JP4826992B2 - Fuel cell plate, fuel cell cylindrical cell, fuel cell stack, fuel cell module, fuel cell unit and fuel cell system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid oxide fuel cell (SOFC) that uses a solid oxide electrolyte to obtain electric energy by an electrochemical reaction, and more specifically, a solid oxide electrolyte layer is sandwiched between electrodes. The present invention relates to a fuel cell plate having a battery element, a fuel cell columnar cell, a fuel cell stack, a fuel cell module, a fuel cell unit, and a fuel cell system.
[0002]
[Prior art]
In recent years, fuel cells have attracted attention as a clean energy source capable of high energy conversion and friendly to the global environment.
As a solid oxide fuel cell (hereinafter abbreviated as “SOFC”), a solid electrolyte having ionic conductivity such as oxygen ions and protons is sandwiched between a porous oxidation electrode and a reduction electrode. There has been proposed a battery that generates an electromotive force by supplying an oxidizing gas to the reducing electrode, supplying a reducing gas to the reducing electrode side, and electrochemically reacting these gases via a solid electrolyte.
[0003]
In addition, as another SOFC, J.A. Electrochem. Soc. , 147, 1338 (2000) and Electrochemical and Solid-State Letters. , 2, 317 (1999) propose a mixed gas introduction type SOFC that generates power by supplying a mixed gas obtained by mixing air (oxidizing gas) and fuel (hydrocarbon gas), and a stack using the same. Has been.
[0004]
Such a mixed gas introduction type SOFC does not separate the air flow path and the fuel flow path, unlike the SOFC of the type that distinguishes the flow gas for each electrode, so that no gas seal is required, and the structure is greatly simplified. Yes. In other words, downsizing and cost reduction are possible.
Further, since the air electrode side and the fuel electrode side have the same gas atmosphere, the electrolyte does not need to have gas separation properties, that is, even if the gas is permeable with a porous electrolyte.
In addition, the mixed gas introduction type SOFC can use the same material as the SOFC of the type that distinguishes the flowing gas for each electrode for each element (air electrode, fuel electrode, and solid electrolyte) of the single cell portion, but air as a fuel. Hydrogen that cannot be mixed cannot be used, and the fuel used is limited to hydrocarbons.
[0005]
[Problems to be solved by the invention]
However, the mixed gas introduction type SOFC has a slightly lower power generation output than the SOFC of the type that distinguishes the distribution gas for each electrode, and the fuel use efficiency (the energy converted into electric power among the energy of the supplied fuel). Ratio) decreases (fuel efficiency is poor).
Moreover, since the mixed gas introduction type SOFC has a common electrolyte, there is a possibility that the power generation output is reduced due to a short circuit.
[0006]
The present invention has been made in view of the above-described problems of the prior art. The object of the present invention is to provide a fuel cell plate having a high power output and a high fuel utilization rate, and a fuel cell column type. The object is to provide a cell, a fuel cell stack, a fuel cell module, a fuel cell unit, and a fuel cell system.
[0007]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have found that the above problems can be solved by installing independent battery elements in a predetermined arrangement on the support base, and to complete the present invention. It came.
[0008]
The cell plate for a fuel cell according to the present invention comprises two or more battery element portions in which a solid oxide electrolyte layer is sandwiched between a fuel electrode layer and an air electrode layer, and the solid oxide electrolyte layers of these battery element portions are mutually connected. The fuel electrode layer and the air electrode layer are mixed and exposed on the front and back surfaces of the support base made of an insulator, which are electrically independent, and a mixed gas containing oxygen and hydrocarbons is formed on the support base. Electric power is generated by being supplied to the front and back surfaces.
[0009]
Moreover, the suitable form of the cell board for fuel cells which concerns on this invention has arrange | positioned the said battery element part so that the said fuel electrode layer and air electrode layer may be exposed in a checkered pattern form on the cell board surface.
[0010]
Furthermore, in another preferred embodiment of the cell plate for a fuel cell according to the present invention, a plurality of battery element portions are sandwiched between a common fuel electrode layer and / or air electrode layer.
[0011]
Furthermore, the cylindrical cell for a fuel cell according to the present invention is formed by using the above-described cell plate for a fuel cell, and the cell plate for a fuel cell is wound in a cylindrical shape.
[0012]
The fuel cell stack according to the present invention is formed by using the fuel cell plate, and the fuel cell plate is laminated.
[0013]
Furthermore, the fuel cell module according to the present invention comprises a fuel cell columnar cell, and the fuel cell columnar cell is provided in a cylindrical tube.
[0014]
Furthermore, a fuel cell power generation unit according to the present invention is formed using the fuel cell stack or the fuel cell module, and a mixed gas containing oxygen and hydrocarbon is mixed between the cell plate and the cell plate. It is made to distribute | circulate in the clearance gap between cylindrical cells.
[0015]
Furthermore, a fuel cell system according to the present invention comprises the above fuel cell power generation unit, and comprises a gas mixer, an A / F sensor, a humidifier, and a burner that generate a mixed gas to be supplied to the fuel cell. And a gas flow control means for controlling them, wherein the gas mixer mixes air and fuel at a predetermined mixing ratio, and the A / F sensor has a concentration of unreacted gas after flowing through the fuel cell power generation unit. From this result, when humidification is necessary, humidify by the humidifier, and when the unreacted gas exceeds a certain value, it is recovered and reused in the gas mixer, and the unreacted gas is constant. When it is less than the value, the burner burns.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the cell plate for a solid oxide fuel cell of the present invention will be described in detail. In the present specification, “%” indicates a mass percentage unless otherwise specified.
For convenience of explanation, one surface of the substrate or the battery element portion is described as “front surface”, and the other surface is described as “rear surface”. However, these are equivalent elements, and the configurations replaced with each other are also the present invention. It goes without saying that it is included in the range.
[0017]
As described above, the cell plate for a solid oxide fuel cell according to the present invention is formed by supporting two or more battery element portions each having a solid electrolyte layer sandwiched between a fuel electrode layer and an air electrode layer on a support base. In other words, it has a battery element portion in which a fuel electrode layer (air electrode layer), a solid electrolyte layer, and an air electrode layer (fuel electrode layer) are laminated in this order. Typically, a cell plate as shown in FIG. 1 can be illustrated.
[0018]
Here, the battery element portion is supported so that at least one fuel electrode layer and air electrode layer are exposed on the front surface and the back surface of the support base. Accordingly, since both the fuel electrode and the air electrode of the single cell element face one side of the cell plate, a mixed gas can be supplied to the battery element unit to generate electric power. In addition, a gas seal is not required, and manufacturing of a stack using the cell plate is easy. As the mixed gas, for example, oxygen as an oxidizing gas and hydrocarbon such as methane as a fuel gas can be used. As the fuel electrode layer, nickel (Ni), copper (Cu), and their cermets can be used. As the air electrode layer, LSC (lanthanum-strontium-cobalt composite oxide), LSM, silver (Ag), platinum (Pt), or the like can be used.
Moreover, the said solid electrolyte layer is supported so that it may become electrically independent for every battery element part. This is effective because a short circuit is prevented. As the solid electrolyte layer, for example, a composite oxide (such as lanthanum gallate) mainly containing YSZ or LaGaO ₃ can be used, but is not limited thereto. In addition, when the solid electrolyte layer in the adjacent battery element part is made common, a short circuit will generate | occur | produce and a power generation output will fall.
[0019]
Moreover, it is preferable that the electric element portions are connected in series using a wiring material. This is effective because the voltage is increased and the power generation output is improved. As a wiring material, Pt, Ag, SUS, lanthanum chromite, or the like can be used. Specifically, a cell plate as shown in FIG. 3 can be illustrated.
[0020]
Furthermore, it is preferable that the battery element part is disposed on the surface of the cell plate so that the fuel electrode layer and the air electrode layer are exposed in a checkered pattern. In this case, it becomes easy to connect in series. That is, wiring of the wiring material is facilitated. Needless to say, wiring on the back surface of the cell plate is similarly easy. Moreover, even if the arrangement of the battery element portion is other than the checkered pattern, it can be appropriately adopted if it is easy to wire in series.
[0021]
Furthermore, the support substrate is preferably an insulator from the viewpoint of ensuring insulation between the air electrode and the fuel electrode of the single cell element. For example, a plate made of alumina or SUS or a porous plate can be used.
[0022]
Moreover, it is preferable that a plurality of adjacent battery element portions are sandwiched between a common fuel electrode layer and / or air electrode layer. In this case, the manufacturing becomes easier, which is effective. For example, as shown in FIG. 5, a comb-shaped cell plate formed by sandwiching battery element portions arranged in a direction perpendicular to the gas flow direction with a common electrode can be exemplified.
[0023]
Further, the support substrate in the cell plate can be corrugated. Thus, the surface area can be increased (volume efficiency can be improved), and the impact resistance can be improved. For example, a wave-shaped cell plate as shown in FIG. In addition, when processing into shapes other than planes, such as this wave shape, it is good to give a softness | flexibility to a cell board using the metal plate etc. which carried out insulation coating. Further, the peaks and valleys (wave corners) of the waveform may be sharp or rounded.
[0024]
In the present invention, a cylindrical cell is obtained by winding the above-described fuel cell plate in a cylindrical shape. In this case, impact resistance is improved and rapid temperature rise is possible. In addition, when winding a cell board in column shape, as shown in FIG. 7, it is good to provide the space holding material etc. and to ensure the distribution | circulation of gas. In addition, a cylindrical cell obtained by winding the above-described wave-shaped cell plate or comb-shaped cell plate is also effective.
[0025]
Next, the solid oxide fuel cell stack and module of the present invention will be described in detail.
Such a fuel cell stack is formed by using the above-described cell plates, and is formed by laminating the fuel cell cell plates. Since the cell plates according to the present invention are stacked, high output is possible. For example, as shown in FIG. 9, by stacking cell plates provided with space protection materials on both ends of the cell plate, a fuel cell stack having a gas flow path is obtained. On the other hand, the fuel cell module is formed by electrically connecting a plurality of cylindrical tubes in which the aforementioned columnar cells are inscribed. At this time, it is preferable to use a cylindrical tube made of a material such as SUS or alumina having both ends opened. Further, this module can easily replace only the stack that has failed at the time of failure as shown in FIG.
[0026]
In these stacks and modules, it is preferable that the fuel electrode layer and the air electrode layer have an arrangement density with respect to the gas flow direction. As a result, the fuel utilization rate can be improved. Here, the “arrangement density” means that the single cell element with the air electrode exposed on one surface of the cell plate and the single cell element with the fuel electrode exposed are evenly arranged in the cell plate. That is not done. The arrangement density can be formed by the arrangement of the electrodes, the shape of the gas flow path, and the like. Typically, as shown in FIG. 4, the upstream side of the gas flow path can be the main air electrode, and the downstream side can be the main fuel electrode.
[0027]
Next, the solid oxide fuel cell power generation unit according to the present invention uses the stack and the module, and a mixed gas containing oxygen and hydrocarbon is circulated in the gap between the cell plates or the gap between the cylindrical cells. . For example, as shown in FIG. 10, there can be mentioned a μ cell unit that uses a Si substrate and has a high output by ensuring a gap for flowing gas with a space holding material.
[0028]
Next, the solid oxide fuel cell system of the present invention is formed using the above-described solid oxide fuel cell power generation unit. Moreover, it has a gas mixer, an A / F sensor, a humidifier, and a burner, and gas distribution control means (computer etc.) which control these. The gas mixer mixes air and fuel at a predetermined mixing ratio, and the A / F sensor detects the concentration of unreacted gas after the fuel cell power generation unit is distributed. From this result, when humidification is required, humidify by the humidifier, and when the unreacted gas is above a certain value, it is recovered and reused in the gas mixer, and the unreacted gas is less than a certain value. When it burns with the above burner. Specifically, it can be used as a vehicle power generation system in which SOFC is a power source as shown in FIG. The above “when humidification is necessary” refers to the time when the output is reduced due to carbon deposition or the like on the fuel electrode, and the above “constant value” refers to the unreacted gas concentration after distribution of the power generation unit. It means 30%.
[0029]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.
[0030]
<Cell plate for solid oxide fuel cell>
Example 1
As shown in FIG. 2, a through hole having a length of 10 mm and a width of 10 mm is formed on an alumina substrate having a thickness of 500 μm and 5 cm × 5 cm, a back plate is applied to the back surface, and then a checkered pattern is formed on the through hole on the front side. An electrolyte green sheet of La _0.9 Sr _0.1 Ga _0.8 Mg _0.2 O ₃ (lanthanum gallate) was inserted into this. A fuel electrode paste (Ni-lanthanum gallate cermet) was applied on the electrolyte by a printing method, and calcined to form a fuel electrode.
Similarly, an air electrode (La _0.7 Sr _0.3 CoO ₃ (LSC)) was formed on the back surface side, followed by main firing.
As shown in FIG. 3, a wiring material was connected between the electrodes to obtain a solid oxide fuel cell plate for this example.
[0031]
(Example 2)
As shown in FIG. 4, the same operation as in Example 1 was repeated except that the gradient arrangement density was provided with respect to the gas flow direction, to obtain a cell plate for a solid oxide fuel cell of this example.
[0032]
(Example 3)
As shown in FIG. 5, the same operation as in Example 1 was repeated except that a pattern in which five electrolytes were sandwiched between two electrodes was obtained, thereby obtaining a cell plate for a solid oxide fuel cell of this example.
[0033]
Example 4
As shown in FIG. 6, the same operation as in Example 1 was repeated except that the cell plate was processed into a corrugated shape after forming the electrode, thereby obtaining a cell plate for a solid oxide fuel cell of this example.
[0034]
<Cylindrical cell for solid oxide fuel cell>
(Example 5)
As shown in FIG. 7, the same operation as in Example 1 was repeated except that an alumina film was formed on the SUS surface for insulation, a space holding material was placed on the surface of the cell plate after electrode formation, and this was wound up. Thus, a cylindrical cell for a solid oxide fuel cell of this example was obtained. In addition, the module for solid oxide fuel cells as shown in FIG. 8 is obtained by inserting this cylindrical cell into a cylindrical open tube at both ends.
[0035]
<Stack for solid oxide fuel cell>
(Example 6)
As shown in FIG. 9, a cell plate is formed by repeating the same operation as in Example 1 except that a space holding material is provided at both ends of the cell plate, and this cell plate is stacked to form a solid oxide fuel cell of this example. Got the stack for.
[0036]
<Solid electrolyte fuel cell power generation unit>
(Example 7)
As shown in FIG. 10, the same operation as in Example 1 was repeated except that a Si substrate was used as the support base and a space holding material was provided on a cell plate having μ cells (2 mm in length and 2 mm in width). The cell plate was stacked and enclosed in a container to obtain a solid oxide fuel cell power generation unit of this example.
[0037]
<Solid electrolyte fuel cell system>
(Example 8)
As shown in FIG. 11, a gas mixer, a humidifier, an A / F sensor, and a burner were connected to the solid oxide fuel cell power generation unit, and a fuel cell system that could be controlled by gas flow control means was obtained.
In this fuel cell system, fuel was sent from a fuel cylinder and air was blown from outside air with a blower to the gas mixer and mixed. The mixing ratio of air and fuel was detected and controlled by an A / F sensor downstream of the gas mixer. When humidification was required for the mixed gas, the branch valve was switched so that the mixed gas circulated through the humidifier.
Furthermore, the unreacted fuel gas concentration in the fuel cell exhaust was detected by an A / F sensor downstream of the fuel cell. At this time, when the unreacted fuel gas was above a certain value (30%), it was recovered into the gas mixer and reused. On the other hand, when it was less than 30%, it was sent to the burner for combustion treatment.
In addition, when the system was started, fuel and air were sent to a burner for combustion, and the fuel cell was heated.
[0038]
The solid oxide fuel cell plate, stack, module, power generation unit, and solid oxide fuel cell system using the same according to the present invention have a good fuel utilization rate of 50 to 80% and an improved power generation output. To do. Moreover, since the electrolyte is independent, a short circuit is prevented. Further, since the gas flow paths are not separated as in the prior art, a gas seal is not required, the structure is greatly simplified, and the size and cost can be reduced. Furthermore, at the time of start-up, since the hydrocarbons are directly combusted on the electrode surface, rapid temperature increase is possible. In addition, since the same gas flows through the air electrode side and the fuel electrode side, the electrolyte does not need to have gas separation properties.
[0039]
As mentioned above, although this invention was demonstrated in detail by the Example, this invention is not limited to these, A various deformation | transformation is possible within the range of the summary of this invention.
For example, the shape of each battery element part such as a cell plate, the arrangement density, the flow rate of the mixed gas, and the like can be arbitrarily selected, and power can be generated according to the target output. Moreover, a fuel cell power generation unit can be produced by using the cell plate and the fuel cell module together.
[0040]
【The invention's effect】
According to the present invention, the following effects can be obtained.
-Two or more battery element parts, these solid oxide electrolyte layers are electrically independent from each other, and a fuel electrode layer and an air electrode layer are mixed on the front and back surfaces of a support base made of an insulator, respectively. Since it is exposed, both the fuel electrode and the air electrode of the battery element part are exposed on one side of the support base, so that it is possible to generate a power by supplying a mixed gas to the battery element part and generating power. The fuel utilization rate can be improved.
-In addition, no gas seal is required, making it easy to manufacture stacks using this cell plate.
Furthermore, since the solid oxide electrolyte layer is supported so as to be electrically independent for each battery element portion, it is effective in preventing a short circuit.
[Brief description of the drawings]
1A and 1B are a plan view and a cross-sectional view showing an example of a solid oxide fuel cell plate according to the present invention.
FIG. 2 is a schematic view showing an example of a method for producing a solid oxide fuel cell plate.
3 is a plan view and a cross-sectional view showing a cell plate for a solid oxide fuel cell of Example 1. FIG.
4 is a plan view showing a cell plate for a solid oxide fuel cell of Example 2. FIG.
5 is a plan view showing a cell plate for a solid oxide fuel cell of Example 3. FIG.
6 is a perspective view showing a cell plate for a solid oxide fuel cell according to Example 4. FIG.
7 is a perspective view showing a cylindrical cell for a solid oxide fuel cell of Example 5. FIG.
FIG. 8 is a perspective view showing a state in which the cylindrical cell of Example 5 is modularized.
9 is a perspective view showing a solid oxide fuel cell stack of Example 6. FIG.
10 is a cross-sectional view showing a solid oxide fuel cell power generation unit of Example 7. FIG.
11 is a schematic view showing a solid oxide fuel cell system of Example 8. FIG.

Claims (11)

Two or more of the battery element portion which sandwiches a solid oxide electrolyte layer with a fuel electrode layer and the air electrode layer, electrically made independent solid oxide electrolyte layer of the battery element portions mutually, and an insulator A fuel electrode layer and an air electrode layer are mixed and exposed on the front and back surfaces of the support substrate,
A cell plate for a fuel cell, wherein a mixed gas containing oxygen and hydrocarbons is supplied to the front and back surfaces of the support base to generate electric power .   The cell plate for a fuel cell according to claim 1, wherein the battery element portions are connected in series. The cell plate for a fuel cell according to claim 1 or 2, wherein the battery element portion is disposed on the surface of the support base so that the fuel electrode layer and the air electrode layer are exposed in a checkered pattern.   The cell board for a fuel cell according to any one of claims 1 to 3, wherein the support base is insulative.   The cell plate for a fuel cell according to any one of claims 1 to 4, wherein a plurality of battery element parts are sandwiched between a common fuel electrode layer and / or an air electrode layer.   The cell board for a fuel cell according to any one of claims 1 to 5, wherein the support base has a wave shape. A fuel cell columnar cell comprising the fuel cell plate according to any one of claims 1 to 6,
A fuel cell cylindrical cell, wherein the fuel cell plate is wound in a cylindrical shape. A fuel cell stack comprising the fuel cell plate according to any one of claims 1 to 6,
A fuel cell stack comprising the fuel cell plate laminated. A fuel cell module comprising the cylindrical cell for a fuel cell according to claim 7,
A fuel cell module comprising the cylindrical cell for a fuel cell provided in a cylindrical tube . A fuel cell power generation unit using the fuel cell module according to claim 9,
The fuel cell power generation unit, wherein the mixed gas is circulated in a gap between the cell plates or the gap between the cylindrical cells . A fuel cell system using the fuel cell power generation unit according to claim 10,
A gas mixer for generating a mixed gas to be supplied to the fuel cell, an A / F sensor, a humidifier and a burner, and a gas flow control means for controlling them,
The gas mixer mixes air and fuel at a predetermined mixing ratio, and the A / F sensor detects the concentration of unreacted gas after distribution through the fuel cell power generation unit. When the unreacted gas is above a certain value, it is recovered by the gas mixer and reused, and when the unreacted gas is less than a certain value, it is burned by the burner. Fuel cell system .

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