Hot module

Abstract

To provide a hot module capable of reducing generation of a low-temperature portion in a stack.SOLUTION: A hot module includes: a laminated body that has a plurality of electrochemical cells, each containing an electrolyte that separates an anode and a cathode, which are stacked and connected in series; stacks that are disposed on both sides in a stacking direction of the electrochemical cells, of the laminated body, and are connected in series with the electrochemical cells, each stack having two terminals of opposite polarity; and electric lines that are connected to connection portions of the terminals and connect the plurality of stacks in series. The hot module also includes a proximity region where a side surface of the stack extending in the stacking direction of the electrochemical cells is located near some part of the electric line, and a distance between the electric line at the proximity region and the side surface is shorter than a distance between the connection portion closest to the proximity region and the side surface at the proximity region.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a hot module including a stack of electrolysis cells. [Background technology]

[0002] A stack, which includes a laminate of multiple electrolytic cells containing an electrolyte that separates the anode and cathode, and terminals connected in series to the electrolytic cells, uses the electrical and thermal energy supplied to the stack to electrolyze fuel gases such as water vapor and carbon dioxide, producing energy carriers such as hydrogen and hydrocarbons. Because the electrolysis of fuel gas is an endothermic reaction, energy is usually supplied to the stack with the goal of reaching a thermal neutral point where the heat generated by Joule heat and the heat absorbed are balanced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2016-538420 Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art disclosed in Patent Document 1, if the amount of energy supplied to the stack is set to the required amount in an attempt to increase the ratio of the energy of carriers generated by the stack to the energy supplied to the stack (energy efficiency), low-temperature areas are more likely to appear in the stack, reducing the amount of energy carriers generated and potentially reducing energy efficiency.

[0005] The present invention has been made to solve this problem, and has as its object to provide a hot module that can reduce the occurrence of low-temperature portions in the stack. [Means for solving the problem]

[0006] A first aspect of a hot module to achieve this objective includes a stack including a stack in which electrolytic cells containing an electrolyte separating an anode and a cathode are stacked and a plurality of the electrolytic cells are connected in series, and two terminals of opposite polarity that are arranged on either side of the stack in the stacking direction of the electrolytic cells and connected in series to the electrolytic cells, and an electric wire that is connected to the connection part of the terminals and connects a plurality of the stacks in series, and includes a proximity part where a side of the stack extending in the stacking direction of the electrolytic cells and a part of the electric wire are located close to each other, and the distance between the electric wire and the side in the proximity part is shorter than the distance between the connection part located closest to the proximity part and the side in the proximity part.

[0007] The second aspect is the first aspect, which includes stacks arranged along the stacking direction of the electrolysis cells, and the adjacent portion includes a part of the electric wire connecting adjacent stacks in the stacking direction of the electrolysis cells.

[0008] In a third aspect, in the second aspect, in stacks arranged in the stacking direction of the electrolytic cells, terminals of opposite polarities are adjacent to each other, and the electric wire including the adjacent portion connects the terminals other than the terminals adjacent to each other in the stacking direction of the electrolytic cells.

[0009] In a fourth aspect, in the second aspect, in the stacks arranged in the stacking direction of the electrolysis cells, terminals of the same polarity are adjacent to each other.

[0010] A fifth aspect is any one of the second to fourth aspects, wherein the terminals are not on the same straight line extending in the stacking direction of the electrolysis cell.

[0011] In a sixth aspect, in any one of the first to fifth aspects, the electric wire has an electrical resistance per unit length of the proximal portion equal to or greater than the electrical resistance per unit length of the portion other than the proximal portion. [Effects of the Invention]

[0012] According to the present invention, a portion of the electric wire is located close to a side surface of the stack extending in the stacking direction of the electrolysis cell. The distance between the electric wire and the side surface at the close portion is shorter than the distance between the connection portion located closest to the close portion and the side surface at the close portion, so that Joule heat from the electric wire is transferred to the side surface of the stack at the close portion, heating the stack. This reduces the occurrence of low-temperature portions in the stack. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a block diagram of a hot module according to the first embodiment. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. 1 is a cross-sectional view of an electrolysis cell. [Figure 5] FIG. 3 is a side view of the stack group as seen from the direction of arrow V in FIG. 2. [Figure 6] FIG. 6 is an enlarged side view of the stack group of the portion surrounded by VI in FIG. 5. [Figure 7] FIG. 10 is a perspective view of a stack group of hot modules in a second embodiment. [Figure 8] FIG. 8 is a side view of the stack group as seen from the direction of arrow VIII in FIG. 7. [Figure 9] FIG. 9 is an enlarged side view of the stack group of the portion surrounded by IX in FIG. 8. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a block diagram of a hot module 10 in a first embodiment. The hot module 10 is a device that electrolyzes fuel gases such as steam and carbon dioxide to produce energy carriers such as hydrogen and hydrocarbons. Hot modules 10 include those that are capable of reversible operation between producing energy carriers and operating as a fuel cell that generates electricity from the energy carriers. In this embodiment, a hot module 10 that electrolyzes steam to produce hydrogen is illustrated.

[0015] The hot module 10 includes a stack group 11 that performs electrolysis, a vaporizer 12 that generates steam that is supplied to the cathode chamber 51 of the stack group 11, a heat exchanger 13 that exchanges heat between the gas supplied to the stack group 11 and the gas generated by the stack group 11, and a heater 14 that heats the stack group 11. To reduce heat radiation, the hot module 10 has the stack group 11, the vaporizer 12, the heat exchanger 13, and the heater 14 arranged inside a thermal insulation material 15. Heat-resistant fibers such as ceramic wool, RCF, and AES fill the gaps between the stack group 11, the vaporizer 12, the heat exchanger 13, and the heater 14.

[0016] The vaporizer 12 includes a heat exchanger that exchanges heat with the high-temperature gas containing oxygen produced by the stack group 11, and heats water to produce steam. The steam produced by the vaporizer 12 contains hydrogen, which reduces oxidation of the catalyst contained in the cathode 47 (see Figure 4). The hydrogen-containing steam exchanges heat with the hydrogen and oxygen produced by the stack group 11 in the heat exchanger 13, is heated to the operating temperature of the stack group 11 by the heater 14, and is supplied to the cathode chamber 51 of the stack group 11. The air exchanges heat with the hydrogen and oxygen produced by the stack group 11 in the heat exchanger 13, is heated to the operating temperature of the stack group 11 by the heater 14, and is supplied to the anode chamber 53 of the stack group 11. The condenser 16 is a device that cools the hydrogen gas, and the liquefied water is supplied to the vaporizer 12 as raw water.

[0017] 2 is a perspective view of the stack group 11. The stack group 11 includes stacks 17, 18, 19, and 20 installed on a rack (not shown). In this embodiment, as an example, the stack group 11 will be described in which four stacks are arranged vertically, but the number of stacks arranged vertically is not limited to this, and is set appropriately depending on the required amount of energy carriers to be generated.

[0018] The stacks 17, 18, 19, and 20 are spaced apart from one another. Each stack 17, 18, 19, and 20 has an anode terminal 21 and a cathode terminal 23. The anode terminals 21 of the stacks 17, 18, 19, and 20 are arranged on the same straight line L1, and the cathode terminals 23 of the stacks 17, 18, 19, and 20 are arranged on the same straight line L2 that is different from the straight line L1. The straight line L2 is a straight line parallel to the straight line L1. In other words, the terminals 21 and 23 are not on the same straight line. The positive pole of a power supply is connected to the connection portion 22 of the terminal 21 of the stack 17, and the negative pole of the power supply is connected to the connection portion 24 of the terminal 23 of the stack 20.

[0019] Electric wire 25 connects connection portion 24 of terminal 23 of stack 17 to connection portion 22 of terminal 21 of stack 19. Electric wire 26 connects connection portion 22 of terminal 21 of stack 18 to connection portion 24 of terminal 23 of stack 19. Electric wire 27 connects connection portion 24 of terminal 23 of stack 18 to connection portion 22 of terminal 21 of stack 20. Electric wires 25, 26, 27 connect stacks 17, 18, 19, 20 in series. Because terminals 21, 23 are not on the same straight line, it is easy to arrange electric wires 25, 26, 27 connecting terminals 21, 23 while avoiding terminals 21, 23.

[0020] 3 is a perspective view of stack 17. Stacks 17, 18, 19, and 20 have the same structure although they are installed at different positions on the rack. Therefore, the structure of stack 17 will be described below, and descriptions of the structures of stacks 18, 19, and 20 will be omitted. Stack 17 includes a stack 29 in which reaction units 28 are stacked in the thickness direction, conductors 30 and 31 arranged on both sides of the reaction units 28 in the stacking direction and electrically connected to stack 29, and end plates 32 and 33 that sandwich stack 29 and conductors 30 and 31 in the thickness direction. Stack 29 is made by stacking, for example, approximately 10 to 30 reaction units 28.

[0021] A terminal 21 is provided on the conductor 30, and a terminal 23 is provided on the conductor 31. The conductors 30, 31 and the terminals 21, 23 may be made of stainless steel, for example. An insulator 34 is disposed between the end plate 32 and the conductor 30, and an insulator 35 is disposed between the end plate 33 and the conductor 31.

[0022] Bolts 36 are arranged at the four corners of the periphery of the stack 17, penetrating the laminate 29, the conductors 30, 31, the insulators 34, 35, and the end plates 32, 33 in the thickness direction. The laminate 29, the conductors 30, 31, the insulators 34, 35, and the end plates 32, 33 are fastened together by the bolts 36.

[0023] Four spaces penetrating the periphery of the stack 17 in the thickness direction function as a passage 37a through which gas enters a cathode chamber 51 (described later) of a reaction unit 28 from outside the stack 17, a passage 37b through which gas exits from the cathode chamber 51 to outside the stack 17, a passage 38b through which gas enters an anode chamber 53 (described later) of a reaction unit 28 from outside the stack 17, and a passage 38a through which gas exits from the anode chamber 53 to outside the stack 17. The stack 17 fastened with bolts 36 includes side surfaces 39 extending in the stacking direction of the reaction units 28 and end surfaces 40 located at both ends of the stacking direction of the reaction units 28.

[0024] Figure 4 is an exploded view of the stack 17 taken along line IV-IV in Figure 3, passing through passages 37a and 37b. Figure 4 is a cross-sectional view taken along line IV-IV, with the components constituting one reaction unit 28 separated in the thickness direction. The thickness of each part is exaggerated in Figure 4. The reaction unit 28 includes, in order in the thickness direction, an interconnector 41, a cathode frame 42, a cell 43 with separators, and an anode frame 44.

[0025] The separator-equipped cell 43 includes an electrolytic cell 45 and a separator 49 disposed in an electrolyte 46 of the electrolytic cell 45. Holes (passages 37a, 37b) penetrate the interconnector 41, the cathode frame 42, the separator 49, and the anode frame 44.

[0026] The electrolytic cell 45 includes an electrolyte 46, and a cathode 47 and an anode 48 separated by the electrolyte 46. The material of the electrolyte 46 is a solid oxide, and examples thereof include stabilized zirconia, a ceria-based solid solution, and a solid solution of alumina with one or more selected from stabilized zirconia and a ceria-based solid solution. Examples of stabilizers for stabilized zirconia include CaO, MgO, YO, ScO, and YbO. Examples of elements that dissolve in ceria in the ceria-based solid solution include Gd, Sm, and Y.

[0027] Examples of the material for the cathode 47 include a material containing a catalyst containing Ni and zirconia with Y dissolved therein, and a material containing a catalyst containing Ni and ceria with Gd dissolved therein. Examples of the catalyst include Ni, Ni-based alloys, and cermet, which is a composite (sintered body) of NiO and an oxide (solid electrolyte).

[0028] The material of the anode 48 is a perovskite oxide, La 1-X Sr X MnO 3-δ ,La 1-X Sr X CoO 3-δ ,La 1-X Sr X Co 1-Y Fe Y O 3-δ ,Pr 1-X Sr X MnO 3-δ is exemplified.

[0029] The separator 49 is a frame-shaped member provided with an opening larger than the anode 48. The separator 49 is made of, for example, stainless steel. The separator 49 is airtightly joined to the electrolyte 46 with brazing material or the like, avoiding the anode 48.

[0030] The interconnectors 41 are conductive plate-like members arranged on both sides in the thickness direction of the electrolytic cell 45. The interconnectors 41 electrically connect the reaction units 28 adjacent to each other in the thickness direction. An example of the material of the interconnectors 41 is stainless steel.

[0031] The cathode frame 42 is a rectangular frame-shaped member disposed between the interconnector 41 and the separator 49. The cathode frame 42 is made of, for example, stainless steel. The cathode frame 42 surrounds the electrolytic cell 45 and a current collector 50 provided in the center of the interconnector 41.

[0032] The current collector 50 electrically connects the cathode 47 and the interconnector 41. The material of the current collector 50 is, for example, a porous body made of a gas-permeable metal such as Ni. A cathode chamber 51 surrounded by the interconnector 41 and the separator-equipped cell 43 is provided inside the cathode frame 42.

[0033] The anode frame 44 is a frame-shaped member disposed between the interconnector 41 and the separator 49. The material of the anode frame 44 is, for example, an insulator such as mica. The anode frame 44 surrounds a current collector 52 provided in the center of the interconnector 41. The current collector 52 electrically connects the anode 48 and the interconnector 41. In this embodiment, the current collector 52 is formed integrally with the interconnector 41, but this is not limitative. It is of course possible for the current collector 52 to be a member separate from the interconnector 41.

[0034] An anode chamber 53 surrounded by an interconnector 41 and a separator-equipped cell 43 is provided inside the anode frame 44. A separator 49 separates the cathode chamber 51 from the anode chamber 53, preventing the fuel gas in the cathode chamber 51 from mixing with the oxidizer gas (oxygen, air, etc.) in the anode chamber 53. Examples of fuel gas include water vapor, carbon dioxide, and a mixture thereof.

[0035] Returning to Figure 3, an interconnector 41 that contacts an anode chamber 53 (see Figure 4) contacts a conductor 30 provided with terminal 21, and an interconnector 41 that contacts a cathode chamber 51 contacts a conductor 31 provided with terminal 23. Terminals 21 and 23 protrude from one of four side surfaces 39 of stack 17, which has a substantially rectangular parallelepiped shape.

[0036] Pipes (not shown) through which gas flows are connected to the passages 37a, 37b, 38a, and 38b, respectively. The fuel gas that enters the passage 37a from the pipe passes through the cathode chambers 51 (see FIG. 4) provided in the respective reaction units 28, and then passes through passage 37b to exit the stack 17. The oxidant gas that enters the passage 38b from the pipe passes through the anode chambers 53 provided in the respective reaction units 28, and then passes through passage 38a to exit the stack 17.

[0037] When the positive electrode of the power supply is connected to terminal 21 and the negative electrode of the power supply is connected to terminal 23, electrons flow toward the cathode 47 of the electrolytic cell 45 (see FIG. 4). The fuel gas that enters the cathode chamber 51 is reduced at the cathode 47. Because electrons are taken away at the anode 48 of the electrolytic cell 45, oxide ions that have moved to the anode 48 via the electrolyte 46 are oxidized at the anode 48. As a result, energy carriers such as hydrogen and hydrocarbons are synthesized in the electrolytic cell 45.

[0038] Because the electrolysis of water vapor, carbon dioxide, and the like contained in the fuel gas is an endothermic reaction, the temperature of the electrolytic cell 45 (the temperature of the exhaust gas flowing through the passages 37b and 38a) decreases as the current density increases, compared to the temperature at the open circuit voltage of the electrolytic cell 45 when current begins to flow (the average voltage of the electrolytic cell 45 when the current density is 0). As the current density increases further, the temperature of the electrolytic cell 45 begins to rise due to Joule heat, and the temperature reaches a thermal neutral point where endothermic and exothermic reactions are balanced. When the current density of the reaction unit 28 becomes lower than the current density of the reaction unit 28 at the thermal neutral point, endothermic reaction in the reaction unit 28 becomes dominant, and the temperature decreases. When the current density of the reaction unit 28 becomes higher than the current density of the reaction unit 28 at the thermal neutral point, exothermic reaction in the reaction unit 28 becomes dominant, and the temperature increases.

[0039] Because the Joule heat of the conductors 30 and 31 is greater than the Joule heat of the reaction units 28, the Joule heat of the conductors 30 and 31 is transmitted to the stack 29, and the temperature of the center of the stack 29 in the stacking direction of the reaction units 28 tends to be lower than the temperature of both ends in the stacking direction. Furthermore, because the Joule heat of the conductors 30 and 31 near the terminals 21 and 23 is greater than the Joule heat of the portions of the conductors 30 and 31 away from the terminals 21 and 23, the temperature of the portions of the side surface 39 of the stack 17 where the terminals 21 and 23 are not provided tends to be lower than the temperature of the portions where the terminals 21 and 23 are provided. This tendency becomes more pronounced as the current flowing through the stack 17 decreases. Because the higher the temperature of the electrolytic cell 45, the more active the synthesis of energy carriers becomes. Therefore, in order to activate the synthesis of energy carriers, it is preferable to reduce the occurrence of low-temperature portions of the stack 17 and reduce temperature unevenness in the stack 17.

[0040] Figure 5 is a side view of the stack groups 11 and 11a. The stack group 11a includes stacks 17, 18, 19, and 20 installed in a rack (not shown). In each of the stack groups 11 and 11a, the stacks 17, 18, 19, and 20 are arranged in the stacking direction (vertical direction in Figure 5) of the electrolytic cells 45 (see Figure 4). The stack groups 11 and 11a are adjacent to each other in a direction intersecting the stacking direction of the electrolytic cells 45. The side surface 39 of the stack group 11 on which the terminals 21 and 23 are provided faces the opposite side surface 39 of the stack group 11a on which the terminals 21 and 23 are provided.

[0041] In the stack groups 11, 11a, stacks 17, 18 are arranged in the stacking direction of the electrolytic cells 45, with terminals 21, 23 of opposite polarities adjacent to each other. Similarly, stacks 18, 19 are arranged in the stacking direction of the electrolytic cells 45, with terminals 21, 23 of opposite polarities adjacent to each other, and stacks 19, 20 are arranged in the stacking direction of the electrolytic cells 45, with terminals 21, 23 of opposite polarities adjacent to each other.

[0042] 6 is a side view of the stack group 11, 11a, enlarging the area surrounded by VI in FIG. 5. The stack group 11, 11a includes a proximity portion 54 where the side surface 39 of the stack 18 and a portion of the electric wires 25, 26 are located close to each other. The proximity portion 54 is a portion where the distance D2 between the electric wires 25, 26 and the side surface 39 is shorter than the distance D1 between the connection portion 22 located closest to the proximity portion 54 and the side surface 39. Joule heat of the electric wires 25, 26 in the proximity portion 54 is transferred to the proximity portion 54 of the side surface 39 of the stack 18, heating the side surface 39 of the stack 18. This reduces the occurrence of low-temperature portions of the stack 18.

[0043] In the proximity portion 54, the electric wires 25, 26 may be in contact with the side surface 39 of the stack 18 (D2=0), or may be spaced apart from the side surface 39. The electric wires 25, 26 are covered with an insulating coating, so that even if the electric wires 25, 26 come into contact with the stack 18, problems such as a short circuit can be prevented.

[0044] In stack 18, the temperature of the portion of side surface 39 of stack 18 where terminals 21, 23 are not provided tends to be lower than the temperature of the portion where terminals 21, 23 are provided. In contrast, proximity portion 54 is provided in the portion of side surface 39 of stack 18 where terminals 21, 23 are not provided, which further reduces the occurrence of low-temperature portions of stack 18.

[0045] In stack 18, the temperature at the center of stack 29 (see FIG. 3) in the stacking direction of reaction units 28 tends to be lower than the temperature at both ends in the stacking direction. In contrast, proximity portion 54 is provided in the portion of side surface 39 of stack 18 between terminal 21 and terminal 23 (the center of stack 29), which further reduces the occurrence of low-temperature portions in stack 18.

[0046] It is preferable that the electrical resistance per unit length of the proximal portion 54 of the electric wire 25 is equal to or greater than the electrical resistance per unit length of the portions other than the proximal portion 54, because this allows for greater Joule heat of the electric wire 25 in the proximal portion 54. Examples of means for increasing the electrical resistance per unit length of the electric wire 25 include making the proximal portion 54 of the electric wire 25 thinner than the portions other than the proximal portion 54 of the electric wire 25, and disposing in the proximal portion 54 a material whose resistivity is higher than the portions other than the proximal portion 54 of the electric wire 25.

[0047] Returning to FIG. 5 , the stack groups 11 and 11a further include proximity portions 55, 56, and 57. In the proximity portion 55, the distance between the electric wire 25 and the side surface 39 of the stack 17 is shorter than the distance between the connection portion 24 located closest to the proximity portion 55 and the side surface 39. In the proximity portion 56, the distance between the electric wires 26 and 27 and the side surface 39 of the stack 19 is shorter than the distance between the connection portion 24 located closest to the proximity portion 56 and the side surface 39. In the proximity portion 57, the distance between the electric wire 27 and the side surface 39 of the stack 20 is shorter than the distance between the connection portion 22 located closest to the proximity portion 57 and the side surface 39. The proximity portion 55 can heat the side surface 39 of the stack 17, the proximity portion 56 can heat the side surface 39 of the stack 19, and the proximity portion 57 can heat the side surface 39 of the stack 20.

[0048] The electric wire 25 connected to the terminal 23 of the stack 17 is connected to the terminal 21 of the stack 19 adjacent to the stack 18, not to the terminal 21 of the stack 18 adjacent to the stack 17. Compared to when the electric wire 25 connects the terminals 21, 23 of the adjacent stacks 17, 18, the electric wire 25 can be made longer, thereby increasing the Joule heat of the electric wire 25. Therefore, the heating effect of the stacks 17, 18 by the adjacent portions 54, 55 can be increased.

[0049] The electric wire 27 connected to the terminal 23 of the stack 18 is connected to the terminal 21 of the stack 20 adjacent to the stack 19, not to the terminal 21 of the stack 19 adjacent to the stack 18. Compared to when the electric wire 27 connects the terminals 21, 23 of the adjacent stacks 18, 19, the electric wire 27 can be made longer, thereby increasing the Joule heat of the electric wire 27. Therefore, the heating effect of the stacks 19, 20 by the adjacent portions 56, 57 can be increased.

[0050] A second embodiment will be described with reference to Figures 7 to 9. In the first embodiment, stacks 17, 18, 19, and 20 were described in which terminals 21 and 23 of opposite polarities were arranged adjacent to each other. In contrast, in the second embodiment, stacks 61, 62, and 63 will be described in which terminals 21 and 23 of the same polarity are arranged adjacent to each other. Parts that are the same as those described in the first embodiment are given the same reference numerals, and the following description will be omitted.

[0051] 7 is a perspective view of a stack group 60 of a hot module 10 in the second embodiment. The stack group 60 includes stacks 61, 62, and 63 installed in a rack (not shown). In this embodiment, as an example, a stack group 60 in which three stacks are arranged vertically will be described, but the present invention is not limited to this, and the number of stacks arranged vertically is set appropriately depending on the required amount of energy carriers to be generated.

[0052] The stacks 61, 62, and 63 are arranged spaced apart from one another. Each of the stacks 61, 62, and 63 has an anode terminal 21 and a cathode terminal 23. The anode terminals 21 of the stacks 61, 62, and 63 are arranged on the same straight line L1, and the cathode terminals 23 are arranged on the same straight line L2 that is different from the line L1. The terminals 21 and 23 are not on the same straight line. The positive pole of a power supply is connected to the connection portion 22 of the terminal 21 of the stack 61, and the negative pole of the power supply is connected to the connection portion 24 of the terminal 23 of the stack 63.

[0053] In the stack group 60, stacks 61 and 62 are arranged in the stacking direction (vertical direction in FIG. 7) of the electrolytic cells 45 (see FIG. 4) with terminals 23 of the same polarity adjacent to each other. Similarly, stacks 62 and 63 are arranged in the stacking direction of the electrolytic cells 45 with terminals 21 of the same polarity adjacent to each other.

[0054] The stacks 61 and 63 have the same structure as the stack 17 (see FIG. 3). In the stack 62, the laminate 29 is provided so that the interconnector 41 in contact with the cathode chamber 51 of the reaction unit 28 (see FIG. 4) is in contact with the conductor 31 (see FIG. 3) provided with the terminal 21. In the stacks 61 and 63, the laminate 29 is provided so that the interconnector 41 in contact with the cathode chamber 51 of the reaction unit 28 is in contact with the conductor 31 provided with the terminal 23, and in this respect, the stack 62 differs from the stacks 61 and 63 in structure.

[0055] Electric wire 64 connects connection portion 24 of terminal 23 of stack 61 to connection portion 22 of terminal 21 of stack 62. Electric wire 65 connects connection portion 24 of terminal 23 of stack 62 to connection portion 22 of terminal 21 of stack 63. Electric wires 64, 65 connect stacks 61, 62, 63 in series. Because terminals 21, 23 are not on the same straight line, it is easy to arrange electric wires 64, 65 connecting terminals 21, 23 while avoiding terminals 21, 23.

[0056] 8 is a side view of stack groups 60, 60a. The stack group 60a includes stacks 61, 62, and 63 installed in a rack (not shown). In each of the stack groups 60, 60a, the stacks 61, 62, and 63 are arranged in the stacking direction (vertical direction in FIG. 5) of the electrolytic cells 45 (see FIG. 4). The stack groups 60, 60a are adjacent to each other in a direction intersecting the stacking direction of the electrolytic cells 45. The side surface 39 of the stack group 60 on which the terminals 21 and 23 are provided faces the opposite side surface 39 of the stack group 60a on which the terminals 21 and 23 are provided.

[0057] 9 is a side view of the stack group 60, 60a, enlarging the area surrounded by IX in FIG. 8. The stack group 60, 60a includes a proximity portion 66 where the side surface 39 of the stack 62 and parts of the electric wires 64, 65 are located close to each other. The proximity portion 66 is a portion where the distance D2 between the electric wires 64, 65 and the side surface 39 is shorter than the distance D1 between the connection portion 24 located closest to the proximity portion 66 and the side surface 39. Joule heat of the electric wires 64, 65 in the proximity portion 66 is transferred to the proximity portion 66 of the side surface 39 of the stack 62, thereby reducing the occurrence of low-temperature portions of the stack 62.

[0058] At the proximity portion 66, the electric wires 64, 65 may be in contact with or separated from the side surface 39 of the stack 62. Because the proximity portion 66 is provided in a portion of the side surface 39 of the stack 62 where the terminals 21, 23 are not provided, the occurrence of low-temperature portions in the stack 62 can be further reduced. Moreover, because the proximity portion 66 is provided in a portion of the side surface 39 of the stack 62 between the terminals 21 and 23 (the center portion of the laminate 29), the occurrence of low-temperature portions in the stack 62 can be further reduced. It is preferable that the electric resistance per unit length of the proximity portion 66 of the electric wires 64, 65 is equal to or greater than the electric resistance per unit length of the portions other than the proximity portion 66, because this allows for greater Joule heat generation of the electric wires 64, 65 at the proximity portion 66.

[0059] Returning to Fig. 8, the stack groups 60, 60a further include proximity portions 67, 68. In the proximity portion 67, the distance between the electric wire 64 and the side surface 39 of the stack 61 is shorter than the distance between the connection portion 24 located closest to the proximity portion 67 and the side surface 39. In the proximity portion 68, the distance between the electric wire 65 and the side surface 39 of the stack 63 is shorter than the distance between the connection portion 22 located closest to the proximity portion 68 and the side surface 39. The proximity portion 67 can heat the side surface 39 of the stack 61, and the proximity portion 68 can heat the side surface 39 of the stack 63.

[0060] In the stack group 60, stacks 61, 62, and 63 are arranged side by side in the stacking direction of the electrolytic cells 45, with terminals 21 and 23 of the same polarity arranged side by side, and an electric wire 64 connects the terminal 23 of stack 61 to the terminal 21 of stack 62, and an electric wire 65 connects the terminal 23 of stack 62 to the terminal 21 of stack 63. Compared to a case where an electric wire connects the terminals 21 and 23 of stacks 61, 62, and 63 arranged side by side with terminals 23 of opposite polarities, the electric wires 64 and 65 can be made longer while minimizing the increase in the space in which the electric wires 64 and 65 are arranged, thereby increasing the Joule heat of the electric wires 64 and 65. This increases the heating effect of the stacks 61, 62, and 63 by the adjacent portions 66, 67, and 68.

[0061] The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention.

[0062] The electric wires 25, 26, 27, 64, and 65 described in the embodiments may be soft flexible wires or hard wires (conductive plates) with a predetermined shape.

[0063] In the embodiment, the Joule heat of the electric wires 25, 26, and 27 of the stack group 11 is used to heat the stacks 17, 18, 19, and 20 of the stack group 11a adjacent to the stack group 11, and the Joule heat of the electric wires 64 and 65 of the stack group 60 is used to heat the stacks 61, 62, and 63 of the stack group 60a adjacent to the stack group 60, but this is not necessarily limited to this. It is of course possible to heat the stacks 17, 18, 19, and 20 of the stack group 11 using the Joule heat of the electric wires 25, 26, and 27 of the stack group 11. It is also of course possible to heat the stacks 61, 62, and 63 of the stack group 60 using the Joule heat of the electric wires 64 and 65 of the stack group 60.

[0064] In the embodiment, the case where the surface of the side surface 39 of the stack 17, 18, 19, 20, 61, 62, 63 opposite to the surface on which the terminals 21, 23 are provided has been described, but this is not necessarily limited to this. In the stacks 17, 18, 19, 20, 61, 62, 63, the temperature at the center in the stacking direction of the reaction units 28 of the stack 29 tends to be lower than the temperatures at both ends in the stacking direction. Therefore, for example, a portion between the terminals 21 and 23 on the surface of the side surface 39 on which the terminals 21, 23 are provided may be heated using Joule heat. Furthermore, it is naturally possible to heat the surface of the side surface 39 on which the terminals 21, 23 are not provided, not just the surface opposite to the surface on which the terminals 21, 23 are provided.

[0065] In the embodiment, the terminals 21, 23 are provided on one of the side surfaces 39 (four surfaces) of the stacks 17, 18, 19, 20, 61, 62, 63, but this is not necessarily limited to this. Of course, it is possible to provide the terminal 21 on one of the side surfaces 39 (four surfaces) and the terminal 23 on another surface. It is also possible to arrange the terminals 21, 23 so that they are on the same straight line extending in the stacking direction of the electrolytic cell 45.

[0066] In the above embodiments, the stacks 17, 18, 19, 20, 61, 62, and 63 have a flat cell design. The flat cell stacks 17, 18, 19, 20, 61, 62, and 63 may be electrode-supported or electrolyte-supported. They may also be metal-supported (metal-supported flat cell) stacks in which the cathode, anode, and electrolyte are supported by a porous metal such as an Fe-Cr-based metal.

[0067] In the embodiment, the electrolytic cell 45 has a rectangular shape, but this is not necessarily limited to this. The shape of the electrolytic cell 45 may be circular or elliptical, or may be polygonal other than a rectangular shape, such as a triangle or pentagon.

[0068] In the embodiment, the case where the electrolyte 46 having oxide ion conductivity is used has been described, but this is not necessarily limited to this. It is of course possible to use an electrolyte 46 that has proton conductivity under the operating conditions of the electrolytic cell 45. Examples of substances that exhibit proton conductivity under the operating conditions of the electrolytic cell 45 include perovskite-type oxides such as SrZrO3 and BaZrO3, in which the B site is substituted with a trivalent metal ion such as Y or In, pyrochlore-type oxides, and phosphates.

[0069] In the above embodiment, the gas passages 37a, 37b, 38a, and 38b are built into the stacks 17, 18, 19, 20, 61, 62, and 63, but this is not necessarily limited to this. It is also possible to connect manifolds serving as the gas passages 37a, 37b, 38a, and 38b to the electrolysis cell and provide them outside the electrolysis cell. Examples of materials for the manifolds include ceramics with high high-temperature strength.

[0070] In the embodiment, the conductors 30 and 31 provided with the terminals 21 and 23 are arranged in the stacks 17, 18, 19, 20, 61, 62, and 63, but this is not necessarily limited to this. It is of course possible to omit the conductors 30 and 31 and the insulators 34 and 35, electrically connect the reaction units 28 to the end plates 32 and 33, and use the end plates 32 and 33 as terminals for the stacks 17, 18, 19, 20, 61, 62, and 63. [Explanation of symbols]

[0071] 10 Hot Modules 17,18,19,20,61,62,63 stacks 21 terminals 22 Connection 23 terminals 24 Connection 25,26,27,64,65 Electric wire 29 Laminate 39 Side 45 Electrolysis Cell 46 Electrolytes 47 Cathode 48 Anode 54, 55, 56, 57, 66, 67, 68 Proximal area D1,D2 distance L1,L2 straight line

Claims

1. a stack of electrolytic cells each containing an electrolyte separating an anode from a cathode, the electrolytic cells being stacked and connected in series; a stack including two terminals of opposite polarities arranged on both sides of the electrolysis cell in the stacking direction of the stack and connected in series to the electrolysis cell; and an electric wire connected to the connection portion of the terminal and connecting a plurality of the stacks in series, a proximity portion where a side surface of the stack extending in a stacking direction of the electrolysis cell and a part of the electric wire are located close to each other; A hot module in which the distance between the wire and the side surface in the proximity portion is shorter than the distance between the connection portion located closest to the proximity portion and the side surface in the proximity portion.

2. the stacks are arranged along a stacking direction of the electrolysis cells, The hot module according to claim 1 , wherein the adjacent portion includes a part of the electric wire connecting the stacks adjacent to each other in the stacking direction of the electrolysis cells.

3. In the stacks arranged in the stacking direction of the electrolysis cells, the terminals of different polarities are adjacent to each other, The hot module according to claim 2 , wherein the electric wire including the adjacent portion connects the terminals other than the terminals adjacent to each other in the stacking direction of the electrolysis cells.

4. The hot module according to claim 2 , wherein the stacks arranged in the stacking direction of the electrolytic cells have the terminals of the same polarity adjacent to each other.

5. 5. The hot module according to claim 2, wherein the terminals are not on the same line extending in the stacking direction of the electrolytic cells.

6. 5. The hot module according to claim 1, wherein the electrical resistance per unit length of the adjacent portion of the electric wire is equal to or greater than the electrical resistance per unit length of the portion other than the adjacent portion.

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