RU2753646C1 - Inlet valve to flow part of hydraulic turbine - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention relates to the field of power engineering, specifically hydraulic turbine construction, in particular to the air intake valve in the flow part of a hydraulic turbine. The air intake valve contains a body consisting of coaxial inner and outer cylinders, a shut-off body, a lid, a base with through holes. In the inner cylinder there are windows connecting the inner cavity of the inner cylinder with the inner cavity of the outer cylinder. The locking body is made in the form of at least one sealing element made of elastic material, fixed on the base from the side of the flow part and closing the through holes. A noise-absorbing material is fixed on the inner surfaces of the inner and outer cylinders and on the inner end surface of the lid. The inner cavity of the inner cylinder is evenly and densely filled with noise-suppressing elastic filler with the possibility of free passage of air through the specified cavity.

EFFECT: reduction in the level of aerodynamic noise during the operation of the air intake valve, an increase in the operational reliability of the valve, a simplification of the valve design.

3 cl, 3 dwg

Description

The proposed technical solution relates to the field of power engineering, in particular, hydraulic turbine, in particular, to the valve for air inlet into the flow path of the hydraulic turbine.

It is known that when a hydraulic turbine is operating outside the optimal mode zone, power fluctuations occur, as well as increased fluctuations of the hydrodynamic water pressure in the flow path of the turbine, primarily under the impeller (for a radial-axial hydraulic turbine) and under the turbine cover (for a rotary-blade hydraulic turbine ). The pressure pulsations of the working fluid are mainly due to the presence of a rotating vortex bundle that occurs in the partial load mode in the suction pipe. A vortex bundle is the primary cause of the occurrence of significant vibrations of the hydraulic turbine, leading to faster wear of the equipment and the possible destruction of individual structural elements, which generally reduces the service life of the hydraulic turbine. To reduce pressure pulsations and power fluctuations, air inlet valves are used in the flow path of the turbine.

At the same time, when air is admitted and passed through the valve, an increase in the level of aerodynamic noise occurs. To reduce the noise level, as well as to prevent its further spread, known designs of valves and silencers are used, installed both inside the valve itself and outside, in a separate design. In some cases, the air inlet valve is removed with the help of pipes outside the building of the hydroelectric power station to reduce the noise level in the building of the hydroelectric power station. However, these devices can only slightly reduce the noise level, and also have a rather complex design. According to the requirements of safety and labor protection, the equivalent level of noise generated by a working hydro-turbine unit in the premises of a hydroelectric power station should be no more than 85 dB in accordance with GOST 12.1.003.

It is known that noise-absorbing (sound-absorbing) materials and sound-absorbing fillers are used to reduce vibrations and noise levels. Sound-absorbing materials are applied in the form of coatings and fixed on the surface of the structure (part). As a sound-absorbing material, a porous material can be used, in which sound waves are scattered through the pores, absorb sound energy with its transformation into thermal energy, thereby lowering the level of sound vibrations. Noise damping fillers allow you to absorb and dissipate sound energy in their structure, weakening it as much as possible, and provide a decrease in the speed and damping of sound waves.

Known invention "Device for air inlet into the impeller zone of a radial-axial hydraulic turbine" (USSR author's certificate No. 1406404; F03B 11/00; publication date 09.24.1985). The device for the air inlet of the hydraulic turbine is aimed at increasing the reliability of operation and reducing the noise level during the air inlet and contains a drainage system, the body element is a pipe fixed in the plugs installed in the shaft cavities and covering the inlet and check valves, a silencer, a throttle located behind it along the air flow washer and water intake. The silencer is a welded cylinder with several rows of holes in the radial direction. Installing a throttle washer behind the muffler reduces air intake noise.

The disadvantage of the known solution is low operational reliability due to unstable operation with multiple re-openings and closings of the check valve, as well as a slight decrease in the level of aerodynamic noise during air intake, the complexity of the design due to the presence of many structural elements and systems.

The closest technical solution to the proposed technical solution in terms of a set of essential features and selected as a prototype is the invention "Device for air inlet into the flow path of a hydraulic turbine" (RF Patent No. 2403433; IPC F03B 11/00; publication date 10.11.2010). According to the invention, the air inlet device (valve) comprises a body consisting of coaxial inner and outer cylinders, a shut-off element, a seat (cover), a bottom (base) having through holes. A hollow cylinder is coaxially installed in the inner cavity of the inner cylinder. The shut-off element is equipped with a piston located in the inner cavity of the hollow cylinder. The bottom, to reduce the noise level, is made with a lot of through holes, the total area of which is 2-6 times less than the area of the flow area of the valve in the fully open position, which makes it possible to reduce the speed of air passing through the valve and reduce the noise level. The cavity of the hollow cylinder under the piston is connected to the flow path of the hydraulic turbine, and the cavity above the piston is connected to atmospheric air.

The disadvantage of the known solution is that repeated shock loads do not allow achieving high reliability of the device. Also, the operation of the valve does not significantly reduce the level of aerodynamic noise arising from the air intake. The assembly of the valve complicates the assembly of the shut-off element and the need to adjust the pressure at which the valve opens.

The technical result, to which the claimed invention is directed, consists in reducing the level of aerodynamic noise during the operation of the air intake valve and increasing the operational reliability of the valve, simplifying the valve design.

To achieve the above technical result, the valve for air inlet into the flow path of the hydraulic turbine contains a housing consisting of coaxial inner and outer cylinders, a shut-off element, a cover, a base having through holes.

In this case, according to the claimed invention, in the inner cylinder there are windows that combine the inner cavity of the inner cylinder with the inner cavity of the outer cylinder.

The shut-off element is made in the form of at least one sealing element made of elastic material, fixed on the base from the side of the flow path and closing the through holes.

Sound-absorbing material is fixed on the inner surfaces of the inner and outer cylinders and on the inner end surface of the cover.

The inner cavity of the inner cylinder is uniformly and densely filled with a sound-absorbing elastic filler with the possibility of free passage of air through the specified cavity.

Noise-damping resilient filler is a loosely twisted stainless steel wire.

Noise-damping elastic filler is made of polymer balls.

The execution of windows in the inner cylinder, combining the inner cavity of the inner cylinder with the inner cavity of the outer cylinder, allows atmospheric air to pass into the zone with elastic noise-dampening material and to reduce the height dimensions of the air intake valve.

The design of the shut-off member in the form of at least one sealing element made of elastic material, fixed on the base from the side of the flow path of the hydraulic turbine and closing the through holes, allows for a tight fit to the base. Sealing elements made of elastic material have reversible deformation, that is, the ability to easily deform many times and restore their original shape. Durability and reliability of sealing elements made of elastic material determine the stability of the air intake valve during its opening and closing, thereby increasing the operational reliability of its operation. Also, the elastic material has sound insulating properties, which reduces the level of aerodynamic noise during valve operation.

Fastening the noise-absorbing material on the inner surfaces of the inner and outer cylinders and on the inner end surface of the cover allows sound waves to be scattered and absorbed, thereby reducing the level of aerodynamic noise.

Uniform and dense filling of the inner cavity of the inner cylinder with a noise-dampening elastic filler with the possibility of free passage of air through the specified cavity, makes it possible to effectively absorb and dissipate sound energy in the filler structure, provides a decrease in the speed and damping of sound waves, and, thereby, reduces the level of aerodynamic noise. Various fillers can be used as an elastic noise-dampening filler, for example, loosely twisted stainless steel wire; balls made of polymeric material, for example, plastic or rubber, and other fillers.

The proposed design of the valve for air inlet into the flow path of the hydraulic turbine in the above-disclosed set of essential features allows to reduce the level of aerodynamic noise during the operation of the valve due to the use of noise-absorbing material and elastic noise-dampening filler, at least one sealing element made of elastic material, and also to increase the operational reliability of operation the valve for air inlet into the flow path of the turbine due to the stable operation of the valve when it is opened and closed. The design of the valve is more compact due to a decrease in the height dimensions of the valve and is simplified in comparison with the prototype, due to a change in the design of the shut-off body and a decrease in the number of structural elements.

The essence of the proposed technical solution is illustrated by graphic materials. FIG. 1 shows the valve for air inlet into the flow path of the hydraulic turbine in a closed state, with an internal cavity filled with a loosely twisted metal stainless wire; in fig. 2 - valve for air inlet into the flow path of the hydraulic turbine in the open state, Fig. 3 - valve for air inlet into the flow path of the hydraulic turbine in a closed state, with an internal cavity filled with polymer balls.

The valve for air inlet into the flow path of the hydraulic turbine contains a body consisting of coaxial inner cylinder 1 and outer cylinder 2, a shut-off element 3, a cover 4, a base 5, made in the form of a ring and having through holes 6. Base 5 separates the inner cavity A of the inner cylinder 1 from the flow path of the hydraulic turbine. The base 5 is made of steel, for example, from stainless steel 08X13 in accordance with GOST 5632 or structural carbon steel St3 in accordance with GOST 380-2005, with a paint and varnish coating, for example, Vinikor-62 enamel.

In the inner cylinder 1 there are windows 7 that combine the inner cavity A of the inner cylinder 1 with the inner cavity B of the outer cylinder 2 for the passage of atmospheric air through the valve.

The shut-off element 3 is made in the form of at least one sealing element 8 made of elastic material, fixed on the base 5 from the side of the flow path and closing the through holes 6, ensuring a snug fit to the base 5. The size of the through holes 6 and their number are determined in such a way that the total area of the through holes 6 was several times less than the flow area of the valve. The flow area of the valve is the total area of the windows 7 made in the inner cylinder 1. Sealing elements 8 can be made, for example, in the form of rubber rings of different diameters, mounted one on top of the other with a large diameter to the through holes 6 and further with a decreasing diameter. The diameters of the sealing elements 8 are selected from the condition of complete closure of the through holes 6. The number of sealing elements 8 determines at what vacuum under the impeller the valve will begin to open and supply air to the flow path. With a higher negative pressure and a higher suction force, a larger number of sealing elements 8 are required. For example, rubber according to GOST 7338-90 can be used as the elastic material of the sealing elements 8. In a specific embodiment, two sealing elements 8 are installed. The sealing elements 8 are fixed in the base 5 using fasteners - bush 9, nut 10, washer 11, pins 12 and cotter pin 13. When the valve is closed, the sealing elements 8 are tightly pressed against the base 5.

The valve cover 4 has an inlet 14 with a variable diameter to let air into the valve and reduce the air flow rate. As a rule, in the set supplied to the hydroelectric power station, there are several covers 4 with different variable diameters, and the required cover 4 is selected by the selection method. If necessary, the inlet 14 is being finalized at the hydroelectric power station.

On the inner surfaces of the inner cylinder 1 and the outer cylinder 2 and on the inner end surface of the cover 4, for example, glued with contact polychloroprene glue Quilosa BUNITEX P-55, or fixed with fasteners 15 noise-absorbing material 15. As noise-absorbing material 15, porous sheet material, for example, technical cork "SEDACOR". The thickness of the sound-absorbing material 15 is determined by its ability to bend, ensuring a snug fit to the valve surfaces without kinks.

The inner cavity A of the inner cylinder 1 is uniformly and densely filled with a noise-dampening elastic filler 16 with the possibility of free passage of air through the inner cavity A. 019-76213974-2015, or according to TU 1483-001-48773208-2015, which, when filling the inner cavity A, forms cells of arbitrary shape and size, through which air freely passes through the inner cavity A. for example, balls made of polymer material - rubber in accordance with GOST 7338-90 or plastic in accordance with GOST 50962-96. With uniform and dense filling of the inner cavity A, the polymer balls form gaps between themselves to ensure a free passage of air (Fig. 3). The diameter of the polymer balls is selected on the basis of ensuring the throughput of the valve without reducing it, that is, the necessary and sufficient amount of air must pass freely between the polymer balls.

The inner cavity A of the inner cylinder 1 is connected to the flow path of the hydraulic turbine, and the inner cavity B of the outer cylinder 2 is connected to atmospheric air.

The valve for air inlet to the flowing part of the hydraulic turbine can be installed in place 17. For a radial-axial hydraulic turbine, place 17 is at the end of the hollow shaft of the hydraulic turbine, outside or inside the shaft, at the end of the gear wheel. For Kaplan turbines, place 17 is on the turbine cover.

The proposed design works as follows.

When the pressure in the flow path of the hydraulic turbine decreases, after the impeller to a level preceding the occurrence of cavitation in the vortex zones and associated increased pressure pulsations in the flow and power of the hydraulic turbine, a pressure drop and a force sufficient to open the air inlet valve arise. The deformation of the sealing elements 8 made of elastic material allows the opening of the valve. When the valve is opened, through the inlet 14 of the valve cover 4, air enters the inner cavity B of the outer cylinder 2 and passes through the inner cavity A of the inner cylinder 1.

On the inner surfaces of the inner 1 and outer 2 cylinders and on the inner end surface of the cover 4, a noise-absorbing material 15 is fixed, which contributes to the scattering of sound waves and absorbs them, reducing the level of aerodynamic noise.

The inner cavity A is uniformly and densely filled with a sound-absorbing elastic filler 16, with the possibility of free passage of air through the inner cavity A, for example, with loosely twisted metal stainless wire or balls of polymer material. When air passes through the elastic noise dampening filler 16, its speed decreases, the sound energy is absorbed and dissipated in the filler structure 16. In this case, the speed decreases and sound waves are damped, and the level of aerodynamic noise decreases. Experimental studies carried out by the applicant have shown that the application of the proposed technical solution provides a decrease in the level of aerodynamic noise when air passes through the intake valve and, according to the measurements, is 82-85 dB.

Having passed the inner cavity A, then the air through the through holes 6 made in the base 5 enters the shaft cavity towards the impeller (radial-axial hydraulic turbine) or into the cavity under the turbine cover (Kaplan turbine) and enters the flow path of the hydraulic turbine. At the same time, when passing through holes 6, the air speed decreases and the level of aerodynamic noise continues to decrease. With a further decrease in pressure down to a pressure close to the pressure of water vapor, the valve is fully opened up to the stop. At constant pressure in the internal cavity B, connected to the atmosphere, and a decrease in pressure in the area of the flow path, there is a complete deformation of the sealing elements 8, and they open (Fig. 2).

When the hydraulic turbine leaves the unstable operation zone, the pressure behind the impeller of the radial-axial hydraulic turbine or behind the turbine cover of the Kaplan hydraulic turbine increases, which leads to a decrease in the pressure drop and the force on the sealing elements 8 to a level at which it is overcome by the compression force. The valve closes and the air supply to the flow path of the hydraulic turbine is cut off. In this case, the valve does not re-open and close, which ensures increased operational reliability of the air intake valve.

Claims (3)

1. The valve for air inlet into the flow path of the hydraulic turbine, containing a housing consisting of coaxial inner and outer cylinders, a shut-off element, a cover, a base having through holes, characterized in that the inner cylinder contains windows that combine the inner cavity of the inner cylinder with the inner cavity the outer cylinder, the shut-off element is made in the form of at least one sealing element made of elastic material, fixed on the base from the side of the flow path and closing the through holes, on the inner surfaces of the inner and outer cylinders and on the inner end surface of the cover, a noise-absorbing material is fixed, and the inner cavity the inner cylinder is uniformly and densely filled with a noise-dampening elastic filler with the possibility of free passage of air through the specified cavity. 2. The valve for air inlet into the flow part of the hydraulic turbine according to claim 1, characterized in that the elastic noise dampening filler is a loosely twisted stainless steel wire. 3. The valve for air inlet into the flow path of the hydraulic turbine according to claim 1, characterized in that the noise dampening resilient filler is made of polymer balls.

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