Hydrogen production plant and hydrogen production method

Abstract

To provide a hydrogen production plant capable of improving safety.SOLUTION: A hydrogen production plant 1 comprises a solid oxide electrolysis cell (SOEC) 10 that produces a hydrogen-containing gas, and a discharge stack 30 into which the hydrogen-containing gas produced by the SOEC 10 is introduced and which discharges the introduced hydrogen-containing gas into the atmosphere. The discharge stack 30 has a spray section 32 that supplies cooling water to cool the hydrogen-containing gas introduced therein.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a hydrogen production plant and a hydrogen production method.

Background Art

[0002] In recent years, hydrogen has been used in various applications in the context of carbon neutrality. Therefore, facilities for producing hydrogen are known (for example, Patent Document 1).

[0003] Patent Document 1 describes a dehumidifying device including a mixed gas generating unit that generates a mixed gas of oxygen-hydrogen gas and liquefied petroleum gas, and a dehumidifying unit that reduces the humidity of the mixed gas generated by the mixed gas generating unit. The mixed gas generating unit described in Patent Document 1 includes an electrolytic cell or the like that generates oxygen-hydrogen gas by electrolysis. The dehumidifying unit includes a gas-liquid contact tank that removes moisture contained in the mixed gas by gas-liquid contact, and a cooler that cools the liquid brought into contact with the mixed gas in the gas-liquid contact tank.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In facilities for producing hydrogen, hydrogen may be released into the atmosphere during startup or emergency shutdown of the facility. Therefore, it is considered to provide a hydrogen production facility with a discharge unit for discharging hydrogen into the atmosphere. Since hydrogen may self-ignite when it reaches a high temperature, it is required to improve safety even in the discharge unit for discharging hydrogen into the atmosphere. However, the dehumidifying device described in Patent Document 1 does not include a discharge unit for discharging the generated hydrogen-containing gas into the atmosphere, and Patent Document 1 does not consider the safety of a device having a discharge unit.

[0006] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a hydrogen production plant and a hydrogen production method capable of improving safety.

Means for Solving the Problems

[0007] In order to solve the above problems, the hydrogen production plant and the hydrogen production method of the present disclosure employ the following means. A hydrogen production plant according to an aspect of the present disclosure includes a production unit that produces a hydrogen-containing gas, and a discharge unit into which the hydrogen-containing gas produced by the production unit is introduced and that discharges the introduced hydrogen-containing gas to the atmosphere, and the discharge unit has a cooling fluid supply unit that supplies a cooling fluid for cooling the hydrogen-containing gas to the introduced hydrogen-containing gas.

[0008] Further, a hydrogen production method according to an aspect of the present disclosure includes a production step of producing a hydrogen-containing gas, an introduction step of introducing the hydrogen-containing gas produced in the production step into the discharge unit, a supply step of supplying a cooling fluid to the hydrogen-containing gas introduced into the discharge unit, and a discharge step of discharging the hydrogen-containing gas introduced into the discharge unit to the atmosphere.

Advantages of the Invention

[0009] According to the present disclosure, the safety of the hydrogen production plant can be improved.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0011] Hereinafter, an embodiment of a hydrogen production plant and a hydrogen production method according to the present disclosure will be described with reference to the drawings. The hydrogen production plant 1 according to this embodiment is a plant that produces hydrogen during normal operation. Further, the hydrogen production plant 1 may release a hydrogen-containing gas into the atmosphere during startup or emergency shutdown.

[0012] As shown in FIG. 1, the hydrogen production plant 1 includes an SOEC device (hereinafter referred to as SOEC10) that produces a hydrogen-containing gas using a solid oxide electrolysis cell (SOEC), an instrumentation air supply unit 11 that supplies instrumentation air to the SOEC10, a city gas supply unit 12 that supplies city gas to the SOEC10, a hydrogen gas supply unit 13 that supplies hydrogen gas to the SOEC10, a nitrogen gas supply unit 14 that supplies nitrogen gas to the SOEC, a makeup water supply unit 15 that supplies makeup water to an electric boiler (steam generation unit) 17, an electrolysis air supply unit 16 that supplies electrolysis air (electrolysis gas) to the SOEC10, an electric boiler 17 that heats the makeup water and generates steam to be supplied to the SOEC10, and a heat exchanger 18 that performs heat exchange between the electrolysis air supplied to the SOEC10 and the electrolysis air (exhaust air) discharged from the SOEC10.

[0013] The SOEC (production unit) 10 is supplied with high-temperature and high-pressure electrolysis gas (in this embodiment, air as an example) and high-temperature and high-pressure steam. The electrolysis gas and steam supplied to the SOEC10 are led into an electrolysis chamber where the electrolysis cell is housed. The SOEC10 electrolyzes steam using a high-temperature solid electrolyte in the electrolysis chamber to generate a hydrogen-containing gas (a mixed gas of hydrogen and steam) and oxygen. The generated hydrogen-containing gas is discharged to the outside through a hydrogen-containing gas pipe L4. Further, the generated oxygen is discharged to the outside together with the exhaust air. For the SOEC, for example, ceramics such as yttria-stabilized zirconia are used as the electrolyte. Since high-temperature steam is used as a raw material, hydrogen can be produced with high efficiency compared to other water electrolysis devices. In addition, co-electrolysis is also possible, in which carbon dioxide (CO2) is used as a raw material and electrolytic hydrogen is used as a reducing agent to produce carbon monoxide (CO).

[0014] The instrumentation air supply unit 11 supplies air (instrumentation air) used for driving a control valve (not shown) provided in the SOEC 10 to the SOEC 10. The city gas supply unit 12 supplies city gas for heating up the SOEC 10 when starting up the SOEC 10 to the SOEC 10. The hydrogen gas supply unit 13 supplies hydrogen gas for making the electrolytic cell into a reducing atmosphere to the SOEC 10 when starting up the SOEC 10. The nitrogen gas supply unit 14 supplies nitrogen gas for purging oxygen and air remaining in the SOEC 10 to the SOEC 10 when starting up the SOEC 10.

[0015] Moreover, the hydrogen production plant 1 includes a nitrogen pipe (first nitrogen pipe) L1 connecting the nitrogen gas supply unit 14 and the SOEC 10, a makeup water pipe L2 connecting the makeup water supply unit 15 and the electric boiler 17, and a steam pipe (first steam pipe) L3 connecting the electric boiler 17 and the SOEC 10. The nitrogen pipe L1 guides the nitrogen gas supplied from the nitrogen gas supply unit 14 to the SOEC 10. The makeup water pipe L2 guides the makeup water supplied from the makeup water supply unit 15 to the electric boiler 17. The steam pipe L3 guides the steam generated by the electric boiler 17 to the SOEC 10. A first steam valve B1 is provided in the steam pipe L3. The first steam valve B1 is, for example, an electromagnetic valve.

[0016] Moreover, the hydrogen production plant 1 includes a hydrogen generation unit 20 that generates product gas (hydrogen) from the hydrogen-containing gas produced by the SOEC 10, and a discharge stack (discharge unit) 30 into which the hydrogen-containing gas produced by the SOEC 10 is introduced and the introduced hydrogen-containing gas is discharged to the atmosphere.

[0017] In addition, the hydrogen production plant 1 includes a hydrogen-containing gas pipe L4 connecting the SOEC 10 and the emission stack 30, a branched nitrogen pipe (second nitrogen pipe) L5 branched from the nitrogen pipe L1, a branched makeup water pipe L6 branched from the makeup water pipe L2, a branched steam pipe L7 branched from the steam pipe L3, and a branched hydrogen-containing gas pipe L8 branched from the hydrogen-containing gas pipe L4. The hydrogen-containing gas pipe L4 guides the hydrogen-containing gas produced by the SOEC 10 to the emission stack 30. The branched nitrogen pipe L5 connects the nitrogen pipe L1 and the emission stack 30 and guides a part of the nitrogen gas flowing through the nitrogen pipe L1 to the emission stack 30. The branched makeup water pipe L6 connects the makeup water pipe L2 and the emission stack 30 and guides a part of the makeup water flowing through the makeup water pipe L2 to the emission stack 30. The branched steam pipe (second steam pipe) L7 connects the steam pipe L3 and the emission stack 30 and guides part or all of the steam flowing through the steam pipe L3 to the emission stack 30. The branched hydrogen-containing gas pipe L8 guides part or all of the hydrogen-containing gas flowing through the hydrogen-containing gas pipe L4 to the hydrogen generation unit 20.

[0018] A first hydrogen-containing gas valve B2 is provided in the hydrogen-containing gas pipe L4. A nitrogen valve B3 is provided in the branched nitrogen pipe L5. A second steam valve B4 is provided in the branched steam pipe L7. A second hydrogen-containing gas valve B5 is provided in the branched hydrogen-containing gas pipe L8. The first hydrogen-containing gas valve B2, the nitrogen valve B3, the second steam valve B4, and the second hydrogen-containing gas valve B5 are each, for example, electromagnetic valves. A cooling water valve (cooling fluid regulating unit) B6 is provided in the branched makeup water pipe L6. The cooling water valve B6 is, for example, a flow control valve. The cooling water valve B6 regulates the amount of cooling water supplied from a spray unit (cooling fluid supply unit) 32 described later.

[0019] The hydrogen generation unit 20 includes a cooler 21 into which the hydrogen-containing gas is introduced via the branched hydrogen-containing gas pipe L8, a dehumidifier 22 into which the hydrogen-containing gas discharged from the cooler 21 is introduced, and a compressor 23 into which the hydrogen-containing gas discharged from the dehumidifier 22 is introduced.

[0020] The cooler 21 condenses water vapor by cooling the hydrogen-containing gas. Thereby, the cooler 21 separates hydrogen and water vapor. Further, the dehumidifier 22 dehumidifies the hydrogen-containing gas cooled by the cooler 21. Also, the compressor 23 boosts the pressure of the hydrogen-containing gas dehumidified by the dehumidifier 22. In this way, the hydrogen generation unit 20 separates water vapor from the hydrogen-containing gas and generates a product gas (hydrogen).

[0021] The discharge stack 30 includes a housing 31 that forms an outer shell, a spray unit (cooling fluid supply unit) 32 provided inside the housing 31, a storage unit 33 provided at the lower part inside the housing 31, a seal unit 34 provided at the upper part inside the housing 31, and a discharge unit 35 that discharges the condensed water stored in the storage unit 33.

[0022] The housing 31 has a space formed inside. The housing 31 has a cylindrical large-diameter portion 31a and a cylindrical small-diameter portion 31b connected to the upper part of the large-diameter portion 31a. The large-diameter portion 31a has a larger diameter than the small-diameter portion 31b. The downstream ends of the hydrogen-containing gas pipe L4 and the branched nitrogen pipe L5 are connected to the large-diameter portion 31a. A discharge opening 31c that opens toward the atmosphere is formed at the upper end of the small-diameter portion 31b. The hydrogen-containing gas introduced into the housing 31 is discharged to the atmosphere through the discharge opening 31c.

[0023] The spray section 32 is inside the large-diameter section 31a and is provided at the upper part of the large-diameter section 31a. The spray section 32 has, for example, a spray pipe extending in the horizontal direction and a plurality of nozzles provided on the lower surface of the spray pipe. The plurality of nozzles are arranged at equal intervals along the extending direction of the spray pipe. The downstream end of the branched makeup water pipe L6 is connected to the spray pipe. Makeup water is supplied to the spray pipe as cooling water for cooling the hydrogen-containing gas via the branched makeup water pipe L6. The spray section 32 injects the cooling water (cooling fluid) supplied to the spray pipe downward from the plurality of nozzles. Specifically, the spray section 32 injects the cooling water against the hydrogen-containing gas supplied into the housing 31. Thereby, the hydrogen-containing gas is cooled. Note that the cooling water that has not evaporated among the injected cooling water drips down to the lower part of the housing 31.

[0024] The storage section 33 is provided at the lower part of the housing 31. The storage section 33 stores the cooling water that has not evaporated among the injected cooling water.

[0025] The seal section 34 suppresses the inflow (backflow) of the atmosphere from the discharge opening 31c by using the gas supplied into the discharge stack 30.

[0026] The seal section 34 uses the hydrogen-containing gas introduced into the discharge stack 30 via the hydrogen-containing gas pipe L4 as a seal gas. That is, the hydrogen-containing gas introduced into the discharge stack 30 rises in the discharge stack 30. Thereby, the hydrogen-containing gas repels the atmosphere (especially oxygen) that tries to flow into the discharge stack 30 from the discharge opening 31c. In this way, the hydrogen-containing gas is used as a seal gas.

[0027] Further, the seal portion 34 may be provided with, for example, a so-called velocity seal. The seal portion 34 has a reduced-diameter portion 34a provided inside the small-diameter portion 31b. The reduced-diameter portion 34a is a frustum-shaped member having openings formed at the upper end and the lower end. The entire circumferential direction of the lower end of the reduced-diameter portion 34a is in contact with the inner peripheral surface of the small-diameter portion 31b. The side wall of the reduced-diameter portion 34a is inclined so that the diameter becomes smaller as it goes upward. The hydrogen-containing gas introduced into the discharge stack 30 rises in the discharge stack 30 and passes through the reduced-diameter portion 34a from the lower side to the upper side.

[0028] In this way, by using the gas supplied from the SOEC 10 into the discharge stack 30, oxygen is prevented from flowing into the discharge stack 30 from the atmosphere through the discharge opening 31c.

[0029] Note that the electric boiler 17 generates steam even before the start of electrolysis and during electrolysis (during normal operation), such as at startup. Therefore, before the start of electrolysis of the SOEC 10, the steam can be used as the stack seal gas. Note that when steam or hydrogen cannot be supplied or is insufficient in the discharge stack 30, such as during an emergency stop of the SOEC 10 and the electric boiler 17, nitrogen supplied through the branch nitrogen pipe L5 may be used as the seal gas. Also, when the amount of seal gas discharged from the SOEC 10 is insufficient, a part of the steam supplied from the electric boiler 17 to the SOEC 10 may be supplied to the stack through the branch steam pipe L7. Also, an oxygen concentration meter may be installed inside the discharge stack 30 to measure the oxygen concentration inside the discharge stack 30 and monitor whether oxygen is flowing into the discharge stack 30 from the atmosphere.

[0030] The discharge portion 35 discharges the water stored in the storage portion 33 to a drain pit 41 provided outside the system. The discharge portion 35 has a U-shaped pipe 35a formed in a U shape. One end of the U-shaped pipe 35a is connected to the housing 31 (storage portion 33) through a horizontal pipe. The other end of the U-shaped pipe 35a is connected to the drain pit 41 through a horizontal pipe. Further, the inside of the U-shaped pipe 35a is filled with a liquid (raw water). This seals the U-shaped pipe 35a so that air does not flow into the discharge stack 30 or hydrogen in the discharge stack 30 does not flow out to the outside via the discharge section 35.

[0031] Also, since the raw water may evaporate inside the U-shaped pipe 35a, a constant amount of raw water is constantly supplied to the U-shaped pipe 35a from the raw water supply section 40. This suppresses a decrease in sealing performance due to excessive reduction of the raw water filled in the U-shaped pipe 35a. A level gauge for detecting the liquid level of the raw water inside the U-shaped pipe 35a may be provided to monitor the liquid level.

[0032] Also, as shown in FIG. 2, the hydrogen production plant 1 includes a thermometer (temperature detection section) 51 that measures the temperature of the hydrogen-containing gas after being cooled by the spray section 32, and a level gauge (level detection section) 52 that detects the liquid level of the water stored in the storage section 33. Also, as shown in FIG. 2, the hydrogen production plant 1 includes a control unit 50. The control unit 50 controls the opening degrees of the respective valves provided in the hydrogen production plant 1. The control unit 50 also acquires information from the thermometer 51 and the level gauge 52.

[0033] The control unit 50 includes, for example, a CPU (Central Processing Unit: processor), a main memory device, a secondary storage device (Secondary storage: memory), etc. Further, the control unit 50 may include a communication unit for transmitting and receiving information to and from other devices. The main memory device is composed of a writable memory such as a cache memory, a RAM (Random Access Memory), etc., and is used as a work area for reading the execution program of the CPU, writing processing data by the execution program, etc. The secondary storage device is a non-transitory computer readable storage medium. The secondary storage device is, for example, a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. As an example, a series of processes for realizing various functions are stored in the secondary storage device in the form of a program. The CPU reads this program into the main storage device and executes information processing and arithmetic operations, thereby realizing various functions. Note that the program may be applied in a form pre-installed in the secondary storage device, a form provided in a state stored in a computer-readable storage medium, a form distributed via wired or wireless communication means, or the like. The computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

[0034] The control unit 50 controls the opening degree of the cooling water valve B6 based on the temperature of the hydrogen-containing gas detected by the thermometer 51. That is, the control unit 50 adjusts the amount of cooling water supplied from the spray unit 32 based on the temperature of the hydrogen-containing gas detected by the thermometer 51. Specifically, when the temperature of the hydrogen-containing gas detected by the thermometer 51 is higher than a predetermined temperature (for example, about 400 ° C), the control unit 50 may increase the opening degree of the cooling water valve B6 so that the amount of cooling water increases. When the temperature of the hydrogen-containing gas detected by the thermometer 51 is lower than the predetermined temperature, the control unit 50 may decrease the opening degree of the cooling water valve B6 so that the amount of cooling water decreases.

[0035] Further, the control unit 50 may control the opening degree of the cooling water valve B6 based on the liquid level detected by the level meter 52. That is, the control unit 50 may adjust the amount of cooling water supplied from the spray unit 32 based on the liquid level detected by the level meter 52. Specifically, when the liquid level detected by the level gauge 52 is lower than a predetermined level, the control unit 50 may control the cooling water valve B6 so that the amount of cooling water increases, and when the liquid level detected by the level gauge 52 is higher than a predetermined level, the control unit 50 may control the cooling water valve B6 so that the amount of cooling water decreases.

[0036] Note that the method for adjusting the amount of cooling water performed by the control unit 50 includes a method of adjusting the flow rate of the cooling water supplied from the spray unit 32 using a control valve (not shown) and a method of switching the flow of water (on) and stop (off) to the spray unit 32 by opening and closing the cooling water valve B6.

[0037] Next, the behavior of the hydrogen production plant 1 during normal operation, startup, and emergency stop will be described.

[0038] [During normal operation] During normal operation, the hydrogen production plant 1 generates hydrogen, which is the product gas, in the hydrogen generation unit 20. That is, the hydrogen production plant 1 supplies the hydrogen-containing gas generated by the SOEC 10 to the hydrogen generation unit 20 via the branched hydrogen-containing gas pipe L8. At this time, the control unit 50 fully closes the first hydrogen-containing gas valve B2 and fully opens the second hydrogen-containing gas valve B5. Further, the control unit 50 fully opens the first steam valve B1 and fully closes the nitrogen valve B3 and the second steam valve B4.

[0039] [During startup or emergency stop] During startup or emergency stop, the hydrogen production plant 1 discharges the hydrogen-containing gas to the atmosphere. That is, the hydrogen production plant 1 supplies the hydrogen-containing gas generated by the SOEC 10 to the discharge stack 30 via the hydrogen-containing gas pipe L4. At this time, the control unit 50 fully opens the first hydrogen-containing gas valve B2 and fully closes the second hydrogen-containing gas valve B5. Further, the control unit 50 opens the second steam valve B4. In addition, if an accident occurs in the hydrogen production plant 1 and cooling water is not supplied to the spray section 32 of the discharge stack 30, or if sealing steam is not supplied to or is insufficient in the discharge stack 30, the control unit 50 may fully open the nitrogen valve B3. With the nitrogen valve B3 fully open, nitrogen gas may be supplied to the discharge stack 30, and the nitrogen gas may be used to substitute for the cooling water and the sealing steam.

[0040] As an operation during startup, after the electrolysis chamber temperature of the SOEC 10 reaches a certain value or higher, steam is introduced and an electrolysis voltage is applied to start electrolysis to generate hydrogen. After hydrogen is generated, when the operation of the device stabilizes, the hydrogen-containing gas is switched to be introduced into the product gas system (hydrogen generation section 20). In addition, examples of emergency stops include when the SOEC 10 stops due to an interlock or when the equipment to which the product gas is supplied malfunctions. In such cases, the hydrogen-containing gas is switched to be led to the discharge stack 30.

[0041] According to the present embodiment, the following operational effects are achieved. In the present embodiment, the discharge stack 30 has a spray section 32 that supplies cooling water for cooling the hydrogen-containing gas introduced therein to the hydrogen-containing gas. Thereby, the hydrogen-containing gas supplied to the inside of the discharge stack 30 can be cooled. Therefore, it is possible to suppress a situation where the hydrogen-containing gas spontaneously ignites when released into the atmosphere. Thus, the safety of the hydrogen production plant 1 can be improved.

[0042] In the present embodiment, the discharge stack 30 has a seal section 34 that suppresses the inflow of air from the discharge opening 31c. Thereby, the seal section 34 can suppress a situation where air flows into the inside of the discharge stack 30 through the discharge opening 31c. Therefore, inside the discharge stack 30, combustion of the hydrogen-containing gas can be avoided. Thus, the safety of the hydrogen production plant 1 can be improved.

[0043] In addition, in the present embodiment, the inflow of air is suppressed by using the steam generated by the electric boiler 17. As a result, the number of components can be reduced as compared with the case where a device for supplying a gas for suppressing the inflow of air separately to the discharge stack 30 is provided. Therefore, the cost can be reduced. In addition, space saving can be achieved.

[0044] In addition, in the present embodiment, a control unit 50 is provided that controls the cooling water valve B6 based on the temperature of the hydrogen-containing gas detected by the thermometer 51. As a result, the amount of cooling water can be adjusted based on the temperature of the hydrogen-containing gas after being cooled by the spray unit 32. Therefore, when the control unit 50 controls the cooling water valve B6 so that the temperature of the hydrogen-containing gas falls within a predetermined temperature range, the temperature of the hydrogen-containing gas can be set within the predetermined temperature range. Thus, the situation where the hydrogen-containing gas spontaneously ignites when released into the atmosphere can be more suitably suppressed. Therefore, the safety of the hydrogen production plant 1 can be improved.

[0045] In addition, in the present embodiment, a control unit 50 is provided that controls the cooling water valve B6 based on the liquid level detected by the level gauge 52. As a result, the amount of cooling water can be adjusted based on the liquid level of the water stored in the storage unit 33. Since the liquid level changes according to the amount of stored water, the amount of stored water can be estimated by detecting the liquid level.

[0046] In addition, in the present embodiment, a branch nitrogen pipe L5 is provided that guides the nitrogen gas from the nitrogen gas supply unit 14 to the discharge stack 30. As a result, nitrogen gas can be supplied to the discharge stack 30. Therefore, for example, when the spray unit 32 makes an emergency stop and cooling water cannot be supplied to the hydrogen-containing gas, the hydrogen-containing gas can be cooled by nitrogen gas by supplying nitrogen gas to the discharge stack 30. Thus, even when the spray unit 32 makes an emergency stop, the hydrogen-containing gas can be cooled, so that the situation where the hydrogen-containing gas spontaneously ignites when released into the atmosphere can be suppressed. Therefore, the safety of the hydrogen production plant 1 can be improved.

[0047] Also, in the present embodiment, nitrogen is supplied to the release stack 30 by a nitrogen gas supply unit 14 that supplies nitrogen to the SOEC 10. That is, nitrogen is supplied to both the SOEC 10 and the release stack 30 from the same device (nitrogen gas supply unit 14). Thereby, the number of components can be reduced as compared with the case where a device for separately supplying nitrogen to the release stack 30 is provided. Therefore, the cost can be reduced. Also, space saving can be achieved.

[0048] Also, in the present embodiment, the discharge unit 35 has a U shape and has a U-shaped pipe 35a filled with liquid inside. Thereby, the inside of the discharge unit 35 is sealed from the inside to the outside of the release stack 30 by the liquid filled therein. Therefore, it is possible to suppress a situation where air flows into the inside of the release stack 30 through the discharge unit 35. Thus, combustion of the hydrogen-containing gas can be avoided inside the release stack 30. Also, it is possible to avoid a situation where the hydrogen-containing gas in the release stack 30 leaks into the atmosphere and burns. Therefore, the safety of the hydrogen production plant 1 can be improved.

[0049] Note that the present disclosure is not limited to the above-described embodiment, and can be appropriately modified without departing from the gist thereof. For example, in the above embodiment, an example in which a velocity seal is provided as the seal portion 34 in the release stack 30 has been described, but the present disclosure is not limited thereto. For example, a molecular seal may be provided as the seal portion 34 in the release stack 30. Also, when sufficient sealing can be ensured by the gas supplied into the release stack 30, a sealing mechanism such as a reduced diameter portion 34a (velocity seal) may not be provided.

[0050] Also, in the above embodiment, an example in which the SOEC 10 is applied as a device for producing a hydrogen-containing gas has been described, but the present disclosure is not limited thereto. The device for producing a hydrogen-containing gas may be any device that electrolyzes water at a high temperature.

[0051] The hydrogen production plant and the hydrogen production method described in the above-described embodiments can be understood as follows, for example. The hydrogen production plant according to the first aspect of the present disclosure includes a production unit (10) that produces a hydrogen-containing gas, and a discharge unit (30) into which the hydrogen-containing gas produced by the production unit (10) is introduced and that discharges the introduced hydrogen-containing gas to the atmosphere. The discharge unit (30) has a cooling fluid supply unit (32) that supplies a cooling fluid for cooling the hydrogen-containing gas to the hydrogen-containing gas introduced therein.

[0052] In the above configuration, the discharge unit has a cooling fluid supply unit that supplies a cooling fluid for cooling the hydrogen-containing gas to the hydrogen-containing gas introduced therein. Thereby, the hydrogen-containing gas supplied to the inside of the discharge unit can be cooled. Therefore, it is possible to suppress a situation in which spontaneous ignition occurs when the hydrogen-containing gas is discharged to the atmosphere. Thus, the safety of the hydrogen production plant can be improved.

[0053] Further, the hydrogen production plant according to the second aspect of the present disclosure, in the above first aspect, includes a steam generation unit (17) that generates steam to be supplied to the production unit (10), a first steam pipe (L3) that guides the steam generated by the steam generation unit (17) to the production unit (10), and a second steam pipe (L7) that guides the steam generated by the steam generation unit (17) to the discharge unit (30). The discharge unit (30) has a discharge opening (31c) that opens toward the atmosphere, and a seal unit that suppresses the inflow of the atmosphere from the discharge opening (31c) by using the steam supplied through the second steam pipe (L7).

[0054] In the above configuration, the discharge unit has a seal unit that suppresses the inflow of the atmosphere, particularly oxygen, from the discharge opening. Thereby, the seal unit can suppress a situation in which the atmosphere, particularly oxygen, flows into the inside of the discharge unit through the discharge opening. Therefore, combustion of the hydrogen-containing gas can be avoided inside the discharge unit. Thus, the safety of the hydrogen production plant can be improved. Further, in the above configuration, the steam generated in the steam generation unit is used to suppress the inflow of the atmosphere, particularly oxygen. As a result, the number of components can be reduced as compared with the case where a device for supplying a gas for suppressing the inflow of the atmosphere, particularly oxygen, to the discharge unit is separately provided. Therefore, the cost can be reduced. Further, space saving can be achieved.

[0055] Further, in the hydrogen production plant according to the third aspect of the present disclosure, in the first aspect or the second aspect, the discharge unit (30) includes a cooling fluid adjustment unit (B6) that adjusts the amount of the cooling fluid supplied from the cooling fluid supply unit (32), and a temperature detection unit (51) that detects the temperature of the hydrogen-containing gas cooled by the cooling fluid, and includes a control unit (50) that controls the cooling fluid adjustment unit (B6) based on the temperature of the hydrogen-containing gas detected by the temperature detection unit (51).

[0056] In the above configuration, a control unit that controls the cooling fluid adjustment unit based on the temperature of the hydrogen-containing gas detected by the temperature detection unit is provided. Thereby, the amount of the cooling fluid can be adjusted based on the temperature of the hydrogen-containing gas cooled by the cooling fluid supply unit. Therefore, when the control unit controls the cooling fluid adjustment unit so that the temperature of the hydrogen-containing gas falls within a predetermined temperature range, the temperature of the hydrogen-containing gas can be set within the predetermined temperature range. Thus, a situation where the hydrogen-containing gas spontaneously ignites when discharged to the atmosphere can be more preferably suppressed. Thus, the safety of the hydrogen production plant can be improved.

[0057] Note that the control unit may control the cooling fluid adjustment unit so that the amount of the cooling fluid increases when the temperature of the hydrogen-containing gas detected by the temperature detection unit is higher than a predetermined temperature range, and may control the cooling fluid adjustment unit so that the amount of the cooling fluid decreases when the temperature of the hydrogen-containing gas detected by the temperature detection unit is lower than the predetermined temperature range. Note that the method for adjusting the amount of the cooling fluid performed by the control unit includes a method of adjusting the amount of the cooling fluid supplied from the cooling fluid supply unit and a method of switching between on and off of the cooling fluid supply unit.

[0058] Further, in the hydrogen production plant according to the fourth aspect of the present disclosure, in the first aspect or the second aspect, the discharge unit (30) includes a cooling fluid adjustment unit (B6) that adjusts the amount of the cooling fluid supplied from the cooling fluid supply unit (32), a storage unit (33) that stores condensed water generated by condensation of the hydrogen-containing gas, and a level detection unit (52) that detects the liquid level of the condensed water stored in the storage unit (33), and includes a control unit (50) that controls the cooling fluid adjustment unit (B6) based on the liquid level detected by the level detection unit (52).

[0059] In the above configuration, a control unit that controls the cooling fluid adjustment unit based on the liquid level detected by the level detection unit is provided. Thereby, the amount of the cooling fluid can be adjusted based on the liquid level of the water stored in the storage unit. Since the liquid level changes according to the amount of the stored water, the amount of the stored water can be estimated by detecting the liquid level.

[0060] Note that the control unit may control the cooling fluid adjustment unit so that the amount of the cooling fluid increases when the liquid level detected by the level detection unit is lower than a predetermined level, and may control the cooling fluid adjustment unit so that the amount of the cooling fluid decreases when the liquid level detected by the level detection unit is higher than the predetermined level.

[0061] Further, in the hydrogen production plant according to the fifth aspect of the present disclosure, in any one of the first aspect to the fourth aspect, a first nitrogen pipe (L1) that guides nitrogen gas from the nitrogen supply unit (14) to the production unit (10) and a second nitrogen pipe (L5) that guides nitrogen gas from the nitrogen supply unit (14) to the discharge unit (30) are provided.

[0062] In the above configuration, a second nitrogen pipe is provided to guide nitrogen gas from the nitrogen supply unit to the discharge unit. As a result, nitrogen gas can be supplied to the discharge unit. Therefore, for example, when the cooling fluid supply unit suddenly stops and cooling fluid cannot be supplied to the hydrogen-containing gas, the hydrogen-containing gas can be cooled by nitrogen gas by supplying nitrogen gas to the discharge unit. Thus, even when the cooling fluid supply unit suddenly stops, the hydrogen-containing gas can be cooled, so that the situation where the hydrogen-containing gas spontaneously ignites when released into the atmosphere can be suppressed. Therefore, the safety of the hydrogen production plant can be improved.

[0063] Also, in the above configuration, nitrogen is supplied to the discharge unit by the nitrogen supply unit that supplies nitrogen to the production unit. That is, nitrogen is supplied to both the production unit and the discharge unit from the same device (nitrogen supply unit). As a result, the number of parts can be reduced as compared with the case of separately providing a device for supplying nitrogen to the discharge unit. Therefore, the cost can be reduced. In addition, space saving can be achieved.

[0064] Further, in the hydrogen production plant according to the sixth aspect of the present disclosure, in any one of the first aspect to the fifth aspect, the discharge unit (30) includes a storage unit (33) that stores condensed water generated by condensation of a part of the hydrogen-containing gas, and a discharge unit (35) that discharges the condensed water stored in the storage unit (33) to the outside of the system. The discharge unit (35) has a U shape and includes a U-shaped pipe (35a) filled with liquid inside.

[0065] In the above configuration, the discharge unit has a U shape and includes a U-shaped pipe filled with liquid inside. As a result, the liquid filled inside the discharge unit seals the inside and outside of the discharge unit. Therefore, it is possible to suppress the situation where air, particularly oxygen, flows into the inside of the discharge unit through the discharge unit. Therefore, combustion of the hydrogen-containing gas inside the discharge unit can be avoided. Also, the situation where the hydrogen-containing gas inside the discharge unit leaks into the atmosphere and burns can be avoided. Therefore, the safety of the hydrogen production plant can be improved.

[0066] Further, the hydrogen production method according to the first aspect of the present disclosure includes a production step of producing a hydrogen-containing gas, an introduction step of introducing the hydrogen-containing gas produced in the production step into the inside of the discharge part (30), a supply step of supplying a cooling fluid to the hydrogen-containing gas introduced into the inside of the discharge part (30), and a discharge step of discharging the hydrogen-containing gas introduced into the inside of the discharge part (30) to the atmosphere.

Explanation of Signs

[0067] 1: Hydrogen production plant 10: SOEC (production part) 11: Instrument air supply part 12: City gas supply part 13: Hydrogen gas supply part 14: Nitrogen gas supply part 15: Makeup water supply part 16: Electrolysis air supply part 17: Electric boiler (steam generation part) 18: Heat exchanger 20: Hydrogen generation part 21: Cooler 22: Dehumidifier 23: Compressor 30: Discharge stack (discharge part) 31: Housing 31a: Large diameter part 31b: Small diameter part 31c: Discharge opening 32: Spray part (cooling fluid supply part) 33: Storage part 34: Seal part 34a: Reduced diameter part 35: Discharge part 35a: U-shaped pipe 40: Raw water supply part 41: Drain pit 50: Control part 51: Thermometer 52: Level gauge B1: First steam valve B2: First hydrogen-containing gas valve B3: Nitrogen valve B4: Second steam valve B5: Second hydrogen-containing gas valve B6: Cooling water valve L1: Nitrogen pipe (First nitrogen pipe) L2: Makeup water pipe L3: Steam pipe (First steam pipe) L4: Hydrogen-containing gas pipe L5: Branch nitrogen pipe (Second nitrogen pipe) L6: Branch makeup water pipe L7: Branch steam pipe (Second steam pipe) L8: Branch hydrogen-containing gas pipe

Claims

1. A production unit for producing a hydrogen-containing gas, and an emission unit into which the hydrogen-containing gas produced by the production unit is introduced and that emits the introduced hydrogen-containing gas to the atmosphere, wherein the emission unit has a cooling fluid supply unit that supplies a cooling fluid for cooling the hydrogen-containing gas to the hydrogen-containing gas introduced therein. A hydrogen production plant.

2. A steam generation unit that generates steam to be supplied to the production unit, a first steam pipe that guides the steam generated by the steam generation unit to the production unit, and a second steam pipe that guides the steam generated by the steam generation unit to the emission unit, wherein the emission unit has an emission opening that opens toward the atmosphere and a seal unit that suppresses the inflow of the atmosphere from the emission opening by using the steam supplied through the second steam pipe. The hydrogen production plant according to claim 1.

3. The emission unit has a cooling fluid adjustment unit that adjusts the amount of the cooling fluid supplied from the cooling fluid supply unit, and a temperature detection unit that detects the temperature of the hydrogen-containing gas cooled by the cooling fluid, and includes a control unit that controls the cooling fluid adjustment unit based on the temperature of the hydrogen-containing gas detected by the temperature detection unit. The hydrogen production plant according to claim 1.

4. The emission unit has a cooling fluid adjustment unit that adjusts the amount of the cooling fluid supplied from the cooling fluid supply unit, a storage unit that stores the condensed water generated by condensation of the hydrogen-containing gas, and a level detection unit that detects the liquid level of the condensed water stored in the storage unit, and includes a control unit that controls the cooling fluid adjustment unit based on the liquid level detected by the level detection unit. The hydrogen production plant according to claim 1.

5. A first nitrogen pipe that guides nitrogen gas from a nitrogen supply unit to the production unit, and a second nitrogen pipe that guides nitrogen gas from the nitrogen supply unit to the emission unit. The hydrogen production plant according to claim 1.

6. The emission unit has a storage unit that stores the condensed water generated by condensation of a part of the hydrogen-containing gas, and a discharge unit that discharges the condensed water stored in the storage unit to the outside of the system, wherein the discharge unit has a U-shaped pipe that has a U shape and is filled with liquid. The hydrogen production plant according to claim 1.

7. A production process for producing a hydrogen-containing gas, and an introduction process for introducing the hydrogen-containing gas produced in the production process into the emission unit, A supply step of supplying a cooling fluid to the hydrogen-containing gas introduced into the inside of the discharge section; A hydrogen production method comprising a discharge step of discharging the hydrogen-containing gas introduced into the inside of the discharge section to the atmosphere.

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