JP2005085598A - Chemical heat-storage hydrogen-storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical heat-storage hydrogen-storage device capable of storing heat and hydrogen at the same time, and of leveling hydrogen consumption of a fuel cell. <P>SOLUTION: This chemical heat-storage hydrogen-storage device is provided with: a first reactor 17 where an endothermic reaction A for releasing hydrogen or an exothermic reaction A<SP>*</SP>of its reverse reaction for absorbing hydrogen is generated; a second reactor 18 where an exothermic reaction B for absorbing hydrogen below a predetermine temperature or an endothermic reaction B<SP>*</SP>of its reverse reaction for releasing hydrogen is generated in the same pressure condition as the pressure of the first reactor 17; a first communication tube 19 for making both the reactors communicate with each other; a first heat exchanger 20 for exchanging heat with the environment in the first reactor 17; a second heat exchanger 21 connected to a circulation circuit 14 for circulating a heat medium fluid between the fuel cell 11 and the second reactor 18 for heating the inside of the second reactor 18 for exchanging heat with the heat medium fluid heated by recovering exhaust heat of the cell 11 and for heating the heat medium fluid by recovering generated heat of the reaction B; and a second communication tube 22 for making a hydrogen supply tube 13 for supplying hydrogen to the cell 11 from a hydrogen supply device 12, and the communication tube 19 communicate with each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a chemical heat storage hydrogen storage device, and more particularly to a chemical heat storage hydrogen storage device used in combination with a fuel cell using hydrogen as a fuel gas.

  Conventionally, as an apparatus using an endothermic reaction for releasing hydrogen and an exothermic reaction for absorbing hydrogen which is the reverse reaction, the following devices are known.

  For example, Patent Document 1 discloses that a hydrogen storage alloy sufficiently hydrogenated by hydrogen supplied from a hydrogen supply device is dehydrogenated by exhaust heat recovered from an exhaust heat source to generate high-pressure hydrogen. A heat storage device is disclosed in which high-pressure hydrogen is allowed to act to hydrogenate other hydrogen storage alloys and use the heat generated at this time.

  Further, Patent Document 2 uses two types of hydrogen storage alloys having different hydrogen dissociation pressures and two types of compressors having different powers, and manufactures cold storage water for air conditioning cooling using nighttime power. Such a heat storage device is disclosed.

  In Patent Document 3, a fuel cell is connected to a heat pump filled with two types of hydrogen storage alloys having different equilibrium hydrogen pressures, and the exhaust heat of the fuel cell is used as a heat source for the heat pump. A hydrogen refining apparatus is disclosed in which cold energy obtained at the time of hydrogen release is used for cooling or the like, and hydrogen released from the hydrogen storage alloy is supplied to the fuel cell.

Japanese Patent Laid-Open No. 7-2108030 JP-A-10-122695 JP 2000-340242 A

  However, the heat storage devices disclosed in Patent Documents 1 and 2 are mere heat storage devices using a hydrogen storage alloy and cannot store both heat and hydrogen.

  The hydrogen purifier disclosed in Patent Document 3 is used in combination with a fuel cell. Basically, a hydrogen storage alloy absorbs and desorbs hydrogen to extract cold while purifying hydrogen. Therefore, it cannot be used for leveling the hydrogen consumption used in fuel cells.

  The problem to be solved by the present invention is to provide a chemical heat storage hydrogen storage device capable of performing heat storage and hydrogen storage simultaneously, and capable of leveling the hydrogen consumption of the fuel cell. It is in.

In order to solve the above problems, a chemical heat storage hydrogen storage device according to the present invention is:
It is used in combination with a fuel cell that uses hydrogen supplied through a hydrogen supply pipe derived from a hydrogen supply device as a fuel gas, and absorbs hydrogen, which is an endothermic reaction A that releases hydrogen, or its reverse reaction. A first reactor in which an exothermic reaction A ^* occurs, and an exothermic reaction B that absorbs hydrogen at a temperature equal to or lower than a predetermined temperature under the same pressure as the pressure in the first reactor or an endothermic reaction B that releases hydrogen, which is the reverse reaction. ^A second reactor in which ^* occurs, a first communication pipe that connects the first reactor and the second reactor, and the first reactor, and the inside of the first reactor and the external environment A first heat exchanger for exchanging heat between the fuel cell and the second reactor and connected to a circulation circuit for circulating a heat medium fluid between the fuel cell and the second reactor; Before the exhaust heat from the heat is recovered and heated A second heat exchanger capable of heating the inside of the container by exchanging heat with the heat medium fluid and recovering heat generated by the exothermic reaction B to heat the heat medium fluid in the circulation circuit; The gist of the present invention is a second communication pipe that communicates with at least one of the reactor, the second reactor, and the first communication pipe, and has the other end communicated with the hydrogen supply pipe.

  The gist is that the hydrogen is pure hydrogen or reformed hydrogen.

  The gist of the fuel cell is a polymer electrolyte fuel cell, a phosphoric acid fuel cell, or a solid oxide fuel cell.

  According to the chemical heat storage hydrogen storage device of the present invention, by adopting the above configuration, both the first reactor and the second reactor can store heat while releasing hydrogen, and further, the first reactor The second reactor can store hydrogen while releasing heat.

  Therefore, when the output of the fuel cell is large such that the amount of hydrogen used increases and the amount of exhaust heat released increases, this chemical heat storage hydrogen storage device is very effective. Conversely, when the output of the fuel cell is small such that the amount of hydrogen used is reduced and the amount of exhaust heat released is reduced, the chemical heat storage hydrogen storage device is very effective.

  In addition, when the fuel cell is generating electricity at its maximum output, the amount of hydrogen used is large, so that hydrogen is insufficient with only hydrogen supplied from the hydrogen supply device. Hydrogen can be replenished from the hydrogen unit. On the other hand, when the fuel cell is stopped, hydrogen is not used, so the hydrogen supplied from the hydrogen supply device becomes redundant. In this case, hydrogen is stored by the chemical heat storage hydrogen storage device. can do. Therefore, according to the chemical heat storage hydrogen storage device according to the present invention, the hydrogen consumption of the fuel cell can be leveled.

  Therefore, for example, when a reformer is used as the hydrogen supply device, there is a request that the output of the reformer is not changed as much as possible, and a constant operation is desired, but the chemical heat storage hydrogen storage device according to the present invention is required. According to the request.

  Below, the chemical heat storage hydrogen storage apparatus which concerns on this embodiment is demonstrated in detail. Drawing 1 is a figure showing the schematic structure of the chemical heat storage hydrogen storage device concerning this embodiment.

  The chemical heat storage hydrogen storage device 10 is basically used in combination with a fuel cell 11 that uses hydrogen as a fuel gas. A hydrogen supply device 12, a hydrogen supply pipe 13, a circulation circuit 14 and the like are connected to the fuel cell 11.

  The fuel cell 11 has a single cell in which a fuel electrode (not shown) is joined to one surface of an electrolyte (not shown) and an air electrode (not shown) is joined to the other surface, and hydrogen such as reformed hydrogen or pure hydrogen is used as fuel. In addition to being supplied to the fuel electrode as a gas, an oxidant gas such as oxygen or air is supplied to the air electrode, thereby generating an electromotive force between the electrodes. Specifically, the fuel cell 11 includes a solid polymer fuel cell (PEFC) using a solid polymer as an electrolyte, a phosphoric acid fuel cell (PAFC) using phosphoric acid as an electrolyte, and an electrolyte. Examples thereof include a solid oxide fuel cell (SOFC) using a solid oxide.

  The hydrogen supply device 12 is for supplying hydrogen to the fuel cell 11. For example, the hydrogen supply device 12 decomposes a reformer, gasoline, methanol, or the like that generates reformed hydrogen by reacting high-temperature steam with city gas. A reformer that generates reformed hydrogen, a device that extracts hydrogen by a dehydrogenation reaction of an organic substance such as cyclohexane or decalin, a hydrogen cylinder filled with pure hydrogen, or the like can be used. A hydrogen supply pipe 13 is led out from the hydrogen supply device 12 so that hydrogen can be supplied to the fuel electrode of the fuel cell 11.

  A circulation device such as a pump (not shown) is attached to the circulation circuit 14 so that a heat medium fluid such as water can be circulated. Thereby, the exhaust heat of the fuel cell 11 can be recovered via the heat exchanger 15, and the heated heat medium fluid can be circulated. In FIG. 1, a heat utilization unit 16 is provided on the circulation circuit 14.

  The chemical heat storage hydrogen storage device 10 includes a first reactor 17, a second reactor 18, a first communication pipe 19, a first heat exchanger 20, a second heat exchanger 21, and a second communication pipe 22. Yes.

In the chemical heat storage hydrogen storage device 10, the first reactor 17 is configured such that an endothermic reaction A that releases hydrogen or an exothermic reaction A ^* that absorbs hydrogen, which is the reverse reaction, occurs. The first reactor 17 is provided with a first heat exchanger 20 so that heat exchange can be performed between the inside of the first reactor 17 and the external environment. Thereby, the temperature in the 1st reactor 17 can be maintained at the same temperature as outside temperature.

In the first reactor 17, if the hydrogen pressure in the first reactor 17 proceeds in the decreasing direction, an endothermic reaction A occurs so as to cancel it, and if the hydrogen pressure in the first reactor 17 proceeds in the increasing direction. An exothermic reaction A ^* occurs to counteract this. The pressure in the first reactor 17 is determined by the equilibrium pressure of the chemical reaction in the first reactor 17.

On the other hand, the second reactor 18 is hydrogen at a predetermined temperature (for example, 80 ° C. in the case of using heat for hot water supply in the heat utilization section 16) under the same pressure as the pressure in the first reactor 17. Exothermic reaction B that absorbs hydrogen or an endothermic reaction B ^* that releases hydrogen, which is the reverse reaction, occurs. The second reactor 18 is provided with a second heat exchanger 21 so that it can be connected to the circulation circuit 14. Thus, heat exchange is performed with the heat medium fluid heated by the exhaust heat of the fuel cell 11 to heat the inside of the second reactor 18, or the heat generated by the exothermic reaction B in the second reactor 18 is recovered and circulated. The heating medium fluid in the circuit 14 can be heated.

In the second reactor 18, if the temperature in the second reactor 18 is lowered in a direction lower than the predetermined temperature, an exothermic reaction B occurs so as to cancel the temperature, and the temperature in the second reactor 18 rises above the predetermined temperature. When proceeding in the direction, an endothermic reaction B ^* occurs so as to cancel this.

  The first reactor 17 and the second reactor 18 are communicated with each other through a first communication pipe 19. As a result, the pressures in the reactors 17 and 18 are made equal to each other, and hydrogen generated in the first reactor 17 or the second reactor 18 can pass back and forth between the reactors.

Here, the endothermic reaction A and the exothermic reaction B make a pair, and the exothermic reaction A ^* and the endothermic reaction B ^{* make} a pair. As the endothermic reaction A and endothermic reaction B ^* that release hydrogen, physical or chemical desorption of hydrogen, dehydrogenation reaction, or the like is used. On the other hand, as the exothermic reaction A ^* and the exothermic reaction B that absorb hydrogen, hydrogen physical or chemical adsorption, hydrogenation reaction, or the like is used. As a specific chemical reaction combination, hydrogen storage alloys having different operating temperatures can be used.

  As an example of the combination of the above chemical reactions, a hydrogen storage alloy that operates at a relatively low temperature in the first reactor 17 as a medium substance, and a hydrogen storage alloy that operates at a high temperature in the second reactor 18 is used. Just fill it.

When MmNi _4.5 Al _0.5 is placed in the first reactor 17 and LaNi _4.7 Al _0.3 is placed in the second reactor 18, the pressure is about 4 atmospheres and the temperature is the same as that of the first reactor 17. About 25 degreeC and the 2nd reactor 18 will be about 85 degreeC. When MmNi ₅ is put in the first reactor 17 and LaNi ₅ is put in the second reactor 18, the pressure is about 14 atm, the temperature is about 25 ° C. in the first reactor 17, and the second reactor 18 is About 85 ° C (Mm: Misch metal)

  The first communication pipe 19 and the hydrogen supply pipe 13 are communicated with each other through a second communication pipe 22. Thereby, the hydrogen generated in the first reactor 17 or the second reactor 18 can be supplied to the fuel cell 11, and the hydrogen generated by the hydrogen supply device 12 is supplied to the first reactor 17 or the second reactor 18. Can be supplied. The second communication pipe 22 may be communicated with the first reactor 17 or the second reactor 18. Further, the chemical heat storage hydrogen storage device 10 and the hydrogen supply pipe 13 may be communicated with each other by a plurality of second communication pipes 22.

  Next, operation | movement of the chemical thermal storage hydrogen storage apparatus 10 which concerns on this embodiment is demonstrated in detail using FIGS. The chemical heat storage hydrogen storage device 10 always operates at a constant pressure.

FIG. 2 is a diagram illustrating an operation during heat storage. When hydrogen is supplied through the hydrogen supply pipe 13 from the hydrogen supply device 12 (assumed to be operating at a constant output), the fuel cell 11 generates electric power using this hydrogen and generates exhaust heat. When the exhaust heat is not used (the heat utilization in the heat utilization unit 16 is low), the exhaust heat is used for heat storage. That is, the exhaust heat of the fuel cell 11 is recovered by the heat exchanger 15, and the heat medium fluid in the circulation circuit 14 is heated by the recovered exhaust heat. The heated heat medium fluid is sent to the second reactor 18 side (in the direction of the arrow in the drawing), and heat exchange with the heat medium fluid is performed in the second reactor 18 via the second heat exchanger 21. As a result, the exhaust heat of the fuel cell 11 is input into the second reactor 18 and the temperature in the reactor tends to rise, so that an endothermic reaction B ^* occurs and hydrogen is generated.

On the other hand, the generated hydrogen moves to the first reactor 17 side through the first communication pipe 19 due to the pressure difference. In the first reactor 17, hydrogen tends to flow from the second reactor 18, so that an exothermic reaction A ^* occurs to maintain the hydrogen pressure, and the hydrogen is absorbed. At this time, the generated heat is discarded to the environment (outside air temperature) via the first heat exchanger 20.

  FIG. 3 is a diagram illustrating an operation during heat dissipation. In FIG. 3, the fuel cell 11 is basically stopped and no hydrogen is used. In such a case, if the heat is utilized in the heat utilization unit 16, the temperature in the second reactor 18 tends to decrease, so that the exothermic reaction B occurs in the second reactor 18 to maintain the predetermined temperature, and the hydrogen is Absorbed. At this time, the generated heat is recovered through the second heat exchanger 21, and the heat medium fluid in the circulation circuit 14 is heated by the recovered heat. The heated heat medium fluid is sent to the heat utilization unit 16 and used for heat utilization.

  On the other hand, in the first reactor 17, hydrogen is about to be sucked into the second reactor 18, so that an endothermic reaction A occurs and hydrogen is generated while maintaining the hydrogen pressure. At this time, heat necessary for the reaction is taken in from the environment (outside air temperature) via the first heat exchanger 20.

FIG. 4 is a diagram showing the operation during hydrogen storage. In FIG. 4, the fuel cell 11 is basically stopped and is not used for heat. In such a case, hydrogen supplied from the hydrogen supply device 12 becomes surplus in the hydrogen supply pipe 13. Therefore, surplus hydrogen is stored using the medium substance in the first reactor 17. That is, surplus hydrogen in the hydrogen supply pipe 13 moves from the hydrogen supply pipe 13 to the first reactor 17 side through the second communication pipe 22 due to a pressure difference. In the first reactor 17, since hydrogen tends to flow in, an exothermic reaction A ^* occurs to maintain the hydrogen pressure, and the hydrogen is absorbed. At this time, the generated heat is discarded to the environment via the first heat exchanger 20. Note that no reaction occurs in the second reactor 18.

  FIG. 5 is a diagram showing an operation when hydrogen is released. In FIG. 5, the fuel cell 11 is in a sufficient power generation state, and the heat utilization unit 16 also uses heat. In such a case, hydrogen is insufficient with only the hydrogen supplied from the hydrogen supply device 12, so that hydrogen is replenished using the hydrogen stored in the medium material in the first reactor 17. That is, when the amount of hydrogen used by the fuel cell 11 increases, the pressure in the hydrogen supply pipe 13 decreases, and therefore, in the first reactor 17, an endothermic reaction A occurs to maintain the hydrogen pressure, and hydrogen is generated. At this time, heat necessary for the reaction is taken in from the environment (outside air temperature) via the first heat exchanger 20. The generated hydrogen is supplied to the fuel cell 11 through the second communication pipe 22 and the hydrogen supply pipe 13. Note that no reaction occurs in the second reactor 18.

  2 and 3 described above are basically the same as the chemical heat storage in which the working medium is hydrogen in the heat storage and the heat release. 4 and 5 are basically the same as the chemical storage of hydrogen using a hydrogen storage alloy or the like when storing hydrogen and releasing hydrogen.

  Here, the utility of the chemical heat storage hydrogen storage device 10 is particularly enhanced during heat storage / hydrogen release and heat dissipation / hydrogen storage. Hereinafter, operations during heat storage / hydrogen release and heat dissipation / hydrogen storage will be described.

FIG. 6 is a diagram showing an operation during heat storage / hydrogen release. When hydrogen is supplied from the hydrogen supply device 12 through the hydrogen supply pipe 13, the fuel cell 11 generates electric power using the hydrogen and generates exhaust heat. As described in the heat storage operation of FIG. 2, when the exhaust heat of the fuel cell 11 is input to the second reactor 18, the temperature in the second reactor 18 tends to rise, so that the endothermic reaction B ^* Occurs to generate hydrogen.

  At this time, when hydrogen is taken out from the chemical heat storage hydrogen storage device 10 through the second communication pipe 22 more than the amount of hydrogen generated in the second reactor 18, the hydrogen pressure in the reactor tends to decrease. In the first reactor 17, an endothermic reaction A occurs to maintain the hydrogen pressure, and hydrogen is generated. That is, in this operation, heat storage is performed while releasing hydrogen in both the first reactor 17 and the second reactor 18.

  FIG. 7 is a diagram showing the operation during heat dissipation / hydrogen storage. In FIG. 7, the fuel cell 11 is basically stopped, and hydrogen is not used at all. In such a case, if the heat is utilized in the heat utilization unit 16, the temperature in the second reactor 18 tends to decrease, so that the exothermic reaction B occurs in the second reactor 18 to maintain the predetermined temperature, Absorbed. The generated heat is recovered through the second heat exchanger 21, and the heat medium fluid in the circulation circuit 14 is heated by the recovered heat. The heated heat medium fluid is sent to the heat utilization unit 16 and used for heat utilization.

At this time, if the amount of hydrogen flowing into the chemical heat storage hydrogen storage device 10 from the hydrogen supply pipe 13 exceeds the amount of hydrogen absorbed by the exothermic reaction B, the hydrogen pressure in the container tends to increase. In the reactor 17, an exothermic reaction A ^* occurs to maintain the hydrogen pressure, and hydrogen is absorbed. That is, in this operation, hydrogen is stored while releasing heat in both the first reactor 17 and the second reactor 18.

  As described with reference to FIGS. 6 and 7, when the output of the fuel cell is large, the amount of hydrogen used increases and the amount of exhaust heat released increases, so that the function of simultaneously storing heat and releasing hydrogen is very good. Useful for. On the other hand, when the output of the fuel cell is small, the amount of hydrogen used decreases and the amount of exhaust heat released decreases, so the function of simultaneously releasing heat and storing hydrogen is very useful. Moreover, the heat radiation at that time can be used as heat.

  Furthermore, since it is almost unnecessary to change the output of the hydrogen supply device in accordance with the amount of hydrogen used in the fuel cell, the hydrogen supply device can be operated with a constant output.

  In addition, the said embodiment does not limit this invention at all, In the range which does not deviate from the summary, various deformation | transformation and improvement are possible.

It is the figure which showed schematic structure of the chemical thermal storage hydrogen storage apparatus which concerns on this embodiment. It is the figure which showed the operation | movement at the time of thermal storage of the chemical thermal storage hydrogen storage apparatus which concerns on this embodiment. It is the figure which showed the operation | movement at the time of thermal radiation of the chemical thermal storage hydrogen storage apparatus which concerns on this embodiment. It is the figure which showed the operation | movement at the time of the hydrogen storage of the chemical thermal storage hydrogen storage apparatus which concerns on this embodiment. It is the figure which showed the operation | movement at the time of hydrogen discharge | release of the chemical thermal storage hydrogen storage apparatus which concerns on this embodiment. It is the figure which showed the operation | movement at the time of thermal storage and hydrogen discharge | release of the chemical thermal storage hydrogen storage apparatus which concerns on this embodiment. It is the figure which showed the operation | movement at the time of thermal radiation / hydrogen storage of the chemical thermal storage hydrogen storage apparatus which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Chemical heat storage hydrogen storage apparatus 11 Fuel cell 12 Hydrogen supply apparatus 13 Hydrogen supply pipe 14 Circulation circuit 15 Heat exchanger 16 Heat utilization part 17 1st reactor 18 2nd reactor 19 1st communication pipe 20 1st heat exchanger 21 Second heat exchanger 22 Second communication pipe

Claims (3)

Used in combination with a fuel cell using as a fuel gas hydrogen supplied through a hydrogen supply pipe derived from a hydrogen supply device;
A first reactor in which an endothermic reaction A that releases hydrogen or an exothermic reaction A ^* that absorbs hydrogen, which is the reverse reaction, occurs;
A second reactor in which an exothermic reaction B that absorbs hydrogen at a temperature equal to or lower than a predetermined temperature or an endothermic reaction B ^* that releases hydrogen, which is the reverse reaction, occurs under the same pressure as the pressure in the first reactor;
A first communication pipe communicating the first reactor and the second reactor;
A first heat exchanger provided in the first reactor for exchanging heat between the first reactor and the external environment;
The heat that is provided in the second reactor and connected to a circulation circuit that circulates a heat medium fluid between the fuel cell and the second reactor, and recovers and heats exhaust heat from the fuel cell. A second heat exchanger capable of heating the inside of the container by exchanging heat with the medium fluid, and recovering heat generated by the exothermic reaction B to heat the heat medium fluid in the circulation circuit;
One end is connected to at least one of the first reactor, the second reactor, or the first communication pipe, and the other end is provided with a second communication pipe connected to the hydrogen supply pipe. Chemical heat storage hydrogen storage device.   The chemical heat storage hydrogen storage device according to claim 1, wherein the hydrogen is pure hydrogen or reformed hydrogen.   3. The chemical heat storage hydrogen storage device according to claim 1, wherein the fuel cell is a polymer electrolyte fuel cell, a phosphoric acid fuel cell, or a solid oxide fuel cell.

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