Solid oxide type cell system

Abstract

To avoid a problem on layout of a gas pipe used in a solid oxide type cell system as well as appropriately absorb stress generated at the gas pipe.SOLUTION: A solid oxide type cell system comprises: a cell stack of a plurality of solid oxide type single cells being laminated; a combustion unit including a combustion section for combusting combustible gas; and one or more gas pipes connecting the cell stack with the combustion unit. The gas pipes include: a pipe member; flange member for connection with the cell stack or the combustion unit; and a coupling member that, on at least one end side of the pipe member, intervenes between the pipe member and the flange member so as to couple the members and has a thickness smaller than those of the pipe member and the flange member.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a solid oxide cell system.

Background Art

[0002] Conventionally, a structure for absorbing stress caused by dimensional errors, thermal expansion, etc. has been proposed for a gas pipe for flowing gas. For example, Patent Document 1 describes a structure for absorbing stress by providing a loop-shaped portion in a gas pipe.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a fuel cell stack composed of solid oxide cells operates at a high temperature, so it is necessary to form a gas pipe with a material having high temperature resistance. However, since such a material is hard and difficult to stretch, it is necessary to increase the bending radius of the gas pipe. Therefore, providing a loop-shaped portion like the gas pipe of Patent Document 1 may cause problems in layout.

[0005] The main object of the present disclosure is to appropriately absorb the stress generated in the gas pipe while avoiding problems in the layout of the gas pipe used in the solid oxide cell system.

Means for Solving the Problems

[0006] The present disclosure has adopted the following means to achieve the above main object.

[0007] The solid oxide cell system of the present disclosure is a cell stack in which a plurality of solid oxide single cells are stacked, and A combustion unit including a combustion part for burning a combustible gas, and one or more gas pipes connecting the cell stack and the combustion unit, and is provided with The gist is that the gas pipe includes a pipe member, a flange member for connecting to the cell stack or the combustion unit, and a connecting member interposed between at least one end side of the pipe member and the flange member to connect the pipe member and the flange member and having a thickness thinner than that of the pipe member and the flange member.

[0008] In the solid oxide fuel cell system of the present disclosure, as one or more gas pipes connecting the cell stack and the combustion unit, a gas pipe having a pipe member, a flange member for connecting to the cell stack or the combustion unit, and a connecting member interposed between at least one end side of the pipe member and the flange member to connect the pipe member and the flange member and having a thickness thinner than that of the pipe member and the flange member is provided. Thereby, the stress generated in the gas pipe can be absorbed by the connecting member, and it can be made unnecessary to provide a loop-shaped portion or the like in the gas pipe. Therefore, while suppressing an increase in the installation space of the gas pipe and avoiding problems in layout, the stress generated in the gas pipe can be appropriately absorbed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Best Mode for Carrying Out the Invention

[0010] Embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is an external perspective view of a fuel cell module 10. FIG. 2 is a schematic configuration diagram of the fuel cell module 10. In the present embodiment, the left-right direction (X-axis), the front-rear direction (Y-axis), and the up-down direction (Z-axis) are as shown in FIG. 1.

[0011] As shown in FIGS. 1 and 2, the fuel cell module 10 includes a fuel cell stack 11, an evaporation unit 14, a reforming unit 20, and a condenser 60. The fuel cell stack 11 generates electricity through an electrochemical reaction between hydrogen in the fuel gas and oxygen in the oxidant gas. The evaporation unit 14 evaporates the reformed water to generate water vapor. The reforming unit 20 reforms the raw fuel gas (e.g., natural gas or LP gas) by steam reforming to generate fuel gas. The fuel cell stack 11, the evaporation unit 14, and the reforming unit 20 are housed in a box-shaped module case 15 having heat insulation properties. The evaporation unit 14 is formed separately from the reforming unit 20 and is disposed above the reforming unit 20, but is not shown in FIG. 1. The condenser 60 is installed outside the module case 15.

[0012] The fuel cell module 10 constitutes a fuel cell system together with a raw fuel gas supply device, a reformed water supply device, an air supply device, and a hot water storage tank (not shown). The raw fuel gas supply device supplies the raw fuel gas to the evaporation unit 14 through the raw fuel gas supply pipe 30a. The reformed water supply device supplies the reformed water necessary for reforming the raw fuel gas into fuel gas (steam reforming) to the evaporation unit 14 through the reformed water supply pipe 30b. The air supply device supplies air as the oxidant gas through the air supply pipe 35. Further, the hot water storage tank recovers the heat generated in the fuel cell module 10 and stores hot water.

[0013] In this embodiment, the fuel cell stack 11 is configured as a flat-plate type solid oxide fuel cell stack in which a plurality of flat single cells 11a are stacked in the plate thickness direction. Each single cell 11a has an electrolyte such as zirconium oxide, and a fuel electrode and an oxidant electrode sandwiching the electrolyte. The fuel cell stack 11 is horizontally placed so that the stacking direction of the single cells 11a is the vertical direction, and end plates 12 are provided at both the upper and lower ends. Further, a fuel gas flow path is connected to the fuel electrode of each single cell 11a, and an oxidant gas flow path is connected to the oxidant electrode of each single cell 11a.

[0014] As shown in FIG. 2, the evaporation unit 14 is connected to a supply pipe 30 connected to the raw fuel gas supply pipe 30a and the reformed water supply pipe 30b, and the raw fuel gas supplied to the raw fuel gas supply pipe 30a and the reformed water supplied to the reformed water supply pipe 30b are introduced from the supply pipe 30. The evaporation unit 14 is filled with a plurality of spherical heat storage members having a high thermal conductivity inside, and when reformed water flows in while the heat storage member is heated, the reformed water is evaporated to generate water vapor. Note that materials such as alumina and stainless steel (for example, ferritic stainless steel) are used for the heat storage member. Further, the evaporation unit 14 preheats the introduced raw fuel gas. The mixed gas of the water vapor generated in the evaporation unit 14 and the preheated raw fuel gas is supplied to the reforming unit 20 (reforming section 22) through a mixed gas supply pipe 32 connected to the lower part of the evaporation unit 14.

[0015] As shown in FIG. 1, the reforming unit 20 is formed in a substantially cylindrical shape, and as shown in FIG. 2, it integrally houses a reforming section 22, a combustion section 23, and an air heat exchange section 24. The combustion section 23, the reforming section 22, and the air heat exchange section 24 (the combustion exhaust gas flow section 24a and the air flow section 24b) are formed in a bottomed cylindrical shape and arranged concentrically. The reforming unit 20 is arranged above the fuel cell stack 11 so as to face the flat surface of the fuel cell stack 11 (single cell 11a), and is formed in a size that fits within the projected area of the fuel cell stack 11 in a top view. Further, at the center of the upper wall of the reforming unit 20, an ignition device 25 is provided that extends into the combustion section 23 and ignites the inside of the combustion section 23. The ignition device 25 includes a discharge electrode (not shown).

[0016] In the combustion section 23, fuel off-gas as a combustible gas and an oxidant off-gas containing oxygen are supplied from below. Although not shown, the combustion section 23 has a fuel nozzle that injects fuel off-gas and a supply cylinder that is formed in a cylindrical shape so as to surround the periphery of the fuel nozzle and supplies the oxidant off-gas.

[0017] The reforming section 22 is formed in a bottomed cylindrical shape, and a reforming catalyst (not shown) such as an Ru-based or Ni-based reforming catalyst is disposed in the internal space with the outer wall of the combustion section 23 as the inner wall. Further, a mixed gas supply pipe 32 is connected to the upper part of the reforming section 22, and the mixed gas (raw fuel gas and water vapor) from the evaporation section 14 is supplied to the internal space through the mixed gas supply pipe 32. The reforming section 22 generates hydrogen gas and carbon monoxide by the reaction of the mixed gas (steam reforming reaction) by the reforming catalyst in the presence of heat from the combustion section 23. Further, the reforming section 22 generates hydrogen gas and carbon dioxide by the reaction of carbon monoxide and water vapor (carbon monoxide shift reaction) generated in the steam reforming reaction. As a result, the reforming section 22 generates a fuel gas containing hydrogen, carbon monoxide, carbon dioxide, water vapor, unreacted raw fuel gas, etc. The generated fuel gas flows from the lower part of the reforming section 22 through the fuel gas supply path 43 into the fuel gas flow path of each single cell 11a of the fuel cell stack 11 and is supplied to the fuel electrode.

[0018] The air heat exchange part 24 is formed in a bottomed cylindrical shape, and has a combustion exhaust gas flow part 24a through which the combustion exhaust gas generated in the combustion part 23 flows, and an air flow part 24b formed in a bottomed cylindrical shape through which the air supplied from the air supply pipe 35 flows. The combustion exhaust gas flow part 24a forms an internal space with the outer wall of the reforming part 22 as the inner wall. The combustion exhaust gas that has flowed through the combustion exhaust gas flow part 24a is supplied to the evaporation part 14 through the combustion exhaust gas supply pipe 37. The combustion exhaust gas supplied to the evaporation part 14 is heat-exchanged with the reformed water and the raw fuel gas in the evaporation part 14, and then is supplied to the condenser 60 through the combustion exhaust gas discharge pipe 39.

[0019] The air flow part 24b has the air supply pipe 35 connected to the upper part thereof, and forms an internal space with the outer wall of the combustion exhaust gas flow part 24a as the inner wall. The air flowing through the air flow part 24b is heated up by heat exchange with the combustion exhaust gas flowing through the combustion exhaust gas flow part 24a. Then, the air that has flowed through the air heat exchange part 24 is supplied as an oxidant gas from the side wall part of the air heat exchange part 24 to the fuel cell stack 11 through the gas supply pipe 50, and flows into the oxidant gas flow path of each single cell 11a and is supplied to the oxidant electrode. The details of the gas supply pipe 50 will be described later.

[0020] At the oxidant electrode of each single cell 11a, oxide ions (O 2- ) are generated, and the oxide ions permeate through the electrolyte and react with hydrogen or carbon monoxide at the fuel electrode to obtain electric energy. The input terminal of the power conditioner is connected to the output terminal of the fuel cell stack 11, and the generated power of the fuel cell stack 11 is converted into AC power by the power conditioner and supplied to the electrical load.

[0021] In each single cell 11a, the fuel gas that has not been used for the electrochemical reaction (power generation) (hereinafter referred to as "fuel off-gas") is supplied to the combustion section 23 through the fuel off-gas supply passage 45. Also, in each single cell 11a, the oxidant gas that has not been used for the electrochemical reaction (power generation) (hereinafter referred to as "oxidant off-gas") is supplied to the combustion section 23 through the oxidant off-gas supply passage 47. The fuel off-gas is a combustible gas containing fuel components such as hydrogen and carbon monoxide, and is mixed with the oxidant off-gas containing oxygen in the combustion section 23. Then, the ignition device 25 ignites the mixed gas of the fuel off-gas and the oxidant off-gas to burn the mixed gas. When the mixed gas burns, combustion heat necessary for the operation of the fuel cell stack 11, preheating of the raw fuel gas and generation of steam in the evaporation section 14, steam reforming reaction in the reforming section 22, etc. is generated. In the present embodiment, a reflux pipe 49 is provided that branches from the fuel off-gas supply passage 45 to reflux a part of the fuel off-gas to the raw fuel gas supply pipe 30a.

[0022] The combustion exhaust gas generated by the combustion of the mixed gas in the combustion section 23 passes through the air heat exchange section 24 (combustion exhaust gas flow section 24a) of the reforming unit 20 and is supplied from the combustion exhaust gas supply pipe 37 to the evaporation section 14. The combustion exhaust gas supplies the heat necessary for steam reforming, the heat necessary for raising the temperature of the oxidant gas (air), and the heat necessary for the generation of steam, respectively, and then reaches the condenser 60 through the combustion exhaust gas discharge pipe 39. Then, the combustion exhaust gas supplied to the condenser 60 is cooled by heat exchange with the hot water from the hot water storage tank, and at least a part of the water vapor contained in the combustion exhaust gas is removed, and then discharged into the atmosphere. Also, the water obtained by condensing the water vapor contained in the combustion exhaust gas is stored in the reformed water tank and used as reformed water.

[0023] Hereinafter, the supply passages of the respective gases between the fuel cell stack 11 and the reforming unit 20, that is, the fuel gas supply passage 43, the fuel off-gas supply passage 45, the oxidant off-gas supply passage 47, and the gas supply pipe (oxidant gas pipe) 50 as the oxidant gas supply passage will be described.

[0024] The fuel gas supply passage 43 includes a gas supply pipe (fuel gas pipe) 43a whose upper end is connected to the lower part of the reforming section 22, and a plate flow passage 43b formed in the flow path forming plate 41. The fuel off-gas supply passage 45 includes a gas supply pipe (fuel off-gas pipe) 45a whose upper end is connected to the lower part of the combustion section 23, and a plate flow passage (not shown) formed in the flow path forming plate 41. The oxidant off-gas supply passage 47 includes a gas supply pipe (oxidant off-gas pipe) 47a whose upper end is connected to the lower part of the combustion section 23, and a plate flow passage 47b formed in the flow path forming plate 41. The flow path forming plate 41 is composed of two metal plates such as ferritic stainless steel. Each metal plate has a flow path groove recessed in a concave shape by press working, and the plate flow passages are formed by welding the metal plates in a superposed state such that a part of the flow path grooves communicate with each other.

[0025] Also, a holding plate 42 having three through holes formed thereon is fastened to the flow path forming plate 41 by fastening members. The holding plate 42 is fastened to the flow path forming plate 41 with the gas supply pipes 43a, 45a, 47a inserted through the respective through holes, thereby holding the flange members (not shown) at the lower ends of the gas supply pipes 43a, 45a, 47a so as to sandwich them between the flow path forming plate 41. As a result, the lower end of the gas supply pipe 43a is connected to the plate flow passage 43b, the lower end of the gas supply pipe 45a is connected to the plate flow passage of the fuel off-gas supply passage 45, and the lower end of the gas supply pipe 47a is connected to the plate flow passage 47b. Thus, in this embodiment, the three gas flow passages (the three gas supply pipes 43a, 45a, 47a) of the fuel gas supply passage 43, the fuel off-gas supply passage 45, and the oxidant off-gas supply passage 47 have a manifold structure integrally formed by the flow path forming plate 41 and the holding plate 42. Note that the gas supply pipe 50 for the oxidant gas is configured independently of those gas supply passages without being held by the holding plate 42.

[0026] As shown in FIGS. 3 to 5, the gas supply pipe 50 is composed of a pipe member 51, a first flange member 52, a first connecting member 53, a second flange member 54, a socket member 55, and a second connecting member 56. In this embodiment, each member 51 to 56 of the gas supply pipe 50 is formed of a metal material such as ferritic stainless steel containing aluminum (Al).

[0027] The pipe member 51 has a horizontally extending portion 51a that extends in the horizontal direction and is connected to the reforming unit 20 (air flow portion 24b), and a vertically extending portion 51b that extends in the vertical direction and is connected to the fuel cell stack 11. The pipe member 51 is formed in an inverted L shape bent so that the horizontally extending portion 51a and the vertically extending portion 51b are orthogonal to each other.

[0028] The first flange member 52 is a rectangular flat plate member with R-processed corners. A central hole 52a communicating with the pipe member 51 is formed at the center of the plate surface, and four insertion holes 52b through which fastening members such as bolts B (see FIG. 1) are inserted are formed near the four corners. Each insertion hole 52b has an inner diameter with a margin with respect to the outer diameter of the fastening member, and is further formed to be longer in the circumferential direction (the dotted line direction in FIG. 4) than in the radial direction centered on the axial center of the pipe member 51. That is, each insertion hole 52b is an elongated hole (elliptical hole) having a longitudinal direction and a short direction orthogonal to the longitudinal direction, and the short direction is formed to be the radial direction centered on the central hole 52a. The first connecting member 53 is an annular thin plate member formed with a central hole 53a through which the pipe member 51 can be inserted, and having an outer diameter that fits between the central hole 52a and the insertion holes 52b of the first flange member 52.

[0029] The second flange member 54 is, like the first flange member 52, a rectangular flat plate member with rounded corners at the four corners, and is formed with a central hole 54a communicating with the pipe member 51 and four insertion holes 54b through which fastening members such as bolts B (see FIG. 1) are inserted. Each insertion hole 54b, like the insertion hole 52b, has an inner diameter with a margin with respect to the outer diameter of the fastening member, and is a long hole formed so as to be longer in the circumferential direction than in the radial direction centered on the axial center of the pipe member 51. The socket member 55 is a stepped tubular member having a large-diameter portion 55a and a small-diameter portion 55b, and is provided at the end (lower end) of the longitudinally extending portion 51b of the pipe member 51. The socket member 55 is formed such that the inner diameter of the large-diameter portion 55a allows the pipe member 51 to be inserted, while the inner diameter of the small-diameter portion 55b does not allow the pipe member 51 to be inserted. The second connecting member 56 is an annular thin plate member formed with a central hole 56a through which the small-diameter portion 55b of the socket member 55 can be inserted, and having an outer diameter that fits between the central hole 54a and the insertion holes 54b of the second flange member 54.

[0030] The assembly of the gas supply pipe 50 is performed, for example, as follows. FIG. 6 is an explanatory view showing the configuration during the assembly of the gas supply pipe 50. The gas supply pipe 50 is assembled by separately assembling the upper portion 50U and the lower portion 50L, and then assembled to the fuel cell stack 11 and the reforming unit 20. In this embodiment, when the gas supply pipe 50 is assembled, the manifold structure of the fuel gas supply path 43, the fuel off-gas supply path 45, and the oxidant off-gas supply path 47, which have been described above, has already been assembled to the fuel cell stack 11 and the reforming unit 20, and the respective supply paths 43, 45, 47 are in a formed state.

[0031] The upper part 50U is assembled by joining the pipe member 51, the first connecting member 53, and the first flange member 52. The first connecting member 53 is joined to the lateral extension part 51a of the pipe member 51 by welding with the end part (lateral end part) of the lateral extension part 51a of the pipe member 51 inserted into the central hole 53a. Also, the first flange member 52 is joined to the first connecting member 53 by welding in a state where the central hole 52a is positioned so as to align with the central hole 53a of the first connecting member 53 (the axial center of the lateral extension part 51a of the pipe member 51). That is, the first connecting member 53 connects the pipe member 51 and the first flange member 52 by being joined to both of them between the two.

[0032] The lower part 50L is assembled by joining the socket member 55, the second connecting member 56, and the second flange member 54. The second connecting member 56 is joined to the socket member 55 by welding with the small-diameter part 55b of the socket member 55 inserted into the central hole 56a. Also, the second flange member 54 is joined to the second connecting member 56 by welding in a state where the central hole 54a is positioned so as to align with the central hole 56a of the second connecting member 56 (the axial center of the socket member 55). That is, the second connecting member 56 connects the socket member 55 and the second flange member 54 by being joined to both of them between the two.

[0033] The thus-assembled lower part 50L is arranged so that a gasket (not shown) is sandwiched between it and the flange member 13 (see FIG. 1) of the fuel cell stack 11, and fastening members such as bolts B are inserted into the respective insertion holes 54b and temporarily tightened to the fastening holes (not shown) of the flange member 13. As described above, since each insertion hole 54b is an oblong hole with an inner diameter having a margin for the fastening member, the lower part 50L can be translated in the X-axis direction or the Y-axis direction or rotated around the Z-axis in a state where the fastening member is temporarily tightened.

[0034] Next, while inserting the end portion (lower end portion) of the longitudinally extending portion 51b of the pipe member 51 into the socket member 55 (large-diameter portion 55a) of the lower portion 50L, the first flange member 52 is sandwiched between the flange member 21 (see FIG. 1) of the reforming unit 20 with a gasket (not shown). In this state, a fastening member such as a bolt B is inserted through each insertion hole 52b and temporarily tightened to a fastening hole (not shown) of the flange member 21. As described above, since each insertion hole 52b is an elongated hole with an inner diameter having a margin for the fastening member, the upper portion 50U can be translated in the X-axis direction or the Z-axis direction or rotated about the Y-axis in a state where the fastening member is temporarily tightened. Note that the height of the socket member 55 (large-diameter portion 55a) is determined so that the end portion of the longitudinally extending portion 51b of the pipe member 51 does not come off from the socket member 55 even when the upper portion 50U is translated in the Z-axis direction.

[0035] Then, while absorbing the displacement caused by dimensional errors or assembly errors of each part of the gas supply pipe 50 with the insertion holes 52b and 54b of the first flange member 52 and the second flange member 54, each fastening member is fastened. As described above, since translation in the X-axis direction, the Y-axis direction, and the Z-axis direction and rotation about the Y-axis and the Z-axis are possible, parallel displacement in each axis direction and rotational displacement about the Y-axis and the Z-axis can be absorbed. Note that the rotational displacement about the X-axis that cannot be absorbed by the insertion holes 52b and 54b is absorbed by the first connecting member 53 and the second connecting member 56 as follows. When each fastening member is fastened to connect the first flange member 52 to the flange member 21 and the second flange member 54 to the flange member 13, the large-diameter portion 55a (upper edge) of the socket member 55 and the longitudinally extending portion 51b of the pipe member 51 are joined by welding. In this way, the gas supply pipe 50 is assembled.

[0036] Here, among the members of the gas supply pipe 50, the thickness t1 of the first connecting member 53 and the second connecting member 56 is formed to be the thinnest. Also, in this embodiment, the thickness t3 of the first flange member 52 and the second flange member 54 is the thickest, and next, the thickness t2 of the pipe member 51 and the socket member 55 is thick. That is, in this embodiment, the thickness t3 > thickness t2 > thickness t1. Also, although not particularly limited, for example, the thickness t3 is 1.5 mm, the thickness t2 is 0.8 mm, the thickness t1 is 0.4 mm, and so on.

[0037] By doing so, the first connecting member 53 and the second connecting member 56 can be made more deformable than the pipe member 51, the first flange member 52, the socket member 55, and the second flange member 54. Thereby, the stress due to misalignment or thermal expansion during the assembly of the gas supply pipe 50 can be absorbed by the deformation of the first connecting member 53 and the second connecting member 56. That is, the rotational misalignment around the X-axis that cannot be absorbed by each insertion hole 52b, 54b can be absorbed by the first connecting member 53 and the second connecting member 56. For this reason, the first connecting member 53 and the second connecting member 56 are also referred to as the first stress absorbing member and the second stress absorbing member, respectively. In this way, since the stress can be absorbed by the first connecting member 53 and the second connecting member 56, deformation due to excessive stress acting on the first flange member 52 and the second flange member 54 can be suppressed. Also, deformation can be suppressed by making the first flange member 52 and the second flange member 54 the thickest to increase rigidity. From these things, it is possible to suppress the surface pressure distribution to the respective seal members from becoming non-uniform from the first flange member 52 and the second flange member 54, and suppress the seal performance from being impaired.

[0038] In the fuel cell module 10 of the present embodiment described above, a gas supply pipe 50 connected to the fuel cell stack 11 and the reforming unit 20 is provided. The gas supply pipe 50 includes a pipe member 51, a first flange member 52 for connecting to the reforming unit 20, and a first connecting member 53 thinner than the pipe member 51 and the first flange member 52. Further, the gas supply pipe 50 includes a second flange member 54 for connecting to the fuel cell stack 11 and a second connecting member 56 thinner than the pipe member 51 and the second flange member 54. Therefore, the stress generated in the gas supply pipe 50 can be absorbed by the first connecting member 53 and the second connecting member 56, and it can be assumed that there is no need to provide a loop-shaped portion or the like to absorb the stress. Accordingly, while suppressing an increase in the installation space of the gas supply pipe 50 and avoiding layout problems, the stress generated in the gas supply pipe 50 can be appropriately absorbed.

[0039] In addition, the pipe member 51 is formed in a bent shape such that a laterally extending portion 51a connected to the reforming unit 20 and a longitudinally extending portion 51b connected to the fuel cell stack 11 are orthogonal to each other. A plurality of insertion holes 52b, 54b through which fastening members are inserted are formed in the first flange member 52 and the second flange member 54, and each of the insertion holes 52b, 54b is formed to be longer in the circumferential direction than in the radial direction centered on the axial center of the pipe member 51. Therefore, the rotational displacement in the circumferential direction (rotational displacement around the Y-axis and the Z-axis) centered on the axial center of the pipe member 51 can be absorbed by the insertion holes 52b, 54b. Accordingly, it is not necessary to enlarge the first connecting member 53 and the second connecting member 56 so as to absorb the rotational displacement in all rotational directions. Further, since each of the insertion holes 52b, 54b has an inner diameter with a margin with respect to the fastening member, the parallel displacement in each axial direction can be absorbed. Accordingly, it is not necessary to enlarge the first connecting member 53 and the second connecting member 56 so as to absorb the parallel displacement. From these facts, since the first connecting member 53 and the second connecting member 56 only need to be able to absorb the rotational displacement around the X-axis, it is possible to prevent their sizes from becoming excessively large. For this reason, since it is not necessary to enlarge the first flange member 52 and the second flange member 54 either, it is possible to suppress an increase in the size of the gas supply pipe 50.

[0040] In addition, in the present embodiment, as the gas pipes, there are provided a gas supply pipe 43a for supplying fuel gas to the fuel electrode of the fuel cell stack 11, a gas supply pipe 50 for supplying oxidant gas to the oxidant electrode of the fuel cell stack 11, a gas supply pipe 45a for supplying fuel off-gas as combustible gas from the fuel electrode of the fuel cell stack 11 to the combustion section 23, and a gas supply pipe 47a for supplying oxidant off-gas from the oxidant electrode of the fuel cell stack 11 to the combustion section 23. The reforming unit 20 includes an air heat exchange section 24 that exchanges heat between the combustion heat of the combustion section 23 and the flowing gas (air). The gas supply pipe 50 having the first connecting member 53 and the second connecting member 56 is a supply pipe for oxidant gas connected to the air heat exchange section 24 and the fuel cell stack 11. Therefore, even if a situation occurs where the stress cannot be sufficiently absorbed due to deterioration or deformation of the gas supply pipe 50 and the sealing performance deteriorates, it can be limited to air leakage and the influence can be minimized.

[0041] In addition, a holding plate 42 for integrally holding the gas supply pipes 43a, 45a, and 47a is provided, and the gas supply pipe 50 is configured to connect the fuel cell stack 11 and the reforming unit 20 without being held by the holding plate 42. Thereby, the gas supply pipes 43a, 45a, and 47a can be collectively and compactly arranged between the fuel cell stack 11 and the reforming unit 20. On the other hand, in the gas supply pipes 43a, 45a, and 47a that are integrally held, it is difficult to absorb misalignment during assembly. Therefore, it is highly significant to provide the first connecting member 53 and the second connecting member 56 to the gas supply pipe 50 that is not held by the holding plate 42 to absorb misalignment.

[0042] Further, the gas supply pipe 50 is formed such that the pipe member 51, the first flange member 52 and the second flange member 54, and the first connecting member 53 and the second connecting member 56 use the same material and the thicknesses of the first connecting member 53 and the second connecting member 56 are the thinnest. Therefore, it is possible to appropriately absorb the stress generated in the gas supply pipe 50 while suppressing the thermal expansion difference with respect to the temperature change in each member and maintaining good joining.

[0043] In the above-described embodiment, the first connecting member 53 and the second connecting member 56 are provided at both ends of the pipe member 51. However, the present invention is not limited to this, and a connecting member may be provided at at least one end of the pipe member 51, and a connecting member may not be provided at the other end of the pipe member 51. Further, the second connecting member 56 is joined to the pipe member 51 via the socket member 55. However, the socket member 55 may not be provided, and the second connecting member 56 may be joined to the pipe member 51.

[0044] In the embodiment, the gas supply pipe 50 used for supplying air as the oxidant gas is exemplified. However, the present invention is not limited to this, and it may be used for supplying any one of the fuel gas, the fuel off-gas, and the oxidant off-gas. Further, at least one of the four supply paths may be configured like the gas supply pipe 50, and a plurality of two or more may be configured like the gas supply pipe 50.

[0045] In the embodiment, the insertion holes 52b and 54b of the first flange member 52 and the second flange member 54 are formed to be longer in the circumferential direction than in the radial direction centered on the axial center of the pipe member 51. However, only one of the insertion holes 52b and 54b may be formed in this way. Further, both of the insertion holes 52b and 54b may be formed in a perfect circle shape without being formed in this way.

[0046] In the embodiment, the first flange member 52 and the second flange member 54 are made thicker than the pipe member 51 (socket member 55). However, the present invention is not limited to this, and the thickness t2 of the pipe member 51 and the thickness t3 of the first flange member 52 and the second flange member 54 may be the same thickness. That is, the relationship of thickness t3 ≧ thickness t2 > thickness t1 may be sufficient. Note that each member 51 to 56 of the gas supply pipe 50 is formed of the same material. However, the first connecting member 53 and the second connecting member 56 may be formed of a material that is more easily deformable.

[0047] In the embodiment, as the gas flow path other than the gas supply pipe 50, the plate flow path formed by the flow path forming plate 41 and the like are exemplified, but the present invention is not limited thereto, and the flow path may be formed using only the gas pipe. Further, the pipe member 51 has a shape bent at a right angle, but the present invention is not limited thereto, and the shape may be bent at an obtuse angle or a curved shape. Further, the pipe member 51 may have a straight shape without bending. When the shape is a straight shape, it may be configured like the gas supply pipe 150 of the modified example shown in FIG. 7. The gas supply pipe 150 can also be used when forming at least one of the fuel gas supply path 43, the fuel off-gas supply path 45, and the oxidant off-gas supply path 47 without using the flow path forming plate 41 or the holding plate 42.

[0048] The gas supply pipe 150 in FIG. 7 includes a pipe member 151 and a connecting member 154, and the connecting member 154 is joined to the flange member 113 of the fuel cell stack 11 by welding. That is, the connecting member 154 has the function of a flange member. The gas pipe provided with the flange member 113 is formed with a relief portion 113a having an inner diameter larger than the outer diameter of the pipe member 151 at the end. Therefore, the parallel displacement of the pipe member 151 in the Z-axis direction can be absorbed by the relief portion 113a. Further, similar to the embodiment, the stress generated in the pipe member 151 can be absorbed by the connecting member 154. When assembling the gas supply pipe 150 to the flange member 113, for example, the pipe member 151 may be positioned in the Z-axis direction, the pipe member 151 and the connecting member 154 may be joined by welding, and then the connecting member 154 and the flange member 113 may be joined by welding.

[0049] In the embodiment, the fuel cell stack 11 in which each cell performs a power generation operation of generating power by the reaction of a fuel gas and an oxidant gas has been exemplified, but the present invention is not limited thereto, and any structure in which a plurality of solid oxide type single cells are stacked may be used. For example, an electrolysis stack in which each cell performs an electrolysis operation of generating hydrogen and oxygen by electrolysis of water vapor may be used, or a reversible operating solid oxide type cell stack capable of both a power generation operation and an electrolysis operation may be used. Further, although the reforming unit 20 including the reforming section 22, the combustion section 23, and the air heat exchange section 24 has been exemplified as the combustion unit, the present invention is not limited thereto, and a structure including the combustion section 23 and the air heat exchange section 24 without including the reforming section 22 may be used, or a structure including only the combustion section 23 without including the reforming section 22 and the air heat exchange section 24 may be used. Further, the present invention is not limited to the gas supply pipe 50 used for supplying the oxidant gas (air) from the reforming unit 20 to the fuel cell stack 11, and any one of the gas pipes for the gas (off-gas) supplied from the combustion unit to the cell stack and the gas pipes for the gas supplied from the combustion unit to the cell stack may be configured as a gas pipe having a connecting member.

[0050] The correspondence between the main elements of the embodiment and the main elements of the present disclosure described in the column of means for solving the problems will be described. The fuel cell stack 11 of the embodiment corresponds to the "cell stack" of the present disclosure, the reforming unit 20 corresponds to the "combustion unit", the gas supply pipe 50 corresponds to the "gas pipe", the pipe member 51 corresponds to the "pipe member", the first flange member 52 and the second flange member 54 correspond to the "flange portion", and the first connecting member 53 and the second connecting member 56 correspond to the "connecting member".

[0051] Note that the correspondence between the main elements of the embodiment and the main elements of the present disclosure described in the column of means for solving the problems is an example for specifically explaining the mode for carrying out the present disclosure described in the column of means for solving the problems in the embodiment, and does not limit the elements of the present disclosure described in the column of means for solving the problems. That is, the interpretation of the present disclosure described in the column of means for solving the problems should be made based on the description in that column, and the embodiment is merely a specific example of the present disclosure described in the column of means for solving the problems.

[0052] As described above, the embodiments for carrying out the present disclosure have been explained. However, the present disclosure is not limited to such embodiments, and it goes without saying that it can be implemented in various forms without departing from the gist of the present disclosure.

Industrial Applicability

[0053] The present disclosure can be used in the manufacturing industry of solid oxide type cell systems and the like.

Explanation of Signs

[0054] 11 Fuel cell stack (cell stack), 20 Reformer unit (combustion unit), 23 Combustion section, 24 Air heat exchange section (heat exchange section), 42 Holding plate (holding member), 43a, 45a, 47a Gas supply pipe (gas pipe), 50 Gas supply pipe (gas pipe, specific gas pipe, gas pipe having a connecting member), 51 Pipe member, 52 First flange member (flange member), 52a, 54a Insertion hole, 53 First connecting member (connecting member), 54 Second flange member (flange member), 56 Second connecting member (connecting member).

Claims

1. A cell stack in which a plurality of solid oxide type single cells are stacked, A combustion unit including a combustion part for burning a combustible gas, One or more gas pipes connecting the cell stack and the combustion unit, Comprising, As the gas pipe, a pipe member, a flange member for connection with the cell stack or the combustion unit, and a connecting member interposed between at least one end side of the pipe member and the flange member so as to connect the pipe member and the flange member and having a thickness thinner than that of the pipe member and the flange member, A solid oxide type cell system.

2. The pipe member is formed in a bent shape such that a portion connected to the combustion unit and a portion connected to the cell stack are orthogonal to each other, The flange member is formed with a plurality of insertion holes through which fastening members are inserted, The insertion holes are formed to be longer in the circumferential direction than in the radial direction centered on the axial center of the pipe member, The solid oxide type cell system according to Claim 1.

3. As the gas pipe, a fuel gas pipe for supplying fuel gas to the fuel electrode of the cell stack, an oxidant gas pipe for supplying oxidant gas to the oxidant electrode of the cell stack, a fuel off-gas pipe for supplying fuel off-gas as the combustible gas from the fuel electrode of the cell stack to the combustion unit, and an oxidant off-gas pipe for supplying oxidant off-gas from the oxidant electrode of the cell stack to the combustion unit, The combustion unit includes a heat exchange part for exchanging heat between the combustion heat of the combustion part and the flowing gas, The gas pipe having the connecting member is the oxidant gas pipe connected to the heat exchange part and the cell stack, The solid oxide type cell system according to Claim 1 or 2.

4. Comprising a holding member for integrally holding the fuel gas pipe, the fuel off-gas pipe, and the oxidant off-gas pipe, The gas pipe having the connecting member is configured to connect the cell stack and the combustion unit without being held by the holding member, The solid oxide type cell system according to Claim 3.

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