JP7423382B2 - Seal member, fuel cell system, and seal member repair method - Google Patents

Description

The present invention relates to a seal member, a fuel cell system, and a method for repairing a seal member.

The fuel cell system of Patent Document 1 includes a manifold that supplies fuel gas and a cell stack that receives the supply of fuel gas from the manifold. The cell stack is configured such that a plurality of elliptical cylindrical cells extending in the longitudinal direction are erected in parallel so that the longitudinal direction thereof projects from the manifold. The cell receives fuel gas and air from the manifold and generates electricity through an electrochemical reaction.

In Patent Document 1, one longitudinal end of a cell is inserted into an insertion port provided in a manifold, joined together, and sealed with a sealing member. Furthermore, one ends of adjacent cells are also sealed with a sealing member. The sealing member of Patent Document 1 is composed of a dense portion in the surface layer portion, a porous portion below the dense portion, and other portions. The lower end of the porous portion reaches the lower end of the sealing member. It is said that such a configuration of the seal member can alleviate the stress caused by thermal contraction inside the seal member, and can suppress the progress of peeling of the seal member to the surface layer of the seal member. Therefore, it is said that it is possible to suppress peeling of the seal member at locations where the seal member is provided, such as the joint portion between the cell and the manifold, and the joint portion between cells.

Japanese Patent Application Publication No. 2017-112045

However, if a sudden temperature change occurs in the seal member at the joint, or if stress exceeding the allowable value is applied to the seal member at the joint due to vibrations such as transportation or earthquakes, the seal member may be damaged. There is sex. If this happens, fuel gas, etc. will leak from the damaged part. Currently, if the seal member is damaged, it is difficult to use the fuel cell.

Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a seal member used in a fuel cell system, a fuel cell system, and a method for repairing the seal member.

The characteristic configuration of the seal member according to the present invention is as follows:
A sealing member applied to a joint portion that joins constituent members of a fuel cell module having fuel cell cells,
a first member made of a material that melts at an operating temperature higher than the normal operating temperature of the fuel cell and has a first softening point temperature;
a second member made of a material that melts at an operating temperature higher than the normal operating temperature of the fuel cell and has a second softening point temperature lower than the first softening point temperature of the first member. fruit ,
The material of the first member and the second member is an isotropic material .
The sealing member including the first member and the second member having the above-described characteristics is applied to a joint portion that joins constituent members of a fuel cell module. Both the first member and the second member have a first softening point temperature and a second softening point temperature at which they melt when the fuel cell is operated at an operating temperature higher than the normal operating temperature. Therefore, when the fuel cell is operated at a normal operating temperature, the first member and the second member do not melt. The second softening point temperature of the second member is lower than the first softening point temperature of the first member. Therefore, when the fuel cell is operated at a temperature where the sealing member is higher than or equal to the second softening point temperature and lower than the first softening point temperature, the second member melts but the first member does not melt. If damage such as cracking or peeling occurs in the sealing member, by heating as described above, the first member will not melt and will maintain its shape, but the second member will melt and the damaged portion of the first member will be removed. make up for and repair. Thereby, even if the seal member is damaged, by repairing it, the joint portion can be sealed and leakage of fuel gas or the like can be suppressed.
In addition, by forming the first member and the second member constituting the sealing member from an isotropic material as in the characteristic configuration described above, stress caused by anisotropic thermal expansion of the sealing member can be suppressed, and stress can be reduced. Since the variation in strength due to the orientation is also suppressed, it is possible to prevent the strength of the seal member from decreasing locally, and it is possible to obtain a stable seal member such that the joint portion can be firmly sealed. Further, even when a damaged portion of the first member is repaired with the second member, the seal member can be made of an isotropic material, so that it is possible to prevent the strength from decreasing locally.

The characteristic configuration of the fuel cell system according to the present invention is as follows:
a plurality of fuel cells each having a fuel gas passage through which fuel gas flows;
a manifold that communicates with the fuel gas passage by inserting one end of the plurality of fuel cells and supplies the fuel gas to the fuel gas passage;
a sealing member applied to a joint between one end of the fuel cell and the manifold;
The sealing member includes a first member made of a material that melts at an operating temperature higher than the normal operating temperature of the fuel cell and has a first softening point temperature; and a second member made of a material that melts at the operating temperature of and has a second softening point temperature lower than the first softening point temperature of the first member.
The sealing member including the first member and the second member having the above characteristic configuration is applied to a joint portion between one end of the fuel cell and the manifold. Both the first member and the second member have a first softening point temperature and a second softening point temperature at which they melt when the fuel cell is operated at an operating temperature higher than the normal operating temperature. Therefore, when the fuel cell is operated at a normal operating temperature, the first member and the second member do not melt. The second softening point temperature of the second member is lower than the first softening point temperature of the first member.
When the fuel cell is operated at a temperature where the sealing member is higher than or equal to the second softening point temperature and lower than the first softening point temperature, the second member melts but the first member does not melt. If damage such as cracking or peeling occurs in the first member, the first member will not melt and maintain its shape by heating as described above, but the second member will melt and damage the first member. Repair and fill in the parts. As a result, even if the seal member at the joint between one end of the fuel cell and the manifold is damaged, leakage of fuel gas or the like can be suppressed by repairing the seal member.

A further characteristic configuration of the fuel cell system according to the present invention is that the materials of the first member and the second member are isotropic materials.

By forming the first member and the second member constituting the sealing member from an isotropic material as in the characteristic configuration described above, it is possible to suppress stress caused by anisotropic thermal expansion of the sealing member, and also to suppress the stress caused by the anisotropic thermal expansion of the sealing member. Since the variation in strength due to this can be suppressed, it is possible to prevent the strength of the sealing member from decreasing locally, and it is possible to obtain a stable sealing member, such as being able to firmly seal the joint portion. Further, even when a damaged portion of the first member is repaired with the second member, the seal member can be made of an isotropic material, so that it is possible to prevent the strength from decreasing locally.

A further feature of the seal member and fuel cell system according to the present invention is that the first member and the second member are adjacent to each other.

According to the above characteristic configuration, since the first member and the second member are adjacent to each other, when the first member is damaged, the sealing member is heated as described above, and the first member and the second member are adjacent to each other. The two parts can be melted to compensate for and repair the damaged part of the first part.

A further characteristic configuration of the seal member and fuel cell system according to the present invention is that the second member is disposed above the first member.

According to the characteristic configuration described above, since the second member is arranged above the first member, heating the sealing member as described above melts the second member above the first member, and the second member is placed above the first member by gravity. It gets into the damaged part of one member. Thereby, the damaged portion of the first member can be compensated for by the second member and repaired.

A further feature of the seal member and fuel cell system according to the present invention is that the second member is arranged to cover the surface of the first member.

According to the characteristic configuration described above, the sealing member is arranged so as to cover any surface that comes into contact with the first member. Therefore, by heating the sealing member as described above, the second member can be melted and inserted into the damaged portion from any surface of the first member to repair it.

A further characteristic configuration of the seal member and fuel cell system according to the present invention is that the first softening point temperature and the second softening point temperature are more preferably 30° C. or higher than the temperature of the seal member during normal operation. It is at a point higher than 100 degrees Celsius.

As in the above characteristic structure, the first softening point temperature and the second softening point temperature are higher than the temperature of the sealing member during normal operation by 30°C or more, more preferably by 100°C or more, so the first member and the second member are It does not melt at normal operating temperatures of fuel cells and can maintain its shape as a sealing member. Therefore, even when the fuel cell is in operation, the sealing member stably provides a sealing function.

A further feature of the seal member and fuel cell system according to the present invention is that the first softening point temperature is higher than the second softening point temperature by 60° C. or more.

According to the characteristic configuration described above, the first softening point temperature is higher than the second softening point temperature by 60° C. or more. Therefore, by operating the fuel cell at a temperature at which the sealing member is higher than or equal to the second softening point temperature and lower than the first softening point temperature, the second member is melted while maintaining the shape of the first member, and the melted second member is melted while maintaining the shape of the first member. The two members can compensate for and repair the damaged portion of the first member.

Further characteristic configurations of the fuel cell system according to the present invention include:
A first operating mode is executable in which the fuel cell is controlled to be operated at a normal operating temperature, the operating temperature is higher than the normal operating temperature of the fuel cell, and the second softening mode is The present invention further includes an operation control section that executes a second operation mode in which the fuel cell is controlled to be operated so that the seal member can be heated to a temperature higher than the point temperature and lower than the first softening point temperature.

According to the characteristic configuration described above, the operation control unit controls the fuel cell to operate so that the sealing member can be heated at a temperature higher than or equal to the second softening point temperature and lower than the first softening point temperature by executing the second operation mode. do. When the fuel cell is operated at an operating temperature higher than the normal operating temperature, the first member does not melt and maintains its shape, but the second member melts and compensates for the damaged portion of the first member. can be repaired. Thereby, even if the seal member is damaged, by repairing it, the joint portion can be sealed and leakage of fuel gas or the like can be suppressed. Furthermore, the sealing member can be repaired by adjusting the operating temperature of the fuel cell. Note that the operating temperature in the second operating mode is preferably a temperature higher than the second softening point by 30° C. or more so that the second member is sufficiently melted. In addition, in order to maintain sufficient strength of the first member during the second operating mode, the first softening point temperature is preferably 30° C. or more, more preferably 100° C. or more higher than the operating temperature in the second operating mode. .

The method for repairing a seal member according to the present invention includes:
A fuel cell module having a fuel cell, in which the constituent members are joined together by the above-mentioned sealing member applied to a joint portion where the constituent members are joined together, and an operation control unit that controls the operation of the fuel cell. A method for repairing the seal member in a fuel cell system comprising:
The operation control unit is configured to control a first operation mode to operate the fuel cell at a normal operating temperature, and a second operation mode in which the operating temperature is higher than the normal operating temperature of the fuel cell. The present invention is capable of implementing a second operation mode in which the fuel cell is operated so as to be able to heat the sealing member at a temperature higher than the point temperature and lower than the first softening point temperature.

According to the characteristic configuration described above, the operation control unit controls the fuel cell to operate so that the sealing member can be heated at a temperature higher than or equal to the second softening point temperature and lower than the first softening point temperature by executing the second operation mode. do. When the fuel cell is operated at a higher temperature than the normal operating temperature, the first member does not melt and maintains its shape, but the second member melts and repairs the damaged part of the first member. be able to. Thereby, even if the seal member is damaged, by repairing it, the joint portion can be sealed and leakage of fuel gas or the like can be suppressed. Furthermore, the seal member can be repaired by adjusting the operating temperature of the fuel cell.

A further method for repairing a seal member according to the present invention includes:
A fuel cell module having a fuel cell and in which the constituent members are joined together by the above-mentioned sealing member applied to a joint portion where the constituent members are joined together, a heating section, and a heating section that controls the heating section. A method for repairing a seal member in a fuel cell system comprising a control unit, the characteristic structure of which is as follows:
The heating section control section controls the heating section so as to heat the sealing member at a temperature higher than or equal to the second softening point temperature and lower than the first softening point temperature.

When the sealing member is heated by the heating section at a temperature higher than or equal to the second softening point temperature and lower than the first softening point temperature, the second member melts but the first member does not melt. If damage such as cracking or peeling occurs in the first member, the first member will not melt and maintain its shape by heating as described above, but the second member will melt and damage the first member. Parts can be replaced and repaired.

FIG. 1 is a block diagram showing the overall configuration of a fuel cell system. FIG. 2 is a side view showing a cylindrical flat plate type fuel cell module. FIG. 2 is a top view showing a cylindrical flat plate type fuel cell module. FIG. 2 is a partially enlarged perspective view of a cylindrical flat plate type fuel cell module. FIG. 3 is an enlarged view showing the arrangement of seal members in a cylindrical flat plate type fuel cell module. FIG. 2 is an enlarged view showing a damaged portion of a seal member in a cylindrical flat plate type fuel cell module. FIG. 3 is an enlarged view showing a state in which a seal member in a cylindrical flat plate type fuel cell module is repaired. FIG. 2 is an exploded perspective view showing a flat plate type fuel cell module. FIG. 2 is a cross-sectional view showing the flow of fuel gas in a flat fuel cell module. FIG. 3 is a cross-sectional view showing the flow of oxidizing gas in a flat fuel cell module. FIG. 3 is an enlarged view showing the arrangement of seal members in a flat fuel cell module. FIG. 3 is an enlarged view showing a damaged portion of a seal member in a flat fuel cell module. FIG. 3 is an enlarged view showing a state in which a seal member in a flat fuel cell module is repaired. FIG. 2 is a side view showing a cylindrical fuel cell module. FIG. 3 is an enlarged view showing the arrangement of seal members in a cylindrical fuel cell module. FIG. 2 is an enlarged view showing a damaged portion of a seal member in a cylindrical fuel cell module. FIG. 3 is an enlarged view showing how a seal member in a cylindrical fuel cell module is being repaired. FIG. 7 is a schematic diagram showing another example of arrangement of seal members. FIG. 3 is a block diagram showing the overall configuration of another fuel cell system.

[Embodiment]
A method for repairing a seal member according to an embodiment of the present invention will be described below with reference to FIG.

(1) Configuration of fuel cell system (1-1) Overall configuration The fuel cell system 100 includes a fuel cell power generation device 1, as shown in FIG. The fuel cell system 100 also includes a fuel gas pump 2 for supplying fuel gas, a boost pump 5, and a desulfurizer 3 in order to supply fuel gas, reformed water, and oxidant gas to the fuel cell power generation device 1. , a reformed water tank 9 for supplying reformed water, and an air blower 15 for supplying oxidizing gas. The fuel cell system 100 also includes a heat exchanger 17 as an exhaust heat utilization unit that reuses heat discharged from the fuel cell power generation device 1, and a heat medium such as water that is circulated between the heat exchanger 17. A hot water storage tank 19 is provided. Further, the fuel cell system 100 includes an operation control section 71 that controls the operation of the fuel cell system 100.

The operation control unit 71 of this embodiment executes a second operation mode in which the fuel cell A, which will be described later, is controlled to be operated at a higher temperature than the normal operating temperature. This repairs the seal member and suppresses leakage of various gases such as fuel gas and oxidizing gas (hereinafter also simply referred to as fuel gas etc.). This point will be discussed later.

Hydrocarbon raw fuel such as city gas (for example, city gas 13A) is supplied to the boost pump 5 with the output of a predetermined flow rate controlled by the fuel gas pump 2. Furthermore, the raw fuel is supplied to the desulfurizer 3 through the raw fuel supply path 41 by the operation of the boost pump 5 .

The desulfurizer 3 removes (desulfurizes) sulfur compound components contained in raw fuel. When the raw fuel contains sulfur compounds, by providing the desulfurizer 3, it is possible to suppress the influence of the sulfur compounds on the reformer 28 or the fuel cell power generation device 1.

Reformed water is supplied from the reformed water tank 9 to the fuel cell power generation device 1 through the reformed water supply path 43 by the operation of the reformed water pump 7 .

The reformed water tank 9 collects condensed water from catalyst combustion exhaust gas, which will be described later. Further, the condensed water supplied to the reformed water tank 9 is purified by a water purifier (not shown). Specifically, condensed water is collected from the catalytic combustion exhaust gas, which will be described later, discharged from the outlet of the heat exchanger 17 via the discharge passage 51 through the condensed water recovery passage 45 into a water purifier (not shown). . Condensed water purified by a water purifier (not shown) is collected in the reformed water tank 9.

Furthermore, water can be supplied to the reformed water tank 9 from a water supply section 13 independently of the condensed water.

The fuel cell power generation device 1 is housed in a storage container 40 and includes a fuel cell module 23, a vaporizer 27, a reformer 28, and a combustion section 29.

The vaporizer 27 is supplied with reformed water from the reformed water tank 9 via the reformed water supply path 43, and is supplied with desulfurized raw fuel via the raw fuel supply path 41. The raw fuel supply path 41 is located downstream of the desulfurizer 3 and merges with the reformed water supply path 43, and the reformed water and raw fuel that are combined outside the storage container 40 are fed to the vaporizer 27. Supplied. The vaporizer 27 supplied with reformed water and raw fuel generates steam from the reformed water. The raw fuel containing steam generated in the vaporizer 27 is supplied to the reformer 28 through a steam-containing raw fuel supply path 31 .

The reformer 28 uses the steam generated in the vaporizer 27 to steam-reform the raw fuel desulfurized in the desulfurizer 3 to produce a fuel gas containing hydrogen gas as a main component (containing a reducing component). gas). At this time, the reformer 28 performs steam reform of the raw fuel using combustion heat generated by combustion of unburned gas including fuel component gas in a combustion section 29, which will be described later.

The fuel gas generated in the reformer 28 is supplied to the fuel cell module 23 through a fuel gas supply path 33. The fuel gas is distributed and supplied to the plurality of fuel cells A that constitute the fuel cell module 23. Each fuel cell A has an anode to which fuel gas is supplied, a cathode to which oxidant gas is supplied through the air blower 15, and an electrolyte between the anode and the cathode. Generates electricity by reacting gases.

The inverter 39 adjusts the output voltage generated by the fuel cell module 23 to make it the same voltage and frequency as the power received from the commercial grid (not shown).

The combustion section 29 is supplied with unburned gas containing fuel component gas that is discharged without being used for the power generation reaction in the fuel cell module 23 . The combustion section 29 burns the supplied unburned gas. From the combustion section 29, cell combustion exhaust gas (an example of combustion exhaust gas) generated by combustion of unburned gas is discharged.

The cell combustion exhaust gas is supplied to the reformer 28 and is discharged to the outside of the storage container 40 from the gas outlet 37 via the combustion catalyst section 35. As described above, the reformer 28 performs steam reforming using the heat of the cell combustion exhaust gas, that is, the combustion heat generated by combustion of the fuel component gas.

A combustion catalyst section 35 is disposed at the gas outlet 37, and burns off unburned gas, which is a reducing component such as carbon monoxide and hydrogen contained in the cell combustion exhaust gas. The combustion catalyst section 35 is made of, for example, a platinum-based catalyst.

Catalyst combustion exhaust gas (an example of combustion exhaust gas) generated by combustion of unburned gas in the combustion catalyst section 35 is discharged from the gas outlet 37 . The catalyst combustion exhaust gas is sent to the heat exchanger 17 via the exhaust path 52.

Each part of the fuel cell power generation device 1 is provided with various detection parts for detecting temperature and voltage. In this embodiment, a cell temperature detection section T1 for detecting the temperature in the fuel cell A, a combustion section temperature detection section T2 for detecting the temperature of the cell combustion exhaust gas in the combustion section 29, and a combustion section temperature detection section T2 for detecting the temperature of the cell combustion exhaust gas in the combustion section 29, It includes a catalyst temperature detection section T3 for detecting the temperature of catalyst combustion exhaust gas, and a voltage detection section V for detecting the generated voltage in the fuel cell A. The detection results of these detection units are transmitted to the operation control unit 71.

In the heat exchanger 17 , heat exchange is performed between the catalytic combustion exhaust gas discharged from the gas outlet 37 and the heat medium discharged from the hot water storage tank 19 . For example, when the heat medium is water, heat exchange is performed between the catalyst combustion exhaust gas and water to generate hot water, which is stored in the hot water storage tank 19 . The catalyst combustion exhaust gas is discharged into the discharge passage 51 in a state where the temperature has been lowered by heat exchange with water. The heat medium exiting the heat exchanger 17 is discharged into the heat medium circulation path 61 and introduced into the hot water storage tank 19. Further, the hot water flows through the heat medium circulation path 61 that exits the hot water storage tank 19 and is introduced into the heat exchanger 17 again. Therefore, the heat medium circulates between the heat exchanger 17 and the hot water storage tank 19 through the heat medium circulation path 61.

The hot water storage tank 19 is provided with a hot water outlet path 19a for discharging the hot water in the hot water storage tank 19, and a water supply channel 19b for supplying water to the hot water storage tank 19 according to the hot water discharge. The hot water stored in the hot water storage tank 19 can be used to supply a bath, washroom, etc., and the exhaust heat of the catalytic combustion exhaust gas from the fuel cell power generation device 1 can be reused.

Further, the heat medium circulation path 61 is equipped with a circulation pump 63 and a radiator 65. The circulation pump 63 controls the rotation speed and supplies the heat medium from the hot water storage tank 19 to the heat exchanger 17 at a desired rotation speed. The radiator 65 includes a heat radiation fan 65a for radiating the heat of the heating medium flowing through the heating medium circulation path 61, and a temperature sensor (not shown).

(1-2) Structure of fuel cell module and sealing member Next, the structure of the fuel cell module 23 will be explained. In the following, the fuel cell module 23 will be described using a cylindrical-flat plate type fuel cell module, a flat plate type fuel cell module, and a cylindrical type fuel cell module as examples.
Furthermore, the fuel cell module 23 is provided with a seal member to prevent leakage of various gases such as fuel gas and oxidant gas, and the structure of the seal member will also be explained along with the explanation of the structure of each fuel cell module. do.

(a) Cylindrical and flat plate type fuel cell module The cylindrical and flat plate type fuel cell module 23 will be explained using FIGS. 2 to 5.
The cylindrical and flat type fuel cell module 23 includes a plurality of cylindrical and flat type fuel cells A, a current collecting member 213, a conductive member 214, a current extraction part 215, and a manifold M into which fuel gas is introduced. are doing. The plurality of cylindrical and flat fuel cells A are arranged in parallel to each other with current collecting members 213 interposed therebetween, and are provided so as to stand up from the manifold M. The conductive members 214 are provided at both ends of the fuel cells A in the arrangement direction so as to sandwich the plurality of fuel cells A and the current collecting member 213. The current extraction section 215 is connected to the conductive member 214 and extracts the current generated by the power generation of the fuel cell A.

The fuel cell A is formed into a cylindrical and flat plate shape, and includes a conductive member 201, a fuel electrode layer 203, an electrolyte layer 204, an intermediate layer 205, an air electrode layer 206, an adhesive layer 207, and an interconnector. 208. The conductive member 201 is provided with a fuel gas passage 202 that penetrates the conductive member 201 along the direction in which the fuel cells A are installed. Fuel gas supplied from the manifold M flows through the fuel gas passage 202 .

On one side of adjacent fuel cells A, a fuel electrode layer 203, an electrolyte layer 204, an intermediate layer 205, and an air electrode layer 206 are laminated in order from the conductive member 201 toward the outside. The fuel electrode layer 203 and the electrolyte layer 204 are formed to extend to a part of the other side of the adjacent fuel cell A. Then, an interconnector 208 is formed with an adhesive layer 207 interposed in a portion on the other side of the adjacent fuel cell A where the fuel electrode layer 203 and the electrolyte layer 204 are not formed.

In the cylindrical and flat plate type fuel cell module 23 as described above, the sealing member 80 connects the fuel cell A and the manifold M, which are vertically arranged so as to communicate with the manifold M, as shown in FIGS. 4 and 5, for example. It is applied to the joints. In the examples shown in FIGS. 4 and 5, a sealing member 80 is applied to the upper surface of the manifold M, and the joint portion between the fuel cell A and the manifold M is sealed by the sealing member 80. By arranging the seal member 80 at the joint portion between the fuel cell A and the manifold M in this manner, leakage of fuel gas and the like can be suppressed. As shown in FIG. 5, the sealing member 80 of this embodiment includes a first member 81 and a second member 83. In the example of FIG. 5, the first member 81 is located below the second member 83.

The second member 83 has a temperature higher than the sealing temperature of the second member 83 during normal operation of the fuel cell A (for example, a sealing temperature of 500 to 650°C in the first operation mode described later) (for example, 700°C or more). It is made of a material having a certain second softening point temperature. That is, for example, the normal operating temperature of the fuel cell A is 700 to 750°C, but the sealing temperature of the second member 83 during normal operation is 500 to 650°C. Then, when the fuel cell A is controlled to a higher operating temperature (for example, 780 to 900 degrees Celsius) than the normal operating temperature (for example, 700 to 750 degrees Celsius), the sealing temperature of the second member 83 becomes 700 degrees Celsius or higher, and the second The member 83 becomes meltable. As described above, the second softening point temperature is a temperature at which the second member 83 can be melted when the fuel cell A is controlled to a high temperature (for example, 780 to 900° C.).

The first member 81 is made of a material having a first softening point temperature higher than the sealing temperature of the first member 81 during normal operation of the fuel cell A and higher than the second softening point temperature. Become. That is, for example, the normal operating temperature of the fuel cell A is 700 to 750°C, but the sealing temperature of the first member 81 during normal operation is 500 to 650°C. When the fuel cell A is controlled to a higher operating temperature (for example, 780 to 900°C) than the normal operating temperature (for example, 700 to 750°C), the sealing temperature of the first member 81 becomes 700°C or higher. The first softening point temperature is a temperature at which the first member 81 does not melt even when the fuel cell A is controlled to a high temperature (for example, 780 to 900° C.).

Therefore, when the fuel cell A is operated at a normal operating temperature, the first member 81 and the second member 83 do not melt. Therefore, when the fuel cell A is generating power in normal operation, the sealing member 80 does not melt and maintains its shape, thereby suppressing leakage of fuel gas and the like.

Here, when the fuel cell A is operated at a temperature at which the seal member 80 is higher than or equal to the second softening point temperature and lower than the first softening point temperature (second operation mode described later), the second member 83 of the seal member 80 is The first member 81 is not melted and maintains its shape and the like. The sealing temperature during normal operation is, for example, 500 to 650°C, although it is not limited thereto. Further, the temperature which is higher than the sealing temperature during normal operation and which is higher than the second softening point temperature and lower than the first softening point temperature is, for example, 650 to 850°C. Further, the first softening point temperature or higher is, for example, a temperature exceeding 900°C.

For example, suppose that in the cylindrical and flat plate type fuel cell module 23, a damaged portion 85 occurs in the sealing member 80 at the joint portion between the fuel cell A and the manifold M, as shown in FIG. In this case, fuel gas leaks from the manifold M. Therefore, by operating the fuel cell A at an operating temperature higher than the normal operating temperature (normal operating temperature in the first operating mode) (high temperature in the second operating mode), the sealing member 80 The temperature becomes higher than or equal to the softening point temperature and lower than the first softening point temperature, resulting in a fluid state. In this case, since the sealing temperature of the sealing member 80 is lower than the first softening point temperature, the first member 81 does not melt. On the other hand, since the sealing temperature of the sealing member 80 is equal to or higher than the second softening point temperature, the second member 83 is melted. Therefore, if damage such as cracking or peeling occurs in the sealing member 80, the first member 81 will not melt and maintain its shape by heating as described above, but the second member 81 will not melt as shown in FIG. 83 melts to compensate for and repair the damaged portion 85 of the first member 81. In the sealing member 80 of FIGS. 6 and 7, since the second member 83 to be melted is placed above the first member 81, by heating the sealing member 80 as described above, the melting second member 83 is placed above the first member 81. The second member 83 melts and enters the damaged portion 85 of the first member 81 due to gravity. Thereby, the damaged portion 85 of the first member 81 can be compensated for and repaired by the second member 83. Therefore, even if the seal member 80 is damaged, by repairing it, the joint portion can be sealed and leakage of fuel gas or the like can be suppressed.

As described above, when the seal member 80 is damaged, the first member 81 of the seal member 80 is not melted, but the second member 83 is melted into a fluid state, thereby repairing the damaged portion 85 of the seal member 80. In this case, by heating the fuel cell A to a high temperature, the second member 83 is melted and brought into a fluid state to some extent; however, the second member 83 may melt too much and flow out of the joint, or the material may partially melt. It is necessary to suppress the volatilization of the It is preferable to take these points into consideration and select materials for the first member 81 and the second member 83 as appropriate.

For example, the first softening point temperature of the first member 81 and the second softening point temperature of the second member 83 are higher than the sealing temperature of the first member 81 and the second member 83 at a normal operating temperature (for example, 700 to 750° C.). It is preferable that the temperature is higher by 30°C or more, and even more preferably by 100°C or more. As a result, the first member 81 and the second member 83 do not melt at the normal operating temperature of the fuel cell A and can maintain their shape as the seal member 80. Therefore, even when the fuel cell A is in normal operation, the sealing member 80 stably provides a sealing function.

Further, the first softening point temperature of the first member 81 is preferably 60° C. or more higher than the second softening point temperature of the second member 83, and more preferably 150° C. or more higher. As a result, by operating the fuel cell A at a temperature where the sealing member 80 is higher than or equal to the second softening point temperature and lower than the first softening point temperature, the second member 83 is melted while maintaining the shape of the first member 81. The damaged portion 85 of the first member 81 can be repaired by making up for it with the melted second member 83.

Moreover, it is preferable that the material of the first member 81 and the second member 83 is an isotropic material. As a result, stress caused by anisotropic thermal expansion of the seal member 80 can be suppressed, and variation in strength due to the direction in which stress is applied can also be suppressed, so that it is possible to suppress the strength of the seal member 80 from being partially reduced, and the joining It is possible to obtain a stable sealing member 80 that can firmly seal the portion. Further, even when the damaged portion 85 of the first member 81 is repaired with the second member 83, since the seal member 80 can be made of an isotropic material, it is possible to suppress a partial decrease in strength.

Examples of materials that can be used for such a sealing member 80 include amorphous glasses such as SiO ₂ -B ₂ O ₃ series, SiO ₂ -CaO series, MgO-B ₂ O ₃ series, crystallized glass, α - It is possible to use glass whose shape is maintained by a filler such as heat-resistant ceramic particles such as alumina. As the first member 81, a material satisfying the first softening point temperature is selected from these materials. Similarly, for the second member 83, a material satisfying the second softening point temperature is selected from these materials.
Note that crystallized glass is, for example, glass in which the volume occupied by the crystalline phase is 60% or more and the volume occupied by the amorphous phase or the like is less than 40% of the total volume.

(b) Flat-plate fuel cell module The flat-plate fuel cell module 23 will be explained using FIGS. 8 to 11.
The flat plate type fuel cell module 23 includes a first separator 101 that accommodates the fuel cell A, and a second separator 101 in which grooves 103a and 103b for supplying fuel gas and oxidant gas to the plane of the fuel cell A are formed. Separators 103 are alternately stacked in the Z direction.

The fuel cell A is housed in the center of the first separator 101. The fuel cell A is formed by laminating an air electrode layer 115, an electrolyte layer 113, and a fuel electrode layer 111 in order from the bottom to the top in the Z direction, and a current collecting member 117 is stacked on the fuel electrode layer 111. has been done. The first separator 101 has an opening formed in the center so as to expose the upper and lower surfaces of the fuel cell A.

The second separator 103 has a groove 103a and a groove 103b at a position corresponding to the center portion of the first separator 101 where the fuel cell A is arranged. The groove 103a is formed on the lower surface of the second separator 103 in order to supply fuel gas to the fuel electrode layer 111 of the fuel cell A. That is, according to FIG. 8, in the second separator 103 facing the fuel electrode layer 111 side of the first separator 101, the groove 103a on the lower surface thereof corresponds to the fuel electrode layer 111. In this embodiment, the groove 103a is formed to extend along the X direction in FIG. Furthermore, four grooves 103a are formed spaced apart in the Y direction.

On the other hand, the groove 103b is formed on the upper surface of the second separator 103 in order to supply oxidant gas to the air electrode layer 115. That is, according to FIG. 8, in the second separator 103 facing the air electrode layer 115 side of the first separator 101, the groove 103b on the upper surface thereof corresponds to the air electrode layer 115. In this embodiment, the groove 103b is formed to extend along the Y direction in FIG. Further, four grooves 103b are formed spaced apart in the X direction. Note that the grooves 103a and 103b are formed to be separated from each other by a predetermined interval.

In order to allow fuel gas and oxidant gas to flow through the grooves 103a and 103b of the second separator 103, openings are formed at the periphery of the stacked first separator 101 and second separator 103, respectively. The openings include an opening for supplying fuel gas and an opening for supplying oxidant gas. Specifically, the openings include a fuel gas supply path 121 inch for supplying fuel gas to the fuel cell A, a fuel gas discharge path 121 out for discharging fuel gas not used for power generation in the fuel cell A, An oxidizing gas supply path 123 inches for supplying oxidizing gas to the fuel cell A, and an oxidizing gas discharge path 123out for discharging the oxidizing gas not used for power generation in the fuel cell A are provided. .

The fuel gas supply path 121in and the fuel gas discharge path 121out are formed at the periphery of the first separator 101 and the second separator 103 so as to face each other in the X direction. Further, the fuel gas supply path 121in and the fuel gas discharge path 121out communicate with each other via the groove 103a. The fuel gas is supplied from below the fuel cell module 23, flows upward in the Z direction through the fuel gas supply path 121 inch (FGin in FIGS. 8 and 9), and is also supplied into the groove 103a. be done. As a result, fuel gas is supplied to the fuel electrode layer 111. The fuel gas that is not used for power generation in the fuel cell A is introduced into the fuel gas exhaust path 121out through the groove 103a. The discharged fuel gas flows downward in the Z direction through the fuel gas discharge path 121out (FGout in FIGS. 8 and 9), and is discharged to the outside of the fuel cell module 23.

The oxidant gas supply path 123in and the oxidant gas discharge path 123out are formed at the periphery of the first separator 101 and the second separator 103 so as to face each other in the Y direction. Further, the oxidant gas supply path 123in and the oxidant gas discharge path 123out communicate with each other via the groove 103b. The oxidizing gas is supplied from below the fuel cell module 23, flows upward in the Z direction through the oxidizing gas supply path 123in (OGin in FIGS. 8 and 10), and flows into the groove 103a. will also be supplied. As a result, the oxidant gas is supplied to the air electrode layer 115. The oxidizing gas that is not used for power generation in the fuel cell A is introduced into the oxidizing gas discharge path 123out through the groove 103b. The discharged oxidant gas flows downward in the Z direction through the oxidant gas discharge path 123out (OGout in FIGS. 8 and 10), and is discharged to the outside of the fuel cell module 23.

In the flat fuel cell module 23 as described above, the sealing member 80 is, for example, as shown in FIGS. 9 and 10, It is arranged at the joint portion (sealing member 80b) between the separator 101 and the second separator. By arranging the seal member 80 in this manner, leakage of fuel gas and the like can be suppressed.

FIG. 11 is an enlarged view showing the seal member 80a disposed at the joint between the fuel cell A and the first separator 101. The sealing member 80 of this embodiment is composed of a first member 81 and a second member 83, as shown in FIG. 11 and the like. In the example of FIG. 11, the first member 81 is located on the fuel cell A side, and the second member 83 is located on the first separator 101 side. The materials of the first member 81 and the second member 83 are the same as those of the seal member 80 described above.

For example, assume that in the flat plate type fuel cell module 23, a damaged portion 85 occurs in the seal member 80 as shown in FIG. By operating the fuel cell A at an operating temperature higher than the normal operating temperature (normal operating temperature in the first operating mode) (high temperature in the second operating mode), the sealing member 80 reaches the second softening point. The temperature becomes higher than or equal to the first softening point temperature and becomes a fluid state. In this case, since the sealing temperature of the sealing member 80 is lower than the first softening point temperature, the first member 81 does not melt. On the other hand, since the sealing temperature of the sealing member 80 is equal to or higher than the second softening point temperature, the second member 83 is melted. Therefore, if damage such as cracking or peeling occurs in the sealing member 80, the first member 81 will not melt and maintain its shape by heating as described above, but the second member 81 will not melt as shown in FIG. 83 melts to compensate for and repair the damaged portion 85 of the first member 81. Thereby, even if the seal member 80 is damaged, leakage of fuel gas or the like can be suppressed by repairing the seal member 80. The material of the seal member 80 is as described above.

In addition, although the above-mentioned FIGS. 12 and 13 describe repair of damage to the seal member 80a, damage to the seal member 80b can also be repaired in the same manner.

(c) Cylindrical Fuel Cell Module The cylindrical fuel cell module 23 will be explained using FIGS. 14 to 15.
The cylindrical fuel cell module 23 includes a cylindrical fuel cell A, a current collecting member 319, a fuel electrode terminal 321, and an air electrode terminal 325. In the fuel cell A, a fuel electrode layer 311, an electrolyte layer 313, and an air electrode layer 315 are laminated in order from the inside of the cylinder. The innermost fuel electrode layer 311 of the fuel cell A constitutes a fuel gas flow section 317 through which fuel gas flows. The current collecting member 319 is provided in contact with the outer surface of the air electrode layer 315 and receives supply of oxidizing gas.

The electrolyte layer 313 and the fuel electrode layer 311 are formed to protrude from the fuel cell A in the axial direction. A fuel electrode side terminal 321 is attached to the protruding electrolyte layer 313 and fuel electrode layer 311. On the other hand, an air electrode side terminal 325 is attached to a current collecting member 319 provided on the outer surface of the air electrode layer 315. The fuel electrode side terminal 321 is provided with a through hole 321a, and the air electrode side terminal 325 is provided with a through hole 325a. The through hole 321a, the fuel gas flow section 317, and the through hole 325a are in communication with each other, and fuel gas flows therethrough.

In the cylindrical and flat plate type fuel cell module 23 as described above, the sealing member 80 is configured to connect the fuel electrode side terminal 321, the electrolyte layer 313 and the fuel electrode layer protruding from the fuel cell A, as shown in FIGS. 14 and 15, for example. 311, and as shown in FIG. 14, it is arranged at the joint between the air electrode side terminal 325 and the air electrode layer 315. By arranging the seal member 80 at the joint portion between the fuel cell A and the terminal in this manner, leakage of fuel gas and the like can be suppressed.

For example, suppose that in the cylindrical fuel cell module 23, a damaged portion 85 occurs in the seal member 80 at the joint portion between the fuel cell A and the fuel electrode side terminal 321, as shown in FIG. In this case, fuel gas leaks outside the fuel cell module 23. Therefore, by operating the fuel cell A at an operating temperature higher than the normal operating temperature (normal operating temperature in the first operating mode) (high temperature in the second operating mode), the sealing member 80 The temperature becomes higher than or equal to the softening point temperature and lower than the first softening point temperature, resulting in a fluid state. In this case, since the sealing temperature of the sealing member 80 is lower than the first softening point temperature, the first member 81 does not melt. On the other hand, since the sealing temperature of the sealing member 80 is equal to or higher than the second softening point temperature, the second member 83 is melted. Therefore, if damage such as cracking or peeling occurs in the sealing member 80, the first member 81 will not melt and maintain its shape by heating as described above, but the second member 81 will not melt as shown in FIG. 83 melts to compensate for and repair the damaged portion 85 of the first member 81. Thereby, even if the seal member 80 is damaged, leakage of fuel gas or the like can be suppressed by repairing the seal member 80. The material of the seal member 80 is as described above.

(2) Seal Member Repair Method Executed by Operation Control Unit The operation control unit 71 of the fuel cell system 100 described above executes a repair method for repairing the seal member 80 when it is damaged.
(2-1) Overall flow of the repair method First, the overall flow of the repair method for the seal member 80 will be explained.
The operation control unit 71 operates in a first operation mode in which the fuel cell A is controlled to operate at a normal operating temperature, and in a second operation mode in which the fuel cell A is controlled to be operated at a higher temperature than the normal operating temperature. mode, and executes the second operation mode at a predetermined timing.

The first operation mode means, for example, normal operation in which the power generated by the fuel cell system 100 is supplied to a load or the like. The normal operating temperature in the first operating mode is the temperature of the fuel cell A in normal operation. Typical operating temperatures are, for example, 700 to 750°C, but are not limited thereto.

The operation control unit 71 controls the fuel gas supply amount by controlling the fuel gas pump 2, the oxidant gas supply amount by controlling the air blower 15, and the reforming water pump 7. The temperature of the fuel cell A is controlled by controlling the amount of water vapor, etc. Note that the operation control unit 71 refers to various temperatures and voltages detected by the cell temperature detection unit T1, combustion section temperature detection unit T2, catalyst temperature detection unit T3, voltage detection unit V, etc., and determines the temperature of the fuel cell A. control.

On the other hand, the second operation mode, unlike the first operation mode, refers to an operation when performing a repair method for repairing the seal member 80. The temperature of the fuel cell A in the second operation mode is higher than the normal operation temperature in the first operation mode, and the seal member 80 can be heated to a temperature higher than or equal to the second softening point temperature and lower than the first softening point temperature. 80, the temperature is such that the second member 83 can be melted and the first member 81 can be repaired. The operating temperature in the second operating mode is, for example, 780 to 900°C, although it is not limited thereto. A method of controlling the operating temperature in the second operating mode will be described later.

The operation control unit 71 executes the second operation mode for repairing the seal member 80 at a predetermined timing. The predetermined timing may be any timing or periodic timing. In addition, the operation control unit 71 may execute the second operation mode at the timing when leakage of fuel gas or the like is detected.
After starting the second driving mode, the driving control unit 71 may end the second driving mode at any timing, or may end the second driving mode after executing the second driving mode for a predetermined period. In addition, the second operation mode may be terminated based on the state of the fuel cell system 100 as described later.

As described above, by executing the second operation mode, the seal member 80 is melted and the damaged portion 85 is compensated for and repaired. Thereby, even if the seal member 80 is damaged, leakage of fuel gas or the like can be suppressed by repairing the seal member 80. Therefore, it is possible to suppress a decrease in power generation performance in the fuel cell A due to leakage of fuel gas and the like, and also to suppress adverse effects on the environment. Further, the seal member 80 can be repaired by adjusting the operating temperature of the fuel cell.

(2-2) Example of temperature control in second operation mode In the second operation mode, the operation control unit 71 is at a higher temperature than the normal operation temperature in the first operation mode, and the sealing member 80 is at a second softening point. The operation of the fuel cell A is controlled so that the temperature is equal to or higher than the first softening point temperature and lower than the first softening point temperature. Below, an example of a method for controlling the fuel cell A in the second operation mode to operate at a high temperature will be described.

In the second operation mode, the operation control unit 71 controls the fuel gas pump 2 to increase the amount of fuel gas supplied than in the first operation mode, thereby increasing the temperature of the fuel cell A. The amount of combustion increases in accordance with the increase in the amount of fuel gas supplied. Thereby, the temperature of the fuel cell A can be increased and the fuel cell A can be operated at a high temperature.

In the second operation mode, the operation control unit 71 controls the air blower 15 to reduce the amount of oxidant gas supplied than in the first operation mode, thereby increasing the temperature of the fuel cell A. When the supply amount of oxidant gas is reduced, cooling of the fuel cell A is suppressed. Thereby, the temperature of the fuel cell A can be increased and the fuel cell A can be operated at a high temperature.

In addition, when controlling the temperature to increase as described above, the operation control section 71 monitors the temperature of the fuel cell A detected by the cell temperature detection section T1, and when the temperature reaches a predetermined high temperature (the sealing member 80 Control is performed to raise the temperature to a temperature that is equal to or higher than the second softening point temperature and lower than the first softening point temperature. Then, when the temperature of the fuel cell A rises to a predetermined high temperature, the operation control unit 71 can stop the control to further increase the temperature.

Further, when controlling the temperature to a high temperature as described above, the operation control unit 71 can control the temperature to be gradually raised to the high temperature. This makes it possible to suppress deformation and cracking of the fuel cell A due to sudden thermal stress caused by a sudden temperature rise.

Further, the operation control unit 71 can gradually increase the temperature while checking whether the power generation performance of the fuel cell A has recovered. If fuel gas or the like leaks due to damage to the seal member 80, the amount of fuel gas or the like supplied to the fuel cell A decreases, and power generation performance deteriorates. Therefore, the operation control unit 71 determines that if the power generation performance of the fuel cell A remains degraded and has not recovered even though the temperature has been increased by a predetermined amount, the damage to the seal member 80 has not been repaired. As a result, the temperature is further increased to melt the sealing member 80 so that it can be repaired. Even in this case, it is preferable to stop the temperature increase at a predetermined high temperature (for example, 900° C.) from the viewpoint of preventing deformation and cracking of the fuel cell A. Note that, when the generated voltage detected by the voltage detection unit V is lower than the generated voltage in normal operation, the operation control unit 71 controls the temperature of the cell combustion exhaust gas detected by the combustion section temperature detection unit T2 to be lower than that in normal operation. If the temperature of the catalyst combustion exhaust gas detected by the catalyst temperature detection unit T3 remains higher than that during normal operation, the damage to the seal member 80 has not been repaired, and the power generation performance It is determined that the patient has not recovered.

On the other hand, if the power generation performance of the fuel cell A is recovered by increasing the temperature by a predetermined temperature, the operation control unit 71 controls to stop the further increase in temperature or return the temperature to normal operation. do. Note that, when the generated voltage detected by the voltage detection unit V is equal to or higher than the generated voltage in normal operation, the operation control unit 71 determines that the temperature of the cell combustion exhaust gas detected by the combustion section temperature detection unit T2 is normal. If the temperature of the catalyst combustion exhaust gas detected by the catalyst temperature detection unit T3 becomes the same as that during normal operation, the damage to the seal member 80 is repaired and power generation resumes. It is determined that performance has recovered.

In addition, when checking the power generation performance of the fuel cell A while gradually increasing the temperature, the operation control unit 71 operates the fuel cell A at a high temperature of 900° C. to repair the sealing member 80, and then It is preferable to once return the normal operating temperature to operate the fuel cell A and check the power generation performance of the fuel cell A at the normal operating temperature. After the power generation performance has been confirmed, if the power generation performance has not recovered, the operation control unit 71 operates the fuel cell A at a higher temperature than the previous temperature, for example, 920°C. If the power generation performance has recovered, the operation control unit 71 operates the fuel cell A at the normal operating temperature.

(2-3) Example of start condition for second operation mode The operation control unit 71 starts the second operation mode at a predetermined timing, such as an arbitrary timing, a regular timing, or a timing when a leak of fuel gas or the like is detected. Execute. Here, a description will be given of the start of the second operation mode at the timing when leakage of fuel gas or the like is detected.

The operation control section 71 executes the second operation mode when the temperature of the cell combustion exhaust gas detected by the combustion section temperature detection section T2 becomes larger than the starting combustion temperature threshold. When the temperature of the cell combustion exhaust gas discharged from the combustion section 29 becomes higher than the starting combustion temperature threshold, the power generation performance of the fuel cell A using the fuel gas and the oxidizing gas decreases, and the combustion This is a case where the combustion of unburned gas in the section 29 increases and the temperature of the cell combustion exhaust gas increases. In this case, the operation control unit 71 executes the second operation mode to repair the seal member 80 because the seal member 80 is damaged and fuel gas, oxidizing gas, etc. leak, resulting in a decrease in power generation performance. do. Note that the starting combustion temperature threshold is set, for example, to a temperature higher than the temperature of the cell combustion exhaust gas in the combustion section 29 during normal operation.

The operation control unit 71 executes the second operation mode when the temperature of the catalyst combustion exhaust gas detected by the catalyst temperature detection unit T3 becomes larger than the starting catalyst temperature threshold. When the temperature of the catalyst combustion exhaust gas discharged from the combustion catalyst section 35 becomes higher than the starting catalyst temperature threshold, the power generation performance of the fuel cell A using the fuel gas and the oxidizing gas decreases, This is a case where the combustion of unburned gas in the combustion catalyst section 35 increases and the temperature of the catalyst combustion exhaust gas rises. In this case, the operation control unit 71 executes the second operation mode to repair the seal member 80 because the seal member 80 is damaged and fuel gas, oxidizing gas, etc. leak, resulting in a decrease in power generation performance. do. Note that the starting catalyst temperature threshold is set, for example, to a temperature higher than the temperature of the catalyst combustion exhaust gas in the combustion catalyst section 35 during normal operation.

The operation control unit 71 executes the second operation mode when the generated voltage detected by the voltage detection unit V becomes smaller than the starting voltage threshold. A case where the power generation voltage of the fuel cell A detected by the voltage detection unit V becomes smaller than the starting voltage threshold is a case where the power generation performance of the fuel cell A using the fuel gas and the oxidizer gas decreases. It is. In this case, the operation control unit 71 executes the second operation mode to repair the seal member 80 because the seal member 80 is damaged and fuel gas, oxidizing gas, etc. leak, resulting in a decrease in power generation performance. do. Note that the starting voltage threshold is set, for example, to a voltage lower than the power generation voltage in fuel cell A during normal operation.

(2-4) Example of end condition for second operation mode The operation control unit 71 may control the fuel cell system 100 at any timing after starting the second operation mode, at any timing after executing the second operation mode for a predetermined period, or at any timing after the second operation mode has been executed for a predetermined period. The second operation mode is ended at a predetermined timing, such as a timing based on the state of. Here, the termination of the second operation mode at a timing based on the state of the fuel cell system 100 will be described.

When the temperature of the cell combustion exhaust gas discharged from the combustion section 29 becomes lower than the combustion temperature threshold for stopping, the operation control section 71 stops execution of the second operation mode. Note that the case where the temperature of the cell combustion exhaust gas discharged from the combustion section 29 becomes lower than the combustion temperature threshold for shutdown means that the power generation performance of the fuel cell A using the fuel gas and the oxidizing gas is improved. This is a case where the combustion of unburned gas in the combustion section 29 is reduced and the temperature of the combustion section 29 is lowered. In this case, the operation control unit 71 stops execution of the second operation mode, assuming that the damage to the seal member 80 has been repaired, leakage of fuel gas, oxidizing gas, etc. is suppressed, and deterioration in power generation performance is suppressed. .
Note that the combustion temperature threshold for shutdown is set, for example, to the temperature of the cell combustion exhaust gas in the combustion section 29 during normal operation.

When the temperature of the catalyst combustion exhaust gas discharged from the combustion catalyst section 35 becomes lower than the catalyst temperature threshold for stopping, the operation control section 71 stops execution of the second operation mode. Note that when the temperature of the catalyst combustion exhaust gas discharged from the combustion catalyst section 35 becomes lower than the catalyst temperature threshold for shutdown, the power generation performance of the fuel cell A using the fuel gas and the oxidant gas is improved. However, this is a case where the combustion of unburned gas in the combustion catalyst section 35 is reduced and the temperature is lowered. In this case, the operation control unit 71 stops execution of the second operation mode, assuming that the damage to the seal member 80 has been repaired, leakage of fuel gas, oxidizing gas, etc. is suppressed, and deterioration in power generation performance is suppressed. .
Note that the catalyst temperature threshold for stopping is set, for example, to the temperature of the catalyst combustion exhaust gas in the combustion catalyst section 35 during normal operation.

When the generated voltage of the fuel cell A detected by the voltage detection unit V becomes larger than the voltage threshold for stopping, the operation control unit 71 stops execution of the second operation mode. Note that when the power generation voltage detected by the voltage detection unit V becomes larger than the voltage threshold for stopping, the power generation performance of the fuel cell using fuel gas and oxidizer gas improves, and the power generation voltage increases. This is the case. In this case, the operation control unit 71 stops execution of the second operation mode, assuming that the damage to the seal member 80 has been repaired, leakage of fuel gas, oxidizing gas, etc. is suppressed, and deterioration in power generation performance is suppressed. .
Note that the stop voltage threshold is set, for example, to the power generation voltage of the fuel cell A during normal operation.

[Experiment example]
In the cylindrical and flat plate type fuel cell module 23 shown in FIGS. 2 to 5, a damaged portion 85 was formed in the seal member 80 as shown in FIG. The first member 81 is made of a glass material containing components such as Si and Al.
Further, the second member 83 is formed using glass frits A to C containing components such as B, Mg, Ca, and Ba. The compositions of glass frits A to C other than the amorphous glass are as follows. Each of the glass frits A to C is formed into a paste using terpineol as a dispersion medium, and is applied as a second member 83 on top of the first member 81.
Glass frit A: B6%, Mg12%, Al4%, Si6%, Ca3%, Zn10%, Ba19%
Glass frit B: B5%, Mg9%, Al3%, Si5%, Zn5%, Ba10%, La30%
Glass frit C: B5%, Mg12%, Al3%, Si5%, Ca5%, La33%

Ｔｇ：ガラス転移温度であり、ミクロな流動性が生じる温度
Ｔｓ：軟化点温度であり、マクロな流動性が出てくる温度
Ｔｃ：結晶化温度であり、ガラスの結晶化発熱が最大となる温度 The sealing member 80 formed from the first member 81 and the second member 83 having the above composition was applied to the joint portion between the fuel cell A and the manifold M, thereby creating a cylindrical flat plate type fuel cell module 23. While supplying fuel gas and oxidant gas to fuel cell A, the temperature was raised to 790° C. and operation was continued for 2 hours. The He gas leak concentration near the seal portion before the 2-hour operation and the He gas leak concentration near the seal portion after the 2-hour operation were measured using a He leak detector. The measurement results are as follows.

Tg: Glass transition temperature, the temperature at which micro fluidity occurs Ts: Softening point temperature, the temperature at which macro fluidity appears Tc: Crystallization temperature, the temperature at which the heat of crystallization of the glass is maximum

As shown in the above results, when fuel cell A is operated at 790°C using glass frits A to C for the second member 83, the amount of He gas leaked is smaller after operation than before operation. are doing. On the other hand, when the seal member 80 is formed only of the first member 81 without including the second member 83, the amount of leakage increases after operation than before operation. This means that the damaged portion 85 of the first member 81 has not been repaired and He gas is leaking.
From this result, it can be seen that the damaged portion 85 of the seal member 80 is repaired by the second member 83 melting and entering.

[Other embodiments]
Note that the configuration disclosed in the above embodiment (including other embodiments, the same applies hereinafter) can be applied in combination with the configuration disclosed in other embodiments, as long as there is no contradiction, and The embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the purpose of the present invention.

(1) In the sealing member 80 of the above embodiment shown in FIG. 5 and the like, the second member 83 that melts is arranged above the first member 81. However, the arrangement relationship between the first member 81 and the second member 83 is not limited to this. As shown in FIG. 18, the first member 81 may be placed above the second member, or the first member 81 and the second member 83 may be placed side by side in the left-right direction. Further, the sealing member 80 may be configured such that the first member 81 is held between the second member 83. Further, it is sufficient that the second member 83 can repair the damaged portion 85 of the first member 81, and a separate intervening layer may be disposed between the first member 81 and the second member 83.
Further, the second member 83 does not need to cover the entire surface of the first member 81, and may cover a part of the surface of the first member 81.

(2) In the above embodiment, the operation control unit 71 operates the fuel cell A at an operating temperature higher than the normal operating temperature, so that the sealing member 80 is heated to a temperature higher than the second softening point temperature and a first softening point temperature. The seal member 80 has been repaired as being less than 100%. However, it is only necessary to heat the seal member 80 to a temperature higher than or equal to the second softening point temperature and lower than the first softening point temperature, and there is no need to change the operating state of the fuel cell A when repairing the seal member 80. For example, as shown in FIG. 19, a heater (heating section) 75 may be disposed inside the storage container 40 of the fuel cell power generation device 1, and the seal member 80 may be heated by the heater 75. In this case, the heating section control section 73 heats the heater 75 at an arbitrary timing, at a regular timing, or at a timing when leakage of fuel gas or the like is detected, as described above, and heats the heater 75 at a temperature higher than the second softening point temperature or at a first temperature. The sealing member 80 is controlled to be heated below its softening point temperature.

(3) In the above embodiment, as an example of a method for the molten second member 83 to enter the damaged portion 85 of the first member 81, the second member 83 placed above the first member 81 and in a fluid state The manner in which it enters the damaged portion 85 of the first member 81 has been explained. However, the second member 83 in a fluid state may enter the damaged portion 85 of the first member 81 due to the suction force of pressure from the damaged portion 85 side. Other modes of penetration include capillary action and the like.

(4) In the above embodiment, the normal operating temperature in the first operating mode was 700 to 750°C, and the operating temperature in the second operating mode was 780 to 900°C. The second softening point temperature of the second member 83 was set to 700°C or higher, and the first softening point temperature of the first member 81 was set to 900°C or higher. However, since the sealing temperature of the sealing member 80 in the second operation mode is equal to or higher than the sealing temperature of the sealing member 80 at the normal operating temperature, and satisfies the condition that the sealing temperature is equal to or higher than the second softening point temperature and lower than the first softening point temperature. If so, the normal operating temperature, the operating temperature in the second operating mode, the first softening point temperature, and the second softening point temperature are not limited to these.

23: Fuel cell module 71: Operation control section 73: Heating section control section 75: Heater 80: Seal member 81: First member 83: Second member 85: Damaged part 100: Fuel cell system A: Fuel cell M: Manifold

Claims (16)

A sealing member applied to a joint portion that joins constituent members of a fuel cell module having fuel cell cells,
a first member made of a material that melts at an operating temperature higher than the normal operating temperature of the fuel cell and has a first softening point temperature;
a second member made of a material that melts at an operating temperature higher than the normal operating temperature of the fuel cell and has a second softening point temperature lower than the first softening point temperature of the first member. fruit ,
A sealing member , wherein the first member and the second member are made of an isotropic material . The seal member according to claim 1 , wherein the first member and the second member are adjacent to each other. The seal member according to claim 2, wherein the second member is located above the first member. The seal member according to claim 2 or 3 , wherein the second member is arranged to cover a surface of the first member. The seal member according to claim 1, wherein the first softening point temperature and the second softening point temperature are 30° C. or more higher than the temperature of the seal member during normal operation. The seal member according to any one of claims 1 to 5 , wherein the first softening point temperature is 60° C. or more higher than the second softening point temperature. a plurality of fuel cells each having a fuel gas passage through which fuel gas flows;
a manifold that communicates with the fuel gas passage by inserting one end of the plurality of fuel cells and supplies the fuel gas to the fuel gas passage;
a sealing member applied to a joint between one end of the fuel cell and the manifold ,
The sealing member includes a first member made of a material that melts at an operating temperature higher than the normal operating temperature of the fuel cell and has a first softening point temperature; a second member made of a material that melts at an operating temperature of and has a second softening point temperature lower than the first softening point temperature of the first member . A first operating mode is executable in which the fuel cell is controlled to be operated at a normal operating temperature, the operating temperature is higher than the normal operating temperature of the fuel cell, and the second softening mode is The fuel cell according to claim 7 , further comprising an operation control unit that executes a second operation mode that controls the fuel cell to operate so as to heat the seal member at a temperature higher than or equal to the first softening point temperature. system. The fuel cell system according to claim 7 or 8, wherein the first member and the second member are made of isotropic material . The fuel cell system according to claim 7, wherein the first member and the second member are adjacent to each other. The fuel cell system according to claim 10, wherein the second member is located above the first member. The fuel cell system according to claim 10 or 11, wherein the second member is arranged to cover a surface of the first member. 13. The fuel cell system according to claim 7, wherein the first softening point temperature and the second softening point temperature are 30° C. or more higher than the temperature of the seal member during normal operation. The fuel cell system according to any one of claims 7 to 13, wherein the first softening point temperature is 60° C. or more higher than the second softening point temperature. A fuel cell module having a fuel cell and in which the constituent members are joined together by the sealing member according to any one of claims 1 to 6 , which is applied to a joint portion where the constituent members are joined together; A method for repairing the seal member in a fuel cell system comprising an operation control unit that controls operation of a fuel cell,
The operation control unit is configured to control a first operation mode to operate the fuel cell at a normal operating temperature, and a second operation mode in which the operating temperature is higher than the normal operating temperature of the fuel cell. A method for repairing a sealing member, which is capable of carrying out a second operation mode in which the fuel cell is operated so as to be able to heat the sealing member at a temperature higher than the point temperature and lower than the first softening point temperature. A fuel cell module having a fuel cell and in which the constituent members are joined by the sealing member according to any one of claims 1 to 6 , which is applied to a joint portion where the constituent members are joined together; A method for repairing a seal member in a fuel cell system comprising: a heating section; and a heating section control section for controlling the heating section.
The heating unit control unit controls the heating unit to heat the sealing member at a temperature higher than or equal to the second softening point temperature and lower than the first softening point temperature.

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