JPS5963526A - Diagnosing method of rotary machine - Google Patents

Abstract

PURPOSE:To judge abnormality from whether oscillation exceeds an experimentally and experientially found oscillation level by detecting acceleration and generating an acceleration spectrum, etc., within a specific frequency range in every necessary period by titled diagnosing method of a rotating machine in a large- scale plant such as an LNG plant. CONSTITUTION:Amplitude values mum corresponding to oscillation frequencies are found to obtain a distribution of an amplitude spectrum of the rotating machine. Constant oscillation levels D1 and D2 found by the past results, experiments, etc., are set and inputted as reference values to decide on a warning state when the value of the amplitude spectrum (x) is between D1 and D2 or an abnormal state when it exceeds D2. Intervals of diagnosis are determined and the amplitude spectrum (x) within the frequency range is generated at intervals of specific elapsed time and displayed on a display device simultaneously with lines indicating the oscillation levels D1 and D2. Thus, the oscillation states of the rotating machine at diagnostic points are judged immediately on the display.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for diagnosing rotating machines in dog-type plants such as runts.

The proportion of rotating machinery in dog-shaped plants and equipment such as LN (3 plants) is extremely high, and their role is also important.

When abnormalities or breakdowns occur in these rotating machines, not only will there be economic losses, but if the accidents escalate, it will develop into a major social problem. For example, LNG plants are used as a supply source for city gas, cold power generation, equipment, etc., and if a failure occurs in the LNG pump that pumps LNG from the tank, it will cause a large loss to the user side and also cause damage to general users. It turns out.

Mechanical diagnostic technology in Japan began in 1950, when the Shinkansen began operation and pollution and contamination issues began to be closely amplified.
Although serious efforts began in the 1960s, the criteria for making such decisions have not yet been standardized.

The present invention was made against this background, and aims to establish a failure prediction technology for rotating machinery in plants, etc., improve the reliability of runts, reduce maintenance costs, and homogenize maintenance techniques. This is the purpose.

The present invention will be described in detail below with reference to the drawings.

To carry out the machine diagnosis method of the present invention, an acceleration detector is installed at an appropriate position of a rotating machine, and based on the signal from the detector, a predetermined frequency range is detected at a certain point in time of the microco 7 pinny tan stem, etc. A vibration spectrum is created, and the spectrum is stored and displayed on a required display device such as a monitor television.

By adding the subscript Kn of the nth spectrum in a given frequency domain, the nth acceleration spectrum is α(,), the nth velocity spectrum is υ(n), the n4th amplitude spectrum is: t(n) The nth angular velocity is expressed as ω(n), the nth frequency is expressed as f(n), the spectrum width is △f, the sampling frequency is f8, the number of sampled data is expressed as N8, and the relationship between the above spectra is as follows. It will be as follows.

aJ(n)-2πf, (n>/(n)-n ・△f Below, the speed of the rotating machine is 60.00 Orpm = 5
A case will be described in which a vibration spectrum is used to perform fault diagnosis in a relatively low frequency range of about 00 rps.

Possible causes of failure that can be diagnosed in a relatively low frequency range include bent shafts, cracks in the pump impeller, and eccentricity of the rotating body.

In the frequency domain, only the fundamental wave component is analyzed, the number of sampling data is 1024 points, the total width of the spectrum is 500I]Z, and the sampling frequency is 1K.
If analyzed under l-IZ conditions, the total number of spectra is 512 (n-1 to 512), and in Figure 1, the horizontal axis is the frequency (maximum 5ooH, Z), the vertical axis is the amplitude value (μm), and 9 , which shows the distribution of the amplitude spectrum (,) of the rotating machine obtained under the above conditions.

The standard vibration levels D, D2, determined through past results, experiments, etc., are set and input into the microcomputer/stem. This vibration level D1゜I)2 is, for example, 1)1
-50μm, D2-75/1m, amplitude spectrum (
, ) is between Dl and D2, caution is required, and when it exceeds D2, it is determined to be abnormal.

Next, an interval for diagnosis is determined, and an amplitude spectrum (,) in the frequency range is created every predetermined period of time, and the vibration level D1. It is displayed on the display device at the same time as the line that displays D2.

This display allows the vibration state of the rotating machine at the time of diagnosis to be immediately determined.

However, if the amplitude spectrum at the time of a certain diagnosis exceeds the vibration level D2 and enters the abnormal region as shown in FIG. 1, it is determined that there is a failure or serious problem, and necessary maintenance is performed.

When diagnosing a failure by displaying such an amplitude spectrum, the frequency of the amplitude spectrum that falls into the abnormal region can be easily read, so the location of the failure can be easily determined.

When a defect occurs, it is thought that the defect will grow over time and lead to a failure, and if the vibration level exceeds D1 at a certain diagnosis point and enters the caution area, the diagnosis period can be shortened to ensure the timing of failure. to understand.

In the above embodiment, the amplitude spectrum (
, ) were selected, but it goes without saying that failure diagnosis can be performed using the same method even if the acceleration spectrum (α) and velocity spectrum (v) are selected.

2 is a block diagram of a preferred apparatus for carrying out the present invention, and the nuclear apparatus will be briefly described below.

In the figure, (1) is a sensor for detecting acceleration, (2) f
Analog signal (acceleration) from d sensor (1) is A/D
This is a low-pass filter for reducing area song errors when the converter (3) converts into a digital signal.
]) The signal digitized by the converter (3) is input to the master microcomputer/stem (4). A diagnostic condition setter (5) is connected to the master micro combinator/stem (4) to set and input the diagnosis interval and vibration level D, 1)2, as well as the arithmetic processor (6) and main memory (7). ), auxiliary memory (8), diagnostic display section (9), and alarm device (1o) are connected to the master microcomputer 7 stem (4).

Master microcomputer/stem (4) uA/D
After performing Aherley/ink calculation to extract the characteristics of the signal from the converter (3), digit number adjustment calculation to prevent underflow and over 7°, etc., the main memory (7), the calculation processor (6), Frequency analysis (
F P i') is performed to convert the signal on the time axis into an amplitude spectrum on the frequency axis.

Here, the arithmetic processor (6) performs Luhatafly calculations (multiplication, addition) and square root calculations for obtaining a spectrum in frequency analysis. The auxiliary memory (microprocessor and main memory (7), arithmetic processor (6))
It houses an operating system that assists the program, and also stores calculation results (amplitude spectra).

Master microcomputer/stem (4) Displays the calculation results in accordance with the diagnostic conditions manually entered by the diagnostic condition setter (5), and drives and displays the alarm device θ0) if necessary. , outputs a signal 0 for alarm and automatic stop/start of the stem.

The father, master microcomputan stem (4) is connected to the power source (c) via a semiconductor relay αυ, and is energized only at the required time (diagnosis time).

(13i-1 slave microcomputer/stem) and the master microcomputer stem (4
), and memory 04) and clock 00 are connected to slave microcomputer system 0 [phase], and slave microcomputer system 0 and clock 00 are connected to power supply (2). Nokuasop circuit a0 is connected.

The slave microcombutan stem α■ is always in operation with power outage protection provided by the vanoteribasokuanop circuit 0.fi)K, and based on the results of special training ono, the master microcombutan stem (4) is Depending on the diagnosis conditions, the semiconductor relay (11) is driven at an appropriate time to control the diagnosis interval, and the necessary take is memorized and stored in preparation for a power outage after the diagnosis is completed.
), the master microcomputer (4) is completely stopped after the diagnosis i*i is completed, and then activated 6 minutes before the next diagnosis.

As described above, the present invention establishes a failure diagnosis technique for rotating machines, and also makes it possible to reliably grasp the time of failure, thereby increasing the reliability of the plant and significantly reducing economic losses.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram of an amplitude spectrum, which is an indicator of failure diagnosis according to the present invention, and FIG. 2 is a block diagram of a preferred apparatus for carrying out the present invention. (]) H sensor (4) indicates the master microcomputer/stem, (9) indicates the diagnostic display section, and 03 indicates the slave microcomputer stem. × (1) Continued from page 1 (12 + Inventor: Takagi Yo, No. 3-2-16 Toyosu, Koto-ku, Tokyo, Ishikawajima-Harima Heavy Industries Co., Ltd., Toyosu General Office (?2) Inventor: Kenji Sugishita, Toyosu, Koto-ku, Tokyo 3-2-16 Ishikawajima Harima Heavy Industries Co., Ltd. Toyosu General Office

Claims (1)

[Claims] 1) Detect the acceleration of the rotating machine, create at least an acceleration spectrum, a speed range, and a stationary width range in a predetermined frequency range for each required period based on the detection results, and experimentally A method for diagnosing a rotating machine in which an abnormality in the rotating machine is determined based on whether the spectrum exceeds a vibration level determined empirically.