Electrochemical system

Abstract

The invention relates to an electrochemical system. An embodiment of an electrochemical system includes a reaction fluid supply line configured to supply a reaction fluid, a first gas-liquid separator, a circulation line, a water electrolysis stack, and a first bypass line; a first gas-liquid separator connected to the reaction fluid supply line and configured to separate the reaction fluid into a gaseous reaction fluid and a liquid reaction fluid; a circulation line connected to the first gas-liquid separator and configured to enable liquid reaction fluid to circulate through the circulation line; the water electrolysis galvanic pile is arranged in the circulating pipeline; and a first bypass line having a first end located on the upstream side of the water electrolysis stack and connected to the circulation line and a second end located on the downstream side of the water electrolysis stack and connected to the circulation line.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2023-0152000, filed on November 6, 2023, which is hereby incorporated by reference into this application. Technical Field

[0003] The present invention relates to electrochemical systems for filtering ions and foreign matter from a reactive fluid. Background Art

[0004] In response to global warming and the depletion of fossil fuels, the need for research and development of alternative energy sources is increasing. Hydrogen energy has attracted attention as a practical solution to environmental and energy issues.

[0005] In particular, hydrogen has attracted much attention as a future energy carrier due to its high energy density and suitability for grid-scale applications.

[0006] A water electrolysis stack as an electrochemical device refers to a device that generates hydrogen and oxygen by electrochemically decomposing water. The water electrolysis stack may be configured by stacking dozens or hundreds of water electrolysis cells (unit cells) in series.

[0007] Meanwhile, when the reaction fluid (reactant) (e.g., water) supplied to an electrochemical device (e.g., a water electrolysis stack) contains ions and foreign matter (impurities), the performance, durability, and reliability of the electrochemical device decrease. Therefore, this decrease can be reduced by removing the ions and foreign matter contained in the reaction fluid as much as possible. Summary of the invention

[0008] The present invention relates to an electrochemical system, and more particularly, to an electrochemical system capable of ensuring the performance of a water electrolysis stack and improving the durability and stability of the water electrolysis stack.

[0009] Embodiments of the present invention may provide a filter device for an electrochemical device that can ensure the performance of a water electrolysis stack and improve the durability and stability of the water electrolysis stack.

[0010] Specifically, embodiments of the present invention may enable a low-quality reaction fluid (eg, a reaction fluid having a higher ionic conductivity) to flow along a bypass line to a circulation line and be reprocessed (eg, deionized) without being supplied to a water electrolysis stack.

[0011] Among other things, embodiments of the present invention may extend the service life of a water electrolysis stack and minimize degradation of the durability and stability of the water electrolysis stack caused by supplying low-quality reactant fluid to the water electrolysis stack.

[0012] The embodiments of the present invention can continuously supply the reaction fluid to the water electrolysis stack without stopping the operation of the system when replacing the filter and prevent the reaction fluid of low quality from being supplied to the water electrolysis stack.

[0013] The embodiment of the present invention can prevent pollutants remaining on the inner wall surface of the gas-liquid separator from being supplied to the water electrolysis stack.

[0014] The advantages achieved by the embodiments of the present invention are not necessarily limited to the above-mentioned advantages, and additional advantages may be understood from the solutions or embodiments described below.

[0015] In order to achieve part or all of the above advantages, according to an exemplary embodiment of the present invention, the electrochemical system includes: a reaction fluid supply pipeline, a first gas-liquid separator, a circulation pipeline, a water electrolysis stack and a first bypass line, wherein the reaction fluid supply pipeline is configured to supply the reaction fluid; the first gas-liquid separator is connected to the reaction fluid supply pipeline and is configured to separate the reaction fluid into a gaseous reaction fluid and a liquid reaction fluid; the circulation pipeline is connected to the first gas-liquid separator and is configured to enable the liquid reaction fluid to circulate through the circulation pipeline; the water electrolysis stack is arranged in the circulation pipeline; one end of the first bypass line is located on the upstream side of the water electrolysis stack and is connected to the circulation pipeline, and the other end is located on the downstream side of the water electrolysis stack and is connected to the circulation pipeline.

[0016] According to an exemplary embodiment of the present invention, the electrochemical system may include a first circulation three-way valve provided in the circulation line and connected to one end of the first bypass line.

[0017] According to an exemplary embodiment of the present invention, the electrochemical system may include a first circulating ion sensor, which is located on the upstream side of the water electrolysis stack, arranged in the circulation pipeline, and configured to sense the ionic conductivity of the liquid reaction fluid; wherein the first circulating three-way valve is configured to enable the liquid reaction fluid to selectively flow from the upstream side of the water electrolysis stack to the downstream side of the water electrolysis stack based on the sensing results from the first circulating ion sensor.

[0018] According to an exemplary embodiment of the present invention, the electrochemical system may include a circulation filter located between the first gas-liquid separator and the inlet of the water electrolysis stack, disposed in the circulation line, and configured to filter the liquid reaction fluid.

[0019] According to an exemplary embodiment of the present invention, the electrochemical system may include a filter portion provided in a reaction fluid supply line and configured to filter the reaction fluid.

[0020] According to an exemplary embodiment of the present invention, the filter section may include a first filter line connected to a reaction fluid supply line and equipped with a first filter, and a second filter line positioned in parallel with the first filter line, connected to the reaction fluid supply line and equipped with a second filter.

[0021] According to an exemplary embodiment of the present invention, the electrochemical system may include a filter three-way valve provided in the reaction fluid supply line and connected to one end of the first filter line and one end of the second filter line.

[0022] According to an exemplary embodiment of the present invention, the electrochemical system may include: a first filter ion sensor and a second filter ion sensor, wherein the first filter ion sensor is located on the downstream side of the first filter, is arranged in the first filter pipeline, and is configured to sense the ionic conductivity of the reaction fluid; the second filter ion sensor is located on the downstream side of the second filter, is arranged in the second filter pipeline, and is configured to sense the ionic conductivity of the reaction fluid; wherein the filter three-way valve is configured to selectively switch the movement route of the reaction fluid to the first filter pipeline or the second filter pipeline based on the sensing results from the first filter ion sensor and the second filter ion sensor.

[0023] According to an exemplary embodiment of the present invention, the electrochemical system may include a second bypass line, a second gas-liquid separator and a recirculation line, wherein the second bypass line is located on the downstream side of the water electrolysis stack and is connected to the circulation line; the second gas-liquid separator is connected to the second bypass line and is configured to separate the bypass fluid flowing along the second bypass line into a gaseous reaction fluid and a liquid reaction fluid; one end of the recirculation line is connected to the second gas-liquid separator, and the other end is connected to the first gas-liquid separator, and the recirculation line is configured to recirculate the liquid reaction fluid that has passed through the second gas-liquid separator to the first gas-liquid separator.

[0024] According to an exemplary embodiment of the present invention, the electrochemical system may include a second circulation three-way valve provided in the circulation line and connected to one end of the second bypass line.

[0025] According to an exemplary embodiment of the present invention, the electrochemical system may include a second circulating ion sensor, which is located on the downstream side of the water electrolysis stack, arranged in the circulation pipeline, and configured to sense the ionic conductivity of the liquid reaction fluid; wherein the second circulation three-way valve is configured to enable the bypass fluid to selectively flow from the circulation pipeline to the second bypass pipeline based on the sensing result from the second circulating ion sensor.

[0026] According to an exemplary embodiment of the present invention, the electrochemical system may include a third bypass line having one end connected to the recirculation line and the other end connected to the second gas-liquid separator.

[0027] According to an exemplary embodiment of the present invention, the electrochemical system may include a recirculation three-way valve provided in the recirculation line and connected to the third bypass line.

[0028] According to an exemplary embodiment of the present invention, the electrochemical system may include a recycling ion sensor, which is arranged in a recycling line and configured to sense the ionic conductivity of the liquid reaction fluid; wherein the recycling three-way valve is configured to enable the liquid reaction fluid to selectively flow from the recycling line to a third bypass line based on the sensing results from the recycling ion sensor.

[0029] According to an exemplary embodiment of the present invention, the electrochemical system may include a storage part located at an upstream side of the first gas-liquid separator, provided in the reaction fluid supply line, and configured to store the reaction fluid.

[0030] According to an exemplary embodiment of the present invention, the electrochemical system may include a first cleaning pipeline, one end of which is connected to the storage part and the other end is connected to the second gas-liquid separator, and the first cleaning pipeline is configured to supply the reaction fluid to the inner wall surface of the second gas-liquid separator.

[0031] According to an exemplary embodiment of the present invention, the electrochemical system may include: a discharge pipeline, a switching valve, and an ion sensor, wherein the discharge pipeline is connected to a second gas-liquid separator and is configured to discharge the liquid reaction fluid from the second gas-liquid separator to the outside; the switching valve is configured to selectively open or close the discharge pipeline; the ion sensor is disposed in the second gas-liquid separator and is configured to sense the ionic conductivity of the liquid reaction fluid in the second gas-liquid separator; wherein the switching valve is configured to selectively open the discharge pipeline based on the sensing result from the ion sensor.

[0032] According to an exemplary embodiment of the present invention, the electrochemical system may include a second cleaning line, one end of which is connected to the first cleaning line and the other end is connected to the first gas-liquid separator, and the second cleaning line is configured to supply the reaction fluid to the inner wall surface of the first gas-liquid separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings of exemplary embodiments, in which:

[0034] Figure 1 is a block diagram of an electrochemical system according to an embodiment of the present invention;

[0035] Figures 2 to 4 is a block diagram for explaining a moving route of a reaction fluid along a circulation line in an electrochemical system according to an embodiment of the present invention;

[0036] Figure 5 and Figure 6 is a block diagram for explaining a moving route of a reaction fluid along a filter section in an electrochemical system according to an embodiment of the present invention;

[0037] Figure 7 and Figure 8 is a schematic diagram for explaining a cleaning line in an electrochemical system according to an embodiment of the present invention; and

[0038] Fig. 9 is a schematic diagram for explaining a modified example of the second gas-liquid separator of the electrochemical system according to the embodiment of the present invention. DETAILED DESCRIPTION

[0039] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0040] However, the technical spirit of the present invention is not limited to certain embodiments described herein, but can be implemented in various forms. One or more constituent elements in the embodiments can be selectively combined and replaced to be used within the scope of the technical spirit of the present invention.

[0041] In addition, unless otherwise specifically and clearly defined and explained, the terms (including technical and scientific terms) used in describing the embodiments of the present invention may be interpreted as the meanings commonly understood by those of ordinary skill in the art to which the present invention belongs. The meanings of commonly used terms (e.g., terms defined in dictionaries) may be interpreted according to the contextual meanings of the relevant technology.

[0042] Furthermore, the terms used in the embodiments of the present invention are for explaining the embodiments and are not necessarily for limiting the present invention.

[0043] In this specification, unless otherwise specifically stated, a singular form may also include a plural form. The expression "at least one (or one or more) of A, B, and C" may include one or more combinations of all combinations that can be formed by combining A, B, and C.

[0044] In addition, terms such as "first", "second", "A", "B", "(a)", and "(b)" may be used to describe constituent elements of embodiments of the present invention. These terms are used only for the purpose of distinguishing one constituent element from another constituent element, and the nature, sequence, or order of the constituent elements is not necessarily limited by these terms.

[0045] In addition, when one constituent element is described as being “connected,” “joined” or “attached” to another constituent element, the one constituent element may be directly connected, joined or attached to the other constituent element, or may be connected, joined or attached to the other constituent element with another constituent element or elements interposed therebetween.

[0046] In addition, the expression "one constituent element is disposed or positioned above (upper) or below (lower) another constituent element" includes not only the case where the two constituent elements are in direct contact with each other, but also the case where one or more other constituent elements are disposed or positioned between the two constituent elements. The expression "above (upper) or below (lower)" may refer to a downward direction and an upward direction based on one constituent element.

[0047] refer to Figures 1 to 9 For an embodiment of the present invention, the electrochemical system 10 includes a reaction fluid supply pipeline 110, a first gas-liquid separator 130, a circulation pipeline 140, a water electrolysis stack 20 and a first bypass pipeline 150, wherein the reaction fluid supply pipeline 110 is configured to supply a reaction fluid; the first gas-liquid separator 130 is connected to the reaction fluid supply pipeline 110 and is configured to separate the reaction fluid into a gaseous reaction fluid and a liquid reaction fluid; the circulation pipeline 140 is connected to the first gas-liquid separator 130 and is configured to allow the liquid reaction fluid to circulate through; the water electrolysis stack 20 is arranged in the circulation pipeline 140; one end of the first bypass pipeline 150 is located on the upstream side of the water electrolysis stack 20 and is connected to the circulation pipeline 140, and the other end of the first bypass pipeline 150 is located on the downstream side of the water electrolysis stack 20 and is connected to the circulation pipeline 140.

[0048] For reference, the electrochemical system 10 according to the embodiment of the present invention can be used to produce electrochemical reactions between various reaction fluids according to the desired conditions and design specifications. The present invention is not necessarily restricted or limited by the type and nature of the reaction fluid used in the electrochemical system 10.

[0049] For example, the electrochemical system 10 according to an embodiment of the present invention may be used to generate hydrogen and oxygen by decomposing water (reaction fluid) through an electrochemical reaction.

[0050] The reaction fluid supply line 110 may be configured to supply a reaction fluid (eg, water) to the water electrolysis stack 20 .

[0051] The reaction fluid supply line 110 may have various structures capable of supplying the reaction fluid. The present invention is not necessarily restricted or limited by the structure and shape of the reaction fluid supply line 110.

[0052] For example, the reaction fluid supply line 110 may be defined as a shape that is approximately a straight line. According to another embodiment of the present invention, the reaction fluid supply line may be defined as a curved shape or other shapes.

[0053] In addition, the reaction fluid supply line 110 may be equipped with various types of accessory devices, for example, a pump (not shown) configured to forcibly move the reaction fluid along the reaction fluid supply line 110, and a valve (not shown) configured to selectively open or close the reaction fluid supply line 110. The present invention is not necessarily restricted or limited by the type of accessory device and the number of accessory devices.

[0054] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a filter unit 120 disposed in the reaction fluid supply line 110 and configured to filter the reaction fluid.

[0055] In the embodiment of the present invention, the configuration in which the filter part 120 filters the reaction fluid may be a configuration in which the filter part 120 removes ions and foreign substances (impurities) contained in the reaction fluid.

[0056] The filter part 120 may have various structures capable of filtering out ions and foreign substances (impurities) contained in the reaction fluid. The present invention is not necessarily restricted or limited by the type and structure of the filter part 120.

[0057] According to an exemplary embodiment of the present invention, the filter part 120 may include a plurality of filter lines connected in parallel.

[0058] Hereinafter, an example in which the filter part 120 includes two filter lines will be described. According to another embodiment of the present invention, the filter part may include three or more filter lines. Alternatively, the filter part may include only one filter line.

[0059] According to an exemplary embodiment of the present invention, the filter unit 120 may include a first filter line 122 and a second filter line 124, wherein the first filter line 122 is connected to the reaction fluid supply line 110 and is equipped with a first filter 122a, and the second filter line 124 is connected in parallel with the first filter line 122 and is connected to the reaction fluid supply line 110 and is equipped with a second filter 124a.

[0060] For example, a plurality of first filters 122 a may be connected (arranged) in series in the first filter line 122 , and a plurality of second filters 124 a may be connected (arranged) in series in the second filter line 124 .

[0061] Various ion filters that can filter out the ions and foreign matter (impurities) contained in the reaction fluid can be used as the first filter 122a and the second filter 124a. The present invention is not necessarily subject to the constraints or restrictions of the type and properties of the ion filter. For example, pre-filters, carbon filters, reverse osmosis (everse osmosis, RO) membrane filters, ion exchange resins, ultraviolet (UV) lamps, etc. or any combination thereof can be used as the first filter 122a and the second filter 124a.

[0062] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a filter three-way valve 126 disposed in the reaction fluid supply line 110 and connected to one end of the first filter line 122 and one end of the second filter line 124 .

[0063] Various three-way valves capable of switching the moving route of the reaction fluid supplied along the reaction fluid supply line 110 to the first filter line 122 or the second filter line 124 may be used as the filter three-way valve 126. The present invention is not necessarily restricted or limited by the type and structure of the filter three-way valve 126.

[0064] For example, the filter three-way valve 126 may include a first port (not shown), a second port (not shown), and a third port (not shown), the reaction fluid supplied to the reaction fluid supply line 110 is introduced into the first port, the second port is connected to the first filter line 122 and is configured to guide the reaction fluid passing through the first port to the first filter line 122, and the third port is connected to the second filter line 124 and is configured to guide the reaction fluid passing through the first port to the second filter line 124. The filter three-way valve 126 can selectively switch the movement route of the reaction fluid by opening or closing the first port to the third port.

[0065] The operation of opening or closing the first port to the third port may be defined as including the operation of completely closing or opening the first port to the third port and the operation of adjusting the opening degree (valve opening angle) (eg, adjusting the degree of port opening).

[0066] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include: a first filter ion sensor 122b and a second filter ion sensor 124b, wherein the first filter ion sensor 122b is located on the downstream side of the first filter 122a, is disposed in the first filter pipeline 122, and is configured to sense the ionic conductivity of the reaction fluid; the second filter ion sensor 124b is located on the downstream side of the second filter 124a, is disposed in the second filter pipeline 124, and is configured to sense the ionic conductivity of the reaction fluid.

[0067] Various ion sensors capable of sensing the ionic conductivity of the reaction fluid may be used as the first filter ion sensor 122b and the second filter ion sensor 124b. The present invention is not necessarily restricted or limited by the type and structure of the first filter ion sensor 122b and the second filter ion sensor 124b.

[0068] Specifically, the moving route of the reaction fluid may be controlled by controlling the filter three-way valve 126 based on the sensing results from the first filter ion sensor 122 b and the second filter ion sensor 124 b .

[0069] The filter three-way valve 126 may be configured to switch a moving route of the reaction fluid supplied along the supply line to the first filter line 122 or the second filter line 124 based on sensing results from the first filter ion sensor 122 b and the second filter ion sensor 124 b .

[0070] For example, refer to Figure 5 When the ionic conductivity of the reaction fluid sensed by the second filter ion sensor 124b is higher than a threshold or a preset reference ionic conductivity (e.g., 1 μS / cm), the movement route of the reaction fluid supplied along the supply line can be defined as along the first filter line 122 by controlling the filter three-way valve 126.

[0071] On the contrary, Figure 6 As shown, when the ionic conductivity of the reaction fluid sensed by the first filter ion sensor 122b is higher than a threshold or a preset reference ionic conductivity (e.g., 1 μS / cm), the movement route of the reaction fluid supplied along the supply pipeline can be defined as along the second filter pipeline 124 instead of the first filter pipeline 122 by controlling the filter three-way valve 126.

[0072] For reference, when the second filter reaches the end of its service life or otherwise requires repair or replacement, the second filter 124a installed in the second filter line 124 can be replaced with a new filter while the reactive fluid moves along the first filter line 122. In the same manner, when the first filter reaches the end of its service life or otherwise requires repair or replacement, the first filter 122a installed in the first filter line 122 can be replaced with a new filter while the reactive fluid moves along the second filter line 124.

[0073] As described above, in the embodiment of the present invention, the moving route of the reaction fluid supplied along the supply line can be selectively switched to the first filter line 122 or the second filter line 124. Therefore, the advantageous effect of being able to continuously supply the reaction fluid to the water electrolysis stack 20 without stopping the system even when the filter is replaced can be obtained. In addition, the advantageous effect of preventing the supply of low-quality reaction fluid to the water electrolysis stack 20 can be obtained.

[0074] Specifically, when the time for replacing the first filter 122a or the second filter 124a is reached, the warning generation unit (not shown) can generate a visual warning signal (for example, a notification window on the control program screen) or an auditory warning signal to enable the operator to identify the end of the service life of the first filter 122a or the second filter 124a, thereby enabling the operator to promptly replace the first filter 122a or the second filter 124a whose service life has expired.

[0075] In the embodiment of the present invention illustrated and described above, an example has been described in which the first filter line 122 and the second filter line 124 are connected in parallel to the reaction fluid supply line 110. However, according to another embodiment of the present invention, the first filter line and the second filter line may be connected (configured) in series to the reaction fluid supply line.

[0076] The first gas-liquid separator 130 may be connected to the reaction fluid supply line 110 and configured to separate the reaction fluid into a gaseous reaction fluid (eg, oxygen) and a liquid reaction fluid (eg, water).

[0077] Various separation devices capable of separating the reaction fluid into gaseous reaction fluid and liquid reaction fluid may be used as the first gas-liquid separator 130. The present invention is not necessarily restricted or limited by the type and structure of the first gas-liquid separator 130.

[0078] For example, the first gas-liquid separator 130 can be provided in the form of a hollow tank. For example, the reaction fluid supply line 110 can be connected to the near-center portion of the first gas-liquid separator 130. A discharge port (not shown) can be provided at the near lower end of the first gas-liquid separator 130, and the discharge port is configured to discharge the liquid reaction fluid in the first gas-liquid separator 130 to the outside. In addition, a liquid level sensor (not shown) can be provided in the first gas-liquid separator 130, and the liquid level sensor is configured to detect the liquid level of the liquid reaction fluid.

[0079] The circulation line 140 may be connected to the first gas-liquid separator 130 via the water electrolysis stack 20 , and the liquid reaction fluid separated by the first gas-liquid separator 130 may circulate along the circulation line 140 .

[0080] More specifically, the reaction fluid (gaseous reaction fluid and liquid reaction fluid) discharged from the water electrolysis stack 20 can be supplied or returned to the first gas-liquid separator 130 along the circulation pipeline 140, and the liquid reaction fluid separated by the first gas-liquid separator 130 can be supplied back to the water electrolysis stack 20 along the circulation pipeline 140.

[0081] The circulation line 140 may have various structures that can be connected to the first gas-liquid separator 130 via the water electrolysis stack 20. The present invention is not necessarily restricted or limited by the structure and shape of the circulation line 140.

[0082] Hereinafter, the connection of the circulation line 140 to the side of the first gas-liquid separator 130 (see Figure 1 For example, the inlet end of the circulation line 140 may be connected to the side of the lower end of the first gas-liquid separator 130, and the outlet end of the circulation line 140 may be connected to the side of the upper end of the first gas-liquid separator 130.

[0083] Specifically, the inlet end of the circulation line 140 can be connected to the first gas-liquid separator 130 so that the inlet end of the circulation line 140 is at a position lower than the liquid level of the liquid reaction fluid separated by the first gas-liquid separator 130 (for example, the side of the lowermost end of the first gas-liquid separator).

[0084] In addition, a pump (not shown) may be provided in the circulation line 140 , wherein the pump is configured to force the liquid reaction fluid to move along the circulation line 140 to the water electrolysis stack 20 .

[0085] According to another embodiment of the present invention, the circulation line may be connected to the upper end or other parts of the first gas-liquid separator.

[0086] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a storage part 112 located at an upstream side of the first gas-liquid separator 130 , provided in the reaction fluid supply line 110 , and configured to store the reaction fluid.

[0087] For example, the storage part 112 may be located between the filter part 120 and the first gas-liquid separator 130 , and provided in the reaction fluid supply line 110 .

[0088] The storage part 112 may have various structures capable of storing the reaction fluid. The present invention is not necessarily restricted or limited by the structure and shape of the storage part 112.

[0089] For example, the storage part 112 may be provided in the form of a hollow can. The reaction fluid having passed through the filter part 120 may be temporarily stored in the storage part 112 before the reaction fluid is supplied to the first gas-liquid separator 130 .

[0090] In addition, a discharge port (not shown) may be provided near the lower end of the storage portion 112 , and the discharge port is configured to selectively discharge the reaction fluid in the storage portion 112 to the outside.

[0091] The water electrolysis stack 20 may be disposed in the circulation line 140 and decompose water (reaction fluid) through an electrochemical reaction to generate hydrogen and oxygen.

[0092] The water electrolysis stack 20 may have various structures capable of decomposing a reaction fluid through an electrochemical reaction to produce hydrogen and oxygen. The present invention is not necessarily restricted or limited by the type and structure of the water electrolysis stack 20.

[0093] For example, the water electrolysis stack 20 may be manufactured by stacking a plurality of unit cells (not shown) in a preset reference stacking direction.

[0094] More specifically, the unit cell may include a reaction layer (not shown) and a diaphragm (not shown) stacked on two opposite surfaces of the reaction layer, respectively. The water electrolysis stack 20 may be configured by stacking a plurality of unit cells in a reference stacking direction and then fastening an end plate (not shown) to two opposite ends of the stack of the plurality of unit cells.

[0095] The reaction layer may have various structures capable of producing an electrochemical reaction of a reaction fluid (eg, water). The present invention is not necessarily restricted or limited by the type and structure of the reaction layer.

[0096] For example, the reaction layer may include a membrane electrode assembly (MEA) (not shown), a first porous transport layer (not shown) in close contact with one surface of the membrane electrode assembly, and a second porous transport layer (not shown) in close contact with another surface of the membrane electrode assembly.

[0097] The membrane electrode assembly can be variously changed in structure and material according to the required conditions and design specifications. The present invention is not necessarily restricted or limited by the structure and material of the membrane electrode assembly.

[0098] For example, the membrane electrode assembly may be configured by attaching catalyst electrode layers (eg, an anode layer and a cathode layer) that generate an electrochemical reaction to two opposite surfaces of an electrolyte membrane.

[0099] The first porous transport layer and the second porous transport layer may uniformly distribute the reaction fluid, and each have a porous structure having pores of a set or predetermined size.

[0100] For reference, water supplied to the anode layer (which is an oxidation electrode for water electrolysis) can be separated into hydrogen ions (protons), electrons and oxygen. The hydrogen ions move to the cathode layer as a reduction electrode through the electrolyte membrane, and the electrons can move to the cathode through an external circuit. In addition, oxygen can be discharged through the anode outlet, and the hydrogen ions and electrons can be converted into hydrogen at the cathode.

[0101] The first bypass line 150 may be configured to allow the liquid reaction fluid separated by the first gas-liquid separator 130 to selectively flow to the downstream side of the water electrolysis stack 20 without passing through the water electrolysis stack 20 .

[0102] More specifically, one end of the first bypass pipeline 150 can be located on the upstream side of the water electrolysis stack 20 (for example, between the first gas-liquid separator and the inlet of the water electrolysis stack) and connected to the circulation pipeline 140, and the other end of the first bypass pipeline 150 can be located on the downstream side of the water electrolysis stack 20 (for example, between the outlet of the water electrolysis stack and the first gas-liquid separator) and connected to the circulation pipeline 140.

[0103] The first bypass line 150 may have various structures according to the required conditions and design specifications. The present invention is not necessarily restricted or limited by the structure and shape of the first bypass line 150. For example, the first bypass line 150 may have a shape that is approximately a straight line. According to another embodiment of the present invention, the first bypass line may have a curved shape or other shapes.

[0104] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a first circulation three-way valve 142 a provided in the circulation line 140 and connected to one end of the first bypass line 150 .

[0105] Any three-way valve that enables the liquid reaction fluid supplied from the first gas-liquid separator 130 to the water electrolysis stack 20 along the circulation pipeline 140 to selectively flow to the downstream side of the water electrolysis stack 20 can be used as the first circulation three-way valve 142a. The present invention is not necessarily restricted or limited by the type and structure of the first circulation three-way valve 142a.

[0106] For example, the first circulation three-way valve 142 a may have a structure that is the same as or similar to the structure of the filter three-way valve 126 described above.

[0107] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a first circulating ion sensor 142b, which is located at the upstream side of the water electrolysis stack 20, disposed in the circulation line 140, and configured to sense the ionic conductivity of the liquid reaction fluid.

[0108] Various ion sensors capable of sensing the ionic conductivity of the liquid reaction fluid may be used as the first circulating ion sensor 142b. The present invention is not necessarily restricted or limited by the type and structure of the first circulating ion sensor 142b.

[0109] Specifically, the movement route of the liquid reaction fluid may be controlled by controlling the first circulation three-way valve 142 a based on the sensing result from the first circulation ion sensor 142 b .

[0110] The first circulation three-way valve 142a may be configured to enable the liquid reaction fluid to selectively flow from the upstream side of the water electrolysis stack 20 to the downstream side of the water electrolysis stack 20 based on the sensing result from the first circulation ion sensor 142b.

[0111] For example, refer to Figure 2 When the ionic conductivity of the liquid reaction fluid sensed by the first circulation ion sensor 142b is higher than a preset reference ionic conductivity (for example, 1 μS / cm), the first circulation three-way valve 142a can be controlled so that the liquid reaction fluid separated by the first gas-liquid separator 130 can flow along the first bypass line 150 to the downstream side of the water electrolysis stack 20 without passing through the water electrolysis stack 20.

[0112] On the contrary, Figure 3 As shown, when the ionic conductivity of the liquid reaction fluid sensed by the first circulation ion sensor 142b is equal to or lower than a preset reference ionic conductivity (for example, 1 μS / cm), the first circulation three-way valve 142a can be controlled so that the liquid reaction fluid separated by the first gas-liquid separator 130 is supplied to the water electrolysis stack 20 instead of the first bypass line 150, and the liquid reaction fluid can be used as water supplied to the water electrolysis stack 20.

[0113] As described above, in the embodiment of the present invention, the liquid reaction fluid separated by the first gas-liquid separator 130 selectively flows to the downstream side of the water electrolysis stack 20 without passing through the water electrolysis stack 20. Therefore, by utilizing the embodiment of the present invention, it is possible to obtain the advantageous effects of ensuring the quality of the reaction fluid supplied to the water electrolysis stack 20, improving the reusability of the reaction fluid, and improving durability and stability.

[0114] When a low-quality reaction fluid (e.g., a liquid reaction fluid with a higher ionic conductivity) is supplied to the water electrolysis stack 20, the performance, durability and stability of the water electrolysis stack 20 may deteriorate. In an embodiment of the present invention, when the ionic conductivity of the liquid reaction fluid separated by the first gas-liquid separator 130 is higher than the reference ionic conductivity (e.g., 1 μS / cm), the liquid reaction fluid flows along the bypass line to the downstream side of the water electrolysis stack 20 without being supplied to the water electrolysis stack 20, and then the liquid reaction fluid is reprocessed (e.g., deionized). Therefore, using an embodiment of the present invention, the advantageous effects of ensuring the quality of the reaction fluid supplied to the water electrolysis stack 20, improving the reusability of the reaction fluid, and improving durability and stability can be obtained.

[0115] Among other things, according to an embodiment of the present invention, advantageous effects of extending the service life of the water electrolysis stack 20 and minimizing deterioration in durability and stability of the water electrolysis stack 20 caused when a low-quality reaction fluid is supplied to the water electrolysis stack 20 can be obtained.

[0116] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a circulation filter 144 , which is located between the first gas-liquid separator 130 and the inlet of the water electrolysis stack 20 , is disposed in the circulation line 140 , and is configured to filter the liquid reaction fluid.

[0117] Any ion filter that can filter out ions and foreign matter (impurities) contained in the liquid reaction fluid can be used as the circulation filter 144. The present invention is not necessarily restricted or limited by the type and nature of the ion filter. For example, ion exchange resins and the like can be used for the circulation filter 144.

[0118] As described above, in the embodiment of the present invention, the liquid reaction fluid recycled along the first bypass line 150 can be filtered again by the circulation filter 144 before being supplied to the water electrolysis stack 20. Therefore, by using the embodiment of the present invention, the advantageous effects of further improving the quality of the reaction fluid supplied to the water electrolysis stack 20 and further improving the durability and stability of the water electrolysis stack 20 can be obtained.

[0119] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a second bypass line 160, a second gas-liquid separator 180 and a recirculation line 190, wherein the second bypass line 160 is located on the downstream side of the water electrolysis stack 20 and is connected to the circulation line 140; the second gas-liquid separator 180 is connected to the second bypass line 160 and is configured to separate the bypass fluid flowing along the second bypass line 160 into a gaseous reaction fluid and a liquid reaction fluid; one end of the recirculation line 190 is connected to the second gas-liquid separator 180, and the other end is connected to the first gas-liquid separator 130, and the recirculation line 190 is configured to recirculate the liquid reaction fluid passing through the second gas-liquid separator 180 to the first gas-liquid separator 130.

[0120] The second bypass line 160 is configured to allow the bypass fluid passing through the water electrolysis stack 20 or the first bypass line 150 to selectively flow to the second gas-liquid separator 180 instead of directly circulating to the first gas-liquid separator 130 .

[0121] More specifically, one end of the second bypass line 160 can be located on the downstream side of the water electrolysis stack 20 (for example, between the outlet of the water electrolysis stack and the first gas-liquid separator) and connected to the circulation line 140, and the other end of the second bypass line 160 can be connected to the second gas-liquid separator 180 (for example, the lower end of the second gas-liquid separator).

[0122] The second bypass line 160 may have various structures according to the required conditions and design specifications. The present invention is not necessarily restricted or limited by the structure and shape of the second bypass line 160. For example, the second bypass line 160 may have a shape that is approximately straight. According to another embodiment of the present invention, the second bypass line may have a curved shape or other shapes.

[0123] The second gas-liquid separator 180 may be connected to the circulation line 140 and configured to separate the bypass fluid passing through the water electrolysis stack 20 or the first bypass line 150 into a gaseous reaction fluid and a liquid reaction fluid.

[0124] Various separation devices capable of separating the bypass fluid into a gaseous reaction fluid and a liquid reaction fluid may be used as the second gas-liquid separator 180. The present invention is not necessarily restricted or limited by the type and structure of the second gas-liquid separator 180.

[0125] For example, the second gas-liquid separator 180 may be provided in the form of a hollow tank. For example, the second bypass line 160 may be connected to the lower end of the second gas-liquid separator 180, and the recirculation line 190 may be connected to the near-center portion of the second gas-liquid separator 180. In addition, a liquid level sensor (not shown) may be provided in the second gas-liquid separator 180, and the liquid level sensor is configured to detect the liquid level of the liquid reaction fluid.

[0126] The recycling line 190 may be configured to recycle the liquid reaction fluid obtained by the gas-liquid separation performed by the second gas-liquid separator 180 to the first gas-liquid separator 130 .

[0127] More specifically, one end of the recycling line 190 can be connected to the second gas-liquid separator 180, and the other end of the recycling line 190 can be connected to the first gas-liquid separator 130, and the liquid reaction fluid passing through the second gas-liquid separator 180 can be recycled to the first gas-liquid separator 130 along the recycling line 190.

[0128] The recirculation line 190 may have various structures capable of connecting the second gas-liquid separator 180 and the first gas-liquid separator 130. The present invention is not necessarily restricted or limited by the structure and shape of the recirculation line 190.

[0129] For example, the inlet end of the recirculation line 190 may be connected to the side of the lower end of the second gas-liquid separator 180 , and the outlet end of the recirculation line 190 may be connected to the upper end of the first gas-liquid separator 130 .

[0130] Specifically, the inlet end of the recirculation line 190 may be connected to the second gas-liquid separator 180 such that the inlet end of the recirculation line 190 is located below the liquid level of the liquid reaction fluid separated by the second gas-liquid separator 180 .

[0131] In addition, the recirculation line 190 may be equipped with various types of accessory devices, for example, a pump (not shown) configured to force the liquid reaction fluid to move along the recirculation line 190 and a filter configured to filter the liquid reaction fluid. The present invention is not necessarily restricted or limited by the type of accessory device and the number of accessory devices.

[0132] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a second circulation three-way valve 146 a provided in the circulation line 140 and connected to one end of the second bypass line 160 .

[0133] Any three-way valve that allows the bypass fluid that has passed through the water electrolysis stack 20 or the first bypass line 150 to selectively flow along the second bypass line 160 to the second gas-liquid separator 180 can be used as the second circulation three-way valve 146a. The present invention is not necessarily restricted or limited by the type and structure of the second circulation three-way valve 146a.

[0134] For example, the second circulation three-way valve 146 a may have a structure that is the same as or similar to the structure of the filter three-way valve 126 described above.

[0135] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a second circulating ion sensor 146b, which is located at the downstream side of the water electrolysis stack 20, disposed in the circulation line 140, and configured to sense the ionic conductivity of the liquid reaction fluid.

[0136] Various ion sensors capable of sensing the ionic conductivity of the liquid reaction fluid may be used as the second circulating ion sensor 146b. The present invention is not necessarily restricted or limited by the type and structure of the second circulating ion sensor 146b.

[0137] Specifically, the movement route of the liquid reaction fluid may be controlled by controlling the second circulation three-way valve 146 a based on the sensing result from the second circulation ion sensor 146 b .

[0138] The second circulation three-way valve 146 a may be configured to enable the bypass fluid to selectively flow from the circulation line 140 to the second bypass line 160 based on the sensing result from the second circulation ion sensor 146 b .

[0139] For example, refer to Figure 2 and Figure 3 When the ionic conductivity of the liquid reaction fluid sensed by the second circulating ion sensor 146b is higher than a preset reference ionic conductivity (for example, 1 μS / cm), the second circulating three-way valve 146a can be controlled so that the bypass fluid passing through the water electrolysis stack 20 or the first bypass line 150 can flow along the second bypass line 160 to the second gas-liquid separator 180 instead of directly circulating to the first gas-liquid separator 130.

[0140] On the contrary, Figure 4 As shown, when the ionic conductivity of the liquid reaction fluid sensed by the second circulating ion sensor 146b is equal to or lower than a preset reference ionic conductivity (for example, 1 μS / cm), the second circulating three-way valve 146a can be controlled so that the bypass fluid passing through the water electrolysis stack 20 or the first bypass line 150 can be supplied to the first gas-liquid separator 130 instead of the second gas-liquid separator 180.

[0141] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a third bypass line 170 configured to allow the liquid reaction fluid passing through the second gas-liquid separator 180 to selectively flow back to the second gas-liquid separator 180 without being directly recycled to the first gas-liquid separator 130.

[0142] More specifically, one end of the third bypass line 170 can be located on the downstream side of the second gas-liquid separator 180 (for example, between the inlet end of the recirculation line and the first gas-liquid separator) and connected to the recirculation line 190, and the other end of the third bypass line 170 can be connected to the second gas-liquid separator 180 (for example, the upper end of the second gas-liquid separator).

[0143] The third bypass line 170 may have various structures according to the required conditions and design specifications. The present invention is not necessarily restricted or limited by the structure and shape of the third bypass line 170. For example, the third bypass line 170 may have a shape that is approximately a straight line. According to another embodiment of the present invention, the third bypass line may have a curved shape or other shapes.

[0144] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a recirculation three-way valve 192 that is disposed in the recirculation line 190 and connected to one end of the third bypass line 170 .

[0145] Various three-way valves capable of allowing the liquid reaction fluid supplied from the second gas-liquid separator 180 to the first gas-liquid separator 130 along the recirculation line 190 to selectively flow back to the second gas-liquid separator 180 may be used as the recirculation three-way valve 192. The present invention is not necessarily restricted or limited by the type and structure of the recirculation three-way valve 192.

[0146] For example, the recirculation three-way valve 192 may have a structure that is the same as or similar to the structure of the filter three-way valve 126 described above.

[0147] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include a recirculating ion sensor 194 disposed in the recirculating line 190 and configured to sense the ionic conductivity of the liquid reaction fluid.

[0148] Any ion sensor capable of sensing the ionic conductivity of the liquid reactive fluid may be used as the recirculating ion sensor 194. The present invention is not necessarily restricted or limited by the type and structure of the recirculating ion sensor 194.

[0149] Specifically, the movement route of the liquid reaction fluid may be controlled by controlling the recycling three-way valve 192 based on the sensing result from the recycling ion sensor 194 .

[0150] The recirculation three-way valve 192 may be configured to enable the liquid reaction fluid to selectively flow from the recirculation line 190 to the third bypass line 170 (second gas-liquid separator) based on the sensing result from the recirculation ion sensor 194 .

[0151] For example, refer to Figure 2When the ionic conductivity of the liquid reaction fluid sensed by the recycling ion sensor 194 is higher than a preset reference ionic conductivity (for example, 1 μS / cm), the recycling three-way valve 192 can be controlled so that the liquid reaction fluid separated by the second gas-liquid separator 180 can flow back to the second gas-liquid separator 180 via the third bypass line 170.

[0152] On the contrary, when the ionic conductivity of the liquid reaction fluid sensed by the recycling ion sensor 194 is equal to or lower than a preset reference ionic conductivity (e.g., 1 μS / cm), the recycling three-way valve 192 can be controlled so that the liquid reaction fluid separated by the second gas-liquid separator 180 can be supplied to the first gas-liquid separator 130 instead of the third bypass line 170.

[0153] refer to Figure 1 and Figures 7 and 8 According to an exemplary embodiment of the present invention, the electrochemical system 10 may include: a first cleaning pipeline 114, one end of which is connected to the storage part 112, and the other end is connected to the second gas-liquid separator 180, and the first cleaning pipeline 114 is configured to discharge the reaction fluid to the inner wall surface of the second gas-liquid separator 180.

[0154] The first cleaning line 114 may be configured to clean the inner wall surface of the second gas-liquid separator 180 by supplying the reaction fluid in the storage part 112 to the inner wall surface of the second gas-liquid separator 180 .

[0155] The first cleaning line 114 may have various structures capable of supplying the reaction fluid in the storage part 112 to the second gas-liquid separator 180. The present invention is not necessarily restricted or limited by the structure and shape of the first cleaning line 114.

[0156] According to an exemplary embodiment of the present invention, the first cleaning line 114 may include a nozzle 114 a capable of spraying the reaction fluid in the storage part 112 to the inner wall surface of the second gas-liquid separator 180 .

[0157] For example, refer to Figure 7 The nozzle 114a may be configured to be rotatable (eg, 90 to 360 degrees) in the second gas-liquid separator 180. The inner wall surface of the second gas-liquid separator 180 may be cleaned by the reaction fluid sprayed from the nozzle 114a (which rotates in the second gas-liquid separator 180).

[0158] As another example, refer to Figure 8, the nozzle 114a can be configured to spray the reaction fluid in a direction inclined relative to a reference line passing through the center of the second gas-liquid separator 180. The reaction fluid sprayed from the nozzle 114a can clean the inner wall surface of the second gas-liquid separator 180 when flowing downward in a vortex along the inner wall surface of the second gas-liquid separator 180. Among other things, in an embodiment of the present invention, the reaction fluid sprayed from the nozzle 114a can flow downward in a vortex. Therefore, using an embodiment of the present invention, the advantageous effect of minimizing the use amount of the reaction fluid used as washing water can be obtained.

[0159] Specifically, the nozzle 114a may be made of a stainless steel material having excellent corrosion resistance. Alternatively, the nozzle 114a may be made of a synthetic resin or other materials having excellent corrosion resistance.

[0160] According to an exemplary embodiment of the present invention, the electrochemical system 10 may include: a discharge line 182 connected to the second gas-liquid separator 180 and configured to discharge the liquid reaction fluid from the second gas-liquid separator 180 to the outside; a switch valve 184 configured to selectively open or close the discharge line 182; and an ion sensor 186 disposed in the second gas-liquid separator 180 and configured to sense the ionic conductivity of the liquid reaction fluid in the second gas-liquid separator 180. The switch valve 184 may selectively open the discharge line 182 based on the sensing result from the ion sensor 186.

[0161] The discharge line 182 may have various structures that enable the liquid reaction fluid to be discharged to the outside from the second gas-liquid separator 180. The present invention is not necessarily restricted or limited by the structure and shape of the discharge line 182. For example, the discharge line 182 may have an approximately straight line shape and be connected to the lower end of the second gas-liquid separator 180.

[0162] A typical valve (eg, a solenoid valve) capable of selectively opening or closing the discharge line 182 may be used as the switching valve 184. The present invention is not necessarily restricted or limited by the type and structure of the switching valve 184.

[0163] Various ion sensors capable of sensing the ionic conductivity of the liquid reaction fluid in the second gas-liquid separator 180 (similarly, capable of sensing the ionic conductivity in the storage portion 112) may be used as the ion sensor 186. The present invention is not restricted or limited by the type and structure of the ion sensor 186.

[0164] The opening / closing time point of the exhaust pipeline 182 (the time point when the liquid reaction fluid is discharged from the second gas-liquid separator 180, similarly, the time point when the liquid reaction fluid is discharged from the storage unit 112) can be controlled by controlling the switch valve 184 based on the sensing result from the ion sensor 186.

[0165] For example, when the ionic conductivity of the liquid reaction fluid sensed by the ion sensor 186 is higher than a preset reference ionic conductivity (e.g., 5 μS / cm), the switch valve 184 can be controlled to open the exhaust pipeline 182 so that the liquid reaction fluid can be discharged from the second gas-liquid separator 180 to the outside.

[0166] According to an exemplary embodiment of the present invention, the first cleaning line 114 can be configured as follows: when the liquid reaction fluid is discharged along the discharge line 182 for a preset discharge time (e.g., 10 minutes), the reaction fluid is supplied to the inner wall surface of the second gas-liquid separator 180 for a preset cleaning time (e.g., 3 minutes) with the discharge line 182 open.

[0167] As described above, in an embodiment of the present invention, the reaction fluid stored in the storage portion 112 can be used as washing water and sprayed to the inner wall surface of the second gas-liquid separator 180, thereby removing the contaminants remaining on the inner wall surface of the second gas-liquid separator 180. Therefore, using an embodiment of the present invention, it is possible to obtain the advantageous effect of minimizing the deterioration (e.g., contamination) of the characteristics of the liquid reaction fluid caused by the contaminants remaining on the inner wall surface of the second gas-liquid separator 180 and preventing the low-quality liquid reaction fluid containing the contaminants from being supplied to the water electrolysis stack 20.

[0168] Furthermore, in the embodiment of the present invention, in the case where the ion conductivity of the liquid reaction fluid in the second gas-liquid separator 180 is higher than the preset reference ion conductivity, the liquid reaction fluid can be discharged to the outside as it is through the discharge line 182. Therefore, with the embodiment of the present invention, it is possible to obtain an advantageous effect of minimizing the number of components and steps required for reprocessing (regenerating) the liquid reaction fluid.

[0169] refer to Fig. 9 According to an exemplary embodiment of the present invention, the electrochemical system 10 may include an outlet port 188 connected to the exhaust line 182 and disposed at the lower end of the second gas-liquid separator 180 based on the gravity direction. The outlet port 188 may have a cross-sectional area that gradually decreases downward from its upper side.

[0170] For example, the outlet port 188 may have an approximately conical shape in which the cross-sectional area gradually decreases downward from the upper side thereof.

[0171] As described above, in an embodiment of the present invention, the outlet port 188 may have a cross-sectional area that gradually decreases from its upper side downward. Therefore, using an embodiment of the present invention, it is possible to obtain the advantageous effect of ensuring that pollutants and liquid reaction fluid are smoothly discharged through the discharge line 182 and preventing pollutants from remaining at the bottom of the second gas-liquid separator 180.

[0172] refer to Figure 1 According to an exemplary embodiment of the present invention, the electrochemical system 10 may include: a second cleaning pipeline 116, one end of which is connected to the first cleaning pipeline 114 (branched from the first cleaning pipeline 114), and the other end is connected to the first gas-liquid separator 130, and the second cleaning pipeline 116 can be configured to supply the reaction fluid to the inner wall surface of the first gas-liquid separator 130.

[0173] The second cleaning line 116 may have various structures capable of supplying the reaction fluid in the storage part 112 to the first gas-liquid separator 130. The present invention is not necessarily restricted or limited by the structure and shape of the second cleaning line 116.

[0174] According to an exemplary embodiment of the present invention, the second cleaning line 116 may be configured to spray the reaction fluid from the storage part 112 to the inner wall surface of the first gas-liquid separator 130 in the same or similar manner as the first cleaning line 114 .

[0175] According to the embodiments of the present invention described above, advantageous effects of ensuring the performance of a water electrolysis stack and improving the durability and stability of the water electrolysis stack can be obtained.

[0176] Specifically, according to an embodiment of the present invention, a low-quality reaction fluid (e.g., a reaction fluid with higher ionic conductivity) can flow along a bypass line to a circulation line without being supplied to a water electrolysis stack, and then the low-quality reaction fluid can be reprocessed (e.g., deionized). Therefore, using an embodiment of the present invention, the advantageous effects of ensuring the quality of the reaction fluid supplied to the water electrolysis stack, improving the reusability of the reaction fluid, and improving durability and stability can be obtained.

[0177] According to the embodiments of the present invention, among other things, advantageous effects of extending the service life of a water electrolysis stack and minimizing deterioration in durability and stability of the water electrolysis stack caused when a low-quality reaction fluid is supplied to the water electrolysis stack can be obtained.

[0178] Furthermore, according to the embodiment of the present invention, it is possible to obtain the advantageous effects of continuously supplying the reaction fluid to the water electrolysis stack without stopping the operation of the system when replacing the filter and preventing the reaction fluid of low quality from being supplied to the water electrolysis stack.

[0179] Furthermore, according to the embodiment of the present invention, it is possible to obtain an advantageous effect of preventing the pollutants remaining on the inner wall surface of the gas-liquid separator from being supplied to the water electrolysis stack.

[0180] Although the embodiments are described above, the embodiments are only illustrative and are not intended to necessarily limit the present invention. It will be appreciated by those skilled in the art that various modifications and applications not described above can be made to the present embodiment without departing from the essential features of the present embodiment. For example, each constituent element specifically described in the embodiments can be modified and then implemented. In addition, the differences associated with modifications and applications can be included within the scope of the present invention as defined in the appended claims.

Claims

1. An electrochemical system comprising: a reaction fluid supply line configured to supply a reaction fluid; a first gas-liquid separator connected to the reaction fluid supply pipeline and configured to separate the reaction fluid into a gaseous reaction fluid and a liquid reaction fluid; a circulation line connected to the first gas-liquid separator and configured to allow a liquid reaction fluid to circulate through the circulation line; A water electrolysis stack is arranged in a circulation pipeline; as well as A first bypass line, wherein a first end of the first bypass line is located at an upstream side of the water electrolysis stack and connected to a circulation line, and a second end of the first bypass line is located at a downstream side of the water electrolysis stack and connected to the circulation line. 2 . The electrochemical system according to claim 1 , further comprising a first circulation three-way valve disposed in the circulation line and connected to a first end of the first bypass line.

3. The electrochemical system according to claim 2 further comprises a first circulating ion sensor, which is located on the upstream side of the water electrolysis stack, arranged in the circulation pipeline, and configured to sense the ionic conductivity of the liquid reaction fluid; wherein the first circulating three-way valve is configured to enable the liquid reaction fluid to selectively flow from the upstream side of the water electrolysis stack to the downstream side of the water electrolysis stack based on the sensing results from the first circulating ion sensor.

4. The electrochemical system according to claim 1 further comprises a circulation filter, which is located between the first gas-liquid separator and the inlet of the water electrolysis stack, is arranged in the circulation pipeline, and is configured to filter the liquid reaction fluid.

5. An electrochemical system comprising: a reaction fluid supply line configured to supply a reaction fluid; a first gas-liquid separator connected to the reaction fluid supply pipeline and configured to separate the reaction fluid into a gaseous reaction fluid and a liquid reaction fluid; a circulation line connected to the first gas-liquid separator and configured to allow a liquid reaction fluid to circulate through the circulation line; A water electrolysis stack is arranged in a circulation pipeline; a first bypass line, wherein a first end of the first bypass line is located at an upstream side of the water electrolysis stack and connected to a circulation line, and a second end of the first bypass line is located at a downstream side of the water electrolysis stack and connected to the circulation line; as well as The filter section is disposed in the reaction fluid supply line and is configured to filter the reaction fluid.

6. The electrochemical system according to claim 5, wherein: The filter unit comprises: a first filter line connected to the reaction fluid supply line and equipped with a first filter; and A second filter line, which is connected in parallel with the first filter line, is connected to the reaction fluid supply line and is equipped with a second filter. 7 . The electrochemical system according to claim 6 , further comprising a filter three-way valve provided in the reaction fluid supply line and connected to one end of the first filter line and one end of the second filter line.

8. The electrochemical system according to claim 7, further comprising: a first filter ion sensor located on a downstream side of the first filter, disposed in the first filter line, and configured to sense ionic conductivity of the reaction fluid; and A second filter ion sensor is located on the downstream side of the second filter, is disposed in the second filter pipeline, and is configured to sense the ionic conductivity of the reaction fluid; wherein the filter three-way valve is configured to selectively switch the movement route of the reaction fluid to the first filter pipeline or the second filter pipeline based on the sensing results from the first filter ion sensor and the second filter ion sensor.

9. An electrochemical system comprising: a reaction fluid supply line configured to supply a reaction fluid; a first gas-liquid separator connected to the reaction fluid supply pipeline and configured to separate the reaction fluid into a gaseous reaction fluid and a liquid reaction fluid; a circulation line connected to the first gas-liquid separator and configured to allow a liquid reaction fluid to circulate through the circulation line; A water electrolysis stack is arranged in a circulation pipeline; a first bypass line, wherein a first end of the first bypass line is located at an upstream side of the water electrolysis stack and connected to a circulation line, and a second end of the first bypass line is located at a downstream side of the water electrolysis stack and connected to the circulation line; a second bypass line located at a downstream side of the water electrolysis stack and connected to the circulation line; a second gas-liquid separator connected to the second bypass line and configured to separate the bypass fluid flowing along the second bypass line into a gaseous reaction fluid and a liquid reaction fluid; as well as A recirculation line, wherein a first recirculation end of the recirculation line is connected to the second gas-liquid separator, a second recirculation end of the recirculation line is connected to the first gas-liquid separator, and the recirculation line is configured to recirculate the liquid reaction fluid passing through the second gas-liquid separator to the first gas-liquid separator. 10 . The electrochemical system according to claim 9 , further comprising a second circulation three-way valve disposed in the circulation line and connected to the first end of the second bypass line.

11. The electrochemical system according to claim 10 further comprises a second circulating ion sensor, which is located on the downstream side of the water electrolysis stack, arranged in the circulating pipeline, and configured to sense the ionic conductivity of the liquid reaction fluid; wherein the second circulating three-way valve is configured to enable the bypass fluid to selectively flow from the circulating pipeline to the second bypass pipeline based on the sensing result from the second circulating ion sensor. 12 . The electrochemical system according to claim 9 , further comprising a third bypass line, a first end of the third bypass line being connected to the recirculation line, and a second end of the third bypass line being connected to the second gas-liquid separator. 13 . The electrochemical system according to claim 12 , further comprising a recirculation three-way valve provided in the recirculation line and connected to the third bypass line.

14. The electrochemical system of claim 13 , comprising a recycling ion sensor disposed in the recycling line and configured to sense the ionic conductivity of the liquid reaction fluid; wherein the recycling three-way valve is configured to allow the liquid reaction fluid to selectively flow from the recycling line to the third bypass line based on the sensing result from the recycling ion sensor. 15 . The electrochemical system according to claim 9 , further comprising a storage portion located on an upstream side of the first gas-liquid separator, provided in the reaction fluid supply line, and configured to store the reaction fluid.

16. The electrochemical system according to claim 15 further comprises a first cleaning line, wherein a first cleaning line end of the first cleaning line is connected to a storage portion, a second cleaning line end of the first cleaning line is connected to a second gas-liquid separator, and the first cleaning line is configured to supply the reaction fluid to the inner wall surface of the second gas-liquid separator.

17. The electrochemical system of claim 16, further comprising: an exhaust line connected to the second gas-liquid separator and configured to exhaust the liquid reaction fluid from the second gas-liquid separator to the outside; a switching valve configured to selectively open or close the discharge line; and An ion sensor is disposed in the second gas-liquid separator and is configured to sense the ionic conductivity of the liquid reaction fluid in the second gas-liquid separator; wherein the switch valve is configured to selectively open the exhaust pipeline based on the sensing result from the ion sensor.

18. The electrochemical system according to claim 17, wherein: The first cleaning line is configured to supply the reaction fluid to the inner wall surface of the second gas-liquid separator for a preset cleaning time.

19. The electrochemical system according to claim 17, further comprising an outlet port connected to the exhaust line and arranged at a lower end of the second gas-liquid separator based on the gravity direction; wherein the outlet port has a cross-sectional area gradually decreasing downward from its upper side.

20. The electrochemical system according to claim 16 further comprises a second cleaning line, a first end of the second cleaning line is connected to the first cleaning line, a second end of the second cleaning line is connected to the first gas-liquid separator, and the second cleaning line is configured to supply the reaction fluid to the inner wall surface of the first gas-liquid separator.

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