JP3595356B2 - Steam turbine plant - Google Patents

Description

[0001]
[Industrial applications]
TECHNICAL FIELD The present invention relates to a steam turbine plant for reducing a shaft vibration by increasing rigidity of a low pressure steam turbine outer casing having a pedestal structure.
[0002]
[Prior art]
4 and 5 are a plan sectional view and a side sectional view schematically showing a shaft end of a conventional low-pressure steam turbine.
In the drawing, the shaft end sides of two low-pressure steam turbine rotors 11A and 11B installed adjacent to each other are journal bearings 13A and 13A installed on outer casings 12A and 12B of a pedestal structure (12C and 12D are pedestal portions). 13B. The shaft ends of the two low-pressure turbine rotors 11A and 11B are rigidly connected by a coupling 14. A thrust bearing 15 is provided at the center of the coupling 14.
During operation of the low-pressure steam turbine, the exhaust chamber 16 communicates with a condenser (not shown) provided at a lower part, and applies a vacuum load when the condenser is evacuated. Further, between the two low-pressure outer casings 12A and 12B, both sides are connected to the centers of the rotors 11A and 11B by tie beams (not shown), and the heat expansion of the outer casings 12A and 12B is made parallel to the axis. I miss it.
[0003]
[Problems to be solved by the invention]
As the size of the steam turbine increases, the outer casings 12A and 12B of the low-pressure steam turbine also increase in size. Therefore, in the pedestal-structured vehicle room in which the bearings are supported on the outer vehicle rooms 12A and 12B as described above, the strength of the dynamic rigidity of the vehicle room is greatly related to the sensitivity of the shaft vibration. It has been found that the vibration of the shaft vibration is greatest near the rotor shaft, that is, on a horizontal plane passing through the axis of the rotor shaft.
Conventionally, as measures against the vibration of the steam turbine, measures have been taken to increase the rigidity of the cabin itself by increasing the thickness of the cabin and attaching ribs and beams to the cabin of the steam turbine. However, this involves problems such as an increase in weight, man-hours, and cost.
As a result of the measurement of bearing stiffness, an axial bearing pedestal vibration mode is detected, and as a result of vibration measurement, when the shaft vibration is large, the vibration in the axial direction of the outer casing, particularly the inward vibration from the stationary state of the casing is large. It turned out to be.
In a steam turbine having a pedestal structure, the present invention was invented by paying attention to the fact that a pedestal portion was installed in an outer surface of an outer casing and in an axial direction, thereby solving the conventional problem. is there.
[0004]
[Means for Solving the Problems]
For this reason, the present invention provides a pedestal- structured steam turbine that is arranged adjacent to each other in the axial direction, and has reinforcing plates at left and right positions of the rotor shaft on a horizontal plane passing through the axis of the rotor shaft of the facing pedestal portion. The pedestal part of the opposing pedestal parts is formed as a unitary structure by passing and mounting the pedestal part.The central part of the pedestal part of the united structure is located on the horizontal plane passing through the axis of the rotor shaft. those with composed so as to be positioned left and right, it is an unit for which a problem solution.
[0005]
[Action]
In the present invention, the two opposing pedestal parts are connected in the axial direction by the reinforcing plate, and the outer casing is connected to the left and right sides of the shaft on the horizontal plane passing through the axial center line in place of the pedestal parts, so that the The support rigidity is enhanced, the response sensitivity is reduced, and the vibration itself is reduced. According to the examination results, the rigidity is increased by the attachment of the reinforcing plate and the vibration response during the specified rotation is reduced. %Decrease.
In the present invention, the support rigidity of the vehicle compartment having a pedestal structure in which the bearing is supported by the pedestal portion outside the outer vehicle compartment is enhanced. As a result, the response sensitivity to shaft vibration is reduced, and the shaft vibration itself is also reduced. Therefore, the reliability of the steam turbine is further improved.
[0006]
【Example】
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the embodiments of the drawings. FIGS. 1 to 3 show one embodiment of the present invention, and FIG. 1 is a plan view of an end portion of a casing shaft according to the embodiment of the present invention. In the figures, 11A and 11B are turbine rotors, 13A and 13B are journal bearings, 14 is a coupling, and 15 is a thrust bearing, which are the same as the conventional one shown in FIG. 4 and FIG.
4A and 4B are two low-pressure outer casings installed adjacent to each other, and are provided with pedestal parts 4C and 4D.
In order to integrate the opposing pedestal parts 4C and 4D, in this embodiment, reinforcing plates 1, 1 are passed to the left and right of the rotor shaft on a horizontal plane passing through the axis of the rotor shaft, and bolts are provided on both sides. The pedestal portions 4C and 4D are connected by tightening, and the pedestal portions 4C and 4D are integrated.
[0007]
FIG. 2 is a perspective view of the reinforcing plate 1. A bolt hole 2 for attaching the reinforcing plate is formed in the width direction of the reinforcing plate 1, and two ribs 3 are attached to a lower surface of the reinforcing plate 1 by welding in a longitudinal direction.
In another embodiment, the ends of the pedestal portions facing each other may be shaped to have arms extending to the center of both turbines, and the two arms may be connected by bolting or the like during assembly.
In addition, without being limited to the pedestal portions 4C and 4D, the outer casings 4A and 4B are not limited to the pedestal portion as long as they are connected to each other on the horizontal plane passing through the axis of the rotor shaft. The matching outer casings may be directly connected using a reinforcing material or the like. Further, in each of the embodiments described above, the joining method is not limited to bolting, but may be welding or other joining means.
[0008]
【The invention's effect】
As described above in detail, according to the present invention, the support rigidity of the pedestal-structured vehicle compartment in which the bearing is supported by the pedestal portion outside the outer vehicle compartment is enhanced. As a result, the response sensitivity to shaft vibration is reduced, and the shaft vibration itself is also reduced. Therefore, the reliability of the steam turbine is further improved.
[Brief description of the drawings]
FIG. 1 is a plan sectional view of a low-pressure outer casing in a steam turbine plant according to an embodiment of the present invention.
FIG. 2 is a perspective view of a reinforcing plate used in FIG.
FIG. 3 is a plan view of a main part in FIG. 1;
FIG. 4 is a sectional plan view of a low-pressure outer casing in a conventional steam turbine plant.
FIG. 5 is a side sectional view of FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reinforcement plate 2 Bolt hole 3 Rib 4A, 4B Low-pressure outer casing 4C, 4D Pedestal part 11A, 11B Turbine rotor 13A, 13B Journal bearing 14 Coupling 15 Thrust bearing

Claims (2)

In a steam turbine having a pedestal structure that is arranged so as to be adjacent to each other in the axial direction, a reinforcing plate is attached to the left and right positions of the rotor shaft by mounting them on a horizontal plane passing through the axis of the rotor shaft of the facing pedestal portion. , the steam turbine plant pedestal of each other facing is characterized by a structure composed integrally. 2. The steam turbine plant according to claim 1, wherein the central portion of the pedestal portion of the integrated structure is located on the left and right sides of the rotor shaft on a horizontal plane passing through the axis of the rotor shaft. 3.

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