Operation method of water electrolysis power generation system

Abstract

The present invention relates to an operating method for a water electrolysis power generation system. The operating method for the water electrolysis power generation system (10) includes a water electrolysis stopping process, a purification process, and a power generation starting process when switching from a water electrolysis mode to a power generation mode. In the purification process, after the water electrolysis stopping process, the oxidant gas is circulated from the oxidant gas flow path (106) through the oxidant gas introduction flow path (108), the first supply flow path (82), the first inlet port (56a), the first fluid flow path (44), the first outlet port (56b), and the first outlet flow path (84) to the first gas-liquid separator (80). In the power generation starting process, after the purification process, the battery unit (12) is caused to generate electricity according to a specified load request value. Accordingly, the switching from the water electrolysis mode to the power generation mode can be performed smoothly and reliably.

Description

Technical Field

[0001] The invention relates to an operating method of a water electrolysis power generation system. Background Art

[0002] For example, Japanese Patent Publication No. 2015-191846 discloses a water electrolysis power generation system having a cell member. The cell member includes an MEA, a first fluid flow path, and a second fluid flow path. The MEA includes an electrolyte membrane and a first electrode and a second electrode that sandwich the electrolyte membrane. The first fluid flow path is a flow path for supplying water and oxidant gas to the first electrode. The second fluid flow path is a flow path for supplying hydrogen to the second electrode. The water electrolysis power generation system can switch between a water electrolysis mode and a power generation mode. In the water electrolysis mode, the water electrolysis power generation system electrolyzes the water supplied to the first electrode to generate hydrogen at the second electrode. In the power generation mode, the water electrolysis power generation system generates electricity through the electrochemical reaction of the oxidant gas supplied to the first electrode and the hydrogen supplied to the second electrode. Summary of the Invention

[0003] In the above-mentioned water electrolysis power generation system, it is desired to be able to smoothly and reliably switch between the power generation mode and the water electrolysis mode.

[0004] The purpose of the present invention is to solve the above-mentioned technical problems.

[0005] One embodiment of the present invention is an operating method of a water electrolysis power generation system, wherein the water electrolysis power generation system has a battery component including a battery, the battery component has an MEA, a first fluid flow path and a second fluid flow path, wherein the MEA is composed of an electrolyte membrane sandwiched by a first electrode and a second electrode, the first fluid flow path is used to supply water and an oxidant gas to the first electrode; the second fluid flow path is used to supply hydrogen to the second electrode, and the water electrolysis power generation system can be switched between a water electrolysis mode and a power generation mode, wherein the water electrolysis mode refers to the operation of the water supplied to the The water at the first electrode is electrolyzed to generate hydrogen at the second electrode; the power generation mode refers to a mode in which power is generated by an electrochemical reaction between the oxidant gas supplied to the first electrode and the hydrogen supplied to the second electrode, and the water electrolysis power generation system comprises a supply flow path, an outlet flow path, a water inlet flow path, an oxidant gas flow path, an oxidant gas inlet flow path and a gas-liquid separator, wherein the supply flow path is connected to an inlet port portion communicating with the first fluid flow path; the outlet flow path is connected to an outlet port portion communicating with the first fluid flow path, and in the water electrolysis mode The gas-containing water containing the generated hydrogen is led out to the lead-out flow path; the water inlet flow path is used to lead the water into the supply flow path; the oxidant gas flow path is used to circulate the oxidant gas; the oxidant gas inlet flow path is used to lead the oxidant gas flowing in the oxidant gas flow path into the supply flow path; the gas-liquid separator performs gas-liquid separation on the gas-containing water guided from the lead-out flow path, and the operation method of the water electrolysis power generation system includes a water electrolysis stopping process, a purification process (pu rgeprocess) and power generation start process, wherein the water electrolysis stopping process refers to the process of stopping the water electrolysis performed by the battery component; the purification process refers to the process of causing the oxidant gas to flow from the oxidant gas flow path through the oxidant gas inlet flow path, the supply flow path, the inlet port part, the first fluid flow path, the outlet port part and the derivation flow path to the gas-liquid separator after the water electrolysis stopping process; the power generation start process refers to the process of causing the battery component to generate electricity according to a specified load request value after the purification process.

[0006] Another embodiment of the present invention is an operating method of a water electrolysis power generation system, wherein the water electrolysis power generation system has a battery component, the battery component has an MEA, a first fluid flow path and a second fluid flow path, wherein the MEA is composed of an electrolyte membrane sandwiched by a first electrode and a second electrode; the first fluid flow path is used to supply water and an oxidant gas to the first electrode; the second fluid flow path is used to supply hydrogen to the second electrode, and the water electrolysis power generation system can switch between a water electrolysis mode and a power generation mode, wherein the water electrolysis mode refers to a mode in which the water supplied to the first electrode is electrolyzed to generate hydrogen at the second electrode; the power generation mode refers to a mode in which power is generated by an electrochemical reaction between the oxidant gas supplied to the first electrode and the hydrogen supplied to the second electrode, and the water electrolysis power generation system has A water inlet flow path, an outlet flow path and a gas-liquid separator, wherein the water inlet flow path is used to supply the water to the inlet port portion connected to the first fluid flow path; the outlet flow path is connected to the outlet port portion connected to the first fluid flow path, and in the water electrolysis mode, the gas-containing water containing the generated hydrogen is discharged to the outlet flow path; the gas-liquid separator is formed to store the water and is connected to the water inlet flow path, and performs gas-liquid separation on the gas-containing water guided from the outlet flow path. The operation method of the water electrolysis power generation system includes a power generation stop process and a water electrolysis start process when switching from the power generation mode to the water electrolysis mode. The power generation stop process refers to the process of stopping the power generation of the battery component, and the water electrolysis start process refers to the process of starting water electrolysis by the battery component when the water level in the gas-liquid separator is above the lower limit level.

[0007] According to one aspect of the present invention, a purification process allows the use of oxidant gas to discharge water (retained water) present in the supply flow path and the first fluid flow path of the battery component during water electrolysis mode to a gas-liquid separator. This allows for a smooth and reliable switch from water electrolysis mode to power generation mode. Furthermore, by utilizing a portion of the supply flow path for both water supply and purification, the water electrolysis power generation system can be miniaturized and manufactured at a low cost.

[0008] According to another aspect of the present invention, water electrolysis is initiated when the water level in the gas-liquid separator is above a lower limit. This prevents air from entering the water supplied to the first fluid flow path of the battery unit during the water electrolysis initiation process. This allows for smooth and reliable switching from power generation mode to water electrolysis mode.

[0009] The above-mentioned objects, features and advantages will be easily understood from the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram showing a water electrolysis power generation system and a hydrogen station according to one embodiment of the present invention.

[0011] Figure 2 yes Figure 1 A schematic diagram illustrating the schematic structure of a water electrolysis power generation system.

[0012] Figure 3 yes Figure 2 A partially omitted cross-sectional illustration of a battery component.

[0013] Figure 4 yes Figure 2 Block diagram of the system ECU.

[0014] Figure 5 This is a flow chart illustrating the water electrolysis mode of the water electrolysis power generation system.

[0015] Figure 6 This is a diagram explaining the operation of the water electrolysis mode.

[0016] Figure 7 It is an explanatory diagram of dehumidification switching between the first dehumidification adsorption unit and the second dehumidification adsorption unit.

[0017] Figure 8 This is a flow chart illustrating the power generation mode of the water electrolysis power generation system.

[0018] Figure 9 This is a diagram explaining the operation of the power generation mode.

[0019] Figure 10 This is a flowchart illustrating the switching from the water electrolysis mode to the power generation mode.

[0020] Figure 11 It is an explanation Figure 10 Flowchart of the purge process.

[0021] Figure 12 This is an operation diagram for explaining the purification process.

[0022] Figure 13 It is an explanation Figure 10 Flowchart of the power generation preparation process.

[0023] Figure 14A This is a flowchart illustrating the switching from the power generation mode to the water electrolysis mode. Figure 14B It is an explanation Figure 14A Flowchart of the power generation shutdown process.

[0024] Figure 15 It is an explanation Figure 14A Flowchart of the water electrolysis preparation process. DETAILED DESCRIPTION

[0025] The water electrolysis power generation system 10 according to one embodiment of the present invention is a system that uses electricity (surplus electricity) from renewable energy sources to produce hydrogen and uses hydrogen to generate electricity when electricity is needed. Figure 1 As shown, for example, the water electrolysis power generation system 10 is connected to a hydrogen station 400 via a low-pressure hydrogen pipeline 402 .

[0026] Hydrogen station 400 includes a water electrolysis system 404, a hydrogen boosting system 406, and a hydrogen tank 408. The water electrolysis system 404 produces hydrogen by electrolyzing water using electricity from renewable energy sources. The hydrogen boosting system 406 boosts the pressure of the hydrogen produced by the water electrolysis system 404 and stores it in the hydrogen tank 408. Hydrogen tank 408 can also store hydrogen (including by-product hydrogen) produced and delivered by other plants.

[0027] The low-pressure hydrogen line 402 supplies hydrogen stored in the hydrogen tank 408 of the hydrogen station 400 or hydrogen produced by the water electrolysis system 404 to the water electrolysis power generation system 10. Furthermore, the low-pressure hydrogen line 402 supplies hydrogen produced by the water electrolysis power generation system 10 (hydrogen without pressure accumulation) to the hydrogen boosting system 406 in order to store it in the hydrogen tank 408. The low-pressure hydrogen line 402 also functions as a tank for storing hydrogen. Specifically, in this embodiment, the hydrogen tank 408 and the low-pressure hydrogen line 402 function as a hydrogen storage unit 410.

[0028] exist Figure 2 In FIG, the water electrolysis power generation system 10 includes a battery unit 12 , a first device 14 , a second device 16 , and a cooling device 18 .

[0029] like Figure 3 As shown, the battery unit 12 includes a battery stack in which a plurality of batteries 20 are stacked. Each battery 20 includes an MEA 22 (electrolyte membrane-electrode assembly) and a first separator 24 and a second separator 26 that sandwich the MEA 22. The MEA 22 includes an electrolyte membrane 28, a first electrode 30, and a second electrode 32. The first electrode 30 is disposed on one surface 28a of the electrolyte membrane 28. The second electrode 32 is disposed on the other surface 28b of the electrolyte membrane 28. The electrolyte membrane 28 is, for example, a solid polymer electrolyte membrane (cation exchange membrane). The solid polymer electrolyte membrane is, for example, a thin film of perfluorosulfonic acid containing water.

[0030] The first electrode 30 includes a first electrode catalyst layer 34 and a first gas diffusion layer 36. The first electrode catalyst layer 34 is bonded to one surface 28a of the electrolyte membrane 28. The first gas diffusion layer 36 is laminated on the first electrode catalyst layer 34. The second electrode 32 includes a second electrode catalyst layer 38 and a second gas diffusion layer 40. The second electrode catalyst layer 38 is bonded to the other surface 28b of the electrolyte membrane 28. The second gas diffusion layer 40 is laminated on the second electrode catalyst layer 38.

[0031] The first electrode catalyst layer 34 comprises, for example, porous carbon particles with a platinum alloy supported on their surfaces. These porous carbon particles, along with an ion-conductive polymer binder, are uniformly applied to the surface of the first gas diffusion layer 36. The second electrode catalyst layer 38 comprises, for example, porous carbon particles with a platinum alloy supported on their surfaces. These porous carbon particles, along with an ion-conductive polymer binder, are uniformly applied to the surface of the second gas diffusion layer 40. The first gas diffusion layer 36 and the second gas diffusion layer 40 are made of carbon paper, carbon cloth, or the like.

[0032] The first and second separators 24 and 26 are formed by press-forming a cross-section of a thin metal plate into a corrugated shape. The thin metal plate may be, for example, a steel plate, a stainless steel plate, an aluminum plate, or a plated steel plate. Alternatively, the thin metal plate may be a stainless steel plate or an aluminum plate with a surface treatment for corrosion protection. The first and second separators 24 and 26 are joined together by a plurality of bonding lines (not shown) to form a joined separator 42.

[0033] The surface 24a of the first separator 24 facing the MEA 22 has a first fluid flow path 44. The surface 26a of the second separator 26 facing the MEA 22 has a second fluid flow path 46. A coolant flow path 48, through which a cooling medium flows, is located between the surfaces 24b of the first separator 24 and 26b of the second separator 26, which are joined to each other. The coolant flow path 48 is formed by overlapping the back surface of the first separator 24, on which the first fluid flow path 44 is formed, and the back surface of the second separator 26, on which the second fluid flow path 46 is formed.

[0034] exist Figure 2In the embodiment, an electrolysis power supply 50 serving as a DC power supply is electrically connected to the battery component 12. The water electrolysis power generation system 10 having such a battery component 12 can switch between a water electrolysis mode and a power generation mode (fuel cell mode). In the water electrolysis mode, the water electrolysis power generation system 10 electrolyzes the water supplied to the first electrode 30 so that the second electrode 32 generates hydrogen. In the power generation mode, the water electrolysis power generation system 10 generates electricity through an electrochemical reaction between the oxidant gas supplied to the first electrode 30 and the hydrogen supplied to the second electrode 32. The electricity generated by the battery component 12 is used to charge, for example, a battery not shown in the figure, but detailed illustration is omitted. In addition, the electricity generated by the battery component 12 can also be supplied to the system power grid after being converted to AC.

[0035] An impedance measurement unit 52 and a battery voltage measurement unit 54 are mounted on the battery unit 12. The impedance measurement unit 52 energizes the first electrode 30 and the second electrode 32 via an AC power source (not shown) and measures the DC resistance component of the battery unit 12 based on the battery voltage. The battery voltage measurement unit 54 measures the battery voltage of each battery 20 during power generation.

[0036] The battery unit 12 is provided with a first inlet port 56a, a first outlet port 56b, a second inlet port 58a, a second outlet port 58b, a refrigerant inlet port 60a, and a refrigerant outlet port 60b. The first inlet port 56a and the first outlet port 56b are connected to the first fluid flow path 44 of the battery unit 12 (see FIG. Figure 3 ) are connected. The first inlet port 56a and the first outlet port 56b are connected to the first device 14. In the water electrolysis mode, water is supplied from the first device 14 to the first inlet port 56a. In the power generation mode, oxidant gas is supplied from the first device 14 to the first inlet port 56a. In the water electrolysis mode, gas-containing water (gas-containing water) containing generated hydrogen and by-product oxygen is discharged from the first fluid flow path 44 to the first outlet port 56b. In the power generation mode, oxidant exhaust gas containing generated water is discharged from the first fluid flow path 44 to the first outlet port 56b.

[0037] The second inlet port 58a and the second outlet port 58b are connected to the second fluid flow path 46 of the battery unit 12 (see Figure 3 ). The second inlet port 58a and the second outlet port 58b are connected to the second device 16. In the water electrolysis mode, nothing is supplied from the second device 16 to the second inlet port 58a. In the power generation mode, hydrogen is supplied from the second device 16 to the second inlet port 58a. In the water electrolysis mode, generated hydrogen containing water is discharged from the second fluid flow path 46 to the second outlet port 58b. In the power generation mode, hydrogen exhaust gas containing water is discharged from the second fluid flow path 46 to the second outlet port 58b.

[0038] The coolant inlet port 60a and the coolant outlet port 60b are connected to the coolant flow path 48 of the battery unit 12 (see Figure 3 The refrigerant inlet port 60a and the refrigerant outlet port 60b are connected to the cooling device 18.

[0039] The first device 14 includes a pure water supply unit 62, a water circulation unit 64, an oxidant gas device 66, and a heat exchanger 68. The pure water supply unit 62 includes a water supply flow path 70 for supplying water (pure water) to the water circulation unit 64. A tap water supply valve 72, a pure water production unit 74, a pure water regulating valve 76, and a check valve 78 are installed in this order from the upstream side toward the water circulation unit 64.

[0040] The tap water supply valve 72 is an on-off valve that opens and closes the water supply flow path 70. The tap water supply valve 72 adjusts the amount of tap water supplied to the pure water production section 74. The pure water production section 74 produces pure water by, for example, circulating tap water through an activated carbon filter, an ion exchange resin (ion exchange resin tower) and a hollow fiber filter, but is not shown in the figure. The pure water regulating valve 76 is an on-off valve that opens and closes the water supply flow path 70. The pure water regulating valve 76 adjusts the amount of pure water produced by the pure water production section 74 supplied to the water circulation section 64. The check valve 78 allows pure water to flow from the pure water production section 74 to the water circulation section 64, and prevents the fluid from flowing from the water circulation section 64 to the pure water production section 74.

[0041] The water circulation unit 64 includes a first gas-liquid separator 80, a water inlet flow path 81, a first supply flow path 82, and a first outlet flow path 84. The water inlet flow path 81 is connected to the first gas-liquid separator 80. The first supply flow path 82 connects the water inlet flow path 81 and the first inlet port 56a. The first outlet flow path 84 connects the first outlet port 56b and the first gas-liquid separator 80.

[0042] The first gas-liquid separator 80 performs gas-liquid separation on the fluid discharged from the cell unit 12. Specifically, the first gas-liquid separator 80 performs gas-liquid separation on the gas-containing water discharged from the first outlet port 56b of the cell unit 12 during the water electrolysis mode. Furthermore, the first gas-liquid separator 80 performs gas-liquid separation on the oxidant off-gas discharged from the first outlet port 56b of the cell unit 12 during the power generation mode. Furthermore, the first gas-liquid separator 80 performs gas-liquid separation on the hydrogen off-gas discharged from the second outlet port 58b via the second device 16 during the power generation mode.

[0043] The first gas-liquid separator 80 includes a first storage section 86 capable of storing water. Pure water is supplied to the first storage section 86 from the pure water supply section 62. Furthermore, the first storage section 86 stores water separated from the fluid discharged from the battery unit 12. Therefore, the first storage section 86 stores a mixture of pure water discharged from the pure water supply section 62 and water separated from the fluid discharged from the battery unit 12.

[0044] The first storage section 86 includes a partition wall 88 that divides the space above the water surface within the first storage section 86 into a first chamber 86a and a second chamber 86b. The partition wall 88 is separated from the bottom surface of the first storage section 86. A portion of the partition wall 88 is submerged in the water within the first storage section 86. Water is introduced from the water supply passage 70 into the first chamber 86a of the first storage section 86. Fluid discharged from the battery unit 12 is introduced into the second chamber 86b of the first storage section 86.

[0045] In the first gas-liquid separator 80, the gas component of the fluid directed to the second chamber 86b passes through the water (between the partition wall 88 and the bottom surface of the first storage unit 86) and is directed to the first chamber 86a. The gas component directed to the first chamber 86a is discharged to the outside through an exhaust flow path 90 connected to the upper portion of the first chamber 86a of the first storage unit 86. A hydrogen sensor 91 for detecting the hydrogen concentration in the gas component is installed in the exhaust flow path 90. The exhaust flow path 90 includes a diffusion pipe (not shown) that diffuses the gas component (hydrogen) at a position at least 5 meters above the ground.

[0046] The water level within the first reservoir 86 is managed so that a portion of the partition wall 88 remains submerged in water. Therefore, the first reservoir 86 also functions as a water seal to prevent flashback. Specifically, the first reservoir 86 prevents flames from propagating from the exhaust passage 90 to the second chamber 86b if, for example, the exhaust passage 90 is struck by lightning. Furthermore, the first reservoir 86 prevents flames from propagating from the first outlet port 56b to the exhaust passage 90 if, for example, the first outlet port 56b of the battery unit 12 catches fire.

[0047] The partition wall 88 also functions as a wave-breaking plate, preventing ripples on the water surface of the second chamber 86b from propagating to the water surface of the first chamber 86a during gas-liquid separation. This stabilizes the water level in the first chamber 86a. A first water level sensor LS1 (first water level acquisition unit) is installed in the first chamber 86a of the first storage section 86 to detect the amount of water in the first storage section 86.

[0048] One end of the water introduction flow path 81 is connected to the first storage unit 86. On the water introduction flow path 81, a filter 92, a water pump 94, a first heat exchanger 96, a pure water treatment unit 98 and a pure water supply valve 100 are installed in order from the first gas-liquid separator 80 to the first supply flow path 82.

[0049] Filter 92 removes foreign matter (floating particles) from the water discharged from the first storage section 86. Water pump 94 is an electric water pump for water electrolysis. Water pump 94 circulates the water in the first storage section 86 through the water inlet flow path 81, the first supply flow path 82, the battery unit 12 (first fluid flow path 44), and the first outlet flow path 84, returning the water to the first storage section 86. First heat exchanger 96 adjusts the water delivered from water pump 94 to a desired temperature. For example, first heat exchanger 96 is a water-cooled intercooler.

[0050] The pure water treatment unit 98 performs pure water treatment on the water guided from the first heat exchanger 96. Accordingly, the water separated from the fluid derived from the battery unit 12 by the first gas-liquid separator 80 can be reused. Therefore, the amount of tap water used per unit amount of hydrogen generated in the water electrolysis mode can be reduced. In addition, the replacement cycle of the parts (activated carbon filter, ion exchange resin, hollow fiber filter, etc.) of the pure water manufacturing unit 74 for making tap water pure water can be extended. Therefore, the operating cost and maintenance cost of the water electrolysis power generation system 10 can be reduced. Moreover, the water supplied to the battery unit 12 can always be pure water. Therefore, the liquid junction resistance and ground fault resistance required for water electrolysis can be reliably managed.

[0051] The pure water treatment unit 98 includes, for example, multiple ion exchangers 102 and mesh filters 104. The multiple ion exchangers 102 are arranged in parallel. This reduces the pressure loss when water flows through the ion exchangers 102, compared to a case where the multiple ion exchangers 102 are arranged in series. The ion exchangers 102 preferably have replaceable cartridges, for example. The mesh filters 104 remove foreign matter from the water after it passes through the ion exchangers 102. The pure water supply valve 100 is an on-off valve that opens and closes the first fluid flow path 44.

[0052] The first supply flow path 82 introduces water (pure water) guided from the water introduction flow path 81 into the first inlet port 56 a . The first outlet flow path 84 is connected to a wall portion of the second chamber 86 b of the first storage portion 86 .

[0053] The oxidant gas device 66 includes an oxidant gas flow path 106, an oxidant gas inlet flow path 108, a dilution flow path 110, and an oxidant gas outlet flow path 112. An air filter 114, an air pump 116, an air flow meter 118 (oxidant gas flow rate acquisition unit), an intercooler 120, a second heat exchanger 122, and a humidifier 124 are installed in the oxidant gas flow path 106 in this order from upstream to downstream.

[0054] Air filter 114 removes foreign matter from the air (oxidant gas). Air pump 116 pressurizes (compresses) the oxidant gas purified by air filter 114. For example, a positive displacement electric motor turbo pump is used for air pump 116. Only one air pump 116 is attached to oxidant gas flow path 106.

[0055] An air flow meter 118 measures the flow rate of the oxidant gas directed from the air pump 116. An intercooler 120 cools the oxidant gas, which has been pressurized and heated by the air pump 116. Intercooler 120 is, for example, an air-cooled intercooler. Specifically, intercooler 120 adjusts the temperature of the oxidant gas by controlling the rotational speed of a fan (not shown).

[0056] The second heat exchanger 122 adjusts the oxidizing gas cooled by the intercooler 120 to a desired temperature. The second heat exchanger 122 is, for example, a water-cooled intercooler. The humidifier 124 humidifies the oxidizing gas guided from the second heat exchanger 122 .

[0057] A first bypass flow path 126 is provided in the oxidizing gas flow path 106, bypassing the humidifier 124. One end (the upstream end) of the first bypass flow path 126 is connected to a position between the humidifier 124 and the second heat exchanger 122 on the oxidizing gas flow path 106 via a flow control valve 128. The other end (the downstream end) of the first bypass flow path 126 is connected to a position on the oxidizing gas flow path 106 downstream of the humidifier 124.

[0058] The flow rate regulating valve 128 regulates the ratio between the flow rate of the oxidizing gas guided to the humidifier 124 and the flow rate of the oxidizing gas guided to the first bypass flow path 126. For example, an electrically adjustable three-way valve is suitable for the flow rate regulating valve 128.

[0059] The downstream end of the oxidizing gas flow path 106 is connected to the oxidizing gas introduction flow path 108 and the dilution flow path 110 via a first flow path switching valve 130. The first flow path switching valve 130 can switch between a flow state in the oxidizing gas introduction flow path 108 and a flow state in the dilution flow path 110.

[0060] When the oxidant gas is flowing through the oxidant gas introduction flow path 108, the first flow path switching valve 130 allows the oxidant gas to flow from the oxidant gas flow path 106 to the oxidant gas introduction flow path 108, and blocks the oxidant gas from flowing from the oxidant gas flow path 106 to the dilution flow path 110. When the oxidant gas is flowing through the dilution flow path 110, the first flow path switching valve 130 allows the oxidant gas to flow from the oxidant gas flow path 106 to the dilution flow path 110, and blocks the oxidant gas from flowing from the oxidant gas flow path 106 to the oxidant gas introduction flow path 108. For example, a three-way valve can be used as the first flow path switching valve 130.

[0061] The oxidant gas inlet flow path 108 guides the oxidant gas, which has flowed through the oxidant gas flow path 106, to the first supply flow path 82. The first supply flow path 82 guides the oxidant gas guided from the oxidant gas inlet flow path 108 into the first inlet port 56a. Specifically, in the water electrolysis mode, the first supply flow path 82 guides the water guided from the water inlet flow path 81 into the first inlet port 56a. Furthermore, in the power generation mode, the first supply flow path 82 guides the oxidant gas guided from the oxidant gas inlet flow path 108 into the first inlet port 56a. In other words, the water electrolysis power generation system 10 uses the same first supply flow path 82 in both the water electrolysis mode and the power generation mode.

[0062] A check valve 132 is installed in the oxidant gas introduction flow path 108 . The check valve 132 allows the oxidant gas to flow from the first flow path switching valve 130 to the first supply flow path 82 , and blocks the fluid (water) from flowing from the first supply flow path 82 to the first flow path switching valve 130 .

[0063] The dilution flow path 110 guides the oxidant gas (dilution gas) that has flowed through the oxidant gas flow path 106 to the second chamber 86b of the first reservoir 86. A check valve 134 is installed in the dilution flow path 110. The check valve 134 allows the oxidant gas to flow from the first flow path switching valve 130 to the first reservoir 86, while preventing the flow of fluid from the first reservoir 86 to the first flow path switching valve 130.

[0064] The oxidant gas outlet flow path 112 guides the oxidant off-gas, which is outlet from the first outlet port 56 b of the battery unit 12 to the first outlet flow path 84 , to the second chamber 86 b of the first storage unit 86 during the power generation mode.

[0065] The oxidizing gas outlet flow path 112 is connected to the first outlet flow path 84 via the second flow path switching valve 136. Specifically, the first outlet flow path 84 includes an upstream outlet flow path 84a located upstream of the second flow path switching valve 136 and a downstream outlet flow path 84b located downstream of the second flow path switching valve 136. The second flow path switching valve 136 can switch between a flow state in the oxidizing gas outlet flow path 112 and a flow state in the downstream outlet flow path 84b.

[0066] When the oxidant gas outlet flow path 112 is flowing, the second flow path switching valve 136 allows the fluid (oxidant exhaust gas) to flow from the upstream outlet flow path 84a to the oxidant gas outlet flow path 112, and blocks the fluid (oxidant exhaust gas) from flowing from the upstream outlet flow path 84a to the downstream outlet flow path 84b. When the downstream outlet flow path 84b is flowing, the second flow path switching valve 136 allows the fluid (aerated water) to flow from the upstream outlet flow path 84a to the downstream outlet flow path 84b, and blocks the fluid (aerated water) from flowing from the upstream outlet flow path 84a to the oxidant gas outlet flow path 112. A three-way valve can be used as the second flow path switching valve 136, for example.

[0067] A humidifier 124, a first back-pressure valve 138, and a check valve 140 are installed in the oxidant gas outlet flow path 112, sequentially extending from the first outlet flow path 84 toward the first reservoir 86. Specifically, the humidifier 124 is installed across the oxidant gas inlet flow path 108 and the oxidant gas outlet flow path 112. The humidifier 124 humidifies the oxidant gas flowing through the oxidant gas flow path 106 using the oxidant off-gas (containing generated water) flowing through the oxidant gas outlet flow path 112. The first back-pressure valve 138 regulates the flow rate of the oxidant off-gas flowing through the oxidant gas outlet flow path 112. A diaphragm valve, for example, can be used for the first back-pressure valve 138. The check valve 140 allows the oxidant off-gas to flow from the first back-pressure valve 138 to the first reservoir 86, while preventing the flow of fluid from the first reservoir 86 to the first back-pressure valve 138.

[0068] Heat exchanger 68 includes a heat medium circulation flow path 142 for circulating a heat medium. In heat exchanger 68, antifreeze is preferably used as the heat medium. Considering specific heat and viscosity, an antifreeze solution such as a 50% dilution of ethylene glycol (coolant) can be used. However, any suitable fluid may be used as the heat medium.

[0069] A heat medium pump 144, a heat medium radiator 146, the first heat exchanger 96, and the second heat exchanger 122 are installed in the heat medium circulation flow path 142. The heat medium pump 144 circulates the heat medium in the heat medium circulation flow path 142. The heat medium radiator 146 is located downstream of the heat medium pump 144 in the heat medium circulation flow path 142. The heat medium radiator 146 exchanges heat between the heat medium and the atmosphere. The heat medium radiator 146 adjusts the temperature of the heat medium by adjusting the rotation speed of a fan (not shown).

[0070] The first heat exchanger 96 is located downstream of the heat medium radiator 146 in the heat medium circulation flow path 142. The first heat exchanger 96 performs heat exchange between the water flowing through the water inlet flow path 81 and the heat medium. The second heat exchanger 122 is located between the heat medium radiator 146 and the first heat exchanger 96 in the heat medium circulation flow path 142. In other words, the second heat exchanger 122 is located upstream of the first heat exchanger 96 in the heat medium circulation flow path 142. The second heat exchanger 122 performs heat exchange between the oxidant gas flowing through the oxidant gas flow path 106 and the heat medium.

[0071] The heat exchange device 68 further includes a heat medium tank and a pressure regulating valve for regulating the flow rate of the heat medium in the heat medium circulation flow path 142 , but these are not shown in the drawings.

[0072] The second device 16 includes a supply and discharge flow path 150, a second supply flow path 154, and a hydrogen gas outlet 156. The supply and discharge flow path 150 communicates with the low-pressure hydrogen gas line 402. The second supply flow path 154 guides the hydrogen gas guided from the low-pressure hydrogen gas line 402 to the supply and discharge flow path 150 toward the second inlet port 58a of the cell unit 12.

[0073] The second supply flow path 154 is provided with a hydrogen supply valve 158, a check valve 160, and an ejector 162, in this order, extending from the supply and discharge flow path 150 toward the second inlet port 58a. The hydrogen supply valve 158 is a shutoff valve that opens and closes the second supply flow path 154. The check valve 160 allows hydrogen to flow from the supply and discharge flow path 150 to the second inlet port 58a, while preventing fluid from flowing from the second inlet port 58a to the supply and discharge flow path 150. A hydrogen off-gas circulation flow path 176 is connected to the ejector 162. During power generation mode, the hydrogen off-gas circulation flow path 176 returns hydrogen off-gas discharged from the second outlet port 58b of the cell unit 12 to the second supply flow path 154. The ejector 162 draws hydrogen off-gas from the hydrogen off-gas circulation flow path 176 using hydrogen gas introduced from the supply and discharge flow path 150, mixes this hydrogen off-gas with hydrogen gas, and discharges it downstream.

[0074] A second bypass flow path 166 is provided on the second supply flow path 154 so as to bypass the ejector 162. One end (the upstream end) of the second bypass flow path 166 is connected between the check valve 160 and the ejector 162 on the second supply flow path 154. The other end of the second bypass flow path 166 is connected to a position on the second supply flow path 154 downstream of the ejector 162.

[0075] An injector 168 is attached to the second bypass flow path 166 . That is, the ejector 162 and the injector 168 are arranged in parallel with each other. The injector 168 is an electromagnetic valve that can adjust the flow rate of the hydrogen gas flowing through the second bypass flow path 166 .

[0076] The hydrogen outlet 156 includes a second outlet flow path 170, a second gas-liquid separator 172, an intermediate outlet flow path 174, a hydrogen off-gas circulation flow path 176, a dehumidification flow path 178, and a storage flow path 180. The second outlet flow path 170 connects the second outlet port 58b and the second gas-liquid separator 172. In the water electrolysis mode, generated hydrogen is discharged from the second outlet port 58b to the second outlet flow path 170. In the power generation mode, hydrogen off-gas is discharged to the second outlet flow path 170.

[0077] Connected to the second outlet flow path 170 is a purge flow path 182, which directs hydrogen off-gas to the second chamber 86b of the first reservoir 86 during power generation mode. A purge valve 184 and a check valve 186 are installed in sequence on the purge flow path 182, extending from the second outlet flow path 170 toward the first reservoir 86. The purge valve 184 is an on-off valve that opens and closes the purge flow path 182. The check valve 186 allows hydrogen off-gas to flow from the second outlet flow path 170 to the first reservoir 86, while preventing fluid from flowing from the first reservoir 86 to the second outlet flow path 170.

[0078] The second gas-liquid separator 172 performs gas-liquid separation on the generated hydrogen gas and hydrogen waste gas introduced from the second outlet flow path 170. The second gas-liquid separator 172 includes a second storage section 188 for storing water separated from the generated hydrogen gas and hydrogen waste gas. A vortex guide (not shown) is installed within the second storage section 188 to induce a vortex-like flow in the generated hydrogen gas and hydrogen waste gas introduced into the second storage section 188. This allows for efficient gas-liquid separation of the generated hydrogen gas and hydrogen waste gas introduced into the second storage section 188.

[0079] A second water level sensor LS2 (second water level acquisition unit) is attached to the second storage section 188 for acquiring the amount of water within the second storage section 188. A drain passage 190 is connected to the bottom surface of the second storage section 188 for draining the water within the second storage section 188. The drain passage 190 is connected between the purge valve 184 and the check valve 186 on the purge passage 182. A drain valve 192 is attached to the drain passage 190 for opening and closing the drain passage 190.

[0080] The intermediate outlet flow path 174 is connected to the upper portion of the second storage section 188. The hydrogen gas and hydrogen off-gas, after the water has been separated in the second storage section 188, are then discharged to the intermediate outlet flow path 174. The hydrogen off-gas circulation flow path 176 and the dehumidification flow path 178 are connected to the intermediate outlet flow path 174 via a third flow path switching valve 194. The third flow path switching valve 194 switches between a flow state in the hydrogen off-gas circulation flow path 176 and a flow state in the dehumidification flow path 178.

[0081] When hydrogen off-gas is flowing through the hydrogen off-gas circulation flow path 176, the third flow path switching valve 194 allows hydrogen off-gas to flow from the intermediate outlet flow path 174 to the hydrogen off-gas circulation flow path 176, and blocks hydrogen off-gas from flowing from the intermediate outlet flow path 174 to the dehumidification flow path 178. When hydrogen off-gas is flowing through the dehumidification flow path 178, the third flow path switching valve 194 allows generated hydrogen to flow from the intermediate outlet flow path 174 to the dehumidification flow path 178, and blocks generated hydrogen from flowing from the intermediate outlet flow path 174 to the hydrogen off-gas circulation flow path 176. A three-way valve can be used as the third flow path switching valve 194, for example.

[0082] The hydrogen off-gas circulation flow path 176 connects the third flow path switching valve 194 and the injector 162. A check valve 196 is installed in the hydrogen off-gas circulation flow path 176. The check valve 196 allows the hydrogen off-gas to flow from the third flow path switching valve 194 to the injector 162, while preventing the hydrogen gas from flowing from the injector 162 to the third flow path switching valve 194.

[0083] The dehumidification flow path 178 connects the third flow path switching valve 194 and the storage flow path 180. The dehumidification cooling unit 198, the first dehumidification adsorption unit 200a, the second dehumidification adsorption unit 200b, and the dehumidification switching unit 202 are installed in the dehumidification flow path 178.

[0084] The dehumidification and cooling unit 198 dehumidifies the generated hydrogen gas by cooling it. The first dehumidification and adsorption unit 200a is installed on the dehumidification flow path 178, downstream of the dehumidification and cooling unit 198. The second dehumidification and adsorption unit 200b is installed on the dehumidification flow path 178, downstream of the first dehumidification and adsorption unit 200a. The first and second dehumidification and adsorption units 200a and 200b are dehumidification and adsorption towers containing adsorbents such as zeolite. The first and second dehumidification and adsorption units 200a and 200b are equipped with heaters (not shown) for restoring the adsorption function of the adsorbents. In other words, the first and second dehumidification and adsorption units 200a and 200b dehumidify the generated hydrogen gas and can restore the dehumidification function.

[0085] The dehumidification switching unit 202 changes the flow direction of the generated hydrogen gas, thereby changing the order in which the generated hydrogen gas flows through the first dehumidification adsorption unit 200a and the second dehumidification adsorption unit 200b. The dehumidification switching unit 202 includes a fourth flow path switching valve 204, a first switching flow path 206, a first on-off valve 208, a second switching flow path 210, and a second on-off valve 212.

[0086] Fourth flow path switching valve 204 is installed between dehumidification cooling unit 198 and first dehumidification adsorption unit 200a on dehumidification flow path 178. Dehumidification flow path 178 includes dehumidification upstream flow path 178a upstream of fourth flow path switching valve 204 and dehumidification downstream flow path 178b downstream of fourth flow path switching valve 204. First switching flow path 206 is connected to fourth flow path switching valve 204.

[0087] The fourth flow path switching valve 204 can switch between a flow state in the dehumidification downstream flow path 178b and a flow state in the first switching flow path 206. When the dehumidification downstream flow path 178b is flowing, the fourth flow path switching valve 204 allows the generated hydrogen gas to flow from the dehumidification upstream flow path 178a to the dehumidification downstream flow path 178b, and blocks the generated hydrogen gas from the dehumidification upstream flow path 178a to the first switching flow path 206. When the first switching flow path 206 is flowing, the fourth flow path switching valve 204 allows the generated hydrogen gas to flow from the dehumidification upstream flow path 178a to the first switching flow path 206, and blocks the generated hydrogen gas from the dehumidification upstream flow path 178a to the dehumidification downstream flow path 178b. For example, a three-way valve can be used as the fourth flow path switching valve 204.

[0088] The first switching flow path 206 is connected to the dehumidification downstream flow path 178b at a position downstream of the second dehumidification adsorption unit 200b. The first on-off valve 208 is installed on the dehumidification downstream flow path 178b at a position downstream of the connection between the dehumidification downstream flow path 178b and the first switching flow path 206. The first on-off valve 208 opens and closes the dehumidification downstream flow path 178b. One end of the second switching flow path 210 is connected to the dehumidification downstream flow path 178b at a position upstream of the first dehumidification adsorption unit 200a. The other end of the second switching flow path 210 is connected to the dehumidification downstream flow path 178b at a position downstream of the first on-off valve 208. The second on-off valve 212 opens and closes the second switching flow path 210.

[0089] Storage flow path 180 guides the dehumidified generated hydrogen gas from dehumidification flow path 178 to supply / discharge flow path 150. A mesh filter 214 and a second back-pressure valve 216 are installed in this order on storage flow path 180, extending from dehumidification flow path 178 toward supply / discharge flow path 150. Mesh filter 214 removes foreign matter from the generated hydrogen gas. Second back-pressure valve 216 regulates the flow rate of the generated hydrogen gas flowing through storage flow path 180. A diaphragm valve, for example, can be used for second back-pressure valve 216.

[0090] A discharge flow path 218 is connected to the storage flow path 180 upstream of the mesh filter 214 and the second back pressure valve 216. The discharge flow path 218 discharges the generated hydrogen gas guided from the dehumidification flow path 178 to the exhaust flow path 90. A discharge valve 220 and a check valve 222 are installed in the discharge flow path 218 in this order, extending from the storage flow path 180 toward the exhaust flow path 90. The discharge valve 220 opens and closes the discharge flow path 218. The check valve 222 allows the generated hydrogen gas to flow from the storage flow path 180 to the exhaust flow path 90, while preventing the flow of fluid from the exhaust flow path 90 to the storage flow path 180.

[0091] The cooling device 18 allows the coolant to flow through the coolant flow path 48 (see Figure 3 ) to cool the battery components 12. For example, an ethylene glycol aqueous solution can be used as the refrigerant.

[0092] The cooling device 18 includes a refrigerant supply passage 224, a refrigerant outlet passage 226, and a refrigerant radiator 228. The refrigerant supply passage 224 connects the refrigerant radiator 228 to the refrigerant inlet port 60a. A refrigerant pump 230 is provided on the refrigerant supply passage 224. The refrigerant pump 230 discharges the refrigerant from the refrigerant supply passage 224 to the refrigerant inlet port 60a. The refrigerant outlet passage 226 connects the refrigerant outlet port 60b to the refrigerant radiator 228.

[0093] A third back-pressure valve 232 is provided on the refrigerant outlet flow path 226. This valve regulates the flow rate of the refrigerant flowing through the refrigerant outlet flow path 226. A diaphragm valve, for example, can be used for the third back-pressure valve 232. The refrigerant radiator 228 exchanges heat between the refrigerant and the atmosphere. The refrigerant radiator 228 adjusts the refrigerant temperature by adjusting the speed of a fan (not shown).

[0094] The cooling device 18 further includes a refrigerant tank and a pressure regulating valve for regulating the flow rate of the refrigerant in the refrigerant supply flow path 224 , the refrigerant outlet flow path 226 , and the refrigerant flow path 48 , but these are not shown in the figure.

[0095] The water electrolysis power generation system 10 further includes a gas meter 234 (flow rate acquisition unit) and a system ECU 236. The gas meter 234 is mounted on the supply and discharge flow path 150. The gas meter 234 acquires the flow rate of generated hydrogen gas flowing from the supply and discharge flow path 150 to the low-pressure hydrogen gas pipeline 402 (the amount of hydrogen sold) and the flow rate of hydrogen gas flowing from the low-pressure hydrogen gas pipeline 402 to the supply and discharge flow path 150 (the amount of hydrogen purchased).

[0096] like Figure 4 As shown, the information acquired by gas meter 234 is transmitted to gateway server 238. Gateway server 238 transmits the transaction information (hydrogen sales and purchase amounts) with a timestamp to VPP server 240 (virtual power plant server). System ECU 236 can communicate with VPP server 240 via gateway server 238. VPP server 240 transmits requests for water electrolysis mode operation, power generation mode operation, mode switching, and operation stop to system ECU 236 via gateway server 238.

[0097] The system ECU 236 receives information from the first water level sensor LS1, the second water level sensor LS2, the impedance measurement unit 52, the battery voltage measurement unit 54, the hydrogen sensor 91, and the air flow meter 118. Furthermore, the system ECU 236 receives information from various sensors included in the battery unit 12, the first device 14, the second device 16, and the cooling device 18, such as pressure sensors, temperature sensors, resistivity meters, hydrogen sensors, and flow meters.

[0098] System ECU 236 includes a computing unit 242 (processing unit) and a storage unit 246. The computing unit 242 can be comprised of a processing circuit such as a CPU (Central Processing Unit). The computing unit 242 includes a valve control unit 248, a pump control unit 250, a syringe control unit 252, a determination unit 254, and a counter 256. Each component of the computing unit 242 (such as the valve control unit 248) can be implemented by the computing unit 242 executing a program stored in the storage unit 246.

[0099] At least some of the components of the computing unit 242 (such as the valve control unit 248) may be implemented using an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). Furthermore, at least some of the components of the computing unit 242 (such as the valve control unit 248) may include an electronic circuit that includes discrete components.

[0100] Storage unit 246 includes volatile memory and non-volatile memory. Examples of volatile memory include RAM (Random Access Memory). Examples of non-volatile memory include ROM (Read Only Memory) and flash memory. At least a portion of storage unit 246 may be incorporated into the aforementioned processor or integrated circuit.

[0101] The valve control unit 248 controls the operation of various valves. The pump control unit 250 controls the operation of various pumps (water pump 94, air pump 116, heat medium pump 144, and refrigerant pump 230). The syringe control unit 252 controls the opening and closing of the syringe 168. The counter 256 measures time.

[0102] Next, a method of operating the water electrolysis power generation system 10 will be described.

[0103] First, the operation of the water electrolysis mode of the water electrolysis power generation system 10 will be described. When the system ECU 236 receives a water electrolysis mode operation request from the VPP server 240 via the gateway server 238 , the water electrolysis power generation system 10 operates in the water electrolysis mode.

[0104] Specifically, if Figure 5 As shown in FIG. 1 , when the water electrolysis mode is in operation, pure water is produced from tap water (step S1). That is, the valve control unit 248 opens the tap water supply valve 72. Figure 6 As shown, tap water is introduced into the pure water production unit 74 via the water supply flow path 70. In the pure water production unit 74, the tap water flows through an activated carbon filter, an ion exchange resin, and a hollow fiber filter (not shown) to produce pure water. The pure water produced by the pure water production unit 74 is introduced into the first storage unit 86 via the pure water regulating valve 76. The pure water supplied to the first storage unit 86 is mixed with the water used for water electrolysis in the battery unit 12 within the first storage unit 86.

[0105] Furthermore, during the water electrolysis mode, the valve control unit 248 opens and closes the pure water regulating valve 76 based on the water level detected by the first water level sensor LS1 to maintain the water level in the first storage section 86 within a specified range. Specifically, when the water level detected by the first water level sensor LS1 drops to a lower limit, the valve control unit 248 opens the pure water regulating valve 76 to supply pure water from the pure water production section 74 to the first storage section 86. Subsequently, when the water level detected by the first water level sensor LS1 rises to a reference level, the valve control unit 248 closes the pure water regulating valve 76 to stop the supply of pure water from the pure water production section 74 to the first storage section 86. Furthermore, when the water level detected by the first water level sensor LS1 rises to an upper limit, the valve control unit 248 opens a discharge valve (not shown) attached to a discharge flow path connected to the bottom surface of the first storage section 86 to discharge the water in the first storage section 86 to the outside.

[0106] If the water level detected by the first water level sensor LS1 rises to the abnormal water level upper limit, the system ECU 236 performs a fault-stop process. If the water level detected by the first water level sensor LS1 drops to the abnormal water level lower limit, the system ECU 236 performs a fault-stop process. The lower limit, reference level, upper limit, abnormal upper limit, and abnormal lower limit levels of the water level in the first storage unit 86 are pre-stored in the storage unit 246.

[0107] Then, the valve control unit 248 controls various valves to the water electrolysis mode state ( Figure 5 Specifically, the valve control unit 248 opens the pure water supply valve 100, the first on-off valve 208, and the second back-pressure valve 216. Furthermore, the valve control unit 248 closes the hydrogen supply valve 158, the purge valve 184, the discharge valve 192, the second on-off valve 212, and the drain valve 220. Furthermore, the first back-pressure valve 138 and the third back-pressure valve 232 may be opened or closed.

[0108] Furthermore, the valve control unit 248 controls the flow rate regulating valve 128 so that the oxidant gas flows through the first bypass flow path 126 and does not flow through the humidifier 124. Furthermore, the valve control unit 248 controls the first flow path switching valve 130 so that the oxidant gas flows through the dilution flow path 110. The valve control unit 248 controls the second flow path switching valve 136 so that the oxidant gas flows through the downstream lead-out flow path 84b. The valve control unit 248 controls the third flow path switching valve 194 so that the oxidant gas flows through the dehumidification flow path 178. The valve control unit 248 controls the fourth flow path switching valve 204 so that the oxidant gas flows through the dehumidification downstream flow path 178b.

[0109] Then, the pump control unit 250 controls the various pumps to the water electrolysis mode ( Figure 5In step S3, pump control unit 250 drives water pump 94, heat medium pump 144, and air pump 116. Pump control unit 250 does not drive refrigerant pump 230. However, in situations where the outside air is at a high temperature (e.g., 45°C or higher), pump control unit 250 may drive refrigerant pump 230 to cool battery unit 12.

[0110] The water stored in the first storage section 86 then passes through the water inlet passage 81, is filtered 92 to remove foreign matter, and is then pressurized by the water pump 94. The water pressurized by the water pump 94 exchanges heat with the heat medium in the first heat exchanger 96, thereby being adjusted to a desired temperature.

[0111] The water that has passed through the first heat exchanger 96 passes through the ion exchanger 102, is purified, and then passes through the mesh filter 104 to remove foreign matter. The water (pure water) that has passed through the mesh filter 104 is then supplied to the first inlet port 56a of the battery unit 12 via the first supply flow path 82 ( Figure 5 Furthermore, if the resistivity of water (pure water) measured at a position downstream of the mesh filter 104 in the water introduction flow path 81 is lower than a lower limit level, the system ECU 236 performs a fault stop process.

[0112] The pure water introduced into the first inlet port 56a flows through the first fluid flow path 44 of the battery unit 12 and is guided toward the first electrode 30. In the water electrolysis mode, the hydrogen supply valve 158 is closed, so hydrogen is not introduced into the second inlet port 58a of the battery unit 12.

[0113] The oxidant gas flowing into the oxidant gas flow path 106 is filtered by an air filter 114 to remove foreign matter and then pressurized by an air pump 116. The oxidant gas, heated by the pressurization, flows through an air flow meter 118, is cooled by an intercooler 120, and then adjusted to a desired temperature by a second heat exchanger 122.

[0114] After passing through the second heat exchanger 122, the oxidant gas is directed to the dilution flow path 110 via the first bypass flow path 126. Specifically, in the water electrolysis mode, the oxidant gas does not flow through the humidifier 124. Therefore, in the water electrolysis mode, the humidifier 124 can be prevented from being dried out by the oxidant gas. Consequently, when switching from the water electrolysis mode to the power generation mode, the humidification amount of the oxidant gas can be efficiently adjusted by the humidifier 124 immediately after power generation begins. The oxidant gas directed to the dilution flow path 110 is introduced into the second chamber 86b of the first storage unit 86.

[0115] After this, the system ECU 236 starts water electrolysis ( Figure 5In step S5, the system ECU 236 drives the electrolysis power source 50 to apply voltage to the battery unit 12. This electrolysis of pure water occurs at the first electrode 30 of each battery cell 20, generating hydrogen ions, electrons, and oxygen. At the second electrode 32 of each battery cell 20, hydrogen ions passing through the electrolyte membrane 28 from the first electrode 30 combine with electrons guided from the first electrode 30 to the second electrode 32, producing hydrogen gas. At this point, a portion of the hydrogen gas produced at the second electrode 32 passes through the electrolyte membrane 28 and is guided toward the first fluid flow path 44.

[0116] Therefore, aerated water containing oxygen generated by the reaction, unreacted water that was not electrolyzed, and generated hydrogen gas that permeated from the second electrode 32 through the electrolyte membrane 28 to the first electrode 30 is directed toward the first outlet port 56b. Furthermore, the generated hydrogen gas is directed toward the second outlet port 58b. Furthermore, the generated hydrogen gas is also directed toward the second inlet port 58a. However, because a check valve 160 is installed in the second supply flow path 154, the generated hydrogen gas directed toward the second inlet port 58a does not flow into the supply and discharge flow path 150. Furthermore, because a check valve 196 is installed in the hydrogen off-gas circulation flow path 176, the generated hydrogen gas directed toward the second inlet port 58a does not flow into the third flow path switching valve 194.

[0117] The aerated water directed to the first outlet port 56b of the battery unit 12 flows into the first gas-liquid separator 80 via the first outlet flow path 84. Specifically, the aerated water flows into the second chamber 86b of the first storage section 86. Furthermore, oxidant gas is introduced into the second chamber 86b of the first storage section 86 via the dilution flow path 110. Consequently, the oxidant gas in the second chamber 86b flows into the first chamber 86a through the water stored in the first storage section 86 (via the partition wall 88 and the bottom surface of the first storage section 86). At this time, the gas components contained in the aerated water are also directed into the first chamber 86a. Specifically, the gas components separated from the aerated water flow into the first chamber 86a, and the water (liquid water) separated from the aerated water is stored within the first storage section 86. The gas components that flowed into the first chamber 86a, diluted with the oxidant gas, are then discharged to the outside via the exhaust flow path 90.

[0118] The generated hydrogen gas guided to the second outlet port 58b of the battery unit 12 flows into the second gas-liquid separator 172 via the second outlet flow path 170. At this time, since the purge valve 184 is closed, the generated hydrogen gas flowing in the second outlet flow path 170 is not guided to the first gas-liquid separator 80 via the purge flow path 182.

[0119] The generated hydrogen gas guided to the second gas-liquid separator 172 flows in a vortex shape in the second storage section 188 to be separated into gas and liquid. The water (liquid water) separated from the generated hydrogen gas is stored in the second storage section 188. The generated hydrogen gas from which the water is separated is guided to the intermediate outlet flow path 174.

[0120] The generated hydrogen gas directed to the intermediate dehumidification flow path 174 flows into the dehumidification flow path 178 via the third flow path switching valve 194 and is dehumidified. Specifically, the generated hydrogen gas flowing from the third flow path switching valve 194 into the dehumidification upstream flow path 178a is cooled and dehumidified by the dehumidification cooling unit 198. Thereafter, the generated hydrogen gas is directed from the dehumidification upstream flow path 178a to the dehumidification downstream flow path 178b via the fourth flow path switching valve 204. The generated hydrogen gas directed to the dehumidification downstream flow path 178b flows sequentially through the first dehumidification adsorption unit 200a and the second dehumidification adsorption unit 200b before flowing into the storage flow path 180. At this point, the generated hydrogen gas is subjected to adsorption dehumidification by the first dehumidification adsorption unit 200a and the second dehumidification adsorption unit 200b. In this case, for example, by performing recovery processing (self-regeneration) of the adsorption function of the first dehumidification adsorption unit 200a and the second dehumidification adsorption unit 200b, the residual moisture content of the generated hydrogen gas can be managed to be less than a predetermined value.

[0121] The generated hydrogen gas flowing into the storage flow path 180 passes through the mesh filter 214 to remove foreign matter, and is then directed to the low-pressure hydrogen line 402 via the second back-pressure valve 216 and the supply / discharge flow path 150. Furthermore, the valve control unit 248 performs feedback control on the second back-pressure valve 216 so that the pressure of the generated hydrogen gas at a position upstream of the second back-pressure valve 216 in the storage flow path 180 is equal to or higher than a predetermined delivery pressure.

[0122] At this time, the gas meter 234 obtains the flow rate of the generated hydrogen gas (the sales volume of the generated hydrogen gas) that is led from the supply and discharge flow path 150 to the low-pressure hydrogen gas pipeline 402 and transmits it to the VPP server 240 via the gateway server 238. This completes the series of operational flows describing the water electrolysis mode of the water electrolysis power generation system 10.

[0123] When the above-mentioned water electrolysis mode is operated, the heat medium (antifreeze) circulating in the first heat exchanger 96 directly exchanges heat with the outside air through the heat medium radiator 146. In other words, in the first heat exchanger 96, the water transported by the water pump 94 does not directly exchange heat with the outside air. Therefore, even if the outside air is below freezing, the freezing of water in the first supply flow path 82 can be suppressed. In addition, in the present embodiment, the water circulation unit 64 is arranged together with the battery unit 12 in a box (not shown) having explosion-proof ventilation and heat preservation functions. Accordingly, even if the external temperature is below freezing, it is possible to prevent water from freezing due to overcooling and improve the temperature control characteristics.

[0124] The pump control unit 250 performs feedback control on the rotational speed (heat medium circulation flow rate) of the heat medium pump 144 to ensure that the temperature of the aerated water discharged from the first outlet port 56b of the battery unit 12 remains within a specified temperature range. This ensures that the temperature of the battery unit 12 remains within the upper operating temperature limit, even if the battery unit 12 overvoltage increases with aging, leading to increased heat generation. Furthermore, if the heat medium temperature at the outlet of the heat medium radiator 146 falls below a preset lower limit (e.g., -25°C), the system ECU 236 does not activate the heat medium pump 144 and instead performs a fault shutdown. Similarly, if the water temperature at the outlet of the first heat exchanger 96 falls below the expected freezing point (e.g., 1°C), the system ECU 236 performs a fault shutdown. This is because, when the outside temperature is extremely low, even if the heat medium flow rate is reduced, the water in the first heat exchanger 96 may freeze.

[0125] Furthermore, the heat medium flowing through the second heat exchanger 122 is guided toward the first heat exchanger 96 downstream of the air pump 116 while being heated by the exhaust heat of the oxidant gas pressurized by the air pump 116. Therefore, even when the outside air is below freezing, the first heat exchanger 96 can effectively prevent the water flowing through the first supply flow path 82 from freezing.

[0126] The pump control unit 250 performs feedback control on the rotation speed of the air pump 116 so that the supply flow rate of the oxidant gas obtained by the air flow meter 118 reaches the dilution flow rate. The dilution flow rate is the flow rate at which the hydrogen concentration near the outlet of the first storage unit 86 in the exhaust flow path 90 does not exceed the upper limit.

[0127] Air pump 116 functions as a dilution pump in water electrolysis mode. Furthermore, as described later, air pump 116 also functions as a pump for supplying oxidant gas in power generation mode. In this case, air pump 116 can ensure a dilution flow rate equivalent to that during maximum rated power generation. Therefore, in water electrolysis mode, the concentration of hydrogen discharged from the first gas-liquid separator 80 can be reliably controlled to be below an upper limit. Furthermore, system ECU 236 terminates water electrolysis mode if the concentration of hydrogen discharged from the first gas-liquid separator 80 exceeds the upper limit.

[0128] When the water level detected by the second water level sensor LS2 rises to the upper limit, the valve control unit 248 opens the discharge valve 192 to discharge the water in the second storage section 188 into the second chamber 86b of the first storage section 86. Then, when the water level detected by the second water level sensor LS2 drops to the lower limit, the valve control unit 248 closes the discharge valve 192 to stop draining the second storage section 188.

[0129] If the water level detected by the second water level sensor LS2 rises to the abnormal water level upper limit, the system ECU 236 performs a fault-stop process. Furthermore, if the water level detected by the second water level sensor LS2 drops to the abnormal water level lower limit, the system ECU 236 performs a fault-stop control. Furthermore, if some of the generated hydrogen gas within the second storage section 188 is blown into the second chamber 86b of the first storage section 86, the generated hydrogen gas flowing into the first storage section 86 is discharged to the atmosphere while being sufficiently diluted with the oxidant gas. The lower limit, upper limit, abnormal upper limit, and abnormal lower limit levels of the water level within the second storage section 188 are pre-stored in the storage section 246.

[0130] In this embodiment, the flow of generated hydrogen is switched to change the order in which the generated hydrogen flows through the first dehumidification adsorption unit 200a and the second dehumidification adsorption unit 200b. Figure 7 As shown, during the water electrolysis mode, valve control unit 248 controls fourth flow path switching valve 204 to flow through first switching flow path 206, closes first on-off valve 208, and opens second on-off valve 212. This causes the generated hydrogen gas, which is directed from dehumidification upstream flow path 178a to fourth flow path switching valve 204, to be directed to first switching flow path 206. The generated hydrogen gas directed to first switching flow path 206 flows sequentially through second dehumidification adsorption unit 200b and first dehumidification adsorption unit 200a before flowing into storage flow path 180 via second switching flow path 210. At this point, the generated hydrogen gas undergoes adsorption and dehumidification processing in second dehumidification adsorption unit 200b and first dehumidification adsorption unit 200a. By reversing the order in which the generated hydrogen gas flows through first dehumidification adsorption unit 200a and second dehumidification adsorption unit 200b, the replacement interval for the dehumidification adsorption units can be extended.

[0131] Next, the power generation mode of the water electrolysis power generation system 10 will be described. When the system ECU 236 receives an operation request for the power generation mode from the VPP server 240 via the gateway server 238 , the water electrolysis power generation system 10 operates in the power generation mode.

[0132] Specifically, if Figure 8 As shown in FIG. 1 , the valve control unit 248 controls various valves to be in the power generation mode (step S6). Figure 9 As shown, the valve control unit 248 opens the first back-pressure valve 138, the hydrogen supply valve 158, the purge valve 184, the discharge valve 192, and the third back-pressure valve 232. The valve control unit 248 closes the pure water supply valve 100 and the second back-pressure valve 216. Furthermore, the first on-off valve 208, the second on-off valve 212, and the drain valve 220 can be opened or closed.

[0133] Furthermore, valve control unit 248 controls flow control valve 128 to allow oxidant gas to flow through humidifier 124 and first bypass flow path 126. Furthermore, valve control unit 248 controls first flow path switching valve 130 to a flow state in oxidant gas inlet flow path 108. Valve control unit 248 controls second flow path switching valve 136 to a flow state in oxidant gas outlet flow path 112. Valve control unit 248 controls third flow path switching valve 194 to a flow state in hydrogen off-gas circulation flow path 176. Furthermore, fourth flow path switching valve 204 can be set to any flow state.

[0134] Next, the pump control unit 250 controls the various pumps to the power generation mode ( Figure 8 In step S7, the pump control unit 250 drives the air pump 116, the heat medium pump 144, and the refrigerant pump 230. Furthermore, the pump control unit 250 does not drive the water pump 94. Furthermore, the syringe control unit 252 drives the syringe 168 at a valve opening and closing time corresponding to the preset load conditions.

[0135] In this manner, the oxidant gas flowing into the oxidant gas flow path 106 passes through the air filter 114 to remove foreign matter, and is then pressurized by the air pump 116 at a position downstream of the air pump 116. The oxidant gas, having been heated by the pressurization, flows through the air flow meter 118, is cooled by the intercooler 120, and is then adjusted to a desired temperature by the second heat exchanger 122.

[0136] The oxidant gas that has passed through the second heat exchanger 122 is split by the flow control valve 128 and flows into the humidifier 124 and the first bypass flow path 126, and merges at a position downstream of the humidifier 124 in the oxidant gas flow path 106. Thereafter, the oxidant gas is introduced into the first inlet port 56a ( ) of the battery unit 12 via the first flow path switching valve 130, the oxidant gas introduction flow path 108, and the first supply flow path 82. Figure 8 Step S8).

[0137] Furthermore, hydrogen supplied from hydrogen station 400 to supply and discharge flow path 150 via low-pressure hydrogen pipeline 402 is introduced into hydrogen supply valve 158 and second supply flow path 154. After the pressure within second supply flow path 154 is maintained at a level equivalent to the delivery pressure of low-pressure hydrogen pipeline 402, check valve 160 opens. At this point, gas meter 234 obtains the flow rate of hydrogen supplied from low-pressure hydrogen pipeline 402 to supply and discharge flow path 150 (the amount of hydrogen purchased) and transmits this information to VPP server 240 via gateway server 238.

[0138] The hydrogen gas guided to the downstream side of the check valve 160 in the second supply flow path 154 is guided to the ejector 162 and the injector 168. The hydrogen gas discharged from the injector 168 and the hydrogen gas discharged from the ejector 162 are mixed with each other and introduced into the second inlet port 58a ( Figure 8 Step S9).

[0139] In the cell unit 12, the oxidant gas introduced into the first inlet port 56a is supplied to the first fluid flow path 44. The hydrogen gas introduced into the second inlet port 58a is supplied to the second fluid flow path 46. After that, in each MEA 22, the oxidant gas supplied to the first electrode 30 and the hydrogen gas supplied to the second electrode 32 are consumed by electrochemical reactions in the first electrode catalyst layer 34 and the second electrode catalyst layer 38. As a result, power generation begins ( Figure 8 At this time, the first electrode 30 generates generated water. In addition, a portion of the generated water diffuses from the first electrode 30 to the second electrode 32 via the MEA 22.

[0140] The oxidant off-gas (containing generated water) from the first electrode 30 is discharged to the first outlet port 56b. The oxidant off-gas discharged to the first outlet port 56b is directed to the oxidant gas discharge flow path 112 via the upstream discharge flow path 84a and the second flow path switching valve 136. The oxidant off-gas directed to the oxidant gas discharge flow path 112 humidifies the oxidant gas flowing through the oxidant gas flow path 106 while flowing through the humidifier 124. The oxidant off-gas then flows through the first back-pressure valve 138 and into the second chamber 86b of the first storage unit 86.

[0141] The hydrogen off-gas (containing unreacted hydrogen and generated water) from the second electrode 32 is discharged to the second outlet port 58b. The hydrogen off-gas discharged to the second outlet port 58b flows through the second outlet flow path 170 and is directed to the purge flow path 182 and the second gas-liquid separator 172. The hydrogen off-gas directed to the purge flow path 182 passes through the check valve 186 and flows into the second chamber 86b of the first storage unit 86. The hydrogen off-gas flowing into the second chamber 86b is diluted by the oxidant off-gas flowing into the second chamber 86b from the oxidant gas outlet flow path 112. The hydrogen off-gas passes between the partition wall 88 and the bottom surface of the first storage unit 86 (in the water) and is then directed to the first chamber 86a. The diluted oxidant off-gas is then discharged to the outside through the exhaust flow path 90. This allows the concentration of hydrogen discharged from the water electrolysis power generation system 10 to be controlled below a specified value during power generation mode operation.

[0142] The hydrogen waste gas flowing into the second storage section 188 of the second gas-liquid separator 172 undergoes vortex-like flow, resulting in gas-liquid separation. The hydrogen waste gas, from which water has been separated in the second storage section 188, is drawn into the ejector 162 via the intermediate outlet flow path 174, the third flow path switching valve 194, and the hydrogen waste gas circulation flow path 176, where it is reused in the power generation of the battery unit 12. This allows the hydrogen to be self-humidified by the generated water in the hydrogen waste gas. Furthermore, during power generation mode operation, the amount of hydrogen used per unit power generation of the battery unit 12 can be reduced.

[0143] The refrigerant delivered by the refrigerant pump 230 is introduced into the refrigerant inlet port 60a of the battery unit 12 via the refrigerant supply flow path 224. The refrigerant introduced into the refrigerant inlet port 60a circulates through the refrigerant flow path 48 to cool the battery unit 12 before being directed to the refrigerant outlet port 60b. The refrigerant directed to the refrigerant outlet port 60b is then directed to the refrigerant radiator 228 via the refrigerant outlet flow path 226, where it exchanges heat (cools) with the atmosphere before returning to the refrigerant supply flow path 224. This concludes the series of operations describing the power generation mode of the water electrolysis power generation system 10.

[0144] During operation in the aforementioned power generation mode, the system ECU 236 performs feedback control on the rotational speed of the intercooler 120's fan (not shown) to ensure that the temperature of the oxidant gas at the outlet of the intercooler 120 falls within a specified temperature range. Furthermore, the heat medium (antifreeze) circulating in the second heat exchanger 122 directly exchanges heat with the outside air via the heat medium radiator 146. In other words, in the second heat exchanger 122, the oxidant gas pressurized by the air pump 116 does not directly exchange heat with the outside air. Therefore, even when the outside air is below freezing, overcooling of the oxidant gas can be prevented and temperature control characteristics can be improved by reducing the flow rate of the heat medium circulating in the heat medium circulation path 142. Furthermore, the pump control unit 250 performs feedback control on the rotational speed of the heat medium pump 144 (the circulating flow rate of the heat medium) to ensure that the temperature of the oxidant gas discharged from the outlet of the second heat exchanger 122 falls within a specified range.

[0145] Furthermore, the system ECU 236 calculates the water content within the battery unit 12 based on the hydrogen concentration detected by the hydrogen sensor 91, the output request value of the battery unit 12, and the DC resistance value of the battery unit 12 detected by the impedance measurement unit 52. The pump control unit 250 then performs feedback control on the rotation speed of the air pump 116 so that the calculated water content within the battery unit 12 is within a specified range and the flow rate of the oxidant gas detected by the air flow meter 118 is greater than or equal to the set stoic equivalence ratio for the target load.

[0146] In addition, the valve control unit 248 controls the opening of the flow regulating valve 128 (the flow ratio of the oxidant gas flowing in the humidifier 124 to the oxidant gas flowing in the first bypass flow path 126) so that the battery component 12 does not dry out (resistance increases due to drying of the electrolyte membrane 28).

[0147] Furthermore, the valve control unit 248 performs feedback control on the first back pressure valve 138 so that the pressure of the oxidant gas in the first supply flow path 82 near the first inlet port 56 a of the battery unit 12 falls within a predetermined range.

[0148] Furthermore, the injector control unit 252 achieves the desired chemical equivalence ratio set value by controlling the valve opening and closing time (valve opening interval) of the injector 168 according to the target load of the battery unit 12, the pressure of the hydrogen gas, and the temperature of the hydrogen gas. The pressure of the hydrogen gas is the pressure of the hydrogen gas near the second inlet port 58a in the second supply flow path 154. The temperature of the hydrogen gas is the temperature of the hydrogen gas near the second inlet port 58a in the second supply flow path 154. The injector 168 introduces the hydrogen gas into the second inlet port 58a of the battery unit 12 in a pulsed flow. Therefore, the pressure difference required for drainage within the second fluid flow path 46 of the battery unit 12 can be ensured by a gas flow rate less than that of a steady flow. However, a pump for circulating the hydrogen exhaust gas can also be installed in the hydrogen exhaust gas circulation flow path 176 to assist in draining the second fluid flow path 46.

[0149] Furthermore, when the water level detected by the second water level sensor LS2 rises to the upper limit, the valve control unit 248 opens the discharge valve 192, draining the water in the second storage section 188 into the second chamber 86b of the first storage section 86. Subsequently, when the water level detected by the second water level sensor LS2 drops to the lower limit, the valve control unit 248 closes the discharge valve 192, stopping the drainage process from the second storage section 188. Furthermore, when the water level detected by the second water level sensor LS2 rises to the abnormal water level upper limit, the system ECU 236 performs a fail-safe shutdown process. Furthermore, when the water level detected by the second water level sensor LS2 drops to the abnormal water level lower limit, the system ECU 236 performs a fail-safe shutdown control.

[0150] During power generation mode operation, if the deviation of a specific cell voltage fluctuation in the battery unit 12 exceeds a threshold, the second fluid flow path 46 may become clogged with trapped water. Furthermore, in this case, nitrogen from air permeating the electrolyte membrane 28 from the first fluid flow path 44 may cause a hydrogen shortage in the second electrode 32. The deviation of cell voltage fluctuation refers to the difference obtained by subtracting the lowest cell voltage from the average cell voltage of all cells 20. In this case, the valve control unit 248 intermittently opens the purge valve 184 to purge the second fluid flow path 46. This enables stable power generation. At this time, the injector control unit 252 and the valve control unit 248 perform feedback control on the valve opening and closing times (valve opening intervals) of the injector 168 and the purge valve 184 to ensure that the hydrogen pressure near the second inlet port 58a of the second supply flow path 154 is within the allowable fluctuation range of the operating pressure of the second inlet port 58a under the preset load conditions.

[0151] Next, a description will be given of a process for switching from the water electrolysis mode to the power generation mode in the operating method of the water electrolysis power generation system 10 .

[0152] like Figure 10 As shown, when the system ECU 236 receives a request to switch from the water electrolysis mode to the power generation mode from the VPP server 240 via the gateway server 238, the water electrolysis stop process (step S11) is performed. In the water electrolysis stop process, the system ECU 236 stops the application of voltage to the battery unit 12 via the electrolysis power source 50.

[0153] After this, a purification process is performed to remove the retained water in the first supply flow path 82 and the first fluid flow path 44 of the battery unit 12 (step S12 ).

[0154] Specifically, in the purification process, the valve control unit 248 controls various valves to the first switching mode ( Figure 11 Step S13). That is, Figure 12 As shown, valve control unit 248 closes pure water supply valve 100 and hydrogen supply valve 158, fully opens first back-pressure valve 138, and fully closes second back-pressure valve 216. Furthermore, valve control unit 248 controls flow control valve 128 to a state where oxidant gas flows through first bypass flow path 126 and does not flow through humidifier 124. Furthermore, valve control unit 248 controls first flow path switching valve 130 to a state where oxidant gas flows through oxidant gas inlet flow path 108. Furthermore, valve control unit 248 controls second flow path switching valve 136 to a state where oxidant gas flows through oxidant gas outlet flow path 112.

[0155] Next, the pump control unit 250 controls the various pumps to operate in the first switching mode ( Figure 11That is, the pump control unit 250 drives the air pump 116 at the maximum rated flow rate. In addition, the pump control unit 250 does not start the water pump 94 and the refrigerant pump 230.

[0156] The oxidant gas flowing into the oxidant gas flow path 106 is then filtered to remove foreign matter and then pressurized by the air pump 116. The oxidant gas, heated by the pressurization, flows through the air flow meter 118, is cooled by the intercooler 120, and then is adjusted to the desired temperature by the second heat exchanger 122.

[0157] After passing through the second heat exchanger 122, the oxidizing gas passes through the flow control valve 128 and the first bypass flow path 126, thereby bypassing the humidifier 124. The oxidizing gas is then introduced into the first inlet port 56a of the cell unit 12 via the first flow path switching valve 130, the oxidizing gas introduction flow path 108, and the first supply flow path 82. At this time, water (residual water) remaining in a portion of the oxidizing gas introduction flow path 108 and a portion of the first supply flow path 82 can be urged to flow toward the first inlet port 56a.

[0158] The oxidant gas introduced into the first inlet port 56a flows toward the first outlet port 56b while pushing the retained water in the first fluid flow path 44. At this time, the oxidant gas causes the first gas diffusion layer 36 (see FIG. 1 ) immersed in water in the water electrolysis mode to flow. Figure 3 ) is dried. This restores the volatility of the first gas diffusion layer 36. The oxidant gas containing retained water, which is discharged from the first outlet port 56b to the upstream discharge flow path 84a, is then directed to the first storage portion 86 via the second flow path switching valve 136 and the oxidant gas flow path 106.

[0159] In addition, Figure 11 When the air pump 116 is started at its maximum rated value, the system ECU 236 starts the counter 256 (step S15). Next, the determination unit 254 determines whether the oxidant gas flow rate (measured value of the oxidant gas flow rate) obtained by the air flow meter 118 has reached the desired rated flow rate range (step S16). If the measured value of the oxidant gas flow rate has not reached the desired rated flow rate range (step S16: No), the pump control unit 250 increases the rotation speed of the air pump 116 (step S17). After this, the process of step S16 is repeated.

[0160] If the measured value of the oxidizing gas flow rate falls within the desired rated flow rate range (step S17: YES), the determination unit 254 determines whether the measured time t of the counter 256 has reached the predetermined time t1 (step S18). If the measured time t of the counter 256 has not reached the predetermined time t1, the process of step S18 is repeated. The predetermined time t1 is preferably set to approximately 10 seconds, for example.

[0161] When the measurement time t of the counter 256 reaches the predetermined time t1 (step S18: Yes), the impedance measurement unit 52 begins measuring the DC resistance component of the battery unit 12 (step S19). Next, the determination unit 254 determines whether the DC resistance component measured by the impedance measurement unit 52 (the measured value of the DC resistance component, the water content of the battery unit 12) falls within a predetermined range (step S20). In other words, the determination unit 254 uses the measured value of the DC resistance component to determine whether the water content of the battery unit 12 falls within the predetermined range. If the measured value of the DC resistance component does not fall within the predetermined range, the process of step S20 is repeated.

[0162] When the measured value of the DC resistance component reaches the predetermined range (step S20 : ​​Yes), the purification step is terminated and the power generation preparation step is performed (step S21 ).

[0163] In the power generation preparation process, such as Figure 13 As shown, the pump control unit 250 drives the air pump 116 under a low load condition (a load condition lower than the load request value in the power generation mode) (step S22 ). In other words, the pump control unit 250 reduces the rotation speed of the air pump 116 .

[0164] Next, the valve control unit 248 controls the flow regulating valve 128 to a state in which the oxidant gas flows through the humidifier 124 and the first bypass flow path 126. Accordingly, the oxidant gas after flowing through the humidifier 124 is guided to the battery component 12 (step S23). In addition, the valve control unit 248 opens the hydrogen supply valve 158 (step S24). Accordingly, the hydrogen flowing from the low-pressure hydrogen pipeline 402 into the supply discharge flow path 150 is guided to the battery component 12. In addition, the injector control unit 252 drives the injector 168 under low-load conditions (step S25). Accordingly, each battery 20 of the battery component 12 generates electricity under low-load conditions.

[0165] After this, the determination unit 254 determines whether the power generation start condition is met (step S26). Specifically, the determination unit 254 determines whether the battery voltage (battery voltage measurement value) of each battery 20 measured by the battery voltage measurement unit 54 is equal to or greater than a specified value and whether the deviation of the battery voltage fluctuation is within a specified tolerance. If the battery voltage measurement value is equal to or greater than the specified value and the deviation of the battery voltage fluctuation is not within the specified tolerance (step S26: No), the process of step S26 is repeated.

[0166] When the battery voltage measurement value reaches a predetermined value or more and the deviation of the battery voltage fluctuation is within a predetermined deviation (step S26: Yes), the system ECU 236 performs a power generation start process (step S26) to cause the battery unit 12 to generate power according to a predetermined load request value. Figure 10 At this point, the system ECU 236 ramps (increases at a certain rate) the load current applied to the battery unit 12 to achieve the specified power generation conditions. Furthermore, the system ECU 236 determines the hydrogen supply amount and load current to the battery unit 12 based on the load request value required to supplement the system power.

[0167] In the purification process when switching from the water electrolysis mode to the power generation mode, the impedance measurement is set between 1kHz and 10kHz. In addition, in the purification process, the superimposed current of the AC impedance sine wave is about ±2A. Accordingly, the water content of the battery component 12 can be managed so that it is within the specified range, so that drying (resistance increase due to drying of the electrolyte membrane 28) can be reliably prevented. In particular, when the electrolyte membrane 28 near the first inlet port 56a is locally dry, the reaction distribution within the battery electrode surface at the start of power generation is easily unstable, and power generation is likely to become unstable. In this way, the deterioration of the electrolyte membrane 28 may be accelerated due to the heat generated in the dry part. However, by managing the water content of the battery component 12, the degradation of the electrolyte membrane 28 due to local drying of the electrolyte membrane 28 can be prevented. Accordingly, stable power generation can be achieved.

[0168] Next, a description will be given of a process for switching from the power generation mode to the water electrolysis mode in the operating method of the water electrolysis power generation system 10 .

[0169] like Figure 14A As shown, when the system ECU 236 receives a switching request from the VPP server 240 via the gateway server 238 to switch from the power generation mode to the water electrolysis mode, the power generation stop process (step S30) is performed. Figure 14BIn the power generation stop process, the system ECU 236 switches to the OCV condition (step S31). Specifically, the system ECU 236 controls the flow rate of hydrogen and oxidant gas supplied to the battery unit 12 and the load current by ramping (reducing them at a certain ratio) to achieve the OCV condition.

[0170] Next, when the OCV condition is reached, the syringe control unit 252 stops driving the syringe 168 (step S32 ), and the pump control unit 250 stops driving the air pump 116 (step S33 ). As a result, the supply of hydrogen gas and oxidant gas to the battery unit 12 is stopped.

[0171] After this, the water electrolysis preparation step ( Figure 14A In the water electrolysis preparation process, the valve control unit 248 controls the various valves to the second switching mode (step S35). Specifically, Figure 6 As shown, valve control unit 248 opens pure water supply valve 100 and closes hydrogen supply valve 158 and purge valve 184. Furthermore, valve control unit 248 controls flow control valve 128 to enable flow in first bypass flow path 126. Furthermore, valve control unit 248 controls first flow path switching valve 130 to enable flow in dilution flow path 110. Furthermore, valve control unit 248 controls second flow path switching valve 136 to enable flow in downstream lead-out flow path 84b. Furthermore, valve control unit 248 controls third flow path switching valve 194 to enable flow in dehumidification flow path 178.

[0172] Then, in Figure 15 In step S36, the pump control unit 250 drives the water pump 94 at the rated flow rate. As a result, the water in the first storage unit 86 is supplied to the battery unit 12 via the first supply flow path 82. The water discharged from the battery unit 12 flows through the first discharge flow path 84 and returns to the first storage unit 86.

[0173] When the water pump 94 is driven, it is determined whether air is not sucked in (air is mixed in) in the first supply flow path 82, the first fluid flow path 44 of the battery unit 12, and the first outlet flow path 84. That is, the system ECU 236 measures the closing time t2 (valve opening interval) of the pure water regulating valve 76 (step S37). Next, the determination unit 254 determines whether the closing time t2 of the pure water regulating valve 76 is greater than the prescribed time t0 (step S38). When the closing time t2 of the pure water regulating valve 76 does not reach the prescribed time t0 (step S38: No), the process of step S37 is performed again. That is, when the water level obtained by the first water level sensor LS1 is lower than the lower limit level, the pure water regulating valve 76 is opened, so the process of step S37 is performed again.

[0174] If the closed time t2 of the pure water regulating valve 76 exceeds the predetermined time t0 (step S38: Yes), the system ECU 236 calculates the water level fluctuation ΔM per unit time within the first storage section 86 based on the water level within the first storage section 86 acquired by the first water level sensor LS1 (step S39). In other words, if the predetermined time t0 has elapsed since the water level acquired by the first water level sensor LS1 reached the reference level and the pure water regulating valve 76 was closed, step S39 is performed. Next, the determination unit 254 determines whether the calculated water level fluctuation ΔM is within the predetermined water level fluctuation ΔM0 (step S40). If the calculated water level fluctuation ΔM is greater than the predetermined water level fluctuation ΔM0, the process from step S39 onward is repeated.

[0175] When the calculated water level variation ΔM is within the predetermined water level variation ΔM0, the system ECU 236 determines that the first supply flow path 82, the first fluid flow path 44 of the battery unit 12, and the first outlet flow path 84 have been replaced with water (pure water), and the water electrolysis start step ( Figure 14A That is, the system ECU 236 drives the electrolytic power source 50 to apply voltage to the battery unit 12.

[0176] This embodiment has the following effects.

[0177] The water electrolysis power generation system 10 includes a first supply flow path 82, a first outlet flow path 84, a water inlet flow path 81, an oxidant gas flow path 106, an oxidant gas inlet flow path 108, a first gas-liquid separator 80, and a dilution flow path 110. The first supply flow path 82 is connected to the first inlet port 56a communicating with the first fluid flow path 44. The first outlet flow path 84 is connected to the first outlet port 56b communicating with the first fluid flow path 44 and, in water electrolysis mode, discharges gas-containing water containing generated hydrogen gas to the first outlet flow path 84. The water inlet flow path 81 introduces water into the first supply flow path 82. Oxidant gas flows through the oxidant gas flow path 106. The oxidant gas inlet flow path 108 introduces the oxidant gas flowing through the oxidant gas flow path 106 into the first supply flow path 82. The first gas-liquid separator 80 separates the gas-containing water introduced from the first outlet flow path 84 into gas and liquid. The dilution flow path 110 guides the oxidizing gas flowing through the oxidizing gas flow path 106 to the first gas-liquid separator 80 as dilution gas.

[0178] With this configuration, water can be supplied from the water inlet flow path 81 via the first supply flow path 82 to the first inlet port 56a during water electrolysis mode, and oxidant gas can be supplied from the oxidant gas flow path 106 via the oxidant gas inlet flow path 108 and the first supply flow path 82 to the first inlet port 56a during power generation mode. In other words, the first supply flow path 82 serves as both a water supply flow path and an oxidant gas supply flow path. This results in a more compact configuration compared to a case where the water supply flow path and the oxidant gas supply flow path are separately connected to the cell unit 12.

[0179] Furthermore, the oxidant gas flowing through the oxidant gas flow path 106 during the water electrolysis mode can be used as dilution gas for the first gas-liquid separator 80. This results in a more compact structure than when separate equipment is provided for supplying oxidant gas to the cell unit 12 and for supplying dilution gas to the first gas-liquid separator 80. Consequently, the water electrolysis power generation system 10 can be miniaturized with a simple structure, and manufacturing costs can be reduced.

[0180] The water electrolysis power generation system 10 includes a first flow path switching valve 130 that can switch between a flow state in the oxidant gas introduction flow path 108 and a flow state in the dilution flow path 110. The flow state in the oxidant gas introduction flow path 108 allows the oxidant gas to flow from the oxidant gas flow path 106 to the oxidant gas introduction flow path 108 and prevents the oxidant gas from flowing from the oxidant gas flow path 106 to the dilution flow path 110. The flow state in the dilution flow path 110 prevents the oxidant gas from flowing from the oxidant gas flow path 106 to the oxidant gas introduction flow path 108 and allows the oxidant gas to flow from the oxidant gas flow path 106 to the dilution flow path 110.

[0181] With this configuration, in the water electrolysis mode, the first flow path switching valve 130 is placed in a flow state for the dilution flow path 110, thereby allowing the oxidant gas to be introduced into the first gas-liquid separator 80. Furthermore, in the power generation mode, the first flow path switching valve 130 is placed in a flow state for the oxidant gas introduction flow path 108, thereby allowing the oxidant gas to be introduced into the battery unit 12.

[0182] Only one air pump 116 is attached to the oxidant gas flow path 106. During the water electrolysis mode, the oxidant gas discharged from the air pump 116 is guided to the first gas-liquid separator 80 via the dilution flow path 110. During the power generation mode, the oxidant gas discharged from the air pump 116 is guided to the first fluid flow path 44 of the battery unit 12 via the oxidant gas introduction flow path 108 and the first supply flow path 82.

[0183] According to this configuration, the oxidant gas for power generation and the oxidant gas for dilution can be supplied by a single gas pump 116. Therefore, cost reduction can be achieved by sharing the equipment.

[0184] The water electrolysis power generation system 10 includes a heat medium circulation flow path 142 and a heat medium pump 144. A heat medium flows through the heat medium circulation flow path 142. The heat medium pump 144 circulates the heat medium through the heat medium circulation flow path 142. A first heat exchanger 96 and a second heat exchanger 122 are mounted on the heat medium circulation flow path 142. The first heat exchanger 96 exchanges heat between the water flowing through the water inlet flow path 81 and the heat medium. The second heat exchanger 122 exchanges heat between the oxidant gas flowing through the oxidant gas flow path 106 and the heat medium.

[0185] With this configuration, the water flowing through the water inlet flow path 81 and the heat medium exchange heat through the first heat exchanger 96 (the water flowing through the water inlet flow path 81 does not directly exchange heat with the outside air in the first heat exchanger 96). Therefore, even when the outside air is below freezing, freezing of the water in the water inlet flow path 81 can be suppressed. Furthermore, since the heat medium, which has been heated by the oxidant gas in the second heat exchanger 122, circulates through the heat medium circulation flow path 142, freezing of the water in the water inlet flow path 81 can be further suppressed.

[0186] A heat medium radiator 146 for cooling the heat medium is attached to the heat medium circulation flow path 142. The heat medium led out from the heat medium radiator 146 flows through the second heat exchanger 122 and the first heat exchanger 96 in sequence, and then returns to the heat medium radiator 146.

[0187] With this configuration, the oxidant gas flowing through the oxidant gas flow path 106 can be cooled more efficiently by the second heat exchanger 122. Furthermore, when the outside air is below freezing, the heat medium heated by the oxidant gas in the second heat exchanger 122 flows through the first heat exchanger 96 before being directed to the heat medium radiator 146. Therefore, freezing of the water in the water inlet flow path 81 can be further suppressed.

[0188] A humidifier 124 for humidifying the oxidant gas is installed in the oxidant gas flow path 106 downstream of the second heat exchanger 122. In the power generation mode, the humidifier 124 humidifies the oxidant gas using the oxidant off-gas discharged from the first outlet port 56b.

[0189] With this configuration, the oxidant gas whose temperature has been adjusted (after cooling) by the second heat exchanger 122 is directed to the humidifier 124. Therefore, even when the oxidant off-gas, whose temperature has been raised by the battery unit 12, flows through the humidifier 124 during power generation mode, it is possible to suppress an excessive increase in the temperature and humidity of the oxidant gas introduced into the battery unit 12.

[0190] A first bypass flow path 126 and a flow control valve 128 are provided in the oxidant gas flow path 106. The first bypass flow path 126 is connected to the upstream side and the downstream side of the humidifier 124, bypassing the humidifier 124. The flow control valve 128 can adjust the ratio between the flow rate of the oxidant gas directed to the humidifier 124 and the flow rate of the oxidant gas directed to the first bypass flow path 126.

[0191] With this configuration, when switching from the water electrolysis mode to the power generation mode, the dry oxidant gas flowing through the first bypass flow path 126 can be introduced into the battery unit 12. Therefore, the retained water in the first fluid flow path 44 of the battery unit 12 can be efficiently drained (purified).

[0192] The water electrolysis power generation system 10 includes a second supply flow path 154, a second outlet flow path 170, a second gas-liquid separator 172, a hydrogen waste gas circulation flow path 176, and a storage flow path 180. The second supply flow path 154 supplies hydrogen to the second fluid flow path 46. During the water electrolysis mode, generated hydrogen is discharged from the second fluid flow path 46 to the second outlet flow path 170. Furthermore, during the power generation mode, hydrogen waste gas is discharged from the second fluid flow path 46 to the second outlet flow path 170. The second gas-liquid separator 172 performs gas-liquid separation between the generated hydrogen and hydrogen waste gas guided from the second outlet flow path 170. The hydrogen waste gas circulation flow path 176 guides the hydrogen waste gas, separated by the second gas-liquid separator 172, to the second supply flow path 154. The storage flow path 180 guides the generated hydrogen, separated by the second gas-liquid separator 172, to the hydrogen storage unit 410. The water electrolysis power generation system 10 uses the second outlet flow path 170 and the second gas-liquid separator 172 in common in the water electrolysis mode and the power generation mode.

[0193] With this configuration, the second outlet flow path 170 and second gas-liquid separator 172 are shared in both the water electrolysis mode and the power generation mode. Therefore, there is no need to provide separate outlet flow paths and gas-liquid separators for the water electrolysis mode and separate outlet flow paths and gas-liquid separators for the electrolysis mode. Consequently, the water electrolysis power generation system 10 can be miniaturized with a simple structure, and its manufacturing cost can be reduced.

[0194] The water electrolysis power generation system 10 includes an intermediate lead-out flow path 174, a dehumidification flow path 178, and a second flow path switching valve 136. The generated hydrogen and hydrogen waste gas that have passed through the second gas-liquid separator 172 are directed to the intermediate lead-out flow path 174. The dehumidification flow path 178 dehumidifies the generated hydrogen flowing through the intermediate lead-out flow path 174 and directs it to the storage flow path 180. The second flow path switching valve 136 can switch between a flow state in the dehumidification flow path 178 and a flow state in the hydrogen waste gas circulation flow path 176. The flow state in the dehumidification flow path 178 allows hydrogen waste gas to flow from the intermediate lead-out flow path 174 to the hydrogen waste gas circulation flow path 176 during the water electrolysis mode, while preventing hydrogen waste gas from flowing from the intermediate lead-out flow path 174 to the dehumidification flow path 178. The flow state of the hydrogen off-gas circulation flow path 176 refers to a state in which the generated hydrogen is allowed to flow from the intermediate outlet flow path 174 to the dehumidification flow path 178 in the power generation mode, and the generated hydrogen is prevented from flowing from the intermediate outlet flow path 174 to the hydrogen off-gas circulation flow path 176.

[0195] With this configuration, in the water electrolysis mode, the second flow path switching valve 136 is placed in a flow state allowing the dehumidification flow path 178 to flow, thereby allowing the generated hydrogen gas, which is discharged from the second gas-liquid separator 172 to the intermediate discharge flow path 174, to be directed to the hydrogen storage unit 410 via the dehumidification flow path 178 and the storage flow path 180. Furthermore, in the power generation mode, the second flow path switching valve 136 is placed in a flow state allowing the hydrogen off-gas circulation flow path 176 to flow, thereby allowing the hydrogen off-gas, which is discharged from the second gas-liquid separator 172 to the intermediate discharge flow path 174, to be directed to the battery unit 12 via the hydrogen off-gas circulation flow path 176 and the second supply flow path 154.

[0196] The dehumidification flow path 178 is equipped with a first dehumidification adsorption unit 200a, a second dehumidification adsorption unit 200b, and a dehumidification switching unit 202. The first and second dehumidification adsorption units 200a, 200b dehumidify the generated hydrogen gas and can restore the dehumidification function. The dehumidification switching unit 202 switches the flow direction of the generated hydrogen gas, changing the order in which the generated hydrogen gas flows through the first and second dehumidification adsorption units 200a, 200b.

[0197] According to this configuration, the first dehumidification adsorption unit 200a and the second dehumidification adsorption unit 200b can be self-regenerated in the water electrolysis mode, thereby extending the replacement time interval between the first dehumidification adsorption unit 200a and the second dehumidification adsorption unit 200b.

[0198] The water electrolysis power generation system 10 includes a supply and discharge flow path 150. The supply and discharge flow path 150 directs the generated hydrogen gas from the storage flow path 180 to the hydrogen storage unit 410. Furthermore, the supply and discharge flow path 150 directs the hydrogen gas from the hydrogen storage unit 410 to the second supply flow path 154. A gas meter 234 is attached to the supply and discharge flow path 150 to measure the flow rate of hydrogen gas flowing from the hydrogen storage unit 410 to the supply and discharge flow path 150 and the flow rate of generated hydrogen gas flowing from the supply and discharge flow path 150 to the hydrogen storage unit 410.

[0199] According to this configuration, the amount of hydrogen gas introduced and the amount of generated hydrogen gas discharged can be easily managed based on the information acquired by the gas meter 234 .

[0200] The operating method of the water electrolysis power generation system 10 includes a water electrolysis stop step, a purge step, and a power generation start step when switching from water electrolysis mode to power generation mode. In the water electrolysis stop step, water electrolysis in the cell unit 12 is stopped. In the purge step, oxidant gas is supplied from the oxidant gas flow path 106 to the first fluid flow path 44 via the oxidant gas introduction flow path 108, the first supply flow path 82, and the first inlet port 56a after the water electrolysis stop step. In the power generation start step, after the purge step, power generation is started in the cell unit 12 according to a predetermined load demand value.

[0201] According to this method, during the water electrolysis mode, water (retained water) present in the first supply flow path 82 and the first fluid flow path 44 of the battery unit 12 (during the water electrolysis mode) is discharged to the first gas-liquid separator 80 using an oxidant gas during a purification step. This allows for smooth and reliable switching from the water electrolysis mode to the power generation mode. Furthermore, by utilizing a portion of the first supply flow path 82 for both water supply and purification, the water electrolysis power generation system 10 can be miniaturized and manufactured at low cost.

[0202] In the cleaning step, the first electrode 30 is dried by the oxidant gas flowing through the first fluid flow path 44 .

[0203] According to this method, power generation by the battery unit 12 can be smoothly started in the power generation start step.

[0204] A humidifier 124 and a first bypass channel 126 are installed in the oxidant gas flow path 106. The humidifier 124 humidifies the oxidant gas. The first bypass channel 126 is connected to the oxidant gas flow path 106 upstream and downstream of the humidifier 124, bypassing the humidifier 124. During the purification process, the oxidant gas is not directed to the humidifier 124 but to the first bypass channel 126.

[0205] According to this method, the first electrode 30 can be dried efficiently during the cleaning process.

[0206] The battery unit 12 includes a plurality of cells 20. The method for operating the water electrolysis power generation system 10 includes a power generation preparation step performed between the purification step and the power generation start step. In the power generation preparation step, the battery unit 12 generates power at a low load lower than the requested load value, and the cell voltage of each cell 20 is obtained. The power generation start step is executed when the cell voltage obtained in the power generation preparation step reaches or exceeds a specified value.

[0207] According to this method, each battery 20 can reliably generate power in the power generation start step.

[0208] In the power generation preparation step, it is determined whether the variation in battery voltage among the plurality of batteries 20 is within a predetermined range. If the variation in battery voltage is within the predetermined range in the power generation preparation step, the power generation start step is performed.

[0209] According to this method, each battery 20 can generate power in a balanced manner in the power generation start step.

[0210] The operating method of the water electrolysis power generation system 10 includes a power generation stop step and a water electrolysis start step when switching from power generation mode to water electrolysis mode. In the power generation stop step, power generation by the battery unit 12 is stopped. In the water electrolysis start step, water electrolysis in the battery unit 12 is started when the water level in the first gas-liquid separator 80 is above the lower limit level.

[0211] According to this method, water electrolysis is started when the water level in the first gas-liquid separator 80 is above the lower limit level, thereby preventing air from being mixed into the water supplied to the battery unit 12 during the water electrolysis start process. This allows for smooth switching from power generation mode to water electrolysis mode.

[0212] In the water electrolysis starting step, water electrolysis in the battery unit 12 is started when the water level fluctuation amount ΔM per unit time in the first gas-liquid separator 80 is equal to or less than a predetermined water level fluctuation amount ΔM0.

[0213] According to this method, it is possible to further suppress mixing of air into the water supplied to the battery unit 12 during the water electrolysis start step.

[0214] The number of dehumidification adsorption units in the water electrolysis power generation system 10 is not limited to two, and may be three or more.

[0215] In addition, the present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

[0216] The above implementation modes are summarized as follows.

[0217] The above embodiment discloses a water electrolysis power generation system (10), which has a battery component (12), and the battery component (12) has an MEA (22), a first fluid flow path (44) and a second fluid flow path (46), wherein the MEA (22) is composed of an electrolyte membrane (28) sandwiched between a first electrode (30) and a second electrode (32); the first fluid flow path (44) is used to supply water and oxidant gas to the first electrode; the second fluid flow path (46) is used to The water electrolysis power generation system (10) is capable of switching between a water electrolysis mode and a power generation mode for supplying hydrogen to the second electrode, wherein the water electrolysis mode is a mode in which the water supplied to the first electrode is electrolyzed to generate hydrogen at the second electrode; and the power generation mode is a mode in which power is generated by an electrochemical reaction between the oxidant gas supplied to the first electrode and the hydrogen supplied to the second electrode. The water electrolysis power generation system comprises a supply flow path (82), an outlet flow path ( 84), a water inlet flow path (81), an oxidant gas flow path (106), an oxidant gas inlet flow path (108), a gas-liquid separator (80) and a dilution flow path (110), wherein the supply flow path (82) is connected to an inlet port portion (56a) communicating with the first fluid flow path; the outlet flow path (84) is connected to an outlet port portion (56b) communicating with the first fluid flow path, and in the water electrolysis mode, the gas-containing water containing the generated hydrogen is exported to the outlet flow path (84); the water outlet flow path (84) is connected to an outlet port portion (56b) communicating with the first fluid flow path; The inlet flow path (81) introduces the water into the supply flow path; the oxidant gas flow path (106) allows the oxidant gas to circulate; the oxidant gas inlet flow path (108) introduces the oxidant gas flowing in the oxidant gas flow path into the supply flow path; the gas-liquid separator (80) performs gas-liquid separation on the gas-containing water discharged from the outlet flow path; and the dilution flow path (110) guides the oxidant gas flowing in the oxidant gas flow path as a dilution gas to the gas-liquid separator.

[0218] The above-mentioned water electrolysis power generation system may also have a flow path switching valve (130), which can be switched between a first state and a second state, wherein the first state refers to a state in which the oxidant gas is allowed to flow from the oxidant gas flow path to the oxidant gas inlet flow path and the oxidant gas is prevented from flowing from the oxidant gas flow path to the dilution flow path; and the second state refers to a state in which the oxidant gas is prevented from flowing from the oxidant gas flow path to the oxidant gas inlet flow path and the oxidant gas is allowed to flow from the oxidant gas flow path to the dilution flow path.

[0219] In the above-mentioned water electrolysis power generation system, only one air pump (116) may be installed on the oxidant gas flow path, and the oxidant gas discharged from the air pump is guided to the gas-liquid separator via the dilution flow path in the water electrolysis mode, and is guided to the first fluid flow path of the battery component via the oxidant gas inlet flow path and the supply flow path in the power generation mode.

[0220] In the above-mentioned water electrolysis power generation system, there may also be a heat medium circulation flow path (142) for circulating a heat medium and a heat medium pump (144) for circulating the heat medium in the heat medium circulation flow path, and a first heat exchanger (96) and a second heat exchanger (122) are installed on the heat medium circulation flow path, wherein the first heat exchanger (96) performs heat exchange between the water circulating in the water inlet flow path and the heat medium; and the second heat exchanger (122) performs heat exchange between the oxidant gas circulating in the oxidant gas flow path and the heat medium.

[0221] In the above-mentioned water electrolysis power generation system, a heat medium radiator (146) for cooling the heat medium may be installed on the heat medium circulation flow path, and the heat medium discharged from the heat medium radiator flows through the second heat exchanger and the first heat exchanger in sequence and then returns to the heat medium radiator.

[0222] In the above-mentioned water electrolysis power generation system, a humidifier (124) for humidifying the oxidant gas may be installed at a position downstream of the second heat exchanger in the oxidant gas flow path, and in the humidifier, the oxidant gas is humidified by the oxidant exhaust gas discharged from the outlet port during the power generation mode.

[0223] In the above-mentioned water electrolysis power generation system, a bypass flow path (126) and a flow regulating valve (128) may be installed on the oxidant gas flow path, wherein the bypass flow path (126) is connected to the upstream side of the humidifier and the downstream side of the humidifier and bypasses the humidifier; and the flow regulating valve (128) can adjust the ratio of the flow rate of the oxidant gas guided to the humidifier and the flow rate of the oxidant gas guided to the bypass flow path.

[0224] The above embodiment discloses a water electrolysis power generation system, which has a battery component, and the battery component has an MEA, a first fluid flow path and a second fluid flow path, wherein the MEA is composed of an electrolyte membrane sandwiched by a first electrode and a second electrode; the first fluid flow path is used to supply water and an oxidant gas to the first electrode; the second fluid flow path is used to supply hydrogen to the second electrode, and the water electrolysis power generation system can be switched between a water electrolysis mode and a power generation mode, wherein the water electrolysis mode refers to a mode in which the water supplied to the first electrode is electrolyzed to generate hydrogen at the second electrode; the power generation mode refers to a mode in which power is generated by an electrochemical reaction between the oxidant gas supplied to the first electrode and the hydrogen supplied to the second electrode, and the water electrolysis power generation system has a supply flow path (154), an outlet flow path (170), a gas-liquid separator (17 2) a circulation flow path (176) and a storage flow path (180), wherein the supply flow path (154) supplies the hydrogen to the second fluid flow path; the derivation flow path (170) is configured to derivate the generated hydrogen from the second fluid flow path to the derivation flow path (170) in the water electrolysis mode and derivate the hydrogen waste gas from the second fluid flow path to the derivation flow path (170) in the power generation mode; the gas-liquid separator (172) performs gas-liquid separation on the generated hydrogen and the hydrogen waste gas guided from the derivation flow path; the circulation flow path (176) guides the hydrogen waste gas after gas-liquid separation by the gas-liquid separator to the supply flow path; the storage flow path (180) is used to guide the generated hydrogen after gas-liquid separation by the gas-liquid separator to the hydrogen storage part (410), and the derivation flow path and the gas-liquid separator are shared in the water electrolysis mode and the power generation mode.

[0225] The water electrolysis power generation system may also include an intermediate lead-out flow path (174), a dehumidification flow path (178), and a flow path switching valve (194), wherein the intermediate lead-out flow path (174) is configured such that the generated hydrogen and the hydrogen waste gas after flowing through the gas-liquid separator are led to the intermediate lead-out flow path (174); the dehumidification flow path (178) dehumidifies the generated hydrogen flowing in the intermediate lead-out flow path and guides it to the storage flow path; the flow path switching valve (194) can be switched between a first state and a second state, wherein the first state refers to a state in which the hydrogen waste gas is allowed to flow from the intermediate lead-out flow path to the circulation flow path and is prevented from flowing from the intermediate lead-out flow path to the dehumidification flow path in the water electrolysis mode; and the second state refers to a state in which the generated hydrogen is allowed to flow from the intermediate lead-out flow path to the dehumidification flow path and is prevented from flowing from the intermediate lead-out flow path to the circulation flow path in the power generation mode.

[0226] In the above-mentioned water electrolysis power generation system, a plurality of dehumidification adsorption parts (200a, 200b) and a dehumidification switching part (202) may be installed on the dehumidification flow path, wherein the plurality of dehumidification adsorption parts (200a, 200b) dehumidify the generated hydrogen and can restore the dehumidification function; and the dehumidification switching part (202) switches the flow direction of the generated hydrogen to change the order in which the generated hydrogen flows through the plurality of dehumidification adsorption parts.

[0227] The above-mentioned water electrolysis power generation system may also have a supply and discharge flow path (150), which is used to discharge the generated hydrogen from the storage flow path to the hydrogen storage part and introduce the hydrogen from the hydrogen storage part into the supply flow path, and a flow acquisition part (234) is installed on the supply and discharge flow path, which acquires the flow rate of the hydrogen flowing from the hydrogen storage part to the supply and discharge flow path and the flow rate of the generated hydrogen flowing from the supply and discharge flow path to the hydrogen storage part.

[0228] The above embodiment discloses an operating method of a water electrolysis power generation system, wherein the water electrolysis power generation system has a battery component, the battery component has an MEA, a first fluid flow path and a second fluid flow path, wherein the MEA is composed of an electrolyte membrane sandwiched by a first electrode and a second electrode; the first fluid flow path is used to supply water and an oxidant gas to the first electrode; the second fluid flow path is used to supply hydrogen to the second electrode, and the water electrolysis power generation system can be switched between a water electrolysis mode and a power generation mode, wherein the water electrolysis mode refers to the electrolysis mode. The water supplied to the first electrode causes the second electrode to generate hydrogen; the power generation mode refers to a mode in which power is generated by an electrochemical reaction between the oxidant gas supplied to the first electrode and the hydrogen supplied to the second electrode, and the water electrolysis power generation system comprises a supply flow path, an outlet flow path, a water inlet flow path, an oxidant gas flow path, an oxidant gas inlet flow path, and a gas-liquid separator, wherein the supply flow path is connected to an inlet port portion communicating with the first fluid flow path; the outlet flow path is connected to an outlet port portion communicating with the first fluid flow path. The inlet port is configured to discharge gas-containing water containing the generated hydrogen gas to the outlet flow path in the water electrolysis mode; the water inlet flow path is configured to discharge the gas-containing water containing the generated hydrogen gas to the outlet flow path in the water electrolysis mode; the water inlet flow path is configured to discharge the water to the supply flow path; the oxidant gas flow path is configured to flow the oxidant gas; the oxidant gas inlet flow path is configured to discharge the oxidant gas flowing in the oxidant gas flow path to the supply flow path; the gas-liquid separator is configured to perform gas-liquid separation on the gas-containing water discharged from the outlet flow path; the operating method of the water electrolysis power generation system includes a water electrolysis stopping step, a purge step, and a power generation starting step when switching from the water electrolysis mode to the power generation mode, wherein in the water electrolysis stopping step, water electrolysis of the cell component is stopped; in the purge step, after the water electrolysis stopping step, the oxidant gas is caused to flow from the oxidant gas flow path through the oxidant gas inlet flow path, the supply flow path, the inlet port, the first fluid flow path, the outlet port, and the outlet flow path to the gas-liquid separator; and in the power generation starting step, after the purge step, the cell component is configured to generate power according to a predetermined load request value.

[0229] In the above-described method for operating a water electrolysis power generation system, in the purification step, the first electrode may be dried by the oxidant gas flowing through the first fluid flow path.

[0230] In the above-mentioned method for operating the water electrolysis power generation system, a humidifier and a bypass flow path may be installed in the oxidant gas flow path, the humidifier being used to humidify the oxidant gas; the bypass flow path is connected to the upstream side and downstream side of the humidifier in the oxidant gas flow path in a manner that bypasses the humidifier, and in the purification process, the oxidant gas is not allowed to flow to the humidifier but is allowed to flow to the bypass flow path.

[0231] In the above-mentioned operating method of the water electrolysis power generation system, the battery component may have a plurality of the batteries, and include a power generation preparation process performed between the purification process and the power generation start process. In the power generation preparation process, the battery component generates power under a low load condition lower than the load request value, and the battery voltage of each of the batteries is obtained. The power generation start process is implemented when the battery voltage of each of the batteries obtained in the power generation preparation process reaches a specified value or above.

[0232] In the above-mentioned method for operating the water electrolysis power generation system, it is also possible that, in the power generation preparation process, it is determined whether the deviation of the battery voltage of the plurality of batteries is within a prescribed range, and the power generation start process is implemented when the deviation of the battery voltage is within the prescribed range in the power generation preparation process.

[0233] The above embodiment discloses an operating method of a water electrolysis power generation system, wherein the water electrolysis power generation system has a battery component, the battery component has an MEA, a first fluid flow path and a second fluid flow path, wherein the MEA is composed of an electrolyte membrane sandwiched by a first electrode and a second electrode; the first fluid flow path is used to supply water and an oxidant gas to the first electrode; the second fluid flow path is used to supply hydrogen to the second electrode, and the water electrolysis power generation system can switch between a water electrolysis mode and a power generation mode, wherein the water electrolysis mode refers to a mode in which the water supplied to the first electrode is electrolyzed to generate hydrogen at the second electrode; the power generation mode refers to a mode in which power is generated by an electrochemical reaction between the oxidant gas supplied to the first electrode and the hydrogen supplied to the second electrode, and the water electrolysis power generation system has A water inlet flow path, an outlet flow path and a gas-liquid separator, wherein the water inlet flow path is used to supply the water to the inlet port portion connected to the first fluid flow path; the outlet flow path is connected to the outlet port portion connected to the first fluid flow path, and in the water electrolysis mode, the gas-containing water containing the generated hydrogen is exported to the outlet flow path; the gas-liquid separator is formed to be able to store the water and is connected to the water inlet flow path, and performs gas-liquid separation on the gas-containing water exported from the outlet flow path, and the operation method of the water electrolysis power generation system includes a power generation stop process and a water electrolysis start process when switching from the power generation mode to the water electrolysis mode, wherein in the power generation stop process, the power generation of the battery component is stopped; in the water electrolysis start process, the water electrolysis of the battery component is started when the water level in the gas-liquid separator is above the lower limit level.

[0234] In the above-described method for operating a water electrolysis power generation system, in the water electrolysis starting step, water electrolysis in the cell unit may be started when a water level fluctuation per unit time in the gas-liquid separator is equal to or less than a predetermined water level fluctuation.

Claims

1. A method for operating a water electrolysis power generation system, wherein the water electrolysis power generation system comprises a battery component including a battery, the battery component comprising an MEA, a first fluid flow path, and a second fluid flow path, wherein: The MEA is formed by sandwiching an electrolyte membrane between a first electrode and a second electrode, the first fluid flow path is used to supply water and oxidant gas to the first electrode; the second fluid flow path is used to supply hydrogen gas to the second electrode, The water electrolysis power generation system can switch between a water electrolysis mode and a power generation mode, wherein the water electrolysis mode is a mode in which water supplied to the first electrode is electrolyzed to generate hydrogen at the second electrode; and the power generation mode is a mode in which power is generated by an electrochemical reaction between an oxidant gas supplied to the first electrode and hydrogen supplied to the second electrode. The operating method of the water electrolysis power generation system is characterized in that: The water electrolysis power generation system comprises a supply flow path, an outlet flow path, a water inlet flow path, an oxidant gas flow path, an oxidant gas inlet flow path and a gas-liquid separator, wherein: The supply flow path is connected to an inlet port portion communicating with the first fluid flow path; The outlet flow path is connected to an outlet port portion communicating with the first fluid flow path, and in the water electrolysis mode, the carbonated water containing the generated hydrogen gas is discharged to the outlet flow path, wherein the generated hydrogen gas permeates from the second electrode to the first electrode; The water introduction flow path is used to introduce the water into the supply flow path; The oxidant gas flow path is used for the circulation of the oxidant gas; The oxidant gas introduction flow path connects the oxidant gas flow path and the supply flow path, and is used to introduce the oxidant gas flowing in the oxidant gas flow path into the supply flow path; The gas-liquid separator is used to separate the gas-containing water guided from the outlet flow path into gas and liquid. The operation method of the water electrolysis power generation system includes a water electrolysis stopping process, a purification process, and a power generation starting process when switching from the water electrolysis mode to the power generation mode. The water electrolysis stopping step refers to a step of stopping the water electrolysis performed by the battery component; The purification step is a step of flowing the oxidant gas from the oxidant gas flow path through the oxidant gas introduction flow path, the supply flow path, the inlet port, the first fluid flow path, the outlet port, and the outlet flow path to the gas-liquid separator after the water electrolysis stopping step. The power generation start step is a step of causing the battery unit to generate power according to a predetermined load request value after the purge step.

2. The operating method of the water electrolysis power generation system according to claim 1, characterized in that: In the cleaning step, the first electrode is dried by the oxidant gas flowing through the first fluid flow path.

3. The operating method of the water electrolysis power generation system according to claim 2, characterized in that: A humidifier and a bypass flow path are installed on the oxidant gas flow path, wherein The humidifier is used to humidify the oxidant gas; The bypass flow path is connected to the upstream side and the downstream side of the humidifier in the oxidant gas flow path in a manner bypassing the humidifier. In the purification step, the oxidizing gas is not caused to flow through the humidifier but is caused to flow through the bypass flow path.

4. The method for operating a water electrolysis power generation system according to any one of claims 1 to 3, characterized in that: The battery component has a plurality of batteries. The method for operating the water electrolysis power generation system includes a power generation preparation step, which is performed between the purification step and the power generation start step. In the power generation preparation step, the battery unit generates power under a low load condition lower than the load request value and acquires the battery voltage of each of the batteries. The power generation starting step is performed when the voltage of each of the batteries acquired in the power generation preparation step reaches a predetermined value or higher.

5. The operating method of the water electrolysis power generation system according to claim 4, characterized in that: In the power generation preparation step, it is determined whether the deviation of the battery voltages of the plurality of batteries is within a predetermined range. The power generation starting step is performed when it is determined in the power generation preparation step that the deviation of the battery voltage is within the predetermined range.

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