Temperature management method for an electrolytic cell stack, open-loop and / or closed-loop control unit, and electrolysis system having the electrolytic cell stack

Abstract

The invention relates to a temperature management method for an electrolytic cell stack, comprising at least the method steps of: measuring an instantaneous stack voltage; processing a stack voltage measured value of the measurement of the stack voltage; applying the processed stack voltage measured value to more than one characteristic temperature-voltage curve of the electrolytic cell stack in order to compare the processed stack voltage measured value with voltage values of the characteristic temperature-voltage curves that are each associated with a target temperature; carrying out open-loop and / or closed-loop control of at least one heating unit of the external temperature control device in order to increase a heating power if at least one of the characteristic temperature-voltage curves indicates, on the basis of the processed stack voltage measured value, that an actual temperature lies below the associated target temperature; carrying out open-loop and / or closed-loop control of the at least one heating unit of the external temperature control device in order to decrease the heating power if at least one of the characteristic temperature-voltage curves indicates, on the basis of the processed stack voltage measured value, that the actual temperature lies above the associated target temperature; and deactivating the external temperature control device if the characteristic temperature-voltage curves indicate, on the basis of the processed stack voltage measured value, that the actual temperature lies in a range close to the target temperature.

Description

[0001] R.413536

[0002] - 1 -

[0003] Description

[0004] Temperature management method for an electrolysis cell stack, control and / or regulation unit and electrolysis system with the electrolysis cell stack

[0005] State of the art

[0006] It is known to equip electrolyzers with cooling systems and to use extensive parameters such as flow rates to control the cooling. However, depending on the operating mode and / or aging, particularly of an electrolysis cell stack in the electrolyzer, warming can also be advantageous. The present invention takes this into account and relies on control using intensive parameters such as temperature.

[0007] Disclosure of the invention

[0008] A temperature management method, in particular a temperature control method, for an electrolysis cell stack, especially a solid oxide electrolysis cell (SOEC) stack or a protonic ceramic electrochemical electrolysis cell (PCEC) stack, is proposed using an external temperature control device, comprising at least the following method steps: a) measuring an instantaneous stack voltage, b) processing a stack voltage measurement, c) applying the processed stack voltage measurement to more than one, preferably three, characteristic temperature-voltage curves of the electrolysis cell stack to compare the processed stack voltage measurement with the voltage values ​​of the characteristic temperature-voltage curves corresponding to a setpoint temperature, and d) controlling and / or regulating at least one heating unit of the external temperature control device to increase a heating power, in particular R.413536

[0009] - 2 -

[0010] Increasing the heating power of at least one heating unit when at least one of the characteristic temperature-voltage curves, based on the processed stack voltage measurement, indicates that an actual temperature is below the corresponding setpoint temperature; controlling and / or regulating at least one cooling unit of the external temperature control device or the at least one heating unit of the external temperature control device to reduce the heating power, in particular reducing the heating power of at least one heating unit when at least one of the characteristic temperature-voltage curves, based on the processed stack voltage measurement, indicates that the actual temperature is above the corresponding setpoint temperature; and deactivating the external temperature control device, in particular the heating unit and the cooling unit, when the characteristic temperature-voltage curves, based on the processed stack voltage measurement, indicate thatthat the actual temperature is at or close to the setpoint temperature. This advantageously optimizes the operation of the electrolysis cell stack. Advantageously, the efficiency, energy consumption, and / or service life of the electrolysis cell stack and / or other components of an electrolyzer can be improved, particularly compared to non-temperature-controlled or merely cooled electrolysis cell stacks. The control and / or regulation of the external temperature control device is preferably achieved by setting a temperature, in particular by setting the setpoint temperature (obtained from the characteristic temperature-voltage curves). Preferably, the temperature management method is temperature-controlled and / or temperature-regulated. Preferably, the external temperature control device is temperature-controlled and / or temperature-regulated.

[0011] The electrolysis cell stack is, in particular, part of an electrolyzer or electrolysis system, which may preferably comprise one or more electrolysis cell stacks. The temperature control device is preferably specifically designed for temperature control of the electrolysis cell stack. However, it is also conceivable that an electrolyzer has a common temperature control device for several electrolysis cell stacks, which can be controlled separately for each connected electrolysis cell stack or which only allows common control for several or all connected electrolysis cell stacks. R.413536

[0012] - 3 -

[0013] In particular, the electrolysis cell stack or the electrolyzer with the electrolysis cell stack comprises a measuring device / measuring instrument for recording the instantaneous stack voltage of at least the electrolysis cell stack, preferably the individual stack voltages of all electrolysis cell stacks of the electrolyzer. For example, the stack voltage of an SOEC stack in thermoneutral operation of the SOEC stack at a temperature range between 550°C and 850°C is 1.29 V multiplied by the number of electrolysis cells in the SOEC stack. A stack voltage above this value indicates, for example, exothermic operation / a cooling requirement for the electrolysis cell stack. A stack voltage below this value indicates, for example, endothermic operation / a heating requirement for the electrolysis cell stack. In thermoneutral operation of the electrolysis cell stack, there is generally no need for temperature control.For example, an electrolysis cell stack can transition from the thermoneutral operating state to the endothermic operating state during operation if hydrogen production of the electrolysis cell stack decreases / is reduced.

[0014] In particular, the electrolysis cell stack or the electrolyzer with the electrolysis cell stack comprises a control and / or regulation unit. The control and / or regulation unit of the electrolysis cell stack or the electrolyzer with the electrolysis cell stack is preferably designed for processing the stack voltage measurement value(s), particularly by means of computer technology and / or algorithms. A "control and / or regulation unit" is understood to mean, in particular, a unit with at least one control electronics unit. "Control electronics" is understood to mean, in particular, a unit with a processor and a data memory unit, as well as an operating program stored in the data memory unit. "Designed" is understood to mean, in particular, specifically programmed, designed, and / or equipped.The fact that an object is intended for a specific function should be understood in particular to mean that the object fulfills and / or performs this specific function in at least one application and / or operating state.

[0015] Furthermore, the control and / or regulation unit is preferably designed for applying the processed stack voltage measurement value to the characteristic temperature-voltage curves of the electrolysis cell stack, particularly using computer-based and / or algorithm-based methods. Furthermore, R.413536

[0016] - 4 -

[0017] The control unit may optionally be provided for determining the actual temperature from the characteristic temperature-voltage curves of the electrolysis cell stack, particularly using computer-based and / or algorithm-based methods. To determine the actual temperature, the measured stack voltage is compared with stack voltages contained in the characteristic temperature-voltage curves, and a corresponding temperature value is read out, from which the actual temperature is then preferably determined. Furthermore, the control unit may preferably be provided for comparing the determined actual temperatures with the corresponding target temperatures, particularly using computer-based and / or algorithm-based methods.Preferably, the control unit is designed to compare the processed stack voltage measurement with the voltage values ​​of the characteristic temperature-voltage curves corresponding to a specific target temperature. The target temperature can also be a target temperature range. The target temperature range is preferably between 550°C and 850°C, particularly for SOEC stacks. Furthermore, the control unit is preferably designed to control the external temperature control device, especially the heating and cooling units, particularly by means of computer technology and / or algorithms. Alternatively, however, it is also conceivable that some of the aforementioned processes are performed by one or more computing units separate from the control unit, which are preferably networked with the control unit.

[0018] The external temperature control unit is specifically designed to supply heat externally (heating unit) and to dissipate heat externally (cooling unit). The cooling unit could comprise a liquid cooling system, an air cooling system, or a hybrid cooling system or a cooling system based on another cooling method. The heating unit could be a furnace heater based on electric resistance heating, induction, a gas burner, or the like, or it could be designed with heating elements / heatable elements integrated into the electrolyzer.

[0019] Furthermore, it is proposed that one of the characteristic temperature-voltage curves represents a plot of a characteristic inlet temperature of an R.413536

[0020] - 5 -

[0021] The characteristic temperature-voltage curves comprise a plot of a characteristic inlet temperature of an anode and / or anode compartment of the electrolysis cell stack against a cell voltage of the electrolysis cell stack, and / or one of the characteristic temperature-voltage curves comprises a plot of a characteristic inlet temperature of an anode and / or anode compartment of the electrolysis cell stack against a cell voltage of the electrolysis cell stack. This enables advantageous, intensive parameter-based temperature control of the electrolysis cell stack, which is particularly reliable and / or accurate. The inlet temperature of the cathode and / or the cathode compartment is preferably a reactant gas temperature at an inlet of the cathode and / or the cathode compartment of the electrolysis cell stack. In this case, the actual temperature can be determined from the stack voltage measurement, which corresponds to a corresponding reactant gas temperature in the characteristic temperature-voltage curve.The inlet temperature of the anode and / or the anode compartment is preferably the air temperature at the inlet of the anode and / or the anode compartment of the electrolysis cell stack. In this case, the actual temperature can be determined from the stack voltage measurement, which corresponds to a specific air temperature in the characteristic temperature-voltage curve. To initiate temperature control, it may be sufficient if this is indicated by one of the determined actual temperatures or by comparing the processed stack voltage value with a target temperature from a characteristic temperature-voltage curve. Alternatively, it might be necessary for several specific actual temperatures or comparisons of the processed stack voltage value with target temperatures from several characteristic temperature-voltage curves to indicate the initiation of temperature control.The cell voltage is, in particular, the voltage drop across a single electrolysis cell of the electrolysis cell stack. The cell voltage is preferably determined by processing the stack voltage measurement. The stack voltage is, in particular, the voltage drop across the entire electrolysis cell stack. For example, the cell voltage of an electrolysis cell of the SOEC stack in thermoneutral operation of the SOEC stack at a temperature range between 550°C and 850°C is 1.29 V.

[0022] - 6 -

[0023] Furthermore, it is proposed that another of the characteristic temperature-voltage curves includes a plot of a characteristic outlet temperature of the cathode and / or cathode compartment or the anode and / or anode compartment, or of a parameter proportional to one of these values, against the cell voltage of the electrolysis cell stack. This advantageously allows for further improvement of the temperature control of the electrolysis cell stack, particularly its accuracy and / or reliability. The outlet temperature of the cathode and / or cathode compartment is preferably a reactant gas temperature at an outlet of the cathode and / or cathode compartment.

[0024] Furthermore, it is proposed that the processing of the stack voltage measurement includes a division of the measured stack voltage by a number of electrolysis cells in the electrolysis cell stack, preferably performed by the control unit and / or by a computer-implemented and / or algorithm-based method. This can advantageously improve temperature control. In particular, this division determines the cell voltage of the individual electrolysis cells in the electrolysis cell stack.

[0025] Furthermore, it is proposed that the processing of the stack voltage measurement includes smoothing the voltage measurement or a cell voltage measurement derived from it using a tunable low-pass filter. This advantageously improves temperature control. It allows for the filtering out of voltage spikes and / or measurement errors that could lead to an incorrect determination of the actual temperature and / or an incorrect adjustment to the setpoint temperature. In particular, the low-pass filter prevents the control unit, especially a controller within the control unit, from reacting to high-frequency or short-term fluctuations in the stack voltage measurement signal. This advantageously avoids oscillations in the control system. Specifically, the measuring device / measuring instrument includes the tunable low-pass filter.

[0026] Additionally, it is conceivable that before comparing the determined actual temperatures with the corresponding target temperatures, a smoothing of each R.413536 is performed.

[0027] - 7 -

[0028] The actual temperature value is filtered through a tunable low-pass filter, in particular through the tunable low-pass filter or through a further tunable low-pass filter. This advantageously improves temperature control. It also advantageously filters out readout errors from the characteristic curves or fluctuations of the input signal for calibration, which could lead to an incorrect output of the actual temperature. In particular, the low-pass filter prevents the control unit, especially a controller of the control unit, from reacting to such incorrect determinations of the actual temperature. This advantageously avoids oscillations in the control system. In particular, the control unit includes the tunable low-pass filter provided for this purpose, in particular a further tunable low-pass filter.

[0029] Preferably, a target temperature value is smoothed before being transferred to the control unit by means of a tunable low-pass filter, in particular by the tunable low-pass filter or by a further tunable low-pass filter. This advantageously allows a high level of control accuracy to be achieved.

[0030] Furthermore, it is proposed that the target temperature(s) of the characteristic temperature-voltage curve(s) correspond to a thermoneutral voltage of a hotbox of the electrolysis plant encompassing the electrolysis cell stack. This allows for particularly precise temperature control. Specifically, the thermoneutral voltage of the hotbox containing the electrolysis cell stack differs from, and is preferably slightly higher than, the thermoneutral voltage of the electrolysis cell stack itself. This is because heat losses of the hotbox must also be compensated. For example, the thermoneutral voltage of the hotbox could deviate from the thermoneutral voltage of the electrolysis cell stack by between 10% and 30%. The hotbox is, in particular, an entire area of ​​the (high-temperature) electrolysis plant encompassing the electrolysis cell stack and other components, which is heated to high temperatures to support the electrolysis process.413536.

[0031] - 8 -

[0032] Alternatively, it is proposed that the target temperature(s) of the characteristic temperature-voltage curve(s) correspond to a voltage that differs from the thermoneutral voltage of a hotbox containing the electrolysis cell stack of an electrolysis plant. This allows for the advantageous setting of any desired operating points for the electrolysis plant.

[0033] Furthermore, it is proposed that the characteristic temperature-voltage curves are each generated by a load profile table (LUT). This advantageously allows for high speed of temperature control. In addition, the required computational load, and thus energy consumption and / or costs, can be kept low. Moreover, a particularly simple implementation of the temperature-voltage curves can be advantageously achieved. Furthermore, high flexibility can be advantageously attained, especially since LUTs are easily adaptable and / or replaceable.

[0034] If, particularly during control, the target temperatures are filtered from the characteristic temperature-voltage curves, especially from a combination of these curves, advantageous temperature control can be achieved. This operating state corresponds to an active control state with an active automatic controller. In this operating state, the temperature is always controlled to a value determined by the input characteristic temperature-voltage curves.

[0035] If, in another operating state, the target temperatures are read from preset standard values, a switching option between an active and a deactivated controller can be advantageously provided. In this other operating state, the controller always operates according to the preset standard value. Specifically, the control unit includes a means, e.g., a physical switch or a software setting, to switch back and forth between the operating state and the other operating state. R.413536

[0036] - 9 -

[0037] Furthermore, the control unit is proposed, comprising the processor and the data memory, which includes at least the operating program with program instructions for executing the temperature management procedure, in particular the temperature control procedure, as well as an electrolyzer or the (high-temperature) electrolysis plant with at least one of the electrolysis cell stacks and the control unit. This enables advantageous, in particular highly efficient, durable, and / or reliable operation of the electrolyzer and / or the electrolysis plant.

[0038] The inventive method, the inventive control unit, and the inventive electrolyzer are not to be limited to the application and embodiment described above. In particular, the inventive method, the inventive control unit, and the inventive electrolyzer may, to achieve a functionality described herein, comprise a different number of individual elements, components, units, and process steps than that specified herein. Furthermore, values ​​within the specified limits of the value ranges stated in this disclosure are also to be considered disclosed and freely usable.

[0039] drawing

[0040] Further advantages will become apparent from the following description of the drawing. The drawing illustrates an embodiment of the invention. The drawing, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0041] They show:

[0042] Fig. 1 shows a schematic representation of an electrolysis plant with an electrolysis cell stack, an external R.413536

[0043] - 10 -

[0044] Temperature control device and a control and / or regulation unit for the implementation of a temperature management procedure,

[0045] Fig. 2 shows a schematic control block diagram of the temperature management procedure for the electrolysis cell stack.

[0046] Fig. 3 shows a schematic flowchart of the temperature management procedure for the electrolysis cell stack.

[0047] Fig. 4a characteristic temperature-voltage curves of inlet temperatures of the electrolysis cell stack,

[0048] Fig. 4b characteristic temperature-voltage curves of outlet temperatures of the electrolysis cell stack and

[0049] Fig. 4c shows a summary of the characteristic temperature-voltage curves of the electrolysis cell stack.

[0050] Description of the exemplary embodiment

[0051] Figure 1 schematically shows an electrolysis plant 60 with an electrolysis cell stack 10. For the sake of simplicity, other balance-of-plant (BOP) components of the electrolysis plant 60, such as pumps, heat exchangers, compressors, tanks, and other measurement and / or control equipment, etc., are not shown in the figures and are only indicated by three dots. The electrolysis cell stack 10 is shown as an example of a solid oxide electrolysis cell (SOEC) stack, but could alternatively be a protonic ceramic electrochemical electrolysis cell (PCEC) stack. The electrolysis cell stack 10 comprises a plurality of electrolysis cells 42, 44. The electrolysis plant 60 could include several additional electrolysis cell stacks, as also indicated by the three dots in Figure 1. The electrolysis plant 60 includes a control unit 62.The control and / or regulation unit 62 can be assigned to only one electrolysis cell stack 10 and its peripherals, or it can be configured as a higher-level control and / or regulation unit 62 for at least a large proportion of all components, in particular at least all electrolysis cell stacks 10, of the electrolysis plant 60. The control and / or regulation unit 62 comprises a processor 64 and a data memory 66, which R.413536.

[0052] - 11 - at least one operating program with program instructions for the execution of a temperature management procedure includes

[0053] The electrolysis system 60 comprises a hotbox 58. The hotbox 58 comprises the electrolysis cell stack 10. The hotbox 58 includes a measuring device 68 for measuring a stack voltage. The measuring device 68 is a voltage measuring device. The measuring device 68 includes a tunable low-pass filter 48 for smoothing the measured values. The electrolysis system 60 comprises an external temperature control unit 12. The temperature control unit 12 comprises a heating unit 28, which is at least associated with the electrolysis cell stack 10. The heating unit 28 is designed to supply heat to the hotbox 58 and, in particular, to its electrolysis cell stack 10. The temperature control unit 12 comprises a cooling unit 30, which is at least associated with the electrolysis cell stack 10. The cooling unit 30 is designed to dissipate heat from the hotbox 58 and, in particular, from its electrolysis cell stack 10.

[0054] Figure 2 shows a schematic control block diagram of the temperature management procedure for the electrolysis cell stack 10. Figure 3 shows a schematic flow diagram of the temperature management procedure for the electrolysis cell stack 10. The temperature management procedure is a temperature control procedure. The temperature management procedure aims to operate the electrolysis cell stack 10, in particular the hotbox 58, at an optimal, preferably at least substantially constant, temperature.

[0055] In at least one process step 100, the instantaneous stack voltage is measured using the measuring device 68. A stack voltage measurement value 20 is determined and recorded. In at least one further process step 110, the determined stack voltage measurement value 20 is processed, in particular by the control unit 62, to determine a cell voltage measurement value 46 of an individual electrolysis cell 42, 44 of the electrolysis cell stack 10. The processing of the stack voltage measurement value 20 comprises dividing the measured stack voltage by the number 40 of electrolysis cells 42, 44 in the electrolysis cell stack 10. This division yields a cell voltage measurement value 46, which is determined via one of the R.413536

[0056] - 12 -

[0057] The electrolysis cells 42, 44 indicate the voltage drop. The processing of the stack voltage measurement 20 also includes smoothing the stack voltage measurement 20 using the tunable low-pass filter 48 of the measuring device 68. Alternatively, the cell voltage measurement 46, determined from the stack voltage measurement 20 by division, could also be smoothed using the tunable low-pass filter 48.

[0058] In at least one further process step 120, the processed stack voltage measurement value 20, i.e. the cell voltage measurement value 46, is applied, in particular by means of the control and / or regulation unit 62, to three characteristic temperature-voltage curves 14, 16, 18 (see Figures 4a to 4c). This application serves to compare the processed stack voltage measurement 20 with the voltage values ​​of the characteristic temperature-voltage curves 14, 16, 18, each corresponding to a target temperature 22, 22', 24, 24', 26, 26'. The three characteristic temperature-voltage curves 14, 16, 18 characterize the hotbox 58, in particular the electrolysis cell stack 10. In principle, the use of more or fewer than three, e.g., two or four, characteristic temperature-voltage curves 14, 16, 18 is also conceivable. A first characteristic temperature-voltage curve 14 comprises (see Fig.4a) The characteristic temperature-voltage curves 14, 16, 18 of the hotbox 58 / electrolysis cell stack 10 include a plot of a characteristic inlet temperature 32 of a cathode and / or a cathode compartment of the electrolysis cell stack 10, in particular one of the electrolysis cells 42, 44 of the electrolysis cell stack 10 (designated tFuelStkln in Fig. 4a) against a cell voltage 34 of the electrolysis cell stack 10, in particular one of the electrolysis cells 42, 44 of the electrolysis cell stack 10. A second characteristic temperature-voltage curve 16 (see Fig. 4a) of the characteristic temperature-voltage curves 14, 16, 18 of the hotbox 58 / electrolysis cell stack comprises 10 a plot of a characteristic inlet temperature 36 of an anode and / or an anode compartment of the electrolysis cell stack 10, in particular one of the electrolysis cells 42, 44 of the electrolysis cell stack 10, (in the Fig.4a (designated tAirStkln) against the cell voltage 34 of the electrolysis cell stack 10, in particular one of the electrolysis cells 42, 44 of the electrolysis cell stack 10. In addition, a further (third and / or fourth) characteristic temperature-voltage curve 18 (see Fig. 4b) R.413536.

[0059] - 13 - of the characteristic temperature-voltage curves 14, 16, 18, a plot of a characteristic outlet temperature 74 of the cathode and / or the cathode compartment (called tFuelStkOut in Fig. 4b) or a characteristic outlet temperature 76 of the anode and / or the anode compartment (called tAirStkOut in Fig. 4b) against the cell voltage 34 of the electrolysis cell stack 10, in particular of the individual electrolysis cells 42, 44 of the electrolysis cell stack 10. Alternatively, a value different from the parameters mentioned could also be used, which is indicative of the characteristic outlet temperature 76 of the anode and / or the anode compartment or of the characteristic outlet temperature 74 of the cathode and / or the cathode compartment, preferably to the characteristic The outlet temperature 76 of the anode and / or the anode space is proportional to the characteristic outlet temperature 74 of the cathode and / or the cathode space.The characteristic temperature-voltage curves 14, 16, 18 are each formed by conversion tables (LUTs) which are stored in the data memory of the control and / or regulation unit 62.

[0060] In at least one further process step 130, an actual temperature can optionally be determined from each of the characteristic temperature-voltage curves 14, 16, 18 by means of the control and / or regulation unit 62 via the application of the processed stack voltage measurements 20, i.e., the cell voltage measurements 46. For this purpose, the most similar value for the cell voltage measurement 46 is sought in the respective conversion tables, and the corresponding value for the respective inlet or outlet temperature is determined. The actual temperatures determined in this way and / or the setpoint temperature values ​​22, 22', 24, 24', 26, 26' transmitted to the control and / or regulating unit 62 for controlling the external temperature control device 12 are also subjected in process step 130 to smoothing by one or more tunable low-pass filters 50, 52, 54 of the control and / or regulating unit 62.In at least one further process step 140, the actual temperatures determined in the preceding process step 130 can optionally be compared with the corresponding target temperatures 22, 22', 24, 24', 26, 26' using the control and / or regulation unit 62. The target temperatures 22, 22', 24, 24', 26, 26' of the characteristic temperature-voltage curves 14, 16, 18 each correspond to a thermoneutral voltage 56 of the electrolysis cell stack 10 R.413536.

[0061] - 14 - comprehensive hotbox 58. The thermoneutral voltage 56 of the hotbox 58 differs from a thermoneutral voltage 38 of the electrolysis cell stack 10 (see, among others, Fig. 4c). Alternatively, however, particularly when a non-thermoneutral operating point is to be set, it is also conceivable that the target temperatures 22, 22', 24, 24', 26, 26' of the characteristic temperature-voltage curves 14, 16, 18 correspond to a voltage that differs from the thermoneutral voltage 56 of the hotbox 58. Depending on the setting of the control and / or regulating unit 62, the applied target temperatures 22, 22', 24, 24', 26, 26' can be different, in particular of different origin. In the control block diagram, a Boolean variable is listed under the abbreviation bActi-ConStkHeatMan, which is intended to indicate a switching option between two predefined possibilities for setpoint temperatures 22, 22', 24, 24', 26, 26' (see also the switches in Fig.2) The target temperatures 22, 24, 26 are either filtered out from the characteristic temperature-voltage curves 14, 16, 18, in particular from a combination of the characteristic temperature-voltage curves 14, 16, 18 (active controller, see the intersection point of the curves in Fig. 4b) or read from preset standard values ​​(passive controller). In Figure 2, the target temperatures 22, 24, 26 filtered out from the characteristic temperature-voltage curves 14, 16, 18 are labeled with the abbreviations tAirStklnSp, tAirStkOutSp and tFuelStklnSp. Figure 2 shows the preset standard values ​​for the target temperatures 22', 24', 26', labeled with the abbreviations tAirStklnSpDefault, tAirStkOutSpDefault and tFuelStklnSpDefault.

[0062] In at least one further process step 150, depending on the result of the adjustment, the temperature control device 12 is controlled and / or regulated by means of the control and / or regulation unit 62. If at least one of the characteristic temperature-voltage curves 14, 16, 18 indicates, based on the processed stack voltage measurement 20, that an actual temperature, preferably more than one or all of the determined actual temperatures, is / are below the corresponding setpoint temperature 22, 22', 24, 24', 26, 26', the heating unit 28 of the external temperature control device 12 is controlled and / or regulated, in particular to increase a heating power (and the cooling unit 30 is deactivated). If at least one of the characteristic temperature-voltage curves, based on the processed stack voltage measurement R.413536

[0063] - 15 - indicates that the actual temperature, preferably more than one or all of the determined actual temperatures, is / are above the corresponding setpoint temperature 22, 22', 24, 24', 26, 26', the cooling unit 30 of the external temperature control device 12 is controlled and / or regulated, in particular activated (and the heating unit 28 is deactivated). Alternatively, the at least one heating unit 28 of the external temperature control device 12 is controlled and / or regulated to reduce the heating output, i.e., the heating output is reduced.If at least one or all of the characteristic temperature-voltage curves 14, 16, 18 indicate, based on the processed stack voltage measurement 20, that the actual temperature, preferably more than one or all actual temperatures, is at or near the corresponding setpoint temperature 22, 22', 24, 24', 26, 26', the external temperature control device 12, i.e., preferably the cooling unit 30 and the heating unit 28, is deactivated. The near range of the target temperature 22, 22', 24, 24', 26, 26' may, for example, include a deviation in a single-digit degree value or of less than 20 K from the exact value of the respective target temperature 22, 22', 24, 24', 26, 26'.

[0064] Figure 4c shows an overview of the characteristic temperature-voltage curves 14, 16, 18. The outlet and inlet curves intersect at the thermoneutral voltage 56 of the hotbox 58. In an operating range 70 to the left of the thermoneutral voltage 56 of the hotbox 58, the electrolysis system 60 is in an endothermic operating state. The electrolysis system 60 is also in an endothermic operating state at the thermoneutral voltage 38 of the electrolysis cell stack 10 due to the influence of other components of the hotbox 58. In an operating range 72 to the right of the thermoneutral voltage 56 of the hotbox 58, the electrolysis system 60 is in an exothermic operating state.

Claims

1. R.413536 - 16 - Claims 1. Temperature management method for an electrolysis cell stack (10), in particular a solid oxide electrolysis cell (SOEC) stack or a protonic ceramic electrochemistry electrolysis cell (PCEC) stack, using an external temperature control device (12), comprising at least the following process steps: - Measuring an instantaneous stack voltage, - Processing a stack voltage measurement (20) of the stack voltage measurement, - Applying the processed stack voltage measurement (20) to more than one characteristic temperature-voltage curve (14, 16, 18) of the electrolysis cell stack (10) to compare the processed stack voltage measurement (20) with the voltage values ​​of the characteristic temperature-voltage curves (14, 16, 18) associated with each target temperature (22, 22', 24, 24', 26, 26'). - Controlling and / or regulating at least one heating unit (28) of the external temperature control device (12) to increase heating power when at least one of the characteristic temperature-voltage curves (14, 16, 18) indicates, based on the processed stack voltage measurement (20), that an actual temperature is below the corresponding setpoint temperature (22, 22', 24, 24', 26, 26'); controlling and / or regulating at least one cooling unit (30) of the external temperature control device (12) or the at least one heating unit (28) of the external temperature control device (12) to decrease heating power when at least one of the characteristic temperature-voltage curves (14, 16, 18) indicates, based on the processed stack voltage measurement (20), that the actual temperature is above the corresponding setpoint temperature (22, 22', 24, 24', 26, 26') and deactivation of the external temperature control device (12) when the characteristic temperature-voltage curves (14, 16,18) indicate, based on the processed stack voltage measurement (20), that the actual temperature is at the target temperature (22, 22', 24, 24', 26, 26') or within a close range, R.413536 - 17 - the target temperature (22, 22', 24, 24', 26, 26') is 2. Temperature management method according to claim 1, characterized in that one of the characteristic temperature-voltage curves (14) comprises a plot of a characteristic inlet temperature (32) of a cathode and / or a cathode space of the electrolysis cell stack (10) against a cell voltage (34) of the electrolysis cell stack (10).

3. Temperature management method according to claim 1 or 2, characterized in that one of the characteristic temperature-voltage curves (16) is a plot of a characteristic inlet temperature (36) of an anode and / or an anode space of the electrolysis cell stack (10) against a cell voltage (34) of the electrolysis cell stack (10) includes.

4. Temperature management method according to one of claims 2 or 3, characterized in that a further of the characteristic temperature-voltage curves (18) comprises a plot of a characteristic outlet temperature (74, 76) of the cathode or the anode or of a parameter proportional to one of these values ​​against the cell voltage (34) of the electrolysis cell stack (10).

5. Temperature management method according to one of the preceding claims, characterized in that the processing of the stack voltage measurement value (20) comprises dividing the measured stack voltage by a number (40) of electrolysis cells (42, 44) in the electrolysis cell stack (10).

6. Temperature management method according to one of the preceding claims, characterized in that the processing of the stack voltage measurement value (20) comprises smoothing the stack voltage measurement value (20) or a cell voltage measurement value (46) determined therefrom by means of a tunable low-pass filter (48). R.413536 - 18 - 7. Temperature management method according to one of the preceding claims, characterized in that the target temperature(s) (22, 22', 24, 24', 26, 26') correspond to the characteristic temperature-voltage curve(s) (14, 16, 18) of a thermoneutral voltage (56) of a hotbox (58) comprising the electrolysis cell stack (10) of an electrolysis plant (60).

8. Temperature management method according to one of the preceding claims, characterized in that the target temperature(s) (22, 22', 24, 24', 26, 26') of the characteristic temperature-voltage curve(s) (14, 16, 18) correspond to a voltage which differs from a thermoneutral voltage (56) of a hotbox (58) comprising the electrolysis cell stack (10) of an electrolysis plant (60).

9. Temperature management method according to one of the preceding claims, characterized in that the characteristic temperature-stress curves (14, 16, 18) are each formed by a conversion table (LUT).

10. Temperature management method according to one of the preceding claims, characterized in that the target temperatures (22, 24, 26) are filtered out from the characteristic temperature-voltage curves (14, 16, 18), in particular from a combination of the characteristic temperature-voltage curves (14, 16, 18).

11. Temperature management method according to one of the preceding claims, characterized in that the target temperatures (22', 24', 26') are read from preset standard values.

12. Control and / or regulation unit (62) comprising at least one processor and at least one data storage device comprising at least one operating program with program instructions for the execution of a temperature management method according to one of the preceding claims. R.413536 - 19 - 13. Electrolysis system (60) with at least one electrolysis cell stack (10), in particular solid oxide electrolysis cell (SOEC) stack or protonic ceramic electrochemistry electrolysis cell (PCEC) stack, and with at least one control and / or regulation unit (62) according to claim 12.

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