Horizontal liquid nitrogen Dewar tank switching use device

Abstract

The invention discloses a horizontal liquid nitrogen Dewar tank switching use device, and belongs to the technical field of radio frequency power supply HASS and HALT tests. A switching device is arranged on liquid nitrogen conveying pipes of two horizontal liquid nitrogen Dewar tanks, so that when liquid nitrogen in one tank is about to be used up, the system can be automatically or manually switched to the other tank to continuously supply liquid, and meanwhile, an empty liquid nitrogen Dewar tank can be replaced, so that uninterrupted circulation of liquid nitrogen supply is realized, and the continuity of a test is ensured; a small-capacity Dewar tank is adopted to replace a large storage tank and is placed on the movable mounting frame, so that the occupied area is reduced, the application scene is wide, the initial input cost is reduced, maintenance is convenient, meanwhile, liquid nitrogen can be supplied as required according to actual requirements, and evaporation loss caused by long-time storage is avoided; in addition, a pressure adjusting assembly is arranged on the liquid nitrogen conveying tank, the pressure in the pipeline can be visually monitored in real time, overpressure of the pipeline is prevented, and safety is improved.

Description

Technical Field

[0001] The invention relates to the technical field of radio frequency power supply HASS and HALT testing, and in particular to a device for switching use of a horizontal liquid nitrogen dewar tank. Background Art

[0002] In the reliability testing of electronic equipment and components, it is necessary to ensure that they can operate stably in various extreme environments, including extremely cold conditions. In order to ensure that the product can still work normally under extremely cold conditions, it is necessary to conduct HASS (Highly Accelerated Stress Screening) tests, in which low-temperature environment simulation is one of the key links. Liquid nitrogen is widely used to simulate low-temperature conditions in polar regions, high altitudes and other cold regions due to its extremely low temperature (about -196°C). In the HASS test, electronic components are placed in a liquid nitrogen environment to identify problems such as solder joint cracking, material embrittlement, and component failure that may be caused by low temperatures.

[0003] Therefore, the use of liquid nitrogen for low-temperature environment simulation has become an important means in the reliability test of electronic equipment. In the HASS test, the supply method of liquid nitrogen directly affects the stability and economy of the test. At present, some large state-owned enterprises usually set up large-capacity liquid nitrogen storage tanks outside the laboratory to meet the test needs. However, this traditional storage method has some problems: (1) High installation cost. The installation of large liquid nitrogen storage tanks requires a lot of space and involves complex pipeline layout and safety protection measures, with high initial investment costs; (2) Difficult equipment maintenance. Since the liquid nitrogen storage tank is exposed to the outdoor environment for a long time, affected by temperature and humidity changes, rain and snow weather, its pipes, valves and other components are prone to rust and aging, and require regular maintenance, which increases its use cost and maintenance workload; (3) Liquid nitrogen loss. Since liquid nitrogen is stored for a long time without use, it will naturally vaporize and be continuously discharged through the pressure relief valve, causing unnecessary loss, reducing the utilization rate of liquid nitrogen and increasing the use cost; (4) Discontinuous liquid supply affects the test. In the HASS test, the stability of liquid nitrogen supply is crucial to the test results. However, the capacity of a single bottle of liquid nitrogen is limited and cannot support the entire test process. If the liquid nitrogen supply is interrupted, not only will the test fail, but the test samples may also be damaged.

[0004] In view of this, this application is hereby filed. Summary of the invention

[0005] The purpose of the present invention is to provide a horizontal liquid nitrogen dewar tank switching device, which can effectively solve the problem of insufficient supply of single bottle of liquid nitrogen in HASS test, so as to realize continuous, economical and safe supply of liquid nitrogen.

[0006] In order to solve the above problems, the present invention adopts the following technical solutions: a device for switching and using a horizontal liquid nitrogen dewar tank, comprising two horizontal liquid nitrogen dewar tanks and a plurality of liquid nitrogen delivery pipes, characterized in that: the two horizontal liquid nitrogen dewar tanks are respectively connected to the switching device through the liquid nitrogen delivery pipes, and the switching device comprises two bus stop valves for switching the supply channels of the two horizontal liquid nitrogen dewar tanks;

[0007] The liquid nitrogen delivery pipe is provided with a pressure regulating assembly, which includes a pressure gauge and a plurality of automatic pressure relief and exhaust valves, and is used to regulate the liquid nitrogen supply pressure and prevent the pipeline from instantaneous overpressure;

[0008] When the residual liquid nitrogen in one of the horizontal liquid nitrogen dewar tanks is insufficient, the switching device can close the supply channel of the tank and open the supply channel of another horizontal liquid nitrogen dewar tank to achieve continuous supply of liquid nitrogen and enable the test to proceed stably.

[0009] In a further embodiment, the liquid nitrogen delivery pipe includes a first liquid nitrogen delivery pipe, a second liquid nitrogen delivery pipe and a third liquid nitrogen delivery pipe, one end of the first liquid nitrogen delivery pipe is connected to the liquid outlet of one of the horizontal liquid nitrogen Dewar tanks, one end of the second liquid nitrogen delivery pipe is connected to the liquid outlet of another horizontal liquid nitrogen Dewar tank, and the third liquid nitrogen delivery pipe is a three-way pipe, which is connected to the first liquid nitrogen delivery pipe and the second liquid nitrogen delivery pipe, and the other end is connected to the test chamber;

[0010] The two bus stop valves are respectively installed on the first liquid nitrogen delivery pipe and the second liquid nitrogen delivery pipe.

[0011] Through the above technical solution, a simpler pipeline switching layout can be achieved, which reduces the repeated laying of pipelines and reduces the complexity of pipelines.

[0012] In a further embodiment, the automatic pressure relief exhaust valve comprises a first automatic pressure relief exhaust valve, a second automatic pressure relief exhaust valve and a third automatic pressure relief exhaust valve, the first automatic pressure relief exhaust valve is installed on the first liquid nitrogen delivery pipe, the second automatic pressure relief exhaust valve is installed on the second liquid nitrogen delivery pipe, and the third automatic pressure relief exhaust valve is installed on the third liquid nitrogen delivery pipe;

[0013] The pressure gauge is installed on the third liquid nitrogen delivery pipe.

[0014] Through the above technical solution, the pressure of each pipeline can be independently monitored and excess pressure can be automatically released, which greatly improves the safety during use; at the same time, a pressure gauge is set on the third liquid nitrogen delivery pipe, which helps to understand the overall pressure situation at the liquid supply end in real time, making it easier for operators to monitor and adjust the operating status of the entire system.

[0015] In a further embodiment, the two horizontal liquid nitrogen dewar tanks are both provided with a vent, and the vent is connected to a pressure relief vent pipe.

[0016] Through the above technical solution, excessive pressure can be prevented from accumulating inside the tank, further improving the safety of use.

[0017] In a further embodiment, the outside of the liquid nitrogen delivery pipe is wrapped with an insulation layer, and the insulation layer is made of aluminum foil, rubber and plastic material.

[0018] Through the above technical solution, the cost of the insulation material is low, and at the same time it has the functions of low temperature resistance and anti-freeze damage, which effectively improves the service life of the pipeline system.

[0019] In a further embodiment, two mounting frames are further included, and a plurality of limit plates are fixed on the mounting frames, and the horizontal liquid nitrogen dewar tank is placed on the limit plates;

[0020] A plurality of universal wheels are arranged at the bottom of the mounting frame.

[0021] Through the above technical solution, the stability during use is increased and the layout of different workstations and use environments can be met.

[0022] In a further embodiment, a support frame is included, and the liquid nitrogen delivery pipe can be placed on the support frame.

[0023] The above technical solution can avoid damage or safety hazards caused by hanging, bending or vibration of the liquid nitrogen delivery pipe.

[0024] In a further embodiment, the first liquid nitrogen delivery pipe and the second liquid nitrogen delivery pipe are detachably connected to the liquid outlet connection of the horizontal liquid nitrogen Dewar tank.

[0025] Through the above technical solution, the liquid supply can be quickly restored after replacement, which helps to shorten the downtime and improve the overall utilization efficiency of the device.

[0026] Beneficial effects: By installing a switching device on the liquid nitrogen delivery pipes of two horizontal liquid nitrogen dewar tanks, when the liquid nitrogen in one tank is about to be exhausted, the system can automatically or manually switch to the other tank to continue supplying liquid, and the empty liquid nitrogen dewar tank can be replaced at the same time to achieve an uninterrupted cycle of liquid nitrogen supply and ensure the continuity of the test; by using a small-capacity dewar tank to replace a large storage tank and placing it on a movable mounting rack, the floor space is reduced, the application scenario is wide, the initial investment cost is reduced and maintenance is convenient, and liquid nitrogen can be supplied on demand according to actual needs to avoid evaporation loss caused by long-term storage; in addition, a pressure regulating component is set on the liquid nitrogen delivery tank, which can monitor the pressure in the pipeline in real time and intuitively, prevent over-pressure in the pipeline, and increase safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the connection between the horizontal liquid nitrogen dewar tank and the liquid nitrogen delivery pipe in the present invention;

[0028] Figure 2 It is a structural schematic diagram of the present invention.

[0029] Figure numerals: 1. horizontal liquid nitrogen dewar tank; 2. mounting frame; 21. limit plate; 22. universal wheel; 31. first liquid nitrogen delivery pipe; 32. second liquid nitrogen delivery pipe; 33. third liquid nitrogen delivery pipe; 4. pressure gauge; 53. third automatic pressure relief exhaust valve; 6. support frame. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In order to solve the problem that the amount of liquid nitrogen in a single bottle cannot sustain the entire test process during the HASS test, and the existing liquid nitrogen storage tanks have high installation costs, difficult equipment maintenance, and reduced liquid nitrogen utilization due to the loss of liquid nitrogen, the present application proposes a horizontal liquid nitrogen Dewar tank 1 switching and use device, hereinafter referred to as "the device". The device can be connected to two bottles of liquid nitrogen at the same time, and automatically switch during the test. When one of the bottles of liquid nitrogen is about to be exhausted, the device will switch to the other bottle to continue supplying liquid. At the same time, the exhausted liquid nitrogen bottle can be replaced with a new full tank of liquid nitrogen at any time to achieve a circulating supply; through small amounts and multiple replenishments, the liquid nitrogen volatilization loss is reduced and the use efficiency is improved. Compared with the single-bottle liquid nitrogen supply method, the present application can not only ensure the continuity of liquid nitrogen supply during the test, but also greatly reduce the waste of liquid nitrogen. At the same time, the device has low installation costs and is easy to operate.

[0032] The content of the present invention will be described below with reference to specific embodiments.

[0033] like Figure 1 to Figure 2 As shown, a switching device for a horizontal liquid nitrogen dewar tank 1 provided in this embodiment includes two horizontal liquid nitrogen dewar tanks 1, a plurality of liquid nitrogen delivery pipes, a switching device and a pressure regulating assembly. The two horizontal liquid nitrogen dewar tanks 1 are respectively connected to the switching device through liquid nitrogen delivery pipes, and the switching device is used to switch the supply channels of the two horizontal liquid nitrogen dewar tanks 1; the pressure regulating assembly is arranged on the liquid nitrogen delivery pipe, and is used to adjust the liquid nitrogen supply pressure and prevent the pipeline from instantaneous overpressure.

[0034] Specifically, two horizontal liquid nitrogen dewar tanks 1 of the same specifications are selected to replace the large liquid nitrogen storage tank. Liquid nitrogen can be supplied on demand according to actual needs, avoiding evaporation loss caused by long-term storage, so as to greatly reduce liquid nitrogen waste and improve utilization. The horizontal liquid nitrogen dewar tank 1 is placed horizontally on the mounting frame 2, and the mounting frame 2 is provided with a plurality of limit plates 21, which are used to limit and fix the horizontal liquid nitrogen dewar tank 1 to prevent the displacement or shaking of the tank body due to vibration or collision during transportation or use. The horizontal liquid nitrogen dewar tank 1 is provided with a vent port and is connected to a pressure relief vent pipe, which is convenient for the safe discharge of the residual liquid nitrogen or gas in the dewar tank during inspection, maintenance or decommissioning, and prevents excessive pressure from accumulating inside the tank body, further improving the safety of use and reducing the potential risk of accidents.

[0035] The liquid nitrogen delivery pipe includes a first liquid nitrogen delivery pipe 31, a second liquid nitrogen delivery pipe 32 and a third liquid nitrogen delivery pipe 33, wherein one end of the first liquid nitrogen delivery pipe 31 is connected to the liquid outlet of a horizontal liquid nitrogen Dewar tank 1, one end of the second liquid nitrogen delivery pipe 32 is connected to the liquid outlet of another horizontal liquid nitrogen Dewar tank 1, and the third liquid nitrogen delivery pipe 33 is a three-way pipe, which is connected to the first liquid nitrogen delivery pipe 31 and the second liquid nitrogen delivery pipe 32, and the other end is connected to the test cavity, so that the first liquid nitrogen delivery pipe 31 and the second liquid nitrogen delivery pipe 32 are merged into the third liquid nitrogen delivery pipe 33, and the third liquid nitrogen delivery pipe 33 is then connected to the test cavity, so as to continuously provide liquid nitrogen to the test device.

[0036] Continue reading Figure 1 The device also includes a support frame 6. The liquid nitrogen delivery pipe can be laid along the support frame 6 during layout to reduce pipeline bending, achieve a more orderly and stable layout, improve the reliability of system operation, and avoid pipeline damage or safety hazards caused by suspension, bending or vibration.

[0037] As a preferred solution, the outside of the liquid nitrogen delivery pipe is wrapped with an insulation layer, which is made of aluminum foil and rubber plastic material, effectively reducing heat exchange during liquid nitrogen transportation and reducing liquid nitrogen evaporation loss; at the same time, the material has low temperature resistance and anti-freeze function, which increases the service life of the pipeline system and has low cost.

[0038] As a preferred solution, the liquid outlets of the two horizontal liquid nitrogen dewar tanks 1 are respectively connected to the first liquid nitrogen delivery pipe 31 and the second liquid nitrogen delivery pipe 32 by detachable connection methods, such as flanges or quick connectors. The detachable connection facilitates the rapid restoration of liquid supply after subsequent maintenance or replacement of the pipeline, which helps to shorten the downtime and improve the overall utilization efficiency of the device.

[0039] The switching device includes two bus stop valves, which are respectively installed on the first liquid nitrogen delivery pipe 31 and the second liquid nitrogen delivery pipe 32. Figure 2As shown, when the horizontal liquid nitrogen Dewar tank 1A is needed, the bus stop valve V1 is opened and the horizontal liquid nitrogen Dewar tank 1B is closed; when the liquid nitrogen in the horizontal liquid nitrogen Dewar tank 1A is insufficient, the bus stop valve V1 is closed and the bus stop valve V2 is opened, and the liquid supply can be quickly switched to the horizontal liquid nitrogen Dewar tank 1B.

[0040] The pressure regulating assembly includes a pressure gauge 4 and several automatic pressure relief exhaust valves. The pressure gauge 4 is installed on the third liquid nitrogen delivery pipe 33 to monitor the pressure of liquid nitrogen entering the test chamber in real time, so that the operator can grasp and adjust the supply of liquid nitrogen. The automatic pressure relief exhaust valve includes a first automatic pressure relief exhaust valve, a second automatic pressure relief exhaust valve and a third automatic pressure relief exhaust valve 53. The first automatic pressure relief exhaust valve is installed on the first liquid nitrogen delivery pipe 31, the second automatic pressure relief exhaust valve is installed on the second liquid nitrogen delivery pipe 32, and the third automatic pressure relief exhaust valve 53 is installed on the third liquid nitrogen delivery pipe 33 to prevent instantaneous overpressure in each pipeline due to temperature changes or operating condition fluctuations, and to discharge excess gas in time to improve the safety of the use process.

[0041] As a preferred solution, both the first liquid nitrogen delivery pipe 31 and the second liquid nitrogen delivery pipe 32 are installed with a booster valve to ensure that the pressure in the pipe is within the pressure range required for the test.

[0042] In this embodiment, the specific working process of the device during the test is as follows:

[0043] Before use, the two horizontal liquid nitrogen dewar tanks 1 are preliminarily pressurized and depressurized to reach the pressure range of 100-150psi required for the test. During depressurization, nitrogen can be discharged to the outside through the pressure relief vent pipe to avoid direct discharge of nitrogen into the indoor air to prevent the risk of suffocation; then, c is installed at the liquid outlets of the two horizontal liquid nitrogen tanks, confirm the liquid nitrogen tank to be used first and open the bus stop valve of the line, and observe whether the actual pressure value is consistent with the preset pressure of the tank body through the pressure gauge 4. If it is inconsistent, fine-tune it through the corresponding booster valve or automatic pressure relief valve on the line to make the pressure in the pipeline within the pressure range required for the test.

[0044] During the experiment, as the amount of liquid nitrogen in the tank decreases, the pressure in the tank will decrease. When the pointer of pressure gauge 4 shows less than 100psi, continue to open the corresponding liquid nitrogen tank booster valve to increase the pressure. When the liquid level gauge of the used liquid nitrogen shows that the remaining amount is less than 10%, open the bus stop valve on the delivery channel of another tank of liquid nitrogen, and close the bus stop valve on the road of the liquid nitrogen tank in use, so that the next tank of liquid nitrogen can be directly and seamlessly switched to use.

[0045] When the whole test is finished, the liquid outlet valves on the two horizontal liquid nitrogen dewar tanks 1 are closed, and the bus stop valves on the first liquid nitrogen delivery pipe 31 and the second liquid nitrogen delivery pipe 32 are opened at the same time. The HASS host computer program is cooled down to a temperature lower than the normal temperature so that the remaining nitrogen in the pipeline can be discharged into the HASS box. It can be observed that the pressure of the pressure gauge 4 returns to zero at this time, indicating that the nitrogen in the pipeline is exhausted. Finally, the two bus stop valves are closed and opened again for the next test.

[0046] Through the coordination of the above structures and steps, this embodiment can ensure a stable and continuous supply of liquid nitrogen during the test, avoiding the system shutdown or instability caused by the exhaustion of a dewar tank. At the same time, the automatic pressure relief exhaust valve, the pressure gauge 4 and the detachable connecting pipeline greatly improve the safety of use and the convenience of maintenance of the device.

[0047] On the basis of the above embodiment, considering the need for outdoor use or mobility in a low-temperature environment, a plurality of universal wheels 22 can be installed at the bottom of the mounting frame 2 and a vibration reduction device can be installed at the universal wheels 22, so as to provide better support and vibration reduction effects during transportation and reduce the impact on the pipeline or valve. At the same time, a protective frame can also be set outside the mounting frame 2 to protect the dewar tank body and pipeline as a whole to prevent damage to them by the external environment.

[0048] Compared with the prior art, this application has the following significant advantages:

[0049] (1) Liquid supply is continuous and stable. By respectively setting bus stop valves on the liquid nitrogen delivery pipes of the two horizontal liquid nitrogen dewar tanks 1, rapid switching between the two horizontal liquid nitrogen dewar tanks 1 is achieved. When the liquid nitrogen in one dewar tank is about to be exhausted, the system can automatically or manually switch to another tank to continue supplying liquid. At the same time, the empty liquid nitrogen dewar tank can be replaced to achieve an uninterrupted cycle of liquid nitrogen supply and ensure the continuity of the test.

[0050] (2) High safety. The liquid nitrogen delivery pipe is equipped with a pressure gauge 4 and several automatic pressure relief and exhaust valves. Once the pressure in one pipeline is higher than the set value, the automatic pressure relief and exhaust valve will open and close in time to avoid pipeline rupture or other dangers caused by overpressure. In addition, the dewar tank itself is also equipped with a vent and connected to the pressure relief and exhaust pipeline, which can quickly and safely discharge the residual pressure during maintenance, decommissioning or abnormality.

[0051] (3) Small footprint and low cost. Dewar tanks are used instead of large storage tanks to reduce the footprint of the equipment, reduce initial investment costs, and avoid evaporation losses caused by long-term storage of liquid nitrogen tanks.

[0052] (4) The structure is simple and easy to maintain. The first liquid nitrogen delivery pipe 31 and the second liquid nitrogen delivery pipe 32 are detachably connected to the horizontal liquid nitrogen dewar tank 1. During routine maintenance or pipeline inspection, they can be quickly disconnected and replaced, which significantly improves the inspection efficiency.

[0053] In summary, the horizontal liquid nitrogen Dewar tank 1 switching use device provided in the present application achieves the purpose of improving the reliability of continuous supply of liquid nitrogen, ensuring the stability of low-temperature tests, enhancing equipment safety and maintenance convenience through reasonable pipeline switching methods and safety protection designs, effectively solves the problem of insufficient supply of single-bottle liquid nitrogen in HASS tests, ensures the stability, economy and safety of the test process, and has wide application value.

[0054] The above content is a detailed description of the present invention in combination with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A device for switching between horizontal liquid nitrogen dewar tanks (1), comprising two horizontal liquid nitrogen dewar tanks (1) and a plurality of liquid nitrogen delivery pipes, characterized in that: The two horizontal liquid nitrogen dewar tanks (1) are respectively connected to a switching device through the liquid nitrogen delivery pipe, and the switching device comprises two bus stop valves for switching supply channels of the two horizontal liquid nitrogen dewar tanks (1); The liquid nitrogen delivery pipe is provided with a pressure regulating assembly, which comprises a pressure gauge (4) and a plurality of automatic pressure relief and exhaust valves, and is used to regulate the liquid nitrogen supply pressure and prevent instantaneous overpressure in the pipeline; When the residual amount of liquid nitrogen in one of the horizontal liquid nitrogen dewar tanks (1) is insufficient, the switching device can close the supply channel of the tank and open the supply channel of another horizontal liquid nitrogen dewar tank (1) to achieve continuous supply of liquid nitrogen and enable the test to be carried out stably.

2. A device for switching use of a horizontal liquid nitrogen dewar tank (1) according to claim 1, characterized in that: The liquid nitrogen delivery pipe comprises a first liquid nitrogen delivery pipe (31), a second liquid nitrogen delivery pipe (32) and a third liquid nitrogen delivery pipe (33); one end of the first liquid nitrogen delivery pipe (31) is connected to a liquid outlet of one of the horizontal liquid nitrogen Dewar tanks (1); one end of the second liquid nitrogen delivery pipe (32) is connected to a liquid outlet of another of the horizontal liquid nitrogen Dewar tanks (1); the third liquid nitrogen delivery pipe (33) is a three-way pipe, which is in communication with the first liquid nitrogen delivery pipe (31) and the second liquid nitrogen delivery pipe (32), and the other end of which is in communication with the test chamber; The two bus stop valves are respectively installed on the first liquid nitrogen delivery pipe (31) and the second liquid nitrogen delivery pipe (32).

3. A device for switching use of a horizontal liquid nitrogen dewar tank (1) according to claim 2, characterized in that: The automatic pressure relief exhaust valve comprises a first automatic pressure relief exhaust valve, a second automatic pressure relief exhaust valve and a third automatic pressure relief exhaust valve (53), the first automatic pressure relief exhaust valve being installed on the first liquid nitrogen delivery pipe (31), the second automatic pressure relief exhaust valve being installed on the second liquid nitrogen delivery pipe (32), and the third automatic pressure relief exhaust valve (53) being installed on the third liquid nitrogen delivery pipe (33); The pressure gauge (4) is installed on the third liquid nitrogen delivery pipe (33).

4. The device for switching use of a horizontal liquid nitrogen dewar tank (1) according to claim 1, characterized in that: The two horizontal liquid nitrogen dewar tanks (1) are both provided with a vent, and the vent is connected to a pressure relief vent pipeline.

5. The device for switching use of a horizontal liquid nitrogen dewar tank (1) according to claim 1, characterized in that: The liquid nitrogen delivery pipe is wrapped with an insulation layer on the outside, and the insulation layer is made of aluminum foil, rubber and plastic material.

6. The device for switching use of a horizontal liquid nitrogen dewar tank (1) according to claim 1, characterized in that: It also comprises two mounting frames (2), a plurality of limit plates (21) being fixed on the mounting frames (2), and the horizontal liquid nitrogen dewar tank (1) is placed on the limit plates (21); A plurality of universal wheels (22) are arranged at the bottom of the mounting frame (2).

7. The device for switching use of a horizontal liquid nitrogen dewar tank (1) according to claim 2, characterized in that: It also comprises a support frame (6), and the liquid nitrogen delivery pipe can be placed on the support frame (6).

8. The device for switching use of a horizontal liquid nitrogen dewar tank (1) according to claim 2, characterized in that: The first liquid nitrogen delivery pipe (31) and the second liquid nitrogen delivery pipe (32) are detachably connected to the liquid outlet connection of the horizontal liquid nitrogen Dewar tank (1).

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