A new horizontal multi-stage centrifugal pump without balancing disc

Abstract

This invention proposes a novel horizontal multistage centrifugal pump that eliminates the need for a balance disc. The pump comprises a pump shaft, suction section, intermediate section, and discharge section. Its main innovation lies in eliminating the traditional balance disc structure, replacing it with a hydraulic balancing system consisting of balance holes on the impeller rear cover plate and a fixed rear sealing groove. This rear sealing groove forms a U-shaped gap seal with the impeller, balancing most of the axial force. The residual axial force is borne by a pair of angular contact ball bearings installed at the non-drive end of the pump shaft, thus completely eliminating rotor axial movement. Furthermore, a balance water pipe reduces the pressure in the mechanical seal cavity, and a water seal pipe is used for cooling and lubrication. This invention fundamentally solves the problems of easy wear and poor reliability of the balance disc in traditional multistage pumps, offering advantages such as reliable operation, long maintenance cycles, high efficiency, and suitability for frequent start-up conditions.

Description

Technical Field

[0001] This utility model relates to the field of centrifugal pump mechanical technology, and in particular to a novel horizontal multistage centrifugal pump that does not require a balancing disc. Background Technology

[0002] Traditional D-type horizontal multistage centrifugal pumps commonly employ a balance disc structure to balance the axial force generated during operation. While theoretically feasible, this structure has a fatal flaw in practical applications: each time the pump starts, before the balancing force is established, the balance disc will experience frictional wear against the balance ring under the axial force. The balance disc is an essential wear component; if it fails due to wear or jamming, it will cause axial movement of the entire rotor assembly, leading to rapid damage to critical components such as mechanical seals and bearings, resulting in equipment accidents, high maintenance costs, and poor reliability.

[0003] Furthermore, because the balance disc structure requires a certain amount of axial movement in the rotor, traditional D-type pumps cannot use bearings such as angular contact ball bearings that can rigidly withstand axial forces, further limiting their reliability. Therefore, there is an urgent need in the field for a multistage centrifugal pump structure that does not rely on a balance disc and can fundamentally solve the problems of axial movement and starting wear. Utility Model Content

[0004] The purpose of this invention is to overcome the aforementioned shortcomings of the prior art and provide a novel horizontal multistage centrifugal pump that does not require a balancing disc. Through structural innovation, this pump eliminates axial movement of the rotor, solves the problems of easy wear and poor reliability associated with traditional balancing discs, and significantly extends the maintenance cycle and service life.

[0005] To achieve the above objectives, this utility model proposes a novel horizontal multistage centrifugal pump that does not require a balancing disc, comprising a pump shaft, impeller, guide vanes, balancing holes, and a rear sealing groove. The pump body includes, along the pump shaft axis, a suction section, several intermediate sections, and a discharge section. Impellers and guide vanes are provided in the intermediate sections. Multiple impellers are spaced apart on the pump shaft, and the guide vanes are disposed between adjacent impellers. The pump shaft is equipped with a cylindrical roller bearing at the drive end and a pair of angular contact ball bearings at the non-drive end. The balance hole is opened in the impeller rear cover plate and connects the high-pressure chamber on the rear side of the impeller and the suction section; the balance hole and the rear sealing groove cooperate to balance the axial force generated during pump operation; The rear sealing groove is provided on the guide vane, and together with the outer circle of the impeller hub and the outer circle of the rear cover plate, they form an axially extending annular gap sealing pair. One end of the balancing water pipe is connected to the suction section, and the other end is connected to the discharge section, which is used to balance the pressure of the machine sealing chamber; One end of the water seal pipe is in communication with the pressure chamber of the first-stage middle section, and the other end is respectively in communication with the seal chambers located on the suction section side and the discharge section side.

[0006] Further, the gap between the rear seal groove and the outer circle of the hub of the impeller rear cover plate, and the gap between the rear seal groove and the outer circle of the impeller rear cover plate together form a seal flow passage with a cross section in the shape of a Chinese character "hui". The seal gap length of the loop-shaped seal structure is jointly adjusted by the fit gap between the impeller outer circle and the seal ring and the fit gap between the impeller inner circle and the seal ring, so as to meet the requirement of axial force balance on the gap length.

[0007] Further, the aperture and the number of the balance holes are determined through computational iterative optimization, so as to ensure that most of the axial force can be counteracted when the balance holes cooperate with the seal ring.

[0008] Further, the angular contact roller bearings are angular contact ball bearings arranged in pairs, and the paired angular contact ball bearings are mounted face-to-face or back-to-back, so as to realize the balance of bidirectional residual axial force.

[0009] Further, the seal chamber is a chamber where the mechanical seal is located, and the pressurized water delivered by the water seal pipe directly acts on the surface of the mechanical seal, so as to improve the sealing performance and heat dissipation effect of the mechanical seal.

[0010] Further, the balance water pipe is communicated to the seal chamber where the mechanical seal is located, so as to reduce the pressure of the seal chamber.

[0011] Compared with the prior art, the present utility model has the following advantages: The centrifugal pump of the present utility model eliminates the easily worn balance disc structure, and adopts a mode combining hydraulic balance of "balance hole + rear seal groove" and mechanical force bearing of "angular contact ball bearing", which fundamentally eliminates starting wear and axial play, greatly improves operation reliability, and prolongs the service lives of the mechanical seal and the bearing.

[0012] The establishment of the balance force of the centrifugal pump of the present utility model does not depend on the relative movement of the friction pair, so it is not afraid of frequent start-stop working conditions and has a wider application range. As the service life of key components is prolonged and the accident rate is reduced, the maintenance frequency and maintenance cost are significantly reduced.

[0013] The rotor of the centrifugal pump of the present utility model has no axial play, which ensures that the impeller and the guide vane are always in the best centering state, reduces the internal leakage loss, and improves the operation efficiency of the pump. Brief Description of the Drawings

[0014] Figure 1 is a schematic plan structural view of the novel horizontal multi-stage centrifugal pump of the present utility model.

[0015] Figure 2This is a schematic diagram of the overall three-dimensional structure of the novel horizontal multistage centrifugal pump of this utility model.

[0016] Figure 3 This is a partially enlarged schematic diagram of the "U-shaped" sealing structure formed by the impeller, balance hole, and rear sealing groove in this utility model.

[0017] Figure 4 This is a schematic diagram of the non-drive end bearing configuration in this utility model.

[0018] Figure 5 This is a schematic diagram of the connection structure between the balance water pipe and the water seal pipe in this utility model.

[0019] 1-Pump shaft; 2-Suction section; 3-Intermediate section; 4-Discharge section; 5-Impeller; 51-Impeller rear cover plate; 52-Balance hole; 53-Outer circle of rear cover plate hub; 54-Outer circle of rear cover plate; 6-Guide vane; 7-Angular contact ball bearing; 8-Cylindrical roller bearing; 9-Rear seal groove; 91-U-shaped seal flow channel; 10-Balance water pipe; 11-Water seal pipe; 12-Mechanical seal; 13-Sealing ring. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be further described below.

[0021] This embodiment proposes a novel horizontal multistage centrifugal pump that does not require a balancing disc, such as... Figure 1-5 As shown, it includes a pump body, a pump shaft 1, an impeller 5, a guide vane 6, a balance hole 52, and a rear sealing groove (guide vane groove) 9; The pump body, along the pump shaft 1, sequentially includes an inlet section 2, several intermediate sections 3, and an outlet section 4. The pump shaft 1 horizontally penetrates the entire pump body. Multiple impellers 5 are installed within the intermediate sections of the pump body, spaced apart on the pump shaft 1. Each impeller 5 is followed by a guide vane 6 fixed within the intermediate section 3 of the pump body. These guide vanes 6 are positioned between adjacent impellers 5 to guide the fluid and convert kinetic energy. A sealing ring 13 is installed on the pump body in the intermediate section 3. This sealing ring 13 forms a clearance fit with the outer circumference of the impeller 5 inlet to reduce backflow of high-pressure fluid into the low-pressure area of ​​the impeller inlet, thus maintaining pump operating efficiency.

[0022] Compared to traditional horizontal centrifugal pumps, the core improvements of the novel centrifugal pump proposed in this embodiment lie in the axial force balancing system and the sealing cooling system.

[0023] Axial force balancing system: such as Figure 2 and Figure 3As shown, multiple balancing holes 52 are evenly distributed on the rear cover plate 51 of each impeller 5. The diameter and number of balancing holes 52 are iteratively optimized through fluid dynamics calculations to ensure that they can offset most of the axial force when mated with the rear sealing groove 9. The balancing holes 52 connect the high-pressure chamber on the rear side of the impeller with the low-pressure area of ​​the suction section 2, reducing the axial force acting on the impeller rear cover plate through the pressure difference. At the same time, a groove space (i.e., the rear sealing groove 9) is machined on the guide vane 6 to match the impeller rear cover plate hub. This groove space (rear sealing groove 9) forms a very small radial gap between the outer circle 53 of the rotating impeller rear cover plate hub and the outer circle 54 of the rear cover plate. This gap extends axially, together forming a U-shaped sealing flow channel 91 with an approximately "U"-shaped cross section. This flow channel cross section further balances the axial force and reduces internal leakage by increasing the throttling length and sealing effect. The U-shaped sealing flow channel 91 not only increases the throttling effect but also increases the flow channel length, saving axial space. During operation, the liquid in the high-pressure chamber on the back of the impeller 5 leaks through the throttling seal channel 91, causing a decrease in liquid pressure at the lower part of the impeller rear cover plate 51, thereby reducing the axial force acting on the rear cover plate. This structure ensures the balance of the impeller axial force and reduces leakage in the clearance, improving pump efficiency. The remaining residual axial force is then distributed by a pair of angular contact ball bearings 7 (such as...) installed at the non-drive end of the pump shaft. Figure 4 (As shown) bears the load. The drive end uses cylindrical roller bearings 8 to mainly bear the radial force. This bearing combination ensures that the rotor has no axial movement during operation, realizes rigid constraint of bidirectional axial force, and completely eliminates rotor axial movement.

[0024] The axial force balancing system of this pump is achieved by a hydraulic balancing structure consisting of a balancing hole 52 and a rear sealing groove 9, and a mechanical load-bearing structure consisting of an angular contact ball bearing 7.

[0025] Sealing and Cooling System: To ensure the reliable operation of the mechanical seal 12, this pump is equipped with a balance water pipe 10 and a water seal pipe 11. For example... Figure 5 As shown, one end of the balancing water pipe 10 is connected to the suction section 2, and the other end is connected to the discharge section 4, used to balance the pressure in the mechanical seal chamber; one end of the water seal pipe 11 is connected to the pressure chamber of the first stage intermediate section, and the other end is connected to the sealing chambers located on the suction and discharge sides respectively. During operation, the balancing water pipe 10 leads the high-pressure liquid from the discharge section 4 to the low-pressure chamber of the suction section 2 (or directly to the sealing chamber where the mechanical seal 12 is located), which effectively reduces the pressure in the chamber where the mechanical seal is located, creating a good low-pressure working environment for the mechanical seal. The water seal pipe 11 draws water from the high-pressure rear chamber of the first stage intermediate section and delivers it to the sealing chambers at both ends of the pump body, playing a role in cooling, lubricating, and water sealing the mechanical seal.

[0026] The working process is as follows: When the pump starts, the impeller 5 rotates to generate high-pressure fluid. The high-pressure fluid is depressurized through the balance hole 52 to the suction section 2. At the same time, the "U"-shaped flow channel 91 formed by the rear sealing groove 9 throttles and reduces pressure, together balancing most of the axial force. The residual axial force is borne by the angular contact ball bearing 7, ensuring that the rotor does not move axially. The balance water pipe 10 and the water seal pipe 11 work synchronously to maintain the low pressure and cooling conditions of the mechanical seal cavity.

[0027] The above are merely preferred embodiments of this utility model and do not constitute any limitation on this utility model. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and contents disclosed in this utility model without departing from the scope of the technical solutions of this utility model shall still fall within the protection scope of this utility model.

Claims

1. A novel horizontal multistage centrifugal pump that does not require a balancing disc, characterized in that, comprising a pump body, a pump shaft, impellers, guide vanes, balance holes and a rear seal groove; The pump body sequentially comprises a suction section, a plurality of middle sections and a discharge section along the axial direction of the pump shaft, and the impellers and the guide vanes are arranged in the middle sections; the plurality of impellers are sleeved on the pump shaft at intervals, and the guide vanes are arranged between adjacent impellers; A cylindrical roller bearing is arranged at the driving end of the pump shaft, and a pair of angular contact ball bearings are arranged at the non-driving end; The balance holes are formed in the rear cover plate of the impeller and communicate the high-pressure cavity at the rear side of the impeller with the suction section; the balance holes cooperate with the rear seal groove to balance the axial force generated during the operation of the pump; The rear seal groove is arranged on the guide vane, and together with the outer circle of the rear cover plate hub of the impeller and the outer circle of the rear cover plate, forms an axially extending annular gap sealing pair; One end of the balance water pipe is communicated with the suction section, and the other end is communicated with the discharge section, for balancing the pressure of the mechanical seal cavity; One end of the water seal pipe is communicated with the pressure cavity of the first-stage middle section, and the other end is respectively communicated with the seal cavities located on the suction section side and the discharge section side.

2. The novel horizontal multistage centrifugal pump without a balancing disc according to claim 1, characterized in that, The gap between the rear seal groove and the outer circle of the rear cover plate hub of the impeller, as well as the gap between the rear seal groove and the outer circle of the rear cover plate of the impeller, together form a sealing flow passage with a cross section in the shape of a Chinese character "回"; The sealing gap length of the loop-shaped sealing structure is jointly adjusted by the matching gap between the outer circle of the impeller and the seal ring and the matching gap between the inner circle of the impeller and the seal ring, so as to meet the requirement of axial force balance on the gap length.

3. The novel horizontal multistage centrifugal pump without a balancing disc according to claim 1, characterized in that, The aperture and number of the balance holes are determined by computational iterative optimization, so as to ensure that most of the axial force can be counteracted when the balance holes cooperate with the seal ring.

4. The novel horizontal multistage centrifugal pump without a balancing disc according to claim 1, characterized in that, The angular contact roller bearings are angular contact ball bearings arranged in pairs, and the paired angular contact ball bearings are installed face-to-face or back-to-back, so as to realize the balance of bidirectional residual axial force.

5. The novel horizontal multistage centrifugal pump without a balancing disc according to claim 1, characterized in that, The seal cavity is a chamber where the mechanical seal is located, and the pressurized water conveyed by the water seal pipe directly acts on the surface of the mechanical seal, so as to improve the sealing performance and heat dissipation effect of the mechanical seal.

6. The novel horizontal multistage centrifugal pump without a balancing disc according to claim 5, characterized in that, The balance water pipe is communicated to the seal cavity where the mechanical seal is located, so as to reduce the pressure of the corresponding seal cavity.

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