Measuring device and method for measuring liquid level height of liquid in low-temperature container

Abstract

The invention provides a measuring device and method for measuring the liquid level height of liquid in a low-temperature container, and relates to the field of measuring the liquid level height of the liquid in the low-temperature container, the measuring device comprises a liquid frame structure, a temperature sensor, a signal acquisition structure and a data processing structure, the liquid frame structure comprises an outer frame structure and an inner frame structure, the outer frame structure and the inner frame structure are each of a cuboid structure. A plurality of temperature sensors are arranged, the plurality of temperature sensors are arranged on the side wall of the inner frame structure, the plurality of temperature sensors are distributed in the direction perpendicular to the ground, and the temperature sensors are attached to the outer side wall of the inner frame structure; the signal acquisition structure is electrically connected with the temperature sensor, and the signal acquisition unit is arranged on the outer frame structure; and the data processing structure is electrically connected with the signal acquisition structure. According to the invention, the problems of intrusive damage to the heat insulation layer, weak anti-interference capability and limited application scene are solved.

Description

Technical Field

[0001] This invention relates to the field of measuring the liquid level in a cryogenic container, and more specifically, to a measuring device and method for measuring the liquid level in a cryogenic container. Background Technology

[0002] Current liquid level measurement technologies for cryogenic containers mainly rely on capacitive, ultrasonic, and gravimetric methods. Capacitive level gauges detect capacitance changes by inserting electrodes inside the container, but strong magnetic fields can interfere with the electrode's electric field distribution, leading to inaccurate measurements. Furthermore, probes penetrating the container wall can damage the insulation structure, increasing heat leakage by more than 30% and significantly shortening the cryogenic liquid storage period. While ultrasonic level gauges do not require immersion in the liquid, cryogenic mists scatter the sound signal, causing echo intensity attenuation by more than 50%, with errors reaching ±5% in liquid nitrogen environments. Additionally, their transmitters / receivers require large-diameter holes, further weakening insulation performance. Gravimetric methods require modification of the entire container's weighing platform, making them unsuitable for fixed installations or mobile devices. All these methods suffer from core drawbacks: invasive damage to the insulation layer, weak anti-interference capabilities, and limited applicability.

[0003] Therefore, there is an urgent need for a measuring device and method for measuring the liquid level in a cryogenic container to solve existing technical problems such as invasive damage to the insulation layer, weak anti-interference ability, and limited applicable scenarios. Summary of the Invention

[0004] The purpose of this invention is to provide a measuring device and method for measuring the liquid level in a cryogenic container, thereby addressing the aforementioned problem. To achieve this purpose, the technical solution adopted by this invention is as follows:

[0005] On one hand, this application provides a measuring device for measuring the liquid level in a cryogenic container, comprising: a liquid frame structure, temperature sensors, a signal acquisition structure, and a data processing structure. The liquid frame structure includes an outer frame structure and an inner frame structure, both of which are rectangular parallelepiped structures. Multiple temperature sensors are disposed on the sidewalls of the inner frame structure and distributed perpendicular to the ground. The temperature sensors are fitted against the outer sidewalls of the inner frame structure. The signal acquisition structure is electrically connected to the temperature sensors, and the signal acquisition unit is disposed on the outer frame structure. The data processing structure is electrically connected to the signal acquisition structure.

[0006] Optionally, the temperature sensor is a PT100 platinum resistance temperature sensor, and the space between the sensing end face of the temperature sensor and the outer wall of the inner frame structure is filled with thermally conductive material.

[0007] Optionally, the signal acquisition structure includes a signal acquisition unit and a signal transmission unit, which are electrically connected. The signal acquisition unit includes a sealed connector and a cable. The sealed connector is disposed through the outer frame structure. One end of the sealed connector is disposed between the outer frame structure and the inner frame structure, and the other end of the sealed connector is disposed on the outside of the outer frame. The sealed connector is electrically connected to the temperature sensor through the cable.

[0008] Optionally, the signal transmission unit includes a multi-channel signal conditioning circuit, an analog-to-digital converter module, and a Modbus RTU communication module. The input terminal of the multi-channel signal conditioning circuit is electrically connected to the signal acquisition structure, the output terminal of the multi-channel signal conditioning circuit is electrically connected to the input terminal of the analog-to-digital converter module, and the output terminal of the analog-to-digital converter module is electrically connected to the Modbus RTU communication module.

[0009] Optionally, the signal transmission unit is electrically connected to the data processing structure via an RS485 bus, with one end of the RS485 bus electrically connected to the Modbus RTU communication module and the other end electrically connected to the data processing structure.

[0010] Optionally, the data processing structure includes a microcontroller that uses signals acquired by a signal acquisition structure to determine the liquid level height.

[0011] Optionally, both the outer frame structure and the inner frame structure are provided with through holes at their tops. A liquid filling and venting pipe is provided on the through hole. The bottom of the liquid filling and venting pipe passes through the through hole and is disposed inside the inner frame structure. The liquid filling and venting pipe is sealed to the through hole.

[0012] Optionally, it also includes a display and a buzzer alarm, the display being electrically connected to the data processing structure and the buzzer alarm being electrically connected to the data processing structure.

[0013] On the other hand, this application provides a measurement method for a measuring device for measuring the liquid level height inside a cryogenic container, comprising:

[0014] Multiple temperature sensors are arranged vertically on the side of the inner frame structure and are tightly attached to the wall surface by thermally conductive material;

[0015] The temperature data of each temperature sensor is collected in real time through the data acquisition structure, and the signal is transmitted to the data processing structure through a sealed air connector;

[0016] Based on the data processing structure, the position of the lowest sensor among all the sensors with rising temperatures is identified, and its temperature change gradient value is obtained.

[0017] The current liquid level height is calculated based on the position of the lowest sensor among all the sensors that have experienced temperature increases, the temperature change gradient value, and the preset temperature-liquid level calibration relationship.

[0018] Optionally, the preset method for the preset temperature-liquid level calibration relationship includes:

[0019] By mapping the temperature of each sensor to its corresponding liquid level based on historical measurements, the correspondence between the temperature of each sensor and its corresponding liquid level is obtained.

[0020] The correspondence between the temperature of each sensor and its corresponding liquid level is used as a preset temperature-liquid level calibration relationship.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention utilizes a high-precision PT100 temperature sensor array vertically arranged on the outer wall of the inner liner of a cryogenic container. Leveraging the dynamic temperature gradient formed by heat conduction between the inner and outer liner, it accurately captures the position of the lowest sensor among all sensors experiencing temperature increases. The signal is extracted via a sealed connector and transmitted to a microcontroller through a multi-channel conditioning circuit and Modbus RTU communication. A dual-mode calibration algorithm (absolute temperature mapping or relative temperature rise fitting) is then used to calculate the liquid level in real time. This innovative approach achieves non-invasiveness, requires no alteration to the cryogenic container's structure, has minimal impact on heat leakage, does not affect the container's insulation time, and is structurally simple and unaffected by magnetic fields, cryogenic mist, or mechanical vibration. This invention is also applicable to rectangular / annular irregular-shaped containers without requiring infrastructure modifications.

[0023] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a three-dimensional structural schematic diagram of a measuring device for measuring the liquid level in a cryogenic container, as described in an embodiment of the present invention.

[0026] Figure 2This is a schematic flowchart of a measurement method for a measuring device for measuring the liquid level in a cryogenic container, as described in an embodiment of the present invention.

[0027] The markings in the diagram are: 1. Outer frame structure; 2. Inner frame structure; 3. Liquid filling and exhaust pipe; 4. Temperature sensor; 5. Sealed aviation connector; 6. Data processing structure; 7. Display; 8. Buzzer alarm. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] Example 1:

[0031] like Figure 1 As shown, this embodiment provides a measuring device for measuring the liquid level in a cryogenic container, comprising: a liquid frame structure, temperature sensors 4, a signal acquisition structure, and a data processing structure 6. The liquid frame structure includes an outer frame structure 1 and an inner frame structure 2, both of which are rectangular parallelepiped structures. Multiple temperature sensors 4 are disposed on the sidewalls of the inner frame structure 2, distributed perpendicular to the ground, and attached to the outer sidewalls of the inner frame structure 2. The signal acquisition structure is electrically connected to the temperature sensors 4, and the signal acquisition unit is disposed on the outer frame structure 1. The data processing structure 6 is electrically connected to the signal acquisition structure.

[0032] The measuring device of this invention achieves a core breakthrough in non-invasive liquid level monitoring through topological optimization of an inner and outer double-layer frame. Specifically, the inner frame structure 2, as a pressure-bearing carrier in direct contact with the cryogenic liquid, has a cuboid configuration that maximizes the effective monitoring area of ​​the side walls while ensuring that the temperature sensor 4 forms a high-density gradient array in the vertical direction. The sensor and the wall surface are filled with thermally conductive materials (such as thermally conductive silicone grease), which reduces temperature transfer delay by eliminating air gap thermal resistance, far lower than the liquid nitrogen evaporation rate. The outer frame structure 1 serves as an electromagnetic shielding and mechanical protection layer, and its rigid cuboid structure prevents sensor displacement due to cold contraction. The partitioned layout of the signal acquisition unit and data processing structure 6 reduces thermoelectric interference noise suppression and is unaffected by magnetic fields, cryogenic fog, and mechanical vibration. This structural design enables the device to achieve continuous liquid level monitoring in extreme scenarios such as superconducting magnetic levitation trains and liquid nitrogen Dewars (cryo-thermal levitation devices).

[0033] The temperature sensor 4 is a PT100 platinum resistance temperature sensor 4, and the sensing end face of the temperature sensor 4 is filled with thermally conductive material between it and the outer wall of the inner frame structure 2.

[0034] It is understood that the PT100 platinum resistance temperature sensor of this invention has a measurement accuracy of ±0.1% in the liquid nitrogen temperature range (77K), which meets the temperature resolution requirements of liquid level detection. The thermally conductive material filling completely eliminates the air gap between the sensor end face and the container wall, ensuring real-time temperature transmission. The pure resistance working principle of PT100 makes it free from signal drift in strong magnetic field environments (such as superconducting magnetic levitation systems).

[0035] The signal acquisition structure includes a signal acquisition unit and a signal transmission unit, which are electrically connected. The signal acquisition unit includes a sealed connector 5 and a cable. The sealed connector 5 is disposed through the outer frame structure 1. One end of the sealed connector 5 is disposed between the outer frame structure 1 and the inner frame structure 2, and the other end of the sealed connector 5 is disposed on the outside of the outer frame. The sealed connector 5 is electrically connected to the temperature sensor 4 through the cable.

[0036] It is understood that the present invention uses a sealed aviation plug 5 with a vacuum sandwich sealing structure to completely block the oxidation or short circuit of the circuit caused by the infiltration of external moisture / air, and ensure the long-term stability of the sensor signal in an environment of -196℃ to 25℃. The sealed design of the aviation plug through the outer frame 1 reduces the heat leakage of the container at a single point and maintains the heat preservation time of the container. The connection between the sealed aviation plug 5 and the cable eliminates the signal interruption caused by the boiling impact of liquid nitrogen.

[0037] The signal transmission unit includes a multi-channel signal conditioning circuit, an analog-to-digital converter module, and a Modbus RTU communication module. The input terminal of the multi-channel signal conditioning circuit is electrically connected to the signal acquisition structure, the output terminal of the multi-channel signal conditioning circuit is electrically connected to the input terminal of the analog-to-digital converter module, and the output terminal of the analog-to-digital converter module is electrically connected to the Modbus RTU communication module.

[0038] It is understood that this invention improves the signal-to-noise ratio of PT100 by differential amplifying and filtering the signal through a multi-channel signal conditioning circuit, effectively suppresses common-mode interference caused by liquid nitrogen boiling, and ensures error-free data packet transmission in a strong electromagnetic environment through the transmission mechanism of the Modbus RTU communication module.

[0039] The signal transmission unit is electrically connected to the data processing structure 6 via an RS485 bus. One end of the RS485 bus is electrically connected to the Modbus RTU communication module, and the other end is electrically connected to the data processing structure 6.

[0040] It is understood that the differential signal transmission mechanism of the RS485 bus in this invention improves the common-mode rejection ratio in a strong magnetic field environment, ensuring that the temperature data is error-free within a specified distance.

[0041] The data processing structure 6 includes a microcontroller, which uses signals acquired by the signal acquisition structure to determine the liquid level height.

[0042] It is understood that this invention uses a microcontroller (such as an Arduino or STM32 series microcontroller) as the core processor and has a built-in algorithm for calculating the content of low-boiling-point liquids. This algorithm is based on the temperature gradient method and the pre-set correspondence between the container wall temperature distribution and the liquid level height of the low-boiling-point liquid to calculate the remaining liquid volume.

[0043] The outer frame structure 1 and the inner frame structure 2 are both provided with through holes at their tops. A liquid filling and venting pipe 3 is provided on the through hole. The bottom of the liquid filling and venting pipe 3 passes through the through hole and is located inside the inner frame structure 2. The liquid filling and venting pipe 3 is sealed to the through hole.

[0044] It is understood that the liquid filling and exhaust pipe 3 of the present invention serves as a key heat conduction path, forming a stable axial temperature gradient (high temperature at the top / low temperature at the bottom) between the inner and outer liner, and forming a dynamic thermal balance with a certain temperature gradient on the side wall of the inner liner. The bottom of the exhaust pipe extends to the inner liner 2, avoiding the impact of hot and cold convection on the sensor area during filling.

[0045] The system includes a display 7 and a buzzer alarm 8. The display 7 is electrically connected to the data processing structure 6, and the buzzer alarm 8 is electrically connected to the data processing structure 6.

[0046] It is understood that the display 7 of the present invention directly presents the dynamic liquid level height value, eliminating the information delay of traditional indirect measurement, and meeting the operator's need for second-level monitoring of the remaining amount of cryogenic liquid. The buzzer alarm 8, through a programmable threshold triggering mechanism, issues an audible and visual alarm when the liquid level is lower than the safety threshold, thereby realizing real-time monitoring of the liquid level.

[0047] Example 2

[0048] like Figure 2 As shown, this embodiment provides a measurement method for a measuring device for measuring the liquid level in a cryogenic container, including steps S1, S2, S3 and S4.

[0049] Step S1: Multiple temperature sensors are arranged vertically on the side of the inner frame structure and tightly attached to the wall surface by thermally conductive material;

[0050] Step S2: Collect temperature data from each temperature sensor in real time through the data acquisition structure, and transmit the signal to the data processing structure through a sealed air connector;

[0051] Step S3: Based on the data processing structure, identify the position of the lowest sensor among all the sensors with rising temperatures, and obtain its temperature change gradient value.

[0052] Step S4: Calculate the current liquid level height based on the position of the lowest sensor among all the sensors with rising temperatures, the temperature change gradient value, and the preset temperature-liquid level calibration relationship.

[0053] It is understood that this invention achieves real-time acquisition of 77K liquid nitrogen temperature signals by vertically arranging a PT100 sensor array on the outer wall of the inner liner and filling it with thermally conductive material, while maintaining the container's insulation structure; it uses a sealed insertion device and multi-channel signal conditioning to suppress signal transmission drift under strong magnetic fields and low-temperature fog; it accurately locates the critical position of liquid level drop based on the bottom temperature change point identification method; and it combines a dual-mode calibration model (absolute temperature / relative temperature rise mapping) to maintain a liquid level measurement error of ≤1.68% during the total evaporation of liquid nitrogen, ultimately achieving non-invasive, interference-resistant, and high-precision dynamic liquid level monitoring.

[0054] Step S4 includes steps S41 and S42.

[0055] Step S41: Map the temperature of each sensor measured in history to its corresponding liquid level to obtain the correspondence between the temperature of each sensor and its corresponding liquid level.

[0056] Step S42: The correspondence between the temperature of each sensor and its corresponding liquid level is used as a preset temperature-liquid level calibration relationship.

[0057] It is understood that there are two preset methods in this invention. One is to pre-establish a mapping relationship between the installation height of each temperature sensor and its measured temperature value. When the liquid level changes, the liquid level corresponding to the current sensor temperature value is directly queried. This mapping is directly based on measured data, avoiding the simplification assumption bias of the heat conduction theory formula. The other method is to use the temperature when the liquid level submerges all sensors as a benchmark to calculate the current temperature rise, and then infer the liquid level based on the nonlinear relationship between the current temperature rise and the liquid level drop. This suppresses ambient temperature drift, compresses the edge effect error when the liquid level is below the sensor to ≤1.68% natural immune magnetic field / fog interference, retains the advantages of non-invasive structure, and solves the problem of accuracy degradation of traditional liquid level detection in extreme environments through differential measurement principle.

[0058] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0059] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0061] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A measuring device for measuring the liquid level in a cryogenic container, characterized in that: A liquid frame structure, comprising an outer frame structure (1) and an inner frame structure (2), wherein both the outer frame structure (1) and the inner frame structure (2) are configured as cuboid structures; Temperature sensor (4), multiple temperature sensors (4) are provided, multiple temperature sensors (4) are provided on the side wall of the inner frame structure (2), multiple temperature sensors (4) are distributed in a direction perpendicular to the ground, and the temperature sensors (4) are attached to the outer side wall of the inner frame structure (2). The signal acquisition structure is electrically connected to the temperature sensor (4), and the signal acquisition unit is disposed on the outer frame structure (1); The data processing structure (6) is electrically connected to the signal acquisition structure.

2. The measuring device for measuring the liquid level in a cryogenic container according to claim 1, characterized in that: The temperature sensor (4) is a PT100 platinum resistance temperature sensor (4), and the sensing end face of the temperature sensor (4) is filled with thermally conductive material between it and the outer wall of the inner frame structure (2).

3. The measuring device for measuring the liquid level in a cryogenic container according to claim 1, characterized in that: The signal acquisition structure includes a signal acquisition unit and a signal transmission unit. The signal acquisition unit and the signal transmission unit are electrically connected. The signal acquisition unit includes a sealed connector (5) and a cable. The sealed connector (5) is disposed through the outer frame structure (1). One end of the sealed connector (5) is disposed between the outer frame structure (1) and the inner frame structure (2). The other end of the sealed connector (5) is disposed on the outside of the outer frame. The sealed connector (5) is electrically connected to the temperature sensor (4) through the cable.

4. The measuring device for measuring the liquid level in a cryogenic container according to claim 1, characterized in that: The signal transmission unit includes a multi-channel signal conditioning circuit, an analog-to-digital converter module, and a Modbus RTU communication module. The input terminal of the multi-channel signal conditioning circuit is electrically connected to the signal acquisition structure, the output terminal of the multi-channel signal conditioning circuit is electrically connected to the input terminal of the analog-to-digital converter module, and the output terminal of the analog-to-digital converter module is electrically connected to the Modbus RTU communication module.

5. The measuring device for measuring the liquid level in a cryogenic container according to claim 4, characterized in that: The signal transmission unit is electrically connected to the data processing structure (6) via an RS485 bus. One end of the RS485 bus is electrically connected to the Modbus RTU communication module, and the other end is electrically connected to the data processing structure (6).

6. The measuring device for measuring the liquid level in a cryogenic container according to claim 1, characterized in that: The data processing structure (6) includes a microcontroller, which determines the liquid level height based on the signal acquired by the signal acquisition structure.

7. The measuring device for measuring the liquid level in a cryogenic container according to claim 1, characterized in that: Both the outer frame structure (1) and the inner frame structure (2) have through holes at their tops. A liquid filling and venting pipe (3) is provided on the through hole. The bottom of the liquid filling and venting pipe (3) passes through the through hole and is located inside the inner frame structure (2). The liquid filling and venting pipe (3) is sealed to the through hole.

8. The measuring device for measuring the liquid level in a cryogenic container according to claim 1, characterized in that, Also includes: The display (7) and the buzzer (8) are electrically connected to the data processing structure (6).

9. The measurement method of the measuring device for measuring the liquid level height in a cryogenic container according to any one of claims 1-8, characterized in that, include: Multiple temperature sensors are arranged vertically on the side of the inner frame structure and are tightly attached to the wall surface by thermally conductive material; The temperature data of each temperature sensor is collected in real time through the data acquisition structure, and the signal is transmitted to the data processing structure through a sealed air connector; Based on the data processing structure, the position of the lowest sensor among all the sensors with rising temperatures is identified, and its temperature change gradient value is obtained. The current liquid level height is calculated based on the position of the lowest sensor among all the sensors that have experienced temperature increases, the temperature change gradient value, and the preset temperature-liquid level calibration relationship.

10. The measurement method of the measuring device for measuring the liquid level height in a cryogenic container according to claim 9, characterized in that, The preset method for the preset temperature-liquid level calibration relationship includes: By mapping the temperature of each sensor to its corresponding liquid level based on historical measurements, the correspondence between the temperature of each sensor and its corresponding liquid level is obtained. The correspondence between the temperature of each sensor and its corresponding liquid level is used as a preset temperature-liquid level calibration relationship.

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