Two-stage cryogenic vacuum pump

Abstract

The present application relates to the technical field of vacuum apparatuses, and especially to a two-stage cryogenic vacuum pump, comprising a pump body and a pressurizing assembly, wherein a liquid-filling cavity is formed inside the pump body; and the pressurizing assembly comprises a cylinder, a movable member and a liquid discharge member. The cylinder is coaxially located in the liquid-filling cavity, the cylinder is divided into a first-stage cylinder and a second-stage cylinder, one end of the first-stage cylinder is connected to the pump body, and the inner diameter of the second-stage cylinder is smaller than that of the first-stage cylinder. The movable member comprises a piston rod, a first-stage safety valve and a liquid output valve, wherein the piston rod sequentially passes through the pump body, the first-stage cylinder and the second-stage cylinder, and the piston rod slides back and forth in the axial direction of the pump body; the piston rod, the first-stage safety valve and the first-stage cylinder form a first-stage compression cavity; an injection port is provided at the end of the first-stage cylinder close to the second-stage cylinder; the piston rod, the liquid output valve and the second-stage cylinder form a second-stage compression cavity; and a flow channel hole is provided inside the piston rod. The liquid discharge member comprises a liquid discharge pipe and a liquid discharge valve, wherein one end of the liquid discharge pipe is in communication with the second-stage compression cavity, and the other end of the liquid discharge pipe is located outside the pump body. The present application has the effect of facilitating the cleaning of impurities.

Description

A two-stage cryogenic vacuum pump Technical Field

[0001] This application relates to the field of vacuum equipment technology, and in particular to a two-stage cryogenic vacuum pump. Background Technology

[0002] Krypton and xenon, as important industrial gases, occupy a key position in national economic development. In recent years, with the booming development of fields such as electronic chips, building doors and windows, satellites, and aerospace and military industries, the demand for krypton and xenon gases has shown a rapid growth trend both domestically and internationally. Against this backdrop, many large and extra-large air separation units have been equipped with krypton and xenon refining centers. As a high-pressure liquid oxygen pump in the crude krypton and xenon extraction system, the krypton and xenon pump plays an indispensable role in the entire krypton and xenon extraction process. It compresses the liquid oxygen initially concentrated in the krypton-lean tower and transports it to the vaporizer for vaporization.

[0003] In existing technologies, krypton-xenon products are primarily extracted from byproducts of air separation units. Currently, conventional high-pressure liquid oxygen pumps utilize ordinary cryogenic piston pumps. In the entire krypton-xenon extraction process, this pump compresses the initially concentrated liquid oxygen in the krypton-lean column and sends it to the vaporizer for vaporization. However, during the krypton-xenon concentration process, harmful impurities such as hydrocarbons and nitrous oxide are also concentrated. Ordinary cryogenic piston pumps do not account for the content of hydrocarbons and nitrous oxide in the lean krypton-xenon solution. When the impurity content is too high, a supersaturated state occurs, leading to precipitation and posing a significant safety hazard. This makes it impossible to remove the impurities, thus failing to effectively solve the problems caused by impurities during the krypton-xenon extraction process. Summary of the Invention

[0004] To address the problem of the inability to remove impurities, this application provides a two-stage cryogenic vacuum pump.

[0005] The two-stage cryogenic vacuum pump provided in this application adopts the following technical solution.

[0006] A two-stage cryogenic vacuum pump includes a pump body and a pressurization assembly. The pump body has a liquid filling chamber inside and an inlet for injecting liquid oxygen.

[0007] The pressurization assembly includes a cylinder, a movable component, and a discharge component. The cylinder is located within the filling chamber and is coaxially arranged with the pump body. The cylinder consists of a primary cylinder and a secondary cylinder communicating with the primary cylinder. One end of the primary cylinder is connected to the pump body, and the secondary cylinder is coaxially connected to the other end of the primary cylinder. The inner diameter of the secondary cylinder is smaller than that of the primary cylinder. The movable component includes a piston rod, a primary safety valve, and a discharge valve. The piston rod is coaxially arranged with the pump body and passes sequentially through the pump body, the primary cylinder, and the secondary cylinder. The piston rod is along the axial direction of the pump body. The piston rod slides back and forth. The primary safety valve is installed at one end of the piston rod inside the primary cylinder. The piston rod is located at the end of the primary safety valve away from the secondary cylinder. The primary safety valve and the primary cylinder form a primary compression chamber. An injection port is opened at the end of the primary cylinder near the secondary cylinder. The discharge valve is installed at one end of the piston rod inside the secondary cylinder. The end of the piston rod near the secondary cylinder, the discharge valve, and the secondary cylinder form a secondary compression chamber. A flow channel hole is provided inside the piston rod to connect the primary compression chamber and the secondary compression chamber.

[0008] The draining component includes a drain pipe and a drain valve. The drain pipe is located inside the pump body, with one end connected to the secondary compression chamber and the other end located outside the pump body. The drain valve is installed on the drain pipe.

[0009] By adopting the above technical solution, the two-stage compression structure can pressurize liquid oxygen, increasing the pump pressure. The first-stage safety valve ensures the safety of the pressure within the first-stage compression chamber, the outlet valve controls the liquid flow, and the discharge component discharges the pressurized liquid. As the piston rod moves away from the second-stage cylinder, the first-stage safety valve moves synchronously with the piston rod, thereby compressing and pressurizing the liquid oxygen within the first-stage compression chamber. When the pressure within the first-stage compression chamber exceeds the preset pressure value, the first-stage safety valve activates, releasing the excess pressure. After pressurization, the liquid is forced into the second-stage compression chamber through the flow channel orifice, ensuring pump safety and increasing the inlet pressure of the second-stage compression chamber, preventing CH4 condensation at the inlet and increasing the solubility of N2O. The liquid oxygen is discharged from the pump along with the pump, reducing wear on the piston rod, cylinder, and packing seals, and mitigating the risk of combustion and explosion caused by frictional heat in the liquid oxygen medium. Simultaneously, it improves the cavitation resistance of the pump's second-stage compression chamber. When the piston rod moves close to the secondary cylinder, the liquid in the secondary compression chamber is compressed and pressurized. When the pressure exceeds the pipeline delivery pressure, the drain valve is opened, and the liquid is delivered through the drain pipe. This facilitates pressurization of liquid oxygen, improves the solubility of impurities, and allows the liquid to be discharged from the pump body along with the medium through the drain pipe, ensuring safety and facilitating the removal of impurities.

[0010] In one specific implementation, a drain assembly is also included, which includes a drain pipe located at the bottom of the pump body, with one end extending to the lowest liquid level in the pump body and the other end extending out of the pump body.

[0011] By adopting the above technical solution, one end of the drain pipe extends to the lowest liquid level in the pump body, which can periodically discharge solid impurity particles located at the bottom of the liquid oxygen to a safe area, avoiding the danger caused by the accumulation of impurity particles at the bottom of the pump blocking the flow channel, and at the same time reducing the risk of solid particles damaging the pump sealing components.

[0012] In one specific implementation, the pressurization assembly further includes a piston component located inside the secondary cylinder and comprising multiple piston rings. The multiple piston rings are spaced apart along the length of the piston rod. The outer wall of the piston rod is provided with multiple placement grooves for the piston rings spaced apart along its length. Each piston ring corresponds to one of the placement grooves. The piston rings are coaxially and fixedly bonded to the piston rod. The outer wall of the piston rings is in contact with the inner wall of the secondary cylinder.

[0013] The piston assembly is located inside the secondary cylinder. Multiple piston rings are spaced apart along the length of the piston rod in placement grooves. The piston rings are coaxially mounted and fixedly bonded to the piston rod, with the outer wall of the piston rings contacting the inner wall of the secondary cylinder. The reciprocating motion of the piston rod pressurizes liquid oxygen in the primary and secondary compression chambers. Pressurization in the primary compression chamber prevents CH4 condensation and increases the solubility of N2O, allowing it to be pumped out of the pump along with the liquid oxygen medium. This reduces wear on the piston rod, cylinder, and packing seals, as well as the risk of combustion and explosion caused by frictional heat generation in the liquid oxygen medium. It also improves the cavitation resistance at the inlet of the secondary compression chamber. A primary safety valve ensures pressure safety in the primary compression chamber. The pressurization in the secondary compression chamber meets operational requirements, and the piston rings seal the high-pressure liquid within the secondary compression chamber, improving the pump's efficiency in pressurizing liquid oxygen.

[0014] In one specific implementation, the pressurization assembly further includes a guide member, which is a guide ring located inside the secondary cylinder. The piston rod has a receiving groove for the guide ring inside the secondary cylinder. The guide ring is coaxially fixed to the piston rod, and the outer wall of the guide ring contacts the inner wall of the secondary cylinder.

[0015] By adopting the above technical solution, the guide ring can ensure that the piston rod remains concentric with the cylinder during its movement. The two-stage cryogenic vacuum pump has a two-stage compression structure, thus utilizing the reciprocating motion of the piston rod to pressurize liquid oxygen in the first and second stage compression chambers. A first-stage safety valve ensures the pressure safety of the first-stage compression chamber, and a liquid outlet valve controls the liquid flow, facilitating piston rod movement.

[0016] In one specific implementation scheme, the pump body includes a first pump body, a second pump body, and a first sealing element. Both the first pump body and the second pump body are hollow inside. One end of the first pump body is provided with a connection hole for the second pump body to be inserted. The second pump body is divided into an integrally formed insertion section and a fixed section. Both ends of the insertion section are open. The insertion section is inserted into the connection hole. The outer wall of the insertion section is in contact with the inner wall of the first pump body. The first pump body is connected to the fixed section. The end of the first-stage cylinder away from the second-stage cylinder is connected to the first pump body.

[0017] The first sealing element includes a second sealing ring, which is coaxially located at the end of the fixed section, and the first pump body abuts against the second sealing ring at one end near the fixed section.

[0018] By adopting the above technical solution, the pump body is divided into a first pump body and a second pump body, with the insertion section of the second pump body inserted into the connection hole of the first pump body. The inner walls of the two are in close contact, providing the main load-bearing structure for the pump. The first stage cylinder is connected to the first pump body, facilitating the installation of the pressurization assembly. The second sealing ring of the first sealing element is located at the end of the fixed section and abuts against the first pump body, sealing the connection between the first and second pump bodies, ensuring the stability and sealing of the overall pump body structure, and preventing media leakage.

[0019] In one specific implementation, the first seal further includes a first sealing ring. The insertion section is coaxially provided with an annular groove at one end near the middle of the first pump body. The first sealing ring is located in the annular groove. The first sealing ring is coaxially arranged with the insertion section. The first sealing ring is fixed to the insertion section and contacts the inner wall of the first pump body.

[0020] By adopting the above technical solution, based on the combination structure of the first pump body and the second pump body, a first sealing ring that contacts the inner wall of the first pump body is set in the annular groove of the plug section, which can seal the connection between the first pump body and the second pump body, prevent medium leakage, and ensure the sealing performance of the overall pump body structure.

[0021] In one specific implementation, a sealing assembly is further included, the sealing assembly comprising a packing seal located between the piston rod and the first pump body, the packing seal comprising a plurality of sealing rings distributed along the length of the piston rod, the sealing rings being coaxially arranged with the piston rod, the sealing rings being fixed to the first pump body, and the inner wall of the sealing rings contacting the piston rod.

[0022] By adopting the above technical solution, the medium can be prevented from leaking into the air along the piston rod, thereby improving the sealing performance.

[0023] In one specific implementation, the packing seal further includes a sealing frame located at one end of the sealing ring near the interior of the first pump body. The sealing frame is arranged circumferentially along the piston rod and fixed to the first pump body. The sealing frame uses a low-temperature resistant packing seal.

[0024] By adopting the above technical solutions, setting up a sealing frame and using low-temperature resistant packing seals, the sealing performance and low-temperature resistance of the sealing components can be improved, thereby preventing media leakage and improving the overall sealing performance of the pump.

[0025] In one specific implementation, the bottom of the first pump body is provided with an air inlet near the packing seal, and the top of the first pump body is provided with an air outlet near the packing seal to discharge excess sealing gas and prevent pressure buildup. The air inlet is connected to an external dry gas source, and the dry gas blows through the packing seal assembly in a direction perpendicular to the piston rod axis.

[0026] In one specific implementation, the pump body further includes a fixing component, which includes multiple fixing bolts and multiple nuts. The multiple fixing bolts are evenly distributed around the fixing section. The fixing bolts are sequentially threaded to the fixing section, the second sealing ring, and the first pump body. The nuts correspond one-to-one with the fixing bolts and are connected to the end of the fixing bolt away from the first pump body.

[0027] By adopting the above technical solution, the nut and bolt are connected to the end of the bolt away from the first pump body, thereby fixing the first pump body and the second pump body and ensuring the stability of the overall structure of the pump body.

[0028] In summary, this application includes the following beneficial technical effects:

[0029] The designed two-stage cryogenic vacuum pump features a two-stage compression structure that pressurizes liquid oxygen, increasing the pump's pressure. The first-stage chamber pressurization prevents CH4 condensation before the second-stage chamber inlet, increasing N2O solubility and allowing it to be discharged along with the liquid oxygen. This reduces wear on the piston rod, cylinder, and packing seals, as well as the risk of combustion and explosion due to frictional heat in the liquid oxygen medium. It also improves the cavitation resistance at the pump's second-stage compression chamber inlet. A first-stage safety valve ensures pressure safety within the first-stage compression chamber, while a discharge valve controls liquid flow. A drain valve discharges the pressurized liquid. In the second-stage compression chamber, the liquid is compressed and pressurized; when the pressure exceeds the pipeline delivery pressure, the drain valve opens, and the liquid is discharged through the drain pipe. Attached Figure Description

[0030] Figure 1 is a perspective view of the two-stage cryogenic vacuum pump of this application.

[0031] Figure 2 is a cross-sectional view from the first perspective of this application.

[0032] Figure 3 is a partial schematic diagram of the piston rod of this application.

[0033] Figure 4 is an enlarged view of part A in Figure 2.

[0034] Figure 5 is a cross-sectional view from a second perspective of this application.

[0035] Figure 6 is an enlarged view of part B in Figure 5.

[0036] Explanation of reference numerals in the attached drawings: 1. Pump body; 11. First pump body; 111. Connecting hole; 112. Drain port; 113. Air inlet; 114. Air outlet; 12. Second pump body; 121. Insert section; 1211. Annular groove; 122. Fixing section; 13. First seal; 131. First sealing ring; 132. Second sealing ring; 14. Fixing component; 141. Fixing bolt; 142. Nut; 15. Liquid inlet; 16. Liquid inlet pipe; 2. Pressurization assembly; 21. Cylinder; 211. First stage cylinder; 2111. First stage compression chamber; 2112. Injection... 212. Inlet; 212. Secondary cylinder; 2121. Secondary compression chamber; 22. Moving part; 221. Piston rod; 2211. Flow channel hole; 2212. Receiving tank; 2213. Placement tank; 222. Primary safety valve; 223. Discharge valve; 224. Drive source; 23. Drainage component; 231. Drainage pipe; 232. Drainage valve; 24. Guide component; 25. Piston component; 251. Piston ring; 3. Sealing assembly; 31. Packing seal; 311. Sealing ring; 312. Sealing frame; 4. Drainage assembly; 41. Drainage pipe; 42. Sealing cover. Detailed Implementation

[0037] The present application will be further described below with reference to Figures 1-6.

[0038] This application discloses a two-stage cryogenic vacuum pump.

[0039] Referring to Figures 1 and 2, a two-stage cryogenic vacuum pump includes a pump body 1 and a pressurization assembly 2 disposed within the pump body 1.

[0040] Referring to Figures 1, 2, and 3, the pump body 1 includes a first pump body 11, a second pump body 12, a first seal 13, and a fixing member 14. The first pump body 11 and the second pump body 12, as the main load-bearing components of the pump, are both cast from high-strength stainless steel. Both the first pump body 11 and the second pump body 12 are hollow inside. One end of the first pump body 11 has a connecting hole 111, which communicates with the internal cavity of the first pump body 11. The second pump body 12 is divided into an integrally formed insertion section 121 and a fixing section 122. Both ends of the insertion section 121 are open. The insertion section 121 is inserted into the connecting hole 111, so that its outer wall fits against the inner wall of the first pump body 11. An annular groove 1211 is provided at the end of the insertion section 121 near the middle of the first pump body 11.

[0041] Referring to Figures 1 and 2, the first sealing element 13 includes a first sealing ring 131 and a second sealing ring 132. The first sealing ring 131 is located within the annular groove 1211 and is coaxially fixedly connected to the insertion section 121 via a flange. The first sealing ring 131 contacts the inner wall of the first pump body 11, thereby sealing the connection between the first pump body 11 and the second pump body 12. The second sealing ring 132 is coaxially located at the end of the fixed section 122, and the end of the first pump body 11 near the fixed section 122 abuts against the second sealing ring 132. The fixing element 14 includes a plurality of fixing bolts 141 and a plurality of nuts 142, with the plurality of fixing bolts 141 evenly distributed circumferentially along the fixed section 122. The fixing bolts 141 are sequentially threadedly connected to the fixed section 122, the second sealing ring 132, and the first pump body 11. The nuts 142 correspond one-to-one with the fixing bolts 141, and the nuts 142 are threadedly connected to the end of the fixing bolt 141 away from the first pump body 11. The first pump body 11 and the second pump body 12 can be fixed by the cooperation of the fixing bolt 141 and the nut 142.

[0042] Referring to Figures 2, 3, and 4, the pressurization assembly 2 includes a cylinder 21, a movable component 22, a drain component 23, a guide component 24, and a piston component 25. The first pump body 11 and the second pump body 12 are internally connected to form a liquid filling chamber. The first pump body 11 has a liquid inlet 15, which communicates with the liquid filling chamber. A liquid inlet pipe 16 is connected to the pump body 1 at the liquid inlet 15. The liquid inlet pipe 16 is welded to the first pump body 11 and is used to inject liquid oxygen into the liquid filling chamber. The cylinder 21 is located within the liquid filling chamber and consists of a primary cylinder 211 and a secondary cylinder 212, which are integrally coaxially connected. One end of the primary cylinder 211 is an open end, facing away from the second pump body 12. The primary cylinder 211 is fixedly connected to the first pump body 11 by screws. The secondary cylinder 212 is located at the end of the primary cylinder 211 near the second pump body 12 and communicates with the primary cylinder 211. The inner diameter of the secondary cylinder 212 is smaller than the inner diameter of the primary cylinder 211.

[0043] Referring to Figures 2 and 3, the movable component 22 includes a piston rod 221, a primary safety valve 222, a liquid outlet valve 223, and a drive source 224. The piston rod 221 is coaxial with the first pump body 11 and passes sequentially through the first pump body 11, the primary cylinder 211, and the secondary cylinder 212, and is slidably connected to them, thereby reciprocating along the axial direction of the first pump body 11. The piston rod 221 may be made of high-strength alloy steel and its surface is hardened and chrome-plated to improve its hardness and wear resistance. The primary safety valve 222 is located inside the primary cylinder 211 and is fixedly connected to the piston rod 221 with screws. The piston rod 221, the primary safety valve 222, and the primary cylinder 211 form a primary compression chamber 2111. An injection port 2112 for liquid oxygen is provided at the end of the primary cylinder 211 near the secondary cylinder 212. The liquid outlet valve 223 is located inside the secondary cylinder 212 and is fixedly connected to one end of the piston rod 221 inside the secondary cylinder 212 with screws. The piston rod 221, the outlet valve 223, and the secondary cylinder 212 form a secondary compression chamber 2121. The piston rod 221 has an internal flow channel 2211, which connects the primary compression chamber 2111 and the secondary compression chamber 2121 for liquid flow. The outlet valve 223 can be a spring-loaded check valve. The first pump body 11 is connected to the drive source 224 via a bolt assembly. The drive source 224 is connected to the end of the piston rod 221 furthest from the second pump body 12 to drive the piston rod 221 in reciprocating motion. The drive source 224 can be a motor-driven crank-connecting rod mechanism to convert the motor's rotational motion into the reciprocating motion of the piston rod 221, or it can be driven by hydraulic or other methods.

[0044] Referring to Figures 2 and 3, the drain component 23 includes a drain pipe 231 and a drain valve 232. The drain pipe 231 is located inside the first pump body 11. One end of the drain pipe 231 is close to the secondary cylinder 212 and communicates with the secondary compression chamber 2121, while the other end communicates with the drain port 112 provided on the first pump body 11. The drain valve 232 is a one-way valve, which is fixedly connected to the drain pipe 231 by a flange. When the piston rod 221 moves away from the second pump body 12, the primary safety valve 222 closes and moves synchronously with the piston rod 221, thereby compressing and pressurizing the liquid oxygen located in the primary compression chamber 2111. When the pressure in the primary compression chamber 2111 exceeds the preset pressure value (0.6 MPa(G)), the primary safety valve 222 opens to release the excess pressure. After being pressurized, the liquid is forced into the secondary compression chamber 2121 through the flow channel 2211. This ensures pump safety and increases the inlet pressure of the secondary compression chamber 2121, thereby improving its cavitation resistance. When the piston rod 221 moves close to the second pump body 12, the outlet valve 223 closes under the action of the spring and fluid force, and the liquid in the secondary compression chamber 2121 is compressed and pressurized. When the pressure exceeds the pipeline delivery pressure, the drain valve 232 opens, and the liquid is delivered through the drain pipe 231. At the same time, the primary compression chamber 2111 reopens, and new medium enters the primary compression chamber 2111, repeating the previous cycle. By setting up secondary pressurization, it is convenient to pressurize liquid oxygen, which is beneficial to improving the solubility of impurities. At atmospheric pressure, the melting point of CH4 is -182.5℃. When the medium temperature is below -182.5℃, CH4 has the risk of condensation. When the pump inlet pressure is ≥0.106MPa(A), the risk of CH4 condensation can be eliminated. At atmospheric pressure, N2O has a melting point of -91℃. When the medium temperature is below -91℃, N2O is at risk of condensation. In practical engineering applications, it is necessary to control the N2O impurity content as much as possible. Therefore, to address the risk of CH4 and N2O condensation in the krypton-xenon extraction system, a two-stage compression structure is adopted to increase the inlet pressure of the pump's second-stage chamber. The pressure in the first-stage compression chamber 2111 can be increased by up to 0.6 MPa(G), preventing CH4 condensation at the inlet of the second-stage compression chamber 2121, improving the solubility of N2O, and ensuring safety.

[0045] Referring to Figures 2 and 4, the guide member 24 is a guide ring located inside the secondary cylinder 212. The piston rod 221 has a receiving groove 2212 for the guide ring inside the secondary cylinder 212. The guide ring is fixedly bonded to the piston rod 221 and coaxially arranged with it. The outer wall of the guide ring contacts the inner wall of the secondary cylinder 212, thereby ensuring that the piston rod 221 remains concentric with the cylinder 21 during movement. The piston member 25 is located inside the secondary cylinder 212 and on the side of the guide ring away from the primary cylinder 211. The piston member 25 includes multiple piston rings 251 spaced apart along the length of the piston rod 221. The outer wall of the piston rod 221 has multiple placement grooves 2213 spaced apart along its length. The piston rings 251 are located in the placement grooves 2213 one-to-one. The piston rings 251 are coaxially fixedly bonded to the piston rod 221. The outer wall of piston ring 251 contacts the inner wall of secondary cylinder 212, thereby sealing the liquid in secondary compression chamber 2121.

[0046] Referring to Figures 5 and 6, the two-stage cryogenic vacuum pump further includes a sealing assembly 3 and a drain assembly 4, both disposed within the pump body 1. The sealing assembly 3 includes a packing seal 31, located between the piston rod 221 and the first pump body 11, for sealing the liquid in the first-stage compression chamber 2111. The packing seal 31 includes multiple sealing rings 311 and a sealing frame 312. The multiple sealing rings 311 are distributed along the length of the piston rod 221 at the end of the piston rod 221 away from the second pump body 12. The sealing rings 311 are coaxially arranged with the piston rod 221 and fixedly bonded to the first pump body 11. The inner wall of the sealing rings 311 contacts the piston rod 221. The sealing frame 312 is circumferentially arranged around the piston rod 221 at the end of the piston rod 221 near the first pump body 11. The sealing frame 312 is fixedly connected to the first pump body 11 by screws. The sealing frame 312 can be filled with cryogenic packing, providing good sealing performance and cryogenic resistance.

[0047] Referring to Figure 5, to further ensure the lifespan and effectiveness of the packing seal, an air inlet 113 is provided at the bottom of the first pump body 11 near the packing seal 31, and an air outlet 114 is provided at the top of the first pump body 11 near the packing seal 31. The air inlet 113 is connected to an external dry gas source, which can be an inert gas such as nitrogen. The dry gas blows the packing seal assembly 3 in a direction perpendicular to the axis of the piston rod 221. Before the pump is started, the dry gas enters the packing seal 31 through the air inlet 113 to blow it clean. This serves two purposes: firstly, to dry the water vapor that has seeped into the packing seal, preventing the water vapor from freezing and damaging the packing seal 31 after the low-temperature medium enters the pump; secondly, when there is a slight leakage of the medium and the equipment cannot be stopped immediately, as long as the sealing gas pressure is increased to a level higher than the pressure of the pump's first-stage compression chamber 2111, the liquid in the first-stage compression chamber 2111 can be sealed under the action of pressure difference, improving the sealing performance and service life of the sealing assembly. At the same time, the air outlet 114 can discharge excess sealing gas to prevent pressure buildup.

[0048] Referring to Figure 5, the drain assembly 4 includes a drain pipe 41 and a sealing cap 42. The drain pipe 41 is located at the bottom connection between the first pump body 11 and the second pump body 12. One end of the drain pipe 41 extends to the lowest liquid level inside the pump body 1, and the other end is sealed by the sealing cap 42, which is threadedly connected to the drain pipe 41. The drain pipe 41 is inclined and its outlet direction faces a safe area. Although the primary compression chamber 2111 can increase the solubility of N2O, it cannot completely eliminate the condensation of N2O. Since the liquid density of N2O is ≥1229.5 kg / m³... 3 The density of liquid oxygen is 1141 kg / m³. 3 Since the density of N2O solid particles is higher than that of liquid oxygen, the solid particles are distributed at the bottom of the liquid oxygen layer. This design facilitates the periodic discharge of impurity particles to a safe area, preventing impurity particles from accumulating at the bottom of the pump and clogging the flow channel, which could cause danger. It also reduces the risk of solid particles damaging the pump's sealing components.

[0049] The implementation principle of the two-stage cryogenic vacuum pump in this embodiment is as follows: The two-stage cryogenic vacuum pump, through the sealed and fixed design of the pump body 1, ensures the stability and sealing of the overall structure, preventing media leakage. The two-stage compression structure of the pressurization assembly 2 utilizes the reciprocating motion of the piston rod 221 to pressurize liquid oxygen in the primary compression chamber 2111 and the secondary compression chamber 2121. The primary compression chamber 2111 effectively increases the inlet pressure of the secondary compression chamber 2121, preventing CH4 condensation and increasing the solubility of N2O, thereby sending it out of the pump along with the liquid oxygen medium. This reduces the wear of the piston rod, cylinder, and packing seal, and the risk of combustion and explosion caused by frictional heat generation in the liquid oxygen medium. Simultaneously, it improves the anti-cavitation performance at the inlet of the secondary compression chamber 2121. The primary safety valve 222 ensures the safety of the pressure within the primary compression chamber 2111, the liquid outlet valve 223 controls the flow of liquid, and the drain component 23 discharges the pressurized liquid, effectively increasing the pump pressure, preventing CH4 condensation, and increasing the solubility of N2O. The packing seal 31 and dry gas purging design of the sealing assembly 3 prevent media leakage and improve sealing performance and service life. The drain assembly 4 promptly discharges impurity particles, preventing them from accumulating at the bottom of the pump and reducing the risk of damage to the pump's sealing components. Compared to traditional cryogenic vacuum pumps, it offers significant improvements in sealing performance, pressurization capacity, and impurity handling capabilities, better meeting the needs of industrial production for the transportation and handling of cryogenic media.

[0050] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A two-stage cryogenic vacuum pump, characterized in that: It includes a pump body (1) and a pressurizing assembly (2). The pump body (1) has a liquid filling chamber inside and a liquid oxygen inlet (15) is provided on the pump body (1). The pressurization assembly (2) includes a cylinder (21), a movable part (22), and a draining part (23). The cylinder (21) is located in the liquid filling chamber and is coaxially arranged with the pump body (1). The cylinder (21) is divided into a primary cylinder (211) and a secondary cylinder (212) communicating with the primary cylinder (211). One end of the primary cylinder (211) is connected to the pump body (1), and the secondary cylinder (212) is coaxially connected to the other end of the primary cylinder (211). The inner diameter of the secondary cylinder (212) is smaller than that of the primary cylinder (211). The movable part (22) includes a piston rod (221), a primary safety valve (222), and a liquid outlet valve (223). The piston rod (221) is coaxially arranged with the pump body (1). The piston rod (221) passes through the pump body (1), the primary cylinder (211), and the secondary cylinder (212) in sequence. The piston rod (221) is along the axial direction of the pump body (1). The piston rod (221) slides back and forth, with the first-stage safety valve (222) installed at one end of the piston rod (221) inside the first-stage cylinder (211). The piston rod (221) is located at the end of the first-stage safety valve (222) away from the second-stage cylinder (212). The first-stage safety valve (222) and the first-stage cylinder (211) form a first-stage compression chamber (2111). An injection port (21) is provided at the end of the first-stage cylinder (211) near the second-stage cylinder (212). 12) The outlet valve (223) is installed at one end of the piston rod (221) inside the secondary cylinder (212). The piston rod (221) near the end of the secondary cylinder (212), the outlet valve (223) and the secondary cylinder (212) form a secondary compression chamber (2121). The piston rod (221) is provided with a flow channel hole (2211) that connects the primary compression chamber (2111) and the secondary compression chamber (2121). The drain component (23) includes a drain pipe (231) and a drain valve (232). The drain pipe (231) is located inside the pump body (1). One end of the drain pipe (231) is connected to the secondary compression chamber (2121), and the other end is located outside the pump body (1). The drain valve (232) is installed on the drain pipe (231).

2. The two-stage cryogenic vacuum pump according to claim 1, characterized in that: It also includes a sewage discharge assembly (4), which includes a sewage discharge pipe (41) located at the bottom of the pump body (1). One end of the sewage discharge pipe (41) extends to the lowest liquid level inside the pump body (1), and the other end extends out of the pump body (1).

3. The two-stage cryogenic vacuum pump according to claim 1, characterized in that: The pressurizing assembly (2) further includes a piston (25), which is located inside the secondary cylinder (212) and includes a plurality of piston rings (251). The plurality of piston rings (251) are spaced apart along the length of the piston rod (221). The outer wall of the piston rod (221) is provided with a plurality of placement grooves (2213) for the piston rings (251) spaced apart along its length. The piston rings (251) correspond one-to-one with the placement grooves (2213). The piston rings (251) are coaxially fixedly bonded to the piston rod (221), and the outer wall of the piston rings (251) is in contact with the inner wall of the secondary cylinder (212).

4. The two-stage cryogenic vacuum pump according to claim 3, characterized in that: The pressurizing assembly (2) also includes a guide (24), which is a guide ring located inside the secondary cylinder (212). The piston rod (221) has a receiving groove (2212) for the guide ring inside the secondary cylinder (212). The guide ring is coaxially fixed to the piston rod (221), and the outer wall of the guide ring contacts the inner wall of the secondary cylinder (212).

5. The two-stage cryogenic vacuum pump according to claim 1, characterized in that: The pump body (1) includes a first pump body (11), a second pump body (12), and a first sealing element (13). The first pump body (11) and the second pump body (12) are both hollow inside. One end of the first pump body (11) is provided with a connecting hole (111) for the second pump body (12) to be inserted. The second pump body (12) is divided into an integrally formed insertion section (121) and a fixed section (122). Both ends of the insertion section (121) are open. The insertion section (121) is inserted into the connecting hole (111). The outer wall of the insertion section (121) is in contact with the inner wall of the first pump body (11). The first pump body (11) is connected to the fixed section (122). The end of the first stage cylinder (211) away from the second stage cylinder (212) is connected to the first pump body (11). The first seal (13) includes a second sealing ring (132), which is coaxially located at the end of the fixed section (122), and the first pump body (11) abuts against the second sealing ring (132) at one end near the fixed section (122).

6. The two-stage cryogenic vacuum pump according to claim 5, characterized in that: The first sealing element (13) further includes a first sealing ring (131). The insertion section (121) is provided with an annular groove (1211) coaxially at one end near the middle of the first pump body (11). The first sealing ring (131) is located in the annular groove (1211). The first sealing ring (131) is coaxially arranged with the insertion section (121). The first sealing ring (131) is fixed with the insertion section (121). The first sealing ring (131) is in contact with the inner wall of the first pump body (11).

7. The two-stage cryogenic vacuum pump according to claim 5, characterized in that: It also includes a sealing assembly (3), which includes a packing seal (31) located between the piston rod (221) and the first pump body (11). The packing seal (31) includes a plurality of sealing rings (311) distributed along the length of the piston rod (221). The sealing rings (311) are coaxially arranged with the piston rod (221) and fixed to the first pump body (11). The inner wall of the sealing rings (311) is in contact with the piston rod (221).

8. The two-stage cryogenic vacuum pump according to claim 7, characterized in that: The packing seal (31) further includes a sealing frame (312), which is located at one end of the sealing ring (311) near the inside of the first pump body (11). The sealing frame (312) is arranged circumferentially along the piston rod (221) and is fixed to the first pump body (11). The sealing frame (312) uses a low-temperature resistant packing seal (31).

9. The two-stage cryogenic vacuum pump according to claim 8, characterized in that: The first pump body (11) has an air inlet (113) at the bottom near the packing seal (31), and an air outlet (114) at the top near the packing seal (31) to discharge excess sealing gas and prevent pressure buildup. The air inlet (113) is connected to an external dry gas source, and the dry gas blows the packing seal assembly (3) in a direction perpendicular to the axis of the piston rod (221).

10. The two-stage cryogenic vacuum pump according to claim 5, characterized in that: The pump body (1) also includes a fixing member (14), which includes multiple fixing bolts (141) and multiple nuts (142). The multiple fixing bolts (141) are evenly distributed around the fixing section (122). The fixing bolts (141) are threadedly connected to the fixing section (122), the second sealing ring (132) and the first pump body (11) in sequence. The nuts (142) correspond one-to-one with the fixing bolts (141) and are connected to the end of the fixing bolts (141) away from the first pump body (11).

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