EP4640922A1

EP4640922A1 - Water electrolysis hydrogen production system

Info

Publication number: EP4640922A1
Application number: EP22969269.4A
Authority: EP
Inventors: Masataka Ozeki; Futoshi Furuta; Keiji Watanabe
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2022-12-23
Filing date: 2022-12-23
Publication date: 2025-10-29
Also published as: WO2024134886A1

Abstract

Provided is a water electrolytic hydrogen production system configured by connecting a plurality of water electrolysis stacks in series, wherein the system is capable of ensuring sufficient insulation performance of each of the water electrolysis stacks. The water electrolytic hydrogen production system includes: a plurality of water electrolysis apparatuses, wherein each of the water electrolysis apparatuses includes: a water electrolysis stack configured to generate hydrogen and oxygen by electrolysis of water; a water supply portion configured to supply water to the water electrolysis stack; a water intake portion configured to take water into the water supply portion from outside; a hydrogen release portion configured to release hydrogen generated in the water electrolysis stack to outside; and an oxygen release portion configured to release oxygen generated in the water electrolysis stack to outside, the water electrolysis stacks of the plurality of water electrolysis apparatuses are electrically connected to each other in series, and an insulation member is disposed at a connecting portion of piping for supplying or releasing a fluid with outside of the apparatus, the piping including at least the water intake portion, the hydrogen release portion, and the oxygen release portion of each of the plurality of water electrolysis apparatuses.

Description

Technical Field

The present invention relates to a structure of a water electrolytic hydrogen production system, and particularly relates to a technique effective for application to a large-scale water electrolytic hydrogen production system configured by connecting a plurality of water electrolysis stacks in series.

Background Art

In recent years, hydrogen is seen as next-generation energy, and expected to be utilized as clean energy in combination with carbon dioxide (CO₂) free electricity such as renewable energy. By utilizing power derived from renewable energy in a water electrolytic hydrogen production system that produces hydrogen by decomposing water into oxygen and hydrogen by the power of electricity, so-called green hydrogen that does not discharge CO₂ during production and in use can be produced.
Therefore, a demand for a large-scale water electrolytic hydrogen production system is growing toward the early realization of a hydrogen society. A large-scale water electrolytic hydrogen production system has a plurality of water electrolysis stacks within the system. A power supply is required for electrolysis of water in the water electrolysis stacks.
As an example of the background art of the present technical field, a technique such as PTL 1 is known. PTL 1 discloses "a high-pressure container storage type water electrolytic hydrogen generation device with a simple configuration and ease of assembly, and that is capable of generating a large amount of hydrogen".
PTL 1 describes a configuration in which a power supply is connected to each of a plurality of water electrolysis stacks (a water electrolysis tank in PTL 1) independently, and a configuration in which a single power supply is connected to the water electrolysis stacks connected in series. The power supply configuration is more simplified by the configuration in which the water electrolysis stacks are connected in series and one power supply is connected.
In addition, PTL 2 discloses "a water electrolysis system capable of achieving high efficiency of the entire system with a simple and compact configuration without wastefully discarding hydrogen dissolved in high-pressure water".
PTL 2 describes an internal configuration of a water electrolysis stacks (in PTL 2, an electrolysis stack), and an electrolysis portion in which a water electrolysis reaction actually occurs in the water electrolysis stacks (in PTL 2, a portion constituted by terminal portions 38a and 38b and a laminated portion of portion cells 30) is electrically insulated from other portions by an insulation (insulating plates 34a, 34b), and the insulation is provided inside the water electrolysis stack. In general, the electrolysis portion is electrically grounded from the viewpoint of durability and reliability of the entire apparatus.

Citation List

Patent Literature

PTL 1: JP 2006-131944 A
PTL 2: JP 2013-53321 A

Summary of Invention

Technical Problem

When a large-scale water electrolytic hydrogen production system is configured using a plurality of water electrolysis stacks, it is possible to make a power supply configuration small and simple by electrically connecting the plurality of water electrolysis stacks in series as in PTL 1.
However, if the number of water electrolysis stacks connected in series increases, the voltage of the entire electrolysis portion in the plurality of water electrolysis stacks when water electrolysis is performed by passing a current increases.
As in PTL 2, the electrolysis portion is insulated from the other portions. On the other hand, since the portions other than the electrolysis portion are electrically grounded in general, the potential is electrically uniform.
As a result, the larger the number of water electrolysis stacks, the larger the maximum potential difference (maximum voltage) between the electrolysis portion insulated in the water electrolysis stacks and the portions other than the electrolysis portion.
In a general water electrolysis stack, an insulation inside does not have sufficient insulation performance for ensuring insulation with respect to a voltage generated in a large number of water electrolysis stacks connected in series.
As a result, when a large number of water electrolysis stacks are connected in series, leakage current increases due to insufficient insulation performance of the insulation, and this may lead to deterioration of durability and reliability of the water electrolysis stacks and the water electrolytic hydrogen production system.
Therefore, an object of the present invention is to provide a water electrolytic hydrogen production system configured by connecting a plurality of water electrolysis stacks in series, wherein the system is capable of ensuring sufficient insulation performance of each of the water electrolysis stacks.

Solution to Problem

In order to solve the above problems, the present invention provides a water electrolytic hydrogen production system including a plurality of water electrolysis apparatuses, wherein each of the water electrolysis apparatuses includes: a water electrolysis stack configured to generate hydrogen and oxygen by electrolysis of water; a water supply portion configured to supply water to the water electrolysis stack; a water intake portion configured to take water into the water supply portion from outside; a hydrogen release portion configured to release hydrogen generated in the water electrolysis stack to outside; and an oxygen release portion configured to release oxygen generated in the water electrolysis stack to outside, the water electrolysis stacks of the plurality of water electrolysis apparatuses are electrically connected to each other in series, and an insulation member is disposed at a connecting portion of piping for supplying or releasing a fluid with outside of the apparatus, the piping including at least the water intake portion, the hydrogen release portion, and the oxygen release portion of each of the plurality of water electrolysis apparatuses.
Further, the present invention provides a water electrolytic hydrogen production system including a plurality of water electrolysis apparatuses, wherein each of the water electrolysis apparatuses includes: a water electrolysis stack configured to generate hydrogen and oxygen by electrolysis of water; a water supply portion configured to supply water to the water electrolysis stack; a water intake portion configured to take water into the water supply portion from outside; a hydrogen release portion configured to release hydrogen generated in the water electrolysis stack to outside; and an oxygen release portion configured to release oxygen generated in the water electrolysis stack to outside, the water electrolysis stacks of the plurality of water electrolysis apparatuses are electrically connected to each other in series, and an insulation member is disposed in piping between at least one of the water intake portion, the hydrogen release portion, and the oxygen release portion, and the water electrolysis stack.

Advantageous Effects of Invention

According to the present invention, it is possible to realize a water electrolytic hydrogen production system configured by connecting a plurality of water electrolysis stacks in series, wherein the system is capable of ensuring sufficient insulation performance of each of the water electrolysis stacks.
Accordingly, durability and reliability of the water electrolysis stacks and the water electrolytic hydrogen production system can be improved.
Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

Brief Description of Drawings

[FIG. 1] FIG. 1 is a diagram showing a schematic configuration of a water electrolytic hydrogen production system according to a first embodiment of the present invention.
[FIG. 2] FIG. 2 is a diagram showing a structure of a water electrolysis stack in FIG. 1.
[FIG. 3] FIG. 3 is a diagram illustrating a modification of an insulation member in a water intake portion in FIG. 1.
[FIG. 4] FIG. 4 is a diagram showing a schematic configuration of a water electrolytic hydrogen production system according to a second embodiment of the present invention.
[FIG. 5] FIG. 5 is a diagram showing a schematic configuration of a water electrolytic hydrogen production system according to a third embodiment of the present invention.
[FIG. 6] FIG. 6 is a diagram showing a structure of a water electrolysis stack in FIG. 5.
[FIG. 7] FIG. 7 is a diagram showing a schematic configuration of a water electrolytic hydrogen production system according to a fourth embodiment of the present invention.
[FIG. 8] FIG. 8 is a diagram showing a schematic configuration of a water electrolytic hydrogen production system according to a fifth embodiment of the present invention.
[FIG. 9] FIG. 9 is a diagram showing a schematic configuration of a water electrolytic hydrogen production system according to a sixth embodiment of the present invention.
[FIG. 10] FIG. 10 is a diagram showing a modification of the water electrolytic hydrogen production system in FIG. 9.
[FIG. 11] FIG. 11 is a diagram showing a schematic configuration of a water electrolytic hydrogen production system according to a seventh embodiment of the present invention.
[FIG. 12] FIG. 12 is a diagram showing a schematic configuration of a conventional multi-series water electrolytic hydrogen production system.

Description of Embodiments

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and the detailed description of overlapping components is omitted.

[First embodiment]

In order to facilitate understanding of the present invention, a conventional multi-series water electrolytic hydrogen production system will be first described with reference to FIG. 12.
FIG. 12 is a diagram showing a schematic configuration of a conventional multi-series water electrolytic hydrogen production system. FIG. 12 shows an example in which ten water electrolysis stacks 3 are connected in series.
As shown in FIG. 12, a conventional multi-series water electrolytic hydrogen production system is configured by electrically connecting water electrolysis stacks 3 in series. A power supply 12 is connected to both ends of the ten water electrolysis stacks 3 connected in series, and a voltage for the ten water electrolysis stacks is applied. In FIG. 12, assuming that the voltage for one water electrolysis stack is 0.5 kV, a total voltage of 5.0 kV (0.5 kV/piece × 10 pieces) is applied to the entire ten water electrolysis stacks 3. In this case, a potential on the positive (+) side of a first one of the water electrolysis stacks 3 is 2.5 kV, and a potential on the negative (-) side of the first one of the water electrolysis stacks 3 is 2.0 kV. In addition, a potential on the positive (+) side of a tenth one of the water electrolysis stacks 3 is -2.0 kV, and a potential on the negative (-) side of the tenth one of the water electrolysis stacks 3 is -2.5 kV. The current flows from the first one of the water electrolysis stacks 3 towards the tenth one of the water electrolysis stacks 3.
Water (H₂O) taken from outside through a water intake portion 4 is sent to a water supply portion 5 of the water electrolysis stack 3 by an electric motor 10 such as a water pump, and taken into the water electrolysis stack 3 through the water supply portion 5. Water (H₂O) taken into the water electrolysis stack 3 is decomposed into hydrogen (H₂) and oxygen (O₂) by a water electrolysis reaction by a voltage (0.5 kV) corresponding to one water electrolysis stack applied to the water electrolysis stack 3, and is released outside through a hydrogen release portion 6 and an oxygen release portion 7, respectively.
Oxygen (O₂) generated inside the water electrolysis stack 3 is released from the water electrolysis stack 3 as a mixture with water (H₂O) which has not contributed to the reaction (O₂, H₂O), and therefore, after being separated into oxygen (O₂) and water (H₂O) by a gas-liquid separator 11, oxygen (O₂) is released outside from the oxygen release portion 7, and water (H₂O) is supplied inside of the water electrolysis stack 3 again through the water supply portion 5.
In the water electrolysis stack 3, an insulation 8 is disposed at a portion to which piping for supplying or releasing a fluid such as the water supply portion 5, the hydrogen release portion 6, and the oxygen release portion 7 is connected, and the water electrolysis stack 3 is insulated from outside except for an electrode portion to which the power supply 12 is connected. In addition, a portion other than the electrode portion to which the power supply 12 is connected is grounded (0 kV).
Therefore, a maximum potential difference of 2.5 kV with respect to the ground potential (0 kV) is generated in the first one of the water electrolysis stacks 3, and a maximum potential difference of -2.5 kV with respect to the ground potential (0 kV) is generated in the tenth one of the water electrolysis stacks 3.
In the typical water electrolysis stack 3, the insulation 8 in the water electrolysis stack 3 usually has an insulation performance capable of withstanding a selfgenerated voltage of 0.5 kV.
However, when a large number of water electrolysis stacks 3 are connected in series, leakage current increases due to insufficient insulation performance of the insulation 8, and this may lead to deterioration of durability and reliability of the water electrolysis stacks 3 and a multi-series water electrolytic hydrogen production system as a whole.
Although it is conceivable to design a water electrolysis stack with insulation performance for a voltage of 5 to 10 times as large with a margin, actually using the water electrolysis stack under a situation where a voltage of 5 to 10 times as large is generated is beyond the design concept of the water electrolysis stacks, and would always reduce durability and reliability.
Next, a water electrolytic hydrogen production system according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
FIG. 1 is a diagram showing a schematic configuration of a water electrolytic hydrogen production system 1 of the present embodiment. FIG. 2 is a diagram showing a structure of the water electrolysis stack 3 in FIG. 1. FIG. 3 is a diagram illustrating a modification of the insulation member 9 in the water intake portion 4 in FIG. 1.
As shown in FIG. 1, the water electrolytic hydrogen production system 1 of the present embodiment includes ten water electrolysis apparatuses 2 each having the water electrolysis stack 3. The water electrolysis stacks 3 of the water electrolysis apparatuses 2 are electrically connected to each other in series, and the power supply 12 is connected to an anode (positive electrode) side of a first water electrolysis stack 3 and a cathode (negative electrode) side of a tenth water electrolysis stack 3.
Each of the water electrolysis apparatuses 2 mainly includes the water supply portion 5 that supplies water (H₂O) to the water electrolysis stack 3, the water intake portion 4 that takes water (H₂O) from outside into the water supply portion 5, the hydrogen release portion 6 that releases hydrogen (H₂) generated in the water electrolysis stack 3 to outside, the oxygen release portion 7 that releases oxygen (O₂) generated in the water electrolysis stack 3 to outside, and the gas-liquid separator 11 that separates a mixture (O₂, H₂O) of oxygen (O₂) and water (H₂O) into oxygen (O₂) and water (H₂O) .
Further, in the water electrolysis apparatus 2, an insulation member 9 is disposed at a connecting portion of piping for supplying or releasing a fluid to or from the outside of the apparatus, the piping including the water intake portion 4, the hydrogen release portion 6, and the oxygen release portion 7.
As shown in FIG. 2, the water electrolysis stack 3 is held by fastening an electrolysis portion 13, power feed plates 15, and the insulation 8 integrally with end plates 14, and further includes a water supply port 16, a mixed discharge port 18, and a hydrogen outlet 17.
The electrolysis portion 13 of the water electrolysis stack 3 includes a solid polymer film and a MEA (Membrane Electrode Assembly) in which an anode (positive electrode) and a cathode (negative electrode) are formed on both sides of the solid polymer film (none of them are shown), and water (H₂O) is supplied to the anode (positive electrode) through the water supply port 16, and a current flows from one (left side in FIG. 2) of the pair of power feed plates 15 to the other (right side in FIG. 2), so that a water electrolysis reaction occurs in the electrolysis portion 13. At this time, oxygen (O₂) generated at the anode (positive electrode) and water (H₂O) that did not contribute to the reaction are released from the mixed discharge port 18 toward outside of the water electrolysis stack 3, and hydrogen (H₂) generated at the cathode (negative electrode) is released from the hydrogen outlet 17 to outside of the water electrolysis stack 3.
After the mixture of oxygen (O₂) and water (H₂O) released from the mixed discharge port 18 is separated into oxygen (O₂) and water (H₂O) by the gas-liquid separator 11, oxygen (O₂) is released from the oxygen release portion 7 to outside of the water electrolysis apparatus 2, and water (H₂O) is again supplied from the water supply portion 5 to the water electrolysis stack 3 through the water supply port 16. In addition, a considerable amount of water (H₂O) consumed in the water electrolysis reaction is taken in from the water intake portion 4 and supplied from the water supply portion 5 to the water electrolysis stack 3 through the water supply port 16.
Here, pure water or ultrapure water having a specific resistance value of 1 to 10 MΩ·cm or more is used as water (H₂O) supplied from the water intake portion 4, and the specific resistance value of water in the water electrolytic hydrogen production system 1 is maintained by circulating the water through an ion exchange resin (not shown) in the system.
The pair of power feed plates 15 and the electrolysis portion 13 of the water electrolysis stack 3 are electrically insulated from other constituent members such as the end plates 14 and pipes by the insulation 8.
Since the water electrolysis stack 3 generates a voltage of 0.5 kV between the pair of power feed plates 15 during the water electrolysis reaction, a difference between a maximum potential and a minimum potential of the ten water electrolysis stacks 3 connected in series is 5 kV.
Here, all the insulation members 9 can maintain sufficient insulation properties between inside and outside of the water electrolysis apparatus 2 even when a voltage of 5 kV, which is the difference between the maximum potential and the minimum potential of the water electrolysis stack 3, is applied.
In addition, all the components inside the water electrolysis apparatus 2 are electrically insulated from outside by the insulation member 9 except for the power supply portion, and are electrically connected to the water electrolysis stack 3 weakly through water (H₂O). Therefore, in each water electrolysis apparatus 2, the constituent members and the electrolysis portion 13 in the water electrolysis stack 3 are substantially equipotential.
Specifically, in the example shown in FIG. 1, the potential on the anode (positive electrode) side of the water electrolysis stack 3 inside a first one of the water electrolysis apparatuses 2 is 2.5 kV, but a portion connected to the left side of the water electrolysis stack 3 such as the water supply portion 5 also has a potential of approximately 2.5 kV, and a portion connected to the right side of the water electrolysis stack 3 has a potential of 2.0 kV.
As a result, the potential difference between both ends of the insulation 8 inside the water electrolysis stack 3 is not a problem, and the insulation performance of the insulation 8 is maintained. The same applies to a second to a tenth one of the water electrolysis apparatuses 2.
Even in the water intake portion 4, when water (H₂O) flows from outside into the water electrolysis apparatus 2, a situation in which the water is weakly electrically connected may occur, but even in this case, the problem is solved by increasing the resistance value of the water (H₂O) by reducing a cross-sectional area of a water flow passage of the water intake portion 4 to increase the insulation.
Furthermore, as shown in FIG. 3, if the water intake portion 4 is configured by a water intake tank 19 having an air layer therein and an insulation member 20, and the amount of water taken from outside is controlled so that the water level in the water intake tank 19 is at a position equal to or lower than the insulation member 20, a situation where the water is electrically connected through water (H₂O) is avoided.

[Second embodiment]

A water electrolytic hydrogen production system according to a second embodiment of the present invention will be described with reference to FIG. 4. FIG. 4 is a diagram showing a schematic configuration of water electrolytic hydrogen production system 1 of the present embodiment.
As shown in FIG. 4, the water electrolytic hydrogen production system 1 of the present embodiment is different from that of the first embodiment (FIG. 1) in that casings of all the water electrolysis apparatuses 2 are configured by insulation casings 21 instead of providing the insulation member 9 inside each of the water electrolysis apparatuses 2. Other configurations are the same as those of the first embodiment (FIG. 1).
The casings of all the water electrolysis apparatuses 2 are formed of an insulation member, and it is possible to maintain sufficient insulation properties even when the voltage of 5 kV, which is the difference between the maximum potential and the minimum potential of the water electrolysis stack 3, is applied between inside and outside of the water electrolysis apparatus 2.
Further, all the components inside the water electrolysis apparatus 2 are electrically insulated from outside by the insulation casing 21 of the water electrolysis apparatus 2, and are electrically connected to the water electrolysis stack 3 weakly through water (H₂O). Therefore, in each water electrolysis apparatus 2, the constituent members and the electrolysis portion 13 in the water electrolysis stack 3 are substantially equipotential.
As described above, the same effects as those of the first embodiment can be obtained without using the insulation member 9 as in the first embodiment (FIG. 1).

[Third embodiment]

A water electrolytic hydrogen production system according to a third embodiment of the present invention will be described with reference to FIGS. 5 and 6.
FIG. 5 is a diagram showing a schematic configuration of water electrolytic hydrogen production system 1 of the present embodiment. FIG. 6 is a diagram showing a structure of the water electrolysis stack 3 in FIG. 5.
As shown in FIG. 5, the water electrolytic hydrogen production system 1 of the present embodiment is different from that of the first embodiment (FIG. 1) in that, in addition to the configuration of the first embodiment (FIG. 1), the water electrolysis stack 3 and the water supply portion 5 are electrically connected via a wiring 22 and the like. Other configurations are the same as those of the first embodiment (FIG. 1).
As shown in FIG. 5, the water electrolysis stack 3 and the water supply portion 5 are electrically connected inside each of the water electrolysis apparatuses 2.
FIG. 6 shows a specific connection portion between the water electrolysis stack 3 and the water supply portion 5. The power feed plate 15 on the anode (positive electrode) side is electrically connected to the water electrolysis stack 3 side, and the pipe (water supply port 16) near the connection portion with the water electrolysis stack 3 is electrically connected to the water supply portion 5 side.
As a result, both ends of the insulation 8 inside the water electrolysis stack 3 are substantially equipotential.
The connection portion on the side of the water electrolysis stack 3 is sufficiently within the design range of the insulation 8 as long as it is either of the pair of power feed plates 15 and the electrolysis portion 13, and similar performance can be obtained, and thus, the connection portion does not exceed the scope of the present invention.
In place of the water supply portion 5, the water intake portion 4, the hydrogen release portion 6, and the oxygen release portion 7 may be electrically connected to the power feed plate 15 or the electrolysis portion 13.

[Fourth embodiment]

A water electrolytic hydrogen production system according to a fourth embodiment of the present invention will be described with reference to FIG. 7. FIG. 7 is a diagram showing a schematic configuration of water electrolytic hydrogen production system 1 of the present embodiment.
As shown in FIG. 7, the water electrolytic hydrogen production system 1 of the present embodiment is different from that of the first embodiment (FIG. 1) in that, in addition to the configuration of the first embodiment (FIG. 1), a potential setting portion 23 in which voltage sources that generate voltages equivalent to those of the respective water electrolysis stacks 3 are connected in series by the number that is less than the number of the water electrolysis stacks 3 by one is further provided. Other configurations are the same as those of the first embodiment (FIG. 1).
The potential setting portion 23 includes voltage sources for generating a voltage equal to that of the water electrolysis stacks 3 provided in the respective water electrolysis apparatuses 2 by the number that is less than the number of the water electrolysis apparatuses 2 (water electrolysis stacks 3) by one. In the example in FIG. 7, the ten water electrolysis stacks 3 are connected in series, and the potential setting portion 23 includes nine voltage sources each generating a voltage of 0.5 kV. The voltage sources of the potential setting portion 23 are electrically connected to the water supply portions 5 of the water electrolysis apparatuses 2.
As a result, the voltage between the water electrolysis stacks 3 is set, and both ends of the insulation 8 inside the water electrolysis stack 3 can be made substantially equipotential.
Note that the potential setting portion 23 can be configured by one voltage source and a plurality of (for example, nine) resistors, and equivalent performance can be obtained even for similar circuit deformation, and thus does not exceed the scope of the present invention.

[Fifth embodiment]

A water electrolytic hydrogen production system according to a fifth embodiment of the present invention will be described with reference to FIG. 8. FIG. 8 is a diagram showing a schematic configuration of water electrolytic hydrogen production system 1 of the present embodiment.
As shown in FIG. 8, the water electrolytic hydrogen production system 1 of the present embodiment is different from that of the first embodiment (FIG. 1) in that, in addition to the configuration of the first embodiment (FIG. 1), an auxiliary machine power supply portion 24 that supplies power to an electric motor (water pump) 10 is further included separately from the power supply 12. Other configurations are the same as those of the first embodiment (FIG. 1).
As shown in FIG. 8, the electric motor 10 such as a water pump is provided inside the water electrolysis apparatus 2, and is often driven at AC 200 V or AC 100 V.
Since the casing of the electric motor 10 is connected to the components inside the water electrolysis apparatus 2 such as the water supply portion 5, the electric potential is substantially equal to that of the water electrolysis stack 3 in each water electrolysis apparatus 2. Therefore, when power is directly supplied from an external power supply to the electric motor 10, a large potential difference is generated between the external power supply and the housing of the electric motor 10.
In order to avoid this, a power supply electrically insulated by a transformer 25 or the like is connected to the electric motor 10 such as a water pump.
To the coil on the primary side (AC power supply side in FIG. 8) of each transformer 25, 0.5 kV (the same voltage as that of the water electrolysis stack 3) is applied, and AC 200 V or AC 100 V (power supply voltage of the auxiliary machine) is generated in the coil on the secondary side (water electrolysis apparatus side in FIG. 8).
As a result, a large potential difference is not generated between the casing of each auxiliary machine such as the electric motor 10 and the power supply, and durability and reliability of each auxiliary machine can also be maintained.

[Sixth embodiment]

A water electrolytic hydrogen production system according to a sixth embodiment of the present invention will be described with reference to FIGS. 9 and 10. FIG. 9 is a diagram showing a schematic configuration of water electrolytic hydrogen production system 1 of the present embodiment. FIG. 10 is a diagram showing a modification of the water electrolytic hydrogen production system 1 in FIG. 9.
As shown in FIG. 9, the water electrolytic hydrogen production system 1 of the present embodiment is different from that of the first embodiment (FIG. 1) in that the insulation member 9 is disposed in pipes between the water intake portion 4, the hydrogen release portion 6, and the oxygen release portion 7, and the water electrolysis stack 3 instead of being disposed in a connection portion of pipes that supply or release a fluid to and from outside of the apparatus. Other configurations are the same as those of the first embodiment (FIG. 1).
When sufficient insulation performance can be secured for each water electrolysis stack 3, the insulation member 9 may be disposed in the vicinity of the water electrolysis stack 3 as shown in FIG. 9.
As shown in FIG. 10, in addition to the configuration of the first embodiment (FIG. 1), another insulation member 9 may be disposed in pipes between the water intake portion 4, the hydrogen release portion 6, and the oxygen release portion 7, and the water electrolysis stack 3. The insulation performance of the water electrolysis stack 3 can be further improved.

[Seventh embodiment]

A water electrolytic hydrogen production system according to a seventh embodiment of the present invention will be described with reference to FIG. 11. FIG. 11 is a diagram showing a schematic configuration of the water electrolytic hydrogen production system 1 of the present embodiment.
As shown in FIG. 11, the water electrolytic hydrogen production system 1 of the present embodiment is different from that of the sixth embodiment (FIG. 9) in that, in addition to the configuration of the sixth embodiment (FIG. 9), the water electrolysis stack 3 and the water supply portion 5 are electrically connected via the wiring 22 and the like. Other configurations are similar to those of the sixth embodiment (FIG. 9).
As shown in FIG. 11, in all the water electrolysis apparatuses 2, the water electrolysis stack 3 and the water supply portion 5 are electrically connected.
A specific configuration of the connection portion between the water electrolysis stack 3 and the water intake portion 4, the water supply portion 5, the hydrogen release portion 6, and the oxygen release portion 7 is the same as that of third embodiment (FIG. 6). That is, the power feed plate 15 or the electrolysis portion 13 of the water electrolysis stack 3 is electrically connected to the water supply portion 5.
As a result, both ends of the insulation 8 inside the water electrolysis stack 3 are substantially equipotential.
The water electrolysis stack 3 may be electrically connected to any one of the insulation member 9 side portions of the water supply portion 5, the hydrogen release portion 6, and the oxygen release portion 7.
In each of the above embodiments, the example in which one water electrolysis stack 3 is disposed in one water electrolysis apparatus 2 has been described, but the present invention is not limited thereto, and a plurality of water electrolysis stacks 3 may be disposed in one water electrolysis apparatus 2.
Further, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail in order to describe the present invention in an easy-to-understand manner, and are not necessarily intended to limit to those having all of the described configurations. Further, a part of one configuration of a certain embodiment can be replaced with a configuration of a different embodiment, and a configuration of one embodiment can be added to a configuration of a different embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

Reference Signs List

1: water electrolytic hydrogen production system
2: water electrolysis apparatus
3: water electrolysis stack
4: water intake portion
5: water supply portion
6: hydrogen release portion
7: oxygen release portion
8: insulation (of water electrolysis stack)
9, 20: insulation member
10: electric motor (water pump)
11: gas-liquid separator
12: power supply
13: electrolysis portion
14: end plate
15: power feed plate
16: water supply port
17: hydrogen outlet
18: mixed discharge port
19: water intake tank
21: insulation casing
22: wiring
23: potential setting portion
24: auxiliary machine power supply portion
25: transformer

Claims

A water electrolytic hydrogen production system comprising a plurality of water electrolysis apparatuses,
wherein each of the water electrolysis apparatuses includes:
a water electrolysis stack configured to generate hydrogen and oxygen by electrolysis of water;

a water supply portion configured to supply water to the water electrolysis stack;

a water intake portion configured to take water into the water supply portion from outside;

a hydrogen release portion configured to release hydrogen generated in the water electrolysis stack to outside; and

an oxygen release portion configured to release oxygen generated in the water electrolysis stack to outside,

the water electrolysis stacks of the plurality of water electrolysis apparatuses are electrically connected to each other in series, and

an insulation member is disposed at a connecting portion of piping for supplying or releasing a fluid with outside of the apparatus, the piping including at least the water intake portion, the hydrogen release portion, and the oxygen release portion of each of the plurality of water electrolysis apparatuses.
The water electrolytic hydrogen production system according to claim 1, wherein a water intake tank having an air layer therein is disposed at the connection portion between the water intake portion and the outside of the apparatus.
The water electrolytic hydrogen production system according to claim 1, wherein the insulation member is an insulation casing of the water electrolysis apparatus.
The water electrolytic hydrogen production system according to claim 1, wherein
the water electrolysis stack includes
a power feed plate that supplies a current from outside; and

an electrolysis portion that performs a water electrolysis reaction,

at least one of the water supply portion, the water intake portion, the hydrogen release portion, and the oxygen release portion is electrically connected to one of the power feed plate and the electrolysis portion.
The water electrolytic hydrogen production system according to claim 1, wherein the water supply portion, the water intake portion, the hydrogen release portion, and the oxygen release portion are substantially equipotential to a part of the water electrolysis stack.
The water electrolytic hydrogen production system according to claim 1, further comprising:
a potential setting portion in which voltage sources of a number smaller than a number of the water electrolysis stacks by one are connected in series, each of the voltage sources generating a voltage equivalent to a voltage generated by each of the water electrolysis stacks of the plurality of water electrolysis apparatuses,

wherein at least one of the water supply portion, the water intake portion, the hydrogen release portion, and the oxygen release portion is electrically connected to the voltage source.
The water electrolytic hydrogen production system according to claim 1, wherein
the water electrolysis apparatus includes one or more electric motors, and

a power supply that supplies power to the electric motors is insulated by a transformer from a power supply that supplies power to the water electrolysis stack.
The water electrolytic hydrogen production system according to claim 1, wherein another insulation member different from the insulation member is disposed in piping between at least one of the water intake portion, the hydrogen release portion, and the oxygen release portion, and the water electrolysis stack.
A water electrolytic hydrogen production system comprising a plurality of water electrolysis apparatuses,
wherein each of the water electrolysis apparatuses includes:
a water electrolysis stack configured to generate hydrogen and oxygen by electrolysis of water;

a water supply portion configured to supply water to the water electrolysis stack;

a water intake portion configured to take water into the water supply portion from outside;

a hydrogen release portion configured to release hydrogen generated in the water electrolysis stack to outside; and

an oxygen release portion configured to release oxygen generated in the water electrolysis stack to outside,

the water electrolysis stacks of the plurality of water electrolysis apparatuses are electrically connected to each other in series, and

an insulation member is disposed in piping between at least one of the water intake portion, the hydrogen release portion, and the oxygen release portion, and the water electrolysis stack.
The water electrolytic hydrogen production system according to claim 9, wherein
the water electrolysis stack includes
a power feed plate that supplies a current from outside; and

an electrolysis portion that performs a water electrolysis reaction,

at least one of the water supply portion, the water intake portion, the hydrogen release portion, and the oxygen release portion is electrically connected to one of the power feed plate and the electrolysis portion.
The water electrolytic hydrogen production system according to claim 9, wherein the water supply portion, the water intake portion, the hydrogen release portion, and the oxygen release portion are substantially equipotential to a part of the water electrolysis stack.