Balanced multi-stage centrifugal pump

Abstract

The invention relates to the technical field of multi-stage centrifugal pumps, and discloses a balanced multi-stage centrifugal pump, a water inlet and outlet section assembly is provided with a balance cavity, a balance hole, a medium outlet and a high-pressure choked flow inlet, the medium outlet and the high-pressure choked flow inlet are respectively communicated with a high-pressure section, and the high-pressure choked flow inlet is located between a pump shaft and the medium outlet. The high-pressure choke flow inlet is communicated with the balance cavity, and the balance cavity is communicated with the transition bent pipe through the balance hole. According to the balance type multi-stage centrifugal pump, the effect of residual axial force on the low-pressure section impeller is reduced, adjustment of the residual axial force of the multi-stage centrifugal pump is achieved, and reliable and safe operation of the multi-stage pump is guaranteed.

Description

Technical Field

[0001] This invention relates to the technical field of multistage centrifugal pumps, and in particular to a balanced multistage centrifugal pump. Background Technology

[0002] Multistage centrifugal pumps are widely used in petroleum, chemical, and power industries to transport liquid media requiring high pressure output. They consist of multiple impellers arranged in series, pressurizing the medium stage by stage under the drive of the pump shaft to achieve high output pressure. However, during the operation of traditional multistage centrifugal pumps, the significant pressure difference between each impeller stage generates substantial axial forces, especially at the last impeller stage. Although structures such as balance discs or balance drums are typically used to offset most of the axial force, a certain amount of residual axial force is unavoidable. This residual axial force acts on the rotor system over a long period, easily leading to problems such as bearing wear, rotor misalignment, and even pump body vibration, affecting the stability and service life of the equipment. Summary of the Invention

[0003] The invention aims to at least solve one of the technical problems existing in the prior art. It provides a balanced multistage centrifugal pump that reduces the effect of residual axial force on the low-pressure section impeller, thereby achieving adjustment of the residual axial force in the multistage centrifugal pump and ensuring reliable and safe operation.

[0004] To achieve the above objectives, the present invention provides a balanced multistage centrifugal pump, comprising a low-pressure section, a high-pressure section, an inlet / outlet water section assembly, a transition bend, and a pump shaft. The inlet / outlet water section assembly is located between the low-pressure section and the high-pressure section. The pump shaft is coaxially inserted through the low-pressure section, the inlet / outlet water section assembly, and the high-pressure section. The low-pressure section is provided with a medium inlet. The low-pressure section is connected to one end of the transition bend through the inlet / outlet water section assembly, and the other end of the transition bend is connected to the end of the high-pressure section away from the inlet / outlet water section.

[0005] The inlet and outlet water section assembly is provided with a balance chamber, a balance hole, a medium outlet, and a high-pressure flow-blocking inlet. The medium outlet and the high-pressure flow-blocking inlet are respectively connected to the high-pressure section. The high-pressure flow-blocking inlet is located between the pump shaft and the medium outlet. The high-pressure flow-blocking inlet is connected to the balance chamber. The balance chamber is connected to the transition bend through the balance hole.

[0006] As a preferred embodiment, the inlet / outlet water section assembly includes an inlet / outlet water section, a balance shaft sleeve, and a high-pressure throttling ring. The balance chamber, the balance hole, and the medium outlet are respectively opened in the inlet / outlet water section. The high-pressure throttling ring is connected to the side of the inlet / outlet water section facing the high-pressure section. The balance shaft sleeve is sleeved on the outer periphery of the pump shaft. The high-pressure throttling ring is sleeved on the end of the balance shaft sleeve facing the high-pressure section. One end of the high-pressure throttling ring and the balance shaft sleeve define a high-pressure flow-blocking inlet. The other end of the high-pressure throttling ring is located in the balance chamber.

[0007] As a preferred embodiment, the inlet / outlet water section assembly further includes a low-pressure throttling ring. The low-pressure throttling ring is connected to the side of the inlet / outlet water section facing the low-pressure section. The low-pressure throttling ring is sleeved on the end of the balance shaft sleeve facing the low-pressure section. One end of the low-pressure throttling ring is located in the balance cavity and forms a medium diffusion port between itself and the high-pressure throttling ring. The other end of the low-pressure throttling ring forms a low-pressure flow-blocking outlet between itself and the balance shaft sleeve. The low-pressure flow-blocking outlet is connected to the transition bend.

[0008] As a preferred embodiment, the inlet and outlet water sections are provided with high-pressure ring connection ports and low-pressure ring connection ports at both ends of the axial direction. The high-pressure ring connection ports are arranged facing the high-pressure section, and the high-pressure throttling ring is connected to the high-pressure ring connection port. The low-pressure ring connection ports are arranged facing the low-pressure section, and the low-pressure throttling ring is connected to the low-pressure ring connection port.

[0009] As a preferred embodiment, the inlet and outlet water sections are provided with a high-pressure annular cavity, which is located on the side of the balance cavity facing the high-pressure section. The high-pressure annular cavity surrounds the outer periphery of the balance cavity, and the opening of the high-pressure annular cavity faces the high-pressure section and communicates with the high-pressure section. The medium outlet is located at the end of the high-pressure annular cavity away from the high-pressure section.

[0010] As a preferred embodiment, a high-pressure balance flow channel is defined between the inlet / outlet section and the high-pressure section. One end of the high-pressure balance flow channel is connected to the high-pressure annular cavity and the high-pressure section, respectively, and the other end is connected to the high-pressure flow-blocking inlet.

[0011] As a preferred embodiment, the inlet and outlet water sections are provided with a low-pressure ring cavity, which is located on the side of the balance cavity facing the low-pressure section. The low-pressure ring cavity surrounds the outer periphery of the balance cavity, and the opening of the low-pressure ring cavity faces the low-pressure section and is connected to the low-pressure section and the transition bend respectively. The balance cavity is connected to the low-pressure ring cavity through the balance hole.

[0012] As a preferred embodiment, a low-pressure balance flow channel is defined between the inlet / outlet section and the low-pressure section. One end of the low-pressure balance flow channel is connected to the low-pressure annular cavity and the low-pressure section, and the other end is connected to the low-pressure flow-blocking outlet.

[0013] As a preferred embodiment, a plurality of balance holes are provided, and the plurality of balance holes are spaced apart circumferentially along the low-pressure annular cavity.

[0014] As a preferred embodiment, the balancing hole has an inlet end and an outlet end, the inlet end is connected to the balancing cavity, the outlet end is connected to the low-pressure annular cavity, and the diameter of the inlet end is smaller than the diameter of the outlet end.

[0015] Compared with existing technologies, the balanced multistage centrifugal pump of this invention has the following advantages: it includes a low-pressure section, a high-pressure section, an inlet / outlet water section assembly, a transition bend, and a pump shaft. The low-pressure section, inlet / outlet water section assembly, transition bend, and high-pressure section are connected to form a complete fluid cavity. The medium enters the fluid cavity from the medium inlet of the low-pressure section. The pump shaft passes through the low-pressure section, the inlet / outlet water section assembly, and the high-pressure section, respectively, and drives the impellers in the low-pressure and high-pressure sections to rotate, thereby pressurizing the medium in the fluid cavity. The inlet / outlet water section assembly is provided with a balance chamber, a balance hole, a medium outlet, and a high-pressure flow-blocking inlet. The medium outlet and the high-pressure flow-blocking inlet are respectively connected to the high-pressure section. The high-pressure flow-blocking inlet is located between the pump shaft and the medium outlet. Most of the high-pressure medium in the high-pressure section flows out from the medium outlet, and the high-pressure medium enters the balance chamber through the high-pressure flow-blocking inlet. The high-pressure flow-blocking inlet, the balance chamber, and the balance hole are connected to form a pressure regulation path. After the high-pressure medium in the high-pressure section enters the balance chamber through the high-pressure flow-blocking inlet, the balance chamber acts as a pressure buffer container, absorbing pressure pulsations through its volume effect. The high-pressure medium in the balance chamber diffuses and depressurizes through the balance hole, and finally flows back to the high-pressure section through the transition bend, reducing the effect of residual axial force on the impeller in the low-pressure section. This achieves the regulation of residual axial force in the multi-stage centrifugal pump, ensuring the reliable and safe operation of the multi-stage pump. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the inlet and outlet water section assembly according to an embodiment of the present invention.

[0017] Figure 2 This is an embodiment of the present invention. Figure 1 A magnified structural diagram at point 5A.

[0018] Figure 3 This is a schematic cross-sectional view of the inlet and outlet water sections according to an embodiment of the present invention.

[0019] Figure 4 This is a schematic diagram of the structure of the inlet and outlet water sections facing the low-pressure section in an embodiment of the present invention.

[0020] Figure 5 This is a schematic diagram of the structure of the inlet and outlet water section facing the high-pressure section in an embodiment of the present invention.

[0021] Figure 6 This is a cross-sectional structural diagram of the balance bushing according to an embodiment of the present invention.

[0022] Figure 7 This is a cross-sectional structural diagram of the high-pressure throttling ring according to an embodiment of the present invention.

[0023] Figure 8 This is an embodiment of the present invention. Figure 1 A magnified structural diagram at point 5B.

[0024] Figure 9 This is an embodiment of the present invention. Figure 1 A magnified structural diagram at point 5C.

[0025] Figure 10 This is a schematic diagram of the low-pressure throttling ring in an embodiment of the present invention.

[0026] Figure 11 This is a schematic diagram of the overall structure of an embodiment of the present invention.

[0027] In the picture:

[0028] 1001, Low-pressure section; 1002, Medium inlet; 1011, Low-pressure chamber; 1013, Low-pressure impeller;

[0029] 2001, High-pressure section; 2010, High-pressure chamber; 2012, High-pressure impeller;

[0030] 3000, Inlet / Outlet Water Section Assembly; 3001, Inlet / Outlet Water Section; 3002, Medium Outlet; 3007, Balance Chamber; 3008, Balance Hole; 3009, High-Pressure Ring Connection Port; 3010, Low-Pressure Ring Connection Port; 3011, High-Pressure Ring Chamber; 3012, Low-Pressure Ring Chamber; 3013, Inlet End; 3014, Outlet End;

[0031] 4001, Transition bend;

[0032] 5001, Pump Shaft;

[0033] 7001, Balance sleeve; 7002, First thrust groove; 7004, High-pressure balance flow channel; 7008, High-pressure flow-blocking inlet; 7014, High-pressure flow-blocking thread; 7016, Low-pressure flow-blocking thread; 7017, Low-pressure flow-blocking outlet; 7020, Low-pressure balance flow channel;

[0034] 8001, High-voltage throttling ring;

[0035] 9001, Low-pressure throttling ring; 9004, Medium diffuser port. Detailed Implementation

[0036] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0037] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" used to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0038] In the description of this invention, it should be understood that the terms "connected," "linked," and "fixed," etc., used in this invention should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or a welded connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly defined. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] like Figures 1 to 11 As shown, a preferred embodiment of the present invention provides a balanced multistage centrifugal pump, comprising a low-pressure section 1001, a high-pressure section 2001, an inlet / outlet water section assembly 3000, a transition bend 4001, and a pump shaft 5001. The inlet / outlet water section assembly 3000 is located between the low-pressure section 1001 and the high-pressure section 2001. The pump shaft 5001 is coaxially inserted through the low-pressure section 1001, the inlet / outlet water section assembly 3000, and the high-pressure section 2001. The low-pressure section 1001 is provided with a medium inlet 1002. The low-pressure section 1001 is connected to one end of the transition bend 4001 through the inlet / outlet water section assembly 3000, and the other end of the transition bend 4001 is connected to the end of the high-pressure section 2001 away from the inlet / outlet water section 3001.

[0040] The inlet and outlet water section assembly 3000 is provided with a balance chamber 3007, a balance hole 3008, a medium outlet 3002, and a high-pressure flow-blocking inlet 7008. The medium outlet 3002 and the high-pressure flow-blocking inlet 7008 are respectively connected to the high-pressure section 2001. The high-pressure flow-blocking inlet 7008 is located between the pump shaft 5001 and the medium outlet 3002. The high-pressure flow-blocking inlet 7008 is connected to the balance chamber 3007. The balance chamber 3007 is connected to the transition bend 4001 through the balance hole 3008.

[0041] The balanced multistage centrifugal pump of the present invention includes a low-pressure section 1001, a high-pressure section 2001, an inlet / outlet water section assembly 3000, a transition bend 4001, and a pump shaft 5001. The low-pressure section 1001, the inlet / outlet water section assembly 3000, the transition bend 4001, and the high-pressure section 2001 are connected to form a complete fluid cavity. The medium enters the fluid cavity from the medium inlet 1002 of the low-pressure section 1001. The pump shaft 5001 passes through the low-pressure section 1001, the inlet / outlet water section assembly 3000, and the high-pressure section 2001, and drives the impellers in the low-pressure section 1001 and the high-pressure section 2001 to rotate, thereby pressurizing the medium in the fluid cavity. The inlet and outlet water section assembly 3000 is provided with a balance chamber 3007, a balance hole 3008, a medium outlet 3002, and a high-pressure flow-blocking inlet 7008. The medium outlet 3002 and the high-pressure flow-blocking inlet 7008 are respectively connected to the high-pressure section 2001. The high-pressure flow-blocking inlet 7008 is located between the pump shaft 5001 and the medium outlet 3002. Most of the high-pressure medium in the high-pressure section 2001 flows out from the medium outlet 3002, and the high-pressure medium enters the balance chamber 3007 through the high-pressure flow-blocking inlet 7008. The high-pressure flow-blocking inlet 7008, the balance chamber 3007, and the balance hole 3008 are connected to form a pressure regulation path. The high-pressure medium in the high-pressure section 2001 enters the balance chamber 3007 through the high-pressure flow-blocking inlet 7008. The balance chamber 3007 acts as a pressure buffer container, absorbing pressure pulsations through its volume effect. The high-pressure medium in the balance chamber 3007 diffuses and depressurizes through the balance hole 3008, and finally flows back to the high-pressure section 2001 through the transition bend 4001, reducing the effect of residual axial force on the impeller of the low-pressure section 1001. This achieves the regulation of residual axial force in the multi-stage centrifugal pump, ensuring the reliable and safe operation of the multi-stage pump.

[0042] As one embodiment, such as Figure 11As shown, a plurality of low-pressure impellers 1013 are provided in the low-pressure section 1001, and the low-pressure impellers 1013 are located in the low-pressure cavity 1011 of the low-pressure section 1001. A plurality of high-pressure impellers 2012 are provided in the high-pressure section 2001, and the high-pressure impellers 2012 are located in the high-pressure cavity 2010 of the high-pressure section 2001. The low-pressure impellers 1013 and the high-pressure impellers 2012 are coaxially rotatably connected to the pump shaft 5001. The plurality of low-pressure impellers 1013 and the plurality of high-pressure impellers 2012 are arranged at intervals along the pump shaft 5001, and the rotation directions of the low-pressure impellers 1013 and the high-pressure impellers 2012 are opposite. The low-pressure impellers 1013 and the high-pressure impellers 2012 are existing technologies, and any impeller capable of pressurizing the medium is acceptable. The medium is pressurized in stages through a low-pressure impeller 1013 and a high-pressure impeller 2012, which is a prior art technique. The low-pressure impeller 1013 and the high-pressure impeller 2012 are fixedly connected to the pump shaft 5001. A motor is connected to the pump shaft 5001, driving it to rotate. The pump shaft 5001 then drives the low-pressure impeller 1013 to rotate within the low-pressure section 1001, and consequently, the high-pressure impeller 2012 to rotate within the high-pressure section 2001.

[0043] As one embodiment, such as Figure 11 As shown, the low-pressure section 1001, the inlet and outlet water section 3001, the transition bend 4001 and the high-pressure section 2001 are connected to form a sealed medium flow channel, that is, the low-pressure cavity 1011 and the high-pressure cavity 2010 are connected to form a sealed medium flow channel.

[0044] Furthermore, such as Figures 1 to 5As shown, the inlet / outlet water section assembly 3000 includes an inlet / outlet water section 3001, a balance sleeve 7001, and a high-pressure throttling ring 8001. A balance chamber 3007, a balance hole 3008, and a medium outlet 3002 are respectively opened in the inlet / outlet water section 3001. The high-pressure throttling ring 8001 is connected to the side of the inlet / outlet water section 3001 facing the high-pressure section 2001. The balance sleeve 7001 is sleeved on the outer periphery of the pump shaft 5001. The high-pressure throttling ring 8001 is sleeved on the end of the balance sleeve 7001 facing the high-pressure section 2001. One end of the high-pressure throttling ring 8001 and the balance sleeve 7001 define a high-pressure flow-blocking inlet 7008. The other end of the high-pressure throttling ring 8001 is located in the balance chamber 3007. The high-pressure throttling ring 8001 is fixed by being connected to the inlet / outlet water section 3001. The balance sleeve 7001 is fitted around the outer circumference of the pump shaft 5001, and the pump shaft 5001 drives the balance sleeve 7001 to rotate synchronously. A high-pressure flow-blocking inlet 7008 is formed between the high-pressure throttling ring 8001 and the balance sleeve 7001, which guides part of the high-pressure medium flowing out of the high-pressure section 2001 into the balance chamber 3007. The other end of the high-pressure throttling ring 8001 is located inside the balance chamber 3007, allowing the high-pressure medium to flow smoothly into the balance chamber 3007 between the balance sleeve 7001 and the high-pressure throttling ring 8001 for pressure buffering, thus enhancing the controllability of the high-pressure medium flow path.

[0045] As one embodiment, the balance bushing 7001 has the following specific shape: Figure 6 The shape shown is a ring structure formed by 360° around the axis of the balance bushing 7001.

[0046] As one embodiment, the high-voltage throttling ring 8001 has the following specific shape: Figure 7 The shape shown is a ring structure formed by 360° around the axis of the high-pressure throttling ring 8001.

[0047] As one embodiment, such as Figure 6 As shown, the outer circumference of the balance sleeve 7001 is provided with a high-pressure flow-blocking thread 7014, the position of which corresponds to the position of the high-pressure throttling ring 8001. When the pump shaft 5001 drives the balance sleeve 7001 to rotate synchronously, the high-pressure medium flowing in from the high-pressure flow-blocking inlet 7008 is guided and promoted to move towards the balance chamber 3007 through the high-pressure flow-blocking thread 7014, effectively preventing the high-pressure medium from flowing back and enhancing the controllability of the high-pressure medium flow path.

[0048] As one embodiment, such as Figure 6 and Figure 8As shown, the end face of the balance sleeve 7001 facing the high-pressure section 2001 is provided with a first thrust groove 7002. The end of the balance sleeve 7001 facing the low-pressure section 1001 abuts against the pump shaft 5001. The opening of the first thrust groove 7002 is set towards the high-pressure section 2001. The high-pressure section 2001 is provided with a high-pressure chamber 2010 for pressurizing fluid. A high-pressure balance flow channel 7004 is provided between the inlet / outlet section 3001 and the high-pressure section 2001. The high-pressure balance flow channel 7004 is connected to the high-pressure chamber 2010, and the first thrust groove 7002 is connected to the high-pressure balance flow channel 7004. The high-pressure balance flow channel 7004 connects the high-pressure chamber 2010 and the first thrust groove 7002. The high-pressure medium in the high-pressure section 2001 enters the first thrust groove 7002 through the high-pressure balance flow channel 7004, pushing the balance sleeve 7001 to move towards the low-pressure side, so that it is positioned and engaged with the pump shaft 5001 to achieve axial positioning. The high-pressure medium automatically positions and balances the shaft sleeve 7001, eliminating the need for external adjustment mechanisms. The continuous action of the high-pressure medium dynamically balances the axial force generated by the pump shaft 5001 during operation, preventing shaft movement and improving the operational stability and pressure output efficiency of the multi-stage centrifugal pump.

[0049] Furthermore, such as Figures 1 to 2 as well as Figures 9 to 10As shown, the inlet / outlet water section assembly 3000 also includes a low-pressure throttling ring 9001. The low-pressure throttling ring 9001 is connected to the side of the inlet / outlet water section 3001 facing the low-pressure section 1001. The low-pressure throttling ring 9001 is sleeved on one end of the balance sleeve 7001 facing the low-pressure section 1001. One end of the low-pressure throttling ring 9001 is located within the balance cavity 3007 and forms a medium diffusion port 9004 between it and the high-pressure throttling ring 8001. The other end of the low-pressure throttling ring 9001 forms a low-pressure flow-blocking outlet 7017 between it and the balance sleeve 7001. The low-pressure flow-blocking outlet 7017 communicates with the transition bend 4001. The low-pressure throttling ring 9001 is fixed by being connected to the inlet / outlet water section 3001. The high-pressure medium first enters the gap between the high-pressure throttling ring 8001 and the balance sleeve 7001 from the high-pressure flow-blocking inlet 7008, and flows along the pump shaft 5001. A portion of the high-pressure medium flows into the balance chamber 3007 through the medium diffuser 9004. After pressure buffering in the balance chamber 3007, it then enters the transition bend 4001 through the balance hole 3008. When the flow rate of the high-pressure medium is large, the remaining portion continues to flow along the pump shaft 5001, enters the gap between the low-pressure throttling ring 9001 and the balance sleeve 7001, and finally flows into the transition bend 4001 through the low-pressure flow-blocking outlet 7017. By setting the medium diffuser 9004, the high-pressure medium is initially dispersed in the balance chamber 3007. When the high-pressure medium flow rate is large, the connection between the low-pressure flow-blocking outlet 7017 and the transition bend 4001 ensures that the high-pressure medium can be diverted in time, avoiding local pressure accumulation. This reduces the impact of residual axial force on the impeller of the low-pressure section 1001, improves the stability, safety and service life of the multi-stage centrifugal pump, enhances the system's ability to handle high-pressure media, and strengthens the dynamic adjustment performance of residual axial force.

[0050] As one embodiment, the specific shape of the low-pressure throttling ring 9001 is as follows: Figure 10 The shape shown is a ring structure formed by 360° around the axis of the low-pressure throttling ring 9001.

[0051] As one embodiment, such as Figure 6 As shown, the outer circumference of the balance bushing 7001 is provided with a low-pressure flow-blocking thread 7016, the position of which corresponds to the position of the low-pressure throttling ring 9001. When the pump shaft 5001 drives the balance bushing 7001 to rotate synchronously, the low-pressure flow-blocking thread 7016 guides and promotes the high-pressure medium to move towards the low-pressure flow-blocking outlet 7017, effectively preventing the high-pressure medium from flowing back and enhancing the controllability of the high-pressure medium flow path.

[0052] Furthermore, such as Figures 3 to 5As shown, the inlet / outlet section 3001 is provided with a high-pressure ring connection port 3009 and a low-pressure ring connection port 3010 at both axial ends. The high-pressure ring connection port 3009 is positioned facing the high-pressure section 2001, and a high-pressure throttling ring 8001 is connected to the high-pressure ring connection port 3009. The low-pressure ring connection port 3010 is positioned facing the low-pressure section 1001, and a low-pressure throttling ring 9001 is connected to the low-pressure ring connection port 3010. The high-pressure ring connection port 3009 provides installation space for the high-pressure throttling ring 8001. The edge of the high-pressure throttling ring 8001 is sealed to the edge of the high-pressure ring connection port 3009, thereby controlling the high-pressure medium to enter the balance chamber 3007 through the high-pressure flow-blocking inlet 7008. The low-pressure ring connection port 3010 provides installation space for the low-pressure throttling ring 9001. The edge of the low-pressure throttling ring 9001 is sealed to the edge of the low-pressure ring connection port 3010, so that the high-pressure medium in the balance chamber 3007 is discharged from the low-pressure flow-blocking outlet 7017.

[0053] Furthermore, such as Figures 3 to 5 As shown, the inlet / outlet section 3001 is equipped with a high-pressure annular cavity 3011. The high-pressure annular cavity 3011 is located on the side of the balance cavity 3007 facing the high-pressure section 2001, surrounding the outer periphery of the balance cavity 3007. The opening of the high-pressure annular cavity 3011 faces and communicates with the high-pressure section 2001. The medium outlet 3002 is located at the end of the high-pressure annular cavity 3011 away from the high-pressure section 2001. The high-pressure medium flowing out of the high-pressure section 2001 first flows into the high-pressure annular cavity 3011. Within the high-pressure annular cavity 3011, the high-pressure medium achieves preliminary pressure equalization and flow guidance, improving the uniformity and stability of the medium flow. Simultaneously, the high-pressure annular cavity 3011 surrounds the balance cavity 3007, creating a relatively stable pressure environment around the balance cavity 3007.

[0054] Furthermore, such as Figures 1 to 2 as well as Figure 8 As shown, a high-pressure balancing flow channel 7004 is formed between the inlet / outlet section 3001 and the high-pressure section 2001. One end of the high-pressure balancing flow channel 7004 is connected to both the high-pressure annular cavity 3011 and the high-pressure section 2001, and the other end is connected to the high-pressure flow-blocking inlet 7008. The high-pressure balancing flow channel 7004, located between the high-pressure section 2001 and the inlet / outlet section 3001, guides the high-pressure medium in the high-pressure section 2001 towards the high-pressure flow-blocking inlet 7008. This guides and diverts the flow of the high-pressure medium in the high-pressure section 2001. Most of the high-pressure medium enters the high-pressure annular cavity 3011 and flows out through the medium outlet 3002, while the remaining portion enters the high-pressure flow-blocking inlet 7008 through the high-pressure balancing flow channel 7004. This allows the high-pressure medium to undergo preliminary pressure distribution adjustment through the high-pressure balancing flow channel 7004 before entering the high-pressure flow-blocking inlet 7008.

[0055] Furthermore, such as Figures 3 to 5As shown, the inlet / outlet section 3001 is equipped with a low-pressure annular cavity 3012. The low-pressure annular cavity 3012 is located on the side of the balance cavity 3007 facing the low-pressure section 1001, surrounding the outer periphery of the balance cavity 3007. The opening of the low-pressure annular cavity 3012 faces the low-pressure section 1001 and communicates with both the low-pressure section 1001 and the transition bend 4001. The balance cavity 3007 communicates with the low-pressure annular cavity 3012 through a balance hole 3008. Before entering the transition bend 4001, the pressurized medium from the low-pressure section 1001 collects with the medium flowing out of the low-pressure flow-blocking outlet 7017 in the low-pressure annular cavity 3012, avoiding local disturbances or pressure fluctuations caused by the medium directly flowing into the transition bend 4001. The low-pressure annular cavity 3012, positioned around the balance cavity 3007, improves the structural compactness of the inlet / outlet section assembly 3000 and provides a more uniform pressure environment around the balance cavity 3007.

[0056] Furthermore, such as Figure 4 As shown, multiple balancing holes 3008 are provided, spaced circumferentially along the low-pressure annular cavity 3012. This allows for more uniform pressure release and flow distribution when the high-pressure medium flows from the balancing cavity 3007 into the low-pressure annular cavity 3012 through the multiple balancing holes 3008. This avoids the local pressure unevenness and sudden flow velocity changes caused by traditional single-hole or centralized arrangements, thus effectively reducing vibration and impact caused by uneven medium flow. Furthermore, the circumferentially spaced balancing holes 3008 enhance the system's adaptability to different operating conditions and improve the stability and reliability of the multistage centrifugal pump under variable load conditions.

[0057] In one embodiment, a plurality of balancing holes 3008 are arranged at equal intervals along the circumference.

[0058] Furthermore, such as Figure 9 As shown, a low-pressure balancing flow channel 7020 is formed between the inlet / outlet section 3001 and the low-pressure section 1001. One end of the low-pressure balancing flow channel 7020 is connected to both the low-pressure annular cavity 3012 and the low-pressure section 1001, while the other end is connected to the low-pressure flow-blocking outlet 7017. The pressurized medium from the low-pressure section 1001, the depressurized medium flowing out of the balancing cavity 3007 through the balancing hole 3008, and the return medium through the low-pressure flow-blocking outlet 7017 are all collected and mixed in the low-pressure annular cavity 3012, and then flow together into the transition bend 4001. This allows media of different pressure levels and flow states to achieve sufficient pressure balance and flow integration in the low-pressure annular cavity 3012. The confluence function of the low-pressure annular cavity 3012 also helps to improve the stability of the medium flow, reduce vibration and noise during pump operation, and significantly improve the overall operational stability, safety, and engineering applicability of the multistage centrifugal pump.

[0059] Furthermore, the balance orifice 3008 is provided with an inlet end 3013 and an outlet end 3014. The inlet end 3013 is connected to the balance cavity 3007, and the outlet end 3014 is connected to the low-pressure annular cavity 3012. The diameter of the inlet end 3013 is smaller than the diameter of the outlet end 3014, so that the high-pressure medium can achieve gradual pressure release and flow diffusion through the flared balance orifice 3008 during the process of flowing from the balance cavity 3007 to the low-pressure annular cavity 3012, thereby reducing the local resistance and turbulence of the fluid during the flow process.

[0060] In one embodiment, the inner walls of the balancing hole 3008 at both ends of the radial direction form an included angle α, where included angle α = 6° to 60°. Controlling included angle α within the range of 6° to 60° ensures the smooth flow of the medium and avoids flow field turbulence caused by excessive angle, thereby improving the adaptability and stability of the system under different operating conditions.

[0061] In summary, the present invention provides a balanced multistage centrifugal pump, comprising a low-pressure section 1001, a high-pressure section 2001, an inlet / outlet water section assembly 3000, a transition bend 4001, and a pump shaft 5001. The low-pressure section 1001, the inlet / outlet water section assembly 3000, the transition bend 4001, and the high-pressure section 2001 are connected to form a complete fluid cavity. The medium enters the fluid cavity from the medium inlet 1002 of the low-pressure section 1001. The pump shaft 5001 passes through the low-pressure section 1001, the inlet / outlet water section assembly 3000, and the high-pressure section 2001, respectively, and drives the impellers in the low-pressure section 1001 and the high-pressure section 2001 to rotate, thereby pressurizing the medium in the fluid cavity. The inlet and outlet water section assembly 3000 is provided with a balance chamber 3007, a balance hole 3008, a medium outlet 3002, and a high-pressure flow-blocking inlet 7008. The medium outlet 3002 and the high-pressure flow-blocking inlet 7008 are respectively connected to the high-pressure section 2001. The high-pressure flow-blocking inlet 7008 is located between the pump shaft 5001 and the medium outlet 3002. Most of the high-pressure medium in the high-pressure section 2001 flows out from the medium outlet 3002, and the high-pressure medium enters the balance chamber 3007 through the high-pressure flow-blocking inlet 7008. The high-pressure flow-blocking inlet 7008, the balance chamber 3007, and the balance hole 3008 are connected to form a pressure regulation path. The high-pressure medium in the high-pressure section 2001 enters the balance chamber 3007 through the high-pressure flow-blocking inlet 7008. The balance chamber 3007 acts as a pressure buffer container, absorbing pressure pulsations through its volume effect. The high-pressure medium in the balance chamber 3007 diffuses and depressurizes through the balance hole 3008, and finally flows back to the high-pressure section 2001 through the transition bend 4001, reducing the effect of residual axial force on the impeller of the low-pressure section 1001. This achieves the regulation of residual axial force in the multi-stage centrifugal pump, ensuring the reliable and safe operation of the multi-stage pump.

[0062] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and substitutions without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A balanced multistage centrifugal pump, characterized in that: It includes a low-pressure section, a high-pressure section, an inlet / outlet water section assembly, a transition bend, and a pump shaft. The inlet / outlet water section assembly is located between the low-pressure section and the high-pressure section. The pump shaft is coaxially inserted through the low-pressure section, the inlet / outlet water section assembly, and the high-pressure section. The low-pressure section is provided with a medium inlet. The low-pressure section is connected to one end of the transition bend through the inlet / outlet water section assembly. The other end of the transition bend is connected to the end of the high-pressure section away from the inlet / outlet water section. The inlet and outlet water section assembly is provided with a balance chamber, a balance hole, a medium outlet, and a high-pressure flow-blocking inlet. The medium outlet and the high-pressure flow-blocking inlet are respectively connected to the high-pressure section. The high-pressure flow-blocking inlet is located between the pump shaft and the medium outlet. The high-pressure flow-blocking inlet is connected to the balance chamber. The balance chamber is connected to the transition bend through the balance hole.

2. The balanced multistage centrifugal pump according to claim 1, characterized in that: The inlet / outlet water section assembly includes an inlet / outlet water section, a balance shaft sleeve, and a high-pressure throttling ring. The balance chamber, the balance hole, and the medium outlet are respectively opened in the inlet / outlet water section. The high-pressure throttling ring is connected to the side of the inlet / outlet water section facing the high-pressure section. The balance shaft sleeve is sleeved on the outer periphery of the pump shaft. The high-pressure throttling ring is sleeved on the end of the balance shaft sleeve facing the high-pressure section. One end of the high-pressure throttling ring and the balance shaft sleeve define a high-pressure flow-blocking inlet. The other end of the high-pressure throttling ring is located in the balance chamber.

3. The balanced multistage centrifugal pump according to claim 2, characterized in that: The inlet / outlet water section assembly also includes a low-pressure throttling ring. The low-pressure throttling ring is connected to the side of the inlet / outlet water section facing the low-pressure section. The low-pressure throttling ring is sleeved on the end of the balance shaft sleeve facing the low-pressure section. One end of the low-pressure throttling ring is located in the balance cavity and forms a medium diffusion port between it and the high-pressure throttling ring. The other end of the low-pressure throttling ring forms a low-pressure flow-blocking outlet between it and the balance shaft sleeve. The low-pressure flow-blocking outlet is connected to the transition bend.

4. The balanced multistage centrifugal pump according to claim 3, characterized in that: The inlet and outlet water sections are provided with high-pressure ring connection ports and low-pressure ring connection ports at both ends of the axial direction. The high-pressure ring connection port is set towards the high-pressure section, and the high-pressure throttling ring is connected to the high-pressure ring connection port. The low-pressure ring connection port is set towards the low-pressure section, and the low-pressure throttling ring is connected to the low-pressure ring connection port.

5. The balanced multistage centrifugal pump according to claim 2, characterized in that: The inlet and outlet water sections are provided with a high-pressure ring cavity. The high-pressure ring cavity is located on the side of the balance cavity facing the high-pressure section. The high-pressure ring cavity surrounds the outer periphery of the balance cavity. The opening of the high-pressure ring cavity faces the high-pressure section and communicates with the high-pressure section. The medium outlet is located at the end of the high-pressure ring cavity away from the high-pressure section.

6. The balanced multistage centrifugal pump according to claim 5, characterized in that: A high-pressure balance flow channel is defined between the inlet / outlet section and the high-pressure section. One end of the high-pressure balance flow channel is connected to the high-pressure annular cavity and the high-pressure section, and the other end is connected to the high-pressure flow-blocking inlet.

7. The balanced multistage centrifugal pump according to claim 3, characterized in that: The inlet and outlet water sections are provided with a low-pressure ring cavity. The low-pressure ring cavity is located on the side of the balance cavity facing the low-pressure section. The low-pressure ring cavity surrounds the outer periphery of the balance cavity. The opening of the low-pressure ring cavity faces the low-pressure section and is connected to the low-pressure section and the transition bend respectively. The balance cavity is connected to the low-pressure ring cavity through the balance hole.

8. The balanced multistage centrifugal pump according to claim 7, characterized in that: A low-pressure balance flow channel is defined between the inlet / outlet section and the low-pressure section. One end of the low-pressure balance flow channel is connected to the low-pressure annular cavity and the low-pressure section, and the other end is connected to the low-pressure flow-blocking outlet.

9. The balanced multistage centrifugal pump according to claim 7, characterized in that: The balancing holes are provided in multiple ways, and the multiple balancing holes are arranged at intervals along the circumference of the low-pressure annular cavity.

10. The balanced multistage centrifugal pump according to claim 7, characterized in that: The balancing hole has an inlet end and an outlet end. The inlet end is connected to the balancing cavity, and the outlet end is connected to the low-pressure annular cavity. The diameter of the inlet end is smaller than the diameter of the outlet end.

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