Low-temperature centrifugal pump supercharging mechanism and low-temperature centrifugal pump

Abstract

The utility model discloses a low-temperature centrifugal pump pressurizing mechanism and a low-temperature centrifugal pump, and relates to the technical field of low-temperature centrifugal pumps, the low-temperature centrifugal pump pressurizing mechanism comprises a pump body, an impeller and an inducer, a mounting cavity is formed in the pump body, and the mounting cavity is communicated with the liquid inlet end and the liquid outlet end of the pump body; the impeller is mounted in the mounting cavity, and a liquid inlet of the impeller corresponds to the liquid inlet end of the pump body; the inducer is connected to a rotating shaft of the impeller, is coaxial with the impeller and is located at the liquid inlet end of the pump body. According to the scheme, the inducer is arranged at the liquid inlet end of the pump body, and the inducer is arranged at the liquid inlet of the impeller and is coaxially connected with the impeller, so that the inducer can be driven to rotate when the impeller rotates, fluid entering from the liquid inlet end of the pump body rotates, and the water pressure of the liquid inlet end of the pump body is improved; the fluid has enough pressure before entering the liquid inlet of the impeller from the liquid inlet end of the pump body, so that cavitation of the fluid to the impeller is reduced, and the service life of the impeller is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of low-temperature centrifugal pumps, in particular to a low-temperature centrifugal pump boosting mechanism and a low-temperature centrifugal pump. Background Art

[0002] Cryogenic centrifugal pumps are widely used in the field of petrochemical industry as process pumps and product disposal pumps. At present, single-stage cryogenic centrifugal pumps are often used as power pumps for product filling in air separation tank areas and LNG tank areas to increase pressure and transport fluids. Due to the characteristics of the process medium, the lowest temperature reaches -196°C. Cavitation often occurs during the startup of cryogenic centrifugal pumps. The principle of its generation is that the pump works on the liquid through the rotating impeller, which increases the energy of the liquid and changes the liquid velocity and pressure. Since the pressure at the impeller inlet is the lowest, if the pressure is equal to or lower than the vaporization pressure of the liquid at this temperature, a large amount of steam and gas dissolved in the liquid will escape, forming many small bubbles of steam and gas mixture. When these bubbles flow to the high-pressure area with the liquid, the pressure around the bubbles is greater than the internal pressure. Under the action of the pressure difference, the bubbles break and re-condense. During the condensation process, the liquid particles accelerate from the surroundings to the center of the bubble, and collide with each other to produce a high local pressure, which produces a cavitation effect on the inner wall of the cryogenic centrifugal pump. Utility Model Content

[0003] The main purpose of the utility model is to provide a low-temperature centrifugal pump boosting mechanism and a low-temperature centrifugal pump, aiming to increase the liquid pressure at the liquid inlet end of the low-temperature centrifugal pump and reduce the influence of cavitation on the low-temperature centrifugal pump.

[0004] In order to achieve the above-mentioned purpose, the low-temperature centrifugal pump boosting mechanism proposed in the utility model comprises:

[0005] A pump body, wherein a mounting cavity is formed in the pump body, and the mounting cavity is connected with a liquid inlet end and a liquid outlet end of the pump body;

[0006] An impeller, the impeller is installed in the installation cavity, and the liquid inlet of the impeller is arranged corresponding to the liquid inlet end of the pump body;

[0007] An inducer wheel is connected to the rotating shaft of the impeller and is coaxially arranged with the impeller. The inducer wheel is located at the liquid inlet end of the pump body.

[0008] In one embodiment, the inducer is an open impeller.

[0009] In one embodiment, a mounting hole is formed on the rotating shaft of the impeller, and a rotating shaft portion of the inducer is inserted into the mounting hole and connected via a fixing key.

[0010] In one embodiment, a step surface is formed on the rotating shaft of the inducer wheel near one end of the impeller, and the step surface abuts against the end of the impeller and is sealed by a sealing ring.

[0011] In one embodiment, the low-temperature centrifugal pump boosting mechanism also includes a positioning stud, which has a first end and a second end along an extension direction, and the peripheries of the first end and the second end are both provided with threads, the first end is threadedly connected to the rotating shaft of the impeller, and the second end is threadedly connected to the rotating shaft of the inducer.

[0012] In one embodiment, the positioning stud passes through the rotating shaft of the inducer and is threadedly connected to the impeller to fix the inducer and the impeller.

[0013] In one embodiment, the low-temperature centrifugal pump boosting mechanism further includes a pressure cap, which is disposed on the side of the rotating shaft of the inducer wheel facing away from the impeller, and is sleeved on the positioning stud, and the pressure cap abuts against the fixing key.

[0014] In one embodiment, the low-temperature centrifugal pump boosting mechanism further includes a locking nut, which is disposed on a side of the pressure cap facing away from the inducer, and the locking nut is threadedly connected to the positioning stud to lock the pressure cap.

[0015] In one embodiment, the low-temperature centrifugal pump boosting mechanism further includes a washer, which is sleeved on the positioning stud, and two sides of the washer are respectively in contact with the pressure cap and the locking nut.

[0016] The utility model also proposes a cryogenic centrifugal pump, the cryogenic centrifugal pump comprising the cryogenic centrifugal pump boosting mechanism described above, the cryogenic centrifugal pump boosting mechanism comprising:

[0017] A pump body, wherein a mounting cavity is formed in the pump body, and the mounting cavity is connected with a liquid inlet end and a liquid outlet end of the pump body;

[0018] An impeller, the impeller is installed in the installation cavity, and the liquid inlet of the impeller is arranged corresponding to the liquid inlet end of the pump body;

[0019] An inducer wheel is connected to the rotating shaft of the impeller and is coaxially arranged with the impeller. The inducer wheel is located at the liquid inlet end of the pump body.

[0020] The technical solution of the utility model is to arrange an inducer at the liquid inlet end of the pump body, and to arrange the inducer at the liquid inlet of the impeller and to be coaxially connected to the impeller, so that when the impeller rotates, the inducer can be driven to rotate so that the fluid entering from the liquid inlet end of the pump body can rotate, thereby increasing the water pressure at the liquid inlet end of the pump body, so that the fluid has sufficient pressure before entering from the liquid inlet end of the pump body to the liquid inlet of the impeller, thereby reducing the cavitation of the impeller by the fluid and increasing the service life of the impeller. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0022] Figure 1 This is a structural schematic diagram of an embodiment of a low-temperature centrifugal pump boosting mechanism provided by the utility model.

[0023] Description of Figure Numbers:

[0024] 1000. Cryogenic centrifugal pump booster mechanism; 1. Pump body; 11. Liquid inlet end; 2. Impeller; 21. Mounting hole; 3. Inducer; 4. Sealing ring; 5. Fixing key; 6. Positioning stud; 7. Pressure cap; 8. Locking nut; 9. Washer.

[0025] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0028] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0029] Cryogenic centrifugal pumps are widely used in the field of petrochemical industry as process pumps and product disposal pumps. At present, single-stage cryogenic centrifugal pumps are often used as power pumps for product filling in air separation tank areas and LNG tank areas to increase pressure and transport fluids. Due to the characteristics of the process medium, the lowest temperature reaches -196°C. Cavitation often occurs during the startup of cryogenic centrifugal pumps. The principle of its generation is that the pump works on the liquid through the rotating impeller, which increases the energy of the liquid and changes the liquid velocity and pressure. Since the pressure at the impeller inlet is the lowest, if the pressure is equal to or lower than the vaporization pressure of the liquid at this temperature, a large amount of steam and gas dissolved in the liquid will escape, forming many small bubbles of steam and gas mixture. When these bubbles flow to the high-pressure area with the liquid, the pressure around the bubbles is greater than the internal pressure. Under the action of the pressure difference, the bubbles break and re-condense. During the condensation process, the liquid particles accelerate from the surroundings to the center of the bubble, and collide with each other to produce a high local pressure, which produces a cavitation effect on the inner wall of the cryogenic centrifugal pump.

[0030] In order to solve the above problems, the utility model proposes a low-temperature centrifugal pump boosting mechanism 1000, including a pump body 1, an impeller 2 and an inducer 3. An installation cavity is formed in the pump body 1, and the installation cavity connects the liquid inlet end 11 and the liquid outlet end of the pump body 1; the impeller 2 is installed in the installation cavity, and the liquid inlet of the impeller 2 is arranged corresponding to the liquid inlet end 11 of the pump body 1; the inducer 3 is connected to the rotating shaft of the impeller 2 and is coaxially arranged with the impeller 2, and the inducer 3 is located at the liquid inlet end 11 of the pump body 1.

[0031] The technical solution of the utility model is to arrange an inducer 3 at the liquid inlet end of the pump body 1, and to arrange the inducer 3 at the liquid inlet of the impeller 2 and to be coaxially connected to the impeller 2, so that when the impeller 2 rotates, the inducer 3 can be driven to rotate to rotate the fluid entering from the liquid inlet end 11 of the pump body 1, thereby increasing the water pressure at the liquid inlet end 11 of the pump body 1, so that the fluid has sufficient pressure before entering the liquid inlet of the impeller 2 from the liquid inlet end 11 of the pump body 1, thereby reducing the cavitation of the impeller 2 by the fluid and increasing the service life of the impeller 2.

[0032] In an optional embodiment, in order to increase the pressure at the liquid inlet end 11 of the pump body 1, the inducer 3 is an open impeller 2. Figure 1 The blades of the open impeller 2 are arranged at the liquid inlet end 11 of the pump body 1. The fluid entering from the liquid inlet end 11 can be directly affected by the rotation of the inducer 3. The fluid forms a vortex in the pump body 1 as the blades of the inducer 3 rotate, so that the fluid has a greater speed and water pressure before entering the impeller 2, thereby avoiding cavitation of the fluid in the pump body 1. The service life of the pump body 1 and the impeller 2 is improved.

[0033] In an optional embodiment, in order to realize the installation of the inducer wheel 3 on the rotating shaft of the impeller 2, the rotating shaft of the impeller 2 is formed with a mounting hole 21, and the rotating shaft portion of the inducer wheel 3 is inserted into the mounting hole 21 and connected via the fixing key 5. Please refer to Figure 1 , by inserting the rotating shaft of the inducer 3 into the mounting hole 21. Thus, the coaxial connection between the impeller 2 and the inducer 3 is realized. The connection between the impeller 2 and the inducer 3 is realized by the fixed key 5, so that the inducer 3 can rotate with the rotation of the impeller 2 to stir the fluid at the liquid inlet end 11 of the pump body 1. In addition, by inserting the inducer 3 into the mounting hole 21, the radial deviation of the inducer 3 can be avoided, and the stability of the connection between the impeller 2 and the inducer 3 can be ensured. When installing the inducer 3 into the mounting hole 21, a hot installation method is adopted, such as uniformly heating the impeller 2 by induction heating, so that the aperture of the mounting hole 21 expands. When the impeller 2 reaches a suitable temperature and the inner diameter is fully expanded, the inducer 3 is quickly installed into the mounting hole 21. As the impeller 2 cools, the inner diameter shrinks, so that the impeller 2 and the inducer 3 are tightly connected and fixed.

[0034] In an optional embodiment, in order to further improve the connection stability between impeller 2 and inducer 3, a step surface is formed on the rotating shaft of inducer 3 near one end of impeller 2, and the step surface abuts against the end of impeller 2 and is sealed by sealing ring 4. Impeller 2 and inducer 3 are positioned in the axial direction by the step surface, and sealing ring 4 is provided at the contact position of the step surface to seal the step surface to prevent fluid from penetrating from the contact surface into mounting hole 21. Optionally, a stepped step can be provided on the rotating shaft of inducer 3, and a stepped step hole is correspondingly provided in mounting hole 21 of impeller 2, so as to further improve the matching stability between impeller 2 and inducer 3 and ensure the coaxial connection effect between the two.

[0035] In an optional embodiment, in order to achieve the fixation of the impeller 2 and the inducer 3, the low-temperature centrifugal pump boosting mechanism 1000 further includes a positioning stud 6, which has a first end and a second end along the extension direction, and the peripheries of the first end and the second end are both provided with threads, the first end is threadedly connected to the rotating shaft of the impeller 2, and the second end is threadedly connected to the rotating shaft of the inducer 3. Please refer to Figure 1 , the first end and the second end of the positioning stud 6 are respectively screwed with the impeller 2 and the inducer 3, so as to achieve the axial fixation of the impeller 2 and the inducer 3, and prevent the inducer 3 from loosening during the rotation process. Optionally, the first end and the second end of the positioning stud 6 can be buried in the rotating shafts of the impeller 2 and the inducer 3, for example, during installation, the first end of the positioning stud 6 is first screwed into the rotating shaft of the impeller 2, and then the inducer 3 is rotated and fixed on the second end of the positioning stud 6 and continues to rotate, so that the rotating shaft of the inducer 3 is screwed into the mounting hole 21 to achieve the match with the impeller 2, so that the axial fixation of the impeller 2 and the inducer 3 can be achieved, and the positioning stud 6 can be prevented from being exposed to the outside and impacted by the fluid. Optionally, by setting the rotation direction of the thread of the positioning stud 6 to be opposite to the rotation direction of the impeller 2 in the pump body 1, the connection strength between the impeller 2 and the positioning stud 6 can be further improved when the impeller 2 rotates, thereby improving the thread connection strength between the impeller 2 and the inducer 3.

[0036] In another optional embodiment, the positioning stud 6 passes through the rotating shaft of the inducer 3 and is screwed to the impeller 2 to achieve the fixation of the inducer 3 and the impeller 2. Figure 1 The positioning stud 6 can be set to a structure similar to a bolt. By passing the positioning stud 6 through the rotating shaft of the inducer 3 and screwing it to the rotating shaft of the impeller 2, and by axially pressing the inducer 3 with the nut at the end of the positioning stud 6, the axial connection strength between the impeller 2 and the inducer 3 is ensured.

[0037] In an optional embodiment, in order to fix the fixing key 5 in the axial direction, the low temperature centrifugal pump booster mechanism 1000 further includes a pressure cap 7, which is arranged on the side of the rotating shaft of the inducer 3 facing away from the impeller 2, and the pressure cap 7 is sleeved on the positioning stud 6, and the pressure cap 7 abuts against the fixing key 5. Please refer to Figure 1 One side of the pressing cap 7 abuts against the fixing key 5 to fix the fixing key 5 axially on the outer periphery of the rotating shaft of the impeller 2. The pressing cap 7 can be fixed on the inducer 3 by screws to ensure the connection strength of the pressing cap 7.

[0038] In an optional embodiment, the cryogenic centrifugal pump boosting mechanism 1000 further includes a locking nut 8, which is disposed on the side of the pressure cap 7 facing away from the inducer 3, and the locking nut 8 is screwed with the positioning stud 6 to lock the pressure cap 7. Optionally, the pressure cap 7 can be connected to the positioning stud 6 through the locking nut 8, and the pressure cap 7 is sleeved on the positioning stud 6, and the locking nut 8 and the positioning stud 6 are rotated and locked to fix the pressure cap 7 on the rotating shaft of the inducer 3, so that the cryogenic centrifugal pump boosting mechanism 1000 can be easily assembled and disassembled, and subsequent inspection and maintenance can be facilitated.

[0039] In order to further improve the stability of the locking nut 8 locking the pressure cap 7 and reduce the possibility of the locking nut 8 being loosened, the low-temperature centrifugal pump boosting mechanism 1000 also includes a washer 9, which is sleeved on the positioning stud 6, and the two sides of the washer 9 are respectively in contact with the pressure cap 7 and the locking nut 8. By arranging a gasket between the locking nut 8 and the pressure cap 7, the locking nut 8 can be more fully compressed when rotating, so that when the locking nut 8 is tightened, the locking nut 8 can generate a greater locking force with the pressure cap 7, and at the same time, the two sides of the gasket are respectively in contact with the locking nut 8 and the pressure cap 7, so that there can be a larger contact area between the two, thereby increasing the friction at the contact position, reducing the possibility of the locking nut 8 being loosened, and ensuring the connection strength.

[0040] The utility model also proposes a low-temperature centrifugal pump, which includes a low-temperature centrifugal pump boosting mechanism 1000. The specific structure of the low-temperature centrifugal pump boosting mechanism 1000 refers to the above-mentioned embodiment. Since the low-temperature centrifugal pump adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0041] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A low temperature centrifugal pump boosting mechanism, characterized in that: include: A pump body, wherein a mounting cavity is formed in the pump body, and the mounting cavity is connected with a liquid inlet end and a liquid outlet end of the pump body; An impeller, the impeller is installed in the installation cavity, and the liquid inlet of the impeller is arranged corresponding to the liquid inlet end of the pump body; An inducer wheel is connected to the rotating shaft of the impeller and is coaxially arranged with the impeller. The inducer wheel is located at the liquid inlet end of the pump body.

2. The low-temperature centrifugal pump boosting mechanism according to claim 1, characterized in that: The inducer is an open impeller.

3. The low-temperature centrifugal pump boosting mechanism according to claim 1, characterized in that: The rotating shaft of the impeller is formed with a mounting hole, and the rotating shaft portion of the inducer is inserted into the mounting hole and connected via a fixing key.

4. The low-temperature centrifugal pump boosting mechanism according to claim 3, characterized in that: A step surface is formed on the rotating shaft of the inducer wheel near one end of the impeller, and the step surface abuts against the end of the impeller and is sealed by a sealing ring.

5. The low-temperature centrifugal pump boosting mechanism according to any one of claims 3 to 4, characterized in that: The low-temperature centrifugal pump boosting mechanism also includes a positioning stud, which has a first end and a second end along an extension direction, and the peripheries of the first end and the second end are both provided with threads, the first end is threadedly connected to the rotating shaft of the impeller, and the second end is threadedly connected to the rotating shaft of the inducer.

6. The low-temperature centrifugal pump boosting mechanism according to claim 5, characterized in that: The positioning stud passes through the rotating shaft of the inducer and is threadedly connected to the impeller to fix the inducer and the impeller.

7. The low-temperature centrifugal pump boosting mechanism according to claim 6, characterized in that: The low-temperature centrifugal pump boosting mechanism also includes a pressure cap, which is arranged on the side of the rotating shaft of the inducer wheel facing away from the impeller, and the pressure cap is sleeved on the positioning stud, and the pressure cap abuts against the fixing key.

8. The low-temperature centrifugal pump boosting mechanism according to claim 7, characterized in that: The low-temperature centrifugal pump boosting mechanism also includes a locking nut, which is arranged on the side of the pressure cap facing away from the inducer, and the locking nut is threadedly connected with the positioning stud to lock the pressure cap.

9. The low-temperature centrifugal pump boosting mechanism according to claim 8, characterized in that: The low-temperature centrifugal pump boosting mechanism further comprises a washer, which is sleeved on the positioning stud, and two sides of the washer are respectively in contact with the pressure cap and the locking nut.

10. A cryogenic centrifugal pump, characterized in that: It comprises a low-temperature centrifugal pump boosting mechanism as claimed in any one of claims 1 to 9.

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