A molecular pump set for evacuating a hydrogen isotope containing ultra-large chamber

Abstract

The application belongs to the technical field of tritium removal pump sets, and discloses a molecular pump set for evacuating a hydrogen isotope containing super-large chamber, which comprises a stainless steel sealed cavity and a super-large vacuum chamber, characterized in that: the inside of the stainless steel sealed cavity is provided with a tritium removal pump set one and a tritium removal pump set two through fixing frames respectively, the tritium removal pump set one and the tritium removal pump set two each comprise four tritium removal pumps, and the tritium removal pump set one and the tritium removal pump set two are in parallel connection and are in communication with the super-large vacuum chamber; the eight tritium removal pumps are installed in the stainless steel chamber, and the parallel connection and series connection connection mode is creatively adopted to adapt to the requirement of continuous evacuation of the large chamber. In the initial stage, the eight tritium removal pumps are in parallel connection to improve the overall pumping speed, and then four tritium removal pumps are used as front-stage pumps and four tritium removal pumps are used as main pumping pumps to improve the compression rate of the pumped tritium, increase the exhaust port pressure, and improve the tritium pumping efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of tritium removal pump sets, specifically a molecular pump set for evacuating ultra-large chambers containing hydrogen isotopes. Background Technology

[0002] A tritium vacuum pump is a special vacuum pump capable of removing tritium (3H) gas. Tritium, a radioactive isotope of hydrogen, exhibits beta decay and is primarily used in the nuclear industry, fusion experiments, and radiopharmaceutical production. These vacuum pumps must meet extremely high requirements for sealing, radiation resistance, and safety. Current tritium removal pumps, when using oil pumps to evacuate tritium-containing chambers, suffer from beta radiation that causes mineral oil to crack and carbonize, producing sludge that clogs the oil passages and reduces pumping speed by more than 30%.

[0003] The fluororubber seals inside diaphragm pumps can harden and crack under radiation, leading to seal failure. Because the reciprocating motion of the diaphragm generates significant heat during gas compression, high-speed diaphragm pumps require water cooling. However, the cooling water can be permeated with tritium to form tritium water (HTO), increasing its biohazard risk by 104 times and resulting in treatment costs exceeding ¥24,000 per cubic meter.

[0004] Ordinary scroll dry pumps are air-cooled, and the temperature rise exceeds 75°C during continuous evacuation of a large chamber, accelerating the aging of internal dynamic sealing components. During long-term operation, the seals of the vacuum pump may age, leading to minor leaks. Once a leak occurs, the leaked tritium cannot be collected and removed immediately, and timely warnings are impossible. Diaphragm pumps are unsuitable for removing tritium from large chambers due to their low pumping speed. The all-metal diaphragm of a diaphragm pump has a lifespan of 1000-3000 hours; replacing it with an imported diaphragm is not only expensive but also requires professional maintenance and after-sales personnel.

[0005] Based on the deficiencies of the prior art, this application proposes a molecular pump assembly for evacuating a large chamber containing hydrogen isotopes to overcome the aforementioned deficiencies. Summary of the Invention

[0006] To address the problems mentioned in the background section, this invention provides a molecular pump assembly for evacuating ultra-large chambers containing hydrogen isotopes, which has the advantages of long service life and no need for maintenance.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a molecular pump assembly for evacuating a large chamber containing hydrogen isotopes, comprising a stainless steel sealed cavity and a large vacuum chamber. Inside the stainless steel sealed cavity, a tritium removal pump assembly one and a tritium removal pump assembly two are respectively installed via a fixing frame. Both tritium removal pump assembly one and tritium removal pump assembly two include four tritium removal pumps. The tritium removal pump assembly one and tritium removal pump assembly two are arranged in parallel and are both connected to the large vacuum chamber. Pneumatic angle valves two and three are respectively installed at the inlet and outlet of each tritium removal pump in tritium removal pump assembly one to control their on / off states. Pneumatic angle valves five and six are respectively installed at the inlet and outlet of each tritium removal pump in tritium removal pump assembly two to control their on / off states.

[0008] Among them, the pneumatic angle valve three of the detritium pump in detritium pump group one and the pneumatic angle valve five of the detritium pump in detritium pump group two are connected in series through pipelines.

[0009] The connection between the ultra-large vacuum chamber and the first tritium removal pump group is controlled by a pneumatic angle valve, and the connection between the second tritium removal pump group and the ultra-large vacuum chamber is controlled by a pneumatic angle valve.

[0010] The first tritium removal pump unit is connected to an external tritium removal pipeline and is equipped with a pneumatic angle valve four to control its on / off state. The second tritium removal pump unit is connected to an external tritium removal pipeline and is equipped with a pneumatic angle valve six to control its on / off state.

[0011] Preferably, a tritium concentration detector is installed in the stainless steel sealed cavity, a nitrogen tank connected to the inside of the cavity is installed outside the stainless steel sealed cavity and its on / off state is controlled by a pneumatic angle valve seven, and a tritium removal pump three is installed on the tritium removal pipeline outside the stainless steel sealed cavity. The tritium removal pump three is connected to the inner cavity of the stainless steel sealed cavity and its on / off state is controlled by a pneumatic angle valve eight.

[0012] Preferably, an air conditioning system is installed in the stainless steel sealed cavity, and the outdoor unit of the air conditioning system is located outside the stainless steel sealed cavity.

[0013] Preferably, the stainless steel sealed cavity is provided with an air duct, which is connected to the air inlet of each of the tritium removal pumps in the first and second tritium removal pump groups. The air inlet of the air duct is connected to the air conditioning system. The air duct and the tritium removal pumps are connected by a three-way valve.

[0014] The stainless steel sealed cavity is equipped with a second air duct. The second air duct is connected to the outlet of each tritium removal pump in the first and second tritium removal pump groups. A three-way valve is installed between the outlet of the tritium removal pump and the second air duct, and the valve controls the opening and closing of the pump.

[0015] Preferably, a branch pipe is connected to the second air duct, the branch pipe extends downward and its opening faces each tritium removal pump body.

[0016] Preferably, the mounting bracket of the tritium removal pump is also provided with a surrounding plate, which encloses the tritium removal pump and is configured as an open ring; the opening of the branch pipe is located on the open ring side of the surrounding plate; and several air grooves are provided on the opposite side of the open ring side of the surrounding plate.

[0017] Preferably, the enclosure further includes several partitions that are slidably installed on the outside of the enclosure, with each partition fixedly connected to the others. A guide rod is installed on the enclosure, and the partitions are vertically sleeved on the guide rod. An elastic member is also provided at the bottom of each partition, which elastically pushes the partition upward.

[0018] Preferably, an air cylinder is provided on the enclosure plate, the piston rod of the air cylinder is connected to the partition plate, and the exhaust end of the tritium removal pump is connected to the rod chamber of the air cylinder and controlled by a pneumatic angle valve.

[0019] Preferably, the bottom partition has locking feet at both ends, and the bottom of the partition has a locking groove, so that the locking groove can be directly engaged when the partition moves down to the bottom.

[0020] Preferably, the length and width of the partition are just enough to cover the air slot. In the initial state, the partition is located above the air slot, making the air slot open.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention integrates eight tritium removal pumps within a stainless steel chamber, employing a novel parallel-series connection method to accommodate the continuous evacuation requirements of a large chamber. Initially, the eight pumps operate in parallel to increase the overall pumping speed, rapidly reducing the pressure within the large chamber to below 1000 Pa. Subsequently, four pumps serve as forestage pumps, and the remaining four act as main pumps, increasing the compressibility of the extracted tritium, raising the exhaust pressure, and enhancing tritium removal efficiency, thus preparing for subsequent collection and purification.

[0023] Due to the specific application scenario, this invention adopts a redundant and maintenance-free design scheme. This means that throughout the entire operating cycle of the pump unit, a faulty pump can be directly shut down or switched to the auxiliary circuit without disassembling the metal casing, ensuring operator safety. The pump unit's normal operating time is ≥16,000 hours.

[0024] This invention employs an oil-free tritium removal pump, with the pump chamber and piping made of 316L stainless steel with aluminum plating, eliminating the risk of lubricant contamination. Furthermore, all sealing parts in contact with gas utilize all-metal seals (copper gaskets, VCR gaskets, hexagonal sealing rings, and C-type sealing rings), completely preventing leakage due to seal failure.

[0025] This invention employs air conditioning for cooling. A glove box-specific air conditioner is installed inside the sealed chamber, which can rapidly cool the room while ensuring the leakage rate of the sealed chamber meets requirements, thus preventing tritium leakage. Furthermore, after the faulty tritium removal pump is identified, its inlet and outlet ports are shut off, and it is then directed to the cold air duct. By closing the air slots in the enclosure, a regional cooling range is established for targeted cooling, allowing the faulty tritium removal pump to still be fully utilized. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the pipeline structure according to the first embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the second embodiment of the present invention;

[0028] Figure 3 This is a top view of the structure of the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of the present invention on the right side;

[0030] Figure 5 For the present invention Figure 4 Enlarged diagram of part A in the middle;

[0031] Figure 6 This is a schematic diagram of the left side of the structure of the present invention.

[0032] In the diagram: 100, Stainless steel sealed cavity; 200, Ultra-large vacuum chamber; 300, Tritium concentration detector; 400, Nitrogen tank; 500, Air conditioning system; 600, Tritium removal pump set one; 700, Tritium removal pump set two; 801, Pneumatic angle valve one; 802, Pneumatic angle valve two; 803, Pneumatic angle valve three; 804, Pneumatic angle valve four; 805, Pneumatic angle valve five; 806, Pneumatic angle valve... Valve 6; 807, Pneumatic Angle Valve 7; 808, Pneumatic Angle Valve 8; 809, Pneumatic Angle Valve 9; 810, Three-Way Valve 1; 811, Three-Way Valve 2; 900, Tritium De-pump 3; 10, Air Duct 1; 20, Air Duct 2; 21, Branch Pipe; 30, Enclosure Panel; 31, Air Slot; 32, Partition Plate; 321, Clip; 322, Slot; 33, Guide Rod; 34, Elastic Component; 35, Air Cylinder. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The first embodiment, as follows Figure 1As shown, this invention provides a molecular pump assembly for evacuating a large chamber containing hydrogen isotopes, comprising a stainless steel sealed cavity 100 and a large vacuum chamber 200. Inside the stainless steel sealed cavity 100, a tritium removal pump assembly 600 and a tritium removal pump assembly 700 are respectively mounted via a fixing frame. Both the tritium removal pump assembly 600 and the tritium removal pump assembly 700 include four tritium removal pumps. The tritium removal pump assembly 600 and the tritium removal pump assembly 700 are arranged in parallel and are all connected to the large vacuum chamber 200. Pneumatic angle valves 802 and 803 are respectively installed at the inlet and outlet of each tritium removal pump in the tritium removal pump assembly 600 to control their on / off states. The inlet and outlet of each tritium removal pump in the tritium removal pump assembly 700 are... Pneumatic angle valves 805 and 806 are respectively installed at the ports to control their on / off states. Specifically, pneumatic angle valve 803 of the detritium pump in detritium pump group 1 600 is connected in series with pneumatic angle valve 805 of the detritium pump in detritium pump group 2 700 through a pipeline. The ultra-large vacuum chamber 200 is connected to detritium pump group 1 600 through pneumatic angle valve 802, and the detritium pump group 2 700 is connected to ultra-large vacuum chamber 200 through pneumatic angle valve 801. Detritium pump group 1 600 is connected to an external detritium removal pipeline and is controlled by pneumatic angle valve 804. Detritium pump group 2 700 is connected to an external detritium removal pipeline and is controlled by pneumatic angle valve 806.

[0035] like Figure 1 and 2 As shown, a tritium concentration detector 300 is installed inside the stainless steel sealed cavity 100. A nitrogen tank 400, connected to the interior of the cavity, is located outside the stainless steel sealed cavity 100 and its on / off state is controlled by a pneumatic angle valve 807. A tritium removal pump 900 is installed on the tritium removal pipeline outside the stainless steel sealed cavity 100, and the tritium removal pump 900 is connected to the interior of the stainless steel sealed cavity 100 and its on / off state is controlled by a pneumatic angle valve 808. An air conditioning system 500 is installed inside the stainless steel sealed cavity 100, and the outdoor unit of the air conditioning system 500 is located outside the stainless steel sealed cavity 100.

[0036] In the above embodiments, the vacuum pump system for transferring tritium-containing gas from an ultra-large chamber can be quickly used to rapidly evacuate the chamber, rapidly reducing the pressure inside to below 100 Pa, and compressing and transferring the extracted tritium to meet industrial-scale tritium purification and separation requirements. This significantly shortens tritium recovery time, improves tritium recovery efficiency, and greatly reduces the risk of tritium leakage. No opening maintenance is required throughout the entire MTBF, ensuring safety during the tritium extraction and transfer process. The nitrogen tank 400 is isolated from the stainless steel sealed chamber 100 by a pneumatic angle valve 807. The outdoor unit of the air conditioning system 500 is connected to the air box via a metal feedthrough flange, ensuring the airtightness of the stainless steel sealed chamber 100. A tritium concentration detector 300 is installed inside the chamber and communicates with an external PLC via the feedthrough flange to monitor the tritium content within the stainless steel sealed chamber 100. A pressure gauge is installed outside the chamber and sealed to the chamber by a copper gasket for pressure monitoring during gas replacement. The tritium removal pump 3900 is connected to the stainless steel sealed cavity 100 via a pneumatic angle valve 808.

[0037] When the first stage requires rapid evacuation of the large chamber, pneumatic angle valves 1 (801), 2 (802), 4 (804), 5 (805), and 6 (806) open, and all eight tritium removal pumps start simultaneously to quickly evacuate the chamber. In the second stage, when the remaining tritium in the chamber needs efficient compression, pneumatic angle valves 1 (801) and 4 (804) close, and pneumatic angle valve 3 (803) opens. The tritium undergoes two stages of compression before being centrally discharged. In energy-saving mode, tritium removal pump group 1 (600) and tritium removal pump group 2 (700) can be arranged to work alternately to extend the system's lifespan.

[0038] When the tritium concentration detector 300 detects that the tritium concentration in the stainless steel sealed cavity 100 exceeds the threshold, the control system will shut down all tritium removal pumps. Open pneumatic angle valve 7 807 to introduce nitrogen from nitrogen tank 400 into the stainless steel sealed cavity 100. Open tritium removal pump 3 900 and pneumatic angle valve 808 to purge and replace the gas. After completion, close pneumatic angle valves 7 807, 808, and 900. Then, use a binary search method to locate the tritium removal pump with a sealing problem. Once the problematic pump is found, permanently close pneumatic angle valves 2 802 and 3 803, or pneumatic angle valves 5 805 and 6 806 at both ends of the pump. Discontinue use of this pump; no cavity opening or maintenance is required.

[0039] The second embodiment, as follows Figures 2-6As shown, a duct 10 is installed in the stainless steel sealed cavity 100. The duct 10 is connected to the air inlet of each tritium removal pump in the tritium removal pump group 600 and the tritium removal pump group 700. The air inlet of the duct 10 is connected to the air conditioning system 500. The connection between the duct 10 and the tritium removal pump is controlled by a three-way valve 810. A duct 20 is installed in the stainless steel sealed cavity 100. The duct 20 is connected to the air outlet of each tritium removal pump in the tritium removal pump group 600 and the tritium removal pump group 700. A three-way valve 811 is installed between the air outlet of the tritium removal pump and the duct 20 and is used to control the connection.

[0040] A branch pipe 21 is connected to the second duct 20. The branch pipe 21 extends downward and its opening faces each tritium removal pump body.

[0041] When a tritium leak is detected and the corresponding problematic pump is identified, the valves at both the inlet and outlet of the pump are closed. However, the pump will simultaneously participate in the operation of the auxiliary pipeline, i.e., the three-way valves 810 and 811 on the pump will switch their conduction directions. Under normal operating conditions of each detritium removal pump, the conduction direction of three-way valve 810 is to connect the pipeline between pneumatic angle valve 802 and the inlet of the detritium removal pump, or between pneumatic angle valve 805 and the inlet of the detritium removal pump. The conduction direction of three-way valve 811 is to connect pneumatic angle valve 803 and the outlet of the detritium removal pump, or between pneumatic angle valve 806 and the outlet of the detritium removal pump. The aforementioned switching of conduction directions means that three-way valve 810 connects duct 10 and the inlet of the detritium removal pump, and three-way valve 811 connects duct 20 and the outlet of the detritium removal pump.

[0042] Therefore, a passage is formed between duct 10 and duct 20 through the faulty tritium removal pump. The air inlet flange of duct 10 is connected to the air box of the air conditioning system 500. The air outlet of duct 20 is divided into 8 outlets, which are extended to each tritium removal pump through branch pipe 21. The cold air in the air box will be directly transported through duct 10 and duct 20 to the surface of the pump body by the faulty tritium removal pump. The original wide-area cooling is switched to regional cooling, which enhances the cooling effect and realizes the subsequent effective utilization of the pump. Moreover, the sealing requirements of the faulty tritium removal pump are not high, and it is easy to meet the pumping and discharge requirements.

[0043] The third embodiment, as Figures 2-6The mounting bracket for the tritium removal pump shown also includes a surrounding plate 30, which encloses the pump and is arranged in an open-loop configuration. The opening of the branch pipe 21 is located on the open-loop side of the surrounding plate 30. Several air grooves 31 are formed on the opposite side of the open-loop side of the surrounding plate 30. The surrounding plate 30 also includes several partitions 32 that are slidably installed outside the surrounding plate 30. The partitions 32 are fixedly connected to each other. A guide rod 33 is installed on the surrounding plate 30, and the partitions 32 are vertically sleeved on the guide rod 33. An elastic element 34 is also provided at the bottom of the partition 32, which elastically supports the partition 32 upwards. An air cylinder 35 is provided on the surrounding plate 30. The piston rod of the air cylinder 35 is connected to the partition 32. The exhaust end of the tritium removal pump is connected to the rod chamber of the air cylinder 35 and the connection and disconnection are controlled by a pneumatic angle valve 809. The bottom partition 32 has locking feet 321 at both ends, and the bottom of the surrounding plate 30 has a locking groove 322. When the partition 32 moves down to the bottom, the locking groove 322 can be directly engaged. The length and width of the partition 32 are just enough to cover the air groove 31. In the initial state, the partition 32 is located above the air groove 31, making the air groove 31 open.

[0044] In this embodiment, to enhance the regional cooling effect and reduce the irregular diffusion of cold air within the regional cooling range, an open-loop enclosure 30 is installed around each pump. A branch pipe 21 extends from one side of the open loop to blow air onto the tritium removal pump. Although the opposite side is enclosed, an air groove 31 is provided on it for ventilation in the initial wide-area cooling state, thereby enhancing the diffusion of cold air.

[0045] When the faulty tritium removal pump is used as a delivery pump in the auxiliary pipeline, the air trough 31 needs to be closed to ensure the concentration of cold air in the refrigeration system. This is achieved by shutting off the pneumatic angle valves 2 (802), 3 (803), 5 (805), and 6 (806) at the inlet and outlet of each tritium removal pump, and switching on the three-way valve 2 (811) and pneumatic angle valve 9 (809). Air is injected into the rod chamber of the corresponding air cylinder 35 of each tritium removal pump, pushing the baffle 32 downwards. The downward movement of the baffle 32 compresses the elastic element 34, eventually reaching the bottom. The locking feet 321 on the baffle 32 are engaged by the locking grooves 322, locking their position. At this point, the baffle 32 seals the air trough 31.

[0046] Then close the three-way valve 2811 and pneumatic angle valve 9809 (excluding the tritium pump), and open the pneumatic angle valve 2802, pneumatic angle valve 3803 or pneumatic angle valve 5805 and pneumatic angle valve 6806.

[0047] At this point, the faulty tritium removal pump delivers cold air to the enclosure 30 of each tritium removal pump in the cooling pipeline, achieving centralized area cooling and improving cooling efficiency.

[0048] Working principle and usage process of this invention:

[0049] When the first stage requires rapid evacuation of the large chamber, pneumatic angle valves 1 (801), 2 (802), 4 (804), 5 (805), and 6 (806) open, and all eight tritium removal pumps start simultaneously to quickly evacuate the chamber. In the second stage, when the remaining tritium in the chamber needs efficient compression, pneumatic angle valves 1 (801) and 4 (804) close, and pneumatic angle valve 3 (803) opens. The tritium undergoes two stages of compression before being centrally discharged. In energy-saving mode, tritium removal pump group 1 (600) and tritium removal pump group 2 (700) can be arranged to work alternately to extend the system's lifespan.

[0050] When the tritium concentration detector 300 detects that the tritium concentration in the stainless steel sealed cavity 100 exceeds the threshold, the control system will shut down all detritium pumps. Pneumatic angle valve 7 807 is opened to introduce nitrogen from nitrogen tank 400 into the stainless steel sealed cavity 100. Detritium pump 3 900 and pneumatic angle valve 808 are then opened to purge and replace the gas. After completion, pneumatic angle valves 7 807 and 808 and detritium pump 3 900 are closed. A binary search method is then used to locate the detritium pump with a sealing problem.

[0051] The faulty tritium removal pump is connected to the cold air duct, and the air slots on the enclosure 30 are closed to create a local cooling zone. The faulty pump delivers cold air to the cooling zones of each tritium removal pump in a directional manner, reducing the irregular diffusion area of ​​cold air, further improving the cooling effect, making reasonable use of the faulty pump, and extending the service life of the entire device.

[0052] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A molecular pump assembly for evacuating an ultra-large chamber containing hydrogen isotopes, comprising a stainless steel sealed cavity (100) and an ultra-large vacuum chamber (200), characterized in that: Inside the stainless steel sealed cavity (100), a tritium removal pump group one (600) and a tritium removal pump group two (700) are respectively installed by a fixing frame. Both the tritium removal pump group one (600) and the tritium removal pump group two (700) include four tritium removal pumps. The tritium removal pump group one (600) and the tritium removal pump group two (700) are arranged in parallel and are both connected to the ultra-large vacuum chamber (200). The inlet and outlet of each tritium removal pump in the first tritium removal pump group (600) are respectively equipped with pneumatic angle valve 2 (802) and pneumatic angle valve 3 (803) to control the on / off state. The inlet and outlet of each tritium removal pump in the second tritium removal pump group (700) are respectively equipped with pneumatic angle valve 5 (805) and pneumatic angle valve 6 (806) to control the on / off state. Among them, the pneumatic angle valve three (803) of the detritium pump in the first detritium pump group (600) and the pneumatic angle valve five (805) of the detritium pump in the second detritium pump group (700) are connected in series through pipelines. The connection between the ultra-large vacuum chamber (200) and the first tritium removal pump group (600) is controlled by a pneumatic angle valve (802), and the connection between the second tritium removal pump group (700) and the ultra-large vacuum chamber (200) is controlled by a pneumatic angle valve (801). The first detritium pump group (600) is connected to an external detritium pipeline and is equipped with a pneumatic angle valve four (804) to control its on / off state; the second detritium pump group (700) is connected to an external detritium pipeline and is equipped with a pneumatic angle valve six (806) to control its on / off state. A tritium concentration detector (300) is installed in the stainless steel sealed cavity (100), and an air conditioning system (500) is installed in the stainless steel sealed cavity (100). The outdoor unit of the air conditioning system (500) is located outside the stainless steel sealed cavity (100). The stainless steel sealed cavity (100) is provided with a duct (10), which is connected to the air inlet of each tritium pump in the first tritium pump group (600) and the second tritium pump group (700). The air inlet of the duct (10) is connected to the air conditioning system (500). The duct (10) and the tritium pump are connected by a three-way valve (810). The stainless steel sealed cavity (100) is provided with a second air duct (20), which is connected to the outlet of each tritium removal pump of the first tritium removal pump group (600) and the second tritium removal pump group (700). A three-way valve (811) is provided between the outlet of the tritium removal pump and the second air duct (20) and is used to control the opening and closing of the air duct. The second air duct (20) is connected to a branch pipe (21), which extends downward and has its opening facing each tritium removal pump body.

2. A molecular pump assembly for evacuating a large chamber containing hydrogen isotopes according to claim 1, characterized in that: The stainless steel sealed cavity (100) is provided with a nitrogen tank (400) that communicates with the inside of the cavity and is controlled by a pneumatic angle valve seven (807). A tritium removal pump three (900) is provided on the tritium removal pipeline outside the stainless steel sealed cavity (100). The tritium removal pump three (900) communicates with the inner cavity of the stainless steel sealed cavity (100) and is controlled by a pneumatic angle valve eight (808).

3. A molecular pump assembly for evacuating a large chamber containing hydrogen isotopes according to claim 2, characterized in that: The mounting bracket of the detritium pump is also provided with a surrounding plate (30), which contains the detritium pump and is set in an open loop; the opening of the branch pipe (21) is located on the open loop side of the surrounding plate (30); several air grooves (31) are opened on the opposite side of the open loop side of the surrounding plate (30).

4. A molecular pump assembly for evacuating a large chamber containing hydrogen isotopes according to claim 3, characterized in that: The enclosure (30) also includes several partitions (32) that are slidably installed on the outside of the enclosure (30). Each partition (32) is fixedly connected to the other. A guide rod (33) is installed on the enclosure (30). The partitions (32) are vertically sleeved on the guide rod (33). An elastic member (34) is also provided at the bottom of the partition (32). The elastic member (34) elastically pushes the partition (32) upward.

5. A molecular pump assembly for evacuating a large chamber containing hydrogen isotopes according to claim 4, characterized in that: An air cylinder (35) is provided on the enclosure (30). The piston rod of the air cylinder (35) is connected to the partition (32). The exhaust end of the tritium removal pump is connected to the rod chamber of the air cylinder (35) and the on / off state is controlled by the pneumatic angle valve (809).

6. A molecular pump assembly for evacuating a large chamber containing hydrogen isotopes according to claim 5, characterized in that: Both ends of the partition (32) located at the bottom are provided with locking feet (321), and the bottom of the enclosure (30) is provided with a locking groove (322). When the partition (32) moves down to the bottom, the locking groove (322) can be directly snapped into the locking groove (322).

7. A molecular pump assembly for evacuating a large chamber containing hydrogen isotopes according to any one of claims 4-6, characterized in that: The length and width of the partition (32) are just enough to cover the air groove (31). In the initial state, the partition (32) is located above the air groove (31), making the air groove (31) open.

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