Water electrolysis apparatus

Abstract

A water electrolysis apparatus (100) comprises: a catalyst (52) that is disposed outside an oxygen gas-liquid separator (4) and reduces hydrogen mixed into oxygen; and an oxygen circulation line (6) in which a blower (61) is disposed and which returns oxygen that has passed through the catalyst (52) to the oxygen gas-liquid separator (4).

Description

Water electrolysis apparatus

[0001] The present disclosure relates to a water electrolysis apparatus that electrolyzes water to generate hydrogen and oxygen.

[0002] Conventionally, water electrolysis apparatuses that generate hydrogen and oxygen by electrolyzing water are known. Regarding this type of water electrolysis apparatus, Patent Document 1 discloses a technology in which a catalyst filter is disposed in an oxygen pipe that guides oxygen to the outside of the main body of the water electrolysis apparatus, to reduce hydrogen mixed into oxygen.

[0003] Japanese Unexamined Patent Publication No. 2024-117416

[0004] However, in the above-mentioned conventional technology, although the hydrogen concentration in oxygen on the downstream side (secondary side) relative to the catalyst filter is reduced, the hydrogen concentration in oxygen in the oxygen gas-liquid separator disposed on the upstream side (primary side) relative to the catalyst filter cannot be reduced.

[0005] The present disclosure has been made in view of the above-mentioned conventional problems, and an object thereof is to reduce the hydrogen concentration in oxygen in an oxygen gas-liquid separator.

[0006] In order to solve the above problems, a water electrolysis apparatus according to one aspect of the present disclosure includes: an oxygen gas-liquid separator that performs gas-liquid separation on gas-liquid mixed water supplied from a water electrolysis cell that electrolyzes water into oxygen and water; a catalyst disposed outside the oxygen gas-liquid separator and configured to reduce hydrogen mixed into the oxygen; and a circulation line that returns the oxygen that has passed through the catalyst back to the oxygen gas-liquid separator, the circulation line being provided with an air blowing unit that feeds the oxygen to the oxygen gas-liquid separator.

[0007] According to one aspect of the present disclosure, the hydrogen concentration in oxygen in the oxygen gas-liquid separator can be reduced.

[0008] It is a schematic diagram showing a configuration example of main parts of the water electrolysis apparatus according to Embodiment 1 of the present disclosure. It is a schematic diagram showing an enlarged configuration example of the oxygen circulation line and its periphery shown in FIG. 1. It is a schematic diagram showing a configuration example of main parts of the water electrolysis apparatus according to Embodiment 2 of the present disclosure. It is a schematic diagram showing an enlarged configuration example of the oxygen circulation line and its periphery shown in FIG. 3.

[0009] [Embodiment 1] An embodiment of the present disclosure will be described below. The following description is an example of a water electrolysis apparatus according to the present disclosure, and the technical scope of the present disclosure is not limited to the illustrated example.

[0010] [Configuration of the Water Electrolyzer] First, an example of the configuration of the water electrolyzer 100 according to this embodiment will be described with reference to Figure 1. Figure 1 is a schematic diagram showing an example of the main components of the water electrolyzer 100 according to this embodiment.

[0011] As shown in Figure 1, the water electrolysis apparatus 100 includes a water electrolysis cell 1, a DC power supply 2, a hydrogen vapor-liquid separator 3, an oxygen vapor-liquid separator 4, a catalytic filter 5 having a catalyst 52, and an oxygen circulation line (circulation line) 6 in which a blower 61 is located.

[0012] The water electrolysis apparatus 100 is equipped with a catalyst 52 for reducing hydrogen (hydrogen gas) mixed in with oxygen (oxygen gas). The water electrolysis apparatus 100 is configured to reduce the hydrogen concentration in the oxygen within the oxygen gas-liquid separator 4 by returning the oxygen, after the hydrogen has been reduced by the catalyst 52 located outside the oxygen gas-liquid separator 4, to the oxygen gas-liquid separator 4 via the oxygen circulation line 6.

[0013] The water electrolysis device 100 may be a solid polymer electrolyte water electrolysis device that electrolyzes pure water to generate hydrogen and oxygen by applying a voltage to a solid polymer electrolyte membrane and passing an electric current through it. The water electrolysis device 100 may be, for example, a proton exchange membrane (PEM) type water electrolysis device. However, the water electrolysis device 100 may be an anion exchange membrane (AEM) type water electrolysis device. Furthermore, the water electrolysis device 100 may be an alkaline water electrolysis device or a solid oxide type water electrolysis device, etc.

[0014] The water electrolytic cell 1 electrolyzes water using, for example, a solid polymer electrolyte membrane to generate oxygen at the anode and hydrogen at the cathode. The water electrolytic cell 1 may also be, for example, a cell stack in which a plurality of cells 11 are stacked in one direction.

[0015] A DC power supply 2 is connected to the water electrolysis cell 1. The power required for the electrolysis of water is supplied from the DC power supply 2 to the water electrolysis cell 1. In addition to power from the commercial power supply, renewable energy sources such as solar power generation and wind power generation, or surplus power from such sources, can be used as the power supplied to the water electrolysis cell 1.

[0016] The hydrogen generated at the cathode of the water electrolytic cell 1 is supplied from the water electrolytic cell 1 to the hydrogen gas-liquid separator 3 in the form of a gas-liquid mixture. The oxygen generated at the anode of the water electrolytic cell 1 is supplied from the water electrolytic cell 1 to the oxygen gas-liquid separator 4 in the form of a gas-liquid mixture.

[0017] The hydrogen vapor-liquid separator 3 separates the hydrogen-containing vapor-liquid mixture supplied from the water electrolytic cell 1 into hydrogen and water. The hydrogen after vapor-liquid separation is moist hydrogen containing a large amount of water. Therefore, the hydrogen after vapor-liquid separation is supplied through the hydrogen line 7 connected to the hydrogen vapor-liquid separator 3 to a dehumidifier or the like (not shown) to remove the water. On the other hand, the water after vapor-liquid separation may be supplied to the water electrolytic cell 1, for example, via the oxygen vapor-liquid separator 4, and reused for hydrogen generation.

[0018] The oxygen-gas-liquid separator 4 separates the oxygen-containing gas-liquid mixture supplied from the water electrolytic cell 1 into oxygen and water. The oxygen after gas-liquid separation flows into the oxygen line 8 connected to the oxygen-gas-liquid separator 4, and the hydrogen mixed in with the oxygen is reduced by passing through the catalytic filter 5 located in the oxygen line 8. After passing through the catalytic filter 5, a portion of the oxygen is returned to the oxygen-gas-liquid separator 4 through the oxygen circulation line 6, and the remainder is released into the atmosphere, for example. Meanwhile, the water after gas-liquid separation is supplied to the water electrolytic cell 1 through the water circulation line 9 connected to the oxygen-gas-liquid separator 4. The water circulation line 9 connects the water electrolytic cell 1 and the oxygen-gas-liquid separator 4, circulating water between the water electrolytic cell 1 and the oxygen-gas-liquid separator 4. A pump 91 is located in the water circulation line 9 to send water from the oxygen-gas-liquid separator 4 to the water electrolytic cell 1.

[0019] Furthermore, a pure water production device (not shown) may be connected to the oxygen vapor-liquid separator 4, and pure water obtained by treating tap water such as city water with the pure water production device may be supplied to the oxygen vapor-liquid separator 4. Also, if the water electrolysis device 100 is an alkaline water electrolysis device, the pure water may be supplied to the hydrogen vapor-liquid separator 3.

[0020] The catalytic filter 5 is located outside the oxygen-gas-liquid separator 4 and contains a catalyst 52 that reduces hydrogen mixed with oxygen. The catalyst 52 promotes the water production reaction, which generates water from hydrogen and oxygen. Therefore, the oxygen separated into gas and liquid form in the oxygen-gas-liquid separator 4 passes through the catalyst 52, thereby reducing the amount of hydrogen mixed with the oxygen.

[0021] The oxygen circulation line 6 is a return line for returning the oxygen that has passed through the catalyst 52 to the oxygen vapor-liquid separator 4. The oxygen circulation line 6 is equipped with a blower (air blower) 61 for sending the oxygen that has passed through the catalyst 52 to the oxygen vapor-liquid separator 4.

[0022] In a water electrolysis apparatus 100 with this configuration, some of the oxygen remaining after the hydrogen contamination is reduced by the catalyst 52 is returned to the oxygen vapor-liquid separator 4 through the oxygen circulation line 6. This allows for a reduction in the hydrogen concentration in the oxygen within the oxygen vapor-liquid separator 4. Furthermore, the amount of oxygen flowing from the oxygen line 8 to the oxygen circulation line 6 can be changed by controlling the operation of the blower 61. This allows for adjustment of the hydrogen concentration in the oxygen within the oxygen vapor-liquid separator 4.

[0023] [Configuration around the oxygen circulation line] Next, with reference to Figure 2, an example of the configuration of the oxygen circulation line 6 and its surroundings in the water electrolysis device 100 will be described. Figure 2 is a schematic diagram showing an enlarged view of the example of the configuration of the oxygen circulation line 6 and its surroundings shown in Figure 1.

[0024] As shown in Figure 2, in this embodiment, the catalytic filter 5 is located in the oxygen line 8 connected to the gas phase of the oxygen gas-liquid separator 4. Upstream of the catalytic filter 5, that is, between the oxygen gas-liquid separator 4 and the catalytic filter 5, a heat exchanger (cooler) 81 for cooling the oxygen and a hydrogen concentration meter 82 for detecting the hydrogen concentration in the oxygen may be installed in this oxygen line 8.

[0025] The catalytic filter 5 includes a catalytic cylinder 51 and a catalyst 52 housed in the catalytic cylinder 51. The catalytic cylinder 51 has, for example, a plurality of holes inside that allow a gas (oxygen) to pass through. The inside of the catalytic cylinder 51 may have a honeycomb structure made of, for example, ceramics.

[0026] Catalyst 52 is a hydrogen removal catalyst that promotes the water production reaction, which generates water from hydrogen and oxygen. As catalyst 52, for example, a Pd-supported catalyst, in which palladium (Pd) is supported on an alumina support, or a Pt-supported catalyst, in which platinum (Pt) is supported on an alumina support, can be used. When the oxygen separated into gas and liquid form in the oxygen-gas-liquid separator 4 passes through catalyst 52, the hydrogen and oxygen react with catalyst 52 to form water, thereby reducing the amount of hydrogen mixed with the oxygen.

[0027] The oxygen circulation line 6 is piped to return a portion of the oxygen that has passed through the catalyst 52 to the oxygen vapor-liquid separator 4. The oxygen circulation line 6 includes an upstream end 6A, which is an inlet for oxygen to flow in, and a downstream end 6B, which is an outlet for oxygen to flow out of the oxygen circulation line 6.

[0028] In this embodiment, the oxygen circulation line 6 has its upstream end 6A connected to the oxygen line 8 and its downstream end 6B connected to the oxygen gas-liquid separator 4. Specifically, the upstream end 6A of the oxygen circulation line 6 is connected to the oxygen line 8 downstream of the location of the catalyst 52. The downstream end 6B of the oxygen circulation line 6 is connected to the gas phase of the oxygen gas-liquid separator 4. As a result, the oxygen introduced from the oxygen gas-liquid separator 4 to the oxygen line 8 passes through the catalyst 52 located in the oxygen line 8 to reduce hydrogen, and then a portion of it flows back into the oxygen circulation line 6 and returns to the oxygen gas-liquid separator 4. This makes it possible to reduce the hydrogen concentration in the oxygen within the oxygen gas-liquid separator 4.

[0029] Thus, in the water electrolysis apparatus 100, the hydrogen concentration in the oxygen downstream (secondary side) of the catalyst 52 can be reduced by passing the oxygen from the oxygen-liquid separator 4 through the catalyst 52. Furthermore, by returning a portion of the oxygen that has passed through the catalyst 52 to the oxygen-liquid separator 4, the hydrogen concentration in the oxygen within the oxygen-liquid separator 4, which is located upstream of the catalyst 52, can be reduced.

[0030] Furthermore, the water electrolysis apparatus 100 includes a control unit 10 that controls each part of the water electrolysis apparatus 100. The control unit 10 performs an abnormality detection process to detect an abnormality in the water electrolysis cell 1 based on the temperature of the catalyst 52, for example.

[0031] Since the heat generated by the catalyst 52 is the heat of combustion of hydrogen mixed with oxygen, the higher the hydrogen concentration in the oxygen passing through the catalyst 52, the higher the temperature of the catalyst 52. For this reason, the control unit 10 monitors the temperature of the catalyst 52 by acquiring the detection signal from the thermometer 53 that detects the temperature of the catalyst 52 (catalyst cylinder 51). If the temperature of the catalyst 52 exceeds a predetermined threshold, the control unit 10 determines that there may be an abnormality in the water electrolytic cell 1. In this case, the control unit 10 may, for example, stop supplying power from the DC power supply 2 to the water electrolytic cell 1 and output an abnormality signal indicating that an abnormality has been detected.

[0032] Furthermore, the control unit 10 performs blower control processing, which uses an inverter to control the operation of the blower 61 located in the oxygen circulation line 6, in order to adjust the hydrogen concentration in the oxygen within the oxygen-liquid separator 4 to a desired range.

[0033] The control unit 10 may, for example, control the operation of the blower 61 according to the operating load of the water electrolytic cell 1. Normally, when the water electrolytic cell 1 is operating at a high load, the hydrogen concentration in the oxygen in the oxygen-liquid separator 4 decreases. On the other hand, when the water electrolytic cell 1 is operating at a low load, the hydrogen concentration in the oxygen in the oxygen-liquid separator 4 increases. Therefore, by controlling the operation of the blower 61 according to the operating load of the water electrolytic cell 1, it becomes easier to adjust the hydrogen concentration in the oxygen in the oxygen-liquid separator 4 to a desired range.

[0034] The control unit 10 may, for example, control the operation of the blower 61 according to the electrolysis current value or oxygen generation amount in the water electrolysis cell 1. Alternatively, the control unit 10 may acquire the detection signal from the hydrogen concentration meter 82 located in the oxygen line 8 and control the operation of the blower 61 according to the hydrogen concentration in the oxygen.

[0035] For example, if the hydrogen concentration in the oxygen within the oxygen-liquid separator 4 exceeds 40,000 ppm, there is a risk of hydrogen explosion within the oxygen-liquid separator 4. Therefore, in order to ensure sufficient safety, it is preferable for the control unit 10 to control the operation of the blower 61 so that the hydrogen concentration in the oxygen within the oxygen-liquid separator 4 can be kept below 20,000 ppm, preferably below 10,000 ppm. The capacity of the oxygen-liquid separator 4, the airflow rate of the blower 61 (blower capacity), or the amount of catalyst 52 used can be appropriately changed according to the scale of the water electrolysis apparatus 100, such as the amount of oxygen generated in the water electrolysis cell 1.

[0036] Furthermore, the control unit 10 may operate the blower 61 during the electrolysis operation of the water electrolytic cell 1 and when the electrolysis operation is stopped. For example, when converting renewable energy to hydrogen, that is, when supplying renewable energy to the water electrolytic cell 1, the electrolysis operation of the water electrolytic cell 1 may be temporarily stopped depending on the power supply situation. In this case, since the operating pressure of the water electrolytic cell 1 is maintained, cross-leakage of oxygen and hydrogen continues to occur. Therefore, when the electrolysis operation of the water electrolytic cell 1 is stopped, no new oxygen and hydrogen are generated, but existing hydrogen permeates through the polymer electrolyte membrane, causing the hydrogen concentration in oxygen within the oxygen-liquid separator 4 to rise. By continuing to operate the blower 61 not only during the electrolysis operation of the water electrolytic cell 1 but also when the electrolysis operation is stopped, the rise in the hydrogen concentration in oxygen within the oxygen-liquid separator 4 during the electrolysis operation stoppage can be suppressed, and the hydrogen concentration in oxygen can be reduced.

[0037] Thus, even when the electrolysis operation of the water electrolytic cell 1 is stopped, the blower 61 may be operated if the water electrolytic cell 1 has operating pressure. This allows, for example, the hydrogen concentration in the oxygen in the oxygen vapor-liquid separator 4 to be sufficiently reduced while the electrolysis operation of the water electrolytic cell 1 is stopped, and the oxygen vapor-liquid separator 4 to be kept on standby until the electrolysis operation is restarted with a low hydrogen concentration in the oxygen vapor-liquid separator 4. Furthermore, for example, if the water electrolytic cell 1 is completely stopped and the operating pressure of the water electrolytic cell 1 is reduced to depressurize it, the blower 61 may be stopped.

[0038] [Effects of the Water Electrolyzer] As described above, the water electrolyzer 100 according to this embodiment includes an oxygen-gas-liquid separator 4 that separates the gas-liquid mixed water supplied from the water electrolyzer cell 1 that electrolyzes water into oxygen and water, a catalyst 52 that is placed outside the oxygen-gas-liquid separator 4 to reduce hydrogen mixed in with the oxygen, and an oxygen circulation line 6 that returns the oxygen that has passed through the catalyst 52 to the oxygen-gas-liquid separator 4, and an oxygen circulation line 6 in which a blower 61 that sends oxygen to the oxygen-gas-liquid separator 4 is arranged.

[0039] In the water electrolysis apparatus 100, the oxygen, after the hydrogen mixed with it has been reduced by the catalyst 52, is returned to the oxygen vapor-liquid separator 4. Therefore, the hydrogen concentration in the oxygen within the oxygen vapor-liquid separator 4 can be reduced. Furthermore, in the water electrolysis apparatus 100, the oxygen circulating through the oxygen circulation line 6 repeatedly passes through the catalyst 52. Therefore, the hydrogen mixed with the oxygen can be efficiently reduced. Moreover, in the water electrolysis apparatus 100, the amount of oxygen flowing through the oxygen circulation line 6 (the amount of oxygen passing through the catalyst 52) ​​can be changed by controlling the operation of the blower 61. Therefore, the hydrogen concentration in the oxygen within the oxygen vapor-liquid separator 4 can be adjusted.

[0040] Furthermore, the water electrolysis apparatus 100 according to this embodiment is connected to an oxygen-gas-liquid separator 4 and includes an oxygen line 8 that guides oxygen to the outside of the oxygen-gas-liquid separator 4. The catalyst 52 is placed in the oxygen line 8, the upstream end 6A of the oxygen circulation line 6 is connected to the oxygen line 8 downstream of the catalyst 52's position, and the downstream end 6B of the oxygen circulation line 6 is connected to the oxygen-gas-liquid separator 4.

[0041] In the water electrolysis apparatus 100, the oxygen guided from the oxygen gas-liquid separator 4 to the oxygen line 8 passes through the catalyst 52 disposed in the oxygen line 8, after which a part of the oxygen flows into the oxygen circulation line 6 and is returned to the oxygen gas-liquid separator 4. Therefore, according to the water electrolysis apparatus 100, the concentration of hydrogen in oxygen within the oxygen gas-liquid separator 4 can be reduced.

[0042] [Embodiment 2] Other embodiments of the present disclosure will be described below. For convenience of explanation, members having the same functions as those described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

[0043] [Configuration of Water Electrolysis Apparatus] First, a configuration example of the water electrolysis apparatus 101 according to the present embodiment will be described with reference to FIG. 3. FIG. 3 is a schematic diagram showing a configuration example of main parts of the water electrolysis apparatus 101 according to the present embodiment.

[0044] As shown in FIG. 3, the water electrolysis apparatus 101 includes a water electrolysis cell 1, a DC power supply 2, a hydrogen gas-liquid separator 3, an oxygen gas-liquid separator 4, a catalyst filter 5 having a catalyst 52, and an oxygen circulation line (circulation line) 60 provided with a blower 61. The water electrolysis apparatus 101 according to the present embodiment mainly differs from the water electrolysis apparatus 100 according to the above embodiment in that the catalyst filter 5 and a hydrogen concentration meter 82 are disposed in the oxygen circulation line 60.

[0045] [Configuration Around Oxygen Circulation Line] Next, a configuration example of the oxygen circulation line 60 and its periphery of the water electrolysis apparatus 101 will be described with reference to FIG. 4. FIG. 4 is an enlarged schematic diagram showing a configuration example of the oxygen circulation line 60 shown in FIG. 3 and its periphery.

[0046] As shown in FIG. 4, in the water electrolysis apparatus 101, the catalyst filter 5 is disposed in the oxygen circulation line 60. In the present embodiment, the catalyst filter 5 is disposed in the oxygen circulation line 60 on the downstream side of the position where the blower 61 is provided. Further, in the water electrolysis apparatus 101, a hydrogen concentration meter 82 is disposed in the oxygen circulation line 60. In the present embodiment, the hydrogen concentration meter 82 is disposed in the oxygen circulation line 60 between the blower 61 and the catalyst filter 5.

[0047] Further, the upstream end 6A of the oxygen circulation line 60 is not connected to the oxygen line 8, but is connected to the oxygen gas-liquid separator 4. That is, in the water electrolysis apparatus 101, the catalyst 52 is disposed in the oxygen circulation line 60, and each of the upstream end 6A and the downstream end 6B of the oxygen circulation line 60 is connected to the gas phase portion of the oxygen gas-liquid separator 4. Therefore, a part of the oxygen in the oxygen gas-liquid separator 4 directly flows into the oxygen circulation line 60, passes through the catalyst 52 disposed in the oxygen circulation line 60, and then is returned to the oxygen gas-liquid separator 4. Thereby, the hydrogen concentration in the oxygen within the oxygen gas-liquid separator 4 can be reduced.

[0048] [Operational Effects of Water Electrolysis Apparatus] As described above, the water electrolysis apparatus 101 according to the present embodiment includes the oxygen gas-liquid separator 4 that performs gas-liquid separation on gas-liquid mixed water supplied from the water electrolysis cell 1 for electrolyzing water into oxygen and water, the catalyst 52 disposed outside the oxygen gas-liquid separator 4 for reducing hydrogen mixed in oxygen, and the oxygen circulation line 60 that returns oxygen having passed through the catalyst 52 to the oxygen gas-liquid separator 4, wherein the oxygen circulation line 60 is provided with a blower 61 that sends oxygen to the oxygen gas-liquid separator 4.

[0049] According to the water electrolysis apparatus 101, by returning, to the oxygen gas-liquid separator 4, the oxygen after hydrogen mixed therein is reduced by the catalyst 52, the hydrogen concentration in the oxygen within the oxygen gas-liquid separator 4 can be reduced. Further, according to the water electrolysis apparatus 101, oxygen circulating through the oxygen circulation line 60 repeatedly passes through the catalyst 52. Therefore, hydrogen mixed in oxygen can be efficiently reduced. Furthermore, according to the water electrolysis apparatus 101, by controlling the operation of the blower 61, the amount of oxygen flowing through the oxygen circulation line 60 (the amount of oxygen passing through the catalyst 52) can be changed. Therefore, the hydrogen concentration in the oxygen within the oxygen gas-liquid separator 4 can be adjusted.

[0050] Further, in the water electrolysis apparatus 101 according to the present embodiment, the catalyst 52 is disposed in the oxygen circulation line 60, and each of the upstream end 6A and the downstream end 6B of the oxygen circulation line 60 is connected to the oxygen gas-liquid separator 4.

[0051] In the water electrolysis apparatus 101, the oxygen in the oxygen-liquid separator 4 flows directly into the oxygen circulation line 60, passes through the catalyst 52 located in the oxygen circulation line 60, and is then returned to the oxygen-liquid separator 4. Therefore, the water electrolysis apparatus 101 makes it possible to reduce the hydrogen concentration in the oxygen within the oxygen-liquid separator 4.

[0052] [Summary] The water electrolysis apparatus according to Embodiment 1 of the present disclosure includes an oxygen-gas-liquid separator that separates gas-liquid mixed water supplied from a water electrolysis cell into oxygen and water, a catalyst disposed outside the oxygen-gas-liquid separator to reduce hydrogen mixed in with the oxygen, and a circulation line (oxygen circulation line 6, 60) that returns the oxygen that has passed through the catalyst to the oxygen-gas-liquid separator, the circulation line having a blower (blower 61) that sends the oxygen to the oxygen-gas-liquid separator.

[0053] According to the above configuration, the hydrogen concentration in the oxygen within the oxygen-gas-liquid separator can be reduced by returning the oxygen, after the hydrogen mixed with oxygen has been reduced by a catalyst, to the oxygen-gas-liquid separator. Furthermore, according to the above configuration, the amount of oxygen flowing through the circulation line can be changed by controlling the operation of the blower. Therefore, the hydrogen concentration in the oxygen within the oxygen-gas-liquid separator can be adjusted.

[0054] In the water electrolysis apparatus according to embodiment 2 of the present disclosure, in embodiment 1, the air blower may operate in accordance with the operating load of the water electrolysis cell.

[0055] According to the above configuration, the blower operates in accordance with the operating load of the water electrolytic cell. Therefore, by changing the amount of oxygen flowing through the circulation line according to the amount of oxygen generated in the water electrolytic cell, for example, it becomes easier to adjust the hydrogen concentration in the oxygen within the oxygen-liquid separator to a desired range.

[0056] In the water electrolysis apparatus according to embodiment 3 of the present disclosure, in embodiment 1 or 2, the blower unit may operate during the electrolysis operation of the water electrolysis cell and when the electrolysis operation is stopped.

[0057] In the above configuration, the blower operates not only during the electrolysis operation of the water electrolytic cell but also when the electrolysis operation is stopped. Therefore, the hydrogen concentration in the oxygen in the oxygen-liquid separator can be efficiently reduced when the electrolysis operation is stopped. Accordingly, with the above configuration, for example, when the electrolysis operation of the water electrolytic cell is stopped, the hydrogen concentration in the oxygen-liquid separator can be sufficiently reduced, and the oxygen-liquid separator can be kept in standby mode until the electrolysis operation is restarted with a low hydrogen concentration in the oxygen-liquid separator.

[0058] In the water electrolysis apparatus according to embodiment 4 of the present disclosure, in any of embodiments 1 to 3, the apparatus further comprises an oxygen line connected to the oxygen gas-liquid separator and for leading the oxygen to the outside of the oxygen gas-liquid separator, the catalyst is arranged in the oxygen line, the upstream end of the circulation line is connected to the oxygen line downstream of the catalyst's position, and the downstream end of the circulation line is connected to the oxygen gas-liquid separator.

[0059] In the above configuration, oxygen introduced from the oxygen-gas-liquid separator to the oxygen line passes through a catalyst placed in the oxygen line, and a portion of it flows into the circulation line and is returned to the oxygen-gas-liquid separator. Therefore, the hydrogen concentration in the oxygen within the oxygen-gas-liquid separator can be reduced.

[0060] In the water electrolysis apparatus according to embodiment 5 of the present disclosure, in any of embodiments 1 to 3, the catalyst may be arranged in the circulation line, and the upstream and downstream ends of the circulation line may each be connected to the oxygen vapor-liquid separator.

[0061] In the above configuration, the oxygen in the oxygen-gas-liquid separator flows directly into the circulation line, passes through a catalyst placed in the circulation line, and is then returned to the oxygen-gas-liquid separator. Therefore, the hydrogen concentration in the oxygen within the oxygen-gas-liquid separator can be reduced.

[0062] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this disclosure.

[0063] 1: Water electrolytic cell 4: Oxygen vapor-liquid separator 6, 60: Oxygen circulation line (circulation line) 6A: Upstream end 6B: Downstream end 8: Oxygen line 10: Control unit 61: Blower (air blower) 100, 101: Water electrolytic device

Claims

1. A water electrolysis apparatus comprising: an oxygen-gas-liquid separator that separates gas-liquid mixed water supplied from a water electrolysis cell into oxygen and water; a catalyst disposed outside the oxygen-gas-liquid separator for reducing hydrogen mixed in with the oxygen; and a circulation line that returns the oxygen that has passed through the catalyst to the oxygen-gas-liquid separator, the circulation line having a blower for sending the oxygen to the oxygen-gas-liquid separator.

2. The water electrolysis apparatus according to claim 1, wherein the blowing unit operates in accordance with the operating load of the water electrolysis cell.

3. The water electrolysis apparatus according to claim 1 or 2, wherein the blowing unit operates during the electrolysis operation of the water electrolysis cell and when the electrolysis operation is stopped.

4. The water electrolysis apparatus according to claim 1 or 2, further comprising an oxygen line connected to the oxygen gas-liquid separator and leading the oxygen to the outside of the oxygen gas-liquid separator, wherein the catalyst is arranged in the oxygen line, the upstream end of the circulation line is connected to the oxygen line downstream of the location of the catalyst, and the downstream end of the circulation line is connected to the oxygen gas-liquid separator.

5. The water electrolysis apparatus according to claim 1 or 2, wherein the catalyst is arranged in the circulation line, and the upstream and downstream ends of the circulation line are connected to the oxygen vapor-liquid separator.

Images