Efficient LNG (Liquefied Natural Gas) gas-liquid multiphase pump

Abstract

The efficient LNG gas-liquid multiphase pump comprises a connecting unit, and the connecting unit comprises a pump shaft; the pressurizing unit comprises at least one centrifugal impeller and at least one mixed flow impeller, and the centrifugal impeller and the mixed flow impeller are connected to the pump shaft in series; and the outer shell comprises a water suction chamber, a water suction chamber gland, a multi-section pump body middle section, a pumping chamber gland and a pumping chamber which are arranged outside the pressurizing unit in a covering manner and are connected in sequence. According to the low-temperature centrifugal pump, the gas-liquid mixed conveying capacity which a low-temperature centrifugal pump does not have is achieved, and the anti-cavitation capacity is further enhanced. And the effects of gas-liquid phase mixed entering and full-liquid-phase high-pressure output are achieved, the impact influence of two-phase flow on a downstream LNG gasifier is avoided, and safe and reliable operation of the whole station yard is further guaranteed.

Description

Technical Field

[0001] The invention relates to a high-efficiency LNG gas-liquid mixed transmission pump, belonging to the technical field of LNG transmission. Background Art

[0002] With the continuous growth of natural gas demand in my country, the construction of LNG receiving stations has become one of the key areas. LNG receiving stations will unload the liquefied natural gas transported to land by offshore LNG ships into storage tanks through ship unloading equipment, and then distribute it to urban gas pipelines or industrial users' facilities. In the production and operation of LNG receiving stations, high-pressure external transmission pumps are one of the most core equipment. Their function is to increase the LNG extracted by low-pressure pumps or LNG after condensing BOG (Boil of Gas) flash gas to a high-pressure state of about 10MPa, so as to facilitate transportation to residents or industrial users through downstream pipelines.

[0003] Low-temperature LNG storage tanks will produce BOG under environmental influences, which will cause the tank pressure to change and be in an unstable state, affecting the subsequent pressurization process. At present, LNG receiving stations are equipped with BOG condensers and high-pressure compressors to handle BOG within a certain flow range, but the main treatment measure for BOG that exceeds the processing capacity of the receiving station is to vent it, which not only wastes precious energy but also pollutes the environment. According to statistics, each ton of LNG leakage will release about 240 cubic meters of natural gas, and methane, the main component of natural gas, is a greenhouse gas that will aggravate the process of global warming. In addition, even if the BOG generation is within the processing capacity of the receiving station, the large fluctuation of BOG generation will cause the change of the condenser outlet temperature, which will in turn affect the stability of the downstream LNG high-pressure external transmission process. The operation of the high-pressure BOG compressor will greatly increase energy consumption, and both economic and environmental protection will be seriously damaged. Therefore, in the construction and operation of LNG receiving stations, how to use appropriate methods to handle the continuously generated BOG and overcome the impact of its large flow fluctuations under extreme conditions is an urgent problem to be solved.

[0004] Inspired by the oil and gas mixed transportation pumps in the oil and gas production field, the mixed transportation of BOG and LNG can effectively solve the above problems. However, there is currently no multiphase pump that can handle the LNG-BOG multiphase flow with a certain gas content of the imported gas when LNG is transported at high pressure.

[0005] Cryogenic centrifugal pumps are commonly used in the field of LNG high-pressure transportation. Most of them adopt a vertical structure, mainly including a pump shaft, an inducer, a multi-stage centrifugal impeller, an external motor, inlet and outlet flanges, etc. The working process is that LNG enters the pump body from the inlet of the outer cylinder, and the motor drives the multi-stage impeller to work in the pump body through the main shaft. After entering the pump body, the LNG is guided from the pump suction chamber to the inlet of the first-stage impeller through the inducer, and then passes through the last-stage impeller under the multi-stage impeller pressurization to obtain pressure energy and kinetic energy, and then enters the LNG high-pressure main pipe through the pump internal pipeline and the pump outlet.

[0006] When conventional cryogenic centrifugal pumps transport two-phase flow, the density of the gas and liquid differs too much, and the centrifugal force generated by the rotation of the impeller exacerbates the separation of the gas-liquid two-phase. When the gas content in LNG increases, the gas occupies a larger space inside the pump, resulting in a significant decrease in pump efficiency. The gas compressibility and volume change greatly, which may also cause vibration and instability of the pump. In addition, the existing centrifugal pumps have a high pressure ratio and weak anti-cavitation ability. Bubbles are easily formed on the suction side of the pump, and they are squeezed and collapsed in the high-pressure area, which will cause damage to the pump in severe cases. In short, the existing centrifugal pumps are not suitable for LNG-BOG two-phase transportation. Therefore, under the premise of ensuring the normal production and operation of the receiving station, an efficient LNG gas-liquid mixed transmission pump is invented to achieve continuous processing of large flow BOG, which will have a revolutionary breakthrough in the operation process of the receiving station. Summary of the invention

[0007] In view of the above technical problems, the present invention provides a high-efficiency LNG gas-liquid mixed delivery pump, which realizes the gas-liquid mixed delivery capability that low-temperature centrifugal pumps do not have, and further enhances the anti-cavitation capability. It also realizes the effect of mixed gas-liquid phase entry and full liquid phase high-pressure output, avoiding the impact of two-phase flow on the downstream LNG gasifier, and further ensuring the safe and reliable operation of the entire station.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A high-efficiency LNG gas-liquid mixed transmission pump, comprising:

[0010] a connecting unit, the connecting unit comprising a pump shaft;

[0011] A booster unit, the booster unit comprising at least one centrifugal impeller and at least one mixed flow impeller, the centrifugal impeller and the mixed flow impeller being connected in series on the pump shaft;

[0012] The outer shell includes a water suction chamber, a water suction chamber pressure cover, a multi-section pump body middle section, a water pressure chamber pressure cover and a water pressure chamber, which are arranged outside the booster unit and are connected in sequence.

[0013] In the high-efficiency LNG gas-liquid mixed transfer pump, preferably, the mixed flow impeller comprises an impeller shaft and a plurality of mixed flow impeller spiral blades, and the plurality of mixed flow impeller spiral blades are evenly spaced along the circumference of the impeller shaft.

[0014] The high-efficiency LNG gas-liquid mixed transfer pump preferably comprises: the mixed flow impeller further comprises a plurality of mixed flow guide vanes, the plurality of mixed flow guide vanes are evenly arranged at circumferential intervals along the impeller shaft, the mixed flow guide vanes are mixed flow guide vane spiral blades, and are arranged at the fluid outlet of the mixed flow impeller spiral blades.

[0015] In the high-efficiency LNG gas-liquid mixed transfer pump, preferably, the centrifugal impeller is a semi-open impeller.

[0016] In the high-efficiency LNG gas-liquid mixed transfer pump, preferably, the centrifugal impeller includes a hub and a rear cover plate extending outwardly along the circumference of the hub, and the rear cover plate is provided with a plurality of blades arranged at intervals.

[0017] In the high-efficiency LNG gas-liquid mixed transfer pump, preferably, the connection unit further comprises a first bearing and a second bearing, and the first bearing and the second bearing are fastened to both ends of the pump shaft by pre-tightening members.

[0018] The high-efficiency LNG gas-liquid mixed transfer pump, preferably, the connecting unit also includes a first sealing sleeve and a second sealing sleeve, the first sealing sleeve and the second sealing sleeve are mounted on the pump shaft, the second sealing sleeve is located on one side of the water suction chamber, and the first sealing sleeve is located on one side of the water pressure chamber.

[0019] The high-efficiency LNG gas-liquid mixed transfer pump, preferably, the outer shell further includes an inlet flange and an outlet flange, the inlet flange is arranged on the water absorption chamber, and the outlet flange is arranged on the water pressure chamber.

[0020] The high-efficiency LNG gas-liquid mixed transfer pump, preferably, the external shell further includes two connecting shells, and the two connecting shells are respectively connected to the water absorption chamber and the water pressure chamber.

[0021] The high-efficiency LNG gas-liquid mixed transfer pump, preferably, the outer shell also includes an end cover, the end cover is connected to the connecting shell located on one side of the water absorption chamber, and the other end of the pump shaft is connected to the motor through a coupling.

[0022] The present invention adopts the above technical solution, which has the following advantages:

[0023] Improve the efficiency and safety of LNG pipeline transmission. Multiphase pumps that adapt to LNG-BOG multiphase fluids can better handle multiphase fluids with high gas content, thereby ensuring the normal operation of pressurized transmission, reducing the existing BOG processing systems and related equipment at the receiving station, reducing the production costs of enterprises, and improving production efficiency. This has revolutionary significance for the field of LNG transmission. In addition, it can also reduce problems such as energy loss and environmental pollution caused by excessive BOG venting. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 An overall schematic diagram of a high-efficiency LNG gas-liquid mixed transport pump provided by one embodiment of the present invention;

[0025] Figure 2 A partial cross-sectional view of a high-efficiency LNG gas-liquid mixed delivery pump provided in this embodiment of the present invention;

[0026] Figure 3 A side view of the mixed flow impeller and guide vanes provided in this embodiment of the present invention;

[0027] Figure 4 A front view of the mixed flow impeller and guide vanes provided in this embodiment of the present invention;

[0028] Figure 5 A cross-sectional view of a centrifugal impeller provided in this embodiment of the present invention;

[0029] Figure 6 A front view of a centrifugal impeller provided in this embodiment of the present invention;

[0030] Figure 7 A three-dimensional diagram of a centrifugal impeller provided in this embodiment of the present invention;

[0031] The reference numerals in the figures are as follows:

[0032] 1-end cover; 2-connecting shell; 3-water suction chamber; 4-water suction chamber gland; 5-middle section of multi-section pump body; 6-fastening bolts; 7-pressure chamber gland; 8-pressure chamber; 9-outlet flange; 10-coupling; 11-first bearing; 12-first sealing sleeve; 13-centrifugal impeller; 14-mixed flow guide vane; 15-mixed flow impeller; 16-inlet flange; 17-second sealing sleeve; 18-pump shaft; 19-second bearing; 20-nut;

[0033] 1301-blade; 1302-rear cover; 1303-hub. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work are within the scope of protection of the present invention.

[0035] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second", "third", "fourth" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" and the like mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0036] For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures, such as "inside", "outside", "inner side", "outer side", "below", "above", etc. Such spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0037] When conventional cryogenic centrifugal pumps transport two-phase flow, the density of the gas and liquid differs too much, and the centrifugal force generated by the rotation of the impeller exacerbates the separation of the gas-liquid two-phase. When the gas content in LNG increases, the gas occupies a larger space inside the pump, resulting in a significant decrease in pump efficiency. The gas compressibility and volume change greatly, which may also cause vibration and instability of the pump. In addition, the existing centrifugal pumps have a high pressure ratio and weak anti-cavitation ability. Bubbles are easily formed on the suction side of the pump, and they are squeezed and collapsed in the high-pressure area, which will cause damage to the pump in severe cases. In short, the existing centrifugal pumps are not suitable for LNG-BOG two-phase transportation. Therefore, under the premise of ensuring the normal production and operation of the receiving station, an efficient LNG gas-liquid mixed transmission pump is invented to achieve continuous processing of large flow BOG, which will have a revolutionary breakthrough in the operation process of the receiving station.

[0038] Based on the above technical problems, the present invention provides a high-efficiency LNG gas-liquid mixed delivery pump, which realizes the gas-liquid mixed delivery capability that low-temperature centrifugal pumps do not have, and further enhances the anti-cavitation capability. It also realizes the effect of gas-liquid mixed entry and full liquid high-pressure output, avoiding the impact of two-phase flow on the downstream LNG gasifier, and further ensuring the safe and reliable operation of the entire station.

[0039] like Figure 1 , 2 As shown in Figure 3, the high-efficiency LNG gas-liquid mixed transmission pump involved in the present invention includes three parts: a booster unit, a connecting unit, and an external shell.

[0040] Specifically, the booster unit includes a mixed flow impeller 15 driven by a motor to provide a certain axial thrust and centrifugal force to the gas-liquid two-phase, and a multi-stage centrifugal impeller 13 for further boosting and outputting after the mixed flow is pressurized.

[0041] The connecting unit mainly includes the pump shaft 18 which is connected in series with the impeller group of the booster unit, which is also the shaft body supporting the rotation of the impeller group, the nut 20 which fastens the pump shaft parts unit (such as the multi-stage impeller and the bearing) and provides a certain preload force to affect the sealing of the pump body and the working performance of the impeller, the first bearing 11 and the second bearing 19 which are necessary for the rotation of the pump shaft 18, and the first sealing sleeve 12 and the second sealing sleeve 17 which prevent the leakage of the transported liquid during the operation of the pump body, which are respectively installed at the two ends of the working range cavity of the pump body.

[0042] The outer shell includes an end cover 1 which is fastened with screws and provides a certain installation space for its nut 20, and an inlet flange 16 is added to provide an initial space for the LNG two-phase liquid to enter the pump body. The suction chamber 3 is fixedly connected to the connecting shell 2, and the pressure chamber 8 is the same. The suction chamber gland 7 that isolates the inner cavity of the suction chamber from the pressurized mixing chamber is adapted to the number of impellers of the relevant boosting unit to achieve a multi-section pump body middle section 5 that can change with the impeller and the length of the pump body accordingly, and is used to fasten the pump body middle section 5, the fastening bolts 6 connecting the suction chamber 3 and the pressure chamber 8, the pressure chamber gland 7 that is used to isolate the pressure chamber 8 from the inner cavity where the boosting impeller is located, and the pressure chamber 8 equipped with its outlet flange 9 discharges the multi-phase liquid with reduced gas content in the gas-liquid two phases after its pressurization.

[0043] Furthermore, if Figure 3 , 4 As shown, the mixed flow impeller 15 includes an impeller shaft and a plurality of mixed flow impeller spiral blades, and the plurality of mixed flow impeller spiral blades are evenly arranged along the circumferential direction of the impeller shaft. The mixed flow impeller 15 also includes a plurality of mixed flow guide vanes 14, and the plurality of mixed flow guide vanes 14 are evenly arranged along the circumferential direction of the impeller shaft. The mixed flow guide vanes 14 are mixed flow guide vane spiral blades and are arranged at the fluid outlet of the mixed flow impeller spiral blades.

[0044] like Figure 5-7 As shown, the centrifugal impeller 13 is a semi-open impeller, including a hub 1303 and a rear cover plate 1302 extending outwardly along the circumference of the hub 1303 , and a plurality of blades 1301 arranged at intervals are provided on the rear cover plate 1302 .

[0045] Furthermore, the pump shaft 18 is designed with a groove in which a positioning pin is installed to facilitate the positioning and installation of the impeller of the booster unit. The contact surface between the pump shaft 18 and the impeller unit should be smooth and flat to avoid friction causing pump body failure. The connection of the multi-section pump body middle section 5 is connected through a groove, an O-ring is installed in the middle, and the seal is tightened by bolts.

[0046] Furthermore, the bearings (first bearing 11 and second bearing 19) that carry the rotational motion of the pump shaft 18 driven by the motor should be deep groove ball bearings on parts that can bear radial loads or combined loads acting radially and axially at the same time.

[0047] Furthermore, the fastening bolts 6 are mainly connected to the suction chamber gland 4 and the pressure chamber gland 7, wherein the glands of the two have through holes at the circumference corners thereof, and the set screws are reinforced therein, and the length thereof should depend on the number of impellers required for the working conditions, and the middle section 5 of the multi-section pump body is the same as above. In a preferred embodiment of the present invention, modular assembly can be performed according to demand, by adding different numbers of centrifugal impellers 13 to achieve the specified pressure head, and adjusting the number of mixed flow impellers 15 to adapt to different degrees of inlet air content.

[0048] Furthermore, the cryogenic gas-liquid mixed transmission pump involved should adopt a horizontal structure and be fixed on the working surface by bolt supports, and shaking of the working pump body should be avoided.

[0049] The working principle of the present invention is described in detail below in conjunction with the operating examples.

[0050] First, a mixture of natural gas and liquid natural gas (LNG) is transported from a storage tank to a mixed flow pump system through a pipeline. The mixed flow pump system is designed with a mixed flow impeller 15 and a centrifugal impeller 13 to handle gas and liquid at the same time to ensure that it can work properly even when a certain proportion of gas is contained in the liquid. The mixture of LNG and natural gas first enters the suction chamber 3 through the inlet flange 16, and then is driven by the mixed flow impeller 15 to rotate. These impellers are specially designed to effectively handle gas-liquid two-phase flow. The impeller structure is such that when the impeller rotates, the two-phase flow is subjected to both centrifugal force and axial thrust, so that it can work properly even when a certain proportion of gas is contained in the liquid.

[0051] After the initial pressurization by the mixed flow impeller 15, the gas phase in the transport medium is effectively controlled and reduced, and the LNG-BOG two-phase flow realizes a gas phase phase change to obtain a two-phase flow with a low gas content. When the gas phase is reduced to a certain level or even disappears, it will be transported to the multi-stage centrifugal impeller 13 through the mixed flow guide vane 14 for pressurized external transmission. After the pressurization of the boosting unit is completed, the two-phase flow with a low gas content enters the pressure water chamber and is transported through the outlet flange 9 for pipeline transportation.

[0052] The combination of the multi-stage mixed flow impeller 15 and the multi-stage centrifugal impeller 13 can effectively reduce the influence of the gas phase on the pump and improve the conveying efficiency.

[0053] In this embodiment, the mixed flow impeller 15 is driven by a motor to rotate the impeller during operation. The particularity of the impeller structure causes the LNG-BOG two-phase flow to be affected by both centrifugal force and axial thrust. Since the inlet and outlet chambers of the mixed flow pump are both axial flow channels, the fluid can flow under the impetus of the axial force during the pumping process, which helps to effectively reduce the impact of centrifugal force alone on the separation of gas-liquid two-phases, such as the gas phase flow channel accumulation and cavitation problems that are easy to produce. Under the combined action of the two forces, the mixed flow pump pushes the fluid in the axial and radial directions, which helps to better mix and dissolve the two-phase fluid and reduce the unit volume of undissolved gas in the form of bubbles. When transporting gas and liquid phases, this helps to reduce the tendency of gas-liquid separation. Reducing the bubble diameter increases the viscosity of the gas phase and reduces the Reynolds number, which leads to an increase in the resistance between the gas and liquid phases, which helps to maintain the mixing state of the two phases and inhibit the separation of the two phases.

[0054] As attached Figure 3 , 4 As shown, the structure and action mechanism of the mixed flow impeller are explained.

[0055] The main body of the mixed flow impeller is composed of two parts, namely the mixed flow impeller 15 and the mixed flow guide vane 14. The mixed flow impeller 15 is used to pressurize and push the fluid, and needs to be designed with appropriate blade geometry and angle to effectively increase the pressure and velocity of the fluid, thereby pushing the fluid through the output port of the pump. The mixed flow impeller 15 transfers the liquid from the suction end to the discharge end of the pump by transferring mechanical energy to the fluid, and increases the pressure and velocity of the fluid in the process.

[0056] The mixed flow guide vane 14 is located at the outlet of the mixed flow impeller 15, and its main function is to control and adjust the flow direction and flow rate of the fluid. The design of the guide vane can adjust the performance and output of the pump as needed. By adjusting the angle and position of the guide vane, the efficiency and performance of the pump can be optimized, ensuring that the fluid maintains the best flow conditions when passing through the pump body, reducing the energy loss of the liquid and the resistance of the pump.

[0057] The overall design process includes detailed planning of the mixed flow impeller 15 and the mixed flow guide vane 14. First, the basic parameters of the pump are calculated according to the required flow rate and head, and the number, shape and blade angle distribution of the impeller are determined. Subsequently, computer-aided design tools are used to perform three-dimensional modeling and flow field analysis of the impeller to optimize the fluid dynamics characteristics of the blades, and structural analysis is performed to ensure that the impeller has sufficient strength and stability when rotating at high speeds.

[0058] Subsequently, the guide vanes are designed to optimize the velocity distribution and flow direction of the fluid, and the effect of the guide vane design is verified through CFD analysis to reduce energy loss. Finally, samples are manufactured for experimental verification, and adjustments and optimizations are made based on the experimental results and analysis feedback to ensure that the mixed flow pump meets the design requirements in actual operation and improves its overall performance and efficiency.

[0059] The mixed flow impeller 15 performs relatively well when conveying a two-phase flow with a certain inlet gas content, can better adapt to the two-phase incoming flow, and can be pressurized internally to achieve gas phase change. Because the bubbles are subjected to forces in different directions of the impeller, the bubbles are more evenly present in the liquid to form small bubbles, which increases the dispersion of the gas phase and promotes the subsequent transformation to the liquid phase.

[0060] As attached Figure 5-7 As shown, after the LNG-BOG two-phase flow undergoes a phase change in the mixing unit, it enters the centrifugal supercharging stage in a full liquid phase state, achieving a rapid increase in pressure. The centrifugal impeller 13 adopts a semi-open impeller structure, and a sealing ring with an adjustable gap is required to increase the efficiency. The semi-open impeller is suitable for conveying liquids containing suspended solids, fibers, etc., with low manufacturing difficulty, low cost, and strong adaptability. It is widely used in chemical centrifugal pumps and can be used to convey high-pressure liquids. Its design process is not the focus of the present invention, so it will not be described.

[0061] An alternative to the present invention is to replace the impeller boosting unit of the mixed flow pump with the impeller boosting unit of the axial flow pump in the high-pressure export pump. The working principle of this scheme is as follows: when the multiphase fluid flows into the high-pressure export pump, the gas therein is guided to the axial flow pump boosting unit. The axial flow pump pressurizes and mixes the gas through the impeller, mixes it with the liquid again and sends it back to the centrifugal impeller group of the high-pressure export pump for further pressurization and transportation. In the axial flow pump boosting unit, gas compression is achieved by the rotation and geometry of the impeller. The impeller captures the gas and pushes it to the outlet of the pump, and through continuous compression and mixing, the gas volume is reduced to achieve the pressurization process. The advantages of this scheme include reducing gas content, improving pump stability and saving energy. However, in specific applications, engineering design and parameter selection need to be carried out according to actual conditions, and ensure that the axial flow pump has good sealing and corrosion resistance to adapt to the special environmental conditions of LNG transportation.

[0062] The present invention can improve the transfer efficiency of the fluid by optimizing the impeller design and the supercharging process. The effective impeller design can reduce energy loss and provide a higher fluid driving force, thereby achieving a higher speed and a larger flow rate. The supercharging unit design can increase the pressure of the fluid and improve the delivery efficiency.

[0063] For LNG-BOG multiphase fluid, its characteristics include high pressure, low temperature and high viscosity, which places high requirements on equipment. Optimized gas-liquid mixed pump design can provide better stability and reliability, reduce failure and maintenance requirements, and reduce production risks. Optimized design can reduce energy consumption. By reducing energy losses and improving efficiency, the energy required for system operation can be reduced, reducing production costs. This is particularly important for the LNG industry, as energy consumption is a major component of operating costs.

[0064] LNG-BOG multiphase fluid has complex physical properties, including different phases, density and viscosity, etc. By designing according to the characteristics of multiphase fluid, the adaptability and stability of the equipment can be improved to ensure the effective transmission and processing of the fluid.

[0065] In summary, the present invention proposes an efficient LNG gas-liquid mixed transmission pump design device, which aims to solve the problems existing in the existing cryogenic centrifugal pumps when processing gas-liquid two-phase flow. The device adopts a combined design of a mixed flow impeller 15 and a multi-stage centrifugal impeller 13, which can effectively process gas-liquid two-phase flow, improve anti-cavitation ability, and reduce pump damage caused by pressure in the high-pressure area. Its structure includes three main units: a booster unit, a connection unit, and an external shell. The booster unit realizes gas-liquid mixed transmission and pressurization through a mixed flow impeller 15 and a multi-stage centrifugal impeller 13, and the connection unit is responsible for the support and sealing of the pump shaft. The external shell includes components such as a water suction chamber and a water pressure chamber to complete the entry, exit, and discharge of the medium. The advantage of this device is that it can effectively reduce the impact of the gas phase on the pump, improve the transportation efficiency, and can operate stably under gas-liquid two-phase transportation conditions.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-efficiency LNG gas-liquid mixed transport pump, characterized in that: include: A connecting unit, the connecting unit comprising a pump shaft (18); A booster unit, the booster unit comprising at least one centrifugal impeller (13) and at least one mixed flow impeller (15), the centrifugal impeller (13) and the mixed flow impeller (15) being connected in series on the pump shaft (18); An external shell, the external shell comprising a water suction chamber (3) which is arranged outside the booster unit and is connected in sequence, a water suction chamber gland (4), a multi-section pump body middle section (5), a water pressure chamber gland (7) and a water pressure chamber (8).

2. The high-efficiency LNG gas-liquid mixed delivery pump according to claim 1 is characterized in that: The mixed flow impeller (15) comprises an impeller shaft and a plurality of mixed flow impeller spiral blades, wherein the plurality of mixed flow impeller spiral blades are evenly spaced along the circumference of the impeller shaft.

3. The high-efficiency LNG gas-liquid mixed delivery pump according to claim 2 is characterized in that: The mixed flow impeller (15) further comprises a plurality of mixed flow guide vanes (14), wherein the plurality of mixed flow guide vanes (14) are evenly spaced along the circumference of the impeller shaft, and the mixed flow guide vanes (14) are mixed flow guide vane spiral blades and are arranged at the fluid outlet of the mixed flow impeller spiral blades.

4. The high-efficiency LNG gas-liquid mixed delivery pump according to claim 1 is characterized in that: The centrifugal impeller (13) is a semi-open impeller.

5. The high-efficiency LNG gas-liquid mixed delivery pump according to claim 4 is characterized in that: The centrifugal impeller (13) comprises a hub (1303) and a rear cover plate (1302) extending outwardly along the circumference of the hub (1303), and a plurality of blades (1301) arranged at intervals are provided on the rear cover plate (1302).

6. The high-efficiency LNG gas-liquid mixed delivery pump according to claim 1 is characterized in that: The connection unit further comprises a first bearing (11) and a second bearing (19), wherein the first bearing (11) and the second bearing (19) are fastened to both ends of the pump shaft (18) via a pre-tightening member.

7. The high-efficiency LNG gas-liquid mixed transfer pump according to claim 6 is characterized in that: The connecting unit further comprises a first sealing sleeve (12) and a second sealing sleeve (17), wherein the first sealing sleeve (12) and the second sealing sleeve (17) are sleeved on the pump shaft (18), the second sealing sleeve (17) is located on one side of the water suction chamber (3), and the first sealing sleeve (12) is located on one side of the water pressure chamber (8).

8. The high-efficiency LNG gas-liquid mixed delivery pump according to claim 1 is characterized in that: The outer shell further comprises an inlet flange (16) and an outlet flange (9), wherein the inlet flange (16) is arranged on the water suction chamber (3), and the outlet flange (9) is arranged on the water pressure chamber (8).

9. The high-efficiency LNG gas-liquid mixed delivery pump according to claim 1, characterized in that: The external shell further comprises two connecting shells (2), and the two connecting shells (2) are respectively connected to the water absorption chamber (3) and the water pressure chamber (8).

10. The high-efficiency LNG gas-liquid mixed transfer pump according to claim 9, characterized in that: The outer shell further comprises an end cover (1), the end cover (1) being connected to the connecting shell (2) located on one side of the water absorption chamber (3), and the other end of the pump shaft (18) being connected to the motor via a coupling (10).

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