JP2007063038A - Hydrogen generator and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen generator excellent in the availability of heat, and to provide a fuel cell system using the hydrogen generator. <P>SOLUTION: The hydrogen generator 110 is equipped with: a couple of reactors 112, 114 which each has a catalyst carrying part 162 comprising a ceramic honeycomb structure carrying a catalyst and non-catalyst carrying parts 164, 166 provided at the both end parts of the catalyst carrying part 162 and each having a low thermal conductivity lower than that of the catalyst carrying part 162, and in each of which a hydrogen-containing gas is formed by a reforming reaction of gasoline or the like on the heated catalyst when the gasoline and a cathode offgas are supplied, the catalyst carrying part 162 is heated by the combustion reaction of an anode offgas or the like when the anode offgas and combustion air are supplied, and the reforming reaction and the combustion reaction can be switched; and a control part 170 for switching the raw material to be supplied to respective reactors to either of a reforming raw material and a heat generating raw material so that the reforming reaction and the combustion reaction are alternately performed in respective reactors 112, 114. The fuel cell system 100 has the hydrogen generator 110. <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, although the container wall thickness is thick and large, the internal volume is limited and the hydrogen filling amount is small. Further, in the case of liquefaction filling with liquid hydrogen, vaporization loss is unavoidable and a great deal of energy is required for liquefaction. 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 mounted, there is a method of obtaining hydrogen by steam reforming the fuel. However, since the reforming reaction is endothermic, a separate heat source is required. Therefore, a system using an electric heater or the like as the heat source cannot improve the overall energy efficiency. Furthermore, it is inevitable that the amount of hydrogen can be stably secured under all environmental conditions.

  The actual hydrogen supply method has not yet been established technically, but it is an urgent need to establish a hydrogen supply method in light of the anticipated increase in hydrogen utilization in various devices in the future. Has been.

  As a technology related to the above, a reformer that uses a catalyst to repeatedly perform a fuel reforming reaction that is an endothermic reaction and an exothermic reaction (regeneration reaction) that regenerates the catalyst temperature decreased by the reforming reaction. Has been proposed (see, for example, Patent Document 1).

  Moreover, a fuel cell using a hydrogen permeable material is disclosed as an example of a fuel cell system that performs a power generation operation in a high temperature range (see, for example, Patent Document 2). In addition to the above, various techniques related to this are disclosed (for example, see Patent Documents 3 to 5).

In such a fuel cell system, since the temperature decreased during the reforming reaction is regenerated by an exothermic reaction, it is important how to cope with the temperature decrease during the reforming reaction. For this reason, the technique which can fully maintain the temperature of the catalyst with which the reforming reactor was equipped was calculated | required.
U.S. Patent No. 2004-175326 JP 2004-146337 A U.S. Patent No. 2004-170558 US Patent No. 2004-170559 US 2003-235529

  As described above, although a fuel cell system using a reformer that reforms and generates hydrogen by switching between a reforming reaction and a regeneration reaction (exothermic reaction) has been proposed, measures against a temperature drop during the reforming reaction are proposed. Is not enough.

  An object of the present invention is to provide a hydrogen generator excellent in heat utilization efficiency and a fuel cell system using the same.

  The present invention relates to a steam reforming reaction of a reforming raw material, which is an endothermic reaction, and an exothermic reaction of a heat generating raw material for recovering the reforming reactivity on the catalyst by recovering the catalyst temperature lowered by the steam reforming reaction. (Hereinafter, also referred to as “regeneration reaction”), and a hydrogen generation device that repeats switching and a fuel cell using the same. The exothermic reaction 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 includes a catalyst supporting portion supporting a catalyst, and heat provided at both ends in the gas flow direction of the catalyst supporting portion, which is more heated than the catalyst supporting portion. A catalyst non-supporting portion made of a member having low conductivity is provided, and when a reforming raw material is supplied, a hydrogen-containing gas is generated by a reforming reaction of the reforming raw material on the heated catalyst, and an exothermic raw material When the catalyst is supplied, the catalyst is heated by an exothermic reaction of the exothermic raw material so that the reforming reaction and the exothermic reaction can be switched, and the reforming reaction of the reforming reactor And control means for switching the raw material supplied to the reforming reactor to either the reforming raw material or the exothermic raw material so that the exothermic reaction and the exothermic reaction are alternately performed.

Here, the “reforming reaction” in the present invention may include a “partial oxidation reaction” which is an exothermic reaction in addition to the “steam reforming reaction” which is the following endothermic 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)
CO + H ₂ O⇔CO ₂ + H ₂ (3)
_{CO + 3H 2 ⇔ CH 4 +} H 2 O ... (4)

  In the reforming reaction in the present invention, the steam reforming reaction (1) is mainly performed.

  According to the first aspect of the present invention, by using a reforming reactor provided with a catalyst non-supporting portion having a thermal conductivity lower than that of the catalyst supporting portion at both ends in the gas flow direction of the catalyst supporting portion, The release of the heat stored in the part can be suppressed by the catalyst non-supporting part having a low thermal conductivity. Thereby, the heat storage property of the reforming reactor is improved, and the heat utilization efficiency of the hydrogen generator can be improved.

  In the present invention, the raw material for reforming is a hydrocarbon fuel (for example, methane gas, gasoline) 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. Etc.) and a mixture of water vapor (moisture) can be used. In addition, the moisture in the reforming raw material is discharged from, for example, a cathode (air electrode; hereinafter the same) of a fuel cell and uses a gas containing moisture (hereinafter sometimes referred to as “cathode off-gas”). The reforming fuel can be supplied by humidifying or using humidified air.

  Examples of the heat generating material include a mixture of combustion fuel and air, and the combustion fuel can be appropriately selected from commonly used hydrocarbon fuels (for example, methane gas, gasoline, etc.). Furthermore, a gas containing hydrogen discharged from the anode (hydrogen electrode; hereinafter the same) (hereinafter sometimes referred to as “anode off gas”) may be used as the combustion raw material.

  Further, according to the first aspect of the present invention, the heat capacity of the catalyst supporting part can be configured to be higher than the heat capacity of the catalyst non-supporting part. The hydrogen generator according to the first aspect of the present invention can increase the amount of heat stored in the catalyst supporting part by using the catalyst supporting part having a higher heat capacity than the catalyst non-supporting part. Thereby, the heat storage property of the reforming reactor can be further improved.

  According to the first aspect of the present invention, the amount of the catalyst supported on the catalyst supporting portion can be configured to differ depending on the site. Since the steam reforming reaction is an endothermic reaction, the catalytic activity increases as the temperature increases. However, catalyst agglomeration (sintering) is likely to occur at high temperature sites, which may inhibit the reforming reaction. On the other hand, as in the first aspect of the present invention, if the catalyst carrying amount of the catalyst carrying unit is configured to be different depending on the site, the catalyst amount can be changed in accordance with the temperature distribution in the reforming reactor. Aggregation of the catalyst can be suppressed while improving the reforming capability of the entire catalyst supporting unit.

  Thus, in the hydrogen generator of the first aspect of the present invention, the amount of the catalyst supported on the catalyst supporting unit is configured to vary according to the temperature distribution in the reforming reactor during the reforming reaction. Preferably, the amount of the catalyst supported on the catalyst supporting unit is set such that the higher the temperature of the catalyst supporting unit, the higher the temperature of the catalyst supporting unit according to the temperature distribution in the reforming reactor during the reforming reaction. By reducing the number, the reforming ability can be enhanced while preventing aggregation of the catalyst in the high temperature part.

  In the hydrogen generator of the first aspect of the present invention, the amount of the catalyst supported on the side of the catalyst supporting unit to which the reforming raw material is supplied is the amount supported on the side of discharging the hydrogen-containing gas. It can also be set as the structure reduced rather than. In the steam reforming reaction, since the steam reforming reaction is performed by the heat stored in the catalyst in a state where no heat is supplied, the temperature distribution of the catalyst supporting portion is important. From this point of view, by reducing the amount of catalyst supported at the reforming gas introduction site, excessive steam reforming reaction (endothermic reaction) at the reforming gas introduction site is suppressed, and the inside of the catalyst supporting unit is kept at an ideal temperature. It is preferable to maintain the distribution.

  The hydrogen generator of the first aspect of the present invention comprises at least a pair of the reforming reactors, and the control means alternately switches the reforming reaction and the exothermic reaction of the pair of reforming reactors, The reforming reactor can perform a reforming reaction, and the other reforming reactor can perform an exothermic reaction. In this way, a reforming reactor (hereinafter referred to as “PSR (Pressure)” which can be switched between a reforming reaction of fuel using heat storage and an exothermic reaction (regeneration reaction) for recovering the amount of heat storage reduced by the reforming reaction. By providing a pair of “swing reforming” type reformers ”, at least one fuel reforming reaction can be performed, and at least one other reforming reaction can be performed (see FIG. Hereinafter, this hydrogen generator is sometimes referred to as “PSR reformer”.)

  For example, when there are two reforming reactors, one of them undergoes a reforming reaction that is an endothermic reaction using heat storage in the chamber, and the other is a regeneration reaction that is an exothermic reaction. When the amount of heat stored in one side decreases due to the progress of the reforming reaction, the flow paths of the raw materials to the two reforming reactors are switched, and the fuel is reformed by the heat stored in the regeneration reaction by the other reforming reactor. The regeneration reaction can be switched to the reforming reaction so that the quality is improved. This eliminates the need for a separate heater and enables continuous hydrogen generation with high use efficiency of heat energy.

  A fuel cell system according to a second aspect of the present invention includes the above-described hydrogen generator of the present invention and a fuel cell that generates electric power by supplying the hydrogen-containing gas reformed and produced in the reforming reactor. be able to.

  According to the second aspect of the present invention, the heat utilization efficiency of the entire system can be increased by using the hydrogen generator having high heat utilization efficiency.

  In the fuel cell system according to the second aspect of the present invention, the fuel cell includes a hydrogen permeable metal layer and an electrolyte layer disposed on at least one side of the hydrogen permeable metal layer. it can.

  The fuel cell including the hydrogen permeable metal layer and the electrolyte layer has an operating temperature range of 300 to 600 ° C. Since this temperature range is substantially the same as the reaction temperature range in which the steam reforming reaction proceeds, it has the advantage that the hydrogen-containing gas produced by steam reforming is supplied in the operating temperature range of the fuel cell, and the anode offgas is reduced. It can be returned to the PSR reformer as it is and used for the regeneration reaction. This is particularly suitable in terms of system configuration and effective use of thermal energy.

  ADVANTAGE OF THE INVENTION According to this invention, the hydrogen generator excellent in the utilization efficiency of a heat | fever and a fuel cell system using the same can be provided.

(First embodiment)
Hereinafter, embodiments of the fuel cell system of the present invention will be described in detail with reference to the drawings, and details of the hydrogen generator of the present invention will also be specifically described through the description.

  In the present embodiment, the present invention is applied to an electric vehicle equipped with a hydrogen separation membrane fuel cell (HMFC) in which a proton-permeable ceramic layer laminated on the surface of a hydrogen-permeable metal membrane is used as a battery membrane. The hydrogen generation apparatus is mounted, and the hydrogen separation membrane fuel cell is configured to perform a power generation operation using hydrogen reformed and generated by the hydrogen generation apparatus.

  In the present embodiment, gasoline and cathode offgas containing water are used as reforming raw materials that are reformed by a steam reforming reaction. In the present embodiment, a combustion reaction is used as an exothermic reaction (regeneration reaction), and a mixed fuel of a combustion fuel and a combustion gas is used as a heat generating material to be combusted during the regeneration reaction. In the present embodiment, anode off-gas discharged from the hydrogen electrode side of the fuel cell is used as the combustion fuel, and combustion air is used as the combustion gas. However, the present invention is not limited to such an embodiment.

  First, the basic configuration of the fuel cell system of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing the configuration of the fuel cell system according to the first embodiment. In FIG. 1, a fuel cell system 100 of the present invention includes a hydrogen generator 110 including a reactor 112 (PSR1) and a reactor 114 (PSR2), and a hydrogen separation membrane fuel cell 120 (HMFC). The hydrogen generation device 110 is configured to perform the power generation operation by supplying the hydrogen produced by reforming to the fuel cell 120.

  The reactor 112 and the reactor 114 shown in FIG. 1 each have a cylindrical configuration in which a catalyst is supported on a ceramic catalyst support, and further, a low thermal conductive ceramic honeycomb is provided at both ends of the catalyst support. Yes. The reactor 112 and the reactor 114 are further equipped with an injection device so that the reforming reaction and the regeneration reaction can be switched. Switching between the reforming reaction and the regeneration reaction includes a gasoline and cathode off-gas supply channel, an anode off-gas and combustion air supply channel, a reformed-generated hydrogen-containing gas discharge channel, and a regeneration reaction. The flow path of the regeneration off gas discharged from the reactor is configured to be controlled by controlling a plurality of valves (valves V1 to V8 and three-way valves SV1 to SV7). Here, the valves V <b> 1 to V <b> 8 are valves that are switched between passing and blocking of gas by opening and closing thereof. Further, three pipes are connected to the three-way valves SV1 to SV7, and any two pipes of the three pipes communicate with each other by driving the valves.

  The fuel cell system 100 of the present invention is configured to perform a steam reforming reaction in one reactor and to perform a regeneration reaction in the other reactor. In addition, since the steam reforming reaction is an endothermic reaction, the temperature of the reactor performing the steam reforming reaction is monitored, and when the temperature inside the reactor falls below a certain temperature, two reactors The fuel supplied to is switched to reverse the reforming and regeneration reactions. That is, in a reactor that has undergone a reforming reaction, a combustion raw material is supplied in place of the reforming raw material and the reforming gas, the reforming reaction is switched to the regenerative reaction, and the regenerative reaction is performed. In such a reactor, the reforming reaction is changed to the reforming reaction by supplying the reforming raw material and the reforming gas instead of the combustion raw material. At this time, the supply of the reforming raw material and the reforming gas and the supply of the combustion raw material are performed from the opposite sides in consideration of the temperature gradient in the reactor.

  In the operation of the fuel cell system 100 of the present invention, the reforming / regeneration reaction of each reactor is repeatedly switched. In this embodiment, for the sake of convenience, the reforming reaction is performed in the reactor 112. A case where the regeneration reaction is performed in the reactor 114 will be described.

  The basic structure of the fuel cell system of the present invention will be described. As shown in FIG. 1, on one side of the reactor 112 and the reactor 114, a fuel supply pipe 130B and a fuel supply pipe 130C connected to the fuel supply pipe 130A via the three-way valve SV1, respectively, are connected. The reforming raw material is supplied through these. Hereinafter, the side on which the reforming material is supplied, that is, the upstream side with respect to the flow direction of the reforming material may be referred to as the “reforming side”. The fuel supply pipe 130A is provided with a pump P1, and gasoline that is a reforming raw material is supplied to the reactor 112 by driving the pump P1. The fuel supply pipes 130B and 130C are provided with valves V1 and V5, respectively. Furthermore, each of the reactor 112 and the reactor 114 is provided with a temperature sensor 116 and a temperature sensor 118 for detecting the temperature in each reactor.

  On the other hand, one end of a hydrogen-containing gas discharge pipe 134A and one end of a hydrogen-containing gas discharge pipe 134B are connected to the other side of the reactor 112 and the reactor 114, respectively. Hereinafter, the side where the hydrogen-containing gas is discharged during the reforming reaction, that is, the downstream side with respect to the flow direction of the reforming raw material may be referred to as “regeneration side”. In the combustion reaction (regeneration reaction), the raw material for combustion is supplied from the regeneration side of each reactor.

  The other ends of the hydrogen-containing gas discharge pipe 134A and the hydrogen-containing gas discharge pipe 134B are connected to the three-way valve SV2, respectively. One end of an anode supply pipe 136 is further connected to the three-way valve SV2, and the anode supply pipe 136 and one of the hydrogen-containing gas discharge pipes 134A and 134B can be communicated with each other by switching the three-way valve SV2. ing.

  The other end of the anode supply pipe 136 is connected to the anode of the fuel cell 120, and a hydrogen-containing gas is supplied to the anode through the pipe. The anode of the fuel cell 120 is connected to the other end of the anode supply pipe 136 on the inlet side, and one end of the anode exhaust pipe 138A is connected to the outlet side. All the gas supplied to the anode of the fuel cell 120 is discharged through the anode exhaust pipe 138A. A three-way valve SV3 is connected to the other end of the anode exhaust pipe 138A, and is configured to communicate with either the anode exhaust pipe 138B or the anode exhaust pipe 138C by switching the three-way valve SV3.

  The anode exhaust pipe 138C is connected to the regeneration side of the reactor 114 at the other end, and is configured to be able to supply the anode off-gas discharged from the fuel cell 120. Further, the anode exhaust pipe 138C is provided with a mixer 139 connected to the combustion air supply pipe 140B. The combustion air supply pipe 140B is communicated with the combustion air supply pipe 140A via a three-way valve SV7. The combustion air is supplied to the mixer 139 by opening / closing the valve V2 provided in the combustion air supply pipe 140B and driving the pump P2. It is configured so that it can be supplied. The anode off gas discharged from the fuel cell 120 is mixed with the combustion air supplied from the combustion air supply pipe 140 </ b> B in the mixer 139 and supplied to the reactor 114. The anode exhaust pipe 138C is provided with a valve V3. Further, the three-way valve SV7 is provided with one end of a combustion air supply pipe 140C.

  A discharge pipe 142A is connected to the reforming side of the reactor 114, and the gas after the oxidation reaction can be discharged out of the system via the three-way valve SV4 and the discharge pipe 142B. Further, the discharge pipe 142A and the fuel supply pipe 130C connected to the reforming side of the reactor 114 are provided with valves V4 and V5, respectively.

  The discharge pipe 142A is configured to be able to communicate with the discharge pipe 142B or 142C via the three-way valve SV4. The other end of the discharge pipe 142C is connected to the three-way valve SV5.

  The anode exhaust pipe 138B is provided with a valve V6, and is connected to the regeneration side of the reactor 112 at the other end. Further, the anode pipe 138B is provided with a mixer 154 to which the other end of the combustion air supply pipe 140C is connected. Further, the combustion air supply pipe 140C is provided with a valve V8.

  One end of a cathode supply pipe 144 provided with a pump P3 is connected to the inlet side of the cathode (oxygen electrode; hereinafter the same) of the fuel cell 120, and air supplied from the cathode supply pipe 144 can be supplied to the cathode. It is configured as follows. Further, one end of a gas supply pipe 146A is connected to the cathode outlet side of the fuel cell 120 so that the cathode off-gas can be discharged.

  The other end of the gas supply pipe 146A is provided with a three-way valve SV5, and communicates with the gas supply pipe 146B via the three-way valve SV5. Further, the other end of the discharge pipe 142C is connected to the three-way valve SV5, and is configured to be able to communicate with either the discharge pipe 142C or the gas supply pipe 146B.

A three-way valve SV6 is connected to the other end of the gas supply pipe 146B, and one end of a gas supply pipe 146C having a valve V7 and a discharge pipe 148 are further connected to the three-way valve SV6. The other end of the gas supply pipe 146C is connected to the reforming side of the reactor 112, and is configured so that a cathode off-gas containing H ₂ O can be inserted into the reactor 112. The discharge pipe 148 is used to discharge the gas supplied from the gas supply pipe 146B to the outside of the system by switching the three-way valve SV6.

  Further, inside the fuel cell 120, a cooling pipe 150 for inserting cooling air sucked from the atmosphere is provided so that the inside of the cell can be cooled by heat exchange. .

  Next, the configuration of the reactor 112 and the reactor 114 will be described using the reactor 112 as an example. FIG. 2 is a schematic cross-sectional view for explaining the configuration of the reactor. As shown in FIG. 2, the reactor 112 includes a cylindrical body 160 having a circular cross section whose both ends are closed, a catalyst supporting part 162 supported on the inner wall surface of the cylindrical body 160, and catalyst non-supporting parts 164 and 166. The cylindrical body 160 forms a space for carrying out the reaction and functions as a catalyst carrier.

  The cylindrical body 160 includes a catalyst supporting portion 162 made of a ceramic honeycomb, and catalyst non-supporting portions 164 and 166 made of a ceramic honeycomb having lower thermal conductivity than the ceramic honeycomb provided at both ends thereof, and a circular cylinder having a cross section of 10 cm in diameter. A hollow body formed into a mold and closed at both ends in the longitudinal direction of the cylinder. 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 reactor 112 is located at the center of the reactor 112 by disposing a catalyst supporting portion 162 having a high thermal conductivity at the center and catalyst non-supporting portions 164 and 166 having a low thermal conductivity in the vicinity of the gas inlet / outlet. The escape of heat from the catalyst carrier 162 can be suppressed, and the heat storage property of the catalyst carrier 162 can be improved. Further, it is easy to configure a temperature distribution that is convex with respect to the axial direction (gas flow direction) of the reactor 112.

  In this embodiment, the thermal conductivity of the entire catalyst support 162 is about 5 to 10 W / m · K, and the thermal conductivity of the non-catalysts 164 and 166 is about 1 to 2 W / m · K. is there. The thermal conductivity ratio between the catalyst supporting part 162 and the catalyst non-supporting parts 164 and 166 is preferably about 5 to 10, more preferably about 10.

  The reactor 112 has a catalyst around the curved surface of the cylindrical body wall in the vicinity of the center of the cylinder from the both ends of the cylindrical body in the cylinder direction, that is, at a predetermined distance A from both ends in the length direction. The catalyst non-supporting portions 164 and 166 that are not supported are used, and the entire surface excluding them is a catalyst supporting portion 162 that supports the catalyst. As the catalyst supported on the catalyst support 162, metals such as Pd, Ni, Pt, Rh, Ag, Ce, Cu, La, Mo, Mg, Sn, Ti, Y, and Zn can be used.

  Further, the catalyst support 162 has ceramic honeycomb structures 167a to 167i (hereinafter sometimes simply referred to as “ceramic honeycomb structure 167”), but plate-shaped members 169a to 169h (hereinafter simply referred to as “plate-shaped”) having a metal honeycomb structure. It may be referred to as “member 169”.). The ceramic honeycomb structure 167 has a higher catalyst supporting capacity than the plate-like member 169, but the plate-like member 169 has better heat transfer than the ceramic honeycomb structure 167. As described above, the catalyst supporting portion 162 has a structure in which a catalyst layer made up of a plurality of ceramic honeycomb structures 167 and a metal layer made up of plate-like members 169 having a plurality of metal honeycomb structures are alternately laminated, thereby forming a catalyst. The in-plane temperature distribution in the reactor 112 (temperature distribution in the direction of arrow C in FIG. 2) can be made uniform while maintaining the catalyst supporting ability of the entire supporting section 162.

  In the present embodiment, the thermal conductivity of the ceramic honeycomb structure 167 is about 2 to 3 W / m · K, and the thermal conductivity of the plate member 169 is about 15 to 30 W / m · K. Further, the ratio of heat transfer between the ceramic honeycomb structure 167 and the plate member 169 is preferably about 5 to 15, more preferably about 15.

  Further, the catalyst supporting part 162 has a higher heat capacity than the catalyst non-supporting parts 164 and 166. Thus, by making the heat capacity of the catalyst supporting part 162 higher than the heat capacity of the catalyst non-supporting parts 164 and 166, the amount of heat that can be stored in the catalyst supporting part 162 increases, so that more reforming reactions can be performed. Become. For this reason, the number of switching of the reforming / regeneration reaction of the reactor can be reduced. In the present embodiment, the catalyst supporting part 162 has a cell structure of 4 to 6 mil and about 400 to 600 cpsi in order to increase the heat capacity, and the catalyst non-supporting parts 164 and 166 have a cell structure to reduce the heat capacity. It is about 2 to mil and 900 to 600 cpsi.

  However, in the present embodiment, the heat capacity of the catalyst carrier 162A (honeycomb structure 167h to 167i) which is a part of the catalyst carrier 162 is configured to be smaller than the other parts of the catalyst carrier 162. Has been. In this way, by providing a portion with a low heat capacity on the regeneration fuel introduction part side of the catalyst carrier 162, a part of the catalyst carrier 162 can be quickly raised to the reformable temperature. Thereby, the startability of the reforming reaction at the time of starting the system can be improved, and prompt hydrogen generation can be ensured.

  When the reforming reaction is performed by the catalyst supporting unit 162, the reformed and generated hydrogen-containing gas is cooled by the catalyst non-supporting unit 166 on the downstream side in the gas discharge direction, and the hydrogen-containing gas is brought to the operating temperature of the fuel cell 120. Can be supplied close. On the other hand, when the reforming reaction is switched to the regeneration reaction, the catalyst non-supporting portion 166 is in a state of being heated by heat exchange with the hydrogen-containing gas, and is opposite to the discharge direction of the hydrogen-containing gas. The supplied anode fuel and combustion air are preheated by the catalyst non-supporting portion 166 and then supplied to the catalyst supporting portion 162. As a result, a temperature distribution in which the amount of heat storage becomes higher is formed near the center of the cylindrical body 160 provided with the catalyst support 162, and this temperature distribution is not only advantageous in terms of reactivity, but also the working gas is reduced. Since it is supplied at a relatively low temperature and is discharged again at a relatively low temperature after passing through a high-temperature reaction zone, the heat that the exhaust gas takes away as sensible heat is kept small, which is advantageous in terms of energy efficiency. The tubular body 160 is attached with a temperature sensor 116 for measuring the temperature of the catalyst.

  Further, a fuel supply pipe 130B and a gas supply pipe 146C are connected to the reforming wall surface of the cylindrical body 160, and an injection device 168 is provided at the tip of the fuel supply pipe 130B. Further, a hydrogen-containing gas discharge pipe 134A and an anode discharge pipe 138B are connected to the wall surface on the regeneration side of the cylindrical body 160.

  When the steam reforming reaction is performed in the reactor 112 during normal operation, the injection device 168 injects gasoline (reforming raw material) at a wide angle and is embedded in the cylindrical body 160 together with moisture contained in the cathode offgas. The supply and reaction on the catalyst support 162 can be performed. In this case, the hydrogen-containing gas generated by the steam reforming reaction is exhausted from the hydrogen-containing gas discharge pipe 134A and supplied to the fuel cell 120.

  When the regeneration reaction is performed in the reactor 112 after switching from the reforming reaction, the catalyst carrier 162 provided in the cylindrical body 160 is supplied by supplying anode off-gas (and gasoline or hydrogen-containing gas if necessary). An anode off gas can be supplied to perform an oxidation reaction.

  Further, the amount of the catalyst supported on the catalyst support 162 varies depending on each part based on the ideal temperature distribution during the reforming reaction. That is, the amount of the catalyst supported on each of the ceramic honeycomb structures 167a to 167i is determined in accordance with an ideal temperature distribution in the reactor 112 during the reforming reaction.

  The relationship between the ideal temperature distribution during the reforming reaction and the amount of catalyst supported on the catalyst support 162 will be described with reference to FIG. FIG. 3 is an explanatory diagram for explaining the relationship between an ideal temperature distribution in the reforming reactor and the amount of catalyst supported during the reforming reaction.

  In the present embodiment, as shown in FIG. 3, a temperature distribution in which the temperature peak is located at the center of the catalyst support 162 is an ideal temperature distribution during the reforming reaction. Further, as shown in FIG. 3, the catalyst carrying amount of the catalyst carrying portion 162 is the largest at both ends (honeycomb structures 167a and 167i) of the catalyst carrying portion 162, and the central portion of the catalyst carrying portion 162. (Honeycomb structure 167e) has a concave distribution with the smallest amount of catalyst supported.

  If this is the ideal temperature distribution shown in FIG. 3, the temperature of both ends (honeycomb structures 167a and 167i) of the catalyst supporting portion 162 is lowered. For this reason, the reforming reaction is promoted by increasing the amount of catalyst supported at both ends of the catalyst support 162. On the other hand, since the central portion (honeycomb structure 167e) is at a high temperature, the reforming reaction is promoted even if the amount of catalyst supported is small. For this reason, it is possible to prevent the catalyst from aggregating excessively without reducing the amount of hydrogen-containing gas produced even if the amount of catalyst supported is reduced.

  In the present embodiment, the catalyst loading amount of the catalyst loading portion 162 is changed stepwise in a stepwise manner. However, the present invention is not limited to this, and the catalyst loading amount gradually varies according to the target temperature distribution. You can also

Next, the fuel cell 120 will be described with reference to FIG. FIG. 4 is a cross-sectional view for explaining the fuel cell in the present embodiment. As shown in FIG. 4, the hydrogen separation membrane fuel cell (HMFC) 120 includes a battery membrane 174 having a dense hydrogen permeable membrane using a hydrogen permeable metal, and an oxygen electrode (O ₂₎ sandwiching the battery membrane 174. Electrode) 176 and a hydrogen electrode (H ₂ electrode) 178. When the hydrogen-containing gas reformed and generated by the hydrogen generator 110 is supplied, hydrogen can be selectively permeated to perform power generation operation. It is like that.

  Between the oxygen electrode 176 and the battery film 174, an air flow path 180 for passing, that is, supplying and exhausting air (Air) as an oxidant gas is formed between the hydrogen electrode 178 and the battery film 174. A fuel flow path 182 for passing, that is, supplying and discharging hydrogen-rich fuel gas (here, reformed and produced hydrogen-containing gas) is formed. The oxygen electrode 176 and the hydrogen electrode 178 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 battery film 174 has a four-layer structure including a dense substrate (dense hydrogen permeable film made of hydrogen permeable metal) 184 formed of vanadium (V). Palladium (Pd) layers (dense hydrogen permeable membranes made of a hydrogen permeable material) 186 and 188 are arranged so as to sandwich the base material 184 from both sides, and are opposite to the side in contact with the base material 184 of one Pd layer 186. On the side surface, an electrolyte layer 190 made of BaCeO ₃ (solid oxide) is further provided in a thin film shape.

  The base material 184 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, which is advantageous in terms of cost.

Electrolyte layer (BaCeO ₃ film) 190 may 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 layer can be protected by providing a dense film using these.

  The dense film (coating film) made of the hydrogen permeable metal is generally made of vanadium (vanadium simple substance and vanadium-nickel alloy, etc.) on the oxygen electrode 176 side because it is generally high in hydrogen permeability 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, it is desirable to use them on the oxygen electrode 176 side in order to avoid hydrogen embrittlement. On the hydrogen electrode 178 side, for example, palladium or a palladium alloy is preferably used because hydrogen permeability is relatively high and hydrogen embrittlement is difficult.

  As shown in FIG. 4, a sandwich structure film composed of three layers of Pd layer 186 / base material 184 / Pd layer 188, that is, a laminated structure of two or more layers composed of different metals (dense film composed of a hydrogen permeable material). In this case, a metal diffusion suppression layer that suppresses diffusion of the different metals may be provided on at least a part of the contact interface of the different metals (for example, see FIGS. 7 and 8 described later). The metal diffusion suppressing layer is described in paragraph numbers [0015] to [0016] of JP-A No. 2004-146337.

  As the layer structure of the above sandwich structure film, in addition to the structure of palladium (Pd) / vanadium (V) / Pd, a five-layer structure such as Pd / tantalum (Ta) / V / Ta / Pd may be used. Is possible. As described above, V has a faster proton or hydrogen atom permeation rate than Pd and is inexpensive, but has a lower ability to dissociate hydrogen molecules into protons and the like. For this reason, hydrogen permeation performance can be improved by providing a Pd membrane having a high ability to protonate hydrogen molecules on one or both sides of the V membrane. In this case, by providing a metal diffusion suppression layer between the metal films, it is possible to suppress mutual diffusion between different kinds of metals and to suppress a decrease in hydrogen permeation performance, and thus a decrease in electromotive force of the fuel cell.

  The electrolyte layer 190 is made of a solid oxide, and a reaction suppression layer that suppresses the reaction between oxygen atoms in the electrolyte layer 190 and Pd may be provided at a part of the interface with the Pd layer 186 (for example, described later). Reaction suppression layer 210 in FIG. This reaction suppression layer is described in paragraphs [0024] to [0025] of JP-A No. 2004-146337.

  The battery membrane 174 is composed of a vanadium base material, which is a dense hydrogen-permeable material, and an inorganic electrolyte layer formed on the cathode side of the fuel cell 120, so that the battery membrane can be made thin. When applied to a high-temperature solid oxide fuel cell (SOFC) used, the operating temperature 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.

When a hydrogen-containing gas having a high hydrogen (H ₂ ) density is supplied to the fuel flow path 182 and air containing oxygen (O ₂ ) is supplied to the air flow path 180, the hydrogen separation membrane type fuel cell 120 will be described below. Electricity is supplied to the outside by causing an electrochemical reaction (battery reaction) represented by the formulas (1) to (3). 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)

  The switching of each valve will be described with reference to FIG. FIG. 5 is a configuration diagram for explaining the valve control. As shown in FIG. 5, the valves V <b> 1 to V <b> 8, the three-way valves SV <b> 1 to SV <b> 7, and the pumps P <b> 1 to P <b> 3 are connected to a control unit (CPU) 170, and their opening / closing and switching are controlled by the control unit 170. . The control unit 170 is connected to the temperature sensor 116 and the temperature sensor 118, and can monitor the temperature in the reactor 112 and the reactor 114. The controller 170 controls the valves and pumps according to the temperatures in the reactor 112 and the reactor 114, and can shift from the reforming reaction of each reactor to the regeneration reaction (combustion reaction). Furthermore, the control unit 170 can control the supply amount of gasoline (reforming raw material), cathode gas, and the like by controlling each pump.

  Next, a normal gas flow and control in the fuel cell system 100 according to the present embodiment will be described with reference to FIG. In FIG. 1, the exhaust pipe indicated by a thick line indicates a pipe used when a reforming reaction is performed in the reactor 112 and a regeneration reaction (combustion reaction) is performed in the reactor 114, and is indicated by white lines. The drainage pipe indicates a pipe that is not used in such a case. In addition, among the valves V1 to V8 shown in FIG. 1, a valve shown in white means that the valve is open, and a valve shown in black means that the valve is closed.

  In FIG. 1, when gasoline is first supplied from the fuel supply pipe 130A by driving the pump P1, it is supplied to the reactor 112 through 130B connected to the fuel supply pipe 130A by the three-way valve SV1. Here, in the present embodiment, the water used for the reforming reaction is a circulation type that supplies the cathode off-gas from the fuel cell 120, but if necessary, the water is supplied from outside the system together with the gasoline or separately from the gasoline. Can be configured to be supplied into the system.

  In the reactor 112 to which gasoline and moisture contained in the cathode off-gas are supplied, hydrogen is generated on the catalyst by a steam reforming reaction, and the hydrogen-containing gas is discharged to the hydrogen-containing gas discharge pipe 134A. At this time, the three-way valve SV2 is adjusted so that the hydrogen-containing gas discharge pipe 134A and the anode supply pipe 136 communicate with each other. The hydrogen-containing gas discharged from the reactor 112 is supplied to the anode of the fuel cell 120 through the hydrogen-containing gas discharge pipe 134A and the anode supply pipe 136, and is used for power generation of the fuel cell 120.

  The anode off gas containing surplus hydrogen that has not been protonated at the anode of the fuel cell 120 is discharged from the anode exhaust pipe 138A. At this time, the three-way valve SV3 is adjusted so that the anode exhaust pipe 138A and the anode exhaust pipe 138C communicate with each other, and the anode off-gas discharged to the anode exhaust pipe 138A is sent to the anode exhaust pipe 138C. Has been. The anode off gas sent to the anode exhaust pipe 138C is first supplied to the mixer 139 through this.

  At this time, the three-way valve SV7 is adjusted so that the combustion air supply pipes 140A and 140B communicate with each other, and the combustion air can be supplied to the mixer 139. Further, the valve V2 is controlled to be open.

  The anode off gas supplied to the mixer 139 is mixed with the combustion air supplied through the combustion air supply pipes 140A and 140B, and then supplied to the reactor 114. At this time, the valve V3 is controlled to be in an open state. In the present invention, a separate auxiliary fuel pipe may be provided so as to supply auxiliary combustion such as gasoline for assisting the regeneration reaction together with the anode off gas.

  At this time, in the reactor 114 as well as the reactor 112, a catalyst supporting part having a high thermal conductivity and a catalyst non-supporting part having a low thermal conductivity at both ends (reforming side and regeneration side) of the catalyst supporting part. Is provided. First, when an anode off gas mixed with combustion air is supplied to the reactor 114, the anode off gas causes a combustion reaction on the catalyst, and heat is accumulated in the catalyst support portion of the reactor 114.

  The off-gas of the combustion reaction is discharged from the reactor 114 via the discharge pipes 142A and 142B, and is discharged outside the system via a desulfurizer or the like (not shown). At this time, the valve V4 provided in the discharge pipe 142A is controlled to be opened, and the valve V5 provided in the fuel supply pipe 130C is controlled to be closed.

  On the cathode side of the fuel cell 120, air serving as an oxidant is supplied to the cathode of the fuel cell 120 through the cathode supply pipe 144 by driving the pump P <b> 3. Oxygen in the air supplied to the cathode reacts with protons that have passed through the electrolyte membrane and electrons that have passed through an external circuit (not shown) to produce water. The cathode off gas containing water is discharged to the gas supply pipe 146A.

  The three-way valves SV5 and SV6 are controlled so that the gas supply pipe 146A, the gas supply pipe 146B, and the gas supply pipe 146C communicate with each other, and the cathode off-gas sent from the cathode of the fuel cell 120 is the gas supply pipe 146A. To reactor 112 through ~ 146C. Thus, by sending the cathode offgas from the fuel cell 120 to the reactor 112 that performs the reforming reaction, the water contained in the cathode offgas can be used for the steam reforming reaction in the reactor 112. Thereby, for example, the amount of moisture supplied from outside the system can be reduced, and an efficient system can be configured.

  Further, during normal operation, cooling air is supplied to the cooling pipe 150, and the inside of the fuel cell 120 is cooled by heat exchange through the cooling pipe 150.

  Next, control of each valve and pump when the reaction in the reactor 112 is switched from the reforming reaction to the regeneration reaction (combustion reaction) will be described with reference to FIG. FIG. 6 is a flowchart showing the transition control from the reforming reaction to the regeneration reaction of the reactor 112 in the first embodiment. In FIG. 6, the controller 170 first supplies gasoline and cathode off-gas to the reactor 112 in order to perform a reforming reaction in the reactor 112 (PSR1) (step S111). At this time, a mixed gas of the anode off gas and the combustion air is supplied to the reactor 114 (PSR2).

  The controller 170 monitors the temperature in the reactor 112 in which the reforming reaction is performed while supplying gasoline and cathode off-gas to the reactor 112, and detects the temperature T1 in the reactor 112. (Step S112).

  Next, the controller 170 compares the temperature T1 detected by the temperature sensor 116 with a threshold T0 (for example, about 600 ° C.), and determines whether or not the temperature T1 is less than the threshold T0 (step S113). When the controller 170 determines that the temperature T1 is equal to or higher than the threshold T0 (No at Step S113), the control unit 170 returns to Step S111 and supplies gasoline and cathode off-gas to the reactor 112.

  On the other hand, when the controller 170 determines that the temperature T1 is less than the threshold (Yes at Step S113), the supply of gasoline and cathode offgas to the reactor 112 is stopped (Step S114). At this time, the controller 170 also stops supplying the anode off gas to the reactor 114.

  Next, the control unit 170 switches the reforming / regeneration reaction of each reactor, supplies the anode off gas and combustion air to the reactor 112, switches the reaction in the reactor 112 to the regeneration reaction, and reduces the reduced reactor interior. Is regenerated by a regeneration reaction (combustion reaction), and gasoline and cathode off-gas are supplied to the reactor 114, a reforming reaction is performed, and the switching process is terminated (step S115).

  In the above description, only the switching control from the reforming reaction to the regeneration reaction in the reactor 112 has been described, but the same control is performed when the reactor 114 switches from the reforming reaction to the regeneration reaction.

  In the above description, the case where gasoline is used as the reforming raw material has been described. However, the same configuration can be used when a hydrocarbon fuel other than gasoline is used.

  Next, another specific example of the hydrogen separation membrane fuel cell that can be diverted to the fuel cell 120 in the fuel cell system according to the first embodiment will be described with reference to FIGS. For details about other specific examples, reference can be made to the description in Japanese Patent Application Laid-Open No. 2004-146337.

FIG. 7 shows a battery film 202 having a five-layer structure including a dense substrate 212 formed of vanadium (V), an oxygen electrode (O ₂ electrode) 204 and a hydrogen electrode (H ₂ electrode) sandwiching the battery film 202. ) 206, and shows a hydrogen separation membrane fuel cell 200 having a metal diffusion suppression layer and a reaction suppression layer. The battery film 202 includes a dense metal diffusion suppression layer 214 and a palladium (Pd) layer 216 in order from the surface side on the surface of the base 212 on the hydrogen electrode (anode) 206 side. Further, a dense reaction suppression layer (for example, a proton conductor, a mixed conductor, or an insulator layer) 210 and a solid oxide are formed on the oxygen electrode (cathode) 204 side surface of the base material 212 in this order from the surface side. A thin electrolyte layer (for example, a metal oxide SrCeO ₃ film which is one of perovskites) 208. The reaction suppression layer 210 has a function of suppressing the reaction between oxygen atoms in the electrolyte layer 208 and the base material (V) 212. Note that an air flow path 180 and a fuel flow path 182 are formed between the oxygen electrode 204 or the hydrogen electrode 206 and the battery membrane 202 in the same manner as described above. Details of the metal diffusion suppression layer and the reaction suppression layer are as described above.

FIG. 8 includes a battery film 302 having a dense hydrogen permeable film using a hydrogen permeable metal, and an oxygen electrode (O ₂ electrode) 304 and a hydrogen electrode (H ₂ electrode) 306 that sandwich the battery film 302. The solid polymer type hydrogen separation membrane fuel cell 300 is shown. The battery membrane 302 has, for example, a multilayer structure in which the surfaces on both sides of the electrolyte layer 312 made of a solid polymer membrane such as a Nafion (registered trademark) membrane are sandwiched between dense hydrogen permeable metal membranes. A palladium (Pd) layer (dense film) 314 is provided on the surface on the hydrogen electrode (anode) 306 side of 312, and a vanadium serving as a base material in order from the surface side on the surface on the oxygen electrode (cathode) 304 side of the electrolyte layer 312. -A nickel alloy (V-Ni) layer (dense film) 310 and a Pd layer (dense film) 308 are provided. As described above, an air channel 180 and a fuel channel 182 are formed between the oxygen electrode 304 or the hydrogen electrode 306 and the battery membrane 302, respectively. Also in the fuel cell 120, a metal diffusion suppression layer can be provided between the V-Ni layer 310 and the Pd layer 308, and a reaction occurs between the V-Ni layer 310 or the Pd layer 314 and the electrolyte layer 312. A suppression layer can be provided.

  In the solid polymer type fuel cell shown in FIG. 8, the hydrogen permeable membrane using the 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 can be 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.

  As described above, in the first embodiment, the catalyst supporting part having high thermal conductivity is arranged at the center of the reforming reactor, and the catalyst non-supporting part having low thermal conductivity is arranged in the vicinity of the gas inlet / outlet. Thus, it is possible to make it difficult for heat to escape from the catalyst carrying portion located in the center of the reforming reactor, and it is possible to improve the heat storage property of the catalyst carrying portion. Further, it is easy to form a temperature distribution that is convex with respect to the axial direction (gas flow direction) of the reforming reactor. Thereby, the heat utilization efficiency of the hydrogen generator and the entire fuel cell system can be increased.

  Further, in the first embodiment, the amount of heat that can be stored in the catalyst supporting part can be increased by making the heat capacity of the catalyst supporting part of the reforming reactor higher than the heat capacity of the catalyst non-supporting part, More reforming reactions can be performed. For this reason, the number of switching of the reforming / regeneration reaction of the reactor can be reduced.

  Furthermore, in the first embodiment, the structure of the catalyst supporting part of the reforming reactor is a laminated structure of a catalyst layer having excellent catalyst supporting ability and a metal layer having better heat transfer than the catalyst layer. In addition, the in-plane temperature distribution in the reforming reactor can be made uniform while maintaining the catalyst supporting ability of the entire catalyst supporting portion.

  Further, in the first embodiment, the amount of catalyst supported by the catalyst supporting portion varies depending on the site, and according to the ideal temperature distribution during the reforming reaction, the amount of catalyst supported at the higher temperature is reduced, and the temperature of the lower temperature portion is decreased. By increasing the amount of catalyst supported, it is possible to prevent the catalyst from agglomerating due to high heat while maintaining the generation efficiency of the hydrogen-containing gas.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The reforming reactor described in the present embodiment is a reforming reactor that can be diverted to the reactors 112 and 114 in the fuel cell system 100 of the first embodiment.

  Hereinafter, the reforming reactor in the second embodiment will be described with reference to FIG. FIG. 9 is a schematic cross-sectional view for explaining the configuration of the reactor in the second embodiment. As shown in FIG. 9, the reactor 412 includes a cylindrical body 460 having a circular cross-section with both ends closed, a catalyst supporting part 462 supported on the inner wall surface of the cylindrical body 460, and catalyst non-supporting parts 464 and 466. The cylindrical body 460 forms a space for carrying out the reaction and also functions as a catalyst carrier.

  The cylindrical body 460 is formed by forming a catalyst supporting portion 462 integrated with a ceramic honeycomb and catalyst non-supporting portions 464 and 466 obtained by dividing the ceramic honeycomb provided at both ends thereof into a cylindrical shape having a circular cross section with a diameter of 10 cm. A hollow body in which both ends in the length direction of the cylinder are 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 carrier 462 disposed at the center of the reactor 412 is composed of an integrated ceramic honeycomb, and thus has no loss in thermal conductivity and has high thermal conductivity. On the other hand, since the catalyst non-supporting portions 464 and 466 arranged in the vicinity of the gas inlet / outlet of the reactor 412 are composed of divided ceramic honeycombs, there is a loss in thermal conductivity at the divided interface, Compared with the catalyst support 462, the overall thermal conductivity is low. For this reason, similarly to the reactor 112 in the first embodiment, it is difficult for heat to escape from the catalyst carrier 462 located at the center of the reactor 412, and the heat storage property of the catalyst carrier 462 can be improved. Further, it is easy to configure a temperature distribution that is convex with respect to the axial direction (gas flow direction) of the reactor 412.

  Reactor 112 has a catalyst around the curved surface of the cylindrical body wall in the vicinity of the center of the cylinder from the both ends of the cylindrical body in the longitudinal direction, that is, at a predetermined distance D from both ends in the longitudinal direction. The catalyst non-supporting portions 464 and 466 that are not supported are used, and the entire surface excluding them is a catalyst supporting portion 462 that supports the catalyst. As the catalyst supported on the catalyst supporting part 462, metals such as Pd, Ni, Pt, Rh, Ag, Ce, Cu, La, Mo, Mg, Sn, Ti, Y, and Zn are used as described above. it can.

  When the reforming reaction is performed by the catalyst supporting unit 462, the hydrogen-containing gas generated by reforming is cooled by the catalyst non-supporting unit 466 on the downstream side in the gas discharge direction, and the hydrogen-containing gas is brought to the operating temperature of the fuel cell 120. Can be supplied close. On the other hand, when the reforming reaction is switched to the regeneration reaction, the catalyst non-supporting portion 466 is in a state of being heated by heat exchange with the hydrogen-containing gas, and is opposite to the discharge direction of the hydrogen-containing gas. The supplied anode off-gas as combustion fuel is preheated by the catalyst non-supporting portion 466 and then supplied to the catalyst supporting portion 462. As a result, a temperature distribution in which the amount of heat storage becomes higher is formed near the center of the cylindrical body 460 provided with the catalyst support 462, and this temperature distribution is advantageous in terms of reactivity. The tubular body 460 is attached with a temperature sensor 116 for measuring the temperature of the catalyst.

  Further, the fuel supply pipe 130B and the gas supply pipe 146C in FIG. 1 are connected to the reforming side wall surface of the cylindrical body 460. Similarly, an injection device 468 is provided at the tip of the fuel supply pipe 130B. It has been. Further, a hydrogen-containing gas discharge pipe 134A and an anode discharge pipe 138B are connected to the wall surface on the regeneration side of the cylindrical body 460.

  In the case of performing a steam reforming reaction in the reactor 412 during normal operation, the injection device 468 injects gasoline (reforming raw material) at a wide angle and is housed in a cylindrical body 460 together with moisture contained in the cathode offgas. The supply and reaction on the catalyst support 462 can be performed. In this case, the hydrogen-containing gas generated by the steam reforming reaction is exhausted from the hydrogen-containing gas discharge pipe 134A and supplied to the fuel cell 120 in FIG.

  When the regeneration reaction is performed in the reactor 412 after switching from the reforming reaction, an anode off-gas (and gasoline or a hydrogen-containing gas, if necessary) is supplied, so that the catalyst support 462 built in the cylindrical body 460 is provided. An anode off gas can be supplied to perform an oxidation reaction.

  Further, in this embodiment, the amount of the catalyst supported on the reforming side by the catalyst supporting unit 462 is smaller than the amount of the catalyst supported on the regeneration side (discharge of hydrogen-containing gas (exit) side). It is configured. The relationship between the ideal temperature distribution and the amount of catalyst supported on the catalyst support 462 in the second embodiment will be described with reference to FIG. FIG. 10 is an explanatory diagram for explaining the relationship between the ideal temperature distribution and the amount of catalyst supported in the second embodiment.

In the present embodiment, as shown in FIG. 10, the temperature distribution peak in the reactor 412 is set to be on the regeneration side of the catalyst support 462. This is based on the following viewpoints. First, if there is a large amount of catalyst at the reforming gas introduction site, the reforming raw material will react somewhat excessively on the reforming side, so it may be difficult to maintain the ideal temperature distribution inside the catalyst carrier. is there. Next, since the steam reforming reaction is an endothermic reaction, the steam reforming reaction is promoted as the temperature increases. For this reason, when the temperature of the outlet side (regeneration side) of the hydrogen-containing gas in the catalyst support 462 is low, the hydrogen-containing gas may return to the original raw material. Further, the reforming reaction of methane is a reversible reaction such as “CH ₄ + H ₂ O ₃ H ₂ + CO”. In the reversible reaction, the peak moves to the regeneration side when the temperature is high, and the peak moves to the reforming side when the temperature is low. For this reason, if the temperature on the outlet side (regeneration side) of the catalyst carrier 462 is low, the amount of hydrogen gas produced may be unfavorable. From the above viewpoint, it is preferable to match the temperature peak in the reactor 412 to the regeneration side of the catalyst supporting unit 462, and the amount of catalyst supported on the regeneration side (exit side) of the catalyst supporting unit 462 contributes to the exothermic reaction. It is preferable to increase the number.

  For this reason, in this embodiment, as shown in FIG. 10, the temperature distribution in which the temperature peak is located on the regeneration side of the catalyst support 462 is set as an ideal temperature distribution. Therefore, as shown in FIG. 10, the catalyst carrying amount of the catalyst carrying unit 462 is the largest on the regeneration side of the catalyst carrying unit 462 (462C in FIG. 10).

  However, the temperature on the regeneration side (exit side) of the catalyst support 462 is not necessarily high, and the temperature shows an equilibrium limit. From the viewpoint of increasing the reaction speed, the inside of the reactor 412 A certain amount of heat is required as a whole. Considering these comprehensively, as shown in FIG. 10, the catalyst carrying amount of the catalyst carrying portion 462 in the reactor 412 of this embodiment is the reforming side and the center portion of the catalyst carrying portion 462 (462A in FIG. 10). And 462B) are set to an appropriate amount, and the amount of catalyst supported on the regeneration side (462C in FIG. 10) of the catalyst supporting portion 462 is maximized.

  As described above, in the second embodiment, the integrated catalyst supporting portion having high thermal conductivity is formed at the center of the reforming reactor, and the gas is divided into portions having low thermal conductivity near the gas inlet / outlet. By disposing the catalyst non-supporting portion, heat can be made difficult to escape from the catalyst supporting portion located in the central portion of the reforming reactor, and the heat storage property of the catalyst supporting portion can be improved. Further, it is easy to form a temperature distribution that is convex with respect to the axial direction (gas flow direction) of the reforming reactor. Thereby, the heat utilization efficiency of the hydrogen generator and the entire fuel cell system can be increased.

  Further, in the second embodiment, the amount of catalyst supported in the catalyst supporting portion differs depending on the site, and the reforming material introduction site is reduced by making the reformed catalyst supported amount smaller than the regeneration-side catalyst supported amount. While suppressing the excessive steam reforming reaction (endothermic reaction) in the catalyst, the temperature distribution can be such that the temperature peak is located on the regeneration side of the catalyst supporting part. Thereby, the utilization efficiency of the heat | fever of a hydrogen generator and the whole system can be improved further.

  In addition, the reforming reactor in the present invention is not limited to the above-described configuration. For example, the heat transfer area of the catalyst supporting part is increased to increase the heat transfer efficiency, and the reforming reactor is positioned at both ends of the catalyst supporting part. The effect of the present invention can also be achieved by reducing the heat transfer area by reducing the heat transfer area of the catalyst non-supporting portion.

  Moreover, you may comprise the reactor in this invention so that the exterior may be covered with a member with low heat conductivity, as shown in FIG. FIG. 11 is a schematic view showing another example of the reforming reactor of the present invention. As shown in FIG. 11, in the present invention, for example, by covering the reactor 112 in FIG. 1 with an outer covering member 500 having a low thermal conductivity, the heat storage property of the reactor 112 can be further improved. As the outer covering member 500, for example, inorganic fibers such as silica and alumina, ceramic fibers, and the like can be used.

It is the schematic which shows the structure of the fuel cell system of 1st Embodiment. It is a schematic sectional drawing for demonstrating the structure of a reactor. It is explanatory drawing for demonstrating the relationship between the ideal temperature distribution in the reforming reactor at the time of reforming reaction, and the load of a catalyst. It is sectional drawing for demonstrating the fuel cell in 1st Embodiment. It is a block diagram for demonstrating valve control. It is a flowchart which shows the transition control from the reforming reaction of the reactor 412 in 1st Embodiment to regeneration reaction. It is sectional drawing for demonstrating the other example of the fuel cell in this invention. It is sectional drawing for demonstrating the other example of the fuel cell in this invention. It is a schematic sectional drawing for demonstrating the structure of the reactor in 2nd Embodiment. It is explanatory drawing for demonstrating the relationship between the ideal temperature distribution and the load of a catalyst in 2nd Embodiment. It is the schematic which shows the other example of the reforming reactor of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Fuel cell system 110 Hydrogen generator 112,114,412 Reactor 120,200,300 Fuel cell 162,462 Catalyst support part 164,166,464,466 Catalyst non-support part 170 Control part 184,212 Base material 186,188 , 216, 308, 314 Palladium (Pd) layer 190, 208, 312 Electrolyte layer 310 Vanadium-nickel alloy (V-Ni) layer

Claims (9)

A catalyst supporting part supporting the catalyst, and a catalyst non-supporting part provided at both ends in the gas flow direction of the catalyst supporting part and having a lower thermal conductivity than the catalyst supporting part, are supplied with the reforming raw material. When the catalyst is heated, a hydrogen-containing gas is generated by a reforming reaction of the reforming raw material on the heated catalyst, and when the exothermic raw material is supplied, the catalyst is heated by an exothermic reaction of the exothermic raw material, and the reforming is performed. A pair of reforming reactors capable of switching between a quality reaction and the exothermic reaction;
Control for switching the raw material supplied to the reforming reactor to either the reforming raw material or the exothermic raw material so that the reforming reaction and the exothermic reaction of the reforming reactor are alternately performed. Means,
A hydrogen generation apparatus comprising:   The hydrogen generation apparatus according to claim 1, wherein a heat capacity of the catalyst supporting part is higher than a heat capacity of the catalyst non-supporting part.   The hydrogen generating apparatus according to claim 1 or 2, wherein the amount of the catalyst supported on the catalyst supporting portion is varied depending on a part.   4. The hydrogen generator according to claim 3, wherein the amount of the catalyst supported on the catalyst supporting unit is made different according to the temperature distribution in the reforming reactor during the reforming reaction.   The amount of the catalyst supported on the catalyst supporting part is decreased as the temperature of the catalyst supporting part is higher in accordance with the temperature distribution in the reforming reactor during the reforming reaction. Hydrogen generator.   The hydrogen according to claim 1 or 2, wherein an amount of the catalyst supported on the side on which the reforming raw material is supplied of the catalyst supporting unit is smaller than an amount supported on the side of discharging the hydrogen-containing gas. Generator.   The control means alternately switches the reforming reaction and the exothermic reaction of the pair of reforming reactors so that one reforming reactor performs the reforming reaction and the other reforming reactor The hydrogen generator according to any one of claims 1 to 6, wherein an exothermic reaction is performed. The hydrogen generator according to any one of claims 1 to 7,
A fuel cell that generates electricity by supplying a hydrogen-containing gas reformed and produced in the reforming reactor;
A fuel cell system comprising:   The fuel cell system according to claim 8, wherein the fuel cell includes a hydrogen permeable metal layer and an electrolyte layer disposed on at least one side of the hydrogen permeable metal layer.

Images