JP2009070659A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safe fuel cell system capable of effectively treating surplus hydrogen and suppressing the release of surplus hydrogen.
A plurality of unit cells each including a positive electrode that reduces oxygen, a negative electrode that oxidizes hydrogen, and a solid electrolyte membrane disposed between the positive electrode and the negative electrode, and each of the plurality of unit cells. A hydrogen supply path for supplying hydrogen to the fuel cell configured by connecting at least a part of the plurality of unit cells in series or in parallel, and a hydrogen supply apparatus connected to the fuel cell, Hydrogen removal means for removing at least part of the hydrogen in the hydrogen supply path, and hydrogen removal by the hydrogen removal means based on a detection signal from the detection means for detecting the hydrogen supply amount in the hydrogen supply device And control means for controlling.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell system using hydrogen as a fuel.

  In recent years, with the widespread use of cordless portable electronic devices such as personal computers and mobile phones, batteries that are power sources are increasingly required to be smaller and have higher capacities. Currently, lithium ion secondary batteries have been put into practical use as batteries that have high energy density and can be reduced in size and weight, and demand for portable power sources is increasing. However, this lithium ion secondary battery has a limit in output capacity, and there is a problem that a sufficient continuous use time cannot be guaranteed for some portable electronic devices.

  In order to solve such problems, development of fuel cells such as solid polymer fuel cells has been underway. The fuel cell can be used continuously if fuel and oxygen are supplied. For example, a polymer electrolyte membrane fuel cell (PEMFC) is a hydrogen ion conductive polymer electrolyte membrane as an electrolyte membrane layer, a catalyst layer disposed on both sides thereof, and further on both sides thereof. It has a plurality of unit cells, each of which is an electrode / electrolyte integrated body (MEA) composed of a porous electrode base material that is a gas diffusion layer.

  Here, hydrogen used as fuel for PEMFC has a lower limit of the combustion limit (explosion limit) of a mixed gas of air under normal temperature and normal pressure of 4.0 vol%. Be careful especially when handling indoors. Cost. For this reason, in small fuel cells that are being developed as next-generation power sources for portable electronic devices, surplus hydrogen that does not contribute to power generation reaction among hydrogen supplied to the fuel cell system also from the viewpoint of the combustion limit described above It is necessary to sufficiently suppress excessive discharge and leakage.

  On the other hand, current fuel cells have a problem of lifetime due to deterioration of the positive electrode and the negative electrode, which is one of the issues for practical application. That is, due to hydrogen remaining in the fuel cell when power supply to the external load is stopped, the positive electrode and the negative electrode are deteriorated due to the growth of the catalyst particles of the positive electrode and the negative electrode and the oxidation reaction of the carbon powder supporting the catalyst particles. It is. There are various theories about the mechanism of the deterioration of the positive electrode and the negative electrode, but since the open circuit voltage of each MEA is close to 1 V due to hydrogen in the battery, the electrode surface area is reduced due to coarsening of catalyst particles in the positive electrode. It is speculated that oxidation of the carbon powder occurs and a combustion reaction of hydrogen and leaking oxygen occurs in the negative electrode, resulting in coarsening of the catalyst particles and oxidation of the carbon powder as in the positive electrode.

  By the way, as a method for producing hydrogen which is a fuel source of a fuel cell, a method of generating hydrogen by chemically reacting water and a hydrogen-generating substance such as aluminum, magnesium, silicon, or zinc is known. For example, a method has been proposed in which an exothermic reaction between water and a hydrogen generating substance is utilized, and the exothermic reaction can be stably maintained by controlling the water to be supplied. Either one or both of the hydrogen generating substance and water is proposed. It is known that the reaction is facilitated by heating (Patent Document 1).

Further, a method has been proposed in which a processing fuel cell for consuming surplus hydrogen discharged from an output fuel cell is disposed separately from the output fuel cell (Patent Document 2).
JP 2007-45646 A JP 2007-80721 A

  However, in the method of generating hydrogen by chemically reacting a hydrogen generating substance and water as described in Patent Document 1, for example, the hydrogen generation rate is significantly increased in the initial stage of supplying water to the hydrogen generating substance. Thus, a large amount of generated hydrogen is discharged out of the path as surplus hydrogen until the fuel cell system stably generates power to an external load. As described above, when an excessive amount of hydrogen is supplied at one time, even if a mechanism for processing surplus hydrogen as shown in Patent Document 2 is provided, surplus hydrogen can be sufficiently processed. Without being able to do so, it will be discharged out of the path of the fuel cell system.

  Further, even when the fuel cell system is stopped, in the method of generating hydrogen by chemically reacting the hydrogen generating substance and water as described in Patent Document 1, the inflow of hydrogen from the hydrogen supply source to the fuel cell As a result, the supply of hydrogen from the hydrogen supply source into the fuel cell continues, and as a result, the unit cell of the fuel cell is exposed to hydrogen, resulting in deterioration of the electrodes described above. Will go on.

  The present invention has been made in view of such a problem, and in a fuel cell system, surplus hydrogen supplied as fuel is effectively processed, and particularly when the fuel cell system is started, stopped or restarted. It is an object of the present invention to provide a safe fuel cell system that can suppress discharge of surplus hydrogen when an excessive amount of hydrogen is supplied.

  In order to solve the above problems, a fuel cell system according to the present invention includes a plurality of positive electrodes that reduce oxygen, a negative electrode that oxidizes hydrogen, and a solid electrolyte membrane disposed between the positive electrode and the negative electrode. A unit cell, and a fuel cell that includes a hydrogen supply path for supplying hydrogen to each of the plurality of unit cells, and is configured by connecting at least a part of the plurality of unit cells in series or in parallel; A detection signal from a detection means for detecting a hydrogen supply amount in the hydrogen supply apparatus, comprising: a hydrogen supply apparatus connected to the fuel cell; and a hydrogen removal means for removing at least part of the hydrogen in the hydrogen supply path. And a control means for controlling the hydrogen removal in the hydrogen removing means.

  According to the present invention, surplus hydrogen in the fuel supply path can be effectively removed even when the amount of hydrogen supplied from the hydrogen supply device becomes excessive. Can be provided.

  As described above, in the fuel cell system according to the present invention, a plurality of unit cells having a positive electrode for reducing oxygen, a negative electrode for oxidizing hydrogen, and a solid electrolyte membrane disposed between the positive electrode and the negative electrode. And a fuel cell comprising a hydrogen supply path for supplying hydrogen to each of the plurality of unit cells, wherein at least a part of the plurality of unit cells is connected in series or in parallel, and the fuel A hydrogen supply device connected to the battery; and a hydrogen removal means for removing at least a portion of the hydrogen in the hydrogen supply path, based on a detection signal from a detection means for detecting a hydrogen supply amount in the hydrogen supply device And a control means for controlling the hydrogen removal in the hydrogen removal means.

  As a result, hydrogen discharged from the fuel cell system can be reduced.

  Further, it is preferable that the hydrogen removal by the hydrogen removing means is performed at the start of the supply of hydrogen from the hydrogen supply device.

  By doing in this way, since the operation | movement of a hydrogen supply apparatus is not stabilized, the removal of surplus hydrogen at the time of the hydrogen supply start which tends to become unstable in the amount of supply hydrogen can be performed effectively.

  Moreover, it is preferable that the hydrogen removal apparatus as the hydrogen removal means is disposed in the fuel supply path between the hydrogen supply apparatus and the fuel cell.

  By doing in this way, the amount of hydrogen supplied to a fuel cell from a hydrogen supply device can be made appropriate.

  Furthermore, it is preferable that the hydrogen removing device includes a positive electrode that reduces oxygen, a negative electrode that oxidizes hydrogen, and a solid electrolyte membrane disposed between the positive electrode and the negative electrode.

  By doing in this way, surplus hydrogen can be processed safely and reliably with the same structure as the unit cell in a fuel cell.

  Furthermore, it is preferable that the plurality of unit cells of the fuel cell are configured such that the positive electrode and the negative electrode can be electrically connected, and each of the plurality of unit cells of the fuel cell functions as a hydrogen removing unit. .

  By doing in this way, it is possible to remove excess hydrogen using the configuration of the fuel cell without adding hydrogen removing means, and it is possible to treat excess hydrogen in the fuel cell.

  The hydrogen supply device preferably supplies water to the hydrogen generating material accommodated in the hydrogen generating container and reacts the hydrogen generating material with the water to generate hydrogen.

  By doing in this way, the stable hydrogen supply to a fuel cell can be performed using the method which can generate | occur | produce hydrogen easily.

  Furthermore, it is preferable that the detection means for detecting the hydrogen supply amount in the hydrogen supply device detects the temperature of the hydrogen generation container. In this case, when the temperature of the hydrogen generation vessel is 60 ° C. to 120 ° C., it is preferable to stop at least part of the hydrogen removal in the hydrogen removal means, and in particular, the temperature of the hydrogen generation vessel is 80 ° C. When the temperature is ˜110 ° C., it is preferable to stop at least part of the hydrogen removal by the hydrogen removal means. Further, when the differential (d (T) / d (t)) value per unit time (t) of the temperature (T) of the hydrogen generation container becomes 0.5 or less, the hydrogen in the hydrogen removing means It is preferred to stop at least part of the removal.

  In addition, it is preferable that the hydrogen removal by the hydrogen removing unit is performed even after the supply of hydrogen from the hydrogen supply device is stopped.

Embodiments of a fuel cell system according to the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 shows a schematic configuration diagram of a fuel cell system according to a first embodiment of the present invention. As shown in FIG. 1, the fuel cell system according to the first embodiment of the present invention includes a fuel cell 1 having a plurality of unit cells 100 electrically connected in series, and fuel for the fuel cell 1. A hydrogen supply device 2 that supplies hydrogen, and a hydrogen removal device 3 that is a hydrogen removal means provided in a hydrogen supply path 7 between the hydrogen supply device 2 and the fuel cell 1 are provided.

  Therefore, after the hydrogen generated by the hydrogen supply device 2 is removed by the hydrogen removal device 3, the hydrogen is supplied to the negative electrode of the unit cell 100 constituting the fuel cell 1 through the hydrogen supply path 7. Then, surplus hydrogen in the fuel cell 100 is released from the exhaust path 8.

  Further, in the fuel cell system according to this embodiment shown in FIG. 1, a stop valve 6 is provided between the hydrogen supply device 2 and the hydrogen removal device 3, and this stop valve 6 is closed when the fuel cell system is stopped. As a result, hydrogen is not supplied to the fuel cell 1 thereafter. However, this stop valve 6 is not essential in the fuel cell system according to the present invention, and can be omitted as appropriate.

  The hydrogen supply device 2 is provided with detection means 9 for detecting the hydrogen supply amount, and a detection signal from the detection means 9 is given to the control means 4. The control means 4 which is an information processing apparatus such as a microcomputer controls the operation of the hydrogen removal apparatus 3 based on the detection signal from the detection means 9. The control means 4 in the present embodiment also performs control of the stop valve 6 and control of electric output to the external load 5 connected to the fuel cell 1.

  Next, the detailed structure of each device constituting the fuel cell system according to the present embodiment will be described with reference to FIGS.

  FIG. 2 is a schematic diagram showing a cross section of the main configuration of the fuel cell 1 in the fuel cell system according to the present embodiment. FIG. 2 shows a state in which three unit cells 100 are combined to form one fuel cell 1, but this is only an example, and the unit cell 100 in the fuel cell as one unit is shown. The number is not limited to three, and it is needless to say that a single fuel cell 1 can be formed by connecting a plurality of unit fuel cells composed of a plurality of unit cells 100.

  In the fuel cell 1 according to the present embodiment shown in FIG. 2, the positive electrode composed of the positive electrode diffusion layer 21 and the positive electrode catalyst layer 23, the solid electrolyte membrane 25, and the negative electrode composed of the negative electrode diffusion layer 22 and the negative electrode catalyst layer 24 are The unit cells 100 are sequentially stacked to form three unit cells 100 arranged in a plane.

  On the positive electrode side of each unit cell 100, positive electrode current collecting plates 37a and 37b, a positive electrode insulating plate 33, and a positive electrode panel plate 31 are sequentially arranged. Further, negative electrode current collecting plates 38a and 38b, a negative electrode insulating plate 34, and a negative electrode panel plate 32 are sequentially arranged on the negative electrode side of each unit cell 100.

  The three unit cells 100 are sandwiched and integrated with the positive electrode panel plate 31 and the negative electrode panel plate 32. Further, although not shown in FIG. 2, the adjacent unit cells 100 are connected in series by electrical connection between the positive electrode current collecting plates 37a and 37b and the negative electrode current collecting plates 38a and 38b.

  The positive electrode current collecting plates 37a and 37b, the positive electrode insulating plate 33, and the positive electrode panel plate 31 are provided with a plurality of oxygen introduction holes for introducing oxygen in the air outside the fuel cell 1 into the positive electrode. Then, the positive electrode diffusion layer 21 of the unit cell 100 is formed from the outer surface of the positive electrode panel plate 31 by the oxygen introduction holes of the positive electrode current collecting plates 37a and 37b, the oxygen introduction hole of the positive electrode insulating plate 33, and the oxygen introduction hole of the positive electrode panel plate 31. A plurality of positive electrode side openings 41 are formed so that oxygen in the air is supplied from the positive electrode side openings 41 to the positive electrode diffusion layer 21 by diffusion.

  Further, in the fuel cell 1 according to the present embodiment shown in FIG. 2, hydrogen as fuel in the fuel tank portion 40 is introduced into the negative electrode current collector plates 38 a and 38 b, the negative electrode insulating plate 34 and the negative electrode panel plate 32. For this purpose, a plurality of hydrogen introduction holes are provided. Then, the hydrogen introduction hole of the negative electrode current collecting plates 38a and 38b, the hydrogen introduction hole of the negative electrode insulating plate 34, and the hydrogen introduction hole of the negative electrode panel plate 32 are provided from the surface of the negative electrode panel plate 32 on the fuel tank portion 40 side. A plurality of negative electrode side openings 42 that reach the negative electrode diffusion layer 22 are formed, and hydrogen that is fuel in the fuel tank section 40 is supplied to the negative electrode diffusion layer 22 from these negative electrode side openings 42. ing.

  In the fuel cell 1 according to the present embodiment, the positive electrode panel plate 31 and the negative electrode panel plate 32, and further the fuel tank portion 40 are integrally fixed by screws 43 and nuts 44. Note that 39a and 39b in FIG. 2 are seals.

  The positive electrode diffusion layer 21 and the negative electrode diffusion layer 22 are made of a porous electron conductive material or the like, for example, a porous carbon sheet subjected to a water repellent treatment. A carbon powder containing fluororesin particles (such as PTFE resin particles) is formed on the catalyst layer side of the positive electrode diffusion layer 21 and the negative electrode diffusion layer 22 for the purpose of further improving water repellency and improving the contact property with the catalyst layer. In some cases, the paste is applied.

  The positive electrode catalyst layer 23 has a function of reducing oxygen diffused through the positive electrode diffusion layer 21 and contains, for example, a carbon powder carrying a catalyst (catalyst carrying carbon powder) and a proton conductive material. is doing. Moreover, you may further contain the resin binder as needed.

  The catalyst contained in the positive electrode catalyst layer 23 is not particularly limited as long as it can reduce oxygen. For example, platinum fine particles can be used. The catalyst may be fine particles composed of an alloy of platinum and at least one metal element selected from the group consisting of iron, nickel, cobalt, tin, ruthenium and gold.

As the carbon powder as the catalyst carrier, for example, carbon black having a BET specific surface area of 10 to 2000 m ² / g and an average particle diameter of 20 to 100 nm is used. The catalyst can be supported on the carbon powder by, for example, a colloid method.

  As a content ratio of carbon powder and a catalyst, it is preferable that a catalyst is 5-400 mass parts with respect to 100 mass parts of carbon powder, for example. With such a content ratio, the positive electrode catalyst layer 23 having sufficient catalytic activity can be configured. In addition, for example, when the catalyst-supported carbon powder is produced by a method of depositing the catalyst on the carbon powder (for example, a colloid method), the catalyst diameter is as long as the carbon powder and the catalyst have the above content ratio. Sufficient catalytic activity can be obtained without becoming too large.

  The proton conductive material contained in the positive electrode catalyst layer 23 is not particularly limited. For example, a resin having a sulfonic acid group such as a polyperfluorosulfonic acid resin, a sulfonated polyether sulfonic acid resin, or a sulfonated polyimide resin is used. Can be used. Specific examples of the polyperfluorosulfonic acid resin include “Nafion (registered trademark)” manufactured by DuPont, “Flemion (registered trademark)” manufactured by Asahi Glass, and “Aciplex (trade name) manufactured by Asahi Kasei Kogyo Co., Ltd. Or the like.

  And it is preferable that content of the proton conductive material in the positive electrode catalyst layer 23 is 2-200 mass parts with respect to 100 mass parts of catalyst carrying | support carbon powder. When the proton conductive material is contained in the above amount, sufficient proton conductivity is obtained in the positive electrode catalyst layer, and the electric resistance value does not become too large, and a fuel cell with good battery performance can be obtained.

  The binder used for the positive electrode catalyst layer 23 is not particularly limited, and examples thereof include PTFE, PFA, FEP, tetrafluoroethylene-ethylene copolymer (E / TFE), polyvinylidene fluoride (PVDF), and poly Fluoropolymers such as chlorotrifluoroethylene (PCTFE), polyethylene, polypropylene, nylon, polystyrene, polyester, ionomer, butyl rubber, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, and ethylene / acrylic acid copolymer Non-fluororesin such as can be used.

  The binder content in the positive electrode catalyst layer 23 is preferably 0.01 to 100 parts by mass with respect to 100 parts by mass of the catalyst-supporting carbon powder. If the binder is contained in the above-mentioned amount, sufficient binding property can be obtained for the positive electrode catalyst layer, and the electric resistance value does not become too large, and a fuel cell with good battery performance can be obtained.

  Next, the negative electrode catalyst layer 24 has a function of oxidizing hydrogen as a fuel diffused through the negative electrode diffusion layer 22. The negative electrode catalyst layer 24 contains, for example, carbon powder carrying a catalyst (catalyst carrying carbon powder) and a proton conductive material. If necessary, a binder such as a resin may be further contained.

  The catalyst used for the negative electrode catalyst layer 24 is not particularly limited as long as it can oxidize hydrogen. For example, the above-described catalysts exemplified as the catalyst used for the positive electrode catalyst layer 23 can be used. As the carbon powder, proton conductive material, and binder used for the negative electrode catalyst layer 24, the above-described materials exemplified as the carbon powder, proton conductive material, and binder used for the positive electrode catalyst layer 23 can be used.

  The solid electrolyte membrane 25 is not particularly limited as long as it is a membrane made of a material that can transport protons and does not exhibit electronic conductivity. As a material that can constitute the solid electrolyte membrane 25, for example, polyperfluorosulfonic acid resin, specifically, "Nafion (registered trademark)" manufactured by DuPont, "Flemion (registered trademark)" manufactured by Asahi Glass, Examples include “Aciplex (trade name)” manufactured by Asahi Kasei Corporation. In addition, sulfonated polyether sulfonic acid resin, sulfonated polyimide resin, sulfuric acid-doped polybenzimidazole, and the like can also be used as the material of the solid electrolyte membrane 25.

  Next, a specific configuration of the hydrogen supply device 2 in the fuel cell system according to the present embodiment will be described with reference to FIG. FIG. 3 is a block configuration diagram showing the configuration of the hydrogen supply device 2 according to the present embodiment.

  Note that the hydrogen supply device according to the present embodiment shown in FIG. 3 has a structure in which water is continuously or intermittently supplied to the hydrogen generating substance and hydrogen is generated by reacting the hydrogen generating substance and water. Shows things.

  The hydrogen supply device 2 according to the present embodiment includes a hydrogen generating substance storage container 51 that stores a hydrogen generating substance 53 and a water storage container 52 that stores water 54. Water 54 is supplied from the container 52, and the hydrogen generating material 53 and the water 54 are reacted to generate hydrogen. For this reason, the hydrogen generating substance storage container 51 also serves as a hydrogen generating container that is a reaction container for the hydrogen generating substance 53 and the water 54. Hydrogen generated in the hydrogen generating substance storage container 51 is supplied to the hydrogen removing device 3 through the hydrogen outlet pipes 57 and 59, and further supplied to the fuel cell 1 through the hydrogen supply path 7. Note that a stop valve 6 is provided in the hydrogen outlet pipe 59.

  A water supply pipe 56 that supplies water 54 from the water storage container 52 to the hydrogen generating substance storage container 51 is provided with a water supply pump 56. The water 54 stored in the water storage container 52 may be neutral water, an acidic aqueous solution, an alkaline aqueous solution, or the like, and a suitable one according to the reactivity with the hydrogen generating substance 53 to be used. Just choose.

  The hydrogen generating substance storage container 51 and the water storage container 52 may be detachable. As a result, when the hydrogen generating material 53 in the hydrogen generating material container 51 is completely consumed or when the water 54 in the water container 52 runs out, these are removed and the hydrogen generating material filled with the hydrogen generating material 53 is generated. By newly attaching the substance container 51 and the water container 52 filled with water 54, hydrogen production can be performed again.

  The hydrogen generating material 53 stored in the hydrogen generating material storage container 51 is not particularly limited as long as it can generate hydrogen by reacting with water 54 at a low temperature of 120 ° C. or lower. For example, metals such as aluminum, silicon, zinc, and magnesium, alloys mainly composed of one or more elements of aluminum, silicon, zinc, and magnesium, and metal hydrides can be preferably used.

  Here, in the case of using an alloy mainly composed of one or more elements of aluminum, silicon, zinc and magnesium, elements other than each element of the main alloy are not particularly limited. Here, the “main body” means that 80% by mass or more, more preferably 90% by mass or more is contained with respect to the entire alloy. These metals such as aluminum, silicon, zinc, and magnesium, and alloys mainly composed of one or more elements of aluminum, silicon, zinc, and magnesium are difficult to react with water at room temperature. It is a substance that facilitates exothermic reaction with water. In addition, normal temperature shall show the temperature of the range of 20-30 degreeC.

  Here, the reaction between the hydrogen generating substance and water will be described in detail. For example, in the case of aluminum and water, the reaction for producing hydrogen and oxidation products is as follows:

2Al + 6H ₂ O → Al ₂ O ₃ .3H ₂ O + 3H ₂ (1)
2Al + 4H ₂ O → Al ₂ O ₃ .H ₂ O + 3H ₂ (2)
2Al + 3H ₂ O → Al ₂ O ₃ + 3H ₂ (3)
In addition, the hydrogen generating material made of the metal or alloy described above is stabilized by forming an oxide film on the surface. For this reason, it is preferable to make the particle size of the hydrogen generating material as small as possible and increase the reaction area. For example, the form of the hydrogen generating substance is preferably in the form of particles or flakes having a particle diameter of 0.1 to 100 μm, and the particle diameter is more preferably 0.1 to 50 μm. This is because hydrogen generation occurs smoothly when the particle size of the hydrogen generating substance is 100 μm or less. Further, when the particle size of the hydrogen generating material is reduced, the hydrogen generation rate is increased. However, when the particle size is smaller than 0.1 μm, the flammability is increased and the handling becomes difficult. Moreover, since the bulk density is reduced, the filling density of the hydrogen generating material is lowered, and the energy density is likely to be lowered. For this reason, it is preferable that the particle size of the hydrogen generating substance is 0.1 μm or more.

  Here, the particle diameter of the hydrogen generating material is an average particle diameter, and means a value of the particle diameter at a volume-based integrated fraction of 50%. As a method for measuring the average particle diameter, for example, a laser diffraction / scattering method or the like can be used. Specifically, this is a particle diameter distribution measurement method using a scattering intensity distribution detected by irradiating a measurement target substance dispersed in a liquid phase such as water with laser light. As a particle size distribution measuring apparatus using a laser diffraction / scattering method, for example, “Microtrac HRA (product name)” manufactured by Nikkiso Co., Ltd. can be used.

  Examples of the metal hydride that can be used as the hydrogen generating substance include sodium borohydride and potassium borohydride. These metal hydrides are relatively stable in an aqueous alkali solution, but when a catalyst is present, they can rapidly react with water to generate hydrogen. As the catalyst, for example, metals such as Pt and Ni, acids, and the like can be used.

  For example, in the case of sodium borohydride, it can react as the following formula to generate hydrogen.

NaBH ₄ + 2H ₂ O → NaBO ₂ + 4H ₂ (4)
In addition, as the hydrogen generating substance, those exemplified above may be used alone or in combination of two or more.

  In addition, by using the above hydrogen generating material together with a heat generating material that generates heat by reacting with water (a material other than the hydrogen generating material), even if low temperature (for example, about 5 ° C.) water is supplied, The temperature in the reaction system can be increased by exotherm, and rapid hydrogen generation can be enabled.

  The exothermic substance that generates heat by reacting with water is, for example, calcium oxide, magnesium oxide, calcium chloride, magnesium chloride, calcium sulfate, etc. Examples include exothermic alkali metal or alkaline earth metal oxides, chlorides, and sulfuric acid compounds. In addition, those that generate hydrogen by reaction with water, such as metal hydrides such as sodium borohydride, potassium borohydride, and lithium hydride, can be used as a hydrogen generating substance as described above. However, it can also be used as a heat generating material when the metal or alloy described above is used as a hydrogen generating material.

  For example, a heat-generating substance that reacts with oxygen and generates heat, such as iron powder, is also known. However, when iron powder is used as the exothermic substance, oxygen must be introduced during the reaction, and it occurs when the hydrogen generating substance and the exothermic substance are arranged in the same reaction vessel as described above. Problems such as reduction in the purity of hydrogen and reduction in the amount of hydrogen generated due to oxidation of the hydrogen generating substance by oxygen are likely to occur. Therefore, as the exothermic substance, a material that generates heat by reacting with water is preferably used.

  In particular, when a metal such as aluminum, silicon, zinc, and magnesium or an alloy mainly composed of one or more elements selected from aluminum, silicon, zinc, and magnesium is used as the hydrogen generating material, the heat generating material is used. It is preferable to use together. On the other hand, when the metal hydride is used as a hydrogen generating substance, hydrogen can be produced at a relatively good rate without using the exothermic substance. May be increased.

  When the hydrogen generating substance and the exothermic substance are used in combination, the amount of the hydrogen generating substance is preferably 85% by mass or more in a total of 100 mass% of the hydrogen generating substance and the exothermic substance introduced into the hydrogen generating substance storage container. . If the amount of hydrogen generating substance in the total of the hydrogen generating substance and the exothermic substance is too small, the amount of hydrogen generated may decrease, or if the amount of exothermic substance is too large, the heat generation may become intense and the hydrogen generation reaction may be difficult to control. There is.

  The exothermic material described above may be put into the hydrogen generating material container 51 as a mixture that is uniformly or non-uniformly mixed with the hydrogen generating material 53, or may be put into the hydrogen generating material container 51 separately from the hydrogen generating material 53. Good. In the latter case, for example, it is preferable to dispose the exothermic material in the vicinity of the mouth portion of the water supply pipe 55 that supplies the water 54 to the hydrogen generating material storage container 51. By arranging the exothermic material in this way, the inside of the reaction system can be heated more efficiently.

  The material and shape of the hydrogen generating substance storage container 51 are not particularly limited as long as it can store the hydrogen generating substance 53 that generates hydrogen. However, the water 54 and hydrogen are not supplied from the water 54 supply port and the hydrogen outlet port. Materials and shapes that do not leak are preferred. As a specific material of the container, a material that does not easily transmit water 54 and hydrogen and that does not break even when heated to about 120 ° C. is preferable. For example, a metal such as aluminum or iron, or a resin such as polyethylene or polypropylene Can be used. Further, as the shape of the container, a prismatic shape, a cylindrical shape or the like can be adopted.

  There is no restriction | limiting in particular about the water storage container 52, For example, the tank etc. which accommodate the water 54 used for the conventional hydrogen supply apparatus are employable.

  The water 54 in the water storage container 52 is supplied to the hydrogen generating substance storage container 51 through the water supply pipe 55, thereby reacting with the hydrogen generating substance 53 in the hydrogen generating substance storage container 51 to generate hydrogen. In some cases, unreacted water present in the hydrogen generating substance storage container 51 is mixed into the generated hydrogen, and the mixture thereof is discharged out of the hydrogen supply device 2 through the hydrogen outlet pipe 57.

  Therefore, as shown in FIG. 3, the hydrogen supply device 2 according to the present embodiment is provided with a condensate separator 58 in front of the hydrogen outlet pipe 59 that supplies hydrogen to the fuel cell 1 and the hydrogen removal device 3. ing. The condensed water separator 58 is connected to the hydrogen generating substance storage container 51 through a hydrogen outlet pipe 57, and a hydrogen outlet pipe 59 is attached thereto. The water in the mixture with the hydrogen discharged from the hydrogen generating substance storage container 51 is cooled in the hydrogen outlet pipe 57 to become condensed water. When the hydrogen accompanying the condensed water is introduced into the condensed water separator 58, the condensed water falls to the lower part of the condensed water separator 58 and is separated by gravity.

  Then, as shown in FIG. 3, the water separated by the condensed water separator 58 is recovered in the water storage container 52 by connecting the condensed water separator 58 and the water storage container 52 by the water recovery pipe 61. be able to. Thus, by collecting the water separated by the condensate separator 58, it becomes possible to reduce the substantial supply amount of water used for hydrogen generation, and to make the water container 52 more compact. be able to.

  In the specific example shown in FIG. 3, the flocculated water separator has been described as a part of the hydrogen supply apparatus. However, the present invention is not limited to this, and the flocculated water separator may be used outside the hydrogen supply apparatus. Moreover, since the coagulated water separator itself is not necessarily required, its adoption may be appropriately determined as necessary.

  Next, a specific configuration of the hydrogen removal apparatus 3 that is a hydrogen removal means in the fuel cell system according to the present embodiment will be described with reference to FIG. FIG. 4 is a schematic diagram showing a main cross-sectional configuration of the hydrogen removal device 3 according to the present embodiment.

  The hydrogen removal apparatus shown in FIG. 4 is configured by a cell 70 having the same structure as the unit cell 100 of the fuel cell 1 in which the positive electrode and the negative electrode can be conducted. That is, the cell 70 includes a positive electrode catalyst layer 73 that reduces oxygen and a negative electrode catalyst layer 74 that oxidizes hydrogen, and further includes a solid electrolyte membrane 75 between the positive electrode catalyst layer 73 and the negative electrode catalyst layer 74. ing. Further, the surface of the positive electrode catalyst layer 73 opposite to the solid electrolyte membrane 75 side has a laminated positive electrode diffusion layer 71, and the surface of the negative electrode catalyst layer 74 opposite to the solid electrolyte membrane 75 side. Has a negative electrode diffusion layer 72 laminated. These can be made of the same material as the unit cell 100 of the fuel cell 1 described in FIG.

  The cell 70 is sandwiched between a positive electrode current collector plate 81 disposed above the positive electrode diffusion layer 71 and a negative electrode current collector plate 82 disposed below the negative electrode diffusion layer 72. The negative electrode current collector plate 82 is fixed by a bolt 91 and a nut 92, for example. Reference numeral 85 denotes a sealing material made of silicon rubber or the like, and 86 denotes a fuel tank portion to which hydrogen is supplied.

  The hydrogen removal device 3 in the present embodiment is connected to the hydrogen supply device 2 via a hydrogen outlet pipe 59 and is connected to the fuel cell 1 via a hydrogen supply path 7. Note that a stop valve 6 is provided in the hydrogen outlet pipe 59.

  The positive electrode current collector plate 81 and the negative electrode current collector plate 82 are made of, for example, a noble metal such as platinum or gold, a corrosion-resistant metal such as stainless steel, or carbon. In addition, the surface may be plated or painted to improve the corrosion resistance.

  A plurality of air holes 83 are formed in the positive electrode current collector plate 81, and oxygen in the atmosphere is supplied to the positive electrode of the cell 70 through the air holes 83. On the other hand, a plurality of hydrogen introduction holes 84 are formed in the negative electrode current collector plate 82, and hydrogen introduced from the hydrogen outlet pipe 59 to the fuel tank portion 86 is supplied to the negative electrode of the cell 70 through these hydrogen introduction holes 84. .

  A positive electrode lead wire 87 is connected to the end portion of the positive electrode current collector plate 83, and a negative electrode lead wire 88 is connected to the end portion of the negative electrode current collector plate 82. These lead wires 87 and 88 are connected via a resistor 89 and a switch 90. When the hydrogen removal device 3 is operated, the hydrogen removal device 3 removes hydrogen from the positive electrode and the negative electrode of the cell 70 by turning on the switch 90 by a control signal from the control unit 4 (not shown). Hydrogen supplied into the apparatus 3 can be consumed. As a result, it is possible to remove excess hydrogen from the hydrogen removal device 3 to the fuel cell 1 via the hydrogen supply path 7.

  In the hydrogen removal apparatus 3 according to the present embodiment shown in FIG. 4, the example in which the positive electrode and the negative electrode of the cell 70 are connected via the resistor 89 has been shown. What is necessary is just to use what has resistance value that the time required for the voltage between the positive electrode-negative electrode of the cell 70 to be 0.1V or less after the start is within 1 minute. Further, the resistor 89 is not necessarily required. If the voltage between the positive electrode and the negative electrode of the cell 70 can be lowered to 0.1 V or less in the same time without using the resistor, the positive electrode of the cell 70 The negative electrode may be connected by a lead body or the like only through a switch without using a resistor so as to be conductive.

  Next, the flow of the hydrogen removal operation in the fuel cell system according to the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing a hydrogen removal operation in the fuel cell system according to the present embodiment. Here, when the fuel cell system is activated, that is, when hydrogen supply from the hydrogen supply device is started, excess hydrogen is removed. Explain the removal status.

  In the present embodiment, a case will be described in which the hydrogen supply device 2 is a type that supplies water to the hydrogen generating material as shown in FIG. 3 using a water supply pump. Note that a temperature sensor that can detect the temperature of the hydrogen generation container is used as the detection means 9 that detects the hydrogen supply amount in the hydrogen supply device 2.

  As shown in the flowchart of FIG. 5, when the fuel cell system is activated, the water supply pump of the hydrogen supply device is turned on in step S1, and water is supplied to the hydrogen generating material to start generation of hydrogen. At the same time, a temperature sensor, which is a detecting means for grasping the hydrogen supply amount, is also turned on.

  In the next step S2, the control means determines whether or not a hydrogen removal operation is necessary from temperature information from the temperature sensor.

  For example, when the temperature of the hydrogen generation container of the hydrogen supply device is sufficiently high, such as when the fuel cell system has been operating a while ago, excessive hydrogen supply is not performed, so There is no need for removal. In such a case, the operation of the fuel cell system can be started without removing the hydrogen as it is.

  On the other hand, when the fuel cell system has stopped operating for a while and the temperature of the hydrogen generation container of the hydrogen supply device has dropped to about room temperature, hydrogen is suddenly generated by the supply of water and the hydrogen supply amount is reduced. It tends to be excessive. In such a case, the control means determines that hydrogen removal is necessary, and turns on the hydrogen removal apparatus in the next step S3. For example, in the hydrogen removal apparatus shown in FIG. 4, the switch 90 is turned on.

  In subsequent step S4, for example, the control means repeatedly monitors the temperature of the temperature sensor at predetermined time intervals, and determines whether the temperature of the hydrogen generation container has reached the predetermined temperature.

  Then, when the temperature reaches a temperature at which hydrogen generation becomes stable, it is determined that hydrogen removal is unnecessary, and in the next step S5, the hydrogen removal apparatus is turned off. In the example of FIG. 4, the switch 90 is turned off.

  Thereafter, hydrogen is stably supplied until the fuel cell system is stopped.

  In addition, since the fuel cell system in this embodiment removes surplus hydrogen with a hydrogen removal apparatus according to the above-mentioned steps, hydrogen supply to the fuel cell can be stably performed from the start. For this reason, excess hydrogen can be effectively prevented from being discharged from the exhaust path 8. Note that the electric output of the fuel cell system is supplied to the external load from the time when the hydrogen reaches the unit cells 100 of the fuel cell 1 and the output of the fuel cell is stabilized.

  In the above description, an example is shown in which the hydrogen supply amount in the hydrogen supply apparatus is related to the temperature of the hydrogen generation container using the temperature sensor. In this case, it is necessary to examine in advance the correlation between the amount of hydrogen generated from the start of the reaction between the hydrogen generating substance and water and the temperature of the hydrogen generating container.

  For example, the amount of hydrogen supply is grasped by the temperature of the hydrogen generation container itself, as in the case where the hydrogen generation amount is stable when the surface temperature of the hydrogen generation container is 60 ° C. to 120 ° C., more preferably 80 ° C. to 110 ° C. A case where the operation of the hydrogen removal apparatus is controlled can be considered.

  Further, by detecting the temperature change per unit time of the hydrogen generation container in the control device, it is detected that the hydrogen generation process in the hydrogen generation container has become stable. For example, the surface temperature (T) of the hydrogen generation container A control method is also conceivable in which the hydrogen removal device is turned off when the derivative (d (T) / d (t)) per unit time (t) is 0.5 or less. In this way, when grasping the hydrogen generation amount by the differential amount per unit time, the Savitzky-Golay method, the adjacent average method, Noise removal techniques such as FFT smoothing can be used.

  In addition, although it changes also with the magnitude | sizes of a fuel cell system, it is desirable to turn off a hydrogen removal apparatus within 10 minutes. Since it is rare that the time required for hydrogen production to stabilize exceeds 10 minutes, when the hydrogen removal apparatus is operated for a long time of 10 minutes or more, the production amount is stabilized, that is, the fuel cell. There is a possibility that hydrogen in a state where almost no discharge from the battery occurs is wasted. Therefore, in the control program for the hydrogen removal apparatus in the control means, it is also effective to perform control to turn off the operation of the hydrogen removal apparatus based on the hydrogen removal time.

  In addition, the position where the temperature sensor for monitoring the surface temperature of the hydrogen generation container of the hydrogen supply device can be accurately detected, regardless of whether it is inside or outside the container. It can also be installed in part of the supply pipe. In any case, the position of the temperature sensor is preferably a position where the temperature of the hydrogen generation container can be measured without being influenced by the external temperature. For example, the outer bottom of the hydrogen generation container or the outer surface near the bottom is desirable. .

  The temperature sensor to be used is not particularly limited as long as it can accurately measure the temperature of the hydrogen generation vessel. For example, a contact sensor such as a platinum resistance thermometer, thermistor, thermocouple, IC temperature sensor, A non-contact sensor such as a radiation thermometer that detects heat can be used. In particular, a thermistor or a thermocouple is preferably used as a small sensor having high sensitivity.

In the fuel cell system according to this embodiment, the hydrogen removal device 3 is also connected when the connection with the external negative load 5 is turned off, that is, when the power generation from the fuel cell 1 to the external load 5 is stopped. To work. Thus, by turning off the connection with the external load and operating the hydrogen removal device 3 even after the electrical output from the fuel cell 1 is stopped, the hydrogen supply device 2 in particular at the initial stage of hydrogen generation is transferred to the fuel cell 1. When the hydrogen supply continues, or when hydrogen leaks into the fuel cell 1 even if the stop valve 6 stops the hydrogen supply, the hydrogen removal device 3 removes the hydrogen flowing into the fuel cell 1. It becomes possible.
(Embodiment 2)
Next, a second embodiment of the fuel cell system according to the present invention will be described with reference to the drawings.

  FIG. 6 is a schematic configuration diagram showing a second embodiment of the fuel cell system according to the present invention. The fuel cell 1 includes a plurality of unit cells 100 electrically connected in series. A hydrogen supply device 2 that supplies hydrogen as a fuel, and a hydrogen removal device 3 that is a hydrogen removal means provided in a hydrogen supply path 7 between the hydrogen supply device 2 and the fuel cell 1. The basic configuration is the same as that of the fuel cell system according to the first embodiment of the present invention shown in FIG. For this reason, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The fuel cell system according to the present embodiment is different from the fuel cell system according to the first embodiment in that the positive and negative electrodes of each unit cell 100 of the fuel cell 1 can be electrically connected. It is a point that has been. Specifically, in the structure shown in FIG. 6, a series connection body 10 of a switch and a resistor is provided between the positive electrode and the negative electrode of each unit cell 100. Further, a control signal is sent from the control means 4 to the switch of the serial connection body 10 provided in each unit cell 100 so that the operation can be controlled.

  In the present embodiment, since the positive electrode and the negative electrode of each unit cell 100 of the fuel cell 1 can be made conductive as described above, it is possible to remove surplus hydrogen in each unit cell 100. 100 can be utilized as part of the hydrogen removal means. For this reason, when a large amount of surplus hydrogen is generated, such as when the fuel cell system is started up, and the hydrogen removal device 3 alone is not sufficient as the surplus hydrogen removal capability, the amount of hydrogen removal is increased and the surplus hydrogen is removed from the system. Emission can be effectively prevented.

  Here, the hydrogen removal operation in the second embodiment of the fuel cell system according to the present invention will be described with reference to FIG. FIG. 7 is a flowchart showing the hydrogen removal operation in the fuel cell system according to the present embodiment. When the fuel cell system is started up, as in the operation of the fuel cell system according to the first embodiment shown in FIG. That is, the situation of the removal of surplus hydrogen performed at the start of the supply of hydrogen from the hydrogen supply device will be described.

  In this case, the hydrogen supply device 2 is a type that supplies water to the hydrogen generating substance as shown in FIG. 3 using a water supply pump, and a detection means 9 for detecting the hydrogen supply amount in the hydrogen supply device 2. As in FIG. 5, the temperature sensor that can detect the temperature of the hydrogen generation container is used.

  As shown in FIG. 7, when the fuel cell system is activated, the water supply pump of the hydrogen supply device is turned on in step S11, and water is supplied to the hydrogen generating material to generate hydrogen. At the same time, a temperature sensor, which is a detecting means for grasping the hydrogen supply amount, is also turned on.

  In the next step S12, the control means determines whether or not a hydrogen removal operation is necessary from temperature information from the temperature sensor.

  For example, when the temperature of the hydrogen generation container of the hydrogen supply device is sufficiently high, such as when the fuel cell system has been operating a while ago, excessive hydrogen supply is not performed, so There is no need for removal. In such a case, the operation of the fuel cell system can be started without removing the hydrogen as it is.

  On the other hand, when the fuel cell system has stopped operating for a while and the temperature of the hydrogen generation container of the hydrogen supply device has dropped to about room temperature, hydrogen is suddenly generated by the supply of water and the hydrogen supply amount is reduced. It tends to be excessive. In such a case, the control means determines that hydrogen removal is necessary, and turns on the hydrogen removal apparatus in the next step S13. For example, in the hydrogen removal apparatus shown in FIG. 4, the switch 90 is turned on.

  In subsequent step S14, the control means determines whether or not further hydrogen removal is necessary in addition to the hydrogen removal by the hydrogen removal device, based on the temperature information from the temperature sensor. For example, a large amount of surplus hydrogen is generated depending on conditions such as the type and amount of the hydrogen generating material in the hydrogen generator, or when the hydrogen removing capability of the hydrogen removing device 3 is insufficient for the entire fuel cell system. In some cases, further hydrogen removal may be required.

  When the control means 4 determines that further hydrogen removal is necessary, in the next step S15, the positive electrode and the negative electrode of each unit cell 100 for power generation of the fuel cell 1 are brought into conduction, and the unit cell 100 becomes a hydrogen removal means. Function as. Specifically, the switch of the serial connection body 10 shown in FIG. 6 is turned on.

  On the other hand, if it is determined that further hydrogen removal is unnecessary and hydrogen removal using only the hydrogen removal device 3 is sufficient, the process proceeds to step S18.

  In the next step S16, for example, the control unit repeatedly monitors the temperature of the temperature sensor at a predetermined time interval, and determines whether or not the temperature of the hydrogen generation container has reached a temperature at which further hydrogen removal can be canceled. To do. Then, when the generation of hydrogen is slightly stabilized and further hydrogen removal is unnecessary, in the next step S17, the continuity between the positive electrode and the negative electrode in the unit cell 100 of the fuel cell 1 is released. As a result, the unit cell 100 of the fuel cell 1 exhibits the original power generation function, and excess hydrogen is removed only by the hydrogen removal device 3.

    In the next step S18, for example, the control means repeatedly monitors the temperature of the temperature sensor at a predetermined time interval, and determines whether the temperature of the hydrogen generation vessel is stable and unnecessary hydrogen removal is unnecessary. If the generation of hydrogen is stable and the removal of surplus hydrogen is no longer necessary, in the next step S19, the hydrogen removal device 3 is turned off and the operation is stopped. In the case of the hydrogen removal apparatus 3 shown in FIG. 4, the switch 90 is turned off.

  Thereafter, hydrogen is stably supplied until the fuel cell system is stopped.

  The operation in the case of the fuel cell system according to the present embodiment will be specifically described. For example, when the temperature of the hydrogen generation container is from room temperature to about 35 ° C., the positive electrode and the negative electrode in each cell 100 of the fuel cell 1 are electrically connected. Thus, further hydrogen removal is performed using the unit cell 100 as a hydrogen removal means, and for example, the surplus hydrogen is removed only by the hydrogen removal device 3 until the temperature of the hydrogen generation container reaches 35 ° C. to 70 ° C. Such an operation can be considered.

  In addition, when the hydrogen supply amount is grasped not by the temperature of the hydrogen generation container itself but by the temperature change in a predetermined time, the differential of the surface temperature (T) of the hydrogen generation container per unit time (t) (d (T ) / D (t)), when the value is 1 or more, further hydrogen removal is performed using the unit cell 100 as a hydrogen removal means, and the hydrogen removal is performed while the differential value is between 1 and 0.5. Control such as removal of excess hydrogen in the apparatus 3 can be considered.

  Further, in the fuel cell system according to the present embodiment, the fact that the unit cell 100 in the fuel cell 1 can be switched from that for power generation and can be used for the removal of surplus hydrogen is utilized, and then the power generation in the fuel cell is stopped. It can also be used to remove excess hydrogen.

  That is, when the fuel power system is stopped, even if the supply of new hydrogen from the hydrogen generator to the fuel cell is completely stopped, hydrogen remains in the fuel cell and the external load is disconnected from the fuel cell. Thereafter, this becomes a cause of deterioration of the positive electrode and the negative electrode of the unit cell. As a result, the life of the fuel cell is impaired. On the other hand, in the fuel cell system of this embodiment, since the positive electrode and the negative electrode of the unit cell for power generation can be made conductive, even if hydrogen remains in the fuel cell, it can be consumed, Residual hydrogen in the fuel cell can be completely removed. For this reason, the above-described deterioration of the positive electrode and the negative electrode due to residual hydrogen can be avoided, and the life of the fuel cell can be extended.

  In the fuel cell system according to the present embodiment shown in FIG. 6, the positive electrode and the negative electrode of each unit cell 100 of the fuel cell 1 are connected via a series connection body 10 of a resistor and a switch. As the resistance used here, for example, after the fuel cell 1 according to the fuel cell system is stopped, the time required for the voltage between the positive electrode and the negative electrode of the unit cell 100 to be 0.1 V or less is within one minute. A resistor having such a resistance value as described above may be used. Further, if the voltage between the positive electrode and the negative electrode of the unit cell 100 can be lowered as described above without using a resistor, the positive electrode and the negative electrode of the unit cell 100 are not used with a resistor. It is also possible to connect with a lead body or the like only through a switch to enable conduction.

  Next, an application example of the fuel cell system according to the present embodiment will be described with reference to FIG.

  In the application example of the fuel cell system according to the present embodiment shown in FIG. 8, the fuel cell system is supplied from the hydrogen supply device 2 between the hydrogen supply device 2 and the hydrogen removal device 3 in addition to the one shown in FIG. 6. The difference is that a monitoring device 11 capable of measuring the amount of hydrogen is arranged.

  By using such a monitoring device 11, it becomes possible to directly grasp the amount of hydrogen supplied from the hydrogen supply device 2. Therefore, in addition to the supply hydrogen amount detection means 9 such as a temperature sensor. By using this, it is possible to grasp the more accurate state of the supplied hydrogen, and it is possible to determine the removal of surplus hydrogen by the control means. For example, when the flow rate of hydrogen is detected by the monitoring device 11 in addition to the detection signal from the temperature sensor, and this flow rate does not exceed a certain threshold value (for example, 200 ml / min) for a certain period (for example, 30 seconds) or longer In this case, it is possible to perform control such as stopping the hydrogen removal operation or reducing the hydrogen removal amount.

  As a monitoring device as shown in this application example, a device that can detect the flow rate of a gas such as hydrogen that does not cause leakage can be used. For example, a digital mass flow meter that monitors the flow velocity or a digital that monitors the air supply pressure A manometer or the like can be used.

  Furthermore, by using the application example of the fuel cell system according to the present embodiment shown in FIG. 8, for example, not only the surplus hydrogen at the start and end of the fuel cell is removed, but the surplus suddenly generated during power generation It is also possible to suppress hydrogen by appropriately switching the unit cell 100 in the hydrogen removal device and the fuel cell 1 from that for power generation and using it for removing excess hydrogen.

  Although specific embodiments of the fuel cell system according to the present invention have been described above, the present invention is not limited to these specific examples. For example, the structure of the unit cell of the fuel cell shown in FIG. 2 is merely an example, and various specific forms known as a polymer electrolyte membrane fuel cell can be adopted.

  In addition, as for the hydrogen supply device, FIG. 3 is merely an example of a specific example of the hydrogen generating material and a mechanism for reacting water and the hydrogen generating material. Further, the hydrogen supply means itself is not limited to the method of reacting the hydrogen generating substance with water, and the present invention can be applied to other hydrogen supply methods. In particular, when a temporal change in hydrogen supply is likely to occur, such as a technique for extracting hydrogen from a hydrogen storage alloy, excess hydrogen in the fuel cell system can be removed by applying the present invention. Can be done effectively.

  Furthermore, the hydrogen removal apparatus is not limited to the structure shown in FIG. 4, and other methods that can remove a predetermined amount of hydrogen from the hydrogen supply path can be used.

  Moreover, although the case where the thermometer which measures the temperature of a hydrogen generation container was used as a detection means which detects the amount of hydrogen generation was demonstrated, this invention is not restricted to this, The fuel concerning 2nd Embodiment A flow meter that directly measures the flow rate of hydrogen as added in the application example in the battery system, and a method that detects hydrogen from the atmospheric pressure of a predetermined portion in the hydrogen supply device are also conceivable. In short, any means can be used as long as it can detect the amount of hydrogen to be supplied that changes as time passes from the start of the operation of the hydrogen supply device.

  Further, in the schematic configuration diagram of the fuel cell system according to the present invention shown in FIGS. 1, 6, and 8, the form in which the fuel cell 1 and the external load 5 are connected / disconnected by the switch SW is shown. Is merely conceptual, and a switch as a circuit element does not necessarily exist. By connecting and disconnecting the external load itself, it may be possible to switch on / off the power supply to the external load, or it may be assumed that the external load is always connected to the fuel cell in terms of circuit configuration.

Hereinafter, the result of having confirmed the effect concretely about the removal of the surplus hydrogen in the fuel cell system of this invention is demonstrated as an Example. In addition, the concrete structure in the following Example does not restrict | limit the content of this invention itself.
<Example 1>
[Fabrication of fuel cell]
As Example 1 for confirming the effect of the fuel cell system of the present invention, the one shown in the schematic configuration diagram of FIG. 9 was used.

  As the positive electrode and the negative electrode of the unit cell 100 shown in FIG. 9, an electrode (LT140E-W Pt amount: 0.5 mg / cm 2 manufactured by E-TEK) coated with carbon on a carbon cloth was used. Moreover, Nafion 112 (made by DuPont) was used for the solid electrolyte membrane. Each electrode was 25 mm × 92 mm, and the solid electrolyte membrane was 29 mm × 96 mm.

  As the configuration of these fuel cells 1, the one shown in FIG. 2 was used in series.

  Hereinafter, the details will be described with reference to FIG. The positive electrode panel plate 31 was made of stainless steel 304 and had a thickness of 2 mm. The positive electrode openings 41 were arranged in a total of 72 1 × 13 mm rectangular holes over the entire area corresponding to the upper part of the positive electrode diffusion layer 21 of each unit cell 100. The negative electrode panel plate 32 has the same material and shape. That is, in the negative electrode panel plate, the oxygen introduction hole related to the positive electrode panel plate is a fuel introduction hole for forming the negative electrode opening (42 in FIG. 2).

  As the positive electrode current collecting plates 37a and 37b, those having a thickness of 0.3 mm in which nickel was plated with gold were used. The negative electrode current collecting plates 38a and 38b were also made of the same material and shape.

  A positive electrode insulating plate 33 made of glass epoxy resin and having a thickness of 0.5 mm was used. The arrangement of the openings is the same as that of the positive electrode panel plate 31. The negative electrode insulating plate 34 has the same material and shape.

  The fuel tank 40 is made of glass epoxy resin and has a thickness of 3 mm. The depth inside the central tank is 2 mm.

  The seals 39a and 39b are made of silicon and have a thickness of 0.2 mm. The size of the hole formed in the portion where the electrode is accommodated was set to 26 m × 93 mm.

As shown in FIG. 2, the above members were stacked and tightened with bolts and nuts to produce a fuel cell.
[Production of hydrogen removal equipment]
As the hydrogen removal apparatus of this example, the one configured in FIG. 4 described above was used.

  The constituent members of the cell 70 are the same as those of the unit cell 100 of the fuel cell 1. The electrode was 6 mm square, and the solid electrolyte membrane was 8 mm square.

As the positive electrode current collector plate 81, a stainless steel plate having a thickness of 2 mm obtained by gold plating was used. As the air holes 83, rectangular holes of 1 × 60 mm were arranged over the entire portion corresponding to the upper part of the positive electrode diffusion layer 71 of each cell 70 as shown in FIG. 4. The negative electrode current collector plate 82 has the same shape and material.
The tank portion 86 made of glass epoxy resin and having a thickness of 3 mm was used. The depth inside the central tank is 2 mm.

  The seal 85 is made of silicon rubber and has a thickness of 0.2 mm. The size of the hole formed in the portion where the electrode is accommodated was 61 mm square.

As shown in FIG. 4, the above members were stacked and tightened with bolts and nuts to produce a hydrogen removal apparatus. Further, a positive electrode lead wire 87 and an anode lead wire 88 were arranged at the end portion of the positive electrode current collector plate 81 and the end portion of the negative electrode current collector plate 82, respectively, and a switch 90 and a 20 mΩ resistor 89 were connected therebetween.
[Production of hydrogen supply device]
As the hydrogen supply apparatus of this example, the one configured in FIG. 3 described above was used.

As the hydrogen generating substance storage container 51, a polypropylene prismatic container having an internal volume of 50 cm ³ was used. As the water supply pipe 55, the hydrogen lead-out pipes 57 and 59, and the water recovery pipe 61, polypropylene pipes having an inner diameter of 2 mm and an outer diameter of 3 mm were used. The hydrogen generating substance storage container 51 was filled with 12.3 g of aluminum powder having an average particle diameter of 3 μm as a hydrogen generating substance and 1.6 g of calcium oxide as a heat generating substance. A polypropylene prismatic container having an internal volume of 50 cm ³ was used as the water storage container 52, and 30 g of water was filled therein. As the condensate separator 58, a polypropylene prismatic container having an internal volume of 30 cm ³ was used.
[Assembly of fuel cell system]
In the fuel cell system described above, the fuel cell 1, the hydrogen removal device 3, and the hydrogen supply device 2 are arranged as shown in FIG.
[Power generation test]
Water in the water storage container 52 is supplied to the hydrogen generating substance storage container 51 by the water supply pump 56 to generate hydrogen, and the power generation test of the fuel cell 1 is performed at a constant voltage of 4.0 V for 1 hour by the external load 5. It was. Moreover, the surplus gas discharged | emitted from the ventilation | gas_flow path 8 was measured with the monitoring apparatus 12 (KOFLOC company made mass flow 8100) from a fuel cell system starting to a stop.
[Flow velocity monitoring]
The switches provided on the lead bodies connecting the positive electrode and the negative electrode of each unit cell 100 of the monitoring device 12, the hydrogen removal device 3, and the fuel cell 1 were turned on. Next, simultaneously with the activation of the water supply pump 56 of the hydrogen supply device 2, the surface temperature of the hydrogen generating substance container 51 is monitored by the temperature sensor 9, and the temperature T = 105 ° C., the differential value per unit second of the temperature. When T ′ = 0.2, conduction between the hydrogen removal device 3 and the individual unit cells 100 of the fuel cell 1 was released, and power generation was started. At this time, the time from the start of the water supply pump 56 to the start of power generation was 3 minutes.

When the operation was stopped, the external load 5 was disconnected and the water supply by the water supply pump 56 was stopped. At the same time, the switch 90 provided on the lead body connecting the positive electrode and the negative electrode of each unit cell 100 of the fuel cell 1 and the switch 90 of the monitoring device 12 and the hydrogen removing device 3 was turned on. The test was performed at room temperature of 25 ° C.
<Comparative Example 1>
In the fuel cell system similar to that of the first embodiment, except that the lead body connecting between the positive electrode and the negative electrode of each unit cell 100 of the hydrogen removal device 3 and the fuel cell 1 is not conducted at the start-up before power generation, the embodiment 1 was performed.
<Comparative example 2>
In the same fuel cell system as in the first embodiment, when the operation is stopped, the lead body connecting between the positive electrode and the negative electrode of each unit cell 100 of the hydrogen removal device 3 and the fuel cell 1 is not conducted, and is the same as in the first embodiment. I went.
[Result of effect measurement experiment]
FIG. 10 shows the change over time in the two-time average value T2 ′ of the surface temperature T of each hydrogen generating substance storage container 51 and the differential value T ′ of the temperature in Example 1 and Comparative Example 1. Here, the differential value T2 ′ was averaged twice for adjacent values for leveling. FIG. 11 shows the change over time in the integrated amount of discharged hydrogen in Example 1 and Comparative Example 1 during 10 minutes from the start of the water supply pump 56. In addition, in FIG. 11, each integrated amount (integrated value) is shown by the relative ratio (%) when the exhausted hydrogen integrated amount of the comparative example 1 1 hour after the electric power generation start is set to 100. FIG.

  Further, FIG. 12 shows the change over time in the integrated amount of hydrogen discharged after stopping power generation to the external load 5 of the fuel cell system and the total voltage value of the fuel cell 1 in Example 1 and Comparative Example 2. In FIG. 12, each integrated amount (integrated value) is shown as a relative ratio (%) when the integrated amount of discharged hydrogen in Comparative Example 2 12 minutes after the stop of power generation is taken as 100.

  From the results of FIG. 10, the surface temperature of the hydrogen generating substance storage container 51 tends to increase in both Example 1 and Comparative Example 1. However, from the results of FIG. It can be seen that exhaust hydrogen is significantly suppressed by simultaneously bringing the positive electrode and the negative electrode of each unit cell 100 of the hydrogen removal device 3 and the fuel cell 1 into conduction.

  Further, in Example 1 of FIG. 12, compared with Comparative Example 2, when the power generation is stopped, the positive electrode and the negative electrode of each unit cell 100 of the hydrogen removal device 3 and the fuel cell 1 are made conductive at the same time. Hydrogen is greatly suppressed, and in Example 1, residual hydrogen is removed by the resistance of the series connection body 10 of each unit cell 100 inside the fuel cell 1, and hydrogen leaked from the hydrogen supply device 2 is removed. The output voltage from the fuel cell 1 can be quickly reduced by removing it quickly with the hydrogen removing device 3.

  From these results, in the fuel cell system of Example 1 in which the positive electrode and the negative electrode of the unit cells 100 of the hydrogen removal device 3 and the fuel cell 1 are simultaneously brought into the conductive state at the initial stage, a large amount generated when the operation of the fuel cell system is disclosed. It can be seen that both the removal of excess hydrogen and the removal of excess hydrogen remaining after power generation stop in the fuel cell 1 can be effectively performed.

  From the above results, it is considered that by using the present invention, a safe and stable power generation environment can be provided by significantly suppressing and suppressing deterioration of discharged hydrogen during power generation and stop of the fuel cell.

  The fuel cell system of the present invention can be suitably used even in indoor use because it can suppress the discharge of hydrogen gas out of the path at the start of operation of the fuel cell. Further, if the hydrogen removing means is operated even when the operation is stopped, it is possible to effectively suppress the deterioration of the battery life due to the deterioration of the positive electrode and the negative electrode of the fuel cell, and it is a relatively simple mechanism. Is easy. Therefore, the fuel cell system of the present invention can be preferably used for various uses to which a conventional fuel cell is applied, including a power supply for a high-performance portable electronic device.

1 is a schematic diagram showing a schematic configuration of a fuel cell system according to a first embodiment of the present invention. It is a schematic diagram which shows the cross-sectional structure of the fuel cell in the fuel cell system concerning the 1st Embodiment of this invention. It is a schematic diagram which shows the structural example of the hydrogen supply apparatus in the fuel cell system concerning the 1st Embodiment of this invention. It is a schematic diagram which shows the cross-sectional structure of the hydrogen removal apparatus in the fuel cell system concerning the 1st Embodiment of this invention. It is a flowchart which shows the operation | movement of the excess hydrogen removal in the fuel cell system concerning the 1st Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system concerning the 2nd Embodiment of this invention. It is a flowchart which shows the operation | movement of the excess hydrogen removal in the fuel cell system concerning the 2nd Embodiment of this invention. It is a schematic diagram which shows schematic structure about the application example of the fuel cell system concerning the 2nd Embodiment of this invention. It is a schematic diagram which shows schematic structure of the Example of the fuel cell system concerning this invention. It is a graph which shows the temperature change of the hydrogen generation container in the Example and comparative example of the fuel cell system concerning this invention. It is a graph which shows the hydrogen discharge | emission amount outside the path | route in the Example and comparative example of the fuel cell system concerning this invention. It is a graph which shows the change of the hydrogen discharge | emission amount and output voltage after the fuel cell stop in the Example and comparative example of the fuel cell system concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Hydrogen supply apparatus 3 Hydrogen removal apparatus 4 Control means 5 External load 100 Unit cell

Claims (11)

A plurality of unit cells each having a positive electrode for reducing oxygen, a negative electrode for oxidizing hydrogen, and a solid electrolyte membrane disposed between the positive electrode and the negative electrode, and supplying hydrogen to each of the plurality of unit cells A fuel cell configured to connect at least a part of the plurality of unit cells in series or in parallel,
A hydrogen supply device connected to the fuel cell;
Hydrogen removing means for removing at least part of the hydrogen in the hydrogen supply path,
A fuel cell system comprising control means for controlling hydrogen removal in the hydrogen removal means based on a detection signal from a detection means for detecting a hydrogen supply amount in the hydrogen supply device.   The fuel cell system according to claim 1, wherein the hydrogen removal by the hydrogen removing means is performed at the start of hydrogen supply from the hydrogen supply device.   3. The fuel cell system according to claim 1, wherein a hydrogen removing device as the hydrogen removing unit is disposed in the hydrogen supply path between the hydrogen supply device and the fuel cell.   4. The fuel cell system according to claim 3, wherein the hydrogen removing device includes a positive electrode that reduces oxygen, a negative electrode that oxidizes hydrogen, and a solid electrolyte membrane disposed between the positive electrode and the negative electrode.   5. The fuel cell according to claim 3, wherein the plurality of unit cells of the fuel cell are configured so that the positive electrode and the negative electrode can conduct, and each of the plurality of unit cells of the fuel cell functions as a hydrogen removing unit. The fuel cell system described.   The hydrogen supply device supplies water to a hydrogen generating substance accommodated in a hydrogen generating container, and reacts the hydrogen generating substance with the water to generate hydrogen. The fuel cell system according to any one of claims.   The fuel cell system according to claim 6, wherein the detection means for detecting the hydrogen supply amount in the hydrogen supply device detects the temperature of the hydrogen generation container.   8. The fuel cell system according to claim 7, wherein when the temperature of the hydrogen generation container is 60 ° C. to 120 ° C., at least a part of hydrogen removal by the hydrogen removal means is stopped.   9. The fuel cell system according to claim 8, wherein when the temperature of the hydrogen generation container is 80 ° C. to 110 ° C., at least a part of the hydrogen removal in the hydrogen removal means is stopped.   When the differential (d (T) / d (t)) value per unit time (t) of the temperature (T) of the hydrogen generation container becomes 0.5 or less, the hydrogen removal means removes hydrogen. The fuel cell system according to claim 7, wherein at least a part of the fuel cell system is stopped.   The fuel cell system according to any one of claims 1 to 10, wherein the hydrogen removal by the hydrogen removal means is performed even after the supply of hydrogen from the hydrogen supply device is stopped.

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