Water electrolysis device

Abstract

The present invention relates to a water electrolysis device including a diaphragm for removing dissolved gas in an electrolyte. By separating dissolved gas present in an electrolyte through a diaphragm provided in a gas-liquid separator or an electrolyte circulation line, it is possible to prevent the gas composition in a gas phase region of the water electrolysis device from reaching an explosion limit and to increase the production efficiency of the dissolved gas in the electrolyte.

Description

[Technical Field]

[0001] The present invention relates to a water electrolysis device including a diaphragm for removing dissolved gases in an electrolyte solution. [Background technology]

[0002] Water electrolysis, a representative hydrogen production technology, is a technology that directly produces hydrogen from water using electrical energy, and can produce high-purity hydrogen in an environmentally friendly manner. Water electrolysis technologies are classified into alkaline water electrolysis, polymer electrolyte water electrolysis, and solid oxide water electrolysis.

[0003] Among these water electrolysis technologies, alkaline water electrolysis has the advantage of being able to produce hydrogen inexpensively and in large quantities.An alkaline water electrolysis system consists of an electrolytic cell that produces hydrogen, a gas-liquid separator that separates the gaseous hydrogen or oxygen discharged from the electrolytic cell from the electrolyte, an electrolyte storage tank that stores the liquid phase discharged from the gas-liquid separator and reintroduces it into the electrolytic cell, and an operating device (Balance of Plant) that appropriately supplies the electrolyte and controls and manages power.

[0004] The electrolytic cell comprises an electrolyte, a separator, and electrodes, a positive electrode (anode) and a negative electrode (cathode), and the following reaction occurs at the positive electrode and the negative electrode:

[0005] Positive electrode: 2OH - →1 / 2O2+H2O+2e -

[0006] Negative electrode: 2H2O+2e - →H2+2OH -

[0007] The electrolyte solution containing dissolved oxygen gas produced by the reaction in the cathode chamber of the electrolytic cell is separated into oxygen gas and electrolyte through a cathode-side gas-liquid separator, and the electrolyte solution containing dissolved hydrogen gas produced by the reaction in the anode chamber of the electrolytic cell is separated into hydrogen gas and electrolyte through an anode-side gas-liquid separator.

[0008] However, the production of hydrogen using alkaline water electrolysis presents a problem of dissolved gas. Specifically, the electrolyte recovered from the cathode chamber of the electrolytic cell contains a portion of dissolved oxygen gas generated by the cathode reaction, and the electrolyte recovered from the anode chamber contains a portion of dissolved hydrogen gas generated by the anode reaction. Here, "oxygen gas" and "hydrogen gas" dissolved in the electrolyte encompass both the state in which oxygen gas and hydrogen gas are dissolved in the electrolyte and the state in which oxygen gas and hydrogen gas remain in the form of fine bubbles. Because the electrolyte recovered from the cathode chamber and the electrolyte recovered from the anode chamber are mixed in the electrolyte storage tank, both oxygen gas and hydrogen gas are dissolved in the electrolyte in the electrolyte storage tank. The oxygen gas and hydrogen gas dissolved in the electrolyte in the electrolyte storage tank are gradually released into the gas phase, gradually increasing the concentrations of oxygen gas and hydrogen gas in the upper gas phase of the electrolyte storage tank. Therefore, during continuous operation of the water electrolysis device, the gas composition in the upper gas phase of the electrolyte storage tank may reach an explosive limit.

[0009] Patent Document 1, which relates to a water electrolysis device that generates hydrogen gas, describes a water electrolysis device that includes a cathode chamber that accommodates a cathode and generates cathode gas, an anode chamber that accommodates an anode and generates hydrogen gas, a diaphragm that separates the cathode chamber from the anode chamber, and a cathode side circulation line that discharges an electrolyte from the cathode chamber and returns it to the cathode chamber, the cathode side circulation line connecting a cathode side gas-liquid separator that separates the cathode gas with the electrolyte, and a cathode side circulation line that connects the cathode chamber and the cathode side gas-liquid separator, and that discharges the electrolyte and the cathode gas from the cathode chamber and sends them to the cathode side gas-liquid separator. Patent Document 1 describes an electrolysis device comprising: a cathode-side discharge line; and a cathode-side supply line connecting the cathode chamber and the cathode-side gas-liquid separator, the cathode-side discharge line discharging the electrolyte from the cathode-side gas-liquid separator and delivering it to the cathode chamber; hydrogen gas dissolved in the electrolyte exists in a gas phase; a cathode gas delivery line connecting the cathode-side gas-liquid separator to a gas phase region where the hydrogen gas and cathode gas are mixed; the cathode gas delivery line delivering at least a portion of the cathode gas to the gas phase region; and the hydrogen gas concentration in the gas phase region being below the lower explosion limit. Patent Document 1 describes a water electrolysis device having the configuration described above that can eliminate the possibility of trace amounts of hydrogen gas gradually accumulating in the electrolyte circulation line and reaching the explosion limit of hydrogen.

[0010] However, Patent Document 1 describes that the gas discharged from the gas phase region of the electrolyte storage tank is released outside the system, and when the gas in the gas phase region of the electrolyte storage tank is purged using the positive electrode gas and then discharged, there is a problem that it is difficult to obtain a highly pure gas even if the discharged gas is recovered.

[0011] On the other hand, when the electrolyte recovered from the positive electrode chamber and the electrolyte recovered from the negative electrode chamber are stored in separate electrolyte storage tanks and circulated, there is a problem that a difference in concentration occurs between the positive electrode side electrolyte storage tank and the negative electrode side electrolyte storage tank due to the difference in the number of moles consumed in the positive electrode reaction and the negative electrode reaction.

[0012] If a connecting pipe is additionally installed between the liquid phase region of the positive electrode side electrolyte storage tank and the liquid phase region of the negative electrode side electrolyte storage tank in order to prevent a difference in liquid level between the positive electrode side electrolyte storage tank and the negative electrode side electrolyte storage tank, the electrolyte flowing in through the connecting pipe contains dissolved gas, and there is a risk that the gas composition in the gas phase region of the storage tank into which the electrolyte flows in through the connecting pipe will reach the explosion limit.

[0013] Therefore, there is a need for a water electrolysis device that can prevent the gas composition in the gas phase region of the electrolyte storage tank from reaching the explosion limit and solve the problem of reduced gas production efficiency due to dissolved gas in the electrolyte. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Japanese Patent Application Publication No. 2017-039982 Summary of the Invention [Problem to be solved by the invention]

[0015] The present invention provides a water electrolysis device that can prevent the gas composition in the gas phase region of the water electrolysis device from reaching the explosion limit and solves the problem of reduced gas production efficiency due to gas dissolved in the electrolyte. [Means for solving the problem]

[0016] The present invention provides a water electrolysis device comprising: an electrolytic cell including a positive electrode chamber and a negative electrode chamber separated by a partition wall; a positive electrode side gas-liquid separator in communication with the positive electrode chamber; an negative electrode side gas-liquid separator in communication with the negative electrode chamber; a positive electrode side circulation line that supplies electrolytic solution discharged from the positive electrode chamber to the positive electrode side gas-liquid separator and that supplies electrolytic solution discharged from the positive electrode side gas-liquid separator to the positive electrode chamber; an negative electrode side circulation line that supplies electrolytic solution discharged from the negative electrode chamber to the negative electrode side gas-liquid separator and that supplies electrolytic solution discharged from the negative electrode side gas-liquid separator to the negative electrode chamber; and a diaphragm having an internal flow path, which is provided in at least one of the positive electrode side gas-liquid separator, the negative electrode side gas-liquid separator, the positive electrode side circulation line, and the negative electrode side circulation line.

[0017] In one embodiment, the diaphragm may have a higher gas permeability than a liquid permeability along the direction of the internal flow path. Also, the diaphragm may be provided such that the gas permeability is higher than the liquid permeability along the direction of the internal flow path.

[0018] In one example, the membrane may be hydrophobic and configured to allow dissolved gases in the electrolyte discharged from the electrolytic cell to pass through to the internal flow passage.

[0019] In one embodiment, the membrane may be porous.

[0020] In one embodiment, the barrier membrane may include at least one material selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polysulfone, polyimide, polyacrylonitrile, polyamide, polyphenylene sulfide, polyethersulfone, and polyester.

[0021] In one embodiment, the membrane may be of the tubular type, hollow fiber type, flat plate type, or spiral wound type.

[0022] The diaphragm may be arranged in a coil shape wound along a predetermined direction.

[0023] In one embodiment, the pressure adjusting means may further be included to adjust the difference between the pressure in the internal passage of the diaphragm and the pressure in the external space of the diaphragm.

[0024] As an example, the pressure adjusting means may include a pressure reducing means for reducing the pressure in the internal flow path to generate a pressure difference.

[0025] The pressure adjusting means may cause the pressure in the space outside the diaphragm to be higher than the pressure in the internal flow passage of the diaphragm.

[0026] In one embodiment, the fuel cell further includes a fluid supply line communicating a gas phase region of at least one of the cathode side gas-liquid separator and the anode side gas-liquid separator with an internal flow path of the diaphragm, and gas present in the gas phase region of at least one of the cathode side gas-liquid separator and the anode side gas-liquid separator may be supplied to the internal flow path of the diaphragm through the fluid supply line.

[0027] In one embodiment, external air may be introduced into the internal flow passage of the membrane.

[0028] In one embodiment, the fuel cell further comprises a gas-liquid separation means communicating with the internal flow path of the diaphragm, and a liquid phase region of the gas-liquid separation means may communicate with at least one of the positive electrode side circulation line and the negative electrode side circulation line.

[0029] In one embodiment, the fuel cell may further include a gas supply line communicating the internal flow path of the diaphragm with a liquid phase region of at least one of the cathode-side gas-liquid separator and the anode-side gas-liquid separator, and gas present in the internal flow path of the diaphragm may be supplied to the liquid phase region of at least one of the cathode-side gas-liquid separator and the anode-side gas-liquid separator through the gas supply line. [Effects of the Invention]

[0030] The water electrolysis device of the present invention separates dissolved gases present in the electrolyte through a gas-liquid separator or a diaphragm provided in the electrolyte circulation line, thereby preventing the gas composition in the gas phase region of the water electrolysis device from reaching an explosion limit and increasing the efficiency of gas production through water electrolysis. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a configuration diagram of a water electrolysis device according to an embodiment of the present invention. [Figure 2] 1 is a configuration diagram of a water electrolysis device including an electrolyte storage tank according to an embodiment of the present invention. [Figure 3] 1 is a schematic diagram showing a cross section of a diaphragm according to an embodiment of the present invention. [Figure 4] 1 is a configuration diagram of a water electrolysis device including a fluid supply line according to an embodiment of the present invention. [Figure 5] 1 is a configuration diagram of a water electrolysis device including a gas-liquid separation means according to an embodiment of the present invention. [Figure 6] 1 is a configuration diagram of a water electrolysis device including a gas supply line according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] The present invention can be modified in various ways and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description.

[0033] However, it should be understood that this is not intended to limit the invention to any particular embodiment, but rather to include all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

[0034] In the present invention, the terms "comprise," "include," "comprise," or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0035] Therefore, the configurations illustrated in the embodiments described in this specification are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of ​​the present invention, and various equivalents and modifications that can replace them may exist at the time of this application.

[0036] Referring to FIG. 1 , a water electrolysis apparatus according to one embodiment of the present invention includes an electrolytic cell 100 including a cathode chamber 130 and an anode chamber 150 separated by a partition wall 110, a cathode-side gas-liquid separator 200 communicating with the cathode chamber 130, and an anode-side gas-liquid separator 300 communicating with the anode chamber 150.

[0037] The cathode gas-liquid separator 200 may include an upper gas phase region 201 and a lower liquid phase region 202. The anode gas-liquid separator 300 may include an upper gas phase region 301 and a lower liquid phase region 302.

[0038] The water electrolysis device also includes a cathode-side circulation line 400 that supplies the electrolyte discharged from the cathode chamber 130 through a cathode-side gas-liquid separator 200 and supplies the electrolyte discharged from the cathode-side gas-liquid separator 200 to the cathode chamber 130, and an anode-side circulation line 500 that supplies the electrolyte discharged from the anode chamber 150 to an anode-side gas-liquid separator 300 and supplies the electrolyte discharged from the anode-side gas-liquid separator 300 to the anode chamber 150.

[0039] The water electrolysis device further includes a diaphragm 600 provided in at least one of the cathode side gas-liquid separator 200, the anode side gas-liquid separator 300, the cathode side circulation line 400, and the anode side circulation line 500, and having an internal flow path 650 formed therein.

[0040] In this document, the water electrolysis device is a device that produces oxygen gas and hydrogen gas by electrolysis using an electrolyte.

[0041] The electrolytic cell 100 includes a positive electrode chamber 130 containing a positive electrode 140 for generating oxygen gas, and an negative electrode chamber 150 containing a negative electrode 160 for generating hydrogen gas. The positive electrode chamber 130 and the negative electrode chamber 150 are separated by a partition wall 110.

[0042] The partition wall 110 separates the positive electrode chamber 130 from the negative electrode chamber 150 and has gas barrier properties, and its shape and material are not particularly limited.

[0043] The partition wall 110 may be a plate having a predetermined thickness, and preferably has high electrolyte permeability, high ion permeability, and high gas barrier property. The material of the partition wall may include polymer resin fibers and inorganic compounds, and may be, for example, a porous polymer film.

[0044] The positive electrode chamber 130 and the negative electrode chamber 150 are each provided to have a space surrounded by a partition wall 110 and an outer frame 120, and the electrolyte flowing in from an electrolyte supply section passes through the space.

[0045] As shown in FIG. 2, the electrolyte supply unit may be the cathode gas-liquid separator 200 and the anode gas-liquid separator 300, and may include a separate electrolyte storage tank 700 in communication with the liquid phase regions of the cathode gas-liquid separator 200 and the anode gas-liquid separator 300.

[0046] The following reaction occurs at the positive electrode 140 in the positive electrode chamber 130 and the negative electrode 160 in the negative electrode chamber 150.

[0047] Positive electrode: 2OH - →1 / 2O2+H2O+2e -

[0048] Negative electrode: 2H2O+2e - →H2+2OH -

[0049] That is, in the positive electrode chamber 130, hydroxide ions (OH - ) is consumed to generate oxygen gas, and hydroxide ions (OH - ) is produced and hydrogen gas is generated.

[0050] The cathode gas-liquid separator 200 is connected to the cathode chamber 130 through the cathode recovery pipe 410 and separates the electrolyte and oxygen gas discharged from the cathode chamber 130 into gas and liquid. At this time, oxygen gas exists in a gas phase region formed in the upper part of the cathode gas-liquid separator 200, and electrolyte containing dissolved oxygen gas exists in a liquid phase region formed in the lower part.

[0051] The anode gas-liquid separator 300 is connected to the anode chamber 150 through the anode recovery pipe 510 and separates the electrolyte and hydrogen gas discharged from the anode chamber 150 into gas and liquid. At this time, hydrogen gas exists in a gas phase region 301 formed in the upper part of the anode gas-liquid separator 300, and electrolyte containing dissolved hydrogen gas exists in a liquid phase region 302 formed in the lower part.

[0052] In the present invention, the term "dissolved oxygen gas" and "dissolved hydrogen gas" refers to a concept that includes a state in which oxygen gas and hydrogen gas are dissolved in the electrolyte, and a state in which oxygen gas and hydrogen gas remain in the form of fine bubbles.

[0053] In this case, the positive electrode recovery pipe 410 and the negative electrode recovery pipe 510 may be connected to the upper portions of the positive electrode gas-liquid separator 200 and the negative electrode gas-liquid separator 300 .

[0054] When the cathode recovery pipe 410 and the anode recovery pipe 510 are connected to the top of the cathode-side gas-liquid separator 200 and the anode-side gas-liquid separator 300, respectively, the time it takes for the electrolyte containing dissolved gases discharged from the electrolytic cell to fall from inside the gas-liquid separator to the liquid surface increases, thereby increasing the gas-liquid separation efficiency.

[0055] The liquid phase region 202 of the cathode gas-liquid separator 200 is provided with a cathode electrolyte recovery pipe 420 that communicates with the cathode chamber 130 of the electrolytic cell 100 , and supplies the electrolyte to the cathode chamber 130 of the electrolytic cell 100 .

[0056] The liquid phase region 302 of the anode gas-liquid separator 300 is provided with an anode electrolyte recovery pipe 520 that communicates with the anode chamber 150 of the electrolytic cell 100 and supplies the electrolyte to the anode chamber 150 of the electrolytic cell 100 .

[0057] Therefore, the positive electrode side circulation line 400 includes a positive electrode recovery pipe 410 that supplies the electrolyte discharged from the positive electrode chamber 130 to the positive electrode side gas-liquid separator 200, and a positive electrode electrolyte recovery pipe 420 that supplies the electrolyte discharged from the positive electrode side gas-liquid separator 200 to the positive electrode chamber 130, and the negative electrode side circulation line 500 includes a negative electrode recovery pipe 510 that supplies the electrolyte discharged from the negative electrode chamber 150 to the negative electrode side gas-liquid separator 300, and a negative electrode electrolyte recovery pipe 520 that supplies the electrolyte discharged from the negative electrode side gas-liquid separator 300 to the negative electrode chamber 150.

[0058] Referring to FIG. 2 , the water electrolysis apparatus according to the present invention may further include an electrolyte storage tank 700 that is in communication with the liquid phase regions 202, 302 of the cathode-side gas-liquid separator 200 and the anode-side gas-liquid separator 300 via a second cathode electrolyte recovery pipe 421 and a second anode electrolyte recovery pipe 521, respectively, and that is in communication with the cathode chamber 130 and the anode chamber 150 of the electrolytic cell 100.

[0059] When the electrolytic cell 100 further includes an electrolyte storage tank 700, the electrolytes present in the liquid phase regions 202, 302 of the cathode-side gas-liquid separator 200 and the anode-side gas-liquid separator 300 may be mixed in the electrolyte storage tank 700 and then supplied to the cathode chamber 130 and the anode chamber 150 of the electrolytic cell 100.

[0060] In this case, the electrolyte storage tank 700 may include an electrolyte supply pipe 430 for supplying the electrolyte to the positive electrode chamber 130 and the negative electrode chamber 150 of the electrolytic cell 100, and the electrolyte supply pipe 430 may branch into a positive electrode electrolyte supply pipe 440 communicating with the positive electrode chamber and a negative electrode electrolyte supply pipe 540 communicating with the negative electrode chamber, respectively.

[0061] In this case, the electrolyte supply pipe 430 may be provided with a circulation pump 800 for supplying the electrolyte to the electrolytic cell, and the circulation pump 800 may be provided in each of the cathode electrolyte supply pipe 440 and the anode electrolyte supply pipe 540. Alternatively, the circulation pump 800 may be installed at the rear end of each electrolytic cell.

[0062] Therefore, when the water electrolysis apparatus according to an embodiment of the present invention further includes the electrolyte storage tank 700, the cathode side circulation line 400 includes a cathode recovery pipe 410 that supplies the electrolyte discharged from the cathode chamber 130 to the cathode side gas-liquid separator 200, a second cathode electrolyte recovery pipe 421 that supplies the electrolyte discharged from the cathode side gas-liquid separator 200 to the electrolyte storage tank 700, and an electrolyte supply pipe 430 and a cathode electrolyte supply pipe 440 that supply the electrolyte from the electrolyte storage tank 700 to the cathode chamber 130. In addition, the anode-side circulation line 500 includes an anode recovery pipe 510 that supplies the electrolyte discharged from the anode chamber 150 to the anode-side gas-liquid separator 300, a second anode electrolyte recovery pipe 521 that supplies the electrolyte discharged from the anode-side gas-liquid separator 300 to the electrolyte storage tank 700, and an electrolyte supply pipe 430 and an anode electrolyte supply pipe 540 that supply the electrolyte from the electrolyte storage tank 700 to the anode chamber 150.

[0063] The water electrolysis apparatus according to one embodiment of the present invention includes a diaphragm 600 having an internal flow path 650 and provided in at least one of the cathode side gas-liquid separator 200, the anode side gas-liquid separator 300, the cathode side circulation line 400, and the anode side circulation line 500.

[0064] The membrane 600 may be configured to have different liquid and gas permeabilities along the direction of the internal flow passage 650. For example, the membrane may include pores, and the permeability of liquid and gas may be varied by adjusting the size of the pores. Alternatively, the permeability of liquid and gas may be varied by adjusting the size of the polymer resin fibers or inorganic particles.

[0065] Specifically, the membrane 600 may have a higher gas permeability than a liquid permeability.

[0066] The membrane 600 having the above properties can be achieved by adjusting the pore diameter, surface area, hydrophilicity, and pore formation structure. For example, a polymer porous membrane, an inorganic porous membrane, a woven fabric, or a nonwoven fabric can be used.

[0067] The diaphragm 600 is hydrophobic and may be configured to allow dissolved gases in the electrolyte discharged from the electrolytic cell to pass through to the internal flow channel 650. That is, the diaphragm 600 is hydrophobic, which makes it difficult for the electrolyte to pass through, but has an affinity for the dissolved gases, which allows only the dissolved gases in the electrolyte to selectively pass through.

[0068] Referring to FIG. 3 , the type of electrolyte is not limited. For example, when the electrolyte is KOH, the KOH solution cannot permeate the diaphragm 600, but oxygen and / or hydrogen gas dissolved in the electrolyte can permeate the diaphragm 600.

[0069] The diaphragm 600 may be a porous membrane. The diaphragm 600 has porosity, allowing only dissolved gas in the electrolyte to selectively pass through. The pores of the diaphragm 600 may be 1 nm to 10 μm.

[0070] The thickness of the diaphragm 600 is not particularly limited, and may be, for example, 0.1 mm to 10 mm. The permeation rate and separation ability can be adjusted by adjusting the pore size and thickness of the diaphragm 600. Specifically, the permeation rate and separation ability of the diaphragm vary depending on the pressure outside the diaphragm, i.e., the electrolyte pressure, the pore size, pore distribution, pore thickness, and the material properties of the diaphragm. Therefore, by adjusting the operating pressure of the water electrolysis device, the pore size, thickness, and material properties of the diaphragm, it is possible to selectively allow only the dissolved gas in the electrolyte to permeate the internal flow path of the diaphragm.

[0071] The material of the diaphragm 600 is preferably hydrophobic and has excellent heat resistance and durability. For example, the diaphragm may be made of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polysulfone, polyimide, polyacrylonitrile, polyamide, polyphenylene sulfide, polyethersulfone, etc. The material may include at least one material selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyphenylene sulfide, polyethersulfone, and polyester. Specifically, the material may include at least one material selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyphenylene sulfide, polyethersulfone, and polyester.

[0072] The membrane 600 may be in the form of a tube, a hollow fiber, a flat plate, or a spiral wound.

[0073] The tubular mold may have one tube or a bundle of tubes, and the shape of the outer frame is not particularly limited, but may be cylindrical when considering the filling rate taking into account the shape of the inner tube.

[0074] When the tubular mold has a tube bundle, the bundle of multiple tubes can be assembled in the mold. When the diaphragm is tubular, the internal flow passage of the diaphragm can be the interior of the tube or the space between the tubes, which can be selected depending on the amount and pressure of the electrolyte.

[0075] The hollow fiber type may be a composite membrane or a single membrane, and in the case of a composite membrane, it may include a hollow support that can support the membrane and an outer membrane layer. The hollow fiber type may be a composite membrane or a single membrane in the form of a bundle of hundreds to thousands of hollow fibers.

[0076] When the diaphragm is a hollow fiber type, the internal flow path of the diaphragm can be the inside or the space between hollow fibers depending on whether it is an internal pressure type or an external pressure type, and this can be selected depending on the amount and pressure of the electrolyte.

[0077] The flat membrane can be inserted between supports on both sides that act as channels for liquid flow. The membrane is arranged in a flat shape, and the membrane and supports can be stacked as needed to increase the membrane area.

[0078] The spiral-wound type has an envelope-like shape with an inlet on one side, and has a channel between the flat membranes through which the electrolyte can flow, and there may be spaces between the membranes to form internal channels, or internal channels may be formed between the flat membranes as needed to allow the electrolyte to pass through the spaces between the membranes.

[0079] The diaphragm 600 has the above-described shape and includes an internal flow path 650. The opposing surface (outer periphery) of the diaphragm 600 contacts the electrolyte, and dissolved gas in the electrolyte can permeate the diaphragm 600 and be accommodated in the internal flow path 650.

[0080] For example, the diaphragm 600 may be arranged in a coil shape wound in a predetermined direction.

[0081] With the above structure, the area in contact with the electrolyte can be increased, thereby improving the efficiency of separating gases dissolved in the electrolyte.

[0082] Also, the barrier membrane 600 may be provided in a plurality of pieces, and in such a structure, the barrier membranes may be stacked and arranged in a predetermined direction.

[0083] In order to facilitate understanding of the present invention, the diaphragm 600 is illustrated in a coil shape wound in a predetermined direction in FIGS. 1, 2, and 4 to 6. However, the diaphragm may be a tubular type, hollow fiber type, flat type, or spiral type, and the external shape of the diaphragm is not limited thereto.

[0084] In addition, in one embodiment of the present invention, the diaphragm 600 is located inside the gas-liquid separator in FIGS. 1, 2, and 4 to 6, but the location of the diaphragm is not limited thereto. The diaphragm may be located in any of the cathode-side gas-liquid separator 200, the anode-side gas-liquid separator 300, the cathode-side circulation line 400, and the anode-side circulation line 500, and a single or multiple diaphragms may be installed at the corresponding locations.

[0085] 3, gas separation through the diaphragm 600 may occur due to a pressure difference between the internal flow path of the diaphragm and the external space of the diaphragm. Specifically, since a water electrolysis apparatus is operated under a predetermined pressure, the pressure P in the external space of the diaphragm 600 is maintained higher than the pressure P' in the internal flow path of the diaphragm, which may cause gas separation through the diaphragm.

[0086] The water electrolysis device may further include a means for increasing the operating pressure of the water electrolysis device to increase the pressure difference between the external space and the internal flow path. The means for increasing the pressure difference may be a pump or a valve.

[0087] In addition, the water electrolysis apparatus may further include a pressure adjusting means for adjusting the pressure difference between the internal flow path of the diaphragm and the external space of the diaphragm in order to improve and adjust the gas separation performance of the diaphragm.

[0088] The pressure control means may include a pressure reducing means for reducing the pressure in the internal flow path to improve separation performance based on the pressure difference. Specifically, to increase the permeation rate and separation efficiency of the membrane, it is preferable that the pressure P' in the internal flow path of the membrane be adjusted to be lower than the pressure P in the external space of the membrane. The pressure reducing means may be a vacuum pump or an orifice. The pressure reducing means may be located at at least one of both ends of the internal flow path of the membrane. By providing the pressure reducing means, the pressure in the internal flow path of the membrane can be maintained lower than that of the outer surface of the membrane that contacts the electrolyte, thereby improving the separation performance and permeation rate of dissolved gases in the electrolyte.

[0089] The water electrolysis device according to an embodiment of the present invention includes a diaphragm having an internal flow path formed therein, thereby separating dissolved gases present in an electrolyte. This prevents the dissolved gases present in the electrolyte from mixing with each other, thereby preventing a potential risk of explosion due to an increase in the concentration of hydrogen gas or oxygen gas beyond the explosive range.

[0090] Meanwhile, referring to FIG. 4 , a water electrolysis apparatus according to an embodiment of the present invention further includes a fluid supply line 220 for connecting the gas phase region 201, 301 of at least one of the cathode side gas-liquid separator 200 and the anode side gas-liquid separator 300 with an internal flow path 650 of the diaphragm 600. In this case, gas present in the gas phase region 201, 301 of at least one of the cathode side gas-liquid separator 200 and the anode side gas-liquid separator 300 may be supplied to the internal flow path of the diaphragm through the fluid supply line 220.

[0091] That is, oxygen gas is present in the gas phase region 201 of the cathode side gas-liquid separator 200, and the oxygen gas is supplied to the internal flow path of the diaphragm 600 through the cathode side fluid supply line 221 connected to the internal flow path 650 of the diaphragm 600. The oxygen gas passes through the internal flow path 650, thereby increasing the separation efficiency of the diaphragm 600. The oxygen gas supplied from the gas phase region 201 of the cathode side gas-liquid separator 200 and passing through the internal flow path 650 of the diaphragm 600 and the dissolved oxygen gas in the electrolyte that permeates the diaphragm 600 are mixed together in the internal flow path of the diaphragm and are then released to the outside of the system.

[0092] Furthermore, hydrogen gas is present in the gas phase region 301 of the anode-side gas-liquid separator 300. The hydrogen gas is supplied to the internal flow path 650 of the diaphragm 600 through the anode-side fluid supply line 321 connected to the internal flow path 650 of the diaphragm 600. As the hydrogen gas passes through the internal flow path 650, the separation efficiency of the diaphragm 600 increases, and thus the amount of hydrogen gas produced can increase. The hydrogen gas supplied from the gas phase region 301 of the anode-side gas-liquid separator 300 and passing through the internal flow path 650 of the diaphragm 600 and the dissolved hydrogen gas in the electrolyte that has permeated the diaphragm can be mixed together in the internal flow path 650 of the diaphragm 600 and released to the outside of the system.

[0093] As shown in Fig. 4, the gases in the gas phase regions 201 and 301 of the cathode gas-liquid separator 200 and the anode gas-liquid separator 300 are supplied to the internal passage 650 of the diaphragm 600. Alternatively, as shown in Fig. 5, external air may be introduced into the internal passage 650 of the diaphragm 600. When external air is introduced into the internal passage of the diaphragm as described above, no additional connection with the internal device is required, simplifying the device configuration. Furthermore, the introduction of external air allows the gas concentration to be adjusted within the gas explosion range, thereby improving safety against gas explosions.

[0094] Referring to FIG. 5 , a gas-liquid separator 900 may be provided in communication with the internal flow path 650 of the diaphragm 600 before the gas present in the internal flow path 650 of the diaphragm 600 is released to the outside of the system, and a liquid phase region of the gas-liquid separator 900 may be connected to at least one of the positive electrode side circulation line 400, the negative electrode side circulation line 500, the positive electrode side gas-liquid separator 200, the negative electrode side gas-liquid separator 300, and the electrolyte storage tank 700.

[0095] In one embodiment, when a means for introducing gas present in the gas phase regions 201, 301 of the cathode-side gas-liquid separator 200 or the anode-side gas-liquid separator 300 and external air into the internal flow path 650 of the diaphragm 600 is provided, the internal flow path 650 is mostly occupied by external air and gas dissolved in the electrolyte that has permeated the diaphragm, but a small amount of electrolyte that contacts the outer surface of the diaphragm 600 may also be present. In addition, the gas phase regions 201, 301 of the cathode-side gas-liquid separator 200 or the anode-side gas-liquid separator 300 may contain a portion of the electrolyte as fumes or the like. Therefore, a portion of the electrolyte may still be present in the internal flow path of the diaphragm.

[0096] When the gas-liquid separation means 900 communicating with the internal flow path 650 of the diaphragm 600 is provided, a portion of the remaining electrolyte components present in the internal flow path 650 of the diaphragm 600 can be separated into a liquid phase. The electrolyte separated by the gas-liquid separation means 900 can be recycled by communicating with at least one of the positive electrode side circulation line 400 and the negative electrode side circulation line 500.

[0097] 6, a water electrolysis apparatus according to an embodiment of the present invention may further include a gas supply line 230 for connecting the internal flow path 650 of the diaphragm 600 with at least one liquid phase region 202, 302 of the cathode-side gas-liquid separator 200 and the anode-side gas-liquid separator 300. With this structure, gas present in the internal flow path 650 of the diaphragm 600 may be supplied to at least one liquid phase region 202, 302 of the cathode-side gas-liquid separator 200 and the anode-side gas-liquid separator 300 through the gas supply line 230. In this case, the gas supply line 230 connected to the internal flow path 650 of the diaphragm may be branched, with one end connected to at least one liquid phase region 202, 302 of the cathode-side gas-liquid separator 200 and the anode-side gas-liquid separator 300 and the other end configured to discharge a portion of the gas present in the internal flow path 650 of the diaphragm to the outside of the system. That is, by resupplying the gas in the internal flow path 650 of the membrane 600, in whole or in part, to the liquid phase regions of the cathode-side gas-liquid separator 200 and the anode-side gas-liquid separator 300 through the gas supply line 230, respectively, fine bubbles are enlarged and generated in the liquid phase regions of the gas-liquid separators, thereby further increasing the gas-liquid separation efficiency.

[0098] The water electrolysis apparatus according to an embodiment of the present invention includes the diaphragm 600, the fluid supply line 220, the gas supply line 230, and the gas-liquid separation means 900, thereby improving the purity of oxygen and hydrogen gas produced in the water electrolysis apparatus and improving the production efficiency of oxygen and hydrogen gas in the water electrolysis apparatus. [Industrial Applicability]

[0099] The water electrolysis device of the present invention separates dissolved gases present in the electrolyte through a gas-liquid separator or a diaphragm provided in the electrolyte circulation line, thereby preventing the gas composition in the gas phase region of the water electrolysis device from reaching an explosion limit and increasing the efficiency of gas production through water electrolysis.

Claims

1. an electrolytic cell including a positive electrode chamber and a negative electrode chamber separated by a partition; a positive electrode-side gas-liquid separator communicating with the positive electrode chamber; an anode-side gas-liquid separator communicating with the anode chamber; a positive electrode side circulation line that supplies the electrolytic solution discharged from the positive electrode chamber to a positive electrode side gas-liquid separator and supplies the electrolytic solution discharged from the positive electrode side gas-liquid separator to the positive electrode chamber; an anode-side circulation line that supplies the electrolytic solution discharged from the anode chamber to an anode-side gas-liquid separator and supplies the electrolytic solution discharged from the anode-side gas-liquid separator to the anode chamber; and a diaphragm having an internal flow path, the diaphragm being provided in each of the positive electrode side gas-liquid separator and the negative electrode side gas-liquid separator; the positive electrode gas-liquid separator includes a gas phase region disposed in an upper portion and a liquid phase region disposed in a lower portion, the negative electrode gas-liquid separator includes a gas phase region disposed in an upper portion and a liquid phase region disposed in a lower portion, the positive electrode circulation line includes a positive electrode recovery pipe configured to communicate with an upper portion of the positive electrode gas-liquid separator, and a positive electrode electrolyte recovery pipe configured to communicate with a liquid phase region of the positive electrode gas-liquid separator; and the anode-side circulation line includes: an anode recovery pipe configured to communicate with an upper portion of the anode-side gas-liquid separator to supply the electrolytic solution discharged from the anode chamber to the anode-side gas-liquid separator; and an anode electrolyte recovery pipe configured to communicate with a liquid phase region of the anode-side gas-liquid separator, the diaphragm is disposed in the liquid phase region of the positive electrode side gas-liquid separator and the liquid phase region of the negative electrode side gas-liquid separator, respectively.

2. The water electrolysis apparatus according to claim 1 , wherein the diaphragm has a gas permeability greater than a liquid permeability along the direction of the internal flow passage.

3. 2. The water electrolysis apparatus according to claim 1, wherein the diaphragm is hydrophobic and is provided so as to allow dissolved gases in the electrolytic solution discharged from the electrolytic cell to pass through the internal flow path.

4. The water electrolysis apparatus according to claim 1 , wherein the diaphragm is porous.

5. 2. The water electrolysis apparatus of claim 1, wherein the diaphragm comprises at least one material selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polysulfone, polyimide, polyacrylonitrile, polyamide, polyphenylene sulfide, polyethersulfone, and polyester.

6. 2. The water electrolysis apparatus according to claim 1, wherein the diaphragm is of a tubular type, a hollow fiber type, a flat plate type, or a spiral wound type.

7. 7. The water electrolysis apparatus according to claim 6, wherein the diaphragms are arranged in the form of a coil wound in a predetermined direction.

8. 2. The water electrolysis apparatus according to claim 1, further comprising a pressure adjusting means for adjusting the difference between the pressure in the internal flow passage of the diaphragm and the pressure in the external space of the diaphragm.

9. 9. The water electrolysis apparatus according to claim 8, wherein the pressure adjusting means includes a pressure reducing means for reducing the pressure in the internal flow path to generate a pressure difference.

10. 9. The water electrolysis apparatus according to claim 8, wherein the pressure adjusting means adjusts the pressure in the external space of the diaphragm to be higher than the pressure in the internal flow path of the diaphragm.

11. 2. The water electrolysis apparatus of claim 1, further comprising a fluid supply line communicating a gas phase region of at least one of the cathode side gas-liquid separator and the anode side gas-liquid separator with an internal flow path of the diaphragm, wherein gas present in the gas phase region of at least one of the cathode side gas-liquid separator and the anode side gas-liquid separator is supplied to the internal flow path of the diaphragm through the fluid supply line.

12. The water electrolysis apparatus according to claim 1 , wherein external air flows into the internal flow passage of the diaphragm.

13. a gas-liquid separation means communicating with the internal flow path of the diaphragm; 2. The water electrolysis apparatus according to claim 1, wherein a liquid phase region of the gas-liquid separation means is in communication with at least one of the positive electrode side circulation line and the negative electrode side circulation line.

14. The cathode gas-liquid separator further includes a gas supply line for communicating the internal flow path of the diaphragm with at least one liquid phase region of the cathode gas-liquid separator and the anode gas-liquid separator; 2. The water electrolysis apparatus according to claim 1, wherein the gas present in the internal flow channel of the diaphragm is supplied to a liquid phase region of at least one of the positive electrode side gas-liquid separator and the negative electrode side gas-liquid separator through the gas supply line.

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