Water supplementing device for eliminating vortex strip of draft tube in full-load range

Abstract

The utility model discloses a water replenishing device for eliminating a vortex strip of a draft tube in a full-load range, which comprises a plurality of upper-layer water replenishing tubes and a plurality of lower-layer water replenishing tubes which are uniformly arranged along the circumferential direction of the wall surface of a taper tube of the draft tube, and the upper-layer water replenishing tubes and the lower-layer water replenishing tubes are arranged in a staggered manner; and electric stop valves are arranged at the upper end ports of each upper-layer water replenishing pipe and each lower-layer water replenishing pipe. Different water supplementing strategies can be adopted in a self-adaptive mode according to the operation load of a unit, so that a cavity vortex strip in the draft tube is restrained or eliminated, and the pressure pulsation amplitude of the draft tube is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of water turbines and relates to a water replenishing device for eliminating the cavity vortex band in the draft tube within the full load range. Background Technique

[0002] As a high-quality renewable energy with flexible operation, hydropower can provide important energy regulation guarantees for the large-scale grid connection of new energy sources such as wind power and photovoltaic power. This requires conventional hydropower stations to have a large load range to regulate the fluctuations of the grid load. The expansion of the operation range inevitably increases the probability of turbine instability, and ensuring the stability of the water turbine within the full load range has become the primary problem to be solved for conventional hydropower stations to achieve energy regulation guarantees. The cavity vortex band inside the draft tube is one of the important factors affecting the stability of Francis turbines. A spiral cavity vortex band will appear inside the draft tube during partial load operation, and a spindle-shaped cavity vortex band will appear during high load operation. The existence of these vortex bands will cause pressure pulsations in the draft tube, which will in turn induce unit vibration and endanger the stability of the unit. Therefore, it is necessary to design a water replenishing device for eliminating the draft tube vortex band within the full load range to suppress or eliminate the cavity vortex band inside the draft tube, so as to weaken the intensity of the draft tube pressure pulsation and improve the stability of the Francis turbine within the full load range. Summary of the Utility Model

[0003] The purpose of the utility model is to provide a water replenishing device for eliminating the draft tube vortex band within the full load range. This water replenishing device can adaptively adopt different water replenishing strategies according to the operating load of the unit, thereby suppressing or eliminating the cavity vortex band inside the draft tube and reducing the amplitude of the draft tube pressure pulsation.

[0004] The technical solution adopted by the utility model is that a water replenishing device for eliminating the draft tube vortex band within the full load range includes a number of upper layer water replenishing pipes and a number of lower layer water replenishing pipes evenly arranged circumferentially along the wall surface of the draft tube cone. Each upper layer water replenishing pipe and each lower layer water replenishing pipe are arranged alternately, and an electric stop valve is provided at the upper end port of each upper layer water replenishing pipe and each lower layer water replenishing pipe.

[0005] The characteristics of the utility model also lie in:

[0006] The number of upper layer water replenishing pipes is 4, and the four upper layer water replenishing pipes are located in the same radial plane.

[0007] The included angle between the center line of each upper layer water replenishing pipe and the outer normal direction of the wall surface of the draft tube cone is 45°.

[0008] The number of lower layer water replenishing pipes is 4, and the four lower layer water replenishing pipes are located in the same radial plane.

[0009] The included angle between the center line of each lower layer water replenishing pipe and the outer normal direction of the wall surface of the draft tube cone is 45°.

[0010] The beneficial effects of the present utility model are as follows. The present utility model arranges two layers of water replenishing pipe devices on the draft tube cone of the water turbine to replenish water into the draft tube according to different operating load magnitudes, suppress or eliminate the cavity vortex band inside the draft tube, reduce the pressure pulsation inside the draft tube, improve the hydraulic performance of the draft tube, and achieve the purpose of improving the stability of the water turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a three-dimensional layout schematic diagram of the water replenishing device for eliminating the vortex band in the draft tube within the full load range of the present utility model;

[0012] Figure 2 is a top view of the upper water replenishing pipe structure of the water replenishing device for eliminating the vortex band in the draft tube within the full load range of the present utility model;

[0013] Figure 3 is a top view of the lower water replenishing pipe structure of the water replenishing device for eliminating the vortex band in the draft tube within the full load range of the present utility model.

[0014] In the figure, 1. upper water replenishing pipe, 2. draft tube cone, 3. lower water replenishing pipe, 4. electric globe valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] The present utility model will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0016] The water replenishing device for eliminating the vortex band in the draft tube within the full load range of the present utility model, as Figure 1 shown, includes an electric globe valve 4, an upper water replenishing pipe 1, and a lower water replenishing pipe 3. The upper water replenishing pipes 1 are circumferentially and uniformly arranged along the wall surface of the draft tube cone 2. The number of upper water replenishing pipes 1 is 4. An electric globe valve 4 is provided at the upper port of each upper water replenishing pipe 1; the lower water replenishing pipes 3 are circumferentially and uniformly arranged along the wall surface of the draft tube cone 2. The number of lower water replenishing pipes 3 is 4. An electric globe valve 4 is provided at the upper end port of each lower water replenishing pipe 3. The four upper water replenishing pipes 1 and the four lower water replenishing pipes 3 are all controlled by the electric globe valve 4. The electric globe valves of all the upper water replenishing pipes 1 are uniformly controlled, and the electric globe valves of the lower water replenishing pipes 3 are uniformly controlled. According to the load range in which the unit operates, it is determined whether to use the upper water replenishing pipe 1 or the lower water replenishing pipe 3 to replenish water into the draft tube cone 2.

[0017] The four upper water replenishing pipes 1 and the four lower water replenishing pipes 3 can adjust the water replenishing strategy for the draft tube according to different operating loads of the water turbine. As Figure 2 shown, the number of water replenishing pipelines of the upper water replenishing pipe 1 is 4. The included angle between the center line of each upper water replenishing pipe 1 and the outer normal direction of the wall surface of the draft tube cone 2 is 45°. The four upper water replenishing pipes 1 are located in the same radial plane, and the 4 upper water replenishing pipes 1 are circumferentially evenly distributed. From Figure 2It can be seen that each upper water replenishing pipe 1 deviates towards the counterclockwise direction of the outer normal of the wall surface of the draft tube cone 2. The ratio of the length L1 of each upper water replenishing pipe 1 in the radial plane to the runner outlet diameter D2 is L1 / D2 = 1 / 2, but it can be adjusted according to the actual pit size. The pipe diameter d1 of each upper water replenishing pipe 1 is 60 mm.

[0018] As Figure 3 shown, the number of water replenishing pipelines of the lower water replenishing pipes 3 is 4. The included angle between the center line of each lower water replenishing pipe 3 and the outer normal direction of the wall surface of the draft tube cone 2 is 45°; the 4 lower water replenishing pipes 3 are located in the same radial plane, and the 4 lower water replenishing pipes 3 are evenly distributed along the circumferential direction. Looking Figure 3 from above, each lower water replenishing pipe 3 deviates towards the clockwise direction of the outer normal of the wall surface of the draft tube cone 2. The ratio of the length L2 of each lower water replenishing pipe 3 in the radial plane to the runner outlet diameter D2 is L2 / D2 = 3 / 4, but it can be adjusted according to the actual pit size. The pipe diameter d2 of each water replenishing pipe of the lower water replenishing pipes is 60 mm.

[0019] Embodiment 1

[0020] A water replenishing device for eliminating the draft tube vortex band within the full load range includes a plurality of upper water replenishing pipes 1 and a plurality of lower water replenishing pipes 3 that are evenly arranged circumferentially along the wall surface of the draft tube cone 2. The upper water replenishing pipes 1 and the lower water replenishing pipes 3 are arranged alternately with each other, and an electric stop valve 4 is provided at the upper end port of each upper water replenishing pipe 1 and each lower water replenishing pipe 3.

[0021] Embodiment 2

[0022] A water replenishing device for eliminating the draft tube vortex band within the full load range includes a plurality of upper water replenishing pipes 1 and a plurality of lower water replenishing pipes 3 that are evenly arranged circumferentially along the wall surface of the draft tube cone 2. The upper water replenishing pipes 1 and the lower water replenishing pipes 3 are arranged alternately with each other, and an electric stop valve 4 is provided at the upper end port of each upper water replenishing pipe 1 and each lower water replenishing pipe 3. The number of the upper water replenishing pipes 1 is 4, and the four upper water replenishing pipes 1 are located in the same radial plane.

[0023] Embodiment 3

[0024] A water replenishing device for eliminating the draft tube vortex band within the full load range includes a plurality of upper water replenishing pipes 1 and a plurality of lower water replenishing pipes 3 that are evenly arranged circumferentially along the wall surface of the draft tube cone 2. The upper water replenishing pipes 1 and the lower water replenishing pipes 3 are arranged alternately with each other, and an electric stop valve 4 is provided at the upper end port of each upper water replenishing pipe 1 and each lower water replenishing pipe 3. The number of the upper water replenishing pipes 1 is 4, and the four upper water replenishing pipes 1 are located in the same radial plane. The included angle between the center line of each upper water replenishing pipe 1 and the outer normal direction of the wall surface of the draft tube cone 2 is 45°.

[0025] Embodiment 4

[0026] A water replenishing device for eliminating the spiral vortex band in the draft tube within the full load range, comprising a plurality of upper layer water replenishing pipes 1 and a plurality of lower layer water replenishing pipes 3 which are circumferentially and uniformly arranged along the wall surface of the draft tube cone 2. The upper layer water replenishing pipes 1 and the lower layer water replenishing pipes 3 are arranged in an alternating manner. Electric stop valves 4 are provided at the upper end ports of each upper layer water replenishing pipe 1 and each lower layer water replenishing pipe 3. The number of the upper layer water replenishing pipes 1 is 4, and the four upper layer water replenishing pipes 1 are located in the same radial plane. The central line of each upper layer water replenishing pipe 1 forms an angle of 45° with the outer normal direction of the wall surface of the draft tube cone 2. The number of the lower layer water replenishing pipes 3 is 4, and the four lower layer water replenishing pipes 3 are located in the same radial plane. The central line of each lower layer water replenishing pipe 3 forms an angle of 45° with the outer normal direction of the wall surface of the draft tube cone 2.

[0027] The control method of the water replenishing device for eliminating the spiral vortex band in the draft tube within the full load range of the present utility model is as follows:

[0028] Step 1: Calculate the current power P1 of the water turbine according to the operating parameters of the water turbine, and calculate the current relative power P’ according to the current power by the following formula (1):

[0029]

[0030] In the above formula, P r is the rated power of the water turbine.

[0031] Step 2: Determine the water replenishing strategy of the water replenishing device according to the calculated P’. Suppose the rotation direction of the runner in Figure 2 and Figure 3 is counterclockwise, then the start-up strategy of the water replenishing device is as follows:

[0032] When 0% < P’ < 70%, all the electric stop valves 4 of the upper layer water replenishing pipes 1 are opened, and the upper layer water replenishing pipes 1 replenish water into the draft tube cone 2;

[0033] When 70% ≤ P’ < 90%, all the electric stop valves 4 of the upper layer water replenishing pipes 1 and the lower layer water replenishing pipes 3 are closed, and the water replenishment into the draft tube cone 2 is stopped;

[0034] When 90% ≤ P’ < 100%, all the electric stop valves 4 of the lower layer water replenishing pipes 3 are opened, and the lower layer water replenishing pipes 3 replenish water into the draft tube cone 2;

[0035] Suppose the rotation direction of the runner in Figure 2 and Figure 3 is clockwise, then the start-up strategy of the water replenishing device is as follows:

[0036] When 0% < P’ < 70%, all the electric stop valves 4 of the lower layer water replenishing pipes 3 are opened, and the lower layer water replenishing pipes 3 replenish water into the draft tube cone 2;

[0037] When 70% ≤ P’ < 90%, all the electric globe valves 4 of the upper water replenishing pipe 1 and the lower water replenishing pipe 3 are closed, and the water replenishment to the draft tube cone 2 stops;

[0038] When 90% ≤ P’ < 100%, all the electric globe valves 4 of the upper water replenishing pipe 1 are opened, and the upper water replenishing pipe 1 replenishes water to the draft tube cone 2;

[0039] Step 3: Control all the electric globe valves 4 of the upper water replenishing pipe 1 and the lower water replenishing pipe 3 according to the water replenishing device control strategy in Step 2, so as to achieve the purpose of adaptively improving the flow pattern of the draft tube cone, reducing the pressure pulsation, and reducing the water flow energy loss.

[0040] The water replenishing device for eliminating the draft tube vortex band within the full load range proposed by the present utility model can suppress or eliminate the cavity vortex band in the draft tube, so as to achieve the effect of weakening the draft tube pressure pulsation intensity and improving the stability of the Francis turbine within the full load range.

Claims

1. A water replenishing device for eliminating draft tube vortex bands within the full load range, characterized in that: It includes a number of upper-layer water supply pipes (1) and a number of lower-layer water supply pipes (3) that are evenly arranged circumferentially along the wall surface of the draft tube cone (2). Each upper-layer water supply pipe (1) and each lower-layer water supply pipe (3) are arranged in an alternating manner. An electric stop valve (4) is provided at the upper end port of each upper-layer water supply pipe (1) and each lower-layer water supply pipe (3).

2. The water replenishing device for eliminating draft tube vortex bands within the full load range according to claim 1, wherein: The number of the upper-layer water supply pipes (1) is 4, and the four upper-layer water supply pipes (1) are located in the same radial plane.

3. The water replenishing device for eliminating the draft tube vortex band within the full load range according to claim 2, wherein: The included angle between the center line of each upper-layer water supply pipe (1) and the outer normal direction of the wall surface of the draft tube cone (2) is 45°.

4. The water replenishing device for eliminating draft tube vortex bands within the full load range according to claim 2, wherein: The number of the lower-layer water supply pipes (3) is 4, and the four lower-layer water supply pipes (3) are located in the same radial plane.

5. The water replenishing device for eliminating draft tube vortex bands within the full load range according to claim 4, characterized in that: The included angle between the center line of each lower-layer water supply pipe (3) and the outer normal direction of the wall surface of the draft tube cone (2) is 45°.

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