Method for setting an electrolyser

Abstract

The method (100) comprises: - determining (101) a plurality of state characteristic values of a cell stack of an electrolyser based on cell voltages determined for various operating temperatures of the cell stack at a predefined operating point, - determining (103) at least one curve (201, 203, 205) of the state characteristic values over various operating temperatures for a predefined service life, - selecting (105) the operating temperature at which the curve (201, 203, 205) of the state characteristic values is at a maximum, - setting (107) the selected operating temperature for operating the electrolyser.

Description

[0001]R. 405022 - 1 - Description Title Method for adjusting an electrolyzer The presented invention relates to a method for adjusting an electrolyzer, an electrolyzer, a computing unit and a computer program product according to the appended claims. State of the art Electrolyzers are electrochemical energy converters which are used, for example, to provide hydrogen. An important criterion for an electrolyzer is the overall efficiency over the operating time. During operation of an electrolyzer, different degradation of cells in a cell stack of the electrolyzer occurs, depending on the respectively selected operating parameters, such as temperature, current density, etc. In particular, the temperature in the cell stack has a major influence on the overall efficiency of the electrolyzer over its operating time.A higher temperature increases the efficiency of the electrolyzer, while at the same time, higher temperatures accelerate the aging process of the electrolyzer's cell stack, causing the cell stack's efficiency to decrease over its lifetime. Accordingly, an optimal operating point must be found over the cell stack's operating life that optimally coordinates the efficiency and aging of the cell stack, as both variables depend on the operating temperature. R. 405022 - 2 - The aging process of a cell stack is complex and depends on many parameters, such as the operating temperature, the temperature distribution within the cell stack, the load profile, the respective manufacturing tolerances, the electrical conductivity of the respective reactants, operating pressures, etc.This means that no optimal operating point can be easily determined that ensures maximum overall efficiency over the operating life of an electrolyzer. Due to the complex aging process, which is also determined by manufacturing tolerances even under identical operating conditions, one and the same operating point cannot be optimally selected for different electrolyzers or different modules of an electrolyzer with regard to overall efficiency over the operating life. Disclosure of the Invention Within the scope of the invention presented, a method for adjusting an electrolyzer, an electrolyzer, a computing unit, and a program product are presented. Further features and details of the invention can be found in the respective subclaims, the description, and the drawings.Features and details described in connection with the method according to the invention naturally also apply in connection with the electrolyzer according to the invention or the computing unit according to the invention as well as the program product according to the invention and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is or can always be made reciprocally. The invention presented serves in particular to operate an electrolyzer energy-efficiently over its lifetime. Thus, according to a first aspect of the invention presented, a method for adjusting an electrolyzer is presented. The method presented comprises determining a plurality of condition characteristics of a cell stack of the electrolyzer based on values ​​for R.405022 - 3 - different operating temperatures of the cell stack at a predetermined operating point of determined cell voltages, determining at least one curve of the condition parameters over different operating temperatures for a predetermined service life, selecting the operating temperature at which the curve of the condition parameters is maximum and setting the selected operating temperature for operating the electrolyzer. In the context of the presented invention, a condition parameter is to be understood as a value that quantifies an energetic efficiency of a cell stack of an electrolyzer, in particular in relation to its service life. In the context of the presented invention, an operating temperature is to be understood as a temperature that is predominantly present in the cell stack of an electrolyzer during normal operation, ie, with possibly brief deviations.A condition value can be determined mathematically using a variety of different calculation methods. For example, the condition value can be calculated as the quotient of an upper calorific value (^). ^^^ ) and a cell voltage (^ ^^^^ ) can be determined according to formula (1). ^ ^ ^^^ ^^^^^ = ^ ^^^^ (1) From the cell voltage, the efficiency of the stack (^ ^^^^^ ) can be determined by converting the minimum required reaction enthalpy (Δ^) for hydrogen electrolysis (Higher Heating Value Δ^ = 285.8 kJ / mol) into a voltage (^ ^^^ ). The ratio of the minimum required reaction enthalpy (Δ^) to the actually required reaction enthalpy (^^^^^^) corresponds to the efficiency of the stack relative to the upper calorific value. The relationship according to formula (2) applies. R. 405022 - 4 - The current-voltage characteristics of a cell stack shift toward higher voltages due to aging effects over the lifetime of the cell stack, meaning the efficiency decreases. Factors influencing the aging of the cell stack over time (t) include the operating temperature, temperature distribution within the stack, the load profile (static and dynamic), manufacturing tolerances, electrical conductivity of the water, operating pressures, etc., so the following applies: Starting from a current cell voltage (^^^^^,^^^^^^) by taking into account the aging effect or an assumption for the aging effect (^ ^^^^,^^^ ) the future cell voltage (^^^^^^,^^^^^^^^) can be deduced, so that: ^^^^^,^^^^^^(^^^^^^,^^^^^^,^)= ^^^^^,^^^^^^(^^^^^^,^^^^^)+ ^^^^^,^^^(^^^^^,^)and Now it is necessary to determine an operating temperature that, depending on the operating point and the desired operating time, finds an optimal balance between the (temporary) efficiency gain due to a higher temperature and the increased aging rate. For this purpose, for example, for a given operating point (^ ^^^^ ) and different operating temperatures (^ ^^^^^ ) the average integral under the efficiency (^^^^^^,^^^^^^^^) over the operating time until the target operating time ((^ ^^^^^^ ) can be calculated according to formula (3). R. 405022 - 5 - The optimum operating temperature for a specific operating time and operating point is therefore determined according to formula (4) Enter a formula here. As soon as the optimal operating temperature has been determined, it can be set on the respective electrolyzer. The cell voltages (^^^^^^, Actual) provided according to the invention can be measured, for example, using a voltmeter. It can be provided that a large number of curves of the condition parameters are determined over different operating temperatures for a large number of different predetermined service lives, in particular for a predetermined operating point, and shown on a display. By displaying a large number of curves of condition parameters that were determined over different operating temperatures for a large number of different predetermined service lives, a technician can, for example, select an operating temperature that leads to a corresponding service life and set it on the corresponding electrolyzer.It can be provided that the condition characteristic mathematically maps the efficiency of the cell stack over the specified service life. It can further be provided that the determination of the plurality of condition characteristic values, the determination of the at least one curve of the condition characteristic values, the selection of the operating temperature, and the setting of the selected operating temperature are carried out repeatedly over the service life of the electrolyzer, so that the set operating temperature is dynamically adapted to a state, in particular a current state, of the electrolyzer and, for example, settles on a value or range of values ​​over time. The current state may differ from an earlier forecast.It can further be provided that a mathematical model is used to determine the plurality of condition parameters, wherein the mathematical model is formed on the basis of operating parameters determined on the cell stack of the electrolyzer and / or a plurality of cell stacks of electrolyzers. A mathematical model that is formed on the basis of a respective electrolyzer or a module of an electrolyzer system is specifically optimized for the respective properties of the electrolyzer, whereas a mathematical model that is formed on the basis of many electrolyzers or modules is particularly robust with regard to measurement tolerances and can possibly predict effects to be expected in the future, such as defects, so that maintenance work can be planned, for example. It can further be provided that the mathematical model comprises a machine learner that is trained to assign a condition parameter orto assign several state parameters. A machine learner, such as an artificial neural network, can be trained on the basis of predetermined training data to automatically determine an optimal setting of an electrolyzer based on the respective measured cell voltages. It can also be provided that the mathematical model is executed locally on a computing unit of the electrolyzer. A locally executed method enables direct and automatic adjustment of the electrolyzer by itself. R. 405022 - 7 - It can also be provided that the mathematical model is executed on a central server, wherein the central server is communicatively connected to a plurality of electrolyzers. A central server for executing the mathematical model enables central control of a plurality of electrolyzers by adapting the mathematical model.According to a second aspect, the presented invention relates to an electrolyzer for providing hydrogen, wherein the electrolyzer comprises a computing unit configured to carry out a method according to the first aspect of the invention. All advantages listed for the method for adjusting an electrolyzer according to the first aspect of the invention also apply to the electrolyzer according to the second aspect of the invention. According to a third aspect, the presented invention relates to a computing unit for adjusting a plurality of electrolyzers, wherein the computing unit is communicatively connected to the plurality of electrolyzers and configured to carry out a method according to the first aspect of the invention and to adjust a respective selected operating temperature at a respective electrolyzer, in particular according to the second aspect of the invention.In the context of the invention presented, a computing unit is understood to mean a computer, a processor, a control unit, or any other programmable circuit. In particular, the computing unit presented can be a central server that is communicatively connected to a plurality of electrolyzers or a plurality of modules of an electrolyzer. Alternatively, the computing unit can be a control unit integrated locally into an electrolyzer. According to a fourth aspect, the invention presented relates to a program product, wherein the program product comprises program code means that configure a computing unit to execute a possible embodiment of the method presented in R. 405022 - 8 - when executed on the computing unit. Further advantages, features, and details of the invention emerge from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings.The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination. Figure 1 shows a schematic representation of a possible embodiment of the presented method for adjusting an electrolyzer. Figure 2 shows an overview of several curves of characteristic state values ​​of a cell stack of an electrolyzer according to a possible embodiment of the presented method. Figure 1 shows a method 100 for adjusting an electrolyzer. The method 100 comprises a first determination step 101 in which a plurality of characteristic state values ​​of a cell stack of the electrolyzer are determined based on cell voltages determined for various operating temperatures of the cell stack at a predetermined operating point.Furthermore, the method 100 comprises a second determination step 103 in which at least one curve of the characteristic state values ​​is determined over various operating temperatures for a predetermined service life. Furthermore, the method 100 comprises a selection step 105 in which the operating temperature at which the curve of the characteristic state values ​​is maximum is selected, and a setting step 107 in which the selected operating temperature for operating the electrolyzer is set. Figure 2 shows a diagram 200 which spans an operating temperature on its abscissa and a characteristic state value R. 405022 - 9 - of a cell stack of an electrolyzer in the form of an average energy efficiency over the service life in [%] on its ordinate. A first curve 201 corresponds to characteristic state values ​​that were determined for a service life of 12 years.A second curve 203 corresponds to characteristic condition values ​​determined for a lifetime of 15 years. A third curve 205 corresponds to characteristic condition values ​​determined for a lifetime of 17 years. Curves 201, 203, and 205 are each marked at their maximum with a marker 207, since the characteristic condition value is optimal at this point, i.e., optimum efficiency is achieved for the respective lifetime. Accordingly, an operating temperature can be selected at the location of the marked characteristic condition values ​​for the respective lifetime and set on an electrolyzer.

Claims

R. 405022 - 10 - Claims 1. Method (100) for setting an electrolyzer, the method (100) comprising: - determining (101) a plurality of characteristic state values ​​of a cell stack of the electrolyzer on the basis of cell voltages determined for different operating temperatures of the cell stack at a predetermined operating point, - determining (103) at least one profile (201, 203, 205) of the characteristic state values ​​over different operating temperatures for a predetermined service life, - selecting (105) the operating temperature at which the profile (201, 203, 205) of the characteristic state values ​​is maximum, - setting (107) the selected operating temperature for operating the electrolyzer.

2. The method (100) according to claim 1, characterized in that a plurality of curves (201, 203, 205) of the characteristic condition values ​​are determined over various operating temperatures for a plurality of different predetermined service lives and displayed on a display.Method (100) according to claim 1 or 2, characterized in that the condition characteristic mathematically maps an efficiency of the cell stack over the predetermined service life. R. 405022 - 11 - 4. The method (100) according to any one of the preceding claims, characterized in that the determination of the plurality of characteristic state values, the determination of the at least one profile (201, 203, 205) of the characteristic state values, the selection of the operating temperature, and the setting of the selected operating temperature are carried out repeatedly over a service life of the electrolyzer.

5. The method (100) according to any one of the preceding claims, characterized in that a mathematical model is used to determine the plurality of characteristic state values, wherein the mathematical model is formed based on operating parameters determined on the cell stack of the electrolyzer and / or a plurality of cell stacks of electrolyzers. 6.The method (100) according to claim 5, characterized in that the mathematical model comprises a machine learner trained to assign a state characteristic value to respective operating parameters of a cell stack.

7. The method (100) according to claim 5 or 6, characterized in that the mathematical model is executed locally on a computing unit of the electrolyzer.

8. The method (100) according to claim 5 or 6, characterized in that the mathematical model is executed on a central server, wherein the central server is communicatively connected to a plurality of electrolyzers. R. 405022 - 12 - 9. An electrolyzer for providing hydrogen, the electrolyzer comprising a computing unit configured to carry out a method (100) according to any one of claims 1 to 8.

10. A computing unit for setting a plurality of electrolyzers, the computing unit being communicatively connected to the plurality of electrolyzers and configured to carry out a method (100) according to claim 8 and to set a respective selected operating temperature at a respective electrolyzer.

11. A program product, the program product comprising program code means that configure a computing unit to carry out a method (100) according to any one of claims 1 to 8 when executed on the computing unit.

Images