JP2007134095A - Solid oxide fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce loads imposed on tube plates through cell tubes, in a fuel cell having a structure where cell tubes of a cylindrical solid oxide fuel cell are used for support members for an upper header and a lower header. <P>SOLUTION: The solid oxide fuel cell has the plurality of cell tubes, the upper and lower headers with the tube plates fixed and supported thereto, and a support base for supporting the lower header, and is structured such that the upper and lower ends of the plurality of cell tubes penetrate the tube plates; the upper header is supported to the cell tubes at parts where the upper ends of the cell tubes penetrate; and the upper header supported by the cell tubes and the cell tubes are supported to the tube plate of the lower header supported to the support base in parts where the lower ends of the cell tubes penetrate. The solid oxide fuel cell is structured such that a load resistant tube plate mainly bearing a vertical load and a seal tube plate mainly carrying out a seal function are provided, and a load imposed on the seal tube plate through a junction part to the cell tubes is remarkably reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid oxide fuel cell (SOFC), and more particularly, to supply a plurality of fuel cell tubes having fuel cells formed on a peripheral surface thereof and fuel gas into the plurality of fuel cell tubes. The first gas chamber and the second gas chamber for discharging the fuel gas that has undergone the power generation reaction in the fuel cell are isolated via a third gas chamber that supplies an oxidant gas to the fuel cell. The present invention relates to a solid oxide fuel cell.

Conventionally, a solid oxide fuel cell (hereinafter referred to as SOFC) in which a power generator is formed on the surface of a porous base tube is well known, and a power generation reaction occurs as follows. For example, the fuel gas is allowed to flow inside the cell tube provided with the fuel cells in which layers such as the fuel electrode, the solid electrolyte, and the air electrode are formed on the surface of the base tube maintained at a temperature of 1000 ° C. When air as an oxidant is flowed, O ²⁻ ions move in the battery cell, an electrochemical reaction occurs, and a potential difference between the air electrode and the fuel electrode is generated to generate power. In addition, you may comprise so that air may be flowed inside a cell tube and fuel gas may be flowed outside.

In recent years, such SOFCs are expected to be a third generation power generation system because of their high power generation efficiency because the operating temperature of the battery cells is as high as about 1000 ° C.
In general, the SOFC cell structure includes a flat plate type and a cylindrical type, and the cylindrical type includes a cylindrical vertical stripe type and a cylindrical horizontal stripe type. The flat plate type is characterized in that the output per unit volume is high. However, in practical use, there are problems of gas sealability on the side surface of the cell and nonuniformity of temperature distribution in the cell. On the other hand, the cylindrical type is inferior to the flat plate type in terms of power density, but is characterized by high mechanical strength due to its shape.
The base tube of the cylindrical solid oxide fuel cell is made of a porous ceramic such as CaO-stabilized ZrO ₂ having an open air porosity of about 30%, and a multi-porous property made of LaMnO ₃ based material on the outside thereof. air electrode, Y ₂ O ₃ consisting of stabilized ZrO ₂ or the like solid electrolyte, a multi-vent of Ni / ZrO ₂ such as a fuel electrode of are sequentially provided.

  As an example of a cylindrical horizontal stripe type fuel cell having such a configuration, a fuel cell having a disk-shaped base portion and a plurality of base tube (fuel cell support pipe) joined to the base portion is disclosed ( For example, see Patent Document 1.) Further, a fuel cell including a plurality of fuel cell tubes and a tube plate supported by the tube is disclosed (for example, see Patent Document 2).

JP 2003-308854 A JP 2004-22368 A

  However, the one disclosed in Patent Document 1 is characterized in that the joint portion of the base portion and the fuel cell support pipe is covered with an electrolyte that is a gas-impermeable membrane. There is no disclosure. Further, what is disclosed in Patent Document 2 is a structure in which a fuel cell support tube (cell tube) and a tube plate are joined by an interference fit, and the present application relates to an improvement of the fuel cell described in Patent Document 2. It is.

  FIG. 8 shows a schematic configuration in a state where the fuel cell module described in Patent Document 2 is covered with a heat insulating wall. A large-capacity fuel cell is formed by connecting a plurality of modules covered with such heat insulating walls. In the figure, 1 is a cell tube, 2 is an upper header, and the upper header 2 includes a tube plate 5 and frame members 3 and 4 for fixing and supporting the tube plate 5. Reference numeral 2 'denotes a lower header, and the lower header 2' includes a tube plate 5 'and a frame member 3', 4 'for fixing and supporting the tube plate 5', which are coupled by means not shown. The lower header 2 ′ is supported by the support base 8. Reference numeral 9 denotes a wall made of a heat insulating material, and reference numeral 10 denotes a cover that covers the upper header 2. A space between the heat insulating wall 9 and the frame members 3, 4, 3 ′, 4 ′ is sealed to form a plurality of fuel cell tubes 1. The fuel cell tube 1 penetrates through the tube plates 5 and 5 ′ and is interference-fitted at the penetration part, and a sealing effect and an adhesion effect are maintained by joining by the interference fit. A heat-resistant electric insulating layer such as aluminum oxide is formed on the interference fitting portion of the cell tube 1. FIG. 9 shows a perspective view of the internal module with the heat insulating wall 9 and the cover 10 removed, and the same components as those in FIG. 8 are given the same reference numerals. Reference numeral 21 denotes a heat insulating member omitted in FIG. Reference numeral 31 denotes a fuel battery cell. This fuel cell is a horizontal stripe type cylindrical solid oxide fuel cell in which the cells 31 are connected in series. FIG. 10 is a view corresponding to the arrow X in FIG. 8 and shows a state in which a large number of cell tubes are arranged.

Returning to FIG. 8, the fuel gas is supplied into the upper header 2 through a passage (not shown), flows into the lower header through the cell tube, and is discharged from the lower header to an external device through a passage (not shown). Is done. On the other hand, air as an oxidant is supplied to a space surrounded by the tube plates 5, 5 ′ and the heat insulating wall 9 through a passage (not shown) and discharged to an external device through a passage (not shown). The cell tube 1 includes a fuel cell 31 in which a fuel electrode layer, an electrolyte layer, and an air electrode layer are sequentially formed on the outer periphery of the base tube. Oxygen in the supplied air receives electrons at the air electrode (cathode) on the outer surface of the tube and becomes O ²⁻ ions, and passes through the electrolyte layer. On the other hand, the fuel gas passing through the cavity of the cell tube 1 reacts with the O ²⁻ ions that have passed through the porous substrate tube and moved through the electrolyte at the fuel electrode (anode) to be changed into water and carbon dioxide. At this time, electrons are emitted and become current, which is taken out at the tip of the cell tube, but the current collector is not shown. The fuel cell 31 is maintained at a temperature of 900 ° C. to 1000 ° C. during power generation. Exhaust gas containing unreacted fuel gas is sent from the lower header to an external device (not shown). Oxygen is consumed and gas containing residual oxygen that has not been consumed is also sent to an external device (not shown). These gases are recombusted by an external device, used for preheating fuel or air, reforming fuel, and the like, and then discharged into the atmosphere.

  However, in the structure of the fuel cell of Patent Document 2, the cell tube 1 is joined to the tube plates 5 and 5 ′ of the upper header 2 and the lower header 2 ′ by an interference fit, and the upper header is supported by the cell tube. The cell tube is supported by the tube plate of the lower header, and these are supported by the support base 8 via the lower header. The cell tube and the tube plate are deformed due to thermal deformation of the tube plate and deformation due to the weight of the header. A bending moment is applied to the joint portion and the cell tube may break, and a support structure that reduces the load on the cell tube is required. Even if the cell tube does not break, the fuel gas side and air side airtightness may be impaired by deformation of the fitting portion between the cell tube and the tube sheet.

  Accordingly, the present invention provides a cylindrical solid oxide fuel cell having a support structure that reduces the load on the cell tube to prevent the airtightness of the fuel gas side and the air side from being impaired, and further prevents the cell tube from being damaged. The purpose is to provide.

  In order to achieve the above object, the present invention provides a plurality of fuel cell tubes having fuel cells formed on a peripheral surface, a first gas chamber for supplying fuel gas into the plurality of fuel cell tubes, And a second gas chamber for discharging the fuel gas that has undergone a power generation reaction in the fuel cell, separated by a third gas chamber for supplying an oxidant gas to the fuel cell. In a fuel cell, a tube plate that divides the first or second gas chamber (hereinafter referred to as a fuel gas chamber) and the third gas chamber is composed of at least two tube plates and is supported on the fuel gas chamber side. One tube located on the fuel gas chamber side at the tube plate fitting portion at both ends of the fuel cell tube formed by the multiple tube plate and inserted on the fuel gas chamber side from the multiple tube plate The third gas chamber has an airtight function on the plate side. So as to have a cell support function in addition to the tube plate positioned proposes a solid oxide fuel cell characterized by that has the fitting portion shape or different tubesheet thickness.

  For example, if the first gas chamber is disposed in the upper part and the second gas chamber is disposed in the lower part, the first gas chamber is supported by the cell tube at the junction between the first tube plate and the fuel cell tube. Thus, the joined body of the first gas chamber and the cell tube is supported by the second tube plate at the joint portion between the second tube plate, which is the second gas tube plate, and the cell tube. In this case, the second gas chamber disposed in the lower part is supported by the support base. During power generation, the fuel cell is kept at a high temperature of 900 to 1000 ° C. Therefore, the vertical load due to the weight of the first gas chamber or the total weight of the first gas chamber and the cell tube is applied to the joint portion between the cell tube and the tube plate. In addition to this, a load due to thermal expansion of the tube sheet or the like is applied. These loads act as a bending moment on the cell tube in addition to the force along the axial direction, and the fixed support ends in which the peripheral portions of the first and second tube sheets are fixedly supported on the side walls of the respective fuel gas chambers. It becomes the largest at the joint between the cell tube and the tube plate joined to the tube plate at a position adjacent to the tube plate.

  The vertical load due to the weight of the first gas chamber is applied at the junction of the first tube plate and the cell tube, and the vertical load due to the total weight of the first gas chamber and the cell tube is applied at the junction of the second tube plate and the cell tube. Therefore, the vertical load applied to the joint portion between the second tube sheet and the cell tube is larger than the vertical load applied to the joint portion between the first tube plate and the cell tube. Accordingly, at least the second tube plate, which is the tube plate of the second gas chamber disposed in the lower part, is preferably a double tube plate or more. Of the multiple tube plates, a hole is provided in addition to the tube plate facing the second gas chamber so that a space formed between the tube plates communicates with the third gas chamber, and these spaces do not become a sealed space. Like that. Thereby, when it is set as sealed space, the force applied to the junction part of a tube plate and a cell tube by the pressure rise in sealed space by the temperature rise of the gas confine | sealed in this sealed space can be excluded.

  Further, the distance from the fixed support end that fixes the peripheral portion of one tube plate located on the fuel gas chamber side to the fitting portion of the fuel cell tube that is closest to the fixed support end is set to the third gas chamber side. It is preferable that the distance is longer than the distance from the fixed support end that fixes the other peripheral portion of the tube plate positioned at the position to the fitting portion of the fuel cell tube that is closest to the fixed support end.

  In the solid oxide fuel cell, for example, the second gas chamber is supported on a support base, the lower end portion of the cell tube is joined to the tube plate (second tube plate) of the second gas chamber, and the first upper end portion of the cell tube is joined. Assuming that the tube plate (first tube plate) of the gas chamber is joined, the weight of the first gas chamber is at the joint between the first tube plate and the cell tube, and the joint between the second tube plate and the cell tube. The total weight of the first gas chamber and the cell tube is applied to the part as a vertical load. Due to the vertical load, bending occurs between the joint between the tube tube and the tube plate, which is located next to the fixed support end around the tube plate, and the fixed support end. In addition to the force along the axial direction of the tube, a moment is generated. Further, during power generation of the fuel cell, the temperature of the header tube plate is higher than the temperature of the other part of the header. Since the tube plate is fixedly supported at its peripheral edge, the tube plate is restrained by the fixed support end even if the tube plate tries to extend, so that compressive stress is generated in the tube plate, the cell tube is pushed by the tube plate, and the fixed The tube sheet is deformed in the vertical direction between the support end and the joint, that is, the tube sheet is bent and a bending moment is applied to the cell tube. The vertical load applied to these cell tubes and the bending moment caused by the temperature difference are the largest in the cell tube adjacent to the fixed support end, that is, the cell tube located next to the fixed support end, and away from the fixed support end. It becomes smaller in the cell tube located. Therefore, it is the cell tube located next to the fixed support end of the tube sheet that is damaged due to excessive load on the cell tube.

  In the multiple tube plate structure, the tube plate facing the fuel gas chamber may have an airtight function, and the other tube plates may have a cell tube support function. For this reason, the distance from the fixed support end that fixes the peripheral edge of the tube plate facing the fuel gas chamber to the cell tube bonded to the tube plate at a position adjacent to the fixed support end is set to another distance. If the tube plate is longer than that of the tube plate, the deflection of the tube plate due to the vertical load is substantially determined by the tube plate with the shorter distance, and the tube plate with the shorter distance and the tube plate with the longer distance are Since the bending becomes the same, the bending angle of the tube sheet at the joint is smaller in the tube sheet having the longer distance than that of the tube sheet having the shorter distance. Accordingly, the bending moment applied from the tube sheet having the longer distance to the joint portion with the cell tube is reduced. As will be described later, when the joint is joined by an interference fit between the barnacle-like hole of the tube plate and the cell tube, the smaller the bending moment at the joint is, the smaller the deformation of the barnacle-like hole becomes. It is possible to prevent such a problem that the sealing function of the joint portion is lowered due to deformation in the hole and gas leakage occurs. That is, according to the multiple tube plate structure of the present invention, the tube plate having a shorter distance, that is, the tube plate facing the fuel gas chamber, is used as a load-resistant tube plate that bears a load at the joint with the cell tube, and the fuel gas The tube sheet having the longer distance facing the chamber can be used as a seal tube sheet having a sealing function at the joint with the cell tube.

  One tube plate facing the fuel gas chamber should be formed thinner than the other tube plate facing the third gas chamber, and in particular, a fixed support for fixing the peripheral portion of the tube plate facing the fuel gas chamber It is preferable to make the tube plate having a longer distance from the end to the joint portion to the cell tube joined to the tube plate at a position adjacent to the fixed support end thinner than the tube plate having a shorter distance. The sealing tube plate that has the gas sealing function is made as thin as possible to keep the sealing function as much as possible, and by increasing the distance as described above, in the interference fitting part between the cell tube and the tube plate due to temperature difference or vertical load The load due to the temperature difference as described above can be reduced. The larger the load at the joint, that is, the barnacle-shaped hole due to the interference fit, the larger the deformation of the barnacle-shaped hole, and in extreme cases, a partial gap may occur in the mating part and the sealing function may be impaired. However, it is possible to eliminate such a concern by reducing the load on the fitting portion.

  Next, regarding the joining of the tube plate and the cell tube, the cell tube is preferably inserted into a hole formed in the shape of a barnacle (Fujitsumi) of the tube plate and joined to the tube plate by an interference fit. Thus, it is taught in the drawing of Patent Document 2 that the cell tube is press-fitted into a hole formed in a barnacle shape of the tube plate and joined by an interference fit. In the present invention, the barnacle (Fuji 壷) -shaped hole is formed in a shape that narrows toward the tip side of the cell tube. This facilitates the insertion of the cell tube. That is, the tip end side of the cell tube can be easily press-fitted from the rounded surface side of the barnacle (Fuji Aoi) -shaped hole.

  The cell tube is made of a porous ceramic material, and an electrical insulating layer is formed on the outermost surface of the portion to be inserted into the tube plate of the cell tube, but it is not always guaranteed that the roundness of the outer periphery is guaranteed. It's not easy. A ring member with a guaranteed roundness of the outer periphery is fixed to the cell tube, and the outer periphery of the ring member is fitted into a barnacle-like hole in the tube plate and joined to the tube plate, thereby preventing gas leakage at the joint. It can be completely prevented. This is also taught in Patent Document 2. The ring member is fixed to the cell tube by an inorganic adhesive having appropriate heat resistance and adhesive strength or other means and gas-sealed.

  A ring member may be fixed to the tip of the cell tube, and the ring member may be fitted into a hole formed in a barnacle (Fujitsumi) shape of the tube plate and hermetically bonded to the tube plate by welding.

  The shape of the fixed support end of the member that fixedly supports the peripheral edge of the tube plate is a fixed distance on the outer periphery of the cell tube joined to the tube plate at a position adjacent to the fixed support end on the side facing the fixed support end. It is good also as a shape which goes along. When the tube plate is bent in a certain amount in the vertical direction, the stress generated at the joint between the tube plate and the cell tube depends on the distance from the fixed support end to the joint portion between the cell tube and the tube plate as described above. In contrast, the larger the distance, the smaller. Therefore, if this distance varies depending on the joint part (circumferential part) with the cell tube, the stress of the tube plate at the different joint part, that is, the force that the cell tube receives from the tube plate will be different and non-uniform. The load applied to the outer periphery on the tube plate fixing support end side becomes uneven. As described above, the shape of the fixed support end is located next to the fixed support end and is formed along the outer diameter with a certain distance from the outer diameter of the cell tube joined to the tube plate, The load applied to the circumference on the fixed support end side of the cell tube which is located next to the fixed support end where the load received from the tube sheet is the most severe and is joined to the tube sheet is equalized. Since the load itself is the same size, if it is equalized, there is no part on the circumference where a particularly large load is applied, and the reliability is improved.

  Both the first and second tube plates are double tube plates made of two tube plates, and a diameter step portion is provided at each end of the fuel cell tube, and the tube plate faces the third gas chamber. It is also possible to provide a cell tube support function by bringing the peripheral surface of the through hole into contact with the shoulder of the diameter step portion of the cell tube.

  In such a configuration, the vertical load applied to the cell tube is carried by bringing the tube plate facing the third gas chamber into contact with the diameter step portion provided on the cell tube, so that the fitting portion generated in the case of an interference fit There is no risk of lowering the supporting force due to the looseness of the. If a through hole of the tube plate in the diameter step portion is provided with a gap in the fitting portion with the cell tube, a load accompanying deformation due to thermal expansion of the tube plate can be eliminated.

  The tube plate facing the third gas chamber has a cell tube support function by affixing a ring member having a diameter step portion to the fuel cell tube and contacting the diameter step portion of the ring member. It's also good. In such a configuration, instead of forming the cell tube in a stepped shape having a small diameter portion and a large diameter portion, the ring member is formed in a stepped shape and fixed to the cell tube, so that the cell tube can be easily manufactured.

  Further, the tube plate facing the third gas chamber is a specific cell tube, in particular, a diameter step portion of a cell tube adjacent to a fixed support end of the tube plate or a diameter step portion of a ring member fixed to the cell tube. A cell tube support function may be provided by abutting on the tube.

  A plurality of fuel battery cell tubes having fuel cells formed on the peripheral surface, a first gas chamber for supplying fuel gas into the plurality of fuel battery cell tubes, and a fuel that has undergone a power generation reaction in the fuel battery cells In a solid oxide fuel cell in which a second gas chamber for discharging gas is disposed separately from a third gas chamber for supplying an oxidant gas to the fuel cell, the fuel gas chamber and the cell The load applied to the cell tube from the tube plate by thermal deformation due to the gravity of the tube and the temperature difference of each part can be reduced, and the cell tube can be prevented from being broken and the gas leak occurring at the joint between the cell tube and the tube plate.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of a cylindrical solid oxide fuel cell of the present invention. The overall configuration as a fuel cell is the same as that described in the conventional configuration of FIGS. FIG. 1 shows only the schematic configuration of the internal module. In Fig. 1, the tube sheet is doubled, one sheet is a load-bearing tube sheet that mainly supports the load, and the other sheet is thin to reduce the thickness and mainly provide a gas seal function at the joint between the cell tube and the tube sheet. It is configured to be a sealed tube plate to ensure. In the figure, reference numeral 1 denotes a fuel cell tube, 2 denotes an upper header (first gas chamber), and the upper header 2 includes an upper first tube plate 5, an upper second tube plate 6, upper frame members 3, 4, 7 and these are connected by means not shown. Reference numeral 2 ′ denotes a lower header (second gas chamber) having the same configuration as the upper header, and the same configuration is indicated by “′”. As will be described later, the cell tube 1 is joined to the tube plates 5, 6, 5 'and 6' by an interference fit, and a heat-resistant electrical insulating layer such as aluminum oxide is formed at the joined portion of the cell tube 1, for example. Has been. The upper first tube sheet 5 is fixedly supported by being sandwiched between upper frame members 3 and 4, and the upper second tube sheet 6 is fixedly supported by being sandwiched by upper frame members 4 and 7. The same applies to the lower header (second gas chamber). Of the frame member the distance L ₂ between the cell tube 1 is located next to the fixed support end and the fixed supporting end of the frame member for fixing and supporting the upper second tube sheet 6 for fixing and supporting the first tube sheet 5 top It is longer than the distance L ₁ between the cell tube 1 is located next to the fixed support end and the fixed support edge.

A load is applied to the joint between the tube plate and the cell tube due to the vertical load due to the weight of the upper header 2 and the thermal expansion difference due to the temperature difference between the header tube plate and the other part of the header. towards the distance L ₂ is longer second tube sheet 6 as smaller than the shorter first tube sheet of the distance L _1. However, if the distance L is long, the deflection due to the vertical load increases, and the tube plates 5 and 6 of the upper header 2 become the cell tube 1, and the joined body of the upper header 2 and the cell tube 1 becomes the tube plate of the lower header 2 '. Since it cannot be stably supported by 5 'and 6', this bending is made small by the first tube sheet 5, 5 '. Accordingly, the force applied from the second tube sheet 6, 6 'to the joint between the tube sheet and the cell tube is reduced, and gas leakage does not occur at the joint. That is, the first tube plates 5 and 5 ′ function as load-resistant tube plates that mainly bear loads, and the second tube plates 6 and 6 ′ function as seal tube plates.

  As shown in FIG. 3, when a hole in the tube sheet 5 is formed in a barnacle (Fuji-an) -shaped hole and a cell tube is tightly fitted in the hole, In the case of double tube plates of mm and 0.3 mm, the stress of the rounded portion 5b of the barnacle-shaped hole, which is an index of the force applied from the tube plate to the cell tube, is applied between the header and the tube plate when a vertical load is applied. The measurement was performed when a temperature difference was given. As a result, the stress of a 0.5mm tube sheet with a double tube sheet configuration is slightly lower than that of a single tube sheet for vertical loads, and the stress of a 0.3mm tube sheet is 1/7 to 1/10. For the temperature difference, the stress of the 0.5mm tube sheet with the double tube plate configuration is slightly lower than that of the single tube sheet at the same temperature difference, and the stress of the 0.3mm tube sheet is 1/2 to 1/3. Became. The smaller the stress, the smaller the risk of gas leakage due to the sag of the joint between the cell tube and the tube sheet. Therefore, the tube plate is configured as a double tube plate, and one tube plate is made thin and supported so that the inclination angle of bending with respect to the same displacement is reduced to form a tube plate having an excellent sealing function. By providing the function of supporting the load, it is possible to completely prevent the occurrence of gas leakage at the joint between the cell tube and the tube sheet.

  As shown in FIG. 1, the double tube plate has a tube plate facing the space in the header on the second tube plate (seal tube plate) 6 and 6 ', on the fuel cell side (center side of the cell tube 1). It is preferable that the tube plate facing the space is configured as the first tube plate (load-resistant tube plate) 5, 5 ′, and the holes 5a, 5a ′ are provided in the load-resistant tube plates 5, 5 ′. As a result, the space in the header (fuel gas chamber) and the fuel cell side space (third gas chamber) are sealed with the sealing tube plate having an excellent sealing function.

The embodiment of FIG. 1 has a configuration in which the thickness of the two tube plates and the fulcrum distance (L ₁ , L ₂ ) of the fixed support are different, but even if the two tube plates have the same configuration, the load is dispersed. The load on the cell tube is reduced. The vertical load applied to the joint between the cell tube and the tube sheet is higher in the lower header tube plate than in the upper header tube plate because the vertical load due to the gravity of the cell tube is added to the lower header tube plate. Become. Therefore, only the tube sheet of the lower header may be a double tube plate, and the tube sheet of the upper header may be a single tube sheet.

  FIG. 2 is a diagram showing a schematic configuration of the second embodiment. The fixed support ends of the second tube plates (seal tube plates) 6 and 6 ′ to the frame members 4, 7 and 4 ′ and 7 ′ and the fixed support are shown. The portion up to the cell tube 1 joined to the tube plate at a position adjacent to the end is formed in a wave shape 6a, 6'a to give flexibility to the deformation of the tube plate due to thermal expansion. Are denoted by the same reference numerals, and description thereof is omitted. Due to the flexibility of the second tube sheet (seal tube sheet), the vertical load and the load applied due to the thermal expansion of the tube sheet are reduced, so that the cell tube is deformed by the deformation of the seal tube sheet in the press-fitting portion of the cell tube. As a result, a situation in which the load applied to the surface becomes small and a local gap is generated in the fitting portion is prevented, and the sealing function is improved. The vertical load is mostly borne by the first tube sheet.

  3 and 4 are diagrams for explaining a joint portion between the cell tube and the tube sheet. Such a joint method is disclosed in Patent Document 2 filed by the same applicant as the present invention. Explained. In FIG. 3, the hole for press-fitting the cell tube of the tube sheet 5 is formed in a shape barnacle (Fuji-an) shape that narrows toward the tip side of the cell tube. The cell tube 1 is joined to the tube plate 5 by the edge of the hole tightening the cell tube 1.

  In FIG. 4, the ring member 31 is bonded to the cell tube 1 with an adhesive 32, and the ring member 31 is joined to the cell tube 1 by an interference fit at the edge of a barnacle (Fujitsumi) -shaped hole of the tube plate 1. As the adhesive 32, an inorganic adhesive having appropriate heat resistance and adhesive strength is used. When shot peening is applied to the inner diameter of the ring, the adhesive strength of the adhesive is improved. As shown in FIGS. 3 and 4, the barnacle (Fuji-an) -shaped hole is formed so as to be narrowed toward the distal end side of the cell tube, thereby facilitating the insertion of the cell tube. That is, the tip end side of the cell tube can be easily press-fitted from the rounded surface side of the barnacle (Fuji Aoi) -shaped hole.

  FIG. 5 is a local sectional view showing a header support structure through a cell tube according to a third embodiment of the present invention. In the figure, 2 is an upper header, and the upper header 2 includes an upper first tube plate 12, an upper second tube plate 6, and a frame member (reference numeral omitted). Reference numeral 2 'denotes a lower header. The lower header 2' includes a lower first tube plate 13, a lower second tube plate 6 ', and a frame member (reference numeral omitted). 11 is a cell tube. In this embodiment, the upper and lower tip portions of the cell tube 11 are formed with small diameters 11a and 11b, and the upper small diameter portion 11a passes through the hole of the upper first tube plate 12 to fit the upper first tube plate. The peripheral surface of the joint hole is in contact with the shoulder of the diameter step portion where the upper end portion of the cell tube has a small diameter, the lower small diameter portion 11b penetrates the hole of the lower first tube plate 13, and the lower end portion of the cell tube has a small diameter. The shoulder of the diameter step portion that is in contact with the peripheral surface of the fitting hole of the lower first tube sheet 13.

  In FIG. 5, the holes through which the small-diameter portions 11 a and 11 b of the cell tube 11 of the upper first tube plate 12 and the lower first tube plate 13 pass are each formed in a barnacle (Fuji 壷) shape constricted toward the center side of the cell tube 11. However, it may be formed in a simple hole. When the tube plate is formed of a thin plate, the rigidity of the tube plate can be increased by forming each hole in a barnacle shape. If an appropriate gap is provided between the holes of the upper first tube plate 12 and the lower first tube plate 13 and the small diameter portions 11a and 11b of the cell tube, the peripheral surface of the fitting hole of the tube plates 12 and 13 is the cell. The cell tube 11 is not restrained by merely contacting the shoulder of the stepped diameter portion of the tube 11. Therefore, even if the tube sheets 12 and 13 are thermally deformed, no force is exerted on the cell tube.

The holes through which the small diameter portions 11a and 11b of the cell tube 11 of the upper second tube plate 6 and the lower second tube plate 6 ′ pass are formed in a barnacle shape (Fujitsu), and the holes and the small diameter portions 11a of the cell tube 11 are formed. 11b is an interference fit, and the interference fit portion performs a sealing function.
According to such a configuration, the vertical load is carried through the shoulder portion of the cell tube 11 without receiving a force due to the thermal expansion of the tube sheet, and the sealing function is applied to the cell tube due to the thermal expansion. It is held by the second tube sheet 6, 6 'configured to reduce the force.

  Since it is difficult to ensure that all the hole portions of the first tube plate are in contact with the shoulders of the diameter step portions of many cell tubes, a specific cell tube, in particular, the first tube plate is used as a frame member. A cell tube arranged at a position closest to the fixed support end to be fixed may be formed to have the stepped portion of the diameter so as to carry a vertical load through the shoulder of the stepped portion.

  FIG. 6 is a partial cross-sectional view showing a header support structure through a cell tube according to a third embodiment of the present invention. In this embodiment, ring members 33 and 34 are fixed to the cell tube 11, and the outer diameters of the ring members 33 and 34 are formed in steps having a large diameter portion and a small diameter portion, and a shoulder portion of the diameter step portion. The other parts are the same as those in the fourth embodiment shown in FIG. Since the cell tube is made of porous ceramic, it is not always easy to accurately manufacture the position of the shoulder, and the current generated by the fuel cell formed on the outer periphery of the cell tube is used as the shoulder. The structure of passing through the section and leading to the tip side of the cell tube must be complicated, but in these respects, according to the fourth embodiment, the cell tube can be more easily manufactured. Also in this case, a ring member having a diameter step portion may be fixed only to a specific cell tube so as to have a support function. For fixing the ring members 33, 34 to the cell tube 1, an inorganic adhesive having appropriate heat resistance and adhesive strength is used.

  FIG. 7 is a plan view showing a fixed end portion shape of a frame member for fixing the peripheral edge portion of the tube plate according to the embodiment of the present invention, wherein 1 is a cell tube, 4 is a frame member, and 5 is a tube plate. This figure shows the case where the cell tube is arranged in 5 rows and 104 tubes. The shape of the frame member 4 fixed support end 4c for fixing and supporting the tube plate 5 is the same as that of the tube plate at a position adjacent to the fixed support end. A shape is formed along the outer periphery of the joined cell tube facing the fixed support end with a certain distance. In FIG. 10, which is a plan view in the case of the prior art, the shape of the frame member 4 fixed support end 4a is formed in a straight line. In this case, the distance from the linear fixed support end to the outer periphery of the cell tube located next to the fixed support end on the side facing the fixed support end is the joint portion of the cell tube and the tube plate, that is, the joint portion. It depends on the direction from the center of the cell tube. As described above, when the tube plate is bent by a certain amount in the vertical direction, the stress generated in the joint portion of the tube plate with the cell tube varies depending on the distance from the fixed support end to the joint portion of the cell tube and the tube plate. The smaller the distance, the smaller. Therefore, if this distance differs depending on the joining portion, the stress of the tube sheet at the joint portion with the cell tube, that is, the force that the cell tube receives from the tube plate also varies depending on the joining portion and becomes non-uniform.

  In this embodiment, as shown in FIG. 7, the shape of the fixed support end 4c of the support member that fixes and supports the peripheral edge of the tube plate of the frame member 4 is the fixed support of the cell tube located next to the fixed support end. It was made into the shape which followed a fixed distance and the outer periphery of the side which faces an end. As a result, the force applied from the tube sheet to the fixed support end side portion of the joint between the tube plate and the cell tube by the vertical load is made uniform, while the vertical load itself is the same, so there is no portion that receives particularly large force. . And the deformation | transformation of the joint hole part with the cell tube of a tube sheet is also equalized, and the nonuniformity of the interference fitting force by nonuniform deformation does not cause gas leakage from a junction part. In addition, the said fixed support end of a frame member is formed in the outer periphery of the side facing the said fixed support end of a cell tube so that a cell tube center angle may extend along about 120 degrees.

  In a fuel cell having a structure in which a cell tube of a cylindrical solid oxide fuel cell is used as a support member for the upper header and the lower header, a load caused by a vertical force applied to a joint portion between the cell tube and the tube sheet, and the header and the tube sheet The load caused by the difference in expansion due to the temperature difference can be reduced, and by providing a load-bearing tube plate that bears the vertical load and a seal tube plate that performs the sealing function, cell tube breakage and cell tube and tube plate Since the occurrence of gas leakage at the joint can be prevented, a highly reliable cylindrical solid oxide fuel cell can be provided.

It is a figure which shows schematic structure of the module of the solid oxide fuel cell which concerns on the 1st Example of this invention. It is a figure which shows schematic structure of the module of the solid oxide fuel cell which concerns on the 2nd Example of this invention. It is local sectional drawing of one Example which shows the joining form of the cell tube and tube sheet in a solid oxide fuel cell. It is a local sectional view of other examples showing a joined form of a cell tube and a tube sheet in a solid oxide fuel cell. It is local sectional drawing which shows the header support structure via the cell tube which concerns on the 3rd Example of this invention. It is local sectional drawing which shows the header support structure via the cell tube which concerns on the 4th Example of this invention. It is a top view which shows the fixed end part shape of the frame member which fixes and supports the peripheral part of the tube sheet which concerns on the Example of this invention. It is a figure which shows schematic structure of the conventional cylindrical solid oxide fuel cell to which this invention is applied. 1 is a perspective view of an internal module of a conventional cylindrical solid oxide fuel cell to which the present invention is applied. It is a top view equivalent to the X arrow view in FIG.

Explanation of symbols

1, 11 Cell tube 2 Upper header 2 'Lower header 3, 4, 7 Frame member 5, 12, 13 Tube plate (load-resistant tube plate)
6. Tube sheet (seal tube sheet)
8 Support stand 9 Heat insulation wall 10 Cover 21 Heat insulation member 31 Ring member 32 Adhesive 33, 34 Ring member

Claims (8)

A plurality of fuel battery cell tubes having fuel cells formed on the peripheral surface;
A first gas chamber for supplying fuel gas into the plurality of fuel cell tubes and a second gas chamber for discharging fuel gas that has been subjected to a power generation reaction in the fuel cells are oxidized to the fuel cells. In the solid oxide fuel cell, which is disposed separately from the third gas chamber for supplying the agent gas,
A tube plate that divides the first or second gas chamber (hereinafter referred to as a fuel gas chamber) and the third gas chamber is formed of a multiple tube plate that is composed of at least two tube plates and is supported on the fuel gas chamber side. In addition, in the tube plate fitting portion at both ends of the fuel cell tube inserted into the fuel gas chamber side from the multiple tube plate, an airtight function is provided on one tube plate side located on the fuel gas chamber side. A solid oxide fuel cell characterized in that the fitting portion shape or the tube plate thickness is made different so that the other tube plate located on the third gas chamber side has a cell support function. .   The distance from the fixed support end that fixes the peripheral edge of one tube plate located on the fuel gas chamber side to the fitting portion of the fuel cell tube closest to the fixed support end is located on the third gas chamber side. 2. The solid oxide according to claim 1, wherein the distance is longer than the distance from the fixed support end for fixing the other peripheral edge of the tube sheet to the fitting portion of the fuel cell tube closest to the fixed support end. Fuel cell.   2. The solid oxide fuel cell according to claim 1, wherein the thickness of one tube plate facing the fuel gas chamber is thinner than the other tube plate facing the third gas chamber.   The airtight function part of the said tube sheet fitting part is comprised by the said cell tube being inserted in the hole formed in the tube sheet, and being joined to the tube sheet by interference fitting, The structure of Claim 1 characterized by the above-mentioned. Solid oxide fuel cell.   The support function portion of the tube plate fitting portion is composed of a ring member fixed to the cell tube and an interference fitting portion in which the outer periphery of the ring member is inserted into a hole of the tube plate. The solid oxide fuel cell according to claim 4.   The support function part of the tube sheet fitting part is provided with a roller having a diameter stepped portion on the fuel cell tube side, and a fitting hole peripheral surface of the tube sheet is brought into contact with a shoulder of the diameter step part of the cell tube. 2. The solid oxide fuel cell according to claim 1, wherein the cell tube is supported.   The support function of the tube plate fitting portion is to fix a ring member provided with a diameter step portion at both ends of the fuel cell tube, and the fitting hole peripheral surface of the tube plate is connected to the diameter step portion of the ring member. 2. The solid oxide fuel cell according to claim 1, wherein the cell tube is supported by a roller brought into contact with the shoulder.   The shape of the fixed support end of the support member that fixes and supports the peripheral edge of the tube plate is formed on the outer periphery of the fuel cell tube that is joined to the tube plate at a position adjacent to the fixed support end on the side facing the fixed support end. 2. The solid oxide fuel cell according to claim 1, wherein the fuel cell has a shape along a certain distance.

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