JPH01199127A - Method for diagnosing facility - Google Patents

Abstract

PURPOSE:To accurately diagnose periods of regular inspection of a facility and improve its reliability by a method wherein a diagnostic index is obtained by a specific calculation based on a spectrum pattern on basic revolutions which are set from an oscillation spectrum of a rotator. CONSTITUTION:During operation of an LNG pump 1, acceleration or displacement is detected by an acceleration detector or a displacement detector, and frequency analysis of this data is carried out to calculate an oscillation spectrum such as acceleration or amplitude. On the basis of this spectrum, a spectrum pattern on basic revolutions of the pump 1 is set. Then by integrating a specific range of gauss distribution, which has been specified according to an integral multiple component of the spectrum pattern, multiplied by the oscillation spectrum at the frequency according to the integral multiple component over a predefined range and by averaging it; at the same time, the diagnostic index is calculated to forecast periods of regular inspection.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is applicable to highly public LNG plants, thermal power plants,
The present invention relates to an equipment diagnosis method applied to rotating machines such as pumps and blowers installed in other equipment. [Prior Art] The proportion of rotating machines in large plants or equipment such as LNG plants is very high, and their role is also important. When abnormalities or breakdowns occur in these rotating machines, it goes without saying that economic losses will occur, but if the accident spreads, it will develop into a major social problem. For example, LNG plants are used as a supply source for city gas, power generation equipment, etc., so if the LNG pump that pumps LNG from the tank breaks down, it will cause a large loss to the user and also cause damage to general users. Become. Therefore, in order to solve this problem, we installed vibration sensors on representative parts of the pump casing and measured vibrations at regular time intervals, performed Fourier analysis on the measured vibration data, and transferred it to data on the frequency axis. , is processed to obtain a diagnostic index, and from the diagnostic index, pump abnormality diagnosis and deterioration prediction are performed. Figures 4 to 6 0) (b) Q When applying the conventional equipment diagnosis method applied to rotating machinery to LNG pumps
In Fig. 4, 1 is an LNG pump, 2 is a casing, 3 is a vertical shaft rotatably supported in the casing 2 via upper and lower bearings 4.4'', and 5 is a plurality of vertical shafts 3. The impeller is fixed in stages, 6 is a drive device that drives the vertical shaft 3 and the impeller 5, 7 is an acceleration detector or displacement detector disposed at a position close to 4° of the lower bearing on the outer periphery of the casing 2, and 8 is an LNG be. During operation of the LNG pump 1, acceleration or displacement is detected by an acceleration detector or displacement detector 7, frequency analysis of this data is performed, and vibration spectrum distribution such as acceleration or amplitude is determined as shown in FIG. In general, vibrations in rotating machines such as pumps are caused by shaft system (vertical shaft 3
The vibration frequencies generated by the shaft system, bearing system, and internal fluid system are mainly θ~500Hz. 500Hz -10KHz, 10KHz ~20K
Distributed in the Hz frequency band. Therefore, the vibration spectrum distribution shown in Fig. 5 is
-10KHz 5 IOKHz - 20KHz divided into frequency band A1 due to shaft system, frequency band B1 frequency band due to bearing system, frequency band C due to internal fluid system, average value of vibration level in each frequency band A, B, C at the time of measurement. s
,b. C is determined and the vibration levels are displayed in chronological order as shown in Figure 6 (IXO) &\). Figure 6 (A) shows the shaft system, Figure 6 (0) shows the bearing system, and Figure 6 (10) shows the diagnostic indicators for the internal fluid system. >The diagnostic index indicates the state of deterioration of the shaft system, bearing system, and internal fluid system over time, so L
Based on data measured during normal operation of the NG pump,
Caution: Define abnormality diagnostic level L C + LD, and set L
During the actual operation of the NG pump, it is determined whether or not an abnormality has occurred in the LNG pump by comparing the diagnostic index, precautions, and abnormality diagnostic levels LC and LD determined by the above-described procedure. [Problems to be Solved by the Invention] However, since the above-mentioned conventional means uses the total average of acceleration or amplitude in a predetermined frequency band when determining a diagnostic index, it may be partially affected by disturbances etc. When a portion with a high average value diagnostic result occurs, there is a problem in that the error in the diagnostic index becomes large, and there is a possibility that accurate and accurate diagnosis cannot be performed. The present invention has been made in view of the above-mentioned circumstances, and is intended to enable accurate equipment diagnosis. [Means for Solving the Problems] The present invention obtains a vibration spectrum based on the acceleration or displacement generated by the rotation of a rotating body, sets a spectrum pattern based on the basic rotational speed of the rotating body, and calculates an integer of the spectrum pattern. The vibration spectrum at the frequency for the integer multiple component is multiplied by a Gaussian distribution in a predetermined range corresponding to the multiple component, and the product is integrated over the predetermined range and averaged to obtain a diagnostic index. , the diagnostic index is obtained in chronological order to predict the periodic inspection time. [Action] A spectral pattern based on the basic rotational speed of the rotating body is set from the vibration spectrum obtained from the acceleration or displacement generated by the rotation of the rotating body, and a predetermined predetermined pattern corresponding to the integral multiple component of the spectral pattern is set. The Gaussian distribution of the range multiplied by the vibration spectrum at the frequency for the integer multiple components is integrated over a predetermined range and averaged to obtain a diagnostic index, and the diagnostic index is determined in a time series. Since the period of periodic inspection can be predicted from the diagnostic index determined by the system, it is possible to accurately judge the period of periodic inspection, improving the reliability of the equipment. [Example] Hereinafter, an example of the present invention will be described with reference to the accompanying drawings. 1 to 3 show an embodiment of the present invention. Similar to the conventional case, acceleration or displacement is detected during operation of a rotating body such as an LNG pump using the acceleration detector or displacement detector 7 shown in FIG. 4, and frequency analysis is performed to detect the Then, find the vibration spectrum distribution such as acceleration or amplitude. The vibrations generated by a rotating body have the largest component due to the basic rotational speed, and often contain information about abnormalities in the shaft system and bearing system (particularly bush bearings). Also, information regarding abnormalities is
Derived components also occur at integral multiples or fractions of the basic rotational speed, and these derived components often become "fluctuations" in the rotational speed due to load fluctuations. However, by setting a spectral pattern based on the basic rotational speed and applying a Gaussian distribution filter to the integer multiple component in the range nf0±Af, the spectral "
"Fluctuation" is prevented. Each component is nfo=! : The average value within Af is evaluated as a diagnostic index Zn. Here, Sp (f); vibration spectrum fo - fundamental frequency Af, width f for finding a spectrum pattern centered around the fundamental frequency or an integral multiple of the frequency; frequency W; coefficient; constant e; natural logarithm ( +) Diagnostic index Z calculated using the formula. (n-1, 2, 3°...
) is displayed in chronological order as shown in Figure 3, and the period To for regular inspections can be predicted from this graph. Therefore, since the error in the diagnostic index is reduced, it becomes possible to accurately diagnose the period of regular inspection, and the stability of the equipment after the regular inspection can be known. It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention. [Effects of the Invention] According to the equipment diagnosis method of the present invention, it is possible to accurately diagnose the periodic inspection period of the equipment, and therefore, the excellent effect of improving the reliability of the equipment can be achieved.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the frequency and vibration spectrum obtained when performing the method of the present invention, Figure 2 is a graph showing the relationship between the same frequency and Gaussian distribution, and Figure 3 is a graph showing the same diagnostic index in time series. Graph, Figure 4 is a general explanatory diagram of an LNG pump, Figure 5 is a graph showing the relationship between the frequency and vibration spectrum obtained when performing the conventional method, and Figure 6 (A) (
B) <A> is a graph showing diagnostic indicators in a conventional method in chronological order. In the figure, 1 is an LNG pump, and 7 is an acceleration detector or a displacement detector. Figure 6 (a) Time (b) (c) Moema RJ77A”

Claims (1)

[Claims] 1) Obtain a vibration spectrum based on the acceleration or displacement generated by the rotation of the rotating body, set a spectrum pattern based on the basic rotational speed of the rotating body, and set a predetermined predetermined value corresponding to the integral multiple component of the spectrum pattern. Multiplying the vibration spectrum at the frequency for the integer multiple component by a Gaussian distribution in the range is integrated and averaged over the predetermined range to obtain a diagnostic index, and the diagnostic index is determined in time series. An equipment diagnosis method characterized by predicting periodic inspection timing.