JP2010019228A - Blade random vibration monitoring system of rotary machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize operational limitation, while surely avoiding random vibration of a moving blade, in a rotary machine such as a steam turbine. <P>SOLUTION: This blade random vibration monitoring system 11 has a pressure measuring device 15 and a warning device 16. The pressure measuring device outputs a time history waveform of a measured pressure value Pi by measuring monitoring position variation pressure by a pressure sensor 17. The warning device 16 determines an entrance into a random vibration area of the moving blade of a monitoring object, and gives a warning when determined as entering the random vibration area. A determination of the entrance into the random vibration area of the moving blade is performed by determining σ<SB>pi</SB>≥σ<SB>pi_thre</SB>on an operation limiting value σ<SB>pi_thre</SB>with a standard deviation σ<SB>pi</SB>of the measured pressure value Pi as an index. The operation limiting value σ<SB>pi_thre</SB>is determined by using a high correlation between an annulus speed-vibration stress characteristic curve and an annulus speed-variation pressure characteristic curve. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a blade random vibration monitoring system for monitoring random vibration that may occur in a moving blade of a rotating machine in which a plurality of paragraphs each including a moving blade and a stationary blade are provided in the axial direction, and particularly in a power plant. The present invention relates to a blade random vibration monitoring system suitable for a steam turbine or the like.

  For example, a rotating machine having blades such as a steam turbine, a gas turbine, or an axial flow compressor is usually configured to have a plurality of stages each including a moving blade and a stationary blade in the axial direction. In such a rotating machine, it is inevitable that vibration is generated in the rotor blade, and vibration monitoring is required particularly in a low load region.

  Random vibration is vibration with large vibration stress that may cause serious damage or destruction to the rotor blades. For example, in a steam turbine used in a general power plant, the load change is large, so measures against random vibration are taken. Is particularly necessary.

  In the power generation industry, a system is generally adopted in which a nuclear power plant is used as a base load operation, and supply adjustment according to power demand on the load side is performed in a thermal power plant. In such a case, the steam turbine of a thermal power plant requires a wide load range for load following operation, so a large load fluctuation is unavoidable and the load is likely to enter a random vibration range. There is considerable possibility of operation, and in a steam turbine for a thermal power plant, such a random vibration problem may be further promoted by the tendency to reduce the number of passenger compartments and make the blades longer.

  In addition, for nuclear power plants, if it becomes difficult to rely only on thermal power plants for power supply adjustment due to an increase in the ratio of nuclear power generation, there is a possibility that output adjustment in a wide range may be required. In this case, the steam turbine of a nuclear power plant generally has a larger output and a larger volume flow rate than the steam turbine of a thermal power plant. The larger the capacity, the longer the low-pressure turbine rear stage becomes and the more likely it is to generate random vibration. There is a tendency, and the load following operation increases the possibility of operating the steam turbine with a load that may enter a random vibration range.

  Furthermore, in power plants, there are not a few cases where adjustment operation is performed in a wider load range than during normal operation during the trial operation period, and even in this case, the steam turbine operates with a load that may enter the random vibration range. There is a possibility that.

  For this reason, steam turbines in power plants can monitor the random vibrations of the rotor blades, that is, enable the occurrence of random vibrations to be determined in advance. It is important that the blade random vibration monitoring can be performed on the moving blade in any paragraph as a monitoring target so that the occurrence of random vibration can be avoided.

  In principle, the blade random vibration monitoring can be performed by using the actual vibration stress in the moving blade as an index for entering the random vibration region. By doing so, the most accurate monitoring can be performed. However, since the moving blade is a rotating element, it is practically difficult to apply the direct measurement of the moving blade vibration stress to the actual machine. Therefore, in order to be able to perform blade random vibration monitoring practically, it is necessary to use indices other than vibration stress as an index for entering a random vibration region.

  As such blade random vibration monitoring, for example, each technique disclosed in Patent Documents 1 to 3 is known. These conventional technologies measure the fluctuating pressure (pressure that changes in magnitude over time) in the vicinity of the moving blade in the paragraph to be monitored, and make it possible to make a prior decision on the occurrence of random vibration based on the fluctuating pressure measurement value. (Patent Literature 1 and Patent Literature 2), and it is possible to make a preliminary determination of random vibration generation using the axial flow Mach number and the exhaust pressure (Patent Literature 3).

JP-A-62-182402 JP 2004-211704 A JP-A-62-82206

  The blade random vibration monitoring as described above involves a problem related to operation restriction that is required when it is determined that random vibration is generated, as described in Patent Document 3, for example. That is, it is a problem that the operation restriction should be optimized so as to reduce the operation restriction as much as possible, and that the generation of random vibration can be surely avoided. These operational limitation problems are becoming more and more important for steam turbines in power plants that tend to increase the chances of low-load operation that can enter the random vibration range as described above. This technology does not necessarily provide a sufficient solution.

  For example, in the case of Patent Document 3, the operation restriction region can be narrowed by making a prior determination of the occurrence of random vibration using the axial flow Mach number and the exhaust pressure. However, even though the axial flow Mach number and exhaust pressure correlate with the vibration of the rotor blade, the accuracy based on the high correlation with the vibration stress is not used, so the accuracy is not necessarily high, and it is not stable. It is inevitable that the limit value related to the notification of the driving restriction alarm becomes somewhat large, and the possibility that unnecessary driving restrictions are made accordingly increases.

  The same can be said for the techniques of Patent Document 1 and Patent Document 2 using fluctuating pressure as an index. In other words, in order to achieve optimization of operational restrictions and reliable avoidance of random vibrations using a method that determines the occurrence of random vibrations in advance based on fluctuating pressures, the limit values set for fluctuating pressures and actual blade damage or destruction The techniques of Patent Document 1 and Patent Document 2 are not necessarily sufficient, such as no direct reference to the correspondence with the limit value of the vibration stress that causes

  The present invention has been made in the background of the above circumstances, and its problem is to optimize operational restrictions for a rotating machine such as a steam turbine while reliably avoiding random vibration of moving blades. It is to provide a wing random vibration monitoring system that can achieve this.

  The inventors of the present invention focused on the correlation between the vibration stress in the moving blade and the fluctuating pressure in the vicinity of the moving blade, and have conducted tests and analyzes using a turbine model from various angles. According to the knowledge obtained as a result, there is a correlation between the vibrational stress and the fluctuating pressure via the annular velocity (also called the annular velocity). Specifically, it is as follows.

  As the fluctuating pressure, a monitoring position fluctuating pressure that is a fluctuating pressure at a specific part is used. Specifically, the fluctuating pressure in the flow path surrounded by the diaphragm (external diaphragm) and the stationary blade on the upstream side or downstream side adjacent to the monitoring target moving blade is used as the monitoring position changing pressure. For the monitoring position fluctuation pressure, the monitoring position fluctuation on the ring speed-fluctuation pressure coordinate system with the ring speed as one axis (usually the horizontal axis) and the fluctuation pressure as the other axis (usually the vertical axis) Annular velocity-fluctuating pressure characteristic curve is obtained by plotting the pressure in correspondence with the monitoring position annular velocity which is the annular velocity at the outlet of the monitored moving blade stage. On the other hand, plot the vibration stress of the monitored blade in relation to the monitoring position ring speed on the ring speed-vibration stress coordinate system with the ring speed as one axis and the vibration stress as the other axis. To obtain the annulus velocity-vibration stress characteristic curve.

  These annulus velocity-fluctuating pressure characteristic curves and annulus velocity-vibration stress characteristic curves have a very high positive correlation. Therefore, the annular velocity-vibration stress characteristic curve for the monitored moving blade and the vibrational stress limit value for the moving blade (this is determined as the fatigue limit of the moving blade based on material strength, etc.) The intersection point on the stress coordinate system is obtained, the ring speed corresponding to the intersection point is obtained on the ring speed-vibration stress coordinate system, and the fluctuating pressure corresponding to the ring speed is obtained from the ring speed-fluctuating pressure coordinate. Ask on the system. Then, the fluctuating pressure becomes extremely accurate as a limit value for performing the preliminary determination of the occurrence of random vibration using the monitoring position fluctuating pressure as an index for entering the random vibration range, and the operation restriction is optimized by minimizing the operation restriction. It becomes an operation limit value that enables reliable avoidance of random vibration while achieving the above.

  The present invention solves the above problems based on the above knowledge. Therefore, the present invention is directed to the rotating blades in any of the above paragraphs for random vibrations that may occur in the moving blades of a rotary machine in which a plurality of paragraphs composed of moving blades and stationary blades are provided in the axial direction. In the blade random vibration monitoring system for monitoring, the monitoring position fluctuation pressure, which is the fluctuation pressure in the flow path surrounded by the diaphragm and the stationary blade on the upstream side or downstream side adjacent to the monitoring target moving blade, is detected. Is determined based on an operation limit value set in advance, and an alarm is issued when the monitored position fluctuation pressure exceeds the operation limit value. On the ring velocity-vibration stress coordinate system with the vibration stress as the other axis and the vibration stress of the monitored moving blade, the vibration position of the monitored moving blade is the ring position velocity at the exit of the monitored moving blade stage. On the annular velocity-fluctuating pressure coordinate system, the annular velocity-vibration stress characteristic curve obtained by plotting in accordance with the degree of vibration and the annular velocity as one axis and the fluctuating pressure as the other axis The position fluctuation pressure is obtained on the basis of the ring speed-fluctuation pressure characteristic curve obtained by plotting the position fluctuation pressure corresponding to the monitoring position ring speed, and the ring speed-vibration stress characteristic curve regarding the monitored moving blade And the vibrational stress limit value on the ring velocity-vibration stress coordinate system, the ring velocity corresponding to the intersection is obtained on the ring velocity-vibration stress coordinate system, and the ring velocity The variation pressure corresponding to is obtained on the annular velocity-variation pressure coordinate system, and the variation pressure is set as the operation limit value.

  The monitoring position ring speed in the blade random vibration monitoring system as described above can be replaced with the volume flow rate at the outlet of the monitored moving blade stage, that is, the monitoring position volume flow rate. Therefore, the present invention is directed to the rotating blades in any of the above paragraphs for random vibration that may occur in the moving blades of a rotating machine in which a plurality of paragraphs each including a moving blade and a stationary blade are provided in the axial direction. In the blade random vibration monitoring system for monitoring, the monitoring position fluctuation pressure, which is the fluctuation pressure in the flow path surrounded by the diaphragm and the stationary blade on the upstream side or downstream side adjacent to the monitoring target moving blade, is detected. Is determined based on a preset operation limit value, and an alarm is issued when the monitored position fluctuation pressure exceeds the operation limit value. On the volume flow-vibration stress coordinate system with the vibration stress as the axis and the vibration flow as the other axis, the vibration stress of the monitored moving blade is the volume flow rate at the outlet of the monitored moving blade stage. On the volume flow-vibration pressure coordinate system where the volume flow rate-vibration stress characteristic curve obtained by plotting in accordance with the volume and the volume flow rate as one axis and the fluctuating pressure as the other axis, the monitored position fluctuation pressure Of the volume flow rate-vibration stress characteristic curve and the vibration stress limit value for the monitored moving blade. Obtaining an intersection point on the volume flow rate-vibration stress coordinate system, obtaining a volume flow rate corresponding to the intersection point on the volume flow rate-vibration stress coordinate system, and further calculating a fluctuating pressure corresponding to the volume flow rate- It is obtained on a fluctuating pressure coordinate system, and the fluctuating pressure is set as the operation limit value.

  According to the present invention, in the blade random vibration monitoring system as described above, the monitoring position fluctuation pressure is preferably measured through a pressure sensor provided on the diaphragm wall surface or the blade surface of the stationary blade. Yes.

  According to the present invention as described above, it is possible to optimize operation restrictions for a rotary machine such as a steam turbine while reliably avoiding random vibration of the moving blades.

  Hereinafter, modes for carrying out the present invention will be described. The blade random vibration monitoring system according to the present invention is applied to a nuclear power plant as shown in FIG. 1 as an example. The nuclear power plant in FIG. 1 is a typical example of a boiling water type, and generates high-temperature and high-pressure steam by boiling water using heat generated in a fission reaction in the core 2 of the reactor pressure vessel 1. The generated steam flows down the main steam pipe 3 and flows into the high-pressure turbine 4. The steam that has worked in the high-pressure turbine 4 flows into the low-pressure turbine 5 through a moisture separation superheater (not shown). The low-pressure turbine 5 transmits rotational power to the generator 7 via the rotor 6, whereby the generator 7 is rotationally driven to generate power. The steam that has worked in the low-pressure turbine 5 is led from the low-pressure turbine outlet to the condenser 8 where it is condensed and becomes condensate. The condensate generated in the condenser 8 is boosted by the condensate pump 9 and returned to the reactor pressure vessel 1 through a feed water heater and a feed water pump (not shown).

  In the nuclear power plant as described above, the blade random vibration monitoring system according to the present invention is applied to, for example, the low-pressure turbine 5. FIG. 2 schematically shows the configuration of the blade random vibration monitoring system 11 according to the first embodiment when applied to the low pressure turbine 5 together with the relationship with the low pressure turbine 5. The blade random vibration monitoring system 11 is applied to the low-pressure turbine 5 as described above. Therefore, the blade random vibration monitoring system 11 is an example when the rotating machine to be monitored for blade random vibration is a steam turbine.

  The low-pressure turbine 5 is a double-flow type, and has symmetrical left and right turbine portions 5L and 5R. Each of the turbine parts 5L and 5R includes a plurality of paragraphs including a stationary blade 12 which is fixedly supported by a diaphragm and is stationary and a rotor blade 13 which is implanted in the rotor 6 and is rotatable. In the example, four stages are provided as the L-0 stage, the L-1 stage, the L-2 stage, and the L-3 stage from the downstream side to the upstream side, and the steam 14 from the high-pressure turbine 4 is divided into left and right. Are allowed to flow into each. In the case of such a double flow type, the blade random vibration monitoring is performed for each turbine unit 5L, 5R, but FIG. 2 shows only the portion related to the left turbine unit 5L in the configuration of the blade random vibration monitoring system 11. The right turbine portion 5R is not shown because it has the same configuration. In the following, i = 0 to 3 is used to distinguish data about each paragraph in correspondence with paragraph numbers 0 to 3 in the L-0, L-1, L-2, and L-3 stages. And

  The blade random vibration monitoring system 11 functions to monitor a random vibration that may occur in the moving blade 13 for any paragraph, and includes a pressure measuring device 15 and an alarm device 16 for that purpose.

  The pressure measuring device 15 is a monitoring position fluctuation pressure used as an index for a random vibration region in random vibration monitoring, that is, a moving blade to be monitored (L-0 stage, L-1 stage, L- Fluctuating pressure in a steam channel (fluid channel) surrounded by a diaphragm and a stationary blade on the upstream side or downstream side adjacent to the moving blades in each of the two stages is measured. The monitoring position fluctuation pressure is measured by the pressure measuring device 15 by converting the pressure detection signal Vi obtained as a voltage signal by the pressure sensor 17 provided in the low-pressure turbine 5 so that the monitoring position fluctuation pressure can be detected, and the actually measured pressure value Pi. It is done by asking for. Accordingly, the pressure measuring device 15 outputs the actually measured pressure value Pi related to the monitored position fluctuation pressure as a time history waveform for each paragraph corresponding to the moving blade to be monitored. FIG. 3 shows an example of a time history waveform of the actually measured pressure value Pi. This time history waveform is a random vibration state generated experimentally.

  4 and 5 show examples of the installation structure of the pressure sensor 17. Here, the terms inner periphery and outer periphery refer to the inner periphery and the outer periphery when viewed in the steam flow path. FIG. 4 schematically shows a state in which the outer peripheral wall surface is viewed from the inner peripheral side of the diaphragm 18 which is an element for fixedly supporting the stationary blade 12, and FIG. 5 shows L-0, L-1, L- FIG. 2 schematically shows a state in which each of the two paragraphs is sectioned on the meridian plane. In the example of FIGS. 4 and 5, the outer periphery of the diaphragm 18 supporting the stationary blade (for example, the L-0 stage stationary blade 12) closest to the monitored moving blade (for example, the L-0 stage blade 13). Pressure sensors 17 are provided on the wall surface and the outer peripheral wall surface of the downstream exhaust part, respectively, and thereby, the fluctuating pressure in the steam flow path surrounded by the diaphragm and the stationary blade on the upstream side or downstream side adjacent to the moving blade to be monitored Can be measured as the monitoring position fluctuation pressure. When the monitoring target is the L-0 stage, there is usually no diaphragm or stationary blade downstream of the L-0 stage moving blade, so the expression of the steam flow path surrounded by the diaphragm and stationary blade is L-0 stage. It can be replaced with a steam passage surrounded by the inner and outer peripheral wall surfaces of the exhaust part. Here, as the pressure sensor 17, it is desirable to use a semiconductor pressure sensor having a wide frequency response range such as a resonance frequency of several tens k to several hundreds kHz.

  The warning device 16 determines that the moving blade to be monitored enters the random vibration range, and issues a warning about operation restriction when it is determined that the moving blade enters the random vibration range. The determination that the moving blade enters the random vibration region is performed using the monitoring position fluctuation pressure obtained as the fluctuation component of the actually measured pressure value Pi as an index. Here, it is preferable to use the standard deviation of the actually measured pressure value Pi as the fluctuation component, and this is also the case in this embodiment. For this purpose, the alarm device 16 includes a standard deviation calculation unit 21, a limit value database 22, and an alarm unit 23.

The standard deviation calculation unit 21 obtains a standard deviation σ _pi (measured variation pressure standard deviation σ _pi ) at an appropriate sampling interval for the actual pressure value Pi provided from the pressure measuring device 15.

The limit value database 22 is used to store the operation limit value σ _{pi_thre} obtained as described later with respect to the monitored position fluctuation pressure as an index for the random vibration range for each paragraph corresponding to the moving blade to be monitored.

The alarm unit 23 includes a determination unit 24, and determines σ _pi ≧ σ _{pi_thre} for the measured fluctuation pressure standard deviation σ _pi provided from the standard deviation calculation unit 21 and the operation limit value σ _{pi_thre} fetched from the limit value database 22. If the result of the determination is affirmative, an alarm is issued.

Hereinafter, a method of _obtaining the operation limit value σ _{pi_thre} will be described. The operation limit value σ _{pi_thre} is obtained using an annular velocity-vibration stress characteristic curve Cvi as shown in FIG. 6A and an annular velocity-variable pressure characteristic curve Cpi as shown in FIG. 6B. . Here, the ring speed-vibration stress characteristic curve Cvi is a curve obtained on the ring speed-vibration stress coordinate system in which the ring speed is the horizontal axis and the vibration stress is the vertical axis. The stress is obtained by plotting the stress corresponding to the monitored position annular velocity, that is, the annular velocity at the outlet of the monitored moving blade stage. On the other hand, the annular velocity-variable pressure characteristic curve Cpi is a curve obtained on the annular velocity-variable pressure coordinate system with the annular velocity as the horizontal axis and the variable pressure, specifically, the standard deviation of the variable pressure as the vertical axis. It is obtained by plotting the monitoring position fluctuation pressure corresponding to the monitoring position ring speed.

As shown in FIG. 6, the annular velocity-vibration stress characteristic curve Cvi and the annular velocity-variable pressure characteristic curve Cpi have a very high positive correlation. The operation limit value σ _{pi_thre} is obtained using such correlation. Specifically, first, the vibration stress limit value S _{i_thre} of the moving blade to be monitored is obtained as a fatigue limit of the rotor blade based on material strength or the like (appropriately considering the safety factor), and this vibration stress limit value S _{i_thre is obtained.} And the intersection Ta of the ring velocity-vibration stress characteristic curve Cvi regarding the moving blade to be monitored are obtained on the ring velocity-vibration stress coordinate system. There are two intersections of the vibrational stress limit value S _{i_thre with} the annular velocity-vibration stress characteristic curve Cvi, and the intersection on the side with the larger annular velocity is the intersection Ta. Then annulus velocity U _{I_thre} the annulus speed corresponding to the intersection Ta - calculated on fluctuating pressure coordinate system, and variable pressure, i.e. annulus velocity U _{I_thre} and annulus velocity corresponding to the annulus velocity _U i_thre - fluctuating pressure A fluctuation pressure limit value σ _{pi_thre} is obtained as a fluctuation pressure (standard deviation of the fluctuation pressure) corresponding to the intersection Tb of the characteristic curve Cpi, and this is set as an operation limit value σ _{pi_thre,} and a range in which the fluctuation pressure is larger than the operation limit value σ _{pi_thre} (see FIG. The hatched part in Fig. 2 is the range where warnings are issued for driving restrictions.

The operation limit value σ _{pi_thre} obtained as described above is extremely accurate as a limit value for issuing an operation limit alarm by making a prior determination of the occurrence of random vibration of the rotor blade using the monitoring position fluctuation pressure as an index for entering the random vibration range. Will be expensive. In other words, the operation limit value σ _{pi_thre} is an operation limit value that makes it possible to reliably avoid random vibration while optimizing the operation limit with the operation limit as a minimum.

Here, the ring speed-vibration stress characteristic curve Cvi and the ring speed-fluctuating pressure characteristic curve Cpi are tests based on actual operating conditions for a model steam turbine having the same configuration as the steam turbine to be monitored for blade random vibration. It will be asked by doing. In the test, the ring speed-vibration stress characteristic curve Cvi and the ring speed-fluctuating pressure characteristic curve Cpi are obtained for each paragraph (paragraph number i = 0 to n) corresponding to the monitored moving blade, and the monitoring obtained from them. The operation limit value σ _{pi_thre} for each target blade is stored in the limit value database 22 and used.

  The monitoring position ring speed in the blade random vibration monitoring system 11 as described above can be replaced with the volume flow rate at the paragraph outlet in the paragraph corresponding to the moving blade to be monitored. In such a case, the monitoring position volume flow rate, which is the volume flow rate at the exit of the paragraph corresponding to the moving blade to be monitored, is used instead of the monitoring position annular velocity, and the annular velocity-vibration stress characteristic curve is used. Instead, a volume flow rate-vibration stress characteristic curve is used, and a volume flow rate-fluctuation pressure characteristic curve is used instead of the annular velocity-fluctuation pressure characteristic curve.

  FIG. 7 schematically shows the configuration of the blade random vibration monitoring system 31 according to the second embodiment together with the relationship with the low-pressure turbine 5. The blade random vibration monitoring system 31 according to the present embodiment is basically the same as the blade random vibration monitoring system 11 of FIG. Therefore, the characteristic configuration of the blade random vibration monitoring system 31 will be mainly described below, and the above description is used for the configuration common to the blade random vibration monitoring system 11. In FIG. 7, the alarm device 16 is shown in a simplified manner, but its detailed configuration is the same as described above.

  The trend creation device 32 includes a ring speed calculation unit 33, a characteristic curve database 34, and a trend creation unit 35. The annular velocity calculation unit 33 calculates the actual annular velocity for each of the paragraphs corresponding to the monitored moving blades in the low-pressure turbine 5 being monitored. The ring speed calculation processing by the ring speed calculation unit 33 is performed according to the flow shown in FIG. 8 as an example. That is, the actual output data such as the output of the generator connected to the low-pressure turbine 5, the inlet / outlet of each paragraph in the low-pressure turbine 5 and the pressure and temperature of the extraction paragraph are acquired, and then the paragraph of each monitored paragraph is calculated by the heat / flow rate balance calculation. The mass flow rate and the extraction stage extraction amount are obtained. Then, the annular velocity is calculated from the paragraph mass flow rate, the actually measured pressure value Pi (which is used as an average value at an appropriate sampling interval), the specific volume, the annular channel area, and the like of the monitored paragraph.

  In addition to the above method, the ring speed calculation can be performed by a method in which sensors are directly installed at necessary locations to acquire data. However, the above-described method using the heat / flow rate balance calculation does not require processing of the turbine casing accompanying the arrangement of various sensors to the low-pressure turbine 5, and is simple and secures an appropriate accuracy. It is excellent in that point.

  The characteristic curve database 34 is used to store the annular velocity-fluctuating pressure characteristic curve obtained as described above for each paragraph corresponding to the monitored moving blade in the low-pressure turbine 5.

The trend creation unit 35 creates a measured pressure value trend on the annular velocity-fluctuating pressure characteristic curve. Specifically, as shown in FIG. 9, the standard deviation σ _pi of the actually measured pressure value Pi is obtained from the annular velocity calculation unit 33 on the annular velocity-variable pressure characteristic curve Cpi obtained from the characteristic curve database 34. The actual pressure value trend is created by plotting with the annular velocity. In this case, the time interval of the plot depends on the sampling interval, but can be arbitrarily set as the setting of the sampling interval.

  The measured pressure value trend created by the trend creation device 32 is displayed on, for example, a monitor device. Therefore, the blade random vibration monitoring system 31 can operate the low-pressure turbine 5 while monitoring the trend of the actually measured pressure value on the annular speed-variable pressure characteristic curve.

  As mentioned above, although the form for implementing this invention was demonstrated, these are only representative examples, This invention can be implemented with various forms in the range which does not deviate from the meaning. For example, in the above-described embodiment, the pressure sensor is provided on the outer peripheral wall surface of the diaphragm, but it is not always necessary to do so. In short, it is only necessary to install a pressure sensor so that the monitoring position fluctuating pressure, that is, the fluctuating pressure in the flow path surrounded by the diaphragm and stationary blade on the upstream side or downstream side adjacent to the moving blade to be monitored can be detected appropriately. For example, it may be provided on the blade surface of the stationary blade adjacent to the moving blade to be monitored, or on the channel side wall surface in the vicinity of the stationary blade. A plurality of pressure sensors may be provided for each paragraph to be monitored. In such a case, the annular velocity-fluctuating pressure characteristic curve and the annular velocity-vibration stress for each installation position of the pressure sensor. It is also possible to obtain a characteristic curve and use the fluctuating pressure limit value for each installation position of the pressure sensor obtained thereby as the operation limit value.

  In the above embodiment, the L-0 stage to the L-2 stage are monitored, but if the blades are further increased in the future, random vibration may become a problem even further upstream. In such a case, the paragraph upstream of the L-2 stage is also targeted.

  In the above-described embodiment, the steam turbine is a target. However, the present invention can be applied to any rotating machine that may generate random vibrations on the moving blades.

It is a figure which shows typically the structure of the nuclear power plant to which the blade random vibration monitoring system by this invention is applied. It is a figure which shows the structure of the blade random vibration monitoring system by 1st Embodiment. It is a figure which shows an example of the time history waveform of measured pressure value. It is a figure which shows typically the state which looked at the outer peripheral wall surface from the inner peripheral side of the diaphragm in which the pressure sensor was installed. It is a figure which shows typically in the state which carried out the cross section of some paragraphs. It is a figure which shows the correlation of annulus velocity-vibration stress characteristic curve and annulus velocity-variable pressure characteristic curve. It is a figure which shows the structure of the blade random vibration monitoring system by 2nd Embodiment. It is a figure which shows the flow of an annular speed calculation process. It is a figure explaining creation of a measurement pressure value trend.

Explanation of symbols

5 Low pressure turbine (rotary machine)
11, 31 Blade random vibration monitoring system 12 Stator blade 13 Rotor blade 17 Pressure sensor 18 Diaphragm Cvi Ring velocity-vibration stress characteristic curve Cpi Ring velocity-fluctuating pressure characteristic curve L-0 to L-3 Paragraph Ta intersection

Claims (3)

A blade for monitoring a random vibration that may occur in the moving blade for the rotating blade in any of the paragraphs, with respect to a rotary machine in which a plurality of paragraphs including a moving blade and a stationary blade are provided in the axial direction In random vibration monitoring system,
Based on the operation limit value set in advance with respect to the monitoring position fluctuation pressure, the monitoring position fluctuation pressure, which is the fluctuation pressure in the flow path surrounded by the diaphragm and the stationary blade on the upstream side or downstream side adjacent to the monitoring target moving blade A warning is issued when the monitored position fluctuation pressure exceeds the operation limit value,
The operation limit value is obtained by calculating the vibration stress of the monitored moving blade at the exit of the monitored moving blade stage on the annular velocity-vibrating stress coordinate system where the annular velocity is one axis and the vibration stress is the other axis. Annular velocity obtained by plotting corresponding to the annular velocity at the monitoring position, which is the annular velocity-Annular velocity with the vibrational velocity characteristic curve as one axis and the annular velocity as the other axis- On the fluctuating pressure coordinate system, the monitoring position fluctuating pressure is obtained based on a ring velocity-fluctuating pressure characteristic curve obtained by plotting the monitoring position fluctuating pressure corresponding to the monitoring position ring velocity,
Then, an intersection point of the annular velocity-vibration stress characteristic curve and the vibration stress limit value on the monitored moving blade on the annular velocity-vibration stress coordinate system is obtained, and the annular velocity corresponding to the intersection point is calculated as the ring velocity. It is obtained on the belt speed-vibration stress coordinate system, and the fluctuation pressure corresponding to the ring speed is obtained on the ring speed-fluctuation pressure coordinate system, and the fluctuation pressure is set as the operation limit value. Wing random vibration monitoring system. A blade for monitoring a random vibration that may occur in the moving blade for the rotating blade in any of the paragraphs, with respect to a rotary machine in which a plurality of paragraphs including a moving blade and a stationary blade are provided in the axial direction In random vibration monitoring system,
Based on the operation limit value set in advance with respect to the monitoring position fluctuation pressure, the monitoring position fluctuation pressure, which is the fluctuation pressure in the flow path surrounded by the diaphragm and the stationary blade on the upstream side or downstream side adjacent to the monitoring target moving blade A warning is issued when the monitored position fluctuation pressure exceeds the operation limit value,
The operation limit value is the volume flow rate at the outlet of the monitored moving blade stage on the volume flow-vibration stress coordinate system where the volume flow rate is one axis and the vibration stress is the other axis. On the volume flow-vibration pressure coordinate system with the volume flow-vibration stress characteristic curve obtained by plotting corresponding to the monitoring position volume flow, and the volume flow as one axis and the variable pressure as the other axis, The monitoring position fluctuation pressure is obtained based on a volume flow rate-fluctuation pressure characteristic curve obtained by plotting the monitoring position fluctuation flow corresponding to the monitoring position volume flow,
Then, an intersection point of the volume flow rate-vibration stress characteristic curve and the vibration stress limit value on the monitored moving blade on the volume flow rate-vibration stress coordinate system is obtained, and the volume flow rate corresponding to the intersection point is determined as the volume flow rate-vibration rate. A blade characterized in that it is obtained on a stress coordinate system, and further, a fluctuating pressure corresponding to the volume flow rate is obtained on the volume flow-fluctuating pressure coordinate system, and the fluctuating pressure is set as the operation limit value. Random vibration monitoring system.   3. The blade random vibration monitoring according to claim 1, wherein the monitoring position fluctuation pressure is measured via a pressure sensor provided on the diaphragm wall surface or the blade surface of the stationary blade. system.

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