JP3796182B2 - Fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell in which a cell stack in which a plurality of fuel cells are gathered is stored in a storage container.
[0002]
[Prior art]
In recent years, various types of fuel cells in which a stack of fuel cells is stored in a storage container have been proposed as next-generation energy.
[0003]
A solid oxide fuel cell is configured by storing a cell stack composed of a plurality of fuel cells in a storage container. Power generation is performed by supplying an oxygen-containing gas and a fuel gas to the cell stack at about 600 to 1000 ° C. It was done at high temperature.
[0004]
However, since a fuel cell using a solid electrolyte has a high operating temperature of 600 to 1000 ° C., it is necessary to heat the fuel cell up to this temperature, and there is a problem that it takes a long time to substantially generate power. In order to solve such problems, conventionally, a preheater for preheating oxygen-containing gas (air) is provided outside the storage container, and the oxygen-containing gas is heated by the preheater and then supplied to the cell stack. It has been proposed to heat the cell and shorten the startup time.
[0005]
In addition, the fuel gas and oxygen-containing gas that were not used for power generation are combusted, this high-temperature combustion gas is routed to the outside of the storage container by piping, and heat is supplied along the piping for supplying the oxygen-containing gas to the inside of the storage container. It has been proposed to perform the exchange and preheat the oxygen-containing gas using the combustion gas.
[0006]
[Problems to be solved by the invention]
However, according to the various methods described above, the inside of the storage container becomes hot during normal operation, but this heat is generally released to the outside by gas, or is released to the outside through the storage container, so that the heat in the storage container is The effective use of was not enough.
[0007]
In the above method, when the fuel cell is started, a heated oxygen-containing gas is introduced into the cell stack, and the fuel cell is heated by the heated oxygen-containing gas. The heating efficiency of the cell is low, and it still takes time to start up. There was a problem that it took.
[0008]
An object of the present invention is to provide a fuel cell that can effectively use heat.
[0009]
[Means for Solving the Problems]
The fuel cell of the present invention is made by housing a cell stack in which a plurality of fuel cells are assembled in the housing container, a fuel cell which generates power by supplying an oxygen-containing gas and fuel gas in the cell stack, the receiving container A combustion chamber provided adjacent to the cell stack, in which surplus oxygen-containing gas and fuel gas derived from the cell stack are combusted to generate combustion gas, and provided adjacent to the combustion chamber. A heat exchange unit that introduces combustion gas and oxygen-containing gas from the combustion chamber and exchanges heat, and an oxygen-containing gas heated by the heat exchange unit through the combustion chamber is supplied to the cell stack. together formed by providing an oxygen-containing gas supply pipe, the inside of the side wall of the container at a side of the cell stack and the combustion chamber, provided with side walls passage of the oxygen-containing gas supplied from the outside Oxygen-containing gas of the side wall flow passage via the heat exchanger, characterized in that it is supplied to the cell stack.
[0010]
In such a fuel cell, the oxygen-containing gas from the outside is supplied to the cell stack through the side wall flow passage. Therefore, during normal operation, the oxygen-containing gas in the side wall flow passage is heated by the heat of the cell stack. The heated oxygen-containing gas is supplied to the cell stack, and the power generation efficiency can be increased by effectively using the heat generated in the storage container.
[0011]
On the other hand, at the time of start-up, by supplying oxygen-containing gas preheated to some extent (for example, 600 ° C.) into the side wall flow passage, the fuel cell of the cell stack provided on the side of the side wall flow passage can be heated and The preheated oxygen-containing gas in the flow passage is introduced into the fuel cell of the cell stack via, for example, an oxygen-containing gas supply pipe, and the fuel cell can be heated by the oxygen-containing gas. It is possible to start up quickly by effectively using.
[0012]
Further, in the present invention, a combustion chamber provided adjacent to the cell stack, in which surplus oxygen-containing gas and fuel gas derived from the cell stack are combusted to generate combustion gas, and adjacent to the combustion chamber. A heat exchange part for introducing and exchanging heat by introducing combustion gas from the combustion chamber and oxygen-containing gas in the side wall passage, and oxygen-containing gas heated by the heat exchange part through the combustion chamber. A plurality of oxygen-containing gas supply pipes supplied to the cell stack are provided in a storage container.
[0013]
In such a fuel cell, surplus fuel gas and oxygen-containing gas that have not been used for power generation in the cell stack are introduced into the combustion chamber and reacted and burned in the combustion chamber. The oxygen-containing gas is introduced into the heat exchanging portion, and the heat exchanging portion exchanges heat between the combustion gas and the oxygen-containing gas, thereby heating the oxygen-containing gas. By supplying the contained gas supply pipe to the cell stack, the power generation efficiency can be improved, and at the time of start-up, the fuel cell temperature can be rapidly heated to the power generation temperature, and the start-up time until power generation can be substantially shortened.
[0014]
Furthermore, since the oxygen-containing gas supply pipe passes through the combustion chamber, the oxygen-containing gas heated in the heat exchange unit can be further heated.
[0015]
In addition, since the combustion gas and the oxygen-containing gas can be heat-exchanged in the storage container, it can be downsized, and the combustion gas can be used effectively, and the high-temperature combustion gas can be directly introduced into the heat exchange part in the storage container. The reduction of the combustion gas temperature can be minimized, and the oxygen-containing gas can be heated effectively with a simple structure.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of a fuel cell according to the present invention. Reference numeral 31 denotes a storage container having a heat insulating structure. Inside the storage container 31, a cell stack 35 in which a plurality of fuel battery cells 33 are gathered, a combustion chamber 37 adjacent above the cell stack 35, and an oxygen-containing gas supply pipe 39 inserted through the combustion chamber 37. And the heat exchange part 41 provided above the combustion chamber 37 is provided.
[0020]
The storage container 31 includes a frame body 31a made of a heat-resistant metal and a heat insulating material 31b provided on the inner surface of the frame body 31a.
[0021]
In the cell stack 35, for example, as shown in FIG. 2, a plurality of fuel cells 33 are arranged in three rows, and electrodes of two adjacent outermost fuel cell cells 33 are connected by a conductive member 42. Thus, the plurality of fuel cells 33 arranged in three rows are electrically connected in series.
[0022]
More specifically, the fuel battery cell 33 has a flat cross section and an overall elliptical cylinder shape, and a plurality of fuel gas passages 34 are formed therein. The fuel cell 33 has a flat cross section, and a dense solid electrolyte 33b, porous conductivity on the outer surface of a fuel side electrode 33a mainly composed of a porous metal having an elliptical columnar shape as a whole. The oxygen side electrode 33c made of ceramics is sequentially laminated, and an interconnector 33d is formed on the outer surface of the fuel side electrode 33a opposite to the oxygen side electrode 33c. The fuel side electrode 33a serves as a support. .
[0023]
A current collecting member 43 made of metal felt and / or a metal plate is interposed between one fuel cell 33 and the other fuel cell 33, and the fuel side electrode 33a of one fuel cell 33 is connected to the fuel cell 33. A cell stack 35 is configured by being electrically connected to the oxygen side electrode 33 c of the other fuel battery cell 33 via an interconnector 33 d provided on the fuel side electrode 33 a and a current collecting member 43.
[0024]
As shown in FIG. 1, the upper and lower ends of the plurality of fuel cells 33 are supported and fixed to the support members 45 and 47, thereby forming a cell stack 35. The support members 45 and 47 also serve as partition walls for partitioning the storage container 31 in the vertical direction. A portion where the fuel side electrode 33a, the solid electrolyte 33b, and the oxygen side electrode 33c overlap between the support members 45 and 47 generates power. The power generation chamber 49 is formed between the support members 45 and 47.
[0025]
The portion where the fuel side electrode 33a, the solid electrolyte 33b, and the oxygen side electrode 33c overlap is present in the center of the power generation chamber 49, and at both ends of the fuel cell 33, the oxygen side electrode 33c is formed on the upper surface of the solid electrolyte 33b. The area | region which is not formed is formed, and the both ends of the fuel cell 33 do not contribute to electric power generation. Both ends of the fuel cell 33 where the oxygen side electrode 33c is not formed are supported and fixed to the support members 45 and 47. The dense solid electrolyte 33b prevents gas mixing inside and outside the solid electrolyte 33b in the power generation chamber 49.
[0026]
A fuel gas supply pipe 51 for supplying fuel gas to the cell stack 35 is provided below the cell stack 35, and the fuel gas is supplied to each fuel gas passage of the fuel cell 33 in the fuel gas supply pipe 51. A branch pipe 52 to be supplied to 34 is formed.
[0027]
A burner gas supply pipe 53 for directly heating the fuel cells is disposed below the fuel gas supply pipe 51, and the burner gas supply pipe 53 is used for combustion in the power generation chamber 49. A plurality of cell heating burners 55 are provided.
[0028]
The tip of the cell heating burner 55 is fixed to the support member 47. The power generation chamber 49 is provided with an ignition source (not shown) for igniting the gas ejected from the cell heating burner 55 at startup.
[0029]
FIG. 3 shows an enlarged view of the cell heating burner 55 and its vicinity. As shown in FIG. 3, the oxygen-side electrode 33c is not formed on the solid electrolyte 33b in the vicinity of the support member 47, and a heat insulating layer 56 made of glass is formed instead. The heat insulating layer 56 is formed on the side of a combustion region F (indicated by a broken line) of gas ejected from the cell heating burner 55.
[0030]
The heat insulating layer 56 may be made of ceramic in addition to glass, but it is desirable to use glass from the viewpoint of good adhesion. The heat insulating layer 56 is formed in a range that minimizes the influence of combustion of the cell heating burner 55.
[0031]
Further, as shown in FIG. 1, the oxygen-containing gas supply pipe 39 that passes through the combustion chamber 37 passes through the support member 45, and its tip is located below the power generation chamber 49 and located between the fuel cells 33. ing. Excess oxygen-containing gas that has not been used in power generation is configured to be ejected into the combustion chamber 37 from an excess gas ejection hole 57 provided in the support member 45. The combustion chamber 37 is also provided with an ignition source for igniting at startup.
[0032]
The heat exchange unit 41 includes a heat exchanger 41 a and an oxygen-containing gas storage chamber 41 b provided to face the cell stack 35 via the combustion chamber 37.
[0033]
As shown in FIG. 4, the heat exchanger 41 a has a plate fin type structure in which flat plates 61 and corrugated plates 63 are alternately stacked. The corrugated plate 63 a that forms a passage communicating with the oxygen-containing gas storage chamber 41 b 4 (b), and a corrugated plate 63b that forms a passage for discharging combustion gas is formed as shown in FIG. 4 (c).
[0034]
The combustion gas is introduced from the lower side surface of the heat exchanger 41a as shown by a one-dot chain line in FIG. 1, and is discharged to the upper side of the heat exchanger 41a, while the oxygen-containing gas is shown by a broken line in FIG. Is introduced from the upper side surface of the heat exchanger 41a, led to the lower side of the heat exchanger 41a, and introduced into the oxygen-containing gas storage chamber 41b.
[0035]
As shown in FIG. 5, the oxygen-containing gas storage chamber 41b is provided on the end surface of the heat exchanger 41a on the side where the oxygen-containing gas is introduced, that is, the end surface on the cell stack side, and passes through each passage of the corrugated plate 63a. The oxygen-containing gas is temporarily stored.
[0036]
One ends of a plurality of oxygen-containing gas supply pipes 39 are opened and communicated with the oxygen-containing gas storage chamber 41b.
[0037]
Further, as shown in FIG. 1, the combustion gas in the combustion chamber 37 is transferred to the heat exchanger 41a between the side surface of the oxygen-containing gas storage chamber 41b and the heat insulating material 31b, that is, around the oxygen-containing gas storage chamber 41b. The combustion gas inlet 71 is introduced. The combustion gas is led out to the passage of the corrugated plate 63b of the heat exchanger 41a through the combustion gas introduction port 71.
[0038]
In the fuel cell of the present invention, the side wall flow passage 73 for the oxygen-containing gas from the outside is provided on the side wall of the storage container 31 on the side of the cell stack 35.
[0039]
That is, in the heat insulating material 31b of the storage container 31, as shown in FIGS. 1 and 6, an annular side wall flow passage is provided so as to surround the cell stack 35, the combustion chamber 37, and the oxygen-containing gas storage chamber 41b. 73 is formed, and two pipes 75 formed in the heat insulating material 31b are connected to the side wall flow passage 73, and the oxygen-containing gas is guided to the upper portion of the heat exchanger 41a by these pipes 75.
[0040]
The sidewall flow passage 73 does not need to be formed in an annular shape around the cell stack 35, and may be formed only in a part around the cell stack 35, for example. It is desirable to be formed all around from the point of transferring heat.
[0041]
Further, the side wall flow passage 73 may be formed only on the side of the cell stack 35, but from the point that the oxygen-containing gas in the side wall flow passage 73 is heated by the combustion gas, as shown in FIG. It is desirable that the combustion gas is extended to a position where it is led out to the heat exchanger 41a.
[0042]
An oxygen-containing gas pipe 77 for supplying oxygen-containing gas to the side wall flow passage 73 is provided in the vicinity of the fuel gas supply pipe 51.
[0043]
In the fuel cell configured as described above, an oxygen-containing gas (for example, air) from the outside is introduced into the heat exchanger 41a through the oxygen-containing gas pipe 77, and is introduced into the oxygen-containing gas storage chamber 41b. The fuel gas (for example, hydrogen) is ejected between the cells of the power generation chamber 49 through the gas supply pipe 39 and the fuel gas is supplied into the fuel gas passage 34 of the fuel cell 33 through the fuel gas supply pipe 51. In the cell 33 in FIG.
[0044]
Excess fuel gas that has not been used for power generation is jetted into the combustion chamber 37 from the upper end of the fuel gas passage 34, and surplus oxygen-containing gas that has not been used for power generation is injected into the combustion chamber 37 from the surplus gas ejection hole 57. The fuel gas is ejected and reacted with the surplus fuel gas and surplus oxygen-containing gas to generate combustion gas. The combustion gas is led to the heat exchanger 41a through the combustion gas inlet 71, and the heat exchanger 41a. It is discharged from the top of the.
[0045]
In the fuel cell of the present invention, since the side wall flow passage 73 for the oxygen-containing gas supplied from the outside is provided on the side wall of the storage container 31 on the side of the cell stack 35, the temperature in the storage container 31 becomes high. During normal operation, the oxygen-containing gas in the side wall flow passage 73 is heated, and the heated oxygen-containing gas is supplied to the heat exchanger 41a through the pipe 75, and the cell stack 35 is supplied through the oxygen-containing gas supply pipe 39. Therefore, it is possible to improve the power generation efficiency by effectively using the heat generated in the storage container 31.
[0046]
Further, when the fuel cell is started, oxygen-containing gas preheated to some extent is supplied from the outside into the side wall flow passage 73 via the oxygen-containing gas pipe 77, thereby being provided adjacent to the side wall flow passage 73. The fuel cell 33 of the existing cell stack 35 can be heated by the preheated oxygen-containing gas in the side wall flow passage 73, so that start-up can be performed quickly. In addition, when it becomes a normal driving | operation after starting, the preheating in the exterior of the storage container 31 can be stopped.
[0047]
Further, the side wall flow passage 73 extends not only to the side of the cell stack 35 but also to the side of the combustion chamber 37 and the oxygen-containing gas storage chamber 41b, that is, the position where the combustion gas is led out to the heat exchanger 41a. Therefore, the oxygen-containing gas in the side wall flow passage 73 can be heated by the combustion gas, and the heated oxygen-containing gas can be introduced into the heat exchanger 41a. An oxygen-containing gas can be supplied.
[0048]
Further, since the side wall flow passage 73 is formed in an annular shape so as to surround the cell stack 35, the combustion chamber 37, and the oxygen-containing gas storage chamber 41 b, the oxygen-containing gas and the fuel cells 33 of the cell stack 35 are connected to each other. It is possible to exchange heat evenly. Further, since the side wall flow passage 73 extends to a position where the combustion gas is led out to the heat exchanger 41a, the oxygen-containing gas in the side wall flow passage 73 can be efficiently heated with the combustion gas.
[0049]
That is, the heat transfer of the oxygen-containing gas according to the present invention will be described. For example, at startup, the oxygen-containing gas is preheated to a certain temperature, and the preheated oxygen-containing gas is passed through the side wall flow passage 73 by the oxygen-containing gas pipe 77. The fuel cell 33 inside the side wall flow passage 73 is heated.
[0050]
As a result, the temperature of the oxygen-containing gas in the side wall flow passage 73 is slightly lowered, but the side wall of the combustion chamber 37 is heated by the combustion gas, and the heated oxygen-containing gas is introduced into the heat exchanger 41a through the pipe 75. Then, it is further heated by the heat exchanger 41 a and supplied into the power generation chamber 49.
[0051]
Then, when the inside of the storage container 31 becomes high temperature and normal operation is started, preheating of the oxygen-containing gas outside is stopped, and the oxygen-containing gas at room temperature is supplied to the side wall flow passage 73, where the cell stack The heat from 35 and the heat from the combustion chamber 37 are transferred to the oxygen-containing gas in the side wall flow passage 73 to heat the oxygen-containing gas. Thereafter, the oxygen-containing gas in the side wall flow passage 73 is supplied into the power generation chamber 49 through the heat exchange unit 41. Therefore, since the supply path of the oxygen-containing gas is optimally designed, heat exchange is optimized, power generation efficiency can be improved, and quick start-up can be performed.
[0052]
Further, since the oxygen-containing gas is supplied into the side wall flow passage 73 by the oxygen-containing gas pipe 77 provided in the vicinity of the fuel gas supply pipe 51 and the burner gas supply pipe 53, the supply of gas from the outside is performed. A compact fuel cell can be provided that can be performed at one place.
[0053]
In the fuel cell of the present invention, since the cell heating burner 55 is provided in the vicinity of the fuel cell 33, when the fuel cell is started, the cell heating burner 55 is ignited by an ignition source, and the fuel cell 33 is directly connected. The fuel cell 33 can be heated up to a temperature at which power is generated, and the startup time can be greatly shortened.
[0054]
Further, even if the fuel cell 33 is directly heated by the cell heating burner 55, the heat insulating layer 56 is formed on the side of the combustion region F, so that the influence on the fuel cell 33 can be almost eliminated. it can. Further, since the oxygen side electrode 33c is formed on the outer surface of the fuel cell 33, even if the cell heating burner 55 is burned, there is no need to worry about the oxidation of the oxygen side electrode 33c.
[0055]
In addition, surplus fuel gas and oxygen-containing gas that did not contribute to power generation are introduced into the combustion chamber 37 and reacted and burned in the combustion chamber 37, and the combustion gas and external oxygen-containing gas are converted into a heat exchanger. The heat exchanger 41a allows heat exchange between the combustion gas and the oxygen-containing gas so that the oxygen-containing gas can be preheated at the time of start-up. By inserting, the oxygen-containing gas in the oxygen-containing gas supply pipe 39 can be further heated by the combustion gas. Therefore, the fuel cell 33 is indirectly heated by the heated oxygen-containing gas to substantially generate power. Can further shorten the startup time.
[0056]
Further, since the combustion chamber 37, the oxygen-containing gas storage chamber 41b, and the heat exchanger 41a are formed adjacent to each other at the upper part of the cell stack 35, the high-temperature combustion gas burned in the combustion chamber 37 is used by piping or the like. And can be directly introduced into the heat exchanger 41a, and the preheating efficiency of the oxygen-containing gas can be increased with a simple structure.
[0057]
In addition, since the combustion gas and the oxygen-containing gas can be heat-exchanged in the storage container 31, there is no need to separately provide a burner for preheating the oxygen-containing gas in the storage container 31, and the combustion gas can be reduced in size. Can be used effectively.
[0058]
Further, since the oxygen-containing gas storage chamber 41b is provided in the heat exchanger 41a, the heat exchanger 41a and the oxygen-containing gas supply pipe 39 can be connected via the oxygen-containing gas storage chamber 41b. The oxygen-containing gas from 41a can be reliably supplied into the power generation chamber 49.
[0059]
In addition, this invention is not limited to the said form, A various change is possible in the range which does not change the summary of invention. For example, in the above embodiment, the example in which the cell stack is configured using the fuel cell 33 having the elliptic cylinder shape and the plurality of fuel gas passages 34 as illustrated in FIG. 2 is described. However, the fuel cell is cylindrical, There may be one fuel gas passage, and the shape of the fuel cell is not particularly limited.
[0060]
Moreover, although the plate fin type | mold was used as the heat exchanger 41a, it is not limited to this in this invention, Of course, you may use another heat exchanger.
[0061]
Furthermore, by providing a baffle plate for circulating the oxygen-containing gas while bypassing the side wall flow passage 73, the heat exchange efficiency between the oxygen-containing gas in the side wall flow passage 73, the cell stack, and the combustion gas is further improved. it can.
[0062]
Further, by forming the side wall flow passage 73 in a spiral shape around the cell stack 35 and the combustion chamber 37, the heat exchange efficiency between the oxygen-containing gas in the side wall flow passage 73, the cell stack, and the combustion gas is further improved. it can.
[0063]
【The invention's effect】
In the fuel cell of the present invention, the side wall flow passage for the oxygen-containing gas from the outside is provided on the side wall of the storage container on the side of the cell stack, so that the oxygen-containing gas from the outside passes through the side wall flow passage. Therefore, during normal operation, the oxygen-containing gas in the side wall flow passage is heated by the heat of the cell stack, and this heated oxygen-containing gas is supplied to the cell stack to effectively use the heat generated in the storage container. It can be used to increase power generation efficiency.
[0064]
On the other hand, when starting the fuel cell, by supplying oxygen-containing gas preheated to some extent into the side wall flow passage, the fuel cell of the cell stack provided on the side of the side wall flow passage can be heated and the side wall circulation The preheated oxygen-containing gas of the road is introduced into the fuel cell of the cell stack via, for example, an oxygen-containing gas supply pipe, and the fuel cell can be heated by the oxygen-containing gas, so that the start-up can be performed quickly. Can do.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a fuel cell of the present invention.
2 is a cross-sectional view showing the cell stack of FIG. 1. FIG.
FIG. 3 is a cross-sectional view showing a state in which a cell heating burner is provided in the vicinity of a fuel cell.
4A and 4B are views for explaining the concept of the heat exchanger of FIG. 1, wherein FIG. 4A is a perspective view of the heat exchanger, and FIG. 4B is a corrugated plate for forming a passage for oxygen-containing gas. A perspective view and (c) are perspective views showing a corrugated plate for forming a passage of combustion gas.
FIG. 5 is a perspective view for explaining a heat exchanging portion of the present invention.
FIG. 6 is a cross-sectional view of the cell stack and its vicinity.
[Explanation of symbols]
31 ... Storage container 33 ... Fuel cell 35 ... Cell stack 37 ... Combustion chamber 39 ... Oxygen-containing gas supply pipe 41 ... Heat exchange section 51 ... Fuel gas supply pipe 55 ... Cell heating burner 73 ... Side wall flow passage 77 ... Oxygen-containing gas pipe

Claims (2)

In a fuel cell configured to store a cell stack in which a plurality of fuel cells are gathered in a storage container, and to generate electric power by supplying an oxygen-containing gas and a fuel gas to the cell stack, the cell stack includes the cell stack. A combustion chamber provided adjacent to the surplus oxygen-containing gas and fuel gas derived from the cell stack and generating combustion gas; and provided adjacent to the combustion chamber; A heat exchanging part that exchanges heat by introducing combustion gas and oxygen-containing gas; and an oxygen-containing gas supply pipe that passes through the combustion chamber and supplies the oxygen-containing gas heated in the heat exchanging part to the cell stack. together formed by providing, on the inner side of the side wall of the container at a side of the cell stack and the combustion chamber, the side wall passage of the oxygen-containing gas supplied from the outside is provided, acid of the side wall flow passage Fuel cell, wherein a containing gas is supplied to the cell stack via the heat exchanger. At startup, the fuel cell according to claim 1, wherein the preheated oxygen-containing gas is supplied to the side wall passage.

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