Method for diagnosing a tank system

Abstract

The invention relates to a method (100) for diagnosing a tank system (200), the method (100) comprising: - outputting (101) a command to close tank valves (207) of each tank (201) of the tank system (200); - determining (103), after a predefined waiting period, a differential pressure between a first pressure in each tank (201) and a second pressure in a line system (211) of the tank system (200), - comparing (105) the differential pressure with a predefined differential-pressure threshold value, - outputting (107) an error message indicating a severe leakage of the tank system (200) if the differential pressure deviates from the differential-pressure threshold value.

Description

[0001] Description

[0002] title

[0003] Procedure for diagnosing a tank system

[0004] The presented invention relates to a method for diagnosing a tank system, a tank system and an energy converter.

[0005] State of the art

[0006] Known methods for detecting leaks in tank systems for storing hydrogen require that, when a respective tank system is deactivated, the pressure in the high-pressure pipeline system is reduced relative to the pressure in its tanks.

[0007] Such targeted adjustment of different pressure levels between the tank, high-pressure piping system and medium-pressure piping system enables sensor-based determination of mass changes in the tank system over its downtime in different system sections (tank, high-pressure piping system and medium-pressure piping system) and thus a diagnosis of different leaks in the tank system.

[0008] One problem with these known methods of so-called parking pressure reduction is that targeted pressure reduction in the high-pressure pipeline system requires a coordinated functional concept between the tank system and the consumer system. This means that after the respective tank valves of the tank system are closed, the consumer system draws a small amount of gas from the high-pressure pipeline system to achieve the desired pressure reduction. This requires communication and coordination of the software functions of the tank system and the consumer system. Such coordination between the tank system and the consumer system is difficult to implement, as the tank system is usually manufactured and distributed independently of the consumer system.

[0009] In particular, hydrogen engines as consumer systems present the problem that they generally require a direct shutdown and a time-limited combustion after-run following a shutdown request is not acceptable.

[0010] Disclosure of the invention

[0011] Within the scope of the presented invention, a method for diagnosing a tank system, a tank system for storing hydrogen, and an energy converter are introduced. Further features and details of the invention will become apparent from the respective dependent claims, the description, and the drawings. Features and details described in connection with the tank system according to the invention naturally also apply in connection with the method and the energy converter according to the invention, and vice versa, so that the disclosure of the individual aspects of the invention is always, or can always be, mutually interdependent.

[0012] The invention presented here serves in particular to provide a means for the safe operation of a tank system.

[0013] Thus, according to a first aspect of the presented invention, a method for diagnosing a tank system is presented.

[0014] The presented method includes issuing a command to close the tank valves of the respective tanks in the tank system, determining a differential pressure between a first pressure in a respective tank and a second pressure in a piping system after a predetermined waiting period, comparing the differential pressure with a predetermined differential pressure threshold, and issuing an error message that reports a leak in the tank system if the differential pressure differs from the differential pressure threshold.

[0015] In the context of the presented invention, deactivating a tank means, for example, closing a tank valve of the respective tank.

[0016] The presented invention is based on the principle that changes in pressure in different parts of a tank system, namely in a specific tank and a piping system, are used to infer the state of the tank system. Accordingly, a reduction in parking pressure by a consumer system coupled to the tank system can be dispensed with, or the presented method can be carried out independently of any consumer system.

[0017] By issuing the command to close the tank valves of the respective tanks of the tank system as provided for in the invention, which occurs, for example, after deactivation of the tank system or a consumer system coupled to the tank system, the respective tanks are normally, i.e., if there is no fault, hydraulically separated from other components of the tank system, in particular the piping system, so that the respective pressures in the tanks and the piping system change independently of each other, since they have different thermal inertia.

[0018] In the event of a fault, e.g., a tank valve stuck open or a defective tank, fluid from at least one tank flows into the piping system despite the command being issued to close the tank valves of the tank system, so that a change in the differential pressure between a first pressure in a respective tank and a second pressure in the piping system behaves differently than under normal circumstances.

[0019] Accordingly, by comparing the differential pressure determined after a waiting period of, for example, 30 minutes with a predefined differential pressure threshold, a conclusion can be drawn about the condition of the tank system and an error message reporting a leak in the tank system can be issued if the differential pressure differs from the differential pressure threshold.

[0020] To output the message, the message can be displayed, for example, on a display unit and / or stored in a memory, in particular an error memory.

[0021] It may also be provided that, in the event that the differential pressure is adjusted against the differential pressure threshold in a condition where a first temperature at at least one point in the tank system is lower than a second temperature in the environment of the tank system, the error message will be issued if the differential pressure is greater than the differential pressure threshold.

[0022] Normally, i.e., with internally sealed tank valves, deactivating the tank system when the temperature of the system's pipes and tanks is lower than ambient temperature leads to a faster heating of the piping system relative to each tank and a faster pressure increase within the piping system relative to each tank. This, in turn, results in a negative differential pressure between the pressure in the individual tanks and the pressure in the piping system. Accordingly, an error message may be issued if this differential pressure exceeds the differential pressure threshold.

[0023] It may further be provided that, in a first case where the differential pressure is adjusted against the differential pressure threshold in a condition where a first temperature at at least one point in the tank system is lower than a second temperature in the environment of the tank system, the error message is then issued if the differential pressure is higher than the differential pressure threshold, or in a second case where the differential pressure is adjusted against the differential pressure threshold in a condition where the first temperature at at least one point in the tank system is higher than the second temperature in the environment of the tank system, the error message is then issued if the differential pressure is lower than the differential pressure threshold.

[0024] Normally, i.e., with internally sealed tank valves, deactivating the tank system when the temperature in the system's pipes and tanks exceeds the ambient temperature leads to faster cooling of the piping system relative to each tank and a faster pressure reduction within the piping system relative to each tank. This, in turn, results in a positive differential pressure between the pressure in the respective tanks and the pressure in the piping system. Accordingly, an error message may be issued if this differential pressure falls below the differential pressure threshold.

[0025] It may also be provided that the differential pressure threshold for the first case differs from the differential pressure threshold for the second case.

[0026] Different differential pressure thresholds can be used to define different states for issuing error messages.

[0027] It may also be provided that at least one location of the tank system comprises a location in a pipe and / or a location in a tank of the tank system.

[0028] A temperature sensor can be used or provided to measure the temperature at at least one point.

[0029] It may also be provided that, in order to determine whether the adjustment of the differential pressure with the differential pressure threshold is carried out in a condition in which a first temperature at at least one point in the tank system is smaller or larger than a second temperature in the environment of the tank system, a differential temperature between the first temperature and the second temperature is determined and adjusted with a temperature threshold.

[0030] By comparing a temperature difference with a temperature threshold, a minimum temperature difference can be specified that is required to carry out the presented procedure, making the procedure particularly valid.

[0031] It can also be specified that the temperature threshold is selected depending on the pressure present in the respective tank.

[0032] By selecting a temperature threshold value depending on the pressure present in the respective tank, a minimum temperature difference required for the execution of the presented process is dynamically adapted to the respective pressure conditions in the tank system, so that, for example, a high temperature threshold value can be selected at low pressure and a low temperature threshold value at high pressure.

[0033] It may also be provided that the second pressure in the piping system is determined at an inlet to a high-pressure regulator and / or a medium-pressure regulator of the tank system and / or at a connecting element for the piping system.

[0034] By using pressures upstream of the pressure regulator in the high-pressure line system and downstream of the pressure regulator in the medium-pressure line system in combination, the presented method becomes particularly robust against disturbances and correspondingly valid. For this purpose, the differential pressure threshold can, for example, include a specific high differential pressure threshold and a specific medium differential pressure threshold.

[0035] Alternatively, the pressures upstream of the pressure regulator in the high-pressure line system and downstream of the pressure regulator in the medium-pressure line system can be combined into a single characteristic value. This can be achieved by mathematically combining a pressure in the high-pressure line system with a pressure in the medium-pressure line system, for example, by multiplying them using weighting factors.

[0036] It may also be provided that, in the event that the differential pressure is greater than a differential pressure threshold, at a predetermined time after the tank valves have closed, a change in mass in the piping system of the tank system within a predetermined period is compared with a mass change threshold, and in the event that the change in mass in the piping system is greater or less than the mass change threshold, an error message is issued reporting a leak in the tank system.

[0037] Even subtle or minor changes in the condition of the tank system can be detected by measuring changes in the mass of the gas in the high-pressure pipeline system and / or the mass of the gas in the medium-pressure pipeline system. Accordingly, detecting such a change allows for the identification of even a slight leak, which, for example, cannot be reliably detected by pressure changes alone.

[0038] The change in mass can occur in both directions, i.e. as an increase in mass due to a leaking tank valve or as a decrease in mass due to external leakage in the piping system.

[0039] It may also be provided that the mass change threshold includes a course of several values ​​over time.

[0040] Since a minor leak only becomes noticeable over a longer period, the mass change profile can be evaluated and compared with a corresponding mass change threshold value, so that different values ​​can be used as the mass change threshold at different times, e.g., in a characteristic curve. According to a second aspect, the presented invention relates to a tank system for storing hydrogen.

[0041] The presented tank system comprises a number of tanks, each containing a temperature sensor for measuring the temperature in the respective tank and a device for determining the pressure in the respective tank, such as a computing unit for executing a mathematical model or a pressure sensor, a number of tank valves for controlling a mass flow from the respective tanks, a piping system with a pressure sensor and a computing unit, wherein the computing unit is configured to carry out a possible embodiment of the presented method.

[0042] The presented method is particularly useful for diagnosing a faulty condition of the presented tank system, especially a leak.

[0043] According to a third aspect, the presented invention relates to an energy converter for converting energy.

[0044] The presented energy converter comprises an energy unit and a possible configuration of the presented tank system, wherein the energy unit is a fuel cell system or a hydrogen engine.

[0045] Based on the presented method, a diagnosis of the tank system of the presented energy converter can be carried out independently of its energy unit, so that a follow-up run of the energy unit after the provision of a command to deactivate the energy unit can be dispensed with.

[0046] Advantages described in detail with respect to the method for diagnosing the condition of a tank system according to the first aspect of the invention apply equally to the tank system according to the second aspect of the invention and to the energy converter according to the third aspect of the invention, and vice versa. Further advantages, features, and details of the invention will become apparent 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 be essential to the invention individually or in any combination.

[0047] Drawings

[0048] They each show schematically:

[0049] Figure 1 shows a possible embodiment of the presented method,

[0050] Figure 2 shows a detailed representation of the states of a tank system during the process according to Figure 1, and

[0051] Figure 3 shows a possible embodiment of the presented energy converter with a possible embodiment of the presented tank system.

[0052] Description of the exemplary implementations

[0053] Figure 1 shows a method 100 for diagnosing a tank system.

[0054] Method 100 comprises an output step 101, in which a command to close tank valves of respective tanks of the tank system is issued; a determination step 103, in which a differential pressure between a first pressure in a respective tank and a second pressure in at least one piping system of the tank system is determined after a predetermined waiting period; a calibration step 105, in which the differential pressure is calibrated against a predetermined differential pressure threshold; and an output step 107, in which an error message reporting a leak in the tank system is issued if the differential pressure differs from the differential pressure threshold. In Fig.Figure 2 shows three diagrams 110, 120 and 130, each with time depicted on its abscissa. The ordinate of the first diagram 110 shows temperature, the ordinate of the second diagram 120 shows pressure and the ordinate of the third diagram 130 shows density.

[0055] At time to, a command is issued to close the tank valves of a tank system. At time ti, temperature equalization takes place between the respective lines of the tank system and the environment.

[0056] Diagrams 110, 120 and 130 show the progression of values ​​for a first case and a second case, where in the first case the gas temperature in the piping system and in the tank of the tank system is lower than the ambient temperature and in the second case the gas temperature in the piping system and in the tank of the tank system is higher than the ambient temperature.

[0057] Diagram 110 shows a first temperature profile 111 in a piping system of the tank system and a second temperature profile 113 in a tank of the tank system for the first case.

[0058] Furthermore, diagram 110 shows a third temperature profile 115 in the piping system of the tank system and a fourth temperature profile 117 in the tank of the tank system for the second case.

[0059] From time to time, the temperature profiles 111, 113, 115 and 117 begin to diverge, with temperature profiles 111, 113 rising and temperature profiles 115, 117 falling.

[0060] Diagram 120 shows a first pressure curve 121 in a pipe system of the tank system and a second pressure curve 123 in a tank of the tank system for the first case.

[0061] Furthermore, Diagram 120 shows a third pressure profile 125 in the piping system of the tank system and a fourth pressure profile 127 in the tank of the tank system for the second case. Diagram 130 shows a first density profile 131 in a piping system of the tank system and a second density profile 133 in a tank of the tank system for the first case.

[0062] Furthermore, diagram 130 shows a third density profile 137 in the piping system of the tank system and a fourth density profile 135 in the tank of the tank system for the second case.

[0063] In the first case, a negative differential pressure between the second pressure curve 123 and the first pressure curve 121 is expected at time ti, provided the system has no leaks. If this negative differential pressure does not occur, or if the differential pressure is greater than a differential pressure threshold, a leak in the tank system can be assumed, and further diagnostic testing is initiated.

[0064] In the second case, a positive differential pressure between the fourth pressure curve 127 and the third pressure curve 125 is expected at time h, provided the system has no leaks. If this positive differential pressure does not occur, or if the differential pressure is less than the differential pressure threshold, a leak in the tank system can be assumed, and further diagnostic testing is initiated.

[0065] Figure 3 shows an energy converter 300 for converting energy.

[0066] The energy converter 300 comprises an energy unit 301, such as a hydrogen engine or a fuel cell system, and a tank system 200.

[0067] The tank system 200 serves to store hydrogen and comprises tanks 201, each of which includes a pressure sensor 203 for measuring the pressure in the respective tank 201 and a temperature sensor 205 for measuring the temperature in the respective tanks 201. Furthermore, the tank system 200 comprises a number of tank valves 207 for controlling a mass flow from the tanks 201, a pressure regulator 209 in a piping system with a pressure sensor 211, and a computing unit 213, wherein the computing unit 213 is configured to perform the method 100 according to Fig. 1.

Claims

Claims 1. Method (100) for diagnosing a tank system (200), the procedure (100) comprises: - Issuing (101) a command to close tank valves (207) of respective tanks (201) of the tank system (200), - Determining (103) a differential pressure between a first pressure in a respective tank (201) and a second pressure in a piping system (211) of the tank system (200), after a specified waiting period, - Adjusting (105) the differential pressure with a predetermined differential pressure threshold value, - Output (107) an error message reporting a leak in the tank system (200) if the differential pressure differs from the differential pressure threshold.

2. Method (100) according to claim 1 , characterized by that for a first case, where the adjustment (105) of the differential pressure with the differential pressure threshold is carried out in a condition where a first temperature at at least one point of the tank system (200) is lower than a second temperature in the environment of the tank system (200), the error message is then issued if the differential pressure is greater than the differential pressure threshold, or For a second case, where the adjustment (105) of the differential pressure with the differential pressure threshold is carried out in a condition where the first temperature at at least one point in the tank system (200) is greater than the second temperature in the environment of the tank system (200), the error message is then issued when the differential pressure is less than the differential pressure threshold.

3. Method (100) according to claim 2, characterized by that the differential pressure threshold for the first case differs from the differential pressure threshold for the second case 4. Method (100) according to claim 2 or 3, characterized by that the at least one location of the tank system (200) includes a location in a line (211) and / or a location in a tank (201) of the tank system (200).

5. Method (100) according to any one of claims 2 to 4, characterized by To determine whether the adjustment (105) of the differential pressure is carried out with a differential pressure threshold in a condition in which a first temperature at at least one point of the tank system (200) is smaller or larger than a second temperature in the environment of the tank system (200), a differential temperature between the first temperature and the second temperature is determined and adjusted with a temperature threshold.

6. Method (100) according to claim 5, characterized by that the temperature threshold is selected depending on the pressure present in the respective tank (201).

7. Method (100) according to any one of the preceding claims, characterized by that the second pressure in the piping system (211) is determined at an inlet to a high-pressure regulator and / or a medium-pressure regulator (209) of the tank system (200) and / or at a connecting element for the piping system (211).

8. Method (100) according to any one of the preceding claims, characterized by that in the event that the differential pressure is greater than a differential pressure threshold value, at a predetermined time after the When the tank valves (207) are closed, a change in mass in the piping system (211) of the tank system (200) within a specified period is compared with a mass change threshold value, and if the change in mass in the piping system (211) is greater or less than the mass change threshold value, an error message is issued, reporting a leak in the tank system (200).

9. Method (100) according to claim 8, characterized by that the mass change threshold encompasses a course of several values ​​over time 10. Tank system (200) for storing hydrogen, the tank system (200) includes: - a number of tanks (201), each comprising a temperature sensor (205) for measuring a temperature present in the respective tanks (201) and a device for determining a pressure present in the respective tank (201), - a number of tank valves (207) for controlling a mass flow from the respective tanks (201), - a piping system (211) with a pressure sensor, - a computing unit (213), wherein the computing unit (213) is configured to perform a method (100) according to any one of claims 1 to 9.

11. Energy converter (300) for converting energy, the energy converter (300) comprises: - one energy unit (301) and - a tank system (200) according to claim 10, where the energy unit (301) is a fuel cell system or a hydrogen engine.

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