RU2582906C1 - System for monitoring torsional vibrations of rotating shaft line of turbine unit - Google Patents

Abstract

FIELD: metrology.

SUBSTANCE: invention relates to metrology, particularly to means of measurement of torsion oscillations of shaft lines. System for monitoring of torsional vibrations comprises measuring information elements in form of teeth arranged on shaft of toothed disc, keyphasor information element, arranged in form of additional disk with single tooth or with single recess, fixed proximity sensors, as well as hardware-software unit. Device contains second keyphasor, wherein information elements and two sensors are installed at ends of two keyphasors shaft train, and location of measurement plane on it is determined by calculation of maximum sensitivity of given point of shaft line to harmonic effect of alternating torques. At that, transducers are arranged outside of shaft by two in every measurement plane at angle of 180 degrees relative to each other.

EFFECT: technical result is high accuracy of diagnostics.

1 cl, 2 dwg

Description

Area of use

The invention relates to measuring equipment for diagnosing the technical condition of machines with rotating elements and can be used, in particular, to determine the characteristics of torsional vibrations of shaft lines of power turbines, feed pumps and other similar equipment of thermal power plants (TPPs). Knowledge of the characteristics of torsional vibrations, as well as the parameter of the static twist of the shaft line for certain characteristics of the operation of the equipment, allows to identify various defects of machines and evaluate the conditions unfavorable for their operation.

State of the art

Known adopted as the closest analogue to the patented invention, a system for monitoring the torsional vibrations of a rotating shaft of a turbine unit, containing information elements of angular displacements of the shaft line located in at least one measuring plane, made in the form of teeth mounted on the shaft of the transverse gear disk, an additional information element of the speed indicator, made in similar to the aforementioned disk with a single tooth or with a single cavity, fixed changes individual sensors installed on the outside of the shaft, two in each measuring plane at an angle of 180 degrees relative to each other, and a stationary sensor of the revolution indicator mounted in the plane of the location of the corresponding information element for generating electrical pulse signals in the contactless interaction of these sensors with the specified information elements, and hardware-software unit connected to the indicated sensors for converting and mathematical processing received from sensors in deformations of (RU 2523044, G01H 11/06, 2014 [1]).

The disadvantages of the system [1] include the lack of the ability to determine the static twist of the shaft line, requiring data on its value along its entire length. In addition, in [1] the locations of the informational and measuring elements location planes on the shaft line were not specified, which can lead to a significant decrease in the accuracy of measurement results due to the small value of the information signal if these places are unsuccessful.

Disclosure of invention

The objective of the invention is to increase the representativeness with guaranteed accuracy of the monitoring results, and the technical results are the ability to control changes in the static twist of the shaft line and the ability to accurately specify locations along the length of the shaft of the measuring planes.

The solution of this problem by achieving the indicated technical results is ensured by the fact that the system of monitoring torsional vibrations of the rotating shaft of the turbine unit, containing at least one measuring plane information elements of the angular displacements of the shaft, made in the form of teeth mounted on the shaft of the transverse gear disk, an additional information element of the marker revolutions made in the form of a disk similar to the aforementioned with a single tooth or with a single a hollow, fixed measuring sensors installed outside the shaft, two in each measuring plane at an angle of 180 degrees relative to each other, and a fixed speed indicator sensor installed in the plane of the location of the corresponding information element for generating electrical impulse signals in the contactless interaction of these sensors with the specified information elements , as well as hardware and software unit for converting and mathematical processing connected to these sensors the information obtained from the sensors, according to the invention further comprises a second speed indicator with an information element and a sensor similar to the specified information element and a sensor of the first speed indicator, the information elements and sensors of the two indicated speed indicators are installed at the ends of the shaft shaft, and the location on the shaft shaft is at least one of the indicated measuring planes is determined on the basis of the greatest sensitivity of a given place of the shafting to the harmonic zdeystviyu variable torque, characterized by sensitivity coefficient value, which is calculated by the formula

δ _ij f = A _ij / M _j ,

Where

f is the frequency of harmonic torque; i is the number of cross sections for measuring torsional vibrations; j is the number of cross sections for the application of harmonic torque; K is the number of natural frequencies of torsional vibrations taken into account; δij is the coefficient of sensitivity of the shaft line in the i-th measuring plane to the influence of harmonic torque with a frequency f _k (k = 1, 2, ..., K) applied in the j-th section of the shaft line; A _ij is the amplitude of torsional vibrations of the shaft line in the i-th measuring plane calculated by one of the known methods from the action of harmonic torque with a frequency f _k applied in its j-th section; M _j - the amplitude of the harmonic torque applied in the j-th section of the shaft line.

The causal relationship between the distinguishing features of the invention and the specified technical result is as follows.

The static twist of the shaft line is an important diagnostic feature, the change of which over time, as a rule, is associated with the appearance of defects in the shaft line, such as breakage of the coupling bolts or disengagement of the coupling with the shaft. The introduction of a second revolution indicator with the installation of two indicated revolution indicators at the ends of the shaft line allows you to control the change in its static twist using two corresponding information elements.

The location on the shafting of measuring planes for monitoring the characteristics of torsional vibrations, as already noted, is very critical, since the change in the shape of the shafting along the length has inflection points, near which the vibration amplitudes cannot be measured at all or measured with low reliability. Determining the optimal location of the measuring plane on the shafting according to the above mathematical formula allows monitoring to obtain knowingly reliable and accurate information about the change in time of the characteristics of torsional vibrations of the shafting of a controlled turbine unit.

Brief Description of the Drawings

In FIG. 1 schematically shows a shaft assembly of a turbine unit with measuring elements mounted on it and with the monitoring system blocks according to the invention located outside it; in FIG. 2 - the same shaft line with a plot of the longitudinal distribution of the amplitude of torsional vibrations, illustrating the choice of the optimal location of the measuring planes on the shaft line.

Legend

APB - hardware-software unit;

ASUTP - automated process control system;

DD - an additional disk;

ZD - a gear disk;

IE - information element;

IP - measuring plane;

PC - workstation

TPP - thermal power plant.

Decoding of the numbering of drawings

1 - shaft shaft; 2 - IP; 3 - ZD; 4 - DD; 5 - APB; 6 - APCS; 7 - PC.

DETAILED DESCRIPTION OF THE INVENTION

The system for monitoring the torsional vibrations of a rotating shaft line 1 (Fig. 1, 2) of a turbine unit (not shown) according to the invention contains information elements (IE) located in the same measuring plane (IE) 2 of the angular displacements of the shaft shaft 1, made in the form of teeth mounted on the shaft of the transverse gear disk (ZD) 3, and additional IE of two revolution indicators, made in the form of additional disks (DD) 4.1, 4.2 located at the ends of the shaft line 1, similar to the mentioned ZD 3, but with a single tooth or single cavity (not shown).

Outside the shaft line 1 in IP 2 and in the planes of location DD 4.1, 4.2, stationary measuring sensors (not shown) are installed, which contactlessly senses the electrical impulses of the signals of the corresponding IEs. In this case, the sensors in IP 2 are installed at an angle of 180 degrees relative to each other. All these sensors are connected to the hardware-software unit (APB) 5 (Fig. 1) for converting and mathematical processing of information received from these sensors. APB 5 is connected by communication lines with the interacting ASUTL 6 TPP and the workstation (PC) 7 that monitors.

According to the invention, the determination of the optimal location on the shafting 1 IP 2 is determined by calculation, based on the greatest sensitivity of a given location of the shafting to the harmonic effect of variable torques. Graphically, the maximum value of the information signal associated with torsional vibrations should correspond to the maximum of the diagram of the distribution of the amplitude of these vibrations along the shafting (Fig. 2). As can be seen from FIG. 2, SP 2 with ZD 3 is set at the maximum region of the above diagram. For comparison, in the same FIG. Figure 2 shows the nearly unsuccessful location of IP 2.2 with ZD 3.2 in the region of the node of the torsional vibration diagram. This location of the IP seems quite real with an approximate choice of its place on the shaft without applying the present invention.

The determination of the indicated optimal location of IP 2 on the shaft 1 according to the invention is carried out by calculating the coefficient of sensitivity of the shaft shaft to the effects of harmonic vibrations associated with the location sought on the shaft. The calculation of the specified coefficient is made according to the formula

δ _ij f = A _ij / M _j ,

Where

f is the frequency of harmonic torque; i is the number of cross sections for measuring torsional vibrations; j is the number of cross sections for the application of harmonic torque; K is the number of natural frequencies of torsional vibrations taken into account; δ _ij is the coefficient of sensitivity of the shaft line in the i-th measuring plane to the influence of harmonic torque with a frequency f _k (k = 1, 2, ..., K) applied in the j-th section of the shaft line; A _ij is the amplitude of torsional vibrations of the shaft line in the i-th measuring plane calculated by one of the known methods from the action of harmonic torque with a frequency f _k applied in its j-th section; M _j - the amplitude of the harmonic torque applied in the j-th section of the shaft line.

System operation

The operation of the monitoring system according to the invention is as follows.

During operation of the turbine unit, starting from the moment of its commissioning as part of the TPP equipment, information signals from the proximity sensors of the measuring IE and IE of the speed indicators are supplied to the APB 5. To obtain information about the current operating parameters (temperature and steam pressure, electrical load, etc.), the АПБ 5 is additionally connected to the standard process control system 6 of the TPP. All information obtained is mathematically processed in a known manner, and the processing results are sent for analysis and archival storage on PC 7.

Claims (1)

A system for monitoring torsional vibrations of a rotating shaft assembly of a turbine unit, comprising information elements of angular displacements of the shaft assembly located in at least one measuring plane and made in the form of teeth of a transverse gear disk mounted on a shaft, an additional information element of a speed indicator made in the form of a similar disk with a single tooth or with a single cavity, fixed measuring sensors mounted outside the shaft, two in each measuring plane speed at an angle of 180 degrees relative to each other, and a stationary sensor of the revolution indicator mounted in the plane of the location of the corresponding information element for generating electrical pulse signals during the contactless interaction of these sensors with the specified information elements, as well as a hardware-software unit for converting and mathematical processing of information received from sensors, characterized in that it further comprises a second marker revolutions with an information element and a sensor similar to the indicated information element and the sensor of the first revolution indicator, and the information elements and sensors of the two indicated revolution indicators are installed at the ends of the shaft line, and the location on the shaft line of at least one of these measuring planes is determined based on the highest sensitivity of this the location of the shafting to the harmonic effect of variable torques, characterized by the value of the sensitivity coefficient and, which is calculated by the formula
δ _ij f = A _ij / M _j ,
Where
f is the frequency of harmonic torque; i is the number of cross sections for measuring torsional vibrations; j is the number of cross sections for the application of harmonic torque; K is the number of accounted for natural frequencies of torsional vibrations; δ _ij is the coefficient of sensitivity of the shaft line in the i-th measuring plane to the influence of harmonic torque with a frequency f _k (k = 1, 2, ..., K) applied in the j-th section of the shaft line; A _ij is the amplitude of torsional vibrations of the shaft line in the i-th measuring plane calculated by one of the known methods from the action of harmonic torque with a frequency f _k applied in its j-th section; M _j - the amplitude of the harmonic torque applied in the j-th section of the shaft line.

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