JP2009093835A - Fuel-reformed type fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel-reformed type fuel cell that is less apt to be cooled after a cell stack reaches a given temperature, and has appropriate internal temperature distribution and high power generating efficiency. <P>SOLUTION: A pair of combustion layers 46a, b having fuel gas react with oxidant gas to be combusted and collecting electricity generated at a power-generating stack 10 is arranged on a top and bottom faces in the laminating direction of power generating cells 20 of the power-generating stack 10 having a plurality of flat power generating cells 20; further, an oxidant heat-exchange layer 44, for exchanging heat with oxidant gas supplied to the power generating stack 10, is arranged on a top face of the combustion layer 46a; and a fuel gas reforming layer 42 for reforming fuel gas into hydrogen is arranged on an underside of the combustion layer 46b, both of them 44, 42 housed in a heat-insulating vessel 50. Here, they are to be housed so that a projected image of the power-generating stack 10 on an auxiliary layer 40 in a laminating direction of the power generating cells 20 is contained in one plane on the auxiliary layer 40. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel reforming fuel cell with high power generation efficiency.

A conventional fuel reforming fuel cell has a configuration in which a power generation stack in which flat power generation cells are stacked is sandwiched between auxiliary layers such as a current collecting layer, a heat exchange layer, or a reforming layer (for example, Patent Document 1). reference). In such a flat plate fuel reforming type fuel cell, it is necessary to keep the power generation stack at a predetermined temperature during power generation. Therefore, after the power generation stack reaches a predetermined temperature, the power generation stack needs to have a structure that is difficult to be cooled.
JP-A-7-176315

  However, in the above fuel reforming fuel cell, the dimensions between the flat power generation stack and the auxiliary layer and the positional relationship when they are stacked are not clear, that is, the size of the power generation stack and the auxiliary layer, or the stacking The deviation between the stacking direction and the vertical direction is not clearly defined. Therefore, if the projection surface with respect to the auxiliary layer of the flat power generation stack protrudes from the auxiliary layer, there is a high possibility that the heat that warms the flat power generation stack will be released to the outside. That is, there is a problem that the power generation stack is likely to be cooled after reaching a predetermined temperature.

  In addition, in the auxiliary layer, thermal absorption and heat generation are performed in order to perform heat exchange and combustion of fuel gas and oxidant gas. Therefore, by arranging the auxiliary layers in an appropriate stacking order, the heat distribution inside the fuel reforming fuel cell can be made appropriate. However, in the conventional fuel reforming fuel cell, it was not possible to improve the power distribution efficiency by improving the heat distribution inside the fuel reforming fuel cell by making the auxiliary layer stacking order appropriate. .

  The present invention has been made in view of these problems, and provides a fuel reforming fuel cell that is difficult to be cooled after the battery stack reaches a predetermined temperature, has an appropriate internal temperature distribution, and has high power generation efficiency. With the goal.

  The fuel reforming fuel cell according to claim 1, which has been made to solve such a problem (1: In this column, in order to facilitate understanding of the invention, the “best mode for carrying out the invention” is included as necessary. The reference numeral used in the column “No.” is used, but it does not mean that the scope of claims is limited by this reference.) Is a power generation stack (10) in which a plurality of flat-plate power generation cells (20) are stacked. ) And a fuel gas reforming layer (42) for reforming the fuel gas into hydrogen, an oxidant heat exchange layer (44) for heat exchange of the oxidant gas supplied to the power generation stack (10), or , Comprising at least one of the combustion layers (46) for causing the fuel gas to react with the oxidant gas and burning it, on the upper and lower surfaces in the stacking direction of the power generation cells (20) of the power generation stack (10) Placed flat plate An auxiliary layer (40), and a projection image of the power generation cell (20) in the stacking direction with respect to the auxiliary layer (40) of the power generation stack (10) is in one plane on the flat auxiliary layer (40) It fits in.

  Such a fuel reforming fuel cell (1) has auxiliary layers (40) on the upper and lower surfaces in the stacking direction of the power generation cells (20) of the power generation stack (10). That is, the power generation stack (10) is sandwiched between the auxiliary layers (40). When the power generation stack (10) is sandwiched between the auxiliary layers (40), the projection image in the stacking direction of the power generation cells (20) with respect to the auxiliary layer (40) of the flat plate-type power generation stack (10) is a flat auxiliary. The power generation stack (10) and the auxiliary layer (40) are arranged so as to fit in one plane on the layer (40).

  As described above, the projection image in the stacking direction of the power generation cells (20) of the power generation stack (10) is within one plane on the flat auxiliary layer (40), that is, the flat power generation stack (10 ) Sandwiches the power generation stack (10) so that the projection surface of the power generation stack (10) does not protrude from the auxiliary layer (40), so that heat generated by the power generation stack (10) is blocked by the auxiliary layer (40). It is done.

  In other words, since at least two surfaces of the flat power generation stack (10) are sandwiched from the flat auxiliary layer (40), the heat dissipation from the other surface of the power generation stack (10) is radiated from the auxiliary layer (40). It will be trapped in between. That is, since the amount of heat escaping from the power generation stack (10) to the outside can be reduced, the power generation stack (10) can be prevented from being cooled.

  Of the auxiliary layer (40), the fuel gas reforming layer (42) absorbs the heat of the fuel gas, the oxidant heat exchange layer (44) absorbs the heat of the oxidant gas, and the combustion layer (46). Heats up. Therefore, the amount and distribution of heat absorption and heating can be controlled by selecting the fuel gas reforming layer (42), the oxidant exchange layer, and the combustion layer (46) or a combination thereof.

  For example, the combustion layer (46) is disposed at both ends of the power generation stack (10), and the fuel gas reforming layer (42) is disposed outside the combustion layer (46) disposed at one end of the power generation stack (10). To place. Further, if the oxidant heat exchange layer (44) is disposed outside the combustion layer (46) disposed at the other end of the power generation stack (10), the heat generated in the combustion layer (46) is converted into fuel gas. Since it can be absorbed by the reforming layer (42) and the oxidant heat exchange layer (44), the heat distribution inside the fuel reforming fuel cell (1) can be made uniform.

Thus, since the heat distribution inside the fuel reforming fuel cell (1) can be controlled, the fuel reforming fuel cell (1) with high power generation efficiency can be obtained.
Furthermore, since the flat power generation stack (10) and the auxiliary layer (40) can be integrally formed, the shape of the fuel reforming fuel cell (1) can be made compact.

Further, as described in claim 2, the auxiliary layer (40) may include a pair of current collecting layers for collecting electricity generated by the power generation stack (10).
By providing the auxiliary layer (40) with a current collecting function in this way, the electricity generated by the fuel reforming fuel cell (1) can be easily taken out.

  Furthermore, as described in claim 3, when the power generation stack (10) and the auxiliary layer (40) are housed in a container (50) having a heat insulating function, the power generation stack (10) is further provided by the heat insulating function of the container (50). Is easily maintained at a predetermined temperature.

  The fuel reforming fuel cell (1) is compact when the power generation cell (20) is made of a solid oxide or a solid polymer as described in claim 5 as described in claim 4. A fuel reforming fuel cell (1) can be obtained.

Embodiments to which the present invention is applied will be described below with reference to the drawings. The embodiment of the present invention is not limited to the following embodiment, and can take various forms as long as they belong to the technical scope of the present invention.
[First Embodiment]
The configuration of the flat plate fuel reforming fuel cell 1 will be described with reference to FIGS. FIG. 1 is a cross-sectional view for illustrating a schematic structure of a flat plate fuel reforming fuel cell 1, and FIG. 2 is a cross-sectional view illustrating a schematic configuration of a power generation cell 20. FIG. 3 is an explanatory view showing a state in which the power generation cell 20 is disassembled.

  As shown in FIG. 1, the flat plate fuel reforming fuel cell 1 includes a power generation stack 10, an auxiliary layer 40, a heat insulating container 50, a burner 52, a fuel gas supply path 60, an oxidant gas supply path 70, an exhaust gas path 80, and A current line 90 is provided.

The power generation stack 10 is formed by stacking a plurality of flat plate-shaped power generation cells 20 made of a solid oxide, and the power generation cells 20 are electrically connected in series.
The power generation cell 20 is a solid electrolyte fuel cell, and is a so-called fuel electrode support membrane type fuel cell as shown in FIG. A fuel electrode (anode) 22 is disposed on the fuel gas supply path 60 side, and a thin film solid electrolyte body 24 is formed on the upper surface of the fuel electrode 22 in FIG. An air electrode (cathode) 26 is formed on the surface of the solid electrolyte body 24 on the oxidant gas supply path 70 side.

  As the solid electrolyte body 24, materials such as YSZ, ScSZ, SDC, GDC, and perovskite oxide can be used. The fuel electrode 22 can be made of cermet of Ni and Ni and ceramic, and the air electrode 26 can be made of perovskite oxide, various noble metals and cermets of noble metal and ceramic.

  In order to ensure the electrical connection between the air electrode 26 and the upper metal interconnector (a plate for ensuring electrical conduction between the power generation cells 20 and preventing gas mixing between the cathode and the anode) 28, For example, a current collector 35 made of LSCF (lanthanum strontium cobalt iron), LSM (lanthanum strontium manganate), or the like similar to the air electrode 26 is disposed.

Hereinafter, the fuel electrode 22, the solid electrolyte body 24, and the air electrode 26 that actually generate power are referred to as a cell body 27.
More specifically, as shown in an exploded view in FIG. 3, the power generation cell 20 includes a pair of upper and lower metal interconnectors 28 and 30, a metal air electrode frame 32 on the oxidant gas supply path 70 side, An insulating frame 34 made of ceramic, a metal separator 36 that is arranged by joining the cell main body 27 and blocks the gas flow path, and a metal fuel electrode frame 38 on the fuel gas supply path 60 side are provided. .

  In addition, since the interconnector between the stacked power generation cells 20 is shared, only one interconnector is disposed between the power generation cells 20 except for the power generation cells 20 at both upper and lower ends.

  The auxiliary layer 40 is not a layer having one function, but includes at least one of a fuel gas reforming layer 42, an oxidant heat exchange layer 44, and a combustion layer 46. In the first embodiment, the fuel gas reforming layer 42, the oxidant heat exchange layer 44, and the two combustion layers 46 are formed. In addition, when it is necessary to distinguish the two combustion layers 46, they are called the combustion layer 46a and the combustion layer 46b.

  The fuel gas reforming layer 42 is an auxiliary layer for reforming the fuel gas into hydrogen, and the reformed hydrogen gas is supplied to the power generation stack 10 and used for power generation. As the reforming method, there are a steam reforming method, a partial oxidation reforming method, etc., but any one method may be used, or two methods may be used in combination.

  The combustion layer 46 is filled with a catalytic combustion catalyst, and is an auxiliary layer that burns residual gas (mainly methane and carbon monoxide) that has not been used in power generation by the catalyst. By burning the residual gas, We are trying to make the exhaust gas harmless.

  The oxidant heat exchange layer 44 is an auxiliary layer for exchanging heat of the oxidant gas supplied to the power generation stack 10. The oxidant gas supplied from the outside is preheated and sent to the power generation stack 10. Used for power generation.

  The auxiliary layer 40 includes a current collecting layer 48 having conductivity for collecting electricity generated by the power generation stack 10. The current collecting layer 48 is used as a single layer of the current collecting layer 48, and is formed integrally with any one of the fuel gas reforming layer 42, the combustion layer 46, and the oxidant heat exchange layer 44. There is. In the first embodiment, the combustion layers 46a and 46b are integrally formed.

These auxiliary layers 40 are formed in a flat plate shape, and are arranged so as to sandwich the power generation stack 10 from above and below in FIG.
There are no restrictions on the arrangement of these auxiliary layers 40. However, since the auxiliary layer 40, particularly the current collecting layer 48, always needs to have a configuration in which the flat power generation stack 10 is sandwiched, at least two are required. That is, two (a pair) of current collecting layers 48 are required, but at least one of the other fuel gas reforming layer 42, combustion layer 46, and oxidant heat exchange layer 44 may be used.

  The heat insulating container 50 is a container that forms the appearance of the flat plate fuel reforming fuel cell 1 and houses the components of the flat plate fuel reforming fuel cell 1 such as the power generation stack 10, the auxiliary layer 40, and the burner 52 inside. is doing. Moreover, the heat insulation container 50 has heat insulation so that the heat generated in the power generation stack 10 and the auxiliary layer 40 does not escape to the outside.

  The burner 52 is a burner 52 for heating the solid oxide forming the power generation cell 20 to a temperature necessary for performing desired power generation, and is stored in the heat insulating container 50. Further, the burner 52 is provided with a burner gas supply path 54 for supplying gas burned by the burner from the outside.

  As described above, the heat generation of the burner 52 can be minimized by housing the burner 52 for supplying heat necessary for power generation of the flat plate fuel reforming fuel cell 1 in the heat insulating container 50. The thermal reforming of the fuel reforming fuel cell 1 is facilitated, and the start-up time until the power generation stack 10 reaches a temperature necessary for starting power generation can be shortened.

  The fuel gas supply path 60 is a path for supplying fuel gas supplied from the outside to each power generation cell 20. As the fuel gas supplied through the fuel gas supply path 60, hydrocarbon gases such as city gas and natural gas are mainly used. By using these hydrocarbon gases, costs can be reduced in that existing gas infrastructure can be used effectively.

  The fuel gas supplied from the outside to the fuel gas supply path 60 passes through the vaporizer 62 and is sent to the fuel gas reforming layer 42. Although not shown, the vaporizer 62 is connected to a reforming water supply line to which water for steam reforming is sent, and the water sent through the reforming water supply line is steamed by the vaporizer 62.

  The fuel gas reformed in the fuel gas reforming layer 42 flows through the fuel gas reforming layer 42 and then flows into each power generation cell 20. The fuel gas after passing through each power generation cell 20 flows into the combustion layer 46b. In this way, the path through which the fuel gas supplied from the outside passes becomes the fuel gas supply path 60.

  The oxidant gas supply path 70 is a path for supplying oxidant gas supplied from the outside to each power generation cell 20. Air can be used as the oxidant gas supplied through the oxidant gas supply path 70. By using air as the oxidant gas, power generation costs can be suppressed.

  The oxidant gas is supplied to the oxidant gas supply path 70 from the outside, and then sent to the oxidant heat exchange layer 44 and heated in the oxidant heat exchange layer 44. The heated oxidant gas flows through the oxidant heat exchange layer 44 and then flows into each power generation cell 20. The oxidant gas after passing through each power generation cell 20 flows into the combustion layer 46. Thus, the path through which the oxidant gas supplied from the outside passes becomes the oxidant gas supply path 70.

  The exhaust gas path 80 is a path for discharging the fuel gas and the oxidant gas discharged through each power generation cell 20 to the outside of the power generation cell 20, and connects the flat plate-shaped power generation stack 10 to the outside with a manifold shape. Connected.

  The fuel gas and the oxidant gas input through the fuel gas supply path 60 and the oxidant gas supply path 70 pass through each power generation cell 20 and then are sent to the combustion layers 46a and 46b. The unburned gas after passing through each power generation cell 20 is made harmless by being burned in the combustion layers 46a and 46b. The exhaust gas rendered harmless in the combustion layers 46a and 46b is discharged to the outside.

The current line 90 is an electric wire for taking out the current generated from the power generation stack 10 to the outside.
(Features of the flat plate fuel reforming fuel cell 1)
Next, characteristics of the flat plate fuel reforming fuel cell 1 configured as described above will be described with reference to FIGS. FIG. 4 is a diagram showing an arrangement when the planar shape of the power generation stack 10 and the auxiliary layer 40 in the flat plate fuel reforming fuel cell 1 is substantially the same, and FIG. It is a figure which shows each arrangement | positioning when the planar shape of the layer 40 is large.

  As shown in FIG. 4, when the projection image A in the stacking direction of the power generation cells 20 onto the planar auxiliary layer 40 of the power generation stack 10 is substantially equal to the planar shape of the auxiliary layer 40, the auxiliary layer 40 is 10 exerts an effect of preventing heat radiation from at least two surfaces (upper and lower surfaces in FIG. 4) of 10.

  Further, as shown in FIG. 5, when the projection image A in the stacking direction of the power generation cells 20 onto the planar auxiliary layer 40 of the power generation stack 10 is smaller than the planar shape of the auxiliary layer 40, The effect which does not escape the heat radiation from up and down is also exhibited.

  When the relationship between the projected image A of the power generation stack 10 and the planar shape of the auxiliary layer 40 is satisfied, for example, the effect of increasing the temperature rise rate of the power generation stack 10 at the start-up and the power generation stack when the fuel cell performs the thermal self-sustaining operation It is effective in maintaining the temperature of

  In particular, when the flat power generation stack 10 is sandwiched between two combustion layers 46 including the current collection layer 48, an effect of suppressing temperature unevenness in the vertical direction of the flat power generation stack 10 during operation of the fuel cell can be obtained.

In FIG. 1, the combustion layers 46 a and 46 b integrated with the power generation stack 10 are provided with a current collection layer 48, and a current line 90 for taking out the current generated from the power generation stack 10 from the auxiliary layer 40 is output. ing. Therefore, the function required for power generation can be realized in a compact size by electrically connecting the auxiliary layer 40 to the power generation stack 10 in series to provide a current collecting function.
[Second Embodiment]
In the second embodiment, a flat plate fuel reforming fuel cell 2 using a solid polymer electrolyte membrane instead of a solid electrolyte in a power generation cell will be described with reference to FIG. FIG. 6 is a cross-sectional view showing a schematic configuration of the power generation cell 120. The flat plate fuel reforming fuel cell 2 of the second embodiment has the same configuration as the flat plate fuel reforming fuel cell 1 of the first embodiment except that a solid polymer electrolyte is used for the power generation cell. The same components are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 6, in the power generation cell 120, a solid polymer electrolyte membrane (PEM: abbreviation of Proton Exchange Membrane) 124 is sandwiched between two electrodes, a fuel electrode 22 (anode) and an air electrode (cathode) 26. .

  A manifold plate 125 on the fuel gas supply path 60 side and a manifold plate 126 on the oxidant gas supply path 70 side each provided with a fuel gas supply path 60 side and an oxidant gas supply path 70 side separated by the solid polymer electrolyte membrane 124. Are overlapped via the sealant 127 with the back surfaces facing each other and changing the phase by 90 °.

A current collector 35 made of a porous carbon sintered body or the like is fitted in each of the fuel gas supply path side 60 and the oxidant gas supply path side 70.
Further, a plurality of grooves 129 that communicate between the fuel gas supply path 60 and the exhaust gas path 80 and a plurality of grooves 131 that communicate between the oxidant gas supply path 70 and the exhaust gas path 80 are partitioned by partition walls 130 and 132, respectively. It is provided.

A power generation stack 10 is formed by stacking a plurality of power generation cells 120 configured as described above via a separator 128.
The flat plate fuel reforming fuel cell 2 using the power generation cell 120 using such a solid polymer electrolyte membrane has the same effect as the flat plate fuel reforming fuel cell 1 of the first embodiment. Yes.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this embodiment, A various aspect can be taken.

1 is a cross-sectional view showing a schematic structure of a flat plate fuel reforming fuel cell 1. FIG. 3 is a cross-sectional view showing a schematic configuration of a power generation cell 20. FIG. It is explanatory drawing which shows the state which decomposed | disassembled the power generation cell. FIG. 2 is a diagram showing an arrangement when the planar shape of the power generation stack 10 and the auxiliary layer 40 is substantially the same planar shape in the flat plate fuel reforming fuel cell 1. FIG. 4 is a diagram illustrating each arrangement when the planar shape of the auxiliary layer 40 is larger than that of the power generation stack 10. 2 is a cross-sectional view showing a schematic configuration of a power generation cell 120. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2 ... Flat fuel reforming type fuel cell, 10 ... Power generation stack, 20, 120 ... Power generation cell, 22 ... Fuel electrode, 24 ... Solid electrolyte body, 26 ... Air electrode, 27 ... Cell body, 28, 30 ... Interconnector 32 ... Air electrode frame 34 ... Insulating frame 35 ... Current collector 36 ... Separator 38 ... Fuel electrode frame 40 ... Auxiliary layer 42 ... Fuel gas reforming layer 44 ... Oxidant heat exchange layer 46, 46a, 46b ... combustion layer, 48 ... current collecting layer, 50 ... heat insulation container, 52 ... burner, 54 ... gas supply path for burner, 60 ... fuel gas supply path, 62 ... vaporizer, 70 ... oxidant gas Supply path, 80 ... exhaust gas path, 90 ... current line, 125,126 ... manifold plate, 127 ... sealing agent, 128 ... separator, 130,132 ... partition, 129,131 ... groove.

Claims (5)

A power generation stack in which a plurality of planar power generation cells are stacked;
A fuel gas reforming layer for reforming the fuel gas to hydrogen, an oxidant heat exchange layer for exchanging heat of the oxidant gas supplied to the power generation stack, or reacting the fuel gas with the oxidant gas And a flat auxiliary layer disposed on the upper and lower surfaces in the stacking direction of the power generation cells of the power generation stack, comprising at least one of the combustion layers for burning.
A fuel reforming fuel cell comprising:
A fuel reforming fuel cell, wherein a projection image of the power generation cell with respect to the auxiliary layer of the power generation stack in a stacking direction is within one plane on the flat auxiliary layer.   2. The fuel reforming fuel cell according to claim 1, wherein the auxiliary layer includes a pair of current collecting layers that collect electricity generated by the power generation stack.   3. The fuel reforming fuel cell according to claim 1, wherein the power generation stack and the auxiliary layer are housed in a container having a heat insulating function.   The fuel reforming fuel cell according to any one of claims 1 to 3, wherein the power generation cell is made of a solid oxide.   The fuel reforming fuel cell according to any one of claims 1 to 3, wherein the power generation cell is made of a solid polymer.