Stacks, hot modules, and electrolytic devices

Abstract

We provide a stack that can reduce the occurrence of electrical failures. [Solution] The stack comprises a block in which cells are connected in series via an interconnect, including cells, separators fixed to the cells and extending outwards from the outer circumference of the cells, interconnects arranged in the thickness direction of the cells, and frames arranged in the thickness direction of the separators, an end plate positioned on the outside of the block in the thickness direction, a cover positioned between the end plate and the block, and a pressing member that presses the separator, frame, end plate and cover against each other in the thickness direction. The end plate comprises an overhanging portion located on the outside of the cover in the thickness direction, an intermediate member located between the overhanging portion and the cover, and a limiting portion that restricts the movement of the intermediate member relative to the overhanging portion in a direction intersecting the thickness direction.

Description

[Technical Field]

[0001] This invention relates to a stack comprising multiple cells in which electrochemical reactions occur. [Background technology]

[0002] A stack is a device that converts fuel gas into electrical energy or synthesizes energy carriers by electrolysis through electrochemical reactions. The stack disclosed in Patent Document 1, etc., consists of reaction units arranged in the thickness direction, each including a cell containing an electrolyte that isolates electrodes in the thickness direction, a separator fixed to the cell, an interconnector positioned in the thickness direction of the cell, and a frame positioned in the thickness direction of the separator. A pressurizing member presses the separator and the frame together in the thickness direction to reduce gas leakage from between the separator and the frame, and the interconnector is pressed against the electrodes of the cell to connect the cell and the interconnector in series. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-80457 [Overview of the project] [Problems that the invention aims to solve]

[0004] In a stack, the internal pressure increases due to the gas supplied to the cells and the energy carriers generated in the cells. This causes the separator to deform and bulge, and the cells and interconnects to shift. This can lead to electrical failures such as poor contact between the cells and interconnects or electrode detachment.

[0005] This invention was made to solve this problem and aims to provide a stack that can reduce the occurrence of electrical failures. [Means for solving the problem]

[0006] A first embodiment for achieving this objective is a stack comprising a block in which a plurality of reaction units are arranged in a line in the thickness direction, each reaction unit including a cell containing an electrolyte that separates a fuel electrode and an air electrode in the thickness direction, a separator fixed to the cell and extending outward from the outer circumference of the cell, an interconnector positioned in the thickness direction of the cell, and a frame positioned in the thickness direction of the separator, and the cells are connected in series via the interconnector; an end plate positioned on the outside of the block in the thickness direction; a cover positioned between the end plate and the block; and a pressurizing member that presses the separator, frame, end plate and cover against each other in the thickness direction. The frame includes an opening in the portion obtained by projecting the cell in the thickness direction, and the end plate includes a protruding portion located on the outside in the thickness direction of the cover, the protruding portion extending into the opening when viewed in the thickness direction and comprising an intermediate member located between the protruding portion and the cover, and a limiting portion that restricts the movement of the intermediate member relative to the protruding portion in a direction intersecting the thickness direction, the figure obtained by projecting the intermediate member in the thickness direction includes a first part that overlaps with a first figure obtained by projecting the protruding portion in the thickness direction, and a second part that does not overlap with the first figure.

[0007] A second embodiment, in the first embodiment, includes a spacer detachably disposed between the protruding portion and the intermediate member in the thickness direction of the first portion.

[0008] A third embodiment, in the first embodiment, includes a spring positioned between the protruding portion and the intermediate member in the thickness direction of the first portion.

[0009] In the fourth aspect, in any of the first to third aspects, the second part is located in the center of the protruding part.

[0010] The fifth embodiment is a hot module comprising a stack according to any of the first to fourth embodiments, a vaporizer that generates water vapor contained in the fuel gas supplied to the stack, a heat exchanger that exchanges heat with the gas supplied to the stack, a heater for heating the stack, and an insulating material in which the stack, vaporizer, heat exchanger and heater are arranged.

[0011] A sixth aspect is an electrolysis device, comprising the hot module according to the fifth aspect. Effects of the Invention

[0012] According to the present invention, the protruding portion of the end plate positioned on the outer side in the thickness direction of the cover protrudes into the opening of the frame when viewed in the thickness direction. An intermediate member is positioned between the protruding portion and the cover, and a restricting portion restricts movement of the intermediate member relative to the protruding portion in a direction intersecting the thickness direction, so that the intermediate member can be prevented from falling off. A shape obtained by projecting the intermediate member in the thickness direction includes a first portion overlapping a first shape obtained by projecting the protruding portion in the thickness direction, and a second portion not overlapping the first shape. Therefore, the intermediate member, together with the protruding portion, restricts displacement of the cover toward the outside in the thickness direction, and restricts swelling of the separator. This can reduce the occurrence of electrical failures caused by poor contact between cells and interconnectors, peeling of electrodes, and the like. Brief Description of the Drawings

[0013] [Figure 1] It is a cross-sectional view of a stack in the first embodiment. [Figure 2] It is a plan view of the stack. [Figure 3] It is a cross-sectional view of the stack taken along line III-III. [Figure 4] It is a cross-sectional view of a stack in a modified example. [Figure 5] It is a block diagram of the electrolysis device. [Figure 6] It is a cross-sectional view of a stack in the second embodiment. [Figure 7] It is a plan view of the stack. [Figure 8] It is a cross-sectional view of a stack in the third embodiment. [Figure 9] It is a plan view of the stack. Mode for Carrying Out the Invention

[0014] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a stack 10 according to the first embodiment. In FIG. 1, the thickness of each part constituting the stack 10 is exaggerated, and illustration of the middle portion in the thickness direction of the stack 10 is omitted.

[0015] The stack 10 includes a block 12 formed by stacking a plurality of reaction units 11 in the thickness direction (vertical direction in FIG. 1), end plates 13 and 14 respectively disposed on the outer side of the block 12 in the thickness direction, and covers 15 and 16 respectively disposed between the end plates 13 and 14 and the block 12. The block 12 has, for example, about 10 to 30 reaction units 11 stacked therein.

[0016] The cover 15 includes a terminal plate 17 provided with terminals for connecting an electric circuit. An insulator 18 is disposed between the cover 15 and the end plate 13. The insulator 18 electrically insulates the cover 15 and the end plate 13 from each other.

[0017] The cover 16 includes a terminal plate 19 provided with terminals for connecting an electric circuit and a support plate 20. The support plate 20 is disposed between the terminal plate 19 and the end plate 14. An insulator 21 is disposed between the support plate 20 and the end plate 14. The insulator 21 electrically insulates the cover 16 and the end plate 14 from each other. Stainless steel is exemplified as the material for the terminal plates 17, 19 and the support plate 20.

[0018] FIG. 2 is a plan view of the stack 10. A pressing member 22 that presses the end plates 13, 14, the covers 15, 16, and the block 12 against each other in the thickness direction is disposed on the peripheral edge of the stack 10. In the present embodiment, the pressing member 22 includes metal bolts that penetrate the end plates 13, 14, the covers 15, 16, and the block 12 in the thickness direction. A nut (not shown) that the bolt fits into is disposed on the end plate 14, and the end plates 13, 14, the covers 15, 16, and the block 12 are pressed by tightening the nut.

[0019] Let's return to Figure 1 for explanation. The space that penetrates the periphery of the end plate 14, cover 16, and block 12 in the thickness direction functions as a passage 23 for supplying fuel gas from outside the stack 10 to the fuel chamber 38 (described later) of the reaction unit 11, a passage 24 for discharging off-gas from the fuel chamber 38 to outside the stack 10, a passage (not shown) for supplying oxidizer gas from outside the stack 10 to the air chamber 39 (described later) of the reaction unit 11, and a passage (not shown) for discharging off-gas from the air chamber 39 to outside the stack 10.

[0020] The reaction unit 11 includes, in order in the thickness direction, a fuel electrode frame 27, a first separator 28, an air electrode frame 29, and a second separator 30. Holes (passages 23, 24) penetrate through the fuel electrode frame 27, the first separator 28, the air electrode frame 29, and the second separator 30. A cell 31 and an interconnector 35 are arranged inside the fuel electrode frame 27, the first separator 28, the air electrode frame 29, and the second separator 30.

[0021] The cell 31 includes an electrolyte 32 and a fuel electrode 33 and an air electrode 34 separated in the thickness direction by the electrolyte 32. In this embodiment, a flat-plate type cell 31 is described, but it is not limited thereto. The cell 31 may also be a metal-supported type (metal-supported flat-plate type) in which the electrodes and electrolyte are supported by a porous metal such as Fe-Cr. The cell 31 may be an electrode-supported type or an electrolyte-supported type.

[0022] The electrolyte 32 material is a solid oxide, and examples include stabilized zirconia, ceria-based solid solutions, and solid solutions of alumina with one or more elements selected from stabilized zirconia and ceria-based solid solutions. Examples of stabilizers for stabilized zirconia include CaO, MgO, Y2O3, Sc2O3, and Yb2O3. Examples of elements that dissolve in ceria in ceria-based solid solutions include Gd, Sm, and Y.

[0023] Examples of the material of the fuel electrode 33 include a material containing a Ni-containing catalyst and zirconia in which Y is solid-dissolved, and a material containing a Ni-containing catalyst and ceria in which Gd is solid-dissolved. Examples of the catalyst include cermet, which is a composite (sintered body) of Ni, a Ni-based alloy, NiO and an oxide (solid electrolyte).

[0024] The material of the air electrode 34 is La, which is a perovskite-type oxide 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 are exemplified.

[0025] The interconnector 35 is disposed between adjacent cells 31 in the thickness direction and electrically connects the cells 31 to each other. The interconnector 35 includes a plate-shaped support portion 36 and a current collecting portion 37 disposed on the support portion 36. Stainless steel is exemplified as the material of the support portion 36. The support portion 36 is provided with grooves (not shown) through which gas flows.

[0026] Examples of the current collecting portion 37 include a bent conductor and a spacer such as mica disposed in the conductor. Nickel, nickel-based alloys, and stainless steel are exemplified as materials for the conductor. The current collecting portions 37 are arranged at intervals from each other. Gas flows through the gaps between the current collecting portions 37.

[0027] The fuel electrode frame 27 is a frame-shaped member having an opening 27a, is disposed between the second separator 30 and the first separator 28, and surrounds the cell 31 and the current collecting portion 37. Stainless steel is exemplified as the material of the fuel electrode frame 27.

[0028] The first separator 28 is a frame-shaped member that is airtightly joined to the electrolyte 32 by brazing material or the like, avoiding the air electrode 34. Stainless steel is an example of a material for the first separator 28.

[0029] The air electrode frame 29 is a frame-shaped member having an opening 29a, and is positioned between the first separator 28 and the second separator 30, surrounding the support portion 36. An example of the material for the air electrode frame 29 is an insulator such as mica.

[0030] The second separator 30 is a frame-shaped member and is airtightly joined to the support part 36 by brazing material or the like. Stainless steel is an example of a material for the second separator 30.

[0031] A fuel chamber 38 is provided inside the fuel electrode frame 27, and an air chamber 39 is provided inside the air electrode frame 29. The fuel chamber 38 is connected to a passage 23 through a slit 40 and to a passage 24 through a slit 41. The air chamber 39 is connected to a passage (not shown) that penetrates the block 12 through a slit (not shown).

[0032] Joints (not shown) connecting to passages 23 and 24 are provided on the end plate 14. A gas pipe supplying fuel gas to passage 23, a gas pipe exhausting the off-gas of the fuel gas coming out of passage 24, a gas pipe supplying oxidizer gas to the passage, and a gas pipe exhausting the off-gas of the oxidizer gas coming out of the passage (none of which are shown) are connected to the joints, respectively. The first separator 28 and the second separator 30 separate the fuel chamber 38 and the air chamber 39, preventing the fuel gas in the fuel chamber 38 and the oxidizer gas in the air chamber 39 from mixing.

[0033] If stack 10 is a fuel cell, examples of fuel gases include hydrogen, carbon monoxide, and hydrocarbons, and examples of oxidizer gases include oxygen and air. If stack 10 is an electrolytic device (cell 31 is an electrolytic cell that has the function of electrolyzing the fuel gas), examples of fuel gases include water vapor, carbon dioxide, and mixtures thereof, and examples of oxidizer gases include oxygen and air. Stack 10 also includes configurations that allow for reversible operation as both a fuel cell and an electrolytic device.

[0034] The cover 15 is provided between the block 12 and the end plate 13. The cover 15 includes a support portion 36 that contacts the air electrode 34 of the cell 31, a frame-shaped second separator 30 hermetically bonded to the support portion 36, a conductive plate 42 arranged in overlapping directions in the thickness direction of the support portion 36, and a current collector portion 37 sandwiched between the conductive plate 42 and the support portion 36. One side of the second separator 30 is in contact with the terminal plate 17 all around, and the other side of the second separator 30 is in contact with the air electrode frame 29 all around, except for a slit (not shown). The cover 15 electrically connects the terminals of the terminal plate 17 to the block 12 and partitions the air chamber 39 of the cell 31 located in the block 12 closest to the end plate 13.

[0035] A frame-shaped third separator 43 is hermetically bonded to the conductive plate 42. The rigidity of the conductive plate 42 is greater than that of the third separator 43. Stainless steel is an example of a material used for the conductive plate 42 and the third separator 43. One side of the third separator 43 is in contact with the terminal board 17 all around, and the other side of the third separator 43 is in contact with the insulator 18 all around. Because the block 12 and the terminal board 17 are connected by two conductive paths, the second separator 30 and the third separator 43, the electrical resistance near the terminal board 17 can be reduced compared to the case where there is only one conductive path.

[0036] In this embodiment, the third separator 43 has a stress buffer portion 44 that curves in an arc shape toward the second separator 30, extending around its entire circumference. The second separator 30 has a stress buffer portion 45 that curves in an arc shape toward the air chamber 39, located at a position corresponding to the stress buffer portion 44, extending around its entire circumference. The first separator 28 has a stress buffer portion 46 that curves in an arc shape toward the fuel chamber 38, located at a position corresponding to the stress buffer portion 45, extending around its entire circumference.

[0037] The cover 16 is provided between the block 12 and the end plate 14. The cover 16 includes a conductive plate 47 that is arranged in overlapping directions in the thickness direction of the support portion 36 and in contact with the support portion 36, and a frame-shaped third separator 48 that is hermetically bonded to the conductive plate 47. The rigidity of the conductive plate 47 is greater than the rigidity of the third separator 48. One side of the third separator 48 is in contact with the terminal plate 19 all around, and the other side of the third separator 48 is in contact with the air electrode frame 29 all around, except for a slit (not shown). The cover 16 electrically connects the terminals of the terminal plate 19 to the block 12.

[0038] The cover 16 includes a support plate 20, a support portion 36 positioned between the support plate 20 and the conductive plate 47, and a current collector 37 sandwiched between the support plate 20 and the support portion 36. A frame-shaped third separator 49 is hermetically bonded to the support portion 36. Stainless steel is an example of the material for the conductive plate 47 and the third separators 48, 49. The rigidity of the support plate 20 is greater than that of the conductive plates 42, 47 and the separators 28, 30, 43, 48, 49.

[0039] One side of the third separator 49 is in contact with the terminal board 19 all around. Since the block 12 and the terminal board 19 are connected by the two conductive paths of the third separators 48 and 49, the electrical resistance near the terminal board 19 can be reduced compared to the case where there is only one conductive path.

[0040] In this embodiment, the third separator 48 has a stress buffer portion 50 that curves in an arc shape toward the third separator 49, located at a position corresponding to the stress buffer portion 46, extending around its entire circumference. The third separator 49 has a stress buffer portion 51 that curves in an arc shape toward the support plate 20, located at a position corresponding to the stress buffer portion 50, extending around its entire circumference.

[0041] The stress buffer sections 44, 45, 46, 50, and 51 are located between the area projected in the thickness direction of the cell 31 and the area projected in the thickness direction of the fuel electrode frame 27 and the air electrode frame 29. Because the stress buffer sections 44, 45, 46, 50, and 51 are bent, they are more easily deformed than the parts of the first separator 28, second separator 30, and third separator 43, 48, and 49 other than the stress buffer sections 44, 45, 46, 50, and 51. As a result, when assembling the airtight stack 10, if a compressive force in the thickness direction is applied to the fuel electrode frame 27, the first separator 28, and the air electrode frame 29 by the pressurizing member 22 (see Figure 2), the stress buffer sections 44, 45, 46, 50, and 51 deform, reducing the bending stress on the cell 31. This reduces damage to the cell 31 during the assembly of the stack 10.

[0042] Multiple cells 31 are electrically connected in series between terminal plates 17 and 19 via an interconnector 35, a conductive plate 47, a second separator 30, and a third separator 48. When the stack 10 is an electrolytic device, electrons flow out toward the fuel electrode 33 of the cell 31 when the positive electrode of a power supply (not shown) is connected to terminal plate 17 and the negative electrode of the power supply is connected to terminal plate 19. The fuel gas that enters the fuel chamber 38 is reduced by the fuel electrode 33. Electrons are removed at the air electrode 34, so oxide ions that have moved to the air electrode 34 via the electrolyte 32 are oxidized at the air electrode 34. This generates energy carriers such as hydrogen and hydrocarbons in the fuel chamber 38.

[0043] If the stack 10 is a fuel cell, when fuel gas is flowed into the fuel chamber 38 and oxidant gas is flowed into the air chamber 39, gaseous oxygen reacts with electrons at the air electrode 34 of the cell 31 to generate oxide ions. These oxide ions move through the electrolyte 32 and react with the fuel gas at the fuel electrode 33 to generate electrons. This causes current to flow to the load (not shown) connected to terminal boards 17 and 19.

[0044] When the stack 10 operates, the gas supplied to the cell 31 and the energy carriers generated in the cell 31 increase the pressure in the fuel chamber 38 and the air chamber 39. As the pressure in the fuel chamber 38 and the air chamber 39 increases, the first separator 28 and the second separator 30 deform, and consequently, the airtight third separators 43, 48, and 49 also deform.

[0045] If the pressure inside the stack 10 increases or the separators 28, 30, 43, 48, 49 deform, causing displacement of the cell 31, interconnect 35, and conductive plates 42, 47, there is a risk of electrical failures occurring due to poor contact between the cell 31 and interconnect 35 or delamination of electrodes (fuel electrode 33 and air electrode 34). In particular, if stress buffer sections 44, 45, 46, 50, 51 are provided in the first separator 28, the second separator 30, and the third separators 43, 48, 49, the separators 28, 30, 43, 48, 49 become more susceptible to deformation, which in turn increases the likelihood of electrical failures.

[0046] Because the rigidity of cover 15 is less than that of cover 16, which includes support plate 20, bulging occurs on cover 15 when the internal pressure of stack 10 increases. The end plate 13 has the function of limiting the bulging of cover 15. The end plate 13 includes a pressurizing portion 52, an overhanging portion 53, and an intermediate member 54. Stainless steel is an example of a material for the pressurizing portion 52, the overhanging portion 53, and the intermediate member 54.

[0047] The pressurized section 52 is a frame-shaped member whose shape, when viewed from the thickness direction of the cell 31, is almost the same as the shape of the fuel electrode frame 27 and the air electrode frame 29. The pressurized member 22 (see Figure 2) penetrates the pressurized section 52, the protruding section 53, the insulators 18, 21, the covers 15, 16, the block 12, and the end plate 14.

[0048] The protruding portion 53 is a frame-shaped member whose outer edge is sandwiched between the pressurizing portion 52 and the insulator 18. When viewed in the thickness direction, the protruding portion 53 extends inside the opening 27a of the fuel electrode frame 27 and inside the opening 29a of the air electrode frame 29.

[0049] The intermediate member 54 is a plate-shaped member positioned between the protruding portion 53 and the cover 15. The intermediate member 54 is located within the range projected from the cell 31 in the thickness direction (vertical direction in Figure 1), and a portion of the intermediate member 54 overlaps with a portion of the limiting portion 56 in the thickness direction.

[0050] The space between the cover 15 and the intermediate member 54 is non-conductive. This means that no current flows between the cover 15 and the intermediate member 54, whether they are in contact or there is a gap between them. In this embodiment, an electrical insulator 55 is provided on the surface of the intermediate member 54 that faces the cover 15. Examples of the electrical insulator 55 include solid insulators such as mica, heat-resistant cement, heat-resistant fiber, and glass or ceramic cloth or plates.

[0051] The limiting portion 56 restricts the movement of the intermediate member 54 relative to the protruding portion 53 in a direction intersecting the thickness direction. Because of the limiting portion 56, the intermediate member 54 is prevented from falling out from between the cover 15 and the protruding portion 53.

[0052] As shown in Figure 2, the figure obtained by projecting the intermediate member 54 in the thickness direction (perpendicular to the plane of the paper in Figure 2) includes a first part 57 that overlaps with the first figure obtained by projecting the protruding portion 53 in the thickness direction, and a second part 58 that does not overlap with the first figure. In this embodiment, the second part 58 is surrounded by the first part 57, and the second part 58 is located in the center of the protruding portion 53. The center of the protruding portion 53 is the position of the centroid of the first figure obtained by projecting the protruding portion 53 in the thickness direction, and the centroid of the first figure is the geometric center of the first figure. The limiting portions 56 are provided at two locations on the first part 57, spaced apart from each other. Providing two limiting portions 56 is just one example; there may be three or more limiting portions 56.

[0053] Figure 3 is a cross-sectional view of the stack 10 along line III-III. Figure 3 shows the area around the limiting portion 56 of the stack 10. The limiting portion 56 includes a hole 59 provided in the protruding portion 53 and a rod-shaped projection 60 that protrudes in the thickness direction from the intermediate member 54 toward the hole 59. The hole 59 penetrates the protruding portion 53, the projection 60 is located inside the hole 59, and there is a gap between the outer circumference of the projection 60 and the hole 59. The gap between the outer circumference of the projection 60 and the hole 59 is set to be large enough so that the intermediate member 54 does not fall off when the intermediate member 54 moves along the cover 15.

[0054] There is a gap in the thickness direction between the protruding portion 53 and the intermediate member 54. Since the protruding portion 53 is fixed to the pressurizing portion 52, the intermediate member 54 can move in the thickness direction between the cover 15 and the protruding portion 53 by the amount of the gap. In this embodiment, a spacer 61 is detachably placed between the protruding portion 53 and the intermediate member 54. The distance that the intermediate member 54 can move in the thickness direction between the cover 15 and the protruding portion 53 is reduced by the thickness of the spacer 61.

[0055] The assembly of stack 10 begins by stacking the end plate 14, insulator 21, cover 16, block 12, and cover 15 in that order, and then placing the insulator 18 and intermediate member 54 on cover 15. Next, the protruding portion 53 is placed on the insulator 18 while inserting the protruding portion 60 of the intermediate member 54 into the hole 59 of the protruding portion 53, and the pressurizing portion 52 is placed on the protruding portion 53. Then, the insulators 18 and 21, covers 15 and 16, block 12, and end plates 13 and 14 are tightened with the pressurizing portion 22. Next, a spacer 61 is attached to the protruding portion 60 between the intermediate member 54 and the protruding portion 53.

[0056] When the stack 10 operates (converting fuel gas into electrical energy or synthesizing energy carriers by electrolysis) and the internal pressure of the stack 10 increases, a bulge appears on the cover 15. When the intermediate member 54 is pressed against the cover 15, the intermediate member 54 is displaced in the thickness direction by the distance between the spacer 61 and the protruding portion 53 until the spacer 61 hits the protruding portion 53. When the spacer 61 hits the protruding portion 53 in the first part 57, the intermediate member 54 can no longer move, and the displacement of the cover 15 in the thickness direction is limited. Since the displacement of the cover 15 in the area projected with the cell 31 in the thickness direction is limited, poor contact between the cell 31 and the interconnector 35 and delamination of the fuel electrode 33 from the electrolyte 32 can be reduced. This reduces the occurrence of electrical failures in the stack 10.

[0057] By limiting the deformation of the cover 15 with the end plate 13, the deformation of the block 12, which is the cause of the deformation of the cover 15, can be limited. The deformation of the block 12 tends to increase as the number of reaction units 11 placed in the block 12 increases, but since the deformation of the block 12 can be limited by the end plate 13, the number of reaction units 11 placed in the block 12 can be increased. This makes it possible to increase the amount of electrical energy and energy carriers generated in the stack 10.

[0058] The distance between the protruding portion 53 and the intermediate member 54, and the thickness of the spacer 61 (the distance between the spacer 61 and the protruding portion 53) are set so that the displacement of the cover 15 does not cause poor contact between the cell 31 and the interconnector 35, or delamination of the fuel electrode 33 from the electrolyte 32. Since the amount of displacement of the cover 15 differs depending on the number of reaction units 11 constituting the block 12 and the operating conditions, spacers 61 of different thicknesses are detachably placed on the end plate 13 for each stack 10.

[0059] The intermediate member 54 only needs to be present in a portion of the area where the cell 31 is projected in the thickness direction. This is because the rigidity of the area of ​​the cover 15 where the cell 31 is projected in the thickness direction is greater than the rigidity of the part of the cover 15 excluding the area where the cell 31 is projected in the thickness direction. Therefore, reducing the displacement of a portion of the area where the cell 31 is projected in the thickness direction can reduce the occurrence of poor contact between the cell 31 and the interconnector 35. However, it is more preferable if the intermediate member 54 is present over the entire area where the cell 31 is projected in the thickness direction.

[0060] Furthermore, it is more preferable if the intermediate member 54 is present in the area obtained by projecting the stress buffer portion 44 in the thickness direction, as this can limit the deformation of the stress buffer portion 44. The intermediate member 54 only needs to be present in a part of the area obtained by projecting the stress buffer portion 44 in the thickness direction. It is even more preferable if the intermediate member 54 is present over the entire area obtained by projecting the stress buffer portion 44 in the thickness direction.

[0061] Since the second part 58 of the intermediate member 54 is located in the center of the protruding part 53, it is easy to place sensors, such as those that measure the length of the distance between the protruding part 53 and the intermediate member 54 to detect the degree of bulging of the cover 15. This makes it easy to detect the degree of bulging of the cover 15.

[0062] Since there is no current flow between the cover 15 and the intermediate member 54, current cannot flow through the cover 15 including the terminal plate 17, the end plate 13 including the intermediate member 54, the pressurizing member 22, the end plate 14, and the joint (not shown) attached to the end plate 14 to the gas pipe (not shown) connected to the joint. This prevents electrical malfunctions such as electric shock caused by contact of a part of the body with the gas pipe.

[0063] In this embodiment, before the stack 10 operates, there are gaps between the protruding portion 53 and the intermediate member 54, and between the protruding portion 53 and the spacer 61. This reduces the pressure exerted between the cover 15 and the intermediate member 54, and further reduces in-plane pressure variations, compared to when there are no gaps before the stack 10 operates. This reduces malfunctions in the cover 15 caused by pressure variations. It is, of course, possible to set the distance between the protruding portion 53 and the intermediate member 54, and the thickness of the spacer 61, so that no gaps are formed between the protruding portion 53 and the intermediate member 54, or between the protruding portion 53 and the spacer 61.

[0064] Figure 4 is a cross-sectional view of the stack 10 in a modified example in which a spring 62 is placed between the protruding portion 53 and the intermediate member 54 instead of the spacer 61. The spring 62 is a compression spring and accumulates elastic force in the direction of increasing the distance between the protruding portion 53 and the intermediate member 54. In this embodiment, the spring 62 is a coil spring. When assembling the stack 10, before placing the protruding portion 53 on the insulator 18, the convex portion 60 of the intermediate member 54 is placed inside the spring 62, and the spring 62 is positioned around the convex portion 60.

[0065] When the stack 10 operates and the internal pressure of the stack 10 increases, causing the cover 15 to bulge, the intermediate member 54, which is pressed by the cover 15, receives the reaction force of the spring 62 until the spring 62 is most compressed. Since the force that the cover 15 receives from the spring 62 gradually increases until the spring 62 is most compressed, the in-plane variation in the pressure exerted between the cover 15 and the intermediate member 54 can be reduced. This reduces the malfunctions that occur in the cover 15 due to pressure variations.

[0066] The electrolytic apparatus 70, which includes a stack 10, will be described with reference to Figure 5. Figure 5 is a block diagram of the electrolytic apparatus 70. The electrolytic apparatus 70 is a device that produces hydrogen from water and includes a hot module 71.

[0067] The hot module 71 comprises a stack 10, a vaporizer 72 that generates steam supplied to the stack 10, a heat exchanger 73 that performs heat exchange between the gas supplied to the stack 10 and the gas generated by the stack 10, and a heater 74 that heats the stack 10. To reduce heat dissipation, the hot module 71 has the stack 10, vaporizer 72, heat exchanger 73, and heater 74 arranged inside an insulating material 75.

[0068] The vaporizer 72 includes a heat exchanger that exchanges heat with the high-temperature gas containing oxygen produced by the stack 10, and heats water to produce steam. The steam produced by the vaporizer 72 contains hydrogen, which reduces the oxidation of the catalyst contained in the fuel electrode 33. The hydrogen-containing steam exchanges heat with the hydrogen and oxygen produced by the stack 10 by the heat exchanger 73, and is then heated by the heater 74 to the operating temperature of the stack 10 and supplied to the fuel chamber 38 of the stack 10. The air exchanges heat with the hydrogen and oxygen produced by the stack 10 by the heat exchanger 73, and is then heated by the heater 74 to the operating temperature of the stack 10 and supplied to the air chamber 39 of the stack 10.

[0069] Examples of the insulation material 75 include heat-resistant fibers such as ceramic wool, refractory ceramic fiber (RCF), and biosoluble fiber (AES), as well as heat-resistant containers formed from heat-resistant fibers. The heat-resistant fibers fill the gaps between the stack 10, the vaporizer 72, the heat exchanger 73, and the heater 74. The condenser 76 is a device for cooling hydrogen gas, and the liquefied water is supplied to the vaporizer 72 as raw water.

[0070] A second embodiment will be described with reference to Figures 6 and 7. In the first embodiment, a stack 10 in which an intermediate member 54 is placed on one end plate 13 was described. In the second embodiment, a case in which the intermediate member 54 is placed on both end plates 83 and 84 of the stack 80 will be described. In the second embodiment, the same reference numerals as in the first embodiment are used for the same parts as in the first embodiment, and some of the following descriptions will be omitted.

[0071] Figure 6 is a cross-sectional view of the stack 80 in the second embodiment. Similar to Figure 1, the thickness of each part is exaggerated in Figure 6, and the intermediate part in the thickness direction of block 81 is omitted from the illustration.

[0072] The stack 80 includes a block 81 formed by stacking multiple reaction units 11 in the thickness direction (vertical direction in Figure 6), end plates 83 and 84 positioned on the outside of the block 81 in the thickness direction, and covers 15 and 82 positioned between the end plates 83 and 84 and the block 81, respectively. An insulator 18 is positioned between cover 15 and end plate 83, and an insulator 85 is positioned between cover 82 and end plate 84.

[0073] Block 81 consists of approximately 10-30 stacked reaction units 11 and includes an interconnector 86 that connects the reaction units 11. The rigidity of the interconnector 86 is greater than that of the interconnector 35. The periphery of the interconnector 86 overlaps with the fuel electrode frame 27 and the air electrode frame 29, and passages 23, 24 and a pressurizing member 22 (see Figure 7) pass through it. The interconnector 86 is provided with a groove (not shown) through which an oxidizing gas flows between the air electrode 34 and the interconnector 86.

[0074] The cover 82 includes a conductive plate 47 that is arranged in overlapping directions in the thickness direction of the support portion 36 and in contact with the support portion 36, and a frame-shaped third separator 48 that is hermetically bonded to the conductive plate 47. One side of the third separator 48 is in contact with the terminal plate 19 all around, and the other side of the third separator 48 is in contact with the air electrode frame 29 all around. The cover 82 electrically connects the terminals of the terminal plate 19 to the block 81.

[0075] The cover 82 includes a conductive plate 87 arranged in overlapping directions in the thickness direction of the conductive plate 47, a frame-shaped third separator 88 hermetically bonded to the conductive plate 87, and a current collector 37 sandwiched between the conductive plate 87 and the conductive plate 47. The rigidity of the conductive plate 87 is greater than that of the third separator 88. One side of the third separator 88 is in contact with the terminal plate 19 all around, and the other side of the third separator 88 is in contact with the insulator 85 all around.

[0076] The end plate 83 includes a pressurizing portion 52, an overhanging portion 89 connected to the pressurizing portion 52 and projecting outwards to the opening 29a in the thickness direction, an intermediate member 54 positioned between the overhanging portion 89 and the cover 15, and an electrical insulator 55 interposed between the intermediate member 54 and the cover 15. The end plate 84 includes a pressurizing portion 52, an overhanging portion 89 connected to the pressurizing portion 52 and projecting outwards to the opening 29a in the thickness direction, an intermediate member 54 positioned between the overhanging portion 89 and the cover 82, and an electrical insulator 55 interposed between the intermediate member 54 and the cover 82. Stainless steel is an example of the material for the overhanging portion 89. The overhanging portion 89 is attached to the pressurizing portion 52 by metallurgical joining such as welding, screw joining, or mechanical joining such as crimping. The pressurizing portion 52 and the overhanging portion 89 may be made of a single component.

[0077] Figure 7 is a plan view of the stack 80. The overhang 89 is installed on opposing portions of the pressurizing portion 52. The figure obtained by projecting the intermediate member 54 in the thickness direction (perpendicular to the plane of the paper in Figure 7) includes a first portion 90 that overlaps with the first figure obtained by projecting the overhang 89 in the thickness direction, and a second portion 91 that does not overlap with the first figure. In this embodiment, the second portion 91 is divided by the first portion 90, and the first portion 90 is located in the center of the overhang 89. The limiting portions 56 are provided at two locations on the first portion 90, spaced apart from each other. Providing two limiting portions 56 is just one example; there may be three or more limiting portions 56.

[0078] The intermediate member 54 is located in the area projected from the cell 31 in the thickness direction and works in cooperation with the protruding portion 89 to restrict the displacement of the covers 15 and 82 in the thickness direction. By restricting the displacement of the covers 15 and 82 in the area projected from the cell 31 in the thickness direction, the intermediate member 54 can reduce poor contact between the cell 31 and the interconnector 35, and the occurrence of delamination of the fuel electrode 33 from the electrolyte 32. This reduces the occurrence of electrical failures in the stack 80.

[0079] The interconnector 86 is positioned approximately in the center of the thickness direction of block 81. The periphery of the interconnector 86 is sandwiched between the pressurizing portions 52, 52, and since the rigidity of the interconnector 86 is greater than that of the interconnector 35, when the intermediate member 54 restricts the deformation of the covers 15, 82, the force applied to the portion of block 81 between the interconnector 86 and cover 15 can be made approximately the same as the force applied to the portion of block 81 between the interconnector 86 and cover 82. This reduces the variation in stress in the thickness direction of block 81, thereby reducing the occurrence of failures caused by excessive stress.

[0080] A third embodiment will be described with reference to Figures 8 and 9. In the first and second embodiments, a case was described in which multiple limiting portions 56 are provided between the protruding portions 53, 89 and the intermediate member 54. In the third embodiment, a case will be described in which one limiting portion 104 is provided between the protruding portion 103 and the intermediate member 54. In the third embodiment, the same reference numerals as in the first embodiment are used for the same parts as in the first embodiment, and some of the following descriptions will be omitted.

[0081] Figure 8 is a cross-sectional view of the stack 100 in the third embodiment. In Figure 8, the thickness of each part constituting the stack 100 is exaggerated, and the intermediate part in the thickness direction of the stack 100 is omitted from the illustration. The stack 100 includes a block 12, end plates 101 and 14 arranged on the outside of the block 12 in the thickness direction, and covers 15 and 16 arranged between the end plates 101 and 14 and the block 12, respectively.

[0082] The end plate 101 includes a pressurized portion 102, an overhanging portion 103, and an intermediate member 54, which limit the bulging of the cover 15. Stainless steel is an example of the material used for the pressurized portion 102 and the overhanging portion 103. In this embodiment, the pressurized portion 102 and the overhanging portion 103 consist of a single component, but are not limited to this. It is naturally possible to attach the overhanging portion 103 to the pressurized portion 102 by metallurgical joining such as welding, or mechanical joining such as screw joining or riveting.

[0083] The pressurized section 102 is a frame-like portion whose shape, when viewed from the thickness direction of the cell 31, is almost the same as the shape of the fuel electrode frame 27 and the air electrode frame 29. The pressurized member 22 (see Figure 9) penetrates the pressurized section 102, the insulators 18, 21, the covers 15, 16, the block 12, and the end plate 14.

[0084] The protruding portion 103 is a frame-shaped part that, when viewed in the thickness direction, extends inside the opening 27a of the fuel electrode frame 27 and inside the opening 29a of the air electrode frame 29. An intermediate member 54 is positioned between the protruding portion 103 and the cover 15. There is a gap between the intermediate member 54 and the protruding portion 103. The intermediate member 54 is located in the area projected from the cell 31 in the thickness direction (vertical direction in Figure 1). An electrical insulator 55 is positioned between the intermediate member 54 and the cover 15.

[0085] Figure 9 is a plan view of the stack 100. The limiting portion 104 includes a polygonal hole 105 provided in the protruding portion 103 and a polygonal prism-shaped protrusion 106 provided on the intermediate member 54 corresponding to the shape of the hole 105. The protrusion 106 is located inside the hole 105, and there is a gap between the outer circumference of the protrusion 106 and the hole 105. The protrusion 106 has corners on its outer circumference, and corners corresponding to the corners of the protrusion 106 are provided in the hole 105, so that the intermediate member 54 does not rotate relative to the protruding portion 103. The limiting portion 104 restricts the movement of the intermediate member 54 relative to the protruding portion 103 in a direction intersecting the thickness direction. Because of the limiting portion 104, the intermediate member 54 does not fall out from between the cover 15 and the protruding portion 103.

[0086] The figure obtained by projecting the intermediate member 54 in the thickness direction (perpendicular to the plane of the paper in Figure 9) includes a first part 107 that overlaps with the first figure obtained by projecting the protruding portion 103 in the thickness direction, and a second part 108 that does not overlap with the first figure. In this embodiment, the second part 108 is surrounded by the first part 107, and the second part 108 is located in the center of the protruding portion 103. The center of the protruding portion 103 is the position of the centroid of the first figure obtained by projecting the protruding portion 103 in the thickness direction.

[0087] When the stack 100 operates and a bulge occurs in the cover 15, the intermediate member 54 is displaced in the thickness direction by the distance between the intermediate member 54 and the protruding portion 103 until the intermediate member 54 hits the protruding portion 103. When the intermediate member 54 hits the protruding portion 103 in the first part 107, the intermediate member 54 can no longer move, and the displacement of the cover 15 in the thickness direction is limited. This reduces the occurrence of electrical failures in the stack 100 caused by the bulge of the cover 15.

[0088] Since the second part 108 of the intermediate member 54 is located in the center of the protruding part 103, it is easy to position a sensor for detecting the degree of bulging of the cover 15. This makes it easy to detect the degree of bulging of the cover 15. Examples of sensors include one that measures the length of the distance between the protruding part 103 and the intermediate member 54, and one that measures the height of the protrusion 106 relative to the protruding part 103.

[0089] Although the present invention has been described above based on embodiments, it can be easily inferred that the present invention is not limited in any way to the above embodiments, and that various improvements and modifications are possible without departing from the spirit of the present invention.

[0090] The structures of covers 15, 16, and 82 in the embodiment are examples and are not limited to the structures of the embodiment. A cover is a layer that does not include cells 31 and has an airtight structure that reduces leakage of fuel gas and oxidizer gas, or a layer that does not include cells 31 and has a structure that includes terminals to which external electrical circuits are connected.

[0091] In the embodiment, a case in which stress buffer portions 44, 45, 46, 50, and 51 are provided in the first separator 28, the second separator 30, and the third separators 43, 48, 49, and 88 has been described, but the embodiment is not necessarily limited to this. It is of course possible to omit all or some of the stress buffer portions of the first separator 28, the second separator 30, and the third separators 43, 48, 49, and 88.

[0092] In this embodiment, the terminal board 17 is electrically connected to the blocks 12 and 81 via the conductive plate 42 and the third separator 43, but this is not necessarily the only possible configuration. It is certainly possible to omit the conductive plate 42 and the third separator 43 and make the terminal board 17 from a single flexible metal plate. Similarly, it is certainly possible to omit the conductive plate 47 and the third separator 48 and make the terminal board 19 from a single flexible metal plate.

[0093] In this embodiment, the case in which the terminal board 17 and blocks 12 and 81 are electrically connected by two conductive paths, the second separator 30 and the third separator 43, has been described, but this is not necessarily the only case. It is of course possible to omit one of the conductive paths. Similarly, it is of course possible to omit one of the third separators 48 and 49 or one of the third separators 48 and 88, and connect blocks 12 and 81 and the terminal board 19 with a single conductive path.

[0094] In this embodiment, passages 23 and 24 through which fuel gas and off-gas pass, and passages (not shown) through which oxidizer gas and off-gas pass, penetrate the terminal board 19, and joints (not shown) to which gas pipes are connected are provided on the end plates 14 and 84. However, the embodiment is not necessarily limited to this. Conversely, it is certainly possible to provide a terminal board 17 through which passages pass, and to provide joints (not shown) to which gas pipes are connected on the end plates 13, 83, and 101.

[0095] In the embodiment, an electrical insulator 55 was described as being placed between the intermediate member 54 and the covers 15, 82 to prevent current from flowing between the covers 15, 82 and the intermediate member 54, but this is not necessarily the only option. For example, it is certainly possible to make the entire intermediate member 54, including the protrusions 60, 106, out of an electrical insulator, or to interpose an electrical insulator between the protruding parts 53, 89, 103 and the pressurizing parts 52, 102. In these cases as well, it is possible to prevent current from flowing between the covers 15, 82 and the intermediate member 54.

[0096] In the embodiment, we have described restricting portions 56 and 104 in which holes 59 and 105 are made in the protruding portions 53, 89 and 103 and protrusions 60 and 106 are provided in the intermediate member 54, but the invention is not necessarily limited to this. It is certainly possible to provide protrusions that project toward the intermediate member 54 on the protruding portions 53, 89 and 103 and provide holes in the intermediate member 54 for the protrusions to fit into. In this case as well, the movement of the intermediate member 54 in the direction intersecting the thickness direction relative to the protruding portions 53, 89 and 103 can be restricted.

[0097] In the first embodiment, a case was described in which a spacer 61 and a spring 62 are placed between the protruding portion 53 and the intermediate member 54, but this is not necessarily the only case. It is certainly possible to omit the spacer 61 and the spring 62.

[0098] In the first embodiment, a case was described in which a spacer 61 is detachably arranged between the protruding portion 53 and the intermediate member 54, but this is not necessarily the only possible embodiment. It is certainly possible to provide an enlarged diameter portion, which is larger than the diameter of the hole 59, integrally with the protrusion 60 at the base of the protrusion 60, and to restrict the movement of the intermediate member 54 in the thickness direction by the enlarged diameter portion. Similarly, in the second and third embodiments, an enlarged diameter portion can be provided on the protrusion.

[0099] In the first embodiment, a case was described in which a compression coil spring (spring 62) is placed between the extension portion 53 and the intermediate member 54, but this is not necessarily the only case. It is of course possible to place other compression springs such as disc springs or leaf springs instead of a compression coil spring. It is also of course possible to provide recesses in the extension portion 53 or the intermediate member 54 and place the spring 62 in those recesses. This allows the spring 62 to be detachably placed between the extension portion 53 and the intermediate member 54.

[0100] Although not described in the second and third embodiments, it is of course possible to place spacers 61 and springs 62 between the intermediate member 54 and the protruding portion 89, or between the intermediate member 54 and the protruding portion 103.

[0101] In the embodiment, the case where the shape of cell 31 is a rectangle was described, but it is not necessarily limited to this. The shape of cell 31 may be a circle or an ellipse, or it may be a polygon other than a rectangle, such as a triangle or a pentagon.

[0102] In the embodiment, the case in which the gas passage is built into stacks 10, 80, and 100 has been described, but it is not necessarily limited to this. It is of course possible to connect the manifold, which serves as the gas passage, to the cell and provide it outside the cell. Examples of manifold materials include ceramics with high high-temperature strength.

[0103] In the embodiments, stacks 10, 80, and 100 including solid oxide type cells 31 have been described, but the embodiments are not necessarily limited to these. It is certainly possible to apply the techniques of the embodiments to stacks including other types of cells, such as molten carbonate type cells.

[0104] In the second embodiment, a stack 80 was described in which a block 81 including an interconnector 86 is placed between the covers 15 and 82. However, it is certainly possible to place the block 12 from the first embodiment between the covers 15 and 82 instead of the block 81. [Explanation of symbols]

[0105] 10,80,100 stacks 11 reaction units 12.81 blocks 13, 83, 84, 101 End Plates 15,82 Cover 22 Pressurizing member 27 Fuel pole frame (frame) 28. First separator (separator) 29. Air pole frame (frame) 29a aperture 30. Second separator (separator) 31 cells 32 Electrolytes 33 Fuel electrode 34 Air pole 35 Interconnectors 53,89,103 Overhang 54 Intermediate member 56,104 Restriction section 57,90,107 Part 1 58,91,108 Part 2 61 Spacer 62 springs 70 Electrolyzer 71 Hot Modules 72 Vaporizer 73 Heat exchanger 74 Heater 75 Insulation

Claims

1. A cell containing an electrolyte that separates the fuel electrode and the air electrode in the thickness direction, A separator fixed to the cell and extending outwards from the outer circumference of the cell, Interconnectors arranged in the thickness direction of the cell, A block comprising a frame arranged in the thickness direction of the separator, a plurality of reaction units arranged in the thickness direction, and the cells connected in series via the interconnector, An end plate positioned on the outer side of the block in the thickness direction, A cover positioned between the end plate and the block, A stack comprising the separator, the frame, the end plate, and the cover, and a pressing member that presses them together in the thickness direction, The frame includes an opening in the portion obtained by projecting the cell in the thickness direction. The end plate includes a protruding portion located on the outer side of the cover in the thickness direction, The aforementioned protruding portion protrudes into the opening when viewed in the thickness direction, An intermediate member located between the protruding portion and the cover, It includes a limiting portion that restricts the movement of the intermediate member relative to the protruding portion in a direction intersecting the thickness direction, The stack obtained by projecting the intermediate member in the thickness direction includes a first part that overlaps with the first figure obtained by projecting the protruding portion in the thickness direction, and a second part that does not overlap with the first figure.

2. The stack according to claim 1, further comprising a spacer detachably disposed between the protruding portion and the intermediate member in the thickness direction of the first part.

3. The stack according to claim 1, further comprising a spring disposed between the protruding portion and the intermediate member in the thickness direction of the first part.

4. The second part is the stack according to any one of claims 1 to 3, located in the center of the protruding portion.

5. The stack according to claim 1, A vaporizer that generates water vapor contained in the fuel gas supplied to the stack, A heat exchanger that performs heat exchange with the gas supplied to the stack, A heater for heating the aforementioned stack, A hot module comprising the stack, the vaporizer, the heat exchanger, and the heater, and an insulating material in which these are arranged.

6. An electrolytic apparatus comprising the hot module described in claim 5.

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