JP2006282469A - Hydrogen production apparatus and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure high durability performance of a hydrogen production apparatus which can perform reforming production of hydrogen with high efficiency for a long period of time by avoiding the deterioration of the catalyst accompanying the switching from a reforming reaction to a regenerating reaction. <P>SOLUTION: When switching from a reforming reaction to a combustion reaction, air-fuel ratio during the combustion reaction is set to be leaner than the theory air-fuel ratio by reducing the supply amounts of a fuel gasoline and an anode off-gas supplied by injection devices 23, 24 than the target amounts. <P>COPYRIGHT: (C)2007,JPO&INPIT

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, when a predetermined condition is established using a catalyst, the steam reforming reaction of the fuel that is an endothermic reaction and the regeneration reaction that regenerates the catalyst temperature decreased by the steam reforming reaction are switched. A fuel reformer that can perform the above has been proposed (see, for example, Patent Document 1).

  In this fuel reformer, two catalysts are combined into one set, and when one catalyst undergoes a reforming reaction, the other catalyst undergoes a regenerative reaction, and these two reactions are alternately switched so that the reforming performance can be maintained. In particular, it is suitable for reforming liquid fuel or the like from which sulfur content is not completely removed. That is, by the regeneration reaction, the catalyst temperature lowered by the steam reforming of the fuel is regenerated, and poisoning substances adhering to the catalyst are burned out.

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).
US 2003-235529 U.S. Patent No. 2004-170558 US Patent No. 2004-170559 U.S. Patent No. 2004-175326 JP 2004-146337 A

  However, the regeneration reaction in the fuel reformer is performed by combustion of fuel with oxygen, that is, an oxidation reaction. The combustion temperature of this combustion reaction is generally determined by setting the fuel / oxygen amount ratio (air-fuel ratio) in the vicinity of the theoretical air-fuel ratio. It becomes the highest during combustion and the temperature rises rapidly.

  Therefore, when regenerating the catalyst temperature, if the combustion reaction becomes too high in relation to the stoichiometric air-fuel ratio, it will reach a temperature that causes a deterioration in the performance of the catalyst reactor, such as causing deterioration of the catalyst itself, It is difficult to maintain durability for a long time.

  Since the temperature rise gradient at this time exceeds the responsiveness of the temperature detector for detecting the catalyst temperature, even in the apparatus provided with the temperature detector, when the temperature is determined to be abnormal and the control means takes necessary measures In many cases, the temperature at which the catalyst loses the reforming function is already exceeded.

  In such a case, in order to avoid a sudden rise in temperature, a method of adjusting the flow rate of oxygen so that the mixture ratio becomes leaner than the stoichiometric air-fuel ratio may be considered. Since the fuel flow is smaller than the air flow rate and the fuel volume is smaller than the air volume, the liquid fuel is superior in supply response to air but is inferior in dispersibility. Therefore, at the time of switching from the reforming reaction to the regeneration reaction, the theoretical air-fuel ratio is established because the fuel precedes and the air arrives late, and the fuel due to poor dispersion despite the small amount of fuel. The stoichiometric air-fuel ratio is established due to the local concentration of air and the good dispersion of air. Thereafter, the catalyst temperature is likely to be abnormally increased because the theoretical air-fuel ratio is adjusted to a predetermined ratio after exceeding the theoretical air-fuel ratio, and the catalyst impairs the reforming function due to this abnormal temperature increase.

  The present invention has been made in view of the above, and avoids catalyst deterioration associated with a rapid temperature rise at the time of switching from a reforming reaction to a regeneration reaction, and performs reforming of hydrogen with high efficiency over a long period of time. It is an object of the present invention to provide a hydrogen generator that can be obtained and a fuel cell system that can stably exhibit power generation performance with high durability.

  The present invention relates to a steam reforming reaction of fuel, which is an endothermic reaction, and an exothermic reaction (hereinafter referred to as “regeneration reaction”) for regenerating the reforming reactivity of the catalyst by recovering the catalyst temperature lowered by the steam reforming reaction. In order to suppress a rapid temperature rise particularly when switching from the reforming reaction to the regeneration reaction, the mixing ratio at the time of switching should be made leaner than the stoichiometric air-fuel ratio. Although it is one method, we obtained knowledge that it is more effective to reduce the fuel amount and make lean than to make it leaner by increasing the oxygen amount, considering the overall thermal efficiency, and achieved based on such knowledge It has been done. The exothermic reaction in the present invention includes a combustion reaction and the like.

  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. At least one reforming performed by switching between the reforming reaction and the exothermic reaction so that when the exothermic fuel is supplied, the exothermic fuel is reacted exothermically to heat the catalyst. Reactor, fuel supply means for supplying exothermic fuel to the reforming reactor, and when switching from reforming reaction to exothermic reaction, so that the air-fuel ratio at the time of exothermic reaction is leaner than the stoichiometric air-fuel ratio, Combustion control means for reducing the amount of heat-generating fuel supplied from the fuel supply means to be less than a predetermined target amount.

  In the hydrogen generator of the present invention, at least one modification that can be performed by switching between a reforming reaction of fuel using heat storage and a regeneration reaction that recovers the heat storage amount (that is, the catalyst temperature) decreased by the reforming reaction. A quality reactor (hereinafter also referred to as “PSR (Pressure swing reforming type reformer)”) is provided. In the case of a configuration in which two or more PSR reformers are provided, at least one of them performs a fuel reforming reaction, and at least one of them performs a regeneration reaction (hereinafter referred to as a PSR reformer). A hydrogen generation device provided with two or more quality devices is also referred to as a “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 constituting the hydrogen generator, one of them performs a steam reforming reaction (mainly the reaction of (1) above) which is an endothermic reaction using heat storage in the reactor, On the other hand, a regeneration reaction, which is an exothermic reaction, is performed. When the amount of heat stored in one side decreases due to a steam reforming reaction, the one is switched to a regeneration reaction, and the other is fuel-modified with heat stored by the regeneration reaction. Switch to reforming reaction to perform quality. This eliminates the need for a separate heater and enables continuous hydrogen generation with high use efficiency of heat energy.

  In the first invention, when switching from the reforming reaction to the exothermic reaction, instead of increasing the supply amount of the oxygen-containing gas for combusting the exothermic fuel, the supply amount of the exothermic fuel is decreased to a predetermined target amount. The air-fuel ratio at the time of the exothermic reaction is made leaner than the stoichiometric air-fuel ratio, so that the entire catalyst can be supplied without being cooled by the oxygen-containing gas when supplied in a large amount. Alternatively, local abnormal temperature rise can be effectively avoided. As a result, the reduction of the reforming function due to catalyst deterioration can be effectively suppressed while maintaining the heat utilization efficiency, and the durability performance can be improved.

  In the first invention, as the reforming reactor, at least a pair of reforming reactors can be provided which are alternately switched between the reforming reaction and the exothermic reaction. In this pair of reforming reactors, two reforming reactors are paired. On the one hand, the reforming reaction is performed, and on the other hand, the exothermic reaction is performed. In the case where it is possible to perform a quality reaction, it is possible to perform continuous hydrogen generation with high utilization efficiency of heat energy while preventing the above-described abnormal temperature rise of the catalyst from occurring in each reforming reactor. it can. In addition, there is no need for a separate heater to regenerate the catalyst temperature lowered by the reforming reaction, and the combustion of poisonous components on the catalyst poisoned during the reforming reaction by the exothermic reaction switched after the reforming reaction. Removal is also possible.

  Further, the switching between the reforming reaction and the exothermic reaction in each reforming reactor is performed by further providing switching means for switching the reforming material supply channel and the exothermic fuel supply channel to the reforming reactor. Can be. By electrically connecting the switching means to the combustion control means, each supply flow path can be automatically switched.

  This switching means has a flow path through which at least the fuel constituting the reforming raw material passes and a flow path through which the heat generating fuel passes, and selectively selects a supply flow path connected to each of the pair of reforming reactors. A flow path switching member for switching can be provided. Since the flow path switching member is configured to be movable, for example, a single switching means (for example, an actuator) can be used to switch between the reforming reaction and the regeneration reaction in the two reforming reactors in a pair. Since they can be performed at the same time, switching malfunctions are avoided and synchronization is assured. As a result, it is possible to prevent combustion of the heat generating fuel from being started at a stage where the amount of oxygen is small or a reduction in reforming efficiency.

  According to the first aspect of the present invention, an oxygen supply means for supplying an oxygen-containing gas for burning the exothermic fuel to the reforming reactor can be further provided. In the case where it is provided in the quality reactor, a partition that suppresses the mixing of the exothermic fuel and the oxygen-containing gas supplied during the exothermic reaction in at least a part of the reforming reactor is provided in the reactor. Is effective.

  As described above, the entire catalyst or a local abnormal temperature rise is avoided, and in the first invention, a partition wall is disposed in the reforming reactor, and is disposed on one side of the region separated by the partition wall. A catalyst provided to be supported in the chamber (for example, the inner wall surface) by providing fuel supply means to supply heat-generating fuel and providing oxygen supply means on the other side to supply oxygen-containing gas Since the contact between the exothermic fuel and the oxygen-containing gas is limited until it reaches the vicinity of the center of the supporting portion, the backfire that tends to occur during the regeneration reaction can be prevented and the exothermic fuel and oxygen-containing gas supply side can be prevented. During the reforming reaction, the inside of the vessel on the discharge side of the reformed hydrogen-containing gas can be cooled with both the heat-generating fuel and the oxygen-containing gas, so the hydrogen-containing gas reformed and generated during the reforming reaction can be cooled at a low temperature. Can be discharged.

  Further, when the oxygen supply means and the fuel supply means are provided in the same reforming reactor, during the exothermic reaction, the exothermic fuel is supplied from one end of the reforming reactor and the oxygen-containing gas is supplied from the other end. It can be configured to be supplied in a direction substantially opposite to that of the heat generating fuel.

  In the first invention, as described above, the entire catalyst or a local abnormal temperature rise is avoided, and further, by adopting such a configuration, the supplied exothermic fuel and oxygen-containing gas are contained in the chamber ( For example, it can be contacted near the center of the catalyst supporting part supported on the inner wall, which is effective for preventing flashback that tends to occur during the regeneration reaction, and concentrates the combustion heat on the catalyst supporting part. Therefore, it is effective for shortening the regeneration reaction time and improving the reforming reactivity.

  An electric heater can be further provided in the catalyst supporting portion where the catalyst of the reforming reactor constituting the first invention is supported. In the present invention, as described above, when switching from the reforming reaction to the exothermic reaction, the supply amount of the exothermic fuel is made smaller than a predetermined target amount so that the air-fuel ratio at the exothermic reaction becomes lean. As a result, the ignitability may be lowered. Therefore, an auxiliary electric heater such as an electric heater or an electric heating catalyst (EHC) is provided in the catalyst supporting part so that it can be heated as necessary. By constituting in this way, it is possible to assist the ignitability at the time of lean and ensure the exothermic reactivity.

  The combustion control means constituting the first invention changes the concentration of the heat generating fuel supplied by the fuel supply means when the air-fuel ratio (fuel / oxygen amount) at the time of switching is made lean. Thus, the air-fuel ratio at the time of the exothermic reaction can be made lean.

  Further, when the air-fuel ratio (fuel / oxygen amount) at the time of switching is made lean, a plurality of fuel supply means are provided in the reforming reactor, and fuel for heat generation is supplied to the reforming reactor from a plurality of parts. It is also effective. Since the fuel can be distributed and supplied onto the catalyst provided in the vessel, the fuel is locally present in the catalyst carrier due to poor dispersion despite the small amount of fuel. Therefore, the establishment of the stoichiometric air-fuel ratio can be avoided, and the catalyst function can be effectively prevented from being lowered due to an abnormal temperature rise of the catalyst temperature.

  When a plurality of fuel supply means are provided in the reforming reactor, the atmosphere passing through the reforming reactor during the exothermic reaction, that is, toward the inserting direction of the supplied exothermic fuel and the combustion gas generated by the regeneration reaction It can be arranged sequentially. If supply is performed with a single fuel supply means, the temperature in the chamber tends to be non-uniform, but there are a plurality of fuel supply means at arbitrary or predetermined intervals along the insertion direction of the atmosphere passing through the chamber. By providing, the catalyst temperature distribution can be made uniform while removing the theoretical air-fuel ratio, so that the regeneration time of the catalyst temperature by the exothermic reaction can be shortened with a smaller amount of fuel.

  At this time, the combustion control means supplies the fuel for heat generation from the plurality of fuel supply means at the time of switching from the reforming reaction to the exothermic reaction, and when it is determined that a predetermined time has elapsed from the switching after the switching, Alternatively, after the switching, when it is determined that the predetermined part of the reforming reactor has reached the predetermined temperature, the exothermic fuel can be supplied from some of the plurality of fuel supply means. As a result, when a small amount of fuel is dispersedly supplied, the time required for catalyst regeneration due to an exothermic reaction is avoided, or the fuel poisoning component is burned and removed by intensive supply from some fuel supply means. It is effective.

  In particular, when the reforming raw material is supplied from one end of the reforming reactor and the exothermic fuel is supplied from the other end, the atmosphere that passes through the reactor during the exothermic reaction, that is, for exothermic use When it is determined that the catalyst has reached a predetermined temperature in at least a part of the upstream side of the center of the catalyst carrier in the fuel and combustion gas insertion direction, the catalyst is disposed downstream of the center in the insertion direction. It is effective to adjust the supply amount of at least one heat generating fuel in the provided fuel supply means to be larger than that on the upstream side.

  Accumulation of sulfur and other poisonous substances on the catalyst tends to concentrate near one end of the reforming reactor on the reforming fuel supply side, so it is supported near the other end on the exothermic fuel supply side. When it is determined that the catalyst that has reached the predetermined temperature, the exothermic reactivity is increased by increasing the supply of the exothermic fuel to the reforming fuel supply side, so the accumulated poisonous substances are removed by combustion. It is effective.

  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, when switching from the reforming reaction to the exothermic reaction, the supply amount of the exothermic fuel is reduced to be smaller than a predetermined target amount, so that the air-fuel ratio at the exothermic reaction is leaner than the stoichiometric air-fuel ratio. Therefore, the abnormal temperature rise locally or locally of the catalyst is eliminated, durability performance capable of continuing reforming and generation of hydrogen for a long time can be secured, and normal power generation operation can be performed stably.

  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. The hydrogen rich gas produced by reforming can be supplied in the operating temperature range of the fuel cell, and the off-gas on the anode side and cathode side of the fuel cell is directly returned to the PSR reformer for regeneration, etc. Therefore, it is particularly suitable in terms of system configuration and effective use of thermal energy. In addition, preheating before supply is unnecessary.

  In 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, the reformed and generated hydrogen is supplied to the fuel cell and is reduced by steam reforming of the fuel. When the reformer recovers the heat storage amount by performing an exothermic reaction (regeneration reaction), which is an exothermic reaction, when the reforming reaction and the regeneration reaction are switched alternately, the reforming reaction is changed to the regeneration reaction. It is possible to construct a system that can suppress deterioration of the catalyst at the time of switching, secure reforming efficiency for reforming and generating hydrogen from fuel, and stably perform stable power generation operation.

  According to the present invention, a hydrogen generator capable of avoiding catalyst deterioration accompanying a rapid temperature increase at the time of switching from a reforming reaction to a regeneration reaction, and performing reforming generation of hydrogen with high efficiency over a long period of time, and a high It is possible to provide a fuel cell system that can stably exhibit power generation performance with durability.

  Hereinafter, with reference to the drawings, 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. In the following embodiment, a case where combustion fuel is used as the heat generating fuel will be mainly described.

  An embodiment of a fuel cell system of the present invention will be described with reference to FIGS. 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. When the hydrogen generation apparatus of the present invention is installed in and the changeover from the reforming reaction to the combustion reaction is performed, the supply amount of combustion gasoline (combustion fuel) used for combustion immediately after the changeover is made smaller than the target amount (theoretical air-fuel ratio) In this configuration, the combustion reaction is started, and then the supply amount of combustion gasoline is gradually increased to the target amount. In addition, after switching from the reforming reaction to the combustion reaction, combustion gasoline is supplied from one of the injection devices on the condition that a predetermined time T has elapsed.

  The hydrogen generator of the present embodiment uses a single switching device having a reforming side passage through which a reforming raw material to be reformed and a regeneration side passage through which a combustion fuel to undergo a combustion reaction passes. The reforming reaction and regeneration reaction between two paired reforming reactors are alternately switched, and the hydrogen separation membrane fuel cell is generated by the hydrogen reformed and generated by this hydrogen generator. It is supposed to drive.

  As for a hydrogen generator, a mixed gas of gasoline and steam is used as a reforming raw material to be reformed by a reforming reaction, gasoline is used as a combustion fuel to be combusted during a regeneration reaction, and a hydrogen electrode ( The description will focus on the case of using a mixture of anode off-gas discharged from the anode side. However, the present invention is not limited to the following embodiment.

  As shown in FIG. 1, the present embodiment is provided with a catalyst and an injection device, and a first PSR reformer (PSR1) capable of alternately switching between a reforming reaction and a regeneration reaction. 10 and a second PSR reformer (PSR2) 20 and a hydrogen separation membrane fuel cell in which hydrogen generated by reforming in each PSR reformer is supplied to perform a power generation operation. (HMFC) 30 and a switching device 40 that simultaneously switches supply channels connected to each of the first and second PSR reformers.

  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 combustion gasoline and an anode (hydrogen electrode; the same applies below) a flow path for supplying off gas (combustion fuel) to the PSR reformer, an air for burning the combustion gasoline and anode off gas (hereinafter referred to as A switching means for switching a flow path for supplying “combustion air”) to the PSR reformer, and a flow path for discharging the reformed and generated hydrogen-rich gas from the PSR reformer; Specifically, the switching device 40 and a plurality of valves (valves V1 to V5) can be controlled by the control device 100.

  At one end of the first PSR reformer 10, an injection device 15 for injecting a mixed gas of gasoline and steam as reforming raw materials is attached, and a supply pipe 102 is connected via the injection device 15. In addition to being connected at one end, one end of the discharge pipe 105 is further connected so that combustion gas generated by the regeneration reaction (hereinafter also referred to as “combustion off-gas”) can be discharged from the other end of the discharge pipe 105. It has become.

  At the other end of the first PSR reformer 10, combustion gasoline that is burned during the regeneration reaction is discharged together with the anode off-gas discharged from a hydrogen separation membrane fuel cell (hereinafter also simply referred to as “fuel cell”) 30. An injection device 16 for injecting and an injection device 18 for injecting combustion-supporting air for burning combustion gasoline and anode off-gas are attached with a partition wall 19 provided in the container therebetween, It is connected at one end to a supply pipe 110 provided with a valve V6 via an injection device 16 and at one end to a supply pipe 112 via an injection device 18. Further, the other end of the PSR reformer 10 is provided with a valve V2 and connected to one end of a discharge pipe 117 that discharges the hydrogen-rich gas reformed and generated by the reforming reaction.

  Further, the side wall of the PSR reformer 10 on the side where the injection device 16 of the partition wall 19 is attached is further connected to one end of the supply pipe 111 branched in the middle of the supply pipe 110. Are further installed, and are configured so that combustion gasoline and anode off-gas can be supplied from two locations of the injection device 16 and the injection device 17.

  At one end of the second PSR reformer 20, an injection device 21 for injecting a mixed gas of gasoline and steam as a reforming raw material is attached, and a supply pipe 103 is connected via the injection device 21. In addition to being connected at one end, one end of the exhaust pipe 106 is further connected so that the combustion off-gas can be discharged from the other end of the exhaust pipe 106.

  Similarly to the PSR reformer 10, the other end of the second PSR reformer 20 is an injection device 23 for injecting combustion gasoline to be burned during the regeneration reaction together with the anode off-gas discharged from the fuel cell 30. An injector 22 for injecting combustion-supporting air for burning combustion gasoline and anode off-gas is attached with a partition wall 25 provided in the container, and is connected to a valve V7 via the injector 23. Is connected at one end to a supply pipe 113 provided with, and is connected at one end to a supply pipe 115 via an injection device 22. Further, the other end of the PSR reformer 20 is provided with a valve V3 and connected to one end of a discharge pipe 118 for discharging the hydrogen rich gas reformed and generated by the reforming reaction.

  Further, the injection device 24 connected to one end of the supply pipe 114 branched in the middle of the supply pipe 113 is further connected to the side wall of the PSR reformer 20 on the side where the injection device 23 of the partition wall 25 is attached. Is further installed, and is configured so that combustion gasoline and anode off-gas can be supplied from two locations of the injection device 23 and the injection device 24.

  The other ends of the supply pipe 102 and the supply pipe 103 are connected to the switching device 40, and further to the side to which the supply pipes 102 and 103 are connected (hereinafter also referred to as “reforming channel side”). The other end of a fuel supply pipe 104 that supplies a mixed gas (reforming raw material) prepared by mixing water vapor with gasoline supplied by a pump P1 attached to one end of the mixer 26 is connected and switched. By the switching operation of the apparatus 40, the fuel supply pipe 104 and the supply pipe 102 are communicated with each other, or the fuel supply pipe 104 and the supply pipe 103 are communicated with each other.

  The mixer 26 is connected to a discharge pipe 120 that discharges the cathode offgas discharged from the fuel cell 30, so that water contained in the cathode offgas is used as a steam source necessary for the steam reforming reaction of gasoline. It has become.

  In addition, on the side opposite to the reforming flow path side to which the supply pipes 102 and 103 and the fuel supply pipe 104 of the switching device 40 are connected (hereinafter also referred to as “regeneration flow path side”), the supply pipe 110 and the supply are provided. Each other end of the pipe 113 is connected to the other end of the fuel supply pipe 121 that is provided with a pump P2 at one end and supplies gasoline as combustion fuel to be burned during the regeneration reaction, and is the same as the reforming flow path side. In addition, by the switching operation of the switching device 40, the fuel supply pipe 121 and the supply pipe 110 are communicated with each other, or the fuel supply pipe 121 and the supply pipe 113 are communicated with each other.

  The other ends of the supply pipe 112 and the supply pipe 115 are connected to a three-way valve V1, and the supply pipes 112 and 115 are connected to the air (support) via a pump P3 attached to one end via the three-way valve V1. The air supply pipe 116 for supplying (combustion air) is communicated. The air supplied from the air supply pipe 116 can be selectively supplied to the regeneration-side PSR reformer to be regenerated by switching the three-way valve V1.

  Further, each of the other ends of the discharge pipe 117 and the discharge pipe 118 is one end of a hydrogen supply pipe 119 that supplies hydrogen-rich gas reformed and generated by the PSR type reformer connected at one end to the hydrogen separation membrane fuel cell 30. And one end of pipes 122 and 123 for sending the anode off-gas discharged from the fuel cell 30 to the PSR reformer are connected in the middle of the pipes of the supply pipes 110 and 113. By selectively switching between V2 and V5, an anode off-gas is selectively introduced into the regeneration-side PSR reformer, and a fuel cell using the hydrogen-rich gas generated and discharged in the reforming-side PSR reformer as a fuel for power generation 30 can be supplied.

  The injection devices 15 and 21 inject a mixed gas (reforming raw material) of gasoline and water vapor at a wide angle when the PSR reformer to which each is attached performs a reforming reaction, to the PSR reformer It can supply and react on the catalyst inside. The injectors 16 and 23 inject combustion gasoline at a wide angle together with the anode off-gas when the PSR reformer to which each of the injectors is attached performs a regeneration reaction, and the injectors 18 and 23 perform the injected combustion. By injecting combustion-supporting air for burning gasoline and anode off-gas for combustion, a combustion reaction can be performed on the catalyst incorporated in the PSR reformer.

  The hydrogen supply pipe 119 is further configured to store excess hydrogen-rich gas in a hydrogen storage tank (for example, a hydrogen storage device) separately attached, and when the hydrogen demand changes due to startup, 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.

  In addition, the pipes 122 and 123 are 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, and drive the throttle valve and supply hydrogen from the hydrogen buffer tank. By performing the above, it is possible to adjust the supply amount to the PSR reformer.

  The hydrogen separation membrane fuel cell 30 is connected on the anode (hydrogen electrode) side to the other end of the hydrogen supply pipe 119 and one end of a discharge pipe 124 capable of discharging and inserting the anode off-gas. The other end of 124 is connected to the other ends of the pipes 122 and 123. In addition, on the cathode (oxygen electrode) side, one end of an air supply pipe 125 that supplies air (oxidant gas) having a high oxygen content for power generation operation, and a discharge pipe 120 that discharges cathode offgas generated by the cell reaction. Is connected to the other end. As described above, the fuel cell 30 is configured to perform a power generation operation when the reformed and generated hydrogen and air are supplied, and to discharge off-gas (anode off-gas and cathode off-gas) to the outside of the cell after power generation. .

  In addition, a cooling pipe through which cooling air (cooling medium) supplied from the atmosphere is inserted may be provided inside the fuel cell 30 so that the inside of the battery can be cooled by heat exchange with the cooling air. . In this case, the cooling air discharged from the cooling pipe may be supplied to the regeneration side PSR reformer and used as combustion support air used for combustion during the regeneration reaction.

  As shown in FIG. 2, the first PSR reformers 10 and 20 include a cylindrical body 11 having a circular cross section with both ends closed, and a catalyst (catalyst supporting section) supported on the inner wall surface of the cylindrical body 11. ) 12, and 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.

  In the curved surface of the cylindrical body wall, the catalyst 12 has a predetermined distance A from the vicinity of the center of the cylinder from both ends in the length direction of the cylindrical body toward the in-cylinder direction, that is, from both ends in the length direction (see FIG. 2). Are left as catalyst non-supporting portions 12A and 12B that do not support a catalyst (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. Combustion gasoline and combustion support air 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.

  In the present embodiment, since both the combustion gasoline and the combustion support air necessary for the regeneration reaction pass through the catalyst non-supporting part 12A and are supplied into the chamber, the reforming reaction is switched again. Before, the catalyst non-supporting portion 12A can be cooled to a lower temperature, and the hydrogen-rich gas generated by switching to the reforming reaction again can be discharged after being sufficiently lowered in temperature.

  The cylindrical body 11 has a temperature sensor 29 for measuring the temperature near the center of the catalyst 12 and the vicinity of the catalyst non-supporting portion 12B of the catalyst 12, that is, in the supply direction of combustion fuel such as combustion gasoline. A temperature sensor 30 for measuring the temperature in the vicinity of the catalyst end is attached. The second PSR reformer 20 is configured in the same manner as the first PSR reformer 10, and is a reaction (reformation reaction) to be performed by the first PSR reformer 10. It is possible to switch between the reforming reaction and the regeneration reaction.

  As shown in FIG. 3, the switching device 40 is provided with three through holes that can be connected to a pipe, and fixed members 41 and 42 that are fixed substantially in parallel with each other at a predetermined interval. The first passage (reforming passage) 44 and the three penetrations of the fixing member 42 are disposed so as to be movable between the fixing member 41 and the fixing member 42 and communicate with two of the three through holes of the fixing member 41. And a movable portion 43 having a second flow path (regeneration flow path) 45 communicating two of the holes.

  When the reforming reaction is performed by the PSR reformer 10 and the regeneration reaction is performed by the PSR reformer 20, the movable portion 43 is moved in parallel to the state shown in FIG. The fuel supply pipe 104 and the supply pipe 102 are communicated with each other via the supply flow path 44, and the fuel supply pipe 121 and the supply pipe 113 are communicated with each other via the second flow path (regeneration flow path) 45. On the contrary, when the PSR reformer 10 causes the regenerative reaction and the PSR reformer 20 causes the reforming reaction by the switching operation of the switching device 40, the movable portion 43 is moved in parallel and shown in FIG. The fuel supply pipe 104 and the supply pipe 103 are communicated via the first flow path (reforming flow path) 44 and the fuel supply pipe 121 is connected via the second flow path (regeneration flow path) 45. And the supply pipe 110 are communicated with each other.

  As described above, the single switching device 40 can be used to simultaneously switch the reforming reaction and the regeneration reaction in the two reforming reactors 10 and 20 that make a pair. Thereby, switching malfunction is avoided and synchronism is ensured, and combustion of combustion fuel can be prevented from being started or reforming efficiency can be prevented from being lowered at a stage where the amount of oxygen is small.

As shown in FIG. 4, 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. 4, 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 hydrogen permeable material). When it is provided, a metal diffusion suppressing layer that suppresses diffusion of the different metals may be provided on at least a part of the contact interface of the different metals (see, for example, FIGS. 15 and 16). 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)

  As shown in FIG. 5, PSR reformers 10 and 20 (PSR reformer 1), hydrogen separation membrane fuel cell (HMFC) 30, switching device 40, temperature sensors 29 and 30, valves V1 to V7, pump P1 to P3, the injection devices 15 to 18 and the injection devices 21 to 24, the mixer 26, and the like 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 reaction control between the reforming reaction and the regeneration reaction in the PSR reformer (combustion control for making the air-fuel ratio at the time of the combustion reaction leaner than the stoichiometric air-fuel ratio when switching from the reforming reaction to the regeneration reaction) Also included).

  In the present embodiment, when the PSR reformer 10 performs the reforming reaction and the PSR reformer 20 performs the regeneration reaction, the movable portion 43 of the switching device 40 is operated to be as shown in FIG. In addition, the fuel supply pipe 104 and the supply pipe 102, the fuel supply pipe 121 and the supply pipe 113 are communicated with each other, and the valve V2 and the valve V5 are opened and the valve V3 and the valve V4 are closed, whereby the discharge pipe 117 and the hydrogen supply pipe 119 are connected. The supply pipe 113 and the pipe 123 are communicated with each other, and the air supply pipe 116 and the supply pipe 115 are communicated by switching the three-way valve V1.

  At this time, the mixed gas (reforming raw material) of gasoline and water vapor is supplied to the PSR reformer 10, and the combustion gasoline, the anode off-gas of the fuel cell 30 and the combustion support air are supplied to the PSR reformer 20. Supplied to each reaction. The mixed gas, which is the reforming raw material, is generated by mixing gasoline and moisture (water vapor) in the cathode off-gas from the discharge pipe 120 in the mixer 26, and is 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 generated by reforming as described above is cooled in advance by the catalyst non-supporting portion 12A on the side to which the discharge pipe 117 of the PSR reformer 10 is connected, and then inserted through the discharge pipe 117 and the hydrogen supply pipe 119. Then, the hydrogen is supplied to the anode side of the hydrogen separation membrane fuel cell 30 and is further supplied with air from the air supply pipe 125 provided on the cathode side to perform a power generation operation (cell reaction).

  After the supplied hydrogen rich gas is consumed in the power generation operation, it is discharged to the supply pipe 124 as an anode off gas, and the discharged anode off gas is inserted into the pipe 123 and the supply pipe 113 and sent to the injector 23 for combustion. It is mixed with gasoline and used for combustion reaction. The anode off gas mainly includes residual hydrogen that has not been subjected to the battery reaction.

  At this time, an air supply pipe 121 and a supply pipe 113 communicating with each other through the switching device 40 are inserted into the PSR reformer 20 side, and combustion gasoline is injected together with the anode off-gas from the injectors 23 and 24. 12 and when the combustion supporting air is supplied from the injection device 22 through the air supply pipe 116 and the supply pipe 115, the combustion reaction of gasoline proceeds, and the amount of heat stored by the combustion heating, that is, the catalyst temperature Can be recovered. That is, the catalyst 12 is heated and regenerated to a temperature higher than the reforming start temperature of the mixed gas of gasoline and steam.

  When the gasoline for combustion reaches the vicinity of the center of the supporting portion of the catalyst 12 by the partition wall 25 provided in the container, it comes into contact with combustion supporting air and causes a combustion reaction. Therefore, a mountain-shaped temperature distribution that is the highest temperature is formed near the center of the supporting portion of the catalyst 12 without causing backfire. As a result, the regeneration reaction can be completed and switched to the reforming reaction in a short time.

  At this time, the catalyst non-supporting portion 12A on the side of the PSR reformer 20 to which combustion gasoline and anode off-gas are 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 combustion gasoline and anode off gas supplied during the regeneration reaction, 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 106.

  When the reforming reaction is switched to the regeneration reaction as in the PSR reformer 20 described above, in the regeneration reaction according to the present invention, the combustion gasoline and anode off-gas injected from the injectors 23 and 24 at the time of switching are changed. After the supply amount is made smaller than a preset target value and the combustion reaction is started under the condition that the air-fuel ratio becomes leaner than the stoichiometric air-fuel ratio, the supply amount is gradually brought closer to the target value and burned. The same applies when the PSR reformer 10 undergoing the reforming reaction is switched to the regeneration reaction again after the reforming reaction is completed.

  Next, in the control routine by the control device 100 of the fuel cell system according to the present embodiment, when the PSR reformer 20 constituting the PSR reformer 1 is switched from the reforming reaction to the regeneration reaction, The fuel is burned with the air-fuel ratio leaner than the stoichiometric air-fuel ratio, and then the supply amount of combustion gasoline is gradually increased, and the temperature in the vicinity of the end of the catalyst 12 on the supply side of combustion gasoline and combustion support air is a predetermined value. An explanation will be made with reference to FIG. 6 focusing on a combustion control routine in which the injection from the injection device 23 is stopped and the gasoline for combustion is supplied only by the injection device 24.

FIG. 6 shows a combustion control routine. When this routine is executed, first, in step 100, the catalyst temperature t ^{1 of the} PSR reformer 20 that is undergoing the reforming reaction is taken in, and in the next step 102, the catalyst temperature t ¹ is changed to the reformable temperature T. It is determined whether or not ¹ or less (t ¹ ≦ T ¹ ), that is, whether or not the reforming reaction needs to be switched to the regeneration reaction.

When it is determined in step 102 that the catalyst temperature t ¹ is equal to or lower than the reformable temperature T ^1, it is necessary to switch the reforming reaction to the regeneration reaction. Therefore, in step 104, the switching device 40, the three-way valve V1, and the valve V2 to V5 are switched.

  Specifically, the movable unit 43 of the switching device 40 switches from the path shown in FIG. 3B to the path shown in FIG. 3-A, and the fuel supply pipe 104, the supply pipe 102, and the air supply pipe 121 The supply pipe 113 is connected to each other, the valve V2 and the valve V5 are opened, the valve V3 and the valve V4 are closed, the discharge pipe 117 and the hydrogen supply pipe 119, the supply pipe 113 and the pipe 123 are connected to each other, and the three-way valve V1 is connected. By switching and connecting the air supply pipe 116 and the supply pipe 115, the regeneration reaction switched from the reforming reaction in the PSR reformer 20, and the regeneration reaction in the PSR reformer 10, as described above. The reforming reaction switched from is performed.

When it is determined in step 102 that the catalyst temperature t ¹ still exceeds the reformable temperature T ¹ , the reforming reaction is performed and the temperature at which hydrogen can be reformed is maintained. This routine is terminated without switching to.

  Next, at step 106, the total supply amount of combustion gasoline and anode off-gas is made smaller than the target value for the PSR reformer 20, and the air-fuel ratio at the start of combustion (total amount of gasoline and anode off-gas / oxygen amount). ) Is driven so that the air-fuel ratio becomes leaner than the stoichiometric air-fuel ratio, and the supply of combustion gasoline is started, and in step 108, the pump P3 is driven to supply a target amount of combustion support air. Start. As a result, the regeneration reaction is started in a lean state that is less than the stoichiometric air-fuel ratio. At this time, the PSR reformer 10 is supplied with a mixed gas of gasoline and water vapor by driving the pump P1, and the reforming reaction is started.

  In this case, when liquid fuel such as gasoline is used, the liquid fuel is inferior in dispersibility at the time of supply. Therefore, in the aspect in which the liquid fuel is injected from one point, the fuel tends to exist locally and the fuel exists locally. The combustion reaction proceeds very rapidly only in the vicinity, and as shown in FIG. 7, the temperature of the catalyst exceeds the critical temperature for damage of the catalyst that impairs the reforming function, and the temperature becomes higher than necessary. At this time, while the high-temperature catalyst part deteriorates the reforming function with catalyst deterioration, the other catalyst parts cannot reach the reformable temperature at which the fuel reforming reaction can be started. Here, the temperature range between the reformable temperature and the catalyst damage limit temperature is a desirable range to be maintained during the regeneration reaction.

  Based on the above, in the present invention, the total amount of gasoline and anode off-gas to be supplied is made smaller than the target amount at which the stoichiometric air-fuel ratio is established, so that the air-fuel ratio at the time of combustion reaction is leaner than the stoichiometric air-fuel ratio. Since the control is performed, the catalyst can be regenerated to a reformable temperature between the reformable temperature and the catalyst damage limit temperature, and the catalyst does not deteriorate. In addition, it is configured to inject from two points, and by increasing the distributed supply of gasoline, a uniform temperature distribution can be achieved in a short time as shown in FIG. 8 while reducing the total amount of gasoline and anode off-gas supplied. Obtainable.

Next, in step 110, a temperature sensor 30 attached to the wall of the PSR reformer 20 near the end of the catalyst on the supply side of the combustion gasoline and combustion support air so that the catalyst temperature can be detected. The detected catalyst temperature t ² is taken in, and in the next step 112, it is determined whether or not the catalyst temperature t ² is equal to or higher than the reforming start temperature T ² .

When it is determined in step 112 that the catalyst temperature t ² is equal to or higher than the reforming start temperature T ² , the catalyst 12 of the PSR reformer 20 has been regenerated to a substantially uniform temperature that can be reformed. In step 114, the valve V7 is closed for a certain period of time to stop the supply from the injector 23, and the combustion gasoline and anode off gas are supplied from only the injector 24.

Sulfur and other catalyst poisoning components contained in gasoline and the like are likely to be concentrated and deposited on the catalyst located on the reforming raw material supply side. Therefore, as in this embodiment, combustion fuel such as gasoline for combustion is used. When the catalyst 12 located on the supply side reaches the reforming start temperature T ² at which reforming can be performed, the reforming raw material supply side is prevented so as not to cause an abnormal temperature rise as shown in FIG. The supply is performed only from the injection device 24, and as shown in FIG. 9, control is performed so that the catalyst temperature at the portion where the accumulation amount of poisoning components is large is raised, so that the accumulated poisoning components can be removed by combustion. it can.

  After the supply of combustion gasoline and combustion support air is started in the above step, in step 116, the drive of the pump P2 is gradually increased to increase the supply amount of combustion gasoline and gradually approach the target amount.

When it is determined in step 112 that the catalyst temperature t ² is lower than the reforming start temperature T ² , the catalyst 12 of the PSR reformer 20 is still regenerated to a substantially uniform temperature that can be reformed. Since there is not, it proceeds to step 116 as it is.

Then, in the next step 118, it is determined whether or not the supply amount p of combustion gasoline is less than the target value P. If it is determined that the supply amount p is less than the target value P, the process returns to step 110. After determining again whether the catalyst temperature t ² is equal to or higher than the reforming start temperature T ² , the supply amount of combustion gasoline is further increased until the supply amount p reaches the target value P.

  When it is determined in step 118 that the supply amount p has reached the target value P, this routine ends.

  As described above, when switching from the reforming reaction to the combustion reaction, the supply amount of air used for combustion in order to make the fuel amount / oxygen amount (air-fuel ratio) from the start of combustion leaner than the stoichiometric air-fuel ratio. The amount of combustion fuel supplied is reduced below a predetermined target amount, so that the catalyst temperature does not drop significantly due to heat exchange with the supplied air. The temperature can be effectively avoided, and the reforming function can be effectively prevented from being lowered due to catalyst deterioration while maintaining the heat utilization efficiency. Therefore, durability performance improves.

  Although the case where the regeneration reaction is switched from the reforming reaction in the PSR reformer 20 has been described here, the reforming reaction in the PSR reformer 10 is performed by switching the switching device 40 and the valves V1 to V5 as described above. The same applies when switching to a regeneration reaction.

In the combustion control routine described above, the stop of the injection of the injection device 23 in step 112 is determined that the switched catalyst temperature t ² has reached a predetermined temperature (reforming start temperature T ² ) as shown in FIG. As shown in FIG. 10, in step 210, the elapsed time t that has elapsed since the switching from the reforming reaction to the regeneration reaction in step 204 is integrated and acquired, and in the next step 212, as shown in FIG. Alternatively, it may be determined by determining whether or not the acquired elapsed time t has reached a predetermined reference time T. FIG. 10 shows that when the PSR reformer 20 is switched from the reforming reaction to the regeneration reaction, combustion is performed with the air-fuel ratio at the start of combustion leaner than the stoichiometric air-fuel ratio, and then the supply amount of combustion gasoline is gradually increased. In addition, a combustion control routine for stopping the injection from the injection device 23 and supplying the combustion gasoline only by the injection device 24 when a predetermined time elapses after switching is shown.

  In this combustion control routine, when it is determined in step 212 that the elapsed time t has reached the reference time T, the valve V7 is closed for a certain period of time to stop the supply from the injection device 23 and concentrate only from the injection device 24. To supply gasoline for combustion and anode off-gas. Note that Step 200 to Step 208 and Step 216 to Step 218 in FIG. 10 are the same as Step 100 to Step 108 and Step 116 to Step 118 in FIG.

  In the above-described embodiment, the case where the reforming gasoline supplied as the reforming raw material and the gasoline supplied for combustion during the regeneration reaction (combustion gasoline) are supplied through different paths has been described. It is also possible to configure such that the gasoline for combustion is supplied by the same route.

  In addition, the case where the PSR reformer is composed of a pair of PSR reformers that alternately perform the reforming reaction and the regeneration reaction has been described as an example. However, the PSR reformer has two or more pairs of PSR reformers. The same applies to the case of using a mass device.

  In the above embodiment, it is effective to provide an electric heater, an electric heating type catalyst, or the like as a heater for auxiliary heating of the catalyst. As a result, when switching from the reforming reaction to the combustion reaction as described above, if the supply amount of gasoline as the combustion fuel is reduced and the air-fuel ratio at the time of the combustion reaction becomes lean, the ignitability is increased. Can be prevented and combustion reactivity can be secured. It is also effective when the switching cycle between the reforming reaction and the regeneration reaction is made short. Specifically, it can be configured as shown in FIGS.

  In FIG. 11, an electrically heated catalyst (EHC) 31 is provided at the end of the catalyst 12 incorporated in the PSR reformer on the combustion fuel (combustion gasoline etc. and combustion support air) supply side. This is an example configured. Since the catalyst itself is heated, the regeneration reaction can be performed in a shorter time and the combustion reactivity can be ensured.

  FIG. 12 shows a pair of PSR reformers that form a pair, in the curved surface of the cylindrical body wall, in the vicinity of the center of the cylinder from both ends in the longitudinal direction of the cylindrical body toward the in-cylinder direction. EHC) 32, the catalyst 12 using the above-described metal sandwiching the EHC) 32, and an electrically heated catalyst (EHC) 31 provided so as to sandwich the EHC 32 and the catalyst 12 are supported. This is an example in which an electric heater (not shown) for heating the catalyst 12 is provided. When the reforming reaction is performed, the EHC 32 is heated by the EHC 31 on the gasoline (reforming raw material) supply side, and when the regeneration reaction is performed, the EHC 32 is heated by the EHC 31 on the combustion fuel (combustion gasoline etc. and combustion support air) supply side. When the amount of stored heat is insufficient during the reaction, the catalyst 12 can be heated with an electric heater. Since the catalyst itself is heated, the regeneration reaction can be performed in a shorter time and the combustion reactivity can be ensured.

  FIG. 13 shows the catalyst 12 using the above-mentioned metal in the vicinity of the center of the cylinder from the both ends in the length direction of the cylindrical body toward the in-cylinder direction among the curved surfaces of the cylindrical body wall constituting the PSR reformer. And a plurality of electrically heated catalysts (EHC) 31 are alternately arranged in a bundle. In this case, each EHC can be electrically selected and heated, and the catalyst having a shortage of heat can be selectively heated. It is effective to perform the regeneration reaction in a shorter time and ensure combustion reactivity.

  In the case where an electric heater, an electric heating type catalyst (EHC), or the like is provided, it is effective to selectively provide it at a portion having the highest temperature among the supporting portions provided to support the catalyst. In other words, the reforming reaction proceeds most rapidly at the highest temperature site, i.e., it does not change linearly with temperature, but proceeds rapidly at higher temperatures. Therefore, the heat energy efficiency can be improved.

  In the above embodiment, as shown in FIG. 14- (a), supply of both combustion gasoline (including anode off-gas) as combustion fuel and combustion support air is performed from one side of the PSR reformer. Although the case where it was made to supply was demonstrated, it can also comprise in the aspect as shown to FIGS. 14- (b)-(d) besides these.

  FIG. 14- (b) is configured to inject combustion gasoline (including anode off gas) and combustion support air in opposite directions from both ends of the PSR reformer, and cause a combustion reaction at the center of the reformer. It is an example. According to this configuration, it is possible to form a mountain-shaped temperature distribution that is the highest temperature near the center of the support portion of the catalyst 12, and is effective in securing the heat storage amount required for the reforming reaction, and is likely to occur during the regeneration reaction. Backfire can be effectively prevented.

  FIG. 14- (c) shows an example in which an injection device is attached to the wall surfaces facing each other in the vicinity of the center in the longitudinal direction of the PSR reformer, and combustion gasoline (anode off gas is injected from one side). In this example, the injection directions of the combustion support air injected from the other and the combustion support air injected from the other are substantially opposite to each other, so that they do not contact each other immediately after injection, that is, in the vicinity of the injection port. Also with this configuration, it is possible to prevent backfire that tends to occur during the regeneration reaction.

  FIG. 14- (d) shows an example in which one injection position of supplied combustion gasoline (including anode off-gas) and combustion support air is arranged downstream of the other injection position in the PSR reformer. It is. Also with this configuration, it is possible to prevent backfire that tends to occur during the regeneration reaction.

  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.

  15 to 16 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. 15 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. 16 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. 16, the hydrogen permeable layer using a hydrogen permeable metal is formed so as to sandwich the hydrous electrolyte layer, so that the moisture evaporation and membrane resistance of the electrolyte layer at 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. It is a schematic sectional drawing for demonstrating the place which switches a connection state using the switching apparatus 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 block diagram which shows the control apparatus which concerns on embodiment of this invention. It is a flowchart which shows the combustion control routine at the time of switching the PSR type | mold reformer which concerns on embodiment of this invention from a reforming reaction to a regeneration reaction. It is a figure for demonstrating the temperature distribution in a container in the conventional reproduction | regeneration reaction in which a catalyst temperature raises abnormal temperature rise at the time of a combustion reaction. It is a figure for demonstrating the internal temperature distribution when making it lean rather than a theoretical air fuel ratio, and injecting and burning from 2 points | pieces. It is a figure for demonstrating the internal temperature distribution when it burns by making one injection amount of 2 points | pieces of FIG. 8 larger than the other. 6 is a flowchart showing another example of a combustion control routine when a PSR reformer is switched from a reforming reaction to a regeneration reaction. It is a conceptual diagram which shows the structural example which provided the electrically heated catalyst in the edge part by the side of the fuel supply for combustion of a catalyst. It is a conceptual diagram which shows the other structural example which provided the electrically heated catalyst in the catalyst. It is a conceptual diagram which shows the other structural example which provided the electrically heated catalyst in the catalyst. It is a conceptual diagram which shows the supply form of the combustion gasoline and combustion support air supplied at the time of a combustion reaction. 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)
15, 16, 17, 18, 21, 22, 23, 24 ... injectors 30, 60, 70 ... hydrogen separation membrane fuel cell 40 ... switching device 51 ... electrolyte membrane 52 ... oxygen electrode 53 ... hydrogen electrode 59a ... air flow Path 59b ... Fuel flow path 100 ... Control devices V1-V7 ... Valve

Claims (14)

When a reforming material comprising a catalyst and containing fuel and water vapor is supplied, the reforming material is subjected to a reforming reaction on the heated catalyst, and when the heat generating fuel is supplied, the heat generating fuel is At least one reforming reactor that switches between the reforming reaction and the exothermic reaction so as to heat the catalyst by causing an exothermic reaction;
Fuel supply means for supplying the exothermic fuel to the reforming reactor;
When switching from the reforming reaction to the exothermic reaction, the supply amount of the exothermic fuel from the fuel supply means is made larger than a predetermined target amount so that the air-fuel ratio during the exothermic reaction becomes leaner than the stoichiometric air-fuel ratio. Combustion control means to reduce,
A hydrogen generation apparatus comprising:   The at least one reforming reactor includes at least a pair of reforming reactors that perform switching between the reforming reaction and the exothermic reaction alternately. One of the pair of reforming reactors is reformed. The hydrogen generator according to claim 1, wherein the hydrogen generator is reacted and the other is exothermic.   The fuel cell further comprises switching means for switching the reforming raw material supply flow path to the reforming reactor and the heat generating fuel supply flow path, and the combustion control means switches the supply flow path by the switching means. The hydrogen generator according to claim 1 or 2, wherein the reforming reaction and the exothermic reaction are switched.   The apparatus further comprises oxygen supply means for supplying an oxygen-containing gas for burning the exothermic fuel to the reforming reactor, and the reforming reactor includes the exothermic fuel and the oxygen-containing gas supplied during the exothermic reaction. The hydrogen generating apparatus according to any one of claims 1 to 3, further comprising a partition wall in the chamber that suppresses mixing with at least a part of the chamber.   The apparatus further comprises oxygen supply means for supplying an oxygen-containing gas for burning the exothermic fuel to the reforming reactor, and during the exothermic reaction, the exothermic fuel is supplied from one end of the reforming reactor and the other end The hydrogen generator according to any one of claims 1 to 3, wherein the oxygen-containing gas is supplied from a gas generator.   The hydrogen generator according to any one of claims 1 to 5, wherein an electric heater is disposed on a catalyst supporting portion on which the catalyst of the reforming reactor is supported.   The combustion control means changes the concentration of the exothermic fuel supplied by the fuel supply means so that the air-fuel ratio during the exothermic reaction becomes leaner than the stoichiometric air-fuel ratio. 2. The hydrogen generator according to item 1.   The hydrogen generating apparatus according to claim 1, wherein a plurality of the fuel supply units are provided in the reforming reactor, and the exothermic fuel is supplied to the reforming reactor from a plurality of portions. The plurality of fuel supply means are sequentially arranged in an insertion direction of an atmosphere that passes through the reforming reactor during an exothermic reaction,
The combustion control means supplies the exothermic fuel from the plurality of fuel supply means when switching from the reforming reaction to the exothermic reaction, and determines that a predetermined time has elapsed from the switching after the switching. 9. The hydrogen generation apparatus according to claim 8, wherein when the fuel is generated, the heat generating fuel is supplied from a part of the plurality of fuel supply means. The plurality of fuel supply means are sequentially arranged in an insertion direction of an atmosphere that passes through the reforming reactor during an exothermic reaction,
The combustion control means supplies the exothermic fuel from the plurality of fuel supply means when switching from the reforming reaction to the exothermic reaction, and after the switching, a predetermined portion of the reforming reactor is predetermined. The hydrogen generator according to claim 8, wherein when it is determined that the temperature has been reached, the fuel for heat generation is supplied from a part of the plurality of fuel supply means. The reforming reactor is configured such that the reforming raw material is supplied from one end and the exothermic fuel is supplied from the other end,
The predetermined portion is at least a part upstream of the center of the catalyst in the insertion direction during the exothermic reaction, and when it is determined that the catalyst in the at least part has reached a predetermined temperature, The hydrogen generator according to claim 10, wherein a supply amount of at least one of the heat generating fuel of the fuel supply unit disposed downstream of the central portion is made larger than that of the upstream side.   The switching means includes a flow path through which the fuel passes and a flow path through which the heat generating fuel passes, and a flow path for selectively switching the supply flow path connected to each of the pair of reforming reactors. The hydrogen generator according to claim 3, further comprising a switching member.   A fuel cell system comprising: the hydrogen generator according to any one of claims 1 to 12; 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 13, wherein the fuel cell includes an electrolyte in which an electrolyte layer is stacked on at least one side of a hydrogen permeable metal layer.

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