Water electrolysis system

Abstract

SOLUTION: A water electrolysis system 10 comprises a water electrolysis device 14 electrolyzing water, a gas-liquid separator 16 applying gas-liquid separation to a mixed fluid of hydrogen gas and water drawn out of the water electrolysis device, a dehumidifier 18 dehumidifying the hydrogen gas separated from the mixed fluid by the gas-liquid separator, a transfer path 22 transferring the hydrogen gas dehumidified by the dehumidifier, a humidifier 24 humidifying the hydrogen gas transferred via the transfer path, and a pressure boosting device 28 boosting the pressure of the hydrogen gas humidified by the humidifier.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a water electrolysis system. [Background technology]

[0002] In recent years, technological developments have been underway in power systems that contribute to energy efficiency in order to ensure that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] Patent Document 1 discloses a water electrolysis system including a water electrolysis device, a gas-liquid separator, a transfer path, and a pressure booster. The water electrolysis device electrolyzes water. The gas-liquid separator separates a mixed fluid of hydrogen gas and liquid water delivered from the water electrolysis device into gas and liquid. The transfer path transports the hydrogen gas separated from the mixed fluid by the gas-liquid separator. The pressure booster boosts the pressure of the hydrogen gas delivered from the transfer path. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2022-83098 Summary of the Invention [Problem to be solved by the invention]

[0005] A better water electrolysis system is needed.

[0006] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0007] An aspect of the present disclosure is a water electrolysis system including: a water electrolysis device that electrolyzes water; a gas-liquid separator that separates a mixed fluid of hydrogen gas and water delivered from the water electrolysis device into gas and liquid; a dehumidifier that dehumidifies the hydrogen gas separated from the mixed fluid by the gas-liquid separator; a transfer path that transfers the hydrogen gas dehumidified by the dehumidifier; a humidifier that humidifies the hydrogen gas transferred via the transfer path; and a booster device that boosts the pressure of the hydrogen gas humidified by the humidifier. [Effects of the Invention]

[0008] According to the present disclosure, a better water electrolysis system can be provided. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a water electrolysis system according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic diagram of a water electrolysis system including a water supply unit according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] In a water electrolysis system, hydrogen gas separated from a mixed fluid by a gas-liquid separator contains water vapor. In this case, the hydrogen gas introduced into the booster device via the transfer path also contains water vapor, and the water vapor can humidify the electrolyte membrane constituting the booster device. However, when the ambient temperature of the transfer path is relatively low, condensation water may occur in the transfer path, making it impossible to appropriately control the humidity of the hydrogen gas introduced into the booster device. There is also a risk of the transfer path being clogged by condensation water. The present disclosure has been made in view of these problems and provides a water electrolysis system that suppresses clogging of the transfer path by condensation water and can appropriately control the humidity of the hydrogen gas introduced into the booster device.

[0011] FIG. 1 is a schematic diagram of a water electrolysis system 10 according to an embodiment of the present disclosure. The water electrolysis system 10 may constitute, for example, a part of a circulatory renewable energy system 12. The circulatory renewable energy system 12 is a system that combines the water electrolysis system 10, which electrolyzes water to produce oxygen gas and hydrogen gas, with a fuel cell system that generates electricity and water through an electrochemical reaction between the oxygen gas and the hydrogen gas. In the circulatory renewable energy system 12, the water electrolysis system 10 uses water produced in the fuel cell system to produce oxygen gas and hydrogen gas required for power generation by the fuel cell system.

[0012] Such a circulatory renewable energy system 12 may be installed, for example, on the Earth or the surface of the moon. The circulatory renewable energy system 12 may also be mounted on an artificial satellite such as the International Space Station (ISS). The water electrolysis system 10 is not limited to being installed in the circulatory renewable energy system 12, and may be installed in, for example, a hydrogen station.

[0013] As shown in FIG. 1 , the water electrolysis system 10 includes a water electrolysis device 14, a gas-liquid separator 16, a dehumidifier 18, a first hydrogen supply path 20, a transfer path 22, a humidifier 24, a second hydrogen supply path 26, a pressure booster (electrochemical pressure booster) 28, and a water supply unit 30.

[0014] The water electrolysis device 14 generates oxygen gas and hydrogen gas by electrolyzing water (pure water). The water electrolysis device 14 is, for example, a solid polymer water electrolysis device. The water electrolysis device 14 may also be an alkaline water electrolysis device, a solid oxide water electrolysis device, or the like.

[0015] The water electrolysis device 14 includes a water electrolysis stack 32 and a water electrolysis power supply 34. The water electrolysis stack 32 includes a plurality of water electrolysis cells 36 stacked on top of each other. The water electrolysis power supply 34 is a DC power supply. The water electrolysis power supply 34 applies a voltage between the anode power supply and the cathode power supply of the water electrolysis cells 36.

[0016] Detailed illustration of the water electrolysis cell 36 is omitted. In the water electrolysis cell 36, water is supplied to the cathode flow channel of the water electrolysis cell 36, and the water electrolysis power supply 34 applies a voltage between the anode power supply and the cathode power supply, thereby electrolyzing water. As a result, oxygen gas is generated in the anode flow channel of the water electrolysis cell 36, and hydrogen gas is generated in the cathode flow channel of the water electrolysis cell 36. The ion exchange membrane of the water electrolysis cell 36 prevents the oxygen gas generated in the anode flow channel from passing to the cathode flow channel. This allows oxygen gas to be stored in the anode flow channel, making it possible to generate high-pressure oxygen gas in the anode flow channel.

[0017] High-pressure oxygen gas generated in the anode flow path of the water electrolysis cell 36 is discharged to the outside of the water electrolysis device 14 via the oxygen gas discharge path 38. The oxygen gas discharge path 38 guides the oxygen gas to, for example, an oxygen gas tank of a fuel cell system (not shown). The hydrogen gas generated in the cathode flow path is guided together with water (liquid water) to the gas-liquid separator 16 via the hydrogen gas discharge path 40.

[0018] The gas-liquid separator 16 separates the mixed fluid of hydrogen gas and water introduced via the hydrogen gas outlet channel 40 into gas and liquid. The gas-liquid separator 16 has a reservoir 42 that stores the water (liquid water) separated from the mixed fluid. Water (liquid water) is supplied to the gas-liquid separator 16 from a water inlet channel 44. Water generated by power generation in a fuel cell system (not shown), for example, is introduced into the water inlet channel 44. Note that water produced by a pure water production system (not shown) may also be introduced into the water inlet channel 44. The water stored in the reservoir 42 is supplied to the water electrolysis device 14 via a water supply unit 30. The detailed configuration of the water supply unit 30 will be described later. The hydrogen gas separated from the mixed fluid by the gas-liquid separator 16 contains water vapor.

[0019] The first hydrogen supply path 20 connects the gas-liquid separator 16 and the dehumidifier 18. The first hydrogen supply path 20 guides the hydrogen gas separated from the mixed fluid by the gas-liquid separator 16 to the dehumidifier 18. A deoxygenation catalyst 46 is provided in the first hydrogen supply path 20. The deoxygenation catalyst 46 removes oxygen from the hydrogen gas. The deoxygenation catalyst 46 contains, for example, platinum.

[0020] The dehumidifier 18 dehumidifies the hydrogen gas introduced through the first hydrogen supply channel 20. In other words, the dehumidifier 18 dehumidifies the hydrogen gas separated from the mixed fluid by the gas-liquid separator 16. The dehumidifier 18 is a membrane dehumidifier. The membrane dehumidifier has a plurality of hollow fiber membranes 48 and an outer casing 50 that houses these hollow fiber membranes 48.

[0021] The hollow fiber membrane 48 is made of a material that is permeable to water vapor but not to hydrogen gas. Hydrogen gas (including water vapor) introduced from the first hydrogen supply channel 20 flows inside the hollow fiber membrane 48. A dehumidification space 52 for circulating dried hydrogen gas is formed outside the hollow fiber membrane 48. The dehumidification space 52 is covered by an outer tube 50. In this case, the water vapor pressure inside the hollow fiber membrane 48 is higher than the water vapor pressure in the dehumidification space 52, and the water vapor pressure difference causes the water vapor contained in the hydrogen gas to permeate the hollow fiber membrane 48 and move to the dehumidification space 52. This dehumidifies the hydrogen gas. In such a membrane dehumidifier, temperature changes in the hydrogen gas can be suppressed compared to when hydrogen gas is dehumidified by cooling it.

[0022] The transfer path 22 transfers the hydrogen gas dehumidified by the dehumidifier 18 to the humidifier 24. The transfer path 22 is a relatively long flow path. The transfer path 22 is longer than each of the first hydrogen supply path 20 and the second hydrogen supply path 26. The transfer path 22 may also be longer than the combined length of the first hydrogen supply path 20 and the second hydrogen supply path 26. The transfer path 22 is provided with a hydrogen pump 54 and a branch path 56. The hydrogen pump 54 sends the hydrogen gas guided from the dehumidifier 18 toward the pressure booster 28 (humidifier 24). This prevents condensation from forming on the hydrogen pump 54. The branch path 56 branches off from a portion of the transfer path 22 downstream of the hydrogen pump 54. This prevents hydrogen gas containing water vapor from flowing back from the branch path 56 (gas-liquid separator 16).

[0023] The branch path 56 guides the hydrogen gas flowing through the transfer path 22 to the dehumidifier 18. Specifically, the branch path 56 guides dried hydrogen gas to the dehumidification space 52 of the dehumidifier 18. The hydrogen gas introduced into the dehumidification space 52 from the branch path 56 is returned to the gas-liquid separator 16 via the return path 58 together with the water vapor (moisture) contained in the dehumidification space 52. This allows the dried hydrogen gas to maintain the dehumidification space 52 in a dry state. In other words, the water vapor pressure in the dehumidification space 52 can be made lower than the water vapor pressure inside the hollow fiber membrane 48, so that the hydrogen gas can be dehumidified efficiently.

[0024] The branch path 56 is provided with an oxygen sensor 60 that measures the oxygen concentration in the dry hydrogen gas flowing through the branch path 56. In this case, the formation of condensation water on the oxygen sensor 60 can be suppressed.

[0025] The humidifier 24 humidifies the dried hydrogen gas transported via the transport path 22. The humidifier 24 is a membrane humidifier. A membrane humidifier has a configuration similar to that of a membrane dehumidifier. That is, the membrane humidifier has a plurality of hollow fiber membranes 62 and an outer cylinder 64 that houses these hollow fiber membranes 62.

[0026] The hollow fiber membrane 62 is made of a material that is permeable to water vapor but not to hydrogen gas. Dry hydrogen gas introduced from the transfer path 22 flows inside the hollow fiber membrane 62. A humidification space 66 for circulating water vapor is formed on the outside of the hollow fiber membrane 62. The humidification space 66 is covered by an outer tube 64. In this case, the water vapor pressure in the humidification space 66 is higher than the water vapor pressure inside the hollow fiber membrane 62, and the water vapor pressure difference causes the water vapor in the humidification space 66 to permeate the hollow fiber membrane 62 and move into the interior of the hollow fiber membrane 62. This humidifies the hydrogen gas.

[0027] The second hydrogen supply passage 26 connects the humidifier 24 and the pressure booster 28. The second hydrogen supply passage 26 introduces the hydrogen gas humidified by the humidifier 24 into the pressure booster 28.

[0028] The booster device 28 is an electrochemical hydrogen pump that electrochemically boosts the pressure of hydrogen gas introduced from the second hydrogen supply channel 26. The booster device 28 has a booster stack 68 and a booster power supply 70. The booster stack 68 includes a plurality of booster cells 72 stacked on top of each other. The booster power supply 70 is a DC power supply. The booster power supply 70 applies a voltage between the anode power supply and the cathode power supply of the booster cell 72.

[0029] Detailed illustration of the booster cell 72 is omitted. In the booster cell 72, humidified hydrogen gas is supplied to the anode flow channel, and the booster power supply 70 applies a voltage between the anode power supply and the cathode power supply. This generates hydrogen ions in the anode flow channel, and these hydrogen ions pass through the ion exchange membrane of the booster cell 72 and are guided to the cathode flow channel. In the cathode flow channel, the hydrogen ions combine to generate hydrogen gas. The ion exchange membrane of the booster cell 72 prevents the hydrogen gas generated in the cathode flow channel from passing into the anode flow channel. This allows hydrogen gas to be stored in the cathode flow channel, allowing high-pressure hydrogen gas to be generated in the cathode flow channel.

[0030] High-pressure hydrogen gas generated in the cathode flow path of the booster cell 72 is discharged to the outside of the booster device 28 via a hydrogen gas discharge path 74. The hydrogen gas discharge path 74 leads the hydrogen gas to, for example, a hydrogen gas tank of a fuel cell system (not shown).

[0031] The water vapor contained in the hydrogen gas flowing through the anode flow path of the booster cell 72 humidifies the ion exchange membrane of the booster cell 72. This prevents the ion exchange membrane of the booster cell 72 from becoming excessively dry. The unreacted hydrogen gas guided from the anode flow path of the booster cell 72 is returned to the gas-liquid separator 16 together with the water vapor via the circulation flow path 76.

[0032] The water supply unit 30 includes a first water supply channel 78, a second water supply channel 80, a water pump 82, and a heat exchanger 84. The first water supply channel 78 connects the gas-liquid separator 16 and the humidifier 24. The first water supply channel 78 guides water (liquid water) stored in the reservoir 42 of the gas-liquid separator 16 to the humidifier 24. Specifically, the first water supply channel 78 guides water to the humidification space 66 of the humidifier 24. The water introduced into the humidification space 66 from the first water supply channel 78 can generate water vapor in the humidification space 66. This allows the water vapor pressure in the humidification space 66 to be higher than the water vapor pressure inside the hollow fiber membrane 62, thereby enabling efficient humidification of hydrogen gas. A heating device (not shown) may also be provided in the first water supply channel 78. This allows the hydrogen gas in the humidification space 66 to be heated while being humidified.

[0033] The second water supply channel 80 connects the humidifier 24 and the water electrolysis device 14. The second water supply channel 80 guides water (liquid water) that has flowed through the humidifier 24 to the water electrolysis device 14. The water pump 82 is provided in the second water supply channel 80. The water pump 82 sends the water flowing through the second water supply channel 80 to the water electrolysis device 14. The location where the water pump 82 is provided can be set as appropriate, and may be, for example, the first water supply channel 78.

[0034] The heat exchanger 84 is provided in a portion of the second water supply channel 80 downstream of the water pump 82. The location of the heat exchanger 84 can be set as appropriate, and for example, the heat exchanger 84 may be provided in a portion of the second water supply channel 80 upstream of the water pump 82, or in the first water supply channel 78. The heat exchanger 84 adjusts the temperature of the water supplied to the water electrolysis device 14. This allows water at an appropriate temperature to be supplied to the water electrolysis device 14.

[0035] Water stored in reservoir 42 of gas-liquid separator 16 is circulated by water pump 82 through first water supply channel 78, humidifier 24, second water supply channel 80, water electrolysis device 14, and hydrogen gas outlet channel 40. Therefore, water whose temperature has been adjusted by heat exchanger 84 is introduced into humidification space 66 of humidifier 24. Therefore, humidifier 24 can adjust the temperature of the hydrogen gas to an appropriate temperature by using water vapor generated from the water.

[0036] Next, the operation of the water electrolysis system 10 will be described. In the water electrolysis system 10, when the water pump 82 is driven, water (liquid water) stored in the reservoir 42 of the gas-liquid separator 16 is supplied to the water electrolysis device 14 via the first water supply channel 78, the humidifier 24, and the second water supply channel 80. In the water electrolysis device 14, high-pressure oxygen gas and low-pressure hydrogen gas are generated by electrolysis of water. The high-pressure oxygen gas is guided to the outside of the water electrolysis device 14 via the oxygen gas outlet channel 38. A mixed fluid of low-pressure hydrogen gas and water (liquid water) is guided to the gas-liquid separator 16 via the hydrogen gas outlet channel 40.

[0037] The mixed fluid introduced from the hydrogen gas outlet path 40 to the gas-liquid separator 16 is separated into hydrogen gas (including water vapor) and water (liquid water) by the gas-liquid separator 16. The water separated from the mixed fluid is stored in a reservoir 42 and reused.

[0038] The hydrogen gas containing water vapor separated from the mixed fluid is drawn into the dehumidifier 18 by the hydrogen pump 54 via the first hydrogen supply channel 20 and the deoxidizing catalyst 46. The dehumidifier 18 dehumidifies the hydrogen gas. The hydrogen gas dehumidified by the dehumidifier 18 (dry hydrogen gas) is sent to the humidifier 24 via the transfer channel 22 by the hydrogen pump 54. Because the hydrogen gas flowing through the transfer channel 22 is dry, it is possible to prevent condensation from forming on the transfer channel 22 even when the water electrolysis system 10 is operated in a low-temperature environment, for example. The humidifier 24 appropriately humidifies the hydrogen gas and adjusts its temperature to an appropriate level. The hydrogen gas humidified and temperature-adjusted by the humidifier 24 is introduced into the pressure booster 28 via the second hydrogen supply channel 26.

[0039] The humidified hydrogen gas is pressurized in the pressure booster 28. The pressurized, high-pressure hydrogen gas is led to the outside of the pressure booster 28 via a hydrogen gas discharge path 74. The water vapor humidifies the electrolyte membrane of the pressure booster cell 72. The hydrogen gas that did not react in the pressure booster 28 is led to the gas-liquid separator 16 via a circulation path 76 together with the excess water vapor.

[0040] According to the present embodiment, the hydrogen gas separated from the mixed fluid by the gas-liquid separator 16 is dehumidified by the dehumidifier 18, and the dehumidified hydrogen gas is introduced into the transfer path 22. Therefore, even if the temperature around the transfer path 22 is relatively low, it is possible to prevent condensation from occurring inside the transfer path 22. Furthermore, the hydrogen gas transferred via the transfer path 22 is humidified by the humidifier 24, and the humidified hydrogen gas is introduced into the booster device 28. This allows the humidity of the hydrogen gas introduced into the booster device 28 to be appropriately controlled. Therefore, a better water electrolysis system 10 can be provided.

[0041] (Variation) Next, a water supply unit 30a according to a modified example will be described. In the water supply unit 30a according to the modified example, the same components as those in the water supply unit 30 described above will be assigned the same reference numerals, and detailed description thereof will be omitted.

[0042] FIG. 2 is a schematic diagram of a water electrolysis system 10 including a water supply unit 30a according to a modified example. As shown in FIG. 2, the water supply unit 30a includes a first section 86 for supplying water to the humidifier 24 and a second section 88 for supplying water to the water electrolysis device 14. The first section 86 and the second section 88 are separate from each other. The first section 86 includes a first water supply channel 78, a water return flow path 90, and a first water pump 92. The water return flow path 90 connects the humidifier 24 and the gas-liquid separator 16. The water return flow path 90 guides water (liquid water) that has flowed through the humidifier 24 to the gas-liquid separator 16. The first water pump 92 is provided in the water return flow path 90. The first water pump 92 sends water flowing through the water return flow path 90 to the gas-liquid separator 16. The first water pump 92 may be provided at any suitable location, such as the first water supply channel 78.

[0043] The second section 88 has a second water supply channel 94, a second water pump 96, and the heat exchanger 84. The second water supply channel 94 connects the gas-liquid separator 16 and the water electrolysis device 14. The second water supply channel 94 guides water stored in the reservoir 42 of the gas-liquid separator 16 to the water electrolysis device 14. The second water pump 96 is provided in the second water supply channel 94. The second water pump 96 sends water circulating through the second water supply channel 94 to the water electrolysis device 14.

[0044] In this modification, the water supply unit 30a is divided into a first section 86 that supplies water to the humidifier 24 and a second section 88 that supplies water to the water electrolysis device 14. The first section 86 includes a first water pump 92, and the second section 88 includes a second water pump 96. This allows the flow rates of water supplied to the humidifier 24 and the water electrolysis device 14 to be individually adjusted depending on the operating state of the water electrolysis system 10, the ambient temperature, etc.

[0045] This embodiment is not limited to the above-described configuration. The water electrolysis system 10 does not necessarily have to include the deoxidizing catalyst 46. The oxygen sensor 60 may be provided in the transfer path 22.

[0046] The following additional notes are further disclosed regarding the above embodiment.

[0047] (Appendix 1) A water electrolysis system (10) according to the present disclosure includes a water electrolysis device (14) that electrolyzes water, a gas-liquid separator (16) that separates a mixed fluid of hydrogen gas and water delivered from the water electrolysis device into gas and liquid, a dehumidifier (18) that dehumidifies the hydrogen gas separated from the mixed fluid by the gas-liquid separator, a transfer path (22) that transfers the hydrogen gas dehumidified by the dehumidifier, a humidifier (24) that humidifies the hydrogen gas transferred via the transfer path, and a pressure booster (28) that boosts the pressure of the hydrogen gas humidified by the humidifier.

[0048] According to this configuration, the hydrogen gas separated from the mixed fluid by the gas-liquid separator is dehumidified by the dehumidifier, and the dehumidified hydrogen gas is introduced into the transfer path. Therefore, even if the temperature around the transfer path is relatively low, it is possible to prevent condensation from occurring in the transfer path. Furthermore, the hydrogen gas transferred through the transfer path is humidified by the humidifier, and the humidified hydrogen gas is introduced into the booster device. This allows the humidity of the hydrogen gas introduced into the booster device to be appropriately controlled. Therefore, a better water electrolysis system can be provided.

[0049] (Appendix 2) In the water electrolysis system according to Supplementary Note 1, the moisture obtained by dehumidifying the hydrogen gas with the dehumidifier may be introduced into either the gas-liquid separator or the humidifier.

[0050] According to this configuration, the moisture obtained by dehumidifying the hydrogen gas with the dehumidifier can be reused.

[0051] (Appendix 3) In the water electrolysis system according to Supplementary Note 1 or 2, the dehumidifier may be a membrane dehumidifier.

[0052] With this configuration, it is possible to suppress temperature changes in the hydrogen gas when the hydrogen gas is dehumidified.

[0053] (Appendix 4) In the water electrolysis system according to any one of Supplementary Notes 1 to 3, the water obtained by either the gas-liquid separator or the dehumidifier may be introduced to the humidifier.

[0054] With this configuration, water can be efficiently supplied to the humidifier.

[0055] (Appendix 5) In the water electrolysis system according to Supplementary Note 4, the gas-liquid separator may have a storage unit (42) for storing water, and may further include a water supply unit (30, 30a) for supplying the water stored in the storage unit to the humidifier and the water electrolysis device.

[0056] With this configuration, there is no need to provide separate sections for storing water to be supplied to the humidifier and water to be supplied to the water electrolysis device, making it possible to make the water electrolysis system more compact.

[0057] (Appendix 6) In the water electrolysis system according to Supplementary Note 5, the water supply unit may include a heat exchanger (84) for adjusting the temperature of water supplied to the humidifier and the water electrolysis device.

[0058] With this configuration, the heat exchanger can adjust the temperature of the water supplied to the water electrolysis device, and the humidifier can humidify the hydrogen gas introduced from the transport path and adjust the temperature to an appropriate level.

[0059] (Appendix 7) In the water electrolysis system according to any one of Supplementary Notes 1 to 6, the humidifier may be a membrane humidifier.

[0060] With this configuration, the hydrogen gas can be efficiently humidified.

[0061] (Appendix 8) In the water electrolysis system according to any one of Supplementary Notes 1 to 7, the transfer path may be provided with a pump (54) for transferring hydrogen gas guided from the dehumidifier to the pressure booster.

[0062] With this configuration, hydrogen gas dehumidified by the dehumidifier (dry hydrogen gas) flows through the pump, which prevents condensation from forming in the pump, thereby preventing the durability of the pump from being reduced by condensation.

[0063] (Appendix 9) The water electrolysis system according to any one of Supplementary Notes 1 to 8 may further include an oxygen sensor (60) for measuring the oxygen concentration in the hydrogen gas flowing through the transfer path.

[0064] With this configuration, hydrogen gas dehumidified by the dehumidifier (dry hydrogen gas) flows through the oxygen sensor, which prevents condensation from forming on the oxygen sensor, thereby preventing the durability of the oxygen sensor from being reduced by condensation.

[0065] (Appendix 10) In the water electrolysis system according to Supplementary Note 8, the transfer path may include a branch path (56) branching off from a portion of the transfer path downstream of the pump, and the moisture obtained by the dehumidifier may be returned to the gas-liquid separator by hydrogen gas flowing through the branch path.

[0066] With this configuration, the moisture generated in the dehumidifier can be returned to the gas-liquid separator by the hydrogen gas sent from the pump and guided to the branch path, eliminating the need to provide an additional pump for returning the moisture generated in the dehumidifier to the gas-liquid separator, thereby reducing the cost and size of the water electrolysis system.

[0067] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments. [Explanation of symbols]

[0068] 10...Water electrolysis system 14...Water electrolysis device 16... Gas-liquid separator 18... Dehumidifier 22...Transport path 24...Humidifier 28... Pressure booster device 30, 30a... Water supply unit 42...Storage section 54...Hydrogen pump (pump) 56... Branch path 60... Oxygen sensor 84...Heat exchanger

Claims

1. a water electrolysis device that electrolyzes water; a gas-liquid separator that separates a mixed fluid of hydrogen gas and water delivered from the water electrolysis device into gas and liquid; a dehumidifier that dehumidifies the hydrogen gas separated from the mixed fluid by the gas-liquid separator; a transport path for transporting the hydrogen gas dehumidified by the dehumidifier; a humidifier that humidifies the hydrogen gas transported through the transport path; a pressure booster that boosts the pressure of the hydrogen gas humidified by the humidifier; A water electrolysis system comprising:

2. The water electrolysis system according to claim 1, the water obtained by dehumidifying the hydrogen gas with the dehumidifier is guided to either the gas-liquid separator or the humidifier.

3. The water electrolysis system according to claim 1, The water electrolysis system, wherein the dehumidifier is a membrane dehumidifier.

4. The water electrolysis system according to claim 1, a water electrolysis system, wherein the water obtained by either the gas-liquid separator or the dehumidifier is introduced to the humidifier.

5. The water electrolysis system according to claim 4, the gas-liquid separator has a storage section for storing water, The water electrolysis system further comprises a water supply unit configured to supply the water stored in the storage unit to the humidifier and the water electrolysis device.

6. The water electrolysis system according to claim 5, a water electrolysis system, wherein the water supply unit includes a heat exchanger for adjusting the temperature of water supplied to the humidifier and the water electrolysis device.

7. The water electrolysis system according to claim 1, The water electrolysis system, wherein the humidifier is a membrane humidifier.

8. The water electrolysis system according to any one of claims 1 to 7, a pump provided in the transfer path for sending the hydrogen gas guided from the dehumidifier to the pressure booster.

9. The water electrolysis system according to claim 1, The water electrolysis system further includes an oxygen sensor for measuring the oxygen concentration in the hydrogen gas flowing through the transport path.

10. The water electrolysis system according to claim 8, the conveying path is provided with a branch path that branches off from a portion of the conveying path downstream of the pump, the moisture obtained by the dehumidifier is returned to the gas-liquid separator by the hydrogen gas flowing through the branch path.

Images