Water electrolysis device and method for controlling the same

Abstract

The present disclosure relates to a water electrolysis device and a control method thereof. The water electrolysis device comprises: a water electrolysis stack; a feed water conduit; and a transport layer arranged upstream of the stack. A processor includes pressure measured on each side of the transport layer and monitors the ionic conductivity of the feed water. When either reading crosses a preset reference threshold, the processor disables the power supply unit and / or stops the circulation pump to protect the stack. When the transport layer or the electrolyte membrane needs to be replaced, or when the pressure of carbon dioxide drops below the feed water pressure, the system can inject carbon dioxide to restore the conductivity and issue an alert. A supplementary control method performs sensing, comparison, intervention and user notification steps.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2024-0184233, filed with the Korean Intellectual Property Office on December 11, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a water electrolysis device and its control method. Background Technology

[0004] Water electrolysis devices using polymer electrolyte membranes (PEMs) (hereinafter referred to as "internal electrolyte membranes") split water into hydrogen and oxygen through an electrochemical reaction and are considered a next-generation technology for producing clean hydrogen due to their advantages, such as rapid hydrogen production rates, high purity of the produced hydrogen, and flexible operability.

[0005] Furthermore, when the electricity supplied to the water electrolysis unit for the electrochemical reaction is replaced with environmentally friendly renewable energy, the surplus electricity can be converted into hydrogen without emitting environmental pollutants.

[0006] Typically, the internal electrolyte membrane comprises a water electrolyzer assembled by stacking multiple cell units to achieve the desired hydrogen production capacity.

[0007] The electrochemical reaction in the water electrolysis device occurs in a membrane electrode assembly comprising an electrolyte membrane based on perfluorinated sulfonic acid ionomers and an anode / cathode electrode. After the water supplied to the anode is decomposed into oxygen, hydrogen ions, and electrons, the hydrogen ions move toward the cathode, which serves as a reduction electrode, through the internal electrolyte membrane, and the electrons move to the cathode through an external circuit and a supply source, causing the hydrogen ions and electrons to react with each other in the cathode to produce hydrogen gas.

[0008] Meanwhile, the purity of the feed water is likely important for the stable production of hydrogen in a water electrolysis unit. This is because when feed water with low purity is introduced into the water electrolysis reactor, the hydrogen production in the reactor may decrease and the lifespan of the water electrolysis unit may be shortened. Impurities affecting feed water purity can be classified as cations, anions, and organic substances, and when impurities flow into the water electrolysis reactor, the electrodes and internal electrolyte membrane deteriorate, increasing the need for water electrolysis units that can manage feed water purity. Summary of the Invention

[0009] This disclosure has been made to address the aforementioned problems in the prior art while maintaining the advantages achieved by the prior art.

[0010] Some embodiments of this disclosure provide a water electrolysis apparatus that can manage the purity of the feed water.

[0011] The technical problems to be solved by this disclosure are not limited to those described above, and any other technical problems not mentioned herein will be clearly understood by those skilled in the art from the following description.

[0012] According to some embodiments of this disclosure, a water electrolysis apparatus includes: a water electrolysis reactor; a supply conduit configured to deliver feed water to the water electrolysis reactor; and a transport layer disposed on the supply conduit, located upstream of the water electrolysis reactor. In various aspects, as disclosed herein, the transport layer may suitably be porous.

[0013] The water electrolysis apparatus may further include: a power supply unit configured to supply power to the water electrolysis reactor; and a processor operatively coupled to the power supply unit, which can control the power supply unit to stop supplying power to the water electrolysis reactor when the concentration of impurities precipitated by the transport layer is greater than or equal to a reference concentration.

[0014] The water electrolysis device may further include: a first pressure gauge disposed on the supply pipeline and located upstream of the transport layer; and a second pressure gauge disposed on the supply pipeline and located between the transport layer and the water electrolysis stack, and the processor may determine that the concentration of impurities has reached the reference concentration when the difference between the first pressure sensed by the first pressure gauge and the second pressure sensed by the second pressure gauge is greater than or equal to the reference pressure difference.

[0015] The water electrolysis apparatus may also include: a circulation pump configured to pump feed water flowing through a supply line, and the circulation pump is operatively coupled to a processor, and the processor may stop the circulation pump when the difference between a first pressure and a second pressure is greater than or equal to a reference pressure difference.

[0016] The reference pressure difference can be approximately 1.1 times the initial pressure difference between the first and second pressure gauges.

[0017] The water electrolysis apparatus may also include an ionic conductivity sensor located between the transport layer and the water electrolysis stack, and the ionic conductivity sensor is configured to sense the ionic conductivity of the feed water.

[0018] The processor is operatively coupled to the ionic conductivity sensor and controls the power supply unit to stop supplying power to the water electrolysis reactor when the value of the ionic conductivity sensed by the ionic conductivity sensor is less than or equal to the first reference ionic conductivity.

[0019] The value of the first reference ionic conductivity can be approximately 0.95 times the initial value of the ionic conductivity.

[0020] An ionic conductivity sensor may include: an electrolyte membrane in contact with feed water; a current source configured to apply current to the electrolyte membrane; and a voltage sensor connected to two points on the electrolyte membrane to sense the voltage between the two points.

[0021] The current source can apply an alternating current to the electrolyte membrane and sense the ionic conductivity of the feed water by: calculating the ionic conductivity based on the AC resistance value caused by the alternating current applied to the electrolyte membrane, sensed by the ionic conductivity sensor. The ionic conductivity can be calculated as: the distance between two points divided by the product of the converted resistance value and the area of ​​the electrolyte membrane. The converted resistance value corresponds to the real part of the value obtained by converting the AC resistance value through a Nyquist plot. The area of ​​the electrolyte membrane is defined by the lengths in two mutually perpendicular directions within a plane perpendicular to the direction connecting the two points.

[0022] A water electrolysis reactor may include an internal electrolyte membrane disposed inside the water electrolysis reactor, and the thickness of the electrolyte membrane may be less than the thickness of the internal electrolyte membrane.

[0023] The water electrolysis reactor may include a stack transport layer disposed inside the water electrolysis reactor, and the stack transport layer is configured to precipitate impurities contained in the feed water introduced into the water electrolysis reactor, and i) the pore size of the transport layer may be less than or equal to the pore size of the stack transport layer, ii) the porosity of the transport layer may be less than or equal to the porosity of the stack transport layer, or iii) the transport layer may be configured to include two transport sublayers corresponding to the stack transport layer.

[0024] The water electrolysis apparatus may further include: a supply tank connected to a point on the supply pipeline between the ion conductivity sensor and the water electrolysis stack, and the supply tank contains carbon dioxide to be supplied to the feed water; an ejector disposed on the supply pipeline and configured to pump carbon dioxide together with the feed water to the water electrolysis stack; and an on / off valve disposed between the ejector and the supply tank.

[0025] The on / off valve can be operatively coupled to the processor, and the processor can control the on / off valve to supply carbon dioxide from the supply tank to the feed water when the value of the ionic conductivity sensed by the ionic conductivity sensor is equal to or less than the second reference ionic conductivity.

[0026] The value of the second reference ionic conductivity can be greater than the value of the first reference ionic conductivity.

[0027] According to some embodiments of this disclosure, a control method for a water electrolysis device includes: supplying feed water to a water electrolysis reactor such that the feed water passes through a transport layer disposed on the upstream side of the water electrolysis reactor; calculating a pressure difference between a first pressure of the feed water sensed by a first pressure gauge disposed on the upstream side of the transport layer and a second pressure of the feed water sensed by a second pressure gauge disposed between the transport layer and the water electrolysis reactor; and stopping the supply of electricity to the water electrolysis reactor or stopping the supply of feed water to the water electrolysis reactor when the pressure difference is greater than or equal to a reference pressure difference.

[0028] The method may further include: using an ionic conductivity sensor disposed between the second pressure gauge and the water electrolyzer to sense the ionic conductivity of the feed water; and stopping the supply of power to the water electrolyzer or stopping the supply of feed water to the water electrolyzer when the sensed ionic conductivity is equal to or less than the first ionic conductivity.

[0029] The method may further include: notifying the user to replace the transport layer when the pressure difference is greater than or equal to a reference pressure difference; and notifying the user to replace the electrolyte membrane contained in the ionic conductivity sensor when the ionic conductivity sensed during the ionic conductivity sensing period is equal to or less than a first ionic conductivity.

[0030] The method may further include supplying carbon dioxide to the feed water when the ionic conductivity sensed during the sensing period is equal to or less than a specific second ionic conductivity.

[0031] The method may further include: notifying the user to fill with carbon dioxide when the pressure of the carbon dioxide supplied to the feed water is less than the pressure of the feed water during carbon dioxide supply. Attached Figure Description

[0032] The above and other objects, features, and advantages of this disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings:

[0033] Figure 1 This is a schematic diagram of a water electrolysis apparatus according to some embodiments of the present disclosure;

[0034] Figure 2 This is a schematic diagram of an ionic conductivity sensor according to some embodiments of the present disclosure;

[0035] Figure 3 This is a schematic diagram of a supply tank, ejector, on / off valve, and water electrolysis reactor according to some embodiments of this disclosure;

[0036] Figure 4 This is a schematic diagram of a water electrolysis apparatus according to some embodiments of the present disclosure;

[0037] Figure 5This is a flowchart illustrating a control method according to some embodiments of the present disclosure, which compares upstream and downstream pressures, then assesses ionic conductivity to selectively stop the flow of power or feed water to the electrolyzer, and issues an alarm for transport layer or electrolyte membrane replacement; and

[0038] Figure 6 This is a flowchart illustrating subsequent steps according to some embodiments of the present disclosure, in which carbon dioxide is injected into the feed water when the ionic conductivity drops below a second threshold, and a refill notification is generated when the CO2 supply pressure drops below the feed water pressure. Detailed Implementation

[0039] In the following, some embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. When adding reference numerals to components in the drawings, it should be noted that even if the same components are shown in different drawings, they will have as many numerals as possible. Furthermore, in describing embodiments of the present disclosure, detailed descriptions associated with well-known functions or configurations will be omitted if they might unnecessarily obscure the subject matter of the disclosure.

[0040] In describing the components of embodiments of this disclosure, the terms first, second, A, B, (a), (b), etc., may be used herein. These terms are used only to distinguish one element from another and do not limit the corresponding element, regardless of the nature, order, or priority of the corresponding element. Furthermore, unless otherwise defined, all terms used herein, including technical and scientific terms, shall be interpreted as conventional terms in the art to which this disclosure pertains. Terms as defined in commonly used dictionaries shall be interpreted as having meanings equivalent to those in the context of the relevant art and shall not be interpreted as having ideal or overly formal meanings unless explicitly defined as having such meanings in this application.

[0041] The term "feed water" in this paper refers to the purified or pretreated water stream introduced into the water electrolyzer for the electrochemical decomposition of H2O into hydrogen and oxygen.

[0042] The term "transport layer" in this document refers to a gas and liquid permeable conductive substrate located in a supply conduit. The term "transport layer" can be formed as porous. The term "transport layer" can also be understood as a porous transport layer located in a supply conduit.

[0043] The term "reactor transport layer" in this paper refers to a porous transport layer structurally integrated within a water electrolyzer. Here, the term "reactor transport layer" refers to a porous transport layer used in a water electrolyzer, which can be assembled within the water electrolyzer.

[0044] In the following text, reference will be made to Figures 1 to 6 Various embodiments of this disclosure are described in detail.

[0045] Figure 1 This is a schematic diagram of a water electrolysis apparatus according to some embodiments of the present disclosure. Figure 2 This is a schematic diagram of an ionic conductivity sensor according to some embodiments of the present disclosure. Figure 3 This is a schematic diagram of a supply tank, injector, on / off valve, and water electrolysis reactor according to some embodiments of this disclosure.

[0046] refer to Figures 1 to 3 The water electrolysis device 100 can be a device that decomposes water into hydrogen and oxygen through an electrochemical reaction using a polymer electrolyte membrane (PEM) (hereinafter referred to as the "internal electrolyte membrane").

[0047] The water electrolysis device 100 may include a water electrolysis stack 110 assembled by stacking multiple cell units using an internal electrolyte membrane, and a supply pipe 101 for introducing feed water into the water electrolysis stack 110. Furthermore, the water electrolysis device 100 may include a power supply unit 120 for supplying power to the water electrolysis stack 110.

[0048] The water electrolysis stack 110 may include a membrane electrode assembly (MEA), an internal electrolyte membrane for moving hydrogen ions to the membrane electrode assembly (MEA), and an anode and a cathode respectively disposed on opposite side surfaces of the internal electrolyte membrane.

[0049] A stack transport layer (not shown) (separate from the transport layer 420 located within the supply pipe 101 and disposed as a porous transport layer (PTL) within the water electrolysis stack 110), a gas diffusion layer (GDL), and gaskets can be stacked in the outer region of the membrane electrode assembly, with the anode and cathode located within the membrane electrode assembly, and channels or separators (through which products generated by the reaction between reactants and cooling water pass) can be combined with the outer regions of the stack transport layer and the gas diffusion layer.

[0050] When feed water is supplied to the water electrolysis unit of the water electrolysis reactor 110, the feed water supplied to the anode can be decomposed into oxygen, hydrogen ions, and electrons, and then the hydrogen ions and electrons can move to the cathode. Therefore, the hydrogen ions and electrons can react with each other at the cathode to produce hydrogen gas. For this reaction, iridium-based (Ir) or ruthenium-based (Ru) catalysts can be used for the anode, and platinum-containing (Pt) catalysts can be used for the cathode. However, the type of catalyst is not limited to these.

[0051] Based on the above principle, the feed water flowing through the supply pipe 101 is introduced into the water electrolysis reactor 110, and hydrogen and oxygen are generated simultaneously. For this purpose, the water electrolysis device 100 may include a first (1-1) discharge pipe 201 and a second (2-1) discharge pipe 301 respectively connected to the water electrolysis reactor 110.

[0052] The water electrolysis device 100 may include a water tank 200 connected to a first (1-1) discharge pipe 201, and a first (1-2) discharge pipe 202 and a supply pipe 101 respectively connected to the water tank 200.

[0053] The discharge sensor 210 can be installed on the (1-1) discharge pipe 201. The discharge sensor 210 can be a component used to determine whether ionic impurities are generated in the water electrolysis reactor 110 by measuring the ionic conductivity of the discharged water flowing through the (1-1) discharge pipe 201.

[0054] The discharge water flowing through the (1-1) discharge pipe 201 and the feed water introduced by the feed water pump 250 can be contained in the water tank 200. A tank sensor 220 can be installed in the water tank 200. The tank sensor 220 can be a component for measuring the ionic conductivity of the discharge water and feed water contained in the water tank 200.

[0055] The (1-2) discharge pipe 202 can be connected to the water tank 200 to allow the oxygen contained in the water tank 200 to flow. A first discharge filter 230 and a first discharge valve 240 can be provided on the (1-2) discharge pipe 202, and when the first discharge valve 240 opens the (1-2) discharge pipe 202, the oxygen flowing through the (1-2) discharge pipe 202 can be filtered by the first discharge filter 230 and then discharged to the outside.

[0056] Meanwhile, the water electrolysis device 100 may include a separator 300 connected to the (2-1) discharge pipe 301, and a (2-2) discharge pipe 302 and a (2-3) discharge pipe 303 respectively connected to the separator 300.

[0057] The separator 300 can be a device for separating solids contained in hydrogen produced by the water electrolysis reactor 110. A second discharge pipe 302 can be connected to the separator 300 to allow the hydrogen separated by the separator 300 to flow. A second discharge filter 310 and a second discharge valve 320 can be provided on the second discharge pipe 302, and when the second discharge valve 320 opens the second discharge pipe 302, the hydrogen flowing through the second discharge pipe 302 can be discharged to the outside after being filtered by the second discharge filter 310.

[0058] The (2-3) discharge pipe 303 connected to the separator 300 can discharge the solids generated in the separator 300 together with the discharge water. In addition, the discharge water discharged from the separator 300 can be recycled to the water tank 200.

[0059] Meanwhile, the effluent and feed water contained in the water tank 200 can flow through the supply pipe 101 to be supplied again to the water electrolyzer 110. To maintain the temperature of the effluent and feed water circulating through the supply pipe 101, a cooler 260 can be installed on the supply pipe 101. Hereinafter, the effluent and feed water flowing through the supply pipe 101 can be referred to as feed water. The feed water that has passed through the cooler 260 can be regulated to a temperature suitable for supplying to the water electrolyzer 110.

[0060] The supply line 101 can supply feed water to the circulation pump 400. In this way, the water electrolysis apparatus 100 may include the circulation pump 400 and the supply line 101, the circulation pump 400 being configured to pump feed water flowing through the supply line 101 to the water electrolysis reactor 110, and the supply line 101 being formed to supply feed water to the water electrolysis reactor 110.

[0061] The water electrolysis device 100 may include a transport layer 420 disposed between the circulating pump 400 and the water electrolysis stack 110. The water electrolysis device 100 may include an ion filter 440, an ion conductivity sensor 460, a supply tank 470, and a controller 500.

[0062] Ion filter 440 can be a component for removing ionic impurities contained in feed water. Supply sensor 450 can be located downstream of ion filter 440. Supply sensor 450 can be a component for determining whether feed water can be supplied to water electrolysis reactor 110 by measuring the ionic conductivity of the feed water that has passed through ion filter 440.

[0063] The transport layer 420 can be disposed on the supply pipe 101, between the ion filter 440 and the circulation pump 400. Unlike the ion filter 440, the transport layer 420 can be formed of titanium (Ti) metal. More specifically, the transport layer 420 can be disposed in the form of titanium fiber felt or titanium particles. When the ion filter 440 is a component for removing ionic impurities from the feed water, the transport layer 420 can be a component for precipitating particulate or organic impurities in the feed water.

[0064] The transport layer 420 can be disposed on the supply pipe 101, located upstream of the water electrolysis reactor 110. The transport layer 420 can be configured as a porous transport layer (PTL). To improve the sensitivity of the transport layer 420 compared to the stack transport layer (not shown) disposed inside the water electrolysis reactor 110, i) the pore size of the transport layer 420 can be equal to or smaller than the pore size of the stack transport layer, ii) the porosity of the transport layer 420 can be equal to or smaller than the porosity of the stack transport layer, or iii) the transport layer 420 can be configured to include two transport sublayers corresponding to the stack transport layer.

[0065] The stack transport layer included in the PTL can also be disposed inside the water electrolysis reactor 110 to precipitate impurities contained in the feed water introduced into the water electrolysis reactor 110. The transport layer 420 can be a component for pre-filtering impurities in the feed water supplied to the water electrolysis reactor 110 because it has a smaller porosity than the stack transport layer, has a pore size that is the same as or smaller than the pore size of the stack transport layer, or is configured to include two or more transport layers corresponding to the stack transport layer.

[0066] This configuration can improve the stability of the water electrolysis unit 100 because ionic impurities in the feed water supplied to the water electrolysis stack 110 can be filtered by the ion filter 440, and particulate or organic impurities can be filtered by the transport layer 420.

[0067] Meanwhile, when a certain amount or more of impurities precipitate in the transport layer 420, the supply of feed water to the water electrolysis reactor 110 needs to be stopped in order to ensure the stability of the water electrolysis reactor 110.

[0068] For this purpose, the water electrolysis device 100 may include a first pressure gauge 410 and a second pressure gauge 430 to estimate the amount of impurities precipitated on the transport layer 420. The first pressure gauge 410 may be installed on the supply pipe 101, located upstream of the transport layer 420. The second pressure gauge 430 may be installed on the supply pipe 101, located downstream of the transport layer 420.

[0069] More specifically, the first pressure gauge 410 may be disposed between the circulation pump 400 and the transport layer 420, and the second pressure gauge 430 may be disposed between the transport layer 420 and the ion filter 440.

[0070] The first pressure gauge 410 and the second pressure gauge 430 may be operatively coupled to the controller 500, and the controller 500 may include a memory (not shown) and a processor (not shown).

[0071] The memory may include: volatile memory such as static random access memory (S-RAM) and dynamic random access memory (D-RAM) for temporarily storing data while power is supplied; and non-volatile memory such as read-only memory (ROM) and erasable programmable read-only memory (EPROM) for storing data even when the power supply is cut off.

[0072] A processor may include various logic circuits and operational circuits, and can process data according to a program provided from memory and generate control signals based on the processing results.

[0073] The first pressure gauge 410 and the second pressure gauge 430 can be operatively coupled to the processor of the controller 500. That is, the first pressure gauge 410 can sense a first pressure of the feed water flowing between the circulation pump 400 and the transport layer 420 and transmit the first pressure to the processor, and the second pressure gauge 430 can sense a second pressure of the feed water flowing between the transport layer 420 and the ion filter 440 and transmit the second pressure to the processor.

[0074] The processor can calculate the difference between the first pressure and the second pressure, and when the difference between the first pressure and the second pressure is equal to or greater than a specific reference pressure difference, the processor can determine that the concentration of impurities precipitated by the transport layer 420 is equal to or greater than the reference concentration. Here, the reference pressure difference can be approximately 1.1 times the difference between the first initial value of the first pressure sensed by the first pressure gauge 410 and the second initial value of the second pressure sensed by the second pressure gauge 430 at the start of operation of the water electrolysis device 100.

[0075] In other words, when the difference between the first pressure and the second pressure increases to more than approximately 1.1 times the difference between the first initial value of the first pressure and the second initial value of the second pressure at the start of the calculation during the operation of the water electrolysis device 100, the processor can determine that the feed water in the transport layer 420 contains impurities at a specific concentration or in a specific amount. Here, "start" can be defined as the point in time when the water electrolysis device 100 begins operation.

[0076] When the processor determines that the feed water contains impurities at a concentration above a certain level, the processor can control the circulation pump 400 to stop its operation, and the processor can control the power supply unit 120 to stop supplying power to the water electrolysis reactor 110. For this purpose, the power supply unit 120 and the circulation pump 400 are operatively coupled to the processor.

[0077] In addition, when the processor determines that the feed water contains impurities at a certain concentration or higher, the processor can notify the user to replace the transport layer 420.

[0078] Meanwhile, the first pressure gauge 410 and the second pressure gauge 430 mentioned above can be components for detecting the pressure of the feed water at the corresponding position, but this disclosure is not limited thereto, and they can be components for detecting the flow rate at the corresponding position, and the processor can estimate the amount or concentration of impurities deposited in the transport layer 420 by the difference between the flow rates.

[0079] In addition, the water electrolysis device 100 may include an ionic conductivity sensor 460, which is disposed between the transport layer 420 and the water electrolysis stack 110 to detect the ionic conductivity of the feed water.

[0080] An ionic conductivity sensor 460 can be positioned between the ion filter 440 and the water electrolysis stack 110. Compared to the supply sensor 450, the discharge sensor 210, and the tank sensor 220, the ionic conductivity sensor 460 can have higher sensitivity to both positive and negative ion impurities.

[0081] The general supply sensor 450, discharge sensor 210, and tank sensor 220 used to measure ionic conductivity can be sensors provided with positive and negative electrodes to measure the ionic conductivity of the feed water as it flows through a pair of spaced-apart plates.

[0082] Unlike this, such as Figure 2 As shown, the ionic conductivity sensor 460 may include: an electrolyte membrane 461 for contacting the feed water as it flows; a current source 462 for applying an alternating current to the electrolyte membrane 461; and a voltage sensor 463 connected to the electrolyte membrane 461 and configured to sense the voltage between two points 463a and 463b, respectively.

[0083] In this configuration, a fixing plate (not shown) for fixing the electrolyte membrane 461 can be disposed on opposite sides of the electrolyte membrane 461 in the upward / downward direction, and a through hole can be formed in either fixing plate so that a portion of the feed water can contact the electrolyte membrane 461 through the through hole. Preferably, the feed water flows above the fixing plate located above the electrolyte membrane 461, and a portion of the flowing feed water can contact the electrolyte membrane 461 through the through hole.

[0084] In the electrolyte membrane 461 in contact with the feed water, an alternating current can be applied to two points 462a and 462b of the current source 462, and then the potential difference between the two points 463a and 463b can be detected by the voltage sensor 463 at two points 463a and 463b.

[0085] In this case, the conversion resistance value "R" corresponding to the real part of the value converted by the Nyquist plot can be calculated from the AC resistance value using the AC current applied to the electrolyte membrane 461. The Nyquist plot is a representation of the frequency function response of a linear system in polar coordinates.

[0086] The reason for calculating the conversion resistance value "R" corresponding to the real part is that the ionic conductivity of the feed water in contact with the electrolyte membrane 461 is calculated by using an implementation in which the resistance of the real part in the high-frequency region increases when ionic impurities are typically introduced into the electrolyte membrane 461 formed of a PFSA0-based material.

[0087] (σ) In this case, the ionic conductivity “σ” sensed by the ionic conductivity sensor 460 can be defined as Equation 1.

[0088] [Equation 1]

[0089] Regarding Equation 1 above, "L" can be the distance between two points 463a and 463b of the voltage sensor 463, "R" can be the converted resistance value corresponding to the real part of the value obtained by converting the AC resistance value caused by the AC current applied to the electrolyte membrane 461 through the Nyquist plot, and "A" can be the area "A" of the electrolyte membrane 461, which is defined in two mutually perpendicular directions in a plane perpendicular to one direction connected to the two points 463a and 463b of the voltage sensor 463.

[0090] That is, the ionic conductivity is calculated based on the AC resistance value caused by the alternating current applied to the electrolyte membrane 461, which is sensed by the ionic conductivity sensor 460. The ionic conductivity can be calculated as the distance "L" between the two points 463a and 463b of the voltage sensor 463 divided by the product of the converted resistance value "R" and the area "A" of the electrolyte membrane 461. The converted resistance value "R" corresponds to the real part of the value obtained by converting the AC resistance value through the Nyquist plot. The area "A" of the electrolyte membrane 461 is defined by the lengths in two mutually perpendicular directions in a plane perpendicular to one direction of the two points 463a and 463b of the voltage sensor 463 (i.e., the cross-sectional area of ​​the electrolyte membrane in a plane perpendicular to the direction of the line connecting the two points 463a and 463b).

[0091] The electrolyte membrane 461 of the ionic conductivity sensor 460 can be configured to be thinner than the internal electrolyte membrane (not shown) disposed inside the water electrolysis reactor 110. This can relatively increase the sensitivity of the ionic conductivity sensor 460.

[0092] like Figure 1As shown, the ionic conductivity sensor 460 can be operatively coupled to the processor of the controller 500. When the value of the ionic conductivity sensed by the ionic conductivity sensor 460 is equal to or less than a specific first reference conductivity, the processor can control the circulation pump 400 to stop its operation and can control the power supply unit 120 to stop supplying power to the water electrolysis reactor 110.

[0093] Here, the value of the first reference conductivity can refer to a value approximately 0.95 times the initial value of the ionic conductivity. In other words, when the value of the ionic conductivity sensed by the ionic conductivity sensor 460 decreases to less than approximately 0.95 times the initial value of the ionic conductivity sensed by the ionic conductivity sensor 460 during the operation of the water electrolysis device 100, the processor can execute control to stop the operation of the circulation pump 400 and the power supply unit 120. Here, "start" can be defined as the time point at which the water electrolysis device 100 begins operation.

[0094] Furthermore, when the value of the ionic conductivity sensed by the ionic conductivity sensor 460 decreases to less than approximately 0.95 times the value of the ionic conductivity sensed by the ionic conductivity sensor 460 at the beginning of operation of the water electrolysis device 100, the processor can notify the user to replace the electrolyte membrane 461.

[0095] Meanwhile, the water electrolysis device 100 may include a supply tank 470, which is connected to the supply pipe 101 at a point between the ion conductivity sensor 460 and the water electrolysis stack 110, to contain carbon dioxide to be supplied to the feed water.

[0096] like Figure 3 As shown, the supply tank 470 can be connected to the supply pipe 101 via a gas supply pipe 472. The gas supply pipe 472 may be a pipe for supplying carbon dioxide contained in the supply tank 470 to the feed water supplied to the water electrolysis reactor 110.

[0097] Water electrolysis device 100 (see Figure 1 The reactor may be equipped with an ejector 490 and an on / off valve 480. The ejector 490 is installed on the supply pipe 101 to pump carbon dioxide and feed water together to the water electrolysis reactor 110. The on / off valve 480 is installed on the gas supply pipe 472 and is located between the ejector 490 and the supply tank 470.

[0098] An on / off valve 480 may be provided on the gas supply line 472 to open and close the passage of the gas supply line 472. The on / off valve 480 is operatively coupled to a processor, and the processor may control the on / off valve 480 to supply carbon dioxide from the supply tank 470 to the feed water when the value of the ionic conductivity sensed by the ionic conductivity sensor 460 is equal to or less than a specific second reference conductivity.

[0099] In this case, the value of the second reference conductivity can be set to be greater than the value of the first reference conductivity described above. In other words, carbon dioxide can be supplied to the feed water when the ionic conductivity sensed by the ionic conductivity sensor 460 is less than the value of the second ionic conductivity. As an example, the value of the second reference conductivity can be approximately 0.97 times the initial value of the ionic conductivity.

[0100] The feed water “w” is used to help restore the performance of the water electrolyzer 110 because when carbon dioxide is supplied to the feed water, H+, HCO3- and CO2 are generated, and H+ can exchange ions with ionic impurities in the electrodes or internal electrolyte membrane of the water electrolyzer 110, so that the ionic impurities can be discharged to the outside of the water electrolyzer 110 instead of being contained in the water electrolyzer 110.

[0101] Subsequently, the gas supply sensor 471 senses the pressure of carbon dioxide supplied to the feed water, and when the pressure of carbon dioxide is lower than the pressure of the feed water, the processor can notify the user to fill with carbon dioxide.

[0102] According to the above structure, the durability and performance of the water electrolysis reactor 110 can be improved because the transport layer 420 can effectively reduce the amount of impurities in the water before the feed water is supplied to the water electrolysis reactor 110.

[0103] Furthermore, the durability and performance of the water electrolyzer 110 can be improved by estimating the amount or concentration of impurities deposited in the transport layer 420 via the first pressure gauge 410 and the second pressure gauge 430, in order to cut off the power supply to the water electrolyzer 110 or prevent feed water from being introduced into the water electrolyzer 110.

[0104] Furthermore, by using the ionic conductivity sensor 460 to more accurately measure the ionic conductivity in the feed water, the durability and performance of the water electrolysis reactor 110 can be improved by cutting off the power supply to the water electrolysis reactor 110 or preventing feed water from being introduced into the water electrolysis reactor 110.

[0105] Figure 4 This is a schematic diagram of a water electrolysis apparatus according to some embodiments of the present disclosure.

[0106] refer to Figure 4The transport layer 420, ion filter 440, and ion conductivity sensor 460 can be connected in parallel with the supply pipe 101, instead of as shown in the example. Figure 1 Similar to the water electrolysis device 100, the transport layer 420, ion filter 440 and ion conductivity sensor 460 are connected in series on the supply pipe 101.

[0107] According to this structure, the transport layer 420 and the ion filter 440 can be used only when needed, based on the condition of the feed water flowing through the supply pipe 101. Therefore, with Figure 1 Compared to the transport layer 420 and ion filter 440 in the water electrolysis device 100 shown, the lifespan of each of the transport layer 420 and ion filter 440 can be improved.

[0108] For except Figure 4 A configuration other than the transport layer 420, ion filter 440, and ion conductivity sensor 460 will be used. Figure 1 The description.

[0109] Figure 5 and Figure 6 This is a flowchart illustrating a method for controlling a water electrolysis apparatus according to some embodiments of the present disclosure.

[0110] refer to Figure 5 and Figure 6 When the water electrolysis device 100 (see Figure 1 When the operation of the water electrolysis device 100 starts (S10), the control method of the water electrolysis device 100 may include preparation operation (S20), supply operation (S30) and pressure calculation operation (S40).

[0111] The preparation operation (S20) may be an operation of preparing the transport layer 420 on the upstream side of the water electrolyzer 110 relative to the flow direction of the feed water. The supply operation (S30) may be an operation of supplying feed water to the water electrolyzer 110, such that the feed water passes through the transport layer 420 disposed on the upstream side of the water electrolyzer 110. The supply operation (S30) may also be an operation of filtering impurities contained in the feed water through the transport layer 420.

[0112] The pressure calculation operation (S40) may be an operation that calculates the first pressure of the feed water sensed by the first pressure gauge 410 located on the upstream side of the transport layer 420 and the second pressure of the feed water sensed by the second pressure gauge 430 located between the transport layer 420 and the water electrolysis reactor 110, in order to estimate the amount of impurities filtered by the transport layer 420.

[0113] The control method of the water electrolysis device 100 may include a pressure comparison operation (S50) for determining whether the pressure difference between a first pressure and a second pressure calculated in the pressure calculation operation (S40) is equal to or greater than a specific reference pressure. Here, the reference pressure may be a pressure value that is approximately 1.1 times the difference between a first initial value of the first pressure and a second initial value of the second pressure.

[0114] When the pressure difference between the first pressure and the second pressure is equal to or greater than the reference pressure (example of S50) during the pressure comparison operation (S50), a first stop operation (S60) can be performed to stop supplying power to the water electrolysis reactor 110 or to stop supplying feed water to the water electrolysis reactor 110, according to the control method of the water electrolysis device 100.

[0115] Furthermore, when the difference between the first pressure and the second pressure in the pressure comparison operation (S50) is equal to or greater than the reference pressure (S50 is), a filter notification operation (S70) can be performed to notify the user that the transport layer 420 needs to be replaced.

[0116] The filtering notification operation (S70) can be performed after the first stop operation (S60), or before the first stop operation (S60), and the first stop operation (S60) and the filtering notification operation (S70) can be performed simultaneously.

[0117] When the pressure difference between the first pressure and the second pressure is less than the reference pressure difference (No in S50) during the pressure comparison operation (S50), a sensing operation (S80) can be performed in the control method of the water electrolysis device 100.

[0118] The sensing operation (S80) can be an operation that senses the ionic conductivity of the feed water by using an ionic conductivity sensor 460 disposed between the second pressure gauge 430 and the water electrolysis stack 110.

[0119] Following the sensing operation (S80), in the control method of the water electrolysis apparatus 100, a first ionic conductivity determination operation (S90) can be performed to determine whether the ionic conductivity sensed by the sensing operation (S80) is equal to or less than a specific first ionic conductivity. Here, the first ionic conductivity may be a value approximately 0.95 times the initial value of the ionic conductivity sensed by the ionic conductivity sensor 460.

[0120] When the ionic conductivity sensed in the sensing operation (S80) is equal to or less than the first ionic conductivity (S90 is), a second stop operation (S100) can be performed in the control method of the water electrolysis device 100 to stop supplying power to the water electrolysis reactor 110 or to stop supplying feed water to the water electrolysis reactor 110.

[0121] Furthermore, when the ionic conductivity sensed by the sensing operation (S80) is equal to or less than the first ionic conductivity (S90 is), in the control method of the water electrolysis device 100, an electrolyte membrane notification operation (S110) can be performed to notify the user to replace the electrolyte membrane 461 included in the ionic conductivity sensor 460.

[0122] The electrolyte membrane notification operation (S110) can be performed after the second stop operation (S100), or before the second stop operation (S100), and the second stop operation (S100) and the electrolyte membrane notification operation (S110) can be performed simultaneously.

[0123] If the ionic conductivity sensed in the sensing operation (S80) is greater than the first ionic conductivity (No in S90), then in the control method of the water electrolysis device 100, a second ionic conductivity determination operation (S120) can be performed.

[0124] The second ionic conductivity determination operation (S120) can be an operation that determines whether the ionic conductivity sensed in the sensing operation (S80) is equal to or less than a specific second ionic conductivity. Here, the value of the second ionic conductivity can be set to be greater than the value of the first ionic conductivity. As an example, when the value of the first ionic conductivity is approximately 0.95 times the initial ionic conductivity value, the value of the second ionic conductivity can be approximately 0.97 times the initial ionic conductivity value.

[0125] When the ionic conductivity sensed by the sensing operation (S80) is equal to or less than the second ionic conductivity (S120), a gas supply operation (S130) can be performed in the control method of the water electrolysis device 100.

[0126] The gas supply operation (S130) can be an operation of supplying carbon dioxide to the feed water from a supply tank 470 connected to a point between the ion conductivity sensor 460 and the water electrolysis reactor 110. The reason for supplying carbon dioxide to the feed water may be to remove impurities inside the water electrolysis reactor 110 as described above.

[0127] In the control method of the water electrolysis device 100, a gas pressure comparison operation (S140) can be performed after the gas supply operation (S130). The gas pressure comparison operation (S140) can be an operation that compares the pressure of carbon dioxide supplied from the gas supply operation (S130) with the pressure of the feed water.

[0128] In the method of controlling the water electrolysis device 100, when the pressure of carbon dioxide is lower than the pressure of the feed water in the gas pressure comparison operation (S140) (S140 is), a filling notification operation (S150) can be performed.

[0129] When the pressure of carbon dioxide supplied from the gas supply operation (S130) is lower than the pressure of the feed water (S140), the filling notification operation (S150) can be an operation to notify the user to fill carbon dioxide.

[0130] The control method of the water electrolysis device 100 can be terminated (S160) after the filling notification operation (S150) or when it corresponds to the no of the second ion conductivity determination operation (S120) or the no of the gas pressure comparison operation (S140).

[0131] The effect of the control method of the water electrolysis device 100 will be replaced by the above description.

[0132] According to this technology, when the amount of impurities in the feed water flowing into the water electrolysis reactor is equal to or greater than a certain amount due to the transport layer located on the upstream side of the water electrolysis reactor, the power supply to the water electrolysis reactor can be cut off or the circulation of the feed water can be stopped, thereby improving the stability of the water electrolysis reactor.

[0133] Furthermore, according to this technology, availability can be improved because the exchange time of the transport layer can be identified by using a first pressure gauge and a second pressure gauge located on the upstream and downstream sides of the transport layer.

[0134] Furthermore, the improved sensitivity of the ionic conductivity sensor enhances the safety of the water electrolysis device.

[0135] Furthermore, according to this technology, the use can be improved because the exchange time of the electrolyte membrane included in the ionic conductivity sensor can be identified by using an ionic conductivity sensor.

[0136] Furthermore, according to this technology, the safety of the water electrolysis device can be improved because carbon dioxide can be supplied to the feed water by using an ionic conductivity sensor.

[0137] Furthermore, according to this technology, the carbon dioxide exchange time can be identified when the carbon dioxide pressure is lower than the feed water pressure, thus improving its usability.

[0138] In addition, various effects can be provided directly or indirectly through this disclosure.

[0139] The above description is merely an example of the technical concept of this disclosure, and various modifications and changes can be made by those skilled in the art without departing from the essential characteristics of this disclosure.

[0140] Therefore, the embodiments described herein are not intended to be limiting, but rather to explain the technical concept of the disclosure, and the scope and spirit of the disclosure are not limited to the described embodiments. The scope of protection of this disclosure should be interpreted by the appended claims, and all equivalents thereof should be interpreted as being included within the scope of this disclosure.

Claims

1. A water electrolysis device, comprising: Hydroelectric reactor; The supply pipeline is configured to deliver feed water to the water electrolysis reactor; as well as The transport layer is located on the supply pipeline and upstream of the water electrolysis reactor.

2. The water electrolysis device according to claim 1, further comprising: A power supply unit is configured to supply power to the water electrolysis reactor; as well as The processor is operatively coupled to the power supply unit. The processor is configured to control the power supply unit to stop supplying power to the water electrolysis reactor when the concentration of impurities precipitated by the transport layer is greater than or equal to a reference concentration.

3. The water electrolysis device according to claim 2, further comprising: The first pressure gauge is installed on the supply pipeline and located upstream of the transport layer; as well as The second pressure gauge is installed on the supply pipeline, located between the transport layer and the water electrolysis reactor. The processor is configured to determine that the concentration of the impurity has reached the reference concentration when the difference between the first pressure sensed by the first pressure gauge and the second pressure sensed by the second pressure gauge is greater than or equal to the reference pressure difference.

4. The water electrolysis apparatus according to claim 3 further includes: A circulation pump is configured to pump the feed water via the supply line, and the circulation pump is operatively coupled to the processor. Specifically, when the difference between the first pressure and the second pressure is greater than or equal to the reference pressure difference, the processor stops the circulating pump.

5. The water electrolysis device according to claim 3, wherein, The reference pressure difference is 1.1 times the initial pressure difference between the first pressure gauge and the second pressure gauge.

6. The water electrolysis apparatus according to claim 2, further comprising: An ionic conductivity sensor is located between the transport layer and the water electrolysis reactor, and the ionic conductivity sensor is configured to sense the ionic conductivity of the feed water.

7. The water electrolysis apparatus according to claim 6, wherein, The processor is operatively coupled to the ionic conductivity sensor, and when the value of the ionic conductivity sensed by the ionic conductivity sensor is less than or equal to a first reference ionic conductivity, the processor controls the power supply unit to stop supplying power to the water electrolysis reactor.

8. The water electrolysis apparatus according to claim 7, wherein, The value of the first reference ionic conductivity is 0.95 times the initial value of the ionic conductivity.

9. The water electrolysis apparatus according to claim 6, wherein, The ionic conductivity sensor includes: The electrolyte membrane is in contact with the feed water; A current source is configured to apply a current to the electrolyte membrane; and A voltage sensor is connected to two points on the electrolyte membrane to sense the voltage between the two points.

10. The water electrolysis apparatus according to claim 9, wherein, The current source applies an alternating current to the electrolyte membrane, and The sensing of the ionic conductivity of the feed water includes: calculating the ionic conductivity based on the AC resistance value caused by the AC current applied to the electrolyte membrane, sensed by the ionic conductivity sensor. The ionic conductivity is calculated as the distance between the two points divided by the product of the converted resistance value and the area of ​​the electrolyte membrane. The converted resistance value corresponds to the real part of the value obtained by converting the AC resistance value using a Nyquist plot. The area of ​​the electrolyte membrane is defined by the lengths in two mutually perpendicular directions within a plane perpendicular to the direction connecting the two points.

11. The water electrolysis apparatus according to claim 9, wherein, The water electrolysis reactor includes an internal electrolyte membrane disposed inside the water electrolysis reactor, and The thickness of the electrolyte membrane is less than the thickness of the inner electrolyte membrane.

12. The water electrolysis apparatus according to claim 1, wherein, The water electrolysis reactor includes a stack transport layer disposed inside the water electrolysis reactor, and the stack transport layer is configured to precipitate impurities contained in the feed water introduced into the water electrolysis reactor. Wherein, i) the pore size of the transport layer is less than or equal to the pore size of the stack transport layer, ii) the porosity of the transport layer is less than or equal to the porosity of the stack transport layer, or iii) the transport layer is configured to include two transport sublayers corresponding to the stack transport layer.

13. The water electrolysis apparatus according to claim 7, further comprising: A supply tank is connected to a point on the supply pipeline located between the ion conductivity sensor and the water electrolysis stack, and the supply tank contains carbon dioxide to be supplied to the feed water; An ejector is disposed on the supply line and the ejector is configured to pump the carbon dioxide together with the feed water to the water electrolysis reactor; as well as An on / off valve is located between the injector and the supply tank.

14. The water electrolysis apparatus according to claim 13, wherein, The on / off valve is operably coupled to the processor, and The processor is configured to control the opening and closing valve to supply carbon dioxide from the supply tank to the feed water when the value of the ionic conductivity sensed by the ionic conductivity sensor is equal to or less than the second reference ionic conductivity.

15. The water electrolysis apparatus according to claim 14, wherein, The value of the second reference ionic conductivity is greater than the value of the first reference ionic conductivity.

16. A control method for a water electrolysis device, the method comprising: Feed water is supplied to the water electrolysis reactor, such that the feed water passes through the transport layer upstream of the water electrolysis reactor; Calculate the pressure difference between the first pressure of the feed water sensed by a first pressure gauge located upstream of the transport layer and the second pressure of the feed water sensed by a second pressure gauge disposed between the transport layer and the water electrolysis reactor; as well as When the pressure difference is greater than or equal to the reference pressure difference, the supply of electricity to the water electrolysis reactor or the supply of feed water to the water electrolysis reactor shall be stopped.

17. The method of claim 16, further comprising: The ionic conductivity of the feed water is sensed using an ionic conductivity sensor positioned between the second pressure gauge and the water electrolysis reactor. as well as When the sensed ionic conductivity is equal to or less than the first ionic conductivity, the power supply to the water electrolysis reactor or the feed water supply to the water electrolysis reactor is stopped.

18. The method of claim 17, further comprising: When the pressure difference is greater than or equal to the reference pressure difference, the user is notified to replace the transport layer. as well as When the ionic conductivity sensed during the sensing of the ionic conductivity is equal to or less than the first ionic conductivity, the user is notified to replace the electrolyte membrane contained in the ionic conductivity sensor.

19. The method of claim 17, further comprising: Carbon dioxide is supplied to the feed water when the ionic conductivity sensed during the sensing period is equal to or less than a specific second ionic conductivity.

20. The method of claim 19, further comprising: When the pressure of the carbon dioxide supplied to the feed water is less than the pressure of the feed water, the user is notified to fill the carbon dioxide.

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