A high-energy water power station water delivery system elbow pipe sand discharging device and a sand discharging method thereof

Abstract

The present application relates to a kind of water power station elbow pipe sand discharge device, especially about a kind of water power station high kinetic energy water delivery system elbow pipe sand discharge device and sand discharge method thereof, inlet section, inlet rectifier section, centrifugal enrichment elbow pipe section, water outlet section are sequentially communicated;Centrifugal enrichment elbow pipe section outer side wall is communicated with the inlet of cyclone intensification chamber, the top of cyclone intensification chamber is communicated with inlet section by backflow pipeline assembly, bottom is connected to sand discharge pool by sand discharge assembly;Backflow pipeline assembly communicates cyclone intensification chamber and inlet section;With the electric proportional sand discharge valve of weighing strain gauge is installed in the bottom of cyclone intensification chamber;Flow rate and sand content integrated sensor is installed in the junction of centrifugal enrichment elbow pipe section and cyclone intensification chamber, PLC controller is electrically connected with flow rate and sand content integrated sensor, electric proportional sand discharge valve with weighing strain gauge respectively, realize signal feedback and automatic control.The present application improves water energy resource utilization efficiency, reduces the abrasion of silt to water turbine flow component.

Description

Technical Field

[0001] This invention relates to a hydropower station bend pipe sand removal device, and particularly to a bend pipe sand removal device and sand removal method for a high-energy water conveyance system of a hydropower station. It is mainly applicable to the field of sand removal in hydropower station water conveyance systems, and is especially suitable for water conveyance scenarios with high flow velocity, high sand content, and short curvature bends, such as high-head flood discharge pipelines, high-speed water conveyance pipelines, and pump station pressure bends. Technical Background

[0002] Currently, there are two main methods for dealing with rivers with high sediment content. One is to shut down the generators and allow the sediment to be discharged, and the other is to let the sediment-laden water flow through the generators to generate electricity.

[0003] While using a shutdown-and-open-drainage method for sediment discharge can effectively avoid wear and tear on the turbines, the direct discharge of water and cessation of power generation result in low hydropower resource utilization efficiency. Although high-sediment-content water flowing through turbines can effectively utilize hydropower resources, it causes severe erosion of turbine components, leading to a significant increase in maintenance frequency, resulting in substantial increases in maintenance costs and downtime losses. Therefore, hydropower stations have long faced the challenge of balancing sediment discharge to maintain reservoir capacity with power generation and reduced wear and tear.

[0004] To avoid the aforementioned problems, power stations can also address them by installing sedimentation basins. For example, in diversion-type hydropower stations with high river sediment content, sedimentation basins must be built at the inlet of the diversion canal. However, this not only wastes water resources, but also requires a large investment in sedimentation basins. Some projects, due to high sediment content, do not meet the conditions for building sedimentation basins and must use regulating reservoirs to settle sediment. However, when regulating reservoirs discharge sediment, the hydropower station cannot operate, which also affects power generation efficiency.

[0005] Conventional bend-type sediment removal (suitable for natural rivers / low-velocity channels) operates at a flow velocity <3m / s, resulting in stable flow. Sediment transport and distribution are primarily driven by lateral circulation, combined with flow inertia and sediment gravity settling characteristics. Surface water containing a large amount of fine suspended sediment deflects towards the concave bank (outer side) of the bend. To maintain flow continuity, bottom water containing bed sand (coarse sediment) flows from the convex bank (inner side) to the concave bank. Because the bottom water velocity is much lower than the surface water, its sediment-carrying capacity is weak, and the sediment density is greater than that of the water. Under gravity, most of the coarse sediment cannot be carried long distances by the bottom water flow and will accumulate on the slower-flowing convex bank (inner side). Therefore, conventional bend-type sediment removal can only handle a portion of the coarse sediment and cannot solve the problem of fine suspended sediment. Fine suspended sediment will still cause adverse effects on hydropower stations, such as equipment erosion and reduced power generation efficiency. Summary of the Invention

[0006] In high-velocity water conveyance systems such as artificial spillways and steep bends, the water flow velocity is much greater than the conventional velocity of natural rivers, classifying them as high-energy water conveyance systems. When the sediment is primarily fine-grained suspended sand with extremely high sediment content, the water flow passing through short, highly curved bends causes the sediment, due to its higher density than water, to move outwards under centrifugal force. This results in clear water on the inside of the bend and a higher concentration of sediment on the outside. This invention leverages this characteristic to design a bend-pipe sediment removal device and method for high-energy water conveyance systems in hydropower stations. This method eliminates the need for expensive sedimentation tanks; sediment removal can be achieved simply by utilizing bends in the water conveyance pipeline or the curved water flow within the turbine casing. This significantly reduces project investment costs, improves hydropower resource utilization efficiency, and reduces wear and tear on turbine components caused by sediment.

[0007] A high-energy water conveyance system for a hydropower station includes a bend-pipe sand discharge device, comprising an inlet section, an inlet rectifying section, a centrifugal enrichment bend-pipe section, a vortex enhancement chamber, a return pipeline assembly, a sand discharge assembly, a detection and control assembly, and an outlet section.

[0008] The inlet section, the inlet rectifier section, the centrifugal enrichment bend section, and the outlet section are connected in sequence; the outer wall of the centrifugal enrichment bend section is connected to the inlet of the cyclone enhancement chamber, the top of the cyclone enhancement chamber is connected to the inlet section through the return pipeline assembly, and the bottom is connected to the sand discharge tank through the sand discharge assembly.

[0009] The return pipeline assembly includes a first return branch pipe, a first shut-off valve, a second return branch pipe, a second shut-off valve, and a third return branch pipe connected in series. The return pipeline assembly connects the vortex enhancement chamber and the water inlet section.

[0010] The sand discharge assembly includes an electric proportional sand discharge valve with a weighing strain gauge and a sand discharge pipe; the electric proportional sand discharge valve with a weighing strain gauge is installed at the bottom of the vortex enhancement chamber, the valve opening can be continuously adjusted, and the weight of the discharged sand can be detected in real time.

[0011] The detection and control components include an integrated sensor for flow velocity and sand content, an electric proportional sand discharge valve with a weighing strain gauge, and a PLC controller. The integrated sensor for flow velocity and sand content is installed at the junction of the centrifugal enrichment bend and the cyclone enhancement chamber. The PLC controller is electrically connected to the integrated sensor for flow velocity and sand content and the electric proportional sand discharge valve with a weighing strain gauge to realize signal feedback and automatic control.

[0012] The ratio of the radius of curvature R of the centrifugal enrichment bend to the inner diameter D of the pipe is 1.5 to 3, which is used to suppress lateral circulation and cause sediment to accumulate on the outside of the bend.

[0013] The inlet rectifier section is equipped with 3 to 4 evenly distributed rectifier blades, with the blades forming an angle of 15° to 30° with the water flow direction.

[0014] The swirl enhancement cavity has a conical cavity structure with a spiral guide groove on its inner wall.

[0015] The inner wall of the centrifugal enrichment bend section is coated with a wear-resistant ceramic coating with a thickness of ≥3mm; the center angle of the bend is 90°~120°.

[0016] The main function of a high-energy water conveyance system for a hydropower station with a curved pipe for sand removal is to allow high-energy sand-laden water to flow through the inlet section and the inlet rectification section to form a stable flow state before entering the centrifugal enrichment curved pipe section. Under the strong centrifugal force, the suspended sand gathers on the outside of the curved pipe (concave bank). The high-concentration sediment gathered on the outside enters the vortex enhancement chamber with part of the water flow. The vortex further separates the sediment. The separated clear water flows upward through the third return branch pipe, the second stop valve, the second return branch pipe, the first stop valve, and the first return branch pipe back to the inlet section. The separated sediment flows downward through the electric proportional sand removal valve with a weighing strain gauge and the sand removal pipe to settle into the sand removal pool. The clear water near the inside of the curved pipe (convex bank) flows through the outlet section to the hydropower station generator unit for power generation.

[0017] A method for removing sediment from a bend in a high-energy water conveyance system of a hydropower station includes the following steps:

[0018] (1) High-energy sediment-laden water flows through the inlet section and enters the inlet rectification section, where it is rectified to form a stable flow pattern;

[0019] (2) When the stable water flow enters the centrifugal enrichment bend section, the sediment is enriched to the outside of the bend under the action of strong centrifugal force.

[0020] (3) The high-concentration sediment water flows into the vortex enhancement chamber. After vortex separation, the clear water flows back to the inlet section (1), and the sediment is discharged to the sediment discharge pool through the sediment discharge component.

[0021] (4) The sand content and sand discharge volume of the water flow are detected in real time by the detection and control components, and the sand discharge valve opening is automatically adjusted to balance the power generation efficiency and sand discharge effect.

[0022] The beneficial effects of the technical solution of this invention are as follows:

[0023] (1) Significantly reduce project investment: There is no need to build large structures such as sedimentation basins and storage tanks. Sand discharge can be achieved by simply using the existing bends in the water conveyance system or by adding dedicated bends, which reduces the project construction cost by 60% to 80%.

[0024] (2) Improve hydropower utilization efficiency: avoid power generation interruption caused by shutdown for sediment discharge, realize simultaneous sediment discharge and power generation, improve hydropower resource utilization efficiency by more than 30%, especially suitable for continuous operation of hydropower stations in rivers with high sediment content;

[0025] (3) Significantly reduce equipment wear: Through centrifugal + cyclone composite separation technology, fine particulate suspended sand is effectively removed (separation efficiency ≥90%), the degree of erosion of turbine flow parts is reduced by more than 70%, the unit maintenance cycle is extended by 2 to 3 times, and maintenance costs are reduced by 50% to 60%;

[0026] (4) Energy saving and stable operation: The separation process is driven by the kinetic energy of the water flow itself, without the need for additional power, and the energy consumption is close to zero; PLC automatic control is adopted, which can adjust the amount of sand discharged in real time according to the sand content, adapt to different sand content water flow conditions, and has high operational reliability.

[0027] (5) Water resource recycling: The separated clean water is reintroduced into the water intake section through the return pipeline to avoid water waste, which is especially suitable for hydropower stations in water-scarce areas;

[0028] (6) Wide adaptability: It is designed for high flow velocity, high sand content and short curvature bends. It can be widely used in various high-energy water conveyance scenarios such as high head flood discharge pipelines, high-speed water conveyance pipelines, and pump station pressure bends. It is flexible in installation and does not require major modification of the original water conveyance system. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the device structure of the present invention;

[0030] Figure 2 This is a cross-sectional structural diagram of the device of the present invention. Detailed Implementation

[0031] The main function of the high-energy water conveyance system bend pipe sand discharge device of the hydropower station involved in this invention is to allow high-energy sand-laden water to flow through the inlet section 1 and the inlet rectification section 4 to form a stable flow state before entering the centrifugal enrichment bend pipe section 7. Under the strong centrifugal force, the suspended sand gathers on the outside of the bend pipe (concave bank). The high-concentration silt gathered on the outside enters the vortex strengthening chamber 16 with part of the water flow. The vortex further separates the silt. The separated clear water flows upward through the third return branch pipe 11, the second stop valve 10, the second return branch pipe 5, the first stop valve 3, and the first return branch pipe 2 back to the inlet section 1. The separated silt flows downward through the electric proportional sand discharge valve 12 with a weighing strain gauge and the sand discharge pipe 14 to settle into the sand discharge pool 15. The clear water near the inside of the bend pipe (convex bank) flows through the outlet section 18 to the hydropower station generator unit for power generation.

[0032] 1. Device Composition

[0033] This device mainly consists of an inlet section 1, a first return branch pipe 2, a first shut-off valve 3, an inlet rectifier section 4, a second return branch pipe 5, a first fixed support 6, a centrifugal enrichment bend section 7, a second fixed support 8, an integrated sensor for flow velocity and sediment content 9, a second shut-off valve 10, a third return branch pipe 11, an electric proportional sand discharge valve with a weighing strain gauge 12, a PLC controller 13, a sand discharge pipe 14, a sand discharge tank 15, a vortex enhancement chamber 16, a third fixed support 17, and an outlet section 18. The connection relationships of each component are as follows:

[0034] One end of the inlet section 1 is connected to a high-energy sediment-laden water pipe, and the other end is fixedly connected to the front end of the inlet rectifying section 4;

[0035] The rear end of the inlet rectifier section 4 is fixedly connected to the inlet end of the centrifugal enrichment bend section 7, and the front end of the centrifugal enrichment bend section 7 is fixed to the installation foundation by the first fixed bracket 6.

[0036] A connecting port is opened on the outer wall of the centrifugal enrichment bend section 7, which is connected to the inlet end of the cyclone enhancement chamber 16 by welding to form an integrated component. The cyclone enhancement chamber 16 is fixed to the installation base by the second fixed bracket 8.

[0037] The top outlet of the swirl enhancement chamber 16 is connected to one end of the third return branch pipe 11 by welding, and the bottom outlet is sealed to the inlet end of the electric proportional sand discharge valve 12 with a weighing strain gauge. The rear end of the centrifugal enrichment bend section 7 is fixed to the installation foundation by the third fixed bracket 17.

[0038] The other end of the third return branch pipe 11 is connected to the inlet end of the second shut-off valve 10. The outlet end of the second shut-off valve 10 is connected to one end of the second return branch pipe 5. The other end of the second return branch pipe 5 is connected to the inlet end of the first shut-off valve 3. The outlet end of the first shut-off valve 3 is connected to one end of the first return branch pipe 2. The other end of the first return branch pipe 2 is connected to the water inlet section 1 by welding.

[0039] The outlet end of the electric proportional sand discharge valve 12 with a weighing strain gauge is connected to one end of the sand discharge pipe 14, and the other end of the sand discharge pipe 14 extends into the sand discharge pool 15.

[0040] The outlet end of the centrifugal enrichment bend section 7 is fixedly connected to one end of the water outlet section 18, and the other end of the water outlet section 18 is connected to the water inlet pipe of the hydropower station generator unit.

[0041] A combined flow velocity and sediment concentration sensor 9 is installed at the junction of the centrifugal enrichment bend section 7 and the vortex enhancement chamber 16 to detect the water flow velocity and sediment concentration in real time.

[0042] The PLC controller 13 is electrically connected to the integrated flow velocity and sand content sensor 9 and the electric proportional sand discharge valve 12 with a weighing strain gauge, respectively, to realize signal transmission and automatic control.

[0043] 2. Core Technology Principles

[0044] This device is based on the composite principle of "centrifugal inertia-cyclone enhancement" and is specifically designed for high-velocity (velocity ≥ 5 m / s), high-sediment (sediment content ≥ 30 kg / m³), and short-curvature (curvature radius to pipe diameter ratio ≤ 3) bends in high-head flood discharge pipelines, high-speed water conveyance pipelines, and pump station pressure bends.

[0045] Centrifugal inertial separation: By using the short curvature design of the centrifugal enrichment bend section 7, combined with the high flow velocity of the high-energy water conveyance system, the transverse circulation that dominates sediment transport in conventional bends is suppressed, reducing the sediment transport phenomenon from the bottom water flow to the convex bank. The strong centrifugal force is used to enrich sediment (especially fine suspended sediment) to the outside of the bend (concave bank), thus achieving preliminary separation of water and sediment.

[0046] Cyclone-enhanced separation: The high-concentration sediment-rich water flow on the outside of the bend enters the cyclone-enhanced chamber 16. Under the action of the cyclone field, the sediment particles are further settled by centrifugal force, while the clear water flows upward, achieving deep separation of water and sediment.

[0047] No additional power required: The entire process utilizes the kinetic energy of the water flow itself to achieve centrifugal and swirling separation, eliminating the need for additional power equipment such as motors and pumps, resulting in energy savings and stable operation.

[0048] 3. Design parameters of key components

[0049] Centrifugal enrichment bend section 7: The ratio of the bend curvature radius R to the pipe inner diameter D is 1.5 to 3, the bend center angle is 90° to 120°, and the inner wall of the pipe is coated with a wear-resistant ceramic coating with a thickness ≥3mm to ensure wear resistance under the impact of high-velocity sand-containing water flow.

[0050] Inlet rectifier section 4: The length is 3 to 5 times the inner diameter of the pipe. It is equipped with 3 to 4 evenly distributed rectifier blades. The angle between the blades and the water flow direction is 15° to 30°. It is used to eliminate water flow turbulence and form a stable flow state.

[0051] Swirl Enhancement Cavity 16: It adopts a conical cavity structure, with a cylindrical cavity at the top (height is 2 to 3 times the inner diameter) and a conical cavity at the bottom (cone angle is 60° to 90°). The inner wall of the cavity is provided with a spiral guide groove, and the lead-to-inner diameter ratio is 2 to 4 to enhance the swirling intensity.

[0052] Electric proportional sand discharge valve 12 with weighing strain gauge: The valve opening can be continuously adjusted within the range of 0 to 100%. The measurement accuracy of the weighing strain gauge is ≤ ±0.5%. It can detect the weight of mud and sand passing through the valve in real time and feed it back to the PLC controller to achieve precise control of the sand discharge volume.

[0053] 4. Work Process

[0054] Start-up preparation: Check the sealing and fixing reliability of each component connection, and set the water flow velocity threshold, sand content threshold and sand discharge threshold through PLC controller 13;

[0055] Water flow introduction: High-energy sediment-laden water flows through the inlet section 1 and enters the inlet rectification section 4. After the turbulence is eliminated by the rectification blades and a stable flow is formed, it flows into the centrifugal enrichment bend section 7.

[0056] Centrifugal enrichment: The water flows at high speed in the centrifugal enrichment bend section 7, generating strong centrifugal force. The sediment (including fine suspended sand) gathers to the outside of the bend, and a clear water flow with low sediment content is formed on the inside of the bend.

[0057] Diversion treatment: The high-concentration sediment water flow on the outside enters the vortex enhancement chamber 16 through the connecting port, while the clear water flow on the inside continues to flow towards the outlet section 18 and flows towards the generator set.

[0058] Cyclone separation: High-concentration sediment water flows along the spiral guide groove in the cyclone enhancement chamber 16. The sediment particles settle towards the chamber wall under the action of centrifugal force and collect at the bottom of the chamber, while the clear water flows upward.

[0059] Clear water return: The clear water after hydrocyclone separation returns to the water inlet section 1 through the third return branch pipe 11, the second stop valve 10, the second return branch pipe 5, the first stop valve 3, and the first return branch pipe 2, so as to realize the recycling of water resources;

[0060] Sediment discharge: The electric proportional sand discharge valve 12 with a weighing strain gauge adjusts the valve opening according to the instruction of the PLC controller 13, and discharges the sediment collected at the bottom through the sand discharge pipe 14 to the sand discharge pool 15 for sedimentation.

[0061] Automatic control: A sensor 9 integrating flow velocity and sediment concentration is used to detect the water flow velocity and sediment concentration at the junction of the centrifugal enrichment bend section 7 and the vortex enhancement chamber 16 in real time. An electric proportional sediment discharge valve 12 with a weighing strain gauge detects the weight of the discharged sediment in real time, and the data is fed back to the PLC controller 13. When the sediment concentration exceeds the set threshold, the PLC controller 13 increases the opening of the sediment discharge valve to increase sediment discharge. When the sediment concentration is lower than the set threshold, the opening of the sediment discharge valve is reduced to ensure a balance between power generation efficiency and sediment discharge effect.

Claims

1. A bent-pipe sand removal device for a high-energy water conveyance system in a hydropower station, characterized in that, It includes the inlet section (1), the inlet rectification section (4), the centrifugal enrichment bend section (7), the vortex enhancement chamber (16), the return pipeline assembly, the sand discharge assembly, the detection and control assembly, and the outlet section (18). The inlet section (1), the inlet rectifier section (4), the centrifugal enrichment bend section (7), and the outlet section (18) are connected in sequence; the outer wall of the centrifugal enrichment bend section (7) is connected to the inlet of the vortex enhancement chamber (16), the top of the vortex enhancement chamber (16) is connected to the inlet section (1) through the return pipe assembly, and the bottom is connected to the sand discharge tank (15) through the sand discharge assembly. The return pipeline assembly includes a first return branch pipe (2), a first shut-off valve (3), a second return branch pipe (5), a second shut-off valve (10), and a third return branch pipe (11) connected in series. The return pipeline assembly connects the vortex enhancement chamber (16) and the water inlet section (1). The sand discharge assembly includes an electric proportional sand discharge valve (12) with a weighing strain gauge and a sand discharge pipe (14); the electric proportional sand discharge valve (12) with a weighing strain gauge is installed at the bottom of the vortex enhancement chamber (16), the valve opening can be continuously adjusted, and the sand discharge weight can be detected in real time. The detection and control components include an integrated sensor (9) for flow velocity and sand content, an electric proportional sand discharge valve (12) with a weighing strain gauge, and a PLC controller (13). The integrated sensor (9) for flow velocity and sand content is installed at the junction of the centrifugal enrichment bend section (7) and the cyclone strengthening chamber (16). The PLC controller (13) is electrically connected to the integrated sensor (9) for flow velocity and sand content and the electric proportional sand discharge valve (12) with a weighing strain gauge, respectively, to realize signal feedback and automatic control. The ratio of the radius of curvature R of the centrifugal enrichment bend (7) to the inner diameter D of the pipe is 1.5 to 3, which is used to suppress transverse circulation and make the sediment enriched on the outside of the bend. The inlet rectifying section (4) is provided with 3 to 4 evenly distributed rectifying blades, with the blades forming an angle of 15° to 30° with the direction of water flow. The swirl enhancement cavity (16) is a conical cavity structure with a spiral guide groove on the inner wall; The inner wall of the centrifugal enrichment bend (7) is provided with a wear-resistant ceramic coating with a thickness of ≥3mm; the center angle of the bend is 90°~120°.

2. A method for removing sediment from a bent pipe in a high-energy water conveyance system of a hydropower station, characterized in that, The bend-pipe sand removal device for a high-energy water conveyance system in a hydropower station as described in claim 1 is characterized by comprising the following steps: (1) High-energy sediment-laden water flows through the inlet section (1) and enters the inlet rectification section (4), where it is rectified to form a stable flow pattern; (2) Stable water flow enters the centrifugal enrichment bend section (7), and under the action of strong centrifugal force, sediment is enriched on the outside of the bend. (3) The high-concentration sediment water flows into the vortex enhancement chamber (16) and after vortex separation, the clear water flows back to the inlet section (1), and the sediment is discharged to the sediment discharge pool (15) through the sediment discharge component. (4) The sand content and sand discharge volume of the water flow are detected in real time by the detection and control components, and the sand discharge valve opening is automatically adjusted to balance the power generation efficiency and sand discharge effect.

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