RU81542U1 - DYNAMIC OSCILLATOR - Google Patents

Abstract

The proposed technical solution relates to dynamic vibration dampers used in the field of power engineering to reduce vibration of the bearings of the rotors of turbine units of mainly medium and high power. The technical result achieved by the utility model consists in damping the vibrations of the support of the turbine unit without reconfiguring the damper simultaneously at two frequencies: ω ₁ equal to the nominal frequency ω of the rotor rotation, and ω ₂ equal to the double nominal speed of the rotor. At the same time, the compact design of the DHA allows it to be installed in a limited space between the bearing cover and the cylinder body. The dynamic damper contains a plate with adjusting weights installed on it, and the plate is curved in the form of a half ring, is rigidly fixed by both ends on the surface of the support of the turbine unit, and the plate parameters thickness h and width 1 are determined by empirical dependencies

h = 1.17ωR ² / c

1 = 5.45 · 10 ^-3 mc / γωR ³ ,

Where

ω - nominal rotational speed of the rotor of the turbine unit

R is the average radius of the half ring

m is the mass of the support

C is the speed of sound propagation in the plate material

γ is the specific gravity of the plate material.

1 ill.

Description

The inventive utility model relates to dynamic vibration dampers (DHA) used in the field of power engineering to reduce vibration of the bearings of the rotors of turbine units of mainly medium and high power. As you know, the reliable operation of the support nodes to a large extent determines the trouble-free and operational reliability of the turbine as a whole, and therefore, the development of effective vibration dampers of bearing bearings is currently an extremely urgent task.

During operation of the turbine unit, disturbing forces from the side of the turbine and / or generator act on the support nodes, including at frequencies equal to the nominal and double rated rotor speeds.

In order to damp the vibrations of the supports of a turbine unit operating with a constant rotor speed, dynamic vibration dampers are currently widely used. It should be noted that when creating dynamic vibration dampers of bearing bearings, one should also take into account rather stringent requirements to the dimensions of dampers, as in the places where the bearings are installed, there is practically no additional free space between the bearing cover and the turbine cylinder body.

Known dynamic vibration damper [RF Patent No. 2035645, F16F 15/00, priority date - 11/26/1991, publication date in the Official Bulletin of the Russian Federation - 05/20/1995], used in conditions of limited dimensions to damp vibrations of bearings of power units operating at a constant frequency rotation. The specified damper contains an elastic massive beam, in the middle part of which there is a massive mount. At the ends of the beam, masses are fixed. DHA also contains

a flexible intermediate element located between the quenching object and the elasto-massive beam, connected to the beam mount.

The considered dynamic damper provides vibration compensation at only one frequency and cannot be used to damp vibrations simultaneously at two frequencies without retuning the damper.

Also known dynamic vibration damper [Nikiforov A.S., Acoustic design of ship structures: Reference. - L .: Sudostroenie, 1990, p.137-138], made in the form of a massive large-sized plate mounted on elastic elements, which reduces the amplitude of resonant vibrations.

This damper provides damping of oscillations only at one frequency and, in addition, cannot be applied in conditions of limited dimensions of the installation sites of bearing supports of turbine units.

The closest in technical essence to the claimed utility model is a dynamic vibration damper [Strelkov SP, Mechanics: textbook.- M .: Lan, 2005, p. 470, Fig. 390], designed to damp vibrations of the bearing housing of a machine operating with a constant speed. The damper is made in the form of a plate rigidly mounted vertically on the bearing housing, with the plate fixed to the bearing housing at one end, and a load fixed to the other free end of the plate. The natural frequency of oscillation of the plate with the load is equal to the frequency of rotation of the machine.

However, this device can operate without reconfiguration at only one frequency equal to the frequency of the disturbing force, and the vertical arrangement of the absorber above the quenching object structurally does not allow the placement of DHA on the support of the turbine unit due to the limited free space between the bearing cover and the cylinder body.

Thus, dynamic vibration dampers known in the art do not allow damping vibrations at two frequencies simultaneously without reconfiguration.

During operation of the turbine unit, the rotor bearing experiences disturbing influences with a frequency ω ₁ equal to the nominal rotor speed ω (ω ₁ = ω), which arise as a result of unbalance of the rotor. In addition, the support experiences disturbing influences with a frequency of ω ₂ , which arise due to unequal rotor stiffness along the axes and / or ovality of the rotor pins, as well as in a number of other cases. In this case, the frequency of these perturbations ω ₂ is equal to twice the nominal rotor speed (ω ₂ = 2ω), which causes resonant vibrations of the support if its natural vibration frequency is also equal to 2ω. As a result, these disturbing influences can lead to damage to the structures of the supports, which can cause an emergency and a shutdown of the turbine unit.

The technical result achieved by the claimed utility model consists in damping the vibrations of the support of the turbine unit without reconfiguring the damper simultaneously at two frequencies: ω ₁ equal to the rated frequency ω of rotation of the rotor of the turbine unit (ω ₁ = ω), and ω ₂ equal to the double rated frequency of rotation of the rotor (ω ₂ = 2ω). At the same time, the compact design of the DHA allows it to be installed in a limited space between the bearing cover and the cylinder body.

To achieve the technical result, a dynamic vibration damper is proposed, comprising a plate with adjusting weights mounted on it. Moreover, according to the claimed utility model, the plate is made curved in the form of a half ring, is rigidly fixed by both ends on the surface of the support of the turbine unit, and the plate parameters thickness h and width 1 are determined according to empirical dependencies, which are obtained on the basis of experimental data:

h = 1,17ωR ² / c

1 = 5.45 · 10 ^-3 mc / γωR ³ ,

Where

h is the plate thickness, (m)

1 - plate width, (m)

ω is the nominal circular frequency of rotation of the rotor of the turbine unit, (s ^-1 )

R is the average radius of the half ring, (m)

m - mass of support, (kg)

s is the speed of sound propagation in the plate material, (m / s)

γ is the specific gravity of the plate material, (kg / m ³ ).

The execution of the damper in the form of a half ring provides a rational distribution of the damper mass over the damping object and allows the absorber to be made of a sufficiently large mass with an inertia moment necessary for efficient damping of vibrations of large-sized bearing bearings weighing several tons. Also, the implementation of the damper in the form of a half ring provides an optimal layout of the damper design - it makes it possible to place the damper above the bearing cap concentrically to it, and such an arrangement - near the source of disturbing force - provides the most effective damping of vibrations. The adjusting weights that the plate is equipped with allow for the most accurate adjustment of the DHA to the quenching frequencies. Rigid attachment of the damper to the extinguishing facility ensures the reliability of the DHA.

The experimentally obtained data, confirmed by the test reports, show that it is precisely with the values of the parameters h (thickness) and 1 (width) of the plate, calculated according to the above formulas, that the vibration of the support of the rotor of the turbine unit is effectively damped simultaneously at two frequencies ω ₁ and ω ₂ .

The value of ω is known from the source data. The average radius of the half ring R is set based on the structural dimensions of the location of the damper, and also taking into account the requirement that the half ring is located as close as possible concentrically to the bearing support cover.

The support structurally includes the following components: a frame mounted on the foundation, a bearing with a liner, and a bearing cover. Accordingly, the mass of the support m is defined as the sum of the mass of the frame, the mass of the bearing with the liner and the mass of the cover, which are known for each particular structure of the support.

The speed of sound propagation in the plate material (s) and the specific gravity of the plate material (γ) are known reference data.

The form of execution of the plate (in the form of a half ring), the geometry of the plate (thickness h and width 1, calculated according to the above formulas), the properties of the plate material (sound propagation velocity in the plate material c and the specific gravity of the plate material γ) together provide effective damping of the support vibrations the turbine unit at two frequencies simultaneously without reconfiguring the quencher, which is confirmed by the available test protocols for DHA.

Figure 1 presents a General view of a dynamic vibration damper mounted on a support of a turbine unit.

DHA contains a plate 1 made in the form of a half ring and mounted on a support 2 of a turbine unit. The support 2 consists of a frame 3 mounted on a foundation, a bearing 4 with a liner, and a bearing cover 5. The plate 1 is rigidly fixed with its ends 6 and 7, for example, made in the form of flanges, on the support 2, namely, on the surface of the bearing cover 5 with bolt connections 8, which ensure reliable fastening of the plate 1. A half-shaped plate 1 is mounted concentrically to the cover 5 bearings, which allows you to place the DHA in a limited space between the bearing cap and the turbine cylinder body, and the same location of the damper determines the choice of the average radius of the half ring. Adjusting weights 9 are installed on the plate 1, which are, for example, a set of metal plates designed to fine tune the damper to the vibration damping frequencies of the support by adjusting the mass.

The value of the average radius R of the half ring is determined based on the design features of a particular support. Referring to FIG. the parameters h and 1 are determined according to the above empirical dependencies.

A dynamic vibration damper, consisting of a plate 1 and adjusting weights 9, is mounted on the cover 5 of the bearing 4 and is rigidly fixed to the damping object using bolted joints 8. The frequency of the disturbing force acting from the turbine and / or generator coincides with the natural frequency of the support structure , causes a resonance of the vibrations of the support. Upon the occurrence of resonant vibrations of the support 2, the attachment of the DHA to the support forms such a resultant system that has antiresonance at the frequency of the disturbing force, which is characterized by the formation of a reaction force damper equal in magnitude to the disturbing force and oppositely directed, which ensures vibration damping. Further, comparing the measured minimum steady-state vibration value on the support with the required value allows us to conclude that it is necessary to additionally configure the DHA by adding or removing adjusting weights 9 to obtain the required vibration values.

Plate 1 can be made, for example, of steel, Art. 3 GOST380-2005. The mass of the plate will be such that the moment of inertia created by it will be sufficient to damp disturbing vibrations. For example, for a K-300 steam turbine, the mass of the support m is 10420 kg, ω = 314 s ^-1 , R = 0.5 m, s = 5000 m / s (for steel), γ = 7800 kg / m ³ . With such initial data, substituting all the known parameters into the calculation formulas, we obtain: h = 0.018 m, 1 = 0.927 m. For this DHA, a set of 10 adjusting weights of 2 kg each can be used. Cargoes can also be made of steel Art. 3.

Claims (1)

A dynamic vibration damper of the support of the turbine unit, comprising a plate with adjusting weights installed on it, characterized in that the plate is curved in the shape of a half ring, both ends of the plate are rigidly fixed to the support of the turbine unit, while the plate parameters - thickness h and width l - are determined from the relations: h = 1,17ωR ² / s, m, l = 5.45 · 10 ^-3 mc / γωR ³ , m, where ω is the nominal circular frequency of rotation of the rotor of the turbine unit, s ^-1 ; R is the average radius of the half ring, m; m is the mass of the support, kg; C is the speed of sound propagation in the plate material, m / s; γ is the specific gravity of the plate material, kg / m ³ .