Runner for a hydraulic turbine and hydraulic turbine

Abstract

The embodiment of the application provides a runner for a hydraulic turbine and the hydraulic turbine, and belongs to the technical field of hydraulic engineering, and comprises an upper crown, a bottom ring and a runner lower ring arranged in the bottom ring, wherein the upper crown is located at one side of the runner lower ring; at least one group of flow resistance pump blade groups are arranged on the outer side wall of the runner lower ring; the flow resistance pump blade group comprises a plurality of flow resistance pump blades which are uniformly and spacedly arranged along the circumferential direction of the runner lower ring; the shape of the flow resistance pump blade is set as a streamline type, and the recess of the streamline type flow resistance pump blade is directed to the side where the upper crown is located. The runner for the hydraulic turbine and the hydraulic turbine provided by the embodiment of the application can improve the wear resistance of the runner and increase the service life of the runner.

Description

Technical Field

[0001] This application relates to the field of water conservancy engineering technology, and more specifically, to a runner and a water turbine for a water turbine. Background Technology

[0002] my country possesses abundant water resources, and hydropower plays a crucial strategic role in the country's energy planning. However, my country's rivers carry a high sediment load, with 115 rivers having an average annual sediment load exceeding 10 million tons, resulting in a total sediment discharge of 1.94 billion tons directly into the sea. The Yangtze River alone carries an average annual sediment load of 514 million tons, with the Three Gorges Reservoir area having an average annual sediment load of 1.17 kg / m³, reaching a maximum of 10.5 kg / m³. The Yellow River carries an even higher sediment load; statistics show that the Sanmenxia section of the Yellow River has an average annual sediment load of 37.6 kg / m³. This high sediment load in my country's rivers leads to sediment abrasion problems in 30% to 40% of hydropower stations. Furthermore, small power stations in my country lack sediment removal devices, meaning that sediment in the water generally passes through the turbines, further exacerbating the erosion of flow-through components.

[0003] Severe wear and tear damages the structural materials of hydroelectric power generation equipment, affecting the reliability and stability of operation, reducing turbine efficiency and output, shortening the service life of the runner, and leading to shorter overhaul cycles, longer construction periods, increased material consumables and spare parts, resulting in huge economic losses. Therefore, it has attracted great attention from experts at home and abroad.

[0004] Taking a conventional mixed-flow turbine with a single installed capacity of 300,000 kW as an example, a single repair of the unit costs at least 1.7 million yuan. Furthermore, the maintenance cycle is generally around 60 days, resulting in a power generation loss of 2 million yuan. Each time the unit is disassembled to replace flow-through components, the lifespan of other parts is reduced, increasing future maintenance costs. If the erosion is more severe, the unit may not be able to withstand even one flood season and will need to be shut down for maintenance, resulting in an estimated loss of 40 million kWh of electricity and an economic loss of over 10 million yuan.

[0005] Because the mechanism of erosion damage is extremely complex and involves many factors, its protection research is a multidisciplinary systematic project. It is necessary to proceed from reality, adapt to local conditions, and take comprehensive measures, such as optimizing the hydraulic and structural design of turbines, using high-quality materials and greatly improving processing precision, avoiding the operation of units in unstable areas, improving maintenance quality, and using necessary metal and non-metal protective layers, etc.

[0006] Currently, the main methods for dealing with sediment wear in hydroelectric turbines are divided into hydraulic design, operation control, and the use of wear-resistant materials. Hydraulic design is the essential core of turbine runner wear resistance. During the power plant planning and design phase, wear-resistant runner designs for multiphase flow containing sediment are carried out based on the power plant scale, turbine selection, sediment conditions, etc., to ensure the rationality of the runner blade shape with the incoming water flow, the impact angle and impact velocity of sediment particles, and to avoid rapid runner wear. Summary of the Invention

[0007] The present application provides a runner for a water turbine and a water turbine, which aims to improve the wear resistance of the runner and increase its service life.

[0008] The first aspect of this application provides a runner for a water turbine, comprising:

[0009] The upper crown, the bottom ring, and the lower ring of the rotating wheel disposed within the bottom ring, wherein the upper crown is located on one side of the lower ring of the rotating wheel;

[0010] At least one set of flow-restricting pump blades is provided on the outer side wall of the lower ring of the impeller;

[0011] The choke pump blade assembly includes a plurality of choke pump blades evenly spaced along the circumference of the lower ring of the impeller. The choke pump blades are streamlined in shape, and the notches of the streamlined choke pump blades face the side where the upper crown is located.

[0012] Optionally, the blade profile of the choke pump is set to an ellipse, and the major axis radius of the elliptical blade profile is:

[0013]

[0014]

[0015] Wherein, R is the major axis radius of the elliptical blade rib, D is the outer diameter of the lower ring of the impeller, L is the wall thickness of the lower ring of the impeller, l is the blade chord length of the choke of the flow-restricting pump blade, and β is the blade placement angle.

[0016] Optionally, the chord length of the impeller blade is:

[0017] l = (0.1 - 0.18)L

[0018] Where L is the wall thickness of the lower ring of the rotor.

[0019] Optionally, the width of the flow-restricting pump blade is:

[0020] h = (0.005 - 0.001)D

[0021] Wherein, D is the outer diameter of the lower ring of the rotor.

[0022] Optionally, the distance between the shaft mounting height of the flow-restricting pump impeller and the tailrace pipe inlet is:

[0023] c = (0.2 - 0.4)H

[0024] Wherein, H is the height of the lower ring of the rotor.

[0025] Optionally, a connecting bolt is provided at the center of the flow-restricting pump blade, and the flow-restricting pump blade is movably connected to the lower ring of the impeller through the connecting bolt.

[0026] Optionally, a connecting groove is provided on the lower ring of the rotor at the position of the connecting bolt, and hydraulic oil is provided in the connecting groove;

[0027] The end of the connecting bolt away from the flow-restricting pump blade is rotatably connected to the inner wall of the connecting groove, and a rotating push plate is provided on the end of the connecting bolt;

[0028] Therefore, the rotary push plate is configured to rotate in different directions as the pressure of the hydraulic oil in the connecting groove increases or decreases, thereby driving the connecting bolt and the pump blade to rotate.

[0029] Optionally, a flow sensor is provided on the bottom ring, which is used to monitor the leakage of the gap between the lower ring of the impeller and the bottom ring.

[0030] Optionally, the impeller of the flow-restricting pump may be made of stainless steel.

[0031] A second aspect of this application provides a water turbine, including a runner for a water turbine as provided in the first aspect of this application.

[0032] Beneficial effects:

[0033] This application provides a turbine runner and a turbine for a water turbine. By providing an upper crown, a bottom ring, and a lower ring, the outer wall of the lower ring is provided with at least one set of flow-blocking pump blades. Each flow-blocking pump blade set includes multiple flow-blocking pump blades evenly spaced along the circumference of the lower ring, and the flow-blocking pump blades are streamlined, with the notches of the streamlined flow-blocking pump blades facing the side where the upper crown is located. When the runner is in use, if water leaks into the lower ring cavity from the gap between the lower ring and the bottom ring, the flow-blocking pump blades on the side wall of the lower ring will generate a counter-current lift force opposite to the mainstream water flow in the gap. This reduces the pressure difference within the gap, decreases the amount of water flowing into the lower ring gap from the main flow channel, reduces leakage, thereby reducing the particle impact velocity within the gap, improving the runner's wear resistance, and ultimately increasing the runner's service life. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of a turbine runner according to an embodiment of this application;

[0036] Figure 2 This is a schematic diagram of the structure of a flow-restricting pump blade in the runner of a water turbine, according to an embodiment of this application.

[0037] Figure 3 This is a schematic diagram of the structure of a flow-restricting pump blade and connecting bolts in the runner of a water turbine, according to an embodiment of this application.

[0038] Explanation of reference numerals in the attached drawings: 1. Impeller blade; 2. Lower impeller ring; 3. Flow-restricting pump blade; 31. First side; 32. Second side; 33. First end; 34. Second end; 4. Top cover; 5. Upper crown; 6. Bottom ring; 7. Gap flow; 8. Tailwater pipe; 9. Gap of the lower impeller ring; 10. Reverse flow; 11. Connecting bolt; 12. Connecting groove; 13. Rotating push plate; 14. Flow sensor. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] Reference Figure 1 As shown in the figure, this application discloses a turbine runner, which includes a top cover 4, an upper crown 5, a lower runner ring 2, multiple runner blades 1, a bottom ring 6, and a tailrace pipe 8.

[0041] Specifically, the top cover 4 is positioned above the upper crown 5, and multiple impeller blades 5 are positioned between the upper crown 4 and the lower impeller ring 2. These blades are evenly spaced along the circumference of the upper crown 4 and the lower impeller ring 2, and are installed using a pump-type mounting method. The bottom ring 6 is located outside the lower impeller ring 2 and completely surrounds it. A lower impeller ring gap 9 is formed between the inner wall of the bottom ring 6 and the outer wall of the lower impeller ring 2. When water flows through the impeller, water enters the lower impeller ring gap 9 between the bottom ring 6 and the lower impeller ring 2, forming a gap flow 7. When particles in the water flow enter the lower impeller ring gap 9, the high impact velocity of the particles causes wear on the lower impeller ring 2 and the bottom ring 6.

[0042] In order to improve the wear resistance of the impeller, in this embodiment of the application, at least one set of flow-blocking pump blades is provided on the outer side wall of the lower ring 2 of the impeller.

[0043] Specifically, refer to Figure 1 and Figure 2 As shown, the choke pump blade assembly includes multiple choke pump blades 3 evenly spaced along the circumference of the lower ring 2 of the impeller, and the choke pump blades 3 are streamlined in shape. The multiple choke pump blades 3 are approximately at the same height on the outer wall of the lower ring 2 of the impeller, and the installation angle of each choke pump blade 3 is approximately the same. The streamlined choke pump blade 3 includes a first side 31 and a second side 32 facing each other. The first side 31 is an inwardly concave arc, forming a notch in the choke pump blade 3, while the opposite second side 32 is an outwardly convex arc. In this embodiment, the notch of the streamlined choke pump blade 3 faces the side where the upper crown 5 is located.

[0044] The choke pump blade 3 includes a first end 33 and a second end 34, which are located at the two ends of the first side 31, respectively. The width of the choke pump blade 3 at the first end 33 is greater than the width of the choke pump blade 3 at the second end 34, and the width of the choke pump blade 3 gradually decreases from the first end 33 to the second end 34.

[0045] Meanwhile, in this embodiment, the front half of the choke pump blade 3 is approximately parallel to the circular edge of the lower ring 2 of the impeller, while the rear half of the choke pump blade 3 is inclined relative to the circular edge of the lower ring 2 of the impeller.

[0046] In this way, when the impeller is in use, the entire impeller will rotate. At this time, some water will leak from the impeller lower ring gap 9 between the impeller lower ring 2 and the bottom ring 6. This gap flow 7 flows towards the lower ring cavity (located on the side of the impeller lower ring 2 away from the upper crown 4). When the flow-blocking pump blade 3 on the outer wall of the impeller lower ring 2 rotates with the impeller lower ring 2, it will generate a countercurrent lift force opposite to the direction of the gap water flow. This will form a countercurrent 10 in the impeller lower ring gap 9, which is opposite to the flow direction of the gap flow 7. The countercurrent 10 will reduce the pressure difference in the impeller lower ring gap 9. It can be understood that the flow-blocking pump blade 3 will make the gap flow 7 flow towards the direction of the upper crown. This can reduce the water flow rate entering the impeller lower ring 2 gap from the main impeller channel, reduce the leakage, thereby reducing the particle impact velocity in the impeller lower ring gap 9, improving the impeller's wear resistance, and thus increasing the impeller's service life.

[0047] Meanwhile, the embodiments of this application provide more convenient maintenance of the impeller. After the unit has been running for several flood seasons, only the obstruction pump blade 3 needs to be replaced or repaired during the maintenance cycle.

[0048] Furthermore, in this embodiment, the choke pump blade 3 is made of high-strength stainless steel, and the surface of the choke pump blade 3 is coated with an anti-wear coating to increase the service life of the choke pump blade 3.

[0049] Furthermore, in this embodiment, the blade profile of the choke pump blade 3 is set to an ellipse, and the major axis radius of the elliptical blade profile can be calculated using the following formula:

[0050]

[0051]

[0052] Wherein, R is the major axis radius of the elliptical blade rib, D is the outer diameter of the lower ring 2 of the impeller, L is the wall thickness of the lower ring 2 of the impeller, l is the blade chord length of the flow-blocking pump blade 3, and β is the blade placement angle.

[0053] In the above formula, the chord length of the impeller blade 3 can be determined based on the wall thickness of the lower ring of the impeller.

[0054] Specifically, the formula for calculating the chord length of the blade of the flow-restricting pump 3 is as follows:

[0055] l = (0.1 - 0.18)L

[0056] In addition, the width of the impeller blade 3 can be determined based on the outer diameter of the lower ring 2 of the impeller. The specific calculation formula is as follows:

[0057] h = (0.005 - 0.001)D

[0058] The distance between the shaft center mounting height of the flow-restricting pump impeller 3 and the tailrace pipe inlet is:

[0059] c = (0.2 - 0.4)H

[0060] Wherein, H is the height of the lower ring 2 of the rotor.

[0061] The various values ​​of the choke pump blade 3 can be determined using the above calculation formulas. Of course, those skilled in the art can design the choke pump blade 3 according to actual needs.

[0062] In one alternative implementation, refer to Figure 1 As shown in the embodiment of this application, a turbine runner is also provided. In this runner, a connecting bolt 11 is provided at the central position of the flow-blocking pump blade 3, and the flow-blocking pump blade 3 is movably connected to the lower ring 2 of the runner through the connecting bolt 11.

[0063] Specifically, in this embodiment, the choke pump blade 3 is connected to the lower ring 2 of the impeller via connecting bolt 11, and the choke pump blade 3 can rotate at a certain angle relative to the lower ring 2 of the impeller, thereby changing the operating angle of the choke pump blade 3.

[0064] Furthermore, referring to Figure 3 As shown, a connecting groove 12 is provided on the lower ring 2 of the rotor at the position of the connecting bolt 11, and hydraulic oil is provided in the connecting groove 12. At the same time, the end of the connecting bolt 11 away from the flow-blocking pump blade 3 is rotatably connected to the inner wall of the connecting groove 11, and a rotating push plate 13 is provided on the end of the connecting bolt.

[0065] Specifically, the rotary push plate 13 includes at least two plates, which are evenly spaced along the circumference of the connecting bolt 11. The rotary push plate 13 is configured to rotate in different directions as the pressure of the hydraulic oil in the connecting groove 12 increases or decreases. For example, when the hydraulic oil pressure increases, the rotary push plate 13 rotates clockwise; when the hydraulic oil pressure decreases, the rotary push plate 13 rotates counterclockwise.

[0066] In practical applications, two sealed cavities can be formed at the positions of the two plates, and hydraulic oil can be placed in these two cavities. By changing the pressure of the hydraulic oil in the two cavities (by injecting or extracting hydraulic oil into the cavities, the pressure of the hydraulic oil can be changed), the movement of the plates can be driven, thereby achieving the rotation of the rotating push plate 13.

[0067] In this way, the rotating push plate 13 can drive the connecting bolt 11 to rotate, so that the connecting bolt 11 can drive the choke pump blade 3 to rotate, thereby realizing the adjustment of the running angle of the choke pump blade 3.

[0068] Furthermore, a flow sensor 14 is provided on the bottom ring 6. The flow sensor 14 is used to monitor the leakage amount 14 between the lower ring 2 of the impeller and the bottom ring 6.

[0069] It is understandable that a control module is installed in the turbine. The control module is connected to the flow sensor 14. The flow sensor 14 can transmit the monitored gap leakage data to the control module. At the same time, the control module is also connected to the hydraulic pump. The control module can send a control signal to the hydraulic pump according to the balance between the lift coefficient of the runner and the gap leakage, so that the hydraulic pump can increase or decrease the hydraulic oil pressure in the connecting groove according to the control signal, thereby adjusting the running angle of the flow-restricting pump blade 3.

[0070] The formula for calculating the lift coefficient of the runner is as follows:

[0071]

[0072] In the formula, P v For lift, C v ρ is the lift coefficient, ρ is the density, and v is the lift coefficient. j Let F be the rotational speed and F be the water flow resistance.

[0073] The impeller provided in this application embodiment uses a drive component to adjust the running angle of the flow-restricting pump blade 3, thereby achieving real-time control of the leakage in the gap between the lower ring 2 and the bottom ring 6 of the impeller, thereby reducing the particle impact velocity in the gap and achieving the anti-wear effect of the impeller.

[0074] In one alternative implementation, the lower ring 2 of the impeller may be provided with more sets of choke pump blades.

[0075] Specifically, the number and combination of the choke pump blade assemblies can be determined based on the turbine's installed capacity. For small and medium-sized turbines with a single unit installed capacity of 300,000 kW or less, only one set of choke pump blade assemblies can be installed on the lower ring 2 of the runner, i.e., n = N; for large turbines with a single unit installed capacity greater than 300,000 kW, two sets of choke pump blade assemblies can be installed on the lower ring 2 of the runner, i.e., n = 2N.

[0076] It should be noted that n is the number of impeller pump blades, and N is the number of turbine runner blades.

[0077] Based on the same inventive concept, this application also discloses a water turbine, including any of the runners for water turbines described above in the embodiments of this application.

[0078] The turbine provided in this application embodiment, when water leaks into the lower ring cavity of the runner from the gap between the lower ring 2 and the bottom ring 6, generates a counter-current lift force opposite to the mainstream flow in the gap. This reduces the pressure difference within the gap, decreases the amount of water flowing into the gap of the lower ring 2 from the main flow channel, and reduces leakage. Furthermore, the turbine provided in this application embodiment has a simple structure, reliable technology, is easy to implement, has broad application prospects, and offers significant economic benefits.

[0079] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0080] It should also be noted that, in this document, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not 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 application. Furthermore, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations, nor should they be construed as indicating or implying relative importance. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements, but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. In the absence of further restrictions, an element defined by the phrase "includes a..." does not preclude the presence of other identical elements in the process, method, article, or terminal device that includes the element.

[0081] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand this application, and the content of this specification should not be construed as a limitation of this application. Furthermore, for those skilled in the art, there will be different forms of changes in the specific implementation methods and application scope based on this application. It is neither necessary nor possible to exhaustively list all implementation methods here, and obvious changes or modifications derived therefrom are still within the protection scope of this application.

Claims

1. A runner for a water turbine, characterized in that, include: The upper crown, the bottom ring, and the lower ring of the rotating wheel disposed within the bottom ring, wherein the upper crown is located on one side of the lower ring of the rotating wheel; At least one set of flow-restricting pump blades is provided on the outer side wall of the lower ring of the impeller; The choke pump blade assembly includes a plurality of choke pump blades evenly spaced along the circumferential direction of the lower ring of the impeller. The shape of the choke pump blades is streamlined, and the notches of the streamlined choke pump blades face the side where the upper crown is located. The blade profile of the choke pump is set to an ellipse, and the major axis radius of the elliptical blade profile is: in, R The radius of the major axis of the elliptical leaf-shaped skeletal line is... D Let L be the outer diameter of the lower ring of the rotor, and L be the wall thickness of the lower ring of the rotor. l β is the chord length of the blade of the flow-restricting pump, and β is the blade placement angle.

2. The runner for a water turbine according to claim 1, characterized in that: The chord length of the impeller blade of the flow-restricting pump is: l =（0.1-0.18） L Where L is the wall thickness of the lower ring of the rotor.

3. The runner for a water turbine according to claim 1, characterized in that: The width of the flow-restricting pump blades is: h =（0.005-0.001） D in, D The outer diameter of the lower ring of the rotor is given.

4. The runner for a water turbine according to claim 1, characterized in that: The distance between the shaft center mounting height of the flow-restricting pump impeller and the tailrace pipe inlet is: c =（0.2-0.4） H Wherein, H is the height of the lower ring of the rotor.

5. The runner for a water turbine according to claim 1, characterized in that: A connecting bolt is provided at the center of the flow-restricting pump blade, and the flow-restricting pump blade is movably connected to the lower ring of the impeller through the connecting bolt.

6. The runner for a water turbine according to claim 5, characterized in that: A connecting groove is provided on the lower ring of the rotor at the position of the connecting bolt, and hydraulic oil is provided in the connecting groove; The end of the connecting bolt away from the flow-restricting pump blade is rotatably connected to the inner wall of the connecting groove, and a rotating push plate is provided on the end of the connecting bolt; Therefore, the rotary push plate is configured to rotate in different directions as the pressure of the hydraulic oil in the connecting groove increases or decreases, thereby driving the connecting bolt and the flow-restricting pump blade to rotate.

7. The runner for a water turbine according to claim 1, characterized in that: A flow sensor is installed on the bottom ring, which is used to monitor the leakage of the gap between the lower ring of the impeller and the bottom ring.

8. The runner for a water turbine according to claim 1, characterized in that: The impeller of the flow-restricting pump is made of stainless steel.

9. A water turbine, characterized in that, Includes the impeller as described in any one of claims 1-8.

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