JP2006248812A - Hydrogen generator and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a steam amount necessary for steam reforming of a fuel regardless of the operation state, to stably form hydrogen by reforming, and to stabilize the power generation performance of a fuel cell system. <P>SOLUTION: When it is determined that the steam amount necessary for reforming reaction in a reformer 10 is insufficient, the exhaust flow passage of a combustion offgas is switched by valves V1-V9 so that the combustion offgas discharged from a PSR-type reformer 20 on the regeneration side is supplied to the reformer 10 on the reforming side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydrogen generator that performs a fuel reforming reaction using a catalyst and a regeneration reaction for heating and regenerating the catalyst, and a fuel cell system including the same.

  A conventional electric vehicle is equipped with a fuel cell as a power source for driving the vehicle, and with hydrogen or a raw fuel for generating hydrogen, which is a fuel for causing the fuel cell to perform a power generation operation.

  When the hydrogen itself is mounted, the hydrogen gas is compressed and packed in a high-pressure cylinder or liquefied and filled into a tank, or mounted using a hydrogen storage alloy or a hydrogen adsorbing material. However, in the case of high-pressure filling, the volume of hydrogen is small because the container wall thickness is thick and large, but in the case of liquefied filling with liquid hydrogen, vaporization loss is unavoidable and it is very difficult to liquefy. Requires energy. Further, hydrogen storage alloys and hydrogen adsorbing materials have insufficient hydrogen storage density required for electric vehicles and the like, and it is difficult to control hydrogen storage / adsorption. In addition, when the raw fuel is installed, there is a method of obtaining hydrogen by steam reforming the fuel, but since the reforming reaction is endothermic, a separate heat source is required, and an electric heater or the like was used as the heat source. The system cannot improve the overall energy efficiency, and it is inevitable that the amount of hydrogen can be secured stably under all environmental conditions.

  The actual hydrogen supply method has not yet been technically established, but it is expected that a hydrogen supply method will be established in light of the anticipated increase in hydrogen utilization in various devices in the future. ing.

  As a technology related to the above, a fuel reformer that uses a catalyst to switch between a steam reforming reaction of fuel that is an endothermic reaction and a regeneration reaction that regenerates the catalyst temperature decreased by the steam reforming reaction can be performed repeatedly. A fuel cell system has been proposed (see, for example, Patent Document 1). In this fuel cell system, moisture in the cathode off-gas from the fuel cell is separately separated and recovered, and then the recovered moisture is supplied to the reformer as water vapor for reforming reaction.

There are some technologies related to this that are disclosed in addition to the above (for example, see Patent Documents 2 to 4). Further, as an example of a fuel cell that performs a power generation operation in a high temperature region, there is a disclosure relating to a fuel cell using a hydrogen permeable material (see, for example, Patent Document 5).
U.S. Patent No. 2004-175326 US 2003-235529 U.S. Patent No. 2004-170558 US Patent No. 2004-170559 JP 2004-146337 A

  However, in the fuel cell system described above, the flow rate of cathode offgas from the fuel cell and the amount of water in the cathode offgas increase and decrease arbitrarily depending on the operating conditions such as the load. For example, at the time of system start-up, low load, or during a transition that changes from low load to high load power generation operation, the amount of steam required for the reforming reaction cannot be satisfied, and steam reforming is not possible. Thus, the amount of hydrogen produced cannot be secured stably. In other words, the amount of generated water is small because the amount of power generation is small when the system is started up or when the load is low, and during the transition, the water demand in the reforming reaction increases as the hydrogen demand in the fuel cell increases rapidly. The demand increased rapidly, and there was a problem in constantly maintaining stable power generation operation.

  The present invention has been made in view of the above, and the amount of water vapor necessary for steam reforming of fuel regardless of the operating state (for example, at low load or load fluctuation when used as a fuel cell system). And a fuel cell that can stably perform reforming and generation of hydrogen, and a fuel cell that can exhibit stable power generation performance without depending on operating conditions such as startup, low load, or load fluctuation An object is to provide a system and to achieve the object.

  The present invention relates to a steam reforming reaction of fuel, which is an endothermic reaction, and a combustion reaction for recovering the reforming reactivity on the catalyst by recovering the catalyst temperature lowered by the steam reforming reaction (hereinafter referred to as “regeneration reaction”). In the case where the atmospheric gas generated by combustion by the regeneration reaction is used, in particular, when the water discharged from the fuel cell is used as the water vapor source necessary for the reforming reaction. The inventors have obtained knowledge that they are useful in improving the utilization efficiency of heat energy and ensuring the stable amount of water vapor required for reforming, and have been achieved based on such knowledge.

  In order to achieve the above object, a hydrogen generator according to a first aspect of the present invention comprises a catalyst, and when the reforming raw material containing fuel and water vapor is supplied, the reforming raw material is heated on the catalyst. And at least two reforming reactors that cause the combustion fuel to undergo a combustion reaction to heat the catalyst when the combustion fuel is supplied, and the reformation that has undergone a combustion reaction (regeneration reaction) And an exhaust gas supply means for supplying the exhaust gas discharged from the reactor to the reforming reactor for the reforming reaction.

  In the first invention, the amount of steam supplied to the reforming reactor that performs the reforming reaction among the plurality of reforming reactors, that is, when reforming and generating hydrogen by steam reforming the reforming raw material The exhaust gas discharged from the reforming reactor that is undergoing the regeneration reaction other than the PSR reformer that undergoes the reforming reaction is supplied to the reforming reactor that performs the reforming reaction so that the amount of water vapor required for the reforming reaction is not insufficient. As a result, the water vapor (moisture) contained in the exhaust gas is replenished, so that the reduction in reforming reactivity due to the shortage of water vapor is suppressed, and the operating state (for example, when starting up or when the fuel cell system is used) The amount of hydrogen produced by reforming can be stably secured without being influenced by the low load or the load fluctuation.

  In the hydrogen generator of the first invention, at least two fuel steam reforming reactions using heat storage and regeneration reactions for recovering the heat storage amount reduced by the steam reforming reaction can be performed alternately. A reforming reactor (hereinafter also referred to as a “PSR (Pressure swing reforming) type reformer”) is provided, and at least one of them performs a steam reforming reaction of the fuel, and at least one of the other is regenerated. The reaction is performed (hereinafter, this hydrogen generator is sometimes referred to as “PSR reformer”).

The reforming reaction according to the present invention includes the following steam reforming reaction which is an endothermic reaction and partial oxidation reaction which is an exothermic reaction.
C _n H _{2n + 2} + nH ₂ O → (2n + 1) H ₂ + nCO (1)
C _n H _{2n + 2} + (n / 2) O ₂ → (n + 1) H ₂ + nCO (2)

  For example, when there are two reforming reactors, one of them is subjected to a steam reforming reaction that is an endothermic reaction using heat storage in the reactor, and the other is allowed to perform a regeneration reaction that is an exothermic reaction, When the heat storage amount is reduced by the reforming reaction, the one is switched to the regeneration reaction by switching means for switching the reforming raw material flow path and the combustion fuel flow path to the two reforming reactors. On the other hand, the regeneration reaction is switched to the reforming reaction so that the fuel reforming is performed with the heat stored by the regeneration reaction. This eliminates the need for a separate heater and the like, and by repeating this switching, continuous hydrogen generation with high use efficiency of heat energy is possible.

  The exhaust gas supply means of the first invention includes a switching means for switching a discharge flow path of exhaust gas discharged from the reforming reactor subjected to the regeneration reaction, and the water vapor supplied to the reforming reactor to be reformed. Determining means for determining whether or not the amount of water vapor satisfies a predetermined amount, and when the determination means determines that the amount of water vapor does not satisfy the predetermined amount (amount required for the reforming reaction), a regeneration reaction is performed. And switching control means for switching the discharge flow path by the switching means so that the exhaust gas discharged from the reforming reactor is supplied to the reforming reactor for the reforming reaction. .

  It is determined whether or not the amount of steam supplied to the reforming reactor satisfies the amount necessary for steam reforming. If it is determined that the amount of steam does not satisfy the required amount, that is, the amount of steam is insufficient. In some cases, the exhaust gas from the reforming reactor that has undergone the regeneration reaction is controlled so that the exhaust gas from the reforming reactor that has undergone the regeneration reaction is supplied to the reforming reactor that undergoes the reforming reaction. Since it can suppress that it supplies excessively, the fall of the hydrogen gas density | concentration produced | generated by reforming can be suppressed effectively.

  A fuel cell system according to a second aspect of the invention comprises a hydrogen generator according to the first aspect of the invention and a fuel cell that generates electric power by supplying a hydrogen-containing gas reformed and produced by the hydrogen generator.

  As described above, the steam (water) in the exhaust gas from the reforming reactor undergoing the regeneration reaction is reformed so that the amount of steam supplied to the PSR reformer that performs the reforming reaction is not insufficient. By supplying it to the reforming reactor, the reduction in reforming reactivity can be suppressed and the amount of reformed hydrogen produced as a power generation fuel can be secured stably. Alternatively, stable power generation operation can be continuously performed without being affected by the operation state such as when the load fluctuates.

  In the second invention, it is effective to use a fuel cell including an electrolyte in which an electrolyte layer is laminated on at least one side of a hydrogen permeable metal layer. Such a fuel cell including an electrolyte in which an electrolyte layer is laminated on at least one side of a hydrogen permeable metal layer has an operating temperature range of 300 to 600 ° C. In the same region, reformed and produced hydrogen-rich gas can be supplied at the operating temperature range of the fuel cell, and the anode off-gas can be returned to the PSR reformer as it is and used for regeneration. Particularly suitable in terms of effective use of thermal energy. In addition, preheating before supply is unnecessary.

  In the present invention, as a fuel in a reforming raw material to be reformed, a hydrocarbon generally used as a fuel for obtaining a synthesis gas (particularly hydrogen) of hydrogen and carbon monoxide by a reforming reaction such as steam reforming. It can be appropriately selected from fuels (for example, methane gas, gasoline, etc.).

  According to the present invention, when a reforming reaction is performed by using a heat storage amount stored in a reformer to form a fuel cell system, reformed and generated hydrogen is supplied to the fuel cell, and the reforming that has decreased due to the reforming of the fuel. When the reforming reaction and the regeneration reaction are alternately switched so as to recover the amount of heat stored in the mass device by performing a combustion reaction (regeneration reaction) that is an exothermic reaction, Reliable efficiency of reforming and generating hydrogen from fuel and stable power generation operation without depending on the battery system, such as when the load fluctuates during a transition from a low load state to a high load state Can be constructed in a system capable of continuously performing the above.

  According to the present invention, the amount of steam necessary for steam reforming of fuel is ensured without being affected by the influence of operating conditions, for example, at the time of start-up or when it is a fuel cell system, at the time of low load or load fluctuation, A hydrogen generator that can stably perform reforming and generation of heat, and high heat utilization efficiency, and does not depend on operating conditions such as startup, low load or load fluctuation, and exhibits stable power generation performance. An obtained fuel cell system can be provided.

  Hereinafter, with reference to FIG. 1 to FIG. 7, embodiments of the fuel cell system of the present invention will be described in detail, and details of the hydrogen generator of the present invention will also be specifically described through the description.

  The fuel cell system of the present embodiment is an electric vehicle equipped with a hydrogen separation membrane fuel cell (HMFC) using an electrolyte membrane in which proton conductive ceramics are laminated on the membrane surface of a hydrogen permeable metal membrane. The hydrogen generator of the present invention is mounted, and the hydrogen generated by reforming with the hydrogen generator is supplied to the hydrogen separation membrane fuel cell as a power generation fuel to perform the power generation operation.

  Regarding the hydrogen generator, a mixed gas of gasoline and steam (or gasoline) may be discharged from the hydrogen electrode side of the fuel cell as a combustion fuel to be burned during the regeneration reaction as a reforming raw material to be reformed by a reforming reaction. In the following description, the anode off-gas (and gasoline or hydrogen gas, if necessary) is used. However, the present invention is not limited to the following embodiment.

  As shown in FIG. 1, the present embodiment is provided with a first PSR reformer 10 and a second PSR reformer 10 that are provided with a catalyst and an injection device and can be switched alternately between a reforming reaction and a regeneration reaction. The PSR reformer 1 having the PSR reformer 20 and a hydrogen separation membrane fuel cell (HMFC) 30 that performs a power generation operation using the hydrogen reformed and generated by each PSR reformer. .

  The mutual switching between the reforming reaction and the regeneration reaction in the PSR reformer 10 and the PSR reformer 20 is for supplying a mixed gas (raw material for reforming) of gasoline and steam to the PSR reformer. A flow path, a flow path for supplying anode (hydrogen electrode; the same applies below) off-gas (fuel for combustion) to the PSR reformer, and a flow for discharging the reformed hydrogen-rich gas from the PSR reformer Switching means for switching the passage and the flow path for discharging the exhaust gas from the regenerated PSR reformer, specifically, a plurality of valves (valves V1 to V9) can be controlled by the control device. It is like that.

  At one end of the first PSR reformer 10, an injection device 15 for injecting a mixed gas of gasoline and steam, which is a reforming raw material, is attached, and a valve V1 is provided via the injection device 15. The supply pipe 102 is connected at one end, and one end of a discharge pipe 105 provided with a valve V4 is further connected. In addition, an injection device 17 for injecting a mixed gas of gasoline and steam, which is a reforming raw material, is attached to one end of the second PSR reformer 20, and a valve V2 is provided via the injection device 17. Is connected at one end, and one end of a discharge pipe 104 provided with a valve V3 is further connected. Each of the other ends of the supply pipes 102 and 103 includes a mixer 117 and is connected to a fuel supply pipe 101 that mixes gasoline with water vapor and supplies a mixed gas (reforming raw material). Valves V1 to V4 are connected to each other. By automatically switching, the raw material for reforming is selectively supplied to the reforming side PSR reformer to be reformed and generated from the regeneration side PSR reformer to be regenerated. Combustion gas (hereinafter also referred to as “combustion off gas”) can be discharged.

  The other ends of the discharge pipes 104 and 105 are connected to one end of a discharge pipe 106 having a valve V5 for discharging combustion off gas to the outside. When the valve V5 is opened, the combustion off gas is discharged. In the closed state, the combustion off-gas discharged from the regeneration-side PSR reformer can be supplied to the reforming-side PSR reformer.

  An anode off gas from a hydrogen separation membrane fuel cell (hereinafter also simply referred to as “fuel cell”) 30 is injected into the other end of the first PSR reformer 10 together with gasoline, hydrogen gas, or the like as necessary. The discharge pipe 107 provided with the valve V6 and the supply pipe 110 provided with the valve V8 are connected to each other at one end. The other end of the second PSR reformer 20 is provided with an injection device 18 for injecting the anode off gas from the fuel cell 30 together with gasoline, hydrogen gas, etc. as necessary, and an exhaust equipped with a valve V7. A supply pipe 109 provided with a valve V <b> 9 is connected to one end of each of the pipe 108 and the injection device 18.

  The other ends of the discharge pipes 107 and 108 are connected to one end of a hydrogen supply pipe 111 that supplies the hydrogen-rich gas reformed and generated by the PSR reformer connected at one end to the hydrogen separation membrane fuel cell 30. At the same time, the other ends of the supply pipes 109 and 110 are supplied to the PSR reformer connected at one end, and the supply pipe 112 for supplying the anode off-gas discharged from the fuel cell 30 together with gasoline, hydrogen gas or the like as necessary. And selectively supplying anode off-gas (and gasoline or hydrogen gas, if necessary) to the regeneration-side PSR reformer by switching the valves V6 to V9, and the reforming-side PSR. The hydrogen-rich gas generated and discharged in the mold reformer can be supplied to the fuel cell 30 as a power generation fuel.

  The injectors 15 and 17 inject a mixed gas of gasoline and steam (reforming raw material) at a wide angle when the PSR reformer to which each is attached causes a reforming reaction, and the injectors 16 and 18 When the PSR reformer to which each is attached causes a regenerative reaction, anode off-gas (and gasoline or hydrogen gas, if necessary) is injected at a wide angle onto the catalyst 12 incorporated in the PSR reformer. Supply and reaction can be performed.

  The hydrogen supply pipe 111 is further configured to store hydrogen in a hydrogen storage tank (for example, a hydrogen storage device) to which extra hydrogen rich gas is separately attached, and when the hydrogen demand varies due to start-up, low load, or load fluctuation. The hydrogen amount may be appropriately increased or decreased by removing the hydrogen from the hydrogen storage tank, or the hydrogen in the anode off-gas supplied to the PSR reformer by temporarily changing the hydrogen supply amount (for combustion It is also possible to adjust the increase / decrease of the fuel amount as appropriate.

  The supply pipe 112 is provided with a valve V10, and an external supply pipe 113 and an air supply pipe 116 are connected via the valve V10, and gasoline, hydrogen gas, or the like is additionally supplied as combustion fuel through the external supply pipe 113. Air can be replenished from the outside, and air (combustion air) for burning hydrogen or the like (combustion fuel) in the anode off-gas can be supplied by the air supply pipe 116 and the amount of air can be controlled. It has become. Further, a pipe for inserting a cathode (oxygen electrode; the same applies hereinafter) off-gas from the fuel cell 30 is connected to the supply pipe 109, 110 or 112 or directly to the PSR reformer to control the amount of combustion support air. At the same time, the temperature may be adjusted by additionally supplying a relatively high temperature cathode off gas.

  A hydrogen sensor 40 for measuring the amount of hydrogen in the anode off-gas is further attached in the vicinity of the connection portion of the supply pipe 112 to the fuel cell 30 and is burned and generated from moisture in the anode off-gas as will be described later. It is configured so that the amount of water can be calculated.

  In addition, the supply pipe 112 is provided with a throttle valve and a hydrogen buffer tank (for example, a hydrogen storage device, a high-pressure hydrogen tank, etc.) that adjust the anode off-gas amount according to the opening degree, and drive the throttle valve and supply hydrogen from the hydrogen buffer tank. By performing this, it is possible to control the supply amount to the PSR reformer so as not to be linked to the power generation operation state.

  The hydrogen separation membrane fuel cell 30 is connected to the other end of the hydrogen supply pipe 111 and the other end of the supply pipe 112 through which the anode off-gas can be discharged and inserted on the anode (hydrogen electrode) side. On the (oxygen electrode) side, an air supply pipe 114 for supplying air (oxidant gas) having a high oxygen content for power generation operation, and a discharge pipe 115 for discharging the cathode off-gas generated by the battery reaction, Are each connected at one end. In this way, the fuel cell 30 is configured to perform a power generation operation when the reformed and generated hydrogen and air are supplied, and after the power generation, off gas (anode off gas and cathode off gas) can be discharged to the outside of the cell, Further, the discharged anode off gas can be supplied mainly to the regeneration side PSR reformer through the supply pipe 112.

  The other end of the discharge pipe 115 is connected in the middle of the fuel supply pipe 101 so that moisture (and residual oxygen) contained in the cathode offgas can be circulated and used as a water vapor source necessary for the reforming reaction. It is configured. In addition, a humidity sensor 41 for measuring the amount of moisture in the cathode off gas is attached to the discharge pipe 115, and control based on the measured amount of moisture can be performed.

  These include hydrogen reforming due to increased hydrogen demands on the fuel cell, such as low moisture at start-up and low loads, or load fluctuations during transitions from low to high load conditions. This is effective when the amount of steam supplied to the PSR reformer in which the reforming reaction is performed is insufficient because the amount of steam necessary for the reforming reaction increases due to the increase in the amount of production.

  In addition, a cooling pipe through which cooling air (cooling medium) supplied from the atmosphere is inserted is provided inside the fuel cell 30 so that the inside of the battery can be cooled by heat exchange with the cooling air. The pipe is connected to the supply pipe 109, 110 or 112 or directly to the PSR reformer on the regeneration side, and cooling air discharged from the cooling pipe is supplied to enable temperature control and flow rate control, You may make it utilize as combustion support air used for the combustion at the time of regeneration reaction.

  As shown in FIG. 2, the first PSR reformer 10 includes a cylindrical body 11 having a circular cross-section whose both ends are closed, and a catalyst (catalyst supporting part) 12 supported on the inner wall surface of the cylindrical body 11. The cylindrical body 11 forms a space for carrying out the reaction and also functions as a catalyst carrier.

  The cylindrical body 11 is a hollow body which is formed into a cylindrical shape having a circular cross section with a diameter of 10 cm using a ceramic honeycomb and has both ends in the longitudinal direction of the cylinder closed. As the cross-sectional shape and size, an arbitrary shape and size such as a rectangle other than a circle and an ellipse can be selected according to the purpose and the like.

  The catalyst 12 does not carry a catalyst in a region of a predetermined distance A from both ends in the length direction of the cylindrical body toward the in-cylinder direction, that is, from the both ends in the length direction, of the curved surface of the cylindrical body wall. The catalyst non-supporting portions 12A and 12B are left (see FIG. 1) and are supported on the entire surface excluding the catalyst non-supporting portion. For the catalyst 12, metals such as Pd, Ni, Pt, Rh, Ag, Ce, Cu, La, Mo, Mg, Sn, Ti, Y, and Zn can be used.

  When the reforming reaction is performed by the catalyst 12, the reformed and generated hydrogen rich gas is cooled by the catalyst non-supporting portion 12 </ b> A on the downstream side in the gas discharge direction, and the hydrogen rich gas can be supplied close to the operating temperature of the fuel cell 30. On the contrary, when the reforming reaction is switched to the regeneration reaction, the catalyst unsupported portion 12A is in a state of being heated by heat exchange with the hydrogen rich gas, and is supplied in a direction opposite to the discharge direction of the hydrogen rich gas. The combustion fuel can be supplied to the catalyst 12 after being preheated by the catalyst non-supporting portion 12A. Thereby, a temperature distribution in which the amount of heat storage becomes higher is formed near the center of the cylindrical body 11 on which the catalyst 12 is supported, which is advantageous in terms of reactivity. The tubular body 11 is provided with a temperature sensor 19 for measuring the temperature of the catalyst.

  The second PSR reformer 20 is configured in the same manner as the first PSR reformer 10, and the reaction (reforming reaction or regeneration reaction) performed by the first PSR reformer 10 is performed. Therefore, it is possible to switch between the reforming reaction and the regeneration reaction.

As shown in FIG. 3, the hydrogen separation membrane fuel cell (HMFC) 30 includes an electrolyte membrane 51 having a dense hydrogen permeable membrane using a hydrogen permeable metal, and an oxygen electrode (O ₂₎ sandwiching the electrolyte membrane 51. Electrode) 52 and a hydrogen electrode (H ₂ electrode) 53. When the hydrogen-rich gas reformed and generated by the PSR reformer 10 is supplied, hydrogen can be selectively permeated to perform power generation operation. It has become so.

  Between the oxygen electrode 52 and the electrolyte membrane 51, an air flow path 59 a for passing, that is, supplying and discharging air (Air) as an oxidant gas is formed, and between the hydrogen electrode 53 and the electrolyte membrane 51. A fuel flow path 59b for passing, that is, supplying and discharging hydrogen-rich fuel gas (here, reformed and generated hydrogen-rich gas) is formed. The oxygen electrode 52 and the hydrogen electrode 53 are made of various materials such as carbon (for example, carbon powder carrying platinum or an alloy composed of platinum and other metals) or an electrolyte solution (for example, Nafion Solution manufactured by Aldrich Chemical). Can be formed.

The electrolyte membrane 51 has a four-layer structure including a dense substrate (dense hydrogen permeable layer made of a hydrogen permeable metal) 56 formed of vanadium (V). The palladium (Pd) layers (dense hydrogen permeable layers made of a hydrogen permeable material) 55 and 57 are provided so as to sandwich the base material 56 from both sides, and are opposite to the side of the one Pd layer 55 in contact with the base material 56. On the side surface, an electrolyte layer 54 made of BaCeO ₃ (solid oxide) is further provided in a thin layer shape.

  The base material 56 can be suitably formed using niobium, tantalum, and an alloy containing at least one of these in addition to vanadium (V). These have high hydrogen permeability and are relatively inexpensive.

Electrolyte layer (BaCeO ₃ layer) 54 can be configured by using a SrCeO ₃ based ceramic proton conductor other than BaCeO _3.

  Examples of the hydrogen permeable metal include, in addition to palladium, vanadium, niobium, tantalum, an alloy containing at least one of these, and a palladium alloy. The electrolyte membrane can be protected by providing a dense layer using these.

  The dense layer (coating) made of a hydrogen permeable metal generally contains, for example, vanadium (vanadium alone and an alloy such as vanadium-nickel) on the oxygen electrode side because it is generally highly hydrogen permeable and relatively inexpensive. ), Niobium, tantalum, and alloys containing at least one of these are preferably used. Although these can be applied on the hydrogen electrode side, the oxygen electrode side is desirable in terms of avoiding hydrogen embrittlement. On the hydrogen electrode side, it is preferable to use, for example, palladium or a palladium alloy because hydrogen permeability is relatively high and hydrogen embrittlement is difficult.

  As shown in FIG. 3, a sandwich structure composed of three layers of Pd layer 55 / base material 56 / Pd layer 57, that is, a laminated structure of two or more layers composed of different metals (dense layer composed of a hydrogen permeable material). When it has, you may make it provide the metal diffusion suppression layer which suppresses the spreading | diffusion of this different metal in at least one part of the contact interface of a different metal (for example, refer FIG.6 and FIG.7). The metal diffusion suppressing layer is described in paragraphs [0015] to [0016] of JP-A No. 2004-146337.

  As described above, the sandwich layer may be provided as a five-layer structure such as Pd / tantalum (Ta) / V / Ta / Pd in addition to palladium (Pd) / vanadium (V) / Pd. is there. As described above, V has a faster proton or hydrogen atom permeation rate than Pd and is inexpensive, but has a low ability to dissociate hydrogen molecules into protons and the like. By providing on one or both sides of the layer, the transmission performance can be improved. In this case, by providing a metal diffusion suppressing layer between the metal layers, mutual diffusion between different metals can be suppressed, and a decrease in hydrogen permeation performance and hence a decrease in electromotive force of the fuel cell can be suppressed.

  The electrolyte layer 54 is made of a solid oxide, and a reaction suppression layer that suppresses the reaction between oxygen atoms in the electrolyte layer and Pd may be provided at least at a part of the interface with the Pd layer 55 ( For example, the reaction suppression layer 65 in FIG. This reaction suppression layer is described in paragraphs [0024] to [0025] of JP-A No. 2004-146337.

  The electrolyte membrane 51 includes a vanadium base material, which is a dense hydrogen-permeable metal, and an inorganic electrolyte layer formed on the cathode side of the fuel cell, so that the electrolyte layer can be made thin. The operating temperature of the high-temperature solid oxide fuel cell (SOFC) can be lowered to a temperature range of 300 to 600 ° C. As a result, the fuel cell system of the present invention that supplies the cathode off-gas discharged from the fuel cell directly to the PSR reformer that undergoes the reforming reaction can be suitably configured.

In the hydrogen separation membrane fuel cell 30, when a hydrogen rich gas having a high hydrogen (H ₂ ) density is supplied to the fuel flow path 59b and air containing oxygen (O ₂ ) is supplied to the air flow path 59a, the following formula ( The electrochemical reaction (battery reaction) represented by 1) to (3) is caused to supply electric power to the outside. Equations (1) and (2) represent reactions on the anode side and cathode side, respectively, and equation (3) represents the total reaction in the fuel cell.
H ₂ → 2H ⁺ + 2e ⁻ (1)
(1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2)
H ₂ + (1/2) O ₂ → H ₂ O (3)

  PSR reformer 10, 20 (PSR reformer), hydrogen separation membrane fuel cell (HMFC) 30, valves V1-V10, injectors 15-18, hydrogen sensor 40, mixer 117, humidity sensor 41, etc. Are electrically connected to the control device 100, and the operation timing is controlled by the control device 100. The control device 100 controls the output of the fuel cell by adjusting the amount of hydrogen gas and air according to the magnitude of a load (not shown) connected to the hydrogen separation membrane fuel cell. Responsible for control, and also responsible for reaction control between the reforming reaction and the regeneration reaction in the PSR reformer (including switching control when load fluctuation occurs during startup or during fuel cell power generation operation). is there.

  In the present embodiment, when the reforming reaction is performed by the PSR reformer 10 and the regeneration reaction is performed by the PSR reformer 20, the fuel supply pipe is formed by opening the valve V1 and the valve V6 and closing the valve V2 and the valve V7. 101 and supply pipe 102, discharge pipe 107 and hydrogen supply pipe 111 are connected to each other, and valve V9, valve V3 and valve V5 are opened, and valve V8 and valve V4 are closed, whereby supply pipe 109, supply pipe 112 and discharge pipe are connected. 104 and the exhaust pipe 106 are communicated with each other. At this time, a mixed gas of gasoline and water vapor (reforming raw material) is supplied to the PSR reformer 10, and the anode off-gas of the fuel cell 30 is supplied to the PSR reformer 20 as a combustion fuel for regenerating reaction. Supplied to the reaction. The gas mixture which is a reforming raw material is generated by mixing gasoline and water vapor (moisture) in the cathode off-gas from the discharge pipe 115 in the mixer 117, and sent to the PSR reformer 10.

  In the PSR type reformer 10, the heat storage amount is increased due to the regeneration reaction before the reforming reaction switching, and the mixed gas (reforming raw material) of gasoline and steam is inserted from the injection device 15 through the supply pipe 102. When injected and supplied onto the catalyst 12, steam reforming of gasoline is performed at the catalyst 12 to generate hydrogen-rich synthesis gas (hydrogen-rich gas). The reforming reaction is desirably performed under heat storage at 300 to 1100 ° C.

The hydrogen-rich gas produced by reforming as described above is cooled in advance in the catalyst non-supporting portion 12A on the side to which the discharge pipe 107 of the PSR reformer 10 is connected, and then inserted into the discharge pipe 107 and the hydrogen supply pipe 111. Then, it is supplied to the anode side of the hydrogen separation membrane fuel cell 30, and further air is supplied from an air supply pipe 114 provided on the cathode side, and a power generation operation (cell reaction) is performed. When the supplied hydrogen-rich gas is consumed in the power generation operation, it is then discharged as an anode off gas to the supply pipe 112 and is injected from the injection device 18 through the supply pipe 112 and the supply pipe 109. The anode off gas mainly includes residual hydrogen that has not been subjected to the cell reaction, and CO and CH ₄ .

  At this time, if the anode off gas alone is small in the amount of combustion and a sufficient heat storage amount cannot be obtained, or if heat storage cannot be performed in a short time, the valve V10 is set so that the external supply pipe 113 communicates with the supply pipe 112. Can be additionally supplied from the outside, such as gasoline or hydrogen gas for combustion, for example, when the amount of moisture in the cathode off-gas at the time of system startup or low load is low, or from low load to high load In the case of a transition period when the power generation operation is changed, the amount of heat stored by combustion heating can be recovered sufficiently and quickly. Similarly, combustion supporting air for burning hydrogen or the like in the anode off-gas is supplied from the air supply pipe 116 by the valve V10.

  When the anode off-gas is supplied from the injection device 18 to the PSR reformer 20, hydrogen or the like injected on the catalyst 12 is combusted, and the amount of heat stored by combustion heating, that is, the catalyst temperature can be recovered. At this time, the catalyst non-supporting portion 12A on the side of the PSR reformer 20 to which the anode off gas or the like is supplied is heated in the reforming reaction before the regeneration reaction is started as described above. Heat is returned to the catalyst 12 again by heat exchange with the supplied anode off gas or the like, so that heat can be used effectively.

  The combustion off gas generated by the regeneration reaction in the PSR reformer 20 is discharged from the discharge pipe 104. When the fuel cell is in a normal power generation operation state, the combustion off-gas is discharged as it is from the exhaust pipe 106. However, when the fuel cell 30 is at a low load or when the fuel cell 30 transitions from a normal power generation operation state at a low load to a high load state. If it is time, the amount of water vapor supplied to the PSR reformer 10 that performs the reforming reaction may be insufficient or insufficient, and thus control is performed as described below.

  That is, when the load is low, the amount of water in the cathode off-gas is small due to low power generation, and during the transition, the hydrogen demand of the fuel cell 30 increases suddenly while moving from the low load state to the high load state, while the PSR reformer The supply of the amount of water vapor corresponding to the amount of water vapor required in 10 cannot follow, and the hydrogen reforming production efficiency due to the shortage of water vapor necessary for the reforming reaction may be significantly reduced. In the present invention, the regeneration reaction is performed. Rather than immediately discharging the moisture generated by the regeneration reaction in the PSR reformer 20 but introducing it into the PSR reformer 10 on the reforming side, a low load or transient It is possible to replenish the shortage of steam required at times and maintain the hydrogen reforming production efficiency regardless of the low load or load fluctuation, thereby ensuring a stable amount of hydrogen. Thereby, the stable electric power generation operation can be performed continuously.

  In addition, in the hydrogen generation by steam reforming performed by replenishing the shortage in this way, the oxygen supply amount to the reforming reactor to be reformed is increased to cause a partial oxidation reaction, that is, a significant decrease in heat storage amount and hydrogen loss. This is more advantageous in terms of hydrogen production efficiency than the method of improving the efficiency of hydrogen production by suppressing the above.

  Specifically, it is as follows. That is, in the control routine performed by the control device 100 of the fuel cell system according to the present embodiment, when the fuel cell 30 changes from a low load to a power generation operation at a high load (transition time), that is, steam for causing a reforming reaction. Load fluctuation control that performs switching control for switching the flow path so that combustion off-gas (exhaust gas) is supplied from the regeneration side PSR reformer 20 to the reforming side PSR reformer 10 when the amount is insufficient. The routine will be mainly described with reference to FIG.

  FIG. 4 shows a load fluctuation control routine. When this routine is executed, in step 100, the load fluctuation value P (= ts) when the fuel cell system is in a transition period, that is, when the fuel cell is shifted from a low load s state to a high load t state. Is determined to exceed the predetermined value Q, and when it is determined that the load fluctuation value P exceeds the predetermined value Q, the process proceeds to step 102 to calculate and acquire the required load on the fuel cell, When it is determined that the load fluctuation value P is less than or equal to the predetermined value Q, the hydrogen reforming production efficiency due to the lack of steam is not likely to be significantly reduced, and thus this routine is immediately terminated.

  After acquiring the required load in step 102, in step 104, the hydrogen generation amount (necessary hydrogen generation amount) necessary for the acquired required load is calculated and acquired. Next, in step 106, the amount of gasoline required to satisfy the acquired required hydrogen production amount is calculated and acquired, and then in step 108, the amount of steam for causing the calculated gasoline to undergo a steam reforming reaction satisfactorily. (Required amount of water vapor) a is calculated.

  Next, in step 110, in light of the relationship line indicating the relationship between the power generation amount of the fuel cell stored in advance and the amount of generated water generated and generated, the power generation amount required in correspondence with the load acquired in step 102 The amount of generated water, that is, the amount of water vapor b contained in the cathode offgas from the fuel cell 30 is acquired.

  In step 112, it is determined whether the required water vapor amount a is equal to or larger than the water vapor amount b supplied by the cathode off gas, that is, whether the water vapor amount in the cathode off gas is satisfied or not. When it is determined that the amount a is equal to or greater than the amount of steam b, that is, the amount of steam is insufficient, the routine proceeds to step 114, and when it is determined that the required amount of steam a is less than the amount of steam b, the amount of steam required for steam reforming. Because there is no risk of shortage, this routine is terminated as it is.

  In step 110 described above, detection is performed by the humidity sensor 41 provided as a detecting means for detecting the amount of moisture in the discharge pipe 115, and the amount of water vapor b contained in the cathode off-gas is obtained from the detected value. May be used to determine whether or not the required water vapor amount a is satisfied.

  In step 114, the deficient water vapor amount c (= ab) is calculated, and then in step 116, the valve V5 is switched to the closed state so that the discharge pipe 104 and the discharge pipe 105 communicate with each other. The combustion off-gas discharged from the mass device 20 is sent from the discharge pipe 104 to the PSR reformer 10 via the discharge pipe 105 without being discharged from the discharge pipe 106. At this time, the amount of combustion off-gas corresponding to the deficient water vapor amount c from the relationship line indicating the relationship between the amount of hydrogen in the anode off-gas measured by the hydrogen sensor 40 and the amount of water produced by the regeneration reaction. Is calculated and supplied to the PSR reformer 10.

  In this way, it is necessary for the reforming reaction due to the increase in the amount of reformed hydrogen generated with the increase in the hydrogen demand to the fuel cell, including the transition from the low load state to the high load state. When the amount of water vapor increases, it is possible to replenish while monitoring the insufficient amount of water vapor, and it is possible to efficiently perform the steam reforming of gasoline to ensure a stable amount of hydrogen.

  As described above, when the heat storage amount of the PSR reformer 10 undergoing the reforming reaction, that is, the catalyst temperature is lowered and the hydrogen reforming production efficiency is lowered, the PSR reformer 10 The reforming reaction is switched to the regeneration reaction, and the regeneration reaction in the PSR reformer 20 is switched to the reforming reaction. Specifically, by opening the valve V2 and the valve V7 and closing the valve V1 and the valve V6, the fuel supply pipe 101 and the supply pipe 103, the discharge pipe 108 and the hydrogen supply pipe 111 are communicated with each other, and the valve V8 and the valve V4 and By opening the valve V5 and closing the valve V9 and the valve V3, the supply pipe 110, the supply pipe 112, the discharge pipe 105, and the discharge pipe 106 are communicated with each other. At this time, a mixed gas (reforming raw material) of gasoline and water vapor is supplied to the PSR reformer 20, and the anode off-gas of the fuel cell 30 is supplied to the PSR reformer 10 as a combustion fuel for regenerating reaction. Supplied to each reaction.

  In the case of switching as described above, the PSR reformer 20 is in a state where the heat storage amount has increased due to the regeneration reaction before the reforming reaction switching, and the gasoline and water vapor are mixed from the injector 17 through the supply pipe 103. When gas (reforming raw material) is injected and supplied onto the catalyst 12, the catalyst 12 performs steam reforming of gasoline to generate hydrogen-rich synthesis gas (hydrogen-rich gas). The reaction temperature of the reforming reaction is the same as described above. The hydrogen-rich gas reformed and generated by the PSR reformer 20 is cooled in advance by the catalyst non-supporting part 12A on the side to which the discharge pipe 108 of the PSR reformer 20 is connected, and then the exhaust pipe 108 and hydrogen The gas is supplied to the anode side of the hydrogen separation membrane fuel cell 30 through the supply pipe 111 and is supplied to the power generation operation (cell reaction) together with the air supplied from the air supply pipe 114. The supplied hydrogen-rich gas is consumed and discharged as an anode off-gas to the supply pipe 112 and then injected from the supply pipe 112 through the supply pipe 110 from the injection device 16.

  At this time, as described above, the external supply pipe 113 is connected to the supply pipe 112 in the case where the anode off gas alone has a small combustion amount and a sufficient heat storage amount cannot be obtained or heat storage cannot be performed in a short time. The valve V10 is switched so as to communicate, and combustion gasoline, hydrogen gas, and the like can be additionally supplied from the outside. Similarly, combustion supporting air is supplied from the air supply pipe 116 by the valve V10.

  The anode off-gas is supplied from the injection device 16 to the PSR reformer 10, and hydrogen or the like supplied on the catalyst 12 is combusted, so that the heat storage amount (that is, the catalyst temperature) can be recovered again. At this time, the catalyst non-supporting portion 12A on the side of the PSR reformer 10 to which the anode off gas or the like is supplied is in a state where the temperature has been raised in the reforming reaction before the regeneration reaction is started in the same manner as described above. The heat is exchanged with the anode off gas or the like, so that the heat is returned to the catalyst 12 again and used effectively.

  The combustion off gas generated by the regeneration reaction in the PSR reformer 10 is exhausted through the exhaust pipe 105. When the fuel cell is in a normal power generation operation state, the combustion off-gas is discharged as it is from the discharge pipe 106 communicating with the discharge pipe 105, but when the fuel cell 30 is in a transient state, the PSR reformer 20 There is a risk that the amount of water vapor supplied to the battery will be insufficient. Therefore, as in the case before the switching between the reforming reaction and the regeneration reaction, the valve V5 is closed without discharging the moisture generated by the regeneration reaction in the PSR reformer 10 from the discharge pipe 106. Then, control is performed so that the discharge pipe 105 is introduced into the PSR reformer 20 on the reforming side via the discharge pipe 104, and a shortage of the amount of steam necessary for the transient is replenished, and the hydrogen is improved regardless of the load fluctuation. The amount of hydrogen can be stably secured while maintaining the quality production efficiency. As a result, even when the reforming reaction is performed by the PSR reformer 20, stable power generation operation can be continuously performed. The specific control method can be performed in the same manner as described above.

  In the above, by providing the valve V5 in the exhaust pipe 106, combustion off-gas can be introduced from the regeneration side PSR reformer to the reforming side PSR reformer, but instead of the valve V5, It is also possible to provide a three-way valve at a connection portion where the other ends of the discharge pipes 104 and 105 and one end of the discharge pipe 106 are connected to introduce the combustion off gas into the reforming PSR reformer.

  In the above description, the case where the amount of water vapor is insufficient due to load fluctuations during normal power generation operation has been described, but when the ignition (IG) switch is turned on to start warming up, when warming up is completed and startup is completed There is a possibility that the amount of water vapor is insufficient even when shifting to normal power generation operation (when startup is completed).

  That is, for example, when the reforming reaction is performed by the PSR reformer 10 and the regeneration reaction is performed by the PSR reformer 20, the power generation in the fuel cell 30 is not yet started or the power generation amount is small when the start-up is completed. Since the amount of water in the interior cannot cover all the amount of steam necessary for steam reforming of gasoline, the combustion off-gas generated by the regeneration reaction in the PSR reformer 20 is not immediately discharged, for example, the valve V5. Is closed and supplied to the PSR reformer 10 on the reforming side, and the shortage of steam necessary for steam reforming after completion of the start-up is replenished with moisture in the combustion off-gas, thereby improving the hydrogen. The amount of hydrogen can be stably secured while maintaining the quality production efficiency. Thereby, stable power generation operation can be performed even in the process in which the fuel cell enters normal power generation operation.

  Hereinafter, referring to FIG. 5, when the amount of water vapor is insufficient in the process of shifting to normal power generation operation after the start-up is completed after the warm-up is completed after turning on the IG switch, the PSR reforming on the regeneration side The start-up control routine for performing switching control for switching the flow path so that the combustion off-gas is supplied from the gas generator 20 to the reforming-side PSR reformer 10 will be mainly described.

FIG. 5 shows a startup control routine. When this routine is executed by turning on the IG switch, in step 200, the temperature t ¹ of the catalyst 12 of the PSR reformer 10 is ^first taken in, and in the next step 202, the temperature t ¹ is equal to or higher than the predetermined temperature T. If it is determined whether or not the warm-up operation has been completed, and it is determined that the warm-up operation has been completed (t ¹ ≧ T), the routine proceeds to step 204. On the other hand, when it is determined in step 202 that the warm-up operation is not completed (t ¹ <T), the process returns to step 200 and waits until the warm-up operation is completed. To do.

  In step 204, the valve V5 is switched to the closed state so that the discharge pipe 104 and the discharge pipe 105 communicate with each other, and the water-containing combustion off-gas discharged from the PSR reformer 20 is first discharged from the discharge pipe 104 to the discharge pipe 105. Then, in step 206, the temperature is gradually raised by the heat of the combustion off gas and the reforming reaction is started. Then, as hydrogen is reformed and generated in step 206, the fuel cell 30 starts a power generation operation in step 208, and the amount of water in the cathode offgas increases.

In step 210, the gasoline supply amount (C ₁ ) supplied to the PSR reformer 10 is acquired. In step 212, the power generation amount and power generation of the fuel cell stored in advance in the same manner as described above. The amount of generated water calculated from the amount of power generation, that is, the amount of water vapor (S ₁ ) in the cathode offgas discharged from the fuel cell 30 is obtained in light of the relationship line indicating the relationship with the amount of generated water.

In step 210, detection may be performed by the humidity sensor 41 provided in the discharge pipe 115, and the water vapor amount S ₁ contained in the cathode off-gas may be acquired from the detected value.

Next, in step 214, it is determined whether or not the ratio (S ₁ / C ₁ ) of the water vapor amount S ₁ to the obtained gasoline supply amount C ₁ is 1.0 (= S ₀ / C ₀ ) or more. When it is determined that S ₁ / C ₁ is 1.0 or more (S ₁ / C ₁ ≧ 1.0), the PSR reformer 10 can secure the amount of water vapor necessary for the reforming reaction. Since there is little possibility of soot formation, in the next step 216, the valve V5 is opened and the valve V4 is closed to shift to a normal power generation operation, and this routine is terminated.

If it is determined in step 214 that the ratio S ₁ / C ₁ is less than 1.0 (S ₁ / C ₁ <1.0), the amount of water vapor necessary for the reforming reaction is not yet obtained. Returning to 210, the process proceeds to step 216 on condition that S ₁ / C ₁ ≧ 1.0 is satisfied.

In addition, when the partial oxidation reaction that is an exothermic reaction is performed together with the steam reforming reaction that is an endothermic reaction, it is desirable to perform so as to satisfy S ₁ / C ₁ + O / C ≧ 2.0 (O / C Represents the oxygen / carbon ratio).

  Although the case where the reforming reaction is performed by the PSR reformer 10 and the regeneration reaction by the PSR reformer 20 has been described here, the regeneration reaction is performed by the PSR reformer 10 by switching the valves V1 to V9 as described above. The same applies to the case where the PSR reformer 20 performs the reforming reaction. Further, instead of the valve V5, a three-way valve is provided at a connection portion where the other ends of the discharge pipes 104 and 105 and one end of the discharge pipe 106 are connected to introduce the combustion off gas into the PSR reformer on the reforming side. It may be.

  In the above, it is also effective to provide a heater such as an electric heater to heat the catalyst during a transition in which the fuel cell 30 shifts from the low load state to the high load state and the hydrogen demand of the fuel cell suddenly increases. Is. In this case, the catalyst can be directly heated by providing an electric heater or the like in the vicinity of the catalyst support portion 12 of the PSR reformer and turning on the electric heater or the like on the PSR reformer side to be reformed. In addition, the reforming reaction can be accelerated rapidly, and it is also effective when the switching cycle between the reforming reaction and the regeneration reaction is made short.

  Further, when a heater such as an electric heater is provided, it is effective to provide a heater selectively at the highest temperature portion of the catalyst support portion of the PSR reformer. The reforming reaction proceeds most rapidly at the site of the highest temperature (that is, the reaction rate does not change linearly with the temperature, and the reaction is rapidly accelerated at a high temperature). The heat energy efficiency can be increased by reducing the heating in the low region so that the region with low reactivity or the entire region including the region is not heated halfway.

  In the fuel cell system of the present invention, as a fuel cell, a hydrogen separation membrane provided with an electrolyte membrane in which an electrolyte layer is laminated on at least one side of a dense hydrogen permeable membrane (hydrogen permeable metal layer) using a hydrogen permeable metal. Type fuel cells (which may be either proton-conductive solid oxide type or solid polymer type) can be selected according to the purpose.

  For example, (1) an electrolyte membrane having a hydrogen permeable metal and an inorganic electrolyte layer (especially proton conductive ceramics) formed on at least one side of the metal, and hydrogen provided on one surface of the electrolyte membrane A fuel supply part for supplying power generation fuel to the electrode and the hydrogen electrode, an oxygen electrode provided on the other surface of the electrolyte membrane, and an oxidant gas supply part for supplying an oxidant gas to the oxygen electrode Hydrogen separation membrane fuel cell, or (2) an electrolyte membrane having a proton conductive electrolyte layer and a hydrogen permeable metal sandwiching the electrolyte layer from both sides, a hydrogen electrode provided on one surface of the electrolyte membrane, and the A solid polymer comprising a fuel supply unit for supplying power generation fuel to the hydrogen electrode, an oxygen electrode provided on the other surface of the electrolyte membrane, and an oxidant gas supply unit for supplying an oxidant gas to the oxygen electrode Type hydrogen separation membrane fuel cell, etc. It can be used to apply.

  6 to 7 show other specific examples of the hydrogen separation membrane fuel cell constituting the fuel cell system of the present invention. For details about other specific examples, reference can be made to the description in Japanese Patent Application Laid-Open No. 2004-146337.

FIG. 6 shows an electrolyte membrane 61 having a five-layer structure including a dense substrate 66 formed of vanadium (V), an oxygen electrode (O ₂ electrode) 62 and a hydrogen electrode (H ₂ electrode) sandwiching the electrolyte membrane 61. ) 63 and a hydrogen separation membrane fuel cell 60 provided with a metal diffusion suppression layer and a reaction suppression layer. The electrolyte membrane 61 is provided with a dense metal diffusion suppression layer 67 and a palladium (Pd) layer 68 in this order from the surface side of the base electrode 66 on the hydrogen electrode (anode) 63 side. On the surface of the cathode 62 side, a dense reaction suppression layer (for example, a proton conductor, mixed conductor, or insulator layer) 65 and a thin electrolyte layer (for example, a perovskite layer) made of a solid oxide are sequentially formed from the surface side. One metal oxide SrCeO ₃ layer, etc.) 64. The reaction suppression layer 65 has a function of suppressing the reaction between oxygen atoms in the electrolyte layer 64 and the base material (V) 66. In the same manner as described above, an air channel 59a and a fuel channel 59b are formed between the oxygen electrode or hydrogen electrode and the electrolyte membrane. Details of the metal diffusion suppression layer and the reaction suppression layer are as described above.

FIG. 7 includes an electrolyte membrane 71 having a dense hydrogen permeable layer using a hydrogen permeable metal, and an oxygen electrode (O ₂ electrode) 72 and a hydrogen electrode (H ₂ electrode) 73 sandwiching the electrolyte membrane 71. The solid polymer type hydrogen separation membrane fuel cell 70 is shown. The electrolyte membrane 71 has, for example, a multilayer structure in which the surfaces on both sides of an electrolyte layer 76 made of a solid polymer membrane such as a Nafion (registered trademark) membrane are sandwiched between dense hydrogen permeable metal layers. A palladium (Pd) layer (dense layer) 77 is provided on the hydrogen electrode (anode) side surface of 76, and a vanadium-nickel serving as a base material in order from the surface side on the oxygen electrode (cathode) side surface of the electrolyte layer 76. An alloy (V—Ni) layer (dense layer) 75 and a Pd layer (dense layer) 74 are provided. As described above, an air channel 59a and a fuel channel 59b are formed between the oxygen electrode or hydrogen electrode and the electrolyte membrane 71, respectively. Also in the present fuel cell, a metal diffusion suppression layer can be provided between the V-Ni layer 75 and the Pd layer 74, and a reaction occurs between the V-Ni layer 75 or the Pd layer 77 and the electrolyte layer 76. A suppression layer can be provided.

  In the polymer electrolyte fuel cell shown in FIG. 7, by forming a hydrogen permeable layer using a hydrogen permeable metal so as to sandwich the hydrous electrolyte layer, moisture evaporation and membrane resistance of the electrolyte layer at a high temperature are achieved. It is possible to suppress the increase, and in general, the operating temperature of a low-temperature polymer electrolyte fuel cell (PEFC) can be improved to a temperature range of 300 to 600 ° C. This is suitable for the configuration of the fuel cell system of the present invention in which the cathode off-gas discharged from the fuel cell is directly supplied to the PSR reformer that undergoes the reforming reaction.

  In the above embodiment, the case where a mixed gas of gasoline and water vapor is used as the reforming raw material has been described, but the same applies to the case where a hydrocarbon fuel other than gasoline is used.

1 is a schematic configuration diagram showing a fuel cell system according to an embodiment of the present invention. It is a perspective view which shows schematic structure of the PSR type reformer which concerns on embodiment of this invention. 1 is a schematic cross-sectional view showing a hydrogen separation membrane fuel cell (HMFC) according to an embodiment of the present invention. It is a flowchart which shows the control routine at the time of the load variation performed at the time of the transition of the fuel cell system which concerns on embodiment of this invention. It is a flowchart which shows the starting time control routine performed after completion of starting of the fuel cell system which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the other specific example of the fuel cell which comprises the fuel cell system which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the other specific example of the fuel cell which comprises the fuel cell system which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... PSR reformer 10, 20 ... PSR reformer 12 ... Catalyst (catalyst carrying part)
12A, 12B ... catalyst non-supporting parts 15, 16, 17, 18 ... injectors 30, 60, 70 ... hydrogen separation membrane fuel cell 40 ... hydrogen sensor 41 ... humidity sensor 51 ... electrolyte membrane 52 ... oxygen electrode 53 ... hydrogen electrode 59a ... Air channel 59b ... Fuel channel 100 ... Control devices V1-V10 ... Valve

Claims (4)

When a reforming material comprising a catalyst and containing fuel and water vapor is supplied, the reforming material is reformed on the heated catalyst, and when the combustion fuel is supplied, the combustion fuel is At least two reforming reactors that heat the catalyst by a combustion reaction;
Exhaust gas supply means for supplying exhaust gas discharged from the reforming reactor subjected to combustion reaction to the reforming reactor for reforming reaction;
A hydrogen generation apparatus comprising:   The exhaust gas supply means includes a switching means for switching a discharge flow path of exhaust gas discharged from the reforming reactor that has undergone a regeneration reaction, and a water vapor amount of the water vapor that is supplied to the reforming reactor that undergoes a reforming reaction. Determining means for determining whether or not a predetermined amount is satisfied, and when the determination means determines that the amount of water vapor does not satisfy the predetermined amount, the reforming reactor that causes the exhaust gas to undergo a reforming reaction The hydrogen generation apparatus according to claim 1, further comprising: a switching control unit that switches the discharge flow path by the switching unit so as to be supplied.   A fuel cell system comprising: the hydrogen generator according to claim 1; and a fuel cell that generates electric power by supplying a hydrogen-containing gas reformed and generated by the hydrogen generator.   The fuel cell system according to claim 3, wherein the fuel cell includes an electrolyte in which an electrolyte layer is stacked on at least one side of the hydrogen permeable metal layer.

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