Water electrolysis device

Abstract

The invention relates to a water electrolysis device, which can well inhibit performance degradation and deterioration of a supercharger that recirculates hydrogen generated by a water electrolysis module in the water electrolysis module. The water electrolysis device according to the present disclosure comprises: a water electrolysis module for generating hydrogen by water vapor electrolysis; a supercharger for supplying hydrogen to the water electrolysis module; a recirculation passage for supplying the hydrogen generated by the water electrolysis module from the water electrolysis module to the intake port of the supercharger; a condenser that condenses water vapor contained in the generated hydrogen; and a temperature raising unit that raises the temperature of the generated hydrogen between the condenser and the supercharger.

Description

Technical Field

[0001] The present disclosure relates to a water electrolysis apparatus including a water electrolysis module that generates hydrogen by electrolysis of water vapor. Background Art

[0002] Conventionally, a water electrolysis apparatus is known in which hydrogen generated at a fuel electrode of a water electrolysis cell is mixed with water vapor supplied to the fuel electrode and recycled in the water electrolysis cell (for example, see Patent Document 1). In this water electrolysis apparatus, the fuel electrode exhaust gas cooled by a cooler is supplied to a phase separator, and the gas that has passed through the phase separator is boosted by a supercharger and then mixed with water vapor.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-517233

[0004] However, in the above-described conventional water electrolysis apparatus, a gas containing saturated water vapor in addition to hydrogen is supplied from the phase separator to the supercharger, and there is a possibility that water vapor condenses in the supercharger, resulting in a decrease in the performance and deterioration of the supercharger. Summary of the Invention

[0005] Therefore, a main object of the present disclosure is to provide a water electrolysis apparatus that can satisfactorily suppress a decrease in the performance and deterioration of a supercharger that recycles hydrogen generated in a water electrolysis module in the water electrolysis module.

[0006] The water electrolysis apparatus of the present disclosure is a water electrolysis apparatus including a water electrolysis module that generates hydrogen by electrolysis of water vapor, and includes: a supercharger that supplies hydrogen to the water electrolysis module; a recirculation passage that supplies generated hydrogen generated by the water electrolysis module to an intake port of the supercharger; a condenser that condenses water vapor contained in the generated hydrogen; and a heating unit that heats the generated hydrogen between the condenser and the supercharger.

[0007] In the water electrolysis device of the present disclosure, the generated hydrogen generated by the water electrolysis module is supplied from the water electrolysis module to the suction port of the supercharger via the recirculation passage. In addition, the water vapor contained in the generated hydrogen is condensed in the condenser, and further, the generated hydrogen that has passed through the condenser is heated by the heating unit between the condenser and the supercharger. Moreover, the generated hydrogen heated by the heating unit is supplied to the water electrolysis module by the supercharger. Thus, the generated hydrogen below the dew point temperature is not supplied from the recirculation passage to the supercharger, and it is possible to suppress the condensation of water vapor in the recirculation passage and the supercharger. As a result, it is possible to satisfactorily suppress the performance degradation and deterioration of the supercharger that recirculates the hydrogen generated by the water electrolysis module in the water electrolysis module. In addition, the supercharger may supply hydrogen for antioxidant protection to the fuel electrode of the water electrolysis cell. Further, the supercharger may supply hydrogen for combustion to the burner included in the water electrolysis module. And the water electrolysis module may include a reversible water electrolysis cell that generates electricity by the electrochemical reaction of hydrogen supplied to the fuel electrode and oxygen supplied to the oxidant electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic configuration diagram showing the water electrolysis device of the present disclosure.

[0009] Figure 2 is a system diagram showing the water electrolysis device of the present disclosure.

[0010] DESCRIPTION OF REFERENCE NUMERALS

[0011] 1... Water electrolysis device; 2... Water electrolysis module; 4... Steam generator; 6... Condenser; 7, 8... Hydrogen supercharger; 10... Housing; 13... Air suction port; 15... Exhaust port; 17... Ventilation fan; 18... Heating unit; 20... Water electrolysis cell stack; 20b... Fuel electrode; F7, F8... Flowmeter; L2... Hydrogen flow pipe; L7... Hydrogen flow pipe (recirculation passage); L8... Recirculation pipe (recirculation passage). DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, a mode for implementing the invention of the present disclosure will be described with reference to the drawings.

[0013] Figure 1 is a schematic configuration diagram showing the water electrolysis device 1 of the present disclosure, Figure 2 is a system diagram showing the water electrolysis device 1. The water electrolysis device 1 shown in these drawings includes a plurality (two in the present embodiment) of water electrolysis modules 2, a power supply device 3, a steam generator 4, a plurality (two in the present embodiment) of blowers 5, a condenser 6, a plurality (two in the present embodiment) of hydrogen superchargers 7 for combustion, a plurality (two in the present embodiment) of hydrogen superchargers 8 for antioxidant protection, a water tank 9, and a housing 10 that houses these components. In addition, for simplicity of explanation, Figure 2It only represents one of the two water electrolysis modules 2.

[0014] As Figure 1 shown, each water electrolysis module 2 is arranged and disposed longitudinally or transversely in the upper part within the housing 10. Each water electrolysis module 2 includes a water electrolysis battery pack 20 that generates hydrogen by electrolyzing water vapor. The water electrolysis battery pack 20 includes a plurality of solid oxide type electrolysis cells (SOEC, hereinafter referred to as "single cells") stacked in a specified direction. In addition, each single cell includes an electrolyte 20a, a fuel electrode 20b disposed on one side of the electrolyte 20a, and an oxidant electrode 20c disposed on the other side of the electrolyte 20a.

[0015] The electrolyte 20a is a solid electrolyte such as stabilized zirconia (e.g., YSZ). The fuel electrode 20b is formed of a composite material of a catalyst metal such as Ni and stabilized zirconia. The oxidant electrode 20c is formed of a ceramic such as LSCF. Each single cell electrolyzes water vapor under a high-temperature environment of, for example, 650 - 800 °C by applying electric power (direct current power) from the power supply device 3, generates hydrogen at the fuel electrode 20b, and generates oxygen at the oxidant electrode 20c. And, in the present embodiment, the single cells of the water electrolysis battery pack 20 are reversible operation type water electrolysis cells that generate hydrogen and oxygen by electrolyzing water vapor and transmit power to a system power supply or the like through the electrochemical reaction of hydrogen and oxygen.

[0016] In addition to the water electrolysis battery pack 20, each water electrolysis module 2 includes various pipes, a plurality of heat exchangers, etc. The constituent elements of these water electrolysis modules 2 are housed in a module housing 21 formed by arranging heat insulating members in a housing member. As Figure 2 shown, a fuel supply pipe L1 forming a fuel supply passage is connected to the fuel electrode inlet of the water electrolysis battery pack 20 of each water electrolysis module 2. The fuel supply pipe L1 of each water electrolysis module 2 is connected to a steam generator 4 provided outside the housing 10 of the water electrolysis device 1 via heat exchangers 22 and 23 within the module housing 21.

[0017] In addition, a hydrogen circulation pipe L2 is connected to the fuel electrode outlet of the water electrolysis battery pack 20 of each water electrolysis module 2, and the hydrogen (generated hydrogen) generated at the fuel electrode 20b of each single cell and the fuel electrode exhaust gas containing water vapor flow into this hydrogen circulation pipe L2. The hydrogen circulation pipes L2 from each water electrolysis battery pack 20 are connected to a condenser 6 outside the module housing 21 via the heat exchanger 24 within the module housing 21 and the above-mentioned heat exchanger 23. That is, the fuel electrode exhaust gas is supplied to the heat exchangers 23 and 24 as a heating medium (heat source) via the hydrogen circulation pipe L2, and the fuel electrode exhaust gas that has passed through the heat exchangers 23 and 24 of each water electrolysis module 2 is supplied to the condenser 6 via the hydrogen circulation pipe L2.

[0018] Further, an air supply pipe L3 forming an air supply passage is connected to the oxidant pole inlet of the water electrolysis cell group 20 of each water electrolysis module 2. The air supply pipes L3 from each water electrolysis cell group 20 are connected to the blower 5 outside the module housing 21 via the heat exchangers 24 and 25 inside the module housing 21. In addition, the oxidant pole outlet of the water electrolysis cell group 20 of each water electrolysis module 2 is connected to the burner 26 via an oxidant pole exhaust pipe L4 forming an oxidant pole exhaust gas passage. The oxidant pole exhaust gas containing oxygen from the oxidant poles 20c of each single cell flows into the burner 26 inside the module housing 21 via the oxidant pole exhaust pipe L4.

[0019] The burner 26 of each water electrolysis module 2 includes an ignition device (not shown) that burns a mixed gas of the oxidant pole exhaust gas from the oxidant pole exhaust pipe L4 and hydrogen supplied from the corresponding hydrogen booster 7 outside the module housing 21 via the hydrogen supply pipe (hydrogen supply passage) L5. The combustion exhaust gas generated by the combustion of the mixed gas in the burner 26 is supplied to the heat exchangers 22 and 25 as a heating medium via the exhaust pipe (exhaust passage) L6. The exhaust gas that has passed through the heat exchangers 22 and 25 is discharged to the outside of the housing 10 of the water electrolysis device 1 via the exhaust pipe L6. In addition, a flowmeter F7 for measuring the flow rate of hydrogen sent out from the hydrogen booster 7 is provided in the hydrogen supply pipe L5.

[0020] The power supply device 3 can be a device powered by at least any one of a system power supply and a renewable energy power generation device, etc., can be a storage battery, or can be a combination thereof. The power supply device 3 and the auxiliary machine A including a control device, etc. are arranged in the lower part inside the housing 10 so as to be located below each water electrolysis module 2 (refer to Figure 1 ).

[0021] The steam generator 4 vaporizes the raw water by a heat pump (not shown) or the like, and supplies the obtained water vapor to the fuel supply pipe L1 of each water electrolysis module 2. The water vapor from the steam generator 4 is heated by heat exchange with the combustion exhaust gas in the heat exchanger 23 inside the module housing 21 of each water electrolysis module 2, and then heated to the required temperature by heat exchange with the fuel pole exhaust gas in the heat exchanger 22. The heated water vapor is supplied to the fuel poles 20b of each single cell via the fuel supply pipe L1 and the fuel pole inlet of the water electrolysis cell group 20.

[0022] The blower 5 is arranged inside the housing 10 of the water electrolysis device 1, above the power supply device 3 and the auxiliary machine A, and outside the module housing 21 of each water electrolysis module 2 (refer to Figure 1)。The blower 5 sucks in the air inside the casing 10 of the water electrolysis device 1 via an air filter (not shown) and blows it out. The air from the blower 5 is heated by heat exchange with the combustion exhaust gas in the heat exchanger 25 inside the module casing 21 of each water electrolysis module 2, and then heated to the required temperature by heat exchange with the fuel electrode exhaust gas in the heat exchanger 24, and is supplied to the oxidant electrode 20c of each single cell via the air supply pipe L3 and the oxidant electrode inlet of the water electrolysis battery pack 20. Thus, the oxygen generated in the oxidant electrode 20c of each single cell can flow out to the oxidant electrode exhaust pipe L4 together with the air from the blower 5, i.e., the residual gas.

[0023] The condenser 6 is provided inside the casing 10 of the water electrolysis device 1, above the power supply device 3 and the auxiliary machine A, and outside the module casing 21 of each water electrolysis module 2 (see Figure 1 ). The condenser 6 cools the fuel electrode exhaust gas from the hydrogen flow pipe L2 with the cold water supplied from the outside of the casing 10 of the water electrolysis device 1, and condenses the water vapor contained in the fuel electrode exhaust gas (hydrogen generation). The condensed water generated in the condenser 6 is recovered (accumulated) in the water tank 9 inside the casing 10, and the condensed water in the water tank 9 is used as the raw water for water vapor in the steam generator 4. And, the fuel electrode exhaust gas separated into gas and liquid in the condenser 6, i.e., hydrogen, flows into a booster 11 such as a diaphragm type, piston type, or centrifugal type via the hydrogen flow pipe (hydrogen passage) L7, and is pumped into the hydrogen tank 12 by this booster 11. Thus, the hydrogen generated by each water electrolysis module 2 is accumulated in this hydrogen tank 12. As Figure 1 and Figure 2 shown, the booster 11 and the hydrogen tank 12 are provided outside the casing 10 of the water electrolysis device 1.

[0024] And, a recirculation pipe L8 forming a recirculation path branches out from the hydrogen flow pipe L7, and the inlets of the respective hydrogen superchargers 7 and 8 are connected to this recirculation pipe L8. Thus, each hydrogen supercharger 7 sucks in a part of the fuel electrode exhaust gas separated into gas and liquid in the condenser 6, i.e., hydrogen, via the recirculation pipe L8, and supplies this hydrogen to the burner 26 of the corresponding water electrolysis module 2 via the hydrogen supply pipe L5. In addition, each hydrogen supercharger 8 sucks in a part of the fuel electrode exhaust gas separated into gas and liquid in the condenser 6, i.e., hydrogen (hydrogen generation), and ejects this hydrogen into the corresponding fuel supply pipe L1 outside the module casing 21 of each water electrolysis module 2. That is, each hydrogen supercharger 8 mixes the hydrogen from the condenser 6 as an antioxidant with the water vapor supplied from the steam generator 4 to each fuel supply pipe L1. Thus, the fuel electrode 20b of each single cell of each water electrolysis battery pack 20 can be maintained in a reducing atmosphere and the oxidation of the catalyst metal can be well suppressed.

[0025] Each of the hydrogen superchargers 7 and 8 is also provided inside the casing 10 of the water electrolysis device 1, above the power supply device 3 and the auxiliary machine A, and outside the module casing 21 of each water electrolysis module 2 (refer to Figure 1 ). Further, a flowmeter F8 for measuring the flow rate of hydrogen sucked by the hydrogen supercharger 8 is provided upstream of the suction port of each hydrogen supercharger 8. In addition, the recirculation pipe L8 is connected to the hydrogen tank 12 outside the casing 10 via a pipe. Thus, at the start of each water electrolysis battery pack 20 or when each water electrolysis battery pack 20 operates as a fuel cell, the hydrogen stored in the hydrogen tank 12 can be supplied to the fuel electrode inlets of the water electrolysis battery packs 20 of each water electrolysis module 2 via the fuel supply pipe L1 by means of each hydrogen supercharger 8.

[0026] In addition, the casing 10 of the water electrolysis device 1 is formed of metal or the like, and an air suction port 13 for internal ventilation is formed at the lower part of the casing 10. The air suction port 13 communicates with the inside of the casing 10 via an air filter 14 provided on the inner bottom surface of the casing 10. Further, an exhaust duct 16 for partitioning the exhaust port 15 is fixed to the upper part of the side wall of the casing 10. An electric ventilation fan 17 is provided at the air inlet of the exhaust duct 16.

[0027] Thus, if the ventilation fan 17 is operated during the operation of the water electrolysis device 1, external air flows into the casing 10 via the air suction port 13 and the air filter 14. The air flowing into the casing 10 absorbs the heat released from each water electrolysis module 2, the power supply device 3, the auxiliary machine A, each blower 5, the condenser 6, each hydrogen supercharger 7 and 8, the fuel supply pipe L1, the hydrogen flow pipe L2, the exhaust pipe L6, etc., and is heated. Further, the air heated in the casing 10 is sucked into the exhaust duct 16 by the ventilation fan 17 and discharged to the outside via the exhaust port 15.

[0028] During the operation of the water electrolysis device 1, the temperature around the ventilation fan 17 in the casing 10 is sufficiently higher than the temperature (dew point temperature, for example, about 30 - 40 °C) of the fuel electrode exhaust gas, i.e., hydrogen, at the fuel electrode exhaust gas outlet of the condenser 6 (for example, about 50 - 55 °C). Accordingly, in the water electrolysis device 1, a part of the hydrogen flow pipe L7 forming the recirculation path and a part of the recirculation pipe L8 between the hydrogen flow pipe L7 and each hydrogen supercharger 7 and each flowmeter F8 are arranged in the casing 10 facing the air inlet of the ventilation fan 17 (exhaust duct 16). That is, a part of the hydrogen flow pipe L7 and a part of the recirculation pipe L8 form a heating section 18 for heating the fuel electrode exhaust gas, i.e., hydrogen, between the condenser 6 and each hydrogen supercharger 7 and each flowmeter F8. From Figure 1 it can be seen that the heating section 18 is closer to the exhaust port 15 than the air suction port 13 of the casing 10.

[0029] As described above, the water electrolysis apparatus 1 includes: a water electrolysis module 2 including a water electrolysis cell stack 20, hydrogen superchargers 7 and 8, hydrogen flow pipes L2 and L7, a recirculation pipe L8, a condenser 6, and a heating unit 18. The water electrolysis cell stack 20 includes a plurality of single cells that generate hydrogen at the fuel electrode 20b by electrolyzing water vapor and generate oxygen at the oxidant electrode 20c. In addition, the hydrogen supercharger 7 supplies hydrogen for combustion to the burner 26 of the water electrolysis module 2, and the hydrogen supercharger 8 supplies hydrogen for antioxidation to the fuel electrode 20b of each single cell of the water electrolysis cell stack 20. Further, the hydrogen flow pipes L2 and L7 and the recirculation pipe L8 form a recirculation path that supplies fuel electrode exhaust gas (hydrogen generated) containing hydrogen from the fuel electrode 20b of each single cell of the water electrolysis cell stack 20 to the suction port of the hydrogen supercharger 8. In addition, the condenser 6 condenses the water vapor contained in the fuel electrode exhaust gas flowing in the hydrogen flow pipe L2 or the like. Moreover, the heating unit 18 heats the fuel electrode exhaust gas (hydrogen generated) between the condenser 6 and the hydrogen superchargers 7 and 8 and the flow meters F7 and F8.

[0030] That is, in the water electrolysis apparatus 1, during the operation of the water electrolysis module 2, the fuel electrode exhaust gas containing hydrogen is supplied from the fuel electrode 20b of each single cell of the water electrolysis cell stack 20 to the hydrogen supercharger 7 (suction port), the flow meter F7, the flow meter F8, and the hydrogen supercharger 8 (suction port) via the hydrogen flow pipes L2 and L7 and the recirculation pipe L8. In addition, the water vapor contained in the fuel electrode exhaust gas flowing in the hydrogen flow pipe L2 is condensed in the condenser 6. Further, the fuel electrode exhaust gas (hydrogen generated) that has passed through the condenser 6 is heated by the heating unit 18 between the condenser 6 and the flow meter F8 and the hydrogen supercharger 8. Then, the hydrogen heated by the heating unit 18 is supplied to the burner 26 of the water electrolysis module 2 as hydrogen for combustion by the hydrogen supercharger 7, and is supplied to the fuel electrode 20b of each single cell of the water electrolysis cell stack 20 as hydrogen for antioxidation by the hydrogen supercharger 8.

[0031] As a result, the fuel electrode exhaust gas (hydrogen generated) below the dew point temperature is not supplied from the recirculation pipe L8 to the hydrogen supercharger 7 and the flow meter F7, and condensation of water vapor in the recirculation pipe L8, the hydrogen supercharger 7, and the flow meter F7 can be suppressed. In addition, the fuel electrode exhaust gas (hydrogen generated) below the dew point temperature is not supplied from the recirculation pipe L8 to the flow meter F8 and the hydrogen supercharger 8, and condensation of water vapor in the flow meter F8 and the hydrogen supercharger 8 can be suppressed. As a result, in the water electrolysis apparatus 1, degradation of the performance of the hydrogen superchargers 7 and 8 and the flow meters F7 and F8 that recirculate the hydrogen generated at the fuel electrode 20b of each single cell of the water electrolysis cell stack 20 in the water electrolysis module 2, that is, the water electrolysis cell stack 20 or the burner 26 of the water electrolysis module 2, can be favorably suppressed.

[0032] In addition, the water electrolysis device 1 includes a housing 10 that houses a water electrolysis module 2 (water electrolysis battery pack 20), hydrogen superchargers 7 and 8, hydrogen flow pipes L2 and L7, a recirculation pipe L8, a condenser 6, etc. The heating section 18 is formed by a part of the hydrogen flow pipe L7 and a part of the recirculation pipe L8 in the area around the ventilation fan 17 inside the housing 10 where the temperature is higher than the dew point temperature of the fuel electrode exhaust gas (hydrogen generated) at the outlet of the condenser 6. Thereby, the heat released into the interior of the housing 10 during the water vapor electrolysis performed in the water electrolysis battery pack 20 can be effectively utilized to heat the fuel electrode exhaust gas (hydrogen generated) supplied from the condenser 6 to the hydrogen superchargers 7 and 8, etc. As a result, it is possible to favorably suppress an increase in the cost and power consumption of the water electrolysis device 1 without the need for additional installation of a heater or the like.

[0033] Moreover, the housing 10 of the water electrolysis device 1 includes an air intake 13 for sucking air into the interior and an exhaust duct 16 that forms an exhaust port 15 for discharging the air inside to the outside. The heating section 18 is arranged inside the housing 10 so as to be closer to the exhaust port 15 than the air intake 13. Thereby, the fuel electrode exhaust gas (hydrogen generated) supplied from the condenser 6 to the hydrogen superchargers 7 and 8, etc. can be favorably heated by the air that has absorbed the heat inside the housing 10.

[0034] In addition, the water electrolysis device 1 includes a ventilation fan 17 that sends the air inside the housing 10 to the exhaust port 15. The air intake 13 is arranged at the lower part of the housing 10, and the exhaust port 15 is arranged at the upper part of the housing 10. Moreover, the heating section 18 is arranged inside the housing 10 so as to face the air inlet of the ventilation fan 17. Thereby, the air that has absorbed the heat inside the housing 10 can be efficiently collected in the heating section 18, and the fuel electrode exhaust gas (hydrogen generated) supplied from the condenser 6 to the hydrogen superchargers 7 and 8, etc. can be favorably heated.

[0035] Furthermore, the invention of the present disclosure is in no way limited to the above-described embodiments, and various modifications can of course be made within the scope of the present disclosure. And the above-described embodiments are merely a specific mode of the invention described in the summary section of the invention, and do not limit the elements of the invention described in the summary section of the invention.

[0036] Industrial Applicability

[0037] The invention of the present disclosure can be utilized in the manufacturing industry of water electrolysis devices, etc.

Claims

1. A water electrolysis device is a water electrolysis device including a water electrolysis module that generates hydrogen by electrolyzing water vapor, and includes: A supercharger for supplying hydrogen to the water electrolysis module; A recirculation passage that supplies the generated hydrogen generated by the water electrolysis module from the water electrolysis module to the suction port of the supercharger; A condenser that condenses the water vapor contained in the generated hydrogen; and A heating unit that heats up the generated hydrogen between the condenser and the supercharger.

2. The water electrolysis device according to claim 1, wherein It further includes a housing that houses the water electrolysis module, the supercharger, the recirculation passage, and the condenser, The heating unit is formed by a part of the recirculation passage disposed in a region inside the housing where the temperature is higher than the dew point temperature of the generated hydrogen at the outlet of the condenser.

3. The water electrolysis device according to claim 2, wherein The housing includes an air suction port for sucking air into the interior and an exhaust port for discharging the air inside to the outside, The heating unit is disposed inside the housing so as to be closer to the exhaust port than the air suction port.

4. The water electrolysis device according to claim 3, wherein It further includes a ventilation fan that sends the air inside the housing to the exhaust port, The air suction port is disposed at the lower part of the housing, The exhaust port is disposed at the upper part of the housing, The heating unit is disposed inside the housing so as to face the air inlet of the ventilation fan.

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