JP2005113805A - Apparatus for preventing unstable oscillation of shafting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for preventing unstable oscillation of bearings with consideration given to bearing characteristics. <P>SOLUTION: The apparatus 10 preventing unstable oscillation is for preventing unstable oscillation from generating in the shafting resulting from load change in a rotary body supported by bearings. The apparatus 10 comprises a computing unit 12 and a control unit 13. In the computing unit 12, a stability margin for shaft oscillation is computed from bearing characteristics based on change in the load, and the stability margin is compared with a specified reference value. In the control unit 13, bearing temperature is controlled on the basis of a result of the comparison between a computed stability margin and the specified reference value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a device for preventing unstable vibration of a shaft system when a bearing load changes due to an influence of an operating condition such as a load in a high-pressure steam turbine or a rotary machine driven by a gear.

  A bearing is used as an element for supporting a shaft of a rotating machine, and a sliding bearing using oil or the like as a lubricating fluid is used in a large rotating machine. The dynamic characteristics (elastic coefficient, damping coefficient) of a sliding bearing depend on the size of each part of the bearing, the bearing load, and the lubricating oil temperature. In high-pressure steam turbines and rotating machines driven by gears, the bearing load changes due to the influence of operating conditions such as the load. Accordingly, the bearing dynamic characteristics also change and affect the shaft vibration. In the worst case, the shaft vibration is stable in a certain operation state, but becomes unstable due to a change in the operation state due to a change in the load, and the operation may not be continued.

In Patent Document 1, as an apparatus for realizing an appropriate bearing oil supply temperature corresponding to the turbine speed, an oil cooler that cools bearing oil supplied to the turbine bearing and a cooling medium line of the oil cooler are inserted. A control valve, a temperature detector that detects the temperature of the bearing oil, a function generator that outputs an oil temperature set value according to the turbine speed, and a deviation calculator that calculates the deviation between the oil temperature set value and the actual oil temperature And a turbine bearing oil supply temperature control device that includes a flow rate controller that performs PID calculation on the deviation to control the opening degree of the control valve.
Further, Patent Document 2 can flexibly cover a low range from a low speed range, a low load range to a high speed range, and a high load range from a low range to a high range. As well as controlling the vibration and temperature around the rotating shaft and bearings, as well as preloading the bearings, which can perform high-precision and high-efficiency machining in all machining conditions with a single machine, reducing equipment costs and machining costs. A cooling control device is disclosed.

JP-A-8-121113 Japanese Patent Laid-Open No. 11-315829 The Japan Opportunity Society, “Statistical and dynamic characteristics of slide bearings”, pages 294-296

  However, Patent Document 1 and Patent Document 2 lack control from the viewpoint of bearing characteristics. Accordingly, an object of the present invention is to provide an apparatus for preventing unstable vibration of a bearing in consideration of bearing characteristics.

Since the elastic modulus and damping coefficient of a bearing are given as a function of the viscosity of the lubricating oil and the bearing load, if the bearing load (surface pressure) changes with the load change of the device in which the bearing is used, the elastic modulus and damping coefficient Will also change and affect the stability of the shaft system supported by the bearing. When the attenuation decreases, the stability margin decreases and the vibration increases.
Here, since the viscosity of the lubricating oil is a function of the temperature of the lubricating oil, the stability of the shaft system can be maintained by changing the elastic coefficient and the damping coefficient of the bearing by adjusting the lubricating oil temperature.
Accordingly, the present invention is an apparatus for preventing unstable shaft system vibration caused by a load change of a rotating body supported by a bearing, and calculates a stability margin of shaft vibration from a bearing characteristic based on the load change, and this stability margin. A shaft system unstable vibration preventing apparatus comprising: an arithmetic processing unit that compares the calculated stability margin with a predetermined reference value; and a control unit that controls a bearing temperature based on a comparison result between the calculated stability margin and the predetermined reference value. The problem is solved.

In the shaft system unstable vibration preventing device of the present invention, the bearing characteristics based on the load change can be obtained based on the prediction of the bearing load after the load change and / or the lubricating oil temperature of the bearing.
In the shaft system unstable vibration preventing device of the present invention, the bearing characteristics based on the load change can be obtained based on the measured value of the temperature of the lubricating oil of the bearing.
In the shaft system unstable vibration preventing device of the present invention, the bearing characteristics based on the load change can be obtained based on the measured value of the temperature of the member constituting the bearing.
In the shaft system unstable vibration preventing device of the present invention, the rotating body may be driven via a gear.
Furthermore, the temperature of the bearing can be controlled by controlling the temperature of the lubricating oil supplied to the bearing, or by supplying a cooling medium other than the lubricating oil to the bearing.

  ADVANTAGE OF THE INVENTION According to this invention, the unstable vibration prevention apparatus of the bearing which considered the bearing characteristic is provided.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
<First Embodiment>
FIG. 1 is a block diagram showing a configuration of an unstable vibration preventing apparatus 10 according to the first embodiment, and FIG. 2 is a flowchart showing a vibration control procedure by the unstable vibration preventing apparatus 10.
The unstable vibration preventing device 10 is disposed in a lubricating oil supply system L of bearings 3, 4, 5 and 6 in a power generation facility including a steam turbine 1 and a generator 2. The lubricating oil supply system L is provided with a cooler 7, and cooling water is circulated through the cooler 7 through a cooling water supply path 9. A flow rate control valve 8 is disposed in the cooling water supply path 9, and the temperature of the lubricating oil flowing through the lubricating oil supply system L is adjusted by adjusting the opening degree of the flow rate control valve 8.

The unstable vibration preventing apparatus 10 includes a load change receiving unit 11, a calculation unit 12, and a control unit 13. In the following, the processing procedure by the unstable vibration preventing apparatus 10 will be described with reference to FIG.
The load change receiving unit 11 receives a change in the operating state of the steam turbine 1, that is, a load change command, and outputs a load change command to the calculation unit 12 (S101 in FIG. 2). The load change command is transmitted from an operation control device of the steam turbine 1 (not shown).

When receiving the load change command, the calculation unit 12 performs the following processing. First, the bearing load and the bearing oil (lubricating oil) temperature after the load change are predicted (S103 in FIG. 2). The bearing load and the bearing oil temperature corresponding to the load may be obtained in advance, and the load, the bearing load, and the bearing oil temperature may be stored in the storage unit (not shown) of the calculation unit 12 in association with each other. When receiving the change command from the load change receiving unit 11, the calculation unit 12 acquires the bearing load and the bearing oil temperature corresponding to the load from the storage unit. In this embodiment, this is referred to as prediction of bearing load and bearing oil (lubricating oil) temperature.

Next, the computing unit 12 calculates the bearing characteristics after the load changes based on the bearing load and the bearing oil temperature corresponding to the load (S105 in FIG. 2). The bearing characteristics are an elastic coefficient and a damping coefficient of lubricating oil supplied to the bearing. The bearing characteristics can be calculated based on, for example, a thermohydrodynamic lubrication theory (THL theory). The calculation of the bearing characteristics based on the THL theory can be performed based on the description in Non-Patent Document 1.

Non-Patent Document 1, page 295, Fig. 4, 7 and 3 show examples of calculation of bearing characteristics based on THL theory (relationship between Sommerfeld number S and dimensionless oil film elastic modulus). Examples of bearing characteristics calculated by THL theory (relationship between Sommerfeld number S and dimensionless oil film damping coefficient) are disclosed in 4, 7, 4 and these figures are used to calculate the elastic coefficient and damping coefficient of lubricating oil. Can be sought. The Sommerfeld number S is proportional to the viscosity coefficient of the lubricating oil as represented by the following formula (1). Accordingly, when the temperature of the lubricating oil increases, the Sommerfeld number S increases. Conversely, conceptually speaking, when the temperature of the lubricating oil decreases, the Sommerfeld number S decreases.
S = μNLD (R / Cp) ² / W (1)
μ: viscosity coefficient of lubricating oil, N: shaft rotation speed (rps), L: bearing width, D: bearing diameter R: bearing radius, Cp: machining radius clearance, W: bearing load

When the bearing characteristics are calculated, the calculation unit 12 predicts the shaft vibration stability margin after the load change based on the calculation result (S107 in FIG. 2). The stability margin of shaft vibration can be obtained based on the previously obtained elastic coefficient and damping coefficient. Specifically, the elastic coefficient and the damping coefficient obtained by the prediction are input to the bearing portion of the vibration analysis model of the rotating machine shaft prepared in advance, and the complex eigenvalue analysis is performed to directly obtain the damping coefficient.
FIG. 11 is a graph showing the relationship between the bearing load and the damping ratio. It is a requirement for the vibration not to be generated that the load is in a stable region in relation to the damping ratio.

  The stability margin obtained by the calculation unit 12 is compared with a predetermined stability margin management value (S109 in FIG. 2). When the obtained stability margin exceeds the stability margin management value, it is considered that the shaft vibration is in a stable state, and the subsequent processing is not performed. On the other hand, when the obtained stability margin is equal to or smaller than the stability margin management value, it is considered that there is a possibility that the shaft vibration may increase and a dangerous state may be caused, and the processing after S111 is executed.

When the calculated stability margin is equal to or less than the stability margin management value, the calculation unit 12 calculates a bearing oil temperature for causing the stability margin to exceed the stability margin management value (S111 in FIG. 2). This bearing oil temperature can be determined as follows.
(1) Since the bearing load is determined, the bearing oil temperature, the elastic coefficient, and the damping coefficient have a one-to-one relationship. Therefore, each coefficient is calculated using the bearing oil temperature as a parameter.
(2) Using the obtained coefficients, a complex eigenvalue analysis using the above-described vibration analysis model is performed, and a bearing oil temperature for making the stability margin higher than the control value is calculated.

The calculation unit 12 transfers the calculated bearing oil supply temperature to the control unit 13. The controller 13 adjusts the temperature of the lubricating oil supplied to the bearings 3, 4, 5 and 6 (bearing oiling temperature) based on the received bearing oiling temperature (S113 in FIG. 2). The bearing oil supply temperature is adjusted by adjusting the opening degree of the flow control valve 8 disposed in the cooling water supply passage 9.

  As described above, it is possible to prevent an increase in the vibrations of the bearings 3, 4, 5 and 6 in the power generation facility including the steam turbine 1 and the generator 2 (S115 in FIG. 2).

<Second Embodiment>
Next, a second embodiment according to the present invention will be described.
FIG. 3 is a block diagram showing a configuration of the unstable vibration preventing apparatus 20 in the second embodiment.
The unstable vibration preventing device 20 is disposed in the lubricating oil supply system L of the bearings 3, 4, 5, and 6 in the power generation facility including the steam turbine 1 and the generator 2 as in the first embodiment. The bearings 3, 4, 5 and 6 are provided with waste oil temperature sensors 24, 25, 26 and 27, respectively. Waste oil temperature sensors 24, 25, 26 and 27 measure the temperature of the lubricating oil discharged from the bearings 3, 4, 5 and 6.
The lubricating oil supply system L is provided with a cooler 7, and cooling water is circulated through the cooler 7 through a cooling water supply path 9. A flow rate control valve 8 is disposed in the cooling water supply path 9, and the temperature of the lubricating oil flowing through the lubricating oil supply system L is adjusted by adjusting the opening degree of the flow rate control valve 8.

The unstable vibration preventing apparatus 20 includes a waste oil temperature monitoring unit 21, a calculation unit 22, and a control unit 23. In the following, a processing procedure by the unstable vibration preventing apparatus 20 will be described with reference to FIG.
The waste oil temperature monitoring unit 21 monitors changes in the waste oil temperature from the bearings based on information from the waste oil temperature sensors 24, 25, 26 and 27. When there is a change in the load, the waste oil temperature changes corresponding to the change in the load. Therefore, monitoring the waste oil temperature is equivalent to monitoring the load change (FIG. 4, S201, S203).

When there is a change in the waste oil temperature, the waste oil temperature monitoring unit 21 outputs the changed waste oil temperature to the calculation unit 22.
The calculating unit 22 calculates bearing characteristics based on the waste oil temperature received from the waste oil temperature monitoring unit 21 (S205 in FIG. 4). This bearing characteristic can be obtained in the same manner as in the first embodiment.

When the bearing characteristics are calculated, the calculation unit 22 predicts the shaft vibration stability margin after the load change based on the calculation result (S207 in FIG. 4). The stability margin of shaft vibration can be obtained in the same manner as in the first embodiment.

  The stability margin obtained by the calculation unit 22 is compared with a predetermined stability margin management value (S209 in FIG. 4). This comparison is the same as in the first embodiment. When the obtained stability margin exceeds the stability margin management value, the shaft vibration is regarded as being in a stable state, and the subsequent processing is not performed. On the other hand, when the obtained stability margin is equal to or less than the stability margin management value, it is considered that there is a possibility that the shaft vibration may increase to be in a dangerous state, and the processing after S211 is executed.

When the calculated stability margin is equal to or less than the stability margin management value, the calculation unit 22 calculates a bearing oil temperature for causing the stability margin to exceed the stability margin management value (S211 in FIG. 4). The bearing oil temperature can be calculated in the same manner as in the first embodiment.

The calculation unit 22 transfers the calculated bearing oil supply temperature to the control unit 23. The control unit 23 adjusts the temperature of the lubricating oil (bearing oiling temperature) supplied to the bearings 3, 4, 5 and 6 based on the received bearing oiling temperature (S213 in FIG. 4). The bearing oil supply temperature is adjusted by adjusting the opening degree of the flow control valve 8 disposed in the cooling water supply passage 9 (S215 in FIG. 4).

<Third Embodiment>
Next, a third embodiment according to the present invention will be described.
FIG. 5 is a block diagram showing a configuration of the unstable vibration preventing apparatus 30 according to the third embodiment.
The unstable vibration preventing device 30 is disposed in the lubricating oil supply system L of the bearings 3, 4, 5, and 6 in the power generation facility including the steam turbine 1 and the generator 2 as in the first embodiment. Further, bearing temperature sensors 34, 35, 36, and 37 are disposed on the bearings 3, 4, 5, and 6, respectively. The bearing temperature sensors 34, 35, 36 and 37 measure the temperature of the bearing metal which is a constituent member of the bearings 3, 4, 5 and 6.
The lubricating oil supply system L is provided with a cooler 7, and cooling water is circulated through the cooler 7 through a cooling water supply path 9. A flow rate control valve 8 is disposed in the cooling water supply path 9, and the temperature of the lubricating oil flowing through the lubricating oil supply system L is adjusted by adjusting the opening degree of the flow rate control valve 8.

The unstable vibration preventing device 30 includes a bearing temperature monitoring unit 31, a calculation unit 32, and a control unit 33. Hereinafter, the processing procedure by the unstable vibration preventing apparatus 30 will be described with reference to FIG.
The bearing temperature monitoring unit 31 monitors changes in the bearing metal temperature based on information from the bearing temperature sensors 34, 35, 36 and 37. When the load changes, the bearing metal temperature changes corresponding to the load change. Therefore, monitoring the bearing metal temperature is equivalent to monitoring the load change (FIGS. 6 S301 and S303).

When there is a change in the bearing metal temperature, the bearing temperature monitoring unit 31 outputs the changed bearing temperature to the calculation unit 32.
The computing unit 32 calculates bearing characteristics based on the bearing metal temperature received from the bearing temperature monitoring unit 31 (S305 in FIG. 6). This bearing characteristic can be obtained in the same manner as in the first embodiment.

When the bearing characteristics are calculated, the calculation unit 32 predicts the shaft vibration stability margin after the load change based on the calculation result (S307 in FIG. 6). The stability margin of shaft vibration can be obtained in the same manner as in the first embodiment.

The stability margin obtained by the calculation unit 32 is compared with a predetermined stability margin management value (S309 in FIG. 6). This comparison is the same as in the first embodiment. When the obtained stability margin exceeds the stability margin management value, the shaft vibration is regarded as being in a stable state, and the subsequent processing is not performed. On the other hand, when the obtained stability margin is equal to or smaller than the stability margin management value, it is considered that there is a possibility that the shaft vibration may increase and a dangerous state may be caused, and the processing after S311 is executed.

When the obtained stability margin is equal to or less than the stability margin management value, the calculation unit 32 calculates a bearing oil temperature for allowing the stability margin to exceed the stability margin management value (S311 in FIG. 6). The bearing oil temperature can be calculated in the same manner as in the first embodiment.

The calculation unit 32 transfers the calculated bearing oil supply temperature to the control unit 33. Based on the received bearing oil temperature, the control unit 33 adjusts the temperature of the lubricating oil (bearing oil temperature) supplied to the bearings 3, 4, 5 and 6 (S313 in FIG. 6). The bearing oil supply temperature is adjusted by adjusting the opening of the flow control valve 8 disposed in the cooling water supply passage 9 (S315 in FIG. 6).

  In addition to the above, when the bearings 3, 4, 5 and 6 are tilting pad bearings, the bearing temperature sensors 34, 35, 36 and 37 measure the temperature of the bearing pads. The processing procedure in that case is shown in FIG. When the bearings 3, 4, 5 and 6 are sleeve bearings, the bearing temperature sensors 34, 35, 36 and 37 measure the temperature of the bearing sleeve. The processing procedure in that case is shown in FIG. The processing procedures in FIGS. 7 and 8 are the same as those shown in FIG.

<Fourth Embodiment>
In the first to third embodiments described above, the unstable vibration preventing apparatus 10 (20, 30) has been described as an apparatus for preventing unstable shaft vibration in a power generation facility including the steam turbine 1. The present invention can also be applied to machines and equipment other than the power generation equipment provided with the steam turbine 1. For example, a rotary machine driven through a gear, specifically, a steam turbine-driven or electric motor-driven compressor, blower, pump, or the like. FIG. 9 shows a processing procedure for preventing unstable vibration in this rotating machine. As will be described below, this processing procedure is basically the same as the processing procedure of the first embodiment shown in FIG. 1, and the apparatus for performing the processing is the same as that of the first embodiment. The same thing is enough.

As shown in FIG. 9, when a load change command (S601 in FIG. 9) is received, the gear bearing load and bearing oil (lubricating oil) temperature after the load change are predicted (S603 in FIG. 9). The gear bearing means a bearing that supports a rotating machine driven by a gear.
As in the first embodiment, the gear bearing load and the bearing oil temperature corresponding to the load are obtained in advance.
Next, based on the bearing load corresponding to the load and the bearing oil temperature, the bearing characteristics after the load is changed are calculated (S605 in FIG. 9).
When the bearing characteristics are calculated, the shaft vibration stability margin after the load change is predicted based on the calculation result (S607 in FIG. 9). As described above, the stability margin of the shaft vibration can be obtained based on the previously obtained elastic coefficient and damping coefficient.

Next, the obtained stability margin is compared with a predetermined stability margin management value (S6 in FIG. 9).
09). When the obtained stability margin exceeds the stability margin management value, it is considered that the shaft vibration is in a stable state, and the subsequent processing is not performed. On the other hand, when the obtained stability margin is equal to or less than the stability margin management value, it is considered that there is a possibility that the shaft vibration may increase to be in a dangerous state, and the processing after S611 is executed.
When the obtained stability margin is equal to or smaller than the stability margin management value, the bearing oil temperature for causing the stability margin to exceed the stability margin management value is calculated (S611 in FIG. 9).

When the bearing is a sleeve bearing, the temperature of the lubricating oil (bearing oil temperature) for supplying the sleeve temperature to the bearing is adjusted based on the calculated bearing oil temperature (S613 in FIG. 9).
. Alternatively, an increase in vibration can be prevented by adjusting the supply of other cooling media, such as water, to the sleeve. When the bearing is a tilting pad bearing, as shown in FIG. 10, the temperature of the lubricating oil (bearing oil supply temperature) for supplying the temperature of the bearing pad to the bearing is adjusted. Alternatively, an increase in vibration can be prevented by adjusting the supply of other cooling medium, for example, water to the sleeve (S615 in FIG. 9).

It is a block diagram which shows the structure of the unstable vibration prevention apparatus in 1st Embodiment. It is a flowchart which shows the vibration control procedure of the unstable vibration prevention apparatus in 1st Embodiment. It is a block diagram which shows the structure of the unstable vibration prevention apparatus in 2nd Embodiment. It is a flowchart which shows the vibration control procedure of the unstable vibration prevention apparatus in 2nd Embodiment. It is a block diagram which shows the structure of the unstable vibration prevention apparatus in 3rd Embodiment. It is a flowchart which shows the vibration control procedure of the unstable vibration prevention apparatus in 3rd Embodiment. It is a flowchart which shows the vibration control procedure by the modification of the unstable vibration prevention apparatus in 3rd Embodiment. It is a flowchart which shows the vibration control procedure by the other modification of the unstable vibration prevention apparatus in 3rd Embodiment. It is a flowchart which shows the vibration control procedure in 4th Embodiment. It is a flowchart which shows the modification of the vibration control procedure in 4th Embodiment. It is a graph which shows the relationship between the load of a bearing, and a damping ratio.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steam turbine, 2 ... Generator, 3, 4, 5, 6 ... Bearing, 7 ... Cooler, 8 ... Flow control valve, 9 ... Cooling water supply path 10, 20, 30 ... Unstable vibration prevention device, DESCRIPTION OF SYMBOLS 11 ... Load change receiving part, 12, 22, 32 ... Calculation part, 13, 23, 33 ... Control part, 21 ... Waste oil temperature monitoring part, 31 ... Bearing temperature monitoring part

Claims (6)

An apparatus for preventing unstable shaft system vibration caused by load change of a rotating body supported by a bearing,
While calculating the stability margin of shaft vibration from the bearing characteristics based on the load change, an arithmetic processing unit that compares this stability margin with a predetermined reference value,
A control unit that controls the temperature of the bearing based on a comparison result between the calculated stability margin and the predetermined reference value;
A shaft system unstable vibration preventing device comprising:   2. The shaft system unstable vibration preventing device according to claim 1, wherein the bearing characteristics based on the load change are obtained based on a prediction of a bearing load and / or a lubricating oil temperature of the bearing after the load change.   2. The shaft system unstable vibration preventing device according to claim 1, wherein the bearing characteristic based on the load change is obtained based on an actual measurement value of a temperature of lubricating oil of the bearing.   2. The shaft system unstable vibration preventing device according to claim 1, wherein the bearing characteristic based on the load change is obtained based on an actual measurement value of a temperature of a member constituting the bearing.   The shaft system unstable vibration preventing device according to any one of claims 1 to 4, wherein the rotating body is driven through a gear.   2. The temperature of the bearing is controlled by controlling the temperature of the lubricating oil supplied to the bearing or by supplying a cooling medium other than the lubricating oil to the bearing. The shaft system unstable vibration prevention apparatus in any one of -5.

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