JPH10169407A - Rotor position detector for steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a characteristic straight line of the amount of movement of a turbine rotor to the output of an axial position sensor without moving the turbine rotor and precisely detect the axial position. SOLUTION: A rotor position detector for a steam turbine comprises a bracket 9 having a moving member movable in the axial directrion of a rotor 1 and attached to a casing 3 for housing the rotor 1 of a steam turbine, a sensor 7 attached to the moving member to measure an axial distance from a prescribed part of the rotor 1 and a correcting circuit 10 for correcting the output of the sensor 7 and forming a linear output for the axial distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the axial position of a rotor of a steam turbine in a casing.

2. Description of the Related Art In a steam turbine, it is necessary to detect an axial position of a rotor with respect to a casing in order to prevent a contact accident between the rotor and the casing due to wear of a thrust bearing or the like. Usually, the position of the rotor with respect to the thrust bearing is referred to as the shaft position, but the shaft position can be up to about 1 mm.
Since the steam turbine moves only to the extent and the shaft position generally indicates an abnormal value, the steam turbine is to be stopped immediately, so that a very high detection accuracy is required. The mounting structure of the conventional steam turbine rotor position detecting device is as shown in FIG. That is, a thrust disk 2 is attached to the turbine rotor 1, and a thrust bearing 4 is provided on the casing 3 that houses the turbine rotor 1 so as to sandwich the thrust disk 2. A measurement disk 5 is also attached to the turbine rotor 1, and a casing 3
Is mounted with a shaft position sensor 7 via a sensor mounting bracket 6. An amplifier 8 is connected to the shaft position sensor 7. In such a mounting structure, when the turbine rotor 1 moves in the axial direction, the movement amount appears as the movement amount of the measurement disk 5 in the axial direction. On the other hand, since the shaft position sensor 7 is mounted on the casing 3, the movement amount of the turbine rotor 1 is measured by the measuring disk 5 and the shaft position sensor 7.
It can be measured as a change in the gap length during the period.
Then, the output change of the shaft position sensor 7 is amplified by the amplifier 8 and output to a recorder or a computer. The conventional shaft position sensor is adjusted and calibrated by the procedure shown in FIG. That is, when the shaft position sensor is mounted, the turbine rotor is stopped while being supported by the lower half casing. In this state, the position of the turbine rotor is unknown because the casing has been opened and the shaft position sensor has been removed. As an adjustment procedure at the time of mounting the shaft position sensor, first, the shaft position sensor is mounted on the sensor mounting bracket with a screw or the like (Step S1), and the turbine rotor is moved forward in the axial direction by a hydraulic jack or the like (Step S2). There is a design-defined clearance (design gap) of about 1 mm between the turbine rotor and the casing, and the turbine rotor hits the casing and stops. The movement amount of the turbine rotor at this time is measured with a clearance gauge or the like (step S3). The output value of the amplifier is set based on the measured value (step S4). Next, the turbine rotor is moved rearward in the axial direction (step S5), and the amount of movement of the turbine rotor is measured when the turbine rotor hits the casing (step S5).
6) The output value of the amplifier is set based on the movement amount (step S7). The thus measured two points of turbine rotor axial movement and amplifier output values are plotted on a graph (step S8). What connects these two points with a straight line is the output characteristic of the shaft position sensor and the amplifier (FIG. 7). During the actual operation of the steam turbine, the sensor output is read and converted into the turbine rotor movement amount by the output characteristics of FIG.

As described above, conventionally,
A heavy turbine rotor had to be moved to obtain a characteristic line of shaft position sensor output versus turbine rotor travel. In addition, in the conventional technology, an error of about 0.05 mm occurs when measuring with the gap gauge,
The output characteristics of the axis position sensor and the amplifier rarely fall on the straight line A in FIG. In addition, errors due to the effect of the material of the measuring disk,
Although there are errors due to the influence of the surrounding conductors, errors due to the temperature characteristics of the sensor, and the like, the output characteristics are assumed ignoring them, so that it can be said that an accurate rotor position is not obtained. . Accordingly, the present invention provides a steam turbine rotor position detecting device capable of obtaining a characteristic straight line of shaft position sensor output versus turbine rotor movement amount without moving the turbine rotor and accurately detecting the shaft position. The purpose is to:

According to the present invention, there is provided a steam turbine rotor position detecting apparatus, comprising: a bracket having a movable member mounted on a casing accommodating a rotor of the steam turbine and capable of moving in the axial direction of the rotor; The sensor includes a sensor attached to a member for measuring an axial distance from a predetermined portion of the rotor, and a correction circuit for correcting an output of the sensor to form a linear output for the axial distance. In the rotor position detecting device for a steam turbine according to the present invention, since the shaft position sensor can be moved in the axial direction of the turbine rotor by the moving member, the characteristic straight line between the shaft position sensor output and the amount of turbine rotor movement can be obtained without moving the turbine rotor. Obtainable. Also, since the axial distance between the predetermined position of the rotor and the axial position sensor, which is generally obtained in a non-linear manner due to the aforementioned error, is corrected by the correction circuit, the rotor position can be accurately obtained.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a steam turbine rotor position detecting apparatus according to an embodiment of the present invention is as shown in FIG. That is, the shaft position sensor 7 is mounted on the casing 3 via the sensor mounting bracket 9 so as to face the measurement disk 5 mounted on the turbine rotor 1. The amplifier 8 and the correction circuit 10 are connected to the shaft position sensor 7. The sensor mounting bracket 9 is of a movable type and is shown in an enlarged manner in FIG. That is, the L-shaped member 92 to which the fixed-side sliding plate 91 is fixed is attached to the casing 3, and the moving-side sliding plate 94 to which the L-shaped member 93 holding the shaft position sensor 7 is fixed is fixed to the fixed-side sliding plate 91. Provide in combination. The fixed-side sliding plate 91 and the moving-side sliding plate 94 can be fixed in a predetermined positional relationship by screws or the like. The details of the fixed side sliding plate 91 and the movable side sliding plate 94 are as shown in FIG. That is, a ridge 95 extending in the axial direction of the turbine rotor is formed on the sliding surface of the fixed-side sliding plate 91, and a groove 96 fitted into the ridge 95 is formed on the sliding surface of the movable-side sliding plate 94.
Is formed. According to the sensor mounting bracket 9 having such a configuration, the shaft position sensor 7 can be moved by the pair of sliding plates 91 and 94. Therefore, the measurement disk 5 and the shaft position sensor 7 can be moved without moving the turbine rotor. The gap length between them can be varied. The sensor output can be measured by arbitrarily setting the gap length. The output of the shaft position sensor 7 is amplified by the amplifier 8, corrected for errors by the correction circuit 10, and output to a recorder or a computer. Next, the correction operation of the correction circuit 10 will be described. The output of the shaft position sensor 7 is shown in FIG.
The sensor output characteristic 21 is as shown in FIG. The horizontal axis in this figure is the amount of movement of the shaft position sensor 7 by the sensor mounting bracket 9, and is measured by a scale or a micrometer attached to the fixed sliding plate 91 or the moving sliding plate 94. The abscissa also indicates the amount of movement of the turbine rotor during the actual measurement. In the rotor position detecting device according to the present embodiment, the shaft position sensor can be easily moved, so that many measurement points are taken as shown in the figure, and the sensor output characteristics 21 are obtained by connecting the measured values. The sensor output characteristic 21 is non-linear because it includes various errors due to the influence of the material of the measurement disk 5, the influence of the surrounding conductor, the temperature dependence of the function of the sensor 7, and the like. From the non-linear characteristic and the theoretical linear characteristic representing the relationship between the gap length and the output, the correction circuit 10 obtains and stores an error characteristic 22 shown in FIG. And
The correction circuit 10 adds the sensor output characteristic 21 and the error characteristic 22, and outputs a corrected linear output characteristic 23 shown in FIG. As described above, the rotor position detection device of the present embodiment can obtain measurement data at many arbitrary points, unlike the conventional measurement result in which the measurement data at two points are connected by a straight line and errors are ignored. Therefore, the actual sensor output characteristic 21 including the error can be obtained. And the sensor output characteristic 2
Even if 1 is a non-linear characteristic including an error, it is corrected by the error characteristic held by the correction circuit 10 to form a corrected linear output. Therefore, an output error to a recorder or a computer can be significantly reduced.

As described above, according to the present invention, it is possible to obtain a characteristic straight line between the output of the shaft position sensor and the movement amount of the turbine rotor without moving the turbine rotor, and to accurately detect the shaft position. Can do things.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a steam turbine rotor position detecting device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a sensor mounting bracket according to the embodiment.

FIG. 3 is an enlarged view of a sliding plate in the sensor mounting bracket.

FIG. 4 is a diagram illustrating an operation of the linear correction circuit according to the embodiment.

FIG. 5 is a configuration diagram of a conventional steam turbine rotor position detecting device.

FIG. 6 is a flowchart showing an adjustment procedure of a conventional shaft position sensor.

FIG. 7 is a diagram showing output characteristics of a conventional steam turbine rotor position detecting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Turbine rotor, 2 ... Thrust disk 3 ... Casing, 4 ... Thrust bearing, 5 ... Measurement disk, 6 ... Sensor mounting bracket (fixed type), 7 ... Shaft position sensor,
8 amplifier, 9 sensor mounting bracket (movable type), 10 correction circuit, 21 sensor output characteristics,
22: error characteristic, 23: corrected linear output characteristic, 91:
Fixed-side sliding plate, 92, 93: L-shaped member, 94: Moving-side sliding plate, 95: Mountain, 96 grooves.

Claims (1)

[Claims] A bracket attached to a casing accommodating a rotor of a steam turbine and having a moving member movable in the axial direction of the rotor, and an axial distance between a bracket attached to the moving member and a predetermined portion of the rotor. An apparatus for detecting a rotor position of a steam turbine, comprising: a sensor to be measured; and a correction circuit that corrects an output of the sensor to form a linear output with respect to the axial distance.