A device and method for detecting the liquid level of a container

Abstract

The present application discloses a detection device and a detection method for the liquid level of a container, including a heater and a temperature sensor. The heater is arranged at a preset monitoring position in the container and is used to heat the medium at the preset monitoring position; the temperature sensor is arranged at the preset monitoring position in the container and is used to detect the temperature change of the medium at the preset monitoring position so as to judge the liquid level at the preset monitoring position. The device and method disclosed in the present application are simple to operate, can reduce the detection cost and have good economy.

Description

Technical Field

[0001] This application relates to the field of liquid level detection, and in particular to a container liquid level detection device and a detection method. Background Art

[0002] In the cryogenic field, the resolution requirement for the liquid level in a container is generally not high and can be met by discrete measurement. For the liquid level detection requirements of discrete measurement, the accuracy is not very strict, and most continuous measurement instruments and equipment can easily meet it. However, if a continuous liquid level measurement device is used at extremely low temperatures, the performance requirements of the device need to be strengthened, which may increase the complexity of the installation process and lead to an increase in the input cost. Therefore, for the need of discrete liquid level measurement under special environmental and unstable working conditions, corresponding liquid level detection methods and devices need to be developed to more economically meet the measurement requirements. Summary of the Invention

[0003] In view of this, embodiments of this application are expected to provide a container liquid level detection device and a detection method to solve the problem of poor economy in discrete liquid level measurement under special environments.

[0004] To achieve the above object, the technical solution of the embodiments of this application is realized as follows:

[0005] Embodiments of this application disclose a container liquid level detection device and a detection method, including:

[0006] A heater, arranged at a preset monitoring position in the container, for heating the medium at the preset monitoring position;

[0007] A temperature sensor, arranged at the preset monitoring position in the container, for detecting the temperature change of the medium at the preset monitoring position to judge the liquid level at the preset monitoring position.

[0008] Further, the detection device further includes:

[0009] A sleeve, arranged in the container, and both the heater and the temperature sensor are arranged in the sleeve.

[0010] Further, the number of sleeves is one, and multiple pairs of the heater and the temperature sensor are arranged at intervals in the sleeve, and the wiring terminals of each pair of the heater and the temperature sensor are uniformly led out from the sleeve outlet to monitor the liquid levels at different preset monitoring positions; or,

[0011] The number of sleeves is multiple, and one pair of the heater and the temperature sensor is arranged in each sleeve to monitor the liquid levels at different preset monitoring positions.

[0012] Further, the detection device further includes:

[0013] A filler, disposed inside the sleeve, is used to fill the gap between the sleeve, the heater and the temperature sensor for heat insulation and heat conduction.

[0014] On the other hand, an embodiment of the present application discloses a method for detecting the liquid level of a container. By using the detection device of any one of the above, the detection method includes:

[0015] Put the detection device into the container to be measured;

[0016] Determine the data acquisition requirements for the detection device to detect the liquid level of the container;

[0017] Apply electric heating power to the heater at the preset monitoring position;

[0018] Obtain the temperature change measured by the temperature sensor at the preset monitoring position;

[0019] Judge the position of the liquid-phase medium according to the temperature change at the preset monitoring position.

[0020] Further, before the step of putting the detection device into the container to be measured, the detection method further includes:

[0021] Determine the spatial dimension of the container and the number of the preset monitoring positions;

[0022] Select a suitable heater and temperature sensor according to the spatial dimension of the container and the properties of the medium to be monitored;

[0023] Determine the arrangement mode of the detection device according to the number of the monitoring positions.

[0024] Further, the step of determining the data acquisition requirements for the detection device to detect the liquid level of the container includes:

[0025] For those with high requirements for the liquid level data of the container, adopt the synchronous heating and synchronous detection mode for all the preset monitoring positions;

[0026] For those with low requirements for the liquid level data of the container, adopt the asynchronous heating and asynchronous detection mode for all the preset monitoring positions.

[0027] Further, the asynchronous heating and asynchronous detection mode includes:

[0028] Heat and detect the temperature change at each position of the monitoring position one by one in a preset direction;

[0029] After determining the liquid level state of the upper position, according to its liquid level detection result, clarify the necessity of detecting the liquid level of the lower position;

[0030] If the liquid level position can be clearly determined after the upper position is detected, the subsequent position detection heating operation is stopped, and only the heating states of the positions on both sides where the liquid level is located are retained for reference of liquid level change indication.

[0031] Further, in the step of applying electric heating power to the heater at the preset monitoring position, the electric heating power is configured as:

[0032] After applying the electric heating power, the temperature change of the detection device at the liquid phase medium is within a preset range, and the temperature change of the detection device at the gas phase medium is outside the preset range.

[0033] The embodiment of the present application discloses a container liquid level detection device and a detection method. By heating the medium at the monitoring position with a heater and using a temperature sensor to detect the temperature change of the medium at the monitoring position, the interval where the liquid level is located can be effectively detected. The structure is simple, the detection cost is low, and the economy is high. Description of the Drawings

[0034] Figure 1 It is a schematic structural diagram of a container liquid level detection device provided by an embodiment of the present application;

[0035] Figure 2 It is a schematic structural diagram of a detection device with multiple sleeves;

[0036] Figure 3 It is a schematic flowchart of a container liquid level detection method provided by an embodiment of the present application;

[0037] Figure 4 It is a schematic flowchart of another container liquid level detection method provided by an embodiment of the present application.

[0038] Description of the Reference Numerals

[0039] Detection device 1; Heater 11; Temperature sensor 12; Sleeve 13; Container 2; Monitoring position 21; Medium 22. Detailed Description of the Embodiment

[0040] It should be noted that, without conflict, the embodiments and technical features in the embodiments of the present application can be combined with each other. The detailed description in the detailed implementation manner should be understood as an explanatory illustration of the purpose of the present application and should not be regarded as an improper limitation of the present application.

[0041] The present application will be further described in detail below with reference to the drawings and specific embodiments. The descriptions such as "first" and "second" in the embodiments of the present application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly including at least one feature. In the description of the embodiments of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0042] With the in-depth development of modern production technology, the demand for liquid level measurement spreads across all fields of industrial production. Currently, there are mainly two demand forms for liquid level detection: discrete measurement and continuous measurement. Discrete measurement is mainly used to monitor the liquid level at fixed positions, such as upper and lower limit indications. Continuous measurement is the continuous measurement that covers all possible liquid level paths. According to different working environments, various detection instruments are used. Currently, there are already many mature liquid level detection methods, such as pressure method, electro method, ultrasonic method, nuclear radiation method, magnetoelectric method, optical method, etc. With the increasing development of automatic control technology and sensor technology, liquid level detection methods and corresponding instruments are constantly improving and updating, and the adaptability to the demand for continuous high-precision liquid level measurement is getting better and better.

[0043] In the cryogenic field, the establishment and maintenance of a low-temperature environment are generally achieved through cryogenic containers. In terms of providing a low-temperature environment, the resolution requirement for the liquid level in the container is generally not high and can be met by discrete measurement. In comparison, the accuracy requirement for the liquid level detection demand of discrete measurement is not very strict, and its required functions can be easily met by most continuous measurement instruments and equipment. However, if a continuous liquid level measurement device that can work at extremely low temperatures is used for a task that can be easily accomplished by a less capable device, it is obviously uneconomical. In addition, in some application scenarios, there may be boiling and foaming conditions, the density of the measurement medium is unstable, the measurement liquid surface may be oscillating, and the liquid surface disturbance will cause great interference to most liquid level sensors, and effective liquid level data cannot be obtained. Therefore, for the demand of discrete liquid level measurement under unstable working conditions, it is necessary to develop corresponding liquid level detection methods and equipment specifically to meet the measurement requirements more economically.

[0044] It can be understood that the so-called "using a sledgehammer to crack a nut" and uneconomical here mean: First, in the field of cryogenic environments, the resolution requirement for liquid level detection is not high, that is, the necessity of continuous measurement is not strong. Second, compared with conventional continuous liquid level measurement devices, continuous measurement devices working in extremely low-temperature environments need to be able to withstand the low-temperature test, and the performance requirements in all aspects need to be strengthened, and the input cost will increase relatively. In addition, cryogenic medium storage and application equipment generally requires a thermal insulation layer to maintain the cryogenic environment, and some are even buried underground. When the structure and application scenarios are complex, it will involve the connection and layout of complex measurement pipelines, resulting in the installation cost of conventional liquid level measurement devices exceeding the instrument itself, and both the operability and economy are poor.

[0045] Generally speaking, the liquid-phase heat capacity of the same medium is much higher than the gas-phase heat capacity. When receiving the same amount of heat, the feedback speed of the gas-phase temperature change is much faster, and the amplitude is also relatively significant. When phase transformation is involved, the difference in the temperature change of the gas-liquid phases due to heating is even more significant. For the gas-liquid two phases in equilibrium in a closed system, when heated equally, the temperature rise of the liquid phase is much smaller than that of the gas phase; for the medium in an open system, the heat absorption of the liquid phase is often accompanied by liquid-gas phase transformation, which in principle does not cause any temperature change, while the heat absorption and temperature rise of the gas phase are relatively significant.

[0046] In view of this, on the one hand, an embodiment of the present application discloses a detection device for the liquid level of a container. Please refer to Figure 1 , which includes a heater 11 and a temperature sensor 12. The heater 11 is arranged at a preset monitoring position 21 in the container 2 for heating the medium 22 at the preset monitoring position 21; the temperature sensor 12 is arranged at the preset monitoring position 21 in the container 2 for detecting the temperature change of the medium 22 at the preset monitoring position 21 to judge the liquid level at the preset monitoring position 21. For example, the temperature sensor 12 can be fixed on the surface of the heater 11 to form the basic hardware for discrete liquid level detection, and it can directly display the temperature on the surface of the heater 11.

[0047] It can be understood that the temperature sensor 12 being fixed on the surface of the heater 11 here means that the relative positions of the two are relatively close and cannot be too far apart. That is to say, as long as they can be kept fixed, there can be a small distance between the temperature sensor 12 and the heater 11. Therefore, the temperature measured by the temperature sensor 12 does not need to be the true temperature of the heater 11, nor the true temperature of the medium 22 to be measured, but the temperature change between the two before and after heating. However, this does not affect the detection result. For example, after applying a certain power to the heater 11, if the medium 22 to be measured is in the gas phase, the temperature measured by the temperature sensor 12 rises sharply and the change is significant; if the medium 22 to be measured is in the liquid phase, the temperature measured by the temperature sensor 12 is stable and the change is not significant, so as to judge the location of the liquid level in the container 2.

[0048] In the embodiment of the present application, by arranging the heater 11 at the monitoring position 21, heating the medium 22 at the monitoring position 21, and using the temperature sensor 12 to detect the temperature change of the medium 22 at the monitoring position 21 to judge the liquid level at the monitoring position 21, the structure is simple, the monitoring cost is low, and the economy is good.

[0049] In one embodiment, the detection device 1 further includes a sleeve 13. The sleeve 13 is arranged in the container 2, and both the heater 11 and the temperature sensor 12 are arranged in the sleeve 13, which is convenient for fixing the heater 11 and the temperature sensor 12 at the monitoring position 21, making the liquid level detection more accurate.

[0050] It can be understood that using the sleeve 13 to load the heater 11 and the temperature sensor 12 can provide better support for the heater 11 and the temperature sensor 12 at the monitoring position 21 in the container 2.

[0051] It can be understood that there is a large difference in size between the sleeve 13 and the container 2 to be measured. When the sleeve 13 is located inside the container 2, the influence of the volume of the sleeve 13 on the rise of the liquid level in the container 2 can be ignored. Figure 1 The structure shown is only schematic and should not be understood as defining the size relationship between the sleeve 13 and the container 2 in terms of this ratio.

[0052] In one embodiment, please refer to Figure 1 , the number of sleeves 13 is one, and multiple pairs of heaters 11 and temperature sensors 12 are arranged at intervals inside the sleeve 13. The connection terminals of each pair of heaters 11 and temperature sensors 12 are uniformly led out from the outlet of the sleeve 13 to monitor the liquid levels at different preset monitoring positions 21. For example, when the liquid level path is short and the monitoring positions 21 are relatively dense, multiple pairs of heaters 11 and temperature sensors 12 can be arranged in one sleeve 13, and the connection terminals of each pair of heaters 11 and temperature sensors 12 can be led out from one interface inside the sleeve 13, which can reduce the length of the wires and is relatively convenient to arrange.

[0053] It can be understood that the liquid level path refers to the height of the possible liquid level positions in the container 2.

[0054] It can be understood that the sleeve 13 is a pipe with good insulation, flame retardancy, and heat conductivity, which can ensure that the applied electric heating power is effectively transmitted to the medium 22 in the container 2, and can also quickly transmit the temperature near the monitoring position 21 in the container 2 back for measurement by the temperature sensor 12.

[0055] In one embodiment, please refer to Figure 2 , the number of sleeves 13 is multiple, and one pair of heater 11 and temperature sensor 12 is arranged inside each sleeve 13 to monitor the liquid levels at different preset monitoring positions 21. For example, when the liquid level path is long and the monitoring positions 21 are relatively sparse, multiple horizontal sleeves 13 can be arranged on the inner wall of the container 2, and one pair of heater 11 and temperature sensor 12 is separately encapsulated inside each sleeve 13.

[0056] It can be understood that when the liquid level path is long and the monitoring positions 12 are sparse, if a single sleeve 13 is used, it will cause the sleeve 13 to be set very long, and the distance between each pair of heaters 11 and temperature sensors 12 will be large, resulting in an increase in the length of the wires between them and an increase in cost; and the overly long sleeve 13 may involve fixing problems. The reason for arranging the horizontal sleeves 13 on the inner wall is that there may be other devices in the container 2, and it cannot be avoided when installed vertically.

[0057] It can be understood that the installation method of the sleeve 13 is not limited to horizontal installation. It can also be installed vertically at the bottom of the container 2 or at a certain angle with the inner wall of the container 2. In short, as long as the heater 11 and the temperature sensor 12 in the sleeve 13 are in the monitoring position 12.

[0058] In one embodiment, the detection device 1 further includes a filler, which is arranged in the sleeve 13 to fill the sleeve 13, the heater 11 and the temperature sensor 12 for heat insulation and heat conduction. For example, the filler can fill the gaps between the heater 11 and the temperature sensor 12, between a pair of heaters 11 and temperature sensors 12 and another pair of heaters 11 and temperature sensors 12, and between the heater 11 and the temperature sensor 12 and the sleeve 13 for insulation, flame retardancy and heat conduction to prevent the instrument and equipment from being burned out. It can also fill the remaining space in the sleeve 13 to better fix the heater 11 and the temperature sensor 12 and prevent them from falling off from the sleeve 13.

[0059] Another aspect of the embodiment of the present application provides a method for detecting the liquid level of a container, using the detection device 1 described above. Please refer to Figure 3 , and the detection method includes:

[0060] S1. Place the detection device 1 into the container 2 to be measured;

[0061] S2. Determine the data acquisition requirements for the detection device 1 to detect the liquid level of the container 2;

[0062] S3. Apply an electric heating power to the heater 11 at the preset monitoring position 21;

[0063] S4. Obtain the temperature change measured by the temperature sensor 12 at the preset monitoring position 21;

[0064] S5. Judge the position of the liquid-phase medium 22 according to the temperature change situation at the preset monitoring position 21.

[0065] It should be noted that the method for detecting the liquid level of the container disclosed in the embodiment of the present application has more advantages in some scenarios where both liquid level detection and heating are required. For example, in some types of reboilers of distillation columns, when a certain product liquid level is required, the liquid-phase product needs to be heated to generate a pressure driving force for discharging. The heating amount of the heater 11 located in the product of the reboiler can heat the liquid phase to the gas phase while assisting in detecting the liquid level, serving as the pressure-increasing driving force for discharging.

[0066] In this embodiment, the detection device 1 is placed into the container 2 to be measured, then the data acquisition requirements for the detection device 1 to detect the liquid level of the container 2 are determined, an electric heating power is applied to the heater 11 at the preset monitoring position 21, the temperature change measured by the temperature sensor 12 at the preset monitoring position 21 is acquired, and the position of the liquid-phase medium 22 is judged according to the temperature change condition at the preset monitoring position 21. The operation is simple, the detection cost is low, and the economy is good.

[0067] In one embodiment, before the above S1 step, the detection method further includes:

[0068] S01. Determine the spatial size of the container 2 and the number of preset monitoring positions 21;

[0069] S02. Select a suitable heater 11 and temperature sensor 12 according to the spatial size of the container 2 and the properties of the medium 22 to be monitored;

[0070] S03. Determine the layout mode of the detection device 1 according to the number of monitoring positions 21.

[0071] For example, the power range, material and size of the heater 11 and the temperature range and form measured by the temperature sensor 12 can be comprehensively determined according to the spatial size of the container 2 and the properties of the monitoring medium 22.

[0072] In one embodiment, the above S2 step: determining the data acquisition requirements for the detection device 1 to detect the liquid level of the container 2 includes:

[0073] S21. For those with high requirements for the liquid level data of the container 2, a synchronous heating and synchronous detection method for all preset monitoring positions 21 is adopted;

[0074] S21'. For those with low requirements for the liquid level data of the container 2, an asynchronous heating and asynchronous detection method for all preset monitoring positions 21 is adopted.

[0075] It can be understood that the high and low requirements for the liquid level data of the container 2 mentioned here refer to the liquid level data refresh rate and the strictness of the data synchronization requirement. For those with a higher liquid level data refresh rate and a strict data synchronization requirement, the synchronous heating and synchronous detection method is adopted, so that the temperature feedback and liquid level information of all monitoring positions 21 can be obtained synchronously. For those with a low liquid level data refresh rate and a low strictness of the data synchronization requirement, the asynchronous heating and asynchronous detection method can be adopted, and the temperature feedback and liquid level information of each monitoring position 21 can be obtained in sequence according to the monitoring order.

[0076] In one embodiment, the asynchronous heating and asynchronous detection method in the above S21' step includes:

[0077] S21'1. Heat and detect the temperature change at each site of the monitoring position 21 in a preset direction;

[0078] After determining the liquid level state of the upper position point, based on the liquid level detection result, clarify the necessity of liquid level detection at the lower position point;

[0079] If the liquid level position can be clearly determined after detecting the upper position point, stop the subsequent position point detection and heating actions, and only retain the heating states of the upper and lower two position points where the liquid level is located for reference in indicating liquid level changes.

[0080] For example, the monitoring positions 21 can be n. They are sequentially marked as 1, 2, 3, …, n from bottom to top according to the monitoring order. Then, a pair of heaters 11 and temperature sensors 12 are respectively arranged at each monitoring position 21. Electric heating power is sequentially applied to the heaters 11 in the vertical direction from bottom to top until a significant temperature change occurs at the x-th monitoring position 21. Then, the liquid level of the monitoring medium 22 is between the x-th monitoring position 21 and the (x - 1)-th monitoring position 21.

[0081] Similarly, in the above embodiment, they can be sequentially marked as 1, 2, 3, …, n from top to bottom according to the monitoring order. Then, a pair of heaters 11 and temperature sensors 12 are respectively arranged at each monitoring position 21. Electric heating power is sequentially applied to the heaters 11 in the vertical direction from top to bottom until the temperature change at the x-th monitoring position 21 is not obvious. Then, the liquid level of the monitoring medium 22 is between the x-th monitoring position 21 and the (x - 1)-th monitoring position 21.

[0082] The asynchronous heating and asynchronous detection method adopted in this embodiment, which uses sequential heating and sequential detection, can accurately obtain the position where the liquid level is located. After obtaining the liquid level position, the subsequent heating actions can be stopped, greatly reducing the overall energy consumption and improving the economy.

[0083] In an embodiment, for the step of applying electric heating power to the heater 11 at the preset monitoring position 21, the electric heating power is configured as:

[0084] After applying the electric heating power, the temperature change of the detection device 1 at the liquid phase medium 22 is within the preset range, and the temperature change of the detection device 1 at the gas phase medium 22 is outside the preset range.

[0085] It can be understood that the preset range refers to the temperature change interval before and after the medium 22 absorbs heat. For example, after heating with the electric heating power, if the detection site is the gas phase medium, an obvious temperature change occurs, and the temperature change exceeds the preset range. If it is the liquid phase medium, the temperature change is within the preset range without causing local boiling of the liquid.

[0086] In the embodiment of the present application, by applying electric power through the heater 11, the interference of liquid level oscillation on the detection result can be significantly weakened, the validity of measurement data can be improved, and by detecting the temperature change of the medium 22, it has strong adaptability to the medium 22, the detection range is not limited, and it is convenient for on-site and remote display and control, which is efficient and convenient.

[0087] An exemplary description will be given below for a method for detecting the liquid level of a container 2 provided in the embodiment of the present application. Please refer to Figure 4 ;

[0088] S01. Determine the spatial dimensions of the container 2 and the number of preset monitoring positions 21;

[0089] S02. Select a suitable heater 11 and temperature sensor 12 according to the spatial dimensions of the container 2 and the properties of the medium 22 to be monitored;

[0090] S03. Determine the arrangement mode of the detection device 1 according to the number of the monitoring positions 21;

[0091] S1. Place the detection device 1 into the container 2 to be measured;

[0092] S2. Determine the data acquisition requirements for the detection device 1 to detect the liquid level of the container 2;

[0093] S3. Apply electric heating power to the heaters 11 at the preset monitoring positions 21;

[0094] S4. Obtain the temperature changes measured by the temperature sensors 12 at the preset monitoring positions 21;

[0095] S5. Judge the position of the liquid-phase medium 22 according to the temperature change conditions at the preset monitoring positions 21.

[0096] For example, taking the detection of the dynamic liquid level of liquid nitrogen in an 80K / 10bar large-scale cryogenic container as an example. The liquid nitrogen in the container is in a state of continuous vaporization and outflow, and it is required that the pressure of the outflowing nitrogen gas is constant. The detection requirement is simple three-point liquid level monitoring, and the monitoring sites are located at the upper, middle, and lower positions of the cryogenic container 2 respectively. The detection data is used as a quantitative indication of the liquid nitrogen in the container 2, mainly used as an indication signal for liquid nitrogen replenishment, and is associated with the opening / closing actions of relevant valves to ensure that the liquid nitrogen in the container 2 is at a reasonable liquid level. The upper and lower liquid level actions can accept a delay time of up to a few minutes.

[0097] Since the liquid nitrogen is in a phase equilibrium state under constant pressure, therefore, heating the liquid phase until it vaporizes to replenish the gas phase will not cause any temperature change in principle. At a temperature of 80K / 10.0bar, the heat capacity of gaseous nitrogen Gas-phase density According to the heat capacity and density of nitrogen, a resistance wire with a heating power of hundreds of watts is selected as the heater 11, and a thermal resistance type temperature sensor is used as the temperature sensor 12.

[0098] The thermal resistance temperature sensor is fixed at a suitable position on the surface of the middle part of the axial direction of the heating resistance wire. For convenient arrangement, the assembled thermal resistance temperature sensor and the heating resistance wire are placed in a rigid sleeve 13. The gap between the sleeve 13 and the thermal resistance temperature sensor and the heating resistance wire is filled with a powder with good insulation, flame retardancy, and heat conductivity as a filler to ensure that the applied electric heating power can be effectively transferred to the medium 22 in the container.

[0099] According to the liquid level data refresh rate and the strictness of data synchronization requirements, an asynchronous heating and asynchronous detection method is adopted for the production and arrangement of the detection device 1.

[0100] According to the three monitoring positions 21, the arrangement spacing of each pair of thermal resistance temperature sensors and heating resistance wires is determined. Based on this, the three pairs of thermal resistance temperature sensors and heating resistance wires are arranged in segments in the same sleeve 13. After the gap is filled and fixed with the filler, the wiring ends of the resistance wire and the thermal resistance are uniformly connected and led out from the top of the container 2. The electric heating powers and temperature signals corresponding to the upper, middle, and lower three positions are H3 / T3, H2 / T2, and H1 / T1 respectively.

[0101] From bottom to top, a constant electric heating power is continuously applied to the heating resistance wire of the detection device 1. The principle of applying the electric heating power: it is sufficient to cause an obvious temperature change at the monitoring position 21 in nitrogen without causing local boiling of the liquid nitrogen. Based on the heat capacity and density data of the liquid / gaseous nitrogen, the applied electric heating power is determined to be 100W.

[0102] (1) Apply a constant electric heating power H1 = 100W to the heater 11 located at the bottom of the container 2, and detect the change in the corresponding temperature signal T1. If T1 does not change significantly, then this place is in the liquid phase and the liquid nitrogen level is above it; if T1 rises significantly, then this place is in the gas phase and the liquid nitrogen level is below it.

[0103] (2) If T1 does not change significantly, then apply a constant electric heating power H2 = 100W to the heater 11 located in the middle of the container 2, and detect the change in the corresponding temperature signal T2. If T2 does not change significantly, then this place is in the liquid phase and the liquid nitrogen level is above it; if T2 rises significantly, then this place is in the gas phase and the liquid nitrogen level is below it.

[0104] (3) If T2 does not change significantly, then apply a constant electric heating power H3 = 100W to the heater 11 located at the upper part of the container 2, and monitor the change in the corresponding temperature signal T3. If T3 does not change significantly, then this place is in the liquid phase and the liquid nitrogen level is above it; if T3 rises significantly, then this place is in the gas phase and the liquid nitrogen level is below it.

[0105] From (1), (2), and (3), the state of the medium 22 at the upper, middle, and lower three liquid level monitoring positions 21 can be determined, and then the approximate position of the liquid level in the container 2 can be determined. By comparing the detected temperature values, the mutation point of the temperature is the interval where the liquid level of the medium 22 in the container 2 is located.

[0106] As described above, it is only the preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application are all included in the protection scope of the present application.

Claims

1. A detection device for the liquid level of a container, characterized in that, Including: A heater, arranged at a preset monitoring position inside the container, for heating the medium at the preset monitoring position; Put the detection device into the container to be measured, and determine the data requirements for the detection device to detect the container. Among them, the liquid level data requirements of the container refer to the liquid level data refresh rate and the strictness of the data synchronization requirements. For those with high requirements for the liquid level data refresh rate and data synchronization of the container, a synchronous heating and synchronous detection method is adopted. For those with low requirements for the liquid level data refresh rate and data synchronization of the container, an asynchronous heating and asynchronous detection method is adopted; A temperature sensor, arranged at the preset monitoring position inside the container, for detecting the temperature change of the medium at the preset monitoring position to judge the liquid level at the preset monitoring position.

2. The detection device according to claim 1, wherein, The detection device further includes: A sleeve, arranged inside the container, and both the heater and the temperature sensor are arranged inside the sleeve.

3. The detection device according to claim 2, characterized in that, The number of the sleeves is one, and multiple pairs of the heaters and the temperature sensors are arranged at intervals inside the sleeve. The wiring terminals of each pair of the heaters and the temperature sensors are uniformly led out from the sleeve outlet to monitor the liquid levels at different preset monitoring positions; or, The number of the sleeves is multiple, and one pair of the heater and the temperature sensor is arranged inside each sleeve to monitor the liquid levels at different preset monitoring positions.

4. The detection device according to claim 2 or 3, characterized in that, The detection device further includes: A filler, arranged inside the sleeve to fill the gaps between the sleeve, the heater and the temperature sensor, for insulation and heat conduction.

5. A method for detecting the liquid level of a container, characterized in that, Using the detection device according to any one of claims 1 to 4, the detection method includes: Put the detection device into the container to be measured; Determine the data acquisition requirements for the detection device to detect the liquid level of the container; Apply electric power to the heater at the preset monitoring position; Obtain the temperature change measured by the temperature sensor at the preset monitoring position; Judge the position of the liquid phase medium according to the temperature change situation at the preset monitoring position; Among them, the determination of the data acquisition requirements for the detection device to detect the liquid level of the container includes: For those with high requirements for the liquid level data of the container, a synchronous heating and synchronous detection method for all preset monitoring positions is adopted; For those with low requirements for the liquid level data of the container, an asynchronous heating and asynchronous detection method for all preset monitoring positions is adopted.

6. The detection method according to claim 5, wherein Before the step of putting the detection device into the container to be measured, the detection method further includes: Determine the space size of the container and the number of the preset monitoring positions; Select a suitable heater and temperature sensor according to the space size of the container and the properties of the medium to be monitored; Determine the layout mode of the detection device according to the number of the monitoring positions.

7. The detection method according to claim 5, characterized in that, The asynchronous heating and asynchronous detection method includes: Heating and detecting the temperature change at each site of the monitoring position in a preset direction; After determining the liquid level state of the upper site, according to its liquid level detection result, clarify the necessity of detecting the liquid level of the lower site; If the liquid level position can be clearly determined after the upper position is detected, stop the subsequent position detection heating operation, and only retain the heating states of the positions on both sides where the liquid level is located for reference of liquid level change indication.

8. The detection method according to claim 5, characterized in that, The step of applying electric heating power to the heater at the preset monitoring position, the electric heating power being configured as: After applying the electric heating power, the temperature change of the detection device at the liquid phase medium is within a preset range, and the temperature change of the detection device at the gas phase medium is outside the preset range.

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