Water seal device of mixed-flow water turbine

Abstract

The invention discloses a mixed-flow water turbine water seal device which comprises a shell, a main shaft, a first pump wheel and a second pump wheel, the main shaft is inserted into the shell, the first pump wheel and the second pump wheel are arranged on the main shaft in a sleeving mode, the main shaft is further sleeved with a shaft sleeve, and the shaft sleeve is connected with the first pump wheel and the second pump wheel in a sleeving mode. The shaft sleeve is clamped between the first pump wheel and the second pump wheel, threads are arranged on the outer surface of the shaft sleeve, the shell comprises a shell body and a partition plate which are fixedly connected, the partition plate is arranged between the first pump wheel and the second pump wheel, one radial end of the partition plate is in clearance fit with the shaft sleeve, and the other radial end of the partition plate is in clearance fit with the shaft sleeve. The main shaft, the shaft sleeve, the first pump wheel and the second pump wheel can rotate synchronously. According to the mixed-flow water turbine water seal device, the first pump wheel can block a large amount of leakage water, the second pump wheel and the shaft sleeve are matched to drain a small amount of leakage water, and the sealing effect of a mixed-flow water turbine water seal device system is improved.

Description

Technical Field

[0001] The invention relates to the technical field of water turbines, and in particular to a water seal device for a mixed flow water turbine. Background Art

[0002] During the operation of high-head mixed-flow turbine generator sets, the main shaft water seal device plays a vital role. It is the core equipment to ensure the normal operation of the unit and prevent water leakage. If the main shaft water seal device fails, it will not only lead to waste of water resources, but also may cause equipment failure, seriously affecting the safe and stable operation of the unit.

[0003] At present, many high-head mixed-flow turbine generator sets generally use a gap-type mechanical seal structure for the main shaft water seal device. This sealing structure mainly relies on the tiny gaps between mechanical components to achieve sealing. However, in practical applications, it has many obvious defects. First, from the perspective of sealing effect, the sealing performance of the gap-type mechanical seal is poor, and it is difficult to effectively prevent the leakage of water. With the continuous increase in the operating years of the unit, the wear of the equipment is inevitable, and the sealing gap will gradually increase. Once the sealing gap increases, the leakage phenomenon will become more serious, which will not only reduce the operating efficiency of the unit, but also cause damage to the surrounding equipment. For example, continuous water leakage may cause rust and corrosion of key components of the equipment, shortening the service life of the equipment. Secondly, since the water leakage problem is difficult to be effectively controlled, it brings great hidden dangers to the safe operation of the entire turbine generator set. In some extreme cases, serious water leakage may even cause the unit to shut down, causing huge economic losses to power production.

[0004] In summary, the existing gap-type mechanical seal shaft water seal device can no longer meet the growing demand for safe and stable operation of high-head mixed-flow turbine generator sets. Therefore, developing a new type of shaft water seal device to effectively seal the shaft leakage, significantly reduce the shaft leakage, and improve the safety performance of the equipment has become a key issue that needs to be solved in this field. Summary of the invention

[0005] The main purpose of the present invention is to provide a water seal device for a mixed flow turbine to solve the problems of poor sealing effect and serious water leakage of the water seal device for a mixed flow turbine in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] According to the mixed flow turbine water seal device of the present application, it includes a casing, a main shaft, a first pump impeller and a second pump impeller, the main shaft is inserted into the casing, the first pump impeller and the second pump impeller are sleeved on the main shaft, the main shaft is also sleeved with a sleeve, the sleeve is clamped between the first pump impeller and the second pump impeller, and a reverse thread is arranged on the outer surface of the sleeve, the casing includes a fixed casing body and a partition, the partition is arranged between the first pump impeller and the second pump impeller, one radial end of the partition is clearance-matched with the sleeve, and the main shaft, the sleeve, the first pump impeller and the second pump impeller can rotate synchronously.

[0008] According to the mixed flow turbine water seal device of the present application, the partition includes a first sub-section and a second sub-section that are connected to each other, the first sub-section is parallel to the first pump wheel, the second sub-section is loosely matched with the shaft sleeve, the upper end of the second sub-section is in contact with the lower bottom surface of the second pump wheel, the lower end of the second sub-section is spaced from the upper top surface of the first pump wheel, and the first baffle and the second baffle are respectively provided at the two radial ends of the first pump wheel, the first baffle is loosely matched with the casing, the second baffle is arranged on the side of the second sub-section away from the shaft sleeve, and the second baffle is loosely matched with the second sub-section.

[0009] Optionally, a first slot is provided at the bottom of the second pump wheel, and the upper end of the second sub-section is clamped in the first slot.

[0010] Optionally, a second slot is provided on the first pump wheel, and a portion of the lower end of the second sub-section is clamped in the second slot.

[0011] Optionally, the first pump wheel is provided with a plurality of first guide grooves, one end of the first guide groove is close to the main shaft, and the other end of the first guide groove is close to the outer peripheral edge of the first pump wheel; the second pump wheel is provided with a plurality of second guide grooves, one end of the second guide groove is close to the main shaft, and the other end of the second guide groove is close to the outer peripheral edge of the second pump wheel, and the other part of the lower end of the second sub-part is arranged opposite to one of the first guide grooves.

[0012] Optionally, the first pump wheel includes a first layer plate and a second layer plate, the second layer plate is close to the second pump wheel, a plurality of first connecting parts are connected between the first layer plate and the second layer plate to define the first guide groove, and a first clamping part is provided on the upper surface of the radial end of the first layer plate close to the main shaft, the first clamping part defines the second clamping groove, and the first clamping part abuts against the sleeve.

[0013] Optionally, the Francis turbine water seal device further comprises:

[0014] A crankshaft protection cover, the main shaft is provided with a flange, the crankshaft protection cover is sleeved on the main shaft and is located on the side of the first pump wheel away from the second pump wheel, the other end of the crankshaft protection cover is abutted against the flange, and a second clamping portion is provided on the lower surface of the radial end of the first layer plate close to the main shaft, the clamping portion defines a third clamping groove, and the crankshaft protection cover is clamped in the third clamping groove.

[0015] Optionally, the mixed flow turbine water seal device also includes a top cover, which is connected to the casing body, and a shaft shoulder is also provided on the main shaft. In the direction from bottom to top, the shaft protection cover, the first pump wheel, the first sub-section, the second pump wheel, the top cover and the shaft shoulder are arranged in sequence, and a water seal box is provided on the top cover, a sealing groove is provided in the water seal box, a V-shaped sealing ring is provided in the sealing groove, and the opening of the V-shaped sealing ring is away from the shaft shoulder. The V-shaped sealing ring can float up under the action of water pressure to abut against the lower surface of the shaft shoulder.

[0016] According to the mixed flow turbine water seal device of the present application, a water guide hole is provided on the side wall of the casing body, and the water guide hole is located between the first sub-section and the second impeller.

[0017] According to the Francis turbine water seal device of the present application, the reverse thread on the shaft sleeve is configured as a reverse square thread.

[0018] The above technical solution provided by the embodiment of the invention has the following advantages compared with the prior art:

[0019] The mixed flow turbine water seal device provided by the present invention has a main shaft inserted in a shell, which serves as the core of power transmission and drives the first pump wheel, the second pump wheel and the shaft sleeve mounted thereon to rotate synchronously. The outer surface of the shaft sleeve is provided with a reverse thread. When the main shaft drives the shaft sleeve to rotate synchronously, the reverse thread can guide the water flow so that the water flow flows along the trajectory of the reverse thread. The reverse design changes the direction of the water flow. At the same time, under the push of the thread, the water flow will be pushed in the reverse direction, thereby guiding the water flow at the second pump wheel to the first pump wheel. The shell includes a fixedly connected shell body and a partition. The partition is arranged between the first pump wheel and the second pump wheel to separate the first pump wheel and the second pump wheel in space so that they each form a relatively independent working area to avoid The working water flows of the first impeller and the second impeller interfere with each other, ensuring that the first impeller and the second impeller can process the water flow respectively according to the design requirements, and each plays the function of blocking a large amount of leakage water and discharging a small amount of leakage water; at the same time, the baffle can guide the water flow to flow along a specific path, guide the water flow out of the first impeller, and form a high-pressure area at the outer edge of the first impeller and the inner wall of the casing body, thereby blocking the water flow coming up from the bottom of the first impeller, achieving effective control of the water flow, and enhancing the water sealing effect. In summary, the first impeller can block a large amount of leakage water, and the cooperation of the second impeller and the shaft sleeve can exclude a small amount of leakage water, thereby improving the coordinated working efficiency of the entire mixed flow turbine water seal device system and ensuring the stable operation of the mixed flow turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A top view of a Francis turbine water seal device provided by an embodiment of the present invention;

[0021] Figure 2 for Figure 1 Sectional view at AA in the middle;

[0022] Figure 3 for Figure 1 Cross-sectional view at DD in the middle.

[0023] Explanation of reference numerals: casing 10, casing body 11, partition 12, first sub-section 121, second sub-section 122, water guide hole 13, main shaft 20, flange 21, first pump wheel 30, second slot 31, first guide groove 32, first layer plate 33, second layer plate 34, first clamping portion 35, second clamping portion 36, first connecting portion 37, second pump wheel 40, first slot 41, second guide groove 42, third layer plate 43, fourth layer plate 44, second connecting portion 45, bushing 50, reverse thread 51, crankshaft protection cover 60, top cover 70, water seal box 80, V-shaped sealing ring 90. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] like Figure 1 and Figure 2 As shown, according to the embodiment of the present application, the mixed flow turbine water seal device includes a housing 10, a main shaft 20, a first pump impeller 30 and a second pump impeller 40, the main shaft 20 is inserted into the housing 10, the first pump impeller 30 and the second pump impeller 40 are sleeved on the main shaft 20, and a shaft sleeve 50 is also sleeved on the main shaft 20, the shaft sleeve 50 is clamped between the first pump impeller 30 and the second pump impeller 40, and a reverse thread 51 is provided on the outer surface of the shaft sleeve 50, the housing 10 includes a fixedly connected housing body 11 and a partition 12, the partition 12 is arranged between the first pump impeller 30 and the second pump impeller 40, and one radial end of the partition 12 is clearance-matched with the shaft sleeve 50, and the main shaft 20, the shaft sleeve 50, the first pump impeller 30 and the second pump impeller 40 can rotate synchronously.

[0026] In a specific embodiment, the shell body 11 is cylindrical as a whole, which can evenly withstand the pressure of the internal water flow and reduce stress concentration. The diameter of the shell body 11 is designed according to the flow rate and power requirements of the turbine. Generally, the larger the flow rate and the higher the power, the larger the diameter. The upper and lower ends of the shell body 11 can be designed to be slightly closed, which helps to guide the water flow into and out of the mixed flow turbine.

[0027] In the above-mentioned embodiment, the reverse thread 51 includes but is not limited to a square thread and a trapezoidal thread.

[0028] In the above-mentioned embodiment, the first pump wheel 30 is fastened to the main shaft 20 by fastening bolts, and the second pump wheel 40 is fastened to the main shaft 20 by fastening bolts.

[0029] In some embodiments, a first spline is provided on the main shaft 20, and a corresponding first keyway is provided at the inner hole of the first pump wheel 30. A second spline is provided on the main shaft, and a corresponding second keyway is provided at the inner hole of the second pump wheel 40. In this way, the centering performance of the synchronous rotation of the first pump wheel 30, the second pump wheel 40 and the main shaft 20 can be further improved, and vibration and noise can be reduced.

[0030] According to the mixed flow turbine water seal device of the embodiment of the present application, the main shaft 20 is inserted into the shell 10, and as the core of power transmission, it drives the first pump impeller 30, the second pump impeller 40 and the shaft sleeve 50 sleeved thereon to rotate synchronously. The outer surface of the shaft sleeve 50 is provided with a reverse thread 51. When the main shaft 20 drives the shaft sleeve 50 to rotate synchronously, the reverse thread 51 can guide the water flow so that the water flow flows along the trajectory of the reverse thread 51. The reverse design changes the direction of the water flow. At the same time, under the push of the thread, the water flow will be pushed in the reverse direction, thereby guiding the water flow at the second pump impeller 40 to the first pump impeller 30. The shell 10 includes a fixedly connected shell body 11 and a partition 12. The partition 12 is arranged between the first pump impeller 30 and the second pump impeller 40 to separate the first pump impeller 30 and the second pump impeller 40 in space so that they each form a relative For independent working areas, the working water flows of the first impeller 30 and the second impeller 40 are prevented from interfering with each other, ensuring that the first impeller 30 and the second impeller 40 can process the water flow according to the design requirements respectively, and each plays the function of blocking a large amount of leakage water and discharging a small amount of leakage water; at the same time, the partition 12 can guide the water flow to flow along a specific path, guide the water flow out of the first impeller 30, and form a high-pressure area at the outer edge of the first impeller 30 and the inner wall of the casing body 11, thereby blocking the water flow from the bottom of the first impeller 30, achieving effective control of the water flow, and enhancing the water sealing effect. In summary, the first impeller 30 can block a large amount of leakage water, and the cooperation of the second impeller 40 and the shaft sleeve 50 can exclude a small amount of leakage water, thereby improving the collaborative working efficiency of the entire mixed flow turbine water seal device system and ensuring the stable operation of the mixed flow turbine.

[0031] like Figure 2 and Figure 3 As shown, according to the mixed flow turbine water seal device of the embodiment of the present application, the partition 12 includes a first sub-portion 121 and a second sub-portion 122 that are connected to each other, the first sub-portion 121 is parallel to the first pump impeller 30, the second sub-portion 122 is clearance-matched with the shaft sleeve 50, the upper end of the second sub-portion 122 abuts against the lower bottom surface of the second pump impeller 40, and the lower end of the second sub-portion 122 is spaced from the upper top surface of the first pump impeller 30, and the first baffle and the second baffle are respectively provided at the two radial ends of the first pump impeller 30, the first baffle is clearance-matched with the casing 10, and the second baffle is arranged on the side of the second sub-portion 122 away from the shaft sleeve 50, and the second baffle is clearance-matched with the second sub-portion 122.

[0032] In detail, the first sub-section 121 can receive the leakage water leaking from the gap between the second pump impeller 40 and the shell body 11 and guide the leakage water to the reverse thread 51, so as to prevent the water flow from directly impacting the first pump impeller 30. Through the cooperation of the first sub-section 121 and the second sub-section 122, the water flow can be further guided, so that the flow of water inside the mixed flow turbine is more controllable. The clearance between the second sub-section 122 and the shaft sleeve 50 can restrain and limit the leakage water, limit the diffusion range of the water flow around the shaft sleeve 50, so that the leakage water can only flow in the gap between the shaft sleeve 50 and the second sub-section 122, reducing The disorderly leakage of water flow, the upper end of the second sub-section 122 abuts against the lower bottom surface of the second pump impeller 40, and the lower end of the second sub-section 122 is spaced from the upper top surface of the first pump impeller 30, forming a channel for limiting the leakage of water flow, and the second baffle cooperates with the second sub-section 122 to further control the direction of the leakage water flow to prevent it from leaking from the side of the second sub-section 122 away from the shaft sleeve 50, and limit the leakage water flow to the gap between the second sub-section 122 and the second baffle, so that it can flow stably to the first pump impeller 30, which is convenient for the first pump impeller 30 to perform subsequent processing on the leakage water flow, thereby improving the controllability and stability of the leakage water flow inside the turbine.

[0033] In some embodiments, the first sub-portion 121 is configured as a flat disc shape; in some embodiments, in order to better receive and guide the water flow, the surface of the first sub-portion 121 facing the second pump impeller 40 can be configured as an inclined shape, so that the leakage water leaking from the gap between the second pump impeller 40 and the shell body 11 can be more naturally gathered at the reverse thread 51.

[0034] In some embodiments, the second sub-portion 122 is configured to be cylindrical; the upper end of the second sub-portion 122 and the lower bottom surface of the second pump wheel 40 can be configured to be a wedge-shaped end, an equal wall thickness end or a stepped end, wherein the wedge-shaped end can better fit the lower bottom surface of the second pump wheel 40, reduce the possibility of water leakage, and also facilitate installation and positioning, the equal wall thickness end can simplify the structural setting, and the stepped end can provide better positioning and support.

[0035] In some embodiments, the first baffle and the second baffle may both be configured as annular flat plates.

[0036] like Figure 2 and Figure 3 As shown, in some embodiments, a first slot 41 is provided at the bottom of the second pump wheel 40 , and an upper end of the second sub-portion 122 is clamped in the first slot 41 .

[0037] In the above-mentioned embodiment, the upper end of the second sub-section 122 is inserted into the first slot 41, which can accurately locate the relative axial position of the second sub-section 122 and the second impeller 40, thereby preventing the second sub-section 122 and the second impeller 40 from being displaced relative to each other when the mixed flow turbine is running at high speed, thereby ensuring a firm connection between the two and ensuring the stability of the structure of the entire mixed flow turbine. At the same time, the snap-fitting and mutual embedding of mechanical structures are utilized to achieve a tight connection between the components, thereby ensuring that the water flow can smoothly transition from the second impeller 40 to the second sub-section 122, thereby maintaining the stability and smoothness of the water flow inside the mixed flow turbine.

[0038] In some embodiments, a second slot 31 is disposed on the first pump wheel 30 , and a portion of the lower end of the second sub-portion 122 is disposed in the second slot 31 .

[0039] In the above-mentioned embodiment, the lower end of the second sub-portion 122 is inserted into the second slot 31. When the mixed flow turbine is running, the first impeller 30 rotates at high speed. The second sub-portion 122 is inserted into the second slot 31 and rotates relative to the second slot 31, thereby stably guiding the water flow into the first impeller 30.

[0040] like Figure 2 and Figure 3 As shown, in some embodiments, a plurality of first guide grooves 32 are provided on the first pump wheel 30, one end of the first guide groove 32 is close to the main shaft 20, and the other end of the first guide groove 32 is close to the outer peripheral edge of the first pump wheel 30; a plurality of second guide grooves 42 are provided on the second pump wheel 40, one end of the second guide groove 42 is close to the main shaft 20, and the other end of the second guide groove 42 is close to the outer peripheral edge of the second pump wheel 40; and the other part of the lower end of the second sub-portion 122 is arranged opposite to a first guide groove 32.

[0041] In detail, when the mixed flow turbine is running, the main shaft 20 drives the first impeller 30 to rotate, a low pressure area is formed in the center of the first impeller 30, and the surrounding water is sucked into the first impeller 30. The water rotates in the first guide groove 32, obtains kinetic energy, and is thrown to the outer edge of the first impeller 30, where the kinetic energy is converted into pressure energy, forming a high pressure area here, which increases the resistance of the leaking water below to flow through, forming a resistance area, thereby playing a role in blocking the water flow. The main shaft 20 drives the second impeller 40 to rotate, a low pressure area is formed in the center of the second impeller 40, and the surrounding water is sucked into the second impeller 40. The water rotates in the second guide groove 42, obtains kinetic energy, and is thrown to the outer edge of the second impeller 40. Since most of the leaking water is blocked by the first impeller 30, a small amount of leakage water that comes up from the matching gap between the main shaft 20 and each rotating component is discharged through the second impeller 40, and the matching reverse thread 51 reduces the water pressure at the outer edge of the second impeller 40. The first guide groove 32 and the second guide groove 42 can guide the water flow, and the first guide groove 32 can convert the water flow with lower pressure near the main shaft 20 into the water flow with higher pressure at the outer peripheral edge of the first pump wheel 30, thereby pressurizing the water flow.

[0042] like Figure 2 and Figure 3 As shown, in some embodiments, the first pump wheel 30 includes a first layer plate 33 and a second layer plate 34, the second layer plate 34 is close to the second pump wheel 40, and a plurality of first connecting portions 37 are connected between the first layer plate 33 and the second layer plate 34 to define a first guide groove 32, and a first clamping portion 35 is provided on the upper surface of the radial end of the first layer plate 33 close to the main shaft 20, and the first clamping portion 35 defines the second clamping groove 31, and the first clamping portion 35 is stopped against the sleeve 50.

[0043] Specifically, a plurality of first connecting parts 37 connect the first layer plate 33 and the second layer plate 34, which not only defines the shape and space of the first guide groove 32, but also enhances the overall structural strength and stability of the first pump wheel 30. During high-speed rotation, it can withstand the impact force and centrifugal force of the water flow, and ensure the normal operation of the first pump wheel 30. The second clamping groove 31 defined by the first clamping part 35 is used to be clamped with the lower end of the second sub-part 122. This clamping method can accurately determine the relative position between the second sub-part 122 and the first pump wheel 30, ensuring that the second sub-part 122 can accurately guide the water flow from the second pump wheel 40 into the first guide groove 32, so that the transition of the water flow between the two pump wheels is smoother. Through the clamping, the second sub-part 122 is tightly connected with the first pump wheel 30. During the operation of the turbine, the second sub-part 122 can be effectively prevented from being displaced or shaken relative to the first pump wheel 30, ensuring the stability and reliability of the entire turbine structure.

[0044] The first clamping portion 35 abuts against the sleeve 50, and can axially position the first pump wheel 30 on the main shaft 20, and limit the axial movement of the first pump wheel 30. This ensures that the position of the first pump wheel 30 remains stable when rotating at high speed, and avoids affecting the coordination with other components and the normal flow of water due to axial displacement.

[0045] The cross-sectional shape of the first guide groove 32 can be set to a trapezoidal shape, and the trapezoidal shape makes the inlet of the first guide groove 32 wider, which is convenient for the inflow of water flow, and the outlet narrower, which is convenient for accelerating and pressurizing the water flow. The inner wall of the first guide groove 32 can be set to a smooth curved surface, and the curvature of the curved surface is optimized according to the flow characteristics of the water flow to reduce the friction resistance of the water flow and the generation of vortices.

[0046] like Figure 3 As shown, in some embodiments, the second pump wheel 40 includes a third plate 43 and a fourth plate 44, the third plate 43 is close to the first pump wheel 30, a plurality of second connecting portions 45 are connected between the third plate 43 and the fourth plate 44 to define a second guide groove 42, and a first card groove 41 is provided on the lower surface of the third plate 43.

[0047] In detail, the third layer plate 43 and the fourth layer plate 44 together constitute the boundary of the second guide groove 42, guiding the water flow to flow in the second guide groove 42, and the second connecting portion 45 connects the third layer plate 43 and the fourth layer plate 44 to form a partition wall of the second guide groove 42, guiding the water flow to flow in a specific direction, thereby improving the sealing performance and operating reliability of the mixed flow turbine.

[0048] The cross-sectional shape of the second guide groove 42 can be set to a trapezoidal shape, and the trapezoidal shape makes the inlet of the second guide groove 42 wider, which is convenient for the inflow of water flow, and the outlet narrower, which is convenient for accelerating and pressurizing the water flow. The inner wall of the second guide groove 42 can be set to a smooth curved surface, and the curvature of the curved surface is optimized according to the flow characteristics of the water flow to reduce the friction resistance of the water flow and the generation of vortices.

[0049] like Figure 2 and Figure 3 As shown, in some embodiments, the mixed flow turbine water seal device also includes a shaft protection cover 60, the main shaft 20 is provided with a flange 21, the shaft protection cover 60 is sleeved on the main shaft 20 and is located on the side of the first impeller 30 away from the second impeller 40, the other end of the shaft protection cover 60 is abutted against the flange 21, and the lower surface of the radial end of the first layer plate 33 close to the main shaft 20 is provided with a second clamping portion 36, the clamping portion defines a third clamping groove, and the shaft protection cover 60 is clamped in the third clamping groove.

[0050] In the above-mentioned embodiment, the shaft protection cover 60 is used to contact and bear force with the first pump impeller 30. The flange 21 is an important structure on the main shaft 20. It provides a reference for the installation and positioning of the shaft protection cover 60. One end of the shaft protection cover 60 abuts against the flange 21, so that the shaft protection cover 60 can be accurately installed at a specific position on the main shaft 20, ensuring the accuracy of the relative position relationship between the shaft protection cover 60 and the main shaft 20. The second clamping portion 36 of the lower surface of the radial end of the second layer 34 close to the main shaft 20 defines a third clamping groove, and the shaft protection cover 60 is clamped in the third clamping groove. This clamping method realizes the close connection between the shaft protection cover 60 and the first pump impeller 30, and further enhances the stability of the first pump impeller 30 on the main shaft 20. Through the clamping, the shaft protection cover 60 and the first pump impeller 30 can rotate with the main shaft 20 as a relatively stable whole, reducing the relative movement and vibration between the components, and improving the operating efficiency and reliability of the turbine.

[0051] In a specific embodiment, the shaft protection cover 60 is cylindrical. In order to reduce weight, the shaft protection cover 60 can be set to a hollow structure, similar to a honeycomb. In this way, the strength of the shaft protection cover 60 can be guaranteed and the weight can be effectively reduced.

[0052] like Figure 1-Figure 3 As shown, in some embodiments, the mixed flow turbine water seal device also includes a top cover 70, which is connected to the casing body 11, and a shaft shoulder is also provided on the main shaft 20. In the direction from bottom to top, the shaft protection cover 60, the first pump impeller 30, the first sub-section 121, the second pump impeller 40, the top cover 70 and the shaft shoulder are arranged in sequence, and a water seal box 80 is provided on the top cover 70, and a sealing groove is provided in the water seal box 80, and a V-shaped sealing ring 90 is provided in the sealing groove, and the opening of the V-shaped sealing ring 90 is away from the shaft shoulder, and the V-shaped sealing ring 90 can float up under the action of water pressure to abut against the lower surface of the shaft shoulder.

[0053] In detail, the top cover 70 is connected to the shell body 11 to form a relatively closed space to protect the internal components of the mixed flow turbine (such as the first pump wheel 30, the second pump wheel 40, etc.). A water seal box 80 is set on the top cover 70 to provide a platform and structural support for the installation of the water seal box 80, ensuring that the water seal device can be accurately installed in a suitable position to play its sealing role. The shoulder is a protruding structure on the main shaft 20, which plays an axial positioning role in the installation of the components of the mixed flow turbine, and can limit the axial movement of other components (such as the first pump wheel 30, the second pump wheel 40, etc.) on the main shaft 20, ensuring the accuracy of the relative position of each component on the main shaft 20, making the structure of the mixed flow turbine more stable. When the mixed flow turbine is shut down, the external pressure water pipe is connected to the water seal box 80. Under the action of the pressure water source, the V-shaped sealing ring 90 is lifted up and contacts the lower end face of the shoulder, blocking the water from the upper cavity to achieve the sealing effect.

[0054] The main shaft 20 may be configured as a smooth cylindrical shape, and the shaft shoulder may be configured as an annular protrusion integrally formed with the main shaft 20 .

[0055] like Figure 3 As shown, according to the Francis turbine water seal device of the embodiment of the present application, a water guide hole 13 is provided on the side wall of the casing body 11 , and the water guide hole 13 is located between the first sub-portion 121 and the second impeller 40 .

[0056] During the operation of the mixed flow turbine water seal device, the operation of the first pump impeller 30 and the second pump impeller 40 will cause pressure changes in different areas inside the mixed flow turbine. The water guide hole 13 located between the first sub-section 121 and the second pump impeller 40 can guide the excess pressure water in the area out, thereby balancing the pressure distribution inside the mixed flow turbine. For example, when the second pump impeller 40 is working and the pressure in the area is too high, the water guide hole 13 can discharge part of the water flow to avoid damage to the mixed flow turbine components caused by excessive pressure, thereby ensuring the stability and safety of the operation of the mixed flow turbine.

[0057] It should be noted that the water guide hole 13 can be designed to be elliptical. Compared with a circular hole, the long axis direction of the elliptical water guide hole 13 can better adapt to the flow direction of the water flow under the same cross-sectional area, thereby reducing the resistance of the water flow. At the same time, the edge of the elliptical water guide hole 13 can be designed to be rounded to avoid the formation of vortices at the hole mouth, thereby further improving the smoothness of the water flow.

[0058] In a specific embodiment, water entering the second pump impeller 40 is thrown toward the outer edge of the second pump impeller 40 when the second pump impeller 40 rotates with the main shaft 20, and is discharged through the water guide hole 13. The other way is to enter the reverse thread 51 of the sleeve 50 from the lower cavity of the second pump impeller 40, and is discharged into the first guide groove 32 of the first pump impeller 30 after being pressurized by the reverse thread 51, and then is pressurized by the first pump impeller 30 and thrown to the outer edge of the first pump impeller 30.

[0059] According to the Francis turbine water seal device of the embodiment of the present application, the reverse thread 51 on the shaft sleeve 50 is configured as a reverse square thread.

[0060] In the above-mentioned embodiment, the tooth profile of the square thread is square, the tooth profile angle is 0°, and its root thickness is larger than other tooth profiles such as triangular threads. This enables the square thread to provide greater load-bearing capacity when subjected to axial force. During the operation of the mixed flow turbine, the sleeve 50 will be subjected to various axial forces such as water flow pressure and impact force. The square thread can better withstand these forces, ensure the stability and reliability of the thread structure, and is not prone to deformation or damage.

[0061] In a specific embodiment, the first pump wheel 30 is clamped on the main shaft 20 by connecting bolts, the first pump wheel 30 and the upper end surface of the shaft protection cover 60 are in contact and spot-welded, the sleeve 50 is fixed on the main shaft 20 in a petal assembly, and the petal assembly surface is welded and fixed in sections, the second pump wheel 40 is clamped on the main shaft 20 by connecting bolts, and the top cover 70 and the casing body 11 are fixed by bolts, which are non-rotating parts.

[0062] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0063] The above is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A water seal device for a Francis turbine, characterized in that: It includes a casing, a main shaft, a first pump wheel and a second pump wheel, the main shaft is inserted into the casing, the first pump wheel and the second pump wheel are sleeved on the main shaft, the main shaft is also sleeved with a sleeve, the sleeve is clamped between the first pump wheel and the second pump wheel, and a reverse thread is arranged on the outer surface of the sleeve, the casing includes a fixedly connected casing body and a partition, the partition is arranged between the first pump wheel and the second pump wheel, one radial end of the partition is clearance-matched with the sleeve, and the main shaft, the sleeve, the first pump wheel and the second pump wheel can rotate synchronously.

2. The Francis turbine water seal device according to claim 1, characterized in that: The partition includes a first sub-section and a second sub-section that are connected to each other, the first sub-section is parallel to the first pump wheel, the second sub-section is loosely matched with the shaft sleeve, the upper end of the second sub-section is in contact with the lower bottom surface of the second pump wheel, the lower end of the second sub-section is spaced from the upper top surface of the first pump wheel, and a first baffle and a second baffle are respectively provided at two radial ends of the first pump wheel, the first baffle is loosely matched with the shell, the second baffle is arranged on the side of the second sub-section away from the shaft sleeve, and the second baffle is loosely matched with the second sub-section.

3. The Francis turbine water seal device according to claim 2, characterized in that: A first slot is provided at the bottom of the second pump wheel, and the upper end of the second sub-part is clamped in the first slot.

4. The Francis turbine water seal device according to claim 2 or 3, characterized in that: The first pump wheel is provided with a second slot, and the lower end of the second sub-part is partially clamped in the second slot.

5. The Francis turbine water seal device according to claim 4, characterized in that: The first pump wheel is provided with a plurality of first guide grooves, one end of which is close to the main shaft, and the other end of which is close to the outer peripheral edge of the first pump wheel; the second pump wheel is provided with a plurality of second guide grooves, one end of which is close to the main shaft, and the other end of which is close to the outer peripheral edge of the second pump wheel; and the other part of the lower end of the second sub-part is arranged opposite to one of the first guide grooves.

6. The Francis turbine water seal device according to claim 5, characterized in that: The first pump wheel includes a first layer plate and a second layer plate, the second layer plate is close to the second pump wheel, a plurality of first connecting parts are connected between the first layer plate and the second layer plate to define the first guide groove, and a first clamping part is provided on the upper surface of the radial end of the first layer plate close to the main shaft, the first clamping part defines the second clamping groove, and the first clamping part abuts against the sleeve.

7. The Francis turbine water seal device according to claim 6, characterized in that: Also includes: A crankshaft protection cover, the main shaft is provided with a flange, the crankshaft protection cover is sleeved on the main shaft and is located on the side of the first pump wheel away from the second pump wheel, the other end of the crankshaft protection cover is abutted against the flange, and a second clamping portion is provided on the lower surface of the radial end of the first layer plate close to the main shaft, the clamping portion defines a third clamping groove, and the crankshaft protection cover is clamped in the third clamping groove.

8. The Francis turbine water seal device according to claim 6, characterized in that: It also includes a top cover, which is connected to the shell body. A shoulder is also provided on the main shaft. From bottom to top, the shaft protection cover, the first pump wheel, the first sub-section, the second pump wheel, the top cover and the shoulder are arranged in sequence. A water seal box is provided on the top cover, a sealing groove is provided in the water seal box, a V-shaped sealing ring is provided in the sealing groove, the opening of the V-shaped sealing ring is away from the shoulder, and the V-shaped sealing ring can float up under the action of water pressure to abut against the lower surface of the shoulder.

9. The Francis turbine water seal device according to claim 2, characterized in that: A water guide hole is provided on the side wall of the housing body, and the water guide hole is located between the first sub-section and the second pump wheel.

10. The Francis turbine water seal device according to claim 1, characterized in that: The reverse thread on the sleeve is configured as a reverse square thread.

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