Electrochemical hydrogen boosting system

Abstract

To provide an electrochemical type hydrogen boosting system which can roughly uniformize water distribution contained in an electrolyte membrane in a short time when the electrolyte membrane is dried, and can early start a hydrogen boosting stack.SOLUTION: An electrochemical type hydrogen boosting system (10) includes a control device (18) for controlling a power source device (26), a hydrogen supply valve (50), a path connector (62), and a water feeder (60). When receiving an operation start instruction, the control device (18) allows a hydrogen boosting stack to supply liquid water from a water source until a prescribed water feeding period elapses. Then, the control device (18) starts supply of hydrogen gas to the hydrogen boosting stack (24). After the prescribed hydrogen gas supply period elapses, the control device (18) starts supply of current to the hydrogen boosting stack (24).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrochemical hydrogen boosting system. [Background technology]

[0002] In recent years, research and development has been conducted on electrochemical hydrogen boosting systems that contribute to energy efficiency in order to ensure that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] The electrochemical hydrogen boosting system of Patent Document 1 includes an electrochemical hydrogen boosting device that boosts hydrogen. The electrochemical hydrogen boosting device includes a hydrogen boosting stack (hydrogen boosting section) and a power supply (power source). The hydrogen boosting stack includes unit cells including an electrolyte membrane, an anode power supply, and a cathode power supply. The power supply supplies current to the hydrogen boosting stack, causing the hydrogen boosting stack to generate high-pressure hydrogen gas at a higher pressure than the hydrogen gas supplied to the hydrogen boosting stack.

[0004] Patent Document 1 discloses a technology in which, based on information regarding the wetness state of the electrolyte membrane, the outlet of the hydrogen boosting stack through which unreacted hydrogen gas is discharged is regulated, and water vapor is retained in the unit cell to keep the electrolyte membrane wet. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-94891 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the longer the electrochemical hydrogen boosting device is stopped, the more the electrolyte membrane tends to dry out. When the electrolyte membrane dries out, the distribution of moisture contained in the electrolyte membrane is likely to become non-uniform. It is believed that the use of the above-mentioned technology of Patent Document 1 will make the electrolyte membrane moist again. However, there is a problem in that it takes a significant amount of time for the distribution of moisture contained in the electrolyte membrane to become roughly uniform.

[0007] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0008] An aspect of the present invention is an electrochemical hydrogen boosting system comprising: a hydrogen boosting stack provided with a unit cell including an electrolyte membrane, an anode electrode, and a cathode electrode; a power supply device that supplies an electric current to the hydrogen boosting stack to generate high-pressure hydrogen gas in the hydrogen boosting stack at a pressure higher than that of hydrogen gas supplied to the hydrogen boosting stack; and a hydrogen supply source that supplies the hydrogen gas to the hydrogen boosting stack via a supply path communicating with the anode side of the unit cell, the system comprising: a hydrogen supply valve provided in the supply path; a path connector that connects a water source to the supply path via a water supply path or disconnects the connection; a water supply device that supplies liquid water from the water source to the hydrogen boosting stack; and a control device that controls the power supply device, the hydrogen supply valve, the path connector, and the water supply device, wherein, upon receiving an operation start command, the control device controls the supply of liquid water from the water source to the hydrogen boosting stack until a predetermined water supply period has elapsed, The electrolyte membrane of each unit cell was uniformly impregnated with the liquid water. Then, start supplying the hydrogen gas to the hydrogen boosting stack, Adjusting the water content of the electrolyte membrane; After a predetermined hydrogen gas supply period has elapsed, the supply of the current to the hydrogen boosting stack is started. Effect of the Invention

[0009] According to the above aspect, the water distribution in the electrolyte membrane can be made substantially uniform in a short period of time, which allows the hydrogen boosting stack to be started up quickly. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an electrochemical hydrogen boosting system according to an embodiment. [Diagram 2] FIG. 2 is a flowchart showing a procedure of the stack startup process. [Diagram 3] FIG. 3 is a schematic diagram showing a modified electrochemical hydrogen boosting system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1 is a schematic diagram showing an embodiment of an electrochemical hydrogen boosting system 10. The electrochemical hydrogen boosting system 10 includes an electrochemical hydrogen boosting device 12, a hydrogen supply source 14, a humidifier 16, and a control device 18.

[0012] The electrochemical hydrogen booster 12 is a device that electrochemically compresses hydrogen gas. The electrochemical hydrogen booster 12 includes a hydrogen booster stack 24 and a power supply 26.

[0013] The hydrogen booster stack 24 has an inlet port PT1, an outlet port PT2, and a high-pressure hydrogen port PT3. The inlet port PT1 is a port for introducing hydrogen gas and is connected to the anode side of each unit cell 28. The outlet port PT2 is a port for discharging unreacted hydrogen gas and is connected to the anode side of each unit cell 28. The high-pressure hydrogen port PT3 is a port for discharging high-pressure hydrogen gas generated in the unit cell 28 and is connected to the cathode side of each unit cell 28.

[0014] The plurality of unit cells 28 each have the same configuration. Each unit cell 28 has an electrolyte membrane 30, an anode electrode 32 provided on one surface of the electrolyte membrane 30, and a cathode electrode 34 provided on the other surface of the electrolyte membrane 30.

[0015] The electrolyte membrane 30 is, for example, a solid polymer electrolyte membrane (cation exchange membrane). The electrolyte membrane 30 may be reinforced on the anode side with a protective sheet (not shown) including a fibrous skeleton. The electrolyte membrane 30 may use a fluorine-based electrolyte or an HC (hydrocarbon)-based electrolyte. The electrolyte membrane 30 is sandwiched between an anode electrode 32 and a cathode electrode 34.

[0016] The anode electrode 32 includes an anode catalyst layer bonded to one surface of the electrolyte membrane 30, and an anode power supply laminated on the anode catalyst layer. The cathode electrode 34 includes a cathode catalyst layer bonded to the other surface of the electrolyte membrane 30, and a cathode power supply laminated on the cathode catalyst layer. The anode power supply and the cathode power supply are formed into a structure that allows hydrogen gas to flow through them.

[0017] When a current is supplied between the anode electrode 32 and the cathode electrode 34, a part of the hydrogen gas supplied to the anode electrode 32 from the inlet port PT1 is converted into protons (H + The converted protons are transported to the cathode electrode 34 via the electrolyte membrane 30. At the cathode electrode 34, high-pressure hydrogen gas is generated by an electrochemical reaction using the transported protons.

[0018] The high-pressure hydrogen gas flows out from the high-pressure hydrogen port PT3. The high-pressure hydrogen gas flowing out from the high-pressure hydrogen port PT3 is supplied to, for example, a tank via a discharge path 35. The discharge path 35 is a path that guides the high-pressure hydrogen gas discharged from the hydrogen booster stack 24. A back pressure valve or the like is provided in the discharge path 35.

[0019] Hydrogen gas that has not reacted at the anode electrode 32 flows out from the exhaust port PT2. The hydrogen gas flowing out from the exhaust port PT2 is supplied into the sealed container 38 via the low-pressure exhaust path 36, or is exhausted via a vent path 40 branching off from the low-pressure exhaust path 36. A discharge valve 42 and a pump 44 are provided in the low-pressure exhaust path 36. A vent valve 45 is provided in the vent path 40. The discharge valve 42 and the vent valve 45 each open or close under the control of the control device 18. The pump 44 is driven under the control of the control device 18, and applies a flow force from the upstream side to the downstream side to the hydrogen gas.

[0020] The power supply device 26 supplies an electric current to the hydrogen booster stack 24. As a result, high-pressure hydrogen gas having a higher pressure than the hydrogen gas supplied to the hydrogen booster stack 24 is generated in the hydrogen booster stack 24.

[0021] The power supply device 26 applies a voltage to the anode electrode 32 and the cathode electrode 34 of each unit cell 28, and supplies a current to the unit cell 28. The power supply device 26 is configured to be able to adjust the magnitude of the current supplied to each unit cell 28 in response to control by the control device 18. The larger the current value supplied to a unit cell 28, the greater the amount of high-pressure hydrogen gas generated in that unit cell 28.

[0022] The hydrogen supply source 14 is a device capable of supplying hydrogen gas. The hydrogen supply source 14 may be a cylinder formed by collecting a plurality of gas cylinders in which hydrogen gas is stored. Alternatively, the hydrogen supply source 14 may be a tank in which hydrogen gas is stored. The hydrogen supply source 14 supplies hydrogen gas to the hydrogen booster stack 24 via a supply path 46.

[0023] The supply path 46 is a path that guides hydrogen gas from the hydrogen supply source 14 to the hydrogen booster stack 24. The upstream end of the supply path 46 is connected to an output port (not shown) of the hydrogen supply source 14. The downstream end of the supply path 46 is connected to an inlet port PT1 of the hydrogen booster stack 24. A pressure reducing valve 48, a hydrogen supply valve 50, and a flow rate control valve 52 are provided in this order in the supply path 46 from the upstream side to the downstream side.

[0024] 1, there is one pressure reducing valve 48, but there may be two or more pressure reducing valves 48. The hydrogen supply valve 50 opens or closes under the control of the controller 18. The flow rate control valve 52 adjusts the flow rate of hydrogen gas supplied to the hydrogen booster stack 24 under the control of the controller 18.

[0025] The humidifier 16 is a device that humidifies hydrogen gas. The humidifier 16 has a sealed container 38. The humidifier 16 vaporizes liquid water stored in the sealed container 38. The humidifier 16 supplies water vapor to the supply path 46 via the outlet path 54.

[0026] The outlet path 54 is a path that leads water vapor from the humidifier 16 to the supply path 46. The upstream end of the outlet path 54 is disposed in the gas phase space of the sealed container 38. The downstream end of the outlet path 54 is connected to the supply path 46 between the hydrogen supply valve 50 and the flow rate adjustment valve 52. The outlet path 54 is provided with an outlet valve 56. The outlet valve 56 opens or closes under the control of the control device 18.

[0027] The sealed container 38 communicates with the supply path 46 via a water supply path 58. The water supply path 58 is a path that guides the liquid water stored in the sealed container 38 to the supply path 46. A water supply device 60 is provided in the water supply path 58. A path connector 62 is provided at the connection between the water supply path 58 and the supply path 46.

[0028] The water supply device 60 is a device that supplies the liquid water stored in the sealed container 38 to the hydrogen booster stack 24. The water supply device 60 is driven according to the control of the control device 18, and imparts a flow force from the upstream side to the downstream side to the hydrogen gas. An example of the water supply device 60 is a pump. FIG. 1 shows an example in which the water supply device 60 is a pump. The path connector 62 is a device that connects the sealed container 38 of the humidifier 16 to the supply path 46 via the water supply path 58, or disconnects the connection. An example of the path connector 62 is a three-way valve. FIG. 1 shows an example in which the path connector 62 is a three-way valve. When the path connector 62 connects the sealed container 38 to the supply path 46, hydrogen gas is not supplied from the hydrogen supply source 14 to the hydrogen booster stack 24. On the other hand, when the path connector 62 cuts off the connection of the sealed container 38 to the supply path 46, hydrogen gas is supplied from the hydrogen supply source 14 to the hydrogen booster stack 24.

[0029] The humidifier 16 may be a bubbler type humidifier. FIG. 1 shows an example in which the humidifier 16 is a bubbler type humidifier. In this case, the humidifier 16 has a bubble generator 64. The bubble generator 64 is disposed in the liquid water in the sealed container 38. The bubble generator 64 releases hydrogen gas supplied from the supply path 46 via the introduction path 66 into the liquid water as bubbles. As a result, the hydrogen gas contains moisture (water vapor). The hydrogen gas containing moisture is supplied to the supply path 46 via the outlet path 54.

[0030] The introduction path 66 is a path that guides a portion of the hydrogen gas flowing through the supply path 46 from the supply path 46 to the bubble generator 64. The upstream end of the introduction path 66 is connected to a location on the supply path 46 upstream of the connection location of the downstream end of the outlet path 54. The downstream end of the introduction path 66 is connected to the bubble generator 64. An introduction valve 68 is provided in the introduction path 66. The introduction valve 68 opens or closes under the control of the control device 18.

[0031] A temperature adjustment device 70 may be provided to adjust the temperature of the liquid water stored in the sealed container 38. The temperature adjustment device 70 includes a heat exchanger 72, a circulation path 74 that circulates the liquid water between the heat exchanger 72 and the sealed container 38, and a pump 76 provided in the circulation path 74. The temperature adjustment device 70 drives the pump 76 to circulate the liquid water between the heat exchanger 72 and the sealed container 38 via the circulation path 74, and adjusts the liquid water to a set temperature by heat exchange with the heat exchanger 72.

[0032] The control device 18 is a computer that controls the electrochemical hydrogen boosting system 10. The control device 18 includes one or more processors and a storage medium. The storage medium may be composed of a volatile memory and a non-volatile memory. Examples of the processor include a CPU, an MCU, etc. Examples of the volatile memory include a RAM, etc. Examples of the non-volatile memory include a ROM, a flash memory, etc.

[0033] A detector 78 is connected to the control device 18. Using the detector 78, the control device 18 acquires an electrical value of the hydrogen booster stack 24 when the current of the hydrogen booster stack 24 is a predetermined value. The electrical value is a value indicating voltage or resistance. The higher the voltage of the hydrogen booster stack 24 compared to a reference voltage that is a voltage suitable for operation of the hydrogen booster stack 24, the more moisture will remain in the unit cell 28. Similarly, the higher the resistance of the hydrogen booster stack 24 compared to a reference resistance that is a resistance suitable for operation of the hydrogen booster stack 24, the more moisture will remain in the unit cell 28. Therefore, the control device 18 can capture the amount of moisture remaining in the unit cell 28 by acquiring an electrical value when the current of the hydrogen booster stack 24 is a predetermined value.

[0034] The detector 78 is provided in the hydrogen booster stack 24. The detector 78 may be a voltage sensor. In this case, the control device 18 acquires, as an electrical value, a voltage value (detected voltage value) detected by the voltage sensor when the current in the hydrogen booster stack 24 is a predetermined value. The detector 78 may be a resistance sensor. In this case, the control device 18 detects, as an electrical value, a resistance value (detected resistance value) detected by the resistance sensor when the current in the hydrogen booster stack 24 is a predetermined value.

[0035] The voltage or resistance may be calculated using Ohm's law, so the value detected by detector 78 may be used by controller 18 to calculate the detected voltage or resistance value.

[0036] The detected voltage value may be a voltage value applied across both ends of a plurality of unit cells 28 included in the hydrogen boosting stack 24. Alternatively, the detected voltage value may be a voltage value of one unit cell 28 selected from the plurality of unit cells 28. Alternatively, the detected voltage value may be a statistical value of the voltage values ​​of each of the plurality of unit cells 28. Alternatively, the detected voltage value may be a statistical value of the voltage values ​​of two or more unit cells 28 selected from the plurality of unit cells 28. Examples of the statistical value include an average value, a median value, a total value, etc.

[0037] Similarly, the detected resistance value may be a resistance value detected at both ends of a plurality of unit cells 28 included in the hydrogen boosting stack 24. Alternatively, the detected resistance value may be a resistance value of one unit cell 28 selected from the plurality of unit cells 28. Alternatively, the detected resistance value may be a statistical value of the resistance values ​​of each of the plurality of unit cells 28. Alternatively, the detected resistance value may be a statistical value of the resistance values ​​of two or more unit cells 28 selected from the plurality of unit cells 28. Examples of the statistical value include an average value, a median value, a total value, etc.

[0038] When the control device 18 receives an operation start command, it executes a stack startup process. The stack startup process may be defined by a program. Alternatively, the stack startup process may be realized by an integrated circuit such as an ASIC or an FPGA. Alternatively, the stack startup process may be realized by an electronic circuit including a discrete device. Details of the stack startup process will be described later.

[0039] When the stack startup process is completed, the hydrogen supply valve 50, the inlet valve 68, and the outlet valve 56 are in an open state. In addition, the path connector 62 is in a state in which the connection of the sealed container 38 to the supply path 46 is interrupted. In this case, hydrogen gas is supplied from the hydrogen supply source 14 to the hydrogen booster stack 24 via the supply path 46. In addition, a portion of the hydrogen gas flowing through the supply path 46 flows into the humidifier 16 via the inlet path 66 and is humidified. The humidified hydrogen gas returns to the supply path 46 via the outlet path 54. Therefore, wet hydrogen gas containing water vapor is supplied to the hydrogen booster stack 24.

[0040] Furthermore, when the stack startup process is completed, a predetermined voltage is applied from the power supply device 26 to each unit cell 28 of the hydrogen boosting stack 24. In this case, a current is supplied from the power supply device 26 to each unit cell 28. In each unit cell 28, an electrochemical reaction is carried out based on the hydrogen gas supplied from the hydrogen supply source 14. As a result, high-pressure hydrogen gas is generated on the cathode side of each unit cell 28.

[0041] After executing the stack startup process, the control device 18 drives the pump 44. The control device 18 also opens the exhaust valve 42 and closes the vent valve 45. As a result, unreacted hydrogen gas in the hydrogen booster stack 24 is supplied to the sealed container 38.

[0042] In addition, after executing the stack startup process, the control device 18 controls at least one of the opening degree of the hydrogen supply valve 50 and the opening degree of the inlet valve 68 to adjust the flow rate ratio of hydrogen gas that passes through the humidifier 16 and hydrogen gas that does not pass through the humidifier 16.

[0043] In addition, after executing the stack startup process, the control device 18 controls the opening degree of the flow control valve 52 based on the target generation amount of high-pressure hydrogen gas, thereby adjusting the flow rate of hydrogen gas supplied to the hydrogen booster stack 24.

[0044] Next, the stack startup process by the control device 18 will be described. Fig. 2 is a flow chart showing the procedure of the stack startup process. Before the start of the stack startup process, the hydrogen booster stack 24 is stopped. Also, the exhaust valve 42, the hydrogen supply valve 50, the vent valve 45, the introduction valve 68 and the discharge valve 56 are closed. Also, the pump 44 and the water supply device 60 are stopped. Also, the path connector 62 is in a state in which the connection of the sealed container 38 to the supply path 46 is cut off. The stack startup process is started when an operation start command is given to the control device 18.

[0045] In step S1, the controller 18 compares the outage duration of the hydrogen booster stack 24 with a predetermined outage duration threshold. The outage duration is the period of time that has elapsed since the supply of current to the hydrogen booster stack 24 was stopped.

[0046] If the operation outage period is equal to or less than a predetermined outage period threshold, the control device 18 determines that the progress of drying of the electrolyte membrane 30 of each unit cell 28 is small. In this case, the control device 18 executes a normal startup subroutine RT1. In the normal startup subroutine RT1, the control device 18 opens the hydrogen supply valve 50, the inlet valve 68, and the outlet valve 56 to supply wet hydrogen gas to the hydrogen booster stack 24. The control device 18 also controls the power supply device 26 to apply a predetermined voltage to the hydrogen booster stack 24 and supply a current to the hydrogen booster stack 24. This completes the stack startup process.

[0047] On the other hand, if the operation suspension period exceeds the predetermined suspension period threshold, the control device 18 determines that the degree of drying of the electrolyte membrane 30 in each unit cell 28 has progressed significantly. In this case, the control device 18 starts the emergency start subroutine RT2 and proceeds to step S2.

[0048] In step S2, the control device 18 controls the path connector 62 to connect the sealed container 38 of the humidifier 16 to the supply path 46 via the water supply path 58. The control device 18 also drives the water supply device 60 to start supplying liquid water from the sealed container 38 of the humidifier 16 to the hydrogen booster stack 24. Thereafter, the control device 18 proceeds to step S3.

[0049] In step S3, the controller 18 determines whether or not a predetermined water supply period has elapsed since the start of the supply of liquid water to the hydrogen booster stack 24. If the water supply period has not elapsed, the controller 18 remains in step S3. On the other hand, if the water supply period has elapsed, the controller 18 proceeds to step S4.

[0050] In step S4, the controller 18 stops the water supply device 60 to stop the supply of liquid water to the hydrogen booster stack 24. Thereafter, the controller 18 proceeds to step S5.

[0051] In step S5, the controller 18 opens the hydrogen supply valve 50 without opening the inlet valve 68 and the outlet valve 56, and starts the supply of dry hydrogen gas from the hydrogen supply source 14 to the hydrogen booster stack 24. Dry hydrogen gas is hydrogen gas that has not been humidified by the humidifier 16. After opening the hydrogen supply valve 50, the controller 18 proceeds to step S6.

[0052] In step S6, the controller 18 determines whether or not a predetermined hydrogen gas supply period has elapsed since the supply of dry hydrogen gas to the hydrogen booster stack 24 was started. If the hydrogen gas supply period has not elapsed, the controller 18 remains in step S6. On the other hand, if the predetermined hydrogen gas supply period has elapsed, the controller 18 proceeds to step S7.

[0053] In step S7, the controller 18 controls the power supply device 26 to start supplying current to each unit cell 28 of the hydrogen boosting stack 24. Thereafter, the controller 18 proceeds to step S8.

[0054] In step S8, the controller 18 uses the detector 78 to obtain an electrical value when the current in the hydrogen booster stack 24 is a predetermined value. After obtaining the electrical value when the current in the hydrogen booster stack 24 is a predetermined value, the controller 18 compares the electrical value with a predetermined threshold value. If the electrical value when the current in the hydrogen booster stack 24 is a predetermined value exceeds the threshold value, the controller 18 determines that the unit cell 28 contains too much moisture. In this case, the controller 18 proceeds to step S9. On the other hand, if the electrical value when the current in the hydrogen booster stack 24 is a predetermined value is equal to or less than the threshold value, the controller 18 determines that the unit cell 28 contains an appropriate amount of moisture. In this case, the controller 18 proceeds to step S10.

[0055] In step S9, the control device 18 controls the power supply device 26 to stop the supply of current to the unit cell 28 until the set time has elapsed, thereby preventing electrolysis of the water contained in the unit cell 28. When the set time has elapsed, the control device 18 returns to step S8.

[0056] In step S10, the controller 18 opens the inlet valve 68 and the outlet valve 56 to start the supply of wet hydrogen gas to the hydrogen booster stack 24. When the supply of wet hydrogen gas starts, the emergency start subroutine RT2 is completed. In this case, the stack start-up process ends.

[0057] As described above, in this embodiment, the controller 18 first causes liquid water to be supplied to the hydrogen booster stack 24 until a predetermined water supply period has elapsed. Thereafter, the controller 18 starts the supply of hydrogen gas to the hydrogen booster stack 24. After the predetermined hydrogen gas supply period has elapsed, the controller 18 starts the supply of current to the hydrogen booster stack 24.

[0058] Therefore, after the electrolyte membrane 30 of the unit cell 28 is uniformly saturated with water, the water content of the electrolyte membrane 30 can be appropriately adjusted by supplying hydrogen gas. This makes it possible to uniformize the water distribution in the electrolyte membrane 30 in a short period of time. As a result, the hydrogen boosting stack 24 can be started up quickly.

[0059] Furthermore, in this embodiment, the controller 18 closes the outlet valve 56 from when the supply of water is stopped until the supply of current is started. After the supply of current is started, the controller 18 opens the outlet valve 56. This allows dry hydrogen gas to be supplied to the hydrogen booster stack 24 until the supply of current is started. Therefore, the adjustment of the water content of the electrolyte membrane 30 can be completed early. Furthermore, after the supply of current is started, wet hydrogen gas can be supplied to the hydrogen booster stack 24. Therefore, the electrolyte membrane 30 can be prevented from drying out during operation of the hydrogen booster stack 24.

[0060] Furthermore, in this embodiment, the controller 18 uses the detector 78 to obtain an electrical value when the current in the hydrogen booster stack 24 is at a predetermined value. When the electrical value after a predetermined hydrogen gas supply period has elapsed is equal to or lower than a predetermined threshold value, the controller 18 opens the outlet valve 56. This allows the amount of water contained in the electrolyte membrane 30 to be adjusted to an appropriate amount before wet hydrogen gas is supplied to the hydrogen booster stack 24.

[0061] Furthermore, in this embodiment, if the electrical value after the hydrogen gas supply period has elapsed does not become equal to or lower than a predetermined threshold value, the control device 18 stops the supply of electrical current to the hydrogen booster stack 24 until the set time has elapsed. This makes it possible to suppress electrolysis of the water contained in the unit cell 28. As a result, it is possible to reduce the amount of oxygen gas generated by electrolysis of water that is discharged from the hydrogen booster stack 24 as an impure gas together with hydrogen gas.

[0062] Furthermore, in this embodiment, if the operation suspension period of the hydrogen booster stack 24 does not exceed a predetermined suspension period threshold, the control device 18 does not supply water to the hydrogen booster stack 24. On the other hand, if the operation suspension period of the hydrogen booster stack 24 exceeds a predetermined suspension period threshold, the control device 18 supplies water to the hydrogen booster stack 24. This makes it possible to avoid supplying water to the hydrogen booster stack 24 even when the electrolyte membrane 30 is not dry. As a result, the hydrogen booster stack 24 can be started up early. In addition, the deterioration of the electrolyte membrane 30 can be prevented from progressing more quickly, and the processing load on the control device 18 can be reduced.

[0063] The above embodiment can be modified as follows.

[0064] (Variation 1) Fig. 3 is a schematic diagram showing a modified electrochemical hydrogen boosting system 10. In Fig. 3, the same components as those described in the embodiment are denoted by the same reference numerals. Note that in this modified example, descriptions that overlap with the embodiment will be omitted.

[0065] In this modified example, a dehumidifier 80, a dehumidification path 82, and a path switch 84 are newly provided.

[0066] The dehumidifier 80 is a device that dehumidifies hydrogen gas. The dehumidifier 80 is provided in a dehumidification path 82. The dehumidifier 80, for example, cools the hydrogen gas flowing from the upstream of the dehumidification path 82, and separates moisture from the hydrogen gas.

[0067] The dehumidification path 82 branches off from the supply path 46 and is connected to the supply path 46 at a location downstream of the branching point. In this embodiment, the dehumidification path 82 branches off from the supply path 46 at a location downstream of the flow rate control valve 52. The dehumidification path 82 guides the dry hydrogen gas, from which moisture has been separated by the dehumidifier 80, to the supply path 46.

[0068] The path switch 84 switches whether or not the hydrogen gas supplied from the hydrogen supply source 14 is caused to flow through the dehumidification path 82 under the control of the control device 18. An example of the path switch 84 is a three-way valve. FIG 3 shows an example in which the path switch 84 is a three-way valve.

[0069] In this modification, the control device 18 allows hydrogen gas to flow through the dehumidification path 82 from when the supply of liquid water is stopped until when the supply of current is started. That is, in the case of this modification, in step S5, the control device 18 does not open the inlet valve 68 and the outlet valve 56, and in addition to opening the hydrogen supply valve 50, controls the path switch 84. In this case, the control device 18 switches the path downstream of the path switch 84 from the supply path 46 to the dehumidification path 82. Also, in the case of this modification, in step S10, the control device 18 opens the inlet valve 68 and the outlet valve 56, and in addition controls the path switch 84. In this case, the control device 18 switches the path downstream of the path switch 84 from the dehumidification path 82 to the supply path 46.

[0070] In this manner, in this modified example, during the period from when the supply of liquid water is stopped until the supply of current is started, the control device 18 causes the dehumidifier 80 to supply dry hydrogen gas to the hydrogen booster stack 24. This makes it possible to quickly complete the adjustment of the water content of the electrolyte membrane 30, which contains water uniformly.

[0071] (Variation 2) If the electrical value after the hydrogen gas supply period has elapsed does not become equal to or lower than the predetermined threshold value (FIG. 2: step S8: NO), the control device 18 may stop the start-up of the hydrogen booster stack 24. In this case, the control device 18 closes the hydrogen supply valve 50 to stop the supply of hydrogen gas to the hydrogen booster stack 24. The control device 18 also controls the power supply device 26 to stop the application of a predetermined voltage to the hydrogen booster stack 24, thereby stopping the supply of current to the hydrogen booster stack 24. This makes it possible to prevent the hydrogen booster stack 24 from being continuously operated in a state in which the generation efficiency of high-pressure hydrogen gas is poor.

[0072] (Variation 3) If the electrical value after the hydrogen gas supply period has elapsed does not become equal to or lower than the predetermined threshold value (FIG. 2: step S8: NO), the controller 18 may reduce the magnitude of the current supplied to the hydrogen booster stack 24 until the set time has elapsed. In this case, the controller 18 reduces the magnitude of the current supplied to the hydrogen booster stack 24 to be smaller than when the supply was started in step S7. This makes it possible to suppress electrolysis of the water contained in the unit cell 28. As a result, it is possible to reduce the amount of oxygen gas generated by the electrolysis of water that is discharged from the hydrogen booster stack 24 as an impure gas together with the high-pressure hydrogen gas.

[0073] (Variation 4) The water source does not have to be the humidifier 16. For example, the water source may be a water tank, a water purification facility, or the like.

[0074] (Variation 5) The bubble generator 64, the introduction path 66, and the introduction valve 68 may be omitted from the electrochemical hydrogen boosting system 10. The hydrogen gas flowing through the supply path 46 can be humidified even without providing the bubble generator 64, the introduction path 66, and the introduction valve 68. Therefore, the same effects as those of the above embodiment can be obtained even without providing the bubble generator 64, the introduction path 66, and the introduction valve 68.

[0075] The invention and effects that can be understood from the above description will be described below.

[0076] (1) The present invention provides an electrochemical hydrogen boosting system (10) comprising: a hydrogen boosting stack (24) provided with a unit cell (28) including an electrolyte membrane (30), an anode electrode (32), and a cathode electrode (34); a power supply device (26) that supplies current to the hydrogen boosting stack to generate high-pressure hydrogen gas in the hydrogen boosting stack having a higher pressure than the hydrogen gas supplied to the hydrogen boosting stack; and a hydrogen supply source (14) that supplies the hydrogen gas to the hydrogen boosting stack via a supply path (46) that communicates with the anode side of the unit cell. The electrochemical hydrogen boosting system includes a hydrogen supply valve (50) provided in the supply path, a path connector (62) that connects or disconnects a water source to the supply path via a water supply path (58), a water supply device (60) that supplies liquid water from the water source to the hydrogen boosting stack, and a control device (18) that controls the power supply device, the hydrogen supply valve, the path connector, and the water supply device. Upon receiving an operation start command, the control device causes the liquid water to be supplied from the water source to the hydrogen boosting stack until a predetermined water supply period has elapsed, and then starts the supply of hydrogen gas to the hydrogen boosting stack, and starts the supply of current to the hydrogen boosting stack after the predetermined hydrogen gas supply period has elapsed.

[0077] According to the present invention, after the electrolyte membrane of the unit cell is uniformly saturated with water, the water content of the electrolyte membrane can be appropriately adjusted by supplying hydrogen gas. This makes it possible to uniformize the water distribution in the electrolyte membrane in a short time. As a result, the hydrogen boosting stack can be started up quickly.

[0078] (2) The present invention provides an electrochemical hydrogen boost system as described in (1) above, comprising a humidifier (16) that supplies water vapor to the supply path via an outlet path (54), and an outlet valve (56) that is provided in the outlet path and controlled by the control device, and the control device may close the outlet valve from the time the supply of the liquid water is stopped until the supply of the current is started, and open the outlet valve after the supply of the current is started.

[0079] This allows dry hydrogen gas to be supplied to the hydrogen booster stack until the supply of current begins, thereby enabling the adjustment of the water content in the electrolyte membrane to be completed quickly. Furthermore, after the supply of current begins, wet hydrogen gas can be supplied to the hydrogen booster stack, thereby preventing the electrolyte membrane from drying out during operation of the hydrogen booster stack.

[0080] (3) The present invention is an electrochemical hydrogen boosting system as described in (2) above, comprising a detector (78) for detecting an electrical value indicating the voltage or resistance of the hydrogen boosting stack, and the control device may open the outlet valve if, after the hydrogen gas supply period has elapsed, the electrical value when the current of the hydrogen boosting stack is at a predetermined value is equal to or lower than a predetermined threshold value.

[0081] This allows the amount of water contained in the electrolyte membrane to be adjusted to an appropriate level before wet hydrogen gas is supplied to the hydrogen boosting stack.

[0082] (4) The present invention is an electrochemical hydrogen boost system as described in (3) above, wherein, after the hydrogen gas supply period has elapsed, if the electrical value when the current of the hydrogen boost stack is a predetermined value does not become equal to or below a predetermined threshold value, the control device may stop the supply of the hydrogen gas and the current to the hydrogen boost stack.

[0083] This makes it possible to prevent the hydrogen booster stack from being continuously operated in a state in which the generation efficiency of high-pressure hydrogen gas is poor.

[0084] (5) The present invention is an electrochemical hydrogen boost system as described in (3) above, wherein if, after the hydrogen gas supply period has elapsed, the electrical value when the current of the hydrogen boost stack is a predetermined value does not become equal to or below a predetermined threshold value, the control device may stop the supply of the current or reduce the magnitude of the current until a set time has elapsed.

[0085] This makes it possible to suppress electrolysis of the water contained in the unit cell, thereby reducing the amount of oxygen gas generated by the electrolysis of water that is discharged as an impure gas from the hydrogen boost stack together with the high-pressure hydrogen gas.

[0086] (6) The present invention is the electrochemical hydrogen boosting system described in (2) above, wherein the water source may be the humidifier.

[0087] This allows the number of parts in the electrochemical hydrogen boosting system to be reduced compared to when the water source is a tank or the like.

[0088] (7) The present invention is an electrochemical hydrogen boost system as described in (1) or (2) above, comprising a dehumidifier (80) provided in a dehumidification path (82) branching off from the supply path and connected to the supply path downstream of the branched portion, for dehumidifying the hydrogen gas, and a path switch (84) for switching whether or not the hydrogen gas supplied from the hydrogen supply source is caused to flow through the dehumidification path in accordance with the control of the control device, and the control device may cause the hydrogen gas to flow through the dehumidification path during the period from when the supply of the liquid water is stopped until when the supply of the current is started, and supply the hydrogen gas dehumidified by the dehumidifier to the hydrogen boost stack.

[0089] This makes it possible to quickly complete the adjustment of the water content of the electrolyte membrane that contains water uniformly.

[0090] (8) The present invention is an electrochemical hydrogen boosting system as described in (1) or (2) above, wherein when the operation shutdown period of the hydrogen boosting stack exceeds a predetermined shutdown period threshold, the control device may supply the water from the water source to the hydrogen boosting stack.

[0091] This makes it possible to suppress electrolysis of the water contained in the unit cell, thereby reducing the amount of oxygen gas generated by the electrolysis of water that is discharged as an impure gas from the hydrogen booster stack 24 together with the high-pressure hydrogen gas.

[0092] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0093] 10...Electrochemical hydrogen boosting system 12...Electrochemical hydrogen boosting device 14...Hydrogen supply source 16...Humidifier 18...Control device 24...Hydrogen booster stack 26...Power supply unit 28...Unit cell 30...electrolyte membrane 32...anode electrode 34: cathode electrode; 38: sealed container 46…Supply route 54…Extraction route 56...Outlet valve 58...Water supply path 60... Water supply device 62... Path connector 78...Detector 80...Dehumidifier 82... Dehumidification path 84... Path switch

Claims

1. a hydrogen boosting stack including a unit cell including an electrolyte membrane, an anode electrode, and a cathode electrode; a power supply device that supplies a current to the hydrogen booster stack to generate high-pressure hydrogen gas in the hydrogen booster stack, the high-pressure hydrogen gas having a pressure higher than that of the hydrogen gas supplied to the hydrogen booster stack; a hydrogen supply source that supplies the hydrogen gas to the hydrogen boosting stack through a supply path that communicates with an anode side of the unit cell; An electrochemical hydrogen boosting system comprising: a hydrogen supply valve provided in the supply path; a path connector for connecting or disconnecting a water source to the water supply path via the water supply path; a water supply device that supplies liquid water from the water source to the hydrogen booster stack; a control device that controls the power supply device, the hydrogen supply valve, the path connector, and the water supply device; Equipped with When the control device receives a start operation command, it supplies liquid water from the water source to the hydrogen boost stack until a predetermined water supply period has elapsed, and after the electrolyte membrane of each unit cell is uniformly saturated with the liquid water, it starts the supply of hydrogen gas to the hydrogen boost stack, adjusts the water content of the electrolyte membrane, and after a predetermined hydrogen gas supply period has elapsed, starts the supply of current to the hydrogen boost stack.

2. 2. The electrochemical hydrogen boosting system according to claim 1, a humidifier that supplies water vapor to the supply path through an outlet path; an outlet valve provided in the outlet path and controlled by the control device; Equipped with The control device closes the outlet valve from the time the supply of the liquid water is stopped until the supply of the current is started, and opens the outlet valve after the supply of the current is started.

3. 3. The electrochemical hydrogen boosting system according to claim 2, a detector for detecting an electrical value indicative of a voltage or resistance of the hydrogen boosting stack; An electrochemical hydrogen boosting system, wherein after the hydrogen gas supply period has elapsed, if the electrical value when the current of the hydrogen boosting stack is a predetermined value is below a predetermined threshold, the control device opens the outlet valve, and if the electrical value does not become below the predetermined threshold, the control device stops the supply of the hydrogen gas and the current to the hydrogen boosting stack.

4. 3. The electrochemical hydrogen boosting system according to claim 2, a detector for detecting an electrical value indicative of a voltage or resistance of the hydrogen boosting stack; An electrochemical hydrogen boosting system, wherein after the hydrogen gas supply period has elapsed, if the electrical value when the current of the hydrogen boosting stack is a predetermined value is below a predetermined threshold, the control device opens the outlet valve, and if the electrical value does not become below the predetermined threshold, the control device stops the supply of the current or reduces the magnitude of the current until a set period has elapsed.

5. 3. The electrochemical hydrogen boosting system according to claim 2, The electrochemical hydrogen boosting system, wherein the water source is the humidifier.

6. 3. The electrochemical hydrogen boosting system according to claim 1 or 2, a dehumidifier provided in a dehumidification path that branches off from the supply path and is connected to the supply path downstream of the branched portion, and that dehumidifies the hydrogen gas; a path switcher that switches whether or not the hydrogen gas supplied from the hydrogen supply source is allowed to flow through the dehumidification path under the control of the control device; Equipped with The control device causes the hydrogen gas to flow through the dehumidification path from the time when the supply of the liquid water is stopped until the supply of the current is started, and supplies the hydrogen gas dehumidified by the dehumidifier to the hydrogen boost stack.

7. 3. The electrochemical hydrogen boosting system according to claim 1 or 2, An electrochemical hydrogen boosting system, wherein if the shutdown period of the hydrogen booster stack does not exceed a predetermined shutdown period threshold, the control device does not supply water to the hydrogen booster stack, and if the shutdown period of the hydrogen booster stack exceeds the predetermined shutdown period threshold, the control device supplies water from the water source to the hydrogen booster stack.

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