Maintenance support system and maintenance support method

Abstract

This provides information to support the development of measures to suppress the accelerated deterioration of some electrolytic cells. [Solution] A maintenance support system 200 according to one aspect of the present invention includes a calculation unit 63 that predicts information on changes in the deterioration state of each of a plurality of electrolytic cells for each electrolytic cell arrangement pattern, based on input information which includes at least electrolytic characteristic information of the electrolytic cell, information on the arrangement pattern of the electrolytic cell, and information on the operating conditions of the electrolytic system, and outputs information on the predicted changes in the deterioration state of each electrolytic cell.

Description

Technical Field

[0001] The present invention relates to a maintenance support system and a maintenance support method.

Background Art

[0002] In recent years, as a countermeasure against global warming, an expansion of the use of renewable energy has been demanded. And, a technology development for electrolyzing water or the like (electrochemical decomposition) using the electric power obtained from renewable energy to generate hydrogen, methylcyclohexane (MCH), etc., and storing and using these as chemical energy has been promoted. For example, in a water electrolysis system which is an example of an electrolysis system, large-scale systems of 100 MW class to 1 GW class are being planned. However, since the scale of an electrolytic cell which is a reaction vessel for performing electrolysis is 1 MW to 10 MW class, an electrolysis system is composed of a plurality of electrolytic cells. In a system composed of a plurality of electrolytic cells, for the purpose of cost reduction of the system, a form in which a plurality of electrolytic cells are electrically connected in series and parallel and operated by one DC power supply is assumed to be adopted.

[0003] When driving a plurality of electrically connected electrolytic cells with one DC power supply, due to variations in the characteristics of the electrolytic cells, differences occur in the operating states such as current and voltage for each electrolytic cell, and an excessive load may be applied to some of the electrolytic cells. In particular, when a significant difference occurs between the characteristics of each of a plurality of electrolytic cells due to replacement of some of the electrolytic cells, etc., an overload is likely to occur in other electrolytic cells connected in series to that electrolytic cell. And, when an overload occurs in a specific electrolytic cell, deterioration in that electrolytic cell accelerates. When the deterioration in a specific electrolytic cell accelerates, there may be a case where an operation restriction or the like for suppressing the amount of hydrogen production by the water electrolysis system is performed for the purpose of delaying the progress of the deterioration.

[0004] Patent Document 1 describes a control device comprising: a prediction unit that predicts the amount of hydrogen generated in a water electrolysis stack and the degree of deterioration of the water electrolysis stack over a predetermined period of time, using the performance measured by a measurement unit that measures the performance of the water electrolysis stack and characteristics related to the susceptibility of the water electrolysis stack to deterioration; and an operating condition determination unit that determines conditions for controlling the operation of the water electrolysis stack based on the prediction results of the prediction unit.

[0005] Furthermore, Patent Document 2 describes a hydrogen production system that controls the power distribution to each series section of a water electrolysis stack based on the location of a faulty stack and a degradation prediction of a plurality of water electrolysis stacks calculated based on degradation characteristics indicating the susceptibility of the water electrolysis stack to degradation. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2024 / 069801 [Patent Document 2] Japanese Patent Publication No. 2023-028092 [Overview of the project] [Problems that the invention aims to solve]

[0007] The control device described in Patent Document 1 can reduce the system's lifecycle cost by suppressing the deterioration of the water electrolysis stack by controlling operating control conditions such as temperature and current to appropriate values ​​based on the deterioration prediction of the water electrolysis stack. However, it does not describe a method for resolving the situation in which some electrolytic cells are more prone to overload than others.

[0008] Furthermore, in the hydrogen production system described in Patent Document 2, the current flowing to the series section of the water electrolysis stack is controlled based on the prediction of the deterioration of the water electrolysis stack. Therefore, it is possible to limit the load only on the series section including the water electrolysis stack, which is prone to overload, thereby suppressing the impact of the load on the entire system. However, the technology described in Patent Document 2 requires a power conversion unit for each series section, which increases the equipment cost.

[0009] This invention was made to solve the above-mentioned problems. The object of this invention is to provide information that supports the formulation of measures to suppress the accelerated deterioration of certain electrolytic cells. [Means for solving the problem]

[0010] A maintenance support system according to one aspect of the present invention is a maintenance support system for an electrolytic system including a plurality of series-parallel connected electrolytic cells that operate using power supplied from a single DC power source. The maintenance support system according to one aspect of the present invention includes a calculation unit that predicts information on changes in the deterioration state of each of the plurality of electrolytic cells for each electrolytic cell arrangement pattern, based on input information which includes at least electrolytic characteristic information of the electrolytic cells, information on the arrangement pattern of the electrolytic cells, and information on the operating conditions of the electrolytic system, and outputs information on the predicted changes in the deterioration state of each electrolytic cell. [Effects of the Invention]

[0011] According to the present invention, information is provided to support the formulation of measures to suppress the accelerated deterioration of some electrolytic cells. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows a schematic diagram of a water electrolysis system according to one embodiment of the present invention. [Figure 2] This is a block diagram showing an example configuration of the control system of a maintenance support system according to one embodiment of the present invention. [Figure 3] This is a block diagram showing an example of the hardware configuration of a maintenance support system according to one embodiment of the present invention. [Figure 4]It is a flowchart showing an example of the procedure of maintenance support processing by a maintenance support system according to an embodiment of the present invention. [Figure 5] It is a graph showing the relationship between the increase rate of ohmic overvoltage and the degree of deterioration of an electrolytic cell according to an embodiment of the present invention. [Figure 6] It is a graph showing the relationship between the increase rate of activation overvoltage and the degree of deterioration of an electrolytic cell according to an embodiment of the present invention. [Figure 7] It is a graph showing the relationship between temperature and the deterioration progress ratio of ohmic overvoltage according to an embodiment of the present invention. [Figure 8] It is a graph showing the relationship between the cell voltage and the deterioration progress ratio of activation overvoltage according to an embodiment of the present invention. [Figure 9] It is a table showing the electrolytic characteristics of each electrolytic cell according to an embodiment of the present invention. [Figure 10] It is a diagram showing an example of two arrangement patterns of an electrolytic cell input to a condition input unit according to an embodiment of the present invention. [Figure 11] It is a graph showing the correspondence between the cell voltage and the operation time of electrolytic cell 211 in the first arrangement pattern according to an embodiment of the present invention. [Figure 12] It is a graph showing the correspondence between the activation overvoltage deterioration degree and the operation time of an electrolytic cell in the first arrangement pattern according to an embodiment of the present invention. [Figure 13] It is a graph showing the correspondence between the cell voltage and the operation time of an electrolytic cell in the second arrangement pattern according to an embodiment of the present invention. [Figure 14] It is a graph showing the correspondence between the activation overvoltage deterioration degree and the operation time of an electrolytic cell in the second arrangement pattern according to an embodiment of the present invention. [Figure 15] It is a diagram showing an example of the configuration of an electrolytic cell characteristic display screen for each arrangement pattern according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this specification and the drawings, elements having substantially the same function or configuration are denoted by the same reference numerals, and redundant descriptions are omitted.

[0014] The electrolysis system according to the present invention is applicable to any electrolysis system such as water electrolysis, direct MCH electrolysis synthesis, and soda electrolysis. In this embodiment, an example applied to a water electrolysis system will be given. Further, the electrolytic cell used in the electrolysis system according to the present invention is applicable to any type of electrolytic cell such as an alkaline type, a solid polymer type, and an anion exchange membrane type. In this embodiment, an example using a solid polymer type electrolytic cell will be given. This is because the solid polymer type electrolytic cell is relatively lightweight because of its high volume output density and weight output density of hydrogen, and it is easy to perform rearrangement and replacement of the electrolytic cell.

[0015] The maintenance support system according to the present invention predicts changes in the deterioration state of each electrolytic cell in each arrangement pattern with different arrangements of the electrolytic cells, and calculates (estimates) the operation cost (profit and loss) of the electrolytic cell using the information on the changes in the deterioration state. Then, the maintenance support system causes the display unit to display the calculation result.

[0016] <Overview of the electrolysis system> First, the configuration of a water electrolysis system 100 according to an embodiment of the present invention will be described. The water electrolysis system 100 according to this embodiment is a system that electrolyzes pure water to generate hydrogen (H2) (an example of a product) and oxygen (O2).

[0017] FIG. 1 is a diagram showing an overview of the water electrolysis system 100 according to this embodiment. As shown in FIG. 1, the water electrolysis system 100 includes a DC power source 1, an electrolytic cell group 2a to 2c, a hydrogen gas-liquid separator 3, an oxygen gas-liquid separator 4, a pump 5, and a heat exchanger 6.

[0018] The DC power source 1 converts and rectifies the input AC power into a DC power and outputs it to each electrolytic cell of the electrolytic cell group 2a to 2c. The electrolytic cell group 2a to 2c is each shown surrounded by a dashed line frame in FIG. 1. Electrolytic cell group 2a consists of electrolytic cell sets 21a-1 to 21a-3, electrolytic cell group 2b consists of electrolytic cell sets 21b-1 to 21b-3, and electrolytic cell group 2c consists of electrolytic cell sets 21c-1 to 21c-3. Electrolytic cell sets 21a-1 to 21a-3, 21b-1 to 21b-3, and 21c-1 to 21c-3 are each enclosed by dashed-dot frames in Figure 1. Since electrolytic cell groups 2a to 2c have the same configuration, the configuration of the electrolytic cells will be explained using electrolytic cell group 2a as an example, and the configurations of electrolytic cell groups 2b and 2c will not be explained.

[0019] In electrolytic cell group 2a, electrolytic cell set 21a-1 consists of electrolytic cells 211a-1 and 211a-2 connected in series, electrolytic cell set 21a-2 consists of electrolytic cells 211a-3 and 211a-4 connected in series, and electrolytic cell set 21a-3 consists of electrolytic cells 211a-5 and 211a-6 connected in series. Furthermore, in electrolytic cell group 2a, electrolytic cell sets 21a-1 to 21a-3 are connected in parallel.

[0020] In the following explanation, when it is not necessary to distinguish between electrolytic cell groups 2a to 2c individually, they will be collectively referred to as "electrolytic cell group 2". Similarly, when it is not necessary to distinguish between electrolytic cell sets 21a-1 to 21a-3, 21b-1 to 21b-3, and 21c-1 to 21c-3 individually, they will be collectively referred to as "electrolytic cell set 21".

[0021] Furthermore, when there is no need to distinguish between electrolytic cells 211a-1 to 211a-6, electrolytic cells 211b-1 to 211b-6, and electrolytic cells 211c-1 to 211c-6, they are collectively referred to as "electrolytic cell 211".

[0022] As described above, the water electrolysis system 100 according to this embodiment shown in Figure 1 is configured such that an electrolytic cell group 2 is formed by connecting three electrolytic cell sets 21, each consisting of two electrolytic cells 211 connected in series, in parallel, and these electrolytic cell groups 2 are connected in series with each other. According to the configuration shown in Figure 1, the voltage is increased by connecting the electrolytic cells 211 in series, and the current value for the same output value can be reduced. Therefore, the water electrolysis system 100 according to this embodiment can reduce the cost of power supply equipment such as a DC power supply 1 and a busbar (not shown).

[0023] Furthermore, in the electrolytic cell group 2 of the water electrolysis system 100, the electrolytic cell sets 21 are connected in parallel, so that a current path can be secured even if deterioration or abnormality occurs in any of the electrolytic cell sets 21. Therefore, according to the water electrolysis system 100 of this embodiment, when an abnormality occurs, it is possible to stop only some of the electrolytic cell groups 2 without having to emergency shut down the entire water electrolysis system 100, while continuing to operate the other electrolytic cell groups 2.

[0024] Furthermore, the number of electrolytic cells 211 in series in the electrolytic cell assembly 21 is preferably a small number, such as four or fewer, and even more preferably two. This is because if the number of electrolytic cells 211 in series exceeds four, the effect of reducing the current flowing through the electrolytic cell assembly 21, including the electrolytic cells 211 with high resistance, becomes smaller.

[0025] Furthermore, in the water electrolysis system 100 according to this embodiment, the multiple electrolytic cell groups 2 connected in series and parallel are operated by the same DC power supply supplied from the DC power supply 1. Each of the multiple electrolytic cells 211 is composed of multiple electrolytic cells (hereinafter simply referred to as "cells"), which are not shown. Each of the multiple cells consists of an anode that performs an oxidation reaction, a cathode that performs a reduction reaction, and an electrolyte located between the anode and cathode (neither of which are shown).

[0026] The hydrogen generated at the cathode of the electrolytic cell 211 is sent to the hydrogen vapor-liquid separator 3, and the oxygen generated at the anode is sent to the oxygen vapor-liquid separator 4. The oxygen vapor-liquid separator 4 separates the oxygen generated at the anode of the electrolytic cell 211 from water. The hydrogen vapor-liquid separator 3 separates the hydrogen generated at the cathode of the electrolytic cell 211 from water. Most of the water discharged from the electrolytic cell 211 is sent to the oxygen vapor-liquid separator 4.

[0027] The pure water discharged from the oxygen vapor-liquid separator 4 is resupplied to each electrolytic cell 211 via the water circulation line indicated by the dashed line. The water circulation line is equipped with a pump 5 and a heat exchanger 6. The pump 5 circulates the water within the water electrolysis system 100 by supplying the circulating water from the water circulation line to the electrolytic cells 211, and also cools the electrolytic cells 211 by supplying the circulating water cooled by the heat exchanger 6 to the electrolytic cells 211. The heat exchanger 6 adjusts (cools) the temperature of the circulating water flowing through the water circulation line to a predetermined temperature.

[0028] The water electrolysis system 100 also includes a control unit (not shown). The control unit controls the temperature and flow rate of the water supplied to each electrolytic cell 211 via the water circulation line. The control unit may adjust the temperature and flow rate of the water flowing through the entire water circulation line and distribute the adjusted water to each electrolytic cell 211, or it may individually control the temperature and flow rate of the water flowing to each electrolytic cell 211.

[0029] Furthermore, in this embodiment, an example was given in which the electrolytic cell 211 is cooled by supplying water cooled by the heat exchanger 6 to the electrolytic cell 211, but the present invention is not limited thereto. For example, the electrolytic cell 211 may be cooled by placing a cooling medium other than the raw material (not shown) in a part of the electrolytic cell 211 that does not come into contact with the electrodes (not shown) of the electrolytic cell 211. The control unit may control the flow rate and temperature of this cooling medium as a whole and then distribute it to each electrolytic cell 211, or it may control them individually for each electrolytic cell.

[0030] Each electrolytic cell 211 is equipped with sensors (not shown) to measure the current, voltage, water temperature, etc., flowing through each electrolytic cell 211. The characteristic data of the electrolytic cells 211 (an example of electrolytic characteristic information) stored in the database 62 (see Figure 2), described later, is created based on the values ​​detected by the sensors. A separate characteristic data generation unit may be provided to automatically generate the characteristic data of the electrolytic cells 211 using the values ​​detected by the sensors.

[0031] <Configuration of the control system for the maintenance support system> Next, with reference to Figure 2, the configuration of the control system of the maintenance support system 200 of the water electrolysis system 100 according to this embodiment will be described. Figure 2 is a block diagram showing an example of the configuration of the control system of the maintenance support system 200.

[0032] As shown in Figure 2, the maintenance support system 200 includes a condition input unit 61, a database 62, a calculation unit 63, and a display unit 64.

[0033] The condition input unit 61 receives input from the user of input conditions (examples of input information) for calculations performed by the calculation unit 63, such as the arrangement patterns of the electrolytic cells 211, the operating patterns of the water electrolysis system 100, constraints, and operating period. The condition input unit 61 then outputs the received input conditions to the calculation unit 63.

[0034] The operating pattern consists of information on the time-dependent changes of various control parameters, such as the current supplied to the water electrolysis system 100, the supplied water temperature, and the water flow rate. The constraints are those imposed on the operation of the electrolytic cell 211 and are determined by factors such as the operating range of the electrolytic cell 211, hydrogen demand, and the operating guidelines of the operator of the water electrolysis system 100. Examples of constraints include a constraint that limits the amount of hydrogen produced even when hydrogen demand is high, in order to prioritize suppressing the deterioration of the electrolytic cell 211 and ensuring the lifespan of the water electrolysis system 100. Other constraints include a constraint that allows operation exceeding the load limit set at the beginning of operation of the water electrolysis system 100, in order to prioritize hydrogen demand.

[0035] The operating period indicates the operating period to be calculated by the calculation unit 63. If the operating period is set to, for example, 20,000 hours, the calculation unit 63 will perform calculations targeting predetermined time steps, such as 100 hours, by successively moving the time steps until the time step reaches 20,000 hours. Alternatively, if the predicted deterioration state of the electrolytic cell 211 reaches a state requiring replacement before the time step reaches 20,000 hours, the calculation unit 63 will terminate the calculation at that point.

[0036] Database 62 stores characteristic data, degradation rate data, cost data, and other information for each electrolytic cell 211. The characteristic data for each electrolytic cell 211 represents the electrolytic characteristics of each electrolytic cell 211 and is composed of the functional form, constants, and degree of degradation of each overvoltage component of each electrolytic cell 211. This characteristic data for each electrolytic cell 211 can be generated from the initial characteristics of the electrolytic cell 211, its operating history, and electrolytic cell characteristic data during operation of the electrolytic cell 211.

[0037] Degradation rate data (an example of predicted degradation rate information) is shown by the functional form and constants of each overvoltage degradation progression. The degradation rate data is generated based on the results of degradation evaluation tests conducted before the start of operation of the water electrolysis system 100. Furthermore, the degradation rate data may be appropriately modified based on the actual operating data (trend data) of the water electrolysis system 100.

[0038] The cost data consists of the assumed price of electricity, the assumed selling price of hydrogen, the fixed costs of the electrolytic cell 211, the asset value of a deteriorated electrolytic cell 211, etc. The cost data may also include replacement costs, maintenance and inspection costs, and installation / replacement costs for the electrolytic cell 211. The cost data is generated, for example, from trend data of the water electrolysis system 100. Furthermore, the cost data may be updated as needed based on the latest trends.

[0039] The calculation unit 63 predicts the operating state and deterioration state of each electrolytic cell 211 in each electrolytic cell arrangement pattern based on various data stored in the database 62 and various input conditions entered from the condition input unit 61, and calculates the advantages and disadvantages of operating the electrolytic cell 211 during the specified operating period based on the predictions. The display unit 64 displays the calculation results from the calculation unit 63.

[0040] <Example of computer hardware configuration> Next, the hardware configuration of the device for realizing the functions of the maintenance support system 200 according to this embodiment will be described with reference to Figure 3. Figure 3 is a block diagram showing an example of the hardware configuration of the maintenance support system 200. The computer 50 shown in Figure 3 is hardware used as a so-called computer.

[0041] The computer 50 comprises a control unit 51 connected to bus B, a non-volatile storage 52, a display unit 53, an operation input unit 54, and a communication interface 55.

[0042] The control unit 51 includes a CPU (Central Processing Unit) 511, a ROM (Read Only Memory) 512, and a RAM (Random Access Memory) 513.

[0043] The CPU 511 reads the program code of the software that implements each function according to this embodiment from the ROM 512, loads it into the RAM 513, and executes it. Variables, parameters, etc. that occur during the calculation process are temporarily written to the RAM 513.

[0044] The control unit 51 may be equipped with a processing unit such as an MPU (Micro-Processing Unit) instead of a CPU 511. Alternatively, the control unit 51 may use both a CPU and an MPU.

[0045] Examples of non-volatile storage 52 include HDDs (Hard Disk Drives), SSDs (Solid State Drives), flexible disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, and non-volatile memory cards. This non-volatile storage 52 stores the OS, various parameters, and programs necessary for the computer 50 to function. The programs may also be stored in the ROM 512.

[0046] The display unit 53 is a monitor, for example, an LCD (Liquid Crystal Display), which displays the results of processing performed by the computer 50. The operation input unit 54 is composed of, for example, a keyboard, mouse, touch sensor, etc., and generates operation signals in response to user operations and supplies them to the CPU 511. The display unit 53 and the operation input unit 54 may be integrated as a single touch panel.

[0047] The program is stored in the form of computer-readable program code, and the CPU 511 sequentially executes operations according to the program code. In other words, the ROM 512 or non-volatile storage 52 is used as an example of a computer-readable, non-transient recording medium that stores a program executed by the computer.

[0048] Communication I / F55 can utilize, for example, a NIC (Network Interface Card), enabling the transmission and reception of various types of data with external devices via a network or communication line.

[0049] <Overview of arithmetic processing by the arithmetic unit> Next, an overview of the calculation process performed by the calculation unit 63 will be described. First, the calculation unit 63 acquires various data from the database 62 (see Figure 2) and various input conditions from the condition input unit 61. Next, based on the acquired characteristic data of each electrolytic cell 211, the arrangement pattern of the electrolytic cells 211, the operating pattern, and the constraint conditions, the calculation unit 63 calculates the operating state of each electrolytic cell 211 at a certain time step and the amount of hydrogen produced by the water electrolysis system 100.

[0050] The time step period is the period to be calculated, for example, 100 hours. The time step period may be set in advance, or it may be specified by the user as an input condition. As for the operating state of each electrolytic cell 211, the calculation unit 63 calculates the current, voltage, temperature, etc. of each electrolytic cell 211. As an example, the calculation unit 63 can calculate the voltage of the electrolytic cell 211 using the following formula (1).

[0051] Ecell=Erev(T,Pa,Pc)+Eohm(I,T,αohm)+Eact(I,T,Pa,Pc,αact)+Edif(I,T,Pa,Pc,F,αdif)…Formula (1)

[0052] In equation (1) above, "Ecell" represents the cell voltage. The cell voltage is the voltage of the cells constituting the electrolytic cell 211, and is the theoretical electrolysis voltage plus ohmic losses such as film resistance and contact resistance, and overvoltage due to reaction resistance at the electrodes. Generally, the lower the cell voltage, the more efficient the water electrolysis, i.e., the higher the electrolysis characteristics. Here, it is assumed that each cell constituting the electrolytic cell 211 has the same characteristics. The electrolysis characteristics of the electrolytic cell 211 can be expressed by several overvoltage components that have different dependencies on temperature, pressure, water flow rate, etc. Furthermore, the degradation of these overvoltage components progresses at different degrees.

[0053] Furthermore, in equation (1) above, "Erev" represents the open-circuit voltage, "Eohm" represents the ohmic overvoltage, "Eact" represents the activation overvoltage, "Edif" represents the diffusion overvoltage, "T" represents the temperature, "Pa" represents the anode pressure, "Pc" represents the cathode pressure, and "I" represents the current. Additionally, "F" represents the water flow rate, "αohm" represents the degree of ohmic overvoltage degradation, "αact" represents the degree of activation overvoltage degradation, and "αdif" represents the degree of diffusion overvoltage degradation.

[0054] Next, the calculation unit 63 calculates the degree of degradation of each overvoltage component at the end of the time step based on the operating state of each electrolytic cell 211 at the calculated time step and the degradation rate data obtained from the database 62. The degree of degradation of activation overvoltage, which is an example of an overvoltage component, is shown by, for example, the following equation (2). The types of factors influencing the degradation rate differ depending on the overvoltage component.

[0055] αact,n+1=αact,n+Δαact(T,V)…Equation (2)

[0056] In equation (2) above, "αact,n+1" represents the degree of activation overvoltage degradation at the end of the time step, "αact,n" represents the degree of activation overvoltage degradation at the start of the time step, and "Δαact" represents the degree of degradation progression. "T" represents the temperature, and "V" represents the voltage of the electrolytic cell 211.

[0057] The calculation unit 63 updates the calculated degradation levels based on the degradation levels of each overvoltage component calculated using equation (2), and calculates the operating state of each electrolytic cell 211 and the degradation level of each overvoltage component for the next time step. The calculation unit 63 continues to perform these calculations until the operating period to be calculated ends, or until the calculated degradation level reaches a level that necessitates the replacement of the electrolytic cell 211.

[0058] Next, the calculation unit 63 calculates the operating cost (gain) of the electrolytic cell 211 during the operating period, based on the cost data obtained from the database 62, the power consumption of the electrolytic cell 211, and the amount of hydrogen produced by the water electrolysis system 100, while calculating (predicting) the operating state. The calculation unit 63 performs calculations of the operating state of the electrolytic cell 211, the degree of degradation of the activation overvoltage, and the operating cost for each electrolytic cell 211 in all configuration patterns.

[0059] <Procedure for maintenance support processing by the maintenance support system> Next, with reference to Figure 4, a maintenance support method by the maintenance support system 200 according to this embodiment will be described. Figure 4 is a flowchart showing an example of the procedure for maintenance support processing by the maintenance support system 200.

[0060] First, the condition input unit 61 receives input conditions for the calculation unit 63 from the user (step S1). In step S1, the condition input unit 61 receives input conditions such as the arrangement pattern of the electrolytic cell 211, the operation pattern, the operation period, and constraint conditions.

[0061] Next, the calculation unit 63 calculates the amount of hydrogen produced by the water electrolysis system 100 and the operating state of each electrolytic cell 211 in the arrangement pattern being calculated (step S2). In step S2, the calculation unit 63 calculates the current, voltage, temperature, etc. of the electrolytic cell 211 as the operating state of the electrolytic cell 211. The calculation unit 63 can calculate the operating state of each electrolytic cell 211 based on the characteristic data of the electrolytic cells in the database 62 (see Figure 2), specifically, information such as the initial performance and degree of degradation of the electrolytic cell 211.

[0062] Next, the calculation unit 63 calculates (predicts) the degree of degradation of each overvoltage component of the electrolytic cell 211 after the end of a predetermined time step (step S3). The calculation unit 63 can calculate the degree of degradation of each overvoltage component of the electrolytic cell 211 based on the degradation rate data information in the database 62. Next, the calculation unit 63 calculates the amount of hydrogen produced by the water electrolysis system 100 and the operating state of the electrolytic cell 211 in the next time step (step S4). Next, the calculation unit 63 determines whether or not the operating period entered in step S1 has ended (step S5).

[0063] If it is determined in step S5 that the operating period has not ended (step S5 is NO), the calculation unit 63 returns to step S3 to process. On the other hand, if it is determined in step S5 that the operating period has ended (step S5 is YES), the calculation unit 63 calculates the gains and losses (operating costs) of the water electrolysis system 100 during the operating period (step S6).

[0064] In step S6, the calculation unit 63 can calculate information such as the deterioration state of each electrolytic cell 211 in the arrangement pattern to be calculated, predicted information on the trend of hydrogen production, the sales profit of the predicted amount of hydrogen produced, and losses incurred due to the deterioration of the electrolytic cell 211, as the gains and losses of the water electrolysis system 100.

[0065] Next, the calculation unit 63 determines whether or not the calculation for all arrangement patterns of the electrolytic cell 211 has been completed (step S7). If it is determined in step S7 that the calculation for all arrangement patterns has not been completed (step S7 is NO), the calculation unit 63 returns to step S2 to continue processing.

[0066] On the other hand, if it is determined in step S7 that the calculations for all arrangement patterns have been completed (step S7 is YES), the calculation unit 63 outputs the calculation results to the display unit 53 (step S8). Next, the display unit 64 displays the calculation results input from the calculation unit 63 on the screen of the display unit 53 (step S9). After the processing in step S9, the maintenance support processing by the maintenance support system 200 is completed.

[0067] [Examples] Next, an example of calculation processing by the calculation unit 63 for a certain arrangement pattern will be described. As an example of a certain arrangement pattern, we will take the arrangement pattern of the electrolytic cell group 2 shown in Figure 1. That is, it is an arrangement pattern in which three sets of electrolytic cells 21, each consisting of two electrolytic cells 211 directly connected, are connected in parallel. In this embodiment, electrolytic cell 211a-1 will be called the first electrolytic cell, electrolytic cell 211a-2 will be called the second electrolytic cell, and electrolytic cell 211a-3 will be called the third electrolytic cell. Also, electrolytic cell 211a-4 will be called the fourth electrolytic cell, electrolytic cell 211a-5 will be called the fifth electrolytic cell, and electrolytic cell 211a-6 will be called the sixth electrolytic cell.

[0068] In this embodiment, the first electrolytic cell is a brand new electrolytic cell 211 that has just been replaced, and the second electrolytic cell has a higher initial ohmic overvoltage and a higher degree of degradation of activation overvoltage than the other electrolytic cells. The initial characteristics and degree of degradation of the third to fifth electrolytic cells are standard, and the degree of degradation of the sixth electrolytic cell is lower than that of the other electrolytic cells.

[0069] Figure 5 is a graph showing the relationship between the rate of increase of ohmic overvoltage and the degree of degradation of the electrolytic cell 211, and Figure 6 is a graph showing the relationship between the rate of increase of activation overvoltage and the degree of degradation of the electrolytic cell 211. In Figure 5, the vertical axis shows the rate of increase of ohmic overvoltage (%), and the horizontal axis shows the degree of degradation of the electrolytic cell 211 (%). In Figure 6, the vertical axis shows the rate of increase of activation overvoltage (%), and the horizontal axis shows the degree of degradation of the electrolytic cell 211 (%). In this embodiment, we give an example in which the characteristic data of the electrolytic cell 211 is shown by a resistance model in which the overvoltage is separated into ohmic overvoltage and activation overvoltage.

[0070] Figure 5 shows that as the degree of degradation of the electrolytic cell 211 progresses over time, the rate of increase in ohmic overpotential also increases. Figure 6 shows that as the degree of degradation of the electrolytic cell 211 progresses, the rate of increase in activation overpotential also increases.

[0071] Furthermore, in this embodiment, we assume a model in which the degradation rate of ohmic overvoltage is affected by temperature, and the degradation rate of activation overvoltage is affected by cell voltage. Figure 7 is a graph showing the relationship between temperature and the degradation rate ratio of ohmic overvoltage, and Figure 8 is a graph showing the relationship between cell voltage and the degradation rate ratio of activation overvoltage. In Figure 7, the vertical axis shows the degradation rate ratio of ohmic overvoltage, and the horizontal axis shows temperature (°C). In Figure 8, the vertical axis shows the degradation rate ratio of activation overvoltage, and the horizontal axis shows cell voltage (V). As shown in Figure 7, the degradation rate ratio of ohmic overvoltage increases with increasing temperature. Also, as shown in Figure 8, the degradation rate ratio of activation overvoltage increases with increasing cell voltage.

[0072] Figure 9 is a table showing the electrolytic characteristics of each electrolytic cell 211. The table in Figure 9 includes the following items: "Electrolytic Cell Number," "Initial Activation Overvoltage Magnification," "Initial Ohmic Overvoltage Magnification," "Activation Overvoltage Degradation," and "Ohmic Overvoltage Degradation."

[0073] The "Electrolytic Cell Number" field stores the number of each electrolytic cell that makes up the arrangement pattern, i.e., one of the numbers from electrolytic cell 1 to electrolytic cell 6. In Figure 9, the electrolytic cell numbers are shown in parentheses. The "Initial Activation Overvoltage Magnification" field stores information on the initial activation overvoltage magnification, and the "Initial Ohmic Overvoltage Magnification" field stores information on the initial ohmic overvoltage magnification. The "Activation Overvoltage Degradation Degree" field stores information on the degree of degradation (%) of the activation overvoltage, and the "Ohmic Overvoltage Degradation Degree" field stores information on the degree of degradation (%) of the ohmic overvoltage.

[0074] In the new first electrolytic cell, both the initial multiplier of the activation overvoltage and the initial multiplier of the ohmic overvoltage are "1.0", and both the degradation degree of the activation overvoltage and the degradation degree of the ohmic overvoltage are "0%". In the second electrolytic cell, which has high resistance and significant degradation, the initial multiplier of the activation overvoltage is "1.0", but the initial multiplier of the ohmic overvoltage is a relatively high "1.1". Furthermore, the degradation degree of the activation overvoltage is a relatively high value of "25%", while the degradation degree of the ohmic overvoltage is a standard value of "19%".

[0075] In electrolytic cells 3 through 5, which have standard characteristics, both the initial magnification of the activation overvoltage and the initial magnification of the ohmic overvoltage are "1.0", and both the degradation degree of the activation overvoltage and the degradation degree of the ohmic overvoltage are "19%". In electrolytic cell 6, which shows less degradation, both the initial magnification of the activation overvoltage and the initial magnification of the ohmic overvoltage are "1.0", and both the degradation degree of the activation overvoltage and the degradation degree of the ohmic overvoltage are "13%".

[0076] Figure 10 shows examples of two arrangement patterns for the electrolytic cell 211 input to the condition input unit 61. In the first arrangement pattern shown on the left side of Figure 10, a new first electrolytic cell and a second electrolytic cell with high resistance are connected in series in the leftmost column of electrolytic cell sets. In the second arrangement pattern shown on the right side of Figure 10, the second electrolytic cell that makes up the leftmost column of electrolytic cell sets in the first arrangement pattern and the sixth electrolytic cell that makes up the rightmost column of electrolytic cell sets are swapped. In other words, in the electrolytic cell sets of the second arrangement pattern, the sixth electrolytic cell with low resistance is directly connected to the new first electrolytic cell.

[0077] Figure 11 is a graph showing the correspondence between cell voltage and the operating time of electrolytic cell 211 in the first configuration pattern of Figure 10, and Figure 12 is a graph showing the correspondence between the degree of activation overvoltage degradation and the operating time of electrolytic cell 211 in the first configuration pattern. Figure 13 is a graph showing the correspondence between cell voltage and the operating time of electrolytic cell 211 in the second configuration pattern, and Figure 14 is a graph showing the correspondence between the degree of activation overvoltage degradation and the operating time of electrolytic cell 211 in the second configuration pattern. In the graphs of Figures 11 and 13, the vertical axis represents cell voltage (V), and the horizontal axis represents the operating time of electrolytic cell 211 (h). In the graphs of Figures 12 and 14, the vertical axis represents the degree of activation overvoltage degradation (%), and the horizontal axis represents the operating time of electrolytic cell 211 (h). Furthermore, in the graphs of Figures 11 to 14, the characteristics of the first electrolytic cell are shown by a coarse dashed line, the characteristics of the second electrolytic cell are shown by a dashed-dotted line, and the characteristics of the third and fourth electrolytic cells are shown by double-dotted lines. In addition, the characteristics of the fifth electrolytic cell are shown by a white dashed line, and the characteristics of the sixth electrolytic cell are shown by a fine dashed line.

[0078] The graphs shown in Figures 11 to 14 represent the calculation results when the input conditions for the calculation unit 63 are as described below. • Operating pattern: The average current density in electrolytic cell 211 is 1.5 A / cm². 2 at a constant • Water temperature supplied to electrolytic cell 211: 60°C • Flow rate of water supplied to electrolytic cell 211: 1 cm² of electrode area 2 2 ml / min • Operating period: 20,000 hours

[0079] In the first configuration pattern shown on the left side of Figure 10, current flows more easily to the first electrolytic cell, which is new and has low resistance. This increases the load on the second electrolytic cell, which is connected in series with the first electrolytic cell and has high resistance and a high degree of degradation. Therefore, as shown in Figure 11, the cell voltage of the second electrolytic cell connected in series with the first electrolytic cell (shown by the dashed line) becomes higher than that of the other electrolytic cells. As a result, as shown in Figure 12, the progression of activation overvoltage degradation in the second electrolytic cell is faster than that of the other electrolytic cells, reaching 100% at 17,200 hours of operation. In other words, it is assumed that the second electrolytic cell will need to be replaced when it reaches 17,200 hours of operation.

[0080] On the other hand, in the second configuration pattern shown on the right side of Figure 10, as shown in Figure 13, the cell voltage of the sixth electrolytic cell connected in series with the new first electrolytic cell is also high. However, because the resistance of the second electrolytic cell, which has been rearranged from the leftmost column to the rightmost column of electrolytic cell sets, is also high, the load on each electrolytic cell is distributed and variations are reduced. As a result, the rate of deterioration in each electrolytic cell constituting the electrolytic cell group is made uniform, and as shown in Figure 14, no electrolytic cells reach 100% deterioration even when the operating time reaches 20,000 hours. This makes it possible for the water electrolysis system 100 to continue operating even after 20,000 hours. In other words, it can be seen that the operating cost of the water electrolysis system 100 can be lowered with the second configuration pattern than with the first configuration pattern.

[0081] Furthermore, if the primary objective is to extend the operating time by making the degradation rate of the electrolytic cell 211 uniform, that is, to reduce the risk of shutdown of the water electrolysis system 100, then adopting the second arrangement pattern is desirable. On the other hand, from the viewpoint of ease of implementing thermal control to maintain the temperature of the electrolytic cell 211 within a predetermined range, and from the viewpoint of suppressing degradation of the electrolytic cell 211 which is less prone to degradation, adopting the first arrangement pattern is desirable. In this embodiment, in order to meet various requirements requested by the user, information regarding the operating costs in various arrangement patterns of the electrolytic cell 211 is displayed on the screen of the display unit 64 (see Figure 2).

[0082] Figure 15 shows an example of the configuration of the electrolytic cell characteristics display screen for each arrangement pattern. As shown in Figure 15, the top of the electrolytic cell characteristics display screen Sc for each arrangement pattern displays operating cost-related information in a table.

[0083] The table showing operational cost-related information includes the following items: "Deployment Pattern Number," "Profit Difference," "System Lifetime," "Total Hydrogen Production," and "Details."

[0084] The "Configuration Pattern Number" field displays an identification number that identifies the configuration pattern. The "Profit Difference" field displays information on the difference (M¥) in profit from the proposed configuration of the water electrolysis system 100 compared to the profit from the current configuration of the water electrolysis system 100. The "System Life" field displays information on the system life (kilometers) of the water electrolysis system 100 in that configuration pattern. System life is indicated, for example, by the time it takes for either the catalyst degradation or the electrolyte membrane degradation to reach 100%. The "Total Hydrogen Production" field displays information on the total hydrogen production of the water electrolysis system 100 in that configuration pattern. The "Details" field contains buttons to display more detailed information such as "Degradation Level" and "Efficiency" for that configuration pattern.

[0085] In the lower left of the table showing operational cost-related information, information on the "layout pattern" is shown graphically. To the right of the "layout pattern" display area, information on the "degree of deterioration" is shown graphically, and to the right of that, information on the "operating efficiency" is shown graphically. For each of the "layout pattern," "degree of deterioration," and "operating efficiency" items, the information for the layout pattern selected by clicking the "Details" button in the table showing operational cost-related information is displayed. Figure 15 shows an example where the first layout pattern shown on the left side of Figure 10 is selected.

[0086] The "Arrangement Pattern" section displays a schematic diagram showing the configuration of the arrangement pattern selected by clicking the button in the "Details" section (the first arrangement pattern in the example of Figure 15). The "Degradation Level" graph has the degradation level (%) on the vertical axis and the operating time (h) on the horizontal axis. The "Degradation Level" graph shows the degradation level information for each electrolytic cell 211 that makes up the arrangement pattern shown in the "Arrangement Pattern" section.

[0087] In the graph showing the "degree of deterioration" in Figure 15, the second electrolytic cell, indicated by the dashed line, has the highest degree of deterioration, reaching 100% after 17,200 hours of operation. This is because the second electrolytic cell is connected in series with the new first electrolytic cell, resulting in an overloaded state and a high degree of deterioration. By reviewing this graph, users can more easily identify electrolytic cells that need replacement or reconfiguration, and plan the timing of such replacements.

[0088] The "Efficiency" graph displays information on the electrolysis efficiency of the water electrolysis system 100 for the configuration pattern shown in the "Configuration Pattern" section. The vertical axis of the "Efficiency" graph represents electrolysis efficiency (%), and the horizontal axis represents operating time (h). By checking this graph, users can predict when the electrolysis efficiency of the water electrolysis system 100 will decrease, and it becomes easier to determine when to take measures such as replacing the electrolytic cell.

[0089] Note that the configuration of the electrolytic cell characteristics display screen Sc is not limited to the example shown in Figure 15, and may include other items not included in Figure 15.

[0090] In the embodiment described above, the calculation unit 63 predicts information on changes in the deterioration state of each of the multiple electrolytic cells 211 for each electrolytic cell arrangement pattern, based on input information that includes at least characteristic data indicating the electrolytic characteristics of the electrolytic cells 211, information on the arrangement pattern of the electrolytic cells 211, and information on the operating conditions of the water electrolysis system 100. The calculation unit 63 then outputs information on the predicted changes in the deterioration state of each electrolytic cell 211. In other words, according to this embodiment, information is provided to the user that supports the formulation of measures to suppress the accelerated deterioration of some electrolytic cells.

[0091] Furthermore, in the above-described embodiment, the calculation unit 63 calculates information regarding the gains and losses obtained from the operation of the water electrolysis system 100 based on the predicted information regarding the deterioration state of each electrolytic cell 211, for each arrangement pattern of the electrolytic cells 211, and outputs the calculated information regarding the gains and losses. Therefore, according to this embodiment, the user can plan the replacement or rearrangement of the electrolytic cells 211 by referring to the information regarding the gains and losses obtained from the operation of the water electrolysis system 100.

[0092] Furthermore, in the embodiment described above, the calculation unit 63 calculates and outputs the difference between the profit obtained from operating the water electrolysis system 100 based on the current arrangement pattern of the electrolytic cells 211 and the profit obtained from operating the water electrolysis system 100 based on the arrangement pattern of the electrolytic cells 211 in which a change in the deterioration state is predicted. Therefore, the user can plan the replacement or rearrangement of the electrolytic cells 211 by referring to the profit information for each arrangement pattern before and after the replacement or rearrangement of the electrolytic cells.

[0093] Furthermore, in the embodiment described above, the input conditions also include information on constraints imposed on the production of products by the water electrolysis system 100. These constraints include either a constraint prioritizing the securing of hydrogen production volume by the water electrolysis system 100, or a constraint prioritizing the suppression of deterioration of the electrolytic cell 211. Therefore, the user can plan the replacement or relocation of the electrolytic cell 211 by referring to the information generated based on the constraints they prioritize.

[0094] Furthermore, in the embodiment described above, the calculation unit 63 includes in the arrangement patterns of the electrolytic cells 211 for predicting changes in the deterioration state an arrangement pattern in which the electrolytic cell 211 connected in series with the electrolytic cell 211 with a low resistance value is changed to an electrolytic cell 211 with a lower resistance value than the corresponding electrolytic cell 211 in the current arrangement pattern. Therefore, the user can formulate measures to suppress the accelerated deterioration of some electrolytic cells by referring to the arrangement patterns proposed by the maintenance support system 200.

[0095] In the embodiments described above, an example was given in which the condition input unit 61 (see Figure 2) receives input conditions from the user, but the present invention is not limited to this. For example, an input condition generation unit may be provided that automatically generates input conditions based on information such as the past operating patterns of the water electrolysis system 100, hydrogen demand forecast information, the operation policy of the water electrolysis system 100, and recommended placement guidelines for the electrolytic cell 211.

[0096] Furthermore, the maintenance support system 200 according to the present invention may include a function unit that automatically generates and outputs operating patterns and constraints that minimize the life cycle cost of the water electrolysis system 100.

[0097] Furthermore, the embodiments described above are intended to explain the configuration of the apparatus and system in detail and specifically in order to make the present invention easier to understand, and are not necessarily limited to those comprising all the configurations described.

[0098] Furthermore, the control lines or information lines shown as solid lines in Figures 2 and 3 are those deemed necessary for explanation and do not necessarily represent all control lines or information lines in the actual product. In reality, it can be assumed that almost all components are interconnected. [Explanation of symbols]

[0099] 1…DC power supply, 2, 2a~2c…Electrolytic cell group, 3…Hydrogen vapor-liquid separator, 4…Oxygen vapor-liquid separator, 5…Pump, 6…Heat exchanger, 21, 21a-1~21c-3…Electrolytic cell set, 61…Condition input unit, 62…Database, 63…Calculation unit, 64…Display unit, 100…Water electrolysis system, 200…Maintenance support system, 211, 211a-1~211c-6…Electrolytic cell

Claims

1. A maintenance support system for an electrolytic system including multiple electrolytic cells connected in series and parallel, The system includes a calculation unit that, based on input information including at least electrolytic characteristic information of the electrolytic cell, information on the arrangement pattern of the electrolytic cell, and information on the operating conditions of the electrolytic system, predicts information on changes in the deterioration state of each of the multiple electrolytic cells for each arrangement pattern of the electrolytic cell, and outputs information on the predicted changes in the deterioration state of each electrolytic cell. Maintenance support system.

2. The calculation unit calculates information regarding the gains and losses obtained from the operation of the electrolysis system based on the predicted information regarding the deterioration state of each electrolytic cell, for each arrangement pattern of the electrolytic cells, and outputs the calculated information regarding the gains and losses. The maintenance support system according to claim 1.

3. The calculation unit calculates the operating state of the electrolytic cell based on the input information, and predicts information on the change in the deterioration state of each of the multiple electrolytic cells based on the calculated operating state information and the predicted deterioration rate information of the electrolytic cell. The maintenance support system according to claim 2.

4. The calculation unit calculates and outputs the difference between the profit obtained from operating the electrolytic system based on the current electrolytic cell arrangement pattern and the profit obtained from operating the electrolytic system based on the electrolytic cell arrangement pattern in which a change in the deterioration state is predicted. The maintenance support system according to claim 3.

5. The aforementioned operating conditions are determined by the control parameters of the current and water supplied to the electrolytic cell. The maintenance support system according to claim 3.

6. The input information also includes information on constraints imposed on the production of products by the electrolysis system. The maintenance support system according to claim 5.

7. The aforementioned constraints include constraints that prioritize securing the production volume of the product by the electrolysis system, or constraints that prioritize suppressing the deterioration of the electrolytic cell. The maintenance support system according to claim 6.

8. The information regarding gains and losses obtained from the operation of the electrolysis system includes at least one of the following: information on the expected production volume of the product by the electrolysis system; information on the expected sales profit of the product by the electrolysis system; and information on the asset value of the deteriorated electrolytic cell. The maintenance support system according to claim 6.

9. The electrolysis system is a water electrolysis system that generates hydrogen by electrolyzing water, and is powered by electricity supplied from a single DC power source, and has an electrolysis cell group in which multiple electrolytic cell sets, each consisting of multiple electrolytic cells connected in series, are connected in parallel. The maintenance support system according to claim 6.

10. The calculation unit includes in the electrolytic cell arrangement pattern for predicting changes in the degradation state an arrangement pattern in which the electrolytic cell connected in series with the electrolytic cell with the lowest resistance value is changed to an electrolytic cell with a lower resistance value than the corresponding electrolytic cell in the current arrangement pattern. The maintenance support system according to claim 9.

11. A maintenance support method for an electrolytic system including multiple electrolytic cells connected in series and parallel, comprising a maintenance support system for an electrolytic system, The calculation unit has a procedure for predicting information on changes in the deterioration state of each of the multiple electrolytic cells for each electrolytic cell arrangement pattern, based on input information which includes at least electrolytic characteristic information of the electrolytic cell, information on the arrangement pattern of the electrolytic cell, and information on the operating conditions of the electrolytic system, and outputting information on the predicted changes in the deterioration state of each electrolytic cell. Maintenance support method.

Images