Liquid helium zero evaporation device

Abstract

The utility model relates to the technical field of liquid helium zero evaporation, in particular to a liquid helium zero evaporation device which comprises a liquid helium Dewar, a cold end and a helium refrigerator which are connected through a plurality of layers of vacuum heat insulation pipelines to form a closed circulation loop. A pressure sensor in the liquid helium Dewar is used for monitoring pressure, and the working state of the helium refrigerating machine is controlled through a pressure control valve; helium flows into the helium refrigerator through the cold end, is liquefied after being subjected to multi-stage heat exchange, compression, expansion refrigeration and J-T valve throttling and then flows back to the liquid helium Dewar, and zero evaporation in the liquid helium storage process is achieved. The device can be integrated on a liquid helium Dewar or a tank car, a compressor and a first-stage turbo expander, the second-stage turbo expander adopts an oil-free gas bearing system, and the device has the advantages of high efficiency, safety, no oil pollution and the like.

Description

Technical Field

[0001] This utility model relates to the field of liquid helium zero evaporation technology, and in particular to a liquid helium zero evaporation device. Background Technology

[0002] Helium is an indispensable rare strategic resource for the development of high-tech industries. Liquid helium has a temperature as low as -269 degrees Celsius, just above absolute zero, and is extremely easy to vaporize, requiring special storage devices. Therefore, efficient storage of liquid helium is crucial for ensuring supply and reducing costs. The main storage methods include liquid helium tanks and liquid helium dewars. Liquid helium tanks are currently the most widely used liquid helium storage and transportation carriers in the world. For example, CIMC Enric's liquid helium tanks can achieve seamless connection in the filling, transportation, and storage of liquid helium, and have advantages such as long-term non-destructive storage.

[0003] Because liquid helium has low latent heat, low density, high thermal conductivity and diffusivity, it is easily vaporized by heat. This will pressurize the storage equipment. When the pressure exceeds the allowable pressure, it needs to be released to reduce the pressure, resulting in a large loss and waste of liquid helium, which increases storage costs. At the same time, the reduction of liquid helium reserves will affect the operation of related equipment. For example, hospital MRI machines rely on liquid helium to maintain the low temperature of superconducting coils. Excessive evaporation of liquid helium may cause the equipment to malfunction. Utility Model Content

[0004] In order to overcome the problems of existing liquid helium equipment, which suffer from the problem that helium is easily evaporated due to its physical properties, resulting in a reduction in helium storage and equipment operation, thus increasing storage costs and affecting equipment operation, this utility model provides a liquid helium zero-evaporation device.

[0005] The technical solution is as follows: A liquid helium zero-evaporation device includes a liquid helium Dewar, a cold end, a helium refrigerator, and also includes multi-layer insulated vacuum pipes, a pressure sensor, and a pressure control valve; the helium refrigerator is installed outside the liquid helium Dewar; a multi-layer insulated vacuum pipe is installed between the liquid helium Dewar and the helium refrigerator; the input end of the liquid helium Dewar is provided with a cold end; the cold end is provided with a pressure control valve; the input end of the pressure control valve is provided with a pressure sensor; the cold end includes a cold end inlet, a cold end outlet, a cold end liquid inlet, and a cold end liquid outlet; the helium refrigerator includes a first heat exchanger, a second heat exchanger, a third heat exchanger, a compressor, a cooler, a first-stage turboexpander, a second-stage turboexpander, and a JT valve.

[0006] Furthermore, there are two multi-layered insulated vacuum pipes, which are respectively connected to the liquid helium Dewar as the input section and the output section; the pressure control valve is connected to the output section of the multi-layered insulated vacuum pipe; the pressure control valve is located inside the cold end.

[0007] Furthermore, a first heat exchanger is provided at the output end of the cold end air outlet; a second heat exchanger is provided at the output end of the first heat exchanger; a third heat exchanger is provided at the output end of the second heat exchanger; a compressor is provided at the output end of the third heat exchanger; and a cooler is provided at the output end of the compressor.

[0008] Furthermore, a first-stage turbine expander is installed between the second heat exchanger and the first heat exchanger; a second-stage turbine expander and a JT valve are installed between the first heat exchanger and the cold end liquid inlet, and the output end of the cooler is connected to the cold end liquid inlet in sequence through the third heat exchanger, the second heat exchanger, the first-stage turbine expander, the first heat exchanger, the second-stage turbine expander, and the JT valve.

[0009] Furthermore, helium gas enters the device from the cold end inlet, and liquid helium exits the device from the cold end outlet.

[0010] Furthermore, the compressor, first-stage turboexpander, and second-stage turboexpander in the helium refrigerator all use gas bearings to support the rotor system.

[0011] Furthermore, the upper and lower pressure limits of the pressure control valve are 0.5 MPa and 0.12 MPa, respectively. When the internal pressure of the liquid helium Dewar is higher than the upper pressure limit of the pressure control valve, the helium refrigerator starts at its rated power. When the internal pressure of the liquid helium Dewar is between the lower and upper limits of the pressure control valve, the helium refrigerator starts at a power lower than its rated power. When the internal pressure of the liquid helium Dewar is lower than the lower limit of the pressure control valve, the helium refrigerator stops operating.

[0012] The beneficial effects are as follows: Helium gas from the liquid helium Dewar flows into the helium refrigerator through the cold end inlet, passes through the heating channels of the first, second, and third heat exchangers to the compressor inlet, is compressed by the compressor, and then flows from the compressor outlet to the cooler. After passing through the cooler, it flows sequentially through the cooling channels of the third and second heat exchangers to the first-stage turbine expander for expansion and cooling, then through the cooling channel of the first heat exchanger to the second-stage turbine expander for expansion and cooling, and finally flows to the JT valve to produce liquid helium. Liquid helium then flows through the outlet pipe back to the liquid helium Dewar, completing one helium cycle. The pressure sensor is installed inside the liquid helium Dewar to monitor the internal pressure in real time. The helium refrigerator operates according to the internal pressure of the liquid helium Dewar, and the start and stop of the helium refrigerator are automatically controlled by the pressure control valve.

[0013] The pressure sensor of this invention monitors the pressure inside the liquid helium Dewar and reliquefies the helium gas based on the pressure value, thereby reducing the thermal leakage of helium gas and achieving efficient and safe storage during the liquid helium storage process.

[0014] This utility model device can be installed not only on liquid helium Dewars, but also on liquid helium tank trucks, improving the safety of liquid helium transportation.

[0015] The compressor, primary turbine expander, and secondary turbine expander of this invention adopt gas bearings, enabling the device to operate completely without oil throughout the entire working process, eliminating oil removal issues and the need for an oil return device. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0017] Figure 2 This is a schematic diagram of the helium refrigerator and cold end assembly processing flow of this utility model.

[0018] In the attached diagram, the following are the reference numerals: 1. Liquid helium Dewar; 2. Cold end; 3. Helium refrigerator; 4. Multi-layer insulated vacuum pipe; 5. Pressure sensor; 6. Pressure control valve; 201. Cold end inlet; 202. Cold end outlet; 203. Cold end liquid inlet; 204. Cold end liquid outlet; 31. First heat exchanger; 32. Second heat exchanger; 33. Third heat exchanger; 34. Compressor; 35. Cooler; 36. First-stage turbine expander; 37. Second-stage turbine expander; 38. JT valve. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] Example 1

[0021] like Figures 1-2 As shown, a liquid helium zero-evaporation device includes a liquid helium Dewar 1, a cold end 2, a helium refrigerator 3, and also includes a multi-layer insulated vacuum pipe 4, a pressure sensor 5, and a pressure control valve 6. The helium refrigerator 3 is installed outside the liquid helium Dewar 1. The multi-layer insulated vacuum pipe 4 is installed between the liquid helium Dewar 1 and the helium refrigerator 3. The cold end 2 is installed at the input end of the liquid helium Dewar 1. The pressure control valve 6 is installed inside the cold end 2. The pressure sensor 5 is installed at the input end of the pressure control valve 6. The cold end 2 includes a cold end inlet 201, a cold end outlet 202, a cold end liquid inlet 203, and a cold end liquid outlet 204. The helium refrigerator 3 includes a first heat exchanger 31, a second heat exchanger 32, a third heat exchanger 33, a compressor 34, a cooler 35, a first-stage turbine expander 36, a second-stage turbine expander 37, and a JT valve 38.

[0022] Two multi-layer insulated vacuum pipes 4 are provided, and the multi-layer insulated vacuum pipes 4 are respectively connected to the liquid helium Dewar 1 as the input section and the output section; the pressure control valve 6 is connected to the output section of the multi-layer insulated vacuum pipe 4; the pressure control valve 6 is located inside the cold end 2.

[0023] A first heat exchanger 31 is provided at the output end of the cold end outlet 202; a second heat exchanger 32 is provided at the output end of the first heat exchanger 31; a third heat exchanger 33 is provided at the output end of the second heat exchanger 32; a compressor 34 is provided at the output end of the third heat exchanger 33; and a cooler 35 is provided at the output end of the compressor 34.

[0024] A primary turbine expander 36 is provided between the second heat exchanger 32 and the first heat exchanger 31; a secondary turbine expander 37 and a JT valve 38 are provided between the first heat exchanger 31 and the cold end inlet 203, and the output end of the cooler 35 is connected to the cold end inlet 203 after passing through the third heat exchanger 33, the second heat exchanger 32, the primary turbine expander 36, the first heat exchanger 31, the secondary turbine expander 37, and the JT valve 38 in series.

[0025] Helium gas enters the device from the cold end inlet 201 of the cold end 2, and liquid helium is discharged from the cold end outlet 204 of the cold end 2.

[0026] The compressor 34, the first-stage turbine expander 36, and the second-stage turbine expander 37 in the helium refrigerator 3 all use gas bearings to support the rotor system.

[0027] Helium gas from the liquid helium dewar 1 flows into the helium refrigerator 3 through the inlet of the cold end 2. It then flows through the heating channels of the first heat exchanger 31, the second heat exchanger 32, and the third heat exchanger 33 to the inlet of the compressor 34. After compression by the compressor 34, it flows from the outlet of the compressor 34 to the cooler 35. After passing through the cooler 35, it flows sequentially through the cooling channels of the third heat exchanger 33 and the second heat exchanger 32 to the first-stage turbine expander 36 for expansion and cooling. Afterward, it flows through the cooling channel of the first heat exchanger 31 to the second-stage turbine expander 37 for further expansion and cooling before flowing to the JT valve 38, producing liquid helium. This liquid helium then flows through the outlet pipe back to the liquid helium dewar 1, completing one helium cycle. The pressure sensor 5 is installed inside the liquid helium dewar 1 to monitor the internal pressure in real time. The helium refrigerator 3 operates according to the internal pressure of the liquid helium dewar 1, and its start and stop are automatically controlled by the pressure control valve 6.

[0028] Example 2

[0029] Based on Example 1, such as Figures 1-2 As shown, the upper and lower pressure limits of pressure control valve 6 are 0.5 MPa and 0.12 MPa, respectively. When the internal pressure of liquid helium Dewar 1 is higher than the upper pressure limit of pressure control valve 6, helium refrigerator 3 starts at rated power. When the internal pressure of liquid helium Dewar 1 is between the lower and upper limits of pressure control valve 6, helium refrigerator 3 starts at lower than rated power. When the internal pressure of liquid helium Dewar 1 is lower than the lower limit of pressure control valve 6, helium refrigerator 3 stops operating.

[0030] The pressure sensor 5 of this invention monitors the internal pressure of the liquid helium Dewar 1 and reliquefies the helium gas according to the pressure value, thereby reducing the thermal leakage of helium gas and achieving efficient and safe storage during the liquid helium storage process. The compressor 34, the first-stage turbine expander 36, and the second-stage turbine expander 37 adopt gas bearings, and the device achieves completely oil-free operation throughout the entire working process, without oil removal problems or oil return devices.

Claims

1. A liquid helium zero-evaporation device, comprising a liquid helium Dewar (1), a cold end (2), and a helium refrigerator (3), characterized in that: It also includes a multi-layered insulated vacuum pipe (4), a pressure sensor (5), and a pressure control valve (6); a helium refrigerator (3) is installed outside the liquid helium Dewar (1); a multi-layered insulated vacuum pipe (4) is installed between the liquid helium Dewar (1) and the helium refrigerator (3); a cold end (2) is installed at the input end of the liquid helium Dewar (1); a pressure control valve (6) is installed inside the cold end (2); a pressure sensor (5) is installed at the input end of the pressure control valve (6); the cold end (2) includes a cold end inlet (201), a cold end outlet (202), a cold end liquid inlet (203), and a cold end liquid outlet (204); the helium refrigerator (3) includes a first heat exchanger (31), a second heat exchanger (32), a third heat exchanger (33), a compressor (34), a cooler (35), a first-stage turbine expander (36), a second-stage turbine expander (37), and a JT valve (38).

2. The liquid helium zero-evaporation apparatus according to claim 1, characterized in that: Two multi-layer insulated vacuum pipes (4) are provided, and the multi-layer insulated vacuum pipes (4) are respectively connected to the liquid helium Dewar (1) as the input section and the output section; the pressure control valve (6) is connected to the output section of the multi-layer insulated vacuum pipes (4); the pressure control valve (6) is located inside the cold end (2).

3. The liquid helium zero-evaporation apparatus according to claim 1, characterized in that: A first heat exchanger (31) is provided at the output end of the cold end outlet (202); a second heat exchanger (32) is provided at the output end of the first heat exchanger (31); a third heat exchanger (33) is provided at the output end of the second heat exchanger (32); a compressor (34) is provided at the output end of the third heat exchanger (33); and a cooler (35) is provided at the output end of the compressor (34).

4. The liquid helium zero-evaporation apparatus according to claim 3, characterized in that: A primary turbine expander (36) is provided between the second heat exchanger (32) and the first heat exchanger (31); a secondary turbine expander (37) and a JT valve (38) are provided between the first heat exchanger (31) and the cold end liquid inlet (203), and the output end of the cooler (35) is connected to the cold end liquid inlet (203) in sequence through the third heat exchanger (33), the second heat exchanger (32), the primary turbine expander (36), the first heat exchanger (31), the secondary turbine expander (37), and the JT valve (38).

5. The liquid helium zero-evaporation apparatus according to claim 1, characterized in that: Helium gas enters the device from the cold end inlet (201) of the cold end (2), and liquid helium is discharged from the cold end outlet (204) of the cold end (2).

6. The liquid helium zero-evaporation apparatus according to claim 3, characterized in that: The compressor (34) and the first-stage turbine expander (36) and the second-stage turbine expander (37) in the helium refrigerator (3) all adopt a gas bearing-supported rotor system.

7. The liquid helium zero-evaporation apparatus according to claim 1, characterized in that: The upper and lower pressure limits of the pressure control valve (6) are 0.5 MPa and 0.12 MPa, respectively. When the internal pressure of the liquid helium dewar (1) is higher than the upper pressure limit of the pressure control valve (6), the helium refrigerator (3) starts at the rated power. When the internal pressure of the liquid helium dewar (1) is between the lower and upper limits of the pressure control valve (6), the helium refrigerator (3) starts at a lower power. When the internal pressure of the liquid helium dewar (1) is lower than the lower limit of the pressure control valve (6), the helium refrigerator (3) stops running.

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