Purging device for preventing cavitation of liquid oxygen pump

Abstract

The invention is applicable to the technical field of cavitation of liquid oxygen pumps, and provides a purging device for preventing cavitation of a liquid oxygen pump, which comprises a heat insulation box and a liquid oxygen pump fixedly mounted in the heat insulation box, the system further comprises a DCS control system, a temperature transmitter and a purging device. The purging device comprises a purging pipeline connected with the liquid oxygen pump; a program control valve, a safety valve, a hand valve and a temperature sensor are arranged on the purging pipeline; the interval time and the discharge time are set through a DCS control system, a program carries out automatic operation according to a sequence control block, periodic automatic exhaust is achieved, the influence on cavitation of the liquid oxygen pump is reduced, gas accumulation is eliminated through regular exhaust of the purging device, the stability of fluid in the pump is maintained, damage of cavitation to a pump impeller is reduced, the service life of equipment is prolonged, and the service life of the equipment is prolonged. Time is accurately controlled through a DCS control system, cooling capacity loss is reduced, and the risk of manual contact with liquid oxygen is reduced through automatic operation.

Description

Technical Field

[0001] This invention relates to the field of liquid oxygen pump cavitation technology, and more specifically, to a purging device for preventing liquid oxygen pump cavitation. Background Technology

[0002] The backup liquid oxygen pump is mainly used to ensure the gas supply to customers in the event of an air separation accident. Currently, the main approach is to pre-cool, start the pump, pressurize, and deliver gas after the system is shut down.

[0003] In traditional designs, liquid oxygen returns to the main cold box via pipeline. However, current designs have flaws, requiring the exhaust valve to open only once per hour. This presents several problems: the manual exhaust valve opening is unstable, and the timing of opening is inaccurate, easily leading to cavitation in the liquid oxygen pump. Cavitation occurs when the local pressure drops below the vaporization pressure of liquid oxygen upon entering the pump, causing the liquid to vaporize and form bubbles. These bubbles are thrown towards the high-pressure area by centrifugal force, where they rapidly burst due to the increased pressure. The impact force from the bursting bubbles erodes the metal surfaces of the pump casing and impeller, damaging the pump's mechanical performance and overall efficiency. Simultaneously, the liquid oxygen pump is directly exposed to the external environment without effective insulation, prolonging the time required for complete pre-cooling during startup. Heat from the external environment is conducted to the pump's interior, causing an increase in internal temperature and resulting in liquid oxygen loss due to vaporization. Furthermore, the partially vaporized liquid oxygen flowing in after the initial flow also contributes to impeller cavitation. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a purging device for preventing cavitation in liquid oxygen pumps. This device regularly vents air to eliminate gas accumulation, maintains fluid stability within the pump, reduces cavitation damage to the pump impeller, and extends equipment life. Furthermore, the DCS control system precisely controls the time, minimizing cooling loss, and automated operation reduces the risk of human contact with liquid oxygen.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A purging device for preventing cavitation in a liquid oxygen pump includes an insulated box and a liquid oxygen pump fixedly installed inside the insulated box; it also includes a DCS control system, a temperature transmitter, and a purging device; the purging device includes a purging pipeline connected to the liquid oxygen pump; the purging pipeline is equipped with a programmable valve, a safety valve, a manual valve, and a temperature sensor; the DCS control system is used for lower-level computer programming and upper-level computer input of exhaust parameters; the temperature sensor is used to monitor the temperature of the purging pipeline to achieve exhaust monitoring; the programmable valve is used to control the liquid oxygen discharge equipment; the safety valve is used to cut off the liquid oxygen discharge equipment in special circumstances; by setting the interval time and discharge time through the DCS control system, the program automatically calculates according to the sequential control block to achieve periodic automatic venting, reducing the impact on liquid oxygen pump cavitation.

[0006] The invention is further configured such that: the insulated box includes a box body and a sealing cover slidably disposed on the box body; the input end and output end of the liquid oxygen pump are respectively connected to an input pipe and an output pipe extending outward through the box body; a reflux valve is provided on both the input pipe and the output pipe; a connecting pipe extending outward through the box body is connected to the top of the liquid oxygen pump; the connecting pipe is connected to a purging pipeline.

[0007] The present invention is further configured such that: a base is fixed to the bottom surface of the box; a plurality of sliding rods are uniformly fixed to the surface of the base; a retaining ring is fixed between the ends of each sliding rod; the sealing cover includes a cover; a plurality of guide holes that slide and cooperate with the corresponding sliding rods are uniformly opened on the surface of the cover; and a support spring sleeved on the corresponding sliding rod is fixedly connected between the cover and the base.

[0008] The invention is further configured such that: a sealing ring is fixed on the bottom surface of the cover and is inserted into the box body; a plurality of coaxial annular cavities are evenly opened on the outer circumferential side of the sealing ring; an elastic diaphragm is provided inside the annular cavity; the elastic diaphragm is made of perfluoroether rubber; and a plurality of sealing grooves are evenly opened on the inner wall of the box body to match the elastic diaphragm in the inflated state.

[0009] The invention is further configured such that: a spherical shell is fixedly fixed through the surface of the cover; a pressure relief pipe and a pressure sensor are sequentially arranged through the surface of the cover; a shut-off valve is provided in the pressure relief pipe; an elastic reset balloon is provided inside the spherical shell; and an air supply pipe is provided between the elastic reset balloon and the corresponding annular cavity.

[0010] The invention is further configured such that: a plurality of inclined guide plates are uniformly fixed on the surface of the cover; a straight guide plate is fixed on the side of the inclined guide plate; a sliding groove is formed on the surface of the straight guide plate; a guide rod is fixed on the inner wall of the sliding groove; an extrusion plate that slides and cooperates with the guide rod is slidably arranged between the inner walls of the sliding groove; a return spring sleeved on the guide rod is fixedly connected between the extrusion plate and the sliding groove; and a plurality of clearance grooves that slide and cooperate with the extrusion plate are uniformly formed on the outer wall of the spherical shell.

[0011] The invention is further configured such that: a plurality of L-shaped plates are uniformly fixed to the outer wall of the box; a piston cylinder is fixed through the side of the L-shaped plate; an ear tube is connected to one end of the piston cylinder; an inflation tube is fixed to the surface of the retaining ring; an inflation valve is provided at one end of the inflation tube, and a plurality of branch tubes are uniformly fixed to the other end; the ear tube and the branch tubes are connected by a flexible hose.

[0012] The invention is further configured such that: a piston plate is slidably disposed inside the piston cylinder; a piston rod is fixedly disposed on the side of the piston plate and slidably engages with the end of the piston cylinder; a compression spring sleeved on the piston rod is fixedly connected between the piston plate and the piston cylinder; a ball head is fixedly disposed at the end of the piston rod; a slide rail is fixedly disposed on the periphery of the piston rod; a limiting groove is provided at the end of the piston cylinder and slidably engages with the slide rail; an L-shaped groove is provided on the side of the piston plate; and an L-shaped exhaust pipe is provided between the periphery of the piston cylinder and the housing near its end.

[0013] The invention is further configured such that: the cover has symmetrically opened sliding openings on its periphery; the outer wall of the box is symmetrically fixed with extension plates; a sliding plate is fixed between the two extension plates; a baffle that slides on the sliding plate and slides with the sliding openings is slidably disposed thereon; a magnet is fixed to the side of the extension plate; and iron blocks are fixed to both ends of the baffle.

[0014] The advantages of this invention are: 1. This invention eliminates gas accumulation by regularly venting through a purging device, maintains fluid stability inside the pump, reduces cavitation damage to the pump impeller, and extends equipment life. The DCS control system precisely controls the time, reducing cold loss, and the automated operation reduces the risk of human contact with liquid oxygen.

[0015] 2. This invention injects helium into each set of piston cylinders, pushing the piston plates to slide. This causes the ball heads to slide closer together, squeezing the corresponding inclined guide plates, thereby pressing the sealing cover into the housing and improving the sealing performance between the housing and the sealing cover. When the ball head slides along the straight guide plate and pushes the extrusion plate, the extrusion plate squeezes the elastic reset ball bladder. The elastic diaphragm is inflated and pushed into the corresponding sealing groove, further improving the sealing performance between the housing and the sealing cover, achieving cold preservation of the liquid oxygen pump, further reducing cavitation damage to the pump impeller, and extending the equipment life. Attached Figure Description

[0016] Figure 1 This is a structural block diagram of a purging device for preventing cavitation in a liquid oxygen pump according to the present invention.

[0017] Figure 2 This is a circuit diagram of the DCS control system of the present invention.

[0018] Figure 3 This is a schematic diagram of the structure of the insulated box of the present invention.

[0019] Figure 4 For the present invention Figure 3 A structural diagram from a frontal viewpoint.

[0020] Figure 5 For the present invention Figure 4 Enlarged view of region A.

[0021] Figure 6 This is a schematic diagram of the structure of the housing of the present invention.

[0022] Figure 7 This is a schematic diagram of the sealing cover of the present invention.

[0023] Figure 8 For the present invention Figure 7 A structural diagram from a frontal viewpoint.

[0024] Figure 9 For the present invention Figure 7 A structural diagram from a top-down perspective.

[0025] Figure 10 For the present invention Figure 7 A structural diagram from an upward-looking perspective.

[0026] In the diagram: 1. Insulation box; 2. Liquid oxygen pump; 3. Purge device; 4. Purge pipeline; 5. Box body; 6. Sealing cover; 7. Input pipe; 8. Output pipe; 9. Return valve; 10. Connecting pipe; 11. Base; 12. Slide rod; 13. Retaining ring; 14. Retaining cover; 15. Guide hole; 16. Sealing ring; 17. Annular cavity; 18. Elastic diaphragm; 19. Sealing groove; 20. Spherical shell; 21. Gas delivery pipe; 22. Pressure relief pipe; 23. Pressure sensor; 24. Inclined guide. 25. Straight guide plate; 26. Slide groove; 27. Guide rod; 28. Compression plate; 29. ​​Return spring; 30. Clearance groove; 31. L-shaped plate; 32. Piston cylinder; 33. Ear tube; 34. Inflation tube; 35. Branch tube; 36. Piston plate; 37. Piston rod; 38. Ball head; 39. Slide rail; 40. L-shaped exhaust pipe; 41. Slide opening; 42. Extension plate; 43. Slide plate; 44. Baffle; 45. L-shaped groove; 46. Compression spring; 47. Elastic return balloon. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] In this invention, unless otherwise stated, the directional terms such as "up" and "down" generally refer to the directions shown in the accompanying drawings, or to the vertical, perpendicular, or gravitational direction; similarly, for ease of understanding and description, "left" and "right" generally refer to the left and right shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0030] Example 1, please refer to Figure 1-10 The present invention provides the following technical solutions: A purging device for preventing cavitation in a liquid oxygen pump specifically includes an insulated box 1 and a liquid oxygen pump 2 fixedly installed inside the insulated box 1; it also includes a DCS control system, a temperature transmitter, and a purging device 3; the purging device 3 includes a purging pipeline 4 connected to the liquid oxygen pump 2; the purging pipeline 4 is equipped with a programmable valve, a safety valve, a manual valve, and a temperature sensor; the DCS control system is used for lower-level computer programming functions and upper-level computer input of exhaust parameters, such as purging time and interval time; the temperature sensor is used to monitor the temperature of the purging pipeline to achieve exhaust monitoring; the programmable valve is used to control the liquid oxygen discharge equipment; the safety valve is used to cut off the liquid oxygen discharge equipment in special circumstances; by setting the interval time and discharge time through the DCS control system, the program automatically calculates according to the sequential control block to achieve periodic automatic venting, reducing the impact on cavitation of the liquid oxygen pump 2.

[0031] Working principle of this embodiment: Input device loop: such as Figure 2 As shown, the field temperature transmitter converts the physical signal into a 4-20mA signal and transmits it to the AI ​​safety barrier in the external distribution cabinet between the cabinets. The safety barrier transmits the signal to the AI ​​card of the DCS system. The card uploads the signal to the CPU via the DP line for processing and displays it on the host computer. Output device circuit: such as Figure 2 As shown, the operator presses the valve switch command on the host computer. After the CPU performs the calculation, it transmits the control signal to the DO card. The DO card then transmits the level signal to the field valve solenoid valve to control the valve's action.

[0032] DCS timing control program settings: Step 1: Create an interval timer block, a discharge timer block, and an automatic discharge program block on the lower-level machine. The time in the two timer blocks can be changed at will, which is convenient to modify according to the specific working conditions.

[0033] Step 2: In the host computer, retrieve the timing function block, click on time settings, change the interval time and discharge time, and confirm the settings.

[0034] Operating steps: Operators pre-set the interval time (e.g., 1 hour) and the discharge time (e.g., 10 minutes), press the automatic button, and the program automatically calculates according to the sequential control block. First, it outputs a command to open the solenoid valve to start venting. After 10 minutes, the venting action ends, the solenoid valve closes, and the interval time module starts timing. After 1 hour, it outputs an open command to start venting again, lasting for 10 minutes, and repeats this cycle to achieve automatic venting. This reduces human intervention, and regular venting reduces the impact of cavitation on the liquid oxygen pump, thereby solving the hidden dangers mentioned in the background. It can effectively improve the safety and stability of equipment operation, reduce energy consumption, and extend the service life of equipment, and has great application value and market prospects. The discharged gas will turn back into liquid oxygen due to changes in ambient temperature and return to the main cold box for recycling.

[0035] Example 2, please refer to Figure 1-10 This second embodiment is an improvement on the first embodiment as follows: Specifically, the insulated box 1 includes a box body 5 and a sealing cover 6 that is slidably disposed on the box body 5; the input end and output end of the liquid oxygen pump 2 are respectively connected to an input pipe 7 and an output pipe 8 that extend outward through the box body 5; both the input pipe 7 and the output pipe 8 are provided with a reflux valve 9; the top of the liquid oxygen pump 2 is connected to a connecting pipe 10 that extends outward through the box body 5; the connecting pipe 10 is connected to the purging pipeline 4.

[0036] By installing reflux valves 9 on both the input pipe 7 and the output pipe 8, the pressure of the incoming liquid oxygen is stabilized by the reflux valve 9 on the input pipe 7, and the pressure of the outgoing liquid oxygen is stabilized by the reflux valve 9 on the output pipe 8.

[0037] A base 11 is fixed to the bottom surface of the housing 5; a plurality of sliding rods 12 are evenly fixed to the surface of the base 11; a retaining ring 13 is fixed between the ends of each sliding rod 12; the sealing cover 6 includes a cover 14; a plurality of guide holes 15 are evenly opened on the surface of the cover 14 to slide and cooperate with the corresponding sliding rods 12; a support spring sleeved on the corresponding sliding rod 12 is fixedly connected between the cover 14 and the base 11.

[0038] In the initial state, the elastic force of the supporting spring causes the cover 14 to press against the bottom surface of the retaining ring 13, which facilitates the maintenance of the liquid oxygen pump 2 inside the housing 5.

[0039] The bottom surface of the cover 14 is fixed with a sealing ring 16 that is inserted into the box 5; the outer periphery of the sealing ring 16 is evenly provided with several coaxial annular cavities 17; an elastic diaphragm 18 is provided inside the annular cavity 17; the elastic diaphragm 18 is made of perfluoroether rubber; the inner wall of the box 5 is evenly provided with several sealing grooves 19 that are adapted to the elastic diaphragm 18 in the inflated state.

[0040] Perfluoroether rubber has excellent chemical resistance, high temperature resistance and low temperature resistance, which enables the elastic diaphragm 18 to be used normally in super-cold environments.

[0041] A spherical shell 20 is fixedly fixed through the surface of the cover 14; a pressure relief pipe 22 and a pressure sensor 23 are sequentially arranged through the surface of the cover 14; a shut-off valve is provided in the pressure relief pipe 22; an elastic reset balloon 47 is provided inside the spherical shell 20; an air supply pipe 21 is provided between the elastic reset balloon 47 and the corresponding annular cavity 17.

[0042] The surface of the cover 14 is uniformly fixed with several inclined guide plates 24; the side of the inclined guide plate 24 is fixed with a straight guide plate 25; the surface of the straight guide plate 25 is provided with a sliding groove 26; the inner wall of the sliding groove 26 is fixed with a guide rod 27; the inner wall of the sliding groove 26 is slidably arranged with a pressing plate 28 that slides and cooperates with the guide rod 27; a return spring 29 sleeved on the guide rod 27 is fixedly connected between the pressing plate 28 and the sliding groove 26; the outer wall of the spherical shell 20 is uniformly provided with several clearance grooves 30 that slide and cooperate with the pressing plate 28.

[0043] A rubber plate is provided on the side of the compression plate 28. In the initial state, the rubber plate is in contact with the elastic reset balloon 47.

[0044] Several L-shaped plates 31 are evenly fixed on the outer wall of the housing 5; a piston cylinder 32 is fixed through the side of the L-shaped plate 31; an ear tube 33 is connected to one end of the piston cylinder 32; an inflation tube 34 is fixed on the surface of the retaining ring 13; an inflation valve is provided at one end of the inflation tube 34, and several branch tubes 35 are evenly fixed at the other end; the ear tube 33 and the branch tubes 35 are connected by a flexible hose.

[0045] A piston plate 36 is slidably disposed inside the piston cylinder 32; a piston rod 37 is fixed to the side of the piston plate 36 and slides with the end of the piston cylinder 32; a compression spring 46 is fixedly connected between the piston plate 36 and the piston cylinder 32 and sleeved on the piston rod 37; a ball head 38 is fixed to the end of the piston rod 37; a slide rail 39 is fixed to the periphery of the piston rod 37; a limiting groove is opened at the end of the piston cylinder 32 and slides with the slide rail 39; an L-shaped groove 45 is opened on the side of the piston plate 36; an L-shaped exhaust pipe 40 is provided on the periphery of the piston cylinder 32 near its end and communicates with the housing 5.

[0046] The cover 14 has symmetrical sliding openings 41 on its sides; the outer wall of the box 5 has symmetrical extension plates 42 fixed on it; the two extension plates 42 are fixed between the two extension plates 42; the slide plate 43 is slidably arranged on the slide plate 43 and slides with the sliding openings 41; magnets are fixed on the sides of the extension plates 42; iron blocks are fixed at both ends of the baffles 44.

[0047] In the initial state, the baffle 44 is far away from the corresponding piston cylinder 32 to avoid affecting the normal closing of the sealing cover 6.

[0048] Working principle of this embodiment two: Press down on the sealing cover 6 to make it slide down along the slide rod 12 to the bottom of the straight ball head 38. Helium is injected into each set of piston cylinders 32 through the inflation tube 34. As the helium is injected, the piston plate 36 is squeezed and slides along the corresponding piston cylinder 32. The corresponding compression spring 46 is compressed. The piston rod 37 drives the ball head 38 to slide into the surface of the cover 14. When the ball head 38 slides on the inclined guide plate 24, it squeezes the inclined guide plate 24 and drives the sealing ring 16 to slide down and insert into the box 5. When the ball head 38 slides to the surface of the straight guide plate 25, the ball head 38 continues to move while the sealing ring 16 does not descend, completing the sealing connection between the sealing ring 16 and the box 5, improving the cooling effect of the liquid oxygen pump 2.

[0049] When the ball head 38 slides on the surface of the straight guide plate 25, it squeezes the corresponding extrusion plate 28, causing the extrusion plate 28 to slide along the inner wall of the slide groove 26. The corresponding return spring 29 is stretched, and the extrusion plate 28 drives the rubber plate to slide through the clearance groove 30 and squeeze the elastic return balloon 47. This causes the air inside the elastic return balloon 47 to enter the corresponding annular cavity 17 through the air supply pipe 21. The corresponding elastic diaphragm 18 is inflated and pushed into the corresponding sealing groove 19, further improving the sealing effect between the sealing ring 16 and the housing 5, and further improving the cold insulation effect of the liquid oxygen pump 2.

[0050] After the elastic diaphragm 18 and the sealing groove 19 are sealed together, the corresponding baffle 44 is slid into the corresponding sliding opening 41, which limits the position of the cover 14. At this time, the iron block on one side of the baffle 44 is magnetically attracted to the magnet on the side of the corresponding extension plate 42, which improves the stability of the baffle 44.

[0051] As helium is continuously input, the L-shaped groove 45 on the piston plate 36 slides to align with the L-shaped exhaust pipe 40, and helium enters the interior of the housing 5. By observing the pressure sensor 23, when the reading of the pressure sensor 23 reaches the specified value, the input of helium is stopped. The high-pressure helium reduces the heat conduction inside the housing 5, thereby preventing external temperature from entering the liquid oxygen pump 2 inside the housing 5 and causing excessive liquid oxygen loss.

[0052] When it is necessary to remove the sealing cover 6, firstly, slowly open the shut-off valve on the pressure relief pipe 22 to gradually release the high pressure inside the housing 5, thereby relieving the high pressure environment inside the piston cylinder 32. Under the elastic reset action of the compression spring 46, the piston plate 36 and the ball head 38 slide back to reset, releasing the compression limit on the straight guide plate 25. Then, under the elastic reset action of the reset spring 29, the compression plate 28 slides back to reset, releasing the compression on the elastic reset balloon 47. Under the elastic reset action, the elastic reset balloon 47 draws out the air inside the annular cavity 17, causing the elastic diaphragm 18 to reset and detach from the corresponding sealing groove 19. As the ball head 38 slides back to detach on the inclined guide plate 24, under the elastic reset action of the support spring, the sealing cover 6 slides up to detach from the housing 5.

[0053] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0054] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0055] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0057] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A purging device for preventing cavitation in a liquid oxygen pump, comprising an insulated box (1) and a liquid oxygen pump (2) fixedly installed inside the insulated box (1); characterized in that: It also includes a DCS control system, a temperature transmitter, and a purging device (3); The purging device (3) includes a purging line (4) connected to the liquid oxygen pump (2); the purging line (4) is equipped with a programmable valve, a safety valve, a manual valve and a temperature sensor; The DCS control system is used for lower-level computer programming and upper-level computer input of exhaust parameters; the temperature sensor is used to monitor the temperature of the purge pipeline to achieve exhaust monitoring; the programmable valve is used to control the liquid oxygen discharge equipment; the safety valve is used to cut off the liquid oxygen discharge equipment under special circumstances. By setting the interval time and emission time through the DCS control system, the program performs automatic calculations based on the sequential control block to achieve periodic automatic venting, thereby reducing the impact on the cavitation of the liquid oxygen pump (2).

2. The purging device for preventing cavitation in a liquid oxygen pump according to claim 1, characterized in that: The insulated box (1) includes a box body (5) and a sealing cover (6) that is slidably disposed on the box body (5); the input end and output end of the liquid oxygen pump (2) are respectively connected to an input pipe (7) that extends outward through the box body (5) and an output pipe (8); a reflux valve (9) is provided on both the input pipe (7) and the output pipe (8); a connecting pipe (10) that extends outward through the box body (5) is connected to the top of the liquid oxygen pump (2); the connecting pipe (10) is connected to the purging pipeline (4).

3. A purging device for preventing cavitation in a liquid oxygen pump according to claim 2, characterized in that: The bottom surface of the box (5) is fixed with a base (11); a plurality of slide rods (12) are evenly fixed on the surface of the base (11); a retaining ring (13) is fixed between the ends of each slide rod (12); the sealing cover (6) includes a cover (14); a plurality of guide holes (15) are evenly opened on the surface of the cover (14) to slide and cooperate with the corresponding slide rods (12); a support spring sleeved on the corresponding slide rod (12) is fixedly connected between the cover (14) and the base (11).

4. A purging device for preventing cavitation in a liquid oxygen pump according to claim 3, characterized in that: The bottom surface of the cover (14) is fixed with a sealing ring (16) that is inserted into the box (5); the outer circumferential side of the sealing ring (16) is evenly provided with a number of coaxial annular cavities (17); an elastic diaphragm (18) is provided inside the annular cavity (17); the elastic diaphragm (18) is made of perfluoroether rubber; the inner wall of the box (5) is evenly provided with a number of sealing grooves (19) that are adapted to the elastic diaphragm (18) in the inflated state.

5. A purging device for preventing cavitation in a liquid oxygen pump according to claim 4, characterized in that: A spherical shell (20) is fixed through the surface of the cover (14); a pressure relief pipe (22) and a pressure sensor (23) are sequentially arranged through the surface of the cover (14); a shut-off valve is provided in the pressure relief pipe (22); an elastic reset balloon (47) is provided inside the spherical shell (20); an air supply pipe (21) is provided between the elastic reset balloon (47) and the corresponding annular cavity (17).

6. A purging device for preventing cavitation in a liquid oxygen pump according to claim 5, characterized in that: The cover (14) has several inclined guide plates (24) evenly fixed on its surface; straight guide plates (25) are fixed on the sides of the inclined guide plates (24); a sliding groove (26) is provided on the surface of the straight guide plate (25); a guide rod (27) is fixed on the inner wall of the sliding groove (26); an extrusion plate (28) is slidably arranged between the inner walls of the sliding groove (26) and slides with the guide rod (27); a return spring (29) sleeved on the guide rod (27) is fixedly connected between the extrusion plate (28) and the sliding groove (26); and several clearance grooves (30) that slide with the extrusion plate (28) are evenly provided on the outer wall of the spherical shell (20).

7. A purging device for preventing cavitation in a liquid oxygen pump according to claim 6, characterized in that: The outer wall of the box (5) is uniformly fixed with several L-shaped plates (31); a piston cylinder (32) is fixed through the side of the L-shaped plate (31); an ear tube (33) is connected to one end of the piston cylinder (32); an inflation tube (34) is fixed on the surface of the retaining ring (13); an inflation valve is provided at one end of the inflation tube (34), and several branch pipes (35) are uniformly fixed at the other end; the ear tube (33) and the branch pipes (35) are connected by a flexible hose.

8. A purging device for preventing cavitation in a liquid oxygen pump according to claim 7, characterized in that: A piston plate (36) is slidably disposed inside the piston cylinder (32); a piston rod (37) is fixed on the side of the piston plate (36) and slides with the end of the piston cylinder (32); a compression spring (46) is fixedly connected between the piston plate (36) and the piston cylinder (32) and sleeved on the piston rod (37); a ball head (38) is fixed at the end of the piston rod (37); a slide rail (39) is fixed on the periphery of the piston rod (37); a limiting groove is opened at the end of the piston cylinder (32) and slides with the slide rail (39); an L-shaped groove (45) is opened on the side of the piston plate (36); an L-shaped exhaust pipe (40) is connected between the periphery of the piston cylinder (32) and the housing (5) near its end.

9. A purging device for preventing cavitation in a liquid oxygen pump according to claim 8, characterized in that: The cover (14) has symmetrically opened sliding openings (41) on its periphery; the outer wall of the box (5) is symmetrically fixed with extension plates (42); a sliding plate (43) is fixed between the two extension plates (42); a baffle (44) that slides on the sliding plate (43) and slides in cooperation with the sliding opening (41); a magnet is fixed on the side of the extension plate (42); and iron blocks are fixed at both ends of the baffle (44).

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