121. The electrolytic cell stack 10 may further have a plurality of gas channels on the outer periphery of the solid oxide electrochemical cell 11 that penetrate along the stacking direction of the solid oxide electrochemical cell 11. One of the gas channels constitutes a channel for the raw material gas supplied to the fuel electrode 103 and air electrode 101, respectively, and for the reaction product gas generated by the fuel electrode 103 and air electrode 101. Another of the gas channels may be connected to piping, for example.

[0022] To generate a large amount of electricity and hydrogen, an electrolytic cell stack 10 is formed by stacking multiple solid oxide type electrochemical cells 11. For example, in the case of a flat-plate type electrolytic cell, the electrolytic cell stack 10 is formed by stacking multiple flat-plate type electrolytic cells, supplying different gases to the air electrode 101 and fuel electrode 103 of each electrolytic cell, and having a structure that allows the electrolytic cells to be electrically connected in series.

[0023] The fastener 4 can fasten the laminate 1, the lower fastening plate 2, and the upper fastening plate 3. Figures 1 and 2 show multiple fasteners 4. The multiple fasteners 4 are arranged along the periphery of the upper surface of the upper fastening plate 3, for example, as shown in Figure 2.

[0024] Examples of fasteners 4 include metal fasteners. Fasteners 4 are compression mechanisms (connectors) such as a combination of bolts and nuts or a spring. The electrolytic cell stack 10 is subjected to compressive force in the stacking direction by the lower fastening plate 2 and upper fastening plate 3, which are positioned above and below the laminate 1, sealing the electrolytic cell stack 10 in particular to prevent hydrogen generated by the electrolytic reaction from leaking to the outside of the electrolytic cell stack 10.

[0025] Figure 4 is a schematic diagram illustrating an example of the structure of the fastener 4. Figure 4 shows an example of the cross-sectional structure (cross-sectional structure in the thickness direction of the electrolytic cell stack 10) at line segment A1-A2 of the electrolytic cell stack 10 shown in Figure 2.

[0026] The fastener 4 comprises a bolt 4a and a nut 4b. The bolt 4a is provided in the opening 5. The bolt 4a penetrates the laminate 1, the lower fastening plate 2, and the upper fastening plate 3 through the opening 5 in the thickness direction of the laminate 1 (the stacking direction of the multiple solid oxide type electrochemical cells 11). The bolt 4a is secured by multiple nuts 4b provided on the outside of the lower fastening plate 2 and the outside of the upper fastening plate 3. The electrolytic cell stack 10 has a gap S between the outer circumferential surface (side surface) of the bolt 4a and the inner circumferential surface (inner wall) of the opening 5. The bolt 4a and nut 4b are made of metal and contain metallic elements such as stainless steel (SUS) or Ni alloy. The shape of the bolt 4a and nut 4b is not particularly limited to the shape shown in Figure 4.

[0027] A system with increased capacity achieved by connecting multiple electrolytic cell stacks 10 in series or parallel is called a module. Multiple electrolytic cell stacks 10 are arranged within the module. Modules using solid oxide electrochemical cells are installed in heating furnaces such as electric furnaces to operate in high-temperature environments. The supply gas to the air electrode 101 and fuel electrode 103 passes through the heating furnace and is supplied into the electrolytic cell stacks 10 from piping or the ends of the electrolytic cell stacks 10.

[0028] When the electrolytic cell stack 10 is operated for electrolysis purposes rather than power generation, it is important to recover the generated hydrogen without leaking it outside the electrolytic cell stack 10 or the electrolysis device.

[0029] Since fasteners 4, such as bolts and springs, are used in high-temperature environments, if the fasteners 4 are made of metal, the axial force decreases due to the relaxation of the fasteners 4. To counteract this, it is conceivable to suppress the decrease in axial force by making the fasteners 4 from ceramics, but due to the strength limitations of ceramic materials, it is not possible to apply a sufficient load to the fasteners 4. When the fastening force is impaired due to the decrease in axial force, it leads to deterioration of the contact condition of each component inside the electrolytic cell stack 10 and gas leakage from the electrolytic cell stack 10, causing a decrease in the performance and deterioration of the electrolytic cell stack 10.

[0030] In contrast, the electrolytic apparatus of the embodiment has a cooling channel through which a cooling fluid flows to cool the fastener 4. An example of an electrolytic cell stack 10 having a cooling channel will be described further below.

[0031] (First embodiment) Figure 5 is a schematic diagram illustrating the first embodiment of the electrolytic device. Figure 5 shows an example of the cross-sectional structure (cross-sectional structure in the thickness direction of the electrolytic cell stack 10) at line segment A1-A2 of the electrolytic cell stack 10 shown in Figure 2. The following explanation will describe the parts that differ from the electrolytic cell stack 10 shown in Figure 4, and for other parts, the explanation in Figure 4 can be appropriately referred to.

[0032] The electrolytic cell stack 10 of the first embodiment further comprises an opening 6 in addition to the components of the electrolytic cell stack 10 shown in Figures 1 and 4.

[0033] The opening 6 forms a cooling channel through which the cooling fluid flows. The opening 6 is provided by passing through the bolt 4a in the thickness direction of the laminate 1. The opening 6 is, for example, a through hole extending through the central axis of the bolt 4a. In other words, the opening 6 forms a hollow structure of the bolt 4a. The arrows in Figure 5 show examples of the direction in which the cooling fluid flows. The cooling fluid flows, for example, from the upper end to the lower end of the opening 6. It is not limited to this, and may also flow from the lower end to the upper end of the opening 6. The opening 6 can be formed, for example, using known machining methods before or after the lamination of each element constituting the electrolytic cell stack 10.

[0034] The temperature of the cooling fluid supplied to the electrolytic cell stack 10 is preferably lower than the operating temperature of the electrolytic cell stack 10. The operating temperature of the electrolytic cell stack 10 is, for example, 600°C to 1000°C. The temperature range of the cooling fluid is, for example, 400°C to 700°C. However, the temperature range of the cooling fluid is not limited to the above range.

[0035] As the cooling fluid passes through the inside of the bolt 4a (opening 6), it cools the outer surface of the bolt 4a through heat transfer from the bolt 4a. Since the electrolytic cell stack 10 is installed, for example, inside a heating furnace, the heat absorption from the electrolytic cell stack 10 and the sides of the bolt 4a, along with the thermal balance of the cooling fluid, results in a lower temperature in the center of the bolt 4a and a higher temperature at the ends of the bolt 4a. As a result, the temperature of the bolt 4a is lower than the operating temperature.

[0036] The heat transfer coefficient of the cooling fluid varies depending on the thermal conductivity and viscosity coefficient of the working fluid (cooling fluid) within the operating temperature range of the electrolytic cell stack 10. It is also possible to supply a gas with a high cooling effect as the cooling fluid. Examples of cooling fluids include gases, including air. The cooling fluid is not limited to gases and may also be a liquid. From the viewpoint of system efficiency, it is simplest and most preferable to use air, which is commonly used in solid oxide type cell stacks, as the cooling fluid.

[0037] By cooling the fastener 4 with a cooling fluid, the relaxation of the fastener 4 can be suppressed. This allows, for example, a metal fastener 4 to be applied to the electrolytic cell stack 10 in a high-temperature environment, and suppresses, for example, the decrease in axial force over time due to creep deformation of the fastener 4. Therefore, gas leakage from the electrolytic cell stack 10 can be suppressed.

[0038] (Second embodiment) Figures 6, 7A, and 7B are schematic diagrams illustrating a second embodiment of the electrolytic device. Figure 6 shows an example of the cross-sectional structure of the electrolytic cell stack 10 shown in Figure 2 along line segment A1-A2. Figure 7A shows a partial example of the cross-sectional structure of the electrolytic cell stack 10 shown in Figure 6 along line segment A1-A2. The following describes the differences from the electrolytic cell stack 10 shown in Figure 4, and for other parts, the explanation in Figure 4 can be appropriately referred to. The solid arrows shown in Figures 6, 7A, and 7B show examples of the direction in which the cooling fluid flows.

[0039] The electrolytic cell stack 10 of the second embodiment further comprises an opening 6 in addition to the configuration of the electrolytic cell stack 10 shown in Figures 1 and 4.

[0040] Opening 6 is connected to opening 5. Cooling fluid is supplied from opening 6 to opening 5. Opening 6, together with opening 5, forms a cooling channel through which the cooling fluid flows. Figure 6 shows an example in which opening 6 extends inside the upper clamping plate 3 and connects the outside of the electrolytic cell stack 10 to opening 5, but is not limited to this, and opening 6 may be provided to extend inside the lower clamping plate 2 and connect the outside of the electrolytic cell stack 10 to opening 5. Opening 6 can be formed, for example, using known machining methods before or after stacking each element constituting the electrolytic cell stack 10.

[0041] Similar to the first embodiment, by lowering the temperature of the cooling fluid supplied to the electrolytic cell stack 10 to below the operating temperature of the electrolytic cell stack 10, the cooling fluid flows into the gap S and cools the outer surface of the bolt 4a by heat transfer. The bolt 4a is cooled from the outer surface facing the opening 5, and the upper and lower ends of the bolt 4a absorb heat from heating. Due to this thermal balance, the ends of the bolt 4a are hotter and the center of the bolt 4a is cooler. For example, if the cooling fluid is supplied from the upper clamping plate 3, the cooling fluid flows from the top to the bottom of the gap S. In Figures 6 and 7A, the opening 6 extends in a direction perpendicular to the central axis of the bolt 4a, but is not limited to this.

[0042] It is preferable that the opening 6 extends in a direction that does not intersect the central axis of the bolt 4a. It is preferable that the cooling fluid from the opening 6 is supplied not toward the central axis of the bolt 4a, as shown in Figure 7B, but toward a position eccentric to the outer diameter side of the bolt 4a from the central axis of the bolt 4a, as shown in Figure 7A. If the opening 6 extends in a direction that intersects the central axis of the bolt 4a, only a portion of the outer surface of the bolt 4a will be cooled, and the temperature will be uneven between the above-mentioned region R1 of the opening 6 and the other portion R2 on the opposite side, as shown in Figure 7B, for example, the temperature of region R2 will be higher than the temperature of region R1. In contrast, as shown in Figure 7A, by offsetting the opening 6 toward the outer diameter side of the bolt 4a from the central axis of the bolt 4a, the cooling fluid can flow from the top to the bottom of the opening 5 while swirling or spiraling, thereby cooling the bolt 4a more uniformly throughout the entire opening 5.

[0043] By cooling the fastener 4 with a cooling fluid, the relaxation of the fastener 4 can be suppressed. This allows, for example, a metal fastener 4 to be applied to the electrolytic cell stack 10 in a high-temperature environment, and suppresses, for example, the decrease in axial force over time due to creep deformation of the fastener 4. Therefore, gas leakage from the electrolytic cell stack 10 can be suppressed.

[0044] (Third embodiment) Figure 8 is a schematic diagram illustrating a third embodiment of the electrolytic device. Figure 8 is a schematic side view showing an example of the structure of the electrolytic cell stack 10. The following describes the differences from the electrolytic cell stack 10 shown in Figure 1, and for other parts, the explanation in Figure 1 can be appropriately referred to.

[0045] The electrolytic cell stack 10 of the third embodiment further comprises a plastic member 7 and a plastic member 8, in addition to the configuration of the electrolytic cell stack 10 shown in Figure 1. The electrolytic cell stack 10 of the third embodiment further comprises the opening 6 in the first or second embodiment.

[0046] The plastic member 7 is positioned between the laminate 1 and the lower clamping plate 2. The plastic member 7 may be in contact with the lower end of the laminate 1 and the upper surface of the lower clamping plate 2. The plastic member 8 is positioned between the laminate 1 and the upper clamping plate 3. The plastic member 8 may be in contact with the upper end of the laminate 1 and the lower surface of the upper clamping plate 3. The electrolytic cell stack 10 may have at least one of the plastic member 7 and the plastic member 8.

[0047] The plastic members 7 and 8 can be formed from a deformation-absorbing member that loses thickness and collapses under compression. The deformation-absorbing member is made of a material that can be used in high-temperature environments such as the operating temperature range of the electrolytic cell stack 10, and is, for example, vermiculite.

[0048] Figure 9 is a schematic diagram illustrating the thermal deformation of the electrolytic cell stack 10. Similar to Figure 1, Figure 9 shows the laminate 1, the lower clamping plate 2, the upper clamping plate 3, and the fastener 4. For example, when the fastener 4 is cooled with a cooling fluid, a temperature difference is created between the cooled area and the other areas, causing deformation such that the central part of the cross-section in the thickness direction of the electrolytic cell stack 10 bulges, as shown in Figure 9. This deformation increases the compressive force in the central part of the cross-section and decreases the compressive force at the ends of the cross-section. When the compressive force at the ends decreases, gas inside the electrolytic cell stack 10 is more likely to leak out, and leakage of hydrogen produced during the electrolytic reaction, in particular, directly adversely affects the electrolytic performance.

[0049] In contrast, as shown in Figure 8, by laminating deformation-absorbing members such as the plastic member 7 and the plastic member 8, the plastic member 7 and the plastic member 8 deform in response to the temperature difference, thereby eliminating the uneven load distribution between the center and the edges of the cross-section in the thickness direction of the laminate 1. Therefore, gas leakage from the electrolytic cell stack 10 can be suppressed.

[0050] (Fourth embodiment) Figure 10 is a schematic diagram illustrating a fourth embodiment of the electrolytic apparatus. Figure 10 shows the electrolytic apparatus 100.

[0051] The electrolytic apparatus 100 includes an electrolytic cell stack 10, a heat exchanger 20, and a heating furnace 30. The arrows shown in Figure 10 indicate the direction in which each gas flows.

[0052] The heat exchanger 20 is one of the heaters that can raise the temperature of the supply gas. Figure 10 shows multiple heat exchangers 20, namely heat exchanger 20_n (where n is a natural number), heat exchanger 20_n+1, and heat exchanger 20_n+2, but the number of heat exchangers 20 is not particularly limited as long as it is one or more.

[0053] The heat exchanger 20_n may be located, for example, outside the heating furnace 30. The heat exchanger 20_n is supplied with a supply gas via a pipe P1 connected to its inlet, and the generated gas is discharged via a pipe P2 connected to its outlet. The gas discharged from the heat exchanger 20_n may contain air included in the supply gas.

[0054] The heat exchanger 20_n+1 may be located, for example, outside the heating furnace 30. The heat exchanger 20_n+1 is connected in series with the heat exchanger 20_n. The heat exchanger 20_n+1 is supplied with a supply gas (the gas produced from the heat exchanger 20_n) via a pipe P2 connected to the inlet of the heat exchanger 20_n+1, and the gas produced is discharged via a pipe P3 connected to the outlet of the heat exchanger 20_n+1. The gas discharged from the heat exchanger 20_n+1 may contain air included in the supply gas. The temperature of the gas discharged from the heat exchanger 20_n+1 is higher than the temperature of the gas discharged from the heat exchanger 20_n.

[0055] The heat exchanger 20_n+2 may be installed, for example, outside the heating furnace 30. The heat exchanger 20_n+2 is connected in series with the heat exchanger 20_n+1. The heat exchanger 20_n+2 is supplied with a supply gas (generated gas from the heat exchanger 20_n+1) via a pipe P3 connected to the inlet of the heat exchanger 20_n+2, and the generated gas is discharged via a pipe P4 connected to the outlet of the heat exchanger 20_n+2. The gas discharged from the heat exchanger 20_n+2 may contain air contained in the supply gas. The temperature of the gas discharged from the heat exchanger 20_n+2 is higher than the temperature of the gas discharged from the heat exchanger 20_n+1. The pipe P4 connects the outlet of the heat exchanger 20_n+2 to the flow path to which the supply gas for the electrolytic cell stack 10 is supplied.

[0056] The electrolytic cell stack 10 is supplied with a supply gas (generated gas from the heat exchanger 20_n+2) via a pipe P4 connected to the outlet of the heat exchanger 20_n+2, for example, and the generated gas is discharged via a pipe P5 connected to the outlet of the electrolytic cell stack 10. The gas discharged from the electrolytic cell stack 10 may contain air included in the supply gas. The pipe P5 may extend from the inside to the outside of the heating furnace 30.

[0057] The electrolytic cell stack 10 is supplied with a cooling fluid, for example, via a pipe P3a that branches off from pipe P3 outside the heating furnace 30. The cooling fluid is the gas discharged from the heat exchanger 20_n+1. Pipe P3a connects pipe P3 to the cooling channel of the electrolytic cell stack 10.

[0058] The electrolytic cell stack 10 has a structure similar to that of the electrolytic cell stack 10 in any of the first to third embodiments. The heating furnace 30 only needs to house at least one electrolytic cell stack 10, and may house multiple electrolytic cell stacks 10.

[0059] In the electrolytic apparatus 100, it is generally difficult to raise the temperature of the air or other gas supplied to the electrolytic cell stack 10 in a single step, and the temperature is raised by multiple heat exchanges using multiple heat exchangers 20, for example. Also, since the electrolytic cell stack 10 is located inside the heating furnace 30, the temperature of the supplied gas rises to near the temperature of the heating furnace 30 through heat absorption (heat transfer) from radiant heat and convective heat from the heating furnace 30, even in the piping P4 inside the heating furnace 30 that supplies the gas to the electrolytic cell stack 10 located inside the heating furnace 30. If we assume that the heating structure up to heat exchanger 20_n+1 is called a low-temperature preheating furnace, and the heating structure from heat exchanger 20_n+2 or from heat exchanger 20_n+2 to the electrolytic cell stack 10 is called a high-temperature preheating furnace, then the cooling fluid passes only through the low-temperature preheating furnace and is supplied to the electrolytic cell stack 10 without passing through the high-temperature preheating furnace.

[0060] Furthermore, by cooling the fastener 4 with the cooling fluid supplied to the electrolytic cell stack 10, similar to the first or second embodiment, relaxation of the fastener 4 can be suppressed. This allows, for example, a metal fastener 4 to be applied to the electrolytic cell stack 10 in a high-temperature environment, and suppresses, for example, the decrease in axial force over time due to creep deformation of the fastener 4. Thus, gas leakage from the electrolytic cell stack 10 can be suppressed.

[0061] Figure 11 is a schematic diagram illustrating the first modification of the fourth embodiment of the electrolytic apparatus. Figure 11 shows the electrolytic apparatus 100. The electrolytic apparatus 100 includes an electrolytic cell stack 10, a heat exchanger 20, and a heating furnace 30. The first modification differs from the fourth embodiment in that it does not include a heat exchanger 20_n+2 and piping P4. The parts that differ from the fourth embodiment will be described below, and the description of the fourth embodiment can be appropriately referenced for other parts. The arrows shown in Figure 11 indicate the direction in which each gas flows.

[0062] As shown in Figure 11, for example, if the low-temperature preheating furnace consists of heat exchangers 20_n and 20_n+1, and the high-temperature preheating furnace is pipe P3 within the heating furnace 30, it is preferable that pipe P3, which is the high-temperature preheating furnace, is designed to have a longer gas path than pipe P3a within the heating furnace 30, so that the temperature of the supply gas rises sufficiently above the temperature of the cooling fluid. Alternatively, by bypassing this gas path, the supply gas can be supplied to the electrolytic cell stack 10 as a cooling fluid via pipe P3a.

[0063] Furthermore, by cooling the fastener 4 with the cooling fluid supplied to the electrolytic cell stack 10, similar to the first or second embodiment, relaxation of the fastener 4 can be suppressed. This allows, for example, a metal fastener 4 to be applied to the electrolytic cell stack 10 in a high-temperature environment, and suppresses, for example, the decrease in axial force over time due to creep deformation of the fastener 4. Thus, gas leakage from the electrolytic cell stack 10 can be suppressed.

[0064] Figure 12 is a schematic diagram illustrating a second modification of the fourth embodiment of the electrolytic apparatus. Figure 12 shows the electrolytic apparatus 100. The electrolytic apparatus 100 includes an electrolytic cell stack 10, a heat exchanger 20, and a heating furnace 30. The second modification differs from the fourth embodiment in that heat exchangers 20_n+1 and 20_n+2 are housed in the heating furnace 30. The parts that differ from the fourth embodiment will be described below, and for other parts, the description of the fourth embodiment can be appropriately referenced. The arrows shown in Figure 12 indicate the direction in which each gas flows.

[0065] Similarly, when heat exchangers 20_n+1 and 20_n+2 are housed in the heating furnace 30, the heating structure up to heat exchanger 20_n+1 is called a low-temperature preheating furnace, and the heating structure from heat exchanger 20_n+2 or from heat exchanger 20_n+2 to the electrolytic cell stack 10 is called a high-temperature preheating furnace. In this case, the cooling fluid passes only through the low-temperature preheating furnace and is supplied to the electrolytic cell stack 10 without passing through the high-temperature preheating furnace.

[0066] Furthermore, by cooling the fastener 4 with the cooling fluid supplied to the electrolytic cell stack 10, similar to the first or second embodiment, relaxation of the fastener 4 can be suppressed. This allows, for example, a metal fastener 4 to be applied to the electrolytic cell stack 10 in a high-temperature environment, and suppresses, for example, the decrease in axial force over time due to creep deformation of the fastener 4. Thus, gas leakage from the electrolytic cell stack 10 can be suppressed.

[0067] Figure 13 is a schematic diagram illustrating a third modification of the fourth embodiment of the electrolytic apparatus. Figure 11 shows the electrolytic apparatus 100. The electrolytic apparatus 100 includes an electrolytic cell stack 10, a heat exchanger 20, and a heating furnace 30. The third modification differs from the fourth embodiment in that it has piping P5a. The parts that differ from the fourth embodiment will be described below, and for other parts, the description of the fourth embodiment can be appropriately referenced. The arrows shown in Figure 13 indicate the direction in which each gas flows.

[0068] Piping P5a branches off from piping P5 outside the heating furnace 30 and is supplied with cooling fluid. Piping P5a connects piping P5 to the cooling channel of the electrolytic cell stack 10. The cooling fluid is, for example, the gas discharged from the electrolytic cell stack 10 inside the heating furnace 30. As in the fourth embodiment, the electrolytic device 100 may also have piping P3a. However, it is not limited to this, and the electrolytic device 100 may not have piping P3a. Furthermore, the gas discharged from the electrolytic cell stack 10 may be cooled via a cooler (not shown) and then supplied to the electrolytic cell stack 10 as cooling fluid. Pumps may also be provided in the middle of each pipe.

[0069] A third modification involves a gas containing air discharged from the outlet of the electrolytic cell stack 10, which can be used as a cooling fluid by, for example, repressurizing the gas after its temperature has dropped following discharge and circulating it back into the electrolytic cell stack 10.

[0070] Furthermore, by cooling the fastener 4 with the cooling fluid supplied to the electrolytic cell stack 10, similar to the first or second embodiment, relaxation of the fastener 4 can be suppressed. This allows, for example, a metal fastener 4 to be applied to the electrolytic cell stack 10 in a high-temperature environment, and suppresses, for example, the decrease in axial force over time due to creep deformation of the fastener 4. Thus, gas leakage from the electrolytic cell stack 10 can be suppressed.

[0071] The first to fourth embodiments can be combined as appropriate.

[0072] Although several embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0073] 1...Laminate, 2...Lower clamping plate, 3...Upper clamping plate, 4...Fastener, 4a...Bolt, 4b...Nut, 5...Opening, 6...Opening, 7...Polyplastic member, 8...Polyplastic member, 10...Electrolytic cell stack, 11...Solid oxide type electrochemical cell, 20...Heat exchanger, 30...Heating furnace, 100...Electrolytic device, 101...Air electrode, 102...Electrolyte, 103...Fuel electrode, 104...Support, 121...Separator, 122...Plate, 123...Sealing material, A1-A2...Line segment, P1...Piping, P2...Piping, P3...Piping, P3a...Piping, P4...Piping, P5...Piping, P5a...Piping, S...Gap

Claims

1. A laminate containing multiple electrolytic cells, A fastener is provided that penetrates the laminate in the first direction and secures the plurality of electrolytic cells, A passage is provided in contact with the fastener, through which a cooling fluid flows in contact with the fastener, An electrolytic cell stack comprising, The temperature of the cooling fluid is lower than the operating temperature of the electrolytic cell stack. Electrolytic cell stack.

2. The electrolytic cell stack has a first opening that penetrates the laminate in the first direction, The fastener has a bolt that penetrates the electrolytic cell stack through the first opening, The bolt has a second opening that penetrates the bolt in the first direction and forms the flow path. The electrolytic cell stack according to claim 1.

3. The electrolytic cell stack has a first opening that penetrates the laminate in the first direction, The fastener has a bolt that penetrates the electrolytic cell stack through the first opening, The electrolytic cell stack is provided between the outer circumferential surface of the bolt and the inner circumferential surface of the first opening and has a gap that forms the flow path. The electrolytic cell stack according to claim 1.

4. The aforementioned electrolytic cell stack is A first clamping plate provided at the lower part of the laminate, A second clamping plate is provided on the upper part of the laminate, Furthermore, it is equipped with, The first clamping plate or the second clamping plate connects the outside of the electrolytic cell stack to the first opening and has a second opening through which the cooling fluid flows. The electrolytic cell stack according to claim 3.

5. The second opening extends inside the first or second clamping plate in a second direction that does not intersect with the central axis of the bolt. The electrolytic cell stack according to claim 4.

6. The aforementioned electrolytic cell stack is A first clamping plate provided at the lower part of the laminate, A second clamping plate is provided on the upper part of the laminate, A plastic member selected from the group consisting of a first plastic member disposed between the laminate and the first clamping plate, and a second plastic member disposed between the laminate and the second clamping plate, It further possesses, The electrolytic cell stack according to claim 1.

7. A heating furnace and The electrolytic cell stack according to any one of claims 1 to 6, disposed inside the heating furnace, At least one heat exchanger located inside or outside the heating furnace, A first pipe through which a first gas containing air flows, supplied from at least one heat exchanger to the electrolytic cell stack, A second pipe that branches off from the first pipe and through which the branched first gas supplied from the first pipe to the electrolytic cell stack flows, It is equipped with, The temperature of the branched first gas supplied to the electrolytic cell stack via the second piping is lower than the temperature of the first gas supplied to the electrolytic cell stack via the first piping. Electrolyzer.

8. A heating furnace and The electrolytic cell stack according to any one of claims 1 to 6 is arranged inside the heating furnace, At least one heat exchanger located inside or outside the heating furnace, A first pipe through which a first gas containing air flows, supplied from at least one heat exchanger to the electrolytic cell stack, A third pipe through which a second gas, which is discharged from the electrolytic cell stack and contains air, flows, A fourth pipe, which branches off from the third pipe outside the heating furnace and through which the branched second gas supplied from the third pipe to the electrolytic cell stack flows, It is equipped with, The temperature of the branched second gas supplied to the electrolytic cell stack via the fourth pipe is lower than the temperature of the second gas discharged from the electrolytic cell stack via the third pipe. Electrolyzer.

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