JP2008066022A - Solid oxide fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to remove simply and exchange a fuel cell stack arranged in a fuel cell system. <P>SOLUTION: The solid oxide fuel cell connects fuel cell stacks connecting a plurality of fuel battery cells by current collector members through a conductive ceramic member, or, when the fuel cell stacks are connected by a stack connection member, they are connected through a ceramic member between the stack and the stack connection member, and furthermore, has a mechanism to support the conductive ceramic member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid oxide fuel cell, and more particularly to a method for connecting a solid oxide fuel cell stack in which a plurality of fuel cells are electrically connected by a current collecting member.

A solid oxide fuel cell is composed of fuel cells made by laminating ceramic materials of different components as an air electrode, an electrolyte, and a fuel electrode, and generates power most efficiently at about 700 ° C to 1000 ° C. This is a type of fuel cell. In particular, a fuel cell having a cylindrical shape is called a cylindrical solid oxide fuel cell.
An example of a conventional typical cylindrical solid oxide fuel cell is shown in FIGS. FIG. 7 is a cross-sectional view of the fuel cell module, and FIG. 8 is a diagram showing a method of connecting a plurality of fuel cell stacks inside the module.
The fuel cell module is arranged in a state where a plurality of fuel cells 1 are electrically connected to the metal wall 13 by the cell current collector 2, and the fuel cell 1 and the cell current collector 2 and the metal wall 13 An insulating member 12 is disposed between them.
A partition plate 6 is attached in the vicinity of the opening of the fuel cell 1. With the partition plate 6 interposed, the sealed end side of the fuel cell 1 is the power generation chamber 8, and the fuel cell 1 opening side is the combustion chamber 9. It is said.
The fuel gas supplied through the fuel supply pipe 14 is effectively dispersed in the fuel dispersion chamber 11 located below the power generation chamber 8, passes through the fuel dispersion plate 16, and enters the power generation chamber 8. Flows toward the upper partition plate 6 while in contact with the outer surface.
On the other hand, the air is supplied from the air supply pipe 15 to the air distributor 7 and is effectively dispersed, and then introduced into the fuel battery cell through the introduction pipe 10 inserted inside the fuel battery cell 1. 1 contacts the inner surface.
When the temperature of the solid oxide fuel cell configured as described above is raised to an operating temperature of about 700 to 1000 ° C., O ² flows from the air electrode inside the fuel cell 1 to the fuel electrode outside the fuel cell 1. ^- ions to move electrochemical reaction takes place, generating electricity. Steam and unreacted fuel gas generated during power generation pass through a partition plate 6 having a proper pressure loss and ventilation function and enter the combustion chamber 9. Further, unreacted air inside the fuel cell 1 also enters the combustion chamber 9. Steam, unreacted fuel gas and unreacted air are mixed in the combustion chamber 9 and discharged from the exhaust gas duct 17 after ignition combustion. Since the partition plate 6 has an appropriate pressure loss, the gas in the combustion chamber 9 is prevented from flowing back to the power generation chamber 8. A heat insulating material 18 is disposed on the outer periphery of the metal wall 13 to maintain the temperature in the power generation chamber 8 at a high temperature and prevent energy loss due to heat dissipation.
Inside the fuel cell module, a plurality of cylindrical fuel cells 1 are electrically connected by a cell current collecting member 2, and end current collecting members 3 are attached to cells at both ends, and have a predetermined power generation capacity. A fuel cell stack 4 is configured. Further, the plurality of fuel cell stacks 4 are electrically connected by connecting the end current collecting member 3 and the stack connecting member 5 to ensure the electric capacity desired for the fuel cell system.

  In such a solid oxide fuel cell configuration, the fuel cell 1, the partition plate 6, the introduction pipe 10, the insulating member 12, the fuel dispersion plate 16, etc. are made of ceramic material, metal wall 13, cell current collecting member 2, The end current collecting member 3, the stack connecting member 5, the air distributor 7, the fuel supply pipe 14, the exhaust gas duct 17 and the like are generally made of a heat-resistant metal material such as Inconel, stainless steel, or nickel.

Further, during operation of the solid oxide fuel cell, the fuel cell 1, the cell current collecting member 2, the end current collecting member 3, and the stack connecting member 5 were each pressed to maintain electrical contact. In the state, it is exposed to a temperature of about 700 to 1000 ° C. Therefore, the fuel battery cell 1 and the cell current collecting member 2, or the cell 1 and the end current collecting member 3, or the end current collecting member 3 and the stack connecting member 5 are sintered after the power generation operation. That is, in the solid oxide fuel cell after operation, the fuel cell 1, the cell current collecting member 2, the end current collecting member 3, the stack connecting member 5 and the like are sintered and integrated.
However, during the long life cycle of the fuel cell system, the performance of some of the many fuel cells may be degraded, or some of the fuel cells may be damaged due to some external cause. It is desirable to replace only damaged fuel cells or fuel cell stacks and reuse healthy fuel cells or fuel cell stacks.

Conventionally, regarding the replacement of the fuel cell stack, the current collector plates at the ends of the fuel cell stacks facing each other are joined together by welding, or the current collector plates at the ends of the fuel cell stack are connected to another stack There has been proposed a method in which a welded connection is made via a member and the welded portion is cut as required for stack exchange. (For example, see Patent Document 1)
However, since the current collector plates or the current collector plates and the stack connecting member are sintered after the fuel cell operation, each stack cannot be handled in the original state after the operation.
In addition, since the current collector plate at the end or a part of the stack connecting member is cut or ground at the time of replacement, the number of times that it can be removed and restored is limited to several times. When the stack 4 is replaced, the history of removal and recovery is added in many fuel cell stacks 4, and the fuel cell system as a whole can only be replaced several times.
Special Table 2002-502100

  The present invention has been made to solve the above problems, and an object of the present invention is to easily remove and replace the fuel cell stack disposed in the fuel cell system.

    In order to achieve the above object, the present invention provides a solid oxide fuel cell comprising a fuel cell stack in which a plurality of fuel cells are connected by a current collecting member, and a conductive ceramic between adjacent fuel cell stacks. And a mechanism for holding the conductive ceramic member.

  The present invention also provides a solid oxide fuel cell comprising a fuel cell stack in which a plurality of fuel cells are connected by a current collecting member, and a stack connection member for connecting the plurality of fuel cell stacks, the fuel cell stack And a stack connecting member, and a mechanism for holding the conductive ceramic member is further provided.

In a preferred aspect of the present invention, the mechanism for holding the conductive ceramic member is a structure in which the fuel cell stacks or the fuel cell stack and the stack connecting member are fastened with bolts.

In a preferred aspect of the present invention, the mechanism for holding the conductive ceramic member is a frame surrounding the fuel cell stack and the stack connecting member, and the material of the frame is equal to the linear expansion coefficient of the fuel cell. It is smaller than that.

In a preferred aspect of the present invention, the mechanism for holding the conductive ceramic member has a structure in which metal walls provided around the plurality of fuel cell stacks are pressed from the outside.

In a preferred aspect of the present invention, the conductive ceramic member is a pressed body of conductive ceramic particles.

  According to the present invention, the fuel cell stack 4 disposed in the fuel cell system can be easily removed and replaced.

Hereinafter, the present invention will be described more specifically with reference to the drawings.
FIG. 1 is a plan sectional view of a cylindrical solid oxide fuel cell schematically showing a first embodiment of the present invention.

A plurality of cylindrical fuel cells 1 are electrically connected by a cell current collecting member 2 to form a fuel cell stack 4 including an end current collecting member 3 and an end current collecting plate 24.
The cell current collector is required to electrically connect the fuel cells at a high temperature of about 700 to 1000 ° C. and to relieve stress between the cells. As the cell current collecting member, a metal felt material or foam material having heat resistance such as stainless steel or nickel can be suitably used. Moreover, in order to perform stress relaxation more effectively, it can also be given elasticity by making it into the shape folded in the accordion shape. As the end current collecting member, a member obtained by folding a felt material or a foam material of a heat-resistant metal such as nickel as in the cell current collecting member can be suitably used. As the end current collecting plate, a metal plate having heat resistance such as stainless steel or nickel can be suitably used. Further, the fuel cell stack 4 may be sintered in advance.
In the present embodiment, the conductive ceramic member 20 is interposed between the end collector plate 24 of one fuel cell stack 4 and the collector plate 24 of the other fuel cell stack 4. Furthermore, in order to hold the conductive ceramic member 20, the current collector plates 24 are fastened with bolts 21. With such a configuration, the current collector plate and the conductive ceramic member maintain an appropriate contact state during the fuel cell operation, and stable conductivity is maintained. Furthermore, since the conductive ceramic member is difficult to sinter even at a high temperature of about 700 to 1000 ° C. and has a low sinterability with a metal material, it is necessary to loosen the bolts at the time of fuel cell maintenance. The current collector plate can be easily separated, and the stack can be removed in the same state as before operation.
As the conductive ceramic member, a material exhibiting high electronic conductivity at a high temperature of about 700 to 1000 ° C., for example, a perovskite oxide such as lanthanum manganite or lanthanum cobaltite can be suitably used. In consideration of the assemblability of the fuel cell module, a conductive ceramic particle formed into a sheet with an organic binder can be suitably used. Since the organic binder volatilizes at the operating temperature of the solid oxide fuel cell, the aggregate of only ceramic particles remains after the operation, but the aggregate of ceramic particles can be easily broken, so it becomes a stack. The end current collector plate and the ceramic member can be separated without applying an extra force.

  FIG. 2 is a plan sectional view of a cylindrical solid oxide fuel cell schematically showing a second embodiment of the present invention.

The fuel cell stack 4 in FIG. 2 has the same configuration as the fuel cell stack 4 in FIG. 1, and a plurality of cylindrical fuel cells 1 are electrically connected by a cell current collector 2, and end current collectors 3 and an end current collector plate 24 are provided.
In the present embodiment, in order to ensure the electric capacity desired for the fuel cell system, the end current collecting plates 24 of the plurality of fuel cell stacks 4 are electrically connected to each other via the conductive ceramic member 20 and the stack connecting member 5. Connected. Further, in this embodiment, the stacks are arranged in parallel. The stack connection member 5 has a flat plate shape for connecting the fuel cell stacks 4 arranged in parallel. Moreover, it has sufficient length in the horizontal direction of FIG. 2 so that it can connect with the edge part of one adjacent fuel cell stack, and the edge part of the other fuel cell stack. The lateral length of the stack connecting member is preferably larger than twice the width of the fuel cell stack when two fuel cell stacks are connected. Further, when n fuel cell stacks are electrically connected by one stack connecting member, it is preferable that the stack connecting member is larger than n times the width of the fuel cell stack. By adopting such a configuration, it is possible to prevent adjacent fuel cell stacks from contacting each other at the side surface and being electrically short-circuited.
The conductive ceramic member 20 is sandwiched between the end current collector plate 24 and the stack connection member 5. Further, the end current collector plate 24 and the stack connection member 5 are fixed by the current collector mounting bolts 21 so that the electrical connection can be maintained even under the operating temperature of the fuel cell, and a pressing force acts on the conductive ceramic member 20. It is configured.
In order to easily connect the stacks, it is preferable to provide bolt holes in the end current collector plate 24 and the stack connection member 5 in advance. In this embodiment, the stack current collector plate is provided with two bolt holes for bolting each adjacent fuel cell stack.

  FIG. 3 is a perspective view of a cylindrical solid oxide fuel cell schematically illustrating the third embodiment of the present invention, and FIG. 4 is a cylindrical solid oxide fuel cell schematically illustrating the third embodiment of the present invention. It is a plane sectional view of a fuel cell.

In FIG. 3, a plurality of cylindrical fuel cells 1 are electrically connected by a cell current collector 2 to constitute a fuel cell stack 4 having an end current collector 3.
In this embodiment, in order to ensure the desired electric capacity of the fuel cell system, the end current collecting members 3 of the plurality of fuel cell stacks 4 are electrically connected to each other through the conductive ceramic member 20 and the stack connecting member 5. Connected.
Further, in the present embodiment, in order to hold the conductive ceramic member 20, the stack frame constituted by the stack frame members 22-ad so as to surround the fuel cell stack 4, the conductive ceramic member 20, and the stack connection member 5. 22 is provided.
The stack frame 22 is made of a material having a linear expansion coefficient smaller than the linear expansion coefficient 11 to 13 μ / K of the fuel cell 1, for example, alumina (linear expansion coefficient 8 μ / K), and has an operating temperature of 700 ° C. to 1000 ° C. , The stack frame 22-a and the stack frame 22-c apply a pressing force to the fuel cell stack 4, the conductive ceramic member 20, and the stack connection member 5 due to the difference in thermal expansion. 20 and the stack connection member 5 can be maintained in electrical connection.
Alternatively, if the stack frame 22 is assembled in advance with the current collecting end 3, the conductive ceramic member 20, and the stack connecting member 5 being pressed, the stack frame 22 has a linear expansion coefficient of 11 to 13 μ / It is also possible to use ferritic stainless steel having a linear expansion coefficient substantially equal to that of K. In this case, for the purpose of preventing an electrical short circuit, the stack frame 22-b and the stack frame 22-c are provided with an insulating material so that the stack frame 22-a and the stack frame 22-c are electrically insulated. Insulation measures such as fixing are performed.

  FIG. 5 is a plan sectional view of a cylindrical solid oxide fuel cell schematically showing a fourth embodiment of the present invention.

In FIG. 5, a plurality of cylindrical fuel cells 1 are electrically connected by a cell current collector 2 to constitute a fuel cell stack 4 having an end current collector 3.
In this embodiment, in order to ensure the desired electric capacity of the fuel cell system, the end current collecting members 3 of the plurality of fuel cell stacks 4 are electrically connected to each other through the conductive ceramic member 20 and the stack connecting member 5. Connected.
Further, in this embodiment, in order to hold the conductive ceramic member 20, an insulating member 12 is provided so as to surround the fuel cell stack 4, the conductive ceramic member 20, and the stack connecting member 5, and further, a metal wall is provided around the insulating member 12. 13 is provided, and a plurality of pressing mechanisms 23 for pressing the metal wall inward by a spring are provided outside the metal wall 13.
The metal wall 13 is made of inconel or stainless steel having excellent heat resistance, and a thin plate of about 0.3 mm to 1.0 mm is used so that it can be easily deformed. Therefore, the pressure applied from the outside to the inside by the pressing mechanism 23 is transmitted to the insulating member 12 by the deformation of the metal wall 13, and the stack connecting member 5, the conductive ceramic member 20, and the fuel cell stack 4 are transmitted from the insulating member 12. It is transmitted to. Therefore, the electrical connection of the fuel cell stack 4, the conductive ceramic member 20, and the stack connecting member 5 can be maintained.

The thickness of the conductive ceramic member is preferably 20 μm to 100 μm.
By setting the thickness of the conductive ceramic member to 20 μm or more, it is possible to effectively prevent the fuel cell stacks or the fuel cell stack and the stack current collector plate from directly contacting and burning. On the other hand, the electrical resistance value can be reduced by setting the thickness of the conductive ceramic member to 100 μm or less.

As a method for providing the conductive ceramic member, for example, there is a method in which a ceramic sheet obtained by processing a mixture of calcined conductive ceramic particles and an organic resin as a binder into a sheet is provided at a desired portion. By using such a method, the conductive ceramic member can be easily provided at a desired site during assembly. Since the binder volatilizes between 700 ° C. and 1000 ° C., which is the operating temperature of the fuel cell, aggregates formed only from the conductive ceramic particles remain, and the current collecting end 3 and the stack connecting member 5 are electrically connected. A conductive ceramic member to be connected is formed. In this state, the conductive ceramic itself does not sinter particles, and is in a state equivalent to a pressed body of powder. Therefore, the conductive ceramic member can be easily destroyed after the fuel cell operation. Therefore, the fuel cell stack, the conductive ceramic member, and the stack connection member that are electrically connected during operation are easily destroyed by destroying the conductive ceramic member after the fuel cell operation. It can be separated into connection members, and the fuel cell stack can be easily taken out.
Further, when reattaching, the fuel cell can be assembled by newly assembling the ceramic sheet between the fuel cell stack and the stack connecting member.
Therefore, since some fuel cell stacks in the fuel cell system can be replaced, the performance of some of the fuel cell cells deteriorates during the long life cycle of the fuel cell system, or due to some external cause. Even if some of the fuel cells are damaged, it is possible to replace only the fuel cell stack including the deteriorated or damaged fuel cells, thereby extending the life of the entire fuel cell system.

  When the pressing mechanism 23 using the stack frame 22 and the pressing mechanism 23 by the spring provided outside the metal wall 13 are provided, the conductive ceramic member 20 is connected to the cell current collecting member 2 as shown in FIG. Can be sandwiched between. By doing so, not only the fuel cell stack 4 can be detached but also the fuel cell 1 can be detached. Therefore, even if some of the fuel cells 1 are damaged due to some external cause, it is possible to replace only the deteriorated or damaged fuel cells 1 and extend the life of the entire fuel cell system at a lower cost.

1 is a cross-sectional plan view of a cylindrical solid oxide fuel cell schematically illustrating a first embodiment of the present invention. FIG. 3 is a plan sectional view of a cylindrical solid oxide fuel cell schematically showing a second embodiment of the present invention. FIG. 6 is a perspective view of a cylindrical solid oxide fuel cell schematically showing a third embodiment of the present invention. FIG. 6 is a plan sectional view of a cylindrical solid oxide fuel cell schematically showing a third embodiment of the present invention. FIG. 6 is a plan sectional view of a cylindrical solid oxide fuel cell schematically showing a fourth embodiment of the present invention. FIG. 6 is a plan sectional view of a cylindrical solid oxide fuel cell schematically showing a fifth embodiment of the present invention. It is a figure which shows the conventional solid oxide fuel cell module. It is a figure which shows the connection method of the several fuel cell stack inside the conventional solid oxide type fuel cell module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell 2 ... Cell current collection member 3 ... End part current collection member 4 ... Fuel cell stack 5 ... Stack connection member 6 ... Partition plate 7 ... Air distributor 8 ... Power generation chamber 9 ... Combustion chamber 10 ... Inlet pipe 11 DESCRIPTION OF SYMBOLS ... Fuel dispersion chamber 12 ... Insulation member 13 ... Metal wall 14 ... Fuel supply pipe 15 ... Air supply pipe 16 ... Fuel dispersion plate 17 ... Exhaust gas duct 18 ... Heat insulating material 19 ... Electrode rod 20 ... Conductive ceramic member 21 ... Current collection member Mounting bolt 22 ... Stack frame 22-a ... Stack frame member 22-b ... Stack frame member 22-c ... Stack frame member 22-d ... Stack frame member 23 ... Pressing mechanism 24 ... End collector plate

Claims (6)

A solid oxide fuel cell comprising a fuel cell stack in which a plurality of fuel cells are connected by current collecting members,
Comprising a conductive ceramic member between adjacent fuel cell stacks;
A solid oxide fuel cell comprising a mechanism for holding the conductive ceramic member. A plurality of fuel cells connected by current collecting members and a fuel cell stack;
In a solid oxide fuel cell comprising a stack connecting member for connecting a plurality of the fuel cell stacks,
A conductive ceramic member is provided between the fuel cell stack and the stack connecting member,
A solid oxide fuel cell comprising a mechanism for holding the conductive ceramic member. 3. The solid according to claim 1, wherein the mechanism for holding the conductive ceramic member is a structure in which the fuel cell stacks or the fuel cell stack and the stack connecting member are fastened with bolts. Oxide fuel cell. The mechanism for holding the conductive ceramic member is a frame surrounding the fuel cell stack and the stack connecting member,
The solid oxide fuel cell according to claim 2, wherein a material of the frame is equal to or smaller than a linear expansion coefficient of the fuel cell. 3. The solid oxide type according to claim 1, wherein the mechanism for holding the conductive ceramic member has a structure in which metal walls provided around the plurality of fuel cell stacks are pressed from the outside. Fuel cell. The solid oxide fuel cell according to any one of claims 1 to 5, wherein the conductive ceramic member is a press body of conductive ceramic particles.

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