JP2004107775A - Water electrolysis device and operation method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water electrolysis device and an operation method thereof for maintaining a moist state without exposing an electrolytic membrane in gas and adequately maintaining water quality even when the device is fully stopped. <P>SOLUTION: An electrolytic cell outlet side piping system which has control valves (24 and 25) to close circulation of pure water when a pump is stopped between inlet manifolds (101a and 101b) and water discharge sides of pumps (5 and 6) and which connects an anode chamber and a cathode chamber to vapor-liquid separators (13 and 14) comprises: outlet manifolds (102a and 102b) provided adjacent to and above electrolytic membranes (100a and 100b); and electrolytic cell outlet pipes (11 and 12) connected to the upper side portions of the vapor-liquid separators from the upper portions of the outlet manifolds. The volume of the electrolytic cell outlet side piping system from the upper ends of the electrolytic membranes to the highest point (the position F) of the electrolytic cell outlet side piping system is not less than the preliminarily calculated volume of the gas including the gas generated during the electrolytic operation in a water electrolysis cell 1 and the gas generated in the system from the upper ends of the electrolytic membranes to the highest position (the position F) of the electrolytic cell outlet side piping system. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a water electrolysis apparatus using an electrolyte membrane such as a solid polymer and a method of operating the same.
[0002]
[Prior art]
Separation into an anode (anode) side and a cathode (cathode) side using an electrolyte membrane of a solid polymer or the like as a membrane, electrolysis while supplying pure water or water containing ions to the anode side, and oxygen from the anode side In recent years, development of a water electrolysis apparatus configured to generate gas from the cathode side to generate hydrogen gas has been advanced, and various proposals have been made regarding the system configuration, stack structure, operation method, and the like (for example, And Patent Documents 1 and 2).
[0003]
Patent Literature 1 describes a general basic system configuration, and Patent Literature 2 discloses that an ion exchange resin tank is provided at a feed water inlet so that an impurity ion contained in water to be electrolyzed is provided. However, there is described a system configuration for preventing adhesion and accumulation on a solid polymer electrolyte membrane to lower the electrolytic performance.
[0004]
FIG. 4 shows a system diagram of a conventional water electrolysis apparatus using a solid polymer electrolyte membrane described with reference to the prior art. In FIG. 4, the interior of the water electrolysis cell 1 is divided into a cathode chamber and an anode chamber by a solid polymer electrolyte membrane. Each of the cathode chamber and the anode chamber includes a catalyst electrode and a porous power supply (not shown).
[0005]
The solid polymer electrolyte membrane is widely used for industrial purposes, and a typical example is a perfluorocarbon sulfonic acid membrane. A material having high conductivity such as a titanium fiber or a stainless fiber sintered plate is used as the power supply. Supplied to the anode side ^{_{water, 2H 2 0 → 0 2 +}} 4H + + 4e - is decomposed by reaction with, for generating oxygen. H ⁺ passes through the sulfone group of the electrolyte membrane, a reaction of 4H ⁺ + 4e ⁻ → 2H ₂ occurs on the cathode side, and hydrogen gas is generated.
[0006]
In FIG. 4, on the anode side of a water electrolysis cell (hereinafter, also simply referred to as electrolysis cell) 1, pure water passing through a pure water device 2 is supplied from an external to an external pure water supply line 4 by a supply pump 3. Supplied via Pure water in each electrode of the electrolytic cell is circulated by the anode-side circulation pump 5 and the cathode-side circulation pump 6 via the electrolytic cell inlet pipes 7 and 8, the electrolytic cell outlet pipes 11 and 12, and the return pipes 9 and 10. Is done. The outlet pipes 11, 12 of the electrolytic cell are connected to gas-liquid separators 13, 14.
[0007]
From the gas-liquid separators 13 and 14, in addition to return pipes 9 and 10 to the entrance of the electrolytic cell, pipes 15 and 16 for extracting separated generated gas (hydrogen and oxygen) are provided. Connected. The gas coolers 17 and 18 are connected to pipes 19 and 20 for returning condensed water to the gas-liquid separators 13 and 14, and pipes 21 and 22 for extracting gas from the water electrolysis device. In order to avoid concentration of impurities in the pure water, a blowdown pipe 23 for discharging a part of the pure water out of the system is connected to the inlet pipe 7 on the anode side. Although not shown, a wiring lead for supplying electric power for electrolysis is connected to the electrolytic cell 1.
[0008]
Next, the operation of the above device will be described below. When power is supplied from a wiring lead (not shown) in an apparatus having a configuration as shown in FIG. 4, electrolysis of water occurs in the electrolytic cell 1, and a mixed flow of pure water and generated gas flows through pipes 11 and 12. The liquid flows into the liquid separators 13 and 14. In the gas-liquid separators 13 and 14, pure water and generated gas are separated, and the pure water is returned to the electrolytic cell 1 again by the circulation pumps 5 and 6 via the pipes 9 and 10. After the gas generated by the electrolysis is separated by the gas-liquid separators 13 and 14, it is cooled by the water coolers 17 and 18 and separated into condensed water and gas. The condensed water is returned to the gas-liquid separators 13 and 14 via the pipes 19 and 20. The cooled gas is sent out of the water electrolysis device via the pipes 21 and 22.
[0009]
In addition, pure water required for the electrolysis reaction is used to remove impurities in the water, which may contaminate the electrolyte membrane or the like and lower the characteristics of the electrolytic cell (increase the electrolysis voltage). Is supplied to the anode side via the pure water apparatus 2 of the above. In order to maintain the electrolysis temperature at a constant level (for example, 80 ° C.) and to quickly discharge generated gas to the outside of the electrolytic cell, the amount of water in both the electrodes is several tens of times the supply amount of pure water for electrolysis. Is circulating.
[0010]
Further, with the operation, the amount of water several times the amount of water to be electrolyzed moves from the anode side to the cathode side through the electrolyte membrane. This is due to the entrainment of water when ions pass through the electrolyte membrane. According to an example of experimental results, about 7 to 9 times the amount of water moves from the anode side to the cathode side through the electrolyte membrane. I do. As described above, since the pure water on the cathode side is increased, the pure water on the cathode side is kept constant by discharging the moving water amount to the outside of the apparatus system or returning it to the anode side. Need to be adjusted. In FIG. 4, a pump 27 is a pump provided on a line connecting between the gas-liquid separators for returning the moving water to the anode side. The adjustment of the amount of water is usually performed by monitoring a liquid level gauge or the like installed in a gas-liquid separator or the like.
[0011]
Further, even through a pure water apparatus, impurities cannot be completely removed from pure water, and trace components remain. The impurities are captured by the electrolyte membrane when pure water passes through the electrode membrane, and become a factor that causes the contamination of the electrolyte membrane and the deterioration of the characteristics of the electrolytic cell. On the other hand, pure water on the cathode side that has passed through the electrolyte membrane is cleaner than pure water on the anode side, and the electrical resistivity is improved. This improvement ratio becomes remarkable when the quality of pure water in the apparatus is reduced, and the electrical resistivity of the cathode-side pure water may be twice or more the electrical resistivity of the anode.
[0012]
Furthermore, the pure water for electrolysis supplied to the device is discharged to the outside of the device as a generated gas or water vapor in the generated gas by electrolysis, but trace impurities (such as alkali metal ions) are not entrained in the gas or water vapor. Then, the water in the apparatus is concentrated as the operation is continued. As the concentration progresses, the characteristics of the electrolytic cell deteriorate. Therefore, in the water electrolysis apparatus, an appropriate amount of water is discharged from the blowdown pipe 23 to the outside of the apparatus to suppress the excessive concentration of impurities.
[0013]
[Patent Document 1]
JP-A-2000-54175 (page 2, FIG. 2)
[Patent Document 2]
Full-text specification of Japanese Utility Model Laid-Open No. 2-51263 (pages 16 to 23, Fig. 1)
[0014]
[Problems to be solved by the invention]
By the way, the conventional water electrolysis apparatus has the following problems related to the maintenance of the electrolyte membrane which is required even when starting and stopping the electrolysis operation.
[0015]
The electrolyte membrane of the electrolytic cell is generally unable to maintain its properties as an electrolyte membrane when dried, and because of the risk of damage to the membrane due to dimensional change due to dry-wet, usually at any part of the electrolytic cell. In order to keep the electrolyte membrane wet, pure water that can maintain a mixed flow of the generated gas and pure water as well as the generated gas around the electrolyte membrane is circulated and supplied.
[0016]
As described above, the cathode side can maintain the wetness of the electrolytic chamber membrane only by the moving water amount from the anode side without external supply. On the other hand, on the anode side, a device for supplying and circulating appropriate pure water is required. The anode side is replenished with the amount of waste water to the outside of the system, the amount of water vapor contained in the generated gas and discharged to the outside of the system, and the amount of water converted into gas by electrolysis. As described above, the amount of wastewater discharged outside the system includes blowdown water for preventing the concentration of impurities in pure water in the system. The amount of water in these systems is controlled to an appropriate range by a water level gauge installed in a gas-liquid separator or the like.
[0017]
Incidentally, a gas-liquid mixed flow of gas and pure water in the electrolysis cell during operation and in the pipe from the electrolysis cell to the gas-liquid separator increases the apparent liquid phase volume in the system. In a water electrolysis apparatus in such an operating state, when all devices of the apparatus including the electrolysis operation are stopped due to an operation stop command or loss of control power due to an abnormality, the pump for water circulation is stopped together with the electrolysis stop. Thus, the gas in the mixed flow in the system will be gathered upward in the system. At this time, if the volume above the electrolyte membrane of the electrolytic cell is equal to or less than the volume of the gas contained in the system, the upper portion of the electrolyte membrane is left in the gas until the operation of the apparatus is recovered, and the wet state cannot be maintained. There is danger.
[0018]
Also, when the electrolysis current of the water electrolysis device rapidly increases and decreases (including start / stop), the apparent liquid volume in the system changes, and there is a risk that the control water level changes and deviates from the control width. Even when the electrolysis operation is stopped, in order to maintain the water quality of the electrolysis cell and reduce the damage of the electrolysis cell (adhesion of impurities, etc.), it is necessary to use a pump for circulating pure water or a pump for supplying external pure water. It is preferable that the operation be continued.
[0019]
However, as described above, when the water level deviates from the control range, it is not preferable in terms of safety of the apparatus to perform control to prevent an emergency stop of the apparatus.
[0020]
The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a method for controlling the presence of gas in circulating water even when the system is completely stopped due to loss of control power during electrolysis operation. It is an object of the present invention to provide a water electrolysis apparatus capable of preventing an electrolyte membrane from being exposed to gas and dried by gathering above in an electrolytic cell or a pipe. Furthermore, in addition to the electrolyte membrane exposure / drying prevention function, a water level fluctuation accompanying an electrolytic current change (input, cut-off, increase, phenomenon) during the electrolytic operation does not cause any stop of the apparatus other than the electrolytic operation, ie, pure water. The operation of the circulation pump and the pump for supplying external pure water is to provide a continuous water electrolysis apparatus and an operation method thereof.
[0021]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a water electrolysis cell in which an interior is partitioned into an anode chamber and a cathode chamber by an electrolyte membrane such as a solid polymer, and a pump for pure water circulation, the anode chamber having Separate pure water circulation circuits on the anode side (anode side) and cathode side (cathode side) each including a gas-liquid separator individually connected to the cathode chamber, and an external supply of pure water from the outside to the water electrolysis cell In a water electrolysis apparatus provided with a pure water supply line, an on-off valve or a reverse valve for closing the circulation of pure water when the pump is stopped is provided between each inlet manifold of the anode chamber and the cathode chamber and the water discharge side of the pump. An electrolytic cell outlet piping system that includes a stop valve and connects the anode chamber and the cathode chamber to each of the gas-liquid separators is provided with an outlet manifold provided above the anode chamber and the cathode chamber adjacent to the electrolyte membrane. And this exit mani And an electrolytic cell outlet pipe connected to the upper side of the gas-liquid separator from above the fuel cell, and an electrolytic cell outlet pipe from the upper end of the electrolyte membrane to the highest point of the electrolytic cell outlet pipe system. The volume in the system is equal to or larger than a predetermined gas volume generated during the electrolysis operation and contained in the water electrolysis cell and in the system from the upper end of the electrolyte membrane to the highest point of the piping system on the outlet side of the electrolytic cell. (The invention of claim 1).
[0022]
According to the configuration, as described in detail below, even when the apparatus is completely stopped, the electrolyte membrane can be exposed to the gas by the gas in the circulating water gathering above the electrolytic cell and the piping. Therefore, the wet state of the electrolyte membrane can be maintained. The gas volume can be obtained in advance by calculation as follows, and the internal volume is set based on this.
[0023]
The gas volume is determined by correcting a theoretical gas amount (normal gas amount) that can be calculated from the operation maximum electrolysis current by a design operation pressure and a design operation temperature of the apparatus with a slight margin. Here, the margin is determined in consideration of a deviation due to a change in the system pressure and the system temperature during operation transition, and a design safety factor.
[0024]
Further, the above problem can be solved by the invention of claim 2 described below. That is, a water electrolysis cell whose interior is partitioned into an anode chamber and a cathode chamber by an electrolyte membrane such as a solid polymer, and a gas having a pump for pure water circulation and individually connected to the anode chamber and the cathode chamber. A water electrolysis system having separate pure water circulation circuits on the anode side (anode side) and the cathode side (cathode side) each including a liquid separator, and an external pure water supply line for supplying pure water to the water electrolysis cell from outside. In the device, an electrolytic cell outlet piping system for connecting the anode chamber and the cathode chamber to each of the gas-liquid separators, and each outlet manifold provided above the anode chamber and the cathode chamber adjacent to the electrolyte membrane, An electrolytic cell outlet pipe connected from above the outlet manifold to an upper side of the gas-liquid separator, and the electrolytic cell outlet pipe system from the upper end of the electrolyte membrane to the top of the gas-liquid separator. And circulating water return piping system The volume in the pure water circulation circuit including the gas volume generated during the electrolysis operation and contained in the water electrolysis cell and the outlet piping system of the electrolysis cell and the gas-liquid separator should be equal to or larger than a predetermined gas volume. .
[0025]
Further, as an embodiment of the invention, the invention of the following claim 3 is preferable from the viewpoint of maintaining the water quality of the electrolytic cell section. That is, in the water electrolysis apparatus according to claim 1 or 2, the gas-liquid separator includes a high level H and a low level L for controlling a water level during the electrolysis operation, and a higher level than the H and L. A water level adjusting device is provided for controlling the water level at four positions (HH, H, L, LL) having a lower highest level HH and a lowest level LL, and the water level difference between HH-H is applied to the maximum electrolytic current. And the water level difference between LL and L is set to be equal to or greater than the water level fluctuation that occurs when the maximum electrolytic current is cut off.
[0026]
Furthermore, in the operation method of the water electrolysis device according to claim 3, when the input, cutoff, increase, and decrease of the electrolysis current are performed, when the water level is between the HH-LL, Control for continuing the operation of the water circulation and the water supply of the pure water circulation circuit and the external pure water supply line is performed (the invention of claim 4).
[0027]
According to the water electrolysis apparatus and the operation method thereof, even if the water level of the gas-liquid separator or the like changes due to the stoppage of the electrolysis operation or the rapid fluctuation of the electrolysis current, the water level abnormality due to other factors leading to the total stoppage of the apparatus is Detection can be performed separately, and control of the pure water supply / circulation system can be continued. Therefore, it is possible to perform an operation (standby operation without electrolysis) to maintain the water quality during the electrolysis operation in an appropriate state.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 show system diagrams of different embodiments of the water electrolysis apparatus of the present invention, and FIG. 3 shows details of an embodiment of the gas-liquid separator. 1 to 3, members having the same functions as those shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof and basic operation of the device will be omitted.
[0029]
First, the embodiment of FIG. 1 will be described. In the system diagram of the water electrolyzer of FIG. 1, the main points on the system diagram different from FIG. 4 are the inlet manifolds (101a, 101b) of the anode chamber and the cathode chamber and the water discharge sides of the pumps (5, 6). And an on-off valve (or a check valve) (24, 25) for closing the circulation of pure water when the pump is stopped, and an anode chamber and a cathode chamber, and each gas-liquid separator (13, 14). Is connected to the outlet manifolds (102a, 102b) provided above the anode chamber and the cathode chamber adjacent to the electrolyte membrane (and the catalyst laying part) (100a, 100b), and the outlets thereof. It is configured to have an electrolytic cell outlet pipe (11, 12) connected to the upper side of the gas-liquid separator (13, 14) from above the manifold.
[0030]
In FIG. 1, reference numeral 28 denotes an on-off valve of a pipe for returning water from the cathode side to the anode side, and reference numeral 30 denotes an on-off valve of a pure water supply pipe.
[0031]
In the above configuration, the volume in the electrolytic cell outlet piping system from the upper end of the electrolyte membrane (100a, 100b) to the highest point (F in the figure) of the electrolytic cell outlet piping system is generated during the electrolysis operation. The gas volume contained in the electrolytic cell 1 and the system from the upper end of the electrolyte membrane to the highest point (position F) of the piping system on the outlet side of the electrolytic cell should be equal to or larger than the gas volume calculated in advance. State.
[0032]
In the configuration of FIG. 1, the water phase state in the water electrolysis cell 1, each gas-liquid separator (13, 14), and each pipe in the system of the pure water circulation circuit is as shown in FIG.
[0033]
When a stop command or some abnormality is detected during the electrolysis operation, electrolysis stops and the circulation pumps (5, 6) stop, and the on-off valves (24, 25) are closed due to the pump stop, pure water in the system is discharged. Is divided into an electrolytic cell side and a return pipe side with the highest point F in the inside as a branch position. At this time, the gas mixed in the gas-liquid mixed phase between C and F on the electrolytic cell side is separated and gathers upward. Here, the volume between E and F of the electrolytic cell outlet manifolds (102a, 102b) and the electrolytic cell outlet pipes (11, 12) located above the electrolyte membranes (100a, 100b) of the water electrolysis cell 1 is determined by electrolysis. The electrolyte membrane (100a, 100b) is not exposed to the gas by setting the volume of the gas mixed between C and F on the cell side to be equal to or larger than the gas volume. The on-off valves (24, 25) may be check valves that automatically close the water flow when the pump stops.
[0034]
Next, the embodiment of FIG. 2 will be described. FIG. 2 is a system diagram showing an embodiment different from FIG. 1 of the present invention. The difference from FIG. 1 is that the on-off valves (24, 25) are not installed in the inlet pipes (7, 8) of the electrolytic cell. Is a point.
[0035]
In the case of the embodiment shown in FIG. 2, when the electrolysis is stopped and the circulation pumps (5, 6) are stopped, the pure water in the system is integrated as a whole and collects below the system. At this time, the total volume above the electrolyte membrane (100a, 100b) of the water electrolysis cell 1, that is, the volume above D and L, is equal to the gas volume mixed between C and F on the electrolysis cell side. The electrolyte membrane (100a, 100b) is not exposed to the gas by setting the gas volume in the liquid separator equal to or larger than the sum of the gas volumes.
[0036]
Next, the embodiment of FIG. 3 will be described. FIG. 3 shows a detailed view of the gas-liquid separator used in the water electrolysis device shown in FIGS. 1 and 2, and a water level gauge 29 is installed in the gas-liquid separator. The water level gauge 29 is provided with four set values HH, H, L, and LL. During normal electrolytic operation, control is performed so that the water level is adjusted between H and L.
[0037]
At this time, when the electrolysis operation is stopped and the operation of the circulation pumps (5, 6) is continued, the inlet G of the gas-liquid separator (13, 14) from the lower end C of the electrolyte membrane (100a, 100b) of the water electrolysis cell 1. During this time, the gas is pushed out into the gas-liquid separator, the apparent liquid phase volume decreases, and the water level in the gas-liquid separator drops sharply.
[0038]
If the amount of the decrease is lower than the L level of the water level gauge, it will deviate from the control range. In order to keep the amount of water in the electrolyzer at an appropriate level, a low-level alarm of the water level in the gas-liquid separator is usually required. However, it is not preferable that the L-level alarm causes the device to stop. Therefore, below the L level, an LL level having a width larger than the fluctuation range of the water level caused by the stop of the electrolysis operation is set. If the water level does not drop to this position, the operation of the device other than the electrolysis operation, that is, Control is performed to continue the operation of the pure water circulation pump and the external pure water supply pump.
[0039]
The phenomenon that the apparent liquid phase volume changes occurs not only when the electrolysis operation is stopped but also when the electrolysis current sharply decreases. The width between LL and L of the water level gauge can respond to any sudden decrease in the electrolytic current by providing a width that can cope with the change from the maximum possible operating load current to zero current (electrolysis stop). It becomes. At the start of the electrolysis operation or when the electrolysis current increases, a phenomenon opposite to the above-described operation occurs, and the water level of the gas-liquid separator rises sharply. This can be dealt with by providing a width equal to or greater than the fluctuation range of the water level occurring with respect to the maximum width of the conceivable current increase between HH and H of the water level meter.
[0040]
【The invention's effect】
As described above, according to the configuration of the present invention, even when the apparatus is completely shut down, the electrolyte membrane is exposed to the gas by the gas in the circulating water gathering above the electrolytic cells and pipes. And the wet state of the electrolyte membrane can be maintained.
[0041]
Further, by implementing the configuration and the operation method including the water level adjusting device for controlling the water level at the four positions (HH, H, L, LL), the gas-liquid separator is stopped due to the stop of the electrolysis operation or the rapid fluctuation of the electrolysis current. Even if the water level fluctuates, it can be detected separately from water level anomalies due to other causes, such as a total stoppage of the equipment, and the control of the pure water replenishment and circulation system can be continued, and the water quality during electrolysis operation suspension can be adjusted appropriately It is possible to perform an operation for maintaining the state.
[Brief description of the drawings]
FIG. 1 is a system diagram of an embodiment of a water electrolysis device of the present invention; FIG. 2 is a system diagram of an embodiment different from FIG. 1 of the water electrolysis device of the present invention; FIG. FIG. 4 is a system diagram showing an example of a conventional water electrolysis device. FIG. 5 is a diagram illustrating a water phase state of each device and a piping system in the water electrolysis device of FIG. Description】
1: water electrolysis cell, 2: pure water device, 3: supply pump, 4: external pure water supply line, 5, 6: circulation pump, 7, 8: piping with electrolytic cell, 9, 10: circulation water return piping , 11, 12: Electrolyte cell outlet pipe, 13, 14: Gas-liquid separator, 15, 16: Pipe for taking out generated gas (hydrogen / oxygen), 17, 18: Gas cooler, 19, 20: Return of condensed water Piping, 21, 22: Piping for taking out generated gas from water electrolysis device, 23: Plow-down piping, 24, 25: Opening / closing valve of electrolytic cell inlet piping, 26: Piping returning water from cathode side to anode side, 27: Cathode Pump for returning water from the side to the anode side, 28: an on-off valve for piping for returning water from the cathode side to the anode side, 29: a water level gauge for the gas-liquid separator, 30: an on-off valve for pure water supply piping, 100a, 100b: Electrolyte membrane, 101a, 101b: Mouth manifold, 102a, 102b: outlet manifold.

Claims (4)

A water electrolysis cell in which the interior is partitioned into an anode chamber and a cathode chamber by an electrolyte membrane such as a solid polymer, and gas-liquid separation having a pump for circulating pure water and individually connected to the anode chamber and the cathode chamber, respectively. In a water electrolysis apparatus provided with separate pure water circulation circuits on the anode side (anode side) and the cathode side (cathode side) each including a vessel, and an external pure water supply line for supplying pure water to the water electrolysis cell from outside. ,
Each of the anode chamber and the cathode chamber between each inlet manifold and the water discharge side of the pump, provided with an on-off valve or a check valve for closing the circulation of pure water when the pump is stopped,
An electrolytic cell outlet piping system for connecting the anode chamber and the cathode chamber with each of the gas-liquid separators includes an outlet manifold provided above the anode chamber and the cathode chamber adjacent to the electrolyte membrane, and the outlet manifold. And an electrolytic cell outlet pipe connected to the upper side of the gas-liquid separator from above,
In addition, the volume in the electrolytic cell outlet piping system from the upper end of the electrolyte membrane to the highest point of the electrolytic cell outlet piping system is generated during the electrolysis operation, and the volume of the electrolytic cell from the water electrolysis cell and from the upper end of the electrolyte membrane is increased. A water electrolysis apparatus wherein the gas volume contained in the system up to the highest point of the cell outlet piping system is not less than a predetermined gas volume. A water electrolysis cell in which the interior is partitioned into an anode chamber and a cathode chamber by an electrolyte membrane such as a solid polymer, and gas-liquid separation having a pump for circulating pure water and individually connected to the anode chamber and the cathode chamber, respectively. In a water electrolysis apparatus provided with separate pure water circulation circuits on the anode side (anode side) and the cathode side (cathode side) each including a vessel, and an external pure water supply line for supplying pure water to the water electrolysis cell from outside. ,
An electrolytic cell outlet piping system for connecting the anode chamber and the cathode chamber with each of the gas-liquid separators includes an outlet manifold provided above the anode chamber and the cathode chamber adjacent to the electrolyte membrane, and the outlet manifold. And an electrolytic cell outlet pipe connected to the upper side of the gas-liquid separator from above,
In addition, the volume in the pure water circulation circuit including the electrolytic cell outlet piping system and the circulating water return piping system from the upper end of the electrolyte membrane to the top of the gas-liquid separator is generated during the electrolysis operation. A water electrolysis apparatus characterized in that the gas volume contained in an electrolysis cell, the outlet pipe system of the electrolysis cell and the gas-liquid separator is not less than a predetermined gas volume. 3. The water electrolysis device according to claim 1, wherein the gas-liquid separator includes a high level H and a low level L for controlling a water level during the electrolysis operation, and a higher level and a lower level higher than H and L. 4. A water level control device for controlling the water level at four positions (HH, H, L, LL) having a lower level HH and a lower level LL, and the water level difference between HH-H is determined when the maximum electrolytic current is applied. A water electrolysis apparatus characterized in that the water level fluctuation is set to be equal to or higher than the water level fluctuation that occurs and the water level difference between LL and L is set to be equal to or higher than the water level fluctuation that occurs when the maximum electrolytic current is cut off. 4. The method for operating a water electrolysis apparatus according to claim 3, wherein when turning on / off, increasing, or decreasing an electrolysis current, when a water level is between the HH and the LL, the pure water circulation circuit. A method for operating a water electrolysis apparatus, characterized by performing control for continuing operation of water circulation and water supply of an external pure water supply line.

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