JP2012082102A - Fuel generation device, and secondary battery type fuel cell system including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel generation device capable of reducing energy to be supplied from the outside.SOLUTION: This fuel generation device includes a plurality of fuel generators (for example, containers 8 each storing a fuel generation member 9) which generate fuel containing hydrogen by a chemical reaction and can be regenerated by a reverse reaction of the chemical reaction, wherein at least two of the plurality of fuel generators are thermally connectable (for example each adjacent container 8 is thermally connected through a contact member 10).

Description

  The present invention relates to a fuel generator that generates hydrogen-containing fuel by a chemical reaction and can be regenerated by a reverse reaction of the chemical reaction, and a secondary battery type fuel cell system including the same.

  In recent years, fuel cells that take out electricity when water is generated from hydrogen and oxygen have been actively developed. Since fuel cells do not emit carbon dioxide in principle, they are not only attracting attention as a clean energy source, but they are also energy efficient because they can be extracted in principle, and they are energy-saving. By recovering the heat, the heat energy can be used, and it is expected as a trump card for solving global energy and environmental problems.

  Such fuel cells include, for example, a solid polymer electrolyte membrane using a solid polymer ion exchange membrane, a solid oxide electrolyte membrane using yttria-stabilized zirconia (YSZ), and the like as a fuel electrode (anode) and an oxidizer electrode ( A single cell structure is formed by sandwiching between the cathode and the cathode from both sides and further sandwiching the outside with a pair of separators. In the cell having such a configuration, a fuel gas flow path for supplying a fuel gas (for example, hydrogen gas) to the fuel electrode, and an oxidant gas flow for supplying an oxidant gas (for example, oxygen or air) to the oxidant electrode. A fuel gas and an oxidant gas are respectively supplied to the fuel electrode and the oxidant electrode through these flow paths.

  There are various usage forms of the fuel cell, one of which is mounted on an EV (electric vehicle) and used as a power source for the EV. In such a usage mode, since the EV is a moving body, it is necessary to make the fuel cell not a type to which fuel is supplied from the outside but a type (secondary battery type) to which a renewable fuel generator is attached. is there.

  Examples of the renewable fuel generator include a fuel generator that generates a fuel containing hydrogen by a chemical reaction and can be regenerated by a reverse reaction of the chemical reaction. As a fuel generator that generates hydrogen-containing fuel by chemical reaction and can be regenerated by reverse reaction of the chemical reaction, for example, the base material (main component) is iron, and hydrogen is generated by oxidation reaction with water. Examples of the hydrogen generator that can be generated and regenerated by a reduction reaction with hydrogen are given.

JP 2006-503414 A (summary) JP 2009-99491 A (summary) JP 2001-295996 A (summary) JP 2007-26683 A (summary)

A hydrogen generator whose base material (main component) is iron can generate hydrogen by an oxidation reaction represented by the following formula (1). The enthalpy change ΔH 2 _O, which is the energy necessary to produce 1 mol of Fe ₃ O ₄ by the oxidation reaction shown in the following formula (1), is a negative value (for example, −115 [kJ / mol] under the condition of 500 ° C.) Therefore, the oxidation reaction shown in the following formula (1) is an exothermic reaction.
3Fe + 4H ₂ O → Fe ₃ O ₄ + 4H ₂ ΔH _O <0 (1)

Moreover, the hydrogen generator whose base material (main component) is iron can be regenerated by the reduction reaction shown in the following formula (2). The reduction reaction shown in (2) below the energy required for reducing the Fe ₃ O ₄ of 1mol enthalpy change [Delta] H _R is a positive value (e.g., 115 [kJ / mol] under the conditions of 500 ° C.) Therefore, the reduction reaction shown in the following formula (2) is an endothermic reaction. Therefore, it is necessary to supply energy from the outside to the hydrogen generator at the time of regeneration, and this energy supply has been a factor of reducing the efficiency of the battery.
_{Fe 3 O 4 + 4H 2 →} 3Fe + 4H 2 O ΔH R> 0 ... (2)

  Although Patent Documents 1 to 4 disclose a fuel cell system to which a fuel generator is attached, the fuel cell system is not a type (secondary battery type) fuel cell system to which a renewable fuel generator is attached.

  An object of this invention is to provide the fuel generator which can reduce the energy supplied from the outside in view of said situation, and a secondary battery type fuel cell system provided with the same.

  In order to achieve the above object, a fuel generator according to the present invention includes a plurality of fuel generators that generate a fuel containing hydrogen by a chemical reaction and can be regenerated by a reverse reaction of the chemical reaction, and the plurality of fuel generators. At least two of these are configured to be thermally connectable.

  According to such a configuration, the heat generated by the exothermic reaction in one fuel generator is transmitted to another fuel generator thermally connected to one fuel generator, and the other fuel generator Since the transmitted heat can be used when an endothermic reaction is caused, the energy supplied from the outside to the other fuel generator to cause the endothermic reaction can be reduced. One of “chemical reaction” and “reverse reaction of the chemical reaction” is an exothermic reaction, and the other is an endothermic reaction.

  In addition, switching means for switching between a state where at least two of the plurality of fuel generators are thermally connected and a state where they are not thermally connected may be provided. As a result, it is possible to establish a thermally connected state only when it is desired to transfer heat, so that heat can be transferred efficiently.

  In addition, the switching unit may include a shape changing member whose shape changes depending on the temperature. As a result, the switching means can be realized without providing a drive mechanism, so that heat can be transferred easily and efficiently.

  For example, a bimetal or a shape memory alloy can be used for the shape changing member.

  In order to achieve the above object, a secondary battery type fuel cell system according to the present invention includes a fuel generator having any one of the above-described configurations, and a fuel cell device that generates power using fuel supplied from the fuel generator. It is set as the structure provided with.

  The fuel generator is a hydrogen generator that generates hydrogen, the fuel cell device is a solid oxide fuel cell, and a circulation path for circulating gas between the fuel generator and the fuel cell device is provided. You may make it prepare.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel generator which can reduce the energy supplied from the outside, and a secondary battery type fuel cell system provided with the same are realizable.

It is a mimetic diagram showing a schematic structure of a fuel cell system concerning one embodiment of the present invention. It is a schematic diagram which shows schematic structure of a solid oxide fuel cell. It is a longitudinal cross-sectional view which shows schematic structure of 1st Example of a fuel generator. It is a longitudinal cross-sectional view which shows schematic structure of 1st Example of a fuel generator. It is a longitudinal cross-sectional view which shows schematic structure of 2nd Example of a fuel generator. It is a longitudinal cross-sectional view which shows schematic structure of 2nd Example of a fuel generator. It is a longitudinal cross-sectional view which shows schematic structure of 3rd Example of a fuel generator. It is a longitudinal cross-sectional view which shows schematic structure of 3rd Example of a fuel generator. It is a longitudinal cross-sectional view which shows schematic structure of 4th Example of a fuel generator. It is a longitudinal cross-sectional view which shows schematic structure of 4th Example of a fuel generator.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments described later.

<Configuration of secondary battery type fuel cell system>
FIG. 1 is a diagram showing an overall configuration of a secondary battery type fuel cell system according to an embodiment of the present invention. The secondary battery type fuel cell system according to an embodiment of the present invention shown in FIG. 1 generates a fuel containing hydrogen by a chemical reaction and has a plurality of fuel generators that can be regenerated by a reverse reaction of the chemical reaction. Gas is generated between the device 1, a fuel cell device 2 that generates power by a reaction between an oxidant containing oxygen and a fuel containing hydrogen supplied from the fuel generator 1, and the fuel generator 1 and the fuel cell device 2. And a circulation path 3 for circulation. Further, the fuel generator 1, the fuel cell device 2, and the circulation path 3 of the secondary battery type fuel cell system according to the embodiment of the present invention shown in FIG. You may provide the pump for circulating the gas in the path | route 3, the sensor which detects the leakage of the fuel gas containing hydrogen, the flow rate controller which controls the gas flow rate to each fuel generator separately, etc. In this embodiment, as will be described later, one fuel cell device 2 performs both power generation and water electrolysis, but each of the plurality of fuel generators is a fuel cell (for example, a solid oxide fuel cell dedicated to power generation). ) And a water electrolyzer (for example, a solid oxide fuel cell dedicated to water electrolysis) may be connected in parallel on the gas circulation path.

<Configuration and operation of fuel cell device>
As the fuel cell device 2, for example, as shown in FIG. 2, an MEA (Membrane Electrode Assembly; membrane) in which a solid electrolyte 4 that transmits O ²⁻ is sandwiched and an oxidant electrode 5 and a fuel electrode 6 are formed on both sides, respectively. -Electrode assembly) A solid oxide fuel cell having a structure can be used. 2 shows a structure in which only one MEA is provided, a plurality of MEAs may be provided, or a plurality of MEAs may be stacked. In the solid oxide fuel cell, the following reaction (3) occurs in the fuel electrode 6 during the power generation operation.
H ₂ + O ²⁻ → H ₂ O + 2e ⁻ (3)

Electrons generated by the reaction of the above formula (3) reach the oxidant electrode 5 through the external load 7, and the reaction of the following formula (4) occurs at the oxidant electrode 5.
1 / 2O ₂ + 2e ⁻ → O ²⁻ (4)

The oxygen ions generated by the reaction of the above formula (4) reach the fuel electrode 6 through the solid electrolyte 4. By repeating the above series of reactions, the solid oxide fuel cell performs a power generation operation. Further, as can be seen from the above expression (3), during the power generation operation, H ₂ is consumed and H ₂ O is generated on the fuel electrode 6 side.

On the other hand, in a solid oxide fuel cell, when operated as an electrolyzer, the reverse reaction of the above formulas (3) and (4) occurs, and H ₂ O is consumed on the fuel electrode 6 side to generate H _2. The

  Therefore, when a solid oxide fuel cell is used for the fuel cell device 2, the gas (hydrogen gas, water vapor gas) consumed or generated on the fuel electrode 6 side as described above is the fuel electrode of the fuel cell device 2. It circulates between the 6 side and the fuel generator 1.

<Reaction at the fuel generator>
When a solid oxide fuel cell is used for the fuel cell device 2, for example, each fuel generator of the fuel generator 1 may contain an iron fine particle compact. The fuel generator 1 having such a configuration can generate hydrogen by the oxidation reaction shown in the above-described equation (1).

  When the oxidation reaction of iron shown in the above formula (1) proceeds, the change from iron to iron oxide proceeds and the remaining amount of iron decreases, but the reduction reaction shown in the above formula (2) (the above-mentioned (1 The fuel generator 1 can be regenerated and the system can be charged by the reverse reaction of the oxidation reaction shown in the formula (1).

<First Example of Fuel Generator>
In the fuel generating apparatus 1 according to the first embodiment, as shown in FIG. 3A, the container 8 has a plurality of partition walls, and a fuel generating member (here, iron fine particle compression) is provided in each section partitioned by the partition walls. Body) 9 is accommodated. With such a structure, the fuel generator 1 according to the first embodiment has a plurality of fuel generators, and each fuel generator is thermally connected by the partition walls. Here, “thermally connected” means the atmosphere around the fuel generator 1 (usually air, and the thermal conductivity near room temperature is about 0.026 W / (m · K)). The state where the heat conduction better than the heat conduction using the medium is realized. The material of the partition wall of the container 8 is a metal, metal oxide, alloy (for example, SUS (about 15 W / (m · K)), glass (about about 0.1 W / (m · K)) or higher. 1 W / (m · K)), Inconel (about 15 W / (m · K)) and the like are preferable.

  In the fuel generator 1 according to the first embodiment, when the fuel cell device 2 is generating electric power using the fuel generated by a certain fuel generator, it is generated by an oxidation reaction of iron in the certain fuel generator. The generated heat is transmitted to another fuel generator that is thermally connected to a certain fuel generator, for example, using regenerative power generated during braking in EV or power supplied from an external power source. When the secondary battery type fuel cell system according to one embodiment of the present invention shown in FIG. 2 is charged, the reduced heat (the iron oxidation reaction) of the iron oxide is utilized in the other fuel generator using the transmitted heat. It is possible to cause the reverse reaction). Therefore, it is possible to reduce the energy supplied from the outside to the another fuel generator in order to cause the reduction reaction of iron oxide, which is an endothermic reaction. Thereby, even if the energy supplied from the outside is reduced, the secondary battery type fuel cell system according to the embodiment of the present invention shown in FIG. 1 can be charged, and the efficiency of the battery system is improved.

  3A, the container 8 is not provided with a plurality of partition walls, but a plurality of containers 8 are provided as shown in FIG. 3B, and the fuel generating member 9 is accommodated in each of the plurality of containers 8 to generate adjacent fuel. The same effect can be obtained even if the fuel generators are thermally connected by providing the contact member 10 between the containers. In this case, the material of the contact member 10 is a metal, metal oxide, alloy (for example, SUS (about 15 W / approximately) having a thermal conductivity of 0.1 W / (m · K) or more, similar to the material of the partition of the container 8. (M · K)), glass (about 1 W / (m · K)), inconel (about 15 W / (m · K)), etc.) are preferable.

<Second Embodiment of Fuel Generator>
As shown in FIGS. 4A and 4B, the fuel generator 1 according to the second embodiment is provided with a plurality of containers 8, and each of the plurality of containers 8 has a fuel generating member (here, an iron fine particle compact). 9 is housed. With such a structure, the fuel generator 1 according to the second embodiment has a plurality of fuel generators. Adjacent fuel generators can be thermally connected via the contact member 10. The material of the container 8 and the material of the contact member 10 are metals, metal oxides, alloys (for example, SUS (about 15 W / (m · K)) having a thermal conductivity of 0.1 W / (m · K) or more. ), Glass (about 1 W / (m · K)), inconel (about 15 W / (m · K)), etc.) are preferable.

  The fuel generator 1 according to the second embodiment is also provided with a contact member drive mechanism 11. The contact member drive mechanism 11 includes a contact member 10 inserted between adjacent fuel generators to thermally connect the adjacent fuel generators, and between the adjacent fuel generators. 10 is extracted, and the contact member 10 is driven so that it can be switched to a state in which adjacent fuel generators are not thermally connected.

  In the fuel generator 1 according to the second embodiment, for example, when it is desired to transfer heat from a fuel generator having a remarkable exothermic reaction to a fuel generator that is to promote the endothermic reaction preferentially, only the two fuel generators are Can be connected to each other (see FIG. 4B), so that heat can be efficiently transferred between the two fuel generators. In addition, by changing the shape and driving mode of the contact member 10 from the mode shown in FIGS. 4A and 4B, not only the thermal connection between adjacent fuel generators, but also the heat between any two fuel generators. Connection is also possible.

<Third embodiment of fuel generator>
As shown in FIGS. 5A and 5B, the fuel generator 1 according to the third embodiment is provided with a plurality of containers 8, each of which has a fuel generating member (here, an iron fine particle compact). 9 is housed. With this structure, the fuel generator 1 according to the third embodiment has a plurality of fuel generators. The material of the container 8 is a metal, metal oxide, alloy (for example, SUS (about 15 W / (m · K)) or glass (about 1 W / K) having a thermal conductivity of 0.1 W / (m · K) or more. (M · K)), Inconel (about 15 W / (m · K)) and the like are preferable.

  Each fuel generator of the fuel generator 1 according to the third embodiment is connected to a shape changing member 12 whose shape changes depending on the temperature of a bimetal, a shape memory alloy or the like. According to such a configuration, for example, when the temperature of a certain fuel generator becomes equal to or higher than a predetermined temperature, the deformation of the shape changing member 12 connected to the certain fuel generator causes deformation of the certain fuel generator and the fuel generator. Since it is possible to thermally connect another adjacent fuel generator (see FIG. 5B), a fuel generator that exhibits a significant exothermic reaction and another adjacent fuel generator are automatically thermally connected. Since it can be connected and the drive mechanism as in the second embodiment described above is not required, heat transfer between the two fuel generators can be easily performed.

The bimetal described above is a shape changing member having a structure in which two kinds of conductive materials having different linear expansion coefficients are joined. For example, a stainless steel material having a linear expansion coefficient of 17 × 10 ⁻⁶ / ° C. and a titanium alloy having a linear expansion coefficient of 9 × 10 ⁻⁶ / ° C. can be joined. When heated, a bimetal having a structure in which two types of conductive materials having different linear expansion coefficients are joined is curved in a convex shape toward the metal material having a large linear expansion coefficient.

Here, reference values of the linear expansion coefficient of the metal material are shown in ascending order. In order to satisfy the design conditions described above, two types having different linear expansion coefficients may be selected from the metals listed below or other metals.
^{Cr: 6.5 × 10 -6 /℃,Ti:8.9×10 -6} /℃,Pt:9.0×10 -6 /℃,SUS430:10.4×10 -6 / ℃, Co: ^{12.5 × 10 -6 /℃,Ni:13.3×10 -6 /℃,Au:14.1×10 -6} /℃,SUS310:15.8×10 -6 / ℃, Mo: 16. ^{0 × 10 -6 /℃,SUS316:16.0×10 -6 /℃,SUS301:16.9×10 -6} /℃,Cu:17.0×10 -6 /℃,SUS304:17.3× ^{10 -6 /℃,Ag:19.1×10 -6 /℃,Mn:23.0×10 -6 /℃,Pb:29.0×10 -6} / ℃

<Fourth Embodiment of Fuel Generator>
As shown in FIG. 6A and FIG. 6B, the fuel generator 1 according to the fourth embodiment is provided with a plurality of heat insulating containers (for example, containers having a vacuum heat insulating structure) 13. A fuel generating member (here, an iron fine particle compact) 9 is accommodated. With such a structure, the fuel generator 1 according to the fourth embodiment has a plurality of fuel generators. The material of the inner and outer walls of the heat insulating container 13 and the material of the contact member 10 are metals, metal oxides, alloys (for example, SUS (about 15 W / (about 15) / (M · K) or more)). m · K)), glass (about 1 W / (m · K)), inconel (about 15 W / (m · K)) and the like) are preferable.

  Each heat insulating container 13 is provided with a shape changing member 12 whose shape changes depending on the temperature of a bimetal, a shape memory alloy, or the like. According to such a configuration, when the temperature in a certain heat insulation container becomes equal to or higher than a predetermined temperature, the inside and outside of the heat insulation container are thermally connected by deformation of the shape changing member 12 provided in the heat insulation container. (See FIG. 6B). In other words, the heat insulating structure of the heat insulating container normally allows heat to remain in the heat insulating container, and the heat in the heat insulating container can be transferred to the outside of the heat insulating container only when necessary. Thereby, heat can be more efficiently transferred.

  In the form shown in FIGS. 6A and 6B, heat transfer between the heat insulating containers 13 is performed via the contact member 10, but instead of the contact member 10, another heat transfer member (for example, a bimetal or a shape memory alloy). A shape-changing member whose shape changes depending on the temperature, etc.), the outer walls of the plurality of heat insulating containers 13 may be physically contacted, and the outer walls of the plurality of heat insulating containers 13 may be integrally formed. Also good.

DESCRIPTION OF SYMBOLS 1 Fuel generator 2 Fuel cell apparatus 3 Circulation path | route 4 Solid electrolyte 5 Oxidizer electrode 6 Fuel electrode 7 External load 8 Container 9 Fuel generating member 10 Contact member 11 Contact member drive mechanism 12 Shape change member 13 Thermal insulation container

Claims (6)

A fuel containing hydrogen is generated by a chemical reaction, and a plurality of fuel generators that can be regenerated by a reverse reaction of the chemical reaction are provided.
A fuel generator, wherein at least two of the plurality of fuel generators are thermally connectable.   2. The fuel generator according to claim 1, further comprising switching means for switching between a state in which at least two of the plurality of fuel generators are thermally connected and a state in which they are not thermally connected. .   The fuel generating device according to claim 2, wherein the switching unit includes a shape changing member whose shape changes with temperature.   The fuel generating device according to claim 3, wherein the shape changing member is a bimetal or a shape memory alloy. The fuel generator according to any one of claims 1 to 4,
A secondary battery type fuel cell system comprising: a fuel cell device that generates electricity using the fuel supplied from the fuel generator. The fuel generator is a hydrogen generator for generating hydrogen;
The fuel cell device is a solid oxide fuel cell;
The secondary battery type fuel cell system according to claim 5, further comprising a circulation path for circulating gas between the fuel generation device and the fuel cell device.

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