JP2005268056A - Hydrogen supply system and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen supply system and a fuel cell system, equipped with the hydrogen supply system capable of safely recycling unreacted hydrogen exhausted from the fuel cell with less energy back to the fuel cell or processing and exhausting it to the outside of the system. <P>SOLUTION: The hydrogen supply system is such that supplies hydrogen to a fuel cell generating power by electrochemical reaction with hydrogen and oxygen. The hydrogen supply system includes a hydrogen supply flow path 22 for supplying hydrogen to an anode side of the fuel cell, and hydrogen for returning flow path 23 for returning at least a part of unreacting hydrogen which do not react at the fuel cell to the anode side of the fuel cell, the latter mounted with an electrochemical hydrogen pump 24 electrochemically transporting hydrogen. The fuel cell system is equipped with the hydrogen supply system and the fuel cell. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hydrogen supply system and a fuel cell system, and more particularly to a hydrogen supply system suitably used for a fuel cell using hydrogen as a fuel and a fuel cell system including the hydrogen supply system.

  In a magnetically levitated linear motor vehicle, it has been studied that a vehicle power source used for air conditioning, lighting, etc., collects non-contact current with an induction current collector using electromagnetic induction (Patent Document 1).

  However, when the linear motor vehicle is traveling at a low speed, the induction current collector cannot obtain sufficient power, and therefore it is necessary to mount an auxiliary battery for supplying power during the low-speed traveling.

  However, the capacity of the auxiliary battery is limited, and there has been a problem that power cannot be supplied for a long time, particularly when the diamond is disturbed.

  Other on-board power systems for linear motor vehicles include gas turbine power generation systems, but gas turbine power generation systems emit dust and carbon dioxide during operation. The problem is big.

  Therefore, a fuel cell, particularly a polymer electrolyte fuel cell has been studied as an on-vehicle power supply system.

Since the polymer electrolyte fuel cell is operated at a relatively low temperature, the starting time is short, it is light and compact, and the noise is low. Also, because hydrogen is used as the fuel, the amount of products other than water is very small, so the exhaust gas is much cleaner compared to gas turbine power generation systems.
JP-A-8-186903

  However, in the polymer electrolyte fuel cell, all the supplied hydrogen is not consumed, and a part is discharged out of the system as unreacted hydrogen.

  Here, since part of the magnetically levitated linear motor railway is considered to be installed in the tunnel, it is safe to discharge unreacted hydrogen gas from a linear motor vehicle that is stopped and traveling in the tunnel. It is not preferable.

  As a solution to the above problem, a method of recycling unreacted hydrogen by circulating it through the fuel cell using a mechanical pump can be considered, but there is a problem that the required power is large.

  Further, if unreacted hydrogen is circulated and used, impurities in the hydrogen accumulate and the performance of the fuel cell deteriorates. Therefore, it is necessary to purge hydrogen gas intermittently.

  The present invention has been made to solve the above-mentioned problems, and hydrogen that can be recirculated to the fuel cell with less energy from unreacted hydrogen discharged from the fuel cell, or can be safely processed and discharged out of the system. An object of the present invention is to provide a fuel cell system that includes a supply system and the hydrogen supply system and is suitable as an on-vehicle power supply system for a linear motor vehicle.

  The invention described in claim 1 is a hydrogen supply system for supplying hydrogen to a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen, wherein the hydrogen supply flow supplies hydrogen to the anode side of the fuel cell. And a hydrogen return channel that returns at least a portion of unreacted hydrogen that has not reacted in the fuel cell to the anode side of the fuel cell, and in the hydrogen return channel, hydrogen is electrochemically supplied. The present invention relates to a hydrogen supply system including an electrochemical hydrogen pump for transfer.

  In the hydrogen supply system, hydrogen is electrochemically transferred by an electrochemical hydrogen pump.

  Therefore, since the hydrogen supply system is a static hydrogen recovery system, there is no moving part such as a mechanical pump. Therefore, the structure is simple, there are few failures, and it can be operated almost silently. Moreover, since isothermal compression is performed to transport unreacted hydrogen, energy consumption is small.

  In the hydrogen supply system, at least a part of unreacted hydrogen may be returned to the hydrogen electrode side of the fuel cell, and it is not always necessary to return the entire amount of unreacted hydrogen.

  Any electrochemical hydrogen pump can be used as long as it has a function of electrochemically transferring hydrogen.

  Examples of the fuel cell that can use the hydrogen supply system include a polymer electrolyte fuel cell. However, the fuel cell is not limited to a polymer electrolyte fuel cell as long as it is a fuel cell using hydrogen as a fuel.

  In addition, there are two modes for returning unreacted hydrogen to the hydrogen supply side of the fuel cell by an electrochemical hydrogen pump.

  The invention according to claim 2 is a hydrogen supply system for supplying hydrogen to a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen, wherein the hydrogen supply flow supplies hydrogen to the anode side of the fuel cell. A hydrogen return channel that returns unreacted hydrogen that has not reacted in the fuel cell to the anode side of the fuel cell, and a hydrogen purge channel that purges at least part of the hydrogen flowing through the hydrogen return channel. The hydrogen purge flow path is provided with an electrochemical hydrogen pump that electrochemically transfers at least part of the purged hydrogen and returns it to the anode side of the fuel cell. The present invention relates to a hydrogen supply system.

  In a fuel cell, hydrogen may be saved by circulating unreacted hydrogen to the anode side without discharging it out of the system. However, if unreacted hydrogen is simply circulated, impurities in the hydrogen accumulate and the performance of the fuel cell deteriorates. Therefore, a part of the circulating hydrogen is purged and at the same time fresh hydrogen is replenished so that impurities in the hydrogen do not accumulate on the anode side.

  However, when the fuel cell is used as an on-vehicle power source for a linear motor vehicle, the linear motor vehicle may stop and run in the tunnel, and the purged hydrogen is discharged as it is without being diluted. Is not preferable for safety.

  In the hydrogen supply system, the purged hydrogen is purified by the electrochemical hydrogen pump and returned to the fuel cell, so that the hydrogen partial pressure in the remaining purge gas can be lowered.

  A third aspect of the present invention relates to the hydrogen supply system according to the first or second aspect, wherein the hydrogen return flow path is connected to the hydrogen supply flow path.

  Since the hydrogen supply system has a hydrogen return channel connected to the hydrogen supply channel, there is no need to modify the anode side of the fuel cell when the hydrogen supply system is combined with the fuel cell.

  A fourth aspect of the present invention relates to the hydrogen supply system according to any one of the first to third aspects, wherein the fuel cell is a polymer electrolyte fuel cell.

  The hydrogen supply system is an example in which the hydrogen supply system of the present invention is used in a polymer electrolyte fuel cell. The polymer electrolyte fuel cell is particularly preferable as an on-vehicle power source for a linear motor vehicle as described in the section of “Background Art”.

  According to a fifth aspect of the present invention, in the hydrogen supply system according to any one of the first to fourth aspects, the amount of electric power supplied to the electrochemical hydrogen pump is controlled according to a load of the fuel cell. The present invention relates to a hydrogen supply system that increases or decreases the amount of hydrogen transferred.

  As the load on the fuel cell increases, the amount of hydrogen supplied increases, resulting in an increase in the amount of unreacted hydrogen discharged. However, in the hydrogen supply system, the amount of electric power supplied to the electrochemical hydrogen pump is controlled according to the load of the fuel cell. In such a case, the electric power is supplied to the electrochemical hydrogen pump. The amount of hydrogen returned to the fuel cell by increasing the amount of electric power can be increased. Therefore, even if the amount of unreacted hydrogen increases, it can be effectively recovered and reused, and even if the load on the fuel cell increases, the amount of unreacted hydrogen discharged outside the system can be suppressed to a small amount. .

  The invention according to claim 6 is the hydrogen supply system according to any one of claims 2 to 5, wherein the purge flow path is connected to a buffer tank for storing purged hydrogen, and The present invention relates to a hydrogen supply system for returning hydrogen in the buffer tank to the anode side of the fuel cell by the electrochemical hydrogen pump when the pressure in the buffer tank is higher than a set pressure.

  The hydrogen supply system includes a buffer tank that temporarily stores purged hydrogen, and the electrochemical hydrogen pump is operated when the pressure in the buffer tank is equal to or higher than a set pressure. There is no need to operate the electrochemical hydrogen pump at all times. Therefore, compared with the case where the electrochemical hydrogen pump is always operated, the electric power consumed by the electrochemical hydrogen pump can be further reduced, so that more electric power can be taken out from the fuel cell.

  The invention according to claim 7 is the hydrogen supply system according to any one of claims 1 to 5, wherein the hydrogen supply channel supplies hydrogen from a hydrogen container to the anode side of the fuel cell. A hydrogen supply system comprising a regulator for adjusting the pressure of hydrogen supplied from the hydrogen container, wherein the hydrogen return flow path is connected to a downstream side of the regulator in the hydrogen supply flow path. .

  Examples of the hydrogen container include a high-pressure container filled with hydrogen at a high pressure, a liquid hydrogen container filled with liquid hydrogen, and a container filled with a hydrogen storage alloy.

  The hydrogen supply system according to claims 6 and 7 is an example in which the hydrogen supply system of the present invention is applied to the fuel cell.

  The invention according to claim 8 is the hydrogen supply system according to any one of claims 1 to 7, wherein the electrochemical hydrogen pump includes an anode, a cathode, and an electrolyte layer disposed therebetween. A hydrogen supply system for supplying the unreacted hydrogen or purge hydrogen to the anode side and transferring the unreacted hydrogen or purge hydrogen from the anode to the cathode by applying a voltage to the anode and the cathode. About.

  In the electrochemical hydrogen pump used in the hydrogen supply system, a positive voltage is applied to the anode and a negative voltage is applied to the cathode. As a result, hydrogen introduced into the electrochemical hydrogen pump is converted into protons at the anode and moves through the electrolyte layer toward the cathode, and the moved protons are supplied with electrons at the cathode and returned to hydrogen. Therefore, even when unreacted hydrogen in which a large amount of impurities are accumulated is introduced into the electrochemical hydrogen pump, pure hydrogen is derived from the outlet side of the electrochemical hydrogen pump. The utilization rate can be increased. Further, impurities in hydrogen are inert, such as nitrogen and argon gas, and most of them are non-toxic, and the hydrogen partial pressure in the gas remaining on the introduction side of the electrochemical hydrogen pump is extremely low. Therefore, it is preferable for safety.

  The invention according to claim 9 relates to the hydrogen supply system according to claim 8, wherein the electrolyte layer of the electrochemical hydrogen pump is made of a solid polymer electrolyte.

  As described above, in the hydrogen supply system, since the electrochemical hydrogen pump is a solid polymer electrolyte, the electrochemical hydrogen pump can operate at a low temperature near normal temperature, has a short time to start, is lightweight, Compact and low noise.

  In addition, since the electrochemical hydrogen pump has almost the same structure as that of the solid polymer fuel cell, and only the operating conditions are different, when the polymer electrolyte fuel cell stack is used as the fuel cell, the stack is A part of the constituting cell can be used as the electrochemical hydrogen pump. In this case, instead of forming the hydrogen supply flow path, the hydrogen return flow path, and the hydrogen purge flow path by independent pipes, the grooves provided in the cells are replaced with the hydrogen supply flow path, the hydrogen return flow path, the hydrogen purge flow path, and the like. A road may be used. Accordingly, the hydrogen supply system can be formed integrally with the fuel cell, and can be configured to be extremely compact and robust.

  The invention according to claim 10 is a hydrogen supply system that supplies hydrogen to a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen, and supplies hydrogen from a hydrogen supply source to the anode side of the fuel cell. And an unreacted hydrogen discharge channel for discharging unreacted hydrogen out of the fuel cell, and the unreacted hydrogen discharge channel includes at least hydrogen discharged outside the system. The present invention relates to a hydrogen supply system characterized in that an electrochemical reactor for electrochemically oxidizing a part thereof is interposed.

  When the concentration of hydrogen discharged from the fuel cell is low or when the amount of hydrogen discharged is small, it may be inefficient to recover the hydrogen with an electrochemical hydrogen pump.

  However, electrochemical reactors can efficiently handle low concentrations of hydrogen. In the hydrogen supply system, the hydrogen discharged from the fuel cell is discharged after being oxidized by the electrochemical reactor, so there is no danger of explosion or the like. Further, in the electrochemical reactor, hydrogen is electrochemically oxidized, so that it can be oxidized at a normal temperature or a low temperature close to normal temperature without generating a flame, and safety is high. Therefore, it is suitable as an on-vehicle power supply system for a linear motor vehicle.

  The invention according to claim 11 is a hydrogen supply system for supplying hydrogen to a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen, wherein the hydrogen supply flow supplies hydrogen to the anode side of the fuel cell. A hydrogen return channel that returns unreacted hydrogen that has not reacted in the fuel cell to the anode side of the fuel cell, and a hydrogen purge channel that purges at least part of the hydrogen flowing through the hydrogen return channel. The hydrogen purge flow path is provided with an electrochemical reactor for electrochemically oxidizing at least part of the purged hydrogen.

  As described in the second aspect, when the fuel cell is used as an on-vehicle power source of the linear motor vehicle, it is not preferable for safety if the purge gas is discharged out of the vehicle as it is.

  In the hydrogen supply system, the purge gas after oxidizing hydrogen in an electrochemical reactor is discharged out of the system, so it is safe to use in semi-enclosed spaces such as tunnels, underground, and inside buildings. There is no problem.

  A twelfth aspect of the present invention is the hydrogen supply system according to the eleventh aspect, wherein the purge flow path is connected to a buffer tank that stores purged hydrogen, and there is pressure in the buffer tank. The present invention relates to a hydrogen supply system in which purge hydrogen in the buffer tank is introduced into the electrochemical reactor and oxidized when the pressure is higher than a set pressure.

  As described in the paragraph (6), the hydrogen supply system includes a buffer tank that temporarily stores purged hydrogen, and an electrochemical reaction when the pressure in the buffer tank is equal to or higher than a set pressure. Since the reactor is operated, it is not necessary to always operate the electrochemical reactor. Therefore, compared with the case where the electrochemical reactor is always operated, the electric power consumed by the electrochemical reactor can be further reduced, so that more electric power can be taken out from the fuel cell.

  A thirteenth aspect of the present invention relates to the hydrogen supply system according to any one of the tenth to twelfth aspects, wherein the fuel cell is a polymer electrolyte fuel cell.

  For the same reason as described in claim 4, the hydrogen supply system can also be suitably used for an on-board power supply system for a linear vehicle.

  The invention according to claim 14 is the hydrogen supply system according to any one of claims 10 to 13, wherein the electrochemical reactor includes an anode, a cathode, and an electrolyte layer disposed therebetween. The present invention relates to a hydrogen supply system that supplies unreacted hydrogen to the anode side and air or oxygen to the cathode side, and applies the voltage to the anode and cathode to react the supplied hydrogen with air or oxygen.

  The invention according to claim 15 relates to the hydrogen supply system according to claim 14, wherein the electrolyte layer of the electrochemical reactor is made of a solid polymer electrolyte.

  The electrochemical reactor used in the hydrogen supply system has almost the same configuration as the fuel cell, and the partial pressure of hydrogen supplied to the anode side is lower than that of the fuel cell. The driving point is different.

  Therefore, when a stack in which fuel cells are stacked is used as a fuel cell, a part of the fuel cells forming the stack can be used as an electrochemical reactor. Therefore, the hydrogen supply system is a fuel cell system. And can be integrated.

  A sixteenth aspect of the present invention is the fuel cell that generates power by an electrochemical reaction between hydrogen and oxygen, and the hydrogen is supplied to the anode side of the fuel cell. The present invention relates to a fuel cell system comprising a hydrogen supply system and an air supply channel for supplying air to the cathode side of the fuel cell.

  In the fuel cell system, at least a part of unreacted hydrogen is returned to the anode side by the hydrogen supply system, or is electrochemically oxidized and converted to water. Therefore, since unreacted hydrogen is not discharged out of the system while being raw, the exhaust can be discharged more safely out of the system.

  Furthermore, since the electrochemical hydrogen pump and the electrochemical reactor used in the hydrogen supply system are both static systems and have no mechanical moving parts, the configuration is simple and there are few failures. You can drive almost silently. Moreover, since isothermal compression is performed to transport unreacted hydrogen, energy consumption is small.

  The invention according to claim 17 is the fuel cell system according to claim 16, wherein the fuel cell is a stack in which a plurality of cells are stacked, and the electrochemical hydrogen pump or the electrochemical reactor is the fuel cell. The present invention relates to a fuel cell system incorporated in a stack.

  In the fuel cell system, it is not necessary to provide an electrochemical hydrogen pump or an electrochemical reactor separately from the fuel cell stack, so that the fuel cell system can be made compact.

  According to an eighteenth aspect of the present invention, in the fuel cell system according to the sixteenth or seventeenth aspect, the electrochemical hydrogen pump performs an electrochemical reaction according to the concentration or amount of unreacted hydrogen discharged from the fuel cell. The present invention relates to a fuel cell system that operates as a container.

  In the fuel cell system, since it is not necessary to provide an electrochemical reactor separately from the electrochemical hydrogen pump, the entire system can be made compact.

  As described above, according to the present invention, the unreacted hydrogen discharged from the fuel cell can be recycled to the fuel cell with less energy, or can be safely processed and discharged out of the system. A fuel cell system including a hydrogen supply system is provided.

1. Embodiment 1
An example of the fuel cell system according to the present invention will be described below.

  As shown in FIG. 1, the fuel cell system 200 according to Embodiment 1 supplies the fuel cell 4, the hydrogen supply system 2 that supplies hydrogen to the anode side of the fuel cell 4, and the air to the cathode side of the fuel cell 4. And an exhaust pipe 8 for discharging the exhaust gas generated by the reaction between hydrogen and air on the cathode side of the fuel cell 4.

  The fuel cell 4 includes an anode 42, a cathode 44, and a polymer electrolyte membrane 46 sandwiched between the anode 42 and the cathode 44. Each of the anode 42 and the cathode 44 is configured, for example, by carrying a platinum catalyst on a carbon fiber cloth. The anode 42 is provided on the hydrogen supply side, and the cathode 44 is provided on the air supply side. The polymer electrolyte membrane 46 is made of an anionic fluorine-based polymer having a skeleton in which a sulfonic acid group is bonded to a perfluorocarbon skeleton, such as Nafion (trade name) and Gore-select (trade name). The

  The hydrogen supply system 2 includes a hydrogen container 21 filled with hydrogen at a high pressure of about 350 to 700 atm, a hydrogen supply channel 22 for supplying hydrogen from the hydrogen container 21 to the anode side of the fuel cell 4, and the fuel cell 4. A hydrogen return channel 23 for returning unreacted hydrogen discharged from the anode side to the hydrogen supply channel 22, and a hydrogen return channel 23, which transfer the unreacted hydrogen toward the hydrogen supply channel 22. A hydrogen pump 24. The hydrogen pump 24 corresponds to the electrochemical hydrogen pump in the present invention. The hydrogen supply flow path 22 is provided with a regulator 25 that adjusts the pressure of hydrogen supplied from the hydrogen container 21 to about 1 to 10 atm.

  Similar to the fuel cell 4, the hydrogen pump 24 includes an anode 24A, a cathode 24B, and a polymer electrolyte membrane 24C sandwiched between the anode 24A and the cathode 24B. As the anode 24A, a Ti fiber sintered body carrying a Pt-Ir catalyst is used, and as the cathode 24B, a stainless steel fiber sintered body carrying a Pt catalyst is used. As the polymer electrolyte membrane 24C, an anionic fluorine-based polymer is used as in the fuel cell 4. The anode 24A is connected to the positive electrode of the DC power supply 24D, and the cathode 24B is connected to the negative electrode of the DC power supply 24D. Unreacted hydrogen is introduced to the anode 24A side of the hydrogen pump 24 and led out from the cathode 24B side.

  Hereinafter, the operation of the fuel cell system 200 will be described.

  In the fuel cell 4, when hydrogen is introduced from the hydrogen container 21 to the anode 42 side through the regulator 25 and the hydrogen supply flow path 22, a current from the cathode 44 toward the anode 42 is generated.

  Of the hydrogen supplied to the fuel cell 4, unreacted hydrogen that has not reacted at the anode 42 is introduced into the hydrogen pump 24 through the hydrogen return channel 23. Here, in the hydrogen pump 24, since a positive voltage is applied to the anode 24A and a negative voltage is applied to the cathode 24B, unreacted hydrogen introduced into the hydrogen pump 24 is deprived of electrons by the anode 24A. It becomes a proton and moves toward the cathode 24B. Then, electrons are received from the cathode 24B and returned to hydrogen molecules. Thus, in the hydrogen pump 24, hydrogen is transferred from the anode 24A side to the cathode 24B side. The hydrogen led out from the hydrogen pump 24 is returned to the outlet side of the regulator 25 in the hydrogen supply flow path 22 through the hydrogen return flow path 23.

  Next, an operation example of the fuel cell system 200 will be described. It is assumed that 20% of the supplied hydrogen is discharged as unreacted hydrogen on the anode 42 side of the fuel cell 4. In the hydrogen pump 24, 98% of the introduced hydrogen is transferred to the cathode 44 side.

  Therefore, 98% of 20% of unreacted hydrogen discharged from the anode 42 side is returned to the hydrogen supply flow path 22 by the hydrogen pump 24. Therefore, the hydrogen discharged from the exhaust pipe 24E in the hydrogen pump 24 is only 20% × 0.02 = 0.4% of the amount supplied to the fuel cell 4.

  In the hydrogen supply system 2 provided in the fuel cell system 200, hydrogen is transferred electrochemically by the hydrogen pump 24. Therefore, the hydrogen supply system 2 is a static hydrogen recovery system and has no movable parts such as a mechanical pump. Therefore, the structure is simple, there are few failures, and it can be operated almost silently. Moreover, since isothermal compression is performed to transport unreacted hydrogen, energy consumption is small.

  Moreover, since the unreacted hydrogen derived from the hydrogen pump 24 is extremely high-purity hydrogen, the recovery rate of the unreacted hydrogen can be set high.

  Further, since the hydrogen return flow path 23 is not directly connected to the anode side of the fuel cell 4 but is connected to the hydrogen supply flow path 22, the piping on the anode side of the fuel cell 4 can be used as it is.

  Furthermore, since the fuel cell 4 is a polymer electrolyte fuel cell, it can be operated at a low temperature and can be started in a short time. Moreover, it is lightweight and compact, and noise is low. Further, since hydrogen is used as the fuel, almost no products other than water vapor are produced, so that the exhaust gas is extremely clean. Therefore, it is particularly preferable as an on-vehicle power supply system for a linear motor vehicle. Further, since the hydrogen pump 24 has almost the same configuration as the polymer electrolyte fuel cell except that it does not supply air to the cathode side, it can be started in a short time like the fuel cell 4 and can be operated at a low temperature. In addition, the amount of hydrogen transferred can be freely controlled by changing the current and voltage applied to the anode and cathode. Therefore, when the load applied to the fuel cell 4 is large, the voltage and current applied to the hydrogen pump 24 are increased to increase the amount of unreacted hydrogen transferred. When the load applied to the fuel cell 4 is small, the voltage is applied to the hydrogen pump 24. The amount of hydrogen transferred in the hydrogen pump 24 can be increased or decreased according to the load applied to the fuel cell 4, for example, the amount of unreacted hydrogen transferred can be reduced by reducing the voltage and current to be applied.

2. Embodiment 2
Another example of the fuel cell system according to the present invention will be described below.

  As shown in FIG. 2, the fuel cell system 202 according to the second embodiment includes the fuel cell 4, a hydrogen supply system 3 that supplies hydrogen to the anode side of the fuel cell 4, and air to the cathode side of the fuel cell 4. And an exhaust pipe 8 for discharging the exhaust gas generated by the reaction between hydrogen and air on the cathode side of the fuel cell 4. 2, the same reference numerals as those in FIG. 1 indicate the same components as those shown in FIG. 1 unless otherwise specified.

  The hydrogen supply system 3 includes a hydrogen container 31 filled with hydrogen at a high pressure of about 350 to 700 atm, a hydrogen supply channel 32 that supplies hydrogen from the hydrogen container 31 to the anode 42 side of the fuel cell 4, and a fuel cell. 4, unreacted hydrogen discharge flow path 33 for discharging unreacted hydrogen that has not reacted to the outside of the system, and unreacted hydrogen discharged from the anode side of fuel cell 4 interposed in unreacted hydrogen discharge flow path 33. And a hydrogen reactor 34 for electrochemical oxidation. The hydrogen reactor 34 corresponds to the electrochemical reactor in the present invention. The hydrogen supply channel 32 is provided with a regulator 35 that adjusts the pressure of hydrogen supplied to the fuel cell 4 to about 1 to 10 atm.

  Similar to the fuel cell 4, the hydrogen reactor 34 includes an anode 34A, a cathode 34B, and a polymer electrolyte membrane 34C sandwiched between the anode 34A and the cathode 34B. As the anode 34A, the cathode 34B, and the polymer electrolyte membrane 34C, those similar to the anode 42, the cathode 44, and the polymer electrolyte membrane 46 of the fuel cell 4 can be used, respectively. The anode 34A is connected to the positive electrode of the DC power supply 34D, and the cathode 34B is connected to the negative electrode of the DC power supply 34D. Unreacted hydrogen is introduced to the anode 34A side, and air is supplied to the cathode 24B side from an air supply passage 36 branched from the air supply passage 6. Accordingly, a reaction similar to that of a normal fuel cell occurs on both the anode 34A side and the cathode 34B side, and unreacted hydrogen changes to protons on the anode 34A side, and the polymer electrolyte membrane 34C moves to the cathode 34B side. On the cathode 34B side, it is oxidized by oxygen in the air introduced by the air supply flow path 36 and changed to water. Therefore, the hydrogen reactor 34 has a function of electrochemically oxidizing unreacted hydrogen. A part of the unreacted hydrogen supplied to the anode 34A side is discharged out of the system as it is from the exhaust pipe 34E.

  The configuration other than the points described above is the same as that of the fuel cell system 200 of the first embodiment.

  Hereinafter, the operation of the fuel cell system 202 will be described.

  In the fuel cell 4, power is generated by introducing hydrogen from the hydrogen container 31 to the anode 42 through the regulator 35 and the hydrogen supply channel 32.

  On the other hand, of the hydrogen supplied to the fuel cell 4, unreacted hydrogen that has not reacted at the anode 42 is led out of the system from the unreacted hydrogen discharge channel 33, but in the middle of the unreacted hydrogen discharge channel. Since the hydrogen reactor 34 is provided, most of the unreacted hydrogen led out of the system from the unreacted hydrogen discharge flow path 33 is electrochemically oxidized in the hydrogen reactor 34 and converted into water vapor. Then, a part of the unreacted hydrogen is discharged from the exhaust pipe 34E as it is.

  In the hydrogen reactor 34, since unreacted hydrogen is electrochemically oxidized, it can be treated at room temperature. Therefore, the fuel cell system 202 is suitable for an on-vehicle power supply system of a linear motor vehicle because there is almost no risk of fire and safety is high. In addition, since the hydrogen reactor 34 can efficiently process low-concentration hydrogen, the fuel cell system 202 is suitable when the utilization rate of hydrogen in the fuel cell 4 is high and the amount or concentration of unreacted hydrogen is low. It is.

3. Embodiment 3
As shown in FIG. 3, the fuel cell system 204 according to the third embodiment supplies the fuel cell 4, the hydrogen supply system 5 that supplies hydrogen to the anode side of the fuel cell 4, and the air to the cathode side of the fuel cell 4. And an exhaust pipe 8 for discharging the exhaust gas generated by the reaction between hydrogen and air on the cathode side of the fuel cell 4. In FIG. 3, the same reference numerals as those in FIG. 1 denote the same constituent elements as those shown in FIG. 1 unless otherwise specified.

  The hydrogen supply system 5 includes a hydrogen container 51 filled with hydrogen at a high pressure of about 350 to 700 atm, a hydrogen supply channel 52 for supplying hydrogen from the hydrogen container 51 to the anode 42 side of the fuel cell 4, and a fuel cell. And a hydrogen return channel 53 that returns unreacted hydrogen that has not reacted in step 4 to the hydrogen supply channel 52. Similar to the fuel cell system 200 of the first embodiment, a regulator 55 that adjusts the pressure of hydrogen supplied to the fuel cell 4 to about 1 to 10 atmospheres is interposed in the hydrogen supply channel 52. The hydrogen return channel 53 is connected to the downstream side of the regulator 55 in the hydrogen supply channel 52, and a pump P that transfers unreacted hydrogen toward the hydrogen supply channel 52 is provided in the middle. . The pump P may be an electrochemical hydrogen pump such as the hydrogen pump 24 described in the first embodiment, but a normal mechanical pump such as a centrifugal pump is preferable. Therefore, a circulation channel through which unreacted hydrogen circulates is formed by the hydrogen supply channel 52, the anode 42 side of the fuel cell 4, and the hydrogen return channel 53.

  Further, in the hydrogen supply system 5, a hydrogen purge flow path 56 that purges a part of unreacted hydrogen circulating in the circulation flow path out of the system branches from the downstream side of the pump P in the hydrogen return flow path 53. ing.

  In the hydrogen purge flow path 56, in order from the upstream side to the downstream side, a purge flow rate adjustment valve 56A that adjusts the flow rate of purged hydrogen, a purge tank 57 that temporarily stores purged hydrogen, and unreacted purged A hydrogen pump 24 for transferring hydrogen toward the hydrogen return channel 53 is interposed. The downstream end of the hydrogen purge channel 56 is connected to the hydrogen return channel 53.

  Hereinafter, the operation of the fuel cell system 204 will be described.

  In the fuel cell 4, when hydrogen is introduced from the hydrogen container 51 to the anode 42 through the regulator 55 and the hydrogen supply channel 52, a current from the cathode 44 toward the anode 42 is generated.

  Of the hydrogen supplied to the fuel cell 4, unreacted hydrogen that has not reacted at the anode 42 is returned to the hydrogen supply flow path 52 through the hydrogen return flow path 53 and fresh hydrogen supplied from the hydrogen container 51. At the same time, the fuel cell 4 is supplied again.

  On the other hand, a part of the unreacted hydrogen circulating in the circulation channel is stored in the purge tank 57 through the hydrogen purge channel 56. The proportion of hydrogen to be purged among the unreacted hydrogen can be set by the purge flow rate adjusting valve 56A.

  When the pressure in the purge tank 57 exceeds the set value, the DC power supply 24D is turned on, and a DC current is supplied to the hydrogen pump 24. Therefore, unreacted hydrogen in the purge tank 57 is transferred toward the circulation channel by the hydrogen pump 24. Here, in the hydrogen pump 24, as described for the hydrogen pump 24 in the first embodiment, the introduced unreacted hydrogen is once converted into protons at the anode 24A and moves through the polymer electrolyte membrane 24C. Since the hydrogen gas is returned to the cathode 24B again, high-purity hydrogen is derived from the hydrogen pump 24. Therefore, high-purity hydrogen is returned to the hydrogen return channel 53, so that no impurities are accumulated in the circulation channel.

  Of the unreacted hydrogen introduced into the hydrogen pump 24, the amount not led out toward the circulation flow path is discharged as a purge gas from the exhaust pipe 24E. However, since the purge gas remains after removing hydrogen from unreacted hydrogen, the hydrogen partial pressure is low, and impurities such as nitrogen and argon are mostly present. Moreover, since the amount of purge gas itself is much smaller than that of unreacted hydrogen returned to the circulation flow path, safety is high even if the purge gas is discharged out of the system as it is.

  Furthermore, since the hydrogen pump 24 is operated only when the internal pressure of the purge tank 57 is equal to or higher than the set value, the energy consumed by the hydrogen pump 24 can be further reduced compared to the fuel cell system 200 of the first embodiment.

4). Embodiment 4
As shown in FIG. 4, the fuel cell system 206 according to Embodiment 4 supplies the fuel cell 4, the hydrogen supply system 7 that supplies hydrogen to the anode side of the fuel cell 4, and the air to the cathode side of the fuel cell 4. And an exhaust pipe 8 for discharging the exhaust gas generated by the reaction between hydrogen and air on the cathode side of the fuel cell 4. In FIG. 4, the same reference numerals as those in FIGS. 1 and 2 indicate the same constituent elements as those shown in FIGS. 1 and 2 unless otherwise specified.

  The hydrogen supply system 7 includes a hydrogen container 71 filled with hydrogen at a high pressure of about 350 to 700 atm, a hydrogen supply channel 72 for supplying hydrogen from the hydrogen container 71 to the anode 42 side of the fuel cell 4, and a fuel cell. And a hydrogen return channel 73 that returns unreacted hydrogen that has not reacted in step 4 to the hydrogen supply channel 52. Similar to the fuel cell system 200 of the first embodiment, the hydrogen supply flow path 72 is provided with a regulator 75 that adjusts the pressure of hydrogen supplied to the fuel cell 4 to about 1 to 10 atm. The hydrogen return channel 73 is connected to the downstream side of the regulator 75 in the hydrogen supply channel 72, and a pump P that transfers unreacted hydrogen toward the hydrogen supply channel 72 is provided in the middle. . Therefore, the hydrogen supply channel 72, the anode 42 side of the fuel cell 4, and the hydrogen return channel 73 form a circulation channel through which unreacted hydrogen circulates.

  The hydrogen supply system 7 further includes a hydrogen purge flow path 76 that purges a part of unreacted hydrogen circulating through the circulation flow path from the downstream side of the pump P in the hydrogen return flow path 73. ing.

  In the hydrogen purge flow path 76, a purge flow rate adjustment valve 76A for adjusting the flow rate of hydrogen to be purged, a purge tank 77 for temporarily storing purged hydrogen, and unreacted purge in order from the upstream side to the downstream side. A hydrogen reactor 34 for electrochemically oxidizing hydrogen is interposed.

  The hydrogen reactor 34 is formed such that an exhaust pipe 34E can be opened and closed. In FIG. 4, 34A, 34B, 34C, and 34D represent an anode, a cathode, a polymer electrolyte membrane, and a DC power source, respectively. The hydrogen reactor 34 is configured to operate with the exhaust pipe 34E being opened when the internal pressure of the purge tank 77 reaches a predetermined value or more.

  The configuration other than the points described above is the same as that of the fuel cell system 200 of the first embodiment.

  Hereinafter, the operation of the fuel cell system 206 will be described.

  In the fuel cell 4, electricity is generated by introducing hydrogen from the hydrogen container 71 to the anode 42 side through the regulator 75 and the hydrogen supply channel 72.

  As in the fuel cell system 204 of the third embodiment, unreacted hydrogen that has not reacted at the anode 42 among the hydrogen supplied to the fuel cell 4 passes through the hydrogen return channel 73 and passes through the hydrogen supply channel 72. The fuel cell 4 is supplied again together with the fresh hydrogen supplied from the hydrogen container 71.

  On the other hand, part of the unreacted hydrogen circulating in the circulation channel is stored in the purge tank 77 through the hydrogen purge channel 76. The ratio of hydrogen to be purged among the unreacted hydrogen can be set by the flow rate adjusting valve 76A.

  When the pressure in the purge tank 77 becomes equal to or higher than the set value, the DC power supply 34D is turned on, air is supplied from the air supply passage 36 provided on the cathode 34B side of the hydrogen reactor 34, and the hydrogen reactor 34 operates. Therefore, unreacted hydrogen in the purge tank 77 is electrochemically oxidized in the hydrogen reactor 34 and then discharged to the outside.

  In the fuel cell system 206 according to Embodiment 4, the purged hydrogen is electrochemically oxidized by the hydrogen reactor 34 and then discharged out of the system. Therefore, since the purged hydrogen is treated at or near room temperature, there is almost no risk of fire.

  Furthermore, since the hydrogen reactor 34 is operated only when the internal pressure of the purge tank 77 is equal to or higher than the set value, the energy consumed in the hydrogen reactor 34 can be further reduced compared to the fuel cell system 202 of the second embodiment. .

5). Embodiment 5
An example of a fuel cell system according to the present invention that includes a fuel cell stack in which a plurality of fuel cells are stacked will be described below.

  As shown in FIG. 5, the fuel cell system 208 of the fifth embodiment includes a fuel cell stack 104, a hydrogen supply system 102 that supplies hydrogen to each of the fuel cells 140 constituting the fuel cell stack 104, and a fuel cell. 140 has an air supply flow path 106 for supplying air to each of 140.

  The fuel cell stack 104 includes four fuel battery cells 140 and one hydrogen pump 24. The fuel cell 140 includes an anode 142, a cathode 144, and a polymer electrolyte membrane 146 sandwiched between the anode 142 and the cathode 144, respectively. The anode 142, the cathode 144, and the polymer electrolyte membrane 146 have the same configuration as the anode 42, the cathode 44, and the polymer electrolyte membrane 46 in the fuel cell 4 provided in the fuel cell system 200 of the first embodiment. In each fuel cell 140, hydrogen is supplied to the anode 142 side and air is supplied to the cathode 144 side.

  The hydrogen supply system 102 includes a hydrogen container 121 filled with hydrogen at a high pressure of about 350 to 700 atm, a hydrogen supply channel 122 that supplies hydrogen from the hydrogen container 121 to the anode side of each fuel cell 140, A hydrogen pump 24 that is a chemical hydrogen pump, an unreacted hydrogen introduction passage 123 that introduces unreacted hydrogen discharged from the anode side of each fuel cell 140 into the hydrogen pump 24, and a hydrogen that is led out from the hydrogen pump 24. And a hydrogen return channel 126 that returns the hydrogen to the hydrogen supply channel 122. A regulator 125 that adjusts the pressure of hydrogen supplied from the hydrogen container 121 to about 1 to 10 atmospheres is interposed in the hydrogen supply channel 122, and the hydrogen return channel 126 is connected to the regulator 125 in the hydrogen supply channel 122. Connected to the exit side.

  In the fuel cell system 208, hydrogen is supplied from the hydrogen container 121 to each fuel cell 140 through the regulator 125 and the hydrogen supply channel 122 to generate electricity.

  Unreacted hydrogen that has not reacted in each fuel cell 140 is introduced into the hydrogen pump 24 through the unreacted hydrogen introduction flow path 123, and is transferred through the hydrogen pump 24 from the anode 24A toward the cathode 24B. 24 is led out to the hydrogen return flow path 126 and returned to the hydrogen supply flow path 122.

  In addition to the features of the fuel cell system 200 according to the first embodiment, the fuel cell system 208 according to the fifth embodiment includes the fuel cell 140 and the hydrogen pump 24 combined into one stack to form the fuel cell stack 104. Therefore, it has the feature that it can be configured more compactly as a whole.

6). Embodiment 6
Another example of the fuel cell system according to the present invention that includes a fuel cell stack in which a plurality of fuel cells are stacked will be described below.

  As shown in FIG. 6, the fuel cell system 210 according to the sixth embodiment includes a fuel cell stack 114, a hydrogen supply system 103 that supplies hydrogen to each of the fuel cells 140 constituting the fuel cell stack 114, and a fuel cell. 140 has an air supply flow path 106 for supplying air to each of 140.

  The fuel cell stack 114 includes four fuel cells 140 and one hydrogen reactor 34. The fuel battery cell 140 is as described in the fifth embodiment.

  The hydrogen supply system 103 includes a hydrogen container 131 filled with hydrogen at a high pressure of about 350 to 700 atm, a hydrogen supply channel 132 that supplies hydrogen from the hydrogen container 131 to the anode side of each fuel cell 140, An unreacted hydrogen discharge channel 133 for discharging unreacted hydrogen from the anode side of the fuel cell 140 and a hydrogen reactor 34 interposed in the unreacted hydrogen discharge channel 133 are provided. A regulator 135 that adjusts the pressure of hydrogen supplied from the hydrogen container 131 to about 1 to 10 atm is interposed in the hydrogen supply channel 132.

  In the fuel cell system 210, unreacted hydrogen that has not reacted in each fuel cell 140 is introduced into the hydrogen reactor 34 through the unreacted hydrogen discharge channel 133, and is electrochemically oxidized in the hydrogen reactor 34. And discharged outside the system.

  In addition to the features of the fuel cell system 202 according to the second embodiment, the fuel cell system 210 according to the sixth embodiment forms the fuel cell stack 114 by combining the fuel cell 140 and the hydrogen reactor 34 into one stack. Therefore, it has the feature that it can be configured more compactly as a whole.

  The fuel cell system provided with the hydrogen supply system of the present invention can be suitably used as an on-vehicle power supply system for a linear motor vehicle, and can also be suitably used as a power supply system for an underground shopping center or a building. Furthermore, it can be suitably used for a fuel cell vehicle.

FIG. 1 is a block diagram showing an outline of a configuration of a fuel cell system according to Embodiment 1. FIG. 2 is a block diagram showing an outline of the configuration of the fuel cell system according to the second embodiment. FIG. 3 is a block diagram showing an outline of the configuration of the fuel cell system according to the third embodiment. FIG. 4 is a block diagram showing an outline of the configuration of the fuel cell system according to Embodiment 4. FIG. 5 is a block diagram showing an outline of the configuration of the fuel cell system according to Embodiment 5. FIG. 6 is a block diagram showing an outline of the configuration of the fuel cell system according to Embodiment 6.

Explanation of symbols

2 Hydrogen supply system 3 Hydrogen supply system 4 Fuel cell 5 Hydrogen supply system 6 Air supply flow path 7 Hydrogen supply system 21 Hydrogen container 22 Hydrogen supply flow path 23 Flow path 24 Hydrogen pump 24A Anode 24B Cathode 24C Polymer electrolyte membrane 24D DC power supply 31 Hydrogen container 32 Hydrogen supply channel 33 Unreacted hydrogen discharge channel 34 Hydrogen reactor 34A Anode 34B Cathode 34C Polymer electrolyte membrane 34D DC power supply 34E Exhaust pipe 36 Air supply channel 42 Anode 44 Cathode 46 Polymer electrolyte membrane 51 Hydrogen container 52 Hydrogen supply flow path 53 Flow path 55 Regulator 56 Hydrogen purge flow path 56A Purge flow rate adjustment valve 57 Purge tank 71 Hydrogen container 72 Hydrogen supply flow path 73 Flow path 75 Regulator 76A Purge flow rate adjustment valve 76 Hydrogen purge flow path 76A Flow rate adjustment valve 77 Purge tank 102 Hydrogen supply system 103 Hydrogen supply system 104 Fuel cell stack 106 Air supply flow path 114 Fuel cell stack 121 Hydrogen container 122 Hydrogen supply flow path 123 Unreacted hydrogen introduction flow path 131 Hydrogen container 132 Hydrogen supply flow path 133 Unreacted hydrogen discharge flow path 140 Fuel Cell 142 Anode 144 Cathode 146 Polymer Electrolyte Membrane 200 Fuel Cell System 202 Fuel Cell System 204 Fuel Cell System 206 Fuel Cell System 208 Fuel Cell System 210 Fuel Cell System

Claims (18)

A hydrogen supply system that supplies hydrogen to a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen,
A hydrogen supply channel for supplying hydrogen to the anode side of the fuel cell;
A hydrogen return flow path for returning at least part of unreacted hydrogen that has not reacted in the fuel cell to the anode side of the fuel cell;
Have
The hydrogen supply system, wherein an electrochemical hydrogen pump for electrochemically transferring hydrogen is interposed in the hydrogen return channel. A hydrogen supply system that supplies hydrogen to a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen,
A hydrogen supply channel for supplying hydrogen to the anode side of the fuel cell;
A hydrogen return flow path for returning unreacted hydrogen that has not reacted in the fuel cell to the anode side of the fuel cell;
A hydrogen purge flow path for purging at least part of the hydrogen flowing through the hydrogen return flow path,
A hydrogen supply system, wherein the hydrogen purge flow path is provided with an electrochemical hydrogen pump that electrochemically transfers at least part of the purged hydrogen and returns it to the anode side of the fuel cell. .   The hydrogen supply system according to claim 1, wherein the hydrogen return flow path is connected to the hydrogen supply flow path.   The hydrogen supply system according to claim 1, wherein the fuel cell is a polymer electrolyte fuel cell.   The hydrogen supply system according to any one of claims 1 to 4, wherein the amount of hydrogen transferred is increased or decreased by controlling an amount of electric power supplied to the electrochemical hydrogen pump in accordance with a load of the fuel cell. The purge flow path is connected to a buffer tank that stores purged hydrogen,
The hydrogen according to any one of claims 2 to 5, wherein when the pressure in the buffer tank is equal to or higher than a predetermined pressure, the hydrogen in the buffer tank is returned to the anode side of the fuel cell by the electrochemical hydrogen pump. Supply system. The hydrogen supply flow path is a flow path for supplying hydrogen from a hydrogen container to the anode side of the fuel cell, and a regulator for adjusting the pressure of hydrogen supplied from the hydrogen container is interposed,
The hydrogen supply system according to any one of claims 1 to 5, wherein the hydrogen return flow path is connected to a downstream side of the regulator in the hydrogen supply flow path.   The electrochemical hydrogen pump includes an anode, a cathode, and an electrolyte layer disposed therebetween, supplies the unreacted hydrogen or purge hydrogen to the anode side, and applies a voltage to the anode and the cathode. The hydrogen supply system according to claim 1, wherein the unreacted hydrogen or purge hydrogen is transferred from the anode toward the cathode.   The hydrogen supply system according to claim 8, wherein the electrolyte layer of the electrochemical hydrogen pump is made of a solid polymer electrolyte. A hydrogen supply system that supplies hydrogen to a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen,
A hydrogen supply channel for supplying hydrogen to the anode side of the fuel cell;
An unreacted hydrogen discharge passage for discharging unreacted hydrogen out of the system in the fuel cell;
The hydrogen supply system, wherein the unreacted hydrogen discharge flow path is provided with an electrochemical reactor that electrochemically oxidizes at least a part of hydrogen discharged outside the system. A hydrogen supply system that supplies hydrogen to a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen,
A hydrogen supply channel for supplying hydrogen to the anode side of the fuel cell;
A hydrogen return flow path for returning unreacted hydrogen that has not reacted in the fuel cell to the anode side of the fuel cell;
A hydrogen purge flow path for purging at least part of the hydrogen flowing through the hydrogen return flow path,
2. A hydrogen supply system, wherein the hydrogen purge flow path is provided with an electrochemical reactor that electrochemically oxidizes at least a part of purge hydrogen. The purge flow path is connected to a buffer tank that stores purged hydrogen,
The hydrogen supply system according to claim 11, wherein when the pressure in the buffer tank is equal to or higher than a set pressure, purge hydrogen in the buffer tank is introduced into the electrochemical reactor to be electrochemically oxidized.   The hydrogen supply system according to claim 10, wherein the fuel cell is a polymer electrolyte fuel cell.   The electrochemical reactor includes an anode, a cathode, and an electrolyte layer disposed therebetween, and supplies unreacted hydrogen or purge hydrogen to the anode side, air or oxygen to the cathode side, and the anode The hydrogen supply according to any one of claims 10 to 13, wherein power is generated by applying a voltage to the cathode and the cathode to react the supplied hydrogen with air or oxygen, or reacting the hydrogen with air or oxygen. system.   The hydrogen supply system according to claim 14, wherein the electrolyte layer of the electrochemical reactor is made of a solid polymer electrolyte. A fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen;
The hydrogen supply system according to any one of claims 1 to 15, wherein hydrogen is supplied to an anode side of the fuel cell.
A fuel cell system comprising an air supply channel for supplying air to the cathode side of the fuel cell.   The fuel cell system according to claim 16, wherein the fuel cell is a stack in which a plurality of cells are stacked, and an electrochemical hydrogen pump or an electrochemical reactor is incorporated in the fuel cell stack.   The fuel cell system according to claim 16 or 17, wherein the electrochemical hydrogen pump also operates as an electrochemical reactor according to the concentration or amount of unreacted hydrogen discharged from the fuel cell.

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