JP6719070B2 - High temperature operating fuel cell and fuel cell system. - Google Patents

Description

The present disclosure relates to a high temperature operation fuel cell and a fuel cell system.

In a fuel cell system, fuel gas and air are supplied to a fuel cell stack, which is the main body of a power generation unit, and an electrochemical reaction between hydrogen in fuel gas and oxygen in air proceeds. As a result, the chemical energy generated in the fuel cell can be extracted as electrical energy. For this reason, since it is possible to easily use the heat energy generated during the power generation operation together with the high-efficiency power generation, development and commercialization are being promoted as a distributed power generation system having high energy use efficiency.

For example, Patent Document 1 discloses a configuration in which a fuel cell stack is directly stacked on an upper portion of a medium supply plate provided with a gas supply flow path. Further, in Patent Document 2, a housing that accommodates a heat exchanger, a reformer, and a fuel cell stack includes an exhaust hole that exhausts combustion exhaust gas, and the exhaust hole is provided below the fuel cell stack. A configuration is disclosed.

Japanese Patent No. 5322950 JP, 2005-95300, A

However, the conventional example still has room for improvement from the viewpoint of preheating characteristics of air sent to the fuel cell stack and the viewpoint of downsizing of the device.

One aspect of the present disclosure has been made in view of such circumstances, and provides a high-temperature operation fuel cell and a fuel cell system capable of preheating air sent to the fuel cell stack more efficiently than before. To do. Further, one aspect of the present disclosure provides a high temperature operation type fuel cell and a fuel cell system capable of downsizing the device as compared with the related art.

In order to solve the above problems, a high temperature operation type fuel cell according to an aspect of the present disclosure includes a plurality of cells stacked in a flat plate shape, a fuel cell stack that generates electric power using fuel gas and air, a side surface and a top surface. An inner wall having a bottom surface and a bottom surface, the inner wall being installed so as to surround the fuel cell stack, a side surface, a top surface and a bottom surface, and an outer wall being installed so as to surround the inner wall, and a top surface of the inner wall and the outer wall. A first air path formed between the inner wall and a top surface of the inner wall, a second air path formed between a side surface of the inner wall and a side surface of the outer wall, and a bottom surface of the inner wall and a bottom surface of the outer wall. A third air path, an air inflow path connected to the first air path, an air supply port for supplying the air from the third air path to the fuel cell stack, and the fuel cell A fuel gas supply path for supplying the fuel gas to a stack, wherein the air is the air inflow path, the first air path, the second air path, the third air path, and the air supply port. Through in this order, and the bottom surface of the inner wall is in surface contact with the fuel cell stack.

In order to solve the above problems, a fuel cell system according to one aspect of the present disclosure is
A high temperature operating fuel cell as described above,
A reformer that generates a hydrogen-containing reformed gas by reforming a raw material as the fuel gas, an evaporator that generates steam to be supplied to the reformer, and an anode discharged from the fuel cell stack. A hydrogen generator comprising a combustor in which off-gas and cathode off-gas are diffused and combusted, and an air heat exchanger in which the combustion exhaust gas generated in the combustor and the air exchange heat.
Equipped with
The hydrogen generator is disposed above the high temperature operation type fuel cell, and the air that has undergone heat exchange in the air heat exchanger is sent to the first air path, and a horizontal cross section of the high temperature operation type fuel cell. Area is larger than the horizontal cross-sectional area of the hydrogen generator.

The high-temperature operation type fuel cell and the fuel cell system according to one aspect of the present disclosure have an effect that the air sent to the fuel cell stack can be preheated more efficiently than before. Further, the high-temperature operation type fuel cell and the fuel cell system according to one aspect of the present disclosure have an effect that the device can be downsized as compared with the related art.

FIG. 1 is a diagram showing an example of a high temperature operation type fuel cell of the first embodiment. FIG. 2A is a diagram showing an example of a high temperature operation type fuel cell of a first modified example of the first embodiment. FIG. 2B is a diagram showing an example of a high temperature operation type fuel cell of a first modified example of the first embodiment. FIG. 2C is a diagram showing an example of a high temperature operation type fuel cell of a first modified example of the first embodiment. FIG. 3 is a diagram showing an example of a high temperature operation type fuel cell of a second modified example of the first embodiment. FIG. 4 is a diagram showing an example of a high temperature operation type fuel cell of a third modified example of the first embodiment. FIG. 5: is a figure which shows an example of the high temperature operation type fuel cell of 2nd Embodiment. FIG. 6 is a diagram showing an example of the fuel cell system of the third embodiment.

The following findings were obtained through intensive studies on the preheating characteristics of the air sent to the fuel cell stack and the miniaturization of the device.

As in the fuel cell system of Patent Document 1, a solid oxide fuel cell is installed above a medium supply plate provided with a gas supply channel, and the medium is supplied via the side surface of the solid oxide fuel cell. When air is supplied to the fuel cell from the plate, it is necessary to supply high temperature air to the solid oxide fuel cell. Therefore, before supplying air to the medium supply plate, a separate heat exchanger for preheating such air is often provided. However, there is a possibility that downsizing of the fuel cell system may be difficult due to the positional relationship between the solid oxide fuel cell and the heat exchanger, the method of routing the gas pipe to the medium supply plate, and the like. On the contrary, if such a heat exchanger is not provided, preheating of air may be insufficient.

In Patent Document 2, as described above, the housing that accommodates the heat exchanger, the reformer, and the fuel cell stack has the exhaust hole that discharges the combustion exhaust gas, and the exhaust hole is provided on the lower side of the fuel cell stack. There is. In such a fuel cell system, in order to preheat the air supplied to the fuel cell, a separate heat exchanger that uses the heat of the combustion exhaust gas discharged from the exhaust holes to heat the air is often provided. However, downsizing of the fuel cell system may be difficult due to the positional relationship between the housing and the heat exchanger, the method of routing the gas piping to the housing, and the like. On the contrary, if such a heat exchanger is not provided, preheating of air may be insufficient.

That is, the inventors have found matters to be improved regarding the conventional example as described above, and have conceived the following one mode of the present disclosure.

That is, the high-temperature operation type fuel cell according to the first aspect of the present disclosure includes a plurality of cells stacked in a flat plate shape, a fuel cell stack that generates electric power using fuel gas and air, a side surface, a top surface, and a bottom surface. Between the inner wall installed so as to surround the fuel cell stack, the side surface, the top surface and the bottom surface, and the outer wall installed so as to surround the inner wall, and between the top surface of the inner wall and the top surface of the outer wall. A first air path formed, a second air path formed between a side surface of the inner wall and a side surface of the outer wall, a third air path formed between a bottom surface of the inner wall and a bottom surface of the outer wall, 1 an air inflow path connected to the air path, an air supply port for supplying air from the bottom surface of the fuel cell stack to the fuel cell stack, and a fuel gas supply path for supplying fuel gas to the fuel cell stack , The air passes through the air inflow path, the first air path, the second air path, the third air path, and the air supply port in this order, and the bottom surface of the inner wall is in surface contact with the fuel cell stack.

According to this structure, the high temperature operation type fuel cell of this aspect can preheat the air sent to the fuel cell stack more efficiently than before. Further, the high temperature operation type fuel cell of this aspect can be downsized as compared with the conventional one.

Specifically, all of the top surface, the side surface, and the bottom surface of the inner wall installed so as to surround the fuel cell stack function as a heat transfer surface for heating the air sent to the fuel cell stack. That is, the heat generated by the power generation of the high-temperature operation type fuel cell can utilize the radiant heat from the fuel cell stack to heat the air to an appropriate temperature through the inner wall provided around the fuel cell stack.

In particular, since the bottom surface of the inner wall corresponding to the third air path through which the air just before flowing into the fuel cell stack is in surface contact with the high temperature fuel cell stack, the air flowing through the third air path is The heat transfer of the stack enables efficient heating.

Further, when the air path to be supplied to the fuel cell stack is configured by piping or the like, a region for routing the piping is required, and thus it may be difficult to downsize the high temperature operation type fuel cell.

On the other hand, in the high temperature operation type fuel cell of this aspect, as described above, the bottom surface of the inner wall is in surface contact with the fuel cell stack. Therefore, it is possible to reduce such wiring of the pipe, and thus the above possibility can be reduced.

A high temperature operation type fuel cell according to a second aspect of the present disclosure is the high temperature operation type fuel cell according to the first aspect, wherein the bottom surface of the inner wall includes a step portion protruding upward from the bottom surface, and the step portion and the fuel cell stack are provided. Are in surface contact.

With such a configuration, the high-temperature operation fuel cell according to this aspect can efficiently heat the air flowing through the third air passage even when the protrusion protruding downward from the bottom surface of the fuel cell stack is present. This is for the following reason.

Depending on the configuration of the fuel cell stack, there may be a case where a protrusion such as a fastening bolt for fastening a plurality of cells or a power take-out portion is provided on the bottom surface of the fuel cell stack.

Therefore, in the high temperature operation type fuel cell of this aspect, by providing the above step portion, even if such a protrusion exists, the protrusion does not contact the bottom surface of the inner wall, and the fuel cell It can be configured for proper surface contact with the stack. Therefore, the air flowing through the third air path can be efficiently heated by the heat transfer of the fuel cell stack.

A high temperature operation type fuel cell according to a third aspect of the present disclosure is the high temperature operation type fuel cell according to the first aspect or the second aspect, and an anode off gas discharge path in which anode off gas discharged from the fuel cell stack is aggregated, And a cathode off-gas discharge path where the cathode off-gas discharged from the fuel cell stack is concentrated, and the anode off-gas discharge path and the cathode off-gas discharge path extend upward to a combustor in which diffusion combustion is performed.

According to such a configuration, each of the anode offgas discharge path and the cathode offgas discharge path is connected to the combustor. As a result, diffusion combustion is performed in the combustor. At this time, it is not necessary to route these anode offgas discharge path and cathode offgas discharge path to the side of the high temperature operation type fuel cell, so that the structure of the gas pipe is simplified. Further, when the anode off-gas discharge path and the cathode off-gas discharge path are routed to the side of the high temperature operation type fuel cell, the installation area of the high temperature operation type fuel cell may increase. Can be reduced.

A fuel cell system according to a fourth aspect of the present disclosure is
A high temperature operating fuel cell of the first aspect;
A reformer that generates a hydrogen-containing reformed gas by reforming a raw material as a fuel gas, an evaporator that generates steam to be supplied to the reformer, an anode off gas and a cathode discharged from the fuel cell stack. A hydrogen generator including a combustor in which off-gas diffuses and burns, and an air heat exchanger in which combustion exhaust gas generated in the combustor and air exchange heat,
Equipped with
The hydrogen generator is arranged above the high temperature operating fuel cell, and the air that has undergone heat exchange in the air heat exchanger is sent to the first air path. Larger than the area of the horizontal cross section of the generator.

With this configuration, the fuel cell system according to this aspect can preheat the air sent to the fuel cell stack more efficiently than before. Further, the fuel cell system of this aspect can be made smaller than the conventional one.

Specifically, the air sent to the fuel cell stack uses heat exchange of the air heat exchanger and radiant heat on the top surface, side surface and bottom surface of the inner wall installed so as to surround the fuel cell stack,
The air sent to the fuel cell stack can be efficiently preheated as compared with the conventional case.

In addition, in the fuel cell system, the hydrogen generator is arranged above the high temperature operation type fuel cell, and the horizontal cross section of the high temperature operation type fuel cell has a larger area than the horizontal cross section of the hydrogen generation apparatus. Therefore, even if the air heat exchanger for preheating the air supplied to the high temperature operation type fuel cell is provided, it is possible to suppress an increase in the installation area of the fuel cell system.

Moreover, since the electrode area per cell can be increased by increasing the horizontal cross-sectional area of the high temperature operating fuel cell, it is also possible to increase the output of the high temperature operating fuel cell.

Hereinafter, a first embodiment of the present disclosure, first to third modifications of the first embodiment, a second embodiment, and a third embodiment of the present disclosure will be described with reference to the accompanying drawings. In addition, 1st Embodiment, 1st-3rd modification of 1st Embodiment, 2nd Embodiment, and 3rd Embodiment which are demonstrated below all show one specific example of this indication. That is, the numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, and connection forms shown below are all examples and do not limit the present disclosure. Further, among the constituent elements shown below, the constituent elements that are not described in the independent claims defining the top concept of the present disclosure are described as arbitrary constituent elements. Further, in the drawings, description of components having the same reference numerals may be omitted. Further, the drawings schematically show the respective constituents for the sake of easy understanding, and the shapes and the dimensional ratios may not be displayed accurately.

(First embodiment)
FIG. 1 is a diagram showing an example of a high temperature operation type fuel cell of the first embodiment.

Hereinafter, as a specific example of the high temperature operation type fuel cell, a solid oxide fuel cell 100 (hereinafter, SOFC 100) including a solid oxide fuel cell stack 1 (hereinafter, SOFC stack 1) in a power generation section will be described as an example. , But is not limited to this. The high temperature operating fuel cell may have any configuration as long as it is a fuel cell that operates at a high temperature (for example, 600° C. or higher).

In FIG. 1 (other drawings are the same), for convenience, “upper” and “lower” are taken as in the same figure, and gravity acts from top to bottom. In addition, the direction vertical to the vertical direction in which gravity acts (sometimes called the vertical direction) is called the horizontal direction, and the plane including this horizontal direction is called the horizontal plane.

In the example shown in FIG. 1, the SOFC 100 includes an SOFC stack 1, an inner wall 2, an outer wall 3, a first air path 5, a second air path 6, a third air path 7, and an air supply port 8. A fuel gas supply path 9 and an air inflow path 4 are provided.

The inner wall 2 of the SOFC 100 includes a side surface 2S, a top surface 2U, and a bottom surface 2D, and is installed so as to surround the SOFC stack 1. That is, the inner wall 2 connects the top surface 2U that covers the entire upper surface of the SOFC stack 1 from above, the bottom surface 2D that covers the entire lower surface of the SOFC stack 1 from below, and the end portion of the top surface 2U and the end portion of the bottom surface 2D. Thus, the side surface 2S that is erected in the vertical direction is provided.

The outer wall 3 of the SOFC 100 includes a side surface 3S, a top surface 3U, and a bottom surface 3D, and is installed so as to surround the inner wall 2. That is, the outer wall 3 includes a top surface 3U that covers the entire top surface 2U of the inner wall 2 from above, a bottom surface 3D that covers the entire bottom surface 2D of the inner wall 2 from below, an end portion of the top surface 3U and an end portion of the bottom surface 3D. And a side surface 3S standing upright in the vertical direction so as to connect to each other.

The side surface 3S of the outer wall 3 is arranged coaxially outside the side surface 2S of the inner wall 2 with a predetermined gap. The top surface 3U of the outer wall 3 is disposed above the top surface 2U of the inner wall 2 with a predetermined gap. The bottom surface 3D of the outer wall 3 is arranged below the bottom surface 2D of the inner wall 2 with a predetermined gap.

Each of the above gaps is a space through which the air supplied to the SOFC stack 1 passes.

Specifically, the first air path 5 is formed between the top surface 2U of the inner wall 2 and the top surface 3U of the outer wall 3. The second air passage 6 is formed between the side surface 2S of the inner wall 2 and the side surface 3S of the outer wall 3. The third air passage 7 is formed between the bottom surface 2D of the inner wall 2 and the bottom surface 3D of the outer wall 3.

Here, in the SOFC 100 of the present embodiment, the air inflow path 4 is connected to the first air path 5. Specifically, the air inflow path 4 extends in the vertical direction with respect to the top surface 3U of the outer wall 3, and an opening corresponding to the downstream end of the air inflow path 4 is formed in the top surface 3U.

The bottom surface 2D of the inner wall 2 and the SOFC stack 1 are in surface contact with each other, and the air supply port 8 is an opening for supplying air from the third air path 7 to the SOFC stack 1. Therefore, here, the air supply port 8 is formed near the center of the bottom surface 2D of the inner wall 2.

As described above, the air for power generation of the SOFC stack 1 passes through the air inflow path 4, the first air path 5, the second air path 6, the third air path 7 and the air supply port 8 in this order. Specifically, the air from the air inflow passage 4 flows horizontally outward from the downstream end of the air inflow passage 4 in the first air passage 5. Then, the air turns at a right angle at the downstream end of the first air path 5 and flows vertically downward in the second air path 6. After that, the air turns to the right angle again at the downstream end of the second air path 6, flows horizontally inward in the third air path 7, and flows into the SOFC stack 1 from the air supply port 8.

Both the inner wall 2 and the outer wall 3 may be made of a metal such as stainless steel having high corrosion resistance.

In the SOFC 100 of the present embodiment, both the side surface 2S of the inner wall 2 and the side surface 3S of the outer wall 3 are configured in a cylindrical shape in plan view, and the top surface 2U and the bottom surface 2D of the inner wall 2 and the top surface 3U of the outer wall 3 and Each of the bottom surfaces 3D has a disc shape. However, the shapes of the inner wall 2 and the outer wall 3 are not limited to this. For example, the side surface 2S of the inner wall 2 and the side surface 2S of the outer wall 3 may be a rectangular body, or a shape obtained by combining a part of a cylindrical body and a part of a rectangular body (for example, a pair of semicircular portions). And an oval-shaped cylindrical body including a pair of straight portions.

However, it is advantageous that the side surface 2S of the inner wall 2 and the side surface 2S of the outer wall 3 are formed in a cylindrical shape or an oval shape, as compared with the case where the side surface 2S is formed in a rectangular shape.

Further, since the operating temperature of the SOFC 100 becomes high (for example, 600° C. or higher), the outer wall 3 of the SOFC 100 is often covered with a heat insulating material (not shown) to suppress heat radiation to the outside.

The fuel gas supply path 9 is a flow path for supplying the fuel gas to the SOFC stack 1. Specifically, the fuel gas supply path 9 extends from the outside of the SOFC 100 so as to vertically and airtightly penetrate the top surface 3U of the outer wall 3 and the top surface 2U of the inner wall 2 and connect to the SOFC stack 1. Examples of the fuel gas include reformed gas and hydrogen gas. When the fuel gas is reformed gas, the upstream end of the fuel gas supply path 9 is connected to an appropriate reformer. Further, the reformed gas (anode off gas) not used for power generation of the SOFC stack 1 is burned in the combustor. Details of the reformer and the combustor will be described later.

The SOFC stack 1 includes a plurality of cells (not shown) stacked in a flat plate shape, and uses fuel gas and air to generate power. That is, the SOFC stack 1 is composed of a flat plate-shaped stack in which members such as a flat plate-shaped single cell and an interconnector are laminated, and the cathode of the SOFC stack 1 is supplied with air from the air supply port 8 described above. The fuel gas from the fuel gas supply path 9 is supplied to the anode of the stack 1, and power generation is performed using oxygen in the air and hydrogen in the fuel gas.

The SOFC 100 includes a temperature detector (not shown) that detects the operating temperature of the SOFC stack 1 (for example, 600° C. or higher), a power extraction unit (not shown) that extracts the power of the SOFC stack 1. It is provided. Since the internal structure of the SOFC stack 1 is similar to that of a general flat plate type SOFC stack, detailed description and illustration of the structure are omitted.

As described above, the SOFC 100 of this embodiment can preheat the air to be sent to the SOFC stack 1 more efficiently than before. Further, the SOFC 100 of this embodiment can be downsized as compared with the conventional one.

Specifically, all of the top surface 2U, the side surface 2S, and the bottom surface 2D of the inner wall 2 installed so as to surround the SOFC stack 1 function as a heat transfer surface on which the air sent to the SOFC stack 1 is heated. That is, the heat generated by the power generation of the SOFC 100 can use the radiant heat from the SOFC stack 1 to heat the air to an appropriate temperature via the inner wall 2 installed around the SOFC stack 1.

Particularly, since the bottom surface 2D of the inner wall 2 corresponding to the third air path 7 through which the air immediately before flowing into the SOFC stack 1 and the SOFC stack 1 in the high temperature state are in surface contact, the air flowing through the third air path 7 Can be efficiently heated by the heat transfer of the SOFC stack 1.

Further, when the air path to be supplied to the SOFC stack 1 is composed of a pipe or the like, a region for routing the pipe is required, and thus it may be difficult to downsize the SOFC 100.

On the other hand, in the SOFC 100 of this embodiment, as described above, the bottom surface 2D of the inner wall 2 and the SOFC stack 1 are in surface contact with each other. Therefore, it is possible to reduce such wiring of the pipe, and thus the above possibility can be reduced.

(First modification)
In the SOFC 100 of the first embodiment, an example has been described in which the top surface 2U of the inner wall 2 that forms the first air path 5 is formed of a horizontal surface that covers the entire upper surface of the SOFC stack 1 from above, but the present invention is not limited to this. ..

For example, as shown in FIG. 2A, the top surface 2U of the inner wall 2 forming the first air path 5 may be a horizontal surface that covers only the end portion of the upper surface of the SOFC stack 1 from above. As a result, the horizontal surface facing only the end portion of the upper surface of the SOFC stack 1 functions as a heat transfer surface for heating the air sent to the SOFC stack 1.

Further, as shown in FIG. 2B, the top surface 2U of the inner wall 2 forming the first air path 5 may be an inclined surface that covers only the end portion of the upper surface of the SOFC stack 1 from above. Thereby, the inclined surface facing only the end portion of the upper surface of the SOFC stack 1 functions as a heat transfer surface for heating the air sent to the SOFC stack 1.

Further, as shown in FIG. 2C, the top surface 2U of the inner wall 2 that constitutes the first air path 5 covers only the end portion of the upper surface of the SOFC stack 1 from above, and covers the horizontal plane of FIG. 2A and the inclined surface of FIG. 2B. It may be a curved surface having a plurality of broken lines that are combined. Thereby, the bent surface facing only the end portion of the upper surface of the SOFC stack 1 functions as a heat transfer surface for heating the air sent to the SOFC stack 1.

The SOFC 100 of this modification may be configured similarly to the SOFC 100 of the first embodiment, except for the above features.

(Second modified example)
In the SOFC 100 of the first embodiment, an example has been described in which the entire top surface 2U, side surface 2S, and bottom surface 2D of the inner wall 2 function as a heat transfer surface for heating the air sent to the SOFC stack 1, but the present invention is not limited to this. Absent. Part of the top surface 2U, the side surface 2S, and the bottom surface 2D of the inner wall 2 may not fulfill such a function of the heat transfer surface.

For example, in order to insert a sensing unit of a temperature detector for detecting the temperature of the SOFC stack 1, a busbar for taking out the electric power of the SOFC stack 1 and the like into the container of the SOFC 100, these wirings 20 are connected to the inner wall 2 and It is necessary to take a configuration that penetrates the outer wall 3 in an airtight manner. At this time, as shown in FIG. 3, the welded portions of the wiring 20 and the inner wall 2 and the outer wall 3 often use a throttle structure in which the inner wall 2 and the outer wall 3 are partially joined to each other. In this case, the inner wall 2 corresponding to the throttle structure does not function as a heat transfer surface.

Although not shown, for example, when a rod member is sandwiched between the inner wall 2 and the outer wall 3 so that the gap between the inner wall 2 and the outer wall 3 is maintained at a constant size, the inner wall 2 or the outer wall 3 There is a case where the protrusion is formed from 3. In these cases, the inner wall 2 corresponding to the rod member and the protrusion does not function as a heat transfer surface.

Further, although not shown, for example, in the gap between the inner wall 2 and the outer wall 3, an annular straightening plate having ventilation holes uniformly formed in the circumferential direction so that the air flow can be made uniform in the circumferential direction. May be provided. In this case, the inner wall 2 corresponding to the current plate does not function as a heat transfer surface.

The SOFC 100 of this modification may be configured similarly to the SOFC 100 of the first embodiment, except for the above features.

(Third modification)
FIG. 4 is a diagram showing an example of a high temperature operation type fuel cell of a third modified example of the first embodiment.

In the example illustrated in FIG. 4, the SOFC 100 includes an SOFC stack 1, an inner wall 12, an outer wall 3, a first air path 5, a second air path 6, a third air path 7, and an air supply port 8. A fuel gas supply path 9 and an air inflow path 4 are provided.

The SOFC stack 1, the outer wall 3, the first air passage 5, the second air passage 6, the third air passage 7, the air supply port 8, the fuel gas supply passage 9, and the air inflow passage 4 are the same as those in the first embodiment. Therefore, the description is omitted.

In the SOFC 100 of this modification, the bottom surface 12D of the inner wall 12 includes a step portion 12E protruding upward from the bottom surface 12D. The step portion 12E and the SOFC stack 1 are in surface contact with each other.

Depending on the configuration of the SOFC stack 1, the bottom surface of the SOFC stack 1 may be provided with, for example, a fastening bolt that fastens a plurality of cells, a protrusion such as a power extraction portion, or the like.

Here, a plurality of protrusions 30 projecting downward from the corners of the bottom surface of the SOFC stack 1 are illustrated.

Therefore, in the SOFC 100 of the present modification, the step portion 12E has a horizontal dimension (width dimension) of the step portion 12E smaller than the horizontal interval between the protrusions 30 and a vertical dimension (step size) of the step portion 12E. The height is set to be longer than the dimension of the protrusion 30 in the vertical direction, and is erected vertically from the bottom surface 12D of the inner wall 12.

As described above, even when the protrusion 30 protruding downward from the bottom surface of the SOFC stack 1 exists, the protrusion 30 does not contact the bottom surface 12D of the inner wall 12 and the surface of the step portion 12E and the SOFC stack 1 in a high temperature state. And can be appropriately surface-contacted. Therefore, the air flowing through the third air path 7 can be efficiently heated by the heat transfer of the SOFC stack 1.

The SOFC 100 of this modification may be configured similarly to the SOFC 100 of the first embodiment, except for the above features.

(Second embodiment)
FIG. 5: is a figure which shows an example of the high temperature operation type fuel cell of 1st Embodiment.

In the example shown in FIG. 5, the SOFC 100 includes an SOFC stack 1, an inner wall 2, an outer wall 3, a first air path 5, a second air path 6, a third air path 7, and an air supply port 8. The fuel gas supply path 9, the air inflow path 4, the anode off-gas exhaust path 10, and the cathode off-gas exhaust paths 11A and 11B are provided.

The SOFC stack 1, the inner wall 2, the outer wall 3, the first air passage 5, the second air passage 6, the third air passage 7, the air supply port 8, the fuel gas supply passage 9 and the air inflow passage 4 are the same as those in the first embodiment. The description is omitted because it is similar.

The anode off-gas discharge path 10 is a flow path where the anode off-gas discharged from the SOFC stack 1 is collected. The anode off-gas exhaust path 10 extends upward to a combustor not shown in FIG.

Specifically, the fuel gas (anode off gas) not used for power generation of the SOFC stack 1 flows into the anode off gas discharge passage 10, passes through the anode off gas discharge passage 10, and is then sent to the combustor. In the SOFC 100 of the present embodiment, the anode off-gas discharge path 10 is arranged above the anode of the SOFC stack 1 so as to airtightly penetrate the top surface 2U of the inner wall 2 and the top surface 3U of the outer wall 3 to communicate with the fuel space of the combustor. Is stretched to. Although the number of the anode off-gas discharge paths 10 is one here, it may be two or more.

The cathode off-gas discharge paths 11A and 11B are channels for collecting the cathode off-gas discharged from the SOFC stack 1. The cathode offgas discharge path 11B extends upward to a combustor not shown in FIG.

Specifically, the air (cathode off gas) not used for power generation of the SOFC stack 1 is sent to the combustor after passing through the cathode off gas discharge paths 11A and 11B. In the SOFC 100 of the present embodiment, the cathode offgas discharge path 11A is formed in the space between the outer shell of the SOFC stack 1 and the top surface 2U and side surface 2S of the inner wall 2. The cathode off-gas discharge path 11B extends upward from the top surface 2U of the inner wall 2 to the top surface 3U of the outer wall 3 in an airtight manner so as to communicate with the fuel space of the combustor. Although the number of the cathode off-gas discharge paths 11B is one here, it may be two or more. Further, the cathode offgas discharge port 11C of the SOFC stack 1 is formed on the side surface of the SOFC stack 1, but such a discharge port may be formed on the upper surface of the SOFC stack 1. In this case, the cathode offgas discharge path 11A is formed in the space between the outer shell of the SOFC stack 1 and the top surface 2U of the inner wall 2.

As described above, each of the anode offgas discharge path 10 and the cathode offgas discharge path 11B is connected to the combustor. As a result, diffusion combustion is performed in the combustor. At this time, it is not necessary to route the anode off-gas discharge path 10 and the cathode off-gas discharge path 11B to the side of the SOFC 100, so that the structure of the gas pipe is simplified. Further, when the anode off-gas discharge path 10 and the cathode off-gas discharge path 11B are routed to the side of the SOFC 100, the installation area of the SOFC 100 may increase, but the above configuration can reduce such a possibility.

In the SOFC 100 of the present modification, the combustor is arranged apart from the SOFC 100 by using the anode offgas exhaust path 10 and the cathode offgas exhaust path 11B. However, the SOFC 100 is A combustor may be provided.

The SOFC 100 of this embodiment may be configured similarly to the SOFC 100 of the first embodiment, except for the above features.

(Third Embodiment)
FIG. 6 is a diagram showing an example of the fuel cell system of the third embodiment.

In the example shown in FIG. 6, the fuel cell system 200 includes the hydrogen generator 50 and the SOFC 100. The SOFC 100 according to the present embodiment is similar to the SOFC 100 according to the third embodiment and will not be described.

As shown in FIG. 6, the hydrogen generator 50 is arranged above the SOFC 100 and includes an evaporator 51, a reformer 52, a combustor 53, and an air heat exchanger 54.

The reformer 52 generates hydrogen-containing reformed gas as the fuel gas by reforming the raw material. The outer shell of the reformer 52 may be formed of, for example, a stainless cylindrical body filled with a reforming catalyst. The reformer 52 is arranged above the combustor 53.

As shown in FIG. 6, the high-temperature combustion exhaust gas passes through the space between the wall portion of the reformer 52 and the inner wall 55A of the storage container 55 of the hydrogen generator 50. As a result, the reforming catalyst of the reformer 52 is heated by the heat of the combustion exhaust gas, and the temperature of the reformer 52 becomes a high temperature (for example, 600° C. or higher) suitable for the reforming reaction. The details of the combustor 53 that generates such combustion exhaust gas will be described later.

Further, the pipe forming the fuel gas supply path 9 airtightly penetrates from the reformer 52 to the outer wall 3 and the inner wall 2 of the SOFC 100 and extends to the SOFC stack 1. As a result, the reformed gas from the reformer 52 is supplied to the anode of the SOFC stack 1 through the fuel gas supply path 9.

The reforming reaction of the reformer 52 may take any form. Examples of the reforming reaction include a steam reforming reaction, an autothermal reaction and a partial oxidation reaction. As the catalytic metal of the reforming catalyst, generally, at least one selected from the group consisting of noble metal-based catalysts such as Pt, Ru and Rh and Ni can be used. Although not shown in FIG. 6, the equipment necessary for the above-mentioned reforming reaction is appropriately provided. For example, if the reforming reaction is an autothermal reaction, the hydrogen generator 50 is provided with an air supplier (for example, a blower) that supplies air to the reformer 52.

As the raw material for the reforming reaction, a hydrocarbon-based fuel gas containing an organic compound composed of at least carbon and hydrogen such as city gas containing methane as a main component, natural gas, and LPG may be used. Hydrocarbon-based liquid fuels such as alcohol, biofuel, and light oil may be used.

In the hydrogen generator 50 of this embodiment, a steam reforming reaction is performed as the reforming reaction of the reformer 52. Therefore, the evaporator 51 is provided directly above the reformer 52.

The evaporator 51 generates steam to be supplied to the reformer 52. Specifically, for example, water is supplied to the evaporator 51 from a water supply port 62 connected to a water supplier (not shown) (for example, a pump). Further, the raw material is supplied to the evaporator 51 from a raw material supply port 63 connected to a raw material supply device (not shown) (for example, a pump). In the evaporator 51, water is evaporated to generate steam, and the raw material and steam are mixed. Then, the mixed gas is sent to the reforming catalyst of the reformer 52.

As shown in FIG. 6, the high-temperature combustion exhaust gas passes through the space between the wall portion of the evaporator 51 and the inner wall 55A of the storage container 55 of the hydrogen generator 50. At this time, since the outer surface of the wall of the evaporator 51 is exposed to the combustion exhaust gas having a temperature higher than the boiling point of water (for example, about 100° C. to 300° C.), the water is exposed to the heat of the combustion exhaust gas. As the temperature rises and vaporizes, the steam and the raw fuel are mixed appropriately.

The air supply path 56 is a flow path through which air to be sent to the cathode of the SOFC stack 1 flows. Specifically, the air from the air supply port 61 connected to an air supply device (not shown) (for example, a blower) is formed between the inner wall 55A and the outer wall 55B of the storage container 55 of the hydrogen generator 50. It circulates through the air supply path 56.

The air heat exchanger 54 exchanges heat between the combustion exhaust gas generated in the combustor 53 and air. Specifically, the air flowing through the air supply path 56 and the combustion exhaust gas flowing inside the inner wall 55A of the storage container 55 exchange heat. That is, in the air heat exchanger 54, the portion of the inner wall 55A exposed by the combustion exhaust gas functions as a heat transfer surface. As a result, when the air at room temperature flows from the upper side to the lower side in the air supply path 56, it is heated by heat exchange with the combustion exhaust gas flowing from the lower side to the upper side in the inner wall 55A.

The air that has undergone heat exchange in the air heat exchanger 54 is sent to the first air path 5 through the air inflow path 4 described above. That is, the air that has undergone heat exchange in the air heat exchanger 54, after passing through the air inflow path 4, further uses the radiant heat from the SOFC stack 1 to reach a temperature suitable for the power generation reaction of the SOFC stack 1. Be heated.

In the combustor 53, the anode off gas and the cathode off gas discharged from the SOFC stack 1 are diffused and burned. Specifically, the combustor 53 is connected to each of the anode offgas discharge path 10 and the cathode offgas discharge path 11B. Then, in the combustion space of the combustor 53, the anode off gas is supplied through the anode off gas discharge path 10 and the cathode off gas is supplied through the cathode off gas discharge path 11B, and these gases are diffused and burned. As a result, high-temperature combustion exhaust gas is generated in the combustion space.

The combustion exhaust gas generated in the combustor 53 is, as described above, between the wall portion of the reformer 52 and the inner wall 55A of the storage container 55 and between the wall portion of the evaporator 51 and the inner wall 55A of the storage container 55. Pass through the space from bottom to top in this order. Since the suitable temperature of the reforming reaction and the suitable temperature of water evaporation become lower in this order, the heat of the combustion exhaust gas generated in the combustor 53 can be effectively used by flowing the combustion exhaust gas in the above order.

The combustion exhaust gas is cooled to an appropriate temperature (for example, about 100° C. to 200° C.) and then discharged from the combustion exhaust gas discharge port 64 to the outside of the fuel cell system 200 to generate hot water for hot water supply, for example. It is sent to a heat exchanger (not shown).

Here, in the fuel cell system 200 of the present embodiment, the horizontal cross-sectional area of the SOFC 100 is larger than the horizontal cross-sectional area of the hydrogen generator 50. The area of the horizontal cross section of the SOFC 100 refers to the area of the horizontal plane formed by the outermost horizontal member (in this example, the side surface 3S of the outer wall 3) of the container of the SOFC 100. The area of the horizontal cross section of the hydrogen generator 50 refers to the area of the horizontal plane formed by the outermost horizontal member (outer wall 55B in this example) of the storage container 55 of the hydrogen generator 50.

As described above, the fuel cell system 200 of the present embodiment can preheat the air to be sent to the SOFC stack 1 more efficiently than before. Further, the fuel cell system 200 of the present embodiment can be downsized as compared with the conventional one.

Specifically, the air sent to the fuel cell stack 1 uses heat exchange of the air heat exchanger 54 and radiant heat from the top surface 2U, the side surface 2S, and the bottom surface 2D of the inner wall 2 installed so as to surround the fuel cell stack 1. Then, it is preheated more efficiently than before.

Further, the hydrogen generator 50 is arranged above the SOFC 100, and the horizontal cross section of the SOFC 100 has a larger area than the horizontal cross section of the hydrogen generator 50. Therefore, even if the air heat exchanger 54 for preheating the air supplied to the SOFC 100 is provided, an increase in the installation area of the fuel cell system 200 can be suppressed.

Moreover, since the electrode area per cell can be increased by increasing the area of the horizontal cross section of the SOFC 100, it is possible to increase the output of the SOFC 100.

That is, in order to increase the output of the flat-plate SOFC 100, there are a method of increasing the number of stacked cells to increase the voltage during power generation, a method of increasing the current density during power generation, a method of increasing the electrode area per cell, and the like. Can be mentioned.

Among these methods, the method of increasing the number of stacked cells tends to cause a temperature distribution in the stacking direction during operation, and thus the stack may be cracked by thermal stress.

Further, in the method of increasing the current density during power generation, hydrogen supply shortage is likely to occur in a region where the current density is high, and thus the configuration of the cell stack may be restricted.

Therefore, in the fuel cell system 200 of this embodiment, the output of the SOFC 100 is increased by increasing the electrode area per cell. That is, in the SOFC 100, the horizontal cross section of the SOFC 100 has a large area so that the electrode area of the cell can be secured in a desired area. Further, the horizontal cross section of the hydrogen generator 50 is configured to have a small area so that the storage container 55 that stores the evaporator 51, the reformer 52, the combustor 53, and the like can be appropriately reduced in size and cost.

In this way, in the fuel cell system 200 of the present embodiment, both high output, small size, and low cost of the fuel cell system 200 are appropriately achieved.

The first embodiment, the first to third modifications of the first embodiment, the second embodiment, and the third embodiment may be combined with each other as long as they do not exclude each other.

For example, in the SOFC 100 of the second embodiment, an example in which the SOFC 100 of the first embodiment includes the anode offgas discharge passage 10 and the cathode offgas discharge passages 11A and 11B has been described, but the third modification of the first embodiment. The SOFC 100 may include the anode offgas discharge path 10 and the cathode offgas discharge paths 11A and 11B. Further, for example, the example in which the fuel cell system 200 of the third embodiment includes the SOFC 100 of the first embodiment has been described, but the fuel cell system 200 of the third embodiment is the same as that of the third modification of the first embodiment. The SOFC 100 may be provided.

Many modifications and other embodiments of the present disclosure will be apparent to those skilled in the art from the above description. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the present disclosure. Details of its structure and/or function may be changed substantially without departing from the spirit of this disclosure.

For example, in the fuel cell system 200, the housing container 55 of the hydrogen generator 50 and the housing container of the SOFC 100 may be configured separately when assembled. That is, the air inflow passage 4, the fuel gas supply passage 9, the anode off-gas discharge passage 10 and the cathode off-gas discharge passage 11B are properly placed, and the air inflow passage 4, the fuel gas supply passage 9, the anode off-gas discharge passage 10 and the cathode off-gas discharge are provided. By connecting the paths 11B to each other by welding or the like, the storage containers configured separately may be finally assembled. As a result, the fuel cell system is configured so that only the connecting portions of the air inflow path 4, the fuel gas supply path 9, the anode offgas discharge path 10 and the cathode offgas discharge path 11B are matched regardless of the shape, size, etc. of the SOFC 100. 200 can be assembled.

The high temperature operation type fuel cell and the fuel cell system of one aspect of the present disclosure can preheat the air sent to the fuel cell stack more efficiently than before. Further, the high-temperature operation type fuel cell and the fuel cell system according to one aspect of the present disclosure can reduce the size of the device as compared with the related art. Therefore, one embodiment of the present disclosure can be used in, for example, a high temperature operation type fuel cell and a fuel cell system.

1: Solid oxide fuel cell stack (SOFC stack)
2: Inner wall 2D: Bottom surface 2S: Side surface 2U: Top surface 3: Outer wall 3D: Bottom surface 3S: Side surface 3U: Top surface 4: Air inflow path 5: First air path 6: Second air path 7: Third air path 8 : Air supply port 9: Fuel gas supply route 10: Anode off gas discharge route 11A: Cathode off gas discharge route 11B: Cathode off gas discharge route 11C: Discharge port 12: Inner wall 12D: Bottom face 12E: Step portion 20: Wiring 30: Projection 50 : Hydrogen generator 51: Evaporator 52: Reformer 53: Combustor 54: Air heat exchanger 55: Storage container 55A: Inner wall 55B: Outer wall 56: Air supply path 61: Air supply port 62: Water supply port 63: Raw material supply port 64: Combustion exhaust gas discharge port 100: Solid oxide fuel cell (SOFC)
200: Fuel cell system

Claims (6)

A fuel cell stack that includes a plurality of cells stacked in a flat plate shape and that uses fuel gas and air to generate power;
An inner wall provided with a side surface, a top surface, and a bottom surface, which is installed so as to surround the fuel cell stack,
An outer wall provided with a side surface, a top surface, and a bottom surface, which is installed so as to surround the inner wall,
A first air path formed between the top surface of the inner wall and the top surface of the outer wall;
A second air path formed between a side surface of the inner wall and a side surface of the outer wall;
A third air path formed between the bottom surface of the inner wall and the bottom surface of the outer wall;
An air inflow path connected to the first air path,
An air supply port for supplying the air to the fuel cell stack from the three air paths;
A fuel gas supply path for supplying the fuel gas to the fuel cell stack;
A cathode off-gas discharge path through which air not used for power generation of the fuel cell stack passes,
Equipped with
The air passes through the air inflow path, the first air path, the second air path, the third air path, and the air supply port in this order, and the bottom surface of the inner wall and the fuel cell stack are in surface contact with each other. The high-temperature operating fuel cell in which the cathode off-gas discharge path is formed in a space between the outer shell of the fuel cell stack and the top surface of the inner wall and the side surface of the inner wall . The high temperature operating fuel cell according to claim 1, wherein the fuel gas supply path penetrates the top surface of the outer wall and the top surface of the inner wall and extends so as to be connected to the fuel cell stack. The high temperature operating fuel cell according to claim 2, wherein the fuel gas supply path is connected to an upper surface of the fuel cell stack. The high temperature operation fuel according to any one of claims 1 to 3 , wherein a bottom surface of the inner wall includes a step portion protruding upward from the bottom surface, and the step portion and the fuel cell stack are in surface contact with each other. battery. Further comprising an anode off-gas discharge path for collecting the anode off-gas discharged from the fuel cell stack,
The high temperature operating fuel cell according to any one of claims 1 to 4, wherein the anode off-gas discharge path and the cathode off-gas discharge path extend upward to a combustor in which diffusion combustion is performed. A high temperature operating fuel cell according to any one of claims 1 to 5 ,
A reformer that generates a hydrogen-containing reformed gas by reforming a raw material as the fuel gas, an evaporator that generates steam to be supplied to the reformer, and an anode discharged from the fuel cell stack. A hydrogen generator comprising a combustor in which off-gas and cathode off-gas are diffused and combusted, and an air heat exchanger in which the combustion exhaust gas generated in the combustor and the air exchange heat.
Equipped with
The hydrogen generator is disposed above the high temperature operating fuel cell,
Air having undergone heat exchange in the air heat exchanger is sent to the first air path,
A fuel cell system in which the horizontal cross-sectional area of the high-temperature operation fuel cell is larger than the horizontal cross-sectional area of the hydrogen generator.

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