Water electrolysis device

Abstract

A water electrolysis device (100) comprises a deaeration cylinder (30) that removes the hydrogen in hydrogen blow-off water that has been isolated by a hydrogen gas / liquid separator (12). The deaeration cylinder (30) has an inlet (31A) into which the hydrogen blow-off water flows and an outlet (31B) that is at a lower height position in the vertical direction than the inlet (31A). The hydrogen blow-off water that flows into the inlet (31A) forms a swirling flow (T) inside the deaeration cylinder (30), causing the hydrogen in the hydrogen blow-off water to form bubbles.

Description

Water electrolysis device

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

[0002] Conventionally, hydrogen production technologies using natural energy as primary energy have been developed, and one of them is a solid polymer type water electrolysis device (Patent Document 1). In this type of water electrolysis device, the hydrogen blow water (separated water) discharged from a hydrogen gas-liquid separator that separates hydrogen generated at the cathode of the water electrolysis cell from water is returned to a water storage tank and reused for hydrogen production.

[0003] Japanese Patent Application Laid-Open No. 2002-173788

[0004] By the way, hydrogen is dissolved in the hydrogen blow water discharged from the hydrogen gas-liquid separator. Therefore, for safety reasons, measures against hydrogen in the hydrogen blow water are required.

[0005] As measures against hydrogen in this hydrogen blow water, for example, the following methods can be considered. A method of introducing dilution air into the upper part of the water storage tank to dilute hydrogen gas, or a method of gas-liquid separation of the hydrogen gas contained in the hydrogen blow water by gravity using the specific gravity difference between gas and liquid, similar to the hydrogen gas-liquid separator, and releasing the hydrogen gas to the atmosphere.

[0006] However, when diluting hydrogen gas with dilution air, in order to make the hydrogen gas at a safe concentration, a device for supplying a huge amount of dilution air is separately required.

[0007] Also, when gas-liquid separation of the hydrogen gas contained in the hydrogen blow water by gravity using the specific gravity difference between gas and liquid, since the hydrogen gas contained in the hydrogen blow water is fine bubbles, it is necessary to slow down the flow rate of the hydrogen blow water. Since the amount of the hydrogen blow water is proportional to the amount of hydrogen generated, in a large solid polymer type water electrolysis device, it is necessary to make the pipe diameter of the hydrogen blow water very large.

[0008] The present disclosure has been made in view of the above conventional problems, and an object thereof is to remove hydrogen contained in hydrogen blow water without increasing the size of the water electrolysis device.

[0009] To solve the above problems, a water electrolysis apparatus according to one aspect of the present disclosure comprises a water electrolysis cell that electrolyzes water using a polymer electrolyte membrane to generate hydrogen at the cathode, a hydrogen vapor-liquid separator that separates the hydrogen generated at the cathode from water, and a deaeration cylinder that removes hydrogen contained in the separated water separated by the hydrogen vapor-liquid separator, wherein the deaeration cylinder has an inlet for the separated water to flow in and an outlet located at a vertical height lower than the inlet, and the separated water flowing in from the inlet forms a swirling flow inside the deaeration cylinder, thereby converting the hydrogen contained in the separated water into bubbles.

[0010] According to one aspect of this disclosure, hydrogen contained in hydrogen blowdown water can be removed without increasing the size of the water electrolysis apparatus.

[0011] This is a block diagram showing the schematic configuration of a water electrolysis apparatus according to Embodiment 1. This is a schematic diagram showing the peripheral configuration of the deaeration cylinder shown in Figure 1. This is a plan view showing the body of the deaeration cylinder shown in Figure 2. This is a block diagram showing a modified example of the water electrolysis apparatus shown in Figure 1. This is a block diagram showing the schematic configuration of the main part of a water electrolysis apparatus according to Embodiment 2. This is a side view showing an example of the configuration of the filter device shown in Figure 5. This is a schematic diagram explaining the function of the filter shown in Figure 6. This is a longitudinal cross-sectional view showing an example of the configuration of the gas venting valve shown in Figure 5. This is a block diagram showing a first modified example of the water electrolysis apparatus shown in Figure 5. This is a block diagram showing a second modified example of the water electrolysis apparatus shown in Figure 5. This is a block diagram showing a third modified example of the water electrolysis apparatus shown in Figure 5. This is a block diagram showing a fourth modified example of the water electrolysis apparatus shown in Figure 5.

[0012] [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.

[0013] [Configuration of Water Electrolyzer 100] Figure 1 is a block diagram showing the schematic configuration of the water electrolyzer 100 according to this embodiment. As shown in Figure 1, the water electrolyzer 100 includes a water electrolytic cell 10, a DC power supply 11, a hydrogen vapor-liquid separator 12, an oxygen vapor-liquid separator 13, and a degassing cylinder 30.

[0014] In the water electrolysis apparatus 100, the hydrogen blowdown water (separated water) discharged from the hydrogen gas-liquid separator 12 forms a swirling flow inside the degassing cylinder 30, thereby converting the hydrogen contained in the hydrogen blowdown water into bubbles. This makes it possible to remove the hydrogen contained in the hydrogen blowdown water without increasing the size of the water electrolysis apparatus 100.

[0015] The water electrolytic cell 10 uses a polymer electrolyte membrane to electrolyze (decompose) water, generating oxygen at the anode and hydrogen at the cathode. A DC power supply 11 is connected to the water electrolytic cell 10. The power required for the electrolysis of water is supplied to the water electrolytic cell 10 from the DC power supply 11. In addition to power from the commercial power supply, renewable energy sources such as solar power generation and wind power generation, or surplus electricity, can be used to supply power to the water electrolytic cell 10.

[0016] The hydrogen generated at the cathode of the water electrolytic cell 10 is supplied from the water electrolytic cell 10 to the hydrogen gas-liquid separator 12 in the form of a gas-liquid mixture. The oxygen generated at the anode of the water electrolytic cell 10 is supplied from the water electrolytic cell 10 to the oxygen gas-liquid separator 13 in the form of a gas-liquid mixture.

[0017] The hydrogen gas-liquid separator 12 separates the hydrogen-containing gas-liquid mixture supplied from the water electrolytic cell 10 into hydrogen and water. The hydrogen (hydrogen gas) after gas-liquid separation is moist hydrogen containing a large amount of water. Therefore, the hydrogen after gas-liquid separation is supplied to a dehumidifier (not shown) or the like to have the water removed. On the other hand, the water after gas-liquid separation is supplied to the deaeration cylinder 30 as hydrogen blowdown water (separated water) through the blowdown water line 19 connecting the hydrogen gas-liquid separator 12 and the deaeration cylinder 30.

[0018] In the deaeration cylinder 30, hydrogen gas dissolved in the hydrogen blowdown water is removed. The deaeration case 32 of the deaeration cylinder 30 is connected to the hydrogen exhaust line 19A, and the hydrogen removed from the hydrogen blowdown water is discharged from the deaeration case 32 to the hydrogen exhaust line 19A. In addition, the hydrogen-removed water (removed water) from which hydrogen has been removed in the deaeration cylinder 30 is supplied to the oxygen gas-liquid separator 13 through the removed water line 19B that connects the deaeration cylinder 30 and the oxygen gas-liquid separator 13.

[0019] The blowdown water line 19 supplies hydrogen blowdown water from the hydrogen gas-liquid separator 12 to the deaeration cylinder 30. The blowdown water line 19 has an electric valve 20 and a deaeration cylinder 30 arranged from the upstream side. In addition, a check valve (backflow prevention mechanism) 22 is arranged in the hydrogen exhaust line 19A.

[0020] The electric valve (flow rate adjustment mechanism) 20 adjusts the flow rate of hydrogen blowdown water flowing through the blowdown water line 19 by changing the valve opening, utilizing the internal pressure difference between the hydrogen gas-liquid separator 12 and the oxygen gas-liquid separator 13. In addition, by adjusting the valve opening, the electric valve 20 reduces the pressure of the hydrogen blowdown water flowing through the blowdown water line 19, making the pressure on the oxygen gas-liquid separator 13 side lower than the pressure on the hydrogen gas-liquid separator 12 side.

[0021] Here, while the water electrolytic cell 10 is operating, the hydrogen gas-liquid separator 12 is pressurized, so the hydrogen blowdown water released from the hydrogen gas-liquid separator 12 is under high pressure. Hydrogen is dissolved in this high-pressure hydrogen blowdown water and it contains hydrogen. When the hydrogen blowdown water flowing through the blowdown water line 19 is depressurized by the electric valve 20, some of the dissolved hydrogen becomes fine bubbles in the hydrogen blowdown water.

[0022] The deaeration cylinder 30 is a deaeration device that removes hydrogen by converting the hydrogen contained in the hydrogen blowdown water into bubbles. In this embodiment, the deaeration cylinder 30 includes a body 31 that converts the hydrogen contained in the hydrogen blowdown water into bubbles, and a deaeration case 32 provided on the upper part of the body 31.

[0023] The fuselage 31 is configured such that the supplied hydrogen blowdown water forms a swirling flow (vortex flow) inside the fuselage 31, thereby converting the hydrogen contained in the hydrogen blowdown water into bubbles. The degassing case 32 is configured to discharge the bubbles of hydrogen from the fuselage 31. Details of the degassing cylinder 30 will be described later.

[0024] The oxygen-gas-liquid separator 13 separates the oxygen-containing gas-liquid mixture supplied from the water electrolytic cell 10 into oxygen and water. The oxygen (oxygen gas) after gas-liquid separation is released into the atmosphere, for example. Meanwhile, the water after gas-liquid separation is supplied to the water electrolytic cell 10 as oxygen-side circulating water through the oxygen-side circulation line 17 of the water electrolytic device 100.

[0025] The oxygen-side circulation line 17 circulates water between the water electrolytic cell 10 and the oxygen vapor-liquid separator 13. A pump 14 is located in the oxygen-side circulation line 17 to send the oxygen-side circulating water from the oxygen vapor-liquid separator 13 to the water electrolytic cell 10.

[0026] In the water electrolysis apparatus 100, the hydrogen-free water from which hydrogen has been removed in the deaeration cylinder 30 is supplied to the oxygen vapor-liquid separator 13. Therefore, the hydrogen-free water from which hydrogen has been removed in the deaeration cylinder 30 can be reused for hydrogen generation in the water electrolysis cell 10.

[0027] Furthermore, the oxygen vapor-liquid separator 13 may be supplied with pure water, such as tap water treated by a pure water production device (not shown).

[0028] [Configuration of the Deaeration Cylinder 30] Next, an example of the configuration of the deaeration cylinder 30 provided in the water electrolysis device 100 will be described. Figure 2 is a schematic diagram showing the surrounding configuration of the deaeration cylinder 30 shown in Figure 1. Figure 3 is a plan view showing the body 31 of the deaeration cylinder 30 shown in Figure 2. As shown in Figure 2, an electric valve (flow rate adjustment mechanism) 20 is arranged on the upstream side of the deaeration cylinder 30. In addition, a T-shaped branched cheese pipe (gas-liquid separation mechanism) 21 is arranged in the removed water line 19B on the downstream side of the deaeration cylinder 30. This cheese pipe 21 is connected to the hydrogen exhaust line 19A and may be configured to discharge hydrogen gas remaining in the hydrogen-removed water to the hydrogen exhaust line 19A.

[0029] The deaeration cylinder 30 removes hydrogen contained in the hydrogen blowdown water flowing through the blowdown water line 19 by creating bubbles. The deaeration cylinder 30 is positioned vertically (up and down) in the blowdown water line 19. In this embodiment, the deaeration cylinder 30 is connected to the blowdown water line 19 and comprises a body 31 that creates bubbles of hydrogen contained in the hydrogen blowdown water, and a deaeration case 32 connected to the upper part of the body 31 and discharges the hydrogen created by bubbles in the body 31. The upper end of the body 31 and the lower end of the deaeration case 32 are in internal communication with each other via a connecting part 33.

[0030] (Body 31) The body 31 is a cylindrical housing. The body 31 has an inlet 31A for introducing hydrogen blowdown water and an outlet 31B located at a vertical height lower than the inlet 31A. In this embodiment, the body 31 has an inlet 31A on the outer circumference of the upper end of the body 31, and an inlet pipe 311 is provided in this inlet 31A. The body 31 also has an outlet 31B on the outer circumference of the lower end of the body 31, and an outlet pipe 312 is provided in this outlet 31B.

[0031] Furthermore, if the outlet 31B is located higher than the inlet 31A relative to the fuselage 31, or if the inlet 31A and outlet 31B are located at the same height, hydrogen bubbles B will be discharged from the outlet 31B, significantly reducing the efficiency of hydrogen removal from the hydrogen blowdown water. For this reason, in order to properly remove hydrogen from the hydrogen blowdown water, it is necessary to position the outlet 31B lower than the inlet 31A.

[0032] The inlet pipe 311 is connected to the supply pipe 41 that constitutes the upstream blowdown water line 19, and supplies the hydrogen blowdown water discharged from the hydrogen gas-liquid separator 12 to the body 31. The outlet pipe 312 is connected to the discharge pipe 42 that constitutes the downstream removal water line 19B, and discharges the hydrogen-removed water, from which hydrogen has been removed from the hydrogen blowdown water, to the discharge pipe 42.

[0033] The inlet pipe 311 is a cylindrical pipe with an inner diameter D1, and the outlet pipe 312 is a cylindrical pipe with an inner diameter D2. Both the inlet pipe 311 and the outlet pipe 312 are installed horizontally to the body 31.

[0034] The inlet pipe 311 is positioned eccentrically from the central axis C3 of the body 31, and is, for example, parallel to the tangent to the inscribed circle of the body 31. As a result, the hydrogen blow-off water ejected from the inlet pipe 311 into the body 31 forms a swirling flow (vortex flow) T. The hydrogen contained in the hydrogen blow-off water is attracted to the central axis C3 of the body 31 by the centrifugal force of the swirling flow T, causing hydrogen bubbles B to aggregate and increasing their size.

[0035] Furthermore, if the degassing cylinder 3 is positioned horizontally (left-right) so that the central axis C3 of the fuselage 31 is horizontal, hydrogen bubbles B will not easily accumulate at the center of the swirling flow T (the central axis C3 of the fuselage 31), making it difficult to separate hydrogen using gravity. For this reason, in order to properly remove hydrogen contained in the hydrogen blowdown water, it is necessary to position the degassing cylinder 3 vertically (up and down).

[0036] In this embodiment, as shown in the plan view in Figure 3, the inlet pipe 311 and the outlet pipe 312 are parallel to each other, and the outlet pipe 312 is provided on the body 31 such that its central axis C2 passes through (is perpendicular to) the central axis C3 of the body 31. On the other hand, the inlet pipe 311 is provided eccentrically from the central axis C3 of the body 31, with its central axis C1 offset radially by a gap I relative to the central axis C2 of the outlet pipe 312. The value of this gap I is, for example, 60 mm to 80 mm when the inner diameter D3 of the body 31 is 190 mm, and in this embodiment, the gap I is set to 70 mm.

[0037] Furthermore, in the plan view shown in Figure 3, if the point where the central axis C1 of the inlet pipe 311 intersects with the inner wall of the body 31 is defined as intersection point P, then the straight line connecting the central axis C3 of the body 31 and intersection point P forms an angle θ with the central axis C2 of the outlet pipe 312, which passes through the center M of the body 31. The value of this angle θ is, for example, between 120 degrees and 140 degrees, and in this embodiment, the angle θ is set to 133 degrees.

[0038] In the fuselage 31, hydrogen contained in the hydrogen blow-off water is separated using the centrifugal force of the swirling flow T. Therefore, in order to avoid hindering the rise of hydrogen bubbles B formed by the swirling flow T, and to suitably collect the hydrogen bubbles B on the central axis C3 of the fuselage 31 using the swirling flow T, it is important to set the ratio D3 / D1 of the inner diameter D1 of the inlet pipe 311 to the inner diameter D3 of the fuselage 31 to an appropriate value.

[0039] For example, when separating hydrogen bubbles B with a diameter of 0.2 mm or less from hydrogen blow water in the fuselage 31, it is preferable that the downward flow velocity of the hydrogen blow water (swirling flow T) inside the fuselage 31 is 0.1 m / s or less. Furthermore, it is preferable that the time the hydrogen blow water remains inside the fuselage 31, that is, the time from when the hydrogen blow water is supplied from the inlet 31A of the fuselage 31 until it is discharged from the outlet 31B, is 20 seconds or more. By forming a swirling flow T that satisfies the above conditions, the upward movement of hydrogen bubbles B is not hindered, and the hydrogen bubbles B can be suitably collected on the central axis C3 of the fuselage 31 by the swirling flow T. For this reason, it is necessary to set the ratio D3 / D1 to an appropriate value so that such a swirling flow T is formed inside the fuselage 31.

[0040] The downward flow velocity V of the hydrogen blow water (swirling flow T) inside the fuselage 31 can be calculated, for example, using the following formula (1): V = 4F / (3600 × π × D3 ２ ) ... (1) F: Hydrogen blowdown water volume (m ３ / h) D3: Inner diameter of the body 31 (m) The inner diameter D1 of the inlet pipe 311 depends on the amount of hydrogen blowdown water F flowing into the body 31. For this reason, for example, the ratio D3 / D1 of the inner diameter D1 of the inlet pipe 311 and the inner diameter D3 of the body 31 can be determined using the above calculation formula (1) so that the downward flow velocity V is a desired value.

[0041] Furthermore, the amount of dissolved hydrogen contained in the hydrogen blowdown water changes depending on the hydrogen generation pressure in the water electrolytic cell 10. For this reason, the preferred value of the ratio D3 / D1 also differs depending on the hydrogen generation pressure.

[0042] Table 1 shows an example of the ratio D3 / D1 and the downward flow velocity V when the hydrogen generation pressure in the water electrolytic cell 10 is 0.8 MPa.

[0043] As shown in Table 1, in the configuration of sample number case 1, the ratio D3 / D1 was approximately 5.0, and the downward flow velocity V in this case was 0.09 m / s. In the configuration of sample number case 2, the ratio D3 / D1 was approximately 6.2, and the downward flow velocity V in this case was 0.07 m / s. Furthermore, in the configuration of sample number case 3, the ratio D3 / D1 was approximately 6.8, and the downward flow velocity V in this case was 0.03 m / s.

[0044] Further, Table 2 shows an example of the ratio D3 / D1 and the descending flow velocity V when the hydrogen generation pressure in the water electrolysis cell 10 is 3.0 MPa.

[0045] As shown in Table 2, in the configuration of sample number case 1, the ratio D3 / D1 was about 14.3, and the descending flow velocity V in this case was 0.01 m / s. Also, in the configuration of sample number case 2, the ratio D3 / D1 was about 14.8, and the descending flow velocity V in this case was 0.01 m / s. Furthermore, in the configuration of sample number case 3, the ratio D3 / D1 was about 16.6, and the descending flow velocity V in this case was 0.01 m / s.

[0046] Thus, it is preferable to set the ratio D3 / D1 of the inner diameter D1 of the inlet pipe 311 to the inner diameter D3 of the body 31 so that the descending flow velocity V of the hydrogen blow water (swirling flow T) inside the body 31 becomes 0.1 m / s or less. Thereby, while setting the deaeration cylinder outlet pressure to an appropriate value, it is possible to prevent the rise of the hydrogen bubbles B and to preferably gather the hydrogen bubbles B around the central axis C3 of the body 31 by the swirling flow T.

[0047] In addition, in order to efficiently vaporize the hydrogen (hydrogen gas) dissolved in the hydrogen blow water, it is preferable that the inside of the body 31 is at a low pressure of about atmospheric pressure. However, in order to transfer the hydrogen blow water (hydrogen removal water) to the oxygen gas-liquid separator 13 side by utilizing the internal pressure difference between the hydrogen gas-liquid separator 12 and the oxygen gas-liquid separator 13, it is necessary that the internal pressure of the body 31 is at least higher than the internal pressure of the oxygen gas-liquid separator 13.

[0048] In addition, the inner wall of the body 31 may be provided with an inclination angle so as to reduce the diameter downward. Thereby, the flow velocity of the swirling flow T increases, and the hydrogen bubbles B can be effectively polymerized inside the body 31. The inclination angle of the inner wall may be, for example, 10 degrees or more and 20 degrees or less with respect to the vertical direction.

[0049] (Deaeration case 32) The deaeration case 32 is connected to the upper part of the body 31 and discharges the hydrogen bubbles B generated in the body 31. The deaeration case 32 includes a case 321, a float 322, a valve seat 323, and a discharge port 324.

[0050] Hydrogen bubbles B generated in the body 31 flow into case 321 via the connecting part 33. As hydrogen bubbles B accumulate inside case 321, the liquid level of the hydrogen blowdown water inside case 321 decreases, causing the float 322 to descend. As the float 322 descends, it separates from the valve seat 323 and opens, and the hydrogen bubbles B accumulated inside case 321 are discharged as hydrogen gas from the outlet 324 into the hydrogen exhaust line 19A. On the other hand, once the hydrogen is discharged, the liquid level of the hydrogen blowdown water inside case 321 increases, causing the float 322 to rise. As the float 322 rises, it contacts the valve seat 323 and closes, stopping the discharge of hydrogen gas from the outlet 324.

[0051] The outlet 324 of the degassing case 32 is connected to the hydrogen exhaust line 19A. Specifically, the outlet 324 is connected to the hydrogen exhaust line 19A between the cheese pipe 21 and the check valve 22. In the cheese pipe 21, hydrogen remaining in the hydrogen blowdown water that has passed through the body 31, that is, hydrogen that was not bubbled and removed in the body 31, flows into the hydrogen exhaust line 19A as hydrogen gas. The hydrogen gas discharged from the outlet 324 is exhausted through the hydrogen exhaust line 19A together with the hydrogen gas that has flowed into the hydrogen exhaust line 19A from the cheese pipe 21.

[0052] The degassing case 32 only needs to be positioned in a location that allows hydrogen to be discharged from the fuselage 31. The degassing case 32 may, for example, be located inside the fuselage 31.

[0053] In the water electrolysis apparatus 100 equipped with the degassing cylinder 30 as described above, hydrogen blowdown water is transferred from the hydrogen gas-liquid separator 12 to the oxygen gas-liquid separator 13 due to the internal pressure difference between the hydrogen gas-liquid separator 12 and the oxygen gas-liquid separator 13. Therefore, there is no need to install pumps, blowers, etc., in the blowdown water line 19 to send out the hydrogen blowdown water, simplifying the configuration of the water electrolysis apparatus 100 and making maintenance easier.

[0054] Furthermore, the discharge-side piping 42 connected to the outlet pipe 312 of the deaeration cylinder 30 may include a rising portion 42A that extends to a vertical height position higher than the upper end (upper end) 30A of the deaeration cylinder 30 (deaeration case 32). By installing the discharge-side piping 42 so as to pass at a position higher than the upper end 30A of the deaeration case 32 of the deaeration cylinder 30, the deaeration cylinder 30 can be liquid-sealed with hydrogen blowdown water to prevent outside air from flowing into the deaeration cylinder 30. In addition, since the inside of the deaeration cylinder 30, that is, the inside of the body 31 and the deaeration case 32, is filled with hydrogen blowdown water, hydrogen bubbles B generated in the body 31 can be suitably pushed up to the deaeration case 32. A vortex breaker, valve, orifice, etc. may be provided in the discharge-side piping 42 to prevent the gas column inside the body 31 from being drawn into the outlet pipe 312.

[0055] Furthermore, in the water electrolysis apparatus 100, the hydrogen-free water from which hydrogen has been removed in the degassing cylinder 30 may be supplied to the gas phase section G of the oxygen gas-liquid separator 13. This reduces the influence of pressure (internal pressure) due to changes in the liquid level of the oxygen gas-liquid separator 13, and allows for a stable supply of hydrogen-free water to the oxygen gas-liquid separator 13 by utilizing the internal pressure difference between the hydrogen gas-liquid separator 12 and the oxygen gas-liquid separator 13.

[0056] [Operating principle of the venting cylinder 30] Next, the operating principle of the venting cylinder 30 will be explained. In the initial state of the venting cylinder 30, the float 322 of the venting case 32 is positioned upward due to the buoyancy of the hydrogen blow water inside the case 321 and is in contact with the valve seat 323. As a result, the outlet 324 is closed by the float 322, the hydrogen blow water is not discharged from the outlet 324 of the case 321, and the internal pressure of the venting cylinder 30 is maintained.

[0057] In the initial state of the degassing cylinder 30, hydrogen blowdown water flows in from an inlet pipe 311 located on the outer circumference of the upper end of the body 31. Since the inlet pipe 311 is located eccentrically from the central axis C3 of the body 31, the hydrogen blowdown water ejected from the inlet pipe 311 forms a swirling flow T inside the body 31. As a result, the hydrogen contained in the hydrogen blowdown water gathers at the center of the swirling flow T due to the centrifugal force of the swirling flow T, rises as a large hydrogen bubble B, and moves to the degassing case 32. The hydrogen-removed water, from which hydrogen has been removed by the swirling flow T, is sequentially discharged from the outlet pipe 312 located on the outer circumference of the lower end of the body 31 to the discharge side piping 42.

[0058] Next, the hydrogen gas collected inside the deaeration case 32 accumulates at the top of the deaeration case 32. As the amount of hydrogen gas at the top of the deaeration case 32 gradually increases, the liquid level of the hydrogen blowdown water inside the deaeration case 32 decreases, and the float 322 descends. This creates a gap between the float 322 and the valve seat 323, causing it to open, and the hydrogen gas inside the deaeration case 32 is discharged from the outlet 324 and supplied to the hydrogen exhaust line 19A.

[0059] Then, when the hydrogen gas inside the deaeration case 32 is discharged, the liquid level of the hydrogen blowdown water inside the deaeration case 32 rises. As a result, the float 322 rises again due to the buoyancy of the hydrogen blowdown water, and comes into contact with the valve seat 323, blocking the outlet 324 and closing it.

[0060] In this way, the deaeration cylinder 30 converts the hydrogen contained in the hydrogen blowdown water into bubbles by forming a swirling flow T inside the body 31. The deaeration cylinder 30 also collects hydrogen bubbles B in a deaeration case 32 located at the top of the body 31, and when a certain amount of hydrogen gas has accumulated, the deaeration case 32 opens and discharges the hydrogen gas. This makes it possible to remove hydrogen contained in the hydrogen blowdown water without increasing the size of the water electrolysis device 100.

[0061] (Effects of the water electrolysis device 100) As described above, the water electrolysis device 100 comprises a water electrolysis cell 10 that electrolyzes water using a polymer electrolyte membrane to generate hydrogen at the cathode, a hydrogen gas-liquid separator 12 that separates the hydrogen generated at the cathode from water, and a degassing cylinder 30 that removes hydrogen contained in the hydrogen blowdown water separated by the hydrogen gas-liquid separator 12. The degassing cylinder 30 has an inlet 31A into which the hydrogen blowdown water flows in, and an outlet 31B that is located at a vertical height lower than the inlet 31A. The hydrogen blowdown water flowing in from the inlet 31A forms a swirling flow T inside the degassing cylinder 30, thereby converting the hydrogen contained in the hydrogen blowdown water into bubbles.

[0062] In the water electrolysis apparatus 100, the hydrogen blowdown water forms a swirling flow T inside the degassing cylinder 30, thereby converting the hydrogen contained in the hydrogen blowdown water into bubbles. Therefore, according to this embodiment, hydrogen contained in the hydrogen blowdown water can be removed without increasing the size of the water electrolysis apparatus 100.

[0063] [Modified Example] Figure 4 is a block diagram showing a modified water electrolysis device 100A, which is a modified version of the water electrolysis device 100 shown in Figure 1. As shown in Figure 4, the water electrolysis device 100A differs from the aforementioned water electrolysis device 100 mainly in that it further includes a water storage tank 15.

[0064] The water storage tank 15 is a container for storing water that is electrolyzed in the water electrolysis cell 10. The water storage tank 15 is positioned between the deaeration cylinder 30 and the oxygen vapor-liquid separator 13. Hydrogen-removed water that has passed through the deaeration cylinder 30 is supplied to the gas phase in the water storage tank 15. The water (pure water) stored in the water storage tank 15 is supplied to the oxygen vapor-liquid separator 13 through the water supply line 18 of the water electrolysis device 100A.

[0065] The water supply line 18 connects the oxygen vapor-liquid separator 13 and the water storage tank 15, supplying water from the water storage tank 15 to the oxygen vapor-liquid separator 13. A pump 16 is located in the water supply line 18 to send water from the water storage tank 15 to the oxygen vapor-liquid separator 13. The water supplied from the water storage tank 15 to the oxygen vapor-liquid separator 13 is then supplied to the water electrolytic cell 10 via the oxygen-side circulation line 17.

[0066] Thus, the hydrogen-removed water from which hydrogen has been removed in the deaeration cylinder 30 may be supplied to the storage tank 15. This allows the hydrogen-removed water to be stored in the storage tank 15 and reused for hydrogen generation in the water electrolysis cell 10.

[0067] In addition, in the water electrolysis apparatus 100A, pure water obtained by treating tap water such as city water using a pure water production apparatus (not shown) may be supplied to the water storage tank 15 instead of the oxygen vapor-liquid separator 13.

[0068] [Embodiment 2] Another embodiment of the present disclosure is described below. For the sake of convenience of explanation, components having the same function as those described in the above embodiment will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0069] [Configuration of Water Electrolyzer 101] Figure 5 is a block diagram showing the schematic configuration of the main parts of the water electrolyzer 101 according to this embodiment. The water electrolyzer 101 differs from the water electrolyzer 100 described above in that it further includes a filter device 50 and a gas venting valve 60.

[0070] As shown in Figure 5, the water electrolysis apparatus 101 includes a filter device 50 positioned between the electric valve 20 of the blowdown water line 19 and the degassing cylinder 30, and a gas venting valve 60 connected to the filter device 50.

[0071] The filter device 50 removes hydrogen contained in the hydrogen blowdown water flowing through the blowdown water line 19. In this embodiment, the filter device 50 is positioned downstream of the electric valve 20 and is configured to remove hydrogen contained in the hydrogen blowdown water that has been transformed into fine bubbles by the electric valve 20. The filter device 50 also captures foreign matter such as carbon powder contained in the hydrogen blowdown water flowing through the blowdown water line 19.

[0072] Figure 6 is a side view showing an example configuration of the filter device 50 shown in Figure 5. Reference numeral 601 in Figure 6 indicates an external view of the filter device 50, and reference numeral 602 in Figure 6 indicates a longitudinal cross-sectional view of the filter device 50.

[0073] As shown in Figure 6, the filter device 50 comprises a filter 51 and a housing 52 that houses the filter 51. Both the filter 51 and the housing 52 are cylindrical. The filter device 50 is configured such that the cartridge-type filter 51 is housed in the housing 52 such that the central axis of the filter 51 and the central axis of the housing 52 substantially coincide.

[0074] The housing 52 is a cylindrical enclosure that houses the filter 51. The housing 52 includes a body portion 52A with an open end (top) that houses the filter 51, and a lid portion 52B that is detachably attached to close the opening of the body portion 52A. The lid portion 52B is provided with an inlet 53, an outlet 54, and a valve connection port (discharge mechanism) 55.

[0075] The inlet 53 and outlet 54 are positioned on the upper side of the lid 52B, facing each other, at a position approximately perpendicular to the central axis of the housing 52. The inlet 53 is connected to the upstream blowdown water line 19 where the electric valve 20 is located, and introduces hydrogen blowdown water into the housing 52. The outlet 54 is connected to the downstream blowdown water line 19 where the degassing cylinder 30 is located, and discharges the hydrogen blowdown water that has passed through the filter 51 to the outside of the housing 52. The valve connection port 55 is located on the upper surface of the lid 52B. The gas venting valve 50 is connected to this valve connection port 55.

[0076] The filter 51 filters the hydrogen blowdown water to remove the hydrogen contained in it. The filter 51 is designed to capture fine hydrogen bubbles at the surface into which the hydrogen blowdown water (liquid) flows. A surface filtration type filter that captures fine hydrogen bubbles contained in the hydrogen blowdown water at its surface is preferably used as the filter 51. In a cylindrical filter 51, the surface 51A side (outer surface side) is the primary side of the filter 51, and the inner surface 51B side (inner surface side or central axis side) is the secondary side of the filter 51.

[0077] Figure 7 is a schematic diagram illustrating the function of the filter 51 shown in Figure 6. As shown in Figure 7, hydrogen blowdown water is supplied to the surface 51A side of the filter 51. The hydrogen blowdown water supplied to the surface 51A side permeates the filter 51 from the surface 51A to the inner surface 51B of the filter 51. As the hydrogen blowdown water permeates the filter 51, fine hydrogen bubbles B-1 contained in the hydrogen blowdown water are captured on the surface 51A of the filter 51. The fine hydrogen bubbles B-1 captured on the surface 51A of the filter 51 combine and enlarge on the surface 51A to become hydrogen bubbles B-2. This increases the buoyancy of hydrogen bubbles B-2, causing them to float along the surface 51A of the filter 51. The floating hydrogen bubbles B-2 flow into the gas vent valve 60 through the valve connection port 55. In other words, the fine hydrogen bubbles B-1 captured by the filter 51 become hydrogen bubbles B-2 and are discharged from inside the housing 52 that houses the filter 51.

[0078] Furthermore, the permeation direction FD1 in which the hydrogen blown water permeates (passes through) the filter 51 and the discharge direction FD2 (the direction of movement of the fine hydrogen bubbles B-1 captured by the filter 51) in which the fine hydrogen bubbles B-1 captured by the filter 51 are discharged intersect (cross-flow).

[0079] More specifically, the housing 52 is attached to the horizontal piping of the blowdown water line 19 such that the inlet 53 and outlet 54 are vertically upward. Therefore, the filter 51 is positioned in the blowdown water line 19 such that the central axis of the cylindrical filter 51 is approximately parallel to the vertical direction. In other words, the filter 51 is positioned in the blowdown water line 19 such that the surface 51A of the filter 51 extends approximately vertically. As a result, as shown in Figure 7, the fine hydrogen bubbles B-1 captured by the surface 51A of the filter 51 move vertically upward. Consequently, the permeation direction FD1 through which the hydrogen blowdown water passes through the filter 51 and the discharge direction FD2 through which the fine hydrogen bubbles B-1 captured by the filter 51 are discharged are approximately perpendicular.

[0080] The arrangement of the filter 51 is not limited to the above. The filter 51 is positioned in the blowdown water line 19 such that its surface 51A is at an angle to the horizontal direction.

[0081] In this way, because the permeation direction FD1 and the discharge direction FD2 intersect, the flow rate of hydrogen blowdown water that can be processed by the filter 51 is greater compared to a configuration in which the permeation direction FD1 and the discharge direction FD2 do not intersect (a configuration in which the permeation direction FD1 and the discharge direction FD2 are substantially parallel). As a result, a large amount of hydrogen blowdown water flowing through the blowdown water line 19 can be processed by the filter device 50, and the filter device 50 can be suitably incorporated into the water electrolysis device 101.

[0082] Furthermore, the filter 51 captures foreign matter such as carbon powder (solid matter) C generated in the water electrolysis cell 10 on its surface 51A. In other words, the filter 51 can simultaneously remove hydrogen (fine hydrogen bubbles B-1) and foreign matter (carbon powder C) contained in the hydrogen blown water.

[0083] Carbon powder C can cause blockages in the equipment of the water electrolysis device 101, and ultimately, it is oxidized on the anode side of the water electrolysis cell 10 to become carbon dioxide, leading to deterioration of the circulating water in the water electrolysis device 101. Therefore, if carbon powder C can be removed by the filter 51, blockages in the equipment of the water electrolysis device 101 and deterioration of the circulating water in the water electrolysis device 101 can be prevented.

[0084] The filter 51 preferably has a pore size of 0.2 μm or more and 10 μm or less, and more preferably has a pore size of about 1 μm. Furthermore, the filter 51 is preferably made of polypropylene. With such a filter 51, the fine hydrogen bubbles B-1 contained in the hydrogen blown water can be suitably captured on the surface 51A and bound to the fine hydrogen bubbles B-1.

[0085] Furthermore, a pleated filter is particularly suitable as the filter 51. By using a pleated filter with a large filtration area as the filter 51, fine hydrogen bubbles B-1 and foreign matter contained in the hydrogen blowdown water can be efficiently captured on the surface 51A. In addition, by using a cylindrical pleated filter, the filter device 50 can be made smaller.

[0086] The gas vent valve 60 discharges the hydrogen captured by the filter 51 from the housing 52. Figure 8 is a longitudinal cross-sectional view showing an example of the configuration of the gas vent valve 60 shown in Figure 5. As shown in Figure 8, the gas vent valve 60 comprises a valve body 61, a float 62, a housing connection port 63, and an outlet 64.

[0087] The gas vent valve 60 is connected to the upper part of the housing 52 of the filter device 50. Specifically, the gas vent valve 60 is connected to the lid portion 52B of the housing 52 via the housing connection port 63 of the gas vent valve 60 and the valve connection port 55 of the housing 52.

[0088] Hydrogen blowdown water containing hydrogen bubbles B-2, which have been captured on the surface 51A of the filter 51, flows into the gas vent valve 60 via the housing connection port 63. As hydrogen bubbles B-2 accumulate inside the gas vent valve 60, the liquid level of the hydrogen blowdown water decreases and the float 62 descends. In conjunction with this descent of the float 62, the valve body 61 opens, and the hydrogen bubbles B-2 accumulated inside the gas vent valve 60 are discharged as hydrogen gas from the outlet 64. On the other hand, once the hydrogen is discharged, the liquid level of the hydrogen blowdown water inside the gas vent valve 60 rises and the float 62 rises. In conjunction with this rise of the float 62, the valve body 61 closes, and the discharge of hydrogen gas from the outlet 64 stops.

[0089] The outlet 64 of the gas venting valve 60 is connected to the hydrogen exhaust line 19A (see Figure 5). Specifically, the outlet 64 may be connected to the hydrogen exhaust line 19A between the aforementioned cheese pipe 21 and check valve 22. The hydrogen gas discharged from the outlet 64 is exhausted through the hydrogen exhaust line 19A together with the hydrogen gas that flows into the hydrogen exhaust line 19A from the degassing cylinder 30.

[0090] By using such a gas vent valve 60, hydrogen removed from the hydrogen blowdown water by the filter 51 can be appropriately discharged from the filter device 50. Therefore, it is possible to prevent a reduction in the effective filtration area due to the airlock phenomenon where the surface 51A of the filter 51 becomes clogged with hydrogen, and to prevent an increase in the pressure loss of the filter 51.

[0091] In the water electrolysis device 101, the hydrogen blowdown water that has passed through the filter 51 flows into the deaeration cylinder 30. The deaeration cylinder 30 removes any remaining hydrogen in the hydrogen blowdown water, that is, hydrogen that could not be removed by the filter 51, by turning it into bubbles. By removing the hydrogen contained in the hydrogen blowdown water using the filter device 50 and the deaeration cylinder 30, it becomes easier to remove the hydrogen contained in the hydrogen blowdown water.

[0092] [Effects of the water electrolysis device 101] As described above, the water electrolysis device 101 further includes a filter device 50 positioned between the hydrogen gas-liquid separator 12 and the degassing cylinder 30, and this filter device 50 removes hydrogen and foreign matter contained in the hydrogen blowdown water.

[0093] In the water electrolysis apparatus 101, hydrogen contained in the hydrogen blowdown water is removed by both the filter device 50 and the degassing cylinder 30. Therefore, according to this embodiment, hydrogen contained in the hydrogen blowdown water can be effectively removed.

[0094] Furthermore, the water electrolysis device 101 is equipped with a filter device 50 to remove foreign matter (carbon powder C) contained in the hydrogen blowdown water. Therefore, according to this embodiment, blockage of the equipment in the water electrolysis device 101 and deterioration of the circulating water in the water electrolysis device 101 can be prevented.

[0095] [Modified Version] (First Modified Version) Figure 9 is a block diagram showing a water electrolysis apparatus 101A, which is a first modified version of the water electrolysis apparatus 101 shown in Figure 5. As shown in Figure 9, the water electrolysis apparatus 101A differs from the aforementioned water electrolysis apparatus 101 mainly in that the gas venting valve 60 is omitted and the electric valve 20 is located downstream of the filter device 50.

[0096] In the water electrolysis apparatus 101A, the filter device 50 is provided to capture foreign matter (carbon powder C) contained in the hydrogen blowdown water without removing the hydrogen (fine hydrogen bubbles B-1) contained in the hydrogen blowdown water flowing through the blowdown water line 19. In other words, the water electrolysis apparatus 101A may be configured to capture foreign matter contained in the hydrogen blowdown water with the filter device 50 and remove the hydrogen contained in the hydrogen blowdown water with the degassing cylinder 30.

[0097] If the hydrogen contained in the hydrogen blowdown water is not removed by the filter device 50, there is no need to place the electric valve 20 that generates fine hydrogen bubbles B-1 upstream of the filter device 50. For this reason, the electric valve 20 may be placed between the filter device 50 and the degassing cylinder 30, that is, downstream of the filter device 50. This prevents fine hydrogen bubbles B-1 from adhering to the surface 51A of the filter 51, thus preventing a reduction in the effective filtration area due to the airlock phenomenon where the surface 51A becomes clogged with hydrogen, and preventing an increase in the pressure loss of the filter 51.

[0098] (Second Modification) Figure 10 is a block diagram showing a second modification of the water electrolysis apparatus 101 shown in Figure 5, which is a water electrolysis apparatus 101B. As shown in Figure 10, the water electrolysis apparatus 101B has a configuration in which an ion exchange resin 70 is further added to the water electrolysis apparatus 101A, which is the first modification.

[0099] The water electrolysis apparatus 101B may also include an ion exchange resin 70. The ion exchange resin 70 removes impurities by ion exchange with the ionic components in the hydrogen blowdown water. In the illustrated example, the ion exchange resin 70 is located between the hydrogen gas-liquid separator 12 and the filter device 50, that is, upstream of the filter device 50. The ion exchange resin 70 may be configured, for example, as an ion exchange resin cylinder housed in a cylindrical casing.

[0100] The cathode side of the water electrolytic cell 10 has high electrical conductivity due to ions generated by electrolysis. When electrical conductivity increases, it can lead to deterioration of the water electrolytic cell 10's performance (corrosion, increase in electrolysis voltage, etc.). Therefore, it is necessary to remove the ions contained in the hydrogen blowdown water (circulating water). For this reason, it is preferable to place an ion exchange resin 70 in the blowdown water line 19 to remove the ions.

[0101] In the water electrolysis device 101B, impurities can be removed by ion exchange of ionic components in the hydrogen blowdown water using the ion exchange resin 70. Furthermore, by capturing carbon powder C in the hydrogen blowdown water with the filter 51, for example, blockage of equipment in the water electrolysis device 101B caused by carbon powder C, and deterioration of the circulating water in the water electrolysis device 101B can be prevented.

[0102] Thus, the water electrolysis device 101B may include at least one of an ion exchange resin 70 that exchanges ionic components contained in the hydrogen blow-dry water, and a filter 51 that captures foreign matter (solid matter) contained in the hydrogen blow-dry water.

[0103] (Third Modification) Figure 11 is a block diagram showing a water electrolytic device 101C, which is a third modification of the water electrolytic device 101 shown in Figure 5. As shown in Figure 11, the water electrolytic device 101C is configured such that a gas venting valve 60 is connected to each of the filter device 50 and ion exchange resin 70 of the water electrolytic device 101B, which is the second modification.

[0104] The water electrolysis device 101C may be configured to include a filter device 50 and an ion exchange resin 70, and a gas venting valve 60 may be individually connected to each of the filter device 50 and the ion exchange resin 70.

[0105] In the water electrolysis apparatus 101C, an electric valve 20, an ion exchange resin 70, and a filter device 50 are arranged from the upstream side between the hydrogen gas-liquid separator 12 and the degassing cylinder 30. In the water electrolysis apparatus 101C, the ion exchange resin (ion exchange resin cylinder) 70, like the filter 51, is designed to capture fine hydrogen bubbles B-1 contained in the hydrogen blowdown water as the hydrogen blowdown water passes through the ion exchange resin 70.

[0106] Therefore, the water electrolysis device 101C can more effectively remove hydrogen contained in the hydrogen blowdown water by removing the hydrogen contained in the hydrogen blowdown water through the ion exchange resin 70, the filter device 50, and the degassing cylinder 30, respectively.

[0107] (Fourth Modification) Figure 12 is a block diagram showing a water electrolytic apparatus 101D, which is a fourth modification of the water electrolytic apparatus 101 shown in Figure 5. As shown in Figure 12, the water electrolytic apparatus 101D differs from the aforementioned water electrolytic apparatus 101 mainly in that the filter 51 and the ion exchange resin 70 are arranged inside the degassing cylinder 30.

[0108] The water electrolyzer 101D comprises at least one of a filter 51 and an ion exchange resin 70, and at least one of the filter 51 and the ion exchange resin 70 may be provided inside the body 31 of the degassing cylinder 30. This makes it possible to suppress the increase in size of the water electrolyzer 101D that would occur with the installation of the filter 51 or the ion exchange resin 70.

[0109] [Summary] The water electrolysis apparatus according to Embodiment 1 of the present disclosure comprises a water electrolysis cell that electrolyzes water using a polymer electrolyte membrane to generate hydrogen at the cathode, a hydrogen vapor-liquid separator that separates the hydrogen generated at the cathode from water, and a deaeration cylinder that removes hydrogen contained in the separated water separated by the hydrogen vapor-liquid separator, wherein the deaeration cylinder has an inlet for the separated water to flow in and an outlet located at a vertical height lower than the inlet, and the separated water flowing in from the inlet forms a swirling flow inside the deaeration cylinder, thereby converting the hydrogen contained in the separated water into bubbles.

[0110] In the above configuration, the separated water (hydrogen blowdown water) forms a swirling flow inside the degassing cylinder, thereby causing the hydrogen contained in the separated water to be converted into bubbles. Therefore, with this configuration, hydrogen contained in the separated water can be removed without increasing the size of the water electrolysis device as in the conventional method.

[0111] The water electrolysis apparatus according to embodiment 2 of the present disclosure further comprises a discharge side pipe connected to the outlet in embodiment 1, wherein the discharge side pipe may include a rising portion that extends to a vertical height position higher than the upper end of the degassing cylinder.

[0112] According to the above configuration, since the discharge piping is installed to pass at a higher position than the venting pipe, the venting pipe can be sealed with separated water to prevent outside air from flowing into the venting pipe.

[0113] The water electrolysis apparatus according to embodiment 3 of the present disclosure may further include, in embodiment 1 or 2, a water storage tank to which removed water from which hydrogen has been removed in the deaeration cylinder is supplied, or an oxygen vapor-liquid separator for separating oxygen and water generated at the anode of the water electrolysis cell, to which removed water from which hydrogen has been removed in the deaeration cylinder is supplied.

[0114] According to the above configuration, the removed water (pure water) can be supplied to a storage tank or an oxygen vapor-liquid separator and reused for hydrogen generation in the water electrolytic cell.

[0115] In the water electrolysis apparatus according to embodiment 4 of the present disclosure, in embodiment 3, the removed water may be supplied to the water storage tank or the gas phase of the oxygen gas-liquid separator.

[0116] According to the above configuration, the influence of pressure (internal pressure) due to changes in the liquid level of the water storage tank or oxygen vapor-liquid separator can be reduced, and the removed water can be stably supplied to the water storage tank or oxygen vapor-liquid separator.

[0117] The water electrolysis apparatus according to embodiment 5 of the present disclosure may further include, in any of embodiments 1 to 4, a filter for capturing solid matter contained in the separated water, or an ion exchange resin for ion exchange of ionic components contained in the separated water.

[0118] According to the above configuration, for example, by capturing carbon powder (solid matter) in the separated water with a filter, it is possible to prevent blockage of the water electrolysis equipment caused by carbon powder and deterioration of the circulating water in the water electrolysis equipment. Furthermore, according to the above configuration, impurities can be removed by ion exchange of ionic components in the separated water with an ion exchange resin.

[0119] In the water electrolysis apparatus according to embodiment 6 of the present disclosure, the filter or the ion exchange resin may be provided inside the degassing cylinder in embodiment 5.

[0120] According to the above configuration, it is possible to suppress the increase in size of the device that would occur with the installation of a filter or ion exchange resin.

[0121] 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. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0122] 12: Hydrogen gas-liquid separator 13: Oxygen gas-liquid separator 15: Water storage tank 30: Degassing cylinder 30A: Upper end (upper end) 31A: Inlet 31B: Outlet 42: Discharge side piping 42A: Riser 51: Filter 70: Ion exchange resin 100, 100A, 101, 10: Water electrolysis device B: Hydrogen bubbles C: Carbon powder (solid material) G: Gas phase T: Swirling flow

Claims

1. A water electrolysis apparatus comprising: a water electrolysis cell that electrolyzes water using a polymer electrolyte membrane to generate hydrogen at the cathode; a hydrogen vapor-liquid separator that separates the hydrogen generated at the cathode from water; and a deaeration cylinder that removes hydrogen contained in the separated water separated by the hydrogen vapor-liquid separator, wherein the deaeration cylinder has an inlet for the separated water to flow in and an outlet located at a vertical height lower than the inlet, and the separated water flowing in from the inlet forms a swirling flow inside the deaeration cylinder, thereby converting the hydrogen contained in the separated water into bubbles.

2. The water electrolysis apparatus according to claim 1, further comprising a discharge pipe connected to the outlet, wherein the discharge pipe includes a rising portion that extends to a vertical height position higher than the upper end of the deaeration cylinder.

3. The water electrolysis apparatus according to claim 1 or 2, further comprising: a water storage tank supplied with removed water from which hydrogen has been removed in the deaeration cylinder; or an oxygen vapor-liquid separator for separating oxygen generated at the anode of the water electrolysis cell from water, wherein the oxygen vapor-liquid separator is supplied with removed water from which hydrogen has been removed in the deaeration cylinder.

4. The water electrolysis apparatus according to claim 3, wherein the removed water is supplied to the water storage tank or the gas phase of the oxygen gas-liquid separator.

5. The water electrolysis apparatus according to claim 1 or 2, further comprising a filter for capturing solid matter contained in the separated water, or an ion exchange resin for ion exchange of ionic components contained in the separated water.

6. The water electrolysis apparatus according to claim 5, wherein the filter or the ion exchange resin is provided inside the degassing cylinder.

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