US-12618213-B2 - Smooth automatic device and method for reservoir sediment flushing

US12618213B2US 12618213 B2US12618213 B2US 12618213B2US-12618213-B2

Abstract

This invention reveals a smooth automatic device and method for efficiently flushing sediment from a reservoir. It includes a sediment flushing funnel located at the reservoir dam's bottom, connected to a sediment flushing pipe. This pipe extends from the funnel's bottom through a smooth connecting pipe, horizontally through the dam, and then to the downstream river channel. Inside the funnel, a trigger-control mechanism is installed, linked to a sediment flushing ball valve within the sediment flushing pipe. The invention operates by automatically opening the ball valve when sediment accumulation in the funnel hits a preset threshold. The sediment is then released into the downstream river channel via the smooth connecting pipe and flushing pipe, driven by gravity. This system offers an effective solution for automatic reservoir sediment flushing, boasting high efficiency, energy conservation, and water resource savings.

Inventors

Yizhi SUN
Zhilin SUN
Hehe ZHU

Assignees

ZHEJIANG UNIVERSITY

Dates

Publication Date: 20260505
Application Date: 20240123
Priority Date: 20230214

Claims (8)

1 . A smooth automatic device for reservoir sediment flushing, comprising a sediment flushing funnel set at bottom of a reservoir dam and a sediment flushing pipe, one end of the sediment flushing pipe is smoothly connected to bottom of the sediment flushing funnel through a smooth connecting pipe, and an other end of the sediment flushing pipe is horizontally connected to a downstream river channel after passing through the reservoir dam; a trigger-control mechanism is installed inside the sediment flushing funnel, and a sediment flushing ball valve connected with the trigger-control mechanism is installed inside the sediment flushing pipe; wherein the trigger-control mechanism comprises: a vertical pipe set on an inner wall of the sediment flushing funnel, and an upper piston assembly and a lower piston assembly set inside the vertical pipe, capable of vertically sliding; the lower piston assembly is connected to top of a connecting rod, bottom of the connecting rod passes through the vertical pipe and is connected eccentrically with a first transmission gear, the first transmission gear and a second transmission gear are meshed, and the second transmission gear is linked to the sediment flushing ball valve; bottom of the vertical pipe is connected with bottom of a clean-water pipe, and top of the clean-water pipe is located in a clean-water area of a reservoir; and a height of top of the vertical pipe is lower than a height of top of the sediment flushing funnel; wherein the upper piston assembly comprises: an upper piston body and an upper spring arranged between the upper piston body and the inner wall of the sediment flushing funnel; a sealing ring is arranged between the upper piston body and an inner wall of the vertical pipe, and the sealing ring is used to keep sediment above the upper piston body separate from clean water below the upper piston body, so that a pressure difference of the upper piston body is equal to an underwater weight of the sediment; the lower piston assembly comprises: a lower piston body set below the upper piston body and a lower spring located between the lower piston body and the inner wall of the sediment flushing funnel; and the upper spring is inserted into the lower spring after passing through a center of the lower piston body.
2 . The smooth automatic device for reservoir sediment flushing according to claim 1 , wherein a transmission ratio I R of the first transmission gear and the second transmission gear is determined by following formula: I R = 2 π ⁢ arc ⁢ cos [ h 2 - 2 ⁢ L ⁢ h 2 ⁢ r ⁡ ( L + r - h ) + 1 ] wherein, h is a set height of the lower piston body, L is a length of the connecting rod, r is a distance from the connecting rod to a center of the first transmission gear, z 1 is a number of teeth of the first transmission gear, and z 2 is a number of teeth of the second transmission gear; when the lower piston body slides downward in the vertical pipe for a distance h to the bottom of the vertical pipe, the first transmission gear is driven to rotate an angle α, and a gear transmission ratio is I R = 2 ⁢ α π , so that a rotation angle of the sediment flushing ball valve is equal to π/2 or 90°; when the lower piston body slides downward in the vertical pipe for the distance h to the bottom of the vertical pipe, the first transmission gear is driven to rotate an angle α 1 , wherein a relation among α 1 , a sliding height h that the lower piston body slides, the length L of the connecting rod, and the distance r from the connecting rod to the center of the first transmission gear is expressed as cos ⁢ α 1 = r 2 + ( L + r - h ) 2 - L 2 2 ⁢ r ⁡ ( L + r - h ) = h 2 - 2 ⁢ L ⁢ h 2 ⁢ r ⁡ ( L + r - h ) + 1 from which a new formula is derived: α 1 = arc ⁢ cos [ h 2 - 2 ⁢ L ⁢ h 2 ⁢ r ⁡ ( L + r - h ) + 1 ] a relation between a rotation angle α 1 of the first transmission gear and a rotation angle α 2 of the second transmission gear is expressed as: α 2 = z 2 z 1 ⁢ α 1 = z 2 z 1 ⁢ arc ⁢ cos [ h 2 - 2 ⁢ L ⁢ h 2 ⁢ r ⁡ ( L + r - h ) + 1 ] wherein, α 2 is the rotation angle of the sediment flushing ball valve and is equal to 90°.
3 . The smooth automatic device for reservoir sediment flushing according to claim 2 , wherein an elastic force F S (t) of the upper spring is equal to a submerged weight of sediment in the vertical pipe, which is expressed as: F S ( t ) = ( ρ S - ρ ) ⁢ π ⁢ R 2 ⁢ h ⁡ ( t ) wherein, R is an internal radius of the vertical pipe or a radius of the upper piston body; h(t) is a deposition above surface of the upper piston body and is a function of time t; a maximum elastic force that the upper spring can withstand is expressed as: F S ⁢ max = k ⁡ ( ρ S - ρ ) ⁢ π ⁢ R 2 ⁢ h max wherein, k is a parameter of a normal distributional funnel, set to be 1.1˜1.2, h max is approximately equal to H, ρ S is a density of accumulated sediment, ρ is a density of water, and H is a height from a mud surface to the bottom of the sediment flushing funnel.
4 . The smooth automatic device for reservoir sediment flushing according to claim 3 , wherein linkage trigger heads that are capable of horizontally sliding are installed symmetrically at the top and the bottom of the vertical pipe, and the linkage trigger heads on a same side of the top and bottom of the vertical pipe are connected by a linkage rod; a limit allowance suitable for the upper piston body is provided between two linkage trigger heads installed at the top of the vertical pipe, and a limit allowance suitable for the lower piston body is provided between two linkage trigger heads installed at the bottom of the vertical pipe; an extrusion spring is set between the vertical pipe and each of the linkage trigger heads.
5 . The smooth automatic device for reservoir sediment flushing according to claim 4 , wherein the sediment flushing funnel is a normal distributional funnel, and the normal distributional funnel is formed by rotating a concave normal-distribution curve around an axis of symmetry; the sediment flushing pipe is an inverse hyperbolic tangent pipe, and a central curve of the inverse hyperbolic tangent pipe is an inverse hyperbolic tangent curve; both the normal distributional funnel and the inverse hyperbolic tangent pipe have arbitrary order of derivatives and have arbitrary degree of smoothness.
6 . The smooth automatic device for reservoir sediment flushing according to claim 5 , wherein top of the smooth connecting pipe is tangent to bottom of the normal distributional funnel, and bottom of the smooth connecting pipe is tangent to top of the inverse hyperbolic tangent pipe; the smooth connecting pipe adopts the following design: in a longitudinal section y=0 of the normal distributional funnel, a single variable normal distribution form corresponding to the normal distributional funnel is denoted as z=h(x), and a function corresponding to a curve at an entrance of the inverse hyperbolic tangent pipe is denoted as z=g(x), wherein, a surface of the normal distributional funnel and the entrance of the inverse hyperbolic tangent pipe are rotationally symmetrical with respect to an ordinate z; a slope of an outlet (x 0 , 0, z 0 ) at the normal distributional funnel is denoted as h′-(x 0 ), a slope at the entrance (x 1 , 0, z 1 ) of the inverse hyperbolic tangent channel is denoted as g′-(x 1 ), wherein |x 0 |>|x 1 |, let C ⁡ ( x ) = z 0 + h ′ ( x 0 ) ⁢ ( x - x 0 ) + β 2 ( x - x 0 ) 2 + β 3 ( x - x 0 ) 3 wherein, β 2 and β 3 are polynomial coefficients depending on the slopes h′-(x 0 ) and g′-(x 1 ), respectively: β 2 = 3 ⁢ ( z 1 - z 0 ) - ( x 1 - x 0 ) ⁢ ( 2 ⁢ h ′ ( x 0 ) + g ′ ( x 1 ) ) ( x 1 - x 0 ) 2 β 3 = ( h ′ ( x 0 ) + g ′ ( x 1 ) ) ⁢ ( x 1 - x 0 ) + 2 ⁢ ( z 0 - z 1 ) ( x 1 - x 0 ) 3 wherein a pipe body of the smooth connecting pipe is a rotationally symmetric surface z=C(x, y) corresponding to a curve C(x).
7 . A smooth automatic method for reservoir sediment flushing, which is based on the smooth automatic method for reservoir sediment flushing according to claim 5 , comprising: step s1: reservoir sediment is dropped into the normal distributional funnel before reaching the reservoir dam, wherein the reservoir sediment enters the vertical pipe and acts on an upper surface of the upper piston body, the clean-water pipe transmits a pressure of a clean-water column between a surface of water and the upper piston body, to a lower surface of the upper piston body; step s2: with an increase in sediment mass, a pressure difference between top and bottom of the upper piston body in the vertical pipe becomes larger, the upper piston body slides downward along the vertical pipe under an action of reservoir sediment pressure until the upper piston body reaches the lower piston body; the reservoir sediment continues to be deposited, and the upper piston body and the lower piston body slide downward together; when the sediment mass in the normal distributional funnel increases to a threshold M 1 -(H), a force experienced by the upper piston body reaches a set threshold M p =ηM 1 (H), and the lower piston body reaches the bottom of the vertical pipe, wherein, η is set according to a ratio of a volume of a deposition volume πR 2 h max above the upper piston body to a volume of the normal distributional funnel with a same top elevation, M 1 -(H) is a force threshold of the upper piston body; step s3: downward movement of the lower piston body drives the connecting rod to move downward to drive the first transmission gear to rotate, and further to drives the second transmission gear to rotate, so as to drive the sediment flushing ball valve into rotation and to be gradually opened, sediment accumulated in the normal distributional funnel is discharged from the reservoir to the downstream river channel through the smooth connecting pipe; at this moment, the lower piston body is stuck between the two linkage trigger heads installed at the bottom of the vertical pipe, which limits an action of the lower piston body, and the sediment flushing ball valve is fully opened to complete sediment flushing continuously; step s4: in a process of sediment discharge in the normal distributional funnel, the pressure difference between the top and bottom of the upper piston body decreases, and the upper piston body gradually resets under an action of the upper spring, when the upper piston body reaches the top of the vertical pipe, the two linkage trigger heads installed at the top of the vertical pipe are triggered; then the two linkage trigger heads installed at the bottom of the vertical pipe are opened, so that the lower piston body is free from limits and can be reset under an action of the lower spring to drive the connecting rod to move upward along the vertical pipe, and to drive the sediment flushing ball valve to be closed through the first transmission gear and the second transmission gear; and step s5: step s1 to step s4 are cycled.
8 . The smooth automatic method for reservoir sediment flushing according to claim 7 , wherein in step s1, a buoyancy of the upper piston body is equal to F S ( t ) = ρ ⁢ π ⁢ R 2 ⁢ h ⁡ ( t ) , and the threshold M 1 (H) in step s2 is calculated by following formula: M 1 ( H ) = 2 ⁢ ( ρ s - ρ ) ⁢ σ 2 ⁢ H [ 1 - ( 1 - k 2 ⁢ π ⁢ σ ⁢ H ) ⁢ ln ⁢ ( 1 - 2 ⁢ π ⁢ σ ⁢ H k ) ] wherein, σ is a variance parameter of the normal distributional funnel.

Description

TECHNICAL FIELD The present invention relates to the technical field of water conservancy project, in particular to a smooth automatic device and method for reservoir sediment flushing. BACKGROUND ART In many rivers there are the problems of high sediment concentration and large sediment discharge, that is, the problem of sediment deposition, is prominent and is one of the challenges for sediment control in the world. After the construction of a water retaining dam on the river to form a reservoir, the water level in the reservoir area is raised, the flow velocity is reduced, and the sediment carried by the water flow is accumulated in the reservoir area, in particular the sediment deposition in front of the dam is the thickest, which significantly reduces the effective capacity of the reservoir. In severe cases, it leads to reservoir siltation and waste. Reservoir sedimentation not only reduces the capacity of the reservoir and shortens the service life, but also causes serious erosion of the downstream river channel due to the discharge of clear water, which destroys the downstream river ecological environment and the habitat of aquatic animals along the river. Meanwhile, the lack of fine-grained suspended matter in the water body results in a lack of biogenic materials and affecting the survival of aquatic animals. Currently, the methods to solve the sediment deposition of reservoirs mainly include sediment discharge gate, sediment discharge around the reservoir, mechanical dredging and siphon sediment discharge, in addition to the three soil-and-water conservation measures, by siltation dam, terraced fields and forest-grass land. Wherein, the scouring sluice is opened when the density current occurs in the flood season, but the sand in unit water body is less than 15%. The scouring sluice is opened and closed by the electromechanical device, wasting water resources and electric energy. The scouring sluice is closed to store clear water after the flood season, and the scouring sluice is opened to discharge muddy water in the flood season, which is the scheduling method of clear-water-storage and muddy-water-discharge, and has been widely used in reservoir sediment flushing in China so far. The disadvantage is that a large amount of water is released during the flood season, resulting in a waste of water resources. In the circuitous method of sediment flushing, the sediment flushing pipe or tunnel is opened on the side of the reservoir to make the sediment bypass the reservoir dam and discharge into the downstream river channel. The sediment discharge efficiency of unit water body is not as good as that of density current, not suitable for reservoirs with long reservoir area or large reservoir capacity. Mechanical dredging requires a lot of energy and manpower, and the disposal of deposit is difficult, which is not suitable for large and medium-sized reservoirs. Siphon sediment flushing uses the downstream water head difference of the dam in the reservoir area to suck the sediment at the bottom of the reservoir into the pipeand discharge it outside, but the disadvantages are that the mechanical movement of suction head and the suction itself are time-consuming and energy-consuming. SUMMARY To solve the above problems, the present invention provides a smooth automatic device and method for reservoir sediment flushing, the combination of automatic sediment flushing and control methods provides a new idea for solving the problem of reservoir sedimentation, the smooth characteristics of gravity automatic sediment flushing function reduce the probability of device clogging, the sediment flushing control system does not require electric drive, which can significantly improve the efficiency of reservoir sediment flushing, save water resources and energy, and improve the ecological environment of downstream rivers. To achieve the above purposes, the present invention provides a smooth automatic device for reservoir sediment flushing, including a sediment flushing funnel set at the bottom of the reservoir dam and a sediment flushing pipe connected to the bottom of the sediment flushing funnel through a smooth connecting pipe at one end, connected to the downstream river channel at the other end after passing through the reservoir dam horizontally; a trigger-control mechanism is arranged inside the sediment flushing funnel, and a trigger-control mechanism connected with a sediment flushing ball valve is arranged inside the sediment flushing pipe. Preferably, the trigger-control mechanism includes a vertical pipe set on the inner wall of the sediment flushing funnel and an upper piston assembly and a lower piston assembly set inside the vertical pipe, capable of vertically sliding, the lower piston assembly is connected to the top of the connecting rod, the bottom end of the connecting rod passes through the vertical pipe and is connected eccentrically with a first transmission gear, the first transmission gear and