How to operate multiple electrolytic cell stacks

Abstract

A method of operating a plurality of electrolyzer stacks, each of the plurality of electrolyzer stacks being configured to be supplied with water and electrical energy to electrochemically produce at least a first reactant gas at a first electrode type of each of the electrolyzer stacks, the first reactant gas produced by each of the plurality of electrolyzer stacks being combined into a first gas stream; The method includes determining a concentration of an impurity in the first gas stream originating from a second reactant gas electrochemically produced at a second electrode type of each of the electrolytic cell stacks, generating a trigger signal when a concentration of the second reactant gas impurity in the combined first reactant gas exceeds a specific second reactant gas level, and when the trigger signal is generated, identifying at least one electrolytic cell stack of the plurality of electrolytic cell stacks that is performing poorly with respect to excessive supply of the second reactant gas impurity to the first gas stream by measuring a current density of the at least one electrolytic cell stack of the plurality of electrolytic cell stacks.

Description

Background Art

[0001] Many electrolysis processes have industrial applications. For example, electrolysis of water provides a source of hydrogen and oxygen. Alternatively, electrolysis of water containing sodium chloride can provide a source of hydrogen, chlorine, and sodium hydroxide. Other chemistries using electrolysis of water are certainly possible, but the electrolysis process of water basically involves decomposing water into its components.

[0002] In a water electrolyzer, water is split into its components, namely hydrogen gas and oxygen gas. The electrolyzer essentially comprises a cathode electrode, an anode electrode, and an electrolyte. Hydrogen is generated at the cathode via the hydrogen evolution reaction (HER). Oxygen is generated at the anode via the oxygen evolution reaction (OER).

[0003] Explanation For the operation of a plurality of electrolyzer stacks, it is useful to control the correct performance of each of the electrolyzer stacks and / or each cell of the electrolyzer stack. The present invention relates to the field of electrolysis technology and more particularly to an improved method for operating an electrolysis cell / stack mainly with respect to monitoring of fault situations.

[0004] Considering a large-scale multi-megawatt hydrogen production facility consisting of dozens of water electrolyzers, it is necessary to have an efficient method to ensure high purity and low safety risk hydrogen production.

[0005] When such an electrolyzer park including a plurality of electrolyzer stacks is operating at full capacity, the oxygen and hydrogen separation in the electrolysis cell can be optimal. However, when a decrease in the availability of renewable energy reduces the operating capacity of one or more electrolyzers in the control system, the pressure gradient in the electrolysis cell can lead to hydrogen diffusion through the membrane to the oxygen side of the cell, or oxygen diffusion to the hydrogen side of the cell.

[0006] Hydrogen diffusion into an oxygen half-cell can create an explosive atmosphere if it exceeds the safe limit of approximately 2% hydrogen in oxygen, while oxygen diffusion into a hydrogen half-cell can reduce the purity of hydrogen, increasing energy consumption for purification purposes in subsequent process steps and reducing the overall efficiency of the system.

[0007] Using physical hydrogen and oxygen sensors to monitor the status of each electrolytic cell stack within multiple electrolytic cell stacks in a multi-MW facility could result in the installation of hundreds of sensors. Processes requiring hundreds of sensors are unreliable and can have very high maintenance costs associated with ensuring the accuracy of each sensor.

[0008] Therefore, the present invention relates to a method for operating multiple electrolytic cell stacks, an electrolytic cell stack operating device, and the use of the electrolytic cell stack operating device.

[0009] Advantageous modifications of the present invention are described in the dependent claims. All combinations of at least two features disclosed in the specification, claims, and drawings fall within the scope of the invention. To avoid repetition, features disclosed in accordance with the method shall also apply and be claimable in accordance with the system mentioned.

[0010] Throughout this description of the present invention, the order of the procedural steps is presented in such a way that the process is easily understood. However, those skilled in the art will recognize that many of the process steps may be performed in a different order and yield the same or corresponding results. In this sense, the order of the process steps can be changed accordingly. Some features are accompanied by count words to improve readability or to make assignments clearer, but this does not imply the presence of certain features. [Overview of the Initiative]

[0011] To achieve these and other advantages, a method for operating multiple electrolytic cell stacks is provided in accordance with the object of the present invention, as embodied and broadly described herein, wherein each of the multiple electrolytic cell stacks is supplied with water and electrical energy to electrochemically generate at least a first reaction gas in a first electrode type of each electrolytic cell stack, and the first reaction gas generated by each of the multiple electrolytic cell stacks is joined to a first gas stream, the method comprising the following steps: In one step, the concentration of impurities in the first gas stream originating from the second reaction gas electrochemically generated at each second electrode type of the electrolytic cell stack is determined. In another step, a trigger signal is generated if the concentration of impurities from the second reaction gas in the combined first reaction gas exceeds a certain second reaction gas level. In yet another step, at least one of the multiple electrolytic cell stacks is identified, which is less efficient at supplying an excess of the second reaction gas impurities to the first gas stream by measuring the current density of at least one of the multiple electrolytic cell stacks when a trigger signal is generated.

[0012] An electrolytic cell stack may be a stack of electrolytic cell cells that are stacked and electrically coupled to one another with respect to the power supplied to the stack, and each electrolytic cell may include an anode electrode and a cathode electrode, the anode electrode and cathode electrode being different electrode types and positioned on opposite sides of a membrane that can act as an electrolyte. The amount of gas electrolytically produced at the anode electrode and / or cathode electrode can be collected from each electrolytic cell to construct an anode flow of gas for the anode electrode, as well as a cathode flow of gas at the cathode electrode of each electrolytic cell stack.

[0013] The electrolytic cell stack can electrochemically generate a first reaction gas at the anode electrode and simultaneously generate a different first reaction gas at the cathode electrode of the electrolytic cell stack. The first reaction gas can be a reaction product formed by the electrolytic reaction at each type of electrode.

[0014] The trigger signal may be an alarm or alarm signal generated when, for example, the concentration of a second reaction gas, determined by a gas sensing sensor, exceeds a certain limit.

[0015] The first reaction gas flows from multiple individual electrolytic cell stacks can be combined by a system of pipes fluidly connected to each electrolytic cell stack, with the pipes connected accordingly. The combined first gas flows can be collected using a tank, which is connected to the pipe system accordingly. As long as all impurities in the mixture remain below the threshold, should we state that some impurities in certain stacks may exceed the threshold?

[0016] According to one embodiment, the identification of a low-performance electrolytic cell stack by measuring the current density of the electrolytic cell stack can be performed alternatively or additionally by measuring the current density of a subsystem of the electrolytic cell stack, for example, as part of and / or individual electrolytic cell stack cells.

[0017] According to one embodiment, the measurement of the current density of at least one electrolytic cell stack may be triggered by a trigger signal, and / or the measurement of the current density may be continuously monitored, and if triggered by a trigger signal, the measured value may be analyzed.

[0018] In other words, this method provides a solution in which, instead of using multiple gas sensing sensors to monitor the status of all electrolytic cell stacks among multiple electrolytic cell stacks, at least one sensor may be placed in the first gas stream and / or in the storage tank for the combined and / or collected reaction gases, such as hydrogen gas and oxygen gas, generated by some of the electrolytic cell stacks. If the impurity levels in the first gas stream and / or the storage tank, i.e., the concentration of the second reaction gas, are within the required safety and quality levels, for example, less than 2% hydrogen gas in oxygen gas, then all electrolytic cell stacks supplying the storage tank are considered to be functioning correctly. If the impurity threshold of the second reaction gas in the first reaction case is exceeded, an alarm signal is triggered, and an algorithm can be used to identify the defective electrolytic cell stack.

[0019] When an alarm signal is triggered, the control system, acting as an electrolytic cell stack operator, can determine the current density generated by each individual electrolytic cell stack supplied to the storage tank. For each of these electrolytic cell stacks, a calibration curve can be pre-set that correlates the determined current density of the individual electrolytic cell stack with the concentration of hydrogen gas in the generated oxygen gas. Thus, the determined current density value can be used as a soft or virtual sensor for determining impurity concentration.

[0020] Hydrogen gas can be generated by a diffusion process from the cathode electrode of the cells in the electrolytic cell stack to the respective anode electrodes on the oxygen side of the cells in the electrolytic cell stack. This means that the anodic hydrogen content can be determined by using a calibration curve.

[0021] By comparing the actual current density with a calibration curve, an algorithm can be used to determine the current density of individual electrolytic cell stacks. This can be used to identify defective or underperforming electrolytic cell stacks, and the power supplied to those underperforming stacks can be bypassed or disconnected.

[0022] As a result, a low-performance electrolytic cell stack can be maintained, and as a result, the hydrogen gas concentration in the generated oxygen gas can be kept below the safety limit. Also, regarding the production of hydrogen gas, the oxygen gas concentration in the produced and collected hydrogen gas can be maintained below the required quality level.

[0023] Advantageously, based on the existing calibration curve of the electrolytic cell stack, the amounts of anode hydrogen and cathode oxygen for each electrolytic cell stack can be determined in real time without disconnecting the individual electrolytic cell stacks. By measuring the impurity concentrations of anode hydrogen and / or cathode oxygen in the combined first gas stream in the pipe and / or tank, an early detection system can be set up. As a result, redundancy can be provided to the physical sensors placed in the collection tank where the hydrogen gas and oxygen gas are stored, thereby improving the reliability of the system.

[0024] This makes it possible to place at least one sensor in the combined first gas stream and / or in the storage tank instead of using individual sensors to monitor the impurity concentration of each electrolytic cell stack, where the first gas stream as the hydrogen gas stream and / or oxygen gas stream generated by several electrolytic cell stacks is collected. If the impurity level determined by the sensor exceeds the threshold value, an alarm signal or a trigger signal can be generated, and an algorithm can be used to identify the faulty electrolytic cell stack by measuring the current density of each electrolytic cell stack using the determined current density value as a soft sensor.

[0025] According to one aspect, the first reaction gas electrochemically generated with the first electrode type is oxygen, and the second reaction gas electrochemically generated with the second electrode type is hydrogen. Alternatively or additionally, the first reaction gas electrochemically generated with the first electrode type is hydrogen, and the second reaction gas electrochemically generated with the second electrode type is oxygen.

[0026] That is, oxygen gas can be generated as the first reaction gas at the anode electrode, and / or hydrogen can be generated as the first reaction gas at the cathode electrode.

[0027] This means that, using the method described above, the hydrogen content in the oxygen stream can be monitored in the same way as the oxygen content in the hydrogen stream, and corrective measures can be taken when the corresponding impurity level threshold is reached. This can increase the purity level of oxygen gas in the hydrogen gas, and by determining the hydrogen level in the oxygen gas, the safety risk can be reduced by this soft sensing.

[0028] According to one aspect, the identification of at least one low-performance electrolyzer stack from a plurality of electrolyzer stacks is performed by comparing the measured current density of at least one electrolyzer stack with a critical current density. In particular, at least one low-performance electrolyzer stack can be identified when the measured current density of that electrolyzer stack is below the critical current density.

[0029] This is because the typical relationship between the current density and the impurity level of the electrolyzer stack is inversely proportional, which can be shown, at least approximately, by the polarization curve.

[0030] According to one aspect, when the first reaction gas is oxygen, a specific second reaction gas level is a hydrogen reaction gas level. When a specific second reaction gas level is an oxygen reaction gas level, the first reaction gas is hydrogen. In particular, the hydrogen reaction gas level and the oxygen reaction gas level may be different.

[0031] According to one aspect, the current density of each of some of the plurality of electrolyzer stacks is measured, and each of the measured current densities is compared with the individual critical current density assigned to each of the some electrolyzer stacks, and a single low-performance electrolyzer stack having the lowest measured current density below its individual critical current density is identified, and the low-performance electrolyzer stack is identified.

[0032] In this regard, the identified low-performance electrolytic cell stack can be considered the one that produces the highest proportion of impurities because its current density is the lowest compared to its individual critical current densities.

[0033] In other words, the electrolytic cell stack that performs the worst in terms of impurity generation should be identified, and in particular, this identified electrolytic cell stack can be disabled or shut down.

[0034] According to one embodiment, the critical current density is updated during the operation of multiple electrolytic cell stacks to account for the degradation of the electrolytic cell stacks.

[0035] During operation, the film may degrade or deteriorate over time, eventually leading to a higher diffusion rate of gas from one electrolytic half-cell to the other in the electrolytic cell stack. This can cause the calibration curve of the electrolytic cell stack to shift upward and / or change the critical current density of the electrolytic cell stack. This can change over time, for example, the 2% impurity threshold may change to, for example, 1.0 A / cm². 2 From 1.2 A / cm 2 This means that it can result from a higher current density.

[0036] If the current density is determined for each electrolytic cell stack, it allows for the calibration curve, and the critical current density of each cell, to be updated individually as the electrolytic cells change over time.

[0037] For example, if multiple electrolytic cell stacks are manufactured over two years, the calibration curves and / or critical current densities of all or individual electrolytic cell stacks can be updated. For this update, the current density and voltage of each electrolytic cell stack are measured at least hourly, or periodically, to update the calibration curves and / or critical current densities in particular. The calibration curves can be updated by storing these values ​​to operate the electrolytic cell stacks at different operating points caused by the amount of electrical energy supplied to them over time. Alternatively or additionally, the production load can be distributed among some of the multiple electrolytic cell stacks to operate them at different setpoints, thereby determining the calibration curves and / or critical current densities. In other words, the setpoints of operation for the electrolytic cell stacks can be swept over time.

[0038] According to one embodiment, the individual critical current densities of several electrolytic cell stacks are updated during the operation of these electrolytic cell stacks to account for the degradation of these electrolytic cell stacks.

[0039] According to one embodiment, the updated critical current density of the electrolytic cell stack and / or the updated individual critical current densities are determined by a linear relationship between the operating time of at least one electrolytic cell stack and the critical current density of that electrolytic cell stack.

[0040] In other words, based on the aging curve of each electrolytic cell stack in the calibration curve, the shift of the calibration curve over time can be used to determine the critical current density of each individual electrolytic cell stack.

[0041] According to one embodiment, the updated critical current density of the electrolytic cell stack and / or the updated individual critical current densities are determined during the operation of the multiple electrolytic cell stacks by operating at least some of the multiple electrolytic cell stacks at different setpoints.

[0042] The current density determines how much oxygen and hydrogen are produced at each operating point. In other words, by comparing that operating point to a given calibration curve that can be updated during operation, the crossover and diffusion of one gas to the other side of the electrolytic cell stack membrane can be determined.

[0043] By shifting or modifying the operating point of the electrolytic cell stack, the production load of individual electrolytic cell stacks in multiple electrolytic cell stacks can be shifted. The setpoint, or operating point, of each electrolytic cell stack can be defined by operating conditions, which are primarily determined by the voltage and current supplied to the electrolytic cell stack, under which the electrolytic cell stack operates to produce a specified first reaction gas.

[0044] Each electrolytic cell stack can be configured to determine DC and / or AC current and DC and / or AC voltage measurements. In particular, these measurements can be used for electrochemical impedance spectroscopy analysis, which ultimately allows for determining the degradation of the analyzed electrolytic cell stack based on the results of the electrochemical impedance spectroscopy analysis after several hours of operation, using this as input, and / or updating the calibration curve.

[0045] According to one embodiment, the updated critical current density of the electrolytic cell stack and / or the updated individual critical current densities are determined by storing the voltage and current density values ​​of the electrolytic cell stack during the operation of multiple electrolytic cell stacks at different setpoints within the operating time.

[0046] According to one embodiment, the updated critical current density of the electrolytic cell stack and / or the updated individual critical current densities are determined by impedance spectroscopic measurements of at least some of the electrolytic cell stacks among a plurality of electrolytic cell stacks.

[0047] Advantageously, adapting the setpoint for operating the electrolytic cell stack can be done by impedance spectroscopic measurements, particularly to determine the polarization curves at different frequencies (impedance spectroscopy), or at least at the frequencies excited by the power supply to the electrolytic cell stack for operation. Especially low frequency fluctuations can even be triggered by the entire control system of a plant with multiple electrolytic cell stacks via the power supply.

[0048] In one embodiment, impedance spectroscopic measurements are performed by using harmonics injected by the power supplied to multiple electrolytic cell stacks.

[0049] According to one embodiment, an identified low-performance electrolytic cell stack is disconnected from the electrical energy it provides.

[0050] For this reason, if multiple electrolytic cell stacks are electrically connected in series, or if they are disconnected, for example by opening a switch, electrical energy can be bypassed.

[0051] According to one embodiment, the above step of identifying a single electrolytic cell stack having the lowest current density and disconnecting it from its supplied electrical energy can be repeated until no trigger signal is generated.

[0052] Advantageously, using this algorithm to identify electrolytic cell stacks that should be cut allows for maintaining a high level of production rate for the first reaction gas with a large number of electrolytic cell stacks, while still providing high quality and safety standards.

[0053] In one embodiment, a waiting period can be introduced after the identified electrolytic cell stack has been disconnected, and this waiting period is long enough to allow the electrolytic cell stack system to approach a new equilibrium or steady state before any further measurements of impurity concentrations are taken.

[0054] According to one embodiment, the concentration of impurities in the second reaction gas is determined by a gas sensing sensor for generating a trigger signal.

[0055] Such gas sensing sensors can be placed inside a tank that collects the first combined gas flow, and / or inside a pipe that carries the first combined gas flow before it enters the tank.

[0056] According to one embodiment, a gas sensing sensor is positioned to sense within a first gas flow. Alternatively or additionally, a gas sensing sensor is positioned to sense within a tank, which is configured for a plurality of electrolytic cell stacks to collect the first reaction gas of the first gas flow.

[0057] An electrolytic cell stack operating device was proposed. - A current density measurement input configured to receive current density measurements from each of multiple electrolytic cell stacks, - A switch control device configured to be signal-coupled to the switches of each of the multiple electrolytic cell stacks in order to disconnect any of the multiple electrolytic cell stacks from the supplied electrical energy, - Trigger signal interface and / or interface for gas sensing sensor, -Includes a current density measurement input, a switch control device, and a control device, in particular including a computer, which is signal-coupled to a first signal interface and / or an interface for a gas sensing sensor. The control device may be configured to perform a method for operating multiple electrolytic cell stacks as described above.

[0058] The use of the electrolytic cell stack operating device described above is proposed for controlling multiple electrolytic cell stacks.

[0059] To provide a further understanding of the present invention, the accompanying drawings, which are included and incorporated into and constitute part of this application, illustrate embodiments of the present invention and, together with the description, serve to illustrate the principles of the present invention. The drawings are shown below. [Brief explanation of the drawing]

[0060] [Figure 1] Figure 1 shows the calibration curve. [Figure 2] Figure 2 shows the system for the electrochemical generation of the first reaction gas. [Modes for carrying out the invention]

[0061] Figure 1 shows A / cm 2 A calibration curve is schematically sketched as a figure 102 showing the relationship between the current density j measured in and the concentration of hydrogen gas in oxygen gas measured in percent. In the figure, a limit curve 104 is drawn for identification of the critical current density j, which can be determined where curve 102 and the limit curve 104 intersect each other.

[0062] Figure 2 schematically sketches a system for the electrochemical generation of the first reaction gas, which may be oxygen gas or hydrogen gas.

[0063] The system includes a power supply 210 and a plurality of electrolytic cell stacks 202, 204, 206 configured to be electrically coupled in series with the power supply 210. Each of the plurality of electrolytic cell stacks 202, 204, and 206 can be disconnected from the power supply 210 by switches 203, 205, and 207 to bypass the current to the next electrolytic cell stack 202, 204, 206. A first reaction gas that can be electrochemically generated by each of the electrolytic cell stacks 202, 204, and 206 is joined to a first gas flow 230 by, for example, a system of pipes fluidly coupled to each of the electrolytic cell stacks 202, 204, and 206, and the first gas flow 230 can be supplied to a tank 220 by, for example, a system of pipes.

[0064] A gas sensing sensor may be placed within the first gas flow 230 and / or tank 220. The physical gas sensing sensor may be configured to monitor the amount of oxygen gas in the hydrogen flow when the first gas flow 230 primarily contains hydrogen gas. Alternatively or additionally, when the first gas flow 230 primarily contains oxygen gas, the gas sensing sensor may be configured to monitor the amount of hydrogen gas in the oxygen gas flow. If hydrogen and oxygen gases are also produced by the electrolytic cell stack, a second piping system including a second tank (not shown herein) is connected to the electrolytic cell stack configured to produce oxygen and hydrogen gases.

[0065] If such a gas sensing sensor determines, for example, that the impurity concentration exceeds the threshold of 2% oxygen in hydrogen, the system is configured to generate a trigger signal or alarm signal, for example, by an electrolytic cell stack operator (not shown here). When a trigger signal is generated, the electrolytic cell stack operator can determine the optimal way to reduce the amount of oxygen impurities in the generated hydrogen gas while minimizing the impact on the hydrogen production rate by bypassing electrolytic cell stack 204 while maintaining electrolytic cell stacks 202 and 206 in operation, for example, as will be described in more detail by the following example.

[0066] The three electrolytic cell stacks 202, 204, and 206 can be configured to produce hydrogen at different production rates and with different oxygen impurity levels. The hydrogen gas produced by all three stacks 202, 204, and 206 can be directed to collect in a single common storage tank 220. As an example, stack 202 can produce 300 ml of hydrogen containing 3% oxygen impurities. 3 It has a hydrogen gas production rate of 200m / h, and stack 204 contains 5% oxygen impurities. 3 Stack 206 produces hydrogen gas at a rate of 1 / h and contains 800m of oxygen impurities. 3It produces hydrogen at a rate of 1 / h. When these hydrogen gas streams are collected in a storage tank equipped with a physical oxygen sensor, they have a total oxygen gas impurity content of 2.07%, which is above the 2% threshold of 10⁴.

[0067] When a trigger signal is generated, the electrolytic cell stack operator is set to determine and / or analyze the current density of each individual stack 202, 204, and 206 by comparing the real-time value of the current density with the limit value of the calibration curve 102. The electrolytic cell stack operator identifies that stacks 202 and 204 are producing hydrogen with an oxygen content exceeding the allowable limit of 2%, but the electrolytic cell stack operator also determines that the overall oxygen level in the storage tank can be reduced from 2.07% to 1.54% by stopping electrolytic cell stack 204, for example by cutting off electrolytic cell stack 204, which has the lowest current density, thus avoiding the need to stop electrolytic cell stack 202.

[0068] Therefore, the electrolytic cell stack actuator can activate switches 203, 205, and 207 as shown in Figure 2 by bypassing electrolytic cell stack 204 while maintaining electrolytic cell stacks 202 and 206 in operation, thereby ensuring quality and safety standards while minimizing the reduction in production speed.

[0069] Similarly, the hydrogen content in the oxygen stream can also be monitored in this way, and as a result, when a threshold is reached, corresponding corrective measures can be taken. The invention described in the original claims of this application is listed below. [1] A method for operating a plurality of electrolytic cell stacks (202, 204, 206), each of the plurality of electrolytic cell stacks (202, 204, 206) being configured to be supplied with water and electrical energy to electrochemically generate at least a first reaction gas in each of the first electrode types of the electrolytic cell stacks (202, 204, 206), the first reaction gas generated by each of the plurality of electrolytic cell stacks (202, 204, 206) being joined to a first gas stream (230), To determine the concentration of impurities in the first gas stream (230) that originate from the second reaction gas electrochemically generated at each of the second electrode types of the electrolytic cell stack, A trigger signal is generated when the concentration of the impurities in the second reaction gas within the combined first reaction gas (230) exceeds a specific second reaction gas level (104). A method comprising, when the trigger signal is generated, identifying at least one of the plurality of electrolytic cell stacks (202, 204, 206) that performs poorly with respect to the excessive supply of the second reaction gas impurity to the first gas flow (230) by measuring the current density of at least one of the plurality of electrolytic cell stacks (202, 204, 206). [2] The method according to [1], wherein the first reaction gas electrochemically produced in the first electrode type is oxygen and the second reaction gas electrochemically produced in the second electrode type is hydrogen, or the first reaction gas electrochemically produced in the first electrode type is hydrogen and the second reaction gas electrochemically produced in the second electrode type is oxygen. [3] Identification of at least one low-performance electrolytic cell stack from the plurality of electrolytic cell stacks (202, 204, 206) is performed by comparing the measured current density of the at least one electrolytic cell stack with the critical current density (104), in particular identifying the at least one low-performance electrolytic cell stack if the measured current density is below the critical current density (104), according to the method of [1] or [2]. [4] The method according to [2] or [3], wherein, when the first reaction gas is oxygen, the particular second reaction gas level is the hydrogen reaction gas level, and when the first reaction gas is hydrogen, the particular second reaction gas level is the oxygen reaction gas level, in particular, different from the hydrogen reaction gas level and the oxygen reaction gas level. [5] The method according to [3] or [4] for identifying a low-performance electrolytic cell stack, wherein the current density of each of the plurality of electrolytic cell stacks (202, 204, 206) is measured, each of the measured current densities is compared with an individual critical current density assigned to each of the plurality of electrolytic cell stacks to identify a single low-performance electrolytic cell stack having the lowest measured current density below that individual critical current density. [6] The method according to any one of [1] to [5], wherein the critical current density is updated during the operation of the plurality of electrolytic cell stacks (202, 204, 206) to account for the degradation of the electrolytic cell stack. [7] The method according to [5], wherein the individual critical current densities of each of the several electrolytic cell stacks are updated during the operation of these electrolytic cell stacks to account for the degradation of these electrolytic cell stacks. [8] The method according to [6] or [7], wherein the updated critical current density of the electrolytic cell stack and / or the updated individual critical current densities of the electrolytic cell stack are determined during the operation of the plurality of electrolytic cell stacks by operating at least some of the plurality of electrolytic cell stacks at different set points. [9] The method according to any one of [6] to [8], wherein the updated critical current density of the electrolytic cell stack and / or the updated individual critical current densities of the electrolytic cell stack are determined by impedance spectroscopic measurements of at least some of the electrolytic cell stacks (202, 204, 206).

[10] The impedance spectroscopic measurement is performed by using harmonics injected by the power supplied to the plurality of electrolytic cell stacks, according to the method of [9].

[11] The method according to any one of [1] to

[10] , wherein the identified low-performance electrolytic cell stack is disconnected from the electrical energy supplied thereto.

[12] The method of

[11] , which is repeated until the trigger signal is no longer generated.

[13] The method according to any one of [1] to

[12] , wherein the concentration of impurities in the second reaction gas is determined by a gas sensing sensor for generating the trigger signal.

[14] The method according to [9], wherein a gas sensing sensor is positioned to sense in the first gas flow (230), or the gas sensing sensor is positioned to sense in a tank (220), the tank (220) is configured relative to the plurality of electrolytic cell stacks (202, 204, 206) to collect the first reaction gas of the first gas flow (230).

[15] Electrolytic cell stack operating device, A current density measurement input configured to receive current density measurements from each of the multiple electrolytic cell stacks (202, 204, 206), A switch control device configured to be signal-coupled to the respective switches (203, 205, 207) of the plurality of electrolytic cell stacks (202, 204, 206) in order to disconnect any of the plurality of electrolytic cell stacks (202, 204, 206) from the supplied electrical energy, Trigger signal interface and / or interface for gas sensing sensor, Apparatus comprising a control device, in particular including a computer, which is signal-coupled to the current density measurement input, signal-coupled to the switch control device, and signal-coupled to a first signal interface and / or the interface for the gas sensing sensor, wherein the control device is configured to perform the method described in any one of [1] to

[14] .

Claims

1. A method for operating a plurality of electrolytic cell stacks (202, 204, 206), wherein each of the plurality of electrolytic cell stacks (202, 204, 206) is configured to be supplied with water and electrical energy to electrochemically generate at least a first reaction gas in each of the first electrode types of the electrolytic cell stacks (202, 204, 206), and the first reaction gas generated by each of the plurality of electrolytic cell stacks (202, 204, 206) is joined to a first gas stream (230). To determine the concentration of impurities in the first gas stream (230) that originate from the second reaction gas electrochemically generated at each of the second electrode types of the electrolytic cell stack, A trigger signal is generated when the concentration of the impurities in the second reaction gas within the combined first reaction gas (230) exceeds a specific second reaction gas level (104). A method comprising, when the trigger signal is generated, identifying at least one of the plurality of electrolytic cell stacks (202, 204, 206) that performs poorly with respect to the excessive supply of the second reaction gas impurity to the first gas flow (230) by measuring the current density of at least one of the plurality of electrolytic cell stacks (202, 204, 206).

2. The method according to claim 1, wherein the first reaction gas electrochemically produced with the first electrode type is oxygen, and the second reaction gas electrochemically produced with the second electrode type is hydrogen, or the first reaction gas electrochemically produced with the first electrode type is hydrogen, and the second reaction gas electrochemically produced with the second electrode type is oxygen.

3. The method according to claim 1, wherein the identification of at least one low-performance electrolytic cell stack from the plurality of electrolytic cell stacks (202, 204, 206) is performed by comparing the measured current density of the at least one electrolytic cell stack with the critical current density (104).

4. The method according to claim 3, wherein at least one low-performance electrolytic cell stack is identified when the measured current density falls below the critical current density (104).

5. The method according to claim 2, wherein when the first reaction gas is oxygen, the specific second reaction gas level is the hydrogen reaction gas level, and when the first reaction gas is hydrogen, the specific second reaction gas level is the oxygen reaction gas level.

6. The method according to claim 5, wherein the hydrogen reaction gas level and the oxygen reaction gas level are different.

7. The method according to claim 3, wherein the current density of several of the plurality of electrolytic cell stacks (202, 204, 206) is measured, each of the measured current densities is compared with an individual critical current density assigned to each of the electrolytic cell stacks to identify a single low-performance electrolytic cell stack having the lowest measured current density below that individual critical current density, thereby identifying the low-performance electrolytic cell stack.

8. The method according to claim 1, wherein the critical current density is updated during the operation of the plurality of electrolytic cell stacks (202, 204, 206) to account for the degradation of the electrolytic cell stack.

9. The method according to claim 7, wherein the individual critical current densities of each of the several electrolytic cell stacks are updated during the operation of these electrolytic cell stacks to account for the degradation of these electrolytic cell stacks.

10. The method of claim 8, wherein the updated critical current density of the electrolytic cell stack and / or the updated individual critical current densities of the electrolytic cell stack are determined during the operation of the plurality of electrolytic cell stacks by operating at least some of the plurality of electrolytic cell stacks at different set points.

11. The method of claim 8, wherein the updated critical current density of the electrolytic cell stack and / or the updated individual critical current densities are determined by impedance spectroscopic measurements of at least some of the plurality of electrolytic cell stacks (202, 204, 206).

12. The method according to claim 11, wherein the impedance spectroscopic measurement is performed by using harmonics injected by the power supplied to the plurality of electrolytic cell stacks.

13. The method according to claim 7, wherein the identified low-performance electrolytic cell stack is disconnected from the supplied electrical energy.

14. The method according to claim 13, wherein the process is repeated until the trigger signal is no longer generated.

15. The method according to claim 1, wherein the concentration of impurities in the second reaction gas is determined by a gas sensing sensor for generating the trigger signal.

16. The method according to claim 15, wherein the gas sensing sensor is positioned to sense within the first gas flow (230), or the gas sensing sensor is positioned to sense within a tank (220), the tank (220) being configured relative to the plurality of electrolytic cell stacks (202, 204, 206) to collect the first reaction gas of the first gas flow (230).

17. An electrolytic cell stack operating device, A current density measurement input configured to receive current density measurements from each of the multiple electrolytic cell stacks (202, 204, 206), A switch control device is configured to be signal-coupled to the respective switches (203, 205, 207) of the plurality of electrolytic cell stacks (202, 204, 206) in order to disconnect any of the plurality of electrolytic cell stacks (202, 204, 206) from the supplied electrical energy, A trigger signal interface and / or an interface for a gas sensing sensor, Apparatus comprising: a control device which is signal-coupled to the current density measurement input, signal-coupled to the switch control device, and signal-coupled to a first signal interface and / or the interface for the gas sensing sensor, wherein the control device is configured to perform the method according to any one of claims 1 to 16.

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