Liquid nitrogen supplementing system and Dewar tank

Abstract

The invention relates to the technical field of Dewar tanks, in particular to a liquid nitrogen supplementing system and a Dewar tank. The liquid nitrogen supplementing system comprises a liquid nitrogen pipeline, and the two ends of the liquid nitrogen pipeline are connected with a liquid nitrogen tank and a Dewar tank liquid nitrogen bin respectively; the temperature sensor, the first exhaust pipeline and the liquid supplementing valve are sequentially arranged on the liquid nitrogen pipeline from the upstream to the downstream, and a bypass valve is arranged on the first exhaust pipeline; the differential pressure sensor is connected with a first connecting pipeline, and the first connecting pipeline is used for connecting the differential pressure sensor with the bottom of the Dewar tank liquid nitrogen bin; the exhaust valve is arranged on the second exhaust pipeline, and the second exhaust pipeline is used for being communicated with the top of the Dewar tank liquid nitrogen bin. According to the liquid nitrogen supplementing system, the liquid level height of liquid nitrogen in the liquid nitrogen bin can be accurately measured by controlling operation of all the valves, and therefore the adding amount of the liquid nitrogen is accurately controlled.

Description

Technical Field

[0001] The invention relates to the technical field of dewar tanks, and in particular to a liquid nitrogen replenishment system and a dewar tank. Background Art

[0002] A dewar is a device that uses liquid nitrogen as a cold source and is used to preserve biological samples at ultra-low temperatures. The ultra-low temperature maintenance of the dewar depends on the use of liquid nitrogen. If the amount of liquid nitrogen in the dewar is insufficient, the preservation temperature will be seriously affected. The temperature of liquid nitrogen is -196°C, and the ultra-low temperature environment makes most liquid level meters unsuitable. If the liquid nitrogen in the dewar is replenished regularly by estimating the loss rate of liquid nitrogen, there will be a large error.

[0003] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a liquid nitrogen replenishing system and a dewar tank, aiming to solve the technical problem in the prior art that the liquid nitrogen level in the liquid nitrogen tank of the dewar tank is difficult to accurately measure.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A first aspect of the present invention provides a liquid nitrogen replenishment system, comprising: a liquid nitrogen pipeline, wherein both ends of the liquid nitrogen pipeline are respectively connected to a liquid nitrogen tank and a dewar liquid nitrogen warehouse; a temperature sensor, a first exhaust pipeline and a liquid replenishment valve, wherein the temperature sensor, the first exhaust pipeline and the liquid replenishment valve are sequentially arranged on the liquid nitrogen pipeline from upstream to downstream, and a bypass valve is arranged on the first exhaust pipeline; a differential pressure sensor and a first connecting pipeline, wherein the first connecting pipeline is used to connect the differential pressure sensor to the bottom of the dewar liquid nitrogen warehouse; a second exhaust pipeline and an exhaust valve arranged on the second exhaust pipeline, wherein the second exhaust pipeline is used to communicate with the top of the dewar liquid nitrogen warehouse; and a control device, wherein the control device is electrically connected to the temperature sensor, the bypass valve, the liquid replenishment valve, the differential pressure sensor and the exhaust valve, respectively.

[0007] The liquid nitrogen replenishment system, wherein, further comprises: a first reversing valve, a purge pipeline and a second connecting pipeline; the first reversing valve comprises three interfaces, which are respectively connected to the purge pipeline, the first connecting pipeline and the second connecting pipeline; the first reversing valve is used to connect the second connecting pipeline with the first connecting pipeline or the purge pipeline; the first connecting pipeline is used to connect the first reversing valve with the pressure difference sensor; the second connecting pipeline is used to connect the first reversing valve with the bottom of the Dewar tank liquid nitrogen warehouse; the purge pipeline is used to connect the first reversing valve with the liquid nitrogen pipeline upstream of the liquid replenishing valve; the first reversing valve is electrically connected to the control device.

[0008] The liquid nitrogen replenishment system, wherein the blow-off pipeline is a capillary tube.

[0009] The liquid nitrogen replenishment system further includes: a second reversing valve and an air pipeline; the first connecting pipeline includes a first sub-pipeline and a second sub-pipeline; the second reversing valve includes three interfaces, which are respectively connected to the first sub-pipeline, the air pipeline and the second sub-pipeline; the second reversing valve is used to connect the first sub-pipeline with the air pipeline or the second sub-pipeline; the first sub-pipeline is used to connect the second reversing valve with the pressure differential sensor; the other end of the air pipeline is connected to the external environment; the second sub-pipeline is used to connect the first reversing valve with the second reversing valve; the second reversing valve is electrically connected to the control device.

[0010] In the liquid nitrogen replenishment system, the liquid nitrogen pipeline comprises an inner embedded section and an exposed section, the inner embedded section is arranged in the Dewar tank, and the exposed section is wrapped with a heat insulating material.

[0011] A second aspect of the present invention provides a Dewar tank, comprising a tank body, a liquid nitrogen tank and the liquid nitrogen replenishment system as described above.

[0012] The Dewar tank, wherein a sample chamber, a first heat insulation layer and a liquid nitrogen chamber are sequentially arranged in the tank body from top to bottom.

[0013] The Dewar tank, wherein a tank cover is arranged on the top of the tank body; a first cavity is formed between the tank cover and the sample chamber; and a second heat insulation layer is arranged on the side wall of the tank body.

[0014] The Dewar tank, wherein a third exhaust pipe is arranged in the second heat insulation layer, the lower end of the third exhaust pipe is connected to the top of the sample chamber, and the top end of the third exhaust pipe is connected to the first cavity above the sample chamber.

[0015] The Dewar tank, wherein a heat insulating material is arranged inside the tank cover.

[0016] Beneficial effects: The first aspect of the present invention provides a liquid nitrogen replenishment system, which detects the pressure difference between the dewar tank liquid nitrogen warehouse and the liquid nitrogen pipeline through a pressure difference sensor, and further converts the liquid level height corresponding to the dewar tank liquid nitrogen warehouse, and adopts an indirect measurement method to achieve accurate measurement of the liquid level height of the dewar tank liquid nitrogen warehouse. In addition, in order to reduce the temperature fluctuation during the liquid nitrogen replenishment process, the present invention also discharges the relatively high-temperature liquid nitrogen remaining in the external liquid nitrogen pipeline by setting a bypass valve to prevent a small amount of relatively high-temperature liquid nitrogen from entering the liquid nitrogen warehouse.

[0017] The second aspect of the present invention provides a dewar tank, wherein the dewar tank comprises the liquid nitrogen replenishment system described above, and the dewar tank can automatically replenish the liquid nitrogen tank with liquid nitrogen and accurately control the replenishment amount of the liquid nitrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the liquid nitrogen replenishment system Figure 1 .

[0019] Figure 2 Schematic diagram of the liquid nitrogen replenishment system Figure 2 .

[0020] Figure 3 Schematic diagram of the liquid nitrogen replenishment system Figure 3 .

[0021] Explanation of the main component symbols: 11-liquid nitrogen pipeline, 12-first exhaust pipeline, 13-second exhaust pipeline, 21-differential pressure sensor, 22-temperature sensor, 31-liquid replenishing valve, 32-bypass valve, 33-exhaust valve, 14-first connecting pipeline, 15-air pipeline, 16-second connecting pipeline, 34-first reversing valve, 35-second reversing valve, 17-blowing pipeline, 141-first sub-pipeline, 142-second sub-pipeline, 41-liquid nitrogen warehouse, 42-tank body, 43-tank cover, 44-sample warehouse, 45-first thermal insulation layer, 46-first cavity, 47-second thermal insulation layer, 48-third exhaust pipeline, 5-liquid nitrogen tank. DETAILED DESCRIPTION

[0022] The present invention provides a liquid nitrogen replenishment system and a dewar tank. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, and a specific direction structure and operation, and therefore, cannot be understood as a limitation of the present invention. In addition, "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means more than two.

[0024] See also Figure 1 The present invention provides a liquid nitrogen replenishment system, comprising:

[0025] A liquid nitrogen pipeline 11, wherein both ends of the liquid nitrogen pipeline 11 are respectively connected to the liquid nitrogen tank 5 and the Dewar liquid nitrogen warehouse 41;

[0026] A temperature sensor 22, a first exhaust pipe 12 and a liquid replenishing valve 31, wherein the temperature sensor 22, the first exhaust pipe 12 and the liquid replenishing valve 31 are sequentially arranged on the liquid nitrogen pipe 11 from upstream to downstream, and a bypass valve 32 is arranged on the first exhaust pipe 12;

[0027] The differential pressure sensor 21 and the first connecting pipe 14, wherein the first connecting pipe 14 is used to connect the differential pressure sensor 21 to the bottom of the Dewar tank liquid nitrogen warehouse 41;

[0028] A second exhaust pipe 13 and an exhaust valve 33 disposed on the second exhaust pipe 13, wherein the second exhaust pipe 13 is used to communicate with the top of the Dewar tank liquid nitrogen warehouse 41;

[0029] A control device, wherein the control device is electrically connected to the temperature sensor 22, the bypass valve 32, the liquid replenishing valve 31, the pressure difference sensor 21 and the exhaust valve 33 respectively.

[0030] The liquid level height of the Dewar tank liquid nitrogen warehouse 41 is related to the pressure. Therefore, by using the differential pressure sensor 21 to measure the pressure difference between the inside of the Dewar tank liquid nitrogen warehouse 41 and the outside, the liquid level height of the Dewar tank liquid nitrogen warehouse 41 can be calculated.

[0031] One end of the pressure difference sensor 21 is connected to the outside world, and the pressure is kept stable. The other end is connected to the bottom of the Dewar tank liquid nitrogen warehouse 41. By measuring the pressure difference change, the liquid level height change of the liquid nitrogen warehouse 41 is calculated.

[0032] The control method of the liquid nitrogen replenishment system of this embodiment is as follows:

[0033] The program in the control device is set to continuously and automatically measure the real-time liquid level of the liquid nitrogen in the Dewar tank liquid nitrogen warehouse 41, and set the lower limit value and the upper limit value of the liquid level. When the detected real-time liquid level is lower than the lower limit value of the liquid level, the temperature sensor 22 is started, and the real-time temperature data in the liquid nitrogen pipeline 11 upstream of the liquid replenishing valve 31 is measured by the temperature sensor 22. The real-time temperature data is compared with the preset upper limit value of the temperature. If the real-time temperature data is greater than the upper limit value of the temperature, the bypass valve 32 is opened to discharge the high-temperature nitrogen in the liquid nitrogen pipeline 11 upstream of the liquid replenishing valve 31 until the real-time temperature data is less than the upper limit value of the temperature, and the bypass valve 32 is closed;

[0034] Then, the liquid replenishing valve 31 and the exhaust valve 33 are opened simultaneously to replenish liquid nitrogen. During the replenishing process, the control device continuously measures the real-time liquid level of the liquid nitrogen. When the real-time liquid level is greater than the preset liquid level upper limit, the liquid replenishing valve 31 and the exhaust valve 33 are closed.

[0035] See also Figure 2In one embodiment, the liquid nitrogen replenishment system also includes: a first reversing valve 34, a purge pipe 17 and a second connecting pipe 16; the first reversing valve 34 includes three interfaces, which are respectively connected to the purge pipe 17, the first connecting pipe 14 and the second connecting pipe 16; the first reversing valve 34 is used to connect the second connecting pipe 16 to the first connecting pipe 14 or the purge pipe 17; the first connecting pipe 14 is used to connect the first reversing valve 34 to the pressure difference sensor 21; the second connecting pipe 16 is used to connect the first reversing valve 34 to the bottom of the Dewar tank liquid nitrogen warehouse 41; the purge pipe 17 is used to connect the first reversing valve 34 to the liquid nitrogen pipe 11 upstream of the refilling valve 31; the first reversing valve 34 is electrically connected to the control device.

[0036] Preferably, the purge pipe 17 is a capillary tube, which is used to convert liquid nitrogen into nitrogen gas, thereby forming nitrogen gas to purge the second connecting pipe 16 .

[0037] In this embodiment, before the differential pressure sensor 21 performs detection, the detection pipeline is also blown out to keep the relevant pipelines for measuring the pressure difference connected, so as to avoid the influence of a small amount of frost formed in the pipeline under low temperature conditions on calibration and measurement.

[0038] The control method of the liquid nitrogen replenishment system of this embodiment is as follows:

[0039] Before calibration, the control device first controls the exhaust valve 33 to open, and controls the first reversing valve 34 to connect the second connecting pipe 16 with the purge pipe 17; after the purge pipe 17 sprays nitrogen to purge the second connecting pipe 16 for a certain period of time, the control device controls the first reversing valve 34 to connect the second connecting pipe 16 with the first connecting pipe 14, so that the differential pressure sensor 21 starts to measure the pressure difference between the bottom of the liquid nitrogen warehouse 41 and the outside.

[0040] See also Figure 3 In one embodiment, the liquid nitrogen replenishment system also includes: a second reversing valve 35, an air pipe 15; the first connecting pipe 14 includes a first sub-pipeline 141 and a second sub-pipeline 142; the second reversing valve 35 includes three interfaces, which are respectively connected to the first sub-pipeline 141, the air pipe 15 and the second sub-pipeline 142; the second reversing valve 35 is used to connect the first sub-pipeline 141 with the air pipe 15 or the second sub-pipeline 142; the first sub-pipeline 141 is used to connect the second reversing valve 35 with the pressure difference sensor 21; the other end of the air pipe 15 is connected to the external environment; the second sub-pipeline 142 is used to connect the first reversing valve 34 with the second reversing valve 35; the second reversing valve 35 is electrically connected to the control device.

[0041] In this embodiment, the air duct 15 is used to calibrate the differential pressure sensor 21. The differential pressure sensor 21 needs to be calibrated regularly to ensure the accuracy of detection.

[0042] During calibration, the control device controls the second reversing valve 35 to connect the air pipe 15 with the first sub-pipeline 141 , so that the pressure difference sensor 21 completes calibration.

[0043] After the calibration is completed, the control device controls the second reversing valve 35 to connect the first sub-pipeline 141 with the second sub-pipeline 142 .

[0044] Preferably, the liquid nitrogen pipeline 11 includes an inner embedded section and an exposed section, the inner embedded section is arranged in the Dewar tank, and the exposed section is wrapped with a heat insulating material, which can reduce the heat exchange between the liquid nitrogen pipeline 11 in the exposed section and the external environment.

[0045] See also Figure 2 In a second aspect, the present invention provides a dewar tank, which includes a tank body 42, a liquid nitrogen tank 5, and the liquid nitrogen replenishment system as described above. Specifically, the tank body 42 is provided with a sample bin 44, a first thermal insulation layer 45, and a liquid nitrogen bin 41 from top to bottom. The dewar tank of the present invention uses the liquid nitrogen bin 41 as a fixed cold source for refrigeration, and adjusts the thickness and thermal insulation performance of the first thermal insulation layer 45 so that the storage temperature of the sample bin 44 is maintained in a specific temperature range.

[0046] Preferably, a tank cover 43 is provided on the top of the tank body 42; a first cavity 46 is formed between the tank cover 43 and the sample chamber 44; a second thermal insulation layer 47 is provided on the side wall of the tank body 42; a third exhaust duct 48 is provided in the second thermal insulation layer 47, and the lower end of the third exhaust duct 48 is connected to the top of the sample chamber 44, and the top end thereof is connected to the first cavity 46 above the sample chamber 44.

[0047] The third exhaust pipe 48 is used to release the nitrogen volatilized from the liquid nitrogen tank 5 to the top of the sample chamber 44. When the tank cover 43 is opened, a low-temperature nitrogen layer will be formed above the sample chamber 44, which can help reduce the temperature increase of the sample chamber 44 during sampling.

[0048] Specifically, the tank cover 43 is also provided with heat insulating material, which can effectively reduce the heat entering the tank.

[0049] In summary, the liquid nitrogen replenishment system of the present invention realizes the accurate measurement of the liquid level of the Dewar tank liquid nitrogen tank 41 and further realizes the accurate control and addition of liquid nitrogen through the combination of components such as the temperature sensor 22, the bypass valve 32, the liquid replenishment valve 31, the pressure difference sensor 21, the exhaust valve 33 and related pipelines.

[0050] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. A liquid nitrogen replenishment system, characterized in that: include: A liquid nitrogen pipeline, both ends of which are connected to a liquid nitrogen tank and a Dewar liquid nitrogen warehouse respectively; A temperature sensor, a first exhaust pipe and a liquid replenishing valve, wherein the temperature sensor, the first exhaust pipe and the liquid replenishing valve are sequentially arranged on the liquid nitrogen pipe from upstream to downstream, and a bypass valve is arranged on the first exhaust pipe; A pressure differential sensor and a first connecting pipe, wherein the first connecting pipe is used to connect the pressure differential sensor to the bottom of the Dewar tank liquid nitrogen bin; A second exhaust pipeline and an exhaust valve disposed on the second exhaust pipeline, wherein the second exhaust pipeline is used to communicate with the top of the Dewar tank liquid nitrogen warehouse; A control device is electrically connected to the temperature sensor, the bypass valve, the liquid replenishing valve, the pressure difference sensor and the exhaust valve respectively.

2. The liquid nitrogen replenishment system according to claim 1, characterized in that: Also includes: a first reversing valve, a purge pipe and a second connecting pipe; the first reversing valve includes three interfaces, which are respectively connected to the purge pipe, the first connecting pipe and the second connecting pipe; the first reversing valve is used to connect the second connecting pipe with the first connecting pipe or the purge pipe; the first connecting pipe is used to connect the first reversing valve with the pressure difference sensor; the second connecting pipe is used to connect the first reversing valve with the bottom of the Dewar tank liquid nitrogen warehouse; the purge pipe is used to connect the first reversing valve with the liquid nitrogen pipe upstream of the refilling valve; the first reversing valve is electrically connected to the control device.

3. The liquid nitrogen replenishment system according to claim 2, characterized in that: The blowing-off pipeline is a capillary tube.

4. The liquid nitrogen replenishment system according to claim 2, characterized in that: Also includes: a second reversing valve and an air duct; the first connecting duct includes a first sub-duct and a second sub-duct; the second reversing valve includes three interfaces, which are respectively connected to the first sub-duct, the air duct and the second sub-duct; the second reversing valve is used to connect the first sub-duct with the air duct or the second sub-duct; the first sub-duct is used to connect the second reversing valve and the pressure difference sensor; the other end of the air duct is connected to the external environment; the second sub-duct is used to connect the first reversing valve with the second reversing valve; the second reversing valve is electrically connected to the control device.

5. The liquid nitrogen replenishment system according to claim 1, characterized in that: The liquid nitrogen pipeline comprises an inner embedded section and an exposed section, wherein the inner embedded section is arranged in a dewar tank, and the exposed section is wrapped with a heat insulating material.

6. A Dewar tank, characterized in that: It comprises a tank body, a liquid nitrogen tank and a liquid nitrogen replenishment system as described in any one of claims 1 to 5.

7. The Dewar vessel according to claim 6, characterized in that: The tank body is provided with a sample chamber, a first heat insulation layer and a liquid nitrogen chamber in sequence from top to bottom.

8. The Dewar vessel according to claim 6, characterized in that: A tank cover is arranged on the top of the tank body; a first cavity is formed between the tank cover and the sample chamber; and a second heat insulation layer is arranged on the side wall of the tank body.

9. The Dewar vessel according to claim 8, characterized in that: A third exhaust duct is arranged in the second heat insulation layer, the lower end of the third exhaust duct is communicated with the top of the sample chamber, and the top end of the third exhaust duct is communicated with the first cavity above the sample chamber.

10. The Dewar vessel according to claim 8, characterized in that: A heat insulating material is arranged inside the tank cover.

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