CN203022824U - Damping girdle structure of high-load short blade for industrial steam turbine - Google Patents

Abstract

The utility model designs a damping girdle structure of a high-load short blade for an industrial steam turbine. Each blade consists of a blade body, a blade root and an intermediate connector, wherein the whole circle of the blades are uniformly arranged on a rotor along the circumferential direction of the blade root; girdles are arranged on the top of the blade body; the girdles of the two adjacent blades in the circumferential direction are tightly adhered; an axial wedged groove is milled in the matching surface of the two adjacent girdles; a wedged damping block is arranged in the wedged groove; circumferential sealing grooves are respectively formed in the two ends of the bottom of the wedged groove; and a sealing shoulder is arranged on the wedged damping block corresponding to the sealing groove. By using the damping girdle structure of the high-load short blade for the industrial steam turbine, the circumferential length of the wedged damping block can be increased as far as possible under the condition of controlling a wedged angle, and centrifugal force is increased to achieve the damping effect. The shear stiffness of the girdles is high, so that the effect of grouping the blades is achieved, the dynamic stress is effectively reduced, and the intensity vibration performance of the short blade under heavy load and high temperature conditions is realized.

Description

The damping shroud structure of industrial steam turbine high load short blade

Technical field

The utility model relates to steam turbine shroud band field, especially a kind of damping shroud structure of industrial steam turbine high load short blade.

Background technique

Steam turbine is the heat energy of water vapor to be converted into the power equipment of mechanical energy.Industrial steam turbine is the driving arrangement that is mainly used in dragging the industrial fields such as feed water pump, compressor, and its characteristics are that variable working condition is complicated, the rotation speed change scope is large etc.Along with the synthesic gas compressor of petrochemical industry in recent years towards high efficiency, the future development of high parameter, therefore the industrial steam turbine supporting with it also bearing larger challenge, the raising of rotating speed, the increasing of steam load have proposed serious challenge to the Security of blade.

Blade is the meeting vibration-generating under the effect of steam power and self centrifugal force, produces dynamic stress.Especially be in the short blade under high temperature, the high-temperature behavior of material sharply descends, rotating speed is high, steam flow is large, dynamic stress threatens greatlyr than stress at rest, so its intensity and vibration characteristics directly have influence on the steam turbine operation reliability.Security when moving in order to increase blade normally tunes to open resonant frequency or shroud in groups or adds the shroud damping to reduce the dynamic stress of blade.The shroud damping structure is to have groove on shroud, has a damping block to make it produce damping under centrifugal action.This class damping shroud structure blade is existing the application in the large-scale power station steam turbine, but using seldom in industrial steam turbine.Be different from 3000r/min large-scale power station steam turbine, the stress level of the High Temperature High Pressure level short blade of industrial steam turbine is often high 7～8 times than it, and its rotating speed is all more than 10000r/min.Therefore its damping requires highly, and damping block also just needs larger, and the high pressure short blade size is little often, compact structure, therefore the damping shroud for it is designed with very large difficulty.

The model utility content

The purpose of this utility model is to provide a kind of group blade that can play for the deficiency that solves above-mentioned technology, reduces the damping shroud structure of the industrial steam turbine high load short blade of dynamic stress.

In order to achieve the above object, the damping shroud structure of the industrial steam turbine high load short blade that the utility model is designed, blade is comprised of blade, blade root and intermediate connector, whole circle blade is circumferentially evenly to be arranged on rotor by blade root, be provided with shroud at the blade top, circumferentially the shroud on adjacent two blades is close to setting, mills on the fitting surface of adjacent two shrouds and establishes an axial wedge slot, is provided with the wedge shape damping block in wedge slot.

Be respectively equipped with the circumferential seal groove at two ends, wedge slot bottom, be provided with the sealing shoulder with the seal groove corresponding position on the wedge shape damping block.

As optimization, described wedge slot is identical with the angle of wedge size of wedge shape damping block, and the angle of wedge is 10 °-30 °.

The damping shroud structure of the resulting industrial steam turbine high load of the utility model short blade, this structure increase centrifugal force, to play better damping in the situation that control the circumferential lengths of the increase wedge shape damping block that the angle of wedge can be large as far as possible well.The shroud shear stiffness is large, can play the effect of group blade, has more effectively reduced dynamic stress, has satisfied the short blade strength vibration performance under this large load high-temperature.

Description of drawings

Fig. 1 is structural representation of the present utility model;

Fig. 2 is the stressed schematic diagram of wedge shape damping block of the present utility model;

Fig. 3 is the stressed schematic diagram of wedge slot stress raiser of the present utility model.

Embodiment

The utility model will be further described by reference to the accompanying drawings below by embodiment.

Embodiment 1:

As shown in Figure 1, damping shroud 4 structures of the industrial steam turbine high load short blade that the present embodiment is described, blade is comprised of blade 1, blade root 2 and intermediate connector 3, whole circle blade is circumferentially evenly to be arranged on rotor by blade root 2, be provided with shroud 4 at blade 1 top, circumferentially the shroud 4 on adjacent two blades is close to setting, mills on the fitting surface of adjacent two shrouds 4 and establishes an axial wedge slot 6, is provided with wedge shape damping block 5 in wedge slot 6.

Be respectively equipped with circumferential seal groove 7 at wedge slot 6 two ends, bottom, be provided with sealing shoulder 8 with seal groove 7 corresponding positions on wedge shape damping block 5.

As optimization, described wedge slot 6 is identical with the angle of wedge size of wedge shape damping block 5, and the angle of wedge is 10 °-30 °.

As shown in Figure 2, the positive pressure of the sphenoid surface of wedge shape damping block 5 is respectively N1 and N2, and frictional force f, friction factor are μ; The centrifugal force of wedge shape damping block 5 is F; 4 circumferential active forces of shroud are F1.Following formula is arranged:

$f={\mathrm{\&mu;<figure-callout\; id="1"\; label="N"\; filenames="HDA00002787378500011.png"\; state="\{\{state\}\}">N</figure-callout>}}_1={\mathrm{\&mu;<figure-callout\; id="2"\; label="N"\; filenames="HDA00002787378500011.png"\; state="\{\{state\}\}">N</figure-callout>}}_2=\frac{\mathrm{\&mu;F}}{2(\sin \mathrm{\&theta;}+\mathrm{\&mu;}\cos \mathrm{\&theta;})}$

${\mathrm{<figure-callout\; id="1"\; label="F"\; filenames="HDA00002787378500011.png"\; state="\{\{state\}\}">F</figure-callout>}}_1=F\&CenterDot;\frac{\mathrm{\&mu;}+\tan \mathrm{\&theta;}}{2(1+\mathrm{\&mu;}\tan \mathrm{\&theta;})}$

$\mathrm{\&sigma;}=\frac{F}{\mathrm{LH}}\&CenterDot;\frac{{\tan }^2\mathrm{\&theta;}}{\mathrm{\&mu;}+\tan \mathrm{\&theta;}}$

Wherein: σ is that shroud 4 wedge slot 6 bottom stresses concentrate the place because of the additional bending stress of wedge shape damping block 5 effects;

L is the axial length of wedge shape damping block 5;

H is shroud 4 radial heights.

As shown in Figure 3, on wedge slot 6, the four edges position is respectively A, B, C, D, and the AB spacing is a, and the CD spacing is b, and the AD spacing is d, and the ED spacing is c, and the normal force on sphenoid surface is identical with the stressed size of wedge shape damping block 5 sphenoid surface, opposite direction.Size is:

${\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="HDA00002787378500011.png"\; state="\{\{state\}\}">N</figure-callout>}}_1={\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HDA00002787378500011.png"\; state="\{\{state\}\}">N</figure-callout>}}_2=\frac{F}{2(\sin \mathrm{\&theta;}+\mathrm{\&mu;}\cos \mathrm{\&theta;})}$

Calculate and find, working position near the D point, can determine that the additional flexural stress of stress raiser D point (or C point) (not considering the original average tensile stress that just has) is about 1/3 position on AD limit like this:

$\mathrm{\&sigma;}=\frac{F}{\mathrm{LH}}\&CenterDot;\frac{{\tan }^2\mathrm{\&theta;}}{\mathrm{\&mu;}+\tan \mathrm{\&theta;}}$

As seen, the θ value is between 10 °～30 ° the time, and the σ value is little, generally can satisfy requirement of strength.When specific design, choose the value of rational a, b, c, d, H and θ according to the designing requirement of damping and shear stiffness.

Claims (3)

1. the damping shroud structure of an industrial steam turbine high load short blade, blade is comprised of blade, blade root and intermediate connector, whole circle blade is circumferentially evenly to be arranged on rotor by blade root, it is characterized in that being provided with shroud at the blade top, circumferentially the shroud on adjacent two blades is close to setting, mill on the fitting surface of adjacent two shrouds and establish an axial wedge slot, be provided with the wedge shape damping block in wedge slot.

2. the damping shroud structure of industrial steam turbine high load short blade according to claim 1, is characterized in that being respectively equipped with the circumferential seal groove at two ends, wedge slot bottom, is provided with the sealing shoulder with the seal groove corresponding position on the wedge shape damping block.

3. the damping shroud structure of industrial steam turbine high load short blade according to claim 1, is characterized in that described wedge slot is identical with the angle of wedge size of wedge shape damping block, and the angle of wedge is 10 °-30 °.

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