Method for controlling the operation of an electrochemical system, electrochemical system and computer program product

Abstract

The invention relates to a method (10) for controlling the operation of an electrochemical system (12) comprising at least one reactant supply line (14) and at least one non-return valve (16) located in the reactant supply line (14). It is proposed that, in at least one method step and during normal operation of the electrochemical system (12), the non-return valve (16) is actuated in order to obtain and / or test a functional capability of the non-return valve (16).

Description

[0001] Description

[0002] Methods for operational control of an electrochemical electrochemical system and

[0003] State of the art

[0004] A method for operational control of an electrochemical system with at least one reactant supply line and with at least one shut-off valve arranged in the reactant supply line has already been proposed.

[0005] Disclosure of the invention

[0006] The invention relates to a method for operational control of an electrochemical system with at least one reactant supply line and with at least one shut-off valve arranged in the reactant supply line.

[0007] It is proposed that in at least one process step of the process, during regular operation of the electrochemical system, the shut-off valve be actuated to maintain and / or test its functionality. The electrochemical system preferably comprises at least one electrochemical unit with at least one electrochemical cell for the electrochemical reaction of at least one reactant. The at least one electrochemical cell is preferably configured as a fuel cell, in particular a solid oxide fuel cell, a polymer electrolyte fuel cell, or the like, or as an electrolysis cell, in particular a solid oxide electrolysis cell, a polymer electrolyte electrolysis cell, or the like. Preferably, the at least one electrochemical cell unit comprises several, in particular at least 100, more preferably at least 200, electrochemical cells.The reactant supply line is preferably connected to the at least one electrochemical unit to supply the at least one electrochemical cell with the reactant. If the electrochemical system comprises several electrochemical units, these are preferably connected in parallel to the reactant supply line via a fluid connection. The reactant supply line can, for example, be used to transport a fuel, in particular a hydrogen-containing, methane-containing, and / or ammonia-containing fuel, and / or an electrolysis reactant, such as water and / or carbon dioxide.

[0008] The shut-off valve is preferably designed to close off the reactant supply line when the electrochemical system is not in operation or in the event of a malfunction, and in particular to seal it tightly with respect to the reactant. A control unit of the electrochemical system closes the shut-off valve, for example, when the electrochemical system is shut down, especially in the event of an emergency shutdown. The shut-off valve is considered to be functioning correctly only if it closes within a predetermined maximum permissible time period after being activated by the control unit. A "control unit" is understood to be, in particular, a unit with at least one control electronics unit. "Control electronics" is understood to be, in particular, a unit with a processor unit, a memory unit, and an operating program stored in the memory unit.The control unit preferably opens the shut-off valve when the electrochemical system is started up. During normal operation, the at least one electrochemical unit electrochemically reacts the reactant. During normal operation, the shut-off valve is held virtually continuously open, in particular fully open, to allow the reactant to flow through the reactant supply line. "Virtually continuously" is understood to mean, in particular, for an accumulated period of time that corresponds to at least 90%, preferably at least 95%, and most preferably at least 99% of the total operating time of the normal state plus the start-up time of the electrochemical unit.

[0009] The electrochemical system preferably comprises a metering element arranged at a distance from the shut-off valve to adjust the flow rate of the reactant. The metering element can be designed, for example, as a proportional valve or as a fluid delivery unit, particularly as a blower or compressor. The shut-off valve can be arranged upstream or downstream of the metering element. The control unit of the electrochemical system preferably controls the metering valve during normal operation to regulate a target operating parameter of the electrochemical system. This target operating parameter is, for example, a reactant utilization rate, an efficiency, an electrical power output, a product delivery rate, or the like.

[0010] Preferably, the control unit attempts to close the shut-off valve, either completely or partially, during regular operation in a maintenance step of the process, and then reopen it. Preferably, the control unit maintains regular operation, particularly unchanged, during the maintenance step. The control unit preferably performs the maintenance step regularly, at random intervals, or on demand, particularly several times a month, preferably several times a week, and especially daily. The maintenance step is specifically designed to counteract the shut-off valve becoming stuck in a position due to lack of actuation. Preferably, the control unit queries a test element of the electrochemical system for confirmation of the shut-off valve actuation in at least one, and preferably several, confirmation steps.Alternatively, to maintain the functionality of the shut-off valve, the control or regulating unit only performs the maintenance step and leaves the confirmation step to, for example, a maintenance service.

[0011] The term "intended" should be understood to mean specifically programmed, designed, and / or equipped. The fact that an object is intended for a specific function should be understood to mean, in particular, that the object fulfills and / or executes this specific function in at least one application and / or operating state.

[0012] The design according to the invention advantageously minimizes the risk or extent of wear resulting from the shut-off valve not being actuated. In particular, the electrochemical system can advantageously operate for extended periods without external maintenance. Furthermore, the electrochemical system can advantageously operate safely for extended periods. Finally, the risk and / or extent of damage to the electrochemical system and / or leakage of the reactant due to malfunction of the shut-off valve can be advantageously minimized.

[0013] It is further proposed that in at least one process step, at least one operating parameter of the electrochemical system is acquired to evaluate the functionality of the shut-off valve. The operating parameter is preferably queried by the test element. The test element is preferably a sensor element of the electrochemical system. The test element is particularly preferably a sensor element of the electrochemical system used for controlling the target operating parameter. Alternatively, the test element is a sensor element specifically designed for monitoring the shut-off valve. In the confirmation step, the control unit preferably infers that the shut-off valve has been actuated if a change in the operating parameter is detected. The operating parameter is particularly preferably a fluid parameter of the reactant.The test element is, for example, a flow sensor, in particular a mass flow meter, which can be arranged downstream or upstream of the shut-off valve. The test element is, for example, a pressure sensor, which is preferably arranged downstream of the shut-off valve. The test element is, for example, a temperature sensor, which is preferably arranged downstream of the shut-off valve. The test element is, for example, an electrical ammeter, voltmeter, and / or power meter, which is connected to the at least one electrochemical unit. In a particularly safe embodiment, the control unit performs at least one confirmation step using at least two test elements. Particularly preferably, the control unit uses multiple test elements, at least two test elements, which detect different physical quantities as operating parameters.When multiple confirmation steps are performed, the control unit preferably concludes that the shut-off valve has been actuated only if each individual confirmation step indicates that the shut-off valve has been actuated. The design according to the invention allows for the advantageous early detection of a malfunction of the shut-off valve. Furthermore, it is proposed that a flow parameter of a fluid located in the feedstock supply line be detected in at least one process step. Preferably, the test element detects a flow rate, in particular a mass flow rate and / or a volume flow rate, of the feedstock in order to confirm actuation of the shut-off element.Preferably, at the beginning of the maintenance step, the control unit stores a start value of the operating parameter, in particular the flow rate, and compares this with an actuation value of the operating parameter, in particular the flow rate, during the maintenance step. Preferably, the control unit concludes that actuation of the shut-off valve was successful if the actuation value is smaller than the start value, in particular by more than a tolerance value. Preferably, the control unit concludes that the shut-off valve was not actuated if the actuation value does not differ from the start value, in particular by less than the tolerance value. The design according to the invention advantageously allows for reliable and direct confirmation of actuation of the shut-off element.

[0014] It is further proposed that a plausibility check be performed in at least one process step to correlate a change in an operating parameter of the electrochemical system with an actuation of the shut-off valve. Preferably, the control unit stores an initial value of a position parameter of the proportional valve at the start of the maintenance step. The position parameter can be a control value, a target flow rate, an angle, or another parameter that describes or characterizes a position of the proportional valve. Preferably, the control unit stores an actuation value of the position parameter when the actuation value of the operating parameter is detected. Preferably, the control unit evaluates the confirmation step as valid, regardless of the result, if the initial value and the actuation value of the position parameter are equal to within a position tolerance value.Preferably, the control unit evaluates the confirmation step as invalid, regardless of the result, if the initial value and the actuation value of the position parameter differ by more than the position tolerance value. Preferably, the control unit repeats the maintenance step and at least one, and in particular all, confirmation steps if at least one confirmation step has been evaluated as invalid. Alternatively, instead of the plausibility check, the control unit blocks actuation of the proportional valve, at least for the duration of the maintenance step. The design according to the invention advantageously minimizes the risk of false-positive and false-negative results from the confirmation steps.

[0015] It is further proposed that the maximum actuation time of the shut-off valve for checking its functionality be limited depending on the reaction time of the electrochemical system. Preferably, the control unit keeps the maintenance step short enough to maintain regular operation, in particular the control of the operating target parameter. For example, the control is slower than the maintenance step. Preferably, the maintenance step lasts less than one second, more preferably less than 750 ms, and most preferably less than 500 ms. Preferably, the control unit repeats the maintenance step if at least one confirmation step was unsuccessful. When repeating the maintenance step, the control unit preferably increases its duration.If, after a predetermined number of repetitions of the maintenance step, at least one confirmation step is unsuccessful, the control unit preferably switches off the electrochemical system. The design according to the invention advantageously minimizes the extent to which the shut-off valve is actuated during regular operation.

[0016] It is further proposed that, in the event of a negative test result, the functionality of the shut-off valve be retested only after a minimum waiting period dependent on the reaction time of the electrochemical system. For example, the minimum waiting period is at least one minute, preferably at least five minutes, and particularly preferably at least 10 minutes. Preferably, the minimum waiting period is less than one hour, and particularly less than 30 minutes. The design according to the invention advantageously and reliably compensates for any potential disruption of regular operation caused by the maintenance step. In particular, the risk and / or extent of a disruption that increases with each repetition of the maintenance step can be advantageously kept low.It is further proposed that the functionality of the shut-off valve be tested at least several times a week, and in particular at least once a day. Preferably, the maintenance step is repeated regularly, preferably with a period of no more than 24 hours, and in particular less than 24 hours. Alternatively, the maintenance step is performed at at least one fixed time. Additionally or alternatively, a change in operating point from full-load operation of the electrochemical system triggers the maintenance step, in particular by resetting a timer for the next execution of the maintenance step. The design according to the invention allows a defect in the shut-off valve to be detected advantageously at an early stage.

[0017] It is further proposed that the actuation of the shut-off valve be electrically assisted in at least one process step. Preferably, in a release step at the beginning of the maintenance step, the control unit actuates the shut-off valve several times in opposite directions to release any possible jamming of the shut-off valve. The control unit can perform the release step at every maintenance step, less frequently than the maintenance step itself (e.g., once a week or month), or only after at least one unsuccessful confirmation step. In at least one embodiment, the control unit performs an active closing step during the maintenance step to assist in closing the shut-off valve. In this closing step, the control unit preferably activates an electromagnet to reliably achieve the closed position of the shut-off valve.The design according to the invention allows the functionality of the shut-off valve and the reliability of the method to be maintained advantageously for a long time.

[0018] It is further proposed that, in at least one process step, an operating parameter of the shut-off valve is evaluated to determine the maintenance status of the shut-off valve and / or to assess its functionality. In the confirmation step, or an additional confirmation step, the control unit determines the functionality of the shut-off valve based on this operating parameter. For example, the test element for acquiring the valve operating parameter is configured as an electrical ammeter, voltmeter, and / or power meter to determine the electrical energy consumption by the shut-off valve required for the maintenance step and / or the time course of electrical current, voltage, and / or power during the maintenance step.Alternatively, the test element for recording the valve operating parameter is designed as a contact sensor or proximity sensor to detect a closed position and / or a closing process of the check valve. In addition to or as an alternative to using the valve operating parameter in the confirmation step, the control unit evaluates the valve operating parameter to determine the wear condition of the check valve, in particular based on the absorbed electrical energy, a characteristic time profile of the valve operating parameter, the time required to close or open the check valve, or the like. Preferably, the control unit uses the wear condition of the check valve to determine when the check valve needs maintenance, in particular replacement, and communicates this to a maintenance service.The design according to the invention allows the functionality of the shut-off valve to be advantageously determined directly. In particular, the risk that a component other than the shut-off valve causes a change in the parameter examined in the confirmation step can be advantageously minimized.

[0019] Furthermore, an electrochemical system comprising a reactant supply line, a shut-off valve arranged in the reactant supply line, and at least one control or regulating unit, particularly one of those already mentioned, is proposed for an embodiment of a method according to the invention. The electrochemical system preferably has a nominal electrical power of at least 10 kW, and in particular at least 20 kW. The electrochemical system preferably comprises at least one electrochemical unit. The reactant supply line is preferably connected to a fluid inlet of the electrochemical unit.The electrochemical system preferably comprises several peripheral devices along the reactant supply line for the preparation of the at least one reactant, such as at least one heat exchanger, a steam injection system, a water separator, a reformer, an exhaust gas recirculation system for feeding exhaust gas back into the reactant supply equation, or the like. The peripheral devices, and in particular at least the majority of them, are preferably arranged downstream of the shut-off valve and, more specifically, downstream of the proportional valve. The electrochemical system preferably comprises the at least one test element, and in particular, a plurality of test elements. If the at least one test element is provided for detecting a fluid parameter of the reactant, it can be arranged upstream, downstream, or between the peripheral devices.It is also conceivable that the electrochemical cell comprises at least one test element located downstream of the electrochemical cell unit and / or in the exhaust gas recirculation system. The design according to the invention allows for the provision of an advantageously safe and low-maintenance electrochemical system.

[0020] Furthermore, a computer program product comprising commands that cause an electrochemical system according to the invention to execute process steps of a process according to the invention is proposed. The computer program product is preferably designed to be implemented and executed on the control unit of the electrochemical system. Preferably, the computer program product comprises several possible routines for executing the confirmation step. Preferably, the computer program product includes at least one selection step for selecting the test elements to be used by the control unit. The selection step can be a query from an operator and / or include a scan to determine which test elements are available for a confirmation step. Due to the design according to the invention, an existing electrochemical system can advantageously be easily retrofitted by means of a software update.

[0021] The inventive method, the inventive electrochemical system, and / or the computer program product are not / should not be limited to the application and embodiment described above. In particular, the inventive method, the inventive electrochemical system, and / or the computer program product may, to achieve a functionality described herein, comprise a different number of individual elements, components, units, and process steps than the number specified herein. Furthermore, values ​​within the specified limits of the value ranges stated in this disclosure shall also be considered disclosed and freely usable.

[0022] Drawings

[0023] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an embodiment of the invention. The drawings, 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.

[0024] They show:

[0025] Fig. 1 shows a schematic representation of an electrochemical system according to the invention and

[0026] Fig. 2 shows a schematic flowchart of a method according to the invention.

[0027] Description of the exemplary embodiment

[0028] Figure 1 shows an electrochemical system 12. The electrochemical system 12 comprises at least one electrochemical unit 22 with at least one electrochemical cell, for example, at least one solid oxide fuel cell. The electrochemical unit 22 is shown here functionally as a single electrochemical cell. Preferably, the electrochemical unit 22 comprises a plurality, in particular at least 100, of electrochemical cells connected in series. The electrochemical unit 22 is preferably designed for the electrochemical reaction of at least one reactant 24, for example, a fuel such as natural gas, biogas, hydrogen, or the like, with the addition of oxygen. The electrochemical system 12 includes a reactant supply line 14 for supplying the electrochemical unit 22 with the at least one reactant 24.The electrochemical system 12 preferably comprises at least one metering element 26 in the reactant supply line 14 for adjusting the flow rate of the reactant 24 to the electrochemical unit 22. The metering element 26 is here exemplified as a proportional valve. The electrochemical system 12 also comprises at least one shut-off valve 16 arranged in the reactant supply line 14. The shut-off valve 16 is preferably designed to partially, and in particular completely, close or open the reactant supply line 14 in the event of a shutdown and / or malfunction of the electrochemical system 12. The electrochemical system 12 preferably comprises at least one control unit 20 for an embodiment of a method 10, which is explained in more detail in Figure 2. The control unit 20 is preferably designed to actuate at least the shut-off valve 16.Preferably, the electrochemical system 12 comprises at least one sensor element 28, 30 for detecting at least one operating parameter of the electrochemical system 12. For example, the electrochemical system 12 comprises at least one fluid sensor element 28 for detecting a fluid parameter of the reactant 24, in particular a flow rate, a pressure and / or a temperature of the reactant 24. For example, the electrochemical system 12 comprises at least one electrical sensor element 30 for detecting an electric current, an electric voltage and / or an electric power of the electrochemical unit 22.

[0029] Figure 2 shows a flowchart of a method 10 for operational monitoring of the electrochemical system 12. In the method 10, the shut-off valve 16 is actuated during regular operation of the electrochemical system 12 to maintain and / or test its functionality. During regular operation, the electrochemical unit 22 preferably reacts the reactant 24 continuously.

[0030] Method 10 preferably comprises a maintenance step 32 in which the shut-off valve 16 is actuated. Maintenance step 32 preferably includes a closing phase 34 in which the control unit 20 attempts to close the shut-off valve 16. The closing phase 34 may include a release step in which actuation of the shut-off valve 16 is electrically assisted. Preferably, in the release step, the control unit 20 actuates the shut-off valve 16 several times alternately in opposite directions to open and close it in order to release a stuck shut-off valve 16. The closing phase 34 preferably ends with a final actuation to close the shut-off valve 16.

[0031] Maintenance step 32 preferably comprises a waiting phase 36, in which the shut-off valve 16 is held in the assumed closed state. A maximum actuation time of the shut-off valve 16 for checking its functionality is limited depending on the reaction time of the electrochemical system 12. The control unit 20 selects a duration for the waiting phase 36 such that the total duration of maintenance step 32, particularly at least during a first iteration of maintenance step 32, remains less than one second, particularly less than 750 ms, and most preferably less than 500 ms. When maintenance step 32 is repeated, the control unit 20 preferably increases the duration of the waiting phase 36. Maintenance step 32 preferably comprises an opening phase 38, in which the control unit 20 reopens the shut-off valve 16 after the waiting phase 36.

[0032] Method 10 preferably comprises a confirmation phase 40 in which at least one, preferably at least two, and in particular at least three confirmation steps 42, 44, 46 are performed. In the at least one confirmation step 42, 44, 46, the control unit 20 preferably checks whether the shut-off valve 16 has closed or not. The confirmation phase 40 is preferably performed during and / or at the end of the waiting phase 36. In the confirmation phase 40, at least one operating parameter of the electrochemical system 12 and / or a valve operating parameter of the shut-off valve 16 is recorded in order to evaluate the functionality of the shut-off valve 16.Preferably, the control unit 20 uses at least one of the sensor elements 28, 30 of the electrochemical system 12 as a test element in at least one of the confirmation steps 42, 44, 46 to confirm a position of the shut-off valve 16 using the operating parameter of the electrochemical system 12. Preferably, the control unit 20 stores a start value of the operating parameter used at the beginning of the opening phase 38. Preferably, the control unit 20 stores an actuation value of the operating parameter in the at least one confirmation step 42, 44, 46. Preferably, the control unit 20 uses the shut-off valve 16 as a test element in at least one of the confirmation steps 42, 44, 46 to confirm a position of the shut-off valve 16 using the valve operating parameter.For example, the control unit 20 records the duration of the opening phase 38, the time course of an electric current through the shut-off valve 16, and / or the total electrical energy consumption by the shut-off valve 16 during the opening phase 38. Preferably, the control unit 20 uses a different operating parameter and / or valve operating parameter in each confirmation step 42, 44, 46. For example, in one of the confirmation steps 42, the control unit 20 uses the at least one fluid sensor element 28, in another confirmation step 44 another fluid sensor element and / or the electrical sensor element 30, and / or in an additional confirmation step 46 the shut-off valve 16 as a test element.

[0033] Method 10 comprises at least one evaluation step 48. In evaluation step 48, the control unit 20 preferably evaluates a result of at least one confirmation step 42, 44, 46. For example, the control unit 20 compares the actuation value with the initial value of the operating parameter. Preferably, if the actuation value deviates from the initial value, the control unit 20 concludes that the shut-off valve 16 was closed during the waiting phase 36. Preferably, if the actuation value and the initial value match, the control unit 20 concludes that the shut-off valve 16 was not closed during the waiting phase 36. For example, the control unit 20 compares a detected value of the valve parameter with a reference value or reference curve stored in the memory of the control unit 20 prior to method 10.If the detected value matches the reference value of the valve operating parameter, the control unit 20 preferably concludes that the shut-off valve 16 has been actuated correctly. If the detected value deviates from the reference value of the valve operating parameter, the control unit 20 preferably determines the type and / or extent of the deviation in order to infer a wear condition and / or the position of the shut-off valve 16, particularly taking the wear condition into account, during the waiting phase 36. If all confirmation steps 42, 44, 46 indicate that the shut-off valve 16 has closed, the control unit 20 evaluates the functional test as successful. If at least one confirmation step 42, 44, 46 indicates that the shut-off valve 16 has remained open, the control unit 20 evaluates the functional test as unsuccessful.

[0034] Method 10 comprises at least one plausibility check 18 to attribute a change in an operating parameter of the electrochemical system 12 to an actuation of the shut-off valve 16. If the plausibility check 18 is positive, the result of evaluation step 48 is preferably considered valid. If the plausibility check 18 is negative, the result of evaluation step 48 is preferably discarded. If the result of evaluation step 48 is discarded, the control unit 20 preferably repeats maintenance step 32 after a repetition waiting time 50. A further check of the functionality of the shut-off valve 16 is performed after the repetition waiting time 50 if the result of evaluation step 48 and / or the plausibility check 18 is negative. The repetition waiting time 50 is preferably greater than or equal to a minimum waiting time dependent on a reaction time of the electrochemical system 12.

[0035] If a successful result of evaluation step 48 is deemed valid, the control unit 20 evaluates the shut-off valve 16 as functional and, in a reset step 52 of the procedure 10, resets a timer for a further check of the shut-off valve 16. Preferably, the timer is set such that a functional test of the shut-off valve 16 is performed at least several times a week, in particular at least once a day, for example, 22 hours after the last successful test. Preferably, the procedure starts with a first reset step 52, so that the first maintenance step 32 is performed no earlier than after the time period specified in the remaining step 52.

[0036] If an unsuccessful result of evaluation step 48 is deemed valid, the control unit 20 preferably repeats maintenance step 32 after the repetition waiting time 50. Preferably, the control unit 20 counts the number of repeated maintenance steps 32, in particular at least those resulting from an unsuccessful evaluation step 48 result deemed valid. If a predetermined maximum number of repetitions of maintenance step 32 is reached in a repetition test step 54 of the method 10, the control unit 20 preferably performs a safety shutdown 56 of the electrochemical system 12 and preferably informs a maintenance service that the shut-off valve 16 must be serviced before resuming operation.

Claims

Claims 1. Method (10) for operational control of an electrochemical system (12) with at least one reactant supply line (14) and with at least one shut-off valve (16) arranged in the reactant supply line (14), characterized in that in at least one method step during regular operation of the electrochemical system (12) the shut-off valve (16) is actuated in order to maintain and / or test the functionality of the shut-off valve (16).

2. Method (10) according to claim 1 , characterized in that in at least one method step at least one operating parameter of the electrochemical system (12) is recorded in order to evaluate the functionality of the shut-off valve (16).

3. Method (10) according to claim 1 or 2, characterized in that in at least one method step a flow parameter of a fluid located in the reactant supply line (14) is detected.

4. Method (10) according to one of the preceding claims, characterized in that in at least one method step a plausibility check (18) is carried out in order to assign a change in an operating parameter of the electrochemical system (12) to an actuation of the shut-off valve (16).

5. Method (10) according to one of the preceding claims, characterized in that a maximum actuation time of the shut-off valve (16) for checking its functionality is limited depending on a reaction time of the electrochemical system (12).

6. Method (10) according to one of the preceding claims, characterized in that a renewed test of the functionality of the shut-off valve (16) in the event of a negative result of such a test is carried out at the earliest after a minimum waiting time which depends on a reaction time of the electrochemical system (12).

7. Method (10) according to one of the preceding claims, characterized in that a test of the functionality of the shut-off valve (16) is carried out at least several times a week, in particular at least once a day.

8. Method (10) according to one of the preceding claims, characterized in that in at least one method step the actuation of the shut-off valve (16) is electrically assisted.

9. Method (10) according to one of the preceding claims, characterized in that in at least one method step a valve operating parameter of the shut-off valve (16) is evaluated in order to determine a maintenance condition of the shut-off valve (16) and / or to assess the functionality of the shut-off valve (16).

10. Electrochemical system (12) with an educt supply line (14), with a shut-off valve (16) arranged in the educt supply line (14) and with at least one control or regulating unit (20) for an embodiment of a method (10) according to one of the preceding claims.

11. Computer program product comprising instructions that cause the electrochemical system (12) of claim 10 to perform process steps of a method (10) according to any one of claims 1 to 9.

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