JP7591994B2 - Water electrolysis device and control method - Google Patents

Description

The present invention relates to a water electrolysis device that electrolyzes water to generate hydrogen and oxygen, and a control method thereof.

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

JP 2002-173788 A

Until now, hydrogen blow water has been considered to be pure water. However, the inventors of the present invention have clarified that hydrogen blow water contains ionic impurities, and that the influence of these ionic impurities increases the electrical conductivity. If such hydrogen blow water with high electrical conductivity is reused to produce hydrogen, problems such as deterioration of the water electrolyzer will arise.

Therefore, in order to maintain the pure water in the system, it would be possible to discard all of the hydrogen blow water and replenish it with new pure water, but in this case, a large amount of pure water would be required.

The present invention aims to provide a water electrolysis device that can reuse hydrogen blow water with reduced ionic components for hydrogen production.

In order to solve the above problems, a water electrolysis device according to one embodiment of the present invention includes a water electrolysis cell that uses a polymer electrolyte membrane to split water and generate hydrogen at the cathode, a hydrogen gas-liquid separator that separates the hydrogen and water generated at the cathode and releases the water as separated water, a filter device including a reverse osmosis membrane that removes ionic components contained in the separated water released from the hydrogen gas-liquid separator, and a water storage tank that stores the permeated water that has permeated the reverse osmosis membrane.

In order to solve the above problem, a method for controlling a water electrolysis device according to one embodiment of the present invention includes the steps of decomposing water using a polymer electrolyte membrane to generate hydrogen at a cathode, separating the hydrogen and water generated at the cathode using a hydrogen gas-liquid separator and discharging the water as separated water, and adjusting the flow of permeated water that has permeated through a reverse osmosis membrane of a filter device that includes a reverse osmosis membrane that removes ionic components contained in the separated water, based on the liquid level of the hydrogen gas-liquid separator.

According to one aspect of the present invention, hydrogen blow water with reduced ionic components can be reused for hydrogen production.

1 is a block diagram showing a schematic configuration of a water electrolysis device according to an embodiment of the present invention. 2 is a schematic diagram showing the peripheral configuration of the coarse filter device and the RO filter device shown in FIG. 1 . FIG. 3 is a diagram showing an example of the configuration of the coarse filter device main body shown in FIG. 2, in which 3001 shows a front view of the coarse filter device main body and 3002 shows a cross-sectional view of the coarse filter device main body. 5A to 5C are schematic diagrams illustrating the function of a coarse filter included in the coarse filter device main body. FIG. 3 is a vertical cross-sectional view showing an example of the configuration of the air vent valve shown in FIG. 2 . FIG. 2 is a schematic diagram illustrating a function of a reverse osmosis membrane included in the RO filter device. 4 is a flowchart showing an example of flow rate control of permeated water in the water electrolysis apparatus. FIG. 2 is a cross-sectional view showing the internal structure of the hydrogen gas-liquid separator. 4 is a flowchart showing an example of concentrated water discharge control in the water electrolysis apparatus. 4 is a flowchart showing an example of an abnormality determination control in the water electrolysis apparatus.

One embodiment of the present invention will be described in detail below with reference to Figures 1 to 10. However, the following description is an example of a water electrolysis device and a control method thereof according to the present invention, and the technical scope of the present invention is not limited to the illustrated example.

[Configuration of water electrolysis device]
Fig. 1 is a block diagram showing a schematic configuration of a water electrolysis apparatus 100 according to an embodiment of the present invention. As shown in Fig. 1, the water electrolysis apparatus 100 includes a water electrolysis cell 10, a DC power supply 11, a hydrogen gas-liquid separator 12, an oxygen gas-liquid separator 13, a water storage tank 15, a coarse filter device 30, and an RO filter device (filter device) 80. The operation of each part of the water electrolysis apparatus 100 is controlled by a control unit 20.

The water electrolysis cell 10 electrolyzes water (electrolyzes it) using a polymer electrolyte membrane (solid polymer membrane), generating oxygen at the anode and hydrogen (gas) at the cathode. A DC power supply 11 is connected to the water electrolysis cell 10. The power required for water electrolysis is supplied from the DC power supply 11 to the water electrolysis cell 10.

The hydrogen generated at the cathode of the water electrolysis cell 10 is supplied from the water electrolysis cell 10 to the hydrogen gas-liquid separator 12 in the form of a gas-liquid mixture together with the water that has not been electrolyzed (water that has permeated the polymer electrolyte membrane). In addition, the oxygen (gas) generated at the anode of the water electrolysis cell 10 is supplied from the water electrolysis cell 10 to the oxygen gas-liquid separator 13 in the form of a gas-liquid mixture together with the water that has not been electrolyzed.

The hydrogen gas-liquid separator 12 separates the hydrogen-containing gas-liquid mixed water supplied from the water electrolysis cell 10 into hydrogen and water. The hydrogen (hydrogen gas) after gas-liquid separation is wet hydrogen containing a large amount of moisture. Therefore, the hydrogen after gas-liquid separation is supplied to a dehumidifier (not shown) or the like to remove the moisture. Meanwhile, the water after gas-liquid separation is supplied to the water storage tank 15 as hydrogen blow water (separated water, liquid) through the hydrogen line 19 of the water electrolysis device 100.

The hydrogen gas-liquid separator 12 includes a level sensor that detects the liquid level of the hydrogen gas-liquid separator 12. The hydrogen gas-liquid separator 12 outputs the liquid level in the hydrogen gas-liquid separator 12 detected by the level sensor to the control unit 20 via signal line SL1.

The hydrogen line 19 supplies hydrogen blow water from the hydrogen gas-liquid separator 12 to the water storage tank 15. In the hydrogen line 19, from the upstream side, a coarse filter device 30, an RO filter device 80, a control valve (first adjustment mechanism) 91, and a first separator (first separation mechanism) 92 are arranged.

The hydrogen line 19 includes a hydrogen exhaust line 19a that branches off at a first separator 92. A check valve (backflow prevention mechanism) 70 is disposed in this hydrogen exhaust line 19a. The hydrogen line 19 also includes a drainage line 19b that branches off at an RO filter device 80. In this drainage line 19b, from the upstream side, an opening/closing valve (second adjustment mechanism) 93, an adjustment valve (second adjustment mechanism) 94, and a second separator (second separation mechanism) 95 are disposed. The drainage line 19b discharges concentrated hydrogen blow water (hereinafter sometimes referred to as concentrated water) that does not pass through the reverse osmosis membrane 81 from the RO filter device 80 and discharges it outside the system.

Here, the hydrogen gas-liquid separator 12 is pressurized while the water electrolysis cell 10 is in operation. Therefore, the hydrogen blow water separated from the hydrogen gas-liquid separator 12 is at high pressure, and hydrogen is dissolved in the high-pressure hydrogen blow water. Therefore, the hydrogen blow water released by the hydrogen gas-liquid separator 12 may contain hydrogen in the form of fine bubbles.

The coarse filter device 30 removes gas contained in the liquid and foreign matter (solid matter) contained in the hydrogen blow water, such as carbon powder. In this embodiment, the coarse filter device 30 mainly removes hydrogen and carbon powder contained in the hydrogen blow water. The coarse filter device 30 includes a coarse filter device main body 40 equipped with a coarse filter 41 that removes hydrogen from the hydrogen blow water, and a gas vent valve (discharge mechanism) 50 that discharges the hydrogen removed by the coarse filter 41. Details of the coarse filter device 30 will be described later.

The RO filter device 80 removes ionic components contained in the liquid. In this embodiment, the RO filter device 80 removes ionic components contained in the hydrogen blow water. The RO filter device 80 includes a reverse osmosis membrane 81 that removes ionic components from the hydrogen blow water. Details of the RO filter device 80 will be described later.

The control valve 91 is disposed between the RO filter device 80 and the water storage tank 15, and adjusts the flow of hydrogen blow water (hereinafter sometimes referred to as permeate water) that has permeated through the RO filter device 80. Specifically, the control valve 91 uses the pressure difference between the pressure (high pressure) on the hydrogen gas-liquid separator 12 side and the pressure (low pressure) on the water storage tank 15 side to adjust the valve opening within a range of 0% to 100%, thereby adjusting the flow rate of the permeate water flowing through the hydrogen line 19. The adjustment of the valve opening of the control valve 91 is controlled by the control unit 20 via the signal line SL3.

The first separator 92 is disposed downstream of the control valve 91 and separates the hydrogen contained in the permeate. The permeate flowing through the hydrogen line 19 is depressurized by the control valve 91, causing some of the hydrogen dissolved in the permeate to vaporize. The first separator 92 separates this vaporized hydrogen from the permeate. The first separator 92 is connected to the hydrogen exhaust line 19a, and the hydrogen separated by the first separator 92 is exhausted through the hydrogen exhaust line 19a.

The on-off valve 93 and the adjustment valve 94 are disposed in the drain line 19b and adjust the flow of the concentrated water. Specifically, the on-off valve 93 controls the timing of draining the concentrated water flowing through the drain line 19b by switching the valve between open and closed. The control valve 91 is controlled by the control unit 20 via the signal line SL4.

The adjustment valve 94, which is located downstream of the on-off valve 93, has a constant valve opening and adjusts the flow rate of concentrated water flowing through the drain line 19b. By placing the adjustment valve 94 in the drain line 19b, the amount of concentrated water discharged is adjusted.

In this manner, in this embodiment, the timing of draining the concentrated water is controlled by switching the opening and closing of the on-off valve 93, and the timing and amount of drainage are adjusted by placing an adjustment valve 94 with a constant valve opening downstream of the on-off valve 93. However, instead of the on-off valve 93 and the adjustment valve 94, a control valve whose valve opening can be adjusted electrically or electromagnetically may be placed in the drain line 19b. This allows the control unit 20 to adjust the valve opening of the control valve to control the timing and amount of drainage of the concentrated water.

The second separator 95 is disposed downstream of the regulating valve 94 and separates the hydrogen contained in the concentrated water. The concentrated water flowing through the drainage line 19b is depressurized by the regulating valve 94, causing some of the hydrogen dissolved in the concentrated water to vaporize. The first separator 92 separates this vaporized hydrogen from the concentrated water. The second separator 95 is connected to the hydrogen exhaust line 19a, and the hydrogen separated by the second separator 95 is exhausted through the hydrogen exhaust line 19a.

The oxygen gas-liquid separator 13 separates the oxygen-containing gas-liquid mixed water supplied from the water electrolysis cell 10 into oxygen and water. The oxygen (oxygen gas) after gas-liquid separation is exhausted, for example, to the atmosphere. Meanwhile, the water after gas-liquid separation is supplied to the water electrolysis cell 10 through the oxygen-side circulation line 17 of the water electrolysis device 100 as oxygen-side circulating water. The oxygen-side circulation line 17 supplies the oxygen-side circulating water from the oxygen gas-liquid separator 13 to the water electrolysis cell 10. A pump 14 is arranged in the oxygen-side circulation line 17 to pump the oxygen-side circulating water from the oxygen gas-liquid separator 13 to the water electrolysis cell 10.

The oxygen-gas-liquid separator 13 includes a level sensor that detects the liquid level in the oxygen-gas-liquid separator 13. The oxygen-gas-liquid separator 13 outputs the liquid level of the oxygen-gas-liquid separator 13 detected by the level sensor to the control unit 20 via signal line SL2.

The water storage tank 15 stores the water to be electrolyzed in the water electrolysis cell 10. Pure water is supplied to the water storage tank 15. Permeated water that has permeated the coarse filter 41 and the reverse osmosis membrane 81 is also supplied to the water storage tank 15. The water stored in the water storage tank 15 is supplied to the oxygen gas-liquid separator 13 through the water supply line 18 of the water electrolysis device 100. A pump 16 that pumps water from the water storage tank 15 to the oxygen gas-liquid separator 13 is disposed in the water supply line 18 that supplies water from the water storage tank 15 to the oxygen gas-liquid separator 13. The water supplied from the water storage tank 15 to the oxygen gas-liquid separator 13 is supplied from the oxygen gas-liquid separator 13 to the water electrolysis cell 10 through the oxygen side circulation line 17.

The control unit 20 controls the operation of each part of the water electrolysis device 100. The control unit 20 is configured, for example, by a processor such as a CPU (Central Processing Unit), or by a logic circuit formed in an integrated circuit (IC chip) or the like.

The control unit 20 controls the supply of power from the DC power source 11 to the water electrolysis tank 10 and controls the operation of the water electrolysis tank 10. The control unit 20 also controls the flow rate of the permeate by controlling the control valve 91 based on the liquid level of the hydrogen gas-liquid separator 12. The control unit 20 also controls the drainage of the concentrated water by controlling the on-off valve 93 based on the liquid level of the hydrogen gas-liquid separator 12 or so that the concentrated water is periodically drained. Furthermore, the control unit 20 performs anomaly determination control to determine whether or not there is a possibility of an abnormality occurring in the water electrolysis device 100 based on the amount of water flowing into the hydrogen gas-liquid separator 12 and the oxygen gas-liquid separator 13, the operating status of the water electrolysis tank 10 related to the amount of water permeated through the reverse osmosis membrane 81, the valve opening degree of the control valve 91, etc.

Figure 2 is a schematic diagram showing the peripheral configuration of the coarse filter device 30 and the RO filter device 80 shown in Figure 1. Figure 2 shows the configuration within the dashed-dotted frame in Figure 1. As shown in Figure 2, the coarse filter device 30 and the RO filter device 80 are arranged in the horizontal piping of the hydrogen line 19. Specifically, the RO filter device 80 is arranged in the horizontal piping of the hydrogen line 19, which is installed at a position higher than the liquid level L1 of the water storage tank 15. As a result, the installation height of the coarse filter device 30 and the RO filter device 80 is higher than the liquid level L1 of the water storage tank 15.

A coarse filter device 30 is disposed upstream of the RO filter device 80, and a first separator 92 consisting of a control valve 91 and a T-shaped branched tee pipe is disposed downstream. A hydrogen exhaust line 19a branches off from the hydrogen line 19 in the first separator 92. In the first separator 92, hydrogen remaining in the permeated water becomes hydrogen gas, which flows into the hydrogen exhaust line 19a and is exhausted. Meanwhile, the permeated water from which hydrogen has been separated in the first separator 92 is supplied to the water storage tank 15.

A drain line 19b is connected to the housing 82 of the RO filter device 80. A second separator 95 consisting of an adjustment valve 94 and a T-shaped branched tee pipe is arranged downstream of the opening and closing valve 93. In the second separator 95, hydrogen remaining in the concentrated water becomes hydrogen gas and flows into the hydrogen exhaust line 19a and is exhausted. Meanwhile, in the second separator 95, the concentrated water after hydrogen is separated is discharged outside the system. Although not shown, a water seal mechanism consisting of, for example, a U-shaped pipe or an S-shaped pipe may be arranged downstream (drainage side) of the second separator 95 in the drainage line 19b. By arranging a water seal mechanism in the drainage line 19b, it is possible to prevent the inflow of air from the end of the drainage side of the drainage line 19b.

The hydrogen gas-liquid separator 12 is pressurized during operation of the water electrolysis apparatus 100, and as described above, the hydrogen gas-liquid separator 12 side is at a higher pressure than the water storage tank 15 side. If a control valve 91 were placed between the hydrogen gas-liquid separator 12 and the RO filter device 80 (i.e., upstream of the RO filter device 80), the control valve 91 could cause a pressure drop in the hydrogen blow water flowing into the RO filter device 80. In the water electrolysis apparatus 100, the control valve 91 is placed between the RO filter device 80 and the water storage tank 15, i.e., downstream of the RO filter device 80, so that the above-mentioned pressure drop in the hydrogen blow water flowing into the RO filter device 80 can be avoided.

(Details of the coarse filter device)
3 is a diagram showing an example of the configuration of the coarse filter device main body 40 shown in FIG. 2, in which 3001 in FIG. 3 shows a front view of the coarse filter device main body 40 and 3002 in FIG.

As shown in FIG. 3, the coarse filter device 30 comprises a coarse filter device body 40 including a coarse filter 41 and a housing 42 that accommodates the coarse filter 41, and a gas vent valve 50 connected to the coarse filter device body 40. The coarse filter 41 and the housing 42 provided in the coarse filter device body 40 are, for example, cylindrical. The cartridge-type coarse filter 41 is accommodated in the housing 42 so that the central axis of the coarse filter 41 and the central axis of the housing 42 are approximately aligned.

The housing 42 is a case that houses the coarse filter 41. The housing 42 includes a body 42a with an open end that houses the coarse filter 41, and a lid 42b that is removably attached to cover the opening of the body 42a. An inlet 43, an outlet 44, and a valve connection port (exhaust mechanism) 45 are arranged in the lid 42b.

The inlet 43 and outlet 44 are arranged on the upper side of the lid 42b, facing each other at positions approximately perpendicular to the central axis of the housing 42. The inlet 43 is connected to the upstream hydrogen line 19 and introduces hydrogen blow water into the interior of the housing 42. The outlet 44 is connected to the downstream hydrogen line 19 and discharges the hydrogen blow water that has permeated the coarse filter 41 to the outside of the housing 42. The valve connection port 45 is arranged on the upper surface of the lid 42b. A gas vent valve 50, which will be described later, is connected to this valve connection port 45.

The coarse filter 41 filters the hydrogen blow water to remove hydrogen contained in the hydrogen blow water. The coarse filter 41 captures fine hydrogen bubbles (gas) on the surface into which the hydrogen blow water (liquid) flows. A surface filtration type filter that captures fine hydrogen bubbles contained in the hydrogen blow water on its surface is preferably used as the coarse filter 41. The surface 41a side (outer peripheral surface side) of the cylindrical coarse filter 41 is the primary side of the coarse filter 41, and the inner surface 41b side (inner peripheral surface side or central axis side) is the secondary side of the coarse filter 41.

Figure 4 is a schematic diagram explaining the function of the coarse filter 41. As shown in Figure 4, hydrogen blow water is supplied to the surface 41a side of the coarse filter 41 (supply process). The hydrogen blow water supplied to the surface 41a side passes through the coarse filter 41 from the surface 41a of the coarse filter 41 to the inner surface 41b of the coarse filter 41. When the hydrogen blow water passes through the coarse filter 41, fine hydrogen bubbles H2-1 contained in the hydrogen blow water are captured by the surface 41a of the coarse filter 41 (capture process). The fine hydrogen bubbles H2-1 captured by the surface 41a of the coarse filter 41 combine on the surface 41a to become larger hydrogen bubbles H2-2. This increases the buoyancy of the hydrogen bubbles H2-2, and the hydrogen bubbles H2-2 rise along the surface 41a of the coarse filter 41. The rising hydrogen bubbles H2-2 flow into the gas vent valve 50 through the valve connection port 45. In other words, the fine hydrogen bubbles H2-1 captured by the coarse filter 41 become hydrogen bubbles H2-2 and are discharged from inside the housing 42 that contains the coarse filter 41 (discharge process).

In addition, the permeation direction D1 in which the hydrogen blow water permeates (passes through) the coarse filter 41 intersects (cross-flows) with the discharge direction D2 in which the fine hydrogen bubbles H2-1 captured by the coarse filter 41 are discharged (the direction in which the fine hydrogen bubbles H2-1 captured by the coarse filter 41 move).

More specifically, the housing 42 is attached to the horizontal piping of the hydrogen line 19 so that the inlet 43 and outlet 44 are vertically upward (see FIG. 3). Therefore, the cylindrical coarse filter 41 is placed in the hydrogen line 19 so that the central axis of the coarse filter 41 is approximately parallel to the vertical direction. In other words, the coarse filter 41 is placed in the hydrogen line 19 so that the surface 41a of the coarse filter 41 extends in the approximately vertical direction. As a result, as shown in FIG. 4, the fine hydrogen bubbles H2-1 captured on the surface 41a of the coarse filter 41 move vertically upward. As a result, the permeation direction D1 in which the hydrogen blow water permeates the coarse filter 41 and the discharge direction D2 in which the fine hydrogen bubbles H2-1 captured by the coarse filter 41 are discharged are approximately perpendicular to each other.

The arrangement of the coarse filter 41 is not limited to the above. It is sufficient that the coarse filter 41 is arranged on the hydrogen line 19 so that the surface 41a of the coarse filter 41 is angled with respect to the horizontal direction.

In this way, since the permeation direction D1 and the discharge direction D2 intersect, the flow rate of the hydrogen blow water that can be treated by the coarse filter 41 is greater than, for example, a configuration in which the permeation direction D1 and the discharge direction D2 do not intersect (a configuration in which the permeation direction D1 and the discharge direction D2 are approximately parallel). This makes it possible for a large amount of hydrogen blow water flowing through the hydrogen line 19 to be treated by the coarse filter device 30, and the coarse filter device 30 can be suitably incorporated into the water electrolysis device 100.

The coarse filter 41 also captures foreign matter (solid matter) contained in the hydrogen blow water, such as carbon powder C generated in the water electrolysis cell 10, on its surface 41a. In other words, the coarse filter 41 can simultaneously remove hydrogen (fine hydrogen bubbles H2-1) and foreign matter (carbon powder C) contained in the hydrogen blow water.

Carbon powder C not only causes clogging of the equipment in the water electrolysis device 100, but also eventually becomes carbon dioxide gas on the anode side of the water electrolysis cell 10, leading to deterioration of the circulating water in the water electrolysis device 100. Therefore, if carbon powder C can be removed by the coarse filter 41, clogging of the equipment in the water electrolysis device 100 and deterioration of the circulating water in the water electrolysis device 100 can be prevented. In particular, in a water electrolysis device 100 in which an RO filter device 80 is arranged in the hydrogen line 19, carbon powder C can be the main cause of clogging (clogging) of the reverse osmosis membrane 81. Therefore, clogging of the reverse osmosis membrane 81 can be effectively reduced by removing carbon powder C from the hydrogen blow water by arranging a coarse filter device 30 upstream of the RO filter device 80.

The coarse filter 41 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. The coarse filter 41 is also preferably made of polypropylene. With such a coarse filter 41, the fine hydrogen bubbles contained in the hydrogen blow water can be suitably captured and bound on the surface 41a.

A pleated filter is particularly suitable as the coarse filter 41. By using a pleated filter with a large filtering area as the coarse filter 41, fine hydrogen bubbles and foreign matter contained in the hydrogen blow water can be efficiently captured on the surface 41a. Furthermore, by using a cylindrical pleated filter, the coarse filter device 30 can be made smaller.

The gas vent valve 50 discharges the gas captured by the coarse filter 41 from inside the housing 42. FIG. 5 is a vertical cross-sectional view showing an example of the configuration of the gas vent valve 50 shown in FIG. 2. As shown in FIG. 5, the gas vent valve 50 includes a valve body 51, a float 52, a housing connection port (discharge mechanism) 53, and a discharge port 54.

The gas vent valve 50 is connected to the upper part of the housing 42 of the coarse filter device main body 40. Specifically, the gas vent valve 50 is connected to the lid portion 42b of the housing 42 via the housing connection port 53 of the gas vent valve 50 and the valve connection port 45 of the housing 42.

Hydrogen blow water containing hydrogen that has been captured on the surface 41a of the coarse filter 41 and turned into hydrogen bubbles H2-2 flows into the gas vent valve 50 through the housing connection port 53. As the hydrogen bubbles H2-2 accumulate inside the gas vent valve 50, the liquid level of the hydrogen blow water lowers and the float 52 descends. In conjunction with this descent of the float 52, the valve body 51 opens, and the hydrogen bubbles H2-2 that have accumulated inside the gas vent valve 50 are discharged from the exhaust port 54 as hydrogen gas. On the other hand, when hydrogen is discharged, the liquid level of the hydrogen blow water inside the gas vent valve 50 rises and the float 52 rises. In conjunction with this rise of the float 52, the valve body 51 closes, and the discharge of hydrogen gas from the exhaust port 54 stops.

The exhaust port 54 of the gas vent valve 50 is connected to the hydrogen exhaust line 19a (see FIG. 2). Specifically, the exhaust port 54 is connected to the hydrogen exhaust line 19a between the tee pipe 60 and the check valve 70. In the tee pipe 60, hydrogen remaining in the hydrogen blow water that has permeated the coarse filter 41, i.e., hydrogen that has not been completely removed by the coarse filter 41, becomes hydrogen gas and flows into the hydrogen exhaust line 19a. The hydrogen gas discharged from the exhaust port 54 is exhausted through the hydrogen exhaust line 19a together with the hydrogen gas that has flowed from the tee pipe 60 into the hydrogen exhaust line 19a.

By using such a gas vent valve 50, hydrogen removed from the hydrogen blow water by the coarse filter 41 can be appropriately discharged from the coarse filter device main body 40. This makes it possible to prevent a reduction in the effective filtering area due to the airlock phenomenon in which the surface 41a of the coarse filter 41 becomes clogged with hydrogen, and an increase in pressure loss in the coarse filter 41.

The gas vent valve 50 may be disposed in a position that allows hydrogen to be discharged from the housing 42 that contains the coarse filter 41. The gas vent valve 50 may be disposed, for example, inside the housing 42.

[Details of the RO filter device]
Conventionally, the hydrogen blow water discharged from the hydrogen gas-liquid separator 12 has been considered to be pure water. However, the inventors of the present invention have clarified that the hydrogen blow water contains ionic components that are ionic impurities, and that the electrical conductivity increases due to the influence of these ionic components. Such ionic components cannot be removed by the coarse filter 41, and problems such as deterioration of the water electrolytic cell 10 arise when the hydrogen blow water with high electrical conductivity is reused for hydrogen production.

Therefore, in the water electrolysis system 100, an RO filter device 80 is placed downstream of the coarse filter device 30, and the ionic components contained in the hydrogen blow water are removed by a reverse osmosis membrane 81.

Figure 6 is a schematic diagram explaining the function of the reverse osmosis membrane 81 provided in the RO filter device 80 shown in Figure 2. As shown in Figure 6, the RO filter device 80 includes a reverse osmosis membrane 81 and a housing 82 that houses the reverse osmosis membrane 81. The reverse osmosis membrane 81 and the housing 82 are, for example, cylindrical. The cartridge-type reverse osmosis membrane 81 is housed in the housing 82 so that the central axis of the reverse osmosis membrane 81 and the central axis of the housing 82 are approximately aligned.

The reverse osmosis membrane 81 removes ionic components contained in the hydrogen blow water. The reverse osmosis membrane 81 is arranged in the housing 81, for example, wound around the outer circumference of a pipe with many holes. This reverse osmosis membrane 81 may be modularized (device) so that it can be replaced periodically.

The reverse osmosis membrane 81 is made of a cross-linked polymer membrane with a mesh-like structure, and due to the size of the mesh, essentially only water molecules pass through the reverse osmosis membrane 81. This allows ionic components to be separated from the hydrogen blow water, resulting in high purification performance. The reverse osmosis membrane 81 separates ionic components from the hydrogen blow water so that the ratio of the electrical conductivity of the permeated water to the electrical conductivity of the concentrated water is, for example, in the range of 10% to 80%, preferably 20% to 25%.

The RO filter device 80 separates water molecules from impurities such as ionic components by applying a constant water pressure to the surface of a reverse osmosis membrane 81 and passing hydrogen blow water over it. The RO filter device 80 extracts the permeated water that has permeated the reverse osmosis membrane 81 as pure water from an outlet 84, and discharges concentrated water that has not permeated the reverse osmosis membrane 81 from a drain outlet 85.

The housing 82 is a generally cylindrical case that houses the reverse osmosis membrane 81. The housing 82 is formed with an inlet 83 for taking in hydrogen blow water that has permeated the coarse filter device 30, an outlet 84 for taking out permeated water that has permeated the reverse osmosis membrane 81, and a drain 85 for draining concentrated water that has not permeated the reverse osmosis membrane 81. The hydrogen line 19 is connected to the inlet 83 and the outlet 84. In addition, the drain 85 is connected to a drain line 19b that drains concentrated water outside the system.

In the water electrolysis device 100, the ionic components contained in the hydrogen blow water are removed by the reverse osmosis membrane 81 arranged between the hydrogen gas-liquid separator 12 and the water storage tank 15, so that the ionic components contained in the permeate can be reduced. In addition, in the water electrolysis device 100, the pressure difference between the pressure (high pressure) on the hydrogen gas-liquid separator 12 side and the pressure (low pressure) on the water storage tank 15 side is utilized, so there is no need to add a power source such as a pump to the hydrogen line 19. Therefore, with the water electrolysis device 100, the ionic components contained in the hydrogen blow water can be removed without adding a power source, and the permeate with reduced ionic components can be reused for hydrogen production.

In addition, it is generally known that the reverse osmosis membrane 81 is vulnerable to oxidizing agents, but in the water electrolysis device 100, the reverse osmosis membrane 81 is arranged in the hydrogen line 19. Therefore, the water electrolysis device 100 can remove ionic components contained in the hydrogen blow water while preventing deterioration of the reverse osmosis membrane 81 caused by oxidizing agents.

[Control of Water Electrolysis Apparatus]
(Flow rate control of permeate)
Fig. 7 is a flowchart showing an example of control of the flow rate of the permeated water in the water electrolysis apparatus 100. The controller 20 controls the flow rate of the permeated water by adjusting the valve opening of the control valve 91. When the water electrolysis apparatus 100 is stopped, the control valve 91 is closed, and when the operation of the water electrolysis apparatus 100 is started, the controller 20 repeatedly executes the control shown in Fig. 7.

When flow rate control is started, the control unit 20 determines whether the water electrolytic cell 10 is in operation (S1). For example, the control unit 20 determines whether the water electrolytic cell 10 is in operation based on the state of power supply from the DC power source 11 to the water electrolytic cell 10, etc. If the control unit 20 determines that the water electrolytic cell 10 is in operation (YES in S1), the control unit 20 opens the control valve 91 so that the valve opening degree is the initial setting value (S2). On the other hand, if the control unit 20 determines that the water electrolytic cell 10 is not in operation (NO in S1), the control unit 20 keeps the control valve 91 closed.

Next, after opening the control valve 91 in S2, the control unit 20 determines whether the liquid level L2 of the hydrogen gas-liquid separator 12 is higher than the reference level CL (S3).

Figure 8 is a cross-sectional view showing the internal structure of the hydrogen-gas-liquid separator 12 shown in Figure 1. As shown in Figure 8, the hydrogen-gas-liquid separator 12 has three preset levels: a reference level CL (e.g., 200 mm) which is a reference liquid level L2, a high adjustment level MH (e.g., 220 mm) where the liquid level L2 is higher than the reference level CL, and a low adjustment level ML (e.g., 180 mm) where the liquid level L2 is lower than the reference level CL. Figure 8 illustrates a state in which the liquid level L2 of the hydrogen-gas-liquid separator 12 is located between the reference level CL and the high adjustment level MH.

If the liquid level L2 of the hydrogen gas-liquid separator 12 suddenly changes, the pressure balance between the oxygen side and the hydrogen side of the water electrolysis device 100 will be lost, and the polymer electrolyte membrane and other components may be damaged. Therefore, in the water electrolysis device 100, the flow of the permeate is adjusted based on the liquid level L2 of the hydrogen gas-liquid separator 12, thereby adjusting the flow rate of the permeate while maintaining the pressure balance between the oxygen side and the hydrogen side.

Specifically, the control unit 20 acquires a measurement value of the liquid level L2 of the hydrogen gas-liquid separator 12 via the signal line SL1, and judges whether the acquired liquid level L2 is higher than the reference level CL. If it is judged that the liquid level L2 is higher than the reference level CL (YES in S3), the control unit 20 controls the control valve 91 to increase the valve opening degree from the initial setting value (S4). As a result, the control unit 20 increases the flow rate of the permeate flowing through the hydrogen line 19, and lowers the liquid level L2 of the hydrogen gas-liquid separator 12 to approach the reference level CL. On the other hand, if it is judged that the liquid level L2 is equal to or lower than the reference level CL (NO in S3), the control unit 20 judges whether the liquid level L2 of the hydrogen gas-liquid separator 12 is higher than the low adjustment level ML (S5).

If the control unit 20 determines that the liquid level L2 is higher than the low adjustment level ML (YES in S5), the control unit 20 controls the control valve 91 to make the valve opening smaller than the initial setting value (S6). As a result, the control unit 20 reduces the flow rate of the permeate flowing through the hydrogen line 19, and raises the liquid level L2 of the hydrogen gas-liquid separator 12 to approach the reference level CL. On the other hand, if the control unit 20 determines that the liquid level L2 is equal to or lower than the low adjustment level ML (NO in S5), the control unit 20 controls the control valve 91 to make the valve opening 0 (S7). As a result, the control unit 20 makes the flow rate of the permeate flowing through the hydrogen line 19 0, and raises the liquid level L2 of the hydrogen gas-liquid separator 12 to approach the reference level CL.

In this way, the control unit 20 appropriately adjusts the flow rate of the permeate based on the liquid level L2 of the hydrogen gas-liquid separator 12 while the water electrolysis cell 10 is in operation. This allows the flow of the permeate to be appropriately adjusted while maintaining the pressure balance between the oxygen side and the hydrogen side of the water electrolysis device 100.

(Control of drainage of concentrated water)
Fig. 9 is a flowchart showing an example of concentrated water discharge control in the water electrolysis apparatus 100. The controller 20 controls the timing of concentrated water discharge by switching between opening and closing of the on-off valve 93. When the water electrolysis apparatus 100 is stopped, the on-off valve 93 is closed, and when the operation of the water electrolysis apparatus 100 is started, the controller 20 repeatedly executes the control shown in Fig. 9.

When drainage control is started, the control unit 20 determines whether the water electrolysis bath 10 is in operation (S11). If it is determined that the water electrolysis bath 10 is in operation (YES in S11), the control unit 20 resets the counter and starts counting (S12). On the other hand, if it is determined that the water electrolysis bath 10 is not in operation (NO in S11), the control unit 20 keeps the on-off valve 93 closed.

Next, the control unit 20 judges whether a predetermined time has elapsed since the start of counting (S13). If it is judged that the predetermined time has elapsed since the start of counting (YES in S13), the control unit 20 judges whether the liquid level L2 of the hydrogen gas-liquid separator 12 is higher than the low adjustment level ML (S14). If it is judged that the liquid level L2 is higher than the low adjustment level ML (YES in S14), the control unit 20 controls the on-off valve 93 to open the valve (S15). This allows the concentrated water to flow through the drain line 19b, and the concentrated water discharged from the RO filter device 80 is discharged outside the system. On the other hand, if it is judged that the liquid level L2 is equal to or lower than the low adjustment level ML (NO in S14), the control unit 20 keeps the control valve 91 closed.

On the other hand, if it is determined that the predetermined time has not elapsed since the start of counting in S13 (NO in S13), that is, between the start of counting and the elapse of the predetermined time, the control unit 20 determines whether the liquid level L2 of the hydrogen gas-liquid separator 12 is higher than the high adjustment level MH (S16).

If it is determined that the liquid level L2 is higher than the high adjustment level MH (YES in S16), the control unit 20 controls the on-off valve 93 to open the valve (S15). This allows the concentrated water to flow through the drain line 19b, and the concentrated water discharged from the RO filter device 80 is discharged outside the system.

If the liquid level L2 becomes higher than the high adjustment level MH between the start of counting in S12 and the lapse of a predetermined time, there is a possibility that the reverse osmosis membrane 81 is clogged or the polymer electrolyte membrane is damaged. Therefore, if it is determined that the liquid level L2 is higher than the high adjustment level MH (YES in S16), abnormality determination control is executed to determine whether or not there is a possibility that an abnormality has occurred in the water electrolysis device 100. Details of the abnormality determination control will be described later.

Next, after opening the on-off valve 93 in S15, the control unit 20 determines whether the liquid level L2 has fallen below the low adjustment level ML (S17). If it is determined that the liquid level L2 is not below the low adjustment level ML (NO in S17), the control unit 20 continues S17 until the liquid level L2 falls below the low adjustment level ML. On the other hand, if it is determined that the liquid level L2 is below the low adjustment level ML (YES in S17), the control unit 20 closes the on-off valve 93 and stops draining the concentrated water (S18).

In this way, the control unit 20 appropriately adjusts the timing of draining the concentrated water based on the liquid level L2 of the hydrogen gas-liquid separator. This makes it possible to appropriately adjust the drainage of the concentrated water while maintaining the pressure balance between the oxygen side and the hydrogen side of the water electrolysis device 100.

The control unit 20 may control the opening and closing of the on-off valve 93 so that the concentrated water is periodically drained regardless of the liquid level L2 of the hydrogen gas-liquid separator. In this way, by periodically draining the concentrated water, clogging of the reverse osmosis membrane 81 can be prevented.

(Abnormality Judgment Control)
Fig. 10 is a flowchart showing an example of the abnormality determination control shown in Fig. 9. For example, if the liquid level L2 of the hydrogen gas-liquid separator 12 suddenly becomes higher than the high adjustment level MH within a predetermined period of time after the start of operation of the water electrolytic cell 10, there is a possibility that the reverse osmosis membrane 81 is clogged, the polymer electrolyte membrane is damaged, or the like.

Therefore, if it is determined in S16 that the liquid level L2 is higher than the high adjustment level MH (YES in S16), the control unit 20 executes an abnormality determination to determine whether or not there is a possibility that an abnormality has occurred in the water electrolysis device 100.

In the abnormality determination control, the control unit 20 determines whether or not there is a possibility of an abnormality occurring in the water electrolysis device 100 based on the amount of water flowing into the hydrogen gas-liquid separator 12 and the oxygen gas-liquid separator 13, the operating status of the water electrolysis cell 10 related to the amount of water passing through the reverse osmosis membrane 81, the valve opening degree of the control valve 91, etc. (S21).

For example, if the permeate is not flowing easily through the hydrogen line 19, specifically if the flow rate of the permeate relative to the opening of the control valve 91 is less than a predetermined threshold, the reverse osmosis membrane 81 may be clogged. Also, if the liquid level L2 in the hydrogen gas-liquid separator 12 does not decrease even when the on-off valve 93 is opened, specifically if the liquid level L2 does not fall below the high adjustment level MH even after a certain amount of time has elapsed since the on-off valve 93 was opened in S15 shown in FIG. 9, damage to the polymer electrolyte membrane or the like may have occurred. In such a case, the control unit 20 determines that an abnormality may have occurred in the water electrolysis device 100.

In addition to the valve opening of the control valve 91, the ease (difficulty) of the permeate flow is affected by the values of the hydrogen blow water temperature (viscosity), the pressure difference before and after the reverse osmosis membrane 81, and the electrolysis current in the water electrolysis cell 10 (proportional to the amount of permeate through the polymer electrolyte membrane). Therefore, the control unit 20 may obtain at least one of these values in addition to the valve opening of the control valve 91 to determine whether or not there is a possibility that the reverse osmosis membrane 81 is clogged.

When it is determined that there is a possibility that an abnormality has occurred in the water electrolysis device 100 (YES in S21), the control unit 20 warns the user that there is a possibility that an abnormality has occurred in the water electrolysis device 100 (S22). The method of issuing the warning is not particularly limited, but examples include displaying the warning content on a display, turning on a warning light, or emitting a warning sound. On the other hand, when it is determined that there is no possibility that an abnormality has occurred in the water electrolysis device 100 (NO in S21), the control unit 20 ends the abnormality determination control without issuing a warning.

[Effects of water electrolysis device]
As described above, the water electrolysis apparatus 100 includes the water electrolysis cell 10 that decomposes water using a polymer electrolyte membrane to generate hydrogen at the cathode, the hydrogen gas-liquid separator 12 that separates the hydrogen and water generated at the cathode and releases the water as separated water, the RO filter device 80 that includes the reverse osmosis membrane 81 that removes ion components contained in the hydrogen blow water released from the hydrogen gas-liquid separator 12, and the water storage tank 15 that stores the permeated water that has permeated through the reverse osmosis membrane 81.

In the water electrolysis device 100, the reverse osmosis membrane 81 arranged between the hydrogen gas-liquid separator 12 and the water storage tank 15 removes ionic components contained in the hydrogen blow water, thereby reducing the ionic components contained in the permeate. Therefore, according to this embodiment, it is possible to realize a water electrolysis device 100 in which the permeate with reduced ionic components can be reused for hydrogen production.

In addition, the water electrolysis device 100 makes it possible to reuse hydrogen blow water with reduced ionic components for hydrogen production, thereby reducing the consumption (supplement) of pure water. This can contribute to the achievement of the Sustainable Development Goals (SDGs).

[Software implementation example]
The functions of the control unit 20 can be realized by a program for causing a computer to function as the control unit 20 .

In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The functions described in each of the above embodiments are realized by executing the program using this control device and storage device.

The program may be non-transiently recorded on one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

In addition, some or all of the functions of each of the control blocks can be realized by a logic circuit. For example, an integrated circuit in which a logic circuit that functions as each of the control blocks is formed is also included in the scope of the present invention.

〔summary〕
A water electrolysis apparatus according to a first aspect of the present invention includes a water electrolysis cell that decomposes water using a polymer electrolyte membrane to generate hydrogen at a cathode, a hydrogen-gas-liquid separator that separates the hydrogen and water generated at the cathode and releases the water as separated water, a filter device including a reverse osmosis membrane that removes ionic components contained in the separated water released from the hydrogen-gas-liquid separator, and a water storage tank that stores the permeated water that has permeated through the reverse osmosis membrane.

In the above configuration, the reverse osmosis membrane arranged between the hydrogen gas-liquid separator and the water tank removes ionic components contained in the separated water, thereby reducing the ionic components contained in the permeated water. Therefore, with the above configuration, the permeated water with reduced ionic components can be reused for hydrogen production.

The water electrolysis device according to aspect 2 of the present invention may further include a first adjustment mechanism disposed between the filter device and the water storage tank and configured to adjust the flow of the permeate.

When the water electrolysis device is in operation, the hydrogen gas-liquid separator is pressurized, and the hydrogen gas-liquid separator side is at a higher pressure than the water tank side. If a first adjustment mechanism were placed between the hydrogen gas-liquid separator and the filter device (i.e., upstream of the filter device), the first adjustment mechanism could cause a pressure drop in the separated water flowing into the filter device. With the above configuration, the first adjustment mechanism is placed between the filter device and the water tank, i.e., downstream of the filter device, so that the above-mentioned pressure drop in the separated water flowing into the filter device can be avoided.

In the water electrolysis device according to aspect 3 of the present invention, in the above aspect 2, the first adjustment mechanism may adjust the flow of the permeate based on the liquid level of the hydrogen gas-liquid separator.

If the liquid level in the hydrogen gas-liquid separator suddenly changes, the pressure balance between the oxygen side and hydrogen side of the water electrolysis device will be lost, and the polymer electrolyte membrane, etc., may be damaged. According to the above configuration, by adjusting the flow of the permeate based on the liquid level in the hydrogen gas-liquid separator, the flow (flow rate) of the permeate can be adjusted while maintaining the pressure balance between the oxygen side and the hydrogen side.

The water electrolysis device according to aspect 4 of the present invention may further include a first separation mechanism arranged downstream of the first adjustment mechanism and configured to separate hydrogen contained in the permeate, in accordance with aspect 2 or 3.

When the pressure of the permeated water is reduced by the action of the first adjustment mechanism, hydrogen dissolved in the permeated water turns into bubbles in the permeated water. According to the above configuration, by disposing the first separation mechanism downstream of the first adjustment mechanism, hydrogen (bubbles) can be separated from the permeated water.

The water electrolysis device according to aspect 5 of the present invention may further include, in any one of aspects 1 to 4, a drain line for draining concentrated water resulting from the separated water being concentrated without passing through the reverse osmosis membrane from the filter device, and a second adjustment mechanism disposed in the drain line for adjusting the flow of the concentrated water.

According to the above configuration, by discharging concentrated water from the filter device, clogging (fouling) of the reverse osmosis membrane can be prevented. In addition, by adjusting the flow of concentrated water discharged from the filter device with the second adjustment mechanism, the amount of discharge or the timing of discharge can be controlled.

In the water electrolysis device according to aspect 6 of the present invention, in the above aspect 5, the second adjustment mechanism may adjust the flow of the concentrated water in the drain line based on the liquid level of the hydrogen gas-liquid separator, or so that the concentrated water is periodically drained.

According to the above configuration, by adjusting the flow of concentrated water based on the liquid level of the hydrogen gas-liquid separator, concentrated water can be discharged while maintaining a pressure balance between the oxygen side and the hydrogen side. In addition, by periodically discharging concentrated water, clogging of the reverse osmosis membrane can be prevented.

The water electrolysis device according to aspect 7 of the present invention may further include a second separation mechanism arranged downstream of the second adjustment mechanism and configured to separate hydrogen contained in the concentrated water in accordance with aspect 5 or 6.

When the pressure of the concentrated water is reduced by the action of the second adjustment mechanism, the hydrogen dissolved in the concentrated water turns into bubbles in the concentrated water. According to the above configuration, the hydrogen (bubbles) can be separated from the concentrated water by disposing the second separation mechanism downstream of the second adjustment mechanism.

A method for controlling a water electrolysis apparatus according to an eighth aspect of the present invention is a method for controlling a water electrolysis apparatus, the method comprising: decomposing water using a polymer electrolyte membrane to generate hydrogen at a cathode; separating the hydrogen and water generated at the cathode using a hydrogen gas-liquid separator, and discharging the water as separated water;
and a step of adjusting the flow of the permeated water that has permeated through the reverse osmosis membrane of a filter device including a reverse osmosis membrane that removes ionic components contained in the separated water, based on the liquid level of the hydrogen gas-liquid separator.

In the above method, the ionic components contained in the separated water are removed by the reverse osmosis membrane, so the ionic components contained in the permeated water can be reduced. Therefore, according to the above method, the permeated water with reduced ionic components can be reused for hydrogen production.

In addition, if the liquid level in the hydrogen gas-liquid separator suddenly changes, the pressure balance between the oxygen side and hydrogen side of the water electrolysis device will be lost, and the polymer electrolyte membrane, etc., may be damaged. According to the above method, by adjusting the flow of the permeate based on the liquid level in the hydrogen gas-liquid separator, it is possible to adjust the flow of the permeate while maintaining the pressure balance between the oxygen side and the hydrogen side.

In the method for controlling a water electrolysis apparatus according to aspect 9 of the present invention, in the above aspect 8, the water electrolysis apparatus further includes a drain line for draining from the filter device concentrated water resulting from the separated water being concentrated without passing through the reverse osmosis membrane, and may further include a step of adjusting the flow of the concentrated water in the drain line based on the liquid level of the hydrogen gas-liquid separator or so that the concentrated water is periodically drained.

According to the above method, the flow of concentrated water can be adjusted based on the liquid level in the hydrogen gas-liquid separator, so that concentrated water can be discharged while maintaining a pressure balance between the oxygen side and the hydrogen side. Alternatively, according to the above method, clogging of the reverse osmosis membrane can be prevented by periodically discharging concentrated water.

The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the disclosed technical means.

10 Water electrolysis cell 12 Hydrogen gas-liquid separator 15 Water storage tank 80 RO filter device (filter device)
81 reverse osmosis membrane 91 control valve (first adjustment mechanism)
92 First separator (first separation mechanism)
93 Opening/closing valve (second adjustment mechanism)
94 Adjustment valve (second adjustment mechanism)
95 Second separator (second separation mechanism)
100 Water electrolysis device L2 Liquid level

Claims (9)

a water electrolysis cell that splits water using a polymer electrolyte membrane and generates hydrogen at a cathode;
a hydrogen gas-liquid separator that separates the hydrogen and water generated at the cathode and releases the water as separated water;
a filter device including a reverse osmosis membrane for removing ion components contained in the separated water discharged from the hydrogen gas-liquid separator;
a water storage tank for storing the permeated water that has permeated the reverse osmosis membrane;
A water electrolysis device comprising: The water electrolysis device according to claim 1, further comprising a first adjustment mechanism disposed between the filter device and the water storage tank, for adjusting the flow of the permeate. The water electrolysis device according to claim 2, wherein the first adjustment mechanism adjusts the flow of the permeate based on the liquid level of the hydrogen gas-liquid separator. The water electrolysis device according to claim 2 or 3, further comprising a first separation mechanism arranged downstream of the first adjustment mechanism and separating hydrogen contained in the permeate. a drain line for draining concentrated water resulting from the separated water being concentrated without permeating the reverse osmosis membrane from the filter device;
A second adjustment mechanism disposed in the drain line and adjusting the flow of the concentrated water;
The water electrolysis apparatus according to claim 1 , further comprising: The water electrolysis device according to claim 5, wherein the second adjustment mechanism adjusts the flow of the concentrated water in the drain line based on the liquid level of the hydrogen gas-liquid separator or so that the concentrated water is periodically drained. The water electrolysis device according to claim 5 or 6, further comprising a second separation mechanism arranged downstream of the second adjustment mechanism and configured to separate hydrogen contained in the concentrated water. A method for controlling a water electrolysis apparatus, comprising:
splitting water using a polymer electrolyte membrane to generate hydrogen at a cathode;
a step of separating the hydrogen and water generated at the cathode using a hydrogen gas-liquid separator and discharging the water as separated water;
a step of adjusting a flow of the permeated water that has permeated through a reverse osmosis membrane of a filter device including a reverse osmosis membrane for removing ionic components contained in the separated water, based on a liquid level of the hydrogen gas-liquid separator;
storing the permeate in a water storage tank;
A method for controlling a water electrolysis apparatus comprising the steps of: the water electrolysis apparatus further includes a drainage line for draining concentrated water produced when the separated water is concentrated without passing through the reverse osmosis membrane from the filter device,
9. The method for controlling a water electrolysis apparatus according to claim 8, further comprising adjusting a flow of the concentrated water in the drain line based on a liquid level in the hydrogen gas-liquid separator or such that the concentrated water is drained periodically.

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