Air extraction system for carrying out local high-vacuum extraction in medium-vacuum environment

Abstract

The invention provides an air extraction system for local high-vacuum extraction in a medium-vacuum environment, which comprises a conduit arranged in the medium-vacuum environment and a high-vacuum air extraction device movably mounted on the conduit, the high-vacuum air extraction device is provided with a base body, a vacuum cavity communicated with the conduit is arranged in the base body, a helium plate is arranged on the cavity wall of the vacuum cavity, and the helium plate is connected with the conduit. The base body is connected with the helium closed system through a pipeline, the helium plate condenses, captures or adsorbs gas molecules entering the vacuum cavity to enable the vacuum cavity to form a high-vacuum environment, and the helium closed system refrigerates and cools the helium plate in the base body and circularly drives cooled helium; through the arrangement of the helium plate, the helium closed system is used for refrigerating and cooling the helium plate, the cold helium plate is used for condensing, trapping or adsorbing gas molecules in the vacuum cavity, and meanwhile, the helium closed system can also be used for helium circulation, so that the whole system forms a closed loop and is free of electromagnetic interference and oil pollution; and the purpose of performing high-vacuum extraction in a medium-vacuum environment is achieved.

Description

Technical Field

[0001] This invention relates to the field of vacuum pumping technology, and in particular to a pumping system for local high vacuum extraction in a medium vacuum environment. Background Technology

[0002] Existing vacuum extraction devices primarily rely on vacuum pumps, which utilize the exhaust gas from the pump to achieve the desired vacuum. Their key characteristic is that the gas in the container being pumped is expelled from the pump. Various types of vacuum pumps exist, each with its effective operating range. This is the most important method for obtaining a vacuum and the most basic pumping equipment.

[0003] Vacuum pumps are mainly classified into two categories: mechanical pumps and jet pumps. Mechanical pumps primarily include reciprocating vacuum pumps (dry and wet vacuum pumps) and water ring vacuum pumps. Jet pumps mainly consist of hydraulic jet pumps and steam jet pumps.

[0004] However, existing vacuum pumps are only used in atmospheric environments and cannot work in vacuum environments. Furthermore, due to equipment defects, they are prone to contaminating the vacuum environment.

[0005] In existing theories, although cryogenic pumps exist, they cannot operate in a vacuum environment or achieve higher vacuum levels, and their methods also cannot achieve high vacuum extraction.

[0006] To achieve a high vacuum, high vacuum extraction is required in a medium vacuum environment, which cannot be accomplished by existing vacuum pumps or conventional condensation methods. Summary of the Invention

[0007] This invention solves the problem that conventional vacuum pumps in the prior art cannot perform high vacuum extraction in a medium vacuum environment. It proposes a pumping system that performs local high vacuum extraction in a medium vacuum environment, thereby increasing the application scenarios of vacuum environments.

[0008] To achieve the above objectives, the following technical solution is proposed: a pumping system for local high vacuum extraction in a medium vacuum environment, comprising a conduit disposed in the medium vacuum environment and a high vacuum pumping device movably mounted on the conduit. The high vacuum pumping device is provided with a base, and a vacuum chamber is disposed within the base and communicates with the conduit. A helium plate is disposed on the wall of the vacuum chamber. The base is connected to a helium closed system through a pipeline. The helium plate condenses, captures, or adsorbs gas molecules entering the vacuum chamber to form a high vacuum environment in the vacuum chamber. The helium closed system cools the helium plate within the base and drives the circulation of cooling helium.

[0009] Preferably, the helium closed system includes a refrigeration circuit and a circulation circuit. The refrigeration circuit provides cold helium gas to the helium plate to maintain the operating temperature of the helium plate, and the circulation circuit provides power support for the cryogenic helium gas.

[0010] Preferably, the refrigeration circuit includes a refrigeration helium compressor, a refrigerator, and a heat exchanger. The refrigeration helium compressor is connected to the refrigerator via a helium tube, the refrigerator is connected to the heat exchanger, and the cold gas output end of the heat exchanger is connected to a high-vacuum pumping device via a cold pipe.

[0011] Preferably, the circulation loop includes a regenerator and a circulating helium compressor. The first inlet of the regenerator is connected to a high-vacuum pumping device, the first outlet of the regenerator is connected to the circulating helium compressor, the second inlet of the regenerator is connected to the circulating helium compressor, and the second outlet of the regenerator is connected to a refrigeration loop.

[0012] Preferably, the helium plate is provided with an adsorbent for adsorbing gas molecules.

[0013] Preferably, the high-vacuum pumping device is equipped with a vacuum gauge, which is used to detect the vacuum level of the vacuum chamber.

[0014] Preferably, the heat exchanger is made of a cooling copper block and a single layer of coiled pipes.

[0015] Preferably, the regenerator is a shell-and-tube countercurrent heat exchanger.

[0016] The beneficial effects of this invention are: by setting up a helium plate, the helium plate is cooled by a closed helium system, and the gas molecules in the vacuum chamber are condensed, captured or adsorbed by the cold helium plate. At the same time, the closed helium system can also circulate helium, so that the whole system forms a closed loop, without electromagnetic interference or oil pollution, and achieves the purpose of high vacuum extraction in a medium vacuum environment. Attached Figure Description

[0017] Figure 1 This is a simplified structural diagram of the air extraction system of Embodiment 1 of the present invention.

[0018] Figure 2 This is a simplified structural diagram of the helium closed system of Embodiment 1 of the present invention.

[0019] The components are: 1. conduit, 2. substrate, 3. vacuum chamber, 4. helium plate, 5. pipeline, 6. vacuum gauge, 7. refrigeration helium compressor, 8. refrigerator, 9. heat exchanger, 10. high vacuum pumping device, 11. regenerator, and 12. circulating helium compressor. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention, and not all embodiments. Based on the embodiments described in the embodiments, other embodiments obtained by those skilled in the art without creative effort are all within the protection scope of the present invention.

[0021] Example 1: A pumping system for localized high-vacuum extraction in a medium-vacuum environment, such as... Figure 1 and Figure 2 As shown, the device includes a conduit 1 positioned in a medium vacuum environment and a high vacuum pumping device 10 movably mounted on the conduit. The high vacuum pumping device has a base 2, within which a vacuum chamber 3 is located and communicates with the conduit. A helium plate 4 is mounted on the wall of the vacuum chamber. The base is connected to a helium closed-loop system via a pipeline 5. The helium plate condenses, traps, or adsorbs gas molecules entering the vacuum chamber, creating a high vacuum environment. The helium closed-loop system cools the helium plate within the base and drives the circulation of cooling helium. The medium vacuum environment referred to in this invention is the vacuum environment after vacuum extraction from the vacuum tank using a vacuum pump. In this invention, the vacuum level within the vacuum tank is <1.3 × 10⁻³ Pa.

[0022] The helium closed-loop system of the present invention includes a cooling circuit and a circulation circuit, wherein the cooling circuit provides cold helium gas to the helium plate to maintain the working temperature of the helium plate, and the circulation circuit provides power support for the cryogenic helium gas.

[0023] The refrigeration circuit includes a refrigeration helium compressor 7, a refrigerator 8, and a heat exchanger 9. The refrigeration helium compressor is connected to the refrigerator via helium pipes, and the refrigerator is connected to the heat exchanger. The cold gas output end of the heat exchanger is connected to the high-vacuum pumping device via cold pipes. The circulation circuit includes a regenerator 11 and a circulating helium compressor 12. The first inlet of the regenerator is connected to the high-vacuum pumping device, the first outlet of the regenerator is connected to the circulating helium compressor, the second inlet of the regenerator is connected to the circulating helium compressor, and the second outlet of the regenerator is connected to the refrigeration circuit. Hot helium is drawn in from the circulating helium compressor, exchanges heat with the cold helium transferred from the regenerator, and then enters the heat exchanger. The refrigeration helium compressor and the refrigerator provide cold helium, which undergoes a second heat exchange to form cold helium at a certain temperature, which is then transferred to the helium plates of the high-vacuum pumping device, bringing the helium plates to the corresponding operating temperature. The circulating helium compressor mainly provides helium circulation, accelerating the circulation of helium in the high-vacuum pumping device, while the refrigeration helium compressor is mainly used to provide cold helium.

[0024] The helium plate is equipped with an adsorbent for adsorbing gas molecules.

[0025] The high vacuum pumping device is equipped with a vacuum gauge 6, which is used to detect the vacuum level of the vacuum chamber. A hot cathode vacuum gauge is selected, and the vacuum gauge is thermally controlled.

[0026] The heat exchanger is made of a cooling copper block and a single layer of coiled pipes.

[0027] The regenerator uses a shell-and-tube counter-current heat exchanger.

[0028] The high vacuum level referred to in this invention is ≤5×10-6 Pa with load. The entire system is designed based on a magnetic shielding system to ensure no electromagnetic interference within the vacuum chamber. Equipment free from oil vapor pollution is selected to ensure no oil contamination within the vacuum chamber. The helium closed-loop system mainly involves low-temperature adsorption and condensation, eliminating vibration issues and having no impact on thermal control or the 100nT magnetic field. The specific details of the condensation, capture, or adsorption referred to in this invention are as follows: (1) Low temperature condensation: When gas molecules are injected into the pumping surface below its saturation temperature, they lose kinetic energy and continuously condense on the pumping surface to form a frost layer.

[0029] (2) Cryogenic trapping: While condensable gases form a frost layer on the low-temperature surface, non-condensable gas molecules are also buried and adsorbed. Typically, gases such as CO2, H2O, SO2, N2, Ar, and Ne first frost on the low-temperature surface to form an adsorption layer, thereby achieving the purpose of adsorbing other gases. At this time, most of the gas molecules in the vacuum chamber are condensed on the surface of the helium plate.

[0030] (3) Low-temperature adsorption: Low-temperature adsorption refers to the adsorption of gas by an adsorbent on a low-temperature surface. Due to the strong interaction between the adsorbent and gas molecules, the gas phase pressure can be lower than the saturated vapor pressure at the cold surface temperature. Activated carbon or molecular sieves are used as adsorbents. By utilizing the adsorbent, more gas molecules are further adsorbed, thereby further increasing the vacuum level in the vacuum chamber and achieving the purpose of local high vacuum.

[0031] To further verify the feasibility of this invention, the minimum pumping speed for localized high vacuum was calculated. The calculation method is as follows: the conductance formula under molecular flow conditions is: Where: d—diameter of the main pump's air intake pipe, mm; L—Length of the main pump's air intake pipe, in mm; C—Flow conductance of the evacuation pipeline between the main pump inlet and the vacuum container evacuation port, L / s; Since the pipe diameter and pipe length are known data, the specific value of the pipe conductance can be calculated.

[0032] The formula for the minimum pumping speed under molecular flow conditions is: Where: p1—local high vacuum degree, 10-6 Pa; it is the local high vacuum degree to be achieved by the present invention; p2—main tank vacuum degree (vacuum degree of medium vacuum environment), 10-3 Pa; S min —Minimum pumping speed under molecular flow conditions, L / s; According to calculations, the required local high vacuum level can be achieved based on its pumping speed.

[0033] The core of this invention lies in the use of a helium plate. After cooling the helium plate, gas molecules within the vacuum chamber are adsorbed through it. This is fundamentally different from the direct extraction by existing vacuum pumps and the condensation method of introducing gas for condensation. Vacuum pumps are limited by the inherent limitations of the equipment and cannot achieve further vacuum extraction. Condensation methods, which use gas condensation, are difficult to completely condense the gas molecules within the vacuum chamber, resulting in significant dispersion. In contrast, the helium plate of this invention covers the entire vacuum chamber, allowing for the condensation and adsorption of all gas molecules within it. Its condensation and adsorption capacity changes with the temperature of the helium plate. This allows the pumping system of this invention to freely control the vacuum level required for localized high vacuum, i.e., by controlling the temperature of the helium gas introduced into the substrate, the temperature of the helium plate is controlled, thereby controlling the vacuum level of the localized high vacuum.

[0034] Another aspect of this invention is that helium can be recycled. The cold helium entering the substrate mainly acts on the helium plate to cool it down, and the helium does not mix with the gas molecules in the vacuum chamber. Therefore, the gas extracted from the substrate outlet is still helium, not a mixed gas, which is different from the mixed gas in the condensation method and realizes the recycling of helium.

[0035] Based on this, the present invention uses a helium plate and a closed helium system to cool the helium plate. The cold helium plate condenses, captures, or adsorbs gas molecules in the vacuum chamber. At the same time, the closed helium system can also circulate helium, so that the entire system forms a closed loop, with no electromagnetic interference and no oil pollution, thus achieving the purpose of high vacuum extraction in a medium vacuum environment.

[0036] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention, but it should not be construed as limiting the specific implementation of the invention to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention.

Claims

1. A pumping system for localized high-vacuum extraction in a medium-vacuum environment, characterized in that, include: A conduit is set in a medium vacuum environment, and a high vacuum pumping device is movably mounted on the conduit. The high vacuum pumping device is provided with a base, and a vacuum chamber is provided in the base and communicates with the conduit. A helium plate is provided on the wall of the vacuum chamber. The base is connected to a helium closed system through pipelines. The helium plate condenses, captures or adsorbs gas molecules entering the vacuum chamber to form a high vacuum environment. The helium closed system cools the helium plate in the base and drives the circulation of cooling helium.

2. The pumping system for local high vacuum extraction in a medium vacuum environment according to claim 1, characterized in that, The closed-loop helium system includes a refrigeration circuit and a circulation circuit. The refrigeration circuit provides cold helium gas to the helium plate to maintain its operating temperature, and the circulation circuit provides power support for the cryogenic helium gas.

3. The pumping system for local high vacuum extraction in a medium vacuum environment according to claim 2, characterized in that, The refrigeration circuit includes a refrigeration helium compressor, a refrigerator, and a heat exchanger. The refrigeration helium compressor is connected to the refrigerator via a helium tube, the refrigerator is connected to the heat exchanger, and the cold gas output end of the heat exchanger is connected to a high vacuum pumping device via a cold pipe.

4. A pumping system for local high vacuum extraction in a medium vacuum environment according to claim 2 or 3, characterized in that, The circulation loop includes a regenerator and a circulating helium compressor. The first inlet of the regenerator is connected to a high-vacuum pumping device, the first outlet of the regenerator is connected to the circulating helium compressor, the second inlet of the regenerator is connected to the circulating helium compressor, and the second outlet of the regenerator is connected to a refrigeration loop.

5. A pumping system for local high vacuum extraction in a medium vacuum environment according to claim 1, characterized in that, The helium plate is provided with an adsorbent for adsorbing gas molecules.

6. The pumping system for local high vacuum extraction in a medium vacuum environment according to claim 1, characterized in that, The high-vacuum pumping device is equipped with a vacuum gauge, which is used to detect the vacuum level of the vacuum chamber.

7. A pumping system for local high vacuum extraction in a medium vacuum environment according to claim 3, characterized in that, The heat exchanger is made of a cooling copper block and a single layer of coiled pipes.

8. A pumping system for local high vacuum extraction in a medium vacuum environment according to claim 4, characterized in that, The regenerator is a shell-and-tube countercurrent heat exchanger.

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