Device for detecting the temperature of a medium in a cryogenic tank
By using a combination of a passive magnetic or inductive transmitter and receiver in a cryogenic storage tank to indirectly measure the change in the length of the inner tank to detect the medium temperature, the problem of thermal bridges formed when temperature sensor circuits pass through the vacuum insulation layer is solved, and safe and reliable temperature detection is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DAIMLER TRUCK AG
- Filing Date
- 2024-11-27
- Publication Date
- 2026-07-21
AI Technical Summary
In existing technologies, the wiring of temperature sensors in cryogenic storage tanks has the problem of forming thermal bridges through the vacuum insulation layer, which leads to inaccurate measurements and safety issues.
By combining a passive magnetic or inductive transmitter with an inductive receiver, the temperature of the medium is indirectly measured by detecting changes in the distance between the inner and outer tanks. The temperature change is inferred using an evaluation electronics unit, thus avoiding the formation of thermal bridges.
It enables robust and reliable temperature detection of the medium in cryogenic storage tanks, avoids the formation of thermal bridges, and ensures the safe operation of the storage tanks.
Smart Images
Figure CN122439062A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an apparatus for detecting the temperature of a medium in a cryogenic tank, as detailed in the preamble of claim 1. Furthermore, this invention relates to a method for ensuring the safe operation of a cryogenic tank using such an apparatus. Background Technology
[0002] The necessity of temperature monitoring in cryogenic storage tanks with inner and outer tanks is well-known in the art. This necessity is particularly evident in the need to avoid the erroneous filling of hot cryogenic tanks with cryogenic liquids, especially liquid hydrogen. This can lead to excessive pressure rises within the cryogenic tank due to the sudden evaporation of the cryogenic liquid. To address this, temperature sensors are typically introduced into the inner tank of such cryogenic storage tanks to detect the temperature of the stored medium, such as liquid hydrogen. The problem with this approach lies in the wiring arrangement to the temperature sensor, as this wiring must pass through both the outer and inner tanks, thus creating a thermal bridge through the vacuum insulation layer between the inner and outer tanks.
[0003] As an alternative, the temperature sensor can also be connected to the outer surface of the inner tank. This approach also suffers from the problem that the measured value must pass through the vacuum layer and the outer tank to be retrieved. Such an arrangement of the temperature sensor can be exemplified only by reference to US 2003 / 0029224 A1, which infers the mass of stored hydrogen based on temperature and pressure.
[0004] DE 10 2013 214 004 A1 describes an alternative method for detecting the mass of stored hydrogen (in this document, a cryogenic pressure tank with pressures up to 150 bar). The method utilizes the fact that the inner tank is typically supported relative to the outer tank by locating supports and at least one floating support. In practice, temperature changes, and especially pressure changes in cryogenic pressure tanks, cause longitudinal expansion of the inner tank, the amount of which is detected by a measuring mechanism. The mass of the stored medium in the inner tank can then be calculated from these detected values. Summary of the Invention
[0005] The objective of this invention is to provide an improved apparatus for detecting the temperature of a medium in a cryogenic storage tank and a method for ensuring the safe operation of such cryogenic storage tanks.
[0006] According to the invention, this task is accomplished by an apparatus having the features described in claim 1, particularly the features described in the characterizing portion of claim 1. Advantageous designs and improvements are derived from the dependent claims. Furthermore, this task is also accomplished by a method for ensuring the safe operation of such cryogenic storage tanks using this apparatus. Advantageous designs are also derived from the dependent claims.
[0007] The apparatus of the present invention refers to the prior art mentioned last above; however, unlike that prior art which relates to a cryogenic pressure tank, it relates to a conventional cryogenic tank, which, according to a particularly advantageous improvement of the apparatus of the present invention, operates at a maximum pressure not exceeding 25 bar (typically in the range of 6-20 bar). If the pressure exceeds, for example, the limit of 20 bar, the evaporated hydrogen will be released, a process known as evaporation loss (Boil Off).
[0008] In the device of the present invention, the measuring mechanism for detecting length changes can also be used to detect medium temperature, because since there is a linear relationship between pressure and length changes, the length changes caused by pressure can be conveniently taken into account together.
[0009] According to the present invention, a passive magnetic, inductive, and / or capacitive transmitter is arranged on the component of the floating support that connects to the inner tank. A corresponding receiver of the sensor of the measuring mechanism is arranged on the outer surface of the outer tank for detecting the distance between the transmitter and the receiver. The measuring mechanism also includes an evaluation electronics unit configured to infer the length change of the inner tank and the associated temperature change based on the distance between the transmitter and the receiver.
[0010] The length change of the inner tank is thus converted into a temperature change of the inner tank. Due to the high vacuum between the inner and outer tanks, there is excellent thermal insulation between them. Conversely, the cryogenic liquid medium, particularly liquid hydrogen, in the inner tank has good thermal conductivity with it. Therefore, the temperature of the inner tank essentially corresponds to the temperature of the medium within it. The thermal expansion of the inner tank then leads to a corresponding length change. This length change is preferably measured along the longest axis of the inner tank, where typically at least one floating support (in most cases, a locating / fixed support and exactly one floating support) is already arranged along this axis. The transmitter itself is passive and can be, for example, a permanent magnet, a passive coil, or a similar element. It moves accordingly as the inner tank undergoes a length change. The receiver detects this movement to determine the distance between the transmitter and receiver. The receiver is arranged on the outer surface of the outer tank and can be easily and efficiently installed and wired at that location without any adverse effects on the vacuum insulation between the inner and outer tanks. Under ideal insulation conditions, and without creating thermal bridges due to sensor connections, the temperature of the medium in the inner tank can thus be determined.
[0011] According to a highly advantageous design, a calibration curve of the absolute length of the inner can relative to temperature can be stored in the evaluation electronics unit, thereby allowing the temperature of the inner can to be determined directly from the detected length, and thus the temperature of the medium. Temperature detection using the device of this invention is particularly robust and reliable, and virtually unaffected by interference.
[0012] As mentioned above, different transmitters can be used. Combinations of different transmitters can also be considered, such as combining capacitive and magnetic transmitters. However, according to a particularly advantageous embodiment, the transmitter can be constructed as a permanent magnet. Such a permanent magnet can be easily and efficiently positioned in the floating support region of the inner can, and its movement can be detected externally. For this purpose, the receiver can preferably be constructed as an inductive receiver, which detects the position of the permanent magnet (the transmitter) relative to the receiver, and thereby determines the distance between the receiver and the transmitter. Combining the known length of the inner can, the wall thickness of the outer can, and the possible components involved in the floating support, the absolute length of the inner can can be determined, for example, by using the aforementioned stored calibration curve to determine the temperature.
[0013] It is preferable to use a magnetic transmitter in combination with an inductive receiver, as this combination offers significant advantages. This combination is particularly suitable for a wide variety of outer can wall materials and provides reliable results even if the material of the outer can or support pin itself is not ferromagnetic (e.g., made of aluminum or stainless steel).
[0014] A particularly advantageous design of the device of the present invention can also be provided as follows: the floating support includes a floating support pin connected to the inner tank and carrying the transmitter. Therefore, the floating support can include the floating support pin in the inner tank region, which is supported in a corresponding support seat of the floating support connected to the outer tank. Such a floating support pin can, for example, move in a spatial direction within an annular support seat that is part of the outer tank. Instead of an annular support seat, multiple individual support points can be arranged circumferentially along the floating support pin, for example, three support points spaced 120° apart.
[0015] According to a particularly advantageous design, the transmitter can be arranged on the surface of the floating support pin facing the outer tank. For example, a permanent magnet can be screwed or bonded to the floating support pin, wherein a gap is always maintained between the outer tank and the floating support pin, which, together with the outer tank wall thickness, is measured by a sensor to infer the length of the inner tank and thereby infer the temperature of the medium in the inner tank.
[0016] The method of this invention is used to ensure the safe operation of such cryogenic storage tanks, and utilizes the device of this invention to detect the temperature of the medium. The medium temperature plays a crucial role, particularly during retrieval, but primarily during the filling of the cryogenic storage tank. Therefore, according to a highly advantageous design provision of the method of this invention, the cryogenic storage tank (which has at least one filling line equipped with valves) is controlled by the temperature detected by the device as follows: the valves are kept closed when a temperature limit is exceeded to prevent filling. Thus, a preset temperature limit specifies the temperature at which filling is permitted when the temperature of the medium stored in the inner tank of the cryogenic storage tank does not exceed a certain value. Once the temperature exceeds this limit, the corresponding valve is closed. This avoids the potentially dangerous operation of filling a hot inner tank with a liquid cryogenic medium (e.g., liquid hydrogen), thereby ensuring safety. Attached Figure Description
[0017] Other advantageous designs of this device also arise from the embodiments detailed below with reference to the accompanying drawings, wherein:
[0018] Figure 1 A schematic cross-sectional view of a cryogenic storage tank with floating supports and positioning supports is shown.
[0019] Figure 2 Show Figure 1 An enlarged view of the central region II, in which a device constructed according to the present invention is provided. Detailed Implementation
[0020] Figure 1 A cryogenic storage tank 1 is schematically shown. Cryogenic storage tank 1 is used to store cryogenic liquid media, such as liquid hydrogen (LH2). Liquid hydrogen (LH2) is stored in an inner tank, designated 2. This inner tank 2 is arranged within an outer tank, designated 3. The inner tank is supported in the outer tank 3 by means of a positioning support 4 (exemplarily shown on the left) and a floating support 5 (schematically shown accordingly on the right). The outer tank 3 is evacuated in a gap 6 formed between the outer tank 3 and the inner tank 2. Preferably, a high vacuum is present to achieve the best possible insulation effect for the inner tank 2. Furthermore, the outer tank 3 may, of course, be covered with an additional insulation layer, such as an insulation layer made of foam or similar materials, on its outer surface.
[0021] For various operating conditions of this type of cryogenic storage tank 1, especially for filling with fresh liquid hydrogen LH2, it is crucial to know the temperature of the liquid hydrogen LH2, i.e., the medium in the inner tank 2. During filling, for safety reasons, valve devices (neither shown) in the filling pipeline can be closed to reliably prevent filling operations that could lead to unsafe temperature and / or pressure increases.
[0022] To robustly and reliably monitor the temperature of the medium in inner tank 2, while avoiding unnecessary thermal bridges in the vacuumed gap 6, a setting can be implemented. Figure 2 The measuring mechanism 7 shown is located in the area of the floating support 5. For this purpose, the floating support 5 may include a floating support pin 8 arranged in the support base 9. Figure 2 The structure shown is purely exemplary; the actual structure would strive to minimize the heat transfer cross-section accordingly. However, it has no further connection to the measuring mechanism 7 described herein. The selected schematic diagram is sufficient for illustration.
[0023] As the temperature rises, the floating support pin 8 moves to the right in the direction of the double arrows shown in the diagram, and to the left when the temperature decreases. As indicated by the double arrows, this movement originates from the length change Δl of the inner tank 2. The floating support pin 8 has a transmitter, specifically a permanent magnet, labeled 10. A receiver 11 is located inside the sensor 12, paired with the transmitter 10. This receiver 11 can be configured as an inductive receiver 11. Therefore, the sensor 12, together with the receiver 11 and the transmitter 10, constitutes a detection device for detecting the distance between the transmitter 10 and the receiver 11. They are components of the measuring mechanism 7, which also includes an evaluation electronics unit 13 that converts the detected distance between the transmitter 10 and the receiver 11 into the actual length of the inner tank 2, taking into account the known initial lengths of the inner tank 2 and the floating support pin 8, as well as the wall thickness of the outer tank 3. This actual length directly corresponds to the temperature of the inner tank 2, and thus to the temperature of the cryogenic medium (i.e., liquid hydrogen LH2) stored in the inner tank 2. Without requiring piping components, sensors, or similar parts to pass through the gap 6, which serves as the main insulation structure of the inner tank 2, the length change Δl can be robustly and reliably detected in a non-contact manner, thereby detecting the temperature of the stored medium and its temperature changes.
Claims
1. An apparatus for detecting the temperature of a medium in a cryogenic storage tank (1), the cryogenic storage tank comprising an inner tank (2) for the cryogenic medium and an outer tank (3) surrounding the inner tank, wherein, The inner tank (2) is supported in the vacuumed outer tank (3) by a positioning support (4) and at least one floating support (5). The device has a measuring mechanism (7) located in the region of the floating support (5) for detecting the length change (Δl) of the inner tank (2). Its features are, A passive magnetic, inductive, and / or capacitive transmitter (10) is arranged on the component (8) of the floating support (5) that is connected to the inner tank (2), wherein a corresponding receiver (11) of the sensor (12) of the measuring mechanism (7) is arranged on the outer surface of the outer tank (3) for detecting the distance between the transmitter (10) and the receiver (11), and wherein the measuring mechanism (7) includes an evaluation electronics unit (13) configured to infer the length change (Δl) of the inner tank (2) and the associated temperature change based on the distance between the transmitter (10) and the receiver (11).
2. The apparatus according to claim 1, characterized in that, The evaluation electronic unit (13) stores a calibration curve of the absolute length of the inner tank (2) relative to temperature.
3. The apparatus according to claim 1 or 2, characterized in that, The transmitter (10) is designed as a permanent magnet.
4. The apparatus according to any one of claims 1 to 3, characterized in that, The receiver (11) is configured as an inductive receiver (11).
5. The apparatus according to any one of claims 1 to 4, characterized in that, The floating support (5) includes a floating support pin (8) connected to the inner tank (2) and carrying the transmitter (10).
6. The apparatus according to claim 5, characterized in that, The transmitter (10) is arranged on the surface of the floating support pin (8) facing the outer tank (3).
7. The apparatus according to any one of claims 1 to 6, characterized in that, The inner tank (2) is designed for a maximum pressure of less than 25 bar.
8. The apparatus according to claim 7, characterized in that, The inner tank (2) is designed for a maximum pressure of approximately 20 bar.
9. A method for ensuring the safe operation of a cryogenic storage tank, the cryogenic storage tank comprising an inner tank (2) for cryogenic media and an outer tank (3) surrounding the inner tank, wherein, The inner tank (2) is supported in the evacuated outer tank (3) by a positioning support (4) and at least one floating support (5), and the cryogenic storage tank has at least one filling pipeline equipped with a valve device. Its features are, The temperature of the cryogenic medium is determined using the apparatus according to any one of claims 1 to 8.
10. The method according to claim 9, characterized in that, The detected medium temperature is compared with a limit temperature, wherein when the medium temperature exceeds a preset limit temperature, the valve device in the filling pipeline is closed.