Tank system and method for operating a tank system

Abstract

The invention relates to a method (100) for operating a tank system (200) comprising a plurality of tanks (201). The method (100) has the steps of: - determining (101) expected individual pressures for each tank (201) of the tank system (200) for a current operating cycle on the basis of the respective individual fill level last stored in the respective tank (201) in the operating cycle preceding the current operating cycle and a first temperature in the respective tank (201), - determining (103) the individual fill level of each tank (201) of the tank system (200) on the basis of the determined respective expected individual pressure, the first temperature, and a second temperature in the respective tank (201), and - determining (105) the total fill level of the tank system (200) by adding the determined individual fill levels, the individual fill level of each tank being weighted according to the tank volume thereof and the first temperature being measured chronologically prior to the second temperature.

Description

[0001] Description

[0002] title

[0003] Tank system and method for operating a tank system

[0004] The presented invention relates to a method for operating a tank system, a tank system for storing a fluid and an energy converter according to the attached claims.

[0005] State of the art

[0006] Tank systems with multiple tanks typically use only one pressure sensor in an area connected to all tanks to determine the pressure and, consequently, the fill level of the overall system.

[0007] Due to differing thermal influences when a tank system is shut down, situations can arise where the pressure in individual tanks changes relative to other tanks. Such pressure differences between individual tanks are equalized over an adjustment period after the tank system is restarted and all tank valves are opened.

[0008] Accordingly, only after the pressures of all tanks have equalized can the fill level of the tank system, and in particular the fill level of individual tanks within the system, be determined based on a pressure reading from a central pressure sensor. This means that a leak in a tank that occurred while the system was stationary may only be detected late during operation, or not at all.

[0009] Disclosure of the Invention: Within the scope of the presented invention, a tank system, a method for operating the tank system, 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 method according to the invention naturally also apply in connection with the tank system and the energy converter according to the invention, and vice versa, so that the disclosure of the individual aspects of the invention always makes, or can make, reciprocal references.

[0010] The presented invention serves in particular to provide a means of determining the individual fill level of each tank in a tank system with multiple tanks. Specifically, the presented invention serves to detect a leak in a tank of a tank system with multiple tanks directly upon commissioning the tank system after a period of inactivity.

[0011] Thus, according to a first aspect of the presented invention, a method for operating a tank system comprising several tanks is presented.

[0012] The presented method comprises determining individual tank expectation pressures of each tank in the tank system for a current operating cycle, based on the respective individual fill states of each tank last stored in an operating cycle preceding the current operating cycle and a first temperature in the respective tanks; determining individual fill states of each tank in the tank system based on the respective determined individual tank expectation pressures, the first temperature and a second temperature in the respective tanks; and determining an overall fill state of the tank system by adding the determined individual fill states, whereby the individual fill states of each tank are weighted according to their tank volume, with the first temperature being measured before the second temperature.The presented method is based on combining various data collected at different times during the operation of the tank system. Specifically, historical data from individual fill levels last stored in a previous operating cycle are retrieved from a memory, i.e., queried, in order to update this historical data using currently measured temperatures in the respective tanks of the tank system and, consequently, to determine a target tank pressure for each tank in the system.

[0013] This means that the fill levels of the respective tanks, which were used in a previous operating cycle where pressure equalization between the tanks has already taken place, are used to directly determine a tank expectation pressure for each tank, i.e., even before pressure equalization between the respective tanks.

[0014] By using historical data, the initial temperature before the tank valves were opened, and the current temperature in each tank, which correlates with the pressure in the tanks, the expected tank pressure can be determined even before pressure equalization between the different tanks in the tank system is complete. In other words, the initial and current temperatures in the tanks are used as an estimate of the change in the current pressure in a tank compared to the historical fill level, so that the historical fill level can be corrected to the expected tank pressure based on the current temperature.

[0015] The tank expectation pressure can be displayed directly or, if necessary, transformed into an expected fill level, in order to inform a user, e.g. immediately after a start of the tank system, about the fill level of the tank system or the respective tanks.

[0016] Since the pressures and, consequently, the temperatures in the individual tanks of a tank system change continuously, particularly during the start-up phase of the tank system, in which pressure equalization takes place between the individual tanks, the tank expectation pressures are used to determine a valid fill level of the respective tanks. For this purpose, the respective tank expectation pressures are updated with temperature values ​​measured at a second time point, which is later than the initial time point, to determine the fill level.

[0017] By adding the weighted individual fill levels, a conclusion is finally drawn about the overall fill level of the tank system.

[0018] It may be provided that the first temperature is measured before an operating point at which the respective tank valves are opened, and the second temperature is measured at an operating point after the respective tank valves have been opened and before all pressures in the respective tanks of the tank system have been equalized.

[0019] It may also be provided that the determination of the individual tanker expectation pressures is carried out continuously, starting with the start of the current operating cycle until a predetermined switching time, and that the determination of the individual fill levels is carried out continuously, starting with the switching time.

[0020] A switching point allows for the separation of a measuring range or duration before pressure equalization between the respective tanks of the tank system and a measuring range or duration after pressure equalization. Accordingly, after the switching point, the respective tank expectation pressures can be updated or transformed to reflect the fill levels.

[0021] It may further be provided that the presented method includes determining a reference total fill level of the entire tank system for the current operating cycle based on a pressure determined by a pressure sensor in a high-pressure system of the tank system during an operating cycle preceding the current operating cycle with pressure equalized between the respective tanks, minus a mass discharged from the tank system since the start of the current operating cycle, determining a difference between the determined reference total fill level and the total fill level, and issuing a validation message if the amount of the determined difference is less than a predefined validation threshold, or issuing an error message if the amount of the determined difference is greater than a predefined error threshold.

[0022] Based on a reference total fill level of an entire tank system, which is based on a historically determined total fill level, updated or transformed using a mass removed from the tank system since the tank system was started, a leakage that occurred when the tank system was at a standstill can be determined particularly quickly and accurately by comparing the reference total fill level with the total fill level determined according to the invention.

[0023] It may also be provided that the mass removed from the tank system since the start of the current operating cycle is determined based on a parameter transmitted to the tank system by a consumer.

[0024] Since a consumer typically measures the mass extracted from a given tank system using a sensor, such as a mass flow sensor or a flow sensor, in order to adjust the consumer's subsystems accordingly, the measured values ​​determined by the consumer, or a correspondingly transformed parameter, can be used to determine the reference total fill level.

[0025] It may also be provided that, in the event that the tank system is deactivated within a specified period after a start of the tank system, the determined individual fill levels are stored in a memory and used to determine the individual tank expectation pressures upon a subsequent start of the tank system.

[0026] Since no valid fill levels can be determined when a tank system is deactivated before pressure equalization occurs between the respective tanks of the system, the determination of the tank expectation pressures can be continued directly on the already determined data in such a case, which enables optimized tank valve control when starting after previous operation in which no pressure equalization between the tanks was achieved.

[0027] According to a second aspect, the presented invention relates to a tank system for storing a fluid.

[0028] The presented tank system comprises a plurality of tanks, each of which has a tank valve and a temperature sensor, a central high-pressure line system that is fluidly coupled to all tanks of the plurality of tanks, a pressure sensor arranged on the high-pressure line system and a computing unit, the computing unit being configured to carry out one possible embodiment of the presented method.

[0029] In the context of the presented invention, a computing unit is to be understood as a computer, a processor, a control unit or any other programmable circuit.

[0030] The presented method is particularly suitable for operating the presented tank system.

[0031] According to a third aspect, the presented invention relates to an energy converter.

[0032] The presented energy converter comprises a consumer, such as a fuel cell system or an internal combustion engine, which converts a fluid supplied by the tank system, in particular into potential or electrical energy; a fluid sensor that determines a characteristic value describing the mass of the fluid supplied by the tank system over a predetermined period; and a processing unit, wherein the processing unit of the energy converter is configured to transmit the determined characteristic value to the processing unit of the tank system. Advantages described in detail with regard to the method for operating a tank system according to the first aspect of the invention apply equally to the tank system for storing a fluid according to the second aspect of the invention and to the energy converter according to the third aspect of the invention, and vice versa.

[0033] 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 each be essential to the invention individually or in any combination.

[0034] Drawings

[0035] They each show schematically:

[0036] Figure 1 shows a representation of a possible embodiment of the presented method, and

[0037] Figure 2 shows a possible embodiment of the presented energy converter with a possible embodiment of the presented tank system.

[0038] Description of the exemplary implementations

[0039] Fig. 1 shows a method 100 for operating a tank system comprising several tanks.

[0040] Method 100 comprises a first determination step 101, in which individual tank expectation pressures of each tank in the tank system for a current operating cycle are determined based on the respective individual fill states of the respective tanks last stored in an operating cycle preceding the current operating cycle and an initial temperature in the respective tanks. Furthermore, Method 100 comprises a second determination step 103, in which individual fill states of each tank in the tank system are determined based on the respective determined individual tank expectation pressures, the initial temperature, and a second temperature in the respective tanks.

[0041] Furthermore, the procedure 100 includes a third determination step 105, in which an overall fill level of the tank system is determined by adding the individual fill levels determined in the second determination step 103, whereby the individual fill levels of respective tanks are weighted according to their tank volume.

[0042] According to procedure 100, the first temperature is measured before the second temperature. Specifically, the first temperature is measured at the first time when the respective tank valves are opened, and the second temperature is measured at a second time after the respective tank valves have been opened and before the tank pressures between the respective tanks of the tank system have been equalized.

[0043] Optionally, the procedure includes a fourth determination step 107, in which a reference total fill level of the entire tank system for the current operating cycle is determined based on a pressure determined by a pressure sensor in a high-pressure system of the tank system during an operating cycle preceding the current operating cycle with pressure equalized between the respective tanks, less a mass removed from the tank system since the start of the current operating cycle, and a fifth determination step 109, in which a difference between the determined reference total fill level and the total fill level determined in the third determination step 105 is determined.

[0044] Furthermore, procedure 100 includes an optional output step 111, in which a validation message is issued if the amount of the determined difference is less than a specified validation threshold, or an error message is issued if the amount of the determined difference is greater than a specified error threshold.

[0045] For example, the error message or the validation message can be displayed on a screen and / or stored in memory to inform a user about the status of the tank system or to be used in other processes.

[0046] Fig. 2 shows an energy converter 300, which includes a tank system 200, a consumer 301 in the form of a fuel cell system supplied with fuel by the tank system 200, a fluid sensor 303, configured to determine a characteristic value that describes a mass of the fluid provided by the tank system 200 in a specified period of time, and a computing unit 305.

[0047] The tank system 200 comprises a plurality of tanks 201, each of which is assigned a tank valve 203 and a temperature sensor 205, a central high-pressure line system 207 which is fluidly coupled to all tanks 201, a pressure sensor 209 arranged on the high-pressure line system 207 and a computing unit 211 which is configured to carry out the method 100 according to Fig. 1.

[0048] The processing unit 305 of the energy converter 300 is configured to transmit the determined characteristic value to the processing unit 211 of the tank system 200. For this purpose, the processing unit 305 of the energy converter 300 and the processing unit 211 of the tank system 200 can be communicatively coupled via a communication interface, such as a wired or wireless communication interface.

Claims

Claims 1. Method (100) for operating a tank system (200) comprising several tanks (201), wherein the method (100) comprises: Determine (101) individual tank expectation pressures of each tank (201) of the tank system (200) for a current operating cycle, based on the respective individual fill states of each tank (201) last stored in an operating cycle preceding the current operating cycle and an initial temperature in each tank (201), Determine (103) individual fill levels of each tank (201) of the tank system (200), based on the respective determined individual tank expectation pressures, the first temperature and a second temperature in the respective tanks (201), Determining (105) an overall fill level of the tank system (200) by adding the determined individual fill levels, wherein the individual fill levels of each tank are weighted according to their tank volume, wherein the first temperature is measured before the second temperature.

2. Method (100) according to claim 1, characterized in that the first temperature is measured before an operating point at which the respective tank valves are opened, and the second temperature is measured at an operating point after the respective tank valves have been opened and before all pressures in the respective tanks of the tank system (200) are equalized.

3. Method (100) according to claim 1 or 2, characterized in that the determination (101) of the individual tanker expectation pressures and the determination (103) of the individual filling states is carried out continuously, starting with a start of the current operating cycle until a predetermined switching time.

4. Method (100) according to one of the preceding claims, characterized in that the method (100) further comprises: Determining (107) a reference total fill level of the entire tank system (200) for the current operating cycle based on a pressure determined by a pressure sensor (209) in a high-pressure system (207) of the tank system (200) during an operating cycle preceding the current operating cycle with pressure equalized between the respective tanks (201), less a mass discharged from the tank system (200) since the start of the current operating cycle, Determine (109) a difference between the determined reference total fill level and the total fill level, issue (111) a validation message if an amount of the determined difference is less than a specified validation threshold, or Output (111) an error message if the amount of the calculated difference is greater than a specified error threshold.

5. Method (100) according to claim 4, characterized in that the mass discharged from the tank system (200) since the start of the current operating cycle is determined on the basis of a characteristic value transmitted to the tank system (200) by a consumer (301).

6. Method (100) according to one of the preceding claims, characterized in that, in the event that the tank system (200) is deactivated within a predetermined period after a start of the tank system (200), the determined individual fill states are stored in a memory and are used to determine the individual tank expectation pressures upon a subsequent start of the tank system (200).

7. Tank system (200) for storing a fluid, wherein the tank system (200) comprises: a plurality of tanks (201), wherein a tank valve (203) and a temperature sensor (205) are arranged on each tank (201) of the plurality of tanks (201), a central high-pressure line system (207) which is fluid-conductingly coupled to all tanks (201) of the plurality of tanks (201), a pressure sensor (209) arranged on the high-pressure line system (207), a computing unit (211), wherein the computing unit (211) is configured to perform a method (100) according to any one of claims 1 to 6.

8. Energy converter (300) for converting energy, wherein the energy converter (300) comprises: a tank system (200) according to claim 7, a consumer (301) that converts a fluid provided by the tank system (200), a fluid sensor (303) configured to determine a characteristic value describing a mass of the fluid provided by the tank system (200) in a predetermined period, a computing unit (305) wherein the computing unit (305) of the energy converter (300) is configured to transmit the determined characteristic value to the computing unit (211) of the tank system (200).

9. Energy converter (300) according to claim 8, characterized in that the consumer (301) is a fuel cell system.

10. Energy converter (300) according to claim 8, characterized in that the consumer (301) is an internal combustion engine.

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