JPH0833100B2 - Love check device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a love check device.

(Prior Art) A turbine used in a power plant or the like is rotated by blowing high-temperature steam onto a moving blade (blade). The rotor blades are planted in the turbine rotor, and the rotors and rotor blades are mounted inside the casing.

Further, the high-temperature steam that has rotated the turbine passes through the inside of the casing and is discharged to the outside, and the rotor, rotor blades, and casing are expanded by the high-temperature steam.

At this time, depending on the expansion state of the rotor, the moving blades, and the casing, the moving blades and the casing may come into contact with each other. This state is called a rubbing state.

If such rubbing occurs, the blades and casing in contact with it will be damaged.Therefore, the presence or absence of this rubbing is detected at a low rotational speed before the turbine rotational speed rises, and the turbine is damaged by the rubbing. Need to be minimized.

Such detection of the presence or absence of rubbing is called a love check. When rubbing is being generated, a unique sound is generated from the turbine casing, so stop steam once,
The sound generated from the turbine casing is detected.

The love check is performed by a human being visually checking the sound generated inside the casing to detect a rubbing sound or using a love check device.

 A conventional example of the love check device is shown in FIG.

In the figure, the turbine casing 1 is provided with a large number of acceleration detectors DA1, DA2, DA3, ... At appropriate positions for detecting vibrations caused by the sound generated by the turbine casing 1. , Those acceleration detectors DA1, DA2,
The detection signals of DA3, ... Are added to the comparator 3 via the bandpass filter 2 that passes only the components of the frequency band of the rubbing sound.

The comparator 3 compares the reference value preset by the presetter 4 with the value of the signal added from the bandpass filter 2, and when the latter becomes larger than the former, outputs the alarm signal AL to the alarm circuit 5. .

As a result, an alarm is output that the rubbing has occurred in the turbine casing 1.

(Problems to be solved by the invention) However, the frequency band of the rubbing sound is 1 to 3 KHz, and if a sound source (for example, sound) in this frequency band exists near the turbine casing 1, it is erroneously determined that rubbing occurs. That caused the inconvenience.

The present invention has been made in order to eliminate the inconvenience of the conventional technique, and an object of the present invention is to provide a love check device capable of suppressing erroneous determination of rubbing occurrence and reliably detecting rubbing occurrence.

[Structure of the Invention] (Means for Solving Problems) The present invention calculates the characteristics of vibration occurring in a turbine casing, compares the calculation result with the characteristics of vibration when rubbing occurs, and compares the results. The occurrence of rubbing is determined based on

(Operation) As a result, even if a sound source in the frequency band of the rubbing sound exists near the turbine casing, the rubbing can be reliably detected without making an erroneous determination that the rubbing has occurred.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a love check device according to an embodiment of the present invention.

In the figure, the turbine casing 10 is provided with acceleration detectors D1 to Dn, which are n vibration detecting means, at appropriate positions. The acceleration detectors D1 to Dn are for detecting vibrations generated in the turbine casing 10 due to a sound or the like generated inside the turbine casing 10,
The detection signal is input to the electronic computer 11.

In the electronic computer 11, the input processing device 11a converts the detection signals of the acceleration detectors D1 to Dn into digital signals and inputs the digital signals. The arithmetic processing device 11b stores the detection signals (digital signals) of the acceleration detectors D1 to Dn input by the input processing device 11a in the storage device 11c at a predetermined cycle, and the stored detection signals have a predetermined number (for example,
Every 1024 pieces), all the detection signals are output to the love check device 12.

Further, the arithmetic processing device 11b forms information for displaying and storing the rubbing occurrence information output from the love check device 12 and outputs the information to the output processing device 11d.

The output processing device 11d forms recording information to be recorded and output to the printing device 13, display information to be displayed on the CRT display device 14, and alarm information to be output to the annunciator 15, based on the display storage information added by the arithmetic processing device 11b. , Outputs the information to the corresponding device.

In the love check device 12, the data registration unit 12a
Accelerometers D1 to Dn output from computer 11 1024
The data for each piece is stored. The power spectrum density calculation unit 12b, which is a characteristic calculation means, calculates the power spectrum density based on 1024 pieces of data for each of the acceleration detectors D1 to Dn.

Here, the detection signals of the acceleration detectors D1 to Dn are discrete values sampled in a predetermined cycle, and can be represented by the autocorrelation function φ (τ) as shown in the following equation (I).

And the power spectral density of each detected signal
PSD (f) can be calculated by the following equation (II).

_{PSD (f) = 4 0 ∫} ∞ (τ) cos (2πfτ) dτ ···
(II) The power spectrum density calculation unit 12b calculates this equation (II) using the 1024 detection signals obtained for each of the acceleration detectors D1 to Dn, and calculates the acceleration detector D1.
For ~ Dn, the power spectral density in the frequency band of 1 to 5 KHz is calculated. The calculation result is output to the comparison unit 12c that is the comparison means.

The reference power spectral density registration unit 12d, which is a rubbing characteristic storage means, stores the reference power spectral density obtained when rubbing occurs in the turbine casing 10.

This reference power spectral density can be obtained in a state where rubbing is generated in a test device having the same configuration as the turbine casing 10.

That is, when the turbine casing 10 is not rubbed, the power spectrum density as shown in FIG. 2 is obtained, and when the turbine casing 10 is rubbed, as shown in FIG. It is possible to obtain a power spectral density having a peak in the frequency band of.

The pattern of the power spectral density changes depending on the location of the turbine casing 10 where rubbing occurs. Therefore, the rubbing generation position is changed by the above-described test apparatus, the reference power spectral density corresponding to each position is measured in advance, and stored in the reference power spectral density registration unit 12d.

The comparing unit 12c outputs the power spectral density pattern for each of the acceleration detectors D1 to Dn output from the power spectral density calculating unit 12b as a plurality of reference power spectral density patterns stored in the reference power spectral density registering unit 12d. Respectively (pattern matching). This comparison is performed as follows.

That is, for example, as shown in FIG. 4, the pattern of the power spectral density PSDd and the reference power spectral density
When the patterns of PSDr are obtained by curves Pd and Pr, respectively,
The area Q of the portion surrounded by the curves Pd and Pr for the frequency band 1 to 3 KHz is calculated based on the following equation (III).

Q = Σ (log (PSDd / PSDr)) ² (III) Then, it was obtained by comparing the power spectral density pattern of each acceleration detector D1 to Dn with a plurality of reference power spectral density patterns. The value of the area Q is used as a rubbing occurrence judging unit which is rubbing occurrence judging means.
Output to 12e.

The rubbing occurrence determination unit 12e checks whether or not the area Q input from the comparison unit 12c satisfies the condition shown in the following equation (IV), and when it satisfies, judges that rubbing has occurred.

| Q | ≦ ε (IV) Then, the rubbing occurrence determination unit 12e outputs the determination result to the arithmetic processing unit 11b of the electronic computer 11.

With the above configuration, when rubbing is detected, the steam that is being supplied to the turbine is temporarily stopped to make it less susceptible to external noise.

In that state, the turbine rotates at a low rotation speed, and the vibration generated in the turbine casing 10 due to the rotation is detected by the acceleration detectors D1 to Dn, and the detection signal is converted into a digital signal by the input processing device 11a. The data is sampled by the arithmetic processing unit 11b at a predetermined cycle and stored in the storage unit 11c in time series.

The arithmetic processing unit 11b, every time 1024 pieces of data are stored for each acceleration detector D1 to Dn in the storage device 11c,
All of them are transferred to the data registration unit 12a.

Thereby, the power spectrum density calculation unit 12b, for each acceleration detector D1 ~ Dn, calculates the power spectrum density of the frequency band of 1 ~ 5KHz using 1024 data, the calculation result to the comparison unit 12c. Output.

The comparing unit 12c compares the plurality of reference power spectral density patterns registered in the reference power spectral density registering unit 12d with the power spectral density patterns of the respective acceleration detectors D1 to Dn input from the power spectral density calculating unit 12b. The rubbing occurrence determination unit 12
Output to e.

The rubbing occurrence determination unit 12e determines rubbing occurrence based on the comparison result of the comparison unit 12e. Then, the combination of the power spectral density pattern determined to generate rubbing at that time and the reference power spectral density pattern is output to the arithmetic processing unit 11b.

Thereby, the arithmetic processing unit 11b represents the names of the acceleration detectors D1 to Dn corresponding to the power spectral density pattern determined to generate rubbing, and the power spectral density pattern and the reference power spectral density pattern. The graph, etc. is displayed and output by the printing device 13 and the CRT display device 14, and the annunciator
15 alarm output.

In this way, the occurrence of rubbing is determined based on the pattern of the power spectral density, so that the occurrence of rubbing can be reliably detected.

Also, since the information representing the power spectral density pattern that caused the occurrence detection and the reference power spectral density pattern that was the target at that time is displayed,
The operator can predict the rubbing occurrence position with a relatively high probability. In addition, the prediction of the occurrence position can be performed based on the identification information of the acceleration detectors D1 to Dn that caused the occurrence detection.

By the way, in the above-described embodiment, when the rubbing check is performed, the steam being supplied to the turbine is stopped, but when the calculation result of the power spectral density is not affected by noise due to the inflow of steam, for example, If the acceleration detector does not output a signal due to the noise, it is not necessary to stop the supply of steam.

Further, in the above-described embodiment, the love check device is configured separately from the electronic computer, but the function of the love check device may be incorporated in the electronic computer.

In the above-described embodiment, the rubbing occurrence is determined by using the power spectrum density pattern at the time of rubbing as the reference pattern, but the rubbing occurs by using the power spectrum density pattern in the state where no rubbing occurs as the reference pattern. It is also possible to detect that the rubbing is not performed and determine that rubbing has occurred in other cases.

[Effects of the Invention] As described above, according to the present invention, the characteristic of vibration occurring in the turbine casing is calculated, the calculated result is compared with the characteristic of vibration when rubbing occurs, and based on the comparison result. Since the rubbing occurrence is determined by the rubbing, the rubbing occurrence can be reliably detected even if a sound source in the frequency band of the rubbing sound exists near the turbine casing, and the rubbing can be reliably detected.

[Brief description of drawings]

FIG. 1 is a block diagram showing a love check device according to an embodiment of the present invention, FIG. 2 is a graph diagram illustrating a power spectrum density pattern obtained in a state where rubbing does not occur, and FIG. FIG. 4 is a graph showing a power spectrum density pattern obtained in the generated state, FIG. 4 is a graph for explaining the operation of the comparison unit, and FIG. 5 is a block diagram showing an example of a conventional device. 11 ... Electronic computer, 11a ... Input processing device, 11b ... Arithmetic processing device, 11c ... Storage device, 12 ... Love check device, 12a ... Data registration unit, 12b ... Power spectrum density calculation unit, 12c …… Comparison unit, 12d …… Reference power spectral density registration unit, 12e …… Rubbing occurrence determination unit, D1 to Dn…
… Accelerometer.

Claims (1)

[Claims] 1. A vibration detecting means for detecting a vibration occurring in a turbine casing, and a characteristic calculating means for calculating a characteristic of the vibration occurring in the turbine casing based on the detected vibration of the vibration detecting means. This rubbing characteristic storage means stores in advance the characteristics of vibrations that occur in the turbine casing when rubbing occurs, and comparison means that compares the calculation result of the characteristic calculation means with the characteristics stored in the rubbing characteristic storage means. A rubbing occurrence determination means for detecting that rubbing has occurred in the turbine casing based on a comparison result of the means.