CN104179534A - Large-damping regulating-stage blade for high-pressure and high-rotational-speed industrial steam turbine - Google Patents

Abstract

The high-pressure and high-speed industrial steam turbine designed by the present invention is composed of a rotor, a blade body, a blade root, an anti-vibration piece and a transition section. The blade root and the blade body are connected through the transition section. With its own shroud, the pitch of the shrouds on two adjacent blades in the circumferential direction is an interference fit, the interference degree is a, the blade body is set in the rotor, and passes through the radial line of the blade and the radial line of the rotor groove during assembly. The eccentricity makes it fit into the rotor; a wedge-shaped groove is provided at the position of the transition section, and an anti-vibration plate is arranged in the wedge-shaped groove. The main feature of this structure is to ensure that the blade shroud can be installed smoothly under the condition of interference through the processing technology. The value of the interference can be controlled and safe through detailed analysis, and the anti-vibration plate is precisely designed. Ensure the damping effect and effectively reduce the dynamic stress.

Description

Large damping regulating stage blades for high pressure and high speed industrial steam turbines

technical field

The invention relates to the field of large-damping regulating-stage blades of industrial steam turbines, in particular to a large-damping regulating-stage blade type for high-pressure and high-speed industrial steam turbines.

Background technique

Industrial steam turbines are driving equipment mainly used to drive feed water pumps, compressors and other industrial fields. The compressor mainly improves the efficiency by increasing the rotating speed, so the industrial steam turbine matched with it is also required to be high temperature, high pressure and high rotating speed. The increase of speed, the increase of steam load, and the safety of the blades in the high temperature and high pressure area are facing serious challenges. There are many fracture accidents of the regulating stage blades in this harsh environment at home and abroad.

Under the action of alternating steam force, the blade will produce dynamic stress and fatigue damage. Especially for short blades at high temperature, the mechanical properties of the material drop sharply, the speed is high, the steam flow rate is large, and the dynamic stress is more threatening than the static stress. Therefore, its strength and vibration characteristics directly affect the operation reliability of the steam turbine. In order to increase the operational safety of the blades, for non-frequency-regulated blades, a damping structure is usually added to reduce the dynamic stress of the blades. The shroud is installed eccentrically to ensure that it produces a pre-tightened damping effect under the action of centrifugal force to increase damping and reduce the dynamic stress of the blade profile. The transition section of the blade root uses a vibration-stopping structure to increase damping and reduce the dynamic stress of the blade root.

Contents of the invention

The purpose of the present invention is to provide a high-pressure and high-speed industrial steam turbine with a large damping adjustment stage blade that can act as a full-circle damping blade and reduce the dynamic stress of the blade profile and blade root in order to solve the above-mentioned technical deficiencies.

In order to achieve the above-mentioned purpose, the high-pressure and high-speed industrial steam turbine designed by the present invention is composed of a rotor, a blade body, a blade root, a vibration damping plate and a transition section, and the blade root and the blade body are connected through the transition section. There is a self-contained shroud on the top of the blade body. The pitch of the shrouds on two adjacent blades in the circumferential direction is an interference fit. The degree of interference is a. The eccentricity of the radial line of the wheel groove makes it fit into the rotor; a wedge-shaped groove is provided at the position of the transition section, and a vibration-stopping sheet is arranged in the wedge-shaped groove.

In order to ensure the circumferential rigidity and provide axial damping to reduce the dynamic stress, and at the same time ensure that the anti-vibration plate is not thrown out under the combined action of centrifugal force and temperature, the interference fit degree is a, and the bottom of the blade root and The gap between the rim is b, the gap between the top of the blade root and the rim is c, and the radial radial line of the blade root is offset by an angle β1 relative to the radial radial line of the rim, where a=0.02~0.08mm; b= 0.1~0.2mm; c=0.1~0.2mm; β ₁ =0.35~0.77°.

The main feature of the high-pressure and high-speed industrial steam turbine designed by the present invention is to use the large damping adjustment stage blade. The main feature is to ensure that the shroud of the blade can be installed smoothly under the condition of interference through the processing technology, and the magnitude of the interference can be controlled through detailed analysis. , Safety range, and precisely designed the damping plate to ensure the damping effect and effectively reduce the dynamic stress. At the same time, the values of a, b, c, and _β1 are well selected through calculation and design, as well as the value of θ of the vibration damper. When these parameters are well controlled, the safety can be guaranteed under the premise of a large damping effect.

Description of drawings

Fig. 1 is a schematic diagram of the shroud structure of the present invention.

Fig. 2 is a schematic diagram of the force acting on the wedge-shaped damping block of the present invention.

Fig. 3 is a three-dimensional schematic diagram of the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings.

Example 1.

The high-pressure and high-speed industrial steam turbine described in this embodiment uses a large damping adjustment stage blade, as shown in Figure 3, the blade is composed of a blade body 1, a blade root 2 and a transition section 3, and the entire circle of blades is uniformly installed circumferentially by the blade root 2 on the rotor. As shown in Figure 1, there is a shroud on the top of the blade body 1, and the upper shrouds of two adjacent blades in the circumferential direction have an interference amount. This is accomplished by offsetting the radial radial line of the rim by a small angle β ₁ . After repeated calculation and optimization of the surrounding band damping structure by finite element, reasonable parameter values are given:

a=0.02~0.08mm;

b=0.1~0.2mm;

c=0.1~0.2mm;

β ₁ =0.35~0.77°.

Two blades are milled with an axial wedge-shaped groove at the position of the transition section 3, and a vibration-stopping plate 4 is arranged in the wedge-shaped groove. The damping structure of the damping plate, as shown in Figure 2, the positive pressure of the wedge-shaped surface of the wedge-shaped vibration plate 4 is N1 and N2, the friction force f ₁ and f ₂ , and the friction coefficient is μ; the centrifugal force of the wedge-shaped vibration plate 5 for F. Has the following formula:

                                                

It can be seen that if the value of θ is too large, it will self-lock and the circumferential force will be small; if it is too small, F will be too small, and the circumferential force will be small; after optimization, it is more reasonable to obtain a value of θ between 8° and 12°.

Claims (2)

1. A large-damping regulating stage blade for high-pressure and high-speed industrial steam turbines, consisting of a rotor, a blade body, a blade root, a vibration damper and a transition section, and is characterized in that the blade root and the blade body are connected through a transition section, and at the top of the blade body There is a self-contained shroud, and the pitch of the shrouds on two adjacent blades in the circumferential direction is an interference fit, the interference degree is a, the blade body is set in the rotor, and radiates through the blade radiation line and the rotor wheel groove during assembly. The eccentricity of the line makes it fit into the rotor; there is a wedge-shaped groove at the position of the transition section, and a vibration-stopping sheet is arranged in the wedge-shaped groove. 2. The high-pressure high-speed industrial steam turbine large-damping regulating stage blade according to claim 1 is characterized in that the interference fit of the described interference fit is a, the gap between the bottom of the blade root and the wheel rim is b, and the gap between the top of the blade root and the wheel rim is b. The gap of the edge is c, and the radial radial line of the blade root is offset by an angle β1 relative to the radial radial line of the rim, where a=0.02~0.08mm; b=0.1~0.2mm; c=0.1~0.2mm; β ₁ =0.35~0.77°.