Electrochemical hydrogen pump and control method thereof

Abstract

The electrochemical hydrogen pump disclosed in the present invention comprises a component and a voltage applicator, wherein the component includes an electrolyte membrane, an anode arranged on one main surface of the electrolyte membrane, and a cathode arranged on the other main surface of the electrolyte membrane, and the voltage applicator applies a voltage between the anode and the cathode. By applying the voltage by the voltage applicator, hydrogen in the hydrogen-containing gas supplied to the anode is moved to the cathode and its pressure is increased. The electrochemical hydrogen pump comprises a controller, and when at least one of the dew point of the hydrogen-containing gas supplied to the anode and the temperature of the component rises, the controller controls the applied voltage of the voltage applicator to increase the current flowing between the anode and the cathode.

Description

Technical Field

[0001] The present disclosure relates to an electrochemical hydrogen pump and a control method thereof. Background Art

[0002] In recent years, due to environmental issues such as global warming and energy issues such as the depletion of oil resources, hydrogen has attracted attention as a clean alternative energy source to replace fossil fuels. Even if hydrogen is burned, it basically only emits water, and does not emit carbon dioxide, which is the cause of global warming, and basically does not emit nitrogen oxides, etc., so it is expected to be used as a clean energy source. In addition, as a device that efficiently uses hydrogen as a fuel, there are fuel cells, and the development and popularization of them for automotive power sources and household private power generation are constantly advancing.

[0003] In the upcoming hydrogen society, in addition to hydrogen production, it is also required to develop technologies that can store hydrogen at high density and transport or utilize hydrogen in a small volume and at low cost. In particular, to promote the popularization of fuel cells as a distributed energy source, it is necessary to equip hydrogen supply facilities. In addition, in order to stably supply hydrogen, various studies are being conducted on the production, purification, and high-density storage of high-purity hydrogen.

[0004] For example, hydrogen gas, which is generally used as fuel gas in fuel cell vehicles, is compressed to several tens of MPa. Hydrogen gas is often generated from water by an electrochemical reaction using a water electrolysis device or the like.

[0005] In addition, for example, Patent Document 1 describes a hydrogen purification and pressure-boosting system, which provides an electrolyte membrane between the anode and the cathode, and purifies and boosts the hydrogen by applying a voltage between the anode and the cathode. Furthermore, the stacked structure of the anode, the electrolyte membrane, and the cathode is referred to as a membrane-electrode assembly (hereinafter sometimes referred to as MEA: Membrane Electrode Assembly). At this time, the hydrogen supplied to the anode may also be mixed with impurities. For example, the hydrogen may be hydrogen gas generated as a by-product from an iron and steel plant, etc., or it may be a modified gas after modifying city gas.

[0006] Prior art literature

[0007] Patent Document 1: Japanese Patent No. 6299027 Summary of the invention

[0008] An object of the present disclosure is to provide, as an example, an electrochemical hydrogen pump capable of suppressing cell degradation more than before and a control method thereof.

[0009] In order to solve the above-mentioned problems, the present invention discloses an electrochemical hydrogen pump in one aspect, comprising a component and a voltage applicator, wherein the component includes an electrolyte membrane, an anode provided on one main surface of the electrolyte membrane, and a cathode provided on the other main surface of the electrolyte membrane, and the voltage applicator applies a voltage between the anode and the cathode, and the voltage applicator applies the voltage to move hydrogen in the hydrogen-containing gas supplied to the anode to the cathode and increase the pressure thereof.

[0010] The electrochemical hydrogen pump includes a controller that controls the voltage applied by the voltage applicator to increase the current flowing between the anode and the cathode when at least one of the dew point of the hydrogen-containing gas supplied to the anode and the temperature of the assembly increases.

[0011] In addition, a control method for an electrochemical hydrogen pump according to one aspect of the present disclosure comprises: a step of applying a voltage between an anode and a cathode provided on each main surface of an electrolyte membrane having a pair of main surfaces, thereby causing hydrogen in a hydrogen-containing gas supplied to the anode to move to the cathode to generate compressed hydrogen; and a step of controlling the voltage applied between the anode and the cathode to increase the current flowing between the anode and the cathode when at least one of the dew point of the hydrogen-containing gas supplied to the anode and the temperature of the component rises.

[0012] The electrochemical hydrogen pump according to one aspect of the present disclosure has the effect of being able to suppress component degradation more than before. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A It means that the current density flowing between the anode and cathode is 1.0A / cm 2 This is a table showing an example of component overvoltage when the component temperature and gas dew point change.

[0014] Figure 1B It means that the current density flowing between the anode and cathode is 1.5A / cm 2 This is a table showing an example of component overvoltage when the component temperature and gas dew point change.

[0015] Figure 1C It means that the current density flowing between the anode and cathode is 2.0A / cm 2 This is a table showing an example of component overvoltage when the component temperature and gas dew point change.

[0016] Figure 1D It means that the current density flowing between the anode and cathode is 2.5A / cm 2 This is a table showing an example of component overvoltage when the component temperature and gas dew point change.

[0017] Figure 2 This is a diagram showing an example of the electrochemical hydrogen pump according to the first embodiment.

[0018] Figure 3 This is a diagram showing an example of the correlation between the module temperature, the proton conductivity (electrical conductivity) of the electrolyte membrane, and the IR loss of the module.

[0019] Figure 4 This is a diagram showing an example of control of the current flowing between the anode and the cathode in the electrochemical hydrogen pump according to the third example of the first embodiment.

[0020] Figure 5 This is a diagram showing an example of an electrochemical hydrogen pump according to the second embodiment. DETAILED DESCRIPTION

[0021] Patent Document 1 does not fully examine the possibility of degradation of components of the electrochemical hydrogen pump.

[0022] Generally speaking, the lower the temperature of the component and the lower the water content of the electrolyte membrane, the lower the proton conductivity of the electrolyte membrane of the component. That is, the proton conductivity of the electrolyte membrane is represented by the product of the proton mobility in the electrolyte membrane and the amount of protons moving in the electrolyte membrane. Moreover, there is a positive correlation between the component temperature and the proton mobility in the electrolyte membrane. In addition, there is a positive correlation between the water content in the electrolyte membrane and the amount of protons moving in the electrolyte membrane. Therefore, for example, when the electrochemical hydrogen pump is started, there are many cases where both the component temperature and the water content of the electrolyte membrane are low. Therefore, it is believed that if the current flowing between the anode and the cathode is increased in such a state where the proton conductivity of the electrolyte membrane is low, then compared with the case where the current flowing between the anode and the cathode is increased after the proton conductivity of the electrolyte membrane becomes high, the phenomenon of the overvoltage of the component reaching a predetermined voltage or more is likely to occur.

[0023] Furthermore, it is generally known that when the overvoltage of the module reaches, for example, a predetermined voltage or more, the corrosion of the carbon carrier in the catalyst of the module advances, and the catalyst of the module is likely to deteriorate.

[0024] Based on the above viewpoints, the present inventors have found that by appropriately controlling the current flowing between the anode and the cathode based on at least one of the dew point of the hydrogen-containing gas supplied to the anode and the component temperature, it is possible to suppress component degradation of the electrochemical hydrogen pump. Such findings have been verified by the following experiments.

[0025] The MEA (module) used in this experiment was produced by simulating each layer of the MEA of the electrochemical hydrogen pump described in the following embodiment. Therefore, the detailed structure of the module will be omitted.

[0026] In this experiment, the current flowing between the anode and cathode was converted into current density and four representative values ​​(1.0 A / cm 2 , 1.5A / cm 2 , 2.0A / cm 2 , 2.5A / cm 2 ) is used as a parameter, and is performed by measuring the overvoltage of the component when the temperature of the component (hereinafter referred to as the component temperature Tc) and the dew point of the low-pressure hydrogen-containing gas supplied to the anode of the component (hereinafter referred to as the gas dew point Tg) respectively change.

[0027] At this time, the gas pressure on the cathode side was fixed at about 1 MPaG, and the gas pressure on the anode side was fixed at a pressure required for a predetermined flow rate of hydrogen-containing gas to circulate in the anode. Furthermore, the overvoltage of the module was measured using a pocket-sized wide-range DC power supply (PWR1201L manufactured by Kikusui Electronics Co., Ltd.).

[0028] However, in this experiment, the precondition that the gas dew point Tg is lower than the component temperature Tc (Tg ≤ Tc) is given. This is due to the following reasons.

[0029] If the gas dew point Tg is higher than the component temperature Tc (Tg>Tc), water vapor in the hydrogen-containing gas condenses at the anode of the component, which may cause blockage (overflow) of the flow path due to condensed water. In addition, since the diffusivity of the hydrogen-containing gas is hindered by the overflow of the anode, the overvoltage of the component may increase. Therefore, when the overvoltage of the component reaches a predetermined voltage (set to 500mV in this experiment) or more, the corrosion of the carbon carrier in the catalyst of the component is promoted, and the catalyst of the component is easily degraded.

[0030] Figure 1A It means that the current density flowing between the anode and cathode is 1.0A / cm 2 This is a table showing an example of component overvoltage when the component temperature and gas dew point change.

[0031] Figure 1B It means that the current density flowing between the anode and cathode is 1.5A / cm 2 This is a table showing an example of component overvoltage when the component temperature and gas dew point change.

[0032] Figure 1C It means that the current density flowing between the anode and cathode is 2.0A / cm 2 This is a table showing an example of component overvoltage when the component temperature and gas dew point change.

[0033] Figure 1D It means that the current density flowing between the anode and cathode is 2.5A / cm 2This is a table showing an example of component overvoltage when the component temperature and gas dew point change.

[0034] In each table, 7 representative temperatures (Tc = 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C) are taken as the component temperature Tc, and 7 representative temperatures (Tg = 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C) are taken as the gas dew point Tg, and the measurement results of the overvoltage (mV) of each component in their combination are shown.

[0035] Furthermore, in each table, the area where the measurement result of the overvoltage of the module is 500mV or more is marked with "X". In addition, from the area marked with "X", when the module temperature Tc is increased without increasing the gas dew point, or when the gas dew point is lowered without reducing the module temperature, the drying of the electrolyte membrane of the module is promoted. As a result, the corrosion of the carbon carrier in the catalyst of the module is promoted, and the catalyst of the module is easily degraded, so the overvoltage measurement of the module is terminated. In each table, such an unmeasured area is indicated by a "-" mark.

[0036] It should be noted that the above experimental conditions and the like are merely examples and are not limited to this example.

[0037] Here, it can be understood from the measurement results in each table that under the condition that the current density flowing between the anode and the cathode is low (for example Figure 1A or Figure 1B ), even when the gas dew point Tg and the component temperature Tc are low, the overvoltage of the component is unlikely to reach the region where the catalyst of the component deteriorates (in this experiment, the region above 500 mV).

[0038] On the other hand, it is known that under the condition that the current density flowing between the anode and the cathode is high (for example Figure 1C or Figure 1D ), when the gas dew point Tg and the component temperature Tc are low, the overvoltage of the component can easily reach the area where the component deteriorates.

[0039] As described above, the experimental results can be inferred from the positive correlation between the proton conductivity of the electrolyte membrane and the component temperature Tc and the water content of the electrolyte membrane (gas dew point Tg). That is, when the gas dew point Tg and the component temperature Tc are low, the resistance of the electrolyte membrane becomes higher. However, the overvoltage of the component including the IR loss equivalent to the product of the current and the resistance, under the condition of low current density flowing between the anode and the cathode, mostly does not reach the region where the catalyst of the component degrades. On the contrary, under the condition of high current density flowing between the anode and the cathode, the overvoltage of the above-mentioned component mostly reaches the region where the catalyst of the component degrades.

[0040] Thus, the lower the component temperature Tc and the gas dew point Tg, the easier it is for the component overvoltage to reach the catalyst deterioration region of the component when the current flowing between the anode and the cathode is increased. In other words, the higher the component temperature Tc and the gas dew point Tg, the harder it is for the component overvoltage to reach the catalyst deterioration region of the component even if the current flowing between the anode and the cathode is increased.

[0041] Based on the above measurement results, it is believed that when the current flowing between the anode and the cathode is increased after at least one of the component temperature Tc and the gas dew point Tg rises from a low state to a high state, it is suitable from the perspective of suppressing the catalyst degradation of the component, compared with the case where the above current is increased while they are kept in a low state.

[0042] That is, the electrochemical hydrogen pump of the first embodiment of the present disclosure comprises a component and a voltage applicator, wherein the component includes an electrolyte membrane, an anode provided on one main surface of the electrolyte membrane, and a cathode provided on the other main surface of the electrolyte membrane, and the voltage applicator applies a voltage between the anode and the cathode. By applying a voltage between the anode and the cathode by the voltage applicator, hydrogen in the hydrogen-containing gas supplied to the anode is moved to the cathode and its pressure is increased. The electrochemical hydrogen pump comprises a controller, and when at least one of the dew point of the hydrogen-containing gas supplied to the anode and the temperature of the component rises, the controller controls the applied voltage of the voltage applicator to increase the current flowing between the anode and the cathode.

[0043] According to such a technical configuration, the electrochemical hydrogen pump of this embodiment can suppress the degradation of components more than ever before.

[0044] For example, since the water content in the electrolyte membrane is positively correlated with the amount of protons moving in the electrolyte membrane, if the current flowing between the anode and the cathode is increased when the dew point of the hydrogen-containing gas supplied to the anode is low, the overvoltage of the assembly increases, and the possibility of catalyst degradation of the assembly increases. In addition, since the temperature of the assembly is positively correlated with the proton mobility in the electrolyte membrane, if the above current is increased when the temperature of the assembly is low, the overvoltage of the assembly increases, and the possibility of catalyst degradation of the assembly increases.

[0045] Therefore, the electrochemical hydrogen pump of the present embodiment increases the current flowing between the anode and the cathode after at least one of the dew point of the hydrogen-containing gas supplied to the anode and the temperature of the component rises, thereby reducing the possibility of the overvoltage of the component reaching the area where the catalyst of the component degrades, compared to the case where the above current is increased when they are low.

[0046] The electrochemical hydrogen pump of the second embodiment of the present invention is, in the electrochemical hydrogen pump of the first embodiment, when the dew point of the hydrogen-containing gas supplied to the anode reaches above the first threshold value, the controller controls the applied voltage of the voltage applicator to increase the current flowing between the anode and the cathode, and when the dew point of the hydrogen-containing gas supplied to the anode is less than the first threshold value, the controller controls the applied voltage of the voltage applicator to not increase the current.

[0047] According to such a technical configuration, the electrochemical hydrogen pump of this embodiment can prevent component degradation by appropriately controlling the increase or decrease of the current flowing between the anode and the cathode based on the comparison between the dew point of the hydrogen-containing gas supplied to the anode and the first threshold.

[0048] In the electrochemical hydrogen pump of the third embodiment of the present invention, in the electrochemical hydrogen pump of the first embodiment or the second embodiment, when the temperature of the component reaches above the second threshold value, the controller controls the applied voltage of the voltage applicator to increase the current flowing between the anode and the cathode, and when the temperature of the component is less than the second threshold value, the controller controls the applied voltage of the voltage applicator to not increase the current.

[0049] In an electrochemical hydrogen pump, for example, when the pump is controlled so that the relative humidity of the electrolyte membrane and the current density flowing between the anode and the cathode are constant, the proton conductivity (electrical conductivity) of the electrolyte membrane increases as the temperature of the component increases. Specifically, when the temperature of the component is above a predetermined temperature, the IR loss of the component is sufficiently reduced. The details are described in the second embodiment.

[0050] Therefore, the electrochemical hydrogen pump of this embodiment can improve the efficiency of the hydrogen pressure boosting operation by increasing the current flowing between the anode and the cathode above the second threshold at which the IR loss of the module is sufficiently reduced.

[0051] In addition, the electrochemical hydrogen pump of the present embodiment can prevent degradation of the component by appropriately controlling the increase or decrease of the current flowing between the anode and the cathode based on the comparison between the temperature of the component and the second threshold value.

[0052] The electrochemical hydrogen pump of the fourth embodiment of the present disclosure may be an electrochemical hydrogen pump according to any one of the first to third embodiments, comprising a dew point adjuster, the dew point adjuster adjusting the dew point of the hydrogen-containing gas supplied to the anode, and a controller controlling the dew point adjuster so that the dew point of the hydrogen-containing gas supplied to the anode is below the temperature of the component.

[0053] According to such a technical configuration, the electrochemical hydrogen pump of this embodiment can suppress the degradation of components more than ever before.

[0054] Specifically, if the dew point of the hydrogen-containing gas supplied to the anode is higher than the temperature of the assembly, water vapor in the hydrogen-containing gas condenses at the anode, which may cause blockage (overflow) of the flow path due to condensed water. Moreover, the diffusivity of the hydrogen-containing gas is hindered by the overflow of the anode, which may cause the overvoltage of the assembly to increase. As a result, when the overvoltage of the assembly reaches a predetermined voltage or more, the corrosion of the carbon carrier in the catalyst of the assembly is promoted, and the assembly is prone to deterioration.

[0055] Therefore, the electrochemical hydrogen pump of the present embodiment suppresses the occurrence of anode flooding by controlling the dew point of the hydrogen-containing gas supplied to the anode to be equal to or lower than the temperature of the assembly.

[0056] The electrochemical hydrogen pump of the fifth embodiment of the present disclosure may be an electrochemical hydrogen pump according to any one of the first to fourth embodiments, wherein a controller controls the applied voltage of a voltage applicator so that, during the period when the current flowing between the anode and the cathode increases from 0 to a predetermined value, the lower the current, the higher the rate of increase of the current.

[0057] The reason for such voltage control is that the lower the current flowing between the anode and the cathode, the lower the possibility that the overvoltage (IR loss) of the module will reach the region where the catalyst of the module deteriorates, even if the rate of increase of the current is high.

[0058] Therefore, the electrochemical hydrogen pump of this mode can appropriately suppress the degradation of the components and quickly increase the current of the components. For example, when the electrochemical hydrogen pump is started, in most cases, both the temperature of the components and the water content of the electrolyte membrane are low. However, even in this case, when the current flowing between the anode and the cathode is low, the rate of increase of the current can be increased without accompanying the degradation of the components, and as a result, the electrochemical hydrogen pump can be effectively started.

[0059] The electrochemical hydrogen pump of the sixth embodiment of the present disclosure may be an electrochemical hydrogen pump according to any one of the first to fifth embodiments, and further include a dew point adjuster, the dew point adjuster adjusting the dew point of the hydrogen-containing gas supplied to the anode, and a controller controlling the dew point adjuster to increase the dew point of the hydrogen-containing gas supplied to the anode according to the temperature increase of the component.

[0060] According to such a technical configuration, the electrochemical hydrogen pump of this embodiment can reduce the possibility of drying up of the electrolyte membrane compared to a case where the dew point of the hydrogen-containing gas supplied to the anode is not increased in accordance with the increase in the temperature of the components.

[0061] That is, the control method of the electrochemical hydrogen pump of the seventh embodiment of the present disclosure comprises: a step of moving hydrogen in the hydrogen-containing gas supplied to the anode to the cathode by applying a voltage between the anode and the cathode provided on each main surface of an electrolyte membrane having a pair of main surfaces to generate compressed hydrogen; and a step of controlling the voltage applied between the anode and the cathode to increase the current flowing between the anode and the cathode when at least one of the dew point of the hydrogen-containing gas supplied to the anode and the temperature of the component rises.

[0062] According to such a technical configuration, in the control method of the electrochemical hydrogen pump of this embodiment, it is possible to suppress the degradation of components more than before.

[0063] Hereinafter, the embodiments of the present disclosure will be described with reference to the accompanying drawings. Furthermore, the embodiments described below all represent an example of the above-mentioned embodiments. Therefore, the shapes, materials, constituent elements, and the configuration positions and connection methods of the constituent elements shown below are only examples, and the above-mentioned embodiments are not limited unless they are recorded in the claims. In addition, the constituent elements that are not recorded in the independent claims representing the highest-level concepts of the above-mentioned embodiments among the following constituent elements are described as optional constituent elements. In addition, the description of the same marks in the drawings is sometimes omitted. For easy understanding, the drawings schematically show the various constituent elements, and the shapes and size ratios are sometimes not accurately represented.

[0064] (First embodiment)

[0065] [Device structure]

[0066] Figure 2 This is a diagram showing an example of the electrochemical hydrogen pump according to the first embodiment.

[0067] Figure 2 In the example shown, the electrochemical hydrogen pump 100 of the present embodiment includes a module 70 , a voltage applicator 102 , and a controller 60 .

[0068] Furthermore, the electrochemical hydrogen pump 100 may include a stack formed by stacking a plurality of modules 70. Details will be described later.

[0069] The module 70 includes an electrolyte membrane 11 , an anode AN, and a cathode CA.

[0070] The anode AN is provided on one main surface of the electrolyte membrane 11. The anode AN is an electrode including an anode catalyst layer and an anode gas diffusion layer. The cathode CA is provided on the other main surface of the electrolyte membrane 11. The cathode CA is an electrode including a cathode catalyst layer and a cathode gas diffusion layer. Thus, the electrolyte membrane 11 is sandwiched by the anode AN and the cathode CA in a manner of contacting the anode catalyst layer 13 and the cathode catalyst layer 12, respectively.

[0071] As long as it is a membrane with proton conductivity, the electrolyte membrane 1 can be of various structures. For example, as the electrolyte membrane 1, a fluorine-based polymer electrolyte membrane, a hydrocarbon-based electrolyte membrane, etc. can be cited. Specifically, as the electrolyte membrane 1, for example, Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Corporation), etc. can be used, but it is not limited thereto.

[0072] The anode catalyst layer is provided on one main surface of the electrolyte membrane 11. The anode catalyst layer includes carbon capable of supporting a catalyst metal (for example, platinum) in a dispersed state, but is not limited thereto.

[0073] The cathode catalyst layer is provided on the other main surface of the electrolyte membrane 11. The cathode catalyst layer includes carbon capable of supporting a catalyst metal (for example, platinum) in a dispersed state, but is not limited thereto.

[0074] Various methods can be cited as the modulation method of the cathode catalyst layer and the anode catalyst layer as catalysts, and there is no particular limitation. For example, as carbon-based powders, powders such as graphite, carbon black, and activated carbon with conductivity can be cited. The method of supporting platinum or other catalytic metals on a carbon carrier is not particularly limited. For example, methods such as powder mixing or liquid phase mixing can be used. As the latter liquid phase mixing, for example, a method of dispersing and adsorbing a carrier such as carbon in a colloidal liquid of the catalyst component can be cited. The supporting state of catalyst metals such as platinum on the carbon carrier is not particularly limited. For example, the catalyst metal can be micronized and supported on the carrier with high dispersion.

[0075] The cathode gas diffusion layer is provided on the cathode catalyst layer. The cathode gas diffusion layer is made of a porous material and has electrical conductivity and gas diffusion properties. It is desirable that the cathode gas diffusion layer has elasticity to appropriately follow the displacement and deformation of the constituent members caused by the pressure difference between the cathode CA and the anode AN when the electrochemical hydrogen pump 100 is working. As a substrate for the cathode gas diffusion layer, for example, a carbon fiber sintered body can be used, but it is not limited thereto.

[0076] The anode gas diffusion layer is provided on the anode catalyst layer. The anode gas diffusion layer is composed of a porous material and has electrical conductivity and gas diffusion properties. It is desirable that the anode gas diffusion layer has a degree of rigidity that can withstand the pressure adhesion of the electrolyte membrane 11 caused by the above-mentioned pressure difference when the electrochemical hydrogen pump 100 is working. As a substrate for the anode gas diffusion layer, for example, a carbon particle sintered body can be used, but it is not limited thereto.

[0077] The voltage applicator 102 is a device that applies a voltage between the anode AN and the cathode CA. The voltage applicator 102 may have various structures as long as it can apply a voltage between the anode AN and the cathode CA. Figure 2In the example shown, the high potential side terminal of the voltage applicator 102 is connected to the anode AN, and the low potential side terminal of the voltage applicator 102 is connected to the cathode CA. Thus, the voltage applicator 102 is used to pass electricity between the anode AN and the cathode CA. Therefore, in the electrochemical hydrogen pump 100 of this embodiment, the voltage applicator 102 applies a voltage between the anode AN and the cathode CA to move hydrogen in the hydrogen-containing gas supplied to the anode AN to the cathode CA and increase the pressure.

[0078] Furthermore, as the voltage applicator 102, for example, a DC / DC converter, an AC / DC converter, etc. can be cited. When the voltage applicator 102 is connected to a DC power source such as a solar cell, a fuel cell, or a battery, a DC / DC converter is used. When the voltage applicator 102 is connected to an AC power source such as a commercial power source, an AC / DC converter is used.

[0079] In addition, the voltage applicator 102 may be a power source, for example, to adjust the voltage applied between the anode AN and the cathode CA and the current flowing between the anode AN and the cathode CA so that the power supplied to the component 70 becomes a predetermined set value.

[0080] When at least one of the dew point of the hydrogen-containing gas supplied to the anode AN and the temperature of the assembly 70 increases, the controller 60 controls the applied voltage of the voltage applicator 102 to increase the current flowing between the anode AN and the cathode CA.

[0081] The controller 60 includes, for example, a computing circuit (not shown) and a storage circuit (not shown) storing a control program. Examples of the computing circuit include an MPU, a CPU, etc. Examples of the storage circuit include a memory, etc. The controller 60 may be composed of a single controller that performs centralized control, or may be composed of a plurality of controllers that cooperate with each other to perform distributed control.

[0082] Although not shown in FIG. 1 , components and equipment required for the hydrogen pressure increasing operation of the electrochemical hydrogen pump 100 may be appropriately provided.

[0083] For example, a pair of diaphragms can respectively clamp the anode AN and the cathode CA of the assembly 70 from the outside. In this case, the diaphragm in contact with the anode AN is a conductive plate-shaped member for supplying hydrogen-containing gas to the anode AN. The plate-shaped member has a gas flow path for the flow of hydrogen-containing gas supplied to the anode AN. The diaphragm in contact with the cathode CA is a conductive plate-shaped member for extracting hydrogen from the cathode CA. The plate-shaped member has a gas flow path for the flow of hydrogen extracted from the cathode CA. These gas flow paths can be provided separately from the diaphragm, but generally, the grooves of the gas flow paths are formed on the surface of the diaphragm, for example, in a serpentine shape.

[0084] In addition, in the electrochemical hydrogen pump 100, sealing materials such as gaskets are usually provided on both sides of the assembly 70 to prevent high-pressure hydrogen from leaking to the outside, and the assembly 70 is pre-assembled as an integrated whole. Furthermore, the diaphragm described above is arranged on the outside of the assembly 70 for mechanically fixing the assembly 70 and electrically connecting adjacent assemblies 70 in series.

[0085] The components 70 and the diaphragms are alternately overlapped, and about 10 to 200 components 70 are stacked. The stack (stack) is clamped by end plates with collector plates and insulating plates interposed therebetween, and the two end plates are fastened by tie rods. This is a general stacking structure. Furthermore, in this case, in order to supply an appropriate amount of hydrogen-containing gas to each gas flow path of the diaphragm, it is necessary to form a structure in which a groove-shaped branch path branches from an appropriate pipeline in each diaphragm, and their downstream ends are connected to each gas flow path of the diaphragm. Such a pipeline is called a manifold, and the manifold is composed of, for example, a connection of through holes provided at each appropriate position of the components constituting the stack.

[0086] In addition, the electrochemical hydrogen pump 100 may be provided with a temperature detector for detecting the temperature of the module 70, a temperature regulator for regulating the temperature of the module 70, a dew point regulator for regulating the dew point of the hydrogen-containing gas supplied to the anode AN, etc. The details of the dew point regulator will be described in the second embodiment.

[0087] Examples of the temperature detector include a thermocouple and a thermistor, but the temperature detector is not limited thereto.

[0088] In addition, as a temperature regulator, for example, a device that circulates a heat medium at an appropriate temperature in a flow path formed in the diaphragm can be cited, but it is not limited to this. The temperature regulator can be a combination of a heater (such as an electric heater) of the heating component 70 and a cooler (such as a cooling fan) of the cooling component 70.

[0089] It should be noted that the above-mentioned components and devices not shown in the figures are merely examples and are not limited to the present example.

[0090] [action]

[0091] Hereinafter, an example of the hydrogen pressure increasing operation of the electrochemical hydrogen pump 100 will be described with reference to the drawings.

[0092] The following operations can be executed by, for example, the arithmetic circuit of the controller 60 reading the control program from the storage circuit of the controller 60. However, it is not necessarily necessary to execute the following operations by the controller 60. The operator can execute part of the operations.

[0093] First, a low-pressure hydrogen-containing gas is supplied to the anode AN of the electrochemical hydrogen pump 100 , and a voltage from the voltage applicator 102 is supplied to the electrochemical hydrogen pump 100 .

[0094] Then, in the anode catalyst layer of the anode AN, hydrogen molecules are separated into protons and electrons (Formula (1)). The protons are conducted in the electrolyte membrane 11 and move to the cathode catalyst layer. The electrons move to the cathode catalyst layer through the voltage applicator 102.

[0095] Then, hydrogen molecules are generated again in the cathode catalyst layer (Formula (2)). It is known that when protons are conducted in the electrolyte membrane 11, a predetermined amount of water moves from the anode AN to the cathode CA as electroosmotic water along with the protons.

[0096] At this time, by using a flow regulator (not shown) to increase the pressure loss of the hydrogen derivation path, the hydrogen (H2) generated at the cathode CA can be pressurized. Furthermore, as a flow regulator, for example, a back pressure valve and a regulating valve provided in the hydrogen derivation path can be cited. In this case, the so-called increase in the pressure loss of the hydrogen derivation path corresponds to reducing the opening of the back pressure valve and the regulating valve provided in the hydrogen derivation path.

[0097] Anode: H2 (low pressure) → 2H + +2e-…(1)

[0098] Cathode: 2H + +2e-→H2(high pressure)…(2)

[0099] In this way, the hydrogen pressure boosting operation of the electrochemical hydrogen pump 100 is performed to boost the pressure of hydrogen in the hydrogen-containing gas supplied to the anode AN at the cathode CA by applying the voltage by the voltage applicator 102. Furthermore, in the hydrogen pressure boosting operation, when at least one of the dew point of the hydrogen-containing gas supplied to the anode AN and the temperature of the assembly 70 increases, the applied voltage of the voltage applicator 102 is controlled so that the current flowing between the anode AN and the cathode CA increases.

[0100] Furthermore, the hydrogen after the pressure increase at the cathode CA is temporarily stored in a hydrogen storage device (not shown). In addition, the hydrogen stored in the hydrogen storage device is promptly supplied to a hydrogen demander. As a hydrogen demander, for example, a fuel cell that uses hydrogen to generate electricity can be cited.

[0101] As described above, the electrochemical hydrogen pump 100 of the present embodiment can suppress the deterioration of the assembly 70 more than conventional ones.

[0102] For example, the water content in the electrolyte membrane 11 is positively correlated with the amount of protons moving in the electrolyte membrane 11, so when the dew point of the hydrogen-containing gas supplied to the anode AN is low, when the current flowing between the anode AN and the cathode CA is increased, the possibility of the catalyst of the assembly 70 being degraded due to the increase in overvoltage of the assembly 70 becomes high. In addition, the temperature of the assembly 70 is positively correlated with the proton mobility in the electrolyte membrane 11, so when the above-mentioned current is increased when the temperature of the assembly 70 is low, the possibility of the catalyst of the assembly 70 being degraded due to the increase in overvoltage of the assembly 70 becomes high.

[0103] Therefore, the electrochemical hydrogen pump 100 of the present embodiment increases the current flowing between the anode AN and the cathode CA after at least one of the dew point of the hydrogen-containing gas supplied to the anode AN and the temperature of the component 70 rises, thereby reducing the possibility of the overvoltage of the component reaching the area where the catalyst of the component 70 deteriorates, compared with the case where the above-mentioned current is increased while maintaining them at a low state.

[0104] (First embodiment)

[0105] The electrochemical hydrogen pump 100 of the first example is the same as the electrochemical hydrogen pump 100 of the first embodiment except for the control contents of the controller 60 described below.

[0106] When the dew point of the hydrogen-containing gas supplied to the anode AN reaches above the first threshold, the controller 60 controls the applied voltage of the voltage applicator 102 to increase the current flowing between the anode AN and the cathode CA, and when the dew point of the hydrogen-containing gas supplied to the anode AN is less than the first threshold, the controller 60 controls the applied voltage of the voltage applicator 102 to not increase the current.

[0107] The first threshold value may be determined by referring to the operating conditions such as the amount of hydrogen boosted by the electrochemical hydrogen pump. Figure 1A-Figure 1D The table described in and the like are set to appropriate values ​​that are unlikely to cause degradation of components of the electrochemical hydrogen pump.

[0108] As described above, the electrochemical hydrogen pump 100 of this embodiment can prevent the component 70 from being easily deteriorated by appropriately controlling the increase or decrease of the current flowing between the anode AN and the cathode CA based on the comparison between the dew point of the hydrogen-containing gas supplied to the anode AN and the first threshold value.

[0109] The electrochemical hydrogen pump 100 of this embodiment may be the same as the electrochemical hydrogen pump 100 of the first embodiment except for the above-mentioned features.

[0110] (Second embodiment)

[0111] The electrochemical hydrogen pump 100 of the second embodiment is the same as the electrochemical hydrogen pump 100 of the first embodiment except for the control contents of the controller 60 described below.

[0112] Figure 3 This is a diagram showing an example of the correlation between the module temperature, the proton conductivity (electrical conductivity) of the electrolyte membrane, and the IR loss of the module. Figure 3 The horizontal axis represents the temperature of the component 70. In addition, Figure 3 The left vertical axis represents the proton conductivity of the electrolyte membrane 11, and the right vertical axis represents the IR loss of the module 70. Figure 3 The above correlation shows the relative humidity of the electrolyte membrane 11 and the density of the current flowing between the anode AN and the cathode CA when they are constant. For example, by increasing or decreasing the dew point of the hydrogen-containing gas as the temperature of the module 70 increases or decreases, the relative humidity of the electrolyte membrane 11 can be maintained constant.

[0113] from Figure 3 It can be understood that in the electrochemical hydrogen pump 100, for example, when the pump is controlled so that the relative humidity of the electrolyte membrane 11 and the current density flowing between the anode AN and the cathode CA are constant, the proton conductivity (electrical conductivity) of the electrolyte membrane 11 increases as the temperature of the component 70 increases. Specifically, it can be seen that when the temperature of the component 70 is above the predetermined temperature, the IR loss of the component 70 is sufficiently reduced.

[0114] Therefore, when the temperature of the component 70 reaches above the second threshold, the controller 60 controls the applied voltage of the voltage applicator 102 to increase the current flowing between the anode AN and the cathode CA. When the temperature of the component 70 is less than the second threshold, the controller 60 controls the applied voltage of the voltage applicator 102 to not increase the current.

[0115] As described above, the electrochemical hydrogen pump 100 of the present embodiment can improve the efficiency of the hydrogen pressure boosting operation by increasing the current flowing between the anode AN and the cathode CA above the second threshold value at which the IR loss of the assembly 70 is sufficiently reduced. In this case, the second threshold value can be set to an appropriate value for improving the efficiency of the hydrogen pressure boosting operation of the electrochemical hydrogen pump 100 by, for example, referring to the correlation between the temperature of the assembly 70 and the IR loss of the assembly 70 based on operating conditions such as the amount of hydrogen boosted by the electrochemical hydrogen pump.

[0116] In addition, the electrochemical hydrogen pump 100 of the present embodiment can appropriately control the increase or decrease of the current flowing between the anode AN and the cathode CA based on the comparison between the temperature of the component 70 and the second threshold value, so that the degradation of the component 70 is not likely to occur. In this case, the second threshold value can be determined based on the operating conditions such as the amount of hydrogen boosted by the electrochemical hydrogen pump, for example. Figure 1A-Figure 1DThe table described in the table is used to set the appropriate value at which the component degradation of the electrochemical hydrogen pump is unlikely to occur.

[0117] The electrochemical hydrogen pump 100 of the present embodiment may be the same as the electrochemical hydrogen pump 100 of the first embodiment or the first example of the first embodiment except for the above-mentioned features.

[0118] (Third embodiment)

[0119] The electrochemical hydrogen pump 100 of the third embodiment is the same as the electrochemical hydrogen pump 100 of the first embodiment except for the control contents of the controller 60 described below.

[0120] Figure 4 This is a diagram showing an example of control of the current flowing between the anode and the cathode in the electrochemical hydrogen pump according to the third example of the first embodiment.

[0121] In the electrochemical hydrogen pump of this embodiment, as an example, Figure 4 As shown, the period during which the current flowing between the anode AN and the cathode CA at the time of starting rises from 0 to a predetermined value is divided into n sub-periods (s1, s2, ..., sn: n is a natural number), and the current increments of each of the n sub-periods are set to f1, f2, ..., fn (n is a natural number). And, n ratios obtained based on the current increment (fx) corresponding to the sub-period (sx) selected from such n sub-periods and the selected sub-period (sx) are set to rx (rx = fx / sx: x is a natural number represented by 1≤x≤n). Then, the lower current of any two ratios selected from the n ratios rx is defined as the first ratio, and the higher current is defined as the second ratio. At this time, the applied voltage of the voltage applicator 102 is controlled so that the second ratio is smaller than the first ratio. That is, by setting the ratio r to r=f1 / s1≥f2 / s2≥f3 / s3≥f4 / s4, the applied voltage of the voltage applicator 102 is controlled so that the time change of the current becomes gentler as time passes from the start of the startup.

[0122] Thus, in the electrochemical hydrogen pump 100 of this embodiment, the controller 60 controls the applied voltage of the voltage applicator 102 so that, while increasing the current flowing between the anode AN and the cathode CA from 0 to a predetermined value, the current increase rate increases as the current decreases.

[0123] The reason for such voltage control is that the lower the current flowing between the anode AN and the cathode CA, the lower the possibility that the overvoltage (IR loss) of the assembly 70 reaches the region where the catalyst of the assembly 70 degrades even if the rate of increase of the current is high.

[0124] Thus, the electrochemical hydrogen pump 100 of the present embodiment can appropriately suppress the degradation of the component 70 and rapidly increase the current of the component 70. For example, when the electrochemical hydrogen pump 100 is started, both the temperature of the component 70 and the water content of the electrolyte membrane 11 are low in many cases. However, even in this case, when the current flowing between the anode AN and the cathode CA is low, the rate of increase of the current can be increased without deteriorating the component 70, and as a result, the electrochemical hydrogen pump 100 can be effectively started.

[0125] The electrochemical hydrogen pump 100 of the present embodiment may be the same as the electrochemical hydrogen pump 100 of the first embodiment and any of the first and second embodiments of the first embodiment, except for the above-described features.

[0126] (Second embodiment)

[0127] Figure 5 This is a diagram showing an example of an electrochemical hydrogen pump according to the second embodiment.

[0128] Figure 5 In the example shown, the electrochemical hydrogen pump 100 of the present embodiment includes a module 70 , a voltage applicator 102 , a dew point adjuster 110 , and a controller 60 .

[0129] Here, the assembly 70 and the voltage applicator 102 are the same as those in the first embodiment, and thus their description is omitted.

[0130] The dew point adjuster 110 is a device for adjusting the dew point of the hydrogen-containing gas supplied to the anode AN. The dew point adjuster 110 may have various structures as long as it can adjust the dew point of the hydrogen-containing gas.

[0131] For example, the dew point adjuster 110 may include a humidifier for humidifying the hydrogen-containing gas. Examples of the humidifier include a humidifier with a bubbling structure for humidifying the hydrogen-containing gas by ventilation in warm water, a humidifier with a structure for humidifying the hydrogen-containing gas using a moisture permeable membrane, etc. Furthermore, when the dew point adjuster 110 includes the humidifier with the bubbling structure, the dew point of the hydrogen-containing gas can be appropriately adjusted according to the warm water temperature.

[0132] In addition, the dew point adjuster 110 may be a mixer that adjusts the dew point of the mixed gas by mixing the highly humidified hydrogen-containing gas discharged from the anode AN and the low humidified hydrogen-containing gas supplied from an external hydrogen supply source. In this case, the hydrogen-containing gas from the external hydrogen supply source may be generated by a water electrolysis device, for example.

[0133] The controller 60 controls the dew point adjuster 110 to set the dew point of the hydrogen-containing gas supplied to the anode AN to be equal to or lower than the temperature of the assembly 70 .

[0134] As described above, the electrochemical hydrogen pump 100 of the present embodiment can suppress the degradation of the component 70 more than before. Specifically, when the dew point of the hydrogen-containing gas supplied to the anode AN is higher than the temperature of the component 70, the water vapor in the hydrogen-containing gas condenses at the anode AN, and thus the flow path blockage (overflow) caused by the condensed water may occur. Moreover, the diffusivity of the hydrogen-containing gas is hindered by the overflow of the anode AN, which may cause the overvoltage of the component 70 to rise. Therefore, when the overvoltage of the component 70 reaches a predetermined voltage or more, the corrosion of the carbon carrier in the catalyst of the component 70 is promoted, and the component 70 is easy to deteriorate.

[0135] Therefore, the electrochemical hydrogen pump 100 of the present embodiment can suppress the occurrence of flooding of the anode AN by controlling the dew point of the hydrogen-containing gas supplied to the anode AN to be equal to or lower than the temperature of the assembly 70 .

[0136] The electrochemical hydrogen pump 100 of the present embodiment may be the same as the electrochemical hydrogen pump 100 of the first embodiment and any of the first to third examples of the first embodiment, except for the above-described features.

[0137] (Variation Example)

[0138] The electrochemical hydrogen pump 100 of the present modification is the same as the electrochemical hydrogen pump 100 of the second embodiment except for the control contents of the controller 60 described below.

[0139] The controller 60 controls the dew point adjuster 110 to increase the dew point of the hydrogen-containing gas supplied to the anode AN in accordance with the increase in the temperature of the assembly 70 .

[0140] As described above, the electrochemical hydrogen pump 100 of the present modification can reduce the possibility of drying up of the electrolyte membrane 11 compared to a case where the dew point of the hydrogen-containing gas supplied to the anode AN is not increased in accordance with the increase in the temperature of the assembly 70 .

[0141] The electrochemical hydrogen pump 100 of this modification example may be the same as the electrochemical hydrogen pump 100 of any of the first embodiment, the first to third examples of the first embodiment, and the second embodiment, except for the above-described features.

[0142] Furthermore, the first embodiment, the first to third examples of the first embodiment, the second embodiment, and the second embodiment modification may be combined with each other as long as they do not exclude each other.

[0143] Based on the above description, many improvements and other embodiments of the present disclosure are obvious to those skilled in the art. Therefore, the above description should be interpreted as an example only, and is provided for the purpose of teaching those skilled in the art the best way to implement the present disclosure. The details of its structure and / or function can be substantially changed without departing from the spirit of the present disclosure.

[0144] Industrial Applicability

[0145] An aspect of the present disclosure can be used for an electrochemical hydrogen pump capable of suppressing component degradation more than ever before.

[0146] Description of Reference Numerals

[0147] 11: Electrolyte membrane

[0148] 60: Controller

[0149] 70: Components

[0150] 100: Electrochemical hydrogen pump

[0151] 102: Voltage applicator

[0152] 110: Dew point adjuster

[0153] AN: Anode

[0154] CA: cathode

Claims

1. An electrochemical hydrogen pump, comprising a component and a voltage applicator, wherein the component comprises an electrolyte membrane, an anode provided on one main surface of the electrolyte membrane, and a cathode provided on the other main surface of the electrolyte membrane, and the voltage applicator applies a voltage between the anode and the cathode, The voltage is applied by the voltage applicator to move hydrogen in the hydrogen-containing gas supplied to the anode to the cathode and increase the pressure thereof, The electrochemical hydrogen pump includes a controller that controls the voltage applied by the voltage applicator to increase the current flowing between the anode and the cathode when the dew point of the hydrogen-containing gas supplied to the anode increases.

2. According to the electrochemical hydrogen pump of claim 1, when the dew point of the hydrogen-containing gas supplied to the anode reaches above the first threshold, the controller controls the applied voltage of the voltage applicator to increase the current, and when the dew point of the hydrogen-containing gas supplied to the anode is less than the first threshold, the controller controls the applied voltage of the voltage applicator to not increase the current.

3. The electrochemical hydrogen pump according to claim 1 or 2, A dew point adjuster is provided for adjusting the dew point of the hydrogen-containing gas supplied to the anode. The controller controls the dew point adjuster so that the dew point of the hydrogen-containing gas supplied to the anode is lower than or equal to the temperature of the assembly.

4. The electrochemical hydrogen pump according to claim 1 or 2, The controller controls the applied voltage of the voltage applicator so that, during a period in which the current flowing between the anode and the cathode is increased from 0 to a predetermined value, the rate of increase of the current is increased as the current is lower.

5. The electrochemical hydrogen pump according to claim 1 or 2, A dew point adjuster is provided for adjusting the dew point of the hydrogen-containing gas supplied to the anode. The controller controls the dew point adjuster to increase the dew point of the hydrogen-containing gas supplied to the anode in accordance with an increase in the temperature of the assembly.

6. A control method for an electrochemical hydrogen pump, comprising: A step of applying a voltage between an anode and a cathode provided on each main surface of an electrolyte membrane having a pair of main surfaces to move hydrogen in a hydrogen-containing gas supplied to the anode to the cathode to generate compressed hydrogen; and The step of controlling a voltage applied between the anode and the cathode to increase a current flowing between the anode and the cathode when a dew point of the hydrogen-containing gas supplied to the anode increases.

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