JP2016081912A - Fuel manifold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel manifold used in the stack structure of a fuel battery, the fuel manifold being designed such that even after the fuel battery is operated for a long time, an introduction pipe is firmly joined and fixed to the wall of the fuel manifold.SOLUTION: A fuel manifold body 200 performs the function of supplying fuel gas in the internal space to each fuel gas passage of a plurality of fuel battery cells. The fuel manifold body 200 is provided with an introduction pipe 230 for introducing fuel gas into the internal space. While one end part of the introduction pipe 230 is inserted into a through-hole formed in a support plate 220 (the upper wall of the fuel manifold), the one end part is welded to the support plate 220 on the internal space side. Thereby, the introduction pipe 230 is joined and fixed to the support plate 220.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a fuel manifold used for a stack structure of a fuel cell.

  Conventionally, a “fuel manifold” provided with “a plurality of fuel cells each having a fuel gas flow path formed therein” is widely known (see, for example, Patent Document 1). The fuel manifold functions to supply the fuel gas in the internal space to the fuel gas flow paths of the plurality of fuel cells.

Japanese Patent No. 5162724

  The fuel manifold described in the above document is provided with an introduction pipe for introducing fuel gas into the internal space of the fuel manifold. This introduction pipe is joined and fixed to the wall of the fuel manifold (in the example described in the above document, the upper wall). However, the above document does not describe how to join and fix the introduction pipe to the wall of the fuel manifold. Even after the fuel cell has been operated for a long time, there is a demand for a fuel manifold that can maintain a state where the introduction pipe is firmly joined and fixed to the wall of the fuel manifold.

  As described above, the present invention is a fuel manifold used in a fuel cell stack structure, and the state where the introduction pipe is firmly joined and fixed to the wall of the fuel manifold even after the fuel cell has been operated for a long time. It aims to provide what can be maintained.

  The fuel manifold according to the present invention is characterized in that the introduction pipe is inserted into a through-hole formed in the wall of the fuel manifold body, and is located in the internal space of the fuel manifold body. To be joined and fixed to the wall.

  Here, it is preferable that the introduction pipe is joined and fixed to the wall by welding on the inner space side with respect to the wall. In this case, the bonding material is composed of the melted introduction pipe and / or the wall material. The introduction pipe may be joined and fixed to the wall by brazing using a metal material (alloy, brazing, material having a melting point lower than that of the introduction pipe and the wall) as the joining material.

  According to the above feature, a “metal material” is used as the material of the “joining material” used for joining the introduction pipe. Therefore, for example, as compared with the case where “glass material” or the like is used as the material of the “bonding material”, the introduction tube can be bonded and fixed more firmly.

  In addition, according to the above feature, the “joining material” used for joining the introduction pipe is located in the internal space of the fuel manifold body. Here, during the operation of the fuel cell, the fuel gas flows in the internal space of the fuel manifold body, so that the internal space of the fuel manifold body is maintained in a reducing atmosphere. Accordingly, during operation of the fuel cell, the atmosphere surrounding the “joining material” is maintained in a reducing atmosphere. In a reducing atmosphere, the “metal material” is not easily oxidized. Therefore, according to the above feature, even after the fuel cell is operated for a long time, the “joining material” is not easily oxidized, and therefore “decrease in the joining strength of the joining material” due to the oxidation hardly occurs. As described above, according to the above feature, even after the fuel cell has been operated for a long time, the state where the introduction pipe is firmly joined and fixed to the wall of the fuel manifold body can be maintained.

It is a perspective view showing one cell used for a stack structure of a fuel cell in which a fuel manifold according to an embodiment of the present invention is used. It is a figure for demonstrating the operation state of the cell shown in FIG. 1 is a perspective view of an entire stack structure of a fuel cell in which a fuel manifold according to an embodiment of the present invention is used. FIG. 4 is an overall perspective view of the fuel manifold shown in FIG. 3. It is an enlarged view of the insertion hole formed in the support plate (upper wall) shown in FIG. It is the cross-sectional view which showed the mode of the junction part of an insertion hole and the one end part of a cell. It is the longitudinal cross-sectional view which showed the mode of the junction part of an insertion hole and the one end part of a cell. It is the figure which showed a mode that fuel gas and air were supplied / discharged with respect to the stack | stuck structure shown in FIG. It is sectional drawing which showed an example of a mode that the introduction pipe was joined and fixed to the wall of the fuel manifold. FIG. 6 is a cross-sectional view showing another example of a state in which an introduction pipe is joined and fixed to a wall of a fuel manifold. FIG. 6 is a cross-sectional view showing another example of a state in which an introduction pipe is joined and fixed to a wall of a fuel manifold. FIG. 6 is a cross-sectional view showing another example of a state in which an introduction pipe is joined and fixed to a wall of a fuel manifold. It is a perspective view of the whole stack structure of a fuel cell using an upper lid concerning a modification of an embodiment of the present invention. FIG. 14 is a cross-sectional view showing an example of a state in which the introduction pipe is joined and fixed to the wall of the upper lid in the stack structure shown in FIG. 13. FIG. 14 is a cross-sectional view showing another example of a state in which the introduction pipe is joined and fixed to the wall of the upper lid in the stack structure shown in FIG. 13.

(Example of cell configuration used for stack structure)
First, an example of a cell 100 used in a stack structure of a solid oxide fuel cell (SOFC) in which a fuel manifold according to an embodiment of the present invention is used will be described with reference to FIGS. .

  A cell 100 shown in FIG. 1 is electrically connected in series to the upper and lower surfaces (main surfaces (planes) on both sides parallel to each other) of a flat plate-like support substrate 10 having a longitudinal direction (x-axis direction). A plurality (four in this example) of power generation element portions A are so-called “horizontal stripe type” in which they are arranged at predetermined intervals in the longitudinal direction.

  The shape of the entire cell 100 as viewed from above is, for example, a side length L1 in the longitudinal direction (x-axis direction) of 50 to 500 mm and a length L2 in the width direction (y-axis direction) orthogonal to the longitudinal direction is 10. It is a rectangle of ˜100 mm (L1> L2). A thickness L3 (distance in the z-axis direction) of the cell 100 is 1 to 5 mm (L2> L3).

  The cell 100 includes a support substrate 10. The support substrate 10 is a flat plate-like fired body made of a porous material having no electronic conductivity. A plurality (six in this example) of fuel gas passages 11 (through holes) extending in the longitudinal direction are formed in the support substrate 10 at predetermined intervals in the width direction. The support substrate 10 can be made of, for example, CSZ (calcia stabilized zirconia).

Each power generating element portion A disposed on each of the upper and lower surfaces of the support substrate 10 is a laminated fired body in which a fuel electrode, a solid electrolyte membrane, and an air electrode are laminated at least in this order. The fuel electrode can be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). The solid electrolyte membrane can be made of, for example, YSZ (8YSZ) (yttria stabilized zirconia). The air electrode can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite).

As shown in FIG. 2, the fuel gas (hydrogen gas or the like) flows through the fuel gas flow path 11 of the support substrate 10 and the upper and lower surfaces of the support substrate 10 with respect to the “horizontal stripe” cell 100 shown in FIG. By flowing a gas (such as air) containing oxygen along the line, an electromotive force is generated in each power generating element portion A due to an oxygen partial pressure difference generated between the front and back surfaces of the solid electrolyte membrane. Further, when the cell 100 is connected to an external load, chemical reactions shown in the following formulas (1) and (2) occur, and current flows in the cell 100 (power generation state). In this power generation state, power is extracted from the cell 100.
(1/2) · O ₂ + 2e ⁻ → O ₂ ⁻ (in the air electrode) (1)
H ₂ + O ₂ ⁻ → H ₂ O + 2e ⁻ (in the fuel electrode) (2)

(Example of overall structure of stack structure)
Next, a stack structure of a solid oxide fuel cell (SOFC) according to an embodiment of the present invention using the above-described cell 100 will be described. As shown in FIG. 3, the stack structure includes a large number of cells 100 and a fuel manifold 20 that is a manifold for supplying fuel gas to each of the large number of cells 100. The fuel manifold 20 is a rectangular parallelepiped housing having a longitudinal direction (z-axis direction).

  The fuel manifold 20 is configured to be provided with a plurality of cells 100 each having a gas flow path 11 formed therein. The fuel manifold 20 is configured to supply fuel gas to the gas flow paths 11 of the plurality of cells 100. The fuel manifold 20 includes a fuel manifold main body 200, an introduction pipe 230, and a bonding material 240 (see FIG. 9).

  The fuel manifold body 200 has a wall that defines an internal space. For example, the fuel manifold main body 200 has a base 210 and a support plate 220 as the walls. The base 210 includes a bottom wall and a side wall, and opens upward. The support plate 220 is disposed on the base 210 and closes the opening. The support plate 220 has a flat plate shape. This support plate 220 constitutes the upper wall of the fuel manifold body 200. The support plate 220 has a function of supporting a large number of cells 100. The base 210 and the support plate 220 are made of, for example, stainless steel. An inner space of the fuel manifold body 200 is defined by the bottom and side walls of the base 210 and the support substrate 220.

  As shown in FIGS. 3 and 4, the introduction pipe 230 is a member for introducing fuel gas into the internal space of the fuel manifold body 200. In the example shown in FIGS. 3 and 4, the introduction tube 230 is joined and fixed to the support plate 220 so as to protrude upward (in the positive x-axis direction) from one of the four corners of the support plate 220. ing. The introduction pipe 230 is also made of, for example, stainless steel. The introduction pipe 230 and the fuel manifold body 200 employ different types of stainless steel. The thermal expansion coefficient of the introduction pipe 230 and the thermal expansion coefficient of the fuel manifold body 200 are also different from each other. For example, the thermal expansion coefficient of the introduction pipe 230 is larger than the thermal expansion coefficient of the fuel manifold body 200. For example, the introduction pipe 230 is made of alumina-formed stainless steel, and the fuel manifold body 200 is made of chromia-formed stainless steel. More specifically, the introduction pipe 230 is at least one selected from the group consisting of NCA-1 made by Nisshin Steel, NSSC-21M made by Nippon Steel & Sumikin Stainless, and JFE18-3USR made by JFE Steel. The fuel manifold body 200 is at least one selected from the group consisting of ZMG232L manufactured by Hitachi Metals, Crofer22APU manufactured by DyssenKrupp (Germany), and general-purpose ferritic stainless steel (for example, SUS440). The joining and fixing of the introduction pipe 230 will be described in detail later.

  Each cell 100 protrudes upward (in the x-axis positive direction) from the support plate 220, and the plurality of cells 100 are separated from each other along the longitudinal direction (z-axis direction) of the fuel manifold body 200. The end (one end) on the fuel gas inflow side in the longitudinal direction (x-axis direction) of the support substrate 10 in each cell 100 is bonded to the support plate 220 using a bonding material so as to be aligned in a stack. It is supported. The end (other end) on the fuel gas discharge side in the longitudinal direction (x-axis direction) of the support substrate 10 in each cell 100 is a free end. Therefore, this stack structure can be expressed as a “cantilever stack structure”.

  As shown in FIG. 4, a large number of insertion holes 221 communicating with the internal space of the fuel manifold body 200 are formed in the support plate 220 (upper wall of the fuel manifold body 200) at intervals in the z-axis direction. Yes. Each insertion hole 221 is arrange | positioned at equal intervals, for example. The one end of the corresponding cell 100 is inserted into each insertion hole 221.

  As shown in FIG. 5, each insertion hole 221 has an oval shape (L4> L5) extending in the y-axis direction with a length L4 and a width L5. The length L4 of the insertion hole 221 is 0.2 to 3 mm longer than the length L2 (see FIG. 1) of the side surface of one end of the cell 100. Similarly, the width L5 of the insertion hole 221 is 0.2 to 3 mm larger than the width L3 (see FIG. 1) of the side surface of one end of the cell 100. That is, as shown in FIGS. 6 and 7, when the one end of the cell 100 is inserted into the insertion hole 221, there is a gap between the inner wall of the insertion hole 221 and the outer wall of the one end of the cell 100. It is formed. In FIG. 6 and FIG. 7 (particularly FIG. 6), the gap is exaggerated.

  As shown in FIGS. 6 and 7, in each of the joint portions between the insertion hole 221 and the one end portion of the cell 100, the solidified joining material 300 is provided so as to fill the gap. Thereby, each insertion hole 221 and the said one end part of the cell 100 corresponding are each joined and fixed. As shown in FIG. 7, the one end of the gas flow path 11 of each cell 100 communicates with the internal space of the fuel manifold main body 200.

The bonding material 300 is made of crystallized glass. As the crystallized glass, for example, a SiO ₂ —B ₂ O ₃ system, a SiO ₂ —CaO system, or a MgO—B ₂ O ₃ system can be adopted, but a SiO ₂ —MgO system is most preferable. In this specification, crystallized glass means that the ratio (crystallinity) of “volume occupied by crystal phase” to the total volume is 60% or more, and “volume occupied by amorphous phase and impurities relative to the total volume”. "Refers to glass (ceramics) having a ratio of less than 40%. The crystallinity of the crystallized glass is specifically determined by, for example, “the crystal phase and the composition after the crystal phase is identified by using XRD or the like and crystallized by using SEM and EDS or SEM and EPMA. The volume ratio of the crystal phase region is calculated based on the result of observing the distribution. The porosity of the bonding material 300 is less than 10%. In other words, the bonding material 300 is dense.

  In addition, as shown in FIG. 7, between adjacent cells 100, 100, between adjacent cells 100, 100 (more specifically, the fuel electrode of one cell 100 and the air electrode of the other cell 100). Current collecting member 400 for electrically connecting the two in series. The current collecting member 400 is made of, for example, a metal mesh. In addition, a current collecting member 500 for electrically connecting the front side and the back side of each cell 100 in series is also provided.

  When the cantilever stack structure of the fuel cell described above is operated, as shown in FIG. 8, the fuel gas (eg, hydrogen) at a high temperature (for example, 600 to 800 ° C.) and the “gas containing oxygen (eg, air) ) ". The fuel gas introduced from the introduction pipe 230 moves into the internal space of the fuel manifold main body 200 and is then introduced into the gas flow path 11 of the corresponding cell 100 via each insertion hole 221. The fuel gas that has passed through each gas flow path 11 is then discharged from the other end (free end) of each gas flow path 11 to the outside. Air flows through the space between adjacent cells 100 in the stack structure along the width direction (y-axis direction) of the cells 100. As a result, each cell 100 enters the power generation state described above, and power is extracted from each cell 100 (and thus the stack structure).

  The above-mentioned cantilever stack structure is assembled by the following procedure, for example. First, a required number of completed cells 100 and a completed manifold body 200 are prepared. Next, the plurality of cells 100 are aligned and fixed in a stack using a predetermined jig or the like. Next, while maintaining the state in which the plurality of cells 100 are aligned and fixed in a stack, one end of each of the plurality of cells 100 is inserted into the corresponding insertion hole of the support plate 220 (in which the paste film is formed). 221 is inserted at a time. Next, a paste of an amorphous material (amorphous glass) for the bonding material 300 is filled in each gap of the bonding portion between the insertion hole 221 and one end portion of the cell 100. At that time, as shown in FIG. 7, the paste may be supplied to the joint to the extent that it protrudes upward from the surface of the support plate 220.

  Next, heat treatment (crystallization treatment) is applied to the amorphous material paste for the bonding material 300 filled as described above. When the temperature of the amorphous material reaches its crystallization temperature by this heat treatment, a crystal phase is generated inside the material at the crystallization temperature, and crystallization proceeds. As a result, the amorphous material is solidified and ceramicized to become crystallized glass. Thereby, the bonding material 300 made of crystallized glass exhibits a function, and one end of each cell is bonded and fixed to the corresponding insertion hole 221. In other words, one end of each cell 100 is joined and supported by the support plate 220 using the joining material 300. Thereafter, the predetermined jig is removed from the plurality of cells 100 to complete the above-described cantilever stack structure.

(Join the introduction pipe)
Hereinafter, joining and fixing of the introduction pipe 230 to the fuel manifold body 200 will be described. For example, as shown in FIG. 9, the introduction pipe 230 is joined and fixed to the upper wall (support plate 220) of the fuel manifold body 200. In the example shown in FIG. 9, one end portion of the introduction pipe 230 that is a straight pipe is inserted into a through hole formed in the support plate 220.

  The joining material 240 joins the introduction pipe 230 to the upper wall of the fuel manifold main body 200. The bonding material 240 is located in the internal space of the fuel manifold body 200. The bonding material 240 is made of a metal material. That is, it can be said that the introduction pipe 230 is joined and fixed to the support plate 220 by the “joining material 240 made of a metal material” located in the internal space of the fuel manifold body 200. Specifically, the introduction pipe 230 is welded to the support plate 220 of the fuel manifold body 200 in the internal space of the fuel manifold body 200. In this case, the bonding material 240 is made of a melted material of the introduction pipe 230 and / or the support plate 220. The introduction pipe 230 is joined to the support plate 220 by “brazing” using “metal material” (alloy, brazing, material having a melting point lower than that of the introduction pipe 230 and the support plate 220) as the “joining material 240”. -It may be fixed. As the metal material (alloy), gold, silver, palladium, nickel, or the like can be used.

  The introduction pipe 230 may be joined and fixed to the side wall of the fuel manifold body 200 as shown in FIG. That is, one end portion of the introduction pipe 230 is welded on the inner space side to the side wall while being inserted into a through hole formed in the side wall of the fuel manifold body 200, so that the introduction pipe 230 is connected to the side wall. It may be joined and fixed to. Further, instead of “welding”, the introduction pipe 230 may be joined and fixed to the side wall by the above “brazing” using a “metal material” (alloy, brazing).

  According to the above configuration, the “metal material” is used as the material of the “joining material” used for joining the introduction pipe 230. Therefore, for example, the introduction tube 230 can be more firmly bonded and fixed as compared with the case where “glass material” or the like is used as the material of the “bonding material”.

  In addition, according to the above configuration, the “joining material” used for joining the introduction pipe 230 is located in the internal space of the fuel manifold body 200. Here, during the operation of the fuel cell, the fuel gas flows in the internal space of the fuel manifold body 200, so that the internal space of the fuel manifold body 200 is maintained in a reducing atmosphere. Accordingly, during operation of the fuel cell, the atmosphere surrounding the “joining material” is maintained in a reducing atmosphere. In a reducing atmosphere, the “metal material” is not easily oxidized. Therefore, according to the above configuration, even after the fuel cell is operated for a long time, the “joining material” is not easily oxidized, and therefore “decrease in the joining strength of the joining material” due to the oxidation hardly occurs. As described above, according to the above configuration, the state where the introduction pipe 230 is firmly joined and fixed to the wall of the fuel manifold body 200 can be maintained even after the fuel cell is operated for a long time.

  The present invention is not limited to the above embodiment, and various modifications can be employed within the scope of the present invention. For example, in the above-described embodiment, a so-called “horizontal stripe type” cell in which adjacent power generating element portions are electrically connected is employed, but only one power generating element portion is provided on the surface of the support substrate. A cell may be employed.

  Moreover, in the said embodiment, although the said one end part of one cell is inserted in one insertion hole formed in the support plate, two or more cells 100 are inserted in one insertion hole formed in the support plate. The one end may be inserted. Further, all of the one end portions of the plurality of cells may be inserted into one (only) insertion hole formed in the support plate.

  Moreover, in the said embodiment, although the several electric power generation element part A is provided in each of the upper and lower surfaces of the flat support substrate 10, the several electric power generation element part A is provided only in the single side | surface of the support substrate. Also good. In the above embodiment, the support substrate 10 has a flat plate shape, but the support substrate may have a cylindrical shape. In this case, the inner space of the cylindrical support substrate functions as a gas flow path.

  Further, in the embodiment shown in FIGS. 9 and 10, no “gap” is formed between the through hole formed in the wall of the manifold body and the introduction pipe 230 inserted into the through hole. However, as shown in FIGS. 11 and 12 corresponding to FIGS. 9 and 10, a “gap” (annular gap) may be formed between the through hole and the introduction tube 230. In this case, as illustrated in FIGS. 11 and 12, the bonding material 240 may enter a part of the “gap”.

  Further, in the above embodiment, a so-called “cantilever stack structure” is adopted, but as shown in FIG. 13, the flat fuel cell 600 and the flat separator 700 are alternately stacked a plurality of times. A stack structure may be employed. Details of this stack structure are described in, for example, Japanese Patent No. 5284921.

  In the stack structure shown in FIG. 13, an upper lid 800 and a lower lid 900 are provided at both ends in the stacking direction (stacking direction, cell thickness direction). The upper lid 800 is provided with an introduction pipe 850 for introducing fuel gas into the stack structure from the outside. This upper lid 800 corresponds to the lid body of the present invention.

  For example, as shown in FIG. 14, the introduction tube 850 is joined and fixed to the upper wall of the upper lid 800. In the example shown in FIG. 14, one end portion of the introduction pipe 850 that is a straight pipe is inserted into a through-hole formed in the upper wall of the upper lid 800, and “welding” is performed on the inner space side with respect to the upper wall. ”, The introduction pipe 850 is joined and fixed to the upper wall.

  That is, similar to the introduction pipe 230 of the above embodiment, the introduction pipe 850 is joined and fixed to the upper wall of the upper lid 800 by the “joining material 860 made of a metal material” located in the internal space of the upper lid 800. Yes. Here, the bonding material 860 is made of a material of the molten introduction pipe 850 and / or the upper lid 800. The introduction pipe 850 is attached to the upper wall of the upper lid 800 by “brazing” using a “metal material” (alloy, brazing, a material having a melting point lower than that of the introduction pipe 850 and the upper lid 800) as the “joining material 860”. It may be joined and fixed. As the metal material (alloy), gold, silver, palladium, nickel, or the like can be used.

  In the example shown in FIG. 14, no “gap” is formed between the through hole formed in the upper wall of the upper lid 800 and the introduction pipe 850 inserted into the through hole. As shown in FIG. 15, a “gap” (annular gap) may be formed between the through hole and the introduction pipe 850. In this case, as shown in FIG. 15, the bonding material 860 may enter a part of the “gap”.

  DESCRIPTION OF SYMBOLS 10 ... Support substrate, 11 ... Fuel gas flow path, 100 ... Cell, 200 ... Manifold, 210 ... Base, 220 ... Support plate, 221 ... Insertion hole, 230, 850 ... Introducing pipe, 240, 860 ... Joining material, A ... Power generation element

Claims (4)

A fuel manifold configured to be provided with a plurality of fuel cells each having a fuel gas channel formed therein, and supplying the fuel gas to each of the fuel gas channels of the plurality of fuel cells. A fuel manifold,
A fuel manifold body having walls defining an interior space;
An introduction pipe inserted into a through-hole formed in the wall of the fuel manifold body, for introducing fuel gas into the internal space of the fuel manifold body;
Composed of a metal material located in the internal space, and a joining material for joining the introduction pipe to the wall;
With fuel manifold. The fuel manifold according to claim 1, wherein
The fuel manifold, wherein the introduction pipe is joined and fixed to the wall by welding on the inner space side with respect to the wall. A lid member provided at an end portion in a stacking direction of a stack structure of a fuel cell in which fuel cells and separators are alternately stacked a plurality of times, and a lid member that supplies fuel gas to the plurality of fuel cells There,
A lid body having a wall defining an interior space;
An introduction pipe that is inserted into a through hole formed in the wall of the lid member and introduces fuel gas into the internal space of the lid body;
It is composed of a metal material located in the internal space, and a bonding material that fixes the introduction pipe to the wall;
A lid member. The lid member according to claim 3,
The introduction pipe is a lid member joined and fixed to the wall by welding on the inner space side to the wall.

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