JP2007242522A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system having a high jet pump recycle property without increasing the amount of a supply hydrogen flow. <P>SOLUTION: A humidification system 5 exchanges the moisture of an anode offgas being a humid gas supplied from a recycle path 7 with a dry hydrogen gas supplied from a regulation valve 3 to moisturize the dry hydrogen gas. The moisturized hydrogen gas increased in its weight for its density is increased is supplied as the driving flow of the jet pump 6. The anode offgas whose steam content is decreased in the humidification system 5 is supplied to the inlet hole of the jet pump 6 by the recycle pump 8. The jet pump 6 draws in the anode offgas flow to be drawn having density decreased for the reduction of the steam component by using the moisturized heavy driving flow to supply the mixed flow thereof to the anode 1a of the fuel cell 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell system that mixes anode off gas and newly supplied fuel gas using a jet pump.

  In a fuel cell system, in order to secure the supply amount of fuel gas to the electrolyte end of the fuel cell body, more fuel gas is supplied than the flow rate required for power generation, and the unreacted fuel gas (circulation gas) discharged is discharged. Some are equipped with a jet pump such as an ejector to supply the fuel cell again.

Some solid polymer fuel cells humidify hydrogen downstream of the jet pump in order to promote ionization of hydrogen at the anode or to exert hydrogen ion conductivity of the polymer electrolyte membrane (for example, Patent Document 1).
Japanese Patent Laying-Open No. 2004-171816 (page 4, FIG. 3)

  However, in the conventional fuel cell system, circulating gas is drawn in by negative pressure generated by injecting newly supplied hydrogen into an orifice of a jet pump or the like, but hydrogen (molecular weight 2) which is the lightest gas. ) As a driving flow, relatively heavy circulation gas containing nitrogen (molecular weight 28), water vapor (molecular weight 18), etc. is drawn into the main component hydrogen, so the ability to generate negative pressure is limited and high circulation performance cannot be demonstrated. There was a problem.

  In other words, the energy source of the driving flow is the pressure energy of hydrogen gas, but the momentum and kinetic energy that can be given to hydrogen with a small mass is reduced. Although the jet pump performance can be improved by increasing the flow rate of the supplied hydrogen itself, the upper limit of the hydrogen supply amount at the rated operating conditions is often determined by the system, and the jet pump is pulled in by the maximum supply hydrogen amount Circulating gas flow rate is limited.

  In view of the above problems, an object of the present invention is to provide a fuel cell system in which a high circulation property of a jet pump can be obtained without increasing the supply hydrogen flow rate.

  In order to solve the above problems, the present invention provides a fuel cell that generates power by an electrochemical reaction between a fuel gas and an oxidant gas, and a fuel gas that is newly supplied to the fuel cell as a driving flow. A jet pump that sucks the discharged anode off gas and supplies a mixed gas obtained by mixing a newly supplied fuel gas and an anode off gas to the fuel cell, and a driving flow density increasing means for increasing the gas density of the driving flow of the jet pump And a fuel cell system having the gist of the above.

  In the present invention, when the driving flow density increasing means increases the gas density of the driving flow of the jet pump, the absolute value of the negative pressure generated in the jet pump increases, and the suction capacity of the jet pump for sucking the circulating gas increases. As a result, a mixed gas obtained by sucking more circulating gas into the jet pump and mixing it with the driving flow can be supplied to the fuel cell.

  Driving flow density increasing means for increasing the gas density of the driving flow of the jet pump includes humidifying means for humidifying the driving flow, means for mixing an inert gas such as nitrogen into the driving flow, A jet pump having a variable restrictor capable of increasing the pressure and reducing the flow rate of the driving flow in accordance with the increase in the driving flow pressure is included.

  According to the present invention, by increasing the gas density of the driving flow of the jet pump, the driving flow can be increased, and the circulation performance of the jet pump is improved. In addition, since the suction flow rate can be increased, when a hydrogen circulation pump is used to circulate the circulating gas, the power consumption of the hydrogen circulation pump is reduced and the overall fuel efficiency of the fuel cell system is improved. There is. Further, since the effect of reducing the rotation speed of the hydrogen circulation pump can be expected, there is an effect that the acoustic vibration level characteristic of the fuel cell system can be improved.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. Each embodiment described below is not particularly limited, but is a fuel cell system suitable as a power source for a fuel cell vehicle.

  FIG. 1 is a configuration diagram showing a schematic configuration of Embodiment 1 of a fuel cell system according to the present invention. In FIG. 1, a fuel cell system includes a fuel cell 1 having an anode (fuel electrode) 1a and a cathode (oxidant electrode) 1b, a high-pressure hydrogen tank 2 for storing hydrogen gas as a fuel gas at a high pressure, and a high-pressure hydrogen tank. 2, a hydrogen supply path 4 extending from 2 to the anode 1 a, a pressure regulating valve 3 disposed on the hydrogen supply path 4 for adjusting the pressure of the high-pressure hydrogen gas to the operating pressure of the fuel cell 1, and disposed downstream of the pressure regulating valve 3. The humidifying means 5 for humidifying the hydrogen, the jet pump 6 using the hydrogen that has been humidified by the humidifying means 5 as a driving flow, and the circulation path for supplying the high-humidity anode off-gas discharged from the anode 1a to the humidifying means 5 7, a hydrogen circulation pump 8 for supplying the anode off-gas discharged from the humidifying means 5 as a suction flow of the jet pump 6, and an exhaust gas branching from the circulation path 7 downstream of the humidifying means 5 And down 10, and a purge valve 9 for opening and closing the exhaust line 10.

  The fuel cell system includes components of an air system that supplies air to the cathode 1b, a cooling system that maintains the operating temperature of the fuel cell 1, and a power system that extracts power from the fuel cell 1. Since there is no feature, the illustration is omitted.

  The humidifying means 5 is a membrane type humidifying means capable of moving a water vapor component from a high-humidity gas to a low-humidity gas via a hollow fiber membrane, for example. The humidifying means 5 is supplied with hydrogen whose pressure is adjusted by the pressure regulating valve 3 as a low-humidity gas, and is supplied with anode off-gas as a high-humidity gas via the circulation path 7. Then, the supply hydrogen is humidified by the water vapor in the anode off-gas moving to the supply hydrogen through the hollow fiber membrane.

  The pressure regulating valve 3 performs pressure adjustment to supply hydrogen from the high-pressure hydrogen tank 2 to the anode 1a by a necessary supply amount. Since the hydrogen stored in the high-pressure hydrogen tank 2 is dry hydrogen gas, the humidifying means 5 is provided between the pressure regulating valve 3 and the jet pump 6 to humidify the supplied hydrogen that is the driving flow of the jet pump 6.

  Here, the jet pump will be described with reference to FIGS. In the fuel cell system application, the driving flow is newly supplied hydrogen, the suction flow is anode off-gas, and the mixed flow is gas supplied to the anode of the fuel cell.

  FIG. 9 is a schematic cross-sectional view illustrating an ejector that is a type of jet pump. The ejector 40 includes a nozzle 41 that ejects the driving flow 101, a mixing chamber 43 in which the driving flow 101 and the suction flow 103 merge, a throat portion 44 in which the driving flow 101 and the suction flow 103 mix, and a driving flow 101. A diffuser portion 45 that recovers the pressure of the mixed flow 104 mixed with the suction flow 103, a drive flow supply port 46, a suction port 47, and an outlet 48 are provided.

  The nozzle 41 is provided with an orifice (throttle) 42, and the driving flow 101 is ejected from the orifice 42 into the mixing chamber 43 as a high-speed jet 102. A negative pressure is formed around the jet 102 having a high velocity, and the suction flow 103 is sucked from the suction port 47 by the negative pressure.

  FIG. 10 is a schematic cross-sectional view illustrating an amplifying nozzle that is a kind of jet pump. The amplification nozzle 50 includes a substantially cylindrical body portion 51, a movable portion 52 that is movable in the axial direction of the body portion 51, and an O-ring 53 that maintains airtightness between the body portion 51 and the movable portion 52. ing. The screw part 54 provided on the inner peripheral part of the body part 51 and the screw part 55 provided on the outer peripheral part of the movable part 52 are screwed together. When the movable portion 52 is driven to reciprocate by a drive mechanism (not shown), the movable portion 52 moves back and forth in the axial direction with respect to the body portion 51, and the opening degree of the ring-shaped restrictor 59 increases or decreases due to this back and forth motion. Variable aperture is realized.

  A drive flow supply port 56 for supplying the drive flow 101 is provided on the cylindrical side surface of the body portion 51, and the drive flow 101 is supplied from the drive flow supply port 56. The driving flow 101 becomes a wall surface flow 62 that flows along the inner surface of the movable portion 52 by the Coanda effect through the restriction 59. For this reason, a negative pressure is generated at the center of the ring-shaped throttle 59, and the suction flow 103 is sucked from the suction port 57. The driving flow 101 and the suction flow 103 are mixed in the throat portion 60 to become a mixed flow 104, and the pressure is recovered in the diffuser portion 61 and discharged from the outlet 58.

  Returning to FIG. 1, the supply hydrogen humidified by the humidifying means 5 is increased in flow rate by the amount of water vapor and the density is also increased (FIG. 9, orifice 42 of the ejector 40, FIG. 10, amplification nozzle). 50), so that a lower negative pressure (larger absolute value) is generated in the mixing chamber of the anode off gas and the driving flow than in the case of dry without being humidified, so that a larger flow rate is obtained. As the anode off-gas is drawn in and a large flow rate is drawn in, the recovery pressure at the outlet of the jet pump recovers to a higher level than in the dry case. Thereby, a circulation flow rate can be increased and the head of a jet pump can be raised.

  When the present invention is not applied, dry hydrogen is used as a driving flow for the jet pump, anode off gas is used as a suction flow, and the mixed flow discharged from the jet pump is humidified. Since the supplied hydrogen is humidified in front, the density and flow rate of the jet pump drive flow can be increased by the amount of water vapor without changing the amount of supplied hydrogen that is uniformly determined by the load of the fuel cell. Boosting and flow rate drawing performance can be improved. Naturally, the supplied hydrogen can also have the role of promoting and protecting the stack reaction at the same time.

  Since the saturated water vapor pressure is determined by the temperature, when the atmospheric pressure is high and low at the same temperature, the water vapor pressure is relatively high when the atmospheric pressure is low, that is, when the atmospheric pressure is low, that is, in the gas. This means that the water vapor concentration is high. For this reason, when the humidifying means 5 is arranged between the pressure regulating valve 3 and the jet pump 6, a larger amount of water vapor can be included in the supplied hydrogen.

  However, it goes without saying that even if the supply hydrogen from the high-pressure hydrogen tank 2 is humidified upstream of the pressure regulating valve 3, it is possible to realize a larger pressure increase / flow rate drawing performance than when humidifying after passing through the jet pump.

  When a membrane-type humidifier is used as the humidifying means 5, it is possible to perform humidification without using electric power by exchanging humidity between the high-humidity gas and the low-humidity gas via the membrane. Further, by using humidified hydrogen as the driving flow of the jet pump 6, the circulation performance of the jet pump 6 is improved, and the power consumption of the hydrogen circulation pump 8 used in combination with the jet pump 6 is reduced, or the hydrogen circulation pump There is an effect that it is possible to construct a system that does not require a hydrogen circulation pump.

  Next, driving flow density increasing means for increasing the density of the driving flow by increasing the gas pressure supplied as the driving flow of the jet pump will be described. The driving flow density increasing means uses the amplifying nozzle described with reference to FIG. 10 in the first embodiment in order to reduce the opening of the variable throttle of the jet pump in accordance with the increase in the pressure of the driving flow. Use as

  If the size of the throttle of the jet pump is determined so that the hydrogen supplied to the jet pump chokes (the hydrogen speed reaches the speed of sound) under the rated conditions of the power generation amount of the fuel cell, The hydrogen velocity is in the subsonic speed range (below the sonic velocity), and the performance (flow rate and head) of the jet pump cannot function at a higher pressure and flow rate as high as choke. Therefore, by making the throttle of the jet pump variable and increasing the supply hydrogen pressure, the supply hydrogen flow rate (NL / min) is not changed, and only the density is increased and ejected.

  As shown by the broken line in FIG. 8, if the nozzles have the same diameter by increasing the hydrogen supply pressure at each fuel cell load, the hydrogen supply amount also increases. However, the increase in the supply pressure increases the hydrogen supply amount by the jet pump. Even if the supply pressure increases by restricting with the variable restrictor, the hydrogen supply amount does not change, and the gas density of the driving flow (supply hydrogen) of the jet pump increases. For this reason, the boosting performance (or flow rate performance) of the jet pump has the effect of improving from the value indicated by the white circle to the value indicated by the black circle even in the operation region below the rated load.

  FIG. 2 is a configuration diagram showing a schematic configuration of a second embodiment of the fuel cell system according to the present invention. In FIG. 2, the fuel cell system includes a fuel cell 1 having an anode (fuel electrode) 1a and a cathode (oxidant electrode) 1b, a high-pressure hydrogen tank 2 for storing hydrogen gas as a fuel gas at high pressure, and a high-pressure hydrogen tank. 2, a hydrogen supply path 4 extending from 2 to the anode 1 a, a pressure regulating valve 3 disposed on the hydrogen supply path 4 for adjusting the pressure of the high-pressure hydrogen gas to the operating pressure of the fuel cell 1, and disposed downstream of the pressure regulating valve 3. The humidifying means 11 for humidifying the hydrogen, the jet pump 6 that uses the hydrogen humidified by the humidifying means 11 as a driving flow, and the high-humidity anode off-gas discharged from the anode 1a are supplied as the suction flow of the jet pump. A circulation path 7 and a hydrogen circulation pump 8 for pumping the anode off gas in the circulation path 7 are provided.

  The fuel cell system includes components of an air system that supplies air to the cathode 1b, a cooling system that maintains the operating temperature of the fuel cell 1, and a power system that extracts power from the fuel cell 1. Since there is no feature, the illustration is omitted.

  The humidifying means 11 includes a water tank 12 for storing water and a heating means 13 for heating the water tank 12. The humidifying means 11 is a so-called bubbler type humidifier that humidifies by blowing hydrogen gas, which is a humidified gas, into the water in the water tank 12. The heating means 13 heats the water tank 12 to raise the water temperature inside the water tank and increase the water vapor partial pressure. As the heating means 13, an electric heater that generates heat with electric power supplied from a storage battery (not shown), a catalytic combustor that generates heat by reacting part of the supplied hydrogen with oxygen in the air, or the like can be used.

  The water in the water tank 12 is preferably supplied with pure water recovered from the cathode exhaust by a condenser (not shown). As a result, a fuel cell system for a moving body that does not require water supply for humidification can be configured.

  In the present embodiment, the humidifying means 11 is a bubbler type, but it is also possible to use a steam injection type in which water vapor is injected into the humidified gas other than the bubbler type. In the case of the steam injection type, the humidification amount of the supplied hydrogen can be rapidly increased only by injecting high-temperature water, and thus it is effective in a fuel cell system that requires high responsiveness.

FIG. 3 is a configuration diagram showing a schematic configuration of a third embodiment of the fuel cell system according to the present invention. In FIG. 3, the fuel cell system includes a fuel cell 1 having an anode (fuel electrode) 1a and a cathode (oxidant electrode) 1b, a high-pressure hydrogen tank 2 for storing hydrogen gas as a fuel gas at high pressure, and a high-pressure hydrogen tank. 2, a hydrogen supply path 4 extending from 2 to the anode 1 a, a pressure regulating valve 3 disposed on the hydrogen supply path 4 for adjusting the pressure of the high-pressure hydrogen gas to the operating pressure of the fuel cell 1, and disposed downstream of the pressure regulating valve 3. The humidifying means 5 for humidifying the hydrogen, the jet pump 6 using the hydrogen that has been humidified by the humidifying means 5 as a driving flow, and the high-humidity anode off-gas discharged from the anode 1 a are jetted via the hydrogen circulation pump 8. A circulation path 7 for supplying the pump 6 and the humidifying means 5;
An anode off-gas introduction path 14 that branches from the circulation path 7 downstream of the hydrogen circulation pump 8 and supplies a part of the anode off-gas to the humidifying means 5, and a flow path of the anode off-gas discharged from the humidifying means 5 is adjusted. And a variable orifice 15 to be returned to.

  The fuel cell system includes components of an air system that supplies air to the cathode 1b, a cooling system that maintains the operating temperature of the fuel cell 1, and a power system that extracts power from the fuel cell 1. Since there is no feature, the illustration is omitted.

  In the first embodiment, the anode off-gas is passed as it is as one of the circulation paths, but the power consumption of the hydrogen circulation pump 8 increases due to the occurrence of pressure loss, which may adversely affect the assist effect of the jet pump 6. There is also sex.

  Therefore, in this embodiment, a part of the anode off-gas having a high temperature compressed by the hydrogen circulation pump 8 is introduced into the humidifying means 5 from between the hydrogen circulation pump 6 and the jet pump suction side inlet to supply hydrogen. The anode off-gas introduction path 14 is provided so as to perform steam exchange with the hydrogen circulation pump and exit to the hydrogen circulation pump inlet.

  In addition, a variable orifice 15 is provided in the anode off-gas passage 14 for varying the amount of humidification of the supplied hydrogen in accordance with the load state of the fuel cell system and varying the amount of assist to the hydrogen circulation pump 8 by the jet pump 6. Thereby, the introduction amount of the anode off gas discharged from the hydrogen circulation pump 8 to the humidifying means 5 is controlled. The variable orifice 15 controls the variable orifice 15 so that the humidification amount increases as the load of the fuel cell system increases, and the humidification amount decreases as the load decreases.

  According to the present embodiment, since the anode off gas is used as a humidification source, the anode off gas, which is the suction flow of the jet pump, becomes lighter and the flow rate is reduced by the amount of water vapor. Therefore, it is possible to obtain a higher jet pump performance improvement effect.

  FIG. 4 is a configuration diagram showing a schematic configuration of the embodiment 4 of the fuel cell system according to the present invention. 4, the fuel cell system includes a fuel cell 1 having an anode (fuel electrode) 1a and a cathode (oxidant electrode) 1b, a high-pressure hydrogen tank 2 for storing hydrogen gas as a fuel gas at a high pressure, and a high-pressure hydrogen tank. 2, a hydrogen supply path 4 extending from 2 to the anode 1 a, a pressure regulating valve 3 disposed on the hydrogen supply path 4 for adjusting the pressure of the high-pressure hydrogen gas to the operating pressure of the fuel cell 1, and disposed downstream of the pressure regulating valve 3. The humidifying means 5 for humidifying the hydrogen, the jet pump 6 using the hydrogen that has been humidified by the humidifying means 5 as a driving flow, and the high-humidity anode off-gas discharged from the anode 1a are supplied as the suction flow of the jet pump. A jet branched from the circulation path 7 and the hydrogen supply path 4 downstream of the jet pump 6 to supply a part of the mixed flow by the jet pump 6 to the humidifying means 5 as a high humidity gas A pump outlet gas inlet passage 17, and a jet pump heating means 16 for heating the jet pump 6.

  The fuel cell system includes components of an air system that supplies air to the cathode 1b, a cooling system that maintains the operating temperature of the fuel cell 1, and a power system that extracts power from the fuel cell 1. Since there is no feature, the illustration is omitted.

  The humidifying means 5 is a membrane type humidifying means capable of moving a water vapor component from a high-humidity gas to a low-humidity gas via a hollow fiber membrane, for example. The humidifying means 5 is supplied with hydrogen whose pressure is adjusted by the pressure regulating valve 3 as a low humidity gas, and is supplied with a jet pump outlet gas via the jet pump outlet gas introduction passage 17 as a high humidity gas. Then, the water vapor in the jet pump outlet gas moves to the hydrogen supply through the hollow fiber membrane, so that the hydrogen supply is humidified.

  In the first to third embodiments, a description has been given of a system in which a hydrogen circulation pump and a jet pump are combined as an anode off-gas circulation device. However, the present invention can be applied to a system having only a jet pump without a hydrogen circulation pump. Of course it is possible.

  Further, at the throttle in the jet pump 6 (FIG. 9, orifice 42 of the ejector 40, FIG. 10, throttle 59 of the amplification nozzle 50, etc.), the supply hydrogen is cooled, so that condensed water is generated and the throttle portion of the jet pump is clogged. In order to avoid the malfunction of the jet pump, a heating means 16 for heating the jet pump is provided. The heating means 16 does not have to be, the necessity depends on the system. Needless to say, not only in this embodiment shown in FIG. 4 but also in all embodiments, the reliability (orifice hole or avoidance) is improved by heating the jet pump. Further, when the supplied hydrogen is warmed by the jet pump 6, the gas temperature rises, so that the circulation efficiency is further improved. The same applies when the supplied hydrogen is heated by the humidifying means. The heating means 16 is composed of, for example, an electric heater or the like, and controls the energization current of the electric heater based on the detection value of the temperature sensor provided in the jet pump so as to achieve a constant heating temperature. This heating temperature is determined in consideration of heat resistance of the stack and operation efficiency.

  FIG. 5 is a configuration diagram showing a schematic configuration of the fifth embodiment of the fuel cell system according to the present invention. In FIG. 5, the fuel cell system includes a fuel cell 1 having an anode (fuel electrode) 1a and a cathode (oxidant electrode) 1b, a high-pressure hydrogen tank 2 for storing hydrogen gas as a fuel gas at a high pressure, and a high-pressure hydrogen tank. 2, a hydrogen supply path 4 extending from 2 to the anode 1 a, a pressure regulating valve 3 disposed on the hydrogen supply path 4 for adjusting the pressure of the high-pressure hydrogen gas to the operating pressure of the fuel cell 1, and disposed downstream of the pressure regulating valve 3. The humidifying means 5 for humidifying the hydrogen, the jet pump 6 using the hydrogen that has been humidified by the humidifying means 5 as a driving flow, and the circulation path 7 for supplying the anode off-gas discharged from the anode 1a as the suction flow of the jet pump A cathode offgas introduction path 18 for supplying the cathode offgas discharged from the cathode 1b as a high humidity gas to the humidifying means 5, and a cathode used in the humidifying means 5. An air pressure regulating valve 19 for controlling the pressure of Doofugasu includes an air discharge passage 20 for discharging the cathode off-gas from the air pressure regulator valve 19, a jet pump heating means 16 for heating the jet pump 6.

  The fuel cell system includes components of an air system that supplies air to the cathode 1b, a cooling system that maintains the operating temperature of the fuel cell 1, and a power system that extracts power from the fuel cell 1. Since there is no feature, the illustration is omitted.

  The humidifying means 5 is a membrane type humidifying means capable of moving a water vapor component from a high-humidity gas to a low-humidity gas via a hollow fiber membrane, for example. The humidifying means 5 is supplied with hydrogen whose pressure is adjusted by the pressure regulating valve 3 as a low-humidity gas, and is supplied with a cathode off-gas as a high-humidity gas via the cathode off-gas introduction path 18. Then, the supply hydrogen is humidified by the water vapor in the cathode off gas moving to the supply hydrogen through the hollow fiber membrane. The cathode off gas discharged from the humidifying means 5 is discharged from the air discharge passage 20 through the air pressure regulating valve 19.

  FIG. 6 is a configuration diagram showing a schematic configuration of Embodiment 6 of the fuel cell system according to the present invention. In FIG. 6, the fuel cell system includes a fuel cell 1 having an anode (fuel electrode) 1a and a cathode (oxidant electrode) 1b, a high-pressure hydrogen tank 2 for storing hydrogen gas as a fuel gas at a high pressure, and a high-pressure hydrogen tank. 2, a hydrogen supply path 4 extending from 2 to the anode 1 a, a pressure regulating valve 3 disposed on the hydrogen supply path 4 for adjusting the pressure of the high-pressure hydrogen gas to the operating pressure of the fuel cell 1, and disposed downstream of the pressure regulating valve 3. The humidifying means 5 for humidifying the hydrogen, the jet pump 6 using the hydrogen that has been humidified by the humidifying means 5 as a driving flow, and the circulation path 7 for supplying the anode off-gas discharged from the anode 1a as the suction flow of the jet pump An anode purge gas introduction passage 21 that supplies the humidifying means 5 as high-humidity gas when purging the anode off-gas discharged from the anode 1a, and the humidifying means A purge valve 9 for controlling the release / release stop of the used anode purge gas, an exhaust line 10 for discharging the anode purge gas from the humidifying means 5, and a jet pump heating means 16 for heating the jet pump 6. .

  The fuel cell system includes components of an air system that supplies air to the cathode 1b, a cooling system that maintains the operating temperature of the fuel cell 1, and a power system that extracts power from the fuel cell 1. Since there is no feature, the illustration is omitted.

  The humidifying means 5 is a membrane type humidifying means capable of moving a water vapor component from a high-humidity gas to a low-humidity gas via a hollow fiber membrane, for example. The humidifying means 5 is supplied with hydrogen whose pressure is adjusted by the pressure regulating valve 3 as low humidity gas, and is supplied with anode purge gas through the anode purge gas introduction passage 21 as high humidity gas. Then, the water vapor in the anode purge gas moves to the hydrogen supply through the hollow fiber membrane, so that the hydrogen supply is humidified. The anode purge gas discharged from the humidifying means 5 is discharged from the exhaust line 10 through the purge valve 9.

  FIG. 7 is a configuration diagram showing a schematic configuration of Embodiment 7 of the fuel cell system according to the present invention. In FIG. 7, the fuel cell system includes a fuel cell 1 having an anode (fuel electrode) 1a and a cathode (oxidant electrode) 1b, a high-pressure hydrogen tank 2 for storing hydrogen gas as a fuel gas at a high pressure, and a high-pressure hydrogen tank. 2, a hydrogen supply path 4 extending from 2 to the anode 1 a, a pressure regulating valve 3 disposed on the hydrogen supply path 4 for adjusting the pressure of the high-pressure hydrogen gas to the operating pressure of the fuel cell 1, and disposed downstream of the pressure regulating valve 3. The humidifying means 5 for humidifying the hydrogen, the jet pump 6 using the hydrogen that has been humidified by the humidifying means 5 as a driving flow, and the circulation path 7 for supplying the anode off-gas discharged from the anode 1a as the suction flow of the jet pump A jet pump heating means 16 for heating the jet pump 6, a high-pressure nitrogen tank 30 for storing nitrogen gas at a high pressure, and the pressure of the high-pressure nitrogen under the hydrogen regulating valve 3. Nitrogen pressure regulating valve 31 to adjust the pressure was reduced to about a pressure, a nitrogen regulating valve 31 and a nitrogen-introducing passage 32 for combining into between the pressure regulated nitrogen gas pressure regulating valve 3 has a humidifier 5, a.

  The fuel cell system includes components of an air system that supplies air to the cathode 1b, a cooling system that maintains the operating temperature of the fuel cell 1, and a power system that extracts power from the fuel cell 1. Since there is no feature, the illustration is omitted.

  As the humidifying means 5, any of the film type humidifying means described in the first embodiment, the bubbler type and the steam injection type described in the second embodiment can be used.

  In this embodiment, the gas density of the driving flow can be increased by mixing a small amount of nitrogen supplied from the high-pressure nitrogen tank 30 between the jet pump 6 and the pressure regulating valve 3 as necessary, and the circulation performance of the jet pump. Has the effect of improving. In addition, since the suction flow rate can be increased, when a hydrogen circulation pump is used to circulate the circulating gas, the power consumption of the hydrogen circulation pump is reduced and the overall fuel efficiency of the fuel cell system is improved. There is. Further, since the effect of reducing the rotation speed of the hydrogen circulation pump can be expected, there is an effect that the acoustic vibration level characteristic of the fuel cell system can be improved.

  Nitrogen may be mixed upstream of the pressure regulating valve 3, but the pressure of the high-pressure nitrogen tank 30 needs to be increased. In order to reduce the cost of machinery, it is cheaper to mix it downstream of the pressure regulating valve 3 because a relatively low pressure is required. The necessary amount of nitrogen mixed is detected from parameters (stack power generation amount, rotational speed of auxiliary machinery, etc.) indicating each operation load condition of the fuel cell. The gas species need not be limited to nitrogen as long as it is harmless to the anode circulation system. The amount of nitrogen gas input is controlled to increase as the load increases and decrease as the load decreases.

It is a block diagram of Example 1 of the fuel cell system according to the present invention. It is a block diagram of Example 2 of the fuel cell system according to the present invention. It is a block diagram of Example 3 of the fuel cell system according to the present invention. It is a block diagram of Example 4 of the fuel cell system according to the present invention. It is a block diagram of Example 5 of the fuel cell system according to the present invention. It is a block diagram of Example 6 of the fuel cell system according to the present invention. It is a block diagram of Example 7 of the fuel cell system according to the present invention. It is a graph which shows the pressure | voltage rise amount of a jet pump with respect to fuel cell load, and hydrogen supply pressure. It is a schematic cross section explaining the structure of an ejector. It is a schematic cross section explaining the structure of the amplification nozzle provided with the variable aperture.

Explanation of symbols

1: Fuel cell (1a: anode, 1b: cathode)
2: High-pressure hydrogen tank 3: Pressure regulating valve 4: Hydrogen supply path 5: Humidification means 6: Jet pump 7: Circulation path 8: Hydrogen circulation pump 9: Purge valve 10: Exhaust line

Claims (11)

A fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidant gas;
The fuel gas newly supplied to the fuel cell is used as a driving flow, and the anode off-gas discharged from the fuel electrode of the fuel cell is sucked, and a mixed gas obtained by mixing the newly supplied fuel gas and the anode off-gas is supplied to the fuel cell. A jet pump to supply;
Driving flow density increasing means for increasing the gas density of the driving flow of the jet pump;
A fuel cell system comprising: A high-pressure hydrogen tank for storing hydrogen gas at high pressure as fuel gas;
A pressure regulating valve for adjusting the pressure of the hydrogen gas supplied from the high-pressure hydrogen tank;
With
2. The fuel cell system according to claim 1, wherein the driving flow density increasing means is a humidifying means disposed between the pressure regulating valve and the jet pump.   The fuel cell system according to claim 2, wherein the humidifying means is a humidifying means for humidifying by blowing hydrogen gas into a water tank.   The fuel cell system according to claim 2, wherein the humidifying means includes a water vapor exchange membrane that performs water vapor exchange between a high humidity gas and hydrogen gas supplied from the pressure regulating valve.   The fuel cell system according to claim 4, wherein the high-humidity gas is an anode off-gas discharged from a fuel electrode of the fuel cell. Equipped with a hydrogen circulation pump that circulates anode off-gas,
6. The fuel cell system according to claim 5, wherein an anode off gas is introduced from the outlet of the hydrogen circulation pump into the humidification means, and the anode off gas discharged from the humidification means is returned to the hydrogen circulation pump inlet.   The fuel cell system according to claim 4, wherein the high-humidity gas is a cathode off-gas discharged from an oxidant electrode of the fuel cell.   The fuel cell system according to claim 4, wherein the high-humidity gas is an anode purge gas or an outlet gas of the jet pump.   The fuel cell system according to any one of claims 1 to 8, wherein a front side of an orifice for restricting a driving flow of the jet pump is heated.   2. The fuel cell system according to claim 1, wherein the driving flow density increasing means is means for mixing an inert gas into the driving flow of the jet pump. The jet pump is a variable throttle jet pump,
The driving flow density increasing means is means for increasing the density of the driving flow by increasing the gas pressure supplied as the driving flow of the jet pump,
2. The fuel cell system according to claim 1, wherein the opening degree of the variable throttle of the jet pump is reduced in accordance with an increase in the pressure of the driving flow.

Images