WO2024195081A1 - Water-electrolysis hydrogen production system and method for running water-electrolysis hydrogen production system - Google Patents

Abstract

Provided is a water-electrolysis hydrogen production system having a plurality of water electrolysis stacks to which water to be electrolyzed is supplied serially, wherein the system, with a relatively simplified configuration, enables decreasing the amount of supply of pure water or ultrapure water, while reducing the moisture content within the hydrogen discharged from the water electrolysis stacks. This invention is characterized in being provided with: a plurality of water electrolysis stacks for generating hydrogen and oxygen by the electrolysis of water, and to which the water to be electrolyzed is supplied serially; and a plurality of hydrogen discharge units for discharging to the exterior the hydrogen generated in each of the plurality of water electrolysis stacks.

Description

Water electrolysis hydrogen production system, and method for operating the water electrolysis hydrogen production system

The present invention relates to the structure and operation method of a water electrolysis hydrogen production system, and in particular to technology that is effective when applied to a large-scale water electrolysis hydrogen production system that is composed of multiple water electrolysis stacks connected in series.

In recent years, hydrogen has been attracting attention as the next generation of energy, and it is expected to be used as a clean energy source when combined with carbon dioxide ( _CO2 )-free electricity from renewable energies. By using electricity derived from renewable energy sources in a water electrolysis hydrogen production system that uses electrical power to split water into oxygen and hydrogen to produce hydrogen, it is possible to produce so-called green hydrogen, which does not emit _CO2 during either production or use.

As a result, while demand for hydrogen is increasing in preparation for a decarbonized society, it is desirable for the hydrogen product to be in a dry state. For example, the international standard ISO14687, which specifies hydrogen quality, stipulates that the water concentration in hydrogen used in fuel cell vehicles and the like must be 5 ppm or less. Meanwhile, in water electrolysis hydrogen production systems, which are effective for producing green hydrogen using electricity derived from renewable energy sources, hydrogen is produced in a state that contains water in the built-in water electrolysis stack.

For this reason, water electrolysis hydrogen production systems typically also include a dehumidifier to remove moisture from the hydrogen that comes out of the water electrolysis stack.

The background technology of this technical field is, for example, technology such as that of Patent Document 1. Patent Document 1 discloses "a configuration for dehumidifying hydrogen containing water vapor produced in a high-pressure hydrogen production device 12 (a water electrolysis stack in this application) using a Peltier dehumidifier 94, and a control method thereof."

JP 2013-49906 A

As mentioned above, water electrolysis hydrogen production systems typically include a dehumidifier to ensure hydrogen quality in terms of moisture content.

However, dehumidifiers generally use electronic cooling systems that use Peltier elements, thermal swing adsorption (TSA) systems that use an adsorbent for adsorption and regeneration, and pressure swing adsorption (PSA) systems, but all of these systems have issues such as high power consumption and complex equipment.

In addition, the water used in water electrolysis must have high electrical insulation properties, so special water such as pure water or ultrapure water is required. However, reducing the supply of this pure water and ultrapure water is also an important issue for the widespread use of hydrogen as an energy source.

The object of the present invention is to provide a water electrolysis hydrogen production system and an operating method thereof that has multiple water electrolysis stacks to which water to be electrolyzed is supplied in series, and that can reduce the amount of water in the hydrogen discharged from the water electrolysis stacks while reducing the amount of pure water or ultrapure water supplied, with a relatively simple configuration.

In order to solve the above problems, the present invention is characterized by comprising a plurality of water electrolysis stacks that generate hydrogen and oxygen by electrolysis of water and to which water to be electrolyzed is supplied in series, and a plurality of hydrogen release units that release the hydrogen generated in each of the plurality of water electrolysis stacks to the outside.

The present invention is also a method for operating a water electrolysis hydrogen production system having multiple water electrolysis stacks to which water to be electrolyzed is supplied in series, and is characterized in that the amount of water electrolysis in each water electrolysis stack is determined based on either the position of the water electrolysis stack relative to the flow of the water to be electrolyzed, the flow rate of the water to be electrolyzed flowing into each of the multiple water electrolysis stacks, or the temperature of each of the multiple water electrolysis stacks.

The present invention provides a water electrolysis hydrogen production system having multiple water electrolysis stacks to which water to be electrolyzed is supplied in series, which has a relatively simple configuration and is capable of reducing the amount of water in the hydrogen discharged from the water electrolysis stacks while reducing the amount of pure water or ultrapure water supplied, and a method for operating the system.

This allows the dehumidifier and water supply device to be made smaller and consume less power.

　Problems, configurations and advantages other than those mentioned above will become clear from the description of the embodiments below.

1 is a diagram showing a schematic configuration of a water electrolysis hydrogen production system according to a first embodiment of the present invention. FIG. FIG. 1 is a diagram showing a schematic configuration of a water electrolysis hydrogen production system according to a second embodiment of the present invention. FIG. 11 is a diagram showing a schematic configuration of a water electrolysis hydrogen production system according to a third embodiment of the present invention. FIG. 11 is a diagram showing a schematic configuration of a water electrolysis hydrogen production system according to a fourth embodiment of the present invention. FIG. 4B is a diagram showing a modification of FIG. 4A. FIG. 11 is a diagram showing a schematic configuration of a water electrolysis hydrogen production system according to a fifth embodiment of the present invention. FIG. 13 is a diagram showing a schematic configuration of a water electrolysis hydrogen production system according to a sixth embodiment of the present invention. FIG. 13 is a diagram showing a schematic configuration of a water electrolysis hydrogen production system according to a seventh embodiment of the present invention. FIG. 13 is a diagram showing a schematic configuration of a water electrolysis hydrogen production system according to an eighth embodiment of the present invention. FIG. 1 is a diagram showing a schematic configuration of a conventional water electrolysis hydrogen production system. FIG. 4 is a diagram showing the relationship between gas temperature and saturated water vapor pressure.

Below, an embodiment of the present invention will be described with reference to the drawings. Note that the same components in each drawing will be given the same reference numerals, and detailed descriptions of overlapping parts will be omitted.

In order to make the present invention easier to understand, a conventional water electrolysis hydrogen production system will first be described with reference to Figures 9 and 10. Figure 9 is a diagram showing the schematic configuration of a conventional water electrolysis hydrogen production system. Figure 10 is a diagram showing the relationship between gas temperature and saturated water vapor pressure.

9, in a conventional water electrolysis hydrogen production system, a water electrolysis stack 2 produces oxygen (O2) and hydrogen (H2) by electrolyzing water (pure water: _H2O ) supplied to the inlet of the anode ( _not shown), discharges the oxygen and excess water ( _O2 , _H2O ) from the outlet of the anode, and discharges hydrogen ( _H2 ) from _the outlet of the cathode (not shown). The power consumption of the water electrolysis stack 2 is, for example, 2 MW.

The water electrolysis hydrogen production system comprises an oxygen gas-liquid separator 4 that separates the oxygen and excess water ( _O2 , _H2O ) discharged from the water electrolysis stack 2 and stores the water ( _H2O ), an electric motor (water pump) 5 that circulates the water ( _H2O ) stored in the oxygen gas-liquid separator 4 to the water electrolysis stack 2, a pure water supplier 6 that supplies pure water generated from city water to the oxygen gas-liquid separator 4, and a hydrogen gas-liquid separator 3 that removes the water ( _H2O ) contained in the hydrogen ( _H2 ) discharged from the water electrolysis stack 2.

The oxygen ( _O2 ) and hydrogen ( _H2 ) discharged from the water electrolysis stack 2 also contain water vapor ( _H2O ). The oxygen ( _O2 ) is released (exhausted) directly outside the water electrolysis hydrogen production system, but the hydrogen ( _H2 ) is sent to a dehumidifier 9 to sufficiently reduce the amount of water vapor contained therein.

9, when water at 60°C is supplied to the water electrolysis stack 2, oxygen (O2), hydrogen ( _H2 ) and moisture ( _H2O ) are all discharged from the water electrolysis stack 2 at 80°C due to heat generated by the water electrolysis reaction. Note that _these temperatures are all examples and will vary depending on the configuration of the water supply system and the configuration of the water electrolysis hydrogen production system.

The amount of water vapor contained in oxygen ( _O2 ) and hydrogen ( _H2 ) is equal to the amount of saturated water vapor determined by their respective temperatures. As shown in Figure 10, the amount of water vapor contained increases as the temperature of oxygen ( _O2 ) or hydrogen ( _H2 ) increases, and the higher the temperature, the greater the increase in the amount of water vapor.

For example, hydrogen (H ₂ ) at 80°C contains about 47% water vapor (H ₂ O) in partial pressure ratio (calculated under atmospheric pressure environment, saturated water vapor pressure at 80°C = 47.5 kPa, atmospheric pressure = 101.3 kPa). As described above, the dehumidifier 9 used to remove this water vapor (H ₂ O) generally uses electronic cooling using Peltier elements, temperature swing adsorption (TSA) which uses an adsorbent for adsorption and regeneration, and pressure swing adsorption (PSA), but all of these have problems such as high power consumption and complicated equipment. In addition, in order to compensate for the water vapor (H ₂ O) taken out by oxygen (O ₂ ) and hydrogen (H ₂ ), it is necessary to ensure the supply capacity of the pure water supplier 6 and the amount of power consumption during operation.

Next, a water electrolysis hydrogen production system according to a first embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a diagram showing the schematic configuration of a water electrolysis hydrogen production system 1 according to the present embodiment.

Hereinafter, water or water vapor (H ₂ O), oxygen (O ₂ ), and hydrogen (H ₂ ) will be referred to simply as water or water vapor, oxygen, and hydrogen.

As shown in FIG. 1, the water electrolysis hydrogen production system 1 of this embodiment has four water electrolysis stacks 2, and the anode outlets and anode inlets are connected in sequence from the anode outlet (not shown) of the first (leftmost) water electrolysis stack 2 to the anode inlet (not shown) of the fourth (rightmost) water electrolysis stack 2, which is the last, and the water used for water electrolysis in each water electrolysis stack 2 is supplied in series from the first water electrolysis stack 2 to the fourth water electrolysis stack 2. The power consumption per water electrolysis stack 2 is, for example, 1/4 of the 2 MW of the water electrolysis stack 2 of a conventional water electrolysis hydrogen production system, i.e., 0.5 MW.

Also, it is equipped with an oxygen gas-liquid separator 4 that separates the oxygen and excess water discharged from the fourth water electrolysis stack 2 and stores the water, an electric motor (water pump) 5 that circulates the water stored in the oxygen gas-liquid separator 4 to the water electrolysis stack 2, a pure water supplier 6 that supplies pure water generated from city water to the oxygen gas-liquid separator 4, and a hydrogen gas-liquid separator 3 that removes moisture contained in the hydrogen discharged from each water electrolysis stack 2 after it is merged into one. In other words, it is equipped with one or more hydrogen bonding parts (hydrogen introduction parts of the hydrogen gas-liquid separator 3 in FIG. 1) that bond multiple hydrogen release parts 7 together, and a hydrogen gas-liquid separator 3 that is arranged after all the multiple hydrogen release parts 7 are bonded together.

In addition, the pure water supply device 6 may be installed as a separate device independent of the water electrolysis hydrogen production system 1, as shown in FIG. 1.

The hydrogen generated by water electrolysis in each water electrolysis stack 2 is sent directly from the hydrogen release section 7 of each water electrolysis stack 2 to the hydrogen gas-liquid separator 3.

The oxygen and hydrogen discharged from the water electrolysis stack 2 contain water vapor. The oxygen is directly discharged (exhausted) from the oxygen release section 8 of the oxygen-liquid separator 4 to the outside of the water electrolysis hydrogen production system 1, but the hydrogen is sent to a dehumidifier 9 to sufficiently reduce the amount of water vapor contained therein.

The flow rate of water sent to the water electrolysis stack 2 by the electric motor (water pump) 5 is equal to the flow rate of water required to operate one water electrolysis stack with a capacity equal to the total water electrolysis capacity of the four water electrolysis stacks 2.

The four water electrolysis stacks 2 have the same water electrolysis capacity, and the temperatures of the oxygen, excess water, and hydrogen discharged from each water electrolysis stack 2 are 65°C for the first (leftmost) water electrolysis stack 2, 70°C for the second (second from the left) water electrolysis stack 2, 75°C for the third (third from the left) water electrolysis stack 2, and 80°C for the fourth (rightmost) water electrolysis stack 2.

The amount of water vapor contained in the hydrogen discharged from each water electrolysis stack 2 decreases as the temperature of the hydrogen decreases, as shown in FIG. 10, so the amount of water vapor contained in the hydrogen discharged from the first to third water electrolysis stacks 2 is less than the amount of water vapor contained in the hydrogen discharged from the fourth water electrolysis stack 2. In addition, the hydrogen discharged from each water electrolysis stack 2 is at the same flow rate and has temperatures of 65°C, 70°C, 75°C, and 80°C, respectively, so the hydrogen after merging has an approximate average temperature of 72.5°C, which is lower than 80°C, and therefore contains approximately 34% water vapor in partial pressure ratio (calculated under atmospheric pressure environment, saturated water vapor pressure at 72.5°C = 34.8 kPa, atmospheric pressure = 101.3 kPa).

As described above, the configuration of the water electrolysis hydrogen production system 1 of this embodiment makes it possible to reduce the amount of water vapor contained in the hydrogen by lowering the temperature of the hydrogen discharged from the water electrolysis hydrogen production system 1 without using any special equipment.

This will contribute to the miniaturization and lower power consumption of dehumidification equipment used to remove the water vapor contained in hydrogen. In addition, by reducing the amount of water vapor carried away by hydrogen, it will also be possible to miniaturize pure water supply devices and reduce their power consumption.

In this embodiment, the four water electrolysis stacks 2 have the same water electrolysis capacity, but the present invention is not limited to this, and it is clear that the same effect can be obtained even if the amount of hydrogen discharged from each water electrolysis stack 2 is different.

The water electrolysis hydrogen production system according to the second embodiment of the present invention will be described with reference to FIG. 2. FIG. 2 is a diagram showing the schematic configuration of the water electrolysis hydrogen production system 1 according to the second embodiment.

As shown in FIG. 2, the water electrolysis hydrogen production system 1 of this embodiment differs from Example 1 (FIG. 1) in that it is provided with four hydrogen gas-liquid separators 3 (first to fourth) that remove moisture contained in each of the hydrogen discharged from each water electrolysis stack 2. In other words, each of the multiple hydrogen release units 7 is provided with a hydrogen gas-liquid separator 3. The rest of the configuration is the same as Example 1 (FIG. 1).

Note that the black circles (●) in the figure indicate hydrogen bonding parts that connect each hydrogen release part 7.

If the moisture contained in hydrogen is unevenly distributed in the path through which the hydrogen is discharged, it may cause fluctuations in the flow rate of the hydrogen or obstruct the flow.

Therefore, by providing each hydrogen gas-liquid separator 3 corresponding to each water electrolysis stack 2 as in this embodiment, the moisture in the path for discharging hydrogen can be reduced, thereby improving the operational stability of the water electrolysis hydrogen production system 1.

The water electrolysis hydrogen production system according to the third embodiment of the present invention will be described with reference to FIG. 3. FIG. 3 is a diagram showing the schematic configuration of the water electrolysis hydrogen production system 1 according to the third embodiment.

As shown in FIG. 3, the water electrolysis hydrogen production system 1 of this embodiment differs from that of embodiment 2 (FIG. 2) in that it is provided with three hydrogen gas-liquid separators 3 (first to third) for removing moisture immediately downstream of the location where the hydrogen discharged from each water electrolysis stack 2 joins in sequence. The rest of the configuration is the same as that of embodiment 2 (FIG. 2).

The black circles (●) in the figure indicate hydrogen bonding parts that connect each hydrogen release part 7. In other words, in this embodiment, there are multiple hydrogen bonding parts (●) that connect multiple hydrogen release parts 7, and hydrogen gas-liquid separators 3 are provided immediately behind all of the multiple hydrogen bonding parts (●).

As mentioned above, the hydrogen released from the first (left end) to fourth (right end) water electrolysis stacks 2 has a different temperature, but when hydrogen of different temperatures is merged, the temperature of the hydrogen at the higher temperature drops, causing some of the water vapor contained in the hydrogen to condense and become water. This increases the amount of water contained in the hydrogen immediately downstream of the hydrogen merger. This increased water tends to be unevenly distributed in the hydrogen discharge path, and there is a risk that it will cause fluctuations in the hydrogen flow rate or obstruct the flow.

The configuration of this embodiment allows water to be removed from areas where the amount of water contained in the hydrogen increases, improving the operational stability of the water electrolysis hydrogen production system 1.

A water electrolysis hydrogen production system according to a fourth embodiment of the present invention will be described with reference to Figures 4A and 4B. Figure 4A is a diagram showing the general configuration of the water electrolysis hydrogen production system 1 according to this embodiment. Figure 4B is a diagram showing a modified example of Figure 4A.

As shown in FIG. 4A, the water electrolysis hydrogen production system 1 of this embodiment differs from Example 1 (FIG. 1) in that it is equipped with four oxygen gas-liquid separators 4 (first to fourth) that separate the oxygen and excess water discharged from each water electrolysis stack 2 and store the water. In other words, all of the multiple oxygen release sections 8 are equipped with an oxygen gas-liquid separator 4. The rest of the configuration is the same as Example 1 (FIG. 1).

Note that the black circles (●) in each figure indicate the hydrogen bonding parts that connect each hydrogen releasing part 7 and the oxygen bonding parts that connect each oxygen releasing part 8.

The temperature of the oxygen discharged from each water electrolysis stack 2 is 65°C for the first (leftmost) water electrolysis stack 2, 70°C for the second (second from the left) water electrolysis stack 2, 75°C for the third (third from the left) water electrolysis stack 2, and 80°C for the fourth (rightmost) water electrolysis stack 2.

The amount of water vapor contained in the oxygen discharged from each water electrolysis stack 2 decreases as the temperature of the oxygen decreases, as shown in FIG. 10, so the amount of water vapor contained in the oxygen discharged from the first to third water electrolysis stacks 2 is less than the amount of water vapor contained in the oxygen discharged from the fourth water electrolysis stack 2. In addition, the oxygen discharged from each water electrolysis stack 2 is at the same flow rate and has temperatures of 65°C, 70°C, 75°C, and 80°C, respectively, so the oxygen after merging has an approximate average temperature of 72.5°C, which is lower than 80°C, so this oxygen contains approximately 34% water vapor in partial pressure ratio (calculated under atmospheric pressure environment, saturated water vapor pressure at 72.5°C = 34.8 kPa, atmospheric pressure = 101.3 kPa).

The configuration of this embodiment makes it possible to reduce the amount of water vapor contained in the oxygen by lowering the temperature of the oxygen discharged from the water electrolysis hydrogen production system 1 without using any special equipment.

This reduces the amount of water vapor carried away by oxygen, making it possible to make the pure water supply more compact and reduce power consumption.

Furthermore, oxygen contained in water can also be a factor that inhibits the water electrolysis reaction. By providing an oxygen gas-liquid separator 4 for each water electrolysis stack 2 as in this embodiment, it is possible to reduce the amount of oxygen contained in the water supplied to the second (second from the left) to fourth (rightmost) water electrolysis stacks 2, thereby improving the stability of the water electrolysis reaction of the second to fourth water electrolysis stacks 2.

As shown in the modified example in FIG. 4B, a combination with the second embodiment (FIG. 2) is also possible, i.e., a configuration further including a hydrogen gas-liquid separator 3 corresponding to each water electrolysis stack 2 as in the second embodiment is also possible. It is clear that this can further improve the operational stability of the water electrolysis hydrogen production system 1, and does not go beyond the scope of the present invention.

With reference to FIG. 5, a water electrolysis hydrogen production system and its operating method according to a fifth embodiment of the present invention will be described. FIG. 5 is a diagram showing the general configuration of the water electrolysis hydrogen production system 1 of this embodiment. The configuration other than the controller 10 is the same as that of the first embodiment (FIG. 1).

The controller 10 calculates, from the amount of water electrolysis required in the entire water electrolysis stack 2,
The amount of water electrolysis of each of the first to fourth water electrolysis stacks 2 is determined so that the amount of water electrolysis of the first (leftmost) water electrolysis stack > the amount of water electrolysis of the second (second from the left) water electrolysis stack > the amount of water electrolysis of the third (third from the left) water electrolysis stack > the amount of water electrolysis of the fourth (rightmost) water electrolysis stack. At this time, the amount of water electrolysis of each water electrolysis stack 2 is determined based on predetermined parameters.

In this embodiment, attention is focused on the fact that the water electrolysis stack 2 located upstream in the water flow contains less oxygen, and that the water electrolysis reaction can be more stably operated the further upstream the water electrolysis stack 2 is. For this reason, the amount of oxygen contained in the water supplied to each water electrolysis stack 2 is calculated in advance, and the controller 10 sets the amount of water electrolysis to be higher as the amount of oxygen contained in the water decreases.

As a result, by increasing the amount of water electrolysis in the more stable upstream water electrolysis stack 2, it is possible to ensure both a sufficient amount of water electrolysis in the entire water electrolysis stack 2 and stable operation.

It is clear that the same effect can be obtained by determining the amount of water electrolysis in each water electrolysis stack 2 based on the flow rate of water supplied or other physical quantities.

A water electrolysis hydrogen production system and its operating method according to a sixth embodiment of the present invention will be described with reference to FIG. 6. FIG. 6 is a diagram showing the schematic configuration of the water electrolysis hydrogen production system 1 according to the sixth embodiment.

As shown in FIG. 6, the water electrolysis hydrogen production system 1 of this embodiment differs from that of Example 1 (FIG. 1) in that, in addition to the configuration of Example 1 (FIG. 1), it is equipped with a controller 10 and four flow meters 11 (first to fourth) that measure the flow rate of water supplied to each of the first to fourth water electrolysis stacks 2. The other configuration is the same as that of Example 1 (FIG. 1).

The controller 10 is configured, for example, by a commonly used PID controller, and determines the amount of water electrolysis in each water electrolysis stack 2 according to the flow rate of water supplied to each water electrolysis stack 2 measured by the four flow meters 11.

This is based on the characteristics of the water electrolysis stack 2, which can provide a stable and high water electrolysis capacity the greater the flow rate of water supplied.

In addition, at this time, the flow rate of water supplied to the electrolysis stack 2 located upstream of the water flow is inevitably greater, so the amount of water electrolyzed is greater the further upstream the electrolysis stack 2 is located with respect to the water flow.

According to this embodiment, the more stable the water electrolysis stack is, the greater the amount of water electrolysis can be achieved, making it possible to ensure both a sufficient amount of water electrolysis and stable operation in the entire water electrolysis stack.

With reference to FIG. 7, a water electrolysis hydrogen production system and its operating method according to a seventh embodiment of the present invention will be described. FIG. 7 is a diagram showing the general configuration of the water electrolysis hydrogen production system 1 of this embodiment. The configuration other than the controller 10 is the same as in the first embodiment (FIG. 1).

Note that the black circles (●) in the figure indicate hydrogen bonding parts that connect each hydrogen release part 7.

The controller 10 calculates, from the amount of water electrolysis required in the entire water electrolysis stack 2,
The amount of water electrolysis of each of the first to fourth water electrolysis stacks 2 is determined so that the amount of water electrolysis of the first (leftmost) water electrolysis stack < the amount of water electrolysis of the second (second from the left) water electrolysis stack < the amount of water electrolysis of the third (third from the left) water electrolysis stack < the amount of water electrolysis of the fourth (rightmost) water electrolysis stack. At this time, the amount of water electrolysis of each water electrolysis stack 2 is determined based on predetermined parameters.

In this embodiment, attention is focused on the fact that the temperature of the water electrolysis stack 2 is higher the further downstream the water flow is, and the more downstream the water electrolysis stack 2 is, the more efficiently and stably the water electrolysis reaction can be operated. For this reason, the temperature of each water electrolysis stack 2 is calculated in advance, and the controller 10 sets it so that the higher the temperature, the greater the amount of water electrolysis.

This makes it possible to increase the water electrolysis efficiency relative to the total amount of water electrolysis, realizing an efficient water electrolysis hydrogen production system 1.

It is clear that the same effect can be obtained by determining the amount of water electrolysis in each water electrolysis stack 2 based on a physical quantity other than temperature.

With reference to Figure 8, a water electrolysis hydrogen production system and its operating method according to Example 8 of the present invention will be described. Figure 8 is a diagram showing the schematic configuration of the water electrolysis hydrogen production system 1 of this example.

As shown in FIG. 8, the water electrolysis hydrogen production system 1 of this embodiment differs from that of Example 1 (FIG. 1) in that, in addition to the configuration of Example 1 (FIG. 1), it is equipped with a controller 10 and four thermometers (first to fourth) 12 that measure the temperatures of the first to fourth water electrolysis stacks 2, respectively. The other configurations are the same as those of Example 1 (FIG. 1).

Note that the black circles (●) in the figure indicate hydrogen bonding parts that connect each hydrogen release part 7.

The controller 10 is, for example, a commonly used PID controller, and determines the amount of water electrolysis in each water electrolysis stack 2 according to the temperature of each water electrolysis stack 2 measured by the four thermometers 12.

This is based on the characteristics of the water electrolysis stack 2, which can provide a stable and high water electrolysis capacity the higher the temperature of the water electrolysis stack 2.

In addition, at this time, the temperature of the electrolysis stack 2 located downstream of the water flow will inevitably be higher, so the amount of water electrolysis will be greater the further downstream the electrolysis stack 2 is located with respect to the water flow.

According to this embodiment, the water electrolysis efficiency relative to the total amount of water electrolysis can be increased, and an efficient water electrolysis hydrogen production system 1 can be realized.

The present invention is not limited to the above-described embodiments, but includes various modified examples. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

1...Water electrolysis hydrogen production system, 2...Water electrolysis stack, 3...Hydrogen gas-liquid separator, 4...Oxygen gas-liquid separator, 5...Electric motor (water pump), 6...Pure water supply, 7...Hydrogen release section, 8...Oxygen release section, 9...Dehumidifier, 10...Controller, 11...Flow meter, 12...Thermometer.

Claims (13)

a plurality of water electrolysis stacks that generate hydrogen and oxygen by electrolysis of water and to which water to be electrolyzed is supplied in series;
a plurality of hydrogen release units configured to release hydrogen generated in each of the plurality of water electrolysis stacks to the outside;
A water electrolysis hydrogen production system comprising: The water electrolysis hydrogen production system according to claim 1,
One or more hydrogen bonding portions connecting the plurality of hydrogen releasing portions;
a gas-liquid separator that is disposed behind all of the hydrogen release units. The water electrolysis hydrogen production system according to claim 1,
A water electrolysis hydrogen production system comprising: a gas-liquid separator in each of the plurality of hydrogen release sections. The water electrolysis hydrogen production system according to claim 1,
A plurality of hydrogen bonding portions connecting the plurality of hydrogen releasing portions;
a gas-liquid separator provided immediately behind each of the plurality of hydrogen bonding sections. The water electrolysis hydrogen production system according to claim 1,
A water electrolysis hydrogen production system comprising a plurality of oxygen release units each releasing oxygen generated in each of the plurality of water electrolysis stacks to the outside. The water electrolysis hydrogen production system according to claim 5,
A water electrolysis hydrogen production system comprising: a gas-liquid separator provided in each of the plurality of oxygen release sections. The water electrolysis hydrogen production system according to claim 1,
A water electrolysis hydrogen production system, wherein the amount of water electrolysis is increased as the water electrolysis stack is located upstream of the flow of water to be electrolyzed. The water electrolysis hydrogen production system according to claim 1,
a water electrolysis hydrogen production system, comprising: a water electrolysis stack configured to determine an amount of water electrolysis in each of the plurality of water electrolysis stacks in accordance with a flow rate of the water to be electrolyzed flowing into the respective stacks; The water electrolysis hydrogen production system according to claim 1,
A water electrolysis hydrogen production system, wherein the amount of water electrolysis is reduced as the water electrolysis stack is located closer to the upstream side of the flow of water to be electrolyzed. The water electrolysis hydrogen production system according to claim 1,
a water electrolysis hydrogen production system, comprising: a water electrolysis stack that determines an amount of water electrolysis performed by each of the plurality of water electrolysis stacks in accordance with a temperature of the respective stacks. A method for operating a water electrolysis hydrogen production system having a plurality of water electrolysis stacks to which water to be electrolyzed is supplied in series, comprising the steps of:
a water electrolysis stack configured to generate hydrogen by electrolysis and a water electrolysis device configured to generate hydrogen from the water electrolysis stack; A method for operating a water electrolysis hydrogen production system according to claim 11, comprising:
A method for operating a water electrolysis hydrogen production system, comprising the steps of: increasing the amount of water electrolysis by a water electrolysis stack located upstream of the water flow to be electrolyzed. A method for operating a water electrolysis hydrogen production system according to claim 11, comprising:
A method for operating a hydrogen production system using water electrolysis, comprising the steps of: reducing the amount of water electrolysis performed by a water electrolysis stack located at a more upstream side with respect to a flow of water to be electrolyzed.

Images