Multistage electrochemical hydrogen compressor and control method thereof

Abstract

A multistage electrochemical hydrogen compressor according to an embodiment of the present invention may include: a stack for compressing hydrogen; and a current supply unit for applying a current to the stack, wherein the stack includes: a low-pressure end plate having an inlet through which low-pressure hydrogen is introduced; a high-pressure end plate having an outlet for discharging high-pressure hydrogen acquired by compressing the low-pressure hydrogen; a plurality of cells disposed between the low-pressure end plate and the high-pressure end plate; and a membrane-electrode assembly each disposed between the plurality of cells, and the current supply unit is connected to each of the plurality of cells to selectively control current application to the plurality of cells.

Description

Multistage electrochemical hydrogen compressor and its control method

[0001] The present invention relates to a multi-stage electrochemical hydrogen compressor and a control method thereof, and more particularly, to a multi-stage electrochemical hydrogen compressor capable of compressing hydrogen in stages by arranging a plurality of membrane-electrode assemblies in multiple stages in a single stack, and a control method thereof.

[0002] Recently, hydrogen fuel cell vehicles have been in the spotlight thanks to the Green New Deal policy, which aims to transition from fossil fuel-centered energy policies to renewable energy and a low-carbon economic structure.

[0003] Hydrogen fuel cell vehicles are eco-friendly vehicles that operate by using electricity generated by reacting hydrogen with oxygen in the air instead of a gasoline internal combustion engine. Since they do not have an engine, they do not emit exhaust fumes or other pollutants.

[0004] Various methods have been proposed to obtain this hydrogen fuel, including alkaline water electrolysis, which produces hydrogen from pure water using electrical energy, polymer electrolyte membrane (PEM) water electrolysis, and high-temperature steam electrolysis using solid oxides.

[0005] Alkaline electrolysis technology uses an alkaline aqueous solution such as potassium hydroxide (KOH) as an electrolyte and a membrane to separate hydrogen and oxygen, and has an operating condition of 100℃ or lower.

[0006] Polymer electrolyte membrane (PEM) electrolysis technology is a technology that uses a polymer electrolyte membrane (PEM) as an electrolyte and a separator, and has an operating condition of 200℃ or lower depending on the stability of the polymer membrane.

[0007] Conventional electrochemical hydrogen compressors have a problem in that a large pressure difference occurs on both sides of the hydrogen ion conductive membrane as hydrogen is compressed, and the hydrogen ion conductive membrane is damaged and destroyed due to the pressure difference.

[0008] In addition, conventional electrochemical hydrogen compressors have a problem in that they have limitations in capacity and flow rate because hydrogen is compressed to high pressure while moving across a single hydrogen ion conducting membrane placed on a separator.

[0009] Therefore, in order to increase the capacity of an electrochemical hydrogen compressor, the capacity can be increased by stacking multiple separators, but there is a problem that multiple separators are required, and the low-pressure hydrogen supplied is individually supplied to each separator, and after the same electrochemical reaction occurs in each separator, the compressed high-pressure hydrogen is collected and discharged, which complicates the entire device and increases the device cost.

[0010] The present invention provides a multi-stage electrochemical hydrogen compressor and a control method thereof, which can compress hydrogen into high-pressure hydrogen by selectively controlling the application of current to each cell on the stack separated by the membrane-electrode assembly by arranging a plurality of membrane-electrode assemblies in multiple stages on a single stack.

[0011] According to one embodiment of the present invention, a multi-stage electrochemical hydrogen compressor comprises: a stack for compressing hydrogen; and a current supply unit for applying current to the stack; wherein the stack comprises: a low-pressure end plate having an inlet for introducing low-pressure hydrogen; a high-pressure end plate having an outlet for discharging high-pressure hydrogen in which the low-pressure hydrogen is compressed; a plurality of cells arranged between the low-pressure end plate and the high-pressure end plate; and a membrane-electrode assembly respectively arranged between the plurality of cells; wherein the current supply unit is connected to each of the plurality of cells and can selectively control the application of current to the plurality of cells.

[0012] As described above, according to the present invention, a plurality of membrane-electrode assemblies are arranged in multiple stages on a single stack to stepwise compress low-pressure hydrogen to produce high-pressure hydrogen, and the same current is selectively applied to each cell on the stack separated by the membrane-electrode assemblies, but the hydrogen in each cell is controlled to have different pressures, thereby improving the hydrogen compression efficiency and increasing the capacity and flow rate of hydrogen.

[0013] FIG. 1 is a drawing illustrating the structure of a multi-stage electrochemical hydrogen compressor according to a first embodiment of the present invention.

[0014] FIG. 2 is a drawing illustrating a control method for controlling the pressure of hydrogen through a multi-stage electrochemical hydrogen compressor according to the first embodiment of the present invention.

[0015] FIG. 3 is a drawing illustrating a modified example of a multi-stage electrochemical hydrogen compressor according to the first embodiment of the present invention.

[0016] FIG. 4 is a drawing showing another modified example of a multi-stage electrochemical hydrogen compressor according to the first embodiment of the present invention.

[0017] FIG. 5 is a drawing illustrating the structure of a multi-stage electrochemical hydrogen compressor according to a second embodiment of the present invention.

[0018] FIG. 6 is a diagram illustrating a control method for controlling the pressure of hydrogen through a multi-stage electrochemical hydrogen compressor according to a second embodiment of the present invention.

[0019] According to one embodiment of the present invention, a multi-stage electrochemical hydrogen compressor comprises: a stack for compressing hydrogen; and a current supply unit for applying current to the stack; wherein the stack comprises: a low-pressure end plate having an inlet for introducing low-pressure hydrogen; a high-pressure end plate having an outlet for discharging high-pressure hydrogen in which the low-pressure hydrogen is compressed; a plurality of cells arranged between the low-pressure end plate and the high-pressure end plate; and a membrane-electrode assembly respectively arranged between the plurality of cells; wherein the current supply unit is connected to each of the plurality of cells and can selectively control the application of current to the plurality of cells.

[0020] In this embodiment, hydrogen ions pass through the membrane-electrode assembly and the hydrogen can be compressed step by step.

[0021] In the present embodiment, a pipe connecting one of the plurality of cells to another adjacent cell may be further included.

[0022] In this embodiment, the pipe may include an openable valve.

[0023] In this embodiment, the current supply unit can apply the same current to the plurality of cells.

[0024] In this embodiment, the low-pressure end plate and the high-pressure end plate may be repeatedly provided at a constant interval relative to the movement path of the hydrogen.

[0025] In the present embodiment, each of the plurality of cells may include ribs extending in one direction and in contact with the membrane-electrode assembly, and channels extending in the one direction between the ribs.

[0026] In this embodiment, hydrogen ions can move through the ribs.

[0027] In this embodiment, the membrane-electrode assembly may be arranged in series in two or more stages spaced apart at a constant interval in the longitudinal direction of the channel.

[0028] According to another embodiment of the present invention, a control method of a multi-stage electrochemical hydrogen compressor comprises a plurality of cells and a membrane-electrode assembly disposed between the plurality of cells, the control method comprising: a step of supplying low-pressure hydrogen to a first cell among the plurality of cells; a first movement step of moving the hydrogen supplied to the first cell to a second cell positioned above the first cell; a second movement step of moving the hydrogen supplied to the second cell to a third cell positioned above the second cell; a first compression step of moving hydrogen from the second cell to the third cell through the membrane-electrode assembly between the second cell and the third cell to increase the hydrogen pressure of the third cell; a second compression step of moving hydrogen from the first cell to the second cell through the membrane-electrode assembly between the first cell and the second cell to increase the hydrogen pressure of the second cell such that the hydrogen pressure of the second cell becomes equal to the hydrogen pressure of the third cell; and a third compression step of moving hydrogen from the second cell to the third cell through a membrane-electrode assembly between the second cell and the third cell to increase the hydrogen pressure of the third cell so that the hydrogen pressure of the third cell becomes greater than the hydrogen pressure of the second cell.

[0029] In the present embodiment, in the first movement step, by applying current only to the second cell, hydrogen from the first cell can be moved to the second cell until the hydrogen pressure of the first cell and the hydrogen pressure of the second cell become equal.

[0030] In the present embodiment, in the second movement step, by applying current only to the third cell, hydrogen from the second cell can be moved to the third cell until the hydrogen pressure of the second cell becomes equal to the hydrogen pressure of the third cell.

[0031] In the present embodiment, in the second compression step, current may be applied only to the second cell to compress it until the hydrogen pressure of the second cell becomes equal to the hydrogen pressure of the third cell.

[0032] In the present embodiment, in the third compression step, current may be applied only to the third cell to compress it so that the hydrogen pressure of the third cell becomes higher than the hydrogen pressure of the second cell.

[0033] In the present embodiment, in the first movement step, hydrogen supplied to the first cell may be moved to the second cell through a first connecting pipe connecting the first cell and the second cell, and in the first movement step, hydrogen supplied to the second cell may be moved to the third cell through a second connecting pipe connecting the second cell and the third cell.

[0034] In the present embodiment, in the first movement step, hydrogen from the first cell can be moved to the second cell through the first connecting pipe until the hydrogen pressure of the first cell and the hydrogen pressure of the second cell become equal.

[0035] In the present embodiment, in the second movement step, hydrogen from the second cell can be moved to the third cell through the second connecting pipe until the hydrogen pressure of the second cell and the hydrogen pressure of the third cell become equal.

[0036] In the present embodiment, in the first compression step, the valve of the first connecting pipe is closed, the valve of the second connecting pipe is opened, and then current is supplied only to the second cell to compress hydrogen, and the hydrogen compressed in the second cell can be moved to the third cell through the second connecting pipe.

[0037] In the present embodiment, in the second compression step, each valve of the first connecting pipe connecting the first cell and the second cell and the second connecting pipe connecting the second cell and the third cell is closed, and then current is supplied only to the third cell to compress hydrogen.

[0038] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0039] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In the present invention, it should be understood that the terms "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0040] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Please note that, where possible, identical components are represented by identical reference numerals throughout the drawings. Furthermore, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted.

[0041] Hereinafter, a multi-stage electrochemical hydrogen compressor according to a first embodiment of the present invention will be described.

[0042] FIG. 1 is a diagram illustrating the structure of a multi-stage electrochemical hydrogen compressor according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating a control method for controlling the pressure of hydrogen through a multi-stage electrochemical hydrogen compressor according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating a modified example of the multi-stage electrochemical hydrogen compressor according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating another modified example of the multi-stage electrochemical hydrogen compressor according to the first embodiment of the present invention.

[0043] Referring to FIG. 1, a multi-stage electrochemical hydrogen compressor (1a) according to a first embodiment of the present invention is a hydrogen compressor that compresses hydrogen in an electrochemical manner, and may include a stack (10) that compresses hydrogen and a current supply unit (70) that applies current to the stack (10).

[0044] The stack (10) may have a plurality of channels (C) formed to provide a path for hydrogen to move. For example, the stack (10) may be a single stack.

[0045] The stack (10) may include a low-pressure end plate (30) having an inlet (30a) for introducing low-pressure hydrogen, a high-pressure end plate (50) having an outlet (50a) for discharging high-pressure hydrogen in which low-pressure hydrogen is compressed, a plurality of cells (11, 12, 13) arranged between the low-pressure end plate (30) and the high-pressure end plate (50), and membrane-electrode assemblies (21, 23) arranged between the plurality of cells (11, 12, 13), respectively.

[0046] A low-pressure end plate (30) is provided on one side of the stack (10) to supply low-pressure hydrogen supplied from the outside into the stack (10). To this end, the low-pressure end plate (30) may include an inlet (30a) for introducing low-pressure hydrogen into the stack (10).

[0047] A high-pressure end plate (50) is provided on the other side of the stack (10) to discharge high-pressure gas generated within the stack (10) to the outside. To this end, the high-pressure end plate (50) may include a discharge port (50a) for discharging high-pressure hydrogen to the outside.

[0048] At least one membrane-electrode assembly (20) is arranged on the hydrogen movement path formed on the channel (C) of the stack (10) so that hydrogen decomposed and ionized can move.

[0049] The membrane electrode assembly (20) can be arranged in series in two or more stages at a constant interval in the longitudinal direction of the channel (C) formed on the stack (10).

[0050] The membrane-electrode assembly (20) may be composed of an anode electrode and a cathode electrode, which are catalytic electrodes formed by applying a platinum catalyst to one side and the other side of the hydrogen ion conductive membrane that moves hydrogen ions.

[0051] The anode and cathode electrodes may include a platinum-based catalyst, iridium oxide, or ruthenium.

[0052] Hydrogen can be ionized by an oxidation reaction at the anode electrode, the ionized hydrogen ions can be moved through a hydrogen ion conducting membrane, and then the hydrogen can be compressed by a reduction reaction at the cathode electrode with electrons transmitted through a current supply unit (70), thereby generating high-pressure hydrogen.

[0053] The electrochemical hydrogen compressor uses the following hydrogen decomposition process:

[0054] H2(low pressure) → 2H+ + 2e-

[0055] Low-pressure hydrogen (H2) is supplied to the anode electrode, and the low-pressure hydrogen supplied to the anode electrode is decomposed into 2H+ + 2e-.

[0056] The hydrogen compression process at the cathode electrode after moving the hydrogen ion conducting membrane is as follows.

[0057] 2H+ + 2e- → H2 (high pressure)

[0058] The decomposed H+ passes through the ion conducting membrane and is transferred to the cathode electrode, and e- is transferred to the cathode electrode through the external conductor, where H+ and e- combine again to generate high-pressure hydrogen.

[0059] Therefore, the hydrogen ion conducting membrane is located between the anode and cathode electrodes and forms a path for compressed pumping of hydrogen gas. The hydrogen ion conducting membrane blocks the passage of hydrogen gas while allowing hydrogen ions to pass through.

[0060] The hydrogen ion conducting membrane can be made of, for example, Nafion. Nafion is a DuPont trademark for a polymer with a polytetrafluoroethylene backbone and sulfonic acid groups. It is thermally stable and has high chemical resistance.

[0061] In this embodiment, the low-pressure end plate (30) is provided at the bottom of the stack (10) and the high-pressure end plate (50) is provided at the top, but this is not limited to this and various changes may be made.

[0062] Meanwhile, in the present embodiment, a plurality of membrane-electrode assemblies (20) may be arranged on a stack (10), and may include a first membrane-electrode assembly (21) adjacent to a low-pressure end plate (30) and a second membrane-electrode assembly (23) adjacent to a high-pressure end plate (50).

[0063] Accordingly, a first cell (11) may be formed between the low-pressure end plate (30) and the first membrane-electrode assembly (21), a second cell (12) may be formed between the first membrane-electrode assembly (21) and the second membrane-electrode assembly (23), and a third cell (13) may be formed between the second membrane-electrode assembly (23) and the high-pressure end plate (50).

[0064] Specifically, each of the plurality of cells (11, 12, 13) may include ribs (L) extending in one direction and channels (C) extending in one direction between the ribs (L) in contact with the membrane-electrode assembly (20). The channels (C) serve as a path for hydrogen movement, through which hydrogen can be ionized. Hydrogen ions can pass through the membrane-electrode assembly (20) via the ribs (L).

[0065] The current supply unit (70) can be electrically connected to each cell (11, 12, 13) separated by a membrane-electrode assembly (20) on the stack (10). Specifically, the current supply unit (70) can be electrically connected to each of the first to third cells (11, 12, 13) arranged on the stack (10).

[0066] The current supply unit (70) can apply current to each cell (11, 12, 13) to transfer electrons decomposed from hydrogen ions by an oxidation reaction to each cell (11, 12, 13).

[0067] The current supply unit (70) can selectively control the current application to each cell (11, 12, 13). In addition, the current supply unit (70) can apply the same current to each cell (11, 12, 13). That is, since the hydrogen supplied and the hydrogen compressed at high pressure must be the same in one single stack (10), the same current must be applied to each cell (11, 12, 13) where the hydrogen is compressed at high pressure. Accordingly, the current supply unit (70) must selectively control the current application to each cell (11, 12, 13), and at this time, the current applied to each cell (11, 12, 13) must all have the same magnitude.

[0068] In this way, low-pressure hydrogen supplied into the stack (10) through the inlet (30a) of the low-pressure end plate (30) can be sequentially moved through the membrane-electrode assemblies (20) arranged in multiple positions on the stack (10) and pressurized in stages to be generated as high-pressure hydrogen.

[0069] In the present embodiment, the membrane-electrode assembly (20) disposed on the stack (10) is formed in two stages and is divided into a first cell (11), a second cell (12), and a third cell (13) with the membrane-electrode assembly (20) interposed therebetween. However, as illustrated in FIG. 3, the membrane-electrode assembly (20) disposed on the stack (10) of the multi-stage electrochemical hydrogen compressor (1b) may be formed in three or more stages, and thus may be divided into a plurality of cells (11, 12, 13, 14) with the membrane-electrode assembly (20) interposed therebetween. At this time, the length of the stack (10) may be varied or the arrangement interval of the membrane-electrode assemblies (20) may be flexibly varied depending on the arrangement of the membrane-electrode assemblies (20).

[0070] Even at this time, a current supply (70) is connected to each cell (11, 12, 13, 14) formed in the stack (10) so that current can be selectively applied.

[0071] In addition, as illustrated in FIG. 4, a multi-stage electrochemical hydrogen compressor (1c) can increase the hydrogen capacity within the stack (10) by repeatedly providing a plurality of low-pressure end plates (31, 33) and high-pressure end plates (51, 53) spaced at regular intervals along the hydrogen movement path on the stack (10).

[0072] Accordingly, low-pressure hydrogen is supplied to each inlet (31a, 33a) of a plurality of low-pressure end plates (31, 33), the supplied low-pressure hydrogen is repeatedly compressed into high-pressure hydrogen while sequentially moving through a plurality of membrane-electrode assemblies (20), and finally, the compressed high-pressure hydrogen can be discharged through each outlet (51a, 53a) formed in a plurality of high-pressure end plates (51, 53).

[0073] Specifically, a first low-pressure end plate (31) and a first high-pressure end plate (51) are provided on the stack (10), and a plurality of membrane-electrode assemblies (21, 23) are arranged between the first low-pressure end plate (31) and the first high-pressure end plate (51), and a second low-pressure end plate (33) and a second high-pressure end plate (53) are provided on the upper portion of the first high-pressure end plate (51), and a plurality of membrane-electrode assemblies (21, 23) are arranged between the second low-pressure end plate (33) and the second high-pressure end plate (53), and so on. After the low-pressure end plate (30) and the high-pressure end plate (50) and the plurality of membrane-electrode assemblies (21, 23) are repeatedly arranged and stacked in the form of units on the stack (10), high-pressure hydrogen is generated through each unit, thereby increasing the capacity of hydrogen.

[0074] Here, among a plurality of low-pressure end plates (31, 33), a second low-pressure end plate (33) and among a plurality of high-pressure end plates (51, 53), a first high-pressure end plate (51) are formed on the same layer on the stack (10), and the second low-pressure end plate (33) and the first high-pressure end plate (51) are spatially separated by a partition wall (not shown), so that low-pressure hydrogen supplied through the first low-pressure end plate (31) is compressed to high pressure while moving stepwise through the plurality of membrane-electrode assemblies (20), and then discharged through the first high-pressure end plate (51), and low-pressure hydrogen supplied through the second low-pressure end plate (33) is compressed to high pressure while moving stepwise through the plurality of membrane-electrode assemblies (20), and then discharged through the second high-pressure end plate (53).

[0075] In addition, it is possible for the second low-pressure end plate (33) and the first high-pressure end plate (51) to be formed in different layers on the stack (10), so that the low-pressure hydrogen supplied through each low-pressure end plate (31, 33) is compressed and then discharged through each high-pressure end plate (51, 53), and various other changes can be made.

[0076] Even at this time, a current supply (70) is connected to each cell (11, 12, 13, 14) that is repeatedly formed in a unit shape in the stack (10) so that current can be selectively applied.

[0077] Meanwhile, the multi-stage electrochemical hydrogen compressor (1a) according to the present embodiment may further include a control unit, and the control unit may control the application of current to each cell (11, 12, 13) and the amount of current applied, and may also control the supply amount of hydrogen supplied to the stack (10) through the inlet (30a) of the low-pressure end plate (30) and the discharge amount of hydrogen discharged through the outlet (50a) of the high-pressure end plate (50).

[0078] Meanwhile, a pressure detection sensor is provided in the cell to measure the hydrogen pressure of each cell (11, 12, 13), or the hydrogen pressure of each cell (11, 12, 13) can be measured through time, current, or voltage versus capacity of each cell (11, 12, 13), thereby determining the hydrogen pressure of each cell (11, 12, 13).

[0079] Hereinafter, a control method for controlling the pressure of hydrogen through a multi-stage electrochemical hydrogen compressor according to the first embodiment of the present invention will be described with reference to FIG. 2.

[0080] In the multi-stage electrochemical hydrogen compressor (1a) according to the present embodiment, in the initial state where no current is applied, the first cell (11), the second cell (12), and the third cell (13) formed by the first membrane-electrode assembly (21) and the second membrane-electrode assembly (23) are in an empty space state, so the pressures of each cell (11, 12, 13) may be different or a slight difference may occur in the pressure.

[0081] Specifically, the hydrogen pressure (P1) of the first cell (11) may be equal to the pressure of the gas flowing into the inlet (30a) of the low-pressure end plate (30), the hydrogen pressure (P2) of the second cell (12) may be equal to or less than the hydrogen pressure (P1) of the first cell (11), and the hydrogen pressure (P3) of the third cell (13) may be equal to or less than the hydrogen pressure (P1) of the first cell (11).

[0082] Accordingly, through the hydrogen compressor (1a) according to the present embodiment, the hydrogen pressure (P1) of the first cell (11) is the same as the pressure of the gas flowing into the inlet (30a) of the low-pressure end plate (30), the hydrogen pressure (P2) of the second cell (12) is greater than the hydrogen pressure (P1) of the first cell (11), and the hydrogen pressure (P3) of the third cell (13) is greater than the hydrogen pressure (P2) of the second cell (12), thereby generating high-pressure hydrogen.

[0083] First, in the initial state, no current is supplied to each cell (11, 12, 13) in the stack (10) through the current supply unit (70), and low-pressure hydrogen is supplied to the first cell (11) among each cell (11, 12, 13) separated by a plurality of membrane-electrode assemblies (21, 23) on the stack (10) through the inlet (30a) of the low-pressure end plate (30). At this time, the outlet (50a) of the high-pressure end plate (50) is closed (section A).

[0084] Next, a first movement step is performed to move the hydrogen supplied to the first cell (11) to the second cell (12) adjacent to the first cell (11) through the first membrane-electrode assembly (21) (section B).

[0085] At this time, by applying current to the second cell (12) through the current supply unit (70), hydrogen supplied to the first cell (11) moves to the second cell (12) as hydrogen ions through the first membrane separation assembly, and electrons decomposed from hydrogen are transferred to the second cell (12) through the current supply unit (70).

[0086] Here, hydrogen from the first cell (11) is moved to the second cell (12) until the hydrogen pressure (P2) of the second cell (12) and the hydrogen pressure (P1) of the first cell (11) become equal, but current is applied only to the second cell (12) to make the hydrogen pressure (P2) of the second cell (12) and the hydrogen pressure (P1) of the first cell (11) equal.

[0087] A second movement step is performed to move hydrogen supplied to the second cell (12) to the third cell (13) adjacent to the second cell (12) through the second membrane-electrode assembly (23) among the plurality of membrane-electrode assemblies (21, 23) (section C).

[0088] At this time, by applying current to the third cell (13) through the current supply unit (70), hydrogen supplied to the second cell (12) moves to the third cell (13) as hydrogen ions through the second membrane separation assembly, and electrons decomposed from hydrogen are transferred to the third cell (13) through the current supply unit (70).

[0089] Here, hydrogen from the second cell (12) is moved to the third cell (13) until the hydrogen pressure (P3) of the third cell (13) and the hydrogen pressure (P2) of the second cell (12) become equal, but current is applied only to the third cell (13) to make the hydrogen pressure (P3) of the third cell (13) and the hydrogen pressure (P2) of the second cell (12) equal.

[0090] That is, by performing the first movement step and the second movement step, hydrogen in the first and second cells (12) is moved to the second cell (12) and the third cell (13) until the hydrogen pressure (P1) of the first cell (11), the hydrogen pressure (P2) of the second cell (12), and the hydrogen pressure (P3) of the third cell (13) become equal.

[0091] At the same time, the hydrogen supplied to the first cell (11) is transferred to the second cell (12) through the first membrane-electrode assembly (21), and the hydrogen supplied to the second cell (12) is transferred to the third cell (13) through the second membrane-electrode assembly (23), a process that is continuously repeated.

[0092] At this time, a first compression step is performed to compress the hydrogen moved from the second cell (12) to the third cell (13) at high pressure to increase the hydrogen pressure (P3) of the third cell (13) (section D).

[0093] That is, when the hydrogen pressure (P3) of the third cell (13) and the hydrogen pressure (P2) of the second cell (12) are formed to be the same and current is continuously applied to the third cell (13), the hydrogen of the second cell (12) moves to the third cell (13), and the hydrogen pressure (P3) of the third cell (13) increases.

[0094] In this way, a second compression step is performed to increase the hydrogen pressure (P3) of the third cell (13) by applying current to the third cell (13), and then compress the hydrogen moved from the first cell (11) to the second cell (12) at high pressure to increase the hydrogen pressure (P2) of the second cell (12) (section E).

[0095] When current is applied only to the second cell (12) without applying current to the third cell (13), hydrogen from the first cell (11) moves to the second cell (12), increasing the hydrogen pressure (P2) of the second cell (12).

[0096] At this time, current is applied only to the second cell (12) to compress it until the hydrogen pressure (P2) of the second cell (12) becomes equal to the hydrogen pressure (P3) of the third cell (13).

[0097] Then, the hydrogen with increased hydrogen pressure (P2) in the second cell (12) is moved to the third cell (13) and compressed at high pressure to increase the hydrogen pressure (P3) of the third cell (13) in a third compression step (section F).

[0098] Here, current is applied only to the third cell (13) to compress the hydrogen pressure (P3) of the third cell (13) so that it becomes higher than the hydrogen pressure (P2) of the second cell (12).

[0099] Therefore, the hydrogen pressures of the first cell (11), the second cell (12), and the third cell (13) are in the order of P3 > P2 > P1 (section G).

[0100] By controlling the hydrogen pressure of each cell (11, 12, 13) in this way in stages, hydrogen can be compressed without high pressure being generated in multiple membrane-electrode assemblies (21, 23), thereby preventing damage and breakage of the membrane-electrode assemblies (21, 23).

[0101] Hereinafter, a multi-stage electrochemical hydrogen compressor according to a second embodiment of the present invention will be described.

[0102] FIG. 5 is a diagram illustrating the structure of a multi-stage electrochemical hydrogen compressor according to a second embodiment of the present invention. FIG. 6 is a diagram illustrating a control method for controlling the pressure of hydrogen through a multi-stage electrochemical hydrogen compressor according to a second embodiment of the present invention.

[0103] The multi-stage electrochemical hydrogen compressor according to the second embodiment of the present invention has the same structure as the multi-stage electrochemical hydrogen compressor according to the first embodiment described above, except for the connecting pipe, so a duplicate description of the same configuration will be omitted.

[0104] Referring to FIG. 5, a multi-stage electrochemical hydrogen compressor (1d) according to a second embodiment of the present invention may include at least one connecting pipe (80) connecting one cell (11, 12) formed on a stack (10) and another cell (12, 13) adjacent to the cell (11, 12).

[0105] Specifically, it may include a first connection pipe (81) that connects the first cell (11) and the second cell (12) formed on one side and the other side of the first membrane-electrode assembly (21), and a second connection pipe (83) that connects the second cell (12) and the third cell (13) formed on one side and the other side of the second membrane-electrode assembly (23).

[0106] Each connecting pipe (81, 83) connecting each cell (11, 12, 13) may be made of an insulating material and may be provided with a valve (not shown) that can be opened and closed inside.

[0107] By opening and closing the valve, hydrogen can be moved from each cell (11, 12) to another cell (12, 13) through each connecting pipe (81, 83), or the movement of hydrogen can be blocked.

[0108] Hereinafter, a control method for controlling the pressure of hydrogen through a multi-stage electrochemical hydrogen compressor according to a second embodiment of the present invention will be described with reference to FIG. 6.

[0109] The multi-stage electrochemical hydrogen compressor (1d) according to this embodiment can control the movement of hydrogen by controlling the opening and closing of the valve of the connecting pipe (80).

[0110] First, in the initial state, no current is supplied to each cell (11, 12, 13) in the stack (10) through the current supply unit (70), and low-pressure hydrogen is supplied to the first cell (11) among each cell (11, 12, 13) separated by a plurality of membrane-electrode assemblies (21, 23) on the stack (10) through the inlet (30a) of the low-pressure end plate (30) (section A). At this time, the outlet (50a) of the high-pressure end plate (50) is closed.

[0111] Next, a first movement step is performed to move the hydrogen supplied to the first cell (11) to the second cell (12) through the first connection pipe (81) connecting the first cell (11) and the second cell (12) adjacent to the first cell (11) among the plurality of connection pipes (80) (section B).

[0112] Here, hydrogen from the first cell (11) is moved to the second cell (12) through the first connecting pipe (81) until the hydrogen pressure (P1) of the first cell (11) and the hydrogen pressure (P2) of the second cell (12) become equal.

[0113] At this time, the valve (not shown) of the first connecting pipe (81) connecting the first cell (11) and the second cell (12) is controlled to be open.

[0114] A second movement step is performed to move the hydrogen supplied to the second cell (12) to the third cell (13) through the second connection pipe (83) connecting the second cell (12) and the third cell (13) adjacent to the second cell (12) among the plurality of connection pipes (80) (section C).

[0115] Here, hydrogen from the second cell (12) is moved to the third cell (13) through the second connecting pipe (83) until the hydrogen pressure (P2) of the second cell (12) and the hydrogen pressure (P3) of the third cell (13) become equal.

[0116] At this time, the valve (not shown) of the second connecting pipe (83) connecting the second cell (12) and the third cell (13) is controlled to be opened.

[0117] In this way, when hydrogen moves through the first connecting pipe (81) and the second connecting pipe (83), the application of current through the current supply unit (70) is stopped.

[0118] Next, a first compression step is performed to increase the hydrogen pressure (P2) of the second cell (12) by moving the hydrogen supplied to the first cell (11) through the first membrane-electrode assembly (21) among the plurality of membrane-electrode assemblies (20) to the second cell (12) and compressing it to high pressure (section D).

[0119] At this time, by applying current to the second cell (12) through the current supply unit (70), hydrogen supplied to the first cell (11) moves to the second cell (12) as hydrogen ions through the first membrane separation assembly (21), and electrons decomposed from hydrogen are transferred to the second cell (12) through the current supply unit (70).

[0120] Here, the valve of the first connecting pipe (81) connecting the first cell (11) and the second cell (12) is closed, and the valve of the second connecting pipe (83) connecting the second cell (12) and the third cell (13) is opened. Then, current is supplied only to the second cell (12) to compress hydrogen, and the compressed hydrogen in the second cell (12) is moved to the third cell (13) through the second connecting pipe (83) (section E).

[0121] That is, by applying current to the second cell (12), hydrogen moves from the first cell (11) to the second cell (12) through the membrane-electrode assembly (20), and the compressed hydrogen that has moved to the second cell (12) moves to the third cell (13) through the second connecting pipe (83).

[0122] Therefore, the hydrogen pressure (P2) of the second cell (12) and the hydrogen pressure (P3) of the third cell (13) can become the same.

[0123] A second compression step is performed to increase the hydrogen pressure (P3) of the third cell (13) by moving the hydrogen supplied to the second cell (12) through the second membrane-electrode assembly (23) among the plurality of membrane-electrode assemblies (20) to the third cell (13) and compressing it to high pressure (section F).

[0124] Even at this time, the hydrogen supplied to the first cell (11) is transferred to the second cell (12) through the first membrane-electrode assembly (21), and the hydrogen supplied to the second cell (12) is also transferred to the third cell (13) through the second membrane-electrode assembly (23), a process that is continuously repeated.

[0125] Then, by applying current to the third cell (13) through the current supply unit (70), hydrogen supplied to the second cell (12) moves to the third cell (13) as hydrogen ions through the second membrane separation assembly (23), and electrons decomposed from hydrogen are transferred to the third cell (13) through the current supply unit (70).

[0126] Here, each valve of the first connecting pipe (81) connecting the first cell (11) and the second cell (12) and the second connecting pipe (83) connecting the second cell (12) and the third cell (13) is closed, and then current is supplied only to the third cell (13) to compress hydrogen.

[0127] Accordingly, the hydrogen pressures of the first cell (11), the second cell (12), and the third cell (13) are formed differently, but the hydrogen pressure (P2) of the second cell (12) is greater than the hydrogen pressure (P1) of the first cell (11), and the hydrogen pressure (P3) of the third cell (13) is greater than the hydrogen pressure (P2) of the second cell (12) (section G).

[0128] Hydrogen compressed at high pressure in the third cell (13) is discharged through the discharge port (50a) of the high-pressure end plate (50).

[0129] Above, one embodiment of the present invention has been described, but a person having ordinary skill in the art will be able to modify and change the present invention in various ways by adding, changing, deleting or adding components, etc., within the scope that does not depart from the spirit of the present invention described in the claims, and this will also be considered to be included within the scope of the rights of the present invention.

Claims

1. A stack for compressing hydrogen; and A current supply unit for supplying current to the stack is included; The above stack is, A low pressure end plate having an inlet for introducing low pressure hydrogen; A high pressure end plate having an outlet for discharging high pressure hydrogen compressed from the low pressure hydrogen; a plurality of cells arranged between the low-pressure end plate and the high-pressure end plate; and A membrane-electrode assembly is disposed between each of the plurality of cells; A multi-stage electrochemical hydrogen compressor in which the current supply unit is connected to each of the plurality of cells and selectively controls the current supply to the plurality of cells.

2. In paragraph 1, A multi-stage electrochemical hydrogen compressor in which hydrogen ions pass through the membrane-electrode assembly and the hydrogen is compressed in stages.

3. In paragraph 1, A multi-stage electrochemical hydrogen compressor further comprising a pipe connecting one of the plurality of cells to another adjacent cell.

4. In paragraph 3, The above pipe is a multi-stage electrochemical hydrogen compressor including an openable valve.

5. In paragraph 1, The above current supply unit is a multi-stage electrochemical hydrogen compressor that applies the same current to the plurality of cells.

6. In paragraph 1, A multi-stage electrochemical hydrogen compressor in which the low-pressure end plate and the high-pressure end plate are repeatedly provided at a constant interval relative to the movement path of the hydrogen.

7. In paragraph 1, A multi-stage electrochemical hydrogen compressor, wherein each of the plurality of cells comprises ribs extending in one direction in contact with the membrane-electrode assembly and channels extending in the one direction between the ribs.

8. In paragraph 7, A multi-stage electrochemical hydrogen compressor in which hydrogen ions move through the above ribs.

9. In paragraph 7, The above membrane-electrode assembly is a multi-stage electrochemical hydrogen compressor in which two or more stages are arranged in series at regular intervals along the length of the channel.

10. A method for controlling a multi-stage electrochemical hydrogen compressor including a plurality of cells and a membrane-electrode assembly respectively disposed between the plurality of cells, A step of supplying low-pressure hydrogen to a first cell among the plurality of cells; A first movement step of moving hydrogen supplied to the first cell to a second cell located on the first cell; A second movement step of moving the hydrogen supplied to the second cell to a third cell located on the second cell; A first compression step for increasing the hydrogen pressure in the third cell by moving hydrogen from the second cell to the third cell through a membrane-electrode assembly between the second cell and the third cell; A second compression step for moving hydrogen from the first cell to the second cell through a membrane-electrode assembly between the first cell and the second cell to increase the hydrogen pressure of the second cell so that the hydrogen pressure of the second cell becomes equal to the hydrogen pressure of the third cell; and A control method for a multi-stage electrochemical hydrogen compressor, comprising: a third compression step for moving hydrogen from the second cell to the third cell through a membrane-electrode assembly between the second cell and the third cell to increase the hydrogen pressure of the third cell so that the hydrogen pressure of the third cell becomes greater than the hydrogen pressure of the second cell.

11. In paragraph 10, In the above first movement step, A control method for a multi-stage electrochemical hydrogen compressor that applies current only to the second cell to move hydrogen from the first cell to the second cell until the hydrogen pressure of the first cell and the hydrogen pressure of the second cell become equal.

12. In paragraph 10, In the second movement step, A control method for a multi-stage electrochemical hydrogen compressor that applies current only to the third cell to move hydrogen from the second cell to the third cell until the hydrogen pressure of the second cell becomes equal to the hydrogen pressure of the third cell.

13. In paragraph 10, In the second compression step, A control method for a multi-stage electrochemical hydrogen compressor that compresses hydrogen until the hydrogen pressure of the second cell becomes equal to the hydrogen pressure of the third cell by applying current only to the second cell.

14. In paragraph 10, In the third compression step, A control method for a multi-stage electrochemical hydrogen compressor that compresses hydrogen so that the hydrogen pressure of the third cell becomes higher than the hydrogen pressure of the second cell by applying current only to the third cell.

15. In paragraph 10, In the first moving step, the hydrogen supplied to the first cell is moved to the second cell through the first connecting pipe connecting the first cell and the second cell, A control method for a multi-stage electrochemical hydrogen compressor that moves hydrogen supplied to the second cell in the first movement step to the third cell through a second connecting pipe connecting the second cell and the third cell.

16. In paragraph 15, In the above first movement step, A control method for a multi-stage electrochemical hydrogen compressor that moves hydrogen from the first cell to the second cell through the first connecting pipe until the hydrogen pressure of the first cell and the hydrogen pressure of the second cell become equal.

17. In paragraph 15, In the second movement step, A control method for a multi-stage electrochemical hydrogen compressor that moves hydrogen from the second cell to the third cell through the second connecting pipe until the hydrogen pressure of the second cell and the hydrogen pressure of the third cell become equal.

18. In paragraph 15, In the above first compression step, The valve of the first connecting pipe is closed, the valve of the second connecting pipe is opened, and then current is supplied only to the second cell to compress hydrogen. A control method for a multi-stage electrochemical hydrogen compressor that moves compressed hydrogen in the second cell to the third cell through the second connecting pipe.

19. In paragraph 15, In the second compression step, A control method for a multi-stage electrochemical hydrogen compressor that compresses hydrogen by closing each valve of the first connecting pipe connecting the first cell and the second cell and the second connecting pipe connecting the second cell and the third cell and then supplying current only to the third cell.

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