Ecological flow releasing device for head dam of runoff type hydropower station

Abstract

The application provides a runoff type hydropower station headrace dam ecological flow releasing device, which is characterized in that: a groove is formed on the top of the headrace dam, a second pipeline is placed in the groove, a siphon structure is formed by cooperation of a first pipeline, the second pipeline, a third pipeline and a fourth pipeline, and the siphon operation is realized by cooperation of a first valve and a second valve, so that the ecological flow is released. The construction method is suitable for releasing the ecological flow of the runoff type hydropower station headrace dam and has high practical value.

Description

Technical Field

[0001] This utility model relates to water conservancy projects, specifically to an ecological flow release device for the head dam of a run-of-river hydropower station. Background Technology

[0002] To ensure the ecological requirements of rivers, it is necessary to release ecological flow from hydropower stations built on rivers. River ecological flow is the amount of water required to meet the ecological needs of downstream areas. This amount of water can ensure the continuous flow of the river and maintain the minimum water demand of the river, which is of great significance for improving the ecological stability of the river basin.

[0003] For run-of-river hydropower stations, which draw water from rivers to generate electricity, a section of the river from the intake to the tailrace outlet forms a reduced-water section. This section is a crucial protected area for the river, requiring ecological flow release to meet water demand. To ensure the water supply requirements of run-of-river hydropower stations and guarantee water diversion, a headworks dam is typically constructed in the river. The headworks dam is the dam at the beginning of the intake canal of a run-of-river hydropower station. These dams are mostly gravity dams. Since their primary function is to impound river water, the headworks dam has a simple structure and does not handle downstream flow release. Therefore, it needs to be modified to accommodate ecological flow release.

[0004] Given the large size of the dam structure, it is not practical to carry out large-scale construction work on it. Moreover, since the head dam impounds the river, there is always water in front of the dam under normal circumstances. Therefore, when releasing ecological flow, it is necessary to take into account its type and structure and provide a reasonable construction method for the release device. Summary of the Invention

[0005] This utility model addresses the problems existing in the prior art by providing an ecological flow release device for the head dam of a run-of-river hydropower station.

[0006] This utility model provides an ecological flow release device for the head dam of a run-of-river hydropower station. The run-of-river hydropower station is a diversion-type power station, with the head dam located in the river channel. A water diversion channel is provided on one side of the head dam, and the end of the water diversion channel is connected to a pressure forebay. A wing wall is provided on the other side of the head dam. The ecological flow release device includes a first pipe, a second pipe, a third pipe, a fourth pipe, a fifth pipe, a first valve, and a second valve. The first pipe is located at the upstream end of the head dam, and its bottom end is lower than the crest elevation of the head dam by a certain distance. The second pipe is located within the head dam, and the third pipe is located downstream of the head dam and fixedly connected to it. The third pipe is horizontally installed. The upper end of the fourth pipe is fixedly connected to the third pipe, and the lower end of the fourth pipe drains water downstream of the dam. The fourth pipe is fixedly connected to the head dam and the wing wall. The first, second, third, and fourth pipes are connected in sequence. A vertical pipe is installed on the second pipe, extending out of the top of the head dam. A first valve is installed at the position where the vertical pipe extends out of the top of the dam. A second valve is installed at the end of the fourth pipe. The third and fourth pipes are both fixed by a fixing device, which includes a U-shaped clamp and fixing bolts. The U-shaped clamp has bolt holes, and the fixing bolts pass through the bolt holes and are fixed to the head dam and the wing wall.

[0007] Preferably, the bottom of the first pipeline is lower than the design water level in front of the headworks dam.

[0008] Preferably, the first valve is a drain valve.

[0009] Preferably, the head dam is a masonry gravity dam, and the wing wall is located on the side of the masonry gravity dam where the water diversion channel is not located.

[0010] This utility model further provides a construction method for this utility model, which specifically includes the following steps: S1: A temporary cofferdam is set up at a certain distance upstream of the headworks dam. At the same time, the power station is started to reduce the water depth in front of the headworks dam. S2: Process the second pipe and the vertical pipe, make a hole in the second pipe, and weld the vertical pipe at the hole position. The vertical pipe is set vertically, and the upper half of the vertical pipe is equipped with a first valve. S3: Excavate at the location where the second pipe is to be installed on the top of the canal head dam. The excavation forms a trapezoidal cross section. Place the second pipe, which has been processed in S2, into the trench formed by the excavation of the canal head dam, and ensure that the vertical pipe is installed vertically. The first valve is located above the top of the dam. S4: Connect the first pipe to the second pipe. The second pipe and the first pipe are fixedly connected by a bend. The first pipe is set vertically downward and is a certain distance below the top of the dam. S5: Connect the third pipe to the second pipe. The second pipe and the third pipe are fixedly connected by a bend. The third pipe is set horizontally and fixed to the head dam by a U-shaped clamp. Bolt holes are provided at both ends of the U-shaped clamp. Fixing is achieved by passing fixing bolts through the bolt holes. S6: Backfill the excavated trench on the top of the head dam with concrete and cure it to the design strength; S7: Connect a fourth pipe to the third pipe. The fourth pipe and the third pipe are fixedly connected by a bend. The fourth pipe is fixedly connected to the head dam and the wing wall. The fourth pipe is fixed to the head dam and the wing wall by a U-shaped clamp. Bolt holes are provided at both ends of the U-shaped clamp. Fixing is achieved by passing fixing bolts through the bolt holes. S8: A second valve is installed at the end of the fourth pipe; S9: Remove the temporary cofferdam and complete the construction of the ecological flow release device.

[0011] The working principle of this utility model is as follows: For the head dam of a run-of-river hydropower station, its structure is simple and no spillway device is installed. If the dam body is structurally modified, the construction is difficult. Therefore, this utility model proposes a siphon structure that uses pipes to form a siphon for ecological flow release, reducing the amount of engineering work and facilitating construction. In particular, it uses a temporary cofferdam to achieve temporary interception and uses the power station to release water, ensuring dry construction. It is chosen during the dry season when the river flow is small and the cofferdam can meet the impoundment requirements. For siphon structures, the top of the head dam is excavated, which is simple to construct and has a low cost. After the siphon pipes are laid, self-compacting concrete is used for backfilling to form a dense structure.

[0012] Unlike typical siphon structures, head dams are prone to debris accumulation areas at both ends. If the siphon pipe inlet is located on either side of the dam, it can cause blockage. Although filter screens and other devices can be installed, this reduces flow capacity and requires frequent cleaning. If the siphon pipe is placed in the middle of the head dam, it can lead to structural instability. Reinforcing it requires complex and costly construction using appropriate piers and other reinforcement devices.

[0013] To address the aforementioned problems, this invention creatively proposes a horizontally arranged third pipe. This horizontally arranged pipe effectively connects the second pipe, located in the middle of the headworks dam, to the wing wall, improving the overall structural stability. Furthermore, its construction is simple, the project cost is low, and it is convenient for construction, replacement, and maintenance. Because of the third pipe, a fourth pipe is connected, which in turn connects to the wing wall and the headworks dam body, improving connection performance and structural stability. Compared to a typical siphon structure, this design is more rationally optimized.

[0014] An exhaust valve is installed on the siphon of the headworks dam to replace the vacuum pump, reducing operating costs. A valve is installed downstream to regulate the ecological discharge, improving the efficiency and effectiveness of equipment operation.

[0015] For the fixing of the pipelines, the pipelines in the headworks dam are fixed by trenching and backfilling. For the first pipeline, it forms a cantilever fixation with the second pipeline. For the third and fourth pipelines, U-shaped clamps are used in conjunction with fixing bolts for fixing. This facilitates construction, maintenance, and replacement, and can achieve good fixing. Compared with fixing methods such as anchor blocks, it is cheaper and simpler to construct. Moreover, through the design of this utility model, the pipelines are fixed to the wing walls and the headworks dam, which greatly improves the fixing effect and realizes the installation and use of the ecological spillway device.

[0016] The advantages of this utility model are: (1) By using the trench on the top of the head dam, the construction work is reduced, and the water flow is discharged by using the siphon structure, which meets the requirements of ecological discharge; (2) Set the inlet of the siphon in the middle of the head dam to ensure the stability of the water flow at the inlet and avoid blockage by debris. Set a horizontal third pipe behind the head dam and lead the fourth pipe of the siphon to the connection between the wing wall and the head dam to improve the strength of the load and avoid impact damage to the siphon during overflow. (3) Installing an air vent valve on the vertical pipe to replace the vacuum pump reduces operating costs. Installing a valve downstream can regulate the ecological discharge and improve the efficiency and effectiveness of equipment operation. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the top structure of the canal head dam. Figure 3 Provide a front view of the top of the headworks dam; Figure 4 A schematic diagram showing the installation of the fourth pipe and clamp. Detailed Implementation

[0018] The following description, based on the accompanying drawings, provides a detailed explanation of the structure defined in this utility model.

[0019] This utility model provides an ecological flow release device for a head dam 1 of a run-of-river hydropower station. The run-of-river hydropower station is a diversion-type power station, with the head dam 1 located in a river channel. A water diversion channel is provided on one side of the head dam 1, and the end of the water diversion channel is connected to a pressure forebay. A wing wall 11 is provided on the other side of the head dam 1. The ecological flow release device includes a first pipe 2, a second pipe 3, a third pipe 4, a fourth pipe 5, a fifth pipe, a first valve 7, and a second valve 8. The first pipe 2 is located at the upstream end of the head dam 1, and its bottom end is lower than the crest elevation of the head dam 1 by a certain distance. The second pipe 3 is located within the head dam 1. The third pipe 4 is located downstream of the head dam 1 and is fixedly connected to it. The fourth pipe 5 is horizontally arranged, with its upper end fixedly connected to the third pipe 4, and its lower end draining water downstream of the dam. The fourth pipe 5 is fixedly connected to the head dam 1 and the wing wall 11. The first pipe 2, the second pipe 3, the third pipe 4, and the fourth pipe 5 are connected in sequence. A vertical pipe 6 is installed on the second pipe 3, extending out of the top of the head dam 1. A first valve 7 is installed at the position where the vertical pipe 6 extends out of the top of the dam. A second valve 8 is installed at the end of the fourth pipe 5. The third pipe 4 and the fourth pipe 5 are both fixed by a fixing device, which includes a U-shaped clamp 9 and a fixing bolt 91. The U-shaped clamp 9 has bolt holes, and the fixing bolt 91 passes through the bolt holes and is fixed to the head dam 1 and the wing wall 11.

[0020] Preferably, the bottom end of the first pipe 2 is lower than the design water level in front of the head dam 1.

[0021] Preferably, the first valve 7 is an air vent valve.

[0022] Preferably, the head dam 1 is a masonry gravity dam, and the wing wall 11 is located on the side of the masonry gravity dam where the water diversion channel is not located.

[0023] This utility model further provides a construction method for this utility model, which specifically includes the following steps: S1: A temporary cofferdam is set up at a certain distance upstream of the head dam 1. At the same time, the power station is started to reduce the water depth in front of the head dam 1. S2: Process the second pipe 3 and the vertical pipe 6, make a hole in the second pipe 3, and weld the vertical pipe 6 at the hole position. The vertical pipe 6 is set vertically, and the upper half of the vertical pipe 6 is equipped with a first valve 7. S3: Excavate at the location where the second pipe 3 is set on the top of the head dam 1. The excavation forms a trapezoidal cross section. Place the second pipe 3, which has been processed in S2, into the trench formed by the excavation of the head dam 1, and ensure that the vertical pipe 6 is set vertically. The first valve 7 is located above the top of the dam. S4: Connect the first pipe 2 to the second pipe 3. The second pipe 3 and the first pipe 2 are fixedly connected by a bend. The first pipe 2 is set vertically downward and is a certain distance below the top of the dam. S5: Connect the third pipe 4 to the second pipe 3. The second pipe 3 and the third pipe 4 are fixedly connected by a bend. The third pipe 4 is set horizontally and fixed to the head dam 1 by a U-shaped clamp 9. Bolt holes are provided at both ends of the U-shaped clamp 9. Fixing is achieved by passing the fixing bolt 91 through the bolt holes. S6: Backfill the excavated trench on the top of the head dam 1 with concrete and cure it to the design strength; S7: Connect the fourth pipe 5 to the third pipe 4. The fourth pipe 5 and the third pipe 4 are fixedly connected by a bend. The fourth pipe 5 is fixedly connected to the head dam 1 and the wing wall 11. The fourth pipe 5 is fixed to the head dam 1 and the wing wall 11 by a U-shaped clamp 9. The U-shaped clamp 9 has bolt holes at both ends. Fixing is achieved by passing a fixing bolt 91 through the bolt holes. S8: A second valve 8 is installed at the end of the fourth pipe 5; S9: Remove the temporary cofferdam and complete the construction of the ecological flow release device.

[0024] Preferably, a fixing device is provided on the water-facing surface of the first pipe 2 and the head dam 1 to fix the first pipe 2 and prevent the first pipe 2 from shifting during operation. The first pipe 2 can also be selected as an inclined pipe, which is set close to the water-facing surface of the head dam 1 and fixed with fasteners. When the first pipe section is a certain distance away from the water-facing surface of the head dam 1, the first pipe 2 can be fixed by erecting fixed anchor rods on the water-facing surface of the head dam 1. In step S1, it is necessary to first reduce the water depth in front of the head dam 1 to achieve a relatively dry working environment for the head dam 1. The method is to set up a temporary cofferdam upstream of the head dam 1 to prevent water from flowing in, and at the same time use the power station to divert water for power generation, and discharge the water in front of the head dam 1 into the downstream through the power station. Preferably, in step S6, the concrete is self-compacting concrete; using self-compacting concrete can improve the strength of the backfill concrete after excavation and reduce the complexity of construction. Preferably, the bottom end of the first pipe 2 is lower than the design water level in front of the head dam 1. The design water level in front of the head dam 1 is the normal operating water level in front of the dam when the power station is operating normally. It is mainly limited by the water intake of the power station's water diversion channel, such as the water intake gate. The design water level in front of the head dam 1 can be determined by the elevation of the bottom plate of the water intake gate. The fact that the bottom end of the first pipe 2 is lower than the design water level ensures that the ecological flow device can continuously discharge flow downstream under normal operating conditions in front of the dam, thereby ensuring the ecological flow requirements. Preferably, the materials of the first pipe 2, the second pipe 3, the third pipe 4, the fourth pipe 5, and the vertical pipe 6 can be steel or other metal materials; the materials of the first pipe 2, the second pipe 3, the third pipe 4, the fourth pipe 5, and the vertical pipe 6 should have a certain degree of corrosion resistance and be weldable to facilitate on-site installation and use. Preferably, the second valve 8 is a gate valve or a butterfly valve.

[0025] Preferably, the first valve 7 is a drain valve; by using the cooperation of the first valve 7 and the second valve 8, the siphon operation of the siphon pipe is realized, thereby using the discharge device of this utility model to release the ecological flow downstream of the headworks dam 1 and meet the functional requirements of regional ecological flow.

[0026] The above embodiments are merely preferred embodiments of the present utility model. The protection scope of the present utility model should not be considered as limited to the specific forms described in the embodiments. The protection scope of the present utility model also includes equivalent technical means that can be conceived by those skilled in the art based on the concept of the present utility model.

Claims

1. An ecological flow release device for the head dam of a run-of-river hydropower station, wherein the run-of-river hydropower station is a diversion-type power station, the head dam is located in the river channel, a water diversion channel is provided on one side of the head dam, the end of the water diversion channel is connected to a pressure forebay, and a wing wall is provided on the other side of the head dam, characterized in that: The ecological flow discharge device includes a first pipe, a second pipe, a third pipe, a fourth pipe, a fifth pipe, a first valve, and a second valve. The first pipe is located at the upstream end of the headworks dam, and its bottom end is a certain distance below the crest elevation of the headworks dam. The second pipe is located in the headworks dam, and the third pipe is located downstream of the headworks dam and is fixedly connected to it. The third pipe is horizontally positioned. The upper end of the fourth pipe is fixedly connected to the third pipe, and its lower end drains water downstream of the dam. The fourth pipe is fixedly connected to the headworks dam and the wing wall. The first, second, third, and fourth pipes are connected sequentially. A vertical pipe is installed on the second pipe, extending beyond the top of the headworks dam. A first valve is installed at the position where the vertical pipe extends beyond the top of the dam. A second valve is installed at the end of the fourth pipe. The third and fourth pipes are both fixed by a fixing device, which includes a U-shaped clamp and fixing bolts. The U-shaped clamp has bolt holes, and the fixing bolts pass through the bolt holes and are fixed to the headworks dam or the wing wall.

2. The ecological flow release device for the headworks dam of a run-of-river hydropower station as described in claim 1, characterized in that: The bottom of the first pipeline is lower than the design water level in front of the headworks dam.

3. The ecological flow release device for the headworks dam of a run-of-river hydropower station as described in claim 1, characterized in that: The first valve is a drain valve.

4. The ecological flow release device for the headworks dam of a run-of-river hydropower station as described in claim 1, characterized in that: The head dam is a masonry gravity dam, and the wing wall is located on the side of the masonry gravity dam where the water diversion channel is not located.

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