Determination device, electrochemical device, and deterioration detection method

Abstract

This invention provides a determination device that enables the detection of electrolyte membrane degradation based on current information and gas pressure acquired during the normal operation of an electrochemical apparatus. [Solution] The determination device 30 determines the deterioration of the electrolyte membrane in an electrochemical apparatus 10 which includes an electrochemical cell 36 and a volume section where the gas generated by the electrochemical cell 36 collects. The determination device 30 includes a pressure acquisition unit 56 which acquires a detection signal detected by a detection sensor 28 which detects the current flowing between the first electrode and the second electrode, and an output signal from a pressure sensor 24 which detects the pressure in the volume section, and a deterioration determination unit 60 which determines whether or not the electrolyte membrane is deteriorated based on the current or the amount of gas generated determined from the current and the pressure in the volume section.

Description

Technical Field

[0001] The present disclosure relates to a determination device for determining deterioration of an electrolyte membrane, an electrochemical device, and a deterioration detection method.

Background Art

[0002] An electrochemical cell in which an electrolyte membrane is disposed between an anode electrode and a cathode electrode is used, for example, in an electrochemical gas pump that boosts a gas such as hydrogen and a water electrolysis device. When an electrochemical device such as an electrochemical gas pump and a water electrolysis device is operated for a long time, the electrolyte membrane becomes thin, and an increase in the reverse flow rate (cross leak rate) of the generated gas from the high-pressure side to the low-pressure side may occur. Further, the deterioration of the electrolyte membrane also appears as a decrease in the permeation amount (permeation characteristics) of substances due to current. The decrease in the permeation characteristics reduces the ratio of the permeation amount of substances to the normally occurring cross leak amount, resulting in a decrease in current efficiency similar to the increase in the cross leak amount when the electrolyte membrane becomes thin. Therefore, in order to enable replacement of the electrochemical cell at an appropriate time, it is required to detect the deterioration of the electrolyte membrane.

[0003] As a method for detecting deterioration of an electrolyte membrane in an electrochemical cell, a method of providing a gas sensor in a gas flow path to detect leaked impurities and a method of measuring the potential difference between an anode and a cathode reflecting cross leak (Japanese Unexamined Patent Application Publication No. 2018-95953) are known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The method using gas sensors has a problem in that it cannot detect cross-leakage in electrochemical devices such as electrochemical gas pumps where the same type of gas flows through both electrodes.

[0006] Furthermore, the method described in Japanese Patent Publication No. 2018-95953 has the problem that it is not possible to detect the deterioration of the electrochemical cell from data acquired during normal operation, and therefore it is not possible to predict the replacement time based on the progress of deterioration.

[0007] This disclosure aims to solve the problems described above. [Means for solving the problem]

[0008] A first aspect of the present disclosure is a determination device for determining the deterioration of an electrolyte membrane in an electrochemical apparatus comprising an electrochemical cell having an electrolyte membrane, a first electrode formed on a first surface of the electrolyte membrane, and a second electrode formed on a second surface of the electrolyte membrane opposite to the first surface, and a volume section where gas generated by the electrochemical cell is collected, the determination device comprising: a current acquisition unit that acquires current information flowing through the electrolyte membrane from a detection signal detected by a detection sensor that detects a current flowing between the first electrode and the second electrode; a pressure acquisition unit that acquires an output signal from a pressure sensor that detects the pressure in the volume section; a deterioration determination unit that determines whether or not the electrolyte membrane is deteriorated based on the current information or the amount of gas generated calculated from the current information and the pressure in the volume section; and a notification unit that notifies the determination result of the deterioration determination unit when it is determined that the electrolyte membrane is deteriorated.

[0009] A second aspect of the present disclosure is an electrochemical apparatus comprising: an electrochemical cell having an electrolyte membrane; a first electrode formed on a first surface of the electrolyte membrane; a second electrode formed on a second surface of the electrolyte membrane opposite to the first surface; a volume section in which the gas generated by the electrochemical cell collects; a detection sensor for detecting a current flowing between the first electrode and the second electrode; a pressure sensor for detecting the pressure in the volume section; a current acquisition unit for acquiring current information flowing through the electrolyte membrane from the detection signal of the detection sensor; and a deterioration determination unit for determining whether the electrolyte membrane is deteriorated based on the current information or the amount of gas generated calculated from the current information and the pressure in the volume section.

[0010] A third aspect of the present disclosure is a method for detecting deterioration of an electrolyte membrane in an electrochemical apparatus having an electrolyte membrane, a first electrode formed on a first surface of the electrolyte membrane, a second electrode formed on a second surface of the electrolyte membrane opposite to the first surface, and a volume section where gas generated in the electrochemical cell collects, the method comprising: acquiring current information flowing through the electrolyte membrane; determining the pressure in the volume section; and determining whether or not the electrolyte membrane is deteriorated based on the current information or the amount of gas generated calculated from the current information and the pressure in the volume section. [Effects of the Invention]

[0011] This disclosure enables the detection of electrolyte membrane degradation based on current information and gas pressure acquired during the normal operation of an electrochemical apparatus. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic diagram of the electrochemical apparatus according to the first embodiment. [Figure 2] Figure 2 is an explanatory diagram of the electrochemical cell in the electrochemical apparatus shown in Figure 1. [Figure 3] Figure 3 is a flowchart illustrating the method for determining the degradation of the electrolyte membrane using the detection device shown in Figure 1. [Figure 4]Figure 4 is a graph showing an example of the change in actual pressure detected by the pressure sensor and the change in pressure calculated from the gas generation rate. [Figure 5] Figure 5 is a flowchart illustrating the method for determining the degradation of the electrolyte membrane in the first modified example. [Figure 6] Figure 6 is a graph showing an example of the difference between the gas generation rate calculated from the amount of electricity and the measured gas generation rate calculated from the pressure. [Figure 7] Figure 7 is a flowchart illustrating the method for determining the degradation of the electrolyte membrane in the second modified example. [Figure 8] Figure 8 is a schematic diagram of the electrochemical module relating to the third modified example. [Figure 9] Figure 9 is a flowchart (fourth modified example) illustrating the method for determining the degradation of an electrolyte membrane using the electrochemical module shown in Figure 8. [Figure 10] Figure 10 is an explanatory diagram of an electrochemical cell according to another embodiment. [Modes for carrying out the invention]

[0013] (First Embodiment) The electrochemical apparatus 10 of this embodiment, shown in Figures 1 and 2, is an electrochemical hydrogen pump that, for example, outputs low-pressure hydrogen gas supplied to the anode 38a as high-pressure hydrogen gas from the cathode 38c. The electrochemical apparatus 10 comprises an electrochemical module 12, an inlet channel 14, an outlet channel 16, a tank 18, a first valve 20, a second valve 22, a pressure sensor 24, a power supply 26, a detection sensor 28, and a determination device 30.

[0014] The electrochemical module 12 comprises a plurality of electrochemical cells 36 between a pair of end plates 34. The plurality of electrochemical cells 36 are arranged stacked in the thickness direction.

[0015] The electrochemical cell 36 includes a pair of separator plates 42 and a membrane electrode assembly (MEA) 38 disposed between the separator plates 42. The separator plates 42 are made of, for example, a corrugated metal plate or the like, and contact the MEA 38 at predetermined locations to support the MEA 38.

[0016] An anode flow path 44 is formed between the separator plate 42 on the anode side and the MEA 38, and a cathode flow path 46 is formed between the separator plate 42 on the cathode side and the MEA 38. The anode flow paths 44 of the plurality of electrochemical cells 36 merge inside the electrochemical module 12 and communicate with the introduction flow path 14. Also, the cathode flow paths 46 of the plurality of electrochemical cells 36 merge inside the electrochemical module 12 and communicate with the outflow flow path 16.

[0017] The MEA 38 includes an electrolyte membrane 40, an anode 38a, and a cathode 38c. In the present embodiment, the electrolyte membrane 40 is a proton-conductive electrolyte membrane. Examples of the material of the electrolyte membrane 40 include Nafion and the like.

[0018] The anode 38a is formed on one surface (first surface) of the electrolyte membrane 40, and the cathode 38c is formed on the other surface (second surface) of the electrolyte membrane 40. The anode 38a is electrically connected to one separator plate 42, and the cathode 38c is electrically connected to the other separator plate 42, so that current is supplied to the electrochemical cell 36 through the separator plate 42. The plurality of electrochemical cells 36 are connected in series through the separator plates 42. Note that the electrochemical cell 36 of the present embodiment is not limited to this, and the MEA 38 may be electrically insulated from the separator plate 42. In this case, as shown in FIG. 8, a power source 26A can be individually connected to each MEA 38.

[0019] When power is supplied to the electrochemical device 10, current flows between the anode 38a and the cathode 38c of the MEA 38. Inside the electrolyte membrane 40, protons (H +Ions are responsible for the transfer of charge, and an amount of protons corresponding to the amount of electric charge (C) is transported from the anode 38a to the cathode 38c. The transported protons are converted into hydrogen gas through an oxidation reaction at the cathode 38c. Since the proton transport proceeds against the pressure difference between the cathode channel 46 and the anode channel 44, hydrogen is pressurized and output to the cathode channel 46. A portion of the hydrogen gas in the cathode channel 46 cross-leaks into the anode channel 44 at a predetermined flow rate through diffusion via the electrolyte membrane 40.

[0020] When the electrochemical apparatus 10 is used for a long period of time, the thickness of the electrolyte membrane 40 may decrease. In this case, the amount of cross-leakage increases. The net amount of hydrogen gas produced, calculated by subtracting the amount of cross-leakage from the amount of hydrogen transported to the cathode channel 46 per unit time relative to the applied current, decreases. Therefore, the current utilization efficiency of the electrochemical apparatus 10 decreases. In addition, the permeability characteristics of the electrolyte membrane 40 may also deteriorate with long-term use. In this case, the amount of hydrogen transported to the cathode channel 46 per unit time decreases. In such cases as well, the net amount of hydrogen produced, calculated by subtracting the amount of cross-leakage from the amount of hydrogen output to the cathode channel 46 per unit time, decreases, and the current utilization efficiency of the electrochemical apparatus 10 decreases. In this embodiment, deterioration refers to a state in the electrolyte membrane 40 that causes a decrease in current utilization efficiency of a predetermined value or more. The method for detecting a deteriorated electrolyte membrane 40 will be described later.

[0021] The introduction channel 14 is connected to the anode channel 44 inside the electrochemical module 12. Low-pressure hydrogen gas is supplied to the introduction channel 14.

[0022] The discharge channel 16 is connected to the cathode channel 46 through an exhaust manifold provided on the end plate 34 of the electrochemical module 12. The discharge channel 16 discharges hydrogen gas from the electrochemical module 12. A tank 18 is connected to the discharge channel 16 through a first valve 20. The first valve 20 is, for example, a back pressure valve, which opens when the pressure on the electrochemical module 12 side increases above a predetermined value, allowing hydrogen gas to flow into the tank 18.

[0023] The second valve 22 is connected to the outflow channel 16 downstream of the tank 18. When closed, the second valve 22 prevents the outflow of hydrogen output from the electrochemical module 12, allowing the hydrogen to be stored in the tank 18. The second valve 22 is opened in response to the demand for high-pressure hydrogen gas. When the second valve 22 is open, hydrogen gas is released from the tank 18 through the outflow channel 16.

[0024] In this embodiment, the cathode channel 46, the tank 18, and the outflow channel 16 up to the second valve 22 are referred to as the volume section. The volume of the volume section is the sum of the volumes of the cathode channel 46, the tank 18, and the outflow channel 16 up to the second valve 22.

[0025] A pressure sensor 24 is provided in the tank 18. The pressure sensor 24 detects the pressure of the hydrogen gas inside the tank 18.

[0026] The power supply 26 supplies power to each electrochemical cell 36 of the electrochemical module 12. The power supply 26 is equipped with a detection sensor 28. The detection sensor 28 detects the current flowing between the anode 38a and cathode 38c of each electrochemical cell 36.

[0027] The determination device 30 comprises an arithmetic unit (processing unit) 48 and a storage unit 50. The arithmetic unit 48 may be composed of a processor, such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), i.e., a processing circuitry.

[0028] The calculation unit 48 includes a current acquisition unit 51, a gas quantity calculation unit 52, a gas generation rate calculation unit 54, a pressure acquisition unit 56, a boost rate calculation unit 58, a deterioration determination unit 60, and a notification unit 62. The current acquisition unit 51, gas quantity calculation unit 52, gas generation rate calculation unit 54, pressure acquisition unit 56, boost rate calculation unit 58, deterioration determination unit 60, and notification unit 62 can be realized by the calculation unit 48 executing a program stored in the storage unit 50.

[0029] Furthermore, at least a portion of the current acquisition unit 51, the gas quantity calculation unit 52, the gas generation rate calculation unit 54, the pressure acquisition unit 56, the boost rate calculation unit 58, the degradation determination unit 60, and the notification unit 62 may be implemented by integrated circuits such as ASICs (Application Specific Integrated Circuits) and FPGAs (Field-Programmable Gate Arrays). Also, at least a portion of the current acquisition unit 51, the gas quantity calculation unit 52, the gas generation rate calculation unit 54, the pressure acquisition unit 56, the boost rate calculation unit 58, the degradation determination unit 60, and the notification unit 62 may be configured by electronic circuits including discrete devices.

[0030] The storage unit 50 may consist of volatile memory and non-volatile memory. Examples of volatile memory include RAM (Random Access Memory). This volatile memory is used as the working memory of the processor and temporarily stores data necessary for processing or calculation. Examples of non-volatile memory include ROM (Read Only Memory) and flash memory. This non-volatile memory is used as storage memory and stores programs, tables, maps, etc. At least a part of the storage unit 50 may be provided in the processor, integrated circuit, etc. as described above.

[0031] The current acquisition unit 51 acquires current information regarding the current flowing through the electrolyte membrane 40 of the electrochemical cell 36 from the detection signal of the detection sensor 28. The current acquisition unit 51 also calculates the cumulative current value flowing through the electrolyte membrane 40 by determining the time-integrated value of the current information. The current acquisition unit 51 calculates the sum of the cumulative current values ​​of multiple electrochemical cells 36 as the amount of electricity (C). The amount of electricity acquired by the current acquisition unit 51 is used to calculate the amount of gas produced.

[0032] The gas quantity calculation unit 52 calculates the amount of gas produced from the detection signal detected by the detection sensor 28. The gas quantity calculation unit 52 calculates the amount of gas produced (mol) based on the amount of electricity acquired by the current acquisition unit 51 and Faraday's law.

[0033] The gas generation rate calculation unit 54 calculates the gas generation rate (mol / hr), which is the amount of gas generated per unit time (hr) (increase rate), by the electrochemical module 12, based on the time change of the amount of gas generated (gas generation amount at multiple time points) calculated by the gas amount calculation unit 52. Depending on the scale of the electrochemical apparatus 10 and the measurement conditions, the unit time can be appropriately determined from seconds (s), minutes (min), hours (hr), etc.

[0034] The pressure acquisition unit 56 acquires the pressure (Pa) of the tank 18 based on the output signal of the pressure sensor 24. When the first valve 20 is open, the pressure of the tank 18 is the same as the pressure of the volume section, so the pressure acquired by the pressure acquisition unit 56 is the same as the pressure of the volume section.

[0035] The pressure boosting rate calculation unit 58 calculates the pressure boosting rate (Pa / hr), which is the rate at which the pressure in the volume section rises per unit time, from the time change of pressure acquired by the pressure acquisition unit 56. The unit time here is the same as the unit time used in the calculation of the gas generation rate.

[0036] The degradation determination unit 60 detects the degradation of the electrolyte membrane 40 based on the gas generation rate and the pressure increase rate. The degradation determination unit 60 calculates the theoretical pressure increase rate (Pa / hr) from the gas generation rate (mol / hr), based on the volume of the volume section (L), the temperature (K), and the ideal gas law. The degradation determination unit 60 determines that the electrolyte membrane 40 has deteriorated if the difference between the theoretical pressure increase rate and the pressure increase rate (measured value) calculated by the pressure increase rate calculation unit 58 is greater than or equal to a predetermined value.

[0037] The notification unit 62 notifies the user or various devices of the determination result of the deterioration determination unit 60.

[0038] The electrochemical apparatus 10 of this embodiment is configured as described above. The operation of the electrochemical apparatus 10 will now be explained.

[0039] As shown in Figure 3, in normal boosting operation, the electrochemical apparatus 10 receives power from the power supply 26 to the electrochemical module 12. When power is supplied, the electrochemical module 12 outputs hydrogen gas introduced from the inlet channel 14 to the outlet channel 16. When the second valve 22 is kept closed, hydrogen gas is gradually accumulated in the volume section including the tank 18, and the pressure in the volume section increases.

[0040] The determination device 30 performs a degradation determination of the electrolyte membrane 40 shown in Figure 3 at appropriate timings during the voltage boosting operation of the electrochemical apparatus 10.

[0041] Degradation of the electrolyte membrane 40 begins in step S1 in Figure 3. In step S1, the determination device 30 calculates the pressure increase rate of the volume section. The pressure increase rate calculation unit 58 calculates an approximate function (linear approximation) of pressure with respect to time based on the pressure and time data (for example, Figure 4) acquired by the pressure acquisition unit 56. The pressure increase rate calculation unit 58 calculates the pressure increase rate from the slope of the approximate function (Figure 4).

[0042] Next, in step S2, the determination device 30 calculates the gas generation rate. The storage unit 50 stores data in which the gas amount calculation unit 52 calculates the gas generation amount based on the amount of electricity acquired by the current acquisition unit 51 and associates it with time. The gas generation rate calculation unit 54 reads the data recording the gas generation amount and time from the storage unit 50, calculates an approximate function (linear approximation) of the gas generation amount with respect to time, and calculates the gas generation rate from the slope of the approximate function.

[0043] Next, in step S3, the determination device 30 calculates the theoretical pressurization rate in the degradation determination unit 60. The degradation determination unit 60 substitutes the gas generation rate n (mol / hr) calculated in step S2, the volume V (L) of the volume section, and the temperature T (K) into the ideal gas law to determine the theoretical pressurization rate, which is the theoretical pressurization rate obtained from the current. As the ideal gas law, for example, the ideal gas law, the van der Waals law, or the virial equation can be used. For example, in the case of the ideal gas law, the theoretical pressurization rate is calculated by nRT / V (where R is the gas constant).

[0044] The degradation determination unit 60 may also calculate the pressure at each time point from the data recording the gas generation amount and time, as shown in Figure 4. In this case, the theoretical pressure increase rate can be determined from the slope of the approximate function (linear approximation) of the calculated pressure and time.

[0045] Next, in step S4, the determination device 30 determines in the deterioration determination unit 60 whether the difference between the theoretical boosting rate obtained in step S3 and the boosting rate obtained in step S1 exceeds a predetermined threshold. If it is determined that the difference exceeds the predetermined threshold (YES), the device proceeds to step S5, where the deterioration determination unit 60 determines that the electrolyte membrane 40 has deteriorated. Subsequently, in step S7, the notification unit 62 notifies the user that the electrolyte membrane 40 has deteriorated.

[0046] Furthermore, if in step S4 it is determined that the difference between the theoretical boosting rate and the boosting rate (measured) is below a predetermined threshold (NO), the process proceeds to step S6, where it is determined that the electrolyte membrane 40 is normal. Subsequently, in step S7, the notification unit 62 notifies the user that the electrolyte membrane 40 is normal. In step S7, the notification unit 62 may also notify the user of the difference between the theoretical boosting rate and the boosting rate (measured) or the current efficiency, along with the determination result.

[0047] As described above, the electrochemical apparatus 10 can detect the deterioration of the electrolyte membrane 40. In this embodiment, the influence of measurement errors can be suppressed by utilizing the pressurization rate and the gas generation rate. As a result, the deterioration of the electrolyte membrane 40 can be determined using data that can be obtained during the normal operation of the electrochemical apparatus 10.

[0048] Furthermore, in this embodiment, the electrochemical apparatus 10 can also predict the operating time required to reach a predetermined threshold by acquiring the time change of the difference between the theoretical boosting rate and the actual boosting rate in the determination device 30. In this case, the maintenance timing of the electrochemical module 12 can be predicted in advance, and the electrochemical apparatus 10 can be operated systematically over a long period of time.

[0049] In the above-described electrochemical apparatus 10, low-pressure hydrogen was supplied to the anode 38a of the electrochemical cell 36, but this embodiment is not limited to this. The electrochemical cell 36 is configured as a PEM-type water electrolysis cell. In this case, water is supplied to the anode 38a and electrolysis is performed, generating oxygen gas at the anode 38a and hydrogen gas at the cathode 38c. High-pressure hydrogen gas can be obtained by connecting the tank 18 to the cathode channel 46 through the outflow channel 16. Even with such an electrochemical cell 36, the determination device 30 can detect the deterioration of the electrolyte membrane 40 based on the relationship between current information and the pressure of the high-pressure hydrogen gas.

[0050] The following describes various modified versions of the electrochemical apparatus 10 of this embodiment.

[0051] (First variation) As shown in Figure 5, this modified example relates to another example of a method for determining the degradation of the electrolyte membrane 40 performed by the determination device 30.

[0052] In this modified example, first, in step S11, the boost rate calculation unit 58 calculates the boost rate. The contents of step S11 are the same as in step S1 in Figure 3.

[0053] Next, in step S12 of Figure 5, the gas generation rate calculation unit 54 calculates the gas generation rate. The content of step S12 is the same as step S2 of Figure 3. As shown in Figure 6, the gas generation rate is obtained from the slope of the approximate function between time and gas generation amount.

[0054] Next, in step S13, the determination device 30 calculates the measured gas production rate per unit time (mol / hr) based on the pressurization rate obtained in step S11. The measured gas production rate is calculated by substituting the pressurization rate (dP / dt), the volume of the volume section (V), and the temperature (T) into the ideal gas law for hydrogen gas. For example, when using the ideal gas law with R as the gas constant, the measured gas production rate is obtained as (dP / dt) × V / RT.

[0055] Even when the electrolyte membrane 40 is functioning normally, cross-leakage occurs, so as shown in Figure 6, the measured gas generation rate is lower than the gas generation rate calculated from the amount of electricity.

[0056] Next, in step S14, the degradation determination unit 60 of the determination device 30 determines whether the difference between the gas generation rate and the measured gas generation rate exceeds a predetermined threshold. If the degradation determination unit 60 determines in step S14 that the difference exceeds the predetermined threshold (YES), the degradation determination unit 60 proceeds to step S15. In step S15, the degradation determination unit 60 determines that the electrolyte membrane 40 has deteriorated, and then in step S17, the notification unit 62 notifies the user or the like that the electrolyte membrane 40 has deteriorated.

[0057] On the other hand, if the degradation determination unit 60 determines in step S14 that the degradation determination unit does not exceed a predetermined threshold (NO), the degradation determination unit 60 proceeds to step S16. In step S16, the degradation determination unit 60 determines that the electrolyte membrane 40 is normal, and then in step S17, the notification unit 62 notifies the user that the electrolyte membrane 40 is normal.

[0058] As described above, in this modified example, the degradation of the electrolyte membrane 40 can be detected by calculating the measured gas generation rate instead of the theoretical pressure increase rate.

[0059] (Second variation) As shown in Figure 7, this modified example relates to yet another example of a method for determining the degradation of the electrolyte membrane 40 performed by the determination device 30.

[0060] In this modified example, first, in step S21, the determination device 30 obtains the ratio of the current value I supplied to the electrochemical module 12 immediately after manufacturing to the boost rate dP / dt as a reference value A (=dP / dt)÷I. The current value supplied to the electrochemical module 12 is determined as the sum of the currents flowing through each electrochemical cell 36. If the electrochemical cells 36 are connected in series, the current value I supplied to the electrochemical module 12 is obtained by multiplying the current based on the detection signal of the detection sensor 28 by the number of electrochemical cells 36. The current value I is to be kept constant within the range used to calculate the reference value A. The boost rate dP / dt is a measured value obtained based on the detection signal of the pressure sensor 24.

[0061] Next, in step S22, the determination device 30 obtains the ratio of the current value I supplied to the electrochemical module 12 during normal operation to the boost rate dP / dt as the measured value B (=(dP / dt) / I). The measured value B in step S22 differs from that in step S21 in that it is obtained from measurement data of the electrochemical module 12 after some time has passed since the start of operation, rather than immediately after manufacture. The method for obtaining the current value I and the boost rate dP / dt in step S22 is the same as in step S21. If the amount of cross-leakage increases due to deterioration of the electrolyte membrane 40, the boost rate dP / dt decreases, and therefore the measured value B decreases in accordance with the deterioration of the electrolyte membrane 40.

[0062] Next, in step S23, the deterioration determination unit 60 determines whether the difference between the reference value A and the measured value B exceeds a predetermined value. If it is determined in step S23 that the difference between the reference value A and the measured value B exceeds a predetermined value (YES), the deterioration determination unit 60 proceeds to step S24 and determines that the electrolyte membrane 40 has deteriorated. Subsequently, in step S26, the notification unit 62 notifies the user that the electrolyte membrane 40 has deteriorated.

[0063] Furthermore, in step S23, if it is determined that the difference between the reference value A and the measured value B does not exceed a predetermined value (NO), the deterioration determination unit 60 proceeds to step S25 and determines that the electrolyte membrane 40 is normal. Subsequently, in step S26, the notification unit 62 notifies the user that the electrolyte membrane 40 is normal.

[0064] As described above, in this modified example, the degradation of the electrolyte membrane 40 can be detected based on the current value I and the boosting rate dP / dt, even without using the volume V of the volume section. Furthermore, by determining the time course of the measured value B, it is possible to predict the degradation of the electrolyte membrane 40, which is preferable for predicting the maintenance timing of the electrochemical module 12.

[0065] (Third variation) As shown in Figure 8, this modified example describes an electrochemical module 12A and power supply 26A relating to another configuration example. Note that the components other than the electrochemical module 12A, power supply 26A, and detection sensor 28A can be used by replacing the electrochemical module 12, power supply 26, and detection sensor 28 of the electrochemical apparatus 10 in Figure 1.

[0066] As shown in the figure, the electrochemical module 12A comprises a plurality of electrochemical cells 36 arranged between a pair of end plates 34. The plurality of electrochemical cells 36 are stacked in the thickness direction. In the electrochemical module 12A, adjacent electrochemical cells 36 in the thickness direction are electrically insulated from each other.

[0067] There are as many 26A power supplies as there are electrochemical cells 36. Each 26A power supply supplies current to one electrochemical cell 36. Each 26A power supply is equipped with a detection sensor 28A. The detection sensor 28A detects the current flowing through each individual electrochemical cell 36.

[0068] In this modified example, the amount of electricity (C) can be determined by summing the integrated values ​​of the currents flowing through the individual electrochemical cells 36. By obtaining the current flowing inside each individual electrochemical cell 36 in this way, the amount of hydrogen gas generated (mol) can be calculated more accurately. That is, depending on the location of the electrochemical cell 36, variations may occur due to drying or excess moisture in the anode 38a, cathode 38c, and electrolyte membrane 40, and the current flowing through each individual electrochemical cell 36 may differ. In such cases, if the supply current value for the entire electrochemical module 12A is used, the current flowing through each individual electrochemical cell 36 will not be accurately reflected in the current information. As in this modified example, by using the detection results of the current values ​​of the electrochemical cells 36, the influence of moisture is eliminated.

[0069] In the electrochemical module 12A of this modified example, degradation of the electrolyte membrane 40 can also be detected by the method described with reference to Figures 3, 5, or 7.

[0070] (Fourth variation) The modified example shown in Figure 9 is a method for detecting the degradation of individual electrolyte membranes 40 using the electrochemical module 12A shown in Figure 8. In the conventional method, it is not possible to determine which electrochemical cell 36's electrolyte membrane 40 has degraded in an electrochemical module 12 having multiple electrochemical cells 36. Therefore, the degradation determination method of this modified example will be described as a method that makes it possible to determine which electrolyte membrane 40 has degraded. The following explanation assumes that the electrochemical module 12 and power supply 26 of the electrochemical apparatus 10 in Figure 1 have been replaced with the electrochemical module 12A and power supply 26A shown in Figure 8.

[0071] First, as shown in step S31, the determination device 30 (see Figure 1) supplies current to the first electrochemical cell 36 through the first power supply 26A. In step S31, no current is supplied to the other electrochemical cells 36.

[0072] Next, in step S32, the boost rate calculation unit 58 (see Figure 1) calculates the boost rate of the volume section. The boost rate calculation unit 58 determines the boost rate of the volume section using the same operation as in step S1 in Figure 3.

[0073] Next, in step S33, the gas generation rate calculation unit 54 (see Figure 1) calculates the amount of electricity (C) flowing through the first electrochemical cell 36 and the gas generation rate of hydrogen gas generated per unit time (mol / hr) based on Faraday's law.

[0074] Next, in step S34, the pressurization rate calculation unit 58 calculates the theoretical pressurization rate (Pa / hr) based on the gas generation rate obtained in step S33, the volume of the volume section, the temperature, and the ideal gas law for hydrogen gas.

[0075] Next, in step S35, the degradation determination unit 60 determines whether the difference between the theoretical boosting rate and the boosting rate (measured) exceeds a predetermined threshold. If it is determined in step S35 that the difference exceeds the predetermined threshold (YES), the degradation determination unit 60 proceeds to step S36 and determines that the first electrolyte membrane 40 through which current was passed may be degraded. If the difference value in step S35 is less than or equal to the predetermined threshold (NO), the degradation determination unit 60 proceeds to step S37 and determines that the first electrolyte membrane 40 through which current was passed is normal.

[0076] Subsequently, in step S38, the notification unit 62 notifies the result of the degradation determination of the electrolyte membrane 40.

[0077] Next, in step S39, the determination device 30 determines whether or not the degradation determination of all electrochemical cells 36 has been completed. If the degradation determination of all electrochemical cells 36 has not been completed (NO), the process proceeds to step S40, the counter specifying the electrochemical cells 36 to be determined is advanced by one, and the process returns to step S31. Thereafter, the process from steps S31 to S40 is repeated until the degradation determination of all electrochemical cells 36 is completed. If the determination in step S39 is YES, the process ends.

[0078] The degradation determination method of this modified example enables the detection of electrolyte membrane 40 with deteriorated permeability characteristics.

[0079] (Other embodiments) The above explanation uses the example of an electrochemical hydrogen pump in which the electrochemical cell 36 electrochemically pressurizes hydrogen gas, but the above disclosure is not limited to this.

[0080] In the electrochemical apparatus 10 of Figure 1, the same effect can be obtained by replacing the electrochemical cell 36 with the electrochemical cell 36B shown in Figure 10. The electrochemical cell 36B in Figure 10 uses an anion-conducting electrolyte membrane that conducts hydroxide ions as the electrolyte membrane 40B. In the electrochemical cell 36B, water or superhumidified hydrogen is supplied to the cathode 38c. The water supplied to the cathode 38c is electrolyzed to generate hydrogen at the cathode 38c. Oxygen is transported through the electrolyte membrane 40B as hydroxide ions, and oxygen gas is generated at the anode 38a. The anode channel 44 is connected to the tank 18 through the outflow channel 16. In the embodiment of Figure 10, oxygen gas is the first gas, and the volume section is composed of the anode channel 44, the outflow channel 16, and the tank 18. In this case as well, deterioration of the electrolyte membrane 40B is detected based on the current information flowing through the electrochemical cell 36B and the pressure in the volume section (oxygen gas pressure).

[0081] With regard to the above embodiments, the following additional information is disclosed.

[0082] (Note 1) The determination device (30) of the present disclosure is a determination device for determining the deterioration of an electrolyte membrane in an electrochemical apparatus (10) which includes an electrolyte membrane (40), an electrochemical cell (36) having a first electrode formed on a first surface of the electrolyte membrane, and a second electrode formed on a second surface of the electrolyte membrane opposite to the first surface, and a volume section where the gas generated by the electrochemical cell is collected, and comprises: a current acquisition unit (51) that acquires current information flowing through the electrolyte membrane from a detection signal detected by a detection sensor (28) that detects a current flowing between the first electrode and the second electrode; a pressure acquisition unit (56) that acquires an output signal from a pressure sensor (24) that detects the pressure in the volume section; a deterioration determination unit (60) that determines whether or not the electrolyte membrane is deteriorated based on the current information or the amount of gas generated calculated from the current information and the pressure in the volume section; and a notification unit (62) that notifies the determination result of the deterioration determination unit when it is determined that the electrolyte membrane is deteriorated.

[0083] The above-described determination device can detect the deterioration of the electrolyte membrane by utilizing current information obtained during the normal operation of the electrochemical apparatus and the pressure of the volume section.

[0084] (Note 2) The determination device described in Appendix 1 may include a gas quantity calculation unit (52) that calculates the gas production amount based on the amount of electricity obtained from the current information. This determination device can accurately determine the gas production amount from the current information and detect the deterioration of the electrolyte membrane by comparing it with physical quantities such as the pressure in the volume section.

[0085] (Note 3) The determination device described in Appendix 2 further includes a gas generation rate calculation unit (54) that calculates a gas generation rate, which is the rate of increase of the gas generation amount, based on the gas generation amount at multiple time points, and a pressure boost rate calculation unit (58) that calculates a pressure boost rate (dp / dt), which is the rate of increase of the pressure, based on the pressure at multiple time points, wherein the deterioration determination unit may determine whether or not the electrolyte membrane is deteriorated based on the gas generation rate and the pressure boost rate. This determination device can accurately evaluate the characteristics of the electrolyte membrane by suppressing the effects of offsets and variations in the gas generation amount and pressure.

[0086] (Note 4) The determination device described in Appendix 3, wherein the deterioration determination unit determines the theoretical pressure-boosting rate of the gas based on the gas generation rate and the volume of the volume section, and if the difference between the theoretical pressure-boosting rate and the actual pressure-boosting rate is greater than or equal to a predetermined value, it may be determined that the electrolyte membrane has deteriorated. This determination device can detect the deterioration of the electrolyte membrane by comparing the pressure-boosting rate calculated from current information with the pressure-boosting rate based on actual measurements.

[0087] (Note 5) The determination device described in Appendix 3, wherein the deterioration determination unit determines the actual gas generation rate of the gas based on the pressure boosting rate and the volume of the volume section, and if the difference between the gas generation rate and the actual gas generation rate is greater than or equal to a predetermined value, it may be determined that the electrolyte membrane has deteriorated. This determination device enables the detection of electrolyte membrane deterioration by converting the actual pressure boosting rate into a gas generation amount, thereby comparing it with the gas generation amount obtained from current information.

[0088] (Note 6) The determination device described in Appendix 2 may include a plurality of electrochemical cells, the current acquisition unit acquires the current flowing through each of the electrochemical cells, and the gas amount calculation unit calculates the gas production amount from the sum of the currents. This determination device can eliminate the influence of variations in the amount of electricity due to drying or excessive humidity of the electrochemical cells and can improve the accuracy of calculating the gas production amount based on current information.

[0089] (Note 7) The determination device described in Appendix 1 may include a pressure-boosting rate calculation unit that calculates a pressure-boosting rate, which is the rate at which the pressure increases, based on the pressure at multiple times, and the deterioration determination unit may determine whether or not the electrolyte membrane has deteriorated based on the relationship between the current information and the pressure-boosting rate. This determination device can determine the deterioration of the electrolyte membrane without determining the volume of the volume section.

[0090] (Note 8) The electrochemical apparatus of the present disclosure comprises an electrochemical cell having an electrolyte membrane, a first electrode formed on a first surface of the electrolyte membrane, and a second electrode formed on a second surface of the electrolyte membrane opposite to the first surface; a volume section in which the gas generated by the electrochemical cell collects; a detection sensor for detecting a current flowing between the first electrode and the second electrode; a pressure sensor for detecting the pressure in the volume section; a current acquisition unit for acquiring current information flowing through the electrolyte membrane from the detection signal of the detection sensor; and a deterioration determination unit for determining whether the electrolyte membrane is deteriorated based on the current information or the amount of gas generated calculated from the current information and the pressure in the volume section.

[0091] (Note 9) The electrochemical apparatus described in Appendix 8 may be such that the electrochemical cell generates hydrogen in the volume section by electrolyzing water.

[0092] (Note 10) The electrochemical apparatus described in Appendix 9, wherein the electrochemical cell may be an electrochemical hydrogen pump that boosts the low-pressure hydrogen gas supplied to the second electrode to the volume section and outputs it.

[0093] (Note 11) The electrochemical apparatus described in Appendix 10 may include an outflow channel (16) that communicates with the first electrode and discharges the gas from the electrochemical cell, and a tank (18) connected to the outflow channel. This electrochemical apparatus can suppress detection errors in the rate of pressure increase by increasing the volume of the tank.

[0094] (Note 12) The degradation detection method of the present disclosure is a method for detecting degradation of an electrolyte membrane in an electrochemical apparatus having an electrolyte membrane, a first electrode formed on a first surface of the electrolyte membrane, a second electrode formed on a second surface of the electrolyte membrane opposite to the first surface, and a volume section where gas generated in the electrochemical cell collects, and comprises the steps of: acquiring current information flowing through the electrolyte membrane; determining the pressure in the volume section; and determining whether the electrolyte membrane is degraded based on the current information or the amount of gas generated calculated from the current information and the pressure in the volume section. This degradation detection method can detect degradation of the electrolyte membrane from current information and pressure acquired during normal operation of the electrochemical apparatus.

[0095] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of Symbols]

[0096] 10... Electrochemical apparatus 12, 12A... Electrochemical module 16…Outlet channel 18…Tank 24...Pressure sensor 26, 26A...Power supply 28, 28A...Detection sensor 30...Determination device 36, 36B…Electrochemical cell; 40, 40B…Electrolyte membrane 52...Gas quantity calculation unit 54...Gas generation rate calculation unit 56...Pressure acquisition unit 58...Pressure boosting rate calculation unit 60...Deterioration detection unit 62...Notification unit

Claims

1. An electrochemical apparatus comprising an electrochemical cell having an electrolyte membrane, a first electrode formed on a first surface of the electrolyte membrane, a second electrode formed on a second surface of the electrolyte membrane opposite to the first surface, and a volume section where the gas generated by the electrochemical cell collects, wherein the apparatus is a determination device for determining the deterioration of the electrolyte membrane, A current acquisition unit acquires current information flowing through the electrolyte membrane from a detection signal detected by a detection sensor that detects the current flowing between the first electrode and the second electrode, A pressure acquisition unit that acquires the output signal of a pressure sensor that detects the pressure in the volume section, A deterioration determination unit that determines whether or not the electrolyte membrane is deteriorated based on the current information or the amount of gas generated calculated from the current information and the pressure in the volume section, A determination device comprising: a notification unit that notifies the determination result of the deterioration determination unit when it is determined that the electrolyte membrane is deteriorated.

2. A determination device according to claim 1, comprising a gas quantity calculation unit that calculates the amount of gas generated based on the amount of electricity obtained from the current information.

3. The determination device according to claim 2, further, A gas generation rate calculation unit calculates the gas generation rate, which is the rate of increase of the gas generation amount, based on the gas generation amount at multiple time points, The system includes a pressure-boosting rate calculation unit that calculates a pressure-boosting rate, which is the rate at which the pressure increases, based on the pressure at multiple times, The deterioration determination unit is a determination device that determines whether or not the electrolyte membrane is deteriorated based on the gas generation rate and the pressure increase rate.

4. A determination device according to claim 3, The deterioration determination unit determines the theoretical pressure-boosting rate of the gas based on the gas generation rate and the volume of the volume section, and determines that the electrolyte membrane has deteriorated if the difference between the theoretical pressure-boosting rate and the pressure-boosting rate is greater than or equal to a predetermined value.

5. A determination device according to claim 3, The deterioration determination unit determines the actual gas generation rate of the gas based on the pressure boosting rate and the volume of the volume section, and determines that the electrolyte membrane has deteriorated if the difference between the gas generation rate and the actual gas generation rate is greater than or equal to a predetermined value.

6. A determination device according to claim 2, The electrochemical apparatus comprises a plurality of electrochemical cells, The current acquisition unit acquires the current flowing through each of the electrochemical cells, The gas quantity calculation unit is a determination device that calculates the amount of gas produced from the sum of the currents.

7. A determination device according to claim 1, The system includes a pressure boost rate calculation unit that calculates a pressure boost rate, which is the rate at which the pressure increases, based on the pressure at multiple times. The deterioration determination unit is a determination device that determines whether or not the electrolyte membrane has deteriorated based on the relationship between the current information and the voltage boosting rate.

8. An electrochemical cell having an electrolyte membrane, a first electrode formed on a first surface of the electrolyte membrane, and a second electrode formed on a second surface of the electrolyte membrane opposite to the first surface, The volume section where the gas generated by the electrochemical cell collects, A detection sensor for detecting the current flowing between the first electrode and the second electrode, A pressure sensor for detecting the pressure in the volume section, A current acquisition unit that acquires current information flowing through the electrolyte membrane from the detection signal of the detection sensor, An electrochemical apparatus comprising: a deterioration determination unit that determines whether or not the electrolyte membrane is deteriorated based on the current information or the amount of gas generated calculated from the current information and the pressure in the volume section.

9. An electrochemical apparatus according to claim 8, wherein the electrochemical cell generates hydrogen in the volume section by electrolyzing water.

10. An electrochemical apparatus according to claim 9, wherein the electrochemical cell is an electrochemical hydrogen pump that pressurizes and outputs low-pressure hydrogen gas supplied to the second electrode to the volume section.

11. The electrochemical apparatus according to claim 10, wherein the volume section is An outflow channel that communicates with the first electrode and discharges the gas from the electrochemical cell, An electrochemical apparatus comprising a tank connected to the aforementioned outflow channel.

12. A method for detecting deterioration of an electrolyte membrane in an electrochemical apparatus, comprising: an electrochemical cell having an electrolyte membrane; a first electrode formed on a first surface of the electrolyte membrane; a second electrode formed on a second surface of the electrolyte membrane opposite to the first surface; and a volume section where gas generated in the electrochemical cell collects, wherein The steps include: acquiring information on the current flowing through the electrolyte membrane; The steps include determining the pressure in the volume section, A degradation detection method comprising the step of determining whether or not the electrolyte membrane is degraded based on the current information or the amount of gas generated calculated from the current information and the pressure in the volume section.

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