A throttling device for a flow and pressure regulating valve

Abstract

The present invention discloses a throttling device for a flow and pressure regulating valve, which includes a throttling sleeve with a central through hole. A flange is fixed on the upper surface of the throttling sleeve, and several positioning holes are provided on the flange. Several small-diameter throttling holes are provided in the side area of the throttling sleeve near the upper surface, and several large-diameter throttling holes are provided in the side area of the throttling sleeve near the lower surface. The present invention has a linear regulation characteristic, and can achieve continuous, stable and precise regulation within the required flow change range; under the maximum or minimum pressure difference, it can operate stably within the opening range of 10% to 100% without cavitation damage. Under the operating requirements such as high pressure difference and small flow rate, low pressure difference and large flow rate, and ultra-wide regulation range, the flow and pressure regulating effect of the valve can be achieved, while avoiding cavitation and reducing the vibration and noise of the valve. The reinforcing ribs can ensure that the whole or part does not deform, and at the same time have a certain guiding effect, so that the water flow jets towards the central part of the throttling sleeve along the side of the ribs.

Description

Technical Field

[0001] The present invention belongs to the technical field of valves and relates to a throttling device for a flow and pressure regulating valve. Background Art

[0002] Flow and pressure regulating valves are widely used in pipelines that require pressure reduction or stabilization, water intake pools of water plants, and flood discharge from reservoirs. The form of flow and pressure regulating valves generally adopts the piston type. Conventional piston valves can achieve flow regulation but cannot achieve pressure reduction. A flow and pressure regulating valve was developed by adding a set of throttling and energy dissipation sleeves at the end of the piston valve. An axial annular flow channel is formed inside the valve body, and a channel with gradually decreasing area and increasing flow velocity is formed from the inlet to the outlet. The sleeve at the end of the piston is provided with energy dissipation slots or round holes. The principle of symmetric water flow collision and energy dissipation is used to collide and cut energy with each other in the center of the valve body, adjust the piston stroke, and then adjust the flow area to play a role in regulating the flow rate, and at the same time achieve the effects of pressure reduction and flow regulation.

[0003] In recent years, with the large-scale construction of long-distance water transmission pipeline projects, the application of large-diameter flow and pressure regulating valves has been increasing. These pipeline projects generally have the situations of long distance, large flow rate, and large pressure difference before and after the valve. At the same time, they also face relatively complex working conditions during operation, which puts high requirements on the design of flow and pressure regulating valves. As a key component of the flow and pressure regulating valve, the throttling sleeve needs to achieve continuous, stable, and precise regulation within the flow rate change range. Its orifice type, size, quantity, and arrangement directly determine the flow rate and pressure regulation ability of the valve. Moreover, it also has an important impact on the cavitation characteristics of the valve. In addition, since the operating conditions of the valves in each project are different, the outlet throttling sleeve also needs to be designed according to specific hydraulic conditions. The common orifice types in the existing design are mostly single slot holes or round holes, which are difficult to simultaneously meet the requirements of flow rate, pressure, and cavitation for large-diameter flow and pressure regulating valves. Especially in some projects, the valves need to meet special working conditions such as high pressure difference and small flow rate, low pressure difference and large flow rate, and ultra-wide regulation range. The existing design methods cannot meet the requirements of pressure regulation, energy dissipation, and cavitation. Summary of the Invention

[0004] The purpose of the present invention is to provide a throttling device for a flow and pressure regulating valve, which solves the technical problems that the existing flow and pressure regulating valves cannot meet the requirements of flow regulation, pressure regulation, energy dissipation, and cavitation.

[0005] The technical solution adopted by the present invention is a throttling device for a flow and pressure regulating valve, which includes a throttling sleeve with a central through hole. A flange is fixed on the upper surface of the throttling sleeve. The flange is provided with several positioning holes. A plurality of throttling holes with small diameters are arranged in the side area of the throttling sleeve near the upper surface, and a plurality of throttling holes with large diameters are arranged in the side area of the throttling sleeve near the lower surface. The small-diameter throttling holes and the large-diameter throttling holes completely cover the side surface of the throttling sleeve.

[0006] The characteristics of the present invention also lie in:

[0007] The diameter of the small-aperture throttle orifice is 1 / 140 to 1 / 80 of the nominal diameter of the flow-regulating and pressure-regulating valve, and the diameter of the large-aperture throttle orifice is 1 / 60 to 1 / 35 of the nominal diameter of the flow-regulating and pressure-regulating valve.

[0008] The large-aperture throttle orifices are arranged at uniform intervals along the axial and circumferential directions of the throttle sleeve, and the small-aperture throttle orifices are arranged in a staggered plum blossom shape along the axial and circumferential directions of the throttle sleeve.

[0009] The side surface of the throttle sleeve is axially divided into several throttle orifice areas, and the small-aperture throttle orifices and the large-aperture throttle orifices are distributed therein.

[0010] The throttle orifice areas are arranged regularly.

[0011] Reinforcing ribs are provided between two adjacent circumferences of throttle orifices on the inner surface of the throttle sleeve.

[0012] A plurality of reinforcing ribs are provided.

[0013] The reinforcing ribs are arranged circumferentially along the inner wall of the throttle sleeve.

[0014] The width of the reinforcing rib is not greater than the width between two adjacent circumferences of throttle orifices, and the height of the reinforcing rib is 1 / 4 to 1 of the diameter of the small-aperture throttle orifice or the large-aperture throttle orifice at its adjacent position.

[0015] Reinforcing ribs are provided every two circumferences of small-aperture throttle orifices in the small-aperture throttle orifice area, and reinforcing ribs are provided every one circumference of large-aperture throttle orifices in the large-aperture throttle orifice area.

[0016] The positioning holes are arranged uniformly.

[0017] The present invention has the following beneficial effects:

[0018] (1) The arrangement of the throttle orifices has a linear regulation characteristic, and can achieve continuous, stable and accurate regulation within the required flow change range; under the maximum or minimum pressure difference, it can operate stably within the opening range of 10% to 100% without cavitation damage.

[0019] (2) Under the operating requirements such as high pressure difference and small flow rate, low pressure difference and large flow rate, and ultra-wide regulation range, it can achieve the flow-regulating and pressure-regulating effects of large-diameter valves, and at the same time avoid cavitation, reduce the vibration and noise of the valves.

[0020] (3) The reinforcing ribs can ensure that the large-diameter throttle sleeve does not deform as a whole or locally under the condition of having a large number of throttle orifices on the surface and high water pressure, and at the same time has a certain flow guiding effect, so that the water flow jets along the rib side to the central part of the throttle sleeve. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of a throttle device for a flow-regulating and pressure-regulating valve of the present invention;

[0022] Figure 2 This is a working schematic diagram of a throttling device for a flow and pressure regulating valve according to the present invention.

[0023] In the figure, 1. Throttle sleeve, 2. Flange, 3. Positioning hole, 4. Small-diameter throttle hole, 5. Large-diameter throttle hole, 6. Throttle hole area, 7. Reinforcing rib, 8. Piston, 9. Linkage mechanism. Specific embodiments

[0024] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] As Figure 1 shown, a throttling device for a flow and pressure regulating valve according to the present invention includes a throttle sleeve 1 with a central through hole. A flange 2 is fixed on the upper surface of the throttle sleeve 1. The flange 2 is provided with several positioning holes 3, and the positioning holes 3 are evenly arranged. A plurality of small-diameter throttle holes 4 are provided in the side area of the throttle sleeve 1 near the upper surface, and a plurality of large-diameter throttle holes 5 are provided in the side area of the throttle sleeve 1 near the lower surface. The small-diameter throttle holes 4 and the large-diameter throttle holes 5 completely cover the side surface of the throttle sleeve 1. The diameter of the small-diameter throttle holes 4 is 1 / 140 - 1 / 80 of the nominal diameter of the flow and pressure regulating valve, and the diameter of the large-diameter throttle holes 5 is 1 / 60 - 1 / 35 of the nominal diameter of the flow and pressure regulating valve. The large-diameter throttle holes 5 are evenly spaced along the axial and circumferential directions of the throttle sleeve 1, and the small-diameter throttle holes 4 are arranged in a staggered pattern in a plum blossom shape along the axial and circumferential directions of the throttle sleeve 1. The side surface of the throttle sleeve 1 is axially divided into several throttle hole areas 6, and the small-diameter throttle holes 4 and the large-diameter throttle holes 5 are distributed therein. The throttle hole areas 6 are regularly arranged. A plurality of reinforcing ribs 7 are provided between two adjacent circles of throttle holes on the inner surface of the throttle sleeve 1. The reinforcing ribs 7 are arranged along the circumferential direction of the inner wall of the throttle sleeve 1. The width of the reinforcing ribs 7 is not greater than the width between two adjacent circles of throttle holes. The height of the reinforcing ribs 7 is 1 / 4 - 1 of the diameter of the small-diameter throttle holes 4 or the large-diameter throttle holes 5 in the vicinity. Reinforcing ribs 7 are provided every two circles of small-diameter throttle holes in the small-diameter throttle hole area, and reinforcing ribs 7 are provided every one circle of large-diameter throttle holes in the large-diameter throttle hole area.

[0026] As Figure 2 shown, the flange 2 of this device is connected to the end of the piston 8 in the valve. After the nuts are inserted through the positioning holes 3 on the flange 2, they are fixed. During operation, the crank-link mechanism 9 in the valve drives the piston 8 to move along the valve center in the valve body to realize the operation of opening and closing the valve.

[0027] When the valve is working, water flows into the piston valve cavity along an arc. The flow path inside the valve is an axisymmetric ring, and it contracts streamline towards the axis at the outlet, so that the medium will not generate turbulence when flowing through the valve, effectively overcoming noise and vibration. The throttle sleeve of this device is provided with energy dissipation round holes. Water jets out from the throttle holes to form high-speed counter-jet impacts, playing a role in pressure reduction and energy dissipation. At the same time, the linear contraction at the outlet part of the valve and the guiding collision and resistance generated by the outlet throttle sleeve achieve the effect of energy dissipation and pressure reduction, avoiding the cavitation influence on the valve body or pipeline caused by throttling. No matter where the piston 8 is driven to, the cross-section of the water flow in the valve cavity is annular, making the valve opening degree linearly related to the flow rate, and having good flow rate or pressure regulation characteristics. Adjust the valve opening degree to achieve flow rate regulation. The valve driving device drives the piston 8 to move axially in the valve cavity through the crank connecting rod mechanism 9, thereby changing the flow area at the outlet of the valve body to achieve the regulation of flow rate and pressure.

[0028] The strengthening rib 7 is arranged in this device to ensure the stiffness of the throttle sleeve 1 of the large-diameter flow regulating and pressure regulating valve, and at the same time has a certain guiding effect, so that the water flow jets towards the central part of the throttle sleeve 1 along the side of the rib.

[0029] The aperture size is initially determined according to the flow rate and the pressure difference before and after the valve. According to the flow rate formula in the pressure pipeline, under ideal conditions, the flow rate Q per unit time 0 is:

[0030]

[0031] where, v is the flow velocity of the fluid, A is the area of the throttle hole, and μ m is the flow coefficient of the liquid, usually taken as 0.82, g is the acceleration due to gravity, and Δp is the pressure difference before and after the valve.

[0032] Therefore, when the pressure difference Δp and the flow rate Q before and after the valve 0 have been determined, only the area A of the throttle hole in the formula is unknown; assuming the aperture is the same, one circle of holes is set for every 10% opening degree, that is, 10 circles of holes are set on the entire throttle, and the number of holes in each circle is 64 at the same time. Then, according to the area formula of the circle, the approximate size of the hole opening can be obtained.

[0033] Example 1:

[0034] The throttle device in this example is applied to the flow regulating and pressure regulating valve of DN2000 model. Its nominal diameter is 2000 mm. Therefore, the diameter of the small-aperture throttle hole 4 is 1 / 80 of the nominal diameter of the flow regulating and pressure regulating valve, that is, 25 mm; the diameter of the large-aperture throttle hole 5 is 1 / 40 of the nominal diameter of the flow regulating and pressure regulating valve, that is, 50 mm; this embodiment divides 8 throttle hole areas 6, and the throttle hole areas 6 are evenly arranged along the surface of the device.

[0035] When the valve opening is below 30%, six rows of small-diameter throttle holes 4 are arranged in a circumferential misalignment along the throttle sleeve 1, with 64 holes in each row, and the total number of holes is 384; when the valve opening is above 30%, large-diameter throttle holes 5 are provided for every 10% of the opening, and seven rows of large-diameter throttle holes 5 are evenly arranged in a circumferential direction along the throttle sleeve 1, with 64 holes in each row, and the total number of holes is 448.

[0036] For the area of the small-diameter throttle holes 4, a reinforcing rib 7 is provided every two rows. The height of the reinforcing rib 7 in this area is 3 / 4 of the throttle hole diameter, that is, 18.75 mm, and the width is 8 mm; for the area of the large-diameter throttle holes 5, a reinforcing rib 7 is provided every row. The height of the reinforcing rib 7 in this area is 1 / 4 of the throttle hole diameter, that is, the height of the reinforcing rib is 12 mm, and the width is 10 mm.

[0037] Embodiment 2:

[0038] The throttle device in this example is applied to a flow-regulating and pressure-regulating valve of DN2000 model, and its nominal diameter is 2000 mm. Therefore, the diameter of the small-diameter throttle hole 4 is 1 / 140 of the nominal diameter of the flow-regulating and pressure-regulating valve, that is, 14 mm; the diameter of the large-diameter throttle hole 5 is 1 / 35 of the nominal diameter of the flow-regulating and pressure-regulating valve, that is, 57 mm; in this embodiment, eight throttle hole areas 6 are divided, and the throttle hole areas 6 are evenly arranged along the surface of the device.

[0039] When the valve opening is below 30%, ten rows of small-diameter throttle holes 4 are arranged in a circumferential misalignment along the throttle sleeve 1, with 128 holes in each row, and the total number of holes is 1280; when the valve opening is above 30%, large-diameter throttle holes 5 are provided for every 10% of the opening, and seven rows of large-diameter throttle holes 5 are evenly arranged in a circumferential direction along the throttle sleeve 4, with 64 holes in each row, and the total number of holes is 448.

[0040] For the area of the small-diameter throttle holes 4, a reinforcing rib 7 is provided every two rows. The height of the reinforcing rib 7 in this area is the throttle hole diameter, that is, 14 mm, and the width is 4 mm; for the area of the large-diameter throttle holes 5, a reinforcing rib 7 is provided every row. The height of the reinforcing rib 7 in this area is 1 / 2 of the throttle hole diameter, that is, the height of the reinforcing rib is 28.5 mm, and the width is 8 mm.

[0041] Embodiment 3:

[0042] The throttle device in this example is applied to a flow-regulating and pressure-regulating valve of DN2000 model, and its nominal diameter is 2000 mm. Therefore, the diameter of the small-diameter throttle hole 4 is 1 / 110 of the nominal diameter of the flow-regulating and pressure-regulating valve, that is, 18 mm; the diameter of the large-diameter throttle hole 5 is 1 / 48 of the nominal diameter of the flow-regulating and pressure-regulating valve, that is, 42 mm; in this embodiment, eight throttle hole areas 6 are divided, and the throttle hole areas 6 are evenly arranged along the surface of the device.

[0043] When the valve opening is below 30%, 9 rows of small-diameter throttle holes 4 with a diameter of 25 mm are arranged in a circumferential offset along the throttle sleeve 1, with 64 holes in each row, and the total number of holes is 576; when the valve opening is above 30%, large-diameter throttle holes 5 with a diameter of 50 mm are provided for every 10% opening, and 7 rows of large-diameter throttle holes 5 are evenly arranged in a circumferential direction along the throttle sleeve 1, with 64 holes in each row, and the total number of holes is 448.

[0044] For the area of the small-diameter throttle holes 4, a reinforcing rib 7 is provided every two rows. The height of the reinforcing rib 7 in this area is 1 / 2 of the throttle hole diameter, that is, 9 mm, and the width is 5 mm; for the area of the large-diameter throttle holes 5, a reinforcing rib 7 is provided every row. The height of the reinforcing rib 7 in this area is the same as the throttle hole diameter, that is, the height of the reinforcing rib 7 is 42 mm, and the width is 12 mm.

[0045] In order to verify the performance effect of the present device and at the same time to verify the comparison effect with a throttling device having the same aperture size, the following experimental scheme was designed for the above embodiments. Specifically as follows:

[0046] The design requirements for the DN2000 type flow regulating and pressure regulating valve are as follows: when the pressure difference Δp between the front and rear of the valve is 61 m to 96 m, the flow rate Q 0 range is 2 ≤ Q 0 ≤ 6 m 3 / s; when the pressure difference Δp between the front and rear of the valve is 16 m to 61 m, the flow rate Q 0 range is 2 ≤ Q 0 ≤ 15.5 m 3 / s, when the pressure difference Δp between the front and rear of the valve is 11 m to 16 m, the flow rate Q 0 range is 2 ≤ Q 0 ≤ 14 m 3 / s.

[0047] The following three schemes are designed:

[0048] 1. Scheme 1 (the scheme of this patent): When the valve opening is below 30%, 6 rows of small-diameter throttle holes 4 with a diameter of 25 mm are arranged in a circumferential offset along the throttle sleeve 1, with 64 holes in each row, and the total number of holes is 384; in the range above 30% opening, large-diameter throttle holes 5 with a diameter of 50 mm are provided for every 10% opening, and 7 rows of large-diameter throttle holes 5 are evenly arranged in a circumferential direction along the throttle sleeve 1, with 64 holes in each row, and the total number of holes is 448.

[0049] 2. Solution 2 (the opening diameter is the small-diameter throttle hole diameter in Solution 1): When the valve opening is below 30%, 6 rows of small-diameter throttle holes 4 with a diameter of 25 mm are arranged in a circumferential dislocation along the throttle sleeve 1, with 64 holes in each row, and the total number of holes is 384; in the range above 30% opening, 2 rows of small-diameter throttle holes 4 with a diameter of 25 mm are set for every 5% opening, and they are evenly arranged in 14 rows along the circumferential direction of the throttle sleeve 1, with 128 holes in each row, and the total number of holes is 1792.

[0050] 3. Solution 3 (the opening diameter is the large-diameter throttle hole diameter in Solution 1): When the valve opening is below 30%, 3 rows of large-diameter throttle holes 5 with a diameter of 50 mm are arranged in a circumferential dislocation along the throttle sleeve 1, with 64 holes in each row, and the total number of holes is 192; in the range above 30% opening, large-diameter throttle holes 5 with a diameter of 50 mm are set for every 10% opening, and they are evenly arranged in 7 rows of large-diameter throttle holes 5 along the circumferential direction of the throttle sleeve 1, with 64 holes in each row, and the total number of holes is 448.

[0051] The CFD software is used to conduct numerical simulations on the two opening solutions respectively to understand their flow fields and cavitation conditions, and the working conditions when the head difference before and after the valve is 96 m, 61 m, 16 m, and 11 m are calculated respectively. The results are as follows:

[0052] Among the three solutions, the results are exactly the same when the opening is below 30%, and no cavitation occurs, so it is only necessary to calculate the working conditions above 30% opening. Further calculation results show that cavitation occurs at different openings when the head difference before and after the valve is 61 m. The calculation results at 60% opening are shown in Table 1:

[0053] Table 1 Comparison of experimental effects

[0054] Solution <![CDATA[Flow rate (m 3 / s)]]> Minimum Pressure (kPa) Whether Cavitation Occurs Solution 1 15.8 75 No Solution 2 19.4 214 Yes Solution 3 25.2 180 Yes

[0055] As can be seen from Table 1, the flow rate in Solution 1 is close to the designed maximum flow rate of 15.5 m 3 / s when the head difference is 61 m, and at the same time, no cavitation occurs; the flow rate in Solution 2 is much greater than the maximum flow rate of 15.5 m 3 / s when the head difference is 61 m, and at the same time, cavitation occurs, not meeting the design requirements; from the perspective of the lowest pressure, the lowest pressure in Solution 1 is also lower than that in Solution 2, indicating that this solution has a better energy dissipation and pressure reduction effect. The flow rate in Solution 3 is much greater than the maximum flow rate of 15.5 m 3 / s when the head difference is 61 m, and at the same time, cavitation occurs, not meeting the design requirements.

[0056] The size and quantity of the throttle holes of this device are roughly given according to the pressure difference and flow rate before and after the valve works, and are further optimized and determined through numerical simulation. The range of the diameters of the given large and small holes meets the flow requirements and does not cause cavitation at the same time. The throttle hole arrangement has a linear adjustment characteristic and can achieve continuous, stable and precise adjustment within the required flow change range; under the maximum or minimum pressure difference, it can operate stably within the opening range of 10% - 100% without cavitation damage. Under operating requirements such as high pressure difference and low flow rate, low pressure difference and high flow rate, and ultra-wide adjustment range, the flow regulation and pressure regulation effects of the valve can be achieved, while avoiding cavitation and reducing the vibration and noise of the valve.

Claims

1. A throttling device for a flow and pressure regulating valve, characterized in that, it includes a throttling sleeve (1) with a central through hole. A flange plate (2) is fixed on the upper surface of the throttling sleeve (1). The flange plate (2) is provided with several positioning holes (3). Several small-diameter throttling holes (4) are arranged in the side area of the throttling sleeve (1) near the upper surface. Several large-diameter throttling holes (5) are arranged in the side area of the throttling sleeve (1) near the lower surface. The small-diameter throttling holes (4) and the large-diameter throttling holes (5) completely cover the side of the throttling sleeve; the diameter of the small-diameter throttling holes (4) is 1 / 140 - 1 / 80 of the nominal diameter of the flow and pressure regulating valve, and the diameter of the large-diameter throttling holes (5) is 1 / 60 - 1 / 35 of the nominal diameter of the flow and pressure regulating valve; the large-diameter throttling holes (5) are arranged at equal intervals along the axial and circumferential directions of the throttling sleeve (1), and the small-diameter throttling holes (4) are arranged in a staggered plum blossom shape along the axial and circumferential directions of the throttling sleeve (1); the side of the throttling sleeve (1) is axially divided into several throttling hole areas (6), and the small-diameter throttling holes (4) and the large-diameter throttling holes (5) are distributed in the throttling hole areas (6); the throttling hole areas (6) are arranged regularly; reinforcing ribs (7) are arranged between the throttling holes on the inner surface of the throttling sleeve (1). Reinforcing ribs (7) are arranged every two circles of small-diameter throttling holes in the area of the small-diameter throttling holes (4), and reinforcing ribs (7) are arranged every one circle of large-diameter throttling holes in the area of the large-diameter throttling holes (5); a plurality of the reinforcing ribs (7) are provided; the reinforcing ribs (7) are arranged circumferentially along the inner wall of the throttling sleeve (1).

2. The throttling device for a flow and pressure regulating valve according to claim 1, characterized in that, the width of the reinforcing rib (7) is not greater than the width between two adjacent circles of throttling holes, and the height of the reinforcing rib (7) is 1 / 4 - 1 of the diameter of the small-diameter throttling hole (4) or the large-diameter throttling hole (5) adjacent thereto.

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