JPH0476569B2 - - Google Patents

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention is directed to the prevention of abnormal axial vibration of a rotating shaft in a rotating machine such as a steam turbine generator, or the axial direction during an earthquake. The present invention relates to an axial vibration detection and diagnosis device for a rotating shaft that directly measures the vibration acceleration of a vibration response, determines whether the vibration acceleration is higher than a set value, and generates an alarm signal when the vibration acceleration is higher than the set value.

(Conventional technology) Conventionally, power plants equipped with steam turbine generators, such as nuclear power plants and thermal power plants, have been constructed after conducting safety evaluations based on seismic design, and have been designed to prevent various accidents from occurring due to earthquakes. It is operated to reduce or prevent damage accidents due to the activation of the protection system. These power plants employ two types of methods: a method of detecting the seismic response of the entire structure using a seismometer, and a method of detecting vibrations of the rotating shaft. Furthermore, methods for detecting vibrations of the rotating shaft include
A method of detecting the absolute vibration in the radial direction of the rotating shaft in a bearing that supports the rotating shaft using a vibrating bar equipped with a velocity vibration meter, and a non-eddy current method that detects the relative vibration between the bearing and the rotating shaft. method using a contact displacement meter,
Furthermore, we selectively adopt methods such as indirect vibration detection in the rotating shaft support system by measuring the vibration acceleration or velocity of the bearing stand, and use the response limit value of the seismograph and the rotating shaft vibration limit value to detect generator emergencies. It's starting to stop.

(Problems to be Solved by the Invention) By the way, in these structures, seismic force tends to act in an unfavorable direction where the restraint force is low, and earthquakes occur when the steam turbine generator is operating, and the seismic force When the maximum horizontal motion coincides with the direction of the rotating shaft, the thrust bearing installed in the steam turbine generator directly receives the thrust force accompanying the operation of the rotating shaft as well as the inertial energy of the rotating shaft due to the horizontal motion of the earthquake. Because these combined thrust forces have a phase with the horizontal motion of the earthquake, the behavior of the rotation axis becomes extremely complex. In past earthquakes, the maximum horizontal acceleration measured by seismographs has been approximately 0.16 to 0.5G at magnitudes 6 to 8. Therefore, as the weight of the rotating shaft increases, the inertial energy increases and the thrust bearing becomes more susceptible to damage. On the other hand, safe operation of steam turbine generators is necessary in terms of energy supply to facilitate social life and industrial operations. Therefore, the problem has been how to accurately detect axial vibrations and how to handle them in order to prevent damage to steam turbine generators in the event of an earthquake.

Further, even if the detection is performed with high accuracy in a rotating system, there will be a problem if the signal transmission means for transmitting the detected information to the stationary side is not highly accurate. For example, an FM transmitting/receiving device is known as a means of transmitting signals from a rotating body to a stationary body, but the electric field strength generated by the magnetic field generated by the transmitter antenna and receiver antenna of this device is such that if the distance between them is too close, the magnetic field will increase. They tend to be non-uniform, and if they are too far apart, they are susceptible to the effects of the radiated electric field, reducing the field strength, increasing the distortion rate of the transmitter, decreasing the signal-to-noise ratio, and decreasing accuracy.

Also, the temperature of the steam turbine is approximately 600 degrees, and the pressure is 200 degrees.
Since it handles steam of kg/ ^cm2 or more, it has heat, and when using an FM transmitter/receiver as a means of signal transmission, it was necessary to make the FM transmitter detachable.

The present invention was made in consideration of the steam situation, and detects the axial vibration of the rotating shaft of a steam turbine generator, etc. as accurately as possible, and detects abnormal vibrations in the rotating shaft direction and rotation due to earthquake response. It is an object of the present invention to provide an axial vibration detection and diagnosis device for a rotating shaft that can contribute to preventing damage to the thrust bearing of the shaft and damage to the rotating machine.

[Structure of the invention]

(Means for Solving the Problems) A diagnostic device for detecting and diagnosing axial vibration of a rotating shaft according to the present invention is installed at the center of the output end of a rotating shaft of a steam turbine generator, and detects acceleration of axial vibration of the rotating shaft. A vibration detector to be detected and a recess provided in a flange on the output end side of the rotating shaft opposite to the joint surface of the flange are removably attached to the vibration detector, and the vibration detector frequency modulates the detection signal of the vibration detector. an FM transmitter for transmitting data; an FM receiver provided in a stationary part for receiving the signal transmitted from the FM transmitter and converting it into a voltage change signal; The present invention is characterized by comprising: signal processing means for determining whether the vibration acceleration of the axial vibration is equal to or higher than a set value, and generating an alarm signal when the vibration acceleration is equal to or higher than the set value.

(Function) According to the axial vibration detection and diagnosis device of the present invention configured as described above, the acceleration of the axial vibration of the rotating shaft is detected by the vibration detector attached to the center of the output end of the rotating shaft. , and in the recess provided on the surface opposite to the joint surface of the flange on the output end side of the rotating shaft.
The FM transmitter is removably installed. Thereby, the axial vibration of the rotating shaft can be detected with high accuracy. At this time, if the acceleration is α, the load applied to the thrust bearing of the rotating shaft during normal operation is F _S , the variable load due to vibration acceleration α is F _I , and the weight of the rotating shaft is W _T , then _FI = W _Therefore , the thrust bearing maximum load F _T is F _T = F _S +
Become _FI . Here, let P _a be the short-term local permissible surface pressure of the metal of the thrust bearing, that is, the yield point of the metal at the surface temperature of the thrust bearing metal, and A be the effective area of the bearing lubricating oil, which is determined for each bearing type and rotating machine type. If the oil film pressure coefficient is β, the stress generated in the thrust bearing metal is F _T ×β/
If A<P _a , the stress is below the allowable stress, and F _T ×β/
If A≧P _a , the stress is greater than the allowable stress.

Therefore, the signal processing means determines that a signal of vibration acceleration α such that the stress generated in the thrust bearing metal exceeds the allowable stress is dangerous, and generates an alarm signal.

(Example) FIG. 2 is an installation position diagram when a vibration detector and a signal transmission means are installed in a steam turbine generator. The steam turbine 1 includes a high and intermediate pressure turbine 2, a low pressure turbine 3, a generator 4, an exciter 5, a rotating shaft 6,
It is equipped with journal bearings 7 _a , 7 _b , 7 _c , 7 _d and a thrust bearing 8 . Further, a vibration detector 9 for detecting acceleration in the axial direction of the rotary shaft is provided at the center of the rotary shaft joint in the middle of the rotary shaft 6 or in the rotary shaft center hole at the end of the rotary shaft. This vibration detector 9 is the exciter 5
It is connected to a signal transmission means (the spring device 10 in this figure) that transmits electrical signals between the rotating part and the stationary part.

FIG. 3 is a longitudinal sectional view showing the structure of one embodiment of the vibration detector 9. This vibration detector 9 includes a vibration accelerometer 9 _a , an electrical insulating material 9 _b , a protective case 9 _c , a ring 9 _d , an axial thrust ring 9 _e , an axial center position adjustment sleeve 9 _f , a cover 9 _g , input/output It is provided with a wiring 9 _h and a main body case 9 _p , and is incorporated into the center hole 6 _a of the rotating shaft 6. The mounting direction of the vibration accelerometer 9 _a built into the vibration detector 9 is such that the axis of the vibration accelerometer 9 _a in the acceleration response direction indicated by the arrow 6 _b in the figure coincides with the center line of the rotating shaft. This is because movable parts such as the vibrator weight or movable coil that respond to external forced vibration displacement in the vibration accelerometer are affected by uneven distribution of centrifugal force due to the rotation of the rotating shaft, which hinders movement in the detection direction. In other words, the vibration accelerometer 9a is mounted so as to be symmetrical with respect to the rotational axis, thereby preventing contact between the movable part and the stationary part of the vibration accelerometer _9a . This vibration accelerometer _9a is integrally molded and incorporated into a protective case _9c using an electrical insulating material _9b . These further include two rings 9 _d with a wedge cross section, an axial thrust ring 9 _e , and a sleeve 9 _f for adjusting the axial center position in the radial direction of rotation.
The entire vibration detector is assembled in the main body case _9p . A cover 9 _g is assembled on the end face of the main body case 9 _p , a hole 9 _i is provided for the input/output wiring 9 _h of the vibration accelerometer 9 _a , and a space 9 _j is provided for input/output wiring of the accelerometer 9 _a . Wiring 9 _h is injected with foam molding material to prevent bending and play, and is filled and molded. Accelerometer 9 installed as above
In _a , assembly fine adjustment is carried out in the operable rotational speed range of the rotary shaft during and after the assembly is completed;
It has been confirmed that it has high precision response sensitivity and reliability to external forced vibration displacement input, and is put into practical use, and is assembled to the rotating shaft 6 with bolts _9k .

In FIG. 4, an FM transmitter and a receiver are used as the signal transmission means, and power transmitted from the stationary side by electromagnetic induction is used as the operating power source for the FM transmitter, receiver, and vibration detector. It is a block diagram of a vibration detector and a signal transmission means when used,
Figure 5 is an assembly diagram of the FM transmitter and vibration detector mounted on the rotating shaft. The induction power supply device 11 generates a magnetic field by passing a current through a stationary coil _11a , and places the rotating coil ₁ on the outer peripheral surface of a rotating shaft that is attached at a position relative to the stationary coil 11a.
2 Induce a voltage at _a . The voltage regulator 12 includes a vibration detector 9, an amplifier 13 for amplifying the detection signal, a signal conditioner 14,
It converts into a smooth constant voltage that operates the FM oscillator 15 and supplies it. On the other hand, the vibration detector 9 functions in response to the applied voltage input supplied from the amplifier 13 and outputs vibration acceleration in the direction of the rotation axis as a voltage change signal, which is amplified by the amplifier 13. This amplified signal is then converted by the signal conditioner 14 into a frequency standard signal corresponding to the voltage change, and is input to the FM oscillator 15.
Furthermore, an FM oscillator 15, an antenna antenna _15a ,
The stationary side antenna 16 _a and the FM receiver 16 make it possible to transmit and receive signals from the rotating body. Then, the FM receiver 16 converts it into a voltage change signal again, and transmits it to the signal transmission means 17.

In this case, a vibration detector 9 for detecting acceleration in the axial direction of the rotating shaft of the steam turbine generator is installed in a center hole 50a at the output end of the rotating shaft 50 of the steam turbine, as shown in FIG. The FM transmitter, which includes a voltage regulator 12, an amplifier 13, a signal contamination unit 14, and an FM oscillator, is connected to a flange on the output end side of the steam turbine rotating shaft 50 and on the input end side of the generator rotating shaft. Flange 6
A recess 50 provided on the side opposite to the joint surface with 0
It is removably attached to c. By doing so, the influence of disturbance (noise) can be minimized, and axial vibrations can be detected with high accuracy.

FIG. 1 is a block diagram showing an embodiment of an axial vibration detection and diagnosis device for a rotating shaft according to the present invention.

The operating power supply and output signal transmission of the vibration detector 9 provided in the center hole at the end of the rotating shaft 6 are carried out by a slip ring 10 that transmits electrical signals between the rotating part and the stationary part. This is done by electrically wiring the detection signal processing section _17a of 17. The detection signal processing unit 17 _a supplies operating power to the vibration detector 9 and at the same time converts the detected vibration acceleration signal into a speed signal and a displacement signal.
The display _17b functions to display the above-mentioned signal as a numerical value for each detection process. On the other hand, this detection signal processing section _17a is connected to a discriminator _17c , and further connected to a data recorder _17d .
The discriminator _17c has a function of instructing the data recorder _17d to start and end input recording of the detected vibration acceleration signal, and has a preset partition value of the vibration acceleration signal and a built-in The signal waveform storage delay circuit in the system enables continuous input recording from a certain period of time before the start of input recording, and automatically records vibration acceleration signals exceeding the above-mentioned partition value. On the other hand, the detection signal processing section _17a is connected to the arithmetic processing section _17e . Then, the arithmetic processing unit 17 _e performs frequency analysis using a built-in fast Fourier transformer using the rotation signal from the rotation signal generator 18 as a reference, and compiles it into power spectrum data. Calculate the acceleration, velocity, displacement, maximum value of vibration amplitude, rate of change in vibration amplitude, etc. Information on the results of these vibration detection processes and calculations is input to the abnormality diagnosis section _17f and the comparison/judgment device _17g .
The abnormality diagnosis unit _17f then uses the above information and information on the axial vibration of the rotating shaft based on safety for each operating state, which is previously input and stored in the storage unit _17h in the same way as the above information. The vibration information at the time of occurrence of various abnormal axial vibrations, the simulated signal information at the time of earthquake response, etc. are compared in an input/output interactive format with the comparison/judgment device _17g , and the cause of the vibration is diagnosed based on the vibration symptoms. The storage unit 17 _i stores these abnormality diagnosis results and functions similarly to the storage unit 17 _h . Also, on the other hand,
The abnormality diagnosis unit _17f compares the detection signal of the seismometer 19 installed in the power plant with the detection signal of vibration in the direction of the rotation axis, and determines whether an earthquake has occurred depending on whether or not an earthquake has occurred at the seismometer 19. Directly determine when an earthquake is not occurring. The arithmetic unit 17 _i is the arithmetic processing unit 1
7. Calculate the variable load in the rotational axis direction due to the vibration acceleration in the rotational axis direction obtained from _e , add the thrust bearing load during normal operation, and compare it with the short-term local surface pressure of the white metal of the thrust bearing. , determine the occurrence of damage and danger to thrust bearings. If a judgment result is obtained that the overload is dangerous, the alarm _17k will display this judgment result, and at the same time, the various protections installed to prevent accidents and damage to rotating machinery will be displayed. Activate the system.

〔Effect of the invention〕

The axial vibration detection and diagnostic device for a rotating shaft according to the present invention includes a vibration detector that is attached to the center of the output end of the rotating shaft of a steam turbine generator to detect acceleration of axial vibration of the rotating shaft, and an output of the rotating shaft. an FM transmitter that is detachably attached to a recess provided on the opposite surface of the end flange to the joint surface of the flange and transmits the frequency-modulated detection signal of the vibration generator; An FM receiver receives the signal sent from the FM transmitter and converts it into a voltage change signal, and based on the output of this FM receiver, it is determined whether the vibration acceleration of the axial vibration of the rotating shaft is greater than a set value. By including a signal processing means that generates an alarm signal when the value exceeds a set value, it is possible to minimize the influence of disturbances and reduce axial vibration of the rotating shaft during rotation. It can be detected with high accuracy, and an alarm signal is generated when this axial vibration exceeds a set value, so it is possible to prevent damage to the thrust bearing of the rotating shaft and rotating machinery due to the occurrence of abnormal vibration in the direction of the rotating shaft and earthquake response. This can contribute to the prevention of damage.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the axial vibration detection and diagnosis device for a rotating shaft according to the present invention, and FIG. 2 is a position diagram when the vibration detector and signal transmission means are attached to a steam turbine generator. Fig. 3 is a longitudinal cross-sectional view showing one embodiment of the vibration detector, and Fig. 4 shows the vibration when power transmitted from the stationary side by electromagnetic induction is used as the signal transmission means and the operating power source of the vibration detector. Figure 5 is a block diagram of the detector and signal transmission means.
It is an installation diagram when an FM oscillator and a vibration detector are attached to a rotating shaft. 9...Vibration detector, 10...Slip ring,
15...FM oscillator, 16...FM receiver, 17
...Signal processing means.

Claims (1)

[Scope of Claims] 1. A vibration detector installed at the center of the output end of the rotating shaft of the steam turbine generator to detect the acceleration of axial vibration of the rotating shaft; and a flange on the output end side of the rotating shaft. , an FM transmitter that is removably attached to a recess provided on a surface opposite to the joint surface of the flange and that frequency modulates and transmits the detection signal of the vibration detector; and an FM transmitter that is provided on a stationary part and transmits a signal from the FM transmitter. An FM receiver that receives the transmitted signal and converts it into a voltage change signal; Based on the output of this FM receiver, it is determined whether the vibration acceleration of the axial vibration of the rotating shaft is greater than or equal to a set value, and the set value is determined. A diagnostic device for detecting and diagnosing axial vibration of a rotating shaft, comprising: signal processing means for generating an alarm signal when the value exceeds a value.