DD261208B5 - Method for detecting sudden imbalance changes on the rotating machinery - Google Patents

Abstract

Method for detecting sudden imbalance changes on the rotating machinery, in particular large turbomachinery. In order to determine slight sudden imbalance changes, the changes in the rotational frequency component for the vibration velocity or the vibration path of adjacent bearing or threshold vibration measurement planes are measured as system-equivalent imbalance changes compared to a reference value according to the relations DV1NA1K 2K (DV1NhDV1Nv) iDS1NA1K 2K (DS1NhDS1Nv) ibzw. when determining transients according to the relationships TV1NA1K 2K (TV1NhTV1Nv) iTS1NA1K 2K (TS1NhTS1Nv) and summed up as diagnostic parameters for the sudden imbalance change and evaluated, z. B. displayed and / or monitored. figure

Description

! Σ (AV1N _h

1N _S

2 K.

1 N _s = -Vz (AS 1 N _h + AS 1 NJ i 2 K

and / or with continuous measurement of the rotational-frequency components and determination of transients of the changes in the position of these rotational-frequency signal components, formed as a pointer difference between the current value and the constantly variable reference value corresponding to the value of the characteristic of the preceding measurement cycle, the system-equivalent transient imbalance change according to the relationships

TV1N _S = -JZ (TVI N _h + TV1 N _v) i 2 K.

TS1 N _s = -JJ ^ I (TS1 TS1 N _h + i NJ

be formed and evaluated as a diagnostic characteristic for sudden imbalance changes, z. B. displayed and / or monitored, wherein in the relationships

V1 N- rotational frequency of vibration velocity

SIN- Rotational frequency component of the vibration path

h - horizontal

ν - vertical

i - adjacent bearings or wave vibration measurement planes K - number of measurement planes

A - Sum value

mean.

2. The method according to claim 1, characterized in that the selection of the changes to be summed the rotational frequency components is made in response to the influence vectors acting for the respective rotor / bearing system of the rotating machine influence for imbalance changes of the respective rotor area.

For this 1 page drawing

Field of application of the invention

The present invention relates to a method for selective vibration monitoring for the diagnosis of small, sudden imbalance changes of the rotating machinery, in particular large thermal turbomachinery, with the aim of damage detection and prevention of consequential damage.

Characteristic of the known state of the art

To determine the size of the existing imbalance of Lauferstrangen rotating machinery and for monitoring and signaling suddenly occurring imbalance changes methods have been developed which specify the rotational frequency components of a broadband frequency spectrum of vibration signals selectively and then by comparison with the measured value before the occurred Unwuchtanderung the proof of Admit admission (DD 158581) The monitoring is done emkanalig means Meßstellenumschalter or multi-channel in Quasr real-time, as implemented in modern vibration monitoring systems (eg DE 3017327, 3112188), wherein in addition to the actual value of the rotational frequency vibration component, the change from a reference value determined from previous measurements as well as the transient of the temporal change between two consecutive measurements and the magnitude of the changes compared with prescribed limits and threshold exceedances sig be nalized Problems are doing next to errors in the Aufnehmermeßkette and defective sensors, which are compensated devices technically monitoring and Fehlalarmunterdruckungsschaltung, recognizing less sudden imbalance changes, since it does not specified signaling limits that require the sake of avoiding faulty Signage certain minimum values, nor set alarm limits In addition, especially in large thermal turbomachinery operating, sometimes quite rapidly acting changes in the vibration level at individual storage areas, which are to be distinguished from mass imbalances

Object of the invention

The aim of the invention is a more meaningful assessment of the mechanical state of rotating machinery, in particular of large thermal turbomachinery, as it is possible with previous methods and devices for continuous vibration monitoring and diagnosis

The operator should be given information about small, sudden imbalance and further resulting from it disturbances to prevent consequential damage as much as possible

Explanation of the essence of the invention

The invention has for its object to develop a method that provides a suitable for the detection of small, sudden Unwuchtanderungen characteristic with little additional equipment and circuit complexity by combining determined from the broadband oscillation signal spectrum changes in the rotational frequency components for the vibration path and the vibration velocity

In accordance with the invention, summation of the respective values of the horizontal and vertical directions of oscillation of adjacent measurement levels is carried out with the rotational frequency components of the vibration signals determined by known vibration monitoring methods and the changes therewith relative to a reference state or the transient changes and summation values ΔV 1 N _A and AS 1 N _A for the vibration velocity and the vibration path according to the relationships

ДѴ1 N _A = - ^ - Σ (ДѴ1 N _h + ДѴ1 N _v ) i 2 K

AS 1 Na = - ^] - Σ (AS 1 N _h + AS 1 NJ 2 K

or with continuous measurement of the rotational-frequency components and determination of transients T of the pointer changes of these rotational-frequency sigma lantei Ie-formed a Is pointer difference between the current value and that of the previous measurement cycle - according to the relationships

TV1N _A = -V Σ (TV 1N _h + TVIN ₇ )!

2 IN

TS1 N _A = - ^] - Σ (TS 1 N _h + TS1 NJ 2 K

formed and evaluated as a diagnostic parameter for the sudden imbalance, ζ B displayed and / or monitored

In relationships mean

V1 N Rotational frequency of the swinging speed

S1 N Rotational frequency component of the vibration path

A total value

h horizontal

vertical

ι adjacent bearing or Wellenschwingungsmeßebenen

K number of measurement levels

It takes into account the physical context that an imbalance change on the rotor according to the present influence vectors in both horizontal and vertical vibration direction at both bearing and Wellenschwingungsmeßebenen and beyond the coupled shaft train at other adjacent vibration levels (depending on the dynamic properties of the Laufer-ZLagerVFundamentsystems of the type of the rotating machine, and at the same time makes apparent from the position of the plane of the initial unbalance and Unwuchtanderung) by different changes to the unbalanced pointers by summing these Unwuchtanderung, where all values are positive amount,

(Amount of pointer changes

AVIN = ѴТЙ - vTft _s " _ug ,

AS 1 N = sTW - STf ^ ug or TV1 N = TVuT (t) - TVTW (t - At), TS1 N = TSTW (t) - TSTW (t - At))

to the Diagnosekenngroßen the new diagnostic parameters in terms of amount as a sum of significantly larger and allow to detect small, sudden imbalance changes and to distinguish them from operational, especially large thermal turbomachinery, typical and sometimes relatively fast-acting changes in vibration levels at individual storage areas

The selection of the measurement levels to be linked can be made by computations of the forced vibrations of the dynamic model of the rotating machines, by model tests or by statistical evaluation of existing operating and test measurements on the machines in question

exemplary

The accompanying drawings show a possible embodiment for implementing the method according to the invention in a block diagram. The oscillations of a rotating machine to be monitored and diagnosed are detected by a plurality of bearing and / or shaft vibration sensors 1a In the drawing is shown for simplicity only a measuring channel for a Lagerschwingungsmeßstelle The monitoring device realized in analogue Meßwertverarbeitung the state of the art corresponding broadband and selective real-time monitoring of the vibration sum level, the rotational and double-rotational frequency signal component and de Differences to limit value overrun The monitoring devices have an almost independent of the transducer type fundamental structure differences are given by possible electrical signal integration in bearing vibration transducers by the frequency range in the bandpass filtering of the measuring signal and the type of filtering method for obtaining the selective signal components Specifically, for a monitor except the vibration sensor 1 a following functional elements typical

- Amplifier 2

- Integrator 3, if necessary, to convert the measured signal into the monitored

- Bandpass filter 4, to suppress unimportant parts of the spectrum

- Narrow band filter 5 with controllable center frequency for filtering the rotational and double-rotational frequency signal components

- Synchronizing and control device 6 for the exact setting of the center frequencies of the narrow band filter devices 5 on the engine rotational frequency and the double engine rotational frequency by means of a, derived from the machine shaft with the pickup 7 per rotor rotation pulse

Rectifier 8 for quantizing the filtered-out signal components (a DC signal proportional to the peak-to-peak, peak-to-peak or rms value is formed)

- Signal evaluation module 9 (threshold value switch) for the classification of the signal components as well as their changes and for the derivation of control and warning signals

- Building blocks 10 for the realization of warning signals and protective measures

- Pointer instruments or numeric displays 11 for displaying the parameters to be monitored

- Test oscillator 12 for checking the entire measuring device

According to the invention extended utilization of the information content of the vibration signals, the signal levels are fed to the rectifiers 8 of an analog or digital arithmetic circuit 13, with the help of the system equivalent imbalance or the system equivalent transient imbalance changes are determined as characteristic diagnosis parameters for the detection of minor imbalance changes according to the above-mentioned relationships Summation values AV1 N _A , AS1 N _A or TV1 N _A , TS1 N _A are additionally fed to the signal evaluation module 9, which is followed by a display unit 11 and a signaling unit 10. This results in monitoring of the levels and signaling in the event of limit value overruns

Claims (1)

1. A method for detecting sudden, small imbalance changes on the rotating machinery, in particular large turbomachinery, using the metrologically determined changes in the rotational frequency component for the vibration velocity or the vibration path from the vibration signal spectrum of a broadband frequency range, characterized in that the changes determined by measurement adjacent Lagerbzw. Wave vibration levels as system equivalent imbalance changes versus a reference value corresponding to the relationships