Vacuum tube temperature differential level gauge

Abstract

The present invention belongs to the technical field of liquid level gauges, and in particular relates to a vacuum tube type differential temperature liquid level gauge, comprising a vacuum tube and a plurality of temperature sensors; when in use, the end of the vacuum tube located in a cryogenic liquid is the lower end, and the end located outside the cryogenic liquid is the upper end; the vacuum tube is a vacuum heat-insulating tube, and the interior of the vacuum tube is a vacuum sealed space; a plurality of heat-conducting layers are sequentially embedded in the tube wall of the vacuum tube from bottom to top, and a plurality of temperature sensors are arranged in the vacuum sealed space, each of the temperature sensors is arranged corresponding to a heat-conducting layer, and the detection end of the temperature sensor is connected to the heat-conducting layer, the temperature sensor is not immersed in the cryogenic liquid, and the interference of the natural convection and transient changes of the cryogenic liquid on the temperature sensor is reduced; at the same time, the vacuum environment in the vacuum sealed space reduces the interference between the plurality of temperature sensors in the vacuum tube, so that the temperature sensor can measure accurately, and at the same time, the service life of the temperature sensor is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid level gauges, and in particular relates to a vacuum tube type temperature differential liquid level gauge. Background Art

[0002] Cryogenic liquid level sensors are used to measure the liquid level of cryogenic liquids such as liquid nitrogen. They play an important role in cryogenic testing and are essential instruments to ensure the normal progress of scientific research experiments and industrial production processes.

[0003] At present, there are many methods for measuring the liquid level of cryogenic liquids, including thermal oscillation method, superconducting wire method, resistance method, diode method and capacitance method, etc. All of the above methods use the difference in the conductive or thermal conductivity or resistance and capacitance characteristics inside and outside the cryogenic liquid to achieve the purpose of judging the liquid level height. The defect is that: since the difference in the above characteristics on both sides of the liquid critical surface is limited, no matter how the sensor itself is changed, it is difficult to make a greater breakthrough in the measurement accuracy of the liquid level side. In order to solve the above defects, a Chinese patent discloses a low-temperature liquid level sensor assembly with application number CN201120352180.1. When in use, one end of the sensor assembly is located in the low-temperature liquid and the other end is located outside the low-temperature liquid. The sensor assembly includes a support rod, several temperature sensors and several signal transmission lines. When the sensor assembly is in use, the end of the support rod located in the low-temperature liquid is the lower end, and the end located outside the low-temperature liquid is the upper end. The temperature sensors are distributed on the outer surface of the support rod from bottom to top. The signal output end of the temperature sensor is connected to one end of the signal transmission line in a one-to-one correspondence, and the other end of the signal transmission line is led out from bottom to top along the support rod. The temperature sensor is connected to the central processor through the signal transmission line. The temperature difference signal of whether the liquid is immersed or not is transmitted to the central processor through the signal transmission line. The central processor can very accurately judge the height of the liquid level according to the position of the temperature sensor. The temperature difference that must exist in the gas and liquid states of the low-temperature liquid medium is used to judge the liquid level, so its error is quite small and the accuracy is very high. It is a great progress in the field of low-temperature liquid level measurement. However, a disclosed cryogenic liquid level sensor assembly has the following defects: the temperature sensors are sequentially distributed on the outer surface of the support rod from bottom to top, and when in use, the temperature sensor and the signal transmission line are always completely immersed in the cryogenic liquid. The natural convection of the cryogenic liquid and the influence of the cryogenic liquid on the temperature sensor through the signal transmission line will affect the measurement accuracy of the temperature sensor. In addition, since the temperature of cryogenic liquids such as liquid nitrogen is extremely low, long-term immersion in cryogenic liquids can easily cause damage to the temperature sensor and its accessories. Summary of the invention

[0004] The object of the present invention is to provide a vacuum tube type differential temperature liquid level gauge, which aims to solve the problem of low measurement accuracy caused by the natural convection of the cryogenic liquid and the influence of the cryogenic liquid on the temperature sensor through the signal transmission line when the cryogenic liquid level sensor assembly is in use in the prior art, and the technical problem that the temperature sensor and the signal transmission line are always completely immersed in the cryogenic liquid, and the temperature sensor is easily damaged due to the extremely low temperature of the cryogenic liquid such as liquid nitrogen, and long-term immersion in the cryogenic liquid can easily cause damage to the temperature sensor and the attached parts.

[0005] To achieve the above-mentioned purpose, an embodiment of the present invention provides a vacuum tube type temperature differential level gauge, comprising a vacuum tube and multiple temperature sensors; when in use, the end of the vacuum tube located in the cryogenic liquid is the lower end, and the end located outside the cryogenic liquid is the upper end; the vacuum tube is a vacuum insulation tube, and the interior of the vacuum tube is a vacuum sealed space; the tube wall of the vacuum tube is sequentially embedded with multiple heat-conducting layers from bottom to top, and multiple temperature sensors are arranged in the vacuum sealed space, each temperature sensor is arranged corresponding to one heat-conducting layer, and the detection end of the temperature sensor is connected to the heat-conducting layer.

[0006] Optionally, a data interface is provided on the top of the vacuum tube, and each of the temperature sensors is electrically connected to the data interface via a signal transmission line.

[0007] Optionally, a vacuum extraction interface is further provided on the top of the vacuum tube at one side of the data interface.

[0008] Optionally, two adjacent heat-conducting layers are embedded in the vacuum tube with a staggered spacing.

[0009] Optionally, the vacuum tube includes a left tube and a right tube; the left tube and the right tube are sealed and connected to form the vacuum tube.

[0010] Optionally, a plurality of the heat-conducting layers are sequentially and spaced apart and embedded in the tube wall of the left tube or the right tube from bottom to top.

[0011] Optionally, a plurality of the heat-conducting layers are sequentially and spaced apart from each other on the tube walls of the left tube and the right tube from bottom to top, and the heat-conducting layers on the left tube are symmetrically arranged with the heat-conducting layers on the right tube.

[0012] Optionally, a groove is dug at one end of the heat-conducting layer in the vacuum sealed space, and the detection end of the temperature sensor is adapted to be plugged into the groove.

[0013] Optionally, the longitudinal distance between two adjacent heat-conducting layers is 0 mm to 15 mm.

[0014] Optionally, a bottle mouth sealing member is also provided at the upper end of the vacuum tube.

[0015] Compared with the prior art, the vacuum tube type temperature differential level gauge provided by the present invention has one of the following technical effects: when in use, the vacuum tube is vertically extended into the cryogenic liquid, and the plurality of temperature sensors are electrically connected to the display instrument through a transmission line, so that each temperature sensor detects the temperature at its location and transmits it to the display instrument. The interior of the vacuum tube of the present invention is a vacuum sealed space, and the cryogenic liquid cannot enter the vacuum sealed space. The temperature sensor is arranged in the vacuum sealed space, and the detection end of the temperature sensor is connected to the heat conductive layer. When working, the heat conductive layer located in the cryogenic liquid transfers the temperature at its location to the corresponding temperature sensor, and the heat conductive layer located outside the cryogenic liquid also transfers the temperature at its location to the corresponding temperature sensor. The temperature sensor is not immersed in the cryogenic liquid, which reduces the interference of the natural convection and transient changes of the cryogenic liquid on the temperature sensor. At the same time, the interior of the vacuum tube is a vacuum sealed space, and the vacuum sealed space reduces the interference between the plurality of temperature sensors in the vacuum tube, so that the temperature sensor measures accurately and improves the service life of the temperature sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 The figure is a schematic diagram of the structure of a vacuum tube type temperature differential level gauge according to the first embodiment of the present invention.

[0018] Figure 2 For the present invention Figure 1 A cutaway view of the .

[0019] Figure 3 It is a cross-sectional view of the exploded state of the left tube and the right tube of the first embodiment of the present invention.

[0020] Figure 4 For the present invention Figure 3 Enlarged view of point A in the middle.

[0021] Figure 5 It is a cross-sectional view of the exploded state of the left tube and the right tube of the second embodiment of the present invention.

[0022] Figure 6 This is a schematic diagram of the structure of a vacuum tube type temperature differential level gauge according to the third embodiment of the present invention.

[0023] Among them, the reference numerals in the figure are:

[0024] Vacuum tube 100 , vacuum sealing space 101 , left tube 102 , right tube 103 , heat conductive layer 110 , data interface 120 , vacuum extraction interface 130 , bottle mouth sealing member 140 , temperature sensor 200 , detection end 210 , signal transmission line 220 . DETAILED DESCRIPTION

[0025] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

[0026] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0027] In the description of the embodiments of the present invention, “plurality” means two or more than two, unless otherwise clearly and specifically defined.

[0028] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0029] In one embodiment of the present invention, referring to Figure 1 and Figure 2 , provides a vacuum tube type temperature differential level gauge, comprising a vacuum tube 100 and a plurality of temperature sensors 200. When in use, the end of the vacuum tube 100 located in the cryogenic liquid is the lower end, and the end located outside the cryogenic liquid is the upper end.

[0030] Reference Figure 2 The vacuum tube 100 is a vacuum insulated tube, and the interior of the vacuum tube 100 is a vacuum sealed space 101, and the vacuum sealed space 101 is isolated from the outside. Figure 1 and Figure 6The tube wall of the vacuum tube 100 is uniformly embedded with a plurality of heat-conducting layers 110 from bottom to top. The material of the heat-conducting layer 110 can be graphene, heat-conducting silicone grease, heat-conducting silica gel and other heat-conducting materials. The heat-conducting layer 110 can be formed on the tube wall of the vacuum tube 100 by an injection molding method.

[0031] Reference Figure 2 , Figure 3 and Figure 4 A plurality of temperature sensors 200 are disposed in the vacuum sealed space 101, each temperature sensor 200 is disposed corresponding to one of the heat-conducting layers 110, and a detection end of the temperature sensor 200 is connected to the heat-conducting layer 110, so that the detection end 210 of the temperature sensor 200 can detect the temperature of the location of the heat-conducting layer 110 through the heat-conducting layer 110.

[0032] When the vacuum tube type temperature differential level gauge is used, the vacuum tube 100 is vertically extended into the cryogenic liquid, and the plurality of temperature sensors 200 are electrically connected to a display instrument (not shown) through a transmission line (not shown in the figure), so that each temperature sensor 200 detects the temperature at its location and transmits it to the display instrument. According to the temperature mutation at the critical surface of the cryogenic liquid medium in the gas and liquid states, that is, there is an obvious temperature difference at the critical surface of the cryogenic liquid medium in the gas and liquid states, therefore, the present invention uses the temperature fed back by each temperature sensor 200 to obtain the obvious temperature difference between two adjacent temperature sensors 200 in a group to judge the liquid level position of the cryogenic liquid, with small error and high precision.

[0033] Compared with the prior art, Figure 2 , Figure 3 and Figure 4 The interior of the vacuum tube 100 of the present invention is a vacuum sealed space 101, and cryogenic liquid cannot enter the vacuum sealed space 101. The temperature sensor 200 is arranged in the vacuum sealed space 101, and the detection end 210 of the temperature sensor 200 is connected to the heat conductive layer 110. When working, the heat conductive layer 110 located in the cryogenic liquid transfers the temperature of its position to the corresponding temperature sensor 200, and the heat conductive layer 110 located outside the cryogenic liquid also transfers the temperature of its position to the corresponding temperature sensor 200. The temperature sensor 200 and the signal transmission line 220 are not immersed in the cryogenic liquid, which reduces the interference of the natural convection and transient changes of the cryogenic liquid on the temperature sensor 200 and the signal transmission line 220. At the same time, the interior of the vacuum tube 100 is a vacuum sealed space 101. The vacuum environment in the vacuum sealed space 101 reduces the interference between the multiple temperature sensors 200 in the vacuum tube 100, so that the temperature sensor 200 can measure accurately and improve the service life of the temperature sensor 200.

[0034] Reference Figure 2 and Figure 3 The top of the vacuum tube 100 is provided with a data interface 120, and each of the temperature sensors 200 is electrically connected to the data interface 120 through a signal transmission line 220. The signal transmission line 220 and the temperature sensor 200 are both housed in the vacuum sealed space 101 of the vacuum tube 100, making the structure of the vacuum tube type temperature differential level gauge compact and simple. The signal transmission line 220 is arranged in the vacuum tube 100 and is not interfered by the cryogenic liquid, thus avoiding the signal transmission line 220 from contacting the medium (such as cryogenic liquefied gas) and affecting the temperature sensor 200. The data interface 120 is electrically connected to the display instrument through a transmission line to realize data transmission.

[0035] Reference Figure 2 and Figure 3 A vacuum interface 130 is also provided at the top of the vacuum tube 100 on one side of the data interface 120 , and the vacuum sealed space 101 can be evacuated through the vacuum interface 130 .

[0036] In another embodiment of the present invention, referring to Figure 2 , Figure 3 and Figure 4 The vacuum tube 100 of the vacuum tube type differential temperature level gauge includes a left tube 102 and a right tube 103. The left tube 102 and the right tube 103 are sealed and connected to form the vacuum tube 100, wherein the left tube 102 and the right tube 103 are sealed and connected by bonding or welding. The vacuum tube 100 is configured as a structure of two halves, the left tube 103 and the right tube 103, which facilitates the connection of the detection end 210 of the temperature sensor 200 with the heat conductive layer 110, and also facilitates the fixed installation of the temperature sensor 200 in the vacuum sealed space 101 of the vacuum tube 100. First, the temperature sensor 200 is fixedly installed on the inner wall of the left tube 102 or the right tube 103, and then the left tube 102 is sealed and connected to the right tube 103.

[0037] The plurality of heat-conducting layers 110 are sequentially and spaced from bottom to top and embedded in the tube wall of the left tube 102 or the right tube 103 . Correspondingly, the temperature sensor 200 is installed on the inner wall of the left tube 102 or the right tube 103 , and the structure is compact.

[0038] In another embodiment of the present invention, referring to Figure 5The tube walls of the left tube 102 and the right tube 103 of the vacuum tube type differential temperature level gauge are sequentially embedded with a plurality of the heat-conducting layers 110 from bottom to top, and the heat-conducting layers 110 on the left tube 102 and the heat-conducting layers 110 on the right tube 103 are symmetrically arranged. Correspondingly, the temperature sensors 200 are symmetrically installed on the inner wall of the left tube 102 or the right tube 103. The temperature sensors 200 on the left tube 102 and the right tube 103 can work simultaneously, so that the temperature difference value of two adjacent temperature sensors of a group of temperature sensors 200 on the left tube 102 and the temperature difference value of two adjacent temperature sensors of a group of temperature sensors 200 on the right tube 103 can be output separately, and the measurement accuracy is higher by referring to the two groups of values.

[0039] Reference Figure 2 and Figure 4 , a groove (not shown) is dug at one end of the heat-conducting layer 110 in the vacuum sealed space 101, and the detection end 210 of the temperature sensor 200 is adapted to be plugged into the groove, wherein the groove is a very shallow groove, mainly for positioning and installing the temperature sensor 200. The height of the heat-conducting layer 110 is slightly greater than the height of the detection end 210 of the temperature sensor 200. Specifically, the detection end of the temperature sensor 200 is plugged into the groove, and then the detection end 210 of the temperature sensor 200 is connected to the heat-conducting layer 110 by adhesive bonding. The temperature sensor 200 can be fixed to the inner wall of the vacuum tube 100 by welding, bonding, screw connection, etc.

[0040] The longitudinal distance between two adjacent heat-conducting layers 110 is 0 mm to 15 mm. In the application, the value of the distance between two adjacent heat-conducting layers 110 is determined according to the actual measurement accuracy required or according to the different cryogenic liquids measured. The smaller the longitudinal distance between two adjacent heat-conducting layers 110 is, the less it is affected by environmental factors, the smaller the measurement error of the liquefied gas temperature differential level meter is, and the higher the measurement accuracy is.

[0041] In another embodiment of the present invention, referring to Figure 1 and Figure 6 , the tube wall of the vacuum tube 100 is sequentially embedded with multiple heat-conducting layers 110 from bottom to top, and two adjacent heat-conducting layers 110 are staggered and arranged in the vacuum tube 100, that is, the distance between the two adjacent heat-conducting layers 110 in the longitudinal direction of the vacuum tube 100 is 0 mm, and there is a gap between the two adjacent heat-conducting layers 110 in the radial direction of the vacuum tube 100, so as to avoid contact interference between the two adjacent heat-conducting layers 110. At this time, the longitudinal distance between the two adjacent heat-conducting layers 110 can be set to 0 mm, and the measurement accuracy is higher.

[0042] Among them, the liquid level of the liquefied gas is in the interval between the two adjacent heat-conducting layers 110. When the liquid level of the liquefied gas is at different positions in the interval, the temperature difference values ​​between the two adjacent temperature sensors 200 will also be different. Therefore, the staff will collect the values ​​during the testing phase, that is, the interval is evenly divided into multiple points, and then the position of the liquid level of the liquefied gas is tested at each point respectively, and the temperature difference value distribution table between the two adjacent temperature sensors 200 corresponding to the positions of each point in the interval is obtained. Therefore, when the liquefied gas temperature differential level meter is used, the liquid level position of the liquefied gas can be accurately obtained according to the above-mentioned temperature difference value distribution table.

[0043] The temperature sensor 200 is a platinum resistance temperature sensor. The platinum resistance temperature sensor is a mature existing technology. The platinum resistance temperature sensor measures temperature by utilizing the property that the resistance value of metal platinum changes with temperature changes. The display instrument will indicate the temperature value corresponding to the resistance value of the platinum resistance. At the same time, the platinum resistance temperature sensor is the most accurate and stable temperature sensor, and its linearity is better than that of thermocouples and thermistors.

[0044] Reference Figure 1 and Figure 2 The upper end of the vacuum tube 100 is also provided with a bottle mouth seal 140, and the bottle mouth seal 140 is made of rubber or silicone, etc. The bottle mouth of the cryogenic liquid is blocked by the bottle mouth seal 140 to achieve bottle mouth sealing.

[0045] The rest of this embodiment is the same as the first embodiment. The features not explained in this embodiment are all based on the explanations in the first embodiment and will not be described in detail here.

[0046] The above content is a further detailed description of the present invention in combination with specific preferred implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, its architecture can be flexible and can derive a series of products. Just making a few simple deductions or substitutions should be regarded as belonging to the scope of patent protection of the present invention determined by the submitted claims.

Claims

1. Vacuum tube temperature differential level gauge, characterized in that: It comprises a vacuum tube and a plurality of temperature sensors; when in use, the end of the vacuum tube located in the cryogenic liquid is the lower end, and the end located outside the cryogenic liquid is the upper end; the vacuum tube is a vacuum insulated tube, and the interior of the vacuum tube is a vacuum sealed space; a plurality of heat-conducting layers are evenly embedded in the tube wall of the vacuum tube from bottom to top, a plurality of temperature sensors are arranged in the vacuum sealed space, each temperature sensor is arranged corresponding to a heat-conducting layer, and the detection end of the temperature sensor is connected to the heat-conducting layer; a groove is dug at one end of the heat-conducting layer in the vacuum sealed space, and the detection end of the temperature sensor is adapted to be plugged into the groove; the longitudinal distance between two adjacent heat-conducting layers is 0 mm to 15 mm.

2. The vacuum tube type temperature differential level gauge according to claim 1, characterized in that: A data interface is provided on the top of the vacuum tube, and each of the temperature sensors is electrically connected to the data interface via a signal transmission line.

3. The vacuum tube type temperature differential level gauge according to claim 2, characterized in that: The top of the vacuum tube is also provided with a vacuum extraction interface on one side of the data interface.

4. The vacuum tube type temperature differential level gauge according to claim 1, characterized in that: Two adjacent heat-conducting layers are mutually staggered and spaced and embedded in the vacuum tube.

5. The vacuum tube type temperature differential level gauge according to claim 1, characterized in that: The vacuum tube comprises a left tube and a right tube; the left tube and the right tube are sealed and connected to form the vacuum tube.

6. The vacuum tube type temperature differential level gauge according to claim 5, characterized in that: The plurality of heat-conducting layers are sequentially and spaced from bottom to top and embedded in the tube wall of the left tube or the right tube.

7. The vacuum tube type temperature differential level gauge according to claim 6, characterized in that: The tube walls of the left tube and the right tube are both sequentially and spaced apart from each other and embedded with a plurality of the heat-conducting layers from bottom to top, and the heat-conducting layers on the left tube are symmetrically arranged with the heat-conducting layers on the right tube.

8. The vacuum tube type temperature differential level gauge according to claim 1, characterized in that: The upper end of the vacuum tube is also provided with a bottle mouth sealing member.

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