Water diversion method for raising water head of small river hydroelectric power station

Abstract

The application provides a water diversion method for lifting water head of a small river hydropower station, comprising a water diversion tunnel, a surge tank, a Y-shaped branch pipe and a stepped pressure shaft. The water diversion tunnel takes the water inlet of the hydropower station as a starting point and the surge tank as a terminal point. The surge tank is connected with the Y-shaped branch pipe, which changes one pipe of the water diversion tunnel into two pipes. The Y-shaped branch pipe is connected with two parallel arranged stepped pressure shafts. The two stepped pressure shafts are composed of four parallel arranged horizontal tunnels and three vertical shafts, and the terminal point is a water inlet ball valve of a unit plant. Through the water diversion method, the water head of the hydropower station can be significantly lifted to 845-922 m, and the reference flow can be increased by 2 times. Not only the water head loss is reduced, but also the power generation capacity is significantly improved, reaching the scale of a large hydropower station.

Description

Technical Field

[0001] This invention relates to the field of water conservancy and hydropower engineering technology, and in particular to a water diversion method for raising the head of a small river hydropower station. Background Technology

[0002] Rivers with a flow rate of less than 100 m³ / s are classified as small rivers. When constructing hydropower stations on small rivers, it is generally only suitable to build medium-sized hydropower stations with an installed capacity of less than 300 MW or small hydropower stations with an installed capacity of less than 50 MW.

[0003] Water head generally refers to the difference between the upstream and downstream water levels of a hydropower station. A high-head hydropower station is generally defined as one with a water head greater than 200 meters, while a water head greater than 250 meters is considered an ultra-high-head hydropower station. The power output and electricity generation of a high-head hydropower station generally depend on the upstream water flow.

[0004] When constructing hydropower stations on small mountain rivers with narrow channels and flow rates less than 100 m³ / s, the flow rate often limits the construction to small-scale hydropower stations. However, the electricity demands of production, business operations, and economic development necessitate raising the water head and increasing the flow rate through water diversion methods to achieve higher power generation. Therefore, developing a water diversion method that can raise the water head for small river hydropower stations is essential. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a water diversion method for raising the head of a small river hydropower station. This method significantly raises the head of the small river hydropower station while reducing head loss, doubling the diversion flow, and increasing power generation, thus achieving the scale of a large hydropower station.

[0006] According to an embodiment of the present invention, a water diversion method for raising the head of a small river hydropower station includes the following steps:

[0007] S1. Starting from the water intake of the hydropower station, a water diversion tunnel is arranged along the direction of the river. The first two-thirds of the tunnel is parallel to the river, and the last one-third is located at a bend in the river.

[0008] S2. A surge tank is vertically arranged at the end of the water diversion tunnel, and the bottom of the surge tank is connected to the tail end of the water diversion tunnel.

[0009] S3. Arrange a Y-shaped branch pipe at the bottom of the surge tank, and connect the main line of the Y-shaped branch pipe to the surge tank, with two branch lines leading out.

[0010] S4. Arrange cascade pressure shafts along the two branch pipelines, making the two cascade pressure shafts relatively parallel. Arrange horizontal tunnels and vertical shafts continuously within the cascade pressure shafts, and finally connect the inlet ball valves of the unit plant through the two cascade pressure shafts respectively.

[0011] Preferably, in S1, the water diversion tunnel is arranged with a total length of 18-24km, and 8-10 turns are set along the water diversion tunnel, with a turning radius between 30-2000m.

[0012] Preferably, in S1, when arranging the water diversion tunnel, the longitudinal slope of the water diversion tunnel along the water flow direction is set to be between 0.3% and 1.2%.

[0013] Preferably, in S1, the cross-section of the water diversion tunnel is constructed into an inner circle and an outer horseshoe shape, and after the water diversion tunnel is lined, the tunnel diameter reaches 6m.

[0014] Preferably, in S2, the height of the pressure regulating well is 200-280m, and the pressure regulating well is a single-chamber or double-chamber type.

[0015] Preferably, the pressure regulating well is provided with a vertical shaft, an upper chamber is provided at the top of the vertical shaft, both the upper chamber and the vertical shaft have circular cross sections, and a lower chamber in the shape of a city gate is arranged at the bottom of the vertical shaft, with the slope ratio of the top plate to the bottom plate of the lower chamber being 1-1.5%.

[0016] Preferably, the two stepped pressure shafts each include four sections of horizontal tunnels and three sections of shaft one, with each section of horizontal tunnel having a length of 60-440m and each section of shaft one having a height of 160-270m.

[0017] Preferably, the vertical shaft has a circular cross-section, the horizontal tunnel has a horseshoe-shaped cross-section, and the bottom slope of the horizontal tunnel is set to 8-13%.

[0018] Preferably, the bottom plate of the flat tunnel is 4.5m wide and the tunnel is 5.6m high.

[0019] Preferably, the shaft is lined with pressure steel pipes, and the pressure steel pipes are equipped with stiffening rings, with an inner diameter of 3.5m.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] In small river hydropower station projects in mountainous areas with an average flow rate of less than 100 m3 / s, this invention has advantages such as significantly raising the water head to more than 800 m, increasing the diversion flow by 2 times, and reducing water head loss. It can also significantly increase power generation, making the total installed capacity of the hydropower station greater than 800 MW, reaching the scale of a large hydropower station. Attached Figure Description

[0022] Figure 1 This is a side view of the structural arrangement of the present invention.

[0023] Figure 2 This is a cross-sectional view of the water diversion tunnel of the present invention.

[0024] Figure 3 This is a cross-sectional view of the pressure regulating well of the present invention.

[0025] Attached reference numerals: 1. Inlet; 2. Water diversion tunnel; 3. Surge well; 31. Upper chamber; 32. Shaft II; 33. Lower chamber; 4. Y-shaped branch pipe; 5. Cascade pressure shaft; 501. First-stage left horizontal tunnel; 502. First-stage right horizontal tunnel; 503. Upper left vertical shaft; 504. Upper right vertical shaft; 505. Second-stage left horizontal tunnel; 506. Second-stage right horizontal tunnel; 507. Middle left vertical shaft; 508. Middle right vertical shaft; 509. Third-stage left horizontal tunnel; 510. Third-stage right horizontal tunnel; 511. Lower left vertical shaft; 512. Lower right vertical shaft; 513. Fourth-stage left horizontal tunnel; 514. Fourth-stage right horizontal tunnel; 6. Unit building. Detailed Implementation

[0026] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] See Figure 1 A method for raising the water head in a small river hydropower station includes a water diversion tunnel 2, a surge tank 3, a Y-shaped branch pipe 4, and two cascade pressure shafts 5. The water diversion tunnel 2 starts at the hydropower station intake 1 and ends at the surge tank 3.

[0028] Furthermore, the first two-thirds of the water diversion tunnel 2 is arranged along the river channel, with its direction roughly parallel to the river channel, while the last one-third of the water diversion tunnel 2 is arranged at the bend of the river.

[0029] The water diversion tunnel 2 is designed with a longitudinal slope along the direction of water flow, so that there is a certain height difference between the starting point and the ending point of the water diversion tunnel 2.

[0030] The pressure regulating well 3 is followed by a Y-shaped branch pipe 4, which transforms one pipe into two pipes. The Y-shaped branch pipe 4 is followed by two parallel stepped pressure vertical shafts 5.

[0031] The endpoints of the two cascade pressure shafts 5 are the inlet ball valves of the unit plant 6.

[0032] A surge tank 3 is installed at the end of the water diversion tunnel 2 to release water hammer and reduce water hammer wave pressure.

[0033] For details, see Figure 1 The water diversion tunnel 2 is 18-24km long, with 8-10 turning points along the route and turning radii ranging from 30-2000m.

[0034] Specifically, the longitudinal slope of the water diversion tunnel 2 is set between 0.3% and 1.2%, so that the elevation difference between the starting point and the ending point of the water diversion tunnel 2 is 150-180m.

[0035] For details, see Figure 2 The water diversion tunnel 2 has a cross-sectional shape of an inner circle and an outer horseshoe shape, and is lined with reinforced concrete throughout. Furthermore, when the tunnel diameter after lining is 6m, it can meet the optimal economic flow velocity of 4.5m / s.

[0036] See Figure 1 A surge tank 3 is installed at the end of the water diversion tunnel 2, and the surge tank 3 has a height of 264m.

[0037] Further, see Figure 3 The surge tank 3 is equipped with an upper chamber 31, a second vertical shaft 32, and a lower chamber 33. The upper chamber 31 has a circular cross-section, with an inner diameter of 18m and a height of 30m after lining. The second vertical shaft 32 has a circular cross-section, with an inner diameter of 5.5m and a height of 234m after lining. The lower chamber 33 is one or two 100m long arch-shaped tunnels, 4.5m wide and 4.25-6.75m high, with a bottom slope of 1.0% inclined towards the vertical shaft and a top slope of 1.5% inclined towards the vertical shaft.

[0038] Furthermore, the surge tank 3 is lined with reinforced concrete and reinforced with consolidation grouting.

[0039] See Figure 1 The two stepped pressure shafts 5 are arranged in parallel, starting from the Y-shaped branch pipe 4 and ending at the inlet ball valve of the unit plant 6.

[0040] Specifically, the two stepped pressure shafts 5 each contain three parallel vertical shaft sections and four horizontal tunnel sections, which are arranged sequentially along the water flow direction as follows: Level 1 left horizontal tunnel 501, Level 1 right horizontal tunnel 502, Upper left vertical shaft 503, Upper right vertical shaft 504, Level 2 left horizontal tunnel 505, Level 2 right horizontal tunnel 506, Middle left vertical shaft 507, Middle right vertical shaft 508, Level 3 left horizontal tunnel 509, Level 3 right horizontal tunnel 510, Lower left vertical shaft 511, Lower right vertical shaft 512, Level 4 left horizontal tunnel 513, and Level 4 right horizontal tunnel 514.

[0041] Specifically, the two stepped pressure shafts 5 have a circular cross-section and are lined with pressure steel pipes. The pressure steel pipes are reinforced with stiffening rings, and the inner diameter after lining is 3.5m.

[0042] Specifically, the horizontal tunnel cross-section of the two stepped pressure shafts 5 is horseshoe-shaped with a slope ratio of 10%, and is lined with reinforced concrete. After lining, the bottom slab is 4.5m wide and the tunnel is 5.6m high.

[0043] Specifically, the first-level horizontal tunnel is 300-340m long, the second-level horizontal tunnel is 320-360m long, the third-level horizontal tunnel is 400-440m long, and the fourth-level horizontal tunnel is 60-110m long.

[0044] Specifically, the upper shaft is 180-220m deep, the middle shaft is 160-200m deep, and the lower shaft is 230-270m deep.

[0045] The working process and principle of the water diversion method constructed using this method are illustrated through a specific engineering example:

[0046] A hydroelectric power station in Pakistan is located on the Kunhar River, a first-order tributary in a mountainous and canyonous region. The river's runoff is primarily generated from snowmelt, resulting in a relatively scarce source of water. The average annual flow at the dam site is 60.3 m³ / s, classifying it as a small river. To meet power generation demands, a method for raising the water head of this small-river hydroelectric power station is employed. This involves combining a water diversion tunnel (2) with two cascade pressure shafts (5) to increase the water head, achieving an operating head range of 845-922 m and doubling the diversion flow to 114-126 m³ / s. This results in an installed capacity of 884 MW and an annual power generation of 3212 GWh, reaching the scale of a large-scale hydroelectric power station. After completion, the power station will supply electricity to the Pakistani grid, effectively alleviating the severe power shortage in the region and promoting local economic development.

[0047] In summary, a water diversion method for raising the head of a small river hydropower station combines a water diversion tunnel with a cascade pressure shaft. This method can significantly raise the head, reduce head loss, increase diversion flow, and improve power generation, ensuring the long-term economic benefits of the power station.

Claims

1. A water diversion method for raising the head of a small river hydropower station, characterized in that, Includes the following steps: S1. Starting from the water intake (1) of the hydropower station, a water diversion tunnel (2) is arranged along the direction of the river. The first 2 / 3 of the tunnel line of the water diversion tunnel (2) is arranged parallel to the river, and the last 1 / 3 of the tunnel line is located at the bend of the river. S2. A surge tank (3) is vertically arranged at the end of the water diversion tunnel (2), and the bottom end of the surge tank (3) is connected to the tail end of the water diversion tunnel (2). S3. Arrange a Y-shaped branch pipe (4) at the bottom of the pressure regulating well (3), and make the main pipeline of the Y-shaped branch pipe (4) connected to the pressure regulating well (3), and lead out two branch pipelines; S4. Arrange the cascade pressure shafts (5) along the two branch pipelines respectively, and make the two cascade pressure shafts (5) relatively parallel. Arrange the horizontal tunnel and the vertical shaft one continuously in the cascade pressure shaft (5), and finally connect the water inlet ball valve of the unit plant (6) through the two cascade pressure shafts (5). In S1, the water diversion tunnel (2) with a total length of 18-24km is arranged, and 8-10 turns are set along the water diversion tunnel (2), with a turning radius between 30-2000m; The two stepped pressure shafts (5) each contain four sections of the horizontal tunnel and three sections of the vertical shaft, and the length of each section of the horizontal tunnel is 60-440m, and the height of each section of the vertical shaft is 160-270m. The vertical shaft has a circular cross-section, the horizontal tunnel has a horseshoe-shaped cross-section, and the bottom slope of the horizontal tunnel is set to 8-13%. The bottom slab of the tunnel is 4.5m wide and the tunnel is 5.6m high; The shaft is lined with pressure steel pipes, and the pressure steel pipes are reinforced with stiffening rings. The inner diameter of the pressure steel pipes is 3.5m.

2. The water diversion method for raising the head of a small river hydropower station as described in claim 1, characterized in that: In S1, when arranging the water diversion tunnel (2), the longitudinal slope of the water diversion tunnel (2) along the water flow direction is set to be between 0.3% and 1.2%.

3. The water diversion method for raising the head of a small river hydropower station as described in claim 1, characterized in that: In S1, the cross-section of the water diversion tunnel (2) is constructed into an inner circle and an outer horseshoe shape, and after the water diversion tunnel (2) is lined, the tunnel diameter reaches 6m.

4. The water diversion method for raising the head of a small river hydropower station as described in claim 1, characterized in that: In S2, the height of the pressure regulating well (3) is 200-280m, and the pressure regulating well (3) is a single-chamber or double-chamber type.

5. The water diversion method for raising the head of a small river hydropower station as described in claim 4, characterized in that: The pressure regulating well (3) is equipped with a second vertical shaft (32). An upper chamber (31) is set at the top of the second vertical shaft (32). Both the upper chamber (31) and the second vertical shaft (32) have circular cross sections. A lower chamber (33) in the shape of a city gate is arranged at the bottom of the second vertical shaft (32). The slope ratio between the top plate and the bottom plate of the lower chamber (33) is 1-1.5%.

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