Water turbine structure of ultra-high water head hydropower station and determination method

Abstract

The invention discloses an ultra-high water head hydropower station water turbine structure and a determination method. The ultra-high water head hydropower station water turbine structure comprises a water distribution ring pipe, nozzles, a rotating wheel and water buckets. The nozzle is connected with the water distribution ring pipe, the section of the joint of the nozzle and the water distribution ring pipe is elliptical, and the section of the tail end of the nozzle is circular; the water buckets are circumferentially and uniformly distributed around the rotating wheel; center lines of the nozzles are positioned on the same horizontal plane and tangent to pitch circles of the runners; the water distribution ring pipe and the rotating wheel are installed on the same horizontal line, and the vertical center line of the rotating wheel coincides with the vertical center line of the water distribution ring pipe. The specific speed of a single nozzle, the number of nozzles, the specific speed of a water turbine, the rated speed of the water turbine, the diameter of a runner of the water turbine, the specific speed of the water turbine, the specific speed of the single nozzle, the jet diameter of the nozzles, the diameter of the nozzles, the optimal diameter ratio, the jet velocity, the linear speed of bucket blades, the runaway speed and the number of buckets are calculated in sequence. And the operation efficiency and the generating capacity are improved, and economic benefits of the hydropower station are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of water conservancy and hydropower engineering, and particularly to a structure and determination method of a water turbine for an ultra-high head hydropower station. Background Art

[0002] The head generally refers to the difference between the upstream water level and the downstream water level of a hydropower station. A high-head hydropower station generally refers to a hydropower station with a head greater than 200 m. When the head is greater than 250 m, it is an ultra-high head hydropower station. For an ultra-high head hydropower station with a head greater than 600 m, only an impulse water turbine can be selected.

[0003] An impulse water turbine is a hydraulic machine that uses high-speed water flow to impact the runner to do work, and uses the high-speed jet energy of the water flow to drive the runner to rotate and do work. The manufacturing difficulty of the water turbine is closely related to the operating head and the runner diameter. Under the same rated power of a single unit, the higher the operating head and the larger the sediment concentration, the larger the runner diameter, and the greater the manufacturing difficulty of the water turbine. Therefore, scientific and reasonable optimization is required. Therefore, it is necessary to design a structure and determination method of a water turbine for an ultra-high head hydropower station to solve the above problems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a structure and determination method of a water turbine for an ultra-high head hydropower station, which can significantly reduce the construction cost while improving the operation efficiency and power generation, so as to ensure the economic benefits of the hydropower station.

[0005] To achieve the above technical effects, the technical solution adopted by the present invention is: A structure of a water turbine for an ultra-high head hydropower station includes a water distribution ring pipe, a nozzle, a runner, and a bucket; the nozzle is connected to the water distribution ring pipe, the cross-section of the water distribution ring pipe is circular, and the nozzles are evenly distributed along the circumference inside the water distribution ring pipe; the cross-section of the connection between the nozzle and the water distribution ring pipe is elliptical, and the cross-section of the end of the nozzle is circular; the bucket is connected to the runner, the runner is a cylinder, and the buckets are evenly distributed along the circumference of the runner; the center lines of the nozzles are located on the same horizontal plane and tangent to the pitch circle of the runner; the water distribution ring pipe and the runner are installed on the same horizontal line, and the vertical center line of the runner coincides with the vertical center line of the water distribution ring pipe.

[0006] Preferably, a determination method for the structure of a water turbine for an ultra-high head hydropower station includes determining the specific speed n sl range of: According to the parameter levels of domestic and foreign impulse water turbines and the empirical values of the cavitation-free curve, determine the range of the specific speed n sl of the water turbine for an ultra-high head hydropower station with a head of 800 - 1000 m, in units of m·kW.

[0007] Preferably, it includes determining the number of nozzles Z0: Select the number of nozzles with the highest weighted average efficiency and beneficial to the long-term operation and increased power generation of the hydropower station.

[0008] Preferably, it includes determining the specific speed n of the water turbine s range: ; In the formula, Z0 is the number of nozzles, n s unit m·kW.

[0009] Preferably, it includes determining the rated speed n of the water turbine r : ; In the formula, H r is the rated head of the water turbine, unit m; N tr is the single-unit rated output of the water turbine, unit kW; n r unit r / min.

[0010] Preferably, it includes determining the runner diameter D of the water turbine l : ; In the formula, n r is the rated speed of the water turbine; when there are multiple values for the runner diameter, select the runner diameter with the smallest manufacturing difficulty coefficient.

[0011] Preferably, it includes determining the specific speed n of the water turbine s : ; In the formula N tr is the single-unit rated output of the water turbine; Determine the specific speed n of a single nozzle sl : ; Determine the jet diameter d0: ; In the formula, Q r is the single-unit rated flow of the water turbine; Determine the nozzle diameter d: ; Determine the optimal diameter ratio m: ; Determine the jet flow velocity v0: ; In the formula, π takes the value of 3.14.

[0012] Preferably, it includes determining the bucket linear velocity v p : ; In the formula, D l is the runner diameter, and n r is the rated speed of the water turbine.

[0013] Preferably, it includes determining the runaway speed n f : ; In the formula, H max is the maximum head of the water turbine, and D l is the runner diameter.

[0014] Preferably, it includes determining the number of buckets Z l : ; In the formula, D l is the runner diameter, and d0 is the jet diameter of the nozzle.

[0015] The beneficial effects of the present invention are as follows: In a high-head hydropower station with a small flow rate, a large amount of sediment, and a head of 800 - 1000 m, the impulse water turbine determined by the present invention has the significant advantages of the smallest runner diameter, the lowest manufacturing difficulty coefficient, the highest weighted average efficiency, and the largest long-term power generation. Description of the Drawings

[0016] Figure 1 is the top view of the water turbine structure of the present invention; Figure 2 is the side view of the distributor ring pipe of the water turbine of the present invention; Figure 3 is the top view of the runner and the buckets of the present invention; Figure 4 is the side view of the runner and the buckets of the present invention.

[0017] The reference numerals in the drawings are: distributor ring pipe 1, nozzle 2, runner 3, bucket 4. Detailed Embodiments

[0018] Embodiment 1: As Figures 1-4As shown in the figure, a water turbine structure for an ultra-high head hydropower station includes a water distribution ring pipe 1, a nozzle 2, a runner 3 and a bucket 4; the nozzle 2 is connected to the water distribution ring pipe 1, the cross-section of the water distribution ring pipe 1 is circular, and the nozzles 2 are evenly distributed along the circumference on the inner side of the water distribution ring pipe 1; the cross-section of the connection between the nozzle 2 and the water distribution ring pipe 1 is oval, and the cross-section of the end of the nozzle 2 is circular; the bucket 4 is connected to the runner 3, the runner 3 is a cylinder, and the buckets 4 are evenly distributed along the circumference around the runner 3; the center lines of the nozzles 2 are located on the same horizontal plane and tangent to the pitch circle of the runner 3; the water distribution ring pipe 1 and the runner 3 are installed on the same horizontal line, and the vertical center line of the runner 3 coincides with the vertical center line of the water distribution ring pipe 1.

[0019] The parameters of the hydropower station in the embodiment are as follows: Rated head: 859 m, Maximum head: 922 m, Number of units: 4 sets, Rated single-unit water intake flow: 28 m 3 / s, Rated single-unit output: 221 MW, Average sediment concentration in the reservoir: 0.18 kg / m 3 , belonging to a sediment-laden river.

[0020] Embodiment 2: This embodiment provides a method for determining the water turbine structure of an ultra-high head hydropower station, which is as follows: 1. Determine the specific speed n of a single nozzle sl Range: Referring to the range limited by the cavitation-free curve, the rated head of the hydropower station in the embodiment is 859 m, and the rated single-unit water intake flow is 28 m 3 / s. According to the head and flow rate, a single nozzle with as high a specific speed as possible should be selected. However, due to the high sediment content in the river of the hydropower station and relatively serious wear, the specific speed of the single nozzle needs to be appropriately reduced to reduce the cavitation problem.

[0021] Therefore, the range of the specific speed of a single nozzle is initially determined as n sl = 11.7~17.4 m·kW.

[0022] 2. Determine the number of nozzles Z0: The rated head of the hydropower station in the embodiment is 859 m, and the maximum head is 922 m. Five or six nozzles can be selected for the water turbine.

[0023] The rated single-unit output of the hydropower station in the embodiment is 221 MW, and there are 4 units. When the number of nozzles is 6, the weighted average efficiency of the water turbine is the highest, and the long-term power generation of the hydropower station is the most.

[0024] Therefore, select 6 nozzles that are more beneficial to the long-term operation and increased power generation of the hydropower station in the embodiment, i.e., Z0 = 6.

[0025] 3. Determine the specific speed n of the water turbine s Range: According to the formula: ; According to 1, the specific speed of a single nozzle is 11.7 - 17.4 m·kW. According to 2, the number of nozzles Z0 = 6. Substitute into the formula 3 to obtain the specific speed n of the water turbine s Range: 28.7 - 42.6 m·kW.

[0026] 4. Determine the rated speed n of the water turbine r : According to the formula: ; In the formula: H r is the rated head of the hydropower station in the embodiment, 859 m.

[0027] n s is the specific speed of the water turbine determined in 3, 28.7 - 42.6 m·kW.

[0028] N tr is the single-unit rated output of the water turbine in the embodiment, 221 MW, i.e., 221000 kW.

[0029] Substitute into the formula 4 to obtain the rated speed n of the water turbine r Range: 284 - 420 r / min.

[0030] According to the rated speed n of the water turbine obtained from the formula 4 r Range, select the commonly used speeds within the interval as 300 r / min, 333 r / min, and 375 r / min.

[0031] Preliminarily determine that the rated speed n of the water turbine of the hydropower station in the embodiment r = 300 r / min, or n r = 333 r / min, or n r = 375 r / min.

[0032] 5. Determine the runner diameter D of the water turbine l : According to the formula: ; In the formula: H r is the rated head of the hydropower station in the embodiment, 859 m.

[0033] n rRated speed of the water turbine determined for the said 4, n r = 300 r / min, or n r = 333 r / min, or n r = 375 r / min are respectively substituted into the calculation.

[0034] Substitute into the said formula 5: When n r = 300 r / min, the runner diameter D l is 3.9 m.

[0035] When n r = 333 r / min, the runner diameter D l is 3.5 m.

[0036] When n r = 375 r / min, the runner diameter D l is 3.1 m.

[0037] According to the water turbine manufacturing difficulty coefficient characterization parameter: D l 2 × H r .

[0038] In the formula: H r is the rated head of the hydropower station in the said embodiment, 859 m.

[0039] D l is the runner diameter determined for the said 5.

[0040] When the head is constant, the smaller the runner diameter, the lower the water turbine manufacturing difficulty coefficient.

[0041] Therefore, initially select the runner diameter D l to be 3.1 m.

[0042] Furthermore, according to the said 2, when the weighted average efficiency of the water turbine of the hydropower station in the embodiment is the highest, the runner diameter is 3.3 m.

[0043] Furthermore, determine the runner diameter D l = 3.3 m.

[0044] Furthermore, determine the rated speed n of the water turbine according to the said formula 5 r , that is, n r = 375 r / min.

[0045] 6. Determine the specific speed n of the water turbine s : According to the said formula: ; In the formula: n r is the rated speed of the water turbine. According to the said 5, nr = 375 r / min.

[0046] H r For the rated head of the hydropower station in the said embodiment, it is 859 m.

[0047] N tr For the single-unit rated output of the water turbine in the said embodiment, it is 221,000 kW.

[0048] Substitute into the said formula 6, and the specific speed n of the water turbine is obtained s = 38 m·kW.

[0049] 7. Determine the specific speed n of a single nozzle sl Value: According to the said formula: ; In the formula: n s is the specific speed of the water turbine. According to the said item 6, n s = 38 m·kW.

[0050] Z0 is the number of nozzles. According to the said item 2, Z0 = 6.

[0051] Substitute into the said formula 7, and the specific speed n of a single nozzle is obtained sl = 15.5 m·kW.

[0052] 8. Determine the jet diameter d0 of the nozzle: According to the said formula: ; In the formula: Q r is the single-unit rated flow rate of the water turbine in the said embodiment, 28 m 3 / s.

[0053] H r is the rated head of the hydropower station in the said embodiment, 859 m.

[0054] Z0 is the number of nozzles. According to the said item 2, Z0 = 6.

[0055] Substitute into the said formula 8, and the jet diameter d0 of the nozzle is obtained as 217 mm.

[0056] Combined with engineering experience, select the optimal jet diameter d0 = 235 mm.

[0057] 9. Determine the nozzle diameter d: According to the said formula: ; In the formula: d0 is the jet diameter of the nozzle. According to the said item 8, d0 = 235 mm.

[0058] Take the coefficient as 1.2.

[0059] Substitute into the formula 9, and the nozzle diameter d = 282 mm.

[0060] 10. Determine the optimal diameter ratio m: According to the formula: ; In the formula: D l is the runner diameter. According to item 5, D l = 3.3 m.

[0061] d0 is the nozzle jet diameter. According to item 8, d0 = 235 mm.

[0062] Substitute into the formula 10, and the optimal diameter ratio m = 14 is obtained.

[0063] 11. Determine the jet flow velocity v0: According to the formula: ; In the formula: Q r is the single-unit rated flow of the water turbine in the embodiment, 28 m 3 / s.

[0064] d0 is the nozzle jet diameter. According to item 8, d0 = 235 mm.

[0065] Z0 is the number of nozzles. According to item 2, Z0 = 6; Take π as 3.14.

[0066] Substitute into the formula 11, and the jet velocity v0 = 108 m / s is obtained.

[0067] 12. Determine the bucket linear velocity v p : According to the formula: ; In the formula: D l is the runner diameter. According to item 5, D l = 3.3 m.

[0068] n r is the rated speed of the water turbine. According to item 5, n r = 375 r / min.

[0069] Take π as 3.14; Substitute into the formula 12, and the bucket linear velocity v p = 65 m / s.

[0070] 13. Determine the runaway speed n f : According to the formula: ; In the formula, H max is the maximum head of the hydropower station in the embodiment, 922 m.

[0071] D l is the runner diameter, according to the above 5, D l = 3.3 m.

[0072] Substitute into the above formula 13 to obtain the runaway speed n f = 644 r / min.

[0073] 14. Determine the number of buckets Z l : According to the above formula: ; In the formula: D l is the runner diameter, according to the above 5, D l = 3.3 m.

[0074] d0 is the jet diameter of the nozzle, according to the above 8, d0 = 235 mm.

[0075] The coefficient value is 6.

[0076] Substitute into the above formula 14 to obtain the number of buckets Z l = 22 pieces.

[0077] Example 3: Taking the turbine structure determined by this method as an example, it is illustrated by a specific engineering example: A certain hydropower station in Pakistan is located on a first-class tributary. The river runoff is mainly formed by snowmelt and it is a sediment-laden river. The parameters of the hydropower station are as follows: Rated head: 859 m, maximum head: 922 m, number of units: 4, single-unit rated diverted flow: 28 m 3 / s, single-unit rated output: 221 MW.

[0078] To reduce the construction cost and meet the power generation demand, the turbine structure and parameters determined by this method are as follows: Number of nozzles 6, turbine specific speed 38 m·kW, turbine rated speed 375 r / min, turbine runner diameter 3.3 m, number of buckets 22, nozzle specific speed 15.5 m·kW, nozzle diameter 282 mm, optimal diameter ratio 14, jet diameter 235 mm, jet flow velocity 108 m / s, bucket linear velocity 65 m / s, runaway speed 644 r / min.

[0079] In summary, a turbine structure and determination method for an extra-high head hydropower station are applicable to extra-high head hydropower stations with small flow, a large amount of sediment, and a head of 800 - 1000 m. The turbine structure determined by the present invention has the characteristics of the smallest runner diameter and the lowest manufacturing difficulty coefficient, and has the advantages of the largest long-term power generation of the hydropower station and the highest weighted average efficiency of the turbine.

Claims

1. A water turbine structure for a super-high head hydropower station, characterized in that, It includes a water distribution ring pipe, nozzles, a runner and buckets; the nozzles are connected to the water distribution ring pipe, the cross-section of the water distribution ring pipe is circular, and the nozzles are evenly distributed along the circumference on the inner side of the water distribution ring pipe; the cross-section at the connection of the nozzle and the water distribution ring pipe is elliptical, and the cross-section at the end of the nozzle is circular; the buckets are connected to the runner, the runner is a cylinder, and the buckets are evenly distributed along the circumference on the periphery of the runner; the center lines of the nozzles are located on the same horizontal plane and tangent to the pitch circle of the runner; the water distribution ring pipe and the runner are installed on the same horizontal line, and the vertical center line of the runner coincides with the vertical center line of the water distribution ring pipe.

2. The method for determining the structure of a very high head hydropower turbine according to claim 1, characterized in that, including determining the range of the specific speed n of a single nozzle sl as follows: According to the parameter levels of impulse turbines at home and abroad and the empirical values of the cavitation-free curve, determine the range of the specific speed n sl of the water turbine for a very high head hydropower station with a head of 800 - 1000 m, in the unit of m·kW.

3. The method for determining the structure of a high-head hydropower turbine according to claim 2, characterized in that It includes determining the number of nozzles Z0: According to the number of nozzles selected with the highest weighted average efficiency and beneficial to the long-term operation and more power generation of the hydropower station.

4. A method for determining the structure of a water turbine in an ultra-high head hydropower station according to claim 3, characterized in that, including determining the range of the specific speed n of the water turbine s as follows: ； Where Z0 is the number of nozzles, n s Unit: m·kW.

5. The determination method of a high-head hydropower turbine structure according to claim 4, characterized in that including determining the rated speed n of the water turbine r : ； Where, H r is the rated head of the water turbine, in m; N tr is the rated output of a single water turbine, in kW; n r in r / min.

6. The method for determining the structure of a water turbine of an ultra-high head hydropower station according to claim 5, characterized in that including determining the diameter D of the turbine runner l : ； where n r is the rated speed of the water turbine; when there are multiple values for the runner diameter, select the runner diameter with the smallest manufacturing difficulty coefficient.

7. The method for determining the structure of a water turbine in an ultra-high head hydropower station according to claim 6, characterized in that including determining the specific speed n of the water turbine s : ； where N tr is the rated output of a single hydro-turbine; Determine the specific speed n of a single nozzle sl : ； Determining the jet diameter d0 of the nozzle: ； Where Q r is the rated flow rate of a single hydroturbine; Determining the diameter d of the nozzle: ； Determining the optimal diameter ratio m: ； Determining the jet flow velocity v0: ； In the formula, π takes the value of 3.

14.

8. The method for determining the structure of a water turbine of an ultra-high head hydropower station according to claim 7, characterized in that, including determining the bucket blade linear velocity v p : ； In the formula, D l is the runner diameter, and n r is the rated speed of the water turbine.

9. A method for determining the structure of a water turbine of an ultra-high head hydropower station according to claim 8, characterized in that, including determining the runaway speed n f : ； Where H max is the maximum head of the water turbine, and D l is the runner diameter.

10. The determination method of the structure of a very high head hydropower turbine according to claim 9, characterized in that, including determining the number of buckets Z l : ； where D l is the runner diameter, and d0 is the nozzle jet diameter.

Images