CN110792612A

CN110792612A - Low-temperature immersed pump

Info

Publication number: CN110792612A
Application number: CN201911259930.8A
Authority: CN
Inventors: 刘洋
Original assignee: Jiuzhou Yunjian (beijing) Space Technology Co Ltd
Current assignee: Jiuzhou Yunjian (beijing) Space Technology Co Ltd
Priority date: 2019-12-10
Filing date: 2019-12-10
Publication date: 2020-02-14

Abstract

The invention discloses a low-temperature immersed pump, which consists of a pump part and a motor part, wherein the pump part comprises: an inlet housing, a volute, and a pump body; the motor part includes: the motor comprises a shell, an end cover and a motor main body arranged in the shell; the inlet shell, the spiral shell, the machine shell and the end cover are sequentially sealed and detachably connected, and the pump main body is arranged in the inlet shell and the spiral shell. According to the low-temperature immersed pump provided by the scheme, the inlet shell, the spiral shell, the shell and the end cover are sequentially and hermetically connected, so that the whole pump body can be completely immersed in liquid, and the overall noise is low during working; meanwhile, the sealing structure enables the motor and the lead to be naturally isolated from liquid, so that dynamic sealing is not needed, the service life of the pump is prolonged, and the use and maintenance cost is reduced. In addition, the shells of the pump part and the motor part are respectively designed into a split assembly structure, so that the pump part and the motor part are convenient to install and maintain, and the internal structure is adjusted.

Description

Low-temperature immersed pump

Technical Field

The invention relates to the technical field of low-temperature conveying, in particular to a low-temperature immersed pump.

Background

Cryogenic pumps are important devices in the LNG industry chain and are very widely used. At present, the development of foreign LNG immersed pumps is developed towards large-scale, high-efficiency and high-pressure directions, and China does not master key core technologies yet and has great significance in independent research and development. The annual growth rate of LNG in China is more than 15 percent, and the LNG becomes a new and rapidly developed industry in the energy field of China. A large number of LNG receiving stations, LNG plants, and LNG storage stations are built in various places. During the process of LNG production, transportation, acceptance and utilization, the LNG transfer needs to use an LNG low-temperature immersed pump. In recent years, with the continuous improvement of low-temperature materials, sealing technology, control technology and processing technology, the performance of the LNG low-temperature submerged pump is greatly improved, and the LNG low-temperature submerged pump is more widely applied. Currently, Nikkiso, Shinko corporation, j.g. garter, Ebara, acdc ryo corporation, Cryostar corporation, france, etc., in japan are major suppliers of LNG low temperature submersible pumps worldwide. However, since no large-scale LNG storage tank and cryogenic pump for LNG ships are independently researched and developed at present in China, the established domestic LNG projects all use imported products, and the research and development of the domestic LNG cryogenic immersed pump with independent intellectual property rights are important for the development of the LNG industry in China under the background of the rapid development of the LNG industry in China.

The development and planning of the LNG industry in China indicates that the future decades are the high-speed development period of the natural gas industry in China, and the demand peak of an LNG cryogenic pump is met by large-scale planning and construction of a large number of LNG receiving stations and LNG factories. In recent years, the rapid development of national economy in China has increased the demand for energy. According to the national energy strategy report made by the national development and improvement committee, Liquefied Natural Gas (LNG) is used as a fifth tactical strategy energy channel for ensuring national energy safety by 'sea gas landing', and is also an important measure for changing and adjusting an energy structure and relieving supply pressure caused by excessive dependence on petroleum. In the whole industrial chain of the LNG, the LNG is composed of a plurality of large links such as export, transportation, receiving and utilization, each link is used for a cryogenic pump, and therefore the role of the LNG cryogenic transport pump in the industrial chain is very important. Currently, only a few companies from american company j.c. caner, Ebara, Cryostar in france, and Nikkiso, Shinko in japan, are known in the world to be able to produce LNG transfer pumps, compared to the fact that there are currently no related products with completely proprietary intellectual property rights in our country. Therefore, imported products from abroad are purchased at the LNG receiving terminal, the vaporizing station and the Liquefied Natural Gas Vehicle (LNGV) filling station in China without exception, however, domestic related scholars are very necessary to develop the domestic research and development of the LNG transfer pump under the large environment that the LNG industry is greatly developed and the national energy safety is guaranteed in China at present.

No similar prior art products exist in China. Domestic motor drive pump is the pump of traditional normal atmospheric temperature medium work, and the motor and the pump portion of this kind of pump divide separately to set up, need set up gearbox and shaft coupling between motor output shaft and the pump drive axle, will set up the dynamic seal behind the pump simultaneously, prevent that the pumping medium from leaking in a large number and influencing pump performance or cause the accident to gearbox or motor.

The motor part and the pump part of the existing motor pump are structurally arranged separately, so that the weight and the size of the whole motor pump are increased, and higher requirements are provided for installation space. Meanwhile, for the transportation of LNG low-temperature media, the pump needs to be additionally provided with a heat insulation design, otherwise, the temperature of the LNG in the pump is rapidly increased under the normal-temperature environment, the media at the inlet of the pump are more likely to generate cavitation erosion, the LNG transported out after the pump is also likely to be gasified, the temperature requirement of the LNG is not met, and once the heat insulation design is added, the weight and the reliability of the whole pump are higher. Meanwhile, the separated motor pump cannot be soaked in the LNG liquid, and extra conveying pipelines, valves and other equipment need to be added in the actual application process. The separated motor pump is provided with the dynamic seal, so that the working life is short, the seal is abraded to a certain degree and then needs to be disassembled, overhauled and replaced, and the working reliability and the service life are influenced. In addition, a sliding bearing and an extrusion oil film damper can be applied to the normal temperature pump, and the shaft system can be supported by introducing oil with certain pressure. In a low-temperature environment, both the sliding bearing and the squeeze film damper cannot be used, so that the motor pump cannot be applied to the application scenes of low-temperature media such as LNG (liquefied natural gas) and the like. Meanwhile, the conventional immersed pump is not provided with an inducer device frequently, the minimum static head of the immersed pump is higher, and the inlet pressure of the immersed pump is required to be higher than the minimum static head during working, so that the requirement of the conventional immersed pump on the minimum liquid level of the storage tank is higher, the LNG storage tank also needs higher pressure, and the thickness and weight of the storage tank in the whole LNG industry are further improved.

In addition, the rotating speed of the traditional motor pump cannot be adjusted in a large range, and the adaptation to working conditions is very limited. Changing the rotation speed in a large range requires replacing the motor and the change gear box, which is not favorable for the adaptive application of the single machine to different scenes.

Disclosure of Invention

In view of the above, the invention provides a low-temperature immersed pump, which is characterized in that a pump part and a motor part are arranged into a split assembly structure, and an inlet shell, a spiral shell, a machine shell and an end cover are sequentially and detachably connected in a sealing manner, so that the efficiency of workers in installation and maintenance of the low-temperature immersed pump is improved.

In order to achieve the purpose, the invention provides the following technical scheme:

a cryogenic submersible pump comprising: a pump portion and a motor portion;

the pump portion includes: an inlet housing, a volute, and a pump body;

the motor part includes: the motor comprises a shell, an end cover and a motor main body arranged in the shell;

the inlet shell, spiral shell, casing and the end cover is sealed in proper order and can dismantle the connection, the pump main part sets up the inlet shell with in the spiral shell.

Preferably, the pump body includes: the centrifugal wheel and the variable pitch inducer wheel are arranged at the inlet of the centrifugal wheel.

Preferably, the method further comprises the following steps:

a front seal ring disposed between the variable pitch inducer and the inlet housing;

and the pump rear sealing ring is arranged between the centrifugal wheel and the screw shell.

Preferably, the pump body includes: the centrifugal pump comprises a shaft system, a centrifugal wheel, an adjusting gasket, a pump end bearing compression nut, a pump end bearing and a bearing seat;

the bearing block is connected with the screw shell through a flange, the pump end bearing is installed on the bearing block and is screwed on the shaft system through the pump end bearing compression nut, and the adjusting gasket is arranged between the centrifugal wheel and the pump end bearing compression nut.

Preferably, the pump body further comprises: and the bearing adjusting pad is arranged between the shafting and the bearing seat.

Preferably, the centrifugal wheel of the pump body is made of an aluminum alloy material and is treated by an anodizing process.

Preferably, the motor main body includes: a motor shaft, a stator and a rotor;

the pump body includes: and the centrifugal wheel is arranged on the motor shaft.

Preferably, the pump body further comprises: the centrifugal wheel is tightly pressed on the shaft system through the on-shaft nut;

and the motor shaft and the nut on the shaft are both provided with backflow hole structures.

Preferably, the pump body includes: a shafting, a centrifugal wheel and a balance mechanism;

the balance mechanism is arranged between the shafting at the rear end of the centrifugal wheel, and/or the balance mechanism is arranged between the rear end of the centrifugal wheel and the screw shell.

Preferably, the method further comprises the following steps: the controller is used for being connected between the motor main body and a power supply and controlling the rotating speed of the motor main body;

the motor main body comprises a rotating speed measuring device which is in communication connection with the controller.

According to the technical scheme, the invention discloses a low-temperature immersed pump, which consists of a pump part and a motor part, wherein the pump part comprises: an inlet housing, a volute, and a pump body; the motor part includes: the motor comprises a shell, an end cover and a motor main body arranged in the shell; the inlet shell, spiral shell, casing and the end cover is sealed in proper order and can dismantle the connection, the pump main part sets up the inlet shell with in the spiral shell. Through the low temperature immersed pump disclosed above, establish pump part and motor part into components of a whole that can function independently assembly structure to with import casing, spiral shell, casing and end cover sealed detachable connection in proper order, make the efficiency of staff when to low temperature immersed pump installation and maintenance obtain promoting.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a detailed structural schematic diagram of a low-temperature immersed pump provided by an embodiment of the invention;

FIG. 2 is a schematic structural diagram of a cryogenic submersible pump with an axial force balancing device according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a low-temperature submersible pump system according to an embodiment of the present invention;

fig. 4 is a schematic diagram of a control method of the low-temperature immersed pump according to an embodiment of the present invention.

The device comprises an inlet shell, a variable pitch inducer, a pump front sealing ring, a sealing gasket, a shaft nut, a spiral shell, a centrifugal wheel, an adjusting gasket, a pump rear sealing ring, a pump end bearing gland nut, a pump end bearing, a sealing gasket, a bearing seat, a bearing adjusting gasket, a shell, a stator, a rotor, a shaft, a tail end bearing, a sealing gasket, a tail end gland nut, an end cover and a balance mechanism, wherein 1 is the inlet shell, 2 is the variable pitch inducer, 3 is the pump front sealing ring, 4 is the sealing gasket, 5 is the shaft nut, 6 is the spiral shell.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The embodiment of the present invention provides a low temperature immersed pump, referring to fig. 1, which is a schematic structural diagram of the low temperature immersed pump according to the embodiment of the present application, and the low temperature immersed pump includes: a pump portion and a motor portion;

it should be noted that the pump part is a machine for transporting or pressurizing a fluid, i.e., a pump, which transfers mechanical energy of a prime mover or other external energy to the fluid to increase the energy of the fluid. The pump is mainly used for conveying liquid such as water, oil, acid-base liquid, emulsion, suspension emulsion and liquid metal, and can also be used for conveying liquid, gas mixture and liquid containing suspended solid. Pumps can be generally classified by their operating principle into three types, positive displacement pumps, dynamic pumps and other types of pumps. In the present application, the type of the pump is selected according to actual requirements, and the type of the pump is not limited herein.

The motor section provides mechanical power to the pump section to enable the pump section to deliver or pressurize fluid.

The pump section includes: an inlet shell 1, a spiral shell 6 and a pump main body;

the motor part includes: a casing 15, an end cover 22 and a motor main body arranged in the casing 15;

the inlet shell 1, the spiral shell 6, the machine shell 15 and the end cover 22 are sequentially connected in a sealing and detachable mode, and the pump main body is arranged in the inlet shell 1 and the spiral shell 6.

It should be noted that, in a specific application, counter bore threads may be uniformly distributed on the screw shell 6 in the circumferential direction, and then connected with the inlet housing 1 through a flange stud.

According to the low-temperature immersed pump disclosed by the invention, the inlet shell 1, the spiral shell 6, the shell 15 and the end cover 22 are sequentially and hermetically connected, so that the whole pump body can be completely immersed in liquid, and the whole noise is low during working; meanwhile, the sealing structure enables the motor and the lead to be naturally isolated from liquid, so that dynamic sealing is not needed, the service life of the pump is prolonged, and the use and maintenance cost is reduced. In addition, the shells of the pump part and the motor part are respectively designed into a split assembly structure, so that the pump part and the motor part are convenient to install and maintain, and the internal structure is adjusted.

Further, the pump body includes: the centrifugal wheel 7 and the variable pitch inducer 2 arranged at the inlet of the centrifugal wheel 7.

It should be noted that the variable pitch inducer 2 is a high-altitude cavitation axial flow impeller, is directly installed at the upstream of the first-stage impeller of the centrifugal impeller 7, and rotates along with the centrifugal impeller 7 when the centrifugal impeller 7 works.

It should be further noted that the variable pitch inducer 2 reduces the static positive suction pressure of the centrifugal wheel 7 by increasing the static pressure at the inlet of the first stage impeller of the centrifugal wheel 7 by the variable pitch inducer 2.

In order to avoid the phenomenon that steam bubbles on the pressure surface of a blade cause the section of a flow passage to be blocked, namely cavitation when the variable pitch inducer 2 works in an overload region, the design flow of the variable pitch inducer 2 is often 1.5-2.3 times of the rated flow of the centrifugal wheel 7, so that when the centrifugal wheel 7 works, the variable pitch inducer 2 always runs in a partial load working region and necessary pressurization is carried out on an impeller of the centrifugal wheel. Therefore, the centrifugal wheel 7 and the variable pitch inducer 2 can better convey the low-temperature fluid medium.

It is worth noting that, because the variable pitch inducer 2 is added in the present application, compared with the prior art, when the inlet pressure of the immersed pump is ensured to be greater than the pressure of the minimum hydrostatic head, the requirement of the immersed pump on the minimum liquid level of the storage tank can be reduced, the LNG storage tank does not need higher pressure, and the thickness and the weight of the whole LNG storage tank can be reduced.

Further, low temperature immersed pump still includes:

the front sealing ring 3 is arranged between the variable pitch inducer 2 and the inlet shell 1;

and a pump rear sealing ring 9 arranged between the centrifugal wheel 7 and the screw shell 6.

It should be noted that the front sealing ring 3 is arranged between the variable pitch inducer 2 and the inlet casing 1, and the pump rear sealing ring 9 is arranged between the centrifugal wheel 7 and the spiral shell 6, so that the isolation from liquid can be effectively prevented, the internal leakage is reduced, and the working performance of the pump part is improved.

Further, the pump body includes: the device comprises a shaft system, a centrifugal wheel 7, an adjusting gasket 8, a pump end bearing compression nut 10, a pump end bearing 11 and a bearing seat 13;

the bearing block 13 is connected with the screw shell 6 through a flange, the pump end bearing 11 is installed on the bearing block 13 and is screwed on a shaft system through a pump end bearing compression nut 10, and the adjusting gasket 8 is arranged between the centrifugal wheel 7 and the pump end bearing compression nut 10.

It should be noted that, the bearing seat 13 is connected with the screw shell 6 through a flange, the pump end bearing 11 is installed on the bearing seat 13, and is screwed on the shaft system through the pump end bearing gland nut 10, so that the installation efficiency of workers during installation can be improved, and the workers can conveniently maintain the shaft system, and are convenient to detach.

It should also be noted that the adjusting washer 8 is disposed between the centrifugal wheel 7 and the pump end bearing compression nut 10, and can be used for adjusting the position deviation between the centrifugal wheel 7 and the screw shell 6, so that the centrifugal wheel 7 and the screw shell 6 are perfectly matched.

Further, the pump body further includes: and a bearing adjusting pad 14 arranged between the shafting and the bearing seat 13.

It should be noted that the bearing adjusting pads 14 are disposed between the bearing adjusting pads 14 between the shaft system and the bearing seat 13, and can be used to adjust the preload of the bearing, so that the bearing can bear the expected load.

Further, the centrifugal wheel 7 of the pump body is made of an aluminum alloy material and is treated by an anodizing process.

It should be noted that, after the centrifugal wheel 7 made of the aluminum alloy material is treated by the anodizing process, the surface hardness and the wear resistance of the centrifugal wheel 7 can be effectively improved.

It should also be noted that the centrifugal wheel 7 is best used with polyimide when being anodized, i.e. the surface hardness and wear resistance of the centrifugal wheel 7 are better.

Further, the motor main body includes: a motor shaft 18, a stator 16, and a rotor 17;

the pump main body includes: the centrifugal wheel 7 is arranged on a motor shaft 18.

It should be noted that the stator 16 is a stationary part of the motor or generator. The stator 16 is composed of a stator core, a stator winding and a base. The main function of the stator 16 is to generate a rotating magnetic field, causing the rotor to turn 17.

It should also be noted that the centrifugal wheel 7 is connected to the motor shaft 18, and the rotor 17 transmits the rotational power to the centrifugal wheel 7 via the motor shaft 18, so that the centrifugal wheel 7 rotates. The motor and the pump impeller are on the same shaft, and the installation and centering adjustment of the coupling are omitted.

Further, the pump body further includes: the on-shaft nut 5 and the centrifugal wheel 7 are tightly pressed on the shaft system through the on-shaft nut 5;

the motor shaft 18 and the on-shaft nut 5 are both provided with a backflow hole structure.

It should be noted that, the on-axis nut 5 is adopted to fix the centrifugal wheel 7 and the shafting, so that the installation in the earlier stage is convenient, and the disassembly in the later maintenance is convenient.

It should also be noted that, the motor shaft 18 and the on-shaft nut 5 are both provided with return hole structures, which can satisfy the cooling requirement when the bearing and the motor work, and do not need to add any other parts to cool the bearing and the motor.

Further, as shown in fig. 2, the pump main body includes: a shafting, a centrifugal wheel 7 and a balance mechanism 23;

the balancing mechanism 23 is arranged between the rear end shafting of the centrifugal wheel 7 and/or the balancing mechanism 23 is arranged between the rear end of the centrifugal wheel 7 and the screw housing 6.

It should be noted that, because the pump may work under the environment with large axial force, a balance mechanism 23 is provided between the shafting at the rear end of the centrifugal wheel 7 and/or between the rear end of the centrifugal wheel 7 and the screw shell 6, and different pressure distributions can be generated along with the movement of the shafting by using the fixed clearance at the rear sealing ring and the variable clearance behind the impeller, so as to realize the function of automatically balancing the axial force. Therefore, in the case of a large axial force, the balancing mechanism 23 in the pump body can extend the service life of the bearing and the overhaul period of the pump body.

Further, as shown in fig. 3 and 4, the low-temperature immersed pump further includes: a controller for connecting between the motor main body and the power supply and controlling the rotation speed of the motor main body;

the motor main part includes the rotational speed measuring device of communication connection in controller.

It should be noted that the controller controls the behavior through three-phase power, and the driving power is sequentially transmitted through the phase line to realize the cyclic action of the driving motor. Meanwhile, a rotating speed measuring device is arranged on the motor main body, and the controller receives a rotating speed feedback signal of the motor and is used for synchronously controlling the power transmitted by the signal through the phase line and detecting and controlling the rotating speed of the motor. The controller power supply is connected with the positive pole and the negative pole of the controller for power supply. The controller can control the rotating speed of the motor main body during working, thereby controlling the pump main body to do work in a rotating way.

Based on the embodiments provided above, referring to fig. 1 to 4, the present solution is further described below with reference to specific embodiments:

the invention creatively designs a single-stage low-temperature immersed pump, which can effectively solve the problems that:

when the low-temperature immersed pump works, the pump rotates at a high speed, LNG is pumped into a storage tank of an onshore transportation device from a transport ship, a power supply provides electric energy for a motor, and the motor drives the immersed pump to rotate to do work according to different application scenes and required rotating speed under the control of a controller.

The controller controls the motor action through three-phase electricity, and the driving power is transmitted in sequence through a phase line to realize the circulating action of the driving motor. Meanwhile, a rotating speed measuring device is arranged on the motor, and the controller receives a rotating speed feedback signal of the motor and is used for synchronizing a control signal (power transmitted through a phase line) and detecting and controlling the rotating speed of the motor. The controller power supply is connected with the positive pole and the negative pole of the controller for power supply.

The low-temperature immersed pump mainly comprises pump parts (1-14) and motor parts (15-22). The pump inlet shell 1 adopts an axial or radial inlet form and is connected with the pump pool structure through a flange. The screw shell 6 is provided with counter bore threads uniformly distributed on the whole circumference and is connected with the inlet shell 1 through a flange stud, and the screw shell 6 and the inlet shell 1 are sealed through an expanded graphite pad 4. A high cavitation erosion resistant variable pitch inducer 2 is arranged at the inlet of the pump, and a centrifugal wheel 7 is tightly pressed on a shaft system through an on-shaft nut 5. An adjusting gasket 8 is arranged behind the centrifugal wheel 7 and used for adjusting the position deviation of the centrifugal wheel 7 and the screw shell 6. A pump front sealing ring 3 and a pump rear sealing ring 9 are arranged between the variable pitch inducer 2, the centrifugal wheel 7 and the shell. The bearing block 13 is connected with the screw shell 6 through a flange, the pump end bearing 11 is installed on the bearing block 13 and is screwed on a shaft system through the pump end bearing compression nut 10, and a bearing adjusting pad 14 is arranged for adjusting the preloading of the bearing. The shell 15 is connected with the screw shell 6 through a flange stud, and the shell is sealed through a sealing gasket 12. A stator 16 is mounted in the housing 15. The rotor 17 is connected with a shaft 18 to drive the shaft system to rotate. An end bearing 19 is mounted on the end of the housing 15 and is secured to the shaft by an end compression nut 21. The end cap 22 is flanged to the housing 15 and sealed with a gasket 20.

THE ADVANTAGES OF THE PRESENT INVENTION

1. The whole pump body is completely immersed in liquid, and the overall noise is low during working.

2. Because the pump is internally provided with a closed system to naturally isolate the motor and the lead from liquid, no dynamic seal is needed, the service life of the pump is prolonged, and the use and maintenance cost is reduced.

3. The motor can better resist the influence of moisture and corrosion, and the insulating property of the motor keeps better and cannot change along with the temperature change.

4. The motor and the pump impeller are on the same shaft, so that the installation and centering adjustment of the coupling are omitted.

5. Because the impeller and the bearing can be cooled and lubricated by the LNG returned from the shaft, an additional lubricating system is not needed, and the problem that the lubricating oil cannot be introduced in a low-temperature environment is solved.

The key point of the invention

1. The high cavitation erosion resistance variable pitch inducer 2 for the liquid rocket engine is added at the inlet of the centrifugal wheel 7, so that the cavitation erosion resistance of the device can be greatly improved, the working condition of the centrifugal wheel is improved, and the working life of the submerged pump is prolonged;

2. the sealing rings 3 and 9 are arranged on the front and rear shoulders of the variable pitch inducer 2 and the centrifugal wheel 7, the sealing rings are made of polyimide materials, polyimide powder is pressed into blanks and then the blanks are finished, the materials are softer than the centrifugal wheel, the abrasion resistance is stronger, even if a static part has friction, large-volume fragments cannot be generated due to abrasion, meanwhile, the sealing rings can keep better mechanical properties at low temperature, and the low-temperature deformation is small.

3. The centrifugal wheel 7 is additionally provided with a front cover plate and a closed centrifugal wheel, and is provided with a front protruding shoulder and a rear protruding shoulder, and the protruding shoulders are provided with seals, so that internal leakage is reduced, and the working performance of the pump is improved.

4. The centrifugal wheel 7 is made of an aluminum alloy material, the surface hardness and the wear resistance are improved through an anodizing process, and the use effect of the centrifugal wheel in cooperation with polyimide is optimal.

5. The bearing is a 3-point contact type angular contact ball bearing, can bear most of axial force, and can meet the use requirement of the whole pump only by two bearings.

6. The motor part adopts the sealed pencil of aluminium pad to penetrate the mouth, realizes soaking the power supply of motor and the sealed of medium, because the motor soaks in low temperature LNG, and the power supply cable adopts multilayer coating technology, adds semiconductor material, insulator material and polytetrafluoroethylene material to increase teflon-stainless steel net protection at the surface outward, and carry out low temperature liquid nitrogen before the use and soak the processing.

7. The copper winding coils on the stator and the rotor of the motor are protected by epoxy resin insulating paint, and low-temperature liquid nitrogen soaking treatment is independently carried out before the motor is assembled. Before the coil is solidified, vacuum impregnation treatment is carried out, so that air gaps can be thoroughly eliminated, and partial discharge in the working process under an immersion liquid environment is prevented.

8. The motor shaft 18 and the nut 5 on the shaft are provided with the backflow hole structures, so that the cooling of the bearing and the motor can be met without adding any other parts.

Further, for a smaller flow rate and a higher usage environment, the pump portion may be increased in stages, such as two or more centrifugal wheels, and an interstage casing may be added between the centrifugal wheels.

For pumps with particularly high flow requirements, the pump inlet housing may be provided as a double suction type.

For a pump working in an environment with a large axial force, an axial force balancing device can be arranged on a shaft or behind an impeller, as shown in fig. 2 below, different pressure distributions can be generated along with the movement of a shaft system by utilizing a fixed gap at the position of a rear sealing ring and a variable gap behind the impeller, and the action of the axial force can be automatically balanced. For the condition of larger axial force, the balance mechanism is added in the pump, so that the service life of the bearing and the overhaul period of the pump can be prolonged.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A cryogenic submersible pump, comprising: a pump portion and a motor portion;

the pump portion includes: the pump comprises an inlet shell (1), a spiral shell (6) and a pump main body;

the motor part includes: the motor comprises a machine shell (15), an end cover (22) and a motor main body arranged in the machine shell (15);

import casing (1), spiral shell (6), casing (15) and end cover (22) seal in proper order and can dismantle the connection, the pump main part sets up import casing (1) with in the spiral shell (6).

2. The cryogenic submersible pump of claim 1, wherein the pump body comprises: the centrifugal impeller comprises a centrifugal wheel (7) and a variable pitch inducer (2) arranged at the inlet of the centrifugal wheel (7).

3. The cryogenic submersible pump of claim 2, further comprising:

a front sealing ring (3) arranged between the variable pitch inducer (2) and the inlet housing (1);

and a pump rear sealing ring (9) arranged between the centrifugal wheel (7) and the screw shell (6).

4. The cryogenic submersible pump of claim 1, wherein the pump body comprises: the centrifugal pump comprises a shaft system, a centrifugal wheel (7), an adjusting gasket (8), a pump end bearing compression nut (10), a pump end bearing (11) and a bearing seat (13);

the bearing block (13) is connected with the screw shell (6) through a flange, the pump end bearing (11) is installed on the bearing block (13) and is screwed on the shaft system through the pump end bearing compression nut (10), and the adjusting gasket (8) is arranged between the centrifugal wheel (7) and the pump end bearing compression nut (10).

5. The cryogenic submersible pump of claim 4, wherein the pump body further comprises: and the bearing adjusting pad (14) is arranged between the shaft system and the bearing seat (13).

6. Low temperature immersed pump according to claim 1, characterized in that the centrifugal wheel (7) of the pump body is made of an aluminium alloy material and is treated by an anodizing process.

7. The cryogenic submersible pump of claim 1, wherein the motor body comprises: a motor shaft (18), a stator (16) and a rotor (17);

the pump body includes: and the centrifugal wheel (7) is arranged on the motor shaft (18).

8. The cryogenic submersible pump of claim 7, wherein the pump body further comprises: the centrifugal wheel (7) is pressed on the shaft system through the on-shaft nut (5);

and the motor shaft (18) and the on-shaft nut (5) are both provided with backflow hole structures.

9. The cryogenic submersible pump of claim 1, wherein the pump body comprises: a shaft system, a centrifugal wheel (7) and a balance mechanism (23);

the balance mechanism (23) is arranged between the rear ends of the centrifugal wheels (7) and the shaft systems, and/or the balance mechanism (23) is arranged between the rear ends of the centrifugal wheels (7) and the screw shell (6).

10. The cryogenic submersible pump of claim 1, further comprising: the controller is used for being connected between the motor main body and a power supply and controlling the rotating speed of the motor main body;