JP2004281393A - Fuel cell power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simplified fuel cell power generation system supplying hydrogen generated at a hydrogen generating device to the fuel cell by utilizing a hydrogen generating medium, of which responsiveness and supplying speed of the hydrogen generating device is improved and manufacturing cost of the same is reduced. <P>SOLUTION: The fuel cell power generating device is constructed by combining the hydrogen generating device 1 equipped with a system supplying water to a reaction container 2 storing a water decomposing medium 30, and the fuel cell 11, and equipped with a reserve tank 6 for storing hydrogen between the hydrogen generating device 1 and the fuel cell 11. The hydrogen generated at the hydrogen generating device 1 is filled in the reserve tank 6, and supplied to the fuel cell 11 therefrom. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell power generation system, and more particularly to a fuel cell power generation system including a hydrogen generator for refueling a fuel cell mounted on a vehicle, and a control method of the fuel cell power generation system.

  Various substances such as hydrogen, methane, methanol, and gasoline have been studied as fuels for fuel cells, and hydrogen is considered to be the most ideal fuel. The advantages of hydrogen include that the exhaust gas is clean, that the electrode reaction proceeds easily, that a reformer is not required, that there are few technical problems, and the like. For this reason, hydrogen generation and storage technologies are very important technologies for fuel cell systems, especially fuel cells for automobiles, and are being studied from various angles such as cost, portability, safety, and future potential. . Particularly, from the viewpoint of the world energy situation and the protection of the global environment, fuel cells for automobiles have been studied from an early stage, and the storage and supply of hydrogen has been taken up as an important issue. Table 1 summarizes the conventional hydrogen storage technologies.

  The method shown in Table 1 will be specifically described. When a hydrogen storage alloy is used, high-pressure hydrogen is required to store hydrogen, and a hydrogen production apparatus and a high-pressure facility for that purpose are required. Further, the hydrogen storage alloy has a low weight efficiency and has a problem in the circulation life (several hundred times).

  When hydrogen is produced by reforming methanol or gasoline, equipment such as a reformer and CO converter is required, CO cannot be completely removed (<10ppm), and the hydrogen generation efficiency of the on-board reformer It is not always advantageous because it has problems such as low temperature and time required to raise the temperature of the reformer.

  Although the method of mounting high-pressure hydrogen is relatively simple, there are concerns about the limitation of the container volume and the danger of gas leakage. In particular, when liquid hydrogen is loaded, there is a problem of energy consumption for liquefying the hydrogen and a problem that the filled liquid hydrogen has only a few days, so that it is considered that it is not suitable for use in personal vehicles.

  In the case of chemical hydride, studies are currently being conducted using an organic compound of benzene or decalin as a medium. However, there is a problem of outflow of gaseous chemical hydride due to an accident or the like, and there is a concern about the effect on the environment. Although there is a method using a borohydride compound, there are problems of medium regeneration, problems of technical complexity, and problems of using an alkaline solution.

  Recently, hydrogen storage using carbon nanotubes has also been studied, but carbon nanotubes have a problem that the specific gravity is small and the volume of the tank to be filled is large, and the hydrogen storage capacity is not sufficiently increased with respect to the manufacturing cost. .

  The method currently used among the above hydrogen storage methods is a method using a high-pressure hydrogen tank. However, in this method, since hydrogen is stored in a state of a high-pressure gas, not only the storage place is strictly regulated, but also the danger of being mounted on a vehicle has been pointed out.

In view of the problems of these hydrogen storage methods, a hydrogen medium using iron oxide has recently been studied. This has been studied as a medium for storing original hydrogen obtained by decomposing hydrocarbons such as CH _4, it is found to have the ability to decompose water into iron powder to generate hydrogen, the hydrogen generating medium It has been proposed to use it as. For example, WO 01/96233 A1 (Patent Document 1) and WO 02/081368 A1 (Patent Document 2) propose a hydrogen generating medium using iron or an iron-based alloy. However, these documents describe a method for supplying hydrogen to a hydrogen generating medium or a fuel cell, but do not describe anything about the configuration of a hydrogen supply system.

WO 01/96233 A1 publication WO 02/081368 A1 Publication

  2. Description of the Related Art In a fuel cell power generation system that supplies hydrogen generated by a hydrogen generator using a hydrogen generating medium such as iron to a fuel cell to generate power, the supply amount of hydrogen is constantly changed according to a change in load of the fuel cell. Must be adjusted to the amount required for supply. In conjunction with this, it is necessary to adjust heating (or cooling) for maintaining the temperature, supply of steam, and the like. In order to operate such a system, the responsiveness of the hydrogen generator (the time from when the hydrogen supply command is issued until the actual supply of hydrogen) and the maximum hydrogen generation capacity (maximum per unit time) It is necessary to considerably increase the amount of generated hydrogen.

  Accordingly, an object of the present invention is to improve the hydrogen supply responsiveness and the supply speed of a hydrogen generator in a system for supplying hydrogen generated by a hydrogen generator using a hydrogen generating medium to a fuel cell, and to reduce the cost of the hydrogen generator. And to provide a simplified fuel cell power generation system.

  From the viewpoint of simplifying the control of the hydrogen generator, improving the hydrogen supply response, optimizing the reaction conditions, and improving the energy use efficiency, the hydrogen generator is continuously operated at a temperature and a hydrogen generation amount as stable as possible. In addition, the fuel cell must be constantly supplied with the required amount of hydrogen. As a result of intensive studies in view of such a purpose, the present inventors have found that (a) installing a reserve tank for temporarily filling hydrogen between the hydrogen generator and the fuel cell, or (b) By storing the generated hydrogen in the reaction vessel using a hydrogenation reaction vessel and promoting the hydrogen generation reaction under pressure, it is possible to supply hydrogen constantly even if the hydrogen consumption rate changes And found the present invention.

  That is, the first fuel cell power generation system according to the present invention is a combination of a hydrogen generator having a mechanism for supplying water to a reaction vessel containing a water splitting medium and a fuel cell, and the hydrogen generator A reserve tank for storing hydrogen between the fuel cell and the fuel cell, filling the reserve tank with hydrogen generated by the hydrogen generator, and supplying hydrogen to the fuel cell from the reserve tank. And

  The second fuel cell power generation system according to the present invention is a combination of a hydrogen generator having a mechanism for supplying water to a reaction vessel containing a water splitting medium, and a fuel cell, wherein the hydrogen generator The reactor is characterized in that it has a pressure resistance of 0.2 to 3 MPa (maximum operating pressure). In this fuel cell power generation system, the generated hydrogen is stored in the reaction vessel, and the hydrogen generation reaction proceeds under pressure.

  The water splitting medium preferably contains at least one element selected from the group consisting of Fe, Ni and Co. Each fuel cell power generation system includes pressure measuring means for measuring the internal pressure of the reserve tank or the reaction vessel, and water injection control means for controlling the amount of water injected into the reaction vessel based on the obtained pressure measurement value. Is preferred. As the pressure measuring means, for example, a pressure sensor can be provided in a reserve tank or a reaction vessel. As the water injection control means, a control device for adjusting the amount of water injected into the reaction container based on the internal pressure value of the reserve tank or the reaction container measured by the pressure sensor and controlling the opening and closing of the injection port can be provided. By providing the pressure measurement means and the water injection control means, the hydrogen pressure in the reserve tank or the reaction vessel can be constantly maintained within a predetermined range, and even if the load of the fuel cell changes, hydrogen that can cope with the change can be obtained. It becomes possible to supply.

  As a method of controlling the internal pressure of the reserve tank or the reaction vessel, when the internal pressure of the reserve tank or the reaction vessel becomes lower than a predetermined lower limit of the hydrogen storage pressure, water is supplied to the reaction vessel to generate hydrogen, When the internal pressure of the vessel becomes higher than a predetermined upper limit of the hydrogen storage pressure, it is preferable to stop the supply of water to the reaction vessel to stop the generation of hydrogen. By performing such control, the responsiveness of hydrogen supply to the fuel cell can be improved, and the hydrogen supply capability can be significantly improved in a short time.

  Furthermore, a humidity measuring means for measuring the humidity in the reserve tank is provided, and the internal pressure measurement value of the reserve tank is corrected using the obtained humidity measurement value, and water is supplied to the reaction vessel based on the obtained pressure correction value. By controlling the supply, the internal pressure of the reserve tank can be controlled more precisely. Similarly, by measuring the humidity in the reaction vessel, the amount of water vapor inside can be found, and excluding this, the exact amount of hydrogen can be found.

  In order to control the humidity of hydrogen supplied to the fuel cell, it is provided with humidity measuring means for measuring the humidity in a reserve tank or a reaction vessel, and a humidifying mechanism for supplying moisture to a hydrogen gas line for supplying hydrogen to the fuel cell. It is also preferable to adjust the amount of water to be supplied to the hydrogen gas line based on the measured humidity value measured by the humidity measuring means. For example, a humidity sensor is provided in the reserve tank, and water can be supplied from the humidifier to the hydrogen gas line based on the measured humidity value in the reserve tank measured by the humidity sensor. The measurement result of the humidity in the reserve tank is a basis for judging the internal state of the reaction vessel and the degree of humidification of the hydrogen supplied to the fuel cell. The amount of humidification can be determined.

  Since the first fuel cell power generation system of the present invention includes the reserve tank between the hydrogen generator and the fuel cell, it can supply hydrogen stably even when the load of the fuel cell changes. Further, by measuring the pressure in the reserve tank and controlling the supply of water vapor to the hydrogen generator, the responsiveness of hydrogen supply to the fuel cell and the hydrogen supply capability in a short time can be greatly improved. Further, in the second fuel cell power generation system of the present invention, since the reaction vessel is a pressure-resistant vessel having a maximum operating pressure of 0.2 to 3 MPa, it is possible to supply hydrogen constantly even if the consumption rate of hydrogen changes.

  The fuel cell power generation system of the present invention not only satisfies the high efficiency, high safety, and compactness required especially for a vehicle fuel cell power generation system, but also is required for starting and accelerating a vehicle. High power density and short time hydrogen supply response can be satisfied.

  A first fuel cell power generation system according to the present invention includes a hydrogen generator, a fuel cell, and a reserve tank provided between the hydrogen generator and the fuel cell for storing hydrogen. Further, the second fuel cell power generation system according to the present invention includes a pressure-resistant reaction vessel in the hydrogen generator. Hereinafter, the fuel cell power generation system will be described in detail, but the description is applicable to both the first and second fuel cell power generation systems unless otherwise specified.

  The hydrogen generator has a mechanism for supplying water to a reaction vessel containing a water splitting medium. It is preferable to use a heat-resistant metal container (for example, a container made of stainless steel (SUS) or the like) as the reaction container. The mechanism for supplying water to the reaction vessel is not particularly limited, and water may be added to the reaction vessel as a liquid or as water vapor. Further, it may be added in a state of an aerosol generated by an ultrasonic vibrator or the like. From the viewpoint of maintaining the medium temperature at a predetermined temperature or higher, it is preferable to heat the supplied water and add it as steam.

  The water splitting medium used in the present invention preferably contains at least one element selected from the group consisting of Fe, Ni and Co. Preferred examples of the water splitting medium include a medium mainly composed of a single metal of Fe, Ni or Co, or an alloy containing at least one of these elements. It is preferable to use a water-splitting medium formed into a shape such as a sphere, a column, a powder, or a porous body. When the water-splitting medium is formed into pellets, the size of the pellets is not particularly limited, but the average particle size is preferably 1 to 10 mm, more preferably 3 to 7 mm.

The reaction in which water is decomposed by the water splitting medium to generate hydrogen is represented by the following equation when, for example, Fe is used as the water splitting medium.

  FIG. 1 is a schematic diagram showing a configuration example of a first fuel cell power generation system of the present invention. The hydrogen generator 1 has a reaction vessel 2 containing a water splitting medium 30, a steam injection device 3 capable of controlling the flow rate attached to the upper part of the reaction vessel 2, and a water storage tank 14. A hydrogen outlet 13 for discharging hydrogen is provided. A pipe 26 coming out of the steam injection device 3 is connected to the water storage tank 14, and a pipe 21 coming out of the hydrogen outlet 13 is connected to the reserve tank 6. Between the hydrogen generator 1 and the reserve tank 6, it is preferable to install a compressor 7, a check valve 9, etc. for increasing the storage pressure of hydrogen for the purpose of increasing the utilization rate of the reserve tank 6. A pipe 22 is connected from the reserve tank 6 to the fuel cell 11 via the pressure reducing valve 10 so that hydrogen can be supplied to the fuel cell 11 at a constant pressure. The fuel cell 11 is not particularly limited, and known fuel cells such as a polymer electrolyte fuel cell, a phosphoric acid fuel cell, a molten carbon salt fuel cell, and a solid oxide fuel cell can be used. In particular, a polymer electrolyte fuel cell is preferably used as a fuel cell for a vehicle.

  An external heating device 4 is attached to the reaction container 2, and a temperature sensor 15 is provided in the reaction container 2, and the temperature sensor 15 is electrically connected to the temperature control device 5 via a wiring 31. The reaction temperature in the reaction vessel 2 can be measured by the temperature sensor 15. The steam injection device 3 is provided with a heating device and a flow meter (not shown). From the temperature control device 5, a pipe 25 is connected to the heating device of the steam injection device 3, and a pipe 24 is connected to the external heating device 4. The off-gas containing hydrogen discharged from the fuel electrode side of the fuel cell 11 is used for heating the reaction vessel 2 and water for generating steam to be injected into the reaction vessel 2. Therefore, a pipe 23 for supplying off-gas from the fuel cell 11 to the temperature control device 5 is provided. The temperature control device 5 adjusts the ratio of the fuel gas and the off-gas as required, and sends them to the external heating device 4 and the heating device of the steam injection device 3.

  A pressure sensor 16 for measuring hydrogen pressure is provided in the reserve tank 6, and the pressure sensor 16 is electrically connected to the water injection control device 8 via a wiring 32. In order to control the flow rate of steam injection from the steam injection device 3 and the operation of the compressor 7 based on the signal from the pressure sensor 16, between the water injection control device 8 and the steam injection device 3 and between the water injection control device 8 and the compressor 7 are electrically connected by wirings 33 and 34, respectively, so that a command from the water injection control device 8 can be transmitted.

  In the fuel cell power generation system shown in FIG. 1, water vapor is injected into the water splitting medium 30 filled in the reaction vessel 2, and the water is decomposed by the reaction between the water splitting medium 30 and water in the reaction vessel 2 to generate hydrogen. Let it. First, the fuel gas is supplied to the external heating device 4 to heat the reaction vessel 2. The reaction temperature is preferably from 200 to 400 ° C, more preferably from 250 to 350 ° C, to increase the efficiency of hydrogen generation. The fuel gas is supplied to the heating device provided in the steam injection device 3, and the water supplied from the water storage tank 14 is converted into steam by the heating device, and is injected into the reaction vessel 2 from the injection port of the steam injection device 3. In order to maintain the reaction temperature in the above range, the temperature of the steam is preferably from 200 to 400C, more preferably from 250 to 350C. Hydrogen generated by the water splitting reaction in the reaction vessel 2 is sent from the hydrogen outlet 13 to the compressor 7 through the pipe 21, and the pressure is increased by the compressor 7 and stored in the reserve tank 6.

  When storing hydrogen in the reserve tank 6, by setting the lower limit value of the hydrogen storage pressure and the upper limit value of the hydrogen storage pressure in advance, it is possible to control the amount of hydrogen (pressure) in the reserve tank 6 within the set range. preferable. Thereby, even if the load of the fuel cell changes, hydrogen corresponding to the change can be supplied. For example, the pressure value obtained by adding the minimum pressure loss of the pressure reducing valve (100 kPa) and the value larger than the pressure loss of the pipe (about 20 to 100 kPa) to the working gas pressure of the fuel cell (about 150 to 200 kPa). The lower limit value of the hydrogen storage pressure of the reserve tank 6 (approximately 270 kPa in the above values) is set, and the hydrogen pressure of the reaction vessel 2, the rated pressure of the reserve tank 6, the upper limit of the working pressure of the compressor 7, and The upper limit of the hydrogen storage pressure is set based on the operating energy efficiency of the compressor 7. The lower limit value and the upper limit value of the set hydrogen storage pressure are input to the water injection control device 8, and the internal pressure of the reserve tank 6 is controlled based on the input value.

  Specifically, the internal pressure of the reserve tank 6 is measured by a pressure sensor 16 provided in the reserve tank 6, and a pressure signal is sent to the water injection control device 8. The measured value of the internal pressure is compared with the set lower limit of the hydrogen storage pressure. If the pressure in the reserve tank 6 is lower than the set lower limit of the hydrogen storage pressure, a drive signal is sent from the water injection control device 8 to the steam injection device 3. Then, the injection port of the steam injection device 3 is opened to supply steam to the reaction vessel 2 to generate hydrogen. As the reaction proceeds in the hydrogen generator 1, the pressure in the reserve tank 6 increases. When the pressure in the reserve tank 6 becomes higher than the set upper limit of the hydrogen storage pressure, a stop signal is sent from the water injection control device 8 to the steam injection device 3, the injection port of the steam injection device 3 is closed, and the water vapor to the reaction vessel 2 is closed. Stop supplying. When the steam is injected from the steam injector 3, the flow rate of the steam may be measured by a flow meter (not shown) provided in the steam injector 3. The measured signal is sent to the water injection controller 8, and the water injection controller 8 can adjust the flow rate and ON / OFF of the water injection based on the signal.

  By controlling the supply of water to the hydrogen generator 1 based on the pressure signal from the pressure sensor 16 as described above, the hydrogen pressure in the reserve tank 6 is always maintained within a predetermined range, and the load of the fuel cell is controlled. Is changed, it is possible to supply a hydrogen fuel that can cope with the change.

  The hydrogen filled in the reserve tank 6 is constantly supplied to the fuel cell 11 through the pipe 22. At this time, the pressure is reduced by the pressure reducing valve 10 provided between the reserve tank 6 and the fuel cell 11, and hydrogen at a constant pressure is supplied to the fuel cell 11. The fuel cell 11 generates power using the supplied hydrogen and the oxidizing gas. Specifically, electrons are generated by an electrochemical reaction between hydrogen and the oxidizing gas, and the electrons are taken out to a load motor (external circuit) 12 to generate electric energy. In addition, from the viewpoint of effectively using hydrogen, off-gas (hydrogen-containing gas) discharged from the fuel electrode side of the fuel cell 11 by power generation is supplied to the temperature control device 5 through the pipe 23. A temperature signal measured by a temperature sensor 15 provided in the reaction vessel 2 is sent to a temperature control device 5, and the temperature control device 5 sends off-gas to an external heating device 4 and a steam injection device 3 of the hydrogen generator 1 based on the temperature signal. Control the amount of The external heating device 4 and the steam injection device 3 burn the off-gas together with the fuel gas, and maintain the reaction temperature in the reaction vessel 2 and the temperature of steam injected into the reaction vessel 2 within a predetermined range.

  FIG. 2 is a schematic diagram showing another configuration example of the first fuel cell power generation system of the present invention. A humidity sensor 17 for measuring the humidity of hydrogen supplied to the fuel cell 11 is provided in the reserve tank 6, and the humidity sensor 17 is electrically connected to a humidity controller 18 via a wiring 35. A gas mixer 20 is provided between the pressure reducing valve 10 and the fuel cell 11, and a humidity control device 18 is electrically connected to a humidifier 19 via a wiring 36, and a pipe for supplying water from the humidifier 19 is provided. 27 is connected to the gas mixer 20. The configuration other than the above is the same as that of the embodiment of FIG.

In a fuel cell reaction, for example, in the case of a polymer electrolyte fuel cell, hydrogen ions are generated by an anode reaction (H ₂ → 2H ⁺ + 2e ⁻ ). The generated hydrogen ions move to the cathode in the electrolyte membrane in a hydrated state. For this reason, if the electrode reaction is performed continuously, the movement of the hydrated hydrogen ions causes a shortage of water near the anode-side surface of the electrolyte membrane. The electrolyte membrane used in the polymer electrolyte fuel cell has good electric conductivity in a wet state, but when the water content is reduced, the electric resistance increases and the electrolyte membrane does not function sufficiently. For this reason, it is preferable that a humidifying mechanism is provided in the fuel cell power generation system, and the hydrogen generated by the hydrogen generator 1 is humidified on the way and then supplied to the fuel cell 11.

  The mechanism for humidifying the hydrogen is not particularly limited, and may be a known mechanism. For example, steam may be generated in the humidifier 19, and the generated steam may be added to the hydrogen supplied from the reserve tank 6 in the gas mixer 20, or a porous film may be provided in the gas mixer 20, Hydrogen may be humidified by passing the water supplied from the humidifier 19 and the hydrogen supplied from the reserve tank 6 through the porous membrane in the mixer 20.

In the example of FIG. 2, the hydrogen generated by the hydrogen generator 1 is sent to the reserve tank 6, and the humidity of the stored hydrogen is measured by the humidity sensor 17. When the signal from the humidity sensor 17 is lower than the set humidity, the humidity controller 18 sends a hydration command to the humidifier 19 so that the humidity of hydrogen supplied to the fuel cell 11 falls within a predetermined range. The humidifier 19 generates steam, sends the steam to the gas mixer 20, and mixes the steam sent from the humidifier 19 with the hydrogen sent from the reserve tank 6 by the gas mixer 20 to form a fuel cell. Supply 11 Further, by measuring the humidity in the reserve tank 6, the hydrogen pressure measurement value is corrected based on the humidity measurement value, and an accurate hydrogen pressure can be measured. By using the corrected measured value, the internal pressure of the reserve tank 6 can be controlled more precisely. Further, the hydrogen generation ability of the water splitting medium can be monitored from the measured value of the humidity of hydrogen. That is, when the reaction in the reaction vessel 2 proceeds, the water splitting medium is oxidized (for example, Fe is oxidized to Fe ₃ O ₄ ), the hydrogen generating ability of the water splitting medium is reduced, and the humidity of the generated hydrogen is increased. Therefore, it is possible to monitor the hydrogen generating ability of the water splitting medium by measuring the humidity in the reserve tank 6.

  FIG. 3 is a schematic diagram showing a configuration example of the second fuel cell power generation system of the present invention. The second fuel cell power generation system has basically the same configuration as that of the first embodiment except that a reserve tank is not provided between the hydrogen generator 1 and the fuel cell 11 and a pressure sensor 16 is provided in the reaction vessel 2. This is the same as the configuration of the first fuel cell power generation system shown in FIG. In the second fuel cell power generation system, a pressure-resistant container having a maximum operating pressure of 0.2 to 3 MPa is used as the reaction container 2 of the hydrogen generator 1. If the maximum operating pressure of the pressure vessel is less than 0.2 MPa, the storage capacity of the generated hydrogen is insufficient, and if it exceeds 3 MPa, the piping and the like must be pressure-resistant, resulting in high cost and increased weight. Connect. The lower limit of the maximum working pressure of the pressure vessel is preferably 0.5 MPa, and the upper limit is preferably 1.5 MPa. When the maximum working pressure of the pressure vessel is in the range of 0.5 to 1.5 MPa, the efficiency of the apparatus is good.

  By using a pressure-resistant container having a maximum operating pressure of 0.2 to 3 MPa, the generated hydrogen can be stored in the reaction container 2, and there is no need to install the above-mentioned reserve tank. Can be reduced. Further, by promoting the hydrogen generation reaction under pressure, the reaction efficiency can be improved as compared with normal pressure. Further, since the inside of the reaction vessel 2 is in a pressurized state, there is no need to use a compressor for extracting the generated hydrogen gas, and the hydrogen supply system is simplified. Of course, a reserve tank can be provided in this configuration to store a larger amount of hydrogen.

  The reaction vessel 2 controls the hydrogen amount (pressure) within a set range by setting a lower limit value and an upper limit value of the hydrogen storage pressure in advance. The internal pressure of the reaction vessel 2 is measured by a pressure sensor 16 provided in the reaction vessel 2, and a pressure signal is sent to the water injection control device 8. The measured value of the internal pressure is compared with the set hydrogen storage pressure lower limit, and when the pressure in the reaction vessel 2 is lower than the set hydrogen storage pressure lower limit, a drive signal is sent from the water injection controller 8 to the steam injector 3. The water vapor is fed to the reaction vessel 2 by opening the injection port of the steam injection device 3 to generate hydrogen. As the hydrogen generation reaction proceeds, the pressure in the reaction vessel 2 increases. When the pressure in the reaction vessel 2 becomes higher than the set upper limit of the hydrogen storage pressure, a stop signal is sent from the water injection control device 8 to the steam injection device 3, the injection port of the steam injection device 3 is closed, and the water vapor to the reaction container 2 is closed. Stop supplying.

FIG. 4 shows an example in which a hydrogen permeable membrane 52 is installed in the hydrogen outlet 13 of the reaction vessel 2 in the fuel cell power generation system of the present invention. Thereby, the derivation of H ₂ O (water vapor) in the reaction vessel 2 can be blocked, and only hydrogen can be extracted. As the hydrogen permeable film 52, a Pd film, a LaNi ₅ film, or the like can be used. For example, a film in which Pd is coated on an alumina porous body by electroless plating can be used. With such a configuration, H ₂ O (steam) in the water storage tank 14 can be reliably used for the hydrogen generation reaction, and the size of the water storage tank 14 can be reduced. Also it is possible to accurately grasp the amount of added H ₂ O H ₂ O used in the hydrogen production reaction from the amount of, if water consumption degradation medium 30 (water splitting medium 30 of Fe is, Fe ₃ O ₄ ) can be detected. The method of detecting the life of the water splitting medium 30 from the consumption (addition amount) of H ₂ O has the advantages of a simpler configuration and higher detection accuracy than the method of detecting from the amount of hydrogen generated.

FIG. 5 shows a still further embodiment of the present invention, in which a pipe 21 connected to a hydrogen outlet 13 is filled with a porous body 62 for an H ₂ O trap, and a pipe 63 for flowing a refrigerant is provided around the pipe 21. The configuration is shown. In this embodiment, the H ₂ O trapping porous body 62 and the steam injection device 3 or the water storage tank 14 are connected by a pipe 64, and H ₂ O liquefied in the H ₂ O trapping porous body 62 is injected with steam. It is returned to the apparatus 3 or the water storage tank 14 and is again introduced into the reaction vessel 2 for hydrogen generation. As shown, an H ₂ O tank 65 may be provided between the H ₂ O trapping porous body 62 and the steam injection device 3 or the water storage tank 14 to store a certain amount of water. Similar effects can be obtained by installing cooling fins or other H ₂ O trap means instead of the H ₂ O trap porous body 62.

  The fuel cell power generation system of the present invention is not limited to the above example, and the components may be changed or new components may be added without impairing the object of the present invention. For example, the temperature control device 5, the water injection control device 8 and the humidity control device 18 may be integrated into a control device, or a mechanism for controlling the steam injection device 3 based on the temperature signal of the temperature sensor 15 may be added. May be.

  The present invention will be described in more detail by the following examples, but the present invention is not limited thereto.

  A hydrogen generation experiment was conducted using the fuel cell power generation system shown in FIG. This fuel cell power generation system includes a hydrogen generator 1, a reserve tank 6, and a fuel cell 11. An external heating device (gas burner) 4 is attached to the bottom of the SUS reaction vessel 2, and a steam injection device 3 combining a heater and a flow meter is attached to the top of the reaction container 2. A pipe 26 coming out of the tank is connected to the water storage tank 14. A pipe 21 is connected from the hydrogen outlet 13 to the reserve tank 6 (capacity of about 10 L) via the compressor 7 and the check valve 9, and a pipe 22 is connected from the reserve tank 6 to the fuel cell 11 via the pressure reducing valve 10. ing. A pipe 23 for supplying off-gas (hydrogen-containing gas) from the outlet of the fuel cell 11 to the temperature control device 5 is connected. A temperature sensor (thermocouple) 15 is provided in the reaction vessel 2, and based on a temperature signal from the temperature sensor 15, fuel gas supplied to a heater provided in the steam injection device 3 and an external heating device (gas burner) 4. Is provided with a temperature control device 5 for controlling the temperature. A pressure sensor 16 is provided in the reserve tank 6, and a water injection control device 8 for controlling the amount of water supplied to the reaction vessel 2 and the compressor 7 based on a pressure signal from the pressure sensor 16 is provided.

  The reaction vessel 2 in the hydrogen supply apparatus having the above configuration is filled with the water-splitting medium 30 in the form of columnar pellets having a diameter of 5 mm and a length of 5 mm made of 97 mol% of Fe and 3 mol% of Al. Was activated. First, in response to a command from the water injection control device 8, the injection port of the steam injection device 3 was opened, and steam at 200 ° C. was supplied to the reaction vessel 2 to generate hydrogen. At that time, the flow rate of the fuel gas supplied to the external heating device (gas burner) 4 was adjusted by the temperature control device 5 to keep the reaction temperature in the reaction vessel 2 at 340 ° C. In addition, the hydrogen-containing gas discharged from the outlet of the fuel cell 11 is returned to the temperature control device 5 and used as fuel for the heater provided in the steam injection device 3 and the external heating device (gas burner) 4 to reduce the utilization rate of hydrogen. Enhanced.

  Hydrogen generated in the reaction vessel 2 was sent to the reserve tank 6, stored in the reserve tank 6, and then supplied to the fuel cell 11 at a constant pressure via the pressure reducing valve 10. During the operation of the power generation system, the supply amount of water vapor to the reaction vessel 2 was controlled based on the value measured by the pressure sensor 16 provided in the reserve tank 6, and the internal pressure of the reserve tank 6 was maintained within a predetermined range. The responsiveness of the hydrogen supply system and the maximum supply rate in 5 seconds were measured. Table 2 shows the results. Even when the load of the fuel cell 11 was varied, good responsiveness (<1 second) and a maximum supply speed of 5 seconds (> 25 L / min) were exhibited.

  An experiment of hydrogen generation was performed using the fuel cell power generation system shown in FIG. This fuel cell power generation system is the same as the fuel cell power generation system of the first embodiment except that a humidity sensor 17, a humidity controller 18, a humidifier 19, and a gas mixer 20 are newly provided. In the same manner as in Example 1, the power generation system was operated by combining the hydrogen supply system and the fuel cell. At this time, the humidity of the hydrogen in the reserve tank 6 (capacity: about 10 L) is measured by the humidity sensor 17, and the humidity controller 18 instructs the humidifier 19 based on the obtained humidity signal. Steam was delivered to the mixer 20. Thereby, the humidity of hydrogen supplied to the fuel cell 11 was adjusted to a predetermined range. FIG. 6 shows a temporal change of the humidity of hydrogen generated by the hydrogen generator 1. From FIG. 6, it can be seen that the humidity of hydrogen increases with the progress of the reaction, and the oxidation of the water splitting medium 30 progresses with time. Therefore, it is understood that the hydrogen generation ability of the water splitting medium 30 can be monitored by measuring the humidity in the reserve tank 6.

  An experiment on hydrogen generation was performed using the fuel cell power generation system shown in FIG. This fuel cell power generation system has basically the same configuration as the fuel cell power generation system shown in FIG. 1 except that a reserve tank is not provided and a pressure sensor 16 is provided in a pressure-resistant reaction vessel 2.

  An external heating device (gas burner) 4 is attached to the bottom of the pressure-resistant reaction vessel 2, and a steam injection device 3, which is a combination of a heater and a flow meter, is attached to the top of the reaction container 2. A pipe 26 is connected to the water storage tank 14. A pipe 28 is connected from the hydrogen outlet 13 to the fuel cell 11 via the check valve 9 and the pressure reducing valve 10. A pipe 23 for supplying off-gas (hydrogen-containing gas) from the outlet of the fuel cell to the temperature control device 5 is connected. A temperature sensor 15 and a pressure sensor 16 are provided in the reaction vessel 2, and fuel gas and off-gas are supplied to a heater provided in the steam injection device 3 and an external heating device (gas burner) 4 based on a temperature signal from the temperature sensor 15. A temperature control device 5 for supplying is provided. Further, a water injection control device 8 for controlling the amount of steam injected by the steam injection device 3 based on the pressure signal from the pressure sensor 16 is provided.

  Using this fuel cell power generation system, hydrogen was generated under the same conditions as in Example 1 except that the reaction temperature in the pressure-resistant reaction vessel 2 was maintained at 340 ° C. and the internal pressure was maintained at 0.5 MPa. As a result, a hydrogen supply response and a maximum supply rate almost equivalent to those in Example 1 were obtained.

Comparative Example 1
An experiment on hydrogen generation was performed using the fuel cell power generation system shown in FIG. However, in this example, the reaction vessel 2 was not used as a pressure-resistant vessel, and its internal pressure was maintained at almost normal pressure (0.10 to 0.15 MPa). The reaction vessel 2 was filled with a 5 mm × 5 mm diameter cylindrical pellet water-splitting medium composed of 97 mol% of Fe and 3 mol% of Al, and the power generation system was operated as follows. First, in response to a command from the water injection control device 8, the injection port of the steam injection device 3 was opened, and steam was supplied to the reaction vessel 2 to generate hydrogen. At that time, the flow rate of the fuel gas supplied to the gas burner 4 was adjusted by the temperature control device 5 to keep the reaction temperature in the reaction vessel 2 at 340 ° C. In addition, the hydrogen-containing gas discharged from the outlet of the fuel cell was returned to the temperature control device 5 and used as a fuel for the heater and the gas burner 4 provided in the steam injection device 3 to increase the utilization rate of hydrogen. The pressure in the reaction vessel 2 was measured by the pressure sensor 16, and the amount of steam injected into the reaction vessel 2 was controlled based on the measured pressure value. Hydrogen generated in the reaction vessel 2 was supplied to the fuel cell 11 via the check valve 9 and the pressure reducing valve 10. When the load of the fuel cell was varied, the responsiveness of the hydrogen supply system took 5 seconds or more, and the maximum supply rate in 5 seconds was about 1/5 of that in Example 1. Table 2 shows the results.

FIG. 1 is a schematic diagram illustrating a configuration example of a first fuel cell power generation system. It is a schematic diagram which shows another example of a structure of a 1st fuel cell power generation system. It is a schematic diagram which shows the example of a structure of a 2nd fuel cell power generation system. FIG. 3 is a schematic diagram showing an example in which a hydrogen permeable membrane is installed at a hydrogen outlet of a reaction vessel in the fuel cell power generation system of the present invention. FIG. 4 is a schematic view showing an example in which a pipe connected to a hydrogen outlet of a reaction vessel is filled with a porous body for an H ₂ O trap in the fuel cell power generation system of the present invention. 9 is a graph showing the change over time of the humidity of hydrogen supplied to a fuel cell in Example 2.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 ... Hydrogen generator 2 ... Reaction vessel 3 ... Steam injection device 4 ... External heating device 5 ... Temperature control device 6 ... Reserve tank 7 ... Compressor 8 ... Water Injection control device 9 ・ ・ ・ Check valve
10 ・ ・ ・ Reducing valve
11 ・ ・ ・ Fuel cell
12 ・ ・ ・ Load motor
13 ・ ・ ・ Hydrogen outlet of reaction vessel
14 ・ ・ ・ Water storage tank
15 ・ ・ ・ Temperature sensor
16 ・ ・ ・ Pressure sensor
17 ・ ・ ・ Humidity sensor
18 ・ ・ ・ Humidity control device
19 ・ ・ ・ Humidifier
20 ・ ・ ・ Gas mixer
21-27 ・ ・ ・ Piping
31-35 ・ ・ ・ Wiring
52 ・ ・ ・ Hydrogen permeable membrane
62 ・ ・ ・ Porous body for H ₂ O trap
63 ・ ・ ・ Cooling piping
64 ・ ・ ・ Piping
65 ・ ・ ・ H ₂ O tank

Claims (7)

  A fuel cell power generation system combining a hydrogen generator having a mechanism for supplying water to a reaction vessel containing a water splitting medium and a fuel cell, wherein hydrogen is supplied between the hydrogen generator and the fuel cell. A fuel cell power generation system comprising a reserve tank for storing, filling the reserve tank with hydrogen generated by the hydrogen generator, and supplying hydrogen from the reserve tank to the fuel cell.   A hydrogen generating device having a mechanism for supplying water to a reaction container containing a water splitting medium, and a fuel cell power generation system combining a fuel cell, wherein the maximum operating pressure of the reaction container of the hydrogen generating device is 0.2 to A fuel cell power generation system characterized by using a 3 MPa pressure-resistant container.   3. The fuel cell power generation system according to claim 1, wherein the water splitting medium contains at least one element selected from the group consisting of Fe, Ni, and Co.   The fuel cell power generation system according to any one of claims 1 to 3, wherein a pressure measuring unit that measures an internal pressure of the reserve tank or the reaction vessel, and water to the reaction vessel based on the obtained pressure measurement value. A fuel cell power generation system comprising water injection control means for controlling an injection amount.   The fuel cell power generation system according to any one of claims 1 to 4, wherein when the internal pressure of the reserve tank or the reaction vessel becomes lower than a predetermined hydrogen storage pressure lower limit, water is supplied to the reaction vessel to generate hydrogen. When the internal pressure of the reserve tank or the reaction vessel becomes higher than a predetermined upper limit of the hydrogen storage pressure, the supply of water to the reaction vessel is stopped to stop the generation of hydrogen, whereby the inside of the reserve tank or the reaction vessel is stopped. A fuel cell power generation system characterized by controlling pressure.   The fuel cell power generation system according to any one of claims 1 to 5, further comprising: a humidity measurement unit configured to measure humidity in the reserve tank or the reaction vessel, and using the obtained humidity measurement value as the reserve tank or the reserve tank. Correcting the measured pressure value in the reaction vessel, controlling the supply of water to the reaction vessel based on the obtained pressure correction value, thereby controlling the internal pressure of the reserve tank or the reaction vessel. Fuel cell power generation system. The fuel cell power generation system according to any one of claims 1 to 6, wherein a humidity measuring means for measuring humidity in the reserve tank or the reaction vessel, and moisture in a hydrogen gas line for supplying hydrogen to the fuel cell. A humidifying mechanism for replenishing the hydrogen gas, adjusting the amount of water to be replenished to the hydrogen gas line based on the humidity measurement value measured by the humidity measuring means, and thereby controlling the humidity of hydrogen supplied to the fuel cell. Fuel cell power generation system.

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