Electrolytic module and electrolytic device

Abstract

To provide an electrolytic module and an electrolytic device which are capable of reducing variation in temperature.SOLUTION: An electrolysis module includes arrayed electrolytic cells, each containing elements that include an electrolyte isolating two electrodes, and the elements are electrically connected in series. When the electrolytic cells are divided into a peripheral portion on an outer periphery of the group of the arrayed electrolytic cells, and a central portion surrounded by the peripheral portion, an average of the area of the elements included in the electrolytic cells in the peripheral portion is smaller than an average of the area of the elements included in the electrolytic cells in the central portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrolysis module in which electrolysis cells are arranged, and an electrolysis device. [Background technology]

[0002] An electrolysis module, which is an arrangement of electrolysis cells in which an element part containing an electrolyte that separates two electrodes is arranged, electrolyzes fuel gas in the element part to which a voltage is applied, and synthesizes energy carriers such as hydrogen and hydrocarbons (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-72892 A Summary of the Invention [Problem to be solved by the invention]

[0004] An electrolytic cell to which a voltage is applied to the element portion has a problem in that the heat dissipation from the center of the electrolytic cell assembly is less than the heat dissipation from the peripheral portion located around the center, so that the temperature in the center is likely to rise, and temperature variations that affect the durability of the electrolytic cell are likely to occur.

[0005] The present invention has been made to solve this problem, and has an object to provide an electrolysis module and an electrolysis device that can reduce temperature variation. [Means for solving the problem]

[0006] A first aspect for achieving this object is an electrolysis module including an electrolysis cell in which an element portion containing an electrolyte separating two electrodes is arranged, the electrolysis cells being arranged and the element portions being electrically connected in series, wherein when the electrolysis cell is partitioned into an outer periphery portion located on the outer periphery of the set of arranged electrolysis cells and a central portion surrounded by the outer periphery portion, the average area of ​​the element portions included in the electrolysis cells in the outer periphery portion is smaller than the average area of ​​the element portions included in the electrolysis cells in the central portion.

[0007] In a second embodiment, in the first embodiment, the average area of ​​the element portions included in the electrolytic cell in the peripheral portion is 40% or more of the average area of ​​the element portions included in the electrolytic cell in the central portion.

[0008] In a third aspect, in the first or second aspect, the average area of ​​the element portions included in the electrolytic cell in the outer periphery is 97% or less of the average area of ​​the element portions included in the electrolytic cell in the central portion.

[0009] A fourth aspect includes an electrolysis module according to any one of the first to third aspects, a power source that supplies current to a circuit connected to the electrodes, and an adjustment unit that adjusts the output of the power source, wherein the adjustment unit sets an average voltage of the central portion to a voltage lower than a thermal neutral point where heat absorption and heat generation are balanced in the electrolysis module set to a predetermined temperature, and sets an average voltage of the peripheral portion to a voltage higher than the thermal neutral point. Effect of the Invention

[0010] According to the present invention, when the electrolytic cell is divided into an outer periphery located on the outer periphery of the set of arranged electrolytic cells and a central portion surrounded by the outer periphery, the average area of ​​the element portions included in the electrolytic cells in the outer periphery is smaller than the average area of ​​the element portions included in the electrolytic cells in the central portion. Since the element portions are connected in series, the same current flows in the outer periphery and the central portion, and the current density of the element portions in the central portion can be made smaller than the current density of the element portions in the outer periphery. Since the Joule heat in the central portion can be made smaller than the Joule heat in the outer periphery, the temperature rise in the central portion, which dissipates less heat than the outer periphery, can be reduced, and the temperature variation in the electrolytic cells can be reduced. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of an electrolysis module according to a first embodiment. [Diagram 2] FIG. 1 is a cross-sectional view of an electrolysis cell. [Diagram 3] 1 is a graph showing current-voltage characteristics and heat generation characteristics of an electrolysis module. [Figure 4] FIG. 2 is a plan view of the electrolysis module. [Diagram 5] FIG. 1 is a block diagram of an electrolysis device. [Figure 6] FIG. 11 is a plan view of an electrolysis module according to a second embodiment. [Figure 7] FIG. 1 is a perspective view of an electrolysis cell. [Figure 8] FIG. 13 is a side view of the electrolysis module according to the third embodiment. [Figure 9] FIG. 9 is a cross-sectional view of the electrolysis module taken along line IX-IX in FIG. [Figure 10] FIG. 13 is a perspective view of an electrolysis module according to a fourth embodiment. [Figure 11] FIG. 2 is an exploded view of the electrolysis cell. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a perspective view of an electrolysis module 10 in a first embodiment. The electrolysis module 10 includes a plurality of electrolysis cells 11. The electrolysis cells 11 have element sections 13 arranged on a breathable support 12. The electrolysis module 10 includes a manifold 14 connected to one end of the support 12, and a manifold 15 connected to the other end of the support 12. The electrolysis cells 11 are arranged between the manifolds 14 and 15. In this embodiment, 20 electrolysis cells 11 are arranged at intervals from each other in three rows.

[0013] FIG. 2 is a cross-sectional view of the electrolysis cell 11. The support 12 is provided with a plurality of cavities 16 with a circular cross section that connect the manifolds 14 and 15. An element unit 13 is provided on each of the outer surfaces (front and back) of the support 12. The support 12 has air permeability between the outer surface of the support 12 and the cavities 16. The element unit 13 includes, in order from the outer surface of the support 12, a fuel electrode 17, an electrolyte 18, and a cathode 19. In FIG. 2, the thickness of the element unit 13 is exaggerated. In this embodiment, the electrolysis cell 11 is a flattened cylindrical horizontal stripe electrolysis cell in which the element units 13 are lined up along the cavities 16.

[0014] The support 12 is a member that does not have electronic conductivity, and an example of the material is stabilized zirconia. Examples of stabilizers for stabilized zirconia include CaO and MgO. Examples of the material for the fuel electrode 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 cermets that are composites (sintered bodies) of NiO and oxides (solid electrolytes).

[0015] The material of the electrolyte 18 is a solid oxide, and examples thereof include stabilized zirconia, ceria-based solid solution, and a solid solution of one or more selected from stabilized zirconia and ceria-based solid solution and alumina. Examples of stabilizers for stabilized zirconia include CaO, MgO, YO, ScO, and YbO. Examples of elements dissolved in ceria in the ceria-based solid solution include Gd, Sm, and Y.

[0016] The material of the cathode 19 is a perovskite oxide called La 1-X Sr X MnO 3-δ ,La 1-X Sr X Chief of Staff 3-δ ,La 1-X Sr X Co 1-Y Fe Y O 3-δ ,Pr 1-X Sr X MnO 3-δ Examples are given below.

[0017] The interconnector 20 connects the air electrode 19 and the fuel electrode 17 of the adjacent element units 13. The material of the interconnector 20 is conductive La 1-X Sr X TiO 3-δ In one electrolytic cell 11, the element parts 13 are connected in series by an interconnector 20. In adjacent electrolytic cells 11, the element parts 13 are connected by a connecting member (not shown), and the element parts 13 included in the 60 electrolytic cells 11 are connected in series.

[0018] Returning to FIG. 1, the manifold 14 supplies fuel gas to each of the electrolysis cells 11. Examples of the fuel gas include water vapor, carbon dioxide, and a mixture of these. The spent fuel gas that has passed through each of the electrolysis cells 11 is supplied to the manifold 15. An oxidant gas flows outside the electrolysis cells 11. Examples of the oxidant gas include air and oxygen.

[0019] When the positive electrode of a power supply (not shown) is connected to the air electrode 19 (see FIG. 2) of the element unit 13 and the negative electrode of the power supply is connected to the fuel electrode 17, electrons flow toward the fuel electrode 17. The fuel gas that has passed through the support 12 is reduced at the fuel electrode 17. Since electrons are lost at the air electrode 19, oxide ions that have moved to the air electrode 19 via the electrolyte 18 are oxidized at the air electrode 19. As a result, energy carriers such as hydrogen and hydrocarbons are synthesized in the electrolysis cell 11.

[0020] 3 is a graph showing the current-voltage characteristics and heat generation characteristics of the electrolysis module 10. Since the electrolysis of water vapor, carbon dioxide, and the like contained in the fuel gas is an endothermic reaction, the temperature of the element unit 13 (the temperature of the exhaust gas entering the manifold 15) decreases with an increase in current density compared to the temperature at the open circuit voltage of the element unit 13 at which current begins to flow (the average voltage of the element unit 13 when the current density is 0). When the current density increases further, the temperature of the element unit 13 begins to rise due to Joule heat, and reaches a thermal neutral point N where the heat absorption and heat generation are balanced.

[0021] At the thermal neutral point N, the electrolytic cell 11 neither generates nor absorbs heat, but when the current density of the element unit 13 becomes lower than the current density of the element unit 13 at the thermal neutral point N, heat absorption becomes predominant in the electrolytic cell 11, and the temperature decreases. When the current density of the element unit 13 becomes higher than the current density of the element unit 13 at the thermal neutral point N, heat generation becomes predominant in the electrolytic cell 11, and the temperature increases.

[0022] Returning to FIG. 1 , the electrolysis module 10 includes a collection of electrolytic cells 11. The electrolytic cells 11 are used in a state in which the element units 13 reach their operating temperature (for example, about 700°C). The element units 13 tend to lose more heat the closer they are to the periphery of the collection of electrolytic cells 11, and thus tend to lose more temperature, whereas the element units 13 tend to lose less heat the closer they are to the center of the collection of electrolytic cells 11, and thus tend to lose more temperature. If any part of the electrolytic cells 11 has a higher temperature than necessary, this may reduce the durability of the electrolytic cells 11.

[0023] FIG. 4 is a plan view of the electrolysis module 10. The manifolds 14, 15 are not shown in FIG. 4. The outer peripheral portion 21 is a portion located on the outer periphery of the arranged electrolysis cells 11. In this embodiment, 42 electrolysis cells 11 are included in the outer peripheral portion 21. The central portion 22 is a portion surrounded by the outer peripheral portion 21. In this embodiment, 18 electrolysis cells 11 are included in the central portion 22. When the collection of electrolysis cells 11 is viewed in a plan view, a single ring is formed by connecting the electrolysis cells 11 included in the outer peripheral portion 21 with lines. The electrolysis cells 11 included in the central portion 22 are located inside the ring.

[0024] In the electrolysis module 10, the average area of ​​the element units 13 (see FIG. 1 ) included in the electrolytic cells 11 in the outer circumferential portion 21 is smaller than the average area of ​​the element units 13 included in the electrolytic cells 11 in the central portion 22. The area of ​​the element units 13 refers to the area of ​​the portion where the electrolyte 18 (see FIG. 2 ), the fuel electrode 17, and the air electrode 19 overlap. The area of ​​the element units 13 can be changed, for example, by changing the area of ​​the fuel electrode 17 or the air electrode 19. The average area of ​​the element units 13 is the value obtained by dividing the sum of the areas of the element units 13 by the number of element units 13 for which the sum was calculated.

[0025] Since the element portions 13 of the electrolytic cell 11 are electrically connected in series, the same current flows through the element portions 13. Since the average area of ​​the element portions 13 included in the electrolytic cell 11 in the outer circumferential portion 21 is smaller than the average area of ​​the element portions 13 included in the electrolytic cell 11 in the central portion 22, the current density of the element portions 13 in the central portion 22 can be made smaller than the current density of the element portions 13 in the outer circumferential portion 21. This makes it possible to reduce the temperature rise of the element portions 13 in the central portion 22.

[0026] The central portion 22 is surrounded by the outer peripheral portion 21, and the outer peripheral portion 21 is open on the side opposite to the central portion 22, so that the heat dissipation of the outer peripheral portion 21 is greater than that of the central portion 22. Since the temperature rise of the central portion 22, which dissipates less heat than the outer peripheral portion 21, can be reduced, it is possible to reduce the temperature variation between the outer peripheral portion 21 and the central portion 22. Since overheating of the central portion 22 can be reduced, it is possible to ensure the durability of the electrolysis cell 11.

[0027] It is preferable that the average area of ​​the element units 13 included in the electrolytic cell 11 in the outer circumferential portion 21 is 40% or more of the average area of ​​the element units 13 included in the electrolytic cell 11 in the central portion 22, because this prevents the current density of the element units 13 in the outer circumferential portion 21 from becoming excessively high and reduces deterioration of the element units 13 in the outer circumferential portion 21. It is preferable that the average area of ​​the element units 13 included in the electrolytic cell 11 in the outer circumferential portion 21 is 97% or less of the average area of ​​the element units 13 included in the electrolytic cell 11 in the central portion 22, because this allows a difference to be made between the heat generated by the element units 13 in the outer circumferential portion 21 and the heat generated by the element units 13 in the central portion 22.

[0028] Fig. 5 is a block diagram of an electrolysis device 30. The electrolysis device 30 includes an electrolysis module 10, a power supply 31 that supplies current to the element unit 13 of the electrolysis module 10, and an adjustment unit 33 that adjusts the output of the power supply 31. In Fig. 5, the element units 13 included in the electrolysis cells 11 in the peripheral portion 21 and central portion 22 of the electrolysis module 10 are represented by line segments. The length of the line segments indicates the average size of the area of ​​the element units 13 included in the electrolysis cells 11 in each portion.

[0029] An ammeter 32 for measuring a current flowing through the circuit is disposed in a circuit connected to the power source 31 and the element section 13. The power source 31 outputs a unipolar pulsating current, pulse, or direct current to the circuit.

[0030] The electrolysis device 30 is equipped with a thermometer 34 that detects the temperature of the electrolytic cell 11 (see FIG. 1). The thermometer 34 is disposed near the manifold 15, and detects the temperature of the exhaust gas entering the manifold 15 as a representative value of the temperature of the electrolytic cell 11. However, this is not limited to this, and it is of course possible to dispose the thermometer 34 in a location other than the manifold 15 and detect a representative value of the temperature of the electrolytic cell 11.

[0031] The electrolysis device 30 includes a heater (not shown) that heats the electrolytic cell 11. There are no limitations on the heater as long as it can heat the electrolytic cell 11. Examples of the heater include a heater that heats the fuel gas or oxidant gas supplied to the electrolytic cell 11 to heat the electrolytic cell 11, and a heater that is disposed in a heat-insulating container that houses the electrolytic cell 11 to heat the electrolytic cell 11 from the periphery of the electrolytic cell 11.

[0032] The adjustment unit 33 includes a CPU, a ROM, a RAM, and a backup RAM (none of which are shown). The adjustment unit 33 acquires the current detected by the ammeter 32, and adjusts the output of the power source 31 so that the average temperature of the element unit 13 (the temperature of the electrolytic cell 11) becomes a temperature equivalent to the thermal neutral point N (see FIG. 3). Since the area of ​​the element unit 13 is known, the current to be passed through the electrolytic cell 11 in order to make the average temperature of the element unit 13 become a temperature equivalent to the thermal neutral point N is determined in advance. The adjustment unit 33 adjusts the output of the power source 31 so that the current detected by the ammeter 32 becomes equal to the previously determined current.

[0033] Instead of the adjustment unit 33 adjusting the output of the power source 31 so that the current detected by the ammeter 32 is equal to the pre-determined current, the adjustment unit 33 may obtain the temperature detected by the thermometer 34 and adjust the output of the power source 31 so that the average temperature of the element unit 13 (the temperature of the electrolytic cell 11) becomes a temperature equivalent to the thermal neutral point N. The adjustment unit 33 may use both of these.

[0034] In the electrolysis module 10, the average area of ​​the element units 13 included in the electrolytic cells 11 in the outer circumferential portion 21 is smaller than the average area of ​​the element units 13 included in the electrolytic cells 11 in the central portion 22. Therefore, when a current flows through the electrolytic cells 11 such that the average temperature of the element units 13 becomes a temperature equivalent to the thermal neutral point N, the average voltage of the element units 13 included in the central portion 22 becomes lower than the voltage equivalent to the thermal neutral point N. In addition, the average voltage of the element units 13 included in the outer circumferential portion 21 becomes higher than the voltage equivalent to the thermal neutral point N.

[0035] As a result, the average temperature of the element units 13 included in the central portion 22 becomes lower than the temperature corresponding to the thermal neutral point N, and the average temperature of the element units 13 included in the peripheral portion 21 becomes higher than the temperature corresponding to the thermal neutral point N. This makes it possible to make the activation overvoltage of the peripheral portion 21 lower than the activation overvoltage of the central portion 22. As a result, the peripheral portion 21 can synthesize energy carriers more efficiently than the central portion 22 for the energy input by the power source 31 to the electrolysis module 10.

[0036] Furthermore, because the average temperature of the element portions 13 included in the central portion 22 is lower than the temperature corresponding to the thermal neutral point N, it is possible to reduce the temperature variation between the central portion 22 and the peripheral portion 21 even if the heat dissipation of the central portion 22 is less than that of the peripheral portion 21. This makes it possible to reduce the decrease in durability of the electrolytic cell 11 caused by a part of the electrolytic cell 11 becoming hot.

[0037] Since the electrolysis device 30 performs electrolysis near the current density of the element unit 13 corresponding to the thermal neutral point N, the temperature of the element unit 13 can be maintained even with little new energy input. Therefore, the electrolysis efficiency can be ensured. Furthermore, the durability of the element unit 13 can be improved because the temperature change of the element unit 13 can be reduced.

[0038] An electrolysis module 40 in a second embodiment will be described with reference to Fig. 6 and Fig. 7. In the second embodiment, an electrolysis module 40 including cylindrical vertical stripe electrolysis cells 41 will be described. Fig. 6 is a plan view of the electrolysis module 40 in the second embodiment. The electrolysis module 40 includes a plurality of electrolysis cells 41. In this embodiment, a total of 18 electrolysis cells 41 are arranged, six vertically and three horizontally.

[0039] 7 is a perspective view of an electrolytic cell 41. The electrolytic cell 41 is cylindrical and includes an element section 42. The element section 42 includes, from the inside to the outside, an air electrode 43, an electrolyte 44, and an anode 45. An interconnector 46 is connected to the air electrode 43. The materials of the air electrode 43, the electrolyte 44, the anode 45, and the interconnector 46 are similar to those of the air electrode 19, the electrolyte 18, the anode 17, and the interconnector 20 of the electrolytic cell 11 in the first embodiment, and therefore will not be described.

[0040] Returning to Fig. 6, adjacent electrolytic cells 41 are connected by a conductor 47. The conductor 47 contacts the interconnector 46 and the fuel electrode 45 of adjacent electrolytic cells 41. The conductor 47 also has a function of buffering thermal expansion of the electrolytic cells 41. An example of the conductor 47 is a nonwoven fabric of metal fibers containing nickel or the like.

[0041] The electrolytic cells 41 adjacent to each other in a different direction via the conductor 47 are electrically insulated by the insulator 48. Examples of materials for the insulator 48 include alumina, mullite, magnesia, and zirconia. All of the electrolytic cells 41 are connected in series by the conductors 47 and the insulators 48. With an oxidant gas supplied into the electrolytic cell 41 and a fuel gas supplied to the outside of the electrolytic cell 41, electrolysis is performed in the element unit 42 to which a voltage is applied.

[0042] When the electrolysis module 40 is partitioned into two parts, an outer peripheral part 49 located on the outer periphery of the set of electrolysis cells 41, and a central part 50 surrounded by the outer peripheral part 49, the average area of ​​the element parts 42 included in the electrolysis cells 41 in the outer peripheral part 49 is smaller than the average area of ​​the element parts 42 included in the electrolysis cells 41 in the central part 50. Since the current density of the element parts 42 in the central part 50 can be made smaller than the current density of the element parts 42 in the outer peripheral part 49, it is possible to reduce a temperature rise of the element parts 42 in the central part 50. Since the temperature variation between the outer peripheral part 49 and the central part 50 can be reduced, it is possible to reduce a decrease in durability of the electrolysis cells 41 caused by a part of the electrolysis cells 41 becoming hot.

[0043] An electrolysis module 60 in a third embodiment will be described with reference to Figs. 8 and 9. In the third embodiment, an electrolysis module 60 including cylindrical horizontal stripe electrolysis cells 61 will be described. Fig. 8 is a side view of the electrolysis module 60 in the third embodiment. Fig. 9 is a cross-sectional view of the electrolysis module 60 taken along line IX-IX in Fig. 8.

[0044] In the electrolysis module 60, manifolds 63, 64 are connected to both ends of a plurality of cylindrical electrolysis cells 61 arranged at intervals from each other. The electrolysis cells 61 include a support and a plurality of element units 62 arranged on the support. The element units 62 include, in order from the outer surface of the support, a fuel electrode, an electrolyte, and a cathode, and adjacent element units 62 are connected by an interconnector (none of which are shown). The support, fuel electrode, electrolyte, cathode, and interconnector included in the electrolysis cell 61 are similar to the support 12, fuel electrode 17, electrolyte 18, cathode 19, and interconnector 20 of the electrolysis cell 11 in the first embodiment, and therefore description thereof will be omitted. All of the element units 62 are connected in series.

[0045] The manifold 63 supplies fuel gas into the electrolytic cells 61. The spent fuel gas that has passed through each of the electrolytic cells 61 is supplied to a manifold 64. An oxidant gas flows outside the electrolytic cells 61. Electrolysis takes place in the element section 62 to which a voltage is applied.

[0046] In the electrolysis module 60, when the electrolysis cells 61 are partitioned into two parts, an outer peripheral part 65 located on the outer periphery of the set of electrolysis cells 61, and a central part 66 surrounded by the outer peripheral part 65, the average area of ​​the element parts 62 included in the electrolysis cells 61 in the outer peripheral part 65 is smaller than the average area of ​​the element parts 62 included in the electrolysis cells 61 in the central part 66. Since the current density of the element parts 62 in the central part 66 can be made smaller than the current density of the element parts 62 in the outer peripheral part 65, it is possible to reduce the temperature rise of the element parts 62 in the central part 66 and ensure the durability of the electrolysis cells 61.

[0047] An electrolysis module 70 in a fourth embodiment will be described with reference to Fig. 10 and Fig. 11. In the fourth embodiment, an electrolysis module 70 including a flat electrolysis cell 71 will be described. Fig. 10 is a perspective view of the electrolysis module 70 in the fourth embodiment. In this embodiment, a total of nine electrolysis cells 71 are arranged, three vertically and three horizontally.

[0048] The electrolytic cell 71 includes a reaction unit 72 and end plates 73, 74 that sandwich the reaction unit 72 in the thickness direction. Bolts 75 are arranged on the periphery of the electrolytic cell 71, penetrating the reaction unit 72 and the end plates 73, 74 in the thickness direction. The reaction unit 72 and the end plates 73, 74 are fastened together by the bolts 75. In this embodiment, a plurality of reaction units 72 are stacked on top of each other.

[0049] The four spaces that penetrate the periphery of the electrolytic cell 71 in the thickness direction function as a passage 76 for gas to enter from outside the electrolytic cell 71 to a fuel chamber 90 (described later) of the reaction unit 72, a passage 77 for gas to exit from the fuel chamber 90 to the outside of the electrolytic cell 71, a passage 78 for gas to enter from outside the electrolytic cell 71 to an air chamber 92 (described later) of the reaction unit 72, and a passage 79 for gas to exit from the air chamber 92 to the outside of the electrolytic cell 71.

[0050] Fig. 11 is an exploded view of the electrolysis cell 71 taken along line XI-XI in Fig. 10, passing through passages 76 and 77. Fig. 11 is a cross-sectional view taken along line XI-XI, in which components constituting one reaction unit 72 are separated in the thickness direction. In Fig. 11, the thickness of each part is exaggerated. The reaction unit 72 includes, in order in the thickness direction, an interconnector 80, an anode frame 81, a cell 82 with separators, and an cathode frame 83.

[0051] The separator-equipped cell 82 includes an element portion 84 and a separator 88 arranged on the element portion 84. Holes (passages 76-78) penetrate the interconnector 80, the anode frame 81, the separator 88, and the cathode frame 83. The element portion 84 includes an electrolyte 85, and an anode 86 and an cathode 87 isolated by the electrolyte 85. The materials of the electrolyte 85, the anode 86, and the cathode 87 are similar to those of the electrolyte 18, the anode 17, and the cathode 19 of the electrolysis cell 11 in the first embodiment, and therefore will not be described.

[0052] The separator 88 is a frame-shaped member provided with an opening larger than the air electrode 87. The material of the separator 88 is, for example, stainless steel. The separator 88 is airtightly joined to the electrolyte 85 by brazing material or the like, avoiding the air electrode 87.

[0053] The interconnectors 80 are conductive plate-like members arranged on both sides in the thickness direction of the element section 84. The interconnectors 80 electrically connect the reaction units 72 adjacent to each other in the thickness direction. An example of the material of the interconnectors 80 is stainless steel.

[0054] The fuel electrode frame 81 is a frame-shaped member disposed between the interconnector 80 and the separator 88. The material of the fuel electrode frame 81 is, for example, stainless steel. The fuel electrode frame 81 surrounds the element portion 84 and a current collector 89 provided in the center of the interconnector 80.

[0055] The current collector 89 electrically connects the fuel electrode 86 and the interconnector 80. The material of the current collector 89 is, for example, a gas permeable porous body made of a metal such as Ni. A fuel chamber 90 surrounded by the interconnector 80 and the separator-equipped cells 82 is provided inside the fuel electrode frame 81.

[0056] The air electrode frame 83 is a frame-shaped member disposed between the interconnector 80 and the separator 88. The material of the air electrode frame 83 is, for example, an insulator such as mica. The air electrode frame 83 surrounds a current collector 91 provided in the center of the interconnector 80. The current collector 91 electrically connects the air electrode 87 and the interconnector 80. In this embodiment, the current collector 91 is formed integrally with the interconnector 80, but this is not limited to this. It is of course possible for the current collector 91 to be a member separate from the interconnector 80.

[0057] An air chamber 92 surrounded by the interconnector 80 and the separator-equipped cell 82 is provided inside the air electrode frame 83. The separator 88 separates the fuel chamber 90 from the air chamber 92, preventing the fuel gas in the fuel chamber 90 and the oxidizer gas in the air chamber 92 from mixing.

[0058] Returning to FIG. 10, the electrolytic cell 71 includes a terminal plate 93 arranged between the end plate 73 and the reaction unit 72, and a terminal plate 94 arranged between the end plate 74 and the reaction unit 72. The reaction units 72 are electrically connected in series between the terminal plates 93, 94. The terminal plate 93 is connected to the air electrode 87, and the terminal plate 94 is connected to the fuel electrode 86. The protruding portions of the terminal plates 93, 94 function as terminals. Holes (passages 76-78) penetrate the terminal plate 94. The element parts 84 included in the multiple electrolytic cells 71 are connected in series.

[0059] When the positive electrode of a power supply (not shown) is connected to terminal plate 93 and the negative electrode of the power supply is connected to terminal plate 94, electrons begin to flow toward the fuel electrode 86 of element unit 84. The fuel gas that has entered the fuel chamber 90 is reduced at the fuel electrode 86. As electrons are lost at the air electrode 87 of element unit 84, oxide ions that have moved to the air electrode 87 via the electrolyte 85 are oxidized at the air electrode 87. As a result, energy carriers such as hydrogen and hydrocarbons are synthesized in the electrolysis cell 71.

[0060] In the electrolysis module 70, when the electrolysis cells 71 are partitioned into two parts, an outer peripheral part 95 (eight in this embodiment) located on the outer periphery of the set of electrolysis cells 71, and a central part 96 (one in this embodiment) surrounded by the outer peripheral part 95, the average area of ​​the element parts 84 included in the electrolysis cells 71 in the outer peripheral part 95 is smaller than the average area of ​​the element parts 84 included in the electrolysis cells 71 in the central part 96. Since the current density of the element parts 84 in the central part 96 can be made smaller than the current density of the element parts 84 in the outer peripheral part 95, it is possible to reduce a temperature rise of the element parts 84 in the central part 96 and reduce a temperature variation between the central part 96 and the outer peripheral part 95. This makes it possible to reduce a decrease in durability of the electrolysis cells 71 caused by a part of the electrolysis cells 71 becoming hot.

[0061] The present invention has been described above based on an embodiment, but the present invention is in no way limited to the above embodiment, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention without departing from the spirit of the present invention.

[0062] The numbers and arrangements of the electrolytic cells 11, 41, 61, and 71 in the embodiments are merely examples and are set appropriately depending on the required characteristics of the electrolytic module.

[0063] In the first embodiment, the electrolysis module 10 in which a plurality of element units 13 are provided in one electrolysis cell 11 has been described, but the present invention is not necessarily limited to this. Electrolysis cells 11 provided with a single element unit 13 may be mixed and arranged with electrolysis cells 11 provided with a plurality of element units 13, or a plurality of electrolysis cells 11 provided with a single element unit 13 may be arranged.

[0064] In the first embodiment, the electrolytic cells 11 are arranged in a flat cylindrical horizontal stripe shape, but this is not necessarily limited to this. It is of course possible to change the design of the electrolytic cells 11 to a flat plate shape or a cylindrical horizontal stripe shape.

[0065] In the second embodiment, the electrolysis module 40 is described in which all 18 electrolysis cells 41 are connected in series, but the present invention is not necessarily limited to this. For example, it is of course possible to create two sets of nine electrolysis cells (three vertical and three horizontal) connected in series, and connect the two sets in parallel. In this case, when the nine electrolysis cells 41 connected in series are partitioned into an outer periphery (8 cells) and a central portion (1 cell) surrounded by the outer periphery, the average area of ​​the element portions 42 included in the electrolysis cells 41 in the central portion is set to be larger than the average area of ​​the element portions 42 included in the electrolysis cells 41 in the outer periphery.

[0066] In the third embodiment, the electrolytic cells 61 are clustered together, but this is not necessarily limited to this. It is of course possible to arrange the electrolytic cells 61 vertically and horizontally or in a single horizontal row.

[0067] In the fourth embodiment, the electrolytic cell 71 has a flat plate design. The flat plate electrolytic cell 71 may be an electrode-supported type or an electrolyte-supported type. It may be a metal-supported type (metal-supported flat plate type) in which the electrodes and electrolyte are supported by a porous body of a metal such as an Fe-Cr-based metal.

[0068] In the fourth embodiment, the passages 76-79 through which the gas passes are built into the electrolytic cell 71, but this is not necessarily limited to this. It is of course possible to provide a manifold as the passages 76-79 outside the electrolytic cell by joining it to the electrolytic cell. Examples of materials for the manifold include ceramics that have high high-temperature strength.

[0069] In the fourth embodiment, the terminal plates 93, 94 including terminals to which a power source (not shown) is connected are disposed in the electrolytic cell 71, but this is not necessarily limited to the above. It is of course possible to omit the terminal plates 93, 94 and electrically connect the reaction units 72 to the end plates 73, 74, thereby using the end plates 73, 74 as terminals of the electrolytic cell 71.

[0070] In the embodiment, the case where the element units 13, 42, 62, 84 of the electrolytic cells 11, 41, 61, 71 included in the electrolytic module 10, 40, 60, 70 are all connected in series, that is, the case where there is only one circuit in which the element units 13, 42, 62, 84 are connected in series in the electrolytic module 10, 40, 60, 70 has been described, but this is not necessarily limited to this. It is of course possible for the electrolytic module 10, 40, 60, 70 to have a plurality of circuits in which the element units 13, 42, 62, 84 are connected in series. In this case, the electrolytic cell including the element units constituting the circuits connected in series is divided into an outer periphery and a center, and the average area of ​​the element units included in the electrolytic cells in the center is made larger than the average area of ​​the element units included in the electrolytic cells in the outer periphery.

[0071] In the embodiment, the electrolyte 18, 44, 85 having oxide ion conductivity is used, but the present invention is not necessarily limited to this. It is of course possible to use the electrolyte 18, 44, 85 having proton conductivity under the operating conditions of the element unit 13, 42, 62, 84. Examples of substances that exhibit proton conductivity under the operating conditions of the element unit 13, 42, 62, 84 include perovskite-type oxides such as SrZrO3 and BaZrO3, pyrochlore-type oxides, and phosphates, in which the B site is substituted with trivalent metal ions such as Y and In. [Explanation of symbols]

[0072] 10,40,60,70 Electrolytic Module 11,41,61,71 Electrolytic cell 13,42,62,84 Element section 17,45,86 Fuel electrode (electrode) 18,44,85 Electrolyte 19,43,87 Air electrode 21,49,65,95 Outer circumference 22,50,66,96 central part 30 Electrolyzer 31 Power supply 33 Adjustment part

Claims

1. An electrolysis module including an electrolysis cell in which an element portion including an electrolyte is disposed separating two electrodes, the electrolysis cells being arranged and the element portions being electrically connected in series, An electrolysis module, wherein when the electrolysis cells are partitioned into an outer periphery located on the outer periphery of the set of arranged electrolysis cells and a central portion surrounded by the outer periphery, the average area of ​​the element units included in the electrolysis cells in the outer periphery is smaller than the average area of ​​the element units included in the electrolysis cells in the central portion.

2. 2. The electrolysis module according to claim 1, wherein an average area of ​​the element portions included in the electrolysis cells in the outer periphery is 40% or more of an average area of ​​the element portions included in the electrolysis cells in the central portion.

3. 2. The electrolysis module according to claim 1, wherein an average area of ​​the element portions included in the electrolysis cells in the outer periphery is 97% or less of an average area of ​​the element portions included in the electrolysis cells in the central portion.

4. An electrolysis module according to any one of claims 1 to 3; A power source that applies a current to a circuit connected to the electrodes; An adjustment unit that adjusts the output of the power source, the adjustment unit sets an average voltage of the central portion to a voltage lower than a thermal neutral point at which heat absorption and heat generation are balanced in the electrolysis module, which is set to a predetermined temperature, and sets an average voltage of the outer periphery to a voltage higher than the thermal neutral point.

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