A zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection

Abstract

The present invention discloses a zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection, comprising a refrigerator, a liquid nitrogen dewar, a storage tank, and an injection port head assembly. A vacuum cavity is provided in the storage tank, the liquid nitrogen dewar is suspended in the vacuum cavity, and a gap is left between the bottom of the liquid nitrogen dewar and the inner wall of the bottom of the storage tank. The injection port head assembly is connected to the liquid nitrogen dewar through a main neck tube bellows passing through the top of the tank body, and the refrigerator is arranged on the top of the tank body. In the present invention, a double-neck tube setting can be achieved by using a steel-aluminum joint and a stainless steel bellows. The use of a steel-aluminum joint can ensure that the stainless steel bellows can be connected to aluminum alloy structures such as the liquid nitrogen dewar, the injection port head assembly, and the refrigerator. This not only extends the heat conduction distance and reduces the lateral vibration of the refrigerator, but also greatly reduces the heat leakage of the system and reduces the evaporation rate of liquid nitrogen. It can achieve a longer static test and a shorter recondensation time, thereby extending the service life of the refrigerator.

Description

Technical Field

[0001] The present invention relates to the field of continuous cooling of a high-purity germanium spectrometer probe, and more particularly to a zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection. Background Art

[0002] High-purity germanium detection requires a continuously low-temperature environment. In order to improve the trouble caused by constantly adding liquid nitrogen, it is necessary to design a zero-evaporation refrigeration system with liquid nitrogen condensation to ensure continuous detection. The lower static evaporation rate and shorter condensation time can meet the effect of more than two years of use after adding liquid nitrogen once. For this purpose, it is necessary to design a low-heat-leakage, light-weight, and high-strength liquid nitrogen storage tank.

[0003] Traditional liquid nitrogen biological containers made of aluminum alloy can only have one main neck tube. Due to lateral force, it is impossible to install a second neck tube on a liquid nitrogen head. When stainless steel is used, the weight does not meet the portability requirements, and the force point is on the neck tube, there is no lateral support and many other pain points.

[0004] Patent publication number CN112731513 A discloses a refrigerator vibration damping structure. The structure includes: a liquid nitrogen tank into which the probe of a high-purity germanium spectrometer extends, with the liquid nitrogen in the tank used to cool the probe; a mounting base plate mounted on the liquid nitrogen tank, the mounting base plate having a first through-hole connecting to the interior of the liquid nitrogen tank; a vibration damping pad mounted on the mounting base plate; a refrigerator connecting flange mounted on the vibration damping pad for mounting the refrigerator, the refrigerator connecting flange having a second through-hole for passage of the refrigerator's refrigeration pipe; a bellows, the ends of which are fixed to the mounting base plate and the refrigerator connecting flange, respectively, with the ends of the bellows corresponding to the first through-hole and the second through-hole, respectively; and a refrigerator mounted on the refrigerator connecting flange, with the refrigerator's refrigeration pipe passing through the second through-hole, the bellows, and the first through-hole, in sequence, before entering the liquid nitrogen tank. This structure can reduce refrigerator vibration and improve the detection accuracy of the high-purity germanium spectrometer.

[0005] This patent document connects the refrigerator and the flange through a bellows to reduce the vibration of the refrigerator, but the core technical problem of heat leakage is not explained in the document. Judging from its product manual, the evaporation rate is relatively high. Summary of the Invention

[0006] The technical problem to be solved by the present invention is how to reduce heat leakage of a liquid nitrogen storage tank and reduce the evaporation rate.

[0007] The present invention solves the above technical problems through the following technical means: a zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection, comprising a refrigerator, a liquid nitrogen dewar, a storage tank, and an injection port head assembly, wherein a vacuum cavity is provided in the storage tank, the liquid nitrogen dewar is suspended in the vacuum cavity, and a gap is left between the bottom of the liquid nitrogen dewar and the inner wall of the bottom of the storage tank, the injection port head assembly is connected to the liquid nitrogen dewar through a main neck tube bellows passing through the top of the tank body, the refrigerator is arranged at the top of the tank body, and its cooling end is connected to the liquid nitrogen dewar through a refrigerator stainless steel bellows, both ends of the main neck tube bellows are fixedly connected to the injection port head assembly and the liquid nitrogen dewar through steel-aluminum joints, and both ends of the refrigerator stainless steel bellows are fastened to the injection port head assembly and the liquid nitrogen dewar through steel-aluminum joints.

[0008] By using steel-aluminum joints and stainless steel bellows, a double-neck tube setting can be achieved, overcoming the technical defect that the second neck tube cannot be set due to the problem of lateral force under the original epoxy resin or G10 material. At the same time, the use of steel-aluminum joints can ensure that the stainless steel bellows can be connected to aluminum alloy structures such as liquid nitrogen Dewar, injection port head assembly, and refrigerator. It not only extends the heat conduction distance and reduces the lateral vibration of the refrigerator, but also greatly reduces the heat leakage of the system and the evaporation rate of liquid nitrogen. It can achieve longer static testing and shorter recondensation time, thereby extending the service life of the refrigerator.

[0009] As an optimal technical solution, the storage tank includes a tank body, an upper flange, and a lower flange. The upper flange, the tank body, and the lower flange form a closed cavity structure. The upper flange is fixedly connected to the liquid nitrogen Dewar through multiple G10 tie rods. By forming a closed vacuum cavity in the storage tank, heat leakage is reduced. At the same time, by using tie rods made of G10 material, the heat transfer distance can be further extended and heat leakage can be reduced.

[0010] As an optimal technical solution, one end of the G10 pull rod is fixedly connected to the bottom wall of the upper flange through a threaded connecting block, and a connecting block is fixedly provided on the outer wall of the liquid nitrogen dewar. The other end of the G10 pull rod passes through the connecting block and is fastened to the pull rod upper nut through the pull rod lower nut. By connecting the G10 pull rod to the upper flange, the force point is transferred to the upper flange and the vacuum cylinder, thereby improving the strength. At the same time, the heat leakage is reduced by the pull rod made of G10 material.

[0011] As an optimal technical solution, one end of the main neck tube bellows is fixedly connected to the injection port head assembly through a steel-aluminum joint on the main bellows, the stainless steel part of the steel-aluminum joint on the main bellows is welded and fixed to the main neck tube bellows, and the aluminum alloy part of the main neck tube bellows is welded and fixed to the injection port head assembly.

[0012] As an optimal technical solution, an upper flange cover is fixedly provided on the top of the storage tank, and the injection port head assembly includes a PTFE upper head and a lower head. The top of the upper flange cover is fixedly connected to the lower head, and the lower head is fixedly connected to the PTFE upper head. A pressure transmitter is provided in the upper flange cover, and the pressure transmitter is fixedly connected to the lower head.

[0013] As a preferred technical solution, the injection port head assembly also includes a safety valve, a capacitance level gauge, a nitrogen pipeline, and a liquid nitrogen pipeline arranged on the PTFE upper head. The ends of the nitrogen pipeline and the liquid nitrogen pipeline are respectively provided with a nitrogen outlet and a liquid nitrogen injection port. The capacitance level gauge extends into the liquid nitrogen tank. By integrating the safety valve, capacitance level gauge, nitrogen outlet, and liquid nitrogen injection port into the PTFE upper head, they can be disassembled as a whole, which is convenient for use and maintenance.

[0014] As an optimal technical solution, it also includes a refrigeration machine cover, a refrigeration machine flange, and a shock-absorbing gasket. The refrigeration machine flange is fixedly arranged on the top of the upper flange, the refrigeration machine is fixedly arranged on the top of the refrigeration machine flange through the shock-absorbing gasket, and the refrigeration machine cover is fixedly arranged on the top of the upper flange cover. By fixing the refrigeration machine cover to the top of the upper flange cover and setting the shock-absorbing gasket, the axial vibration range of the refrigerator is increased.

[0015] As an optimal technical solution, the liquid nitrogen Dewar is provided with a lower connecting groove of the refrigerator bellows that is compatible with the main neck tube bellows and the steel-aluminum joint. The inner wall of the bottom of the storage tank is provided with a G10 axial stabilization block. The bottom of the liquid nitrogen Dewar is provided with a slider that is compatible with the G10 axial stabilization block. Through the setting of the G10 axial stabilization block, it is fixed in the middle of the lower flange and does not contact the wall surface of the upper liquid nitrogen Dewar. It will only contact when it shakes axially, which not only reduces heat leakage but also plays an axial positioning role.

[0016] As an optimal technical solution, the main neck tube bellows and the refrigerator stainless steel bellows are made of stainless steel 304 with a wall thickness of 0.15 mm. The refrigerator stainless steel bellows and the main neck tube bellows are made of stainless steel 304 with a wall thickness of 0.15 mm, which increases the heat conduction distance and reduces heat leakage. At the same time, it effectively reduces the vibration of the liquid nitrogen cylinder, making the liquid level measurement more accurate.

[0017] As an optimal technical solution, a heat dissipation baffle and a heat dissipation fan are provided on the top of the storage tank. The heat dissipation baffle is located between the main neck tube bellows and the refrigerator, and the heat dissipation fan is located outside the refrigerator.

[0018] The advantages of the present invention are:

[0019] (1) In the present invention, the double-neck tube can be set up by using a steel-aluminum joint and a stainless steel bellows, which overcomes the technical defect that the second neck tube cannot be set up due to the problem of lateral force under the original epoxy resin or G10 material. At the same time, the use of the steel-aluminum joint can ensure that the stainless steel bellows can be connected to aluminum alloy structures such as the liquid nitrogen dewar, the injection port head assembly, and the refrigerator. It not only extends the heat conduction distance and reduces the lateral vibration of the refrigerator, but also greatly reduces the heat leakage of the system and reduces the evaporation rate of liquid nitrogen. It can achieve a longer static test and a shorter recondensation time, thereby extending the service life of the refrigerator.

[0020] (2) In the present invention, by connecting the G10 tie rod to the upper flange, the force point is transferred to the upper flange and the vacuum cylinder, thereby improving the strength. At the same time, the heat leakage is reduced by the tie rod made of G10 material.

[0021] (3) In the present invention, the safety valve, capacitance level gauge, nitrogen outlet, and liquid nitrogen injection port are all integrated into the PTFE upper head, which can be disassembled as a whole, making it convenient to use and maintain.

[0022] (4) In the present invention, the stainless steel bellows of the refrigerator and the main neck tube bellows are made of stainless steel 304 with a wall thickness of 0.15 mm, which increases the heat conduction distance and reduces heat leakage, while effectively reducing the vibration of the liquid nitrogen cylinder, making the liquid level measurement more accurate.

[0023] (5) In the present invention, the G10 axial stabilizing block is fixed in the middle of the lower flange and does not contact the wall of the upper liquid nitrogen Dewar. It only contacts the wall when it shakes axially, which not only reduces heat leakage but also plays an axial positioning role. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a top view of a zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection provided by an embodiment of the present invention;

[0025] Figure 2 A zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection provided by an embodiment of the present invention Figure 1 Schematic diagram of AA structure;

[0026] Figure 3 A zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection provided by an embodiment of the present invention Figure 1 Schematic diagram of BB structure;

[0027] Figure 4 A schematic structural diagram of an injection port head assembly of a zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection provided by an embodiment of the present invention;

[0028] Figure 5A schematic diagram of the heat dissipation baffle structure of a zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection provided by an embodiment of the present invention;

[0029] Figure 6 A schematic diagram of the internal structure of a zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection provided by an embodiment of the present invention;

[0030] Figure 7 Schematic diagram of a force analysis of a G10 tie rod of a zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection provided by an embodiment of the present invention (the container simulates 30L liquid nitrogen);

[0031] Figure 8 A schematic diagram of the enhancement effect of the fillet weld at the root of the main neck pipe of a zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection provided by an embodiment of the present invention;

[0032] Figure numbers: 1. Refrigerator cover; 2. Upper flange cover; 3. Small Stirling refrigerator; 4. Refrigerator flange; 5. Shock-absorbing gasket; 6. Refrigerator upper steel-aluminum joint; 7. Refrigerator stainless steel bellows; 8. Refrigerator bellows lower connecting groove; 9. Refrigerator lower steel-aluminum joint; 10. Liquid nitrogen dewar; 11. Condenser; 12. Capacitance level gauge; 13. G10 axial stabilizer block; 14. PTFE upper head; 15. Liquid level gauge display; 16. Safety valve; 17. Lower head; 18. Upper steel-aluminum joint of main bellows; 19. Upper flange; 20. Main neck tube bellows; 21. G10 pull rod; 22. Lower steel-aluminum joint of main bellows; 23. Vacuum chamber; 24. Nitrogen outlet; 25. Pressure transmitter; 26. Liquid nitrogen injection port; 27. Handle; 28. Upper nut of pull rod; 29. Lower nut of pull rod; 30. Lower flange; 31. Lower connecting groove of main neck tube bellows; 32. Heat dissipation baffle; 33. Cooling fan; 34. Evacuation port. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with 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. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] See Figure 2, a zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection, comprising a refrigerator, a liquid nitrogen dewar 10, a storage tank, and an injection port head assembly. In this embodiment, the refrigerator is a small Stirling refrigerator 3, a vacuum chamber 23 is provided in the storage tank, the liquid nitrogen dewar 10 is suspended in the vacuum chamber 23, and a gap is left between the bottom of the liquid nitrogen dewar 10 and the inner wall of the bottom of the storage tank, the injection port head assembly is connected to the liquid nitrogen dewar 10 through a main neck tube bellows 20 passing through the top of the tank body, the refrigerator is provided at the top of the tank body, and its cooling end is connected to the liquid nitrogen dewar 10 through the refrigerator stainless steel bellows 7, the two ends of the main neck tube bellows 20 are respectively fixedly connected to the injection port head assembly and the liquid nitrogen dewar 10 through steel-aluminum joints. In this embodiment, the two ends of the refrigerator stainless steel bellows 7 are respectively connected and fastened to the injection port head assembly and the liquid nitrogen dewar 10 through steel-aluminum joints; the output end of the refrigerator is connected to the condenser 11;

[0035] The main neck tube bellows 20 and the refrigerator stainless steel bellows 7 are made of stainless steel 304 with a wall thickness of 0.15mm. The refrigerator stainless steel bellows 7 and the main neck tube bellows 20 are made of stainless steel 304 with a wall thickness of 0.15mm, which increases the heat conduction distance and reduces heat leakage. At the same time, it effectively reduces the vertical vibration transmitted to the liquid nitrogen dewar 10 by the refrigerator through the upper flange 19, making the liquid level measurement more accurate. The liquid nitrogen dewar 10 includes an upper head, a dewar body, and a lower head. The upper head is fixedly connected to the lower head through the dewar body. Through the hot and cold pits of the refrigerator and the heat leakage, zero evaporation of liquid nitrogen in the system (storage tank) is achieved.

[0036] By using steel-aluminum joints and stainless steel bellows, a double neck tube can be set up, which overcomes the technical defect that the second neck tube cannot be set up due to the problem of lateral force under the original aluminum alloy material. The original neck tube can only have one main neck tube under the aluminum alloy material, and the second neck tube cannot be set on a liquid nitrogen head due to lateral force; when stainless steel is used, the weight does not meet the portability, and there are many pain points such as the force point on the neck tube and no lateral support. At the same time, the use of steel-aluminum joints can ensure that the stainless steel bellows can be connected to aluminum alloy structures such as liquid nitrogen Dewar 10, injection port head assembly, and refrigerator, which not only extends the heat conduction distance and reduces heat leakage, but also reduces the lateral vibration caused by the refrigerator.

[0037] See Figure 3The storage tank includes a tank body, an upper flange 19, and a lower flange 30. The upper flange 19, the tank body, and the lower flange 30 enclose a closed cavity structure, namely a vacuum cavity 23. The upper flange cover 2 is fixedly connected to the top of the upper flange 19. The upper flange cover 2 and the upper flange 19 enclose another closed cavity structure. The upper flange 19 is fixedly connected to the liquid nitrogen dewar 10 through multiple G10 tie rods 21. The G10 tie rod 21 is a tie rod made of G10 material. The liquid nitrogen dewar 10 is connected through the G10 tie rod 21. The force point is transferred to the upper flange 19 to improve the strength, and the heat leakage is reduced by the G10 pull rod; one end of the G10 pull rod 21 is fixedly connected to the bottom wall of the upper flange 19 through a threaded connecting block, and a connecting block is fixedly provided on the outer wall of the liquid nitrogen dewar 10. The other end of the G10 pull rod 21 passes through the connecting block and is fastened to the pull rod upper nut 28 through the pull rod lower nut 29. Two handles 27 are also provided on the outside of the tank body to facilitate the equipment. An evacuation port 34 is provided on the top of the tank body, and the tank body can be evacuated through the evacuation port 34.

[0038] See Figure 1 and Figure 4 The injection port head assembly includes a PTFE upper head 14, a lower head 17, a safety valve 16, a capacitance level gauge 12, a nitrogen pipeline, and a liquid nitrogen pipeline. The nitrogen pipeline and the liquid nitrogen pipeline are respectively provided with a nitrogen outlet 24 and a liquid nitrogen injection port 26. The capacitance level gauge 12 extends into the liquid nitrogen tank. The top of the upper flange cover 2 is fixedly connected to the lower head 17. The lower head 17 is sealed with the PTFE upper head 14 through an O-ring and is fastened by four long screws. A pressure transmitter 25 is provided in the upper flange cover 2. The pressure transmitter The transmitter 25 is fixedly connected to the lower head 17. The pressure transmitter 25 is fixed to the lower head 17 through NPT threads to monitor the internal pressure. The safety valve 16, capacitance level gauge 12, nitrogen outlet 24 and liquid nitrogen injection port 26 are all integrated into the PTFE upper head 14 and are detachably connected to the PTFE upper head 14 for easy use and maintenance. A liquid level gauge display 15 is provided on the top of the upper flange cover 2. The liquid level gauge display 15 displays the liquid level measured by the capacitance level gauge 12. All of them are commercially available parts.

[0039] See Figure 3The liquid nitrogen dewar 10 is provided with a main neck tube bellows lower connecting groove 31, one end of the main neck tube bellows 20 is fixedly connected to the lower head 17 through the main bellows upper steel-aluminum joint 18, the stainless steel part of the main bellows upper steel-aluminum joint 18 is welded and fixed to the main neck tube bellows 20, and the other end of the main neck tube bellows 20 is welded and fixed to the main neck tube bellows lower connecting groove 31 through the main bellows lower steel-aluminum joint 22, the stainless steel part of the main bellows lower steel-aluminum joint 22 is welded to the main neck tube bellows 20, and the aluminum alloy part is welded to the main neck tube bellows. The lower connecting groove 31 of the bellows is welded and fixed, the aluminum alloy part of the main neck tube bellows 20 is welded and fixed to the lower head 17, the liquid nitrogen Dewar 10 is provided with a lower connecting groove 8 of the refrigerator bellows, the refrigerator stainless steel bellows 7 is welded and fixed to the upper flange 19 through the refrigerator upper steel-aluminum joint 6, the stainless steel part of the refrigerator upper steel-aluminum joint 6 is welded to the refrigerator stainless steel bellows 7, the aluminum alloy part of the lower connecting groove 8 of the refrigerator bellows is welded to the refrigerator lower steel-aluminum joint 9, and then welded and fixed to the refrigerator stainless steel bellows 7.

[0040] Except for the upper steel-aluminum joint 6 of the refrigerator, the stainless steel bellows 7 of the refrigerator, the lower steel-aluminum joint 9 of the refrigerator, the capacitance level gauge 12, the G10 axial stabilization block 13, the PTFE upper head 14, the level gauge display 15, the safety valve 16, and the G10 pull rod 21, the materials involved in the device are basically made of aluminum alloy 6061-T6, which effectively reduces the overall weight of the device.

[0041] See Figure 2 The refrigerator flange 4 is fixed to the top of the upper flange 19, and the refrigerator is fixed to the top of the refrigerator flange 4 through the shock-absorbing washer 5. The refrigerator is pressed on the refrigerator flange 4 through the shock-absorbing washer 5, and at the same time, the refrigerator cover 1 is fixed to the top of the upper flange cover 2 to increase the axial vibration of the refrigerator along the stroke.

[0042] See Figure 5 A heat dissipation baffle 32 and a heat dissipation fan 33 are provided on the top of the storage tank. The heat dissipation baffle 32 is located between the main neck tube bellows 20 and the refrigerator. The heat dissipation fan 33 is located outside the refrigerator. The heat dissipation fan 33 is fixed on the heat dissipation baffle 32 to cool the refrigerator. At the same time, the heat on the wall of the heat dissipation baffle 32 is transferred to the main neck tube to reduce heat leakage.

[0043] See Figure 6 The main force point of this device is fixed on the upper flange 19 through three G10 threaded rods (G10 pull rods 21) to pull the liquid nitrogen dewar 10. It has high strength. Compared with the traditional model, the force point is transferred to the upper flange 19 and the vacuum cylinder, which is more reliable. For force analysis, please refer to Figure 7 、 Figure 8The maximum stress is 57 MPa in the middle hole of the upper flange 19, which has a size of 424 x 13 mm. The maximum deformation is 0.6 mm. Considering the reinforcement of the weld, the actual deformation is less than 0.6 mm.

[0044] See Figure 2 A G10 axial stabilizing block 13 is provided on the inner wall of the bottom of the storage tank, and a slider adapted to the G10 axial stabilizing block 13 is provided on the bottom of the liquid nitrogen Dewar 10. The G10 axial stabilizing block does not contact the bottom wall of the liquid nitrogen Dewar 10, and only contacts during axial displacement. This can reduce heat leakage and play an axial positioning role. In conjunction with the three G10 pull rods 21, it effectively ensures the stability of the inner container.

[0045] The total theoretical heat leakage of the system from 77K to 300K is 0.48W, of which the heat leakage of the main neck tube bellows 20 is 0.05W; the heat leakage of the stainless steel bellows 7 of the refrigerator is 0.15W; the heat leakage of the detection rod of the capacitance liquid level gauge 12 is 0.24W; the radiation heat leakage is 0.017W, and it is wrapped with about 80 layers of insulation material; the total heat leakage of the three G10 pull rods 21 is 0.03W; and the 0.48W heat leakage vaporizes 0.26L of liquid nitrogen in one day. In actual continuous testing for five days, the static evaporation rate without detection rod load was 0.12L / d, corresponding to a heat leakage of about 0.23W, which can be regarded as zero evaporation of the system.

[0046]

[0047]

[0048]

[0049] ORTEC products of the same level have a no-load heat leakage of 3L / d.

[0050] A stainless steel rod measuring 38 x 2 and 488 mm long was used to simulate the detector's heat leakage. The theoretical heat leakage was 1.29 W. However, the actual heat leakage was approximately 1.5 W (approximately 0.8 L / d), including 0.23 W of static heat leakage. The actual heat leakage of the test rod was 1.27 W, a 1.6% difference from 1.29 W, demonstrating high accuracy.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection, characterized in that: The invention comprises a refrigerator, a liquid nitrogen dewar (10), a storage tank, and an injection port head assembly. A vacuum cavity (23) is provided in the storage tank. The liquid nitrogen dewar (10) is suspended in the vacuum cavity (23), and a gap is left between the bottom of the liquid nitrogen dewar (10) and the inner wall of the bottom of the storage tank. The injection port head assembly is connected to the liquid nitrogen dewar (10) through a main neck tube bellows (20) passing through the top of the tank body. The refrigerator is provided at the top of the tank body, and its cooling end is connected to the liquid nitrogen dewar (10) through a refrigerator stainless steel bellows (7). Both ends of the main neck tube bellows (20) are fixedly connected to the injection port head assembly and the liquid nitrogen dewar (10) through steel-aluminum joints. The two ends of the stainless steel bellows (7) of the refrigerator are respectively connected and fastened to the injection port head assembly and the liquid nitrogen dewar (10) through steel-aluminum joints; the storage tank includes a tank body, an upper flange (19), and a lower flange (30); the upper flange (19), the tank body, and the lower flange (30) are enclosed to form a closed cavity structure, and the upper flange (19) is fixedly connected to the liquid nitrogen dewar (10) through multiple G10 tie rods (21); one end of the G10 tie rod (21) is fixedly connected to the bottom wall of the upper flange (19) through a threaded connection block, and a connection block is fixedly provided on the outer wall of the liquid nitrogen dewar (10), and the other end of the G10 tie rod (21) passes through the connection block and is connected to the upper thread of the tie rod through the lower nut (29) of the tie rod. The female (28) is connected and fastened; an upper flange cover (2) is fixedly provided on the top of the storage tank, and the injection port head assembly includes a PTFE upper head (14) and a lower head (17); the top of the upper flange cover (2) is fixedly connected to the lower head (17), and the lower head (17) is fixedly connected to the PTFE upper head (14); a pressure transmitter (25) is provided in the upper flange cover (2), and the pressure transmitter (25) is fixedly connected to the lower head (17); the injection port head assembly also includes a safety valve (16) provided on the PTFE upper head (14), a capacitance level gauge (12), a nitrogen pipeline, and a liquid nitrogen pipeline, and the ends of the nitrogen pipeline and the liquid nitrogen pipeline are respectively provided with a nitrogen outlet (24) and a liquid nitrogen injection port (26), the capacitance level gauge (12) extends into the liquid nitrogen tank; it also includes a refrigerator cover (1), a refrigerator flange (4), and a shock-absorbing gasket (5), the refrigerator flange (4) is fixed to the top of the upper flange (19), the refrigerator is fixed to the top of the refrigerator flange (4) through the shock-absorbing gasket (5), and the refrigerator cover (1) is fixed to the top of the upper flange cover (2); the liquid nitrogen dewar (10) is provided with a refrigerator bellows lower connecting groove (8) that is compatible with the main neck tube bellows (20) and the steel-aluminum joint, the inner wall of the bottom of the storage tank is provided with a G10 axial stabilizing block (13), and the bottom of the liquid nitrogen dewar (10) is provided with a slider that is compatible with the G10 axial stabilizing block (13).

2. A zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection according to claim 1, characterized in that: One end of the main neck tube bellows (20) is fixedly connected to the injection port head assembly via a steel-aluminum joint (18) on the main bellows, the stainless steel portion of the steel-aluminum joint (18) on the main bellows is welded and fixed to the main neck tube bellows (20), and the aluminum alloy portion of the main neck tube bellows (20) is welded and fixed to the injection port head assembly.

3. The zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection according to claim 1, characterized in that: The main neck tube bellows (20) and the refrigerator stainless steel bellows (7) are made of 304 stainless steel with a wall thickness of 0.15 mm.

4. The zero-evaporation liquid nitrogen storage tank suitable for high-purity germanium detection according to claim 1, characterized in that: A heat dissipation baffle (32) and a heat dissipation fan (33) are provided on the top of the storage tank. The heat dissipation baffle (32) is located between the main neck tube bellows (20) and the refrigerator, and the heat dissipation fan (33) is located outside the refrigerator.

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