Water electrolysis evaluation device, water electrolysis evaluation method, and water electrolysis evaluation program

Abstract

The present invention provides a water electrolysis evaluation device 100 for evaluating a water electrolysis device W, which evaluates the water electrolysis device while appropriately taking care of a mixed gas of an oxygen gas and a hydrogen gas generated by crossover. The water electrolysis evaluation device 100 comprises: a gas flow path 41 through which an exhaust gas discharged from the water electrolysis device W flows; a sensor 81 that is provided in the gas flow path 41 and measures the flow rate or concentration of the exhaust gas; a dilution gas supply unit 82 that supplies a dilution gas to the gas flow path 41 so as to dilute the exhaust gas; and a flow rate control unit 83 that controls the flow rate of the dilution gas supplied from the dilution gas supply unit 82 to the gas flow path 41 on the basis of the measurement value of the sensor 81.

Description

Water electrolysis evaluation device, water electrolysis evaluation method, and water electrolysis evaluation program

[0001] The present invention relates to a water electrolysis evaluation device, a water electrolysis evaluation method, and a water electrolysis evaluation program.

[0002] In recent years, as shown in Patent Document 1, research and development of water electrolysis devices such as PEM (Polymer Electrolyte Membrane) type have been underway.

[0003] For example, a PEM type water electrolysis device is composed of a plurality of water electrolysis cells each having an anode disposed on one side and a cathode disposed on the other side with a solid polymer electrolyte membrane (PEM) sandwiched therebetween. And water is discharged from the anode side of the water electrolysis device together with oxygen gas, and water is discharged from the cathode side together with hydrogen gas.

[0004] As a method for evaluating this water electrolysis device, for example, operating the water electrolysis device under various conditions and analyzing the oxygen gas or hydrogen gas discharged from the water electrolysis device at that time, or analyzing the water discharged together with the oxygen gas or hydrogen gas, etc. can be considered.

[0005] Japanese Unexamined Patent Application Publication No. 2022-29892

[0006] By the way, there are cases where the hydrogen gas generated on the cathode side permeates through the PEM and hydrogen gas is discharged from the anode side together with oxygen gas. Similarly, although generated on the anode side, oxygen gas may permeate through the PEM and oxygen gas is discharged from the cathode side together with hydrogen gas. Such a phenomenon in which the gas on the anode side and the gas on the cathode side are mixed with each other is called crossover. Here, in a mixed gas of hydrogen gas and oxygen gas, there are problems such as an explosion limit, so it is necessary to perform appropriate exhaust treatment.

[0007] Therefore, the present invention has been made in view of the above problems, and the main problem is to evaluate the water electrolysis device while appropriately treating the mixed gas of oxygen gas and hydrogen gas (crossover gas) generated by crossover.

[0008] In other words, the water electrolysis evaluation apparatus according to the present invention is a water electrolysis evaluation apparatus for evaluating a water electrolysis apparatus that generates oxygen gas and hydrogen gas by electrolyzing water, and is characterized by comprising: a gas flow path through which exhaust gas containing the oxygen gas or hydrogen gas discharged from the anode or cathode of the water electrolysis apparatus flows; a sensor provided in the gas flow path for measuring the flow rate or concentration of the exhaust gas; a dilution gas supply unit for supplying dilution gas to the gas flow path to dilute the exhaust gas; and a flow rate control unit that controls the flow rate of the dilution gas supplied from the dilution gas supply unit to the gas flow path based on the measurement value of the sensor.

[0009] With such a water electrolysis evaluation device, the flow rate or concentration of exhaust gas containing oxygen or hydrogen gas discharged from the anode or cathode of the water electrolysis device is measured, and the flow rate of dilution gas supplied from the dilution gas supply unit to the gas flow path is controlled based on the measured value. This ensures that the mixed gas of oxygen and hydrogen gas generated by the crossover is reliably diluted to a concentration below the explosion limit. As a result, the water electrolysis device can be evaluated while appropriately processing the mixed gas of oxygen and hydrogen gas generated by the crossover.

[0010] Preferably, the gas flow path is connected to the anode of the water electrolysis device. With this configuration, the concentration of crossover gas (hydrogen gas) contained in the oxygen gas discharged from the anode can be diluted to a concentration below the explosion limit.

[0011] In a specific implementation, it is desirable that the sensor measures the flow rate of the exhaust gas, the dilution gas supply unit is connected downstream of the sensor in the gas flow path, and the flow rate control unit controls the flow rate of the dilution gas supplied from the dilution gas supply unit to the gas flow path based on the measurement value of the sensor.

[0012] One possible specific implementation of the flow control unit is to control the flow rate of the dilution gas based on the measurement value of the sensor so that the dilution ratio of the exhaust gas remains constant.

[0013] Preferably, the sensor is installed downstream of the connection point of the dilution gas supply unit in the gas flow path and measures the concentration of the crossover gas contained in the exhaust gas. With this configuration, the concentration of the crossover gas obtained by the sensor can be fed back to control the flow rate of the dilution gas supplied from the dilution gas supply unit to the gas flow path. As a result, the crossover gas can be reliably diluted to a concentration below the explosion limit.

[0014] Preferably, two of the aforementioned sensors are provided, one for high concentrations and the other for low concentrations. With this configuration, the concentration of the crossover gas after dilution can be measured with high accuracy.

[0015] The water electrolysis evaluation apparatus of the present invention further comprises a gas-liquid separation tank provided in the gas flow path, and the sensor is provided downstream of the gas-liquid separation tank in the gas flow path. With this configuration, the flow rate or concentration of the exhaust gas from which water has been removed by the gas-liquid separation tank is measured, and the flow rate of the dilution gas supplied to the gas flow path can be controlled with high precision.

[0016] In the aforementioned gas flow path, it is desirable to provide a heat exchanger for cooling the exhaust gas upstream of the gas-liquid separation tank. With this configuration, the exhaust gas can be cooled to below the dew point temperature by the heat exchanger, and the water vapor contained in the exhaust gas can be efficiently separated by the gas-liquid separation tank.

[0017] Examples of water electrolysis devices used as test specimens for the water electrolysis evaluation apparatus of the present invention include PEM (Polymer Electrolyte Membrane) type water electrolysis devices.

[0018] Furthermore, the water electrolysis evaluation method according to the present invention is a water electrolysis evaluation method for evaluating a water electrolysis apparatus that generates oxygen gas and hydrogen gas by electrolyzing water, characterized in that the flow rate or concentration of exhaust gas flowing through a gas channel connected to the anode or cathode of the water electrolysis apparatus is measured by a sensor, and a dilution gas is supplied to the gas channel by a dilution gas supply unit to dilute the exhaust gas, and the flow rate of the dilution gas supplied from the dilution gas supply unit to the gas channel is controlled based on the measurement value of the sensor.

[0019] Furthermore, the water electrolysis evaluation program according to the present invention is for evaluating a water electrolysis apparatus that generates oxygen gas and hydrogen gas by electrolyzing water, and is used in a water electrolysis evaluation apparatus comprising a gas flow path through which exhaust gas containing the oxygen gas or hydrogen gas discharged from the anode or cathode of the water electrolysis apparatus flows, a sensor provided in the gas flow path for measuring the flow rate or concentration of the exhaust gas, and a dilution gas supply unit for supplying dilution gas to the gas flow path to dilute the exhaust gas, wherein the program is equipped with a computer that functions as a flow control unit that controls the flow rate of the dilution gas supplied from the dilution gas supply unit to the gas flow path based on the measurement value of the sensor.

[0020] According to the present invention configured in this way, it is possible to evaluate a water electrolysis device while appropriately processing the mixed gas of oxygen and hydrogen gas generated by the crossover.

[0021] This is a schematic diagram showing the configuration of a water electrolysis evaluation apparatus according to one embodiment of the present invention. This is a schematic diagram showing the configuration of the water supply section of the same embodiment. This is a schematic diagram showing the configuration of the anode-side gas discharge section of the same embodiment. This is a schematic diagram showing the configuration of the cathode-side gas discharge section of the same embodiment. This is a functional block diagram of the control device of the same embodiment.

[0022] Hereinafter, a water electrolysis evaluation apparatus according to one embodiment of the present invention will be described with reference to the drawings. Note that all the following drawings are schematic representations, with some parts omitted or exaggerated for clarity. The same components are denoted by the same reference numerals, and their descriptions are omitted as appropriate.

[0023] <Configuration of the Water Electrolysis Evaluation Apparatus 100> The water electrolysis evaluation apparatus 100 of this embodiment is an apparatus for evaluating water electrolysis devices such as PEM (Polymer Electrolyte Membrane: solid polymer electrolyte membrane) type water electrolysis devices.

[0024] The following describes an example of evaluating a water electrolysis stack, which is part of a water electrolysis apparatus. Here, as shown in Figure 1, the water electrolysis stack W is constructed by stacking multiple water electrolysis cells, each having an anode W1 on one side and a cathode W2 on the other side of a solid polymer electrolyte membrane (PEM) W3.

[0025] As shown in Figure 1, the water electrolysis evaluation apparatus 100 is an evaluation device for evaluating the water electrolysis stack W, which is a test specimen. It includes a power supply unit 2 that applies voltage to the water electrolysis stack W, a water supply unit 3 that supplies water to the anode W1 of the water electrolysis stack W, an anode-side gas discharge unit 4 that discharges exhaust gas containing oxygen gas (hereinafter referred to as anode-side gas) discharged from the anode W1 of the water electrolysis stack W, and a cathode-side gas discharge unit 5 that discharges exhaust gas containing hydrogen gas (hereinafter referred to as cathode-side gas) discharged from the cathode W2 of the water electrolysis stack W.

[0026] Furthermore, the water electrolysis evaluation apparatus 100 of this embodiment has a test specimen housing section 6 that houses the water electrolysis stack W, and the temperature and pressure inside the test specimen housing section 6 are configured to be adjustable. In addition, the water electrolysis evaluation apparatus 100 has a pressure adjustment section 7 that adjusts the pressure on the cathode side from low pressure to high pressure.

[0027] The following describes each of the parts 2 to 5 in detail. The power supply unit 2 applies a DC voltage to the anode W1 and cathode W2 of the water electrolysis stack W, causing the water electrolysis stack W to perform water electrolysis. This power supply unit 2 can change the DC voltage applied to the water electrolysis stack W to a predetermined value (for example, between 0 and 30V). The power supply unit 2 can also change the DC current supplied to the water electrolysis stack W to a predetermined value (for example, between 0 and 1200A).

[0028] As shown in Figure 2, the water supply unit 3 includes a water supply channel 31 connected to a water supply port P1 provided on the anode W1 of the water electrolysis stack W, a pump 32 provided in the water supply channel 31 for pressurizing water, and a preheating tank 33 provided in the water supply channel 31 for preheating the water supplied to the water supply port P1 to a predetermined temperature (for example, a temperature between room temperature and 90°C).

[0029] Furthermore, the water supply unit 3 may be equipped with a flow sensor 34 downstream of the pump 32 in the water supply channel 31, and control the pump 32, etc., based on the flow rate measured by the flow sensor 34 to adjust the amount of water supplied to the anode W1. In addition, the water supply channel 31 may be equipped with a temperature sensor (TM, TC) for measuring the water temperature, or a pressure sensor (PS) for measuring the water supply pressure, as needed. Furthermore, at least the downstream side of the preheating tank 33 in the water supply channel 31 may be heated or maintained at a predetermined temperature (for example, room temperature to 90°C) by a heater 10, etc.

[0030] As shown in Figure 3, the anode-side gas discharge section 4 is connected to an exhaust port P2 provided on the anode W1 of the water electrolysis stack W and includes an anode-side gas flow path 41 for discharging anode-side gas and a gas-liquid separation mechanism 42 provided in the anode-side gas flow path 41 for separating water discharged together with the anode-side gas.

[0031] In addition, the anode gas flow path 41 may be equipped with, as needed, a temperature sensor (TM, TC) for measuring the temperature of the anode gas, a pressure sensor (PS) for measuring the pressure of the anode gas, a flow sensor 43 for measuring the flow rate of the anode gas that has passed through the gas-liquid separation mechanism 42, a hydrogen sensor 44 for measuring the concentration of hydrogen gas contained in the anode gas that has passed through the gas-liquid separation mechanism 42, or an oxygen sensor for measuring the concentration of oxygen gas contained in the anode gas that has passed through the gas-liquid separation mechanism 42.

[0032] The gas-liquid separation mechanism 42 includes a first gas-liquid separation section 421, which is a first storage section that separates water (mainly liquid water) discharged together with the anode gas, and a second gas-liquid separation section 422, which is a second storage section that separates water (mainly water vapor) contained in the anode gas that has passed through the first gas-liquid separation section 421.

[0033] The first gas-liquid separation unit 421 includes a first heat exchanger 421a for cooling the anode-side gas, and a first gas-liquid separation tank 421b for condensing and separating water vapor contained in the anode-side gas cooled by the first heat exchanger 421a along with liquid water. The water stored in the first gas-liquid separation tank 421b is returned to the water supply unit 3 by the water return channel 70 and supplied again to the water supply port P1 of the anode W1. In other words, the first gas-liquid separation tank 421b functions as a circulation tank. The water return channel 70 may also be heated or maintained at a predetermined temperature (for example, room temperature to 90°C) by a heater 10 or the like.

[0034] The second gas-liquid separation unit 422 includes a second heat exchanger 422a that cools the anode-side gas that has passed through the first gas-liquid separation unit 421, and a second gas-liquid separation tank 422b that condenses and separates the water vapor contained in the anode-side gas cooled by the second heat exchanger 422a.

[0035] Furthermore, the first gas-liquid separation tank 421b and the second gas-liquid separation tank 422b are each equipped with a water level sensor 45, and a drainage channel 46 for discharging the stored water is connected to them. This drainage channel 46 is equipped with a fluid control valve 47 that is controlled based on the water level detected by the water level sensor 45. For example, the fluid control valve 47 is controlled so that the water level in each tank 421b and 422b is 10% to 70% of the maximum water level (height) in the tank, more preferably 25% to 45% of the maximum water level in the tank. In addition, the first gas-liquid separation tank 421b and the second gas-liquid separation tank 422b have a double-wall structure consisting of an inner wall and an outer wall, and cooling water is supplied between the inner wall and the outer wall. Moreover, in the anode-side gas flow path 41, the temperature is maintained by an insulating material 11 at least up to the second heat exchanger 422a.

[0036] As shown in Figure 4, the cathode-side gas discharge section 5 is connected to an exhaust port P3 provided on the cathode W2 of the water electrolysis stack W and has a cathode-side gas flow path 51 for discharging cathode-side gas and a gas-liquid separation mechanism 52 provided in the cathode-side gas flow path 51 for separating water discharged together with the cathode-side gas.

[0037] In addition, the cathode-side gas flow path 51 may be equipped with, as needed, a temperature sensor (TM, TC) for measuring the temperature of the cathode-side gas, a pressure sensor (PS) for measuring the pressure of the cathode-side gas, a flow rate sensor 53 for measuring the flow rate of the cathode-side gas that has passed through the gas-liquid separation mechanism 52, a hydrogen sensor 54 for measuring the concentration of hydrogen gas contained in the cathode-side gas that has passed through the gas-liquid separation mechanism 52, or an oxygen sensor 55 for measuring the concentration of oxygen gas contained in the cathode-side gas that has passed through the gas-liquid separation mechanism 52.

[0038] The gas-liquid separation mechanism 52 includes a first gas-liquid separation unit 521 that separates water (mainly liquid water (associated water)) discharged together with the cathode-side gas, and a second gas-liquid separation unit 522 that separates water (mainly water vapor) contained in the cathode-side gas that has passed through the first gas-liquid separation unit 521. In this way, liquid water (associated water) discharged from the cathode W2 of the water electrolysis device (water electrolysis stack W) together with the cathode-side gas can be separated or recovered by the first gas-liquid separation unit 521, and water vapor contained in the hydrogen gas can be separated or recovered by the second gas-liquid separation unit 522, thus enabling accurate evaluation of the water electrolysis stack W.

[0039] The first gas-liquid separation unit 521 separates liquid water (associated water) that is discharged together with the cathode-side gas, and has a first gas-liquid separation tank 521a. The water separated by the first gas-liquid separation unit 521 may include liquid water generated by the condensation of water vapor in the path from the cathode W2 of the water electrolysis stack W to the first gas-liquid separation unit 521.

[0040] The second gas-liquid separation unit 522 includes a second heat exchanger 522a for cooling the cathode-side gas that has passed through the first gas-liquid separation unit 521, and a second gas-liquid separation tank 522b for condensing and separating the water vapor contained in the cathode-side gas cooled by the second heat exchanger 522a. The water separated by the second gas-liquid separation unit 522 may include liquid water contained in the cathode-side gas that has passed through the first gas-liquid separation unit 521. In this embodiment, a dew point sensor 56a for measuring the dew point of moisture contained in the cathode-side gas is provided between the first gas-liquid separation unit 521 and the second gas-liquid separation unit 522 in the cathode-side gas flow path 51. Furthermore, a dew point sensor 56b for measuring the dew point of moisture contained in the cathode-side gas and / or a temperature sensor 56c for measuring temperature are provided downstream of the second gas-liquid separation unit 522. The dew point sensor 56b is capable of measuring the dew point under atmospheric pressure. The temperature and / or flow rate of the refrigerant flowing through the heat exchanger 522a may be controlled based on the dew point obtained by the dew point sensors 56a and 56b and / or the temperature obtained by the temperature sensor 56c.

[0041] Furthermore, the first gas-liquid separation tank 521b and the second gas-liquid separation tank 522b are each equipped with a water level sensor 57, and a drainage channel 58 for discharging the stored water is connected to them. This drainage channel 58 is equipped with a fluid control valve 59 that is controlled based on the water level detected by the water level sensor 57. In addition, the first gas-liquid separation tank 521a and the second gas-liquid separation tank 522b have a double-wall structure consisting of an inner wall and an outer wall, and cooling water is supplied between the inner wall and the outer wall. Moreover, the cathode-side gas channel 51 is insulated by an insulating material 11 at least up to the second heat exchanger 522a. Also, the drainage channel 58 is insulated by an insulating material 11 up to the fluid control valve 59.

[0042] Here, a pressure transmitter (differential pressure transmitter) may be used for the water level sensor 57. This pressure transmitter detects the pressure difference between two specific points. For example, by placing the two pressure detection units of the pressure transmitter in the gas phase portion of the gas-liquid separation tanks 521b and 522b and in the bottom portion of the gas-liquid separation tanks 521b and 522b, the pressure difference between these two points can be measured. The positions of the two detection units of the pressure transmitter may be set to match the upper and lower limits of the water level in the tank. Since the pressure transmitter can measure differential pressure, it is possible to measure the water level regardless of the absolute pressure of the hydrogen gas.

[0043] The first gas-liquid separation unit 521 and the second gas-liquid separation unit 522 are connected via a high-pressure flow path 51a and a low-pressure flow path 51b, which can be switched between them. The high-pressure flow path 51a and the low-pressure flow path 51b are branches of the cathode-side gas flow path 51. The high-pressure flow path 51a is equipped with a pressure regulating valve 51a1 for high pressure (e.g., 3 to 8 MPa), and the low-pressure flow path 51b is equipped with a pressure regulating valve 51b1 for low pressure (e.g., 0.3 to 0.9 PaG).

[0044] In addition, a pressure relief flow path L1 provided with a relief valve RV is connected to the first gas-liquid separation tank 521a of the first gas-liquid separation section 521 so that the pressure inside the tank does not exceed a predetermined upper limit pressure (for example, 8.5 MPa). Further, a pressure relief flow path L2 provided with a relief valve RV is connected to the downstream side of the confluence point of the high-pressure flow path 51a and the low-pressure flow path 51b so that the pressure in the flow path is less than a predetermined pressure (for example, 0.95 MPa). For example, when manufacturing a system that complies with the High-Pressure Gas Safety Act, it is necessary to specify the high-pressure portions. In a system as shown in FIG. 4, the first gas-liquid separation tank 521a may become high-pressure. Under such high-pressure conditions, the flow path range sandwiched by the relief valve RV may become high-pressure, and it is necessary to select components corresponding to high pressure within this range. On the other hand, by branching the cathode-side gas flow path 51 into the high-pressure flow path 51a and the low-pressure flow path 51b as shown in FIG. 4, the possibility that the range outside the range sandwiched by the relief valve RV becomes high-pressure can be reduced. Therefore, the range that requires high-pressure countermeasures can be limited, and effects can be enjoyed in terms of safety and cost.

[0045] In addition, drain pipes 58H that constitute a drain flow path 58 are connected to the bottom walls of the first gas-liquid separation tank 521a and the second gas-liquid separation tank 522b, respectively. The opening of the drain pipe 58H connected to the first gas-liquid separation tank 521a is located above the bottom surface of the first gas-liquid separation tank 521a. The opening of the drain pipe 58H connected to the second gas-liquid separation tank 522b is located above the bottom surface of the second gas-liquid separation tank 522b.

[0046] Note that dust discharge flow paths L3 for discharging dust such as scale are connected to the bottom walls of the first gas-liquid separation tank 521a and the second gas-liquid separation tank 522b, respectively, separately from the drain flow path 58. The dust discharge flow path L3 opens to the bottom surface of the first gas-liquid separation tank 521a or the bottom surface of the second gas-liquid separation tank 522b. An opening and closing valve CV such as a ball valve is provided in the dust discharge flow path L3. In the dust discharge flow path L3, up to the opening and closing valve CV, it is heat-insulated by the heat insulating material 11.

[0047] Further, on the cathode-side gas flow path 51, the downstream side of the second gas-liquid separation section 522 branches into a plurality of flow path sections 51c and 51d according to the flow rate of the cathode-side gas. In the present embodiment, there are a large-flow-rate flow path section 51c and a small-flow-rate flow path section 51d. A pressure adjustment valve 51c1 capable of flowing a large flow rate at a predetermined pressure (0.3 to 0.9 MPaG) is provided in the large-flow-rate flow path section 51c. Also, a pressure adjustment valve 51d1 capable of flowing a small flow rate at a predetermined pressure (0.3 to 0.9 MPaG) is provided in the small-flow-rate flow path section 51d.

[0048] Further, as shown in FIG. 3, an anode-side gas dilution mechanism 8 for diluting the crossover gas (hydrogen gas) contained in the anode-side gas is provided in the anode-side gas flow path 41 of the water electrolysis evaluation apparatus 100 of the present embodiment.

[0049] Specifically, the anode-side gas dilution mechanism 8 includes a sensor 81 provided in the anode-side gas flow path 41 for measuring the flow rate or concentration of the anode-side gas, a dilution gas supply section 82 for supplying a dilution gas to the anode-side gas flow path 41 to dilute the anode-side gas, and a flow rate control section 83 for controlling the flow rate of the dilution gas supplied from the dilution gas supply section 82 to the anode-side gas flow path 41 based on the measurement value of the sensor 81.

[0050] The sensor 81 of the present embodiment is a flow rate sensor for measuring the flow rate of the anode-side gas, and is provided on the downstream side of the gas-liquid separation mechanism 42 (the gas-liquid separation tank 422b of the second gas-liquid separation section 422) in the anode-side gas flow path 41. That is, the flow rate sensor 81 measures the flow rate of the anode-side gas from which moisture has been removed by the gas-liquid separation mechanism 42.

[0051] The dilution gas supply unit 82 is connected downstream of the flow sensor 81 in the anode-side gas flow path 41 and supplies a dilution gas, such as air, to the anode-side gas flow path 41. This dilution gas supply unit 82 has a dilution gas flow path 821 connected to the anode-side gas flow path 41 and a flow rate adjustment device 822 provided in the dilution gas flow path 821 for adjusting the flow rate of the dilution gas. The dilution gas flow path 821 may be configured to take in air from the atmosphere. The flow rate adjustment device 822 is, for example, a mass flow controller and has a flow sensor and a flow rate adjustment valve. In addition, the dilution gas supply unit 82 may have a pressure pump 823 or a dust collection filter 824. The flow rate adjustment device 822 may also be composed of an inverter fan and a flow meter. In this case, the flow rate of the dilution gas can be controlled by controlling the rotation speed of the inverter fan based on the output of the flow meter, etc.

[0052] The flow control unit 83 controls the flow rate of the dilution gas supplied from the dilution gas supply unit 82 to the anode-side gas flow path 41 based on the flow rate measured by the flow sensor 81. Specifically, the flow control unit 83 controls the flow rate of the dilution gas based on the flow rate measured by the flow sensor 81 so that the dilution ratio of the anode-side gas remains constant. In this embodiment, for example, the flow control unit 83 controls the flow rate adjustment device 822 so that the dilution ratio of the anode-side gas becomes 10 times. In other words, the flow control unit 83 controls the flow rate adjustment device 822 so that the ratio of the flow rate measured by the flow sensor 81 to the flow rate of the dilution gas becomes 1:9.

[0053] Furthermore, a hydrogen sensor 44 for measuring the concentration of hydrogen gas is provided downstream of the connection point of the dilution gas supply unit 82 in the anode-side gas flow path 41. In this embodiment, two hydrogen sensors 44 are provided; one hydrogen sensor 44 is for high concentrations, and the other hydrogen sensor 44 is for low concentrations.

[0054] <Water Level Control of Gas-Liquid Separation Tanks> Furthermore, the water electrolysis evaluation apparatus 100 of this embodiment has a configuration for controlling the water level of the first gas-liquid separation tank 521a or the second gas-liquid separation tank 522b of the gas-liquid separation mechanism 52 provided in the cathode-side gas flow path 51 in a predetermined manner. Below, an example of controlling the water level of the first gas-liquid separation tank 521a in a predetermined manner will be described, but the same applies to the second gas-liquid separation tank 522b.

[0055] Specifically, as described above, the water electrolysis evaluation device 100 includes a water level sensor 57 installed in the first gas-liquid separation tank 521a for measuring the water level in the first gas-liquid separation tank 521a, a drainage channel 58 connected to the first gas-liquid separation tank 521a for discharging water from the first gas-liquid separation tank 521a, and a fluid control valve 59 installed in the drainage channel 58 for controlling the flow rate of water flowing through the drainage channel 58.

[0056] Furthermore, the water electrolysis evaluation device 100 has a control calculation unit 50 that controls the fluid control valve 59 so that the water level in the first gas-liquid separation tank 521a remains within a certain range, based on the output signal of the water level sensor 57. In this way, by controlling the fluid control valve 59 so that the water levels in the gas-liquid separation tanks 521a and 522b remain within a certain range based on the output signal of the water level sensor 57, pressure fluctuations on the exhaust side of the water electrolysis device (water electrolysis stack W) can be reduced, and the test conditions of the water electrolysis device (water electrolysis stack W) can be maintained.

[0057] Furthermore, the drainage channel 58 has a main channel section 581 connected to the first gas-liquid separation tank 521a, and a first branch channel section 582 and a second branch channel section 583 branching off from the main channel section 581. The main channel section 581 is equipped with a flow sensor 581a for measuring the flow rate of water flowing through the drainage channel 58. The first branch channel section 582 is equipped with a first fluid control valve 59a for high pressure and a high-pressure on / off valve 582a. The second branch channel section 583 is equipped with a second fluid control valve 59b for low pressure and a low-pressure on / off valve 583a. Flow rate control in each branch channel 582, 583 may be performed, for example, by controlling the on / off valves 582a, 583a while keeping the opening degree of each fluid control valve 59a, 59b constant. Furthermore, flow rate control in each branched flow path 582, 583 can be achieved by switching the flow path with each on / off valve 582a, 583a, and controlling the flow rate with fluid control valves 59a, 59b provided in the switched flow path sections 582, 583. The drainage flow path 58 of the second gas-liquid separation tank 522b is equipped with a flow sensor 58a for measuring the flow rate of water flowing through the drainage flow path 58, a fluid control valve 59, and an on / off valve 58b. Flow rate control in this drainage flow path 58 may be achieved, for example, by keeping the opening degree of the fluid control valve 59 constant while turning the on / off valve 58b ON / OFF.

[0058] The control calculation unit 50 switches the opening and closing of the first fluid control valve 59a and on / off valve 582a, or the second fluid control valve 59b and on / off valve 583a, respectively, according to the pressure in the first gas-liquid separation tank 521a. The control calculation unit 50 also performs either the first measurement mode (constant water level mode) or the second measurement mode (water volume measurement mode) described below in order to calculate the water discharge flow rate or storage rate to the first gas-liquid separation tank 521a. Furthermore, the control calculation unit 50 can switch between the first measurement mode and the second measurement mode based on input signals from the user. The control calculation unit 50 can also transmit measurement results from various sensors to the display unit D (see Figure 1) and display the measurement results on the display unit D.

[0059] <First Measurement Mode (Constant Water Level Mode)> The control calculation unit 50 controls the first fluid control valve 59a and on / off valve 582a, or the second fluid control valve 59b and on / off valve 583a, so that the water level in the first gas-liquid separation tank 521a remains constant, and calculates the water discharge flow rate or storage rate to the first gas-liquid separation tank 521a based on the flow rate measured by the flow sensor 581a at that time.

[0060] Here, the control calculation unit 50 controls the first fluid control valve 59a and the on / off valve 582a to maintain a constant water level in the first gas-liquid separation tank 521a when the first fluid control valve 59a and the on / off valve 582a are open (the second fluid control valve 59b and the on / off valve 583a are closed), that is, when the first gas-liquid separation tank 521a is under high pressure. Based on the flow rate measured by the flow sensor 581a at that time, the control calculation unit 50 calculates the water discharge flow rate or storage rate into the first gas-liquid separation tank 521a.

[0061] On the other hand, when the second fluid control valve 59b is open (the first fluid control valve 59a is closed), that is, when the pressure inside the first gas-liquid separation tank 521a is low, the control calculation unit 50 controls the second fluid control valve 59b and the on / off valve 583a so that the water level inside the first gas-liquid separation tank 521a remains constant, and calculates the discharge flow rate or storage rate of water into the first gas-liquid separation tank 521a based on the flow rate measured by the flow sensor 581a at that time.

[0062] <Second Measurement Mode (Water Volume Measurement Mode)> With the first fluid control valve 59a and the second fluid control valve 59b closed, the control calculation unit 50 calculates the water discharge flow rate or storage rate to the first gas-liquid separation tank 521a by determining the time it takes for the water level in the first gas-liquid separation tank 521a to change from a predetermined lower limit to a predetermined upper limit, based on the output signal of the water level sensor 57.

[0063] Here, the control calculation unit 50 opens the first fluid control valve 59a or the second fluid control valve 59b to drain the water in the first gas-liquid separation tank 521a until the water level reaches a predetermined lower limit, and then closes the first fluid control valve 59a and the second fluid control valve 59b.

[0064] Subsequently, the control calculation unit 50 determines the change time required for the water level in the first gas-liquid separation tank 521a to change from a predetermined lower limit to a predetermined upper limit, based on the output signal of the water level sensor 57. Then, the control calculation unit 50 calculates the discharge flow rate or storage rate of water to the first gas-liquid separation tank 521a based on the volume from the lower limit to the upper limit of the water level in the first gas-liquid separation tank 521a and the change time.

[0065] In addition, the water electrolysis evaluation apparatus 100 of this embodiment may have a control device C for controlling various evaluation equipment, as shown in Figure 5. The control device C is composed of a computer equipped with a CPU, memory, input / output interface, AD converter, etc.

[0066] As shown in Figure 5, this control device C performs functions such as a reception unit C1, a calculation unit C2, a test control unit C3, and / or an output unit C4.

[0067] The reception unit C1 receives information from the measurement unit C0 or from an external source. The measurement unit C0 measures information about the test specimen W, information about the water supplied to the test specimen W, and / or information about the gas discharged from the test specimen. The measurement unit C0 has, for example, at least one sensor (e.g., a temperature sensor, a pressure sensor, a conductivity sensor, or a gas sensor), and measures information about the test specimen W, information about the water supplied to the test specimen W, and / or information about the gas discharged from the test specimen based on the output of the sensor. The measurement unit C0 may also include the various sensors described in the embodiment. Furthermore, the water supplied to the test specimen W may be in a liquid state or a gaseous state.

[0068] Here, information regarding the test specimen W can include, for example, the temperature of the test specimen W, the current, voltage, or power supplied to the test specimen W, or the operating time of the test specimen W. Information regarding the water supplied to or discharged from the test specimen W can include, for example, the temperature, flow rate, pressure, or conductivity of the water. Furthermore, information regarding the gas discharged from the test specimen W can include, for example, the temperature, flow rate, pressure, and / or concentration of the gas.

[0069] The calculation unit C2 calculates predetermined evaluation values ​​based on the values ​​measured by the measurement unit C0. These predetermined evaluation values ​​serve as indicators for evaluating the electrolytic stack W, which is the test specimen. Specific examples of evaluation values ​​include, for example, the purity of the generated gas calculated using the gas concentration, the amount of gas generated calculated using the gas concentration and flow rate, the energy consumption calculated using voltage, current and operating time, the internal resistance (stack resistance) calculated using voltage and current, and / or the water utilization efficiency (ratio of gas generated to water supplied) calculated using the water supply and gas generated amount. The calculation unit C2 may be composed of a single computer or its functions may be distributed among multiple computers.

[0070] The test control unit C3 controls the control objects included in the test equipment based on the values ​​measured by the measurement unit C0 or the evaluation values ​​calculated by the calculation unit C2. The test control unit C3 can also control the control objects included in the test equipment based on user commands input from an external source. Examples of control objects include pumps, on / off valves, flow control valves, heaters, heat exchangers, or power supply devices. An example of control by the test control unit C3 is to control the power supply device to start supplying power to the test specimen W when the conductivity of water falls below a predetermined threshold, or to adjust the opening degree of the pump and / or flow control valve according to the temperature or gas flow rate of the test specimen W.

[0071] The output unit C4 outputs the value measured by the measurement unit C0 or the evaluation value calculated by the calculation unit C2 to a display unit C5 or the like. Alternatively, the output unit C4 may output the value measured by the measurement unit C0 or the evaluation value calculated by the calculation unit C2 in a format readable by another information processing device (not shown).

[0072] Furthermore, the configuration and arrangement of the sensors used in the measurement unit C0, and the details of the controlled object and control method of the test control unit C3 can be understood by including the descriptions of each of the parts 2 to 5 described above.

[0073] <Effects of this embodiment> According to the water electrolysis evaluation apparatus 100 of this embodiment configured as described above, the flow rate of exhaust gas containing oxygen gas discharged from the anode W1 of the water electrolysis apparatus (water electrolysis stack W) is measured, and the flow rate of dilution gas supplied from the dilution gas supply unit 82 to the anode-side gas flow path 41 is controlled based on the measured flow rate. As a result, the mixed gas of oxygen gas and hydrogen gas generated by the crossover can be reliably diluted to a concentration below the explosion limit.

[0074] <Other Embodiments> The present invention is not limited to the embodiments described above.

[0075] For example, in the above embodiment, an anode-side gas dilution mechanism 8 is provided in the anode-side gas flow path 41, but a cathode-side gas dilution mechanism may also be provided in the cathode-side gas flow path 51 to dilute the crossover gas (oxygen gas) discharged together with the hydrogen gas.

[0076] In the above embodiment, the control calculation unit 50 was configured to control the dilution gas supply unit 82 (flow rate adjustment device 822) based on the flow rate measured by the flow sensor 81. However, it may also be configured to control the dilution gas supply unit 82 (flow rate adjustment device 822) based on the measured concentration of the hydrogen sensor 44 or the oxygen sensor. For example, the control calculation unit 50 may control the dilution gas supply unit 82 (flow rate adjustment device 822) so that the measured concentration of the hydrogen sensor 44 or the oxygen sensor is below a predetermined threshold. In this configuration, the hydrogen sensor 44 or the oxygen sensor may be provided upstream of the connection point of the dilution gas supply unit 82 in the anode-side gas flow path 41.

[0077] Furthermore, although the gas-liquid separation mechanism 42 of the anode-side gas flow path 41 was configured to have a first gas-liquid separation section 421 and a second gas-liquid separation section 422, it may also be configured to have only one gas-liquid separation section (either the first gas-liquid separation section 421 or the second gas-liquid separation section 422).

[0078] Furthermore, although the gas-liquid separation mechanism 52 of the cathode-side gas flow path 51 was configured to have a first gas-liquid separation section 521 and a second gas-liquid separation section 522, it may also be configured to have only one gas-liquid separation section (either the first gas-liquid separation section 521 or the second gas-liquid separation section 522).

[0079] Furthermore, although the water electrolysis evaluation apparatus 100 of the above embodiment performed a first measurement mode or a second measurement mode in the first gas-liquid separation tank 521a or the second gas-liquid separation tank 522b by the control calculation unit 50, the apparatus may also be configured not to perform these measurement modes. In this case, the control calculation unit 50 may, based on the output signal of the water level sensor 57, open the fluid control valve 59 when the water level in the first gas-liquid separation tank 521a or the second gas-liquid separation tank 522b reaches a predetermined upper limit, thereby controlling the apparatus to drain water from the first gas-liquid separation tank 521a or the second gas-liquid separation tank 522b.

[0080] In addition, although the second gas-liquid separation section 522 of the cathode-side gas flow path 51 in the above embodiment had a configuration that included a second heat exchanger 522a and a second gas-liquid separation tank 522b, it may also have a configuration that does not include the second heat exchanger 522a. Furthermore, the first gas-liquid separation section 521 of the cathode-side gas flow path 51 in the above embodiment may have a configuration that includes a first heat exchanger upstream of the first gas-liquid separation tank 521a.

[0081] Furthermore, the water electrolysis evaluation device 100 may be configured without a cathode-side pressure adjustment unit 7.

[0082] The test specimen in the above embodiment was a water electrolysis stack, but it may also be a water electrolysis cell constituting a water electrolysis stack, or a water electrolysis apparatus equipped with a water electrolysis stack. Furthermore, the water electrolysis apparatus is not limited to a PEM type water electrolysis apparatus, but may also be other types of water electrolysis apparatus such as an AEM (Anion Exchange Membrane) type water electrolysis apparatus or an SOEC (Solid Oxide Electrolysis Cell) type water electrolysis apparatus.

[0083] Furthermore, it goes without saying that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from its spirit.

[0084] According to the present invention, it is possible to evaluate a water electrolysis apparatus while appropriately processing the mixed gas of oxygen and hydrogen gas generated by the crossover.

[0085] 100...Water electrolysis evaluation device W...Water electrolysis device (water electrolysis stack) W1...Anode W2...Cathode W3...Solid polymer electrolyte membrane 41...Anode-side gas flow path 81...Sensor (flow sensor) 82...Dilution gas supply unit 83...Flow control unit 422a...Heat exchanger 422b...Gas-liquid separation tank

Claims

1. A water electrolysis evaluation apparatus for evaluating a water electrolysis apparatus that generates oxygen gas and hydrogen gas by electrolyzing water, comprising: a gas flow path through which exhaust gas containing the oxygen gas or hydrogen gas discharged from the anode or cathode of the water electrolysis apparatus flows; a sensor provided in the gas flow path for measuring the flow rate or concentration of the exhaust gas; a dilution gas supply unit for supplying dilution gas to the gas flow path to dilute the exhaust gas; and a flow control unit for controlling the flow rate of the dilution gas supplied from the dilution gas supply unit to the gas flow path based on the measurement value of the sensor.

2. The water electrolysis evaluation apparatus according to claim 1, wherein the gas flow path is connected to the anode of the water electrolysis apparatus.

3. The water electrolysis evaluation apparatus according to claim 1 or 2, wherein the sensor measures the flow rate of the exhaust gas, the dilution gas supply unit is connected downstream of the sensor in the gas flow path, and the flow rate control unit controls the flow rate of the dilution gas supplied from the dilution gas supply unit to the gas flow path based on the measurement value of the sensor.

4. The water electrolysis evaluation apparatus according to claim 3, wherein the flow rate control unit controls the flow rate of the dilution gas based on the measurement value of the sensor so that the dilution ratio of the exhaust gas remains constant.

5. The water electrolysis evaluation apparatus according to any one of claims 1 to 4, wherein the sensor is provided downstream of the connection point of the dilution gas supply unit in the gas flow path and measures the concentration of the crossover gas contained in the exhaust gas.

6. The water electrolysis evaluation apparatus according to any one of claims 1 to 5, wherein two sensors are provided, one of which is for high concentration and the other is for low concentration.

7. The water electrolysis evaluation apparatus according to any one of claims 1 to 6, further comprising a gas-liquid separation tank provided in the gas flow path, wherein the sensor is provided downstream of the gas-liquid separation tank in the gas flow path.

8. The water electrolysis evaluation apparatus according to claim 7, wherein a heat exchanger for cooling the exhaust gas is provided upstream of the gas-liquid separation tank in the gas flow path.

9. The water electrolysis evaluation apparatus according to any one of claims 1 to 8, wherein the water electrolysis apparatus is a PEM type water electrolysis apparatus.

10. A water electrolysis evaluation method for evaluating a water electrolysis apparatus that generates oxygen gas and hydrogen gas by electrolyzing water, comprising: measuring the flow rate or concentration of exhaust gas flowing through a gas channel connected to the anode or cathode of the water electrolysis apparatus using a sensor; supplying a dilution gas to dilute the exhaust gas to the gas channel using a dilution gas supply unit; and controlling the flow rate of the dilution gas supplied from the dilution gas supply unit to the gas channel based on the measurement value of the sensor.

11. A water electrolysis evaluation program for use in a water electrolysis evaluation apparatus for evaluating a water electrolysis apparatus that generates oxygen gas and hydrogen gas by electrolyzing water, the apparatus comprising: a gas flow path through which exhaust gas containing the oxygen gas or hydrogen gas discharged from the anode or cathode of the water electrolysis apparatus flows; a sensor provided in the gas flow path for measuring the flow rate or concentration of the exhaust gas; and a dilution gas supply unit for supplying dilution gas to the gas flow path to dilute the exhaust gas, wherein the water electrolysis evaluation program provides a computer with the function of a flow control unit that controls the flow rate of the dilution gas supplied from the dilution gas supply unit to the gas flow path based on the measurement value of the sensor.

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