Water inlet and outlet structure for improving outflow of vertical shaft

Abstract

The utility model discloses a water inlet and outlet structure for improving vertical shaft outflow, which belongs to the technical field of hydraulic engineering and comprises a water flow channel, the water flow channel is provided with a vertical section, a water inlet and outlet is arranged at the upper end of the vertical section, and diversion members are uniformly distributed around the water inlet and outlet. The device is characterized in that the upper portion of the flow dividing component is arranged on the periphery above the water inlet and outlet to form a cylindrical retaining wall of a stopping structure, and the upper edge of the cylindrical retaining wall is higher than the dead water level of a reservoir area of the pumped storage power station. According to the vertical shaft type water inlet and outlet structure, the water flow uniformity, flow distribution and trash rack flow velocity distribution are remarkably improved by introducing the buffer water body and optimizing the design, the reverse flow velocity problem is thoroughly eliminated, the operation safety of a power station is improved, the service life of equipment is prolonged, and economic benefits are increased.

Description

Technical Field

[0001] The utility model belongs to the technical field of water conservancy projects, and particularly relates to a water inlet and outlet structure for improving the outflow of a shaft. Background Technique

[0002] A pumped-storage power station is a power system that optimizes the grid load by storing and regulating electricity. It uses electricity during the low-demand period to pump water from the lower reservoir to the upper reservoir for storage; when the peak electricity demand comes, the water stored in the upper reservoir flows through a water turbine to generate electricity, thereby providing additional electricity to the grid. This process not only helps balance the grid load but also improves the reliability and stability of the power system. Pumped-storage power stations can effectively regulate power supply, support the access of renewable energy, and promote the sustainable use of energy. In recent years, the construction and development of pumped-storage power stations in China have been rapid. The shaft-type water inlet and outlet has been widely used in pumped-storage power stations due to its flexible layout, relatively low requirements for topographical and geological conditions, smaller quantities of excavation and concrete structures, and simple structural stress, etc.

[0003] The structure of the existing shaft-type water inlet and outlet is as Figure 3 , which mainly includes a water flow channel, a cover plate 8, a guide cone 9, and a guide cone 5. The water flow channel is further divided into four parts: a vertical diffusion section 1, a straight pipe section 2, a bend section 3, and a transition section 4. The bend section forms a 90° channel transformation, that is, from horizontal transportation to vertical transportation, and at the water inlet and outlet, the water flow is deformed into a horizontal direction again.

[0004] Although the shaft-type water inlet and outlet is a common design in pumped-storage power stations, it has some significant disadvantages and deficiencies in practical applications:

[0005] Since the shaft-type water inlet and outlet design needs to achieve two-way water flow (the water flow changes from horizontal to vertical and then from vertical to horizontal), the water flow undergoes two 90° flow direction changes within a short distance. This design makes the flow direction of the water flow change violently, resulting in very complex hydraulic conditions. In the inflow (power generation condition) and outflow (pumping condition) states, the water flow needs to change its direction under the obstruction of the guide cone and the cover plate, which easily generates eddy currents and unstable flow patterns, and these factors all have an adverse impact on the efficiency and safety of the system.

[0006] In the pumping (outflow) condition, there is a reverse flow velocity at the bottom of the trash rack section that is difficult to eliminate. The existence of the reverse flow velocity may cause damage to the trash rack structure and affect its normal function. The structural limitations of the trash rack and the complex flow pattern of the water flow make it difficult to eliminate these reverse flow velocities, which not only affects the long-term stability of the equipment but also increases the difficulty of maintenance.

[0007] At the outlet of the shaft - type water inlet and outlet, the obstruction effects of the cover plate and the flow - guiding cone are obvious. These structural components cause the water flow to face additional resistance when turning from vertical to horizontal, resulting in energy loss and uneven water flow. Although the design purpose of the flow - guiding cone is to optimize the entry of water flow, the resistance generated during the turning process often causes a decrease in flow velocity and efficiency loss.

[0008] Currently, although many researchers have conducted a large number of numerical analyses and model tests on traditional cover - plate shaft - type water inlets and outlets, the problems of reverse flow velocity and flow instability still cannot be completely solved. Although these studies are helpful for understanding and improving the design of shaft - type water inlets and outlets, in practical engineering applications, hydrodynamic problems are still significant, affecting the reliability and performance of the system. Summary of the Utility Model

[0009] Aiming at the problems existing in the prior art, the present utility model provides a water inlet and outlet structure for improving shaft outflow, which aims to solve the problems such as the violent turning of water flow, reverse flow velocity, and structural obstruction in the design of traditional shaft - type water inlets and outlets, and their impacts on the operation efficiency and safety of equipment.

[0010] The present utility model is realized as follows: A water inlet and outlet structure for improving shaft outflow includes a water flow channel. The water flow channel has a vertical section. The upper end of the vertical section is a water inlet and outlet. The water inlet and outlet are evenly distributed with flow - dividing components around it. It is characterized in that: The upper part of the flow - dividing component is provided with a cylindrical retaining wall that forms a retaining structure above the water inlet and outlet. The height of the upper edge of the cylindrical retaining wall is higher than the dead water level of the reservoir area of the pumped - storage power station.

[0011] In the above - mentioned technical solution, preferably, it includes an annular cover plate. The annular cover plate is arranged between the flow - dividing component and the cylindrical retaining wall. The annular cover plate forms an annular component with openings and is supported by the flow - dividing component. The cylindrical retaining wall is arranged on the circumferential cover plate.

[0012] In the above - mentioned technical solution, preferably, the opening diameter of the annular cover plate is greater than 2 / 3 of the diameter of the circumscribed circle of the annular cover plate.

[0013] In the above - mentioned technical solution, preferably, the water flow channel is, in sequence from the water inlet and outlet inwards, a vertical diffusion section, a straight - pipe section, a bend section, and a transition section. The water inlet and outlet are arranged at the upper end of the vertical diffusion section.

[0014] In the above - mentioned technical solution, preferably, the flow - dividing component is flow - dividing piers evenly spaced circumferentially around the water inlet and outlet.

[0015] The water inlet and outlet structure for improving shaft outflow proposed by the present utility model shows multiple advantages and remarkable effects in terms of optimized design and performance improvement:

[0016] 1. The shaft - type inlet - outlet structure has been optimized in design, and its hydraulic indexes under both pumping (out - flow) and power - generation (in - flow) conditions meet the requirements of relevant design codes. This ensures the hydraulic stability of the power station under different operation modes, enabling the power station to operate safely and efficiently under various conditions.

[0017] 2. Through innovative structural design, this structure introduces a buffer water body, which is significantly different from traditional physical buffer and diversion structures. The buffer water body is formed at the upper end of the inlet - outlet. As a "natural water cushion", it has unique advantages: by absorbing the kinetic energy and turbulence of the water flow, the buffer water body reduces the impact force when the water flow enters the shaft, making the water flow more stable. Compared with traditional rigid structures, the gentle adjustment effect of the buffer water body significantly reduces the turbulence and turbulence of the water flow, improving the uniformity of the water flow. Due to the rigid physical obstruction of traditional buffer structures, eddies are likely to be generated at the inlet - outlet, while the buffer water body can effectively dissipate eddies through the natural flow characteristics of water, reducing hydrodynamic disturbance and making the entire hydraulic system more stable. The buffer water body can dynamically adjust the water flow velocity and pressure, reduce energy loss, make the water flow through more smoothly, and thus improve the efficiency of the water flow passing through the shaft. This effect is incomparable to traditional physical buffer devices.

[0018] 3. Due to the existence of the buffer water body and the optimized hydraulic design, the out - flow of the shaft - type inlet - outlet is more uniform. Especially under the pumping condition, the distribution of the water flow is smoother, avoiding the situation of excessive or too small local water flow, and ensuring the stability of the entire water flow system.

[0019] 4. The optimized structure makes the flow distribution of each orifice more balanced, which is crucial for ensuring the flow consistency of the water flow at different orifices. Uniform flow distribution helps to reduce hydraulic fluctuations and prevent hydraulic pressure imbalance caused by excessive or too low local flow.

[0020] 5. In the design of traditional trash racks, the flow velocity is likely to be uneven, especially at the bottom of the cross - section, where reverse flow velocities are likely to accumulate. By optimizing the water flow path and introducing a buffer water body, the flow velocity distribution at the trash - rack cross - section is significantly improved, the water flow is more uniform at the trash rack, and the turbulent flow and unstable flow phenomena are reduced.

[0021] 6. This utility model particularly solves the long - existing problem of reverse flow velocity at the bottom of the trash - rack cross - section. In the design of traditional shaft - type inlet - outlets, the reverse flow velocity causes significant impact on the trash - rack structure, making it prone to damage. However, through the adjustment of the buffer water body and the improved water flow path in this optimized design, the reverse flow velocity is completely eliminated, thus avoiding the damage to the trash rack caused by the reverse flow velocity.

[0022] 7. Due to the elimination of the reverse flow velocity, the trash rack structure no longer bears frequent impacts and abrasions, greatly extending its service life. The inspection and replacement frequencies of the trash rack are significantly reduced, reducing the maintenance costs during operation. This advantage directly enhances the economic benefits of the power station and reduces the daily operation expenses.

[0023] 8. By optimizing the water flow distribution, achieving uniform outflow, and effectively solving the reverse flow velocity problem, the overall hydraulic conditions of the shaft-type intake and outlet are greatly improved, and the power station operates more stably and safely under different working conditions. Especially under high-load conditions, this design effectively reduces the accident risk caused by hydraulic anomalies and enhances the reliability of the power station.

[0024] 9. By reducing the equipment maintenance and replacement costs and extending the equipment life, the overall operation cost of the power station is significantly reduced. At the same time, the improvement of water flow efficiency also directly increases the power generation efficiency and pumping efficiency of the power station, further enhancing the economic benefits of the power station. Considering these factors comprehensively, this optimized design brings significant economic advantages to the long-term operation of the power station.

[0025] The technical solution proposed by the present utility model comprehensively improves the hydrodynamic performance and structural stability of the shaft-type intake and outlet through the introduction of a buffer water body and optimized design. It not only solves the reverse flow velocity problem in the traditional design but also significantly improves the water flow uniformity, orifice flow distribution, and the operating conditions of the trash rack, ensuring the operation safety of the power station and enhancing the economic benefits. Brief Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of the present utility model;

[0027] Figure 2 is a top view of the intake and outlet described in the present utility model;

[0028] Figure 3 is a schematic structural diagram of the existing intake and outlet. Detailed Embodiments

[0029] In order to make the objectives, technical solutions, and advantages of the present utility model clearer and more understandable, the present utility model will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0030] In order to solve the problems of violent water flow turning, reverse flow velocity and structural obstruction in the traditional vertical inlet and outlet design, the utility model particularly provides an inlet and outlet structure for improving the vertical shaft outflow. Through the introduction of a buffer water body and optimized design, this vertical shaft inlet and outlet structure significantly improves the water flow uniformity, flow distribution and trash rack flow velocity distribution, completely eliminates the reverse flow velocity problem, improves the operation safety, equipment life and economic benefits of the power station, and has wide popularization and application value. In order to further illustrate the structure of the utility model, the following is a detailed description with reference to the drawings:

[0031] Please refer to Figure 1 and Figure 2 , an inlet and outlet structure for improving the vertical shaft outflow, including a water flow channel. The water flow channel has a vertical section, and the upper end of the vertical section is the inlet and outlet, and diversion members are evenly distributed around the inlet and outlet.

[0032] The water flow channel is successively a vertical diffusion section 1, a straight pipe section 2, a bend section 3 and a transition section 4 from the inlet and outlet inwards. The inlet and outlet is arranged at the upper end of the vertical diffusion section. The vertical diffusion section is a vertical part in the vertical shaft with a gradually increasing cross-sectional area, and its main function is to slow down the water flow velocity and prevent adverse effects caused by too fast water flow. The straight pipe section is a vertical straight pipe through which the water flow passes, used to maintain the stability of the water flow and ensure that the water flow flows in or out evenly. The bend section is the bent part in the water flow channel, used to change the direction of the water flow, which is to meet the needs of terrain or hydraulic engineering layout. The transition section is a part where the cross-section of the pipe gradually changes, used to adjust the water flow velocity and pressure and reduce the energy loss in the flow.

[0033] The diversion members are diversion piers 5 evenly arranged at intervals around the inlet and outlet in the circumferential direction. The diversion piers are existing members. The diversion piers are arranged at the upper end of the vertical diffusion section of the vertical shaft inlet and outlet, at the key position where the water flow enters or exits the vertical shaft. Through reasonable geometric design, the water flow is guided and dispersed, making the water flow more uniform when entering the vertical shaft and reducing the phenomena of eddy current and unstable water flow. The setting of the diversion piers helps to improve the water flow efficiency and ensure that even when the reservoir water level is close to the lowest, the water flow can still smoothly enter or exit the inlet and outlet, maintaining the normal operation of the power station.

[0034] A cylindrical retaining wall 6 forming a retaining structure is arranged above the upper part of the diversion piers around the inlet and outlet. The upper edge height of the cylindrical retaining wall is higher than the dead water level of the reservoir area of the pumped-storage power station. The dead water level of the reservoir area of the pumped-storage power station refers to the water level line that still remains when the water level in the reservoir drops to the lowest.

[0035] It includes an annular cover plate 7 which is arranged between the flow splitting member and the cylindrical retaining wall. The annular cover plate forms an annular member with openings and is supported by the flow splitting member, and the cylindrical retaining wall is arranged on the circumferential cover plate. The diameter of the opening of the annular cover plate is greater than 2 / 3 of the diameter of the circumscribed circle of the annular cover plate. In this embodiment, the flow splitting pier, the annular cover plate and the cylinder are integrally cast concrete members, or they can also be three prefabricated members tightly connected at the construction site.

[0036] The working principle of the present utility model is as follows:

[0037] When the proposed water inlet and outlet structure of the present utility model is adopted, during the pumping condition of the pumped-storage power station, the water flow channel and the space inside the cylindrical retaining wall extending upward are filled with water. The water flow flows upward from the straight pipe section and mixes with the water body inside the cylindrical retaining wall, avoiding the violent turning of the water flow caused by the obstruction of the cover plate set in the traditional structure, effectively slowing down the water flow velocity, thereby improving the velocity distribution of the trash rack section and eliminating the reverse water flow at the bottom of the trash rack section.

[0038] Since the operating conditions of each actual project are different, the specific height of the cylindrical retaining wall needs to be further determined according to the actual situation. In this embodiment, the cylindrical retaining wall should be at least 5 m higher than the dead water level of the reservoir area. At the dead water level, during the outflow condition, for the water flow from the vertical diffusion section, a part of the water flows into the cylindrical wall from the center of the annular cover plate and diffuses around in the cylindrical wall, generating water surface fluctuations. The average water surface in the cylindrical wall is slightly higher than the water level of the reservoir area (dead water level) (about 0.5 m); another part of the water flow interacts with the backflow in the cylindrical wall, turns 90° from the vertical diffusion to horizontal diffusion. The water flow in the vertical diffusion section diffuses relatively fully, and after being split by the flow splitting pier, it flows out evenly. The velocity distribution between the orifices is relatively uniform; the main flow of the trash rack section is close to the upper middle part of the orifice, there is no reverse water flow at the bottom plate of the orifice, and the water surface of the reservoir area outside the water inlet and outlet is relatively stable. During the inflow condition, the water flow mainly enters the water inlet and outlet from the reservoir area through each orifice relatively evenly and smoothly, and the flow pattern is good; the water flow in the cylindrical wall flows into the water inlet and outlet around the edge of the cover plate, and the water level drops (about 0.25 m) compared with the reservoir area (dead water level).

[0039] The top of the cylindrical retaining wall is higher than the dead water level of the reservoir area, which can prevent the water body inside the cylindrical retaining wall and the water body of the reservoir area from flowing mutually from the top at low water levels. The water level difference ensures that the water flow flows out from the flow splitting pier, avoiding the water flow flowing out from the upper end of the cylindrical retaining wall during outflow, and further avoiding the water surface fluctuations caused by the overflow at the upper end.

[0040] During the power generation condition, the water flow enters the water inlet and outlet from the reservoir area. The cylindrical retaining wall can prevent the water flow from flowing into the top end of the cylindrical retaining wall from the reservoir area to form harmful vortices or carry debris in the reservoir into the unit during inflow, which affects the operation safety of the power station.

[0041] Compared with the traditional vertical inlet and outlet, a cylindrical retaining wall and an annular cover plate are used to replace the existing cover plate and flow guide cone. The annular cover plate is used to assist in fixing the orifice trash rack. When discharging water, the obstructive effect of the annular cover plate with openings is relatively small. The water flows upward from the straight pipe section and mixes with the water body inside the cylindrical retaining wall at the top of the annular cover plate, avoiding the sharp turning caused by the cover plate obstructing the water flow, effectively slowing down the water flow velocity, thereby improving the velocity distribution of the trash rack section and eliminating the reverse flow velocity at the bottom of the trash rack section.

[0042] Taking a pumped-storage power station project as an example, it is further described in conjunction with the attached drawings:

[0043] For a pumped-storage power station project, the normal storage level of the reservoir is 606 m, and the dead level is 571 m. The inlet and outlet structure proposed by the present utility model is adopted. In this structure, the inner diameter of the cylindrical retaining wall is 18.5 m, and the top elevation is 580 m, which is 9 m higher than the dead level of the reservoir area. The annular cover plate has an inner circular diameter of 15 m and an outer circular diameter of 20 m.

[0044] The model test results show that when the inlet and outlet structure proposed by the present utility model is adopted, under the pumping (discharging) condition, the head loss of the vertical inlet and outlet is relatively small, the orifice flow distribution is more uniform, the velocity distribution of the trash rack section is more uniform, there is no reverse flow velocity at the bottom of the trash rack section. At low water level (dead level), the water surface fluctuation in the reservoir is relatively small, and at high water level, the water surface is calm. Under the power generation condition, the head loss is relatively small, the orifice flow distribution is uniform, the velocity distribution of the trash rack section is uniform, and the water surface in the reservoir is calm.

[0045] According to the model test results, when applying the inlet and outlet structure proposed by the present utility model, all the hydraulic indexes of the vertical inlet and outlet meet the design and specification requirements. Especially in the pumping condition, the flow distribution of each orifice is more uniform, the velocity distribution of the trash rack section is more uniform, and the reverse flow velocity at the bottom of the trash rack section is eliminated. The inlet and outlet structure proposed by the present utility model effectively solves the problem that it is difficult to eliminate the reverse flow velocity at the bottom of the trash rack section of the vertical inlet and outlet for many years, with obvious effects, which is beneficial to reducing the operation safety risk of the power station and can be widely promoted and applied in pumped-storage power station projects.

[0046] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. An inlet and outlet structure for improving the outflow of a vertical shaft, comprising a water flow channel, the water flow channel having a vertical section, the upper end of the vertical section being the inlet and outlet, and diversion members being evenly distributed around the inlet and outlet, characterized in that: The upper part of the flow dividing member is provided with a cylindrical retaining wall that forms a retaining structure around the upper side of the water inlet and outlet, and the height of the upper edge of the cylindrical retaining wall is higher than the dead water level of the reservoir area of the pumped storage power station.

2. The water inlet and outlet structure for improving the shaft outflow according to claim 1, characterized in that: It includes an annular cover plate, which is arranged between the flow dividing member and the cylindrical retaining wall. The annular cover plate forms an annular member with openings and supported by the flow dividing member, and the cylindrical retaining wall is arranged on the circumferential cover plate.

3. The water inlet and outlet structure for improving the vertical shaft outflow according to claim 2, wherein: The diameter of the opening of the annular cover plate is greater than 2 / 3 of the diameter of the circumcircle of the annular cover plate.

4. The water inlet and outlet structure for improving the outflow of the vertical shaft according to claim 1, characterized in that: The water flow channel is, in sequence from the water inlet and outlet inward, a vertical diffusion section, a straight pipe section, a bend section, and a transition section, and the water inlet and outlet is arranged at the upper end of the vertical diffusion section.

5. The water inlet and outlet structure for improving the shaft outflow according to claim 1, characterized in that: The flow dividing member is a flow dividing pier that is circumferentially and evenly spaced around the water inlet and outlet.

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