JPH0334573B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a remaining life diagnosing device for diagnosing the remaining life of an existing prime mover used in a temperature range where creep damage to materials becomes a problem.

[Technical background of the invention]

In general, prime movers such as steam turbines and gas turbines that operate using high-temperature, high-pressure fluids generate unsteady thermal stress due to uneven temperature distribution inside the components when starting and stopping the plant, and fatigue damage accumulates due to repeated stress. do. On the other hand, during steady operation of such a prime mover, creep damage accumulates due to centrifugal force or internal pressure stress. When the sum of the above-mentioned two damage accumulations reaches a certain limit value, cracks may occur and a serious accident may develop. These damages do not accumulate uniformly in each part of the member; for example, in the case of a turbine rotor, fatigue damage tends to accumulate in the heat group of the rotor, and creep damage tends to accumulate in the center hole and the root of the wheel.

Conventionally, as a device for diagnosing the lifespan of a prime mover, a method has already been proposed that focuses on fatigue damage or creep damage calculated using the temperature measurement results of the part to be diagnosed, and estimates the lifespan from the degree of damage. There are
Publication No. 64141). However, known life diagnosis devices diagnose the life of a rotating part using the temperature measured at a stationary part close to the surface of the rotating part (Japanese Patent Publication No. 16372/1983), or use the temperature measured at a stationary part to (Japanese Unexamined Patent Publication No. 57-64141), which diagnoses the lifespan of stationary parts based on
It cannot be applied to life diagnosis of rotating parts.

[Purpose of the invention]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an apparatus for diagnosing the remaining life of a prime mover that can estimate the remaining life of the rotating parts of an existing prime mover with high accuracy in light of the above-mentioned prior art.

[Conventional overview]

In order to achieve the above object, the present invention calculates in advance the parts of an existing plant where only creep damage accumulates, and prevents creep damage in the corresponding parts when the plant is opened during periodic inspections. This is a remaining life diagnosis device that measures hardness and other non-destructive measurement methods, and corrects the remaining life diagnosis results based on temperature measurements based on actual measurement data for creep-damaged areas.

More specifically, the remaining life diagnosing device of the present invention uses operating condition data including the temperature and pressure, rotation speed, and load of a component to be diagnosed or a component close to it in an operating prime mover measured at a stationary part. A first means of calculating the temperature distribution and stress distribution of the prime mover material by numerical analysis based on the above, and a second means of determining the fatigue damage distribution from the ratio of the number of times the prime mover is started and the fatigue life of the material determined from the temperature distribution. and a third means of determining the creep damage distribution from the ratio of the operating time of the prime mover to the creep life of the material determined from the temperature distribution and stress distribution, and a third means of determining the life consumption of the prime mover based on the fatigue damage distribution and the creep damage distribution. a fourth means for determining a portion with large creep damage and a fifth means for determining a portion with large creep damage and small fatigue damage by comparing the fatigue damage distribution and creep damage distribution; a sixth means for directly measuring the state of change in the metal composition of a portion due to creep damage when the prime mover is stopped;
A seventh means for estimating the actual machine temperature using the measurement results obtained by the means and the operating history of the prime mover, and a seventh means for correcting fatigue life, creep life, and life consumption through correction of temperature distribution. and an eighth means for feeding back the actual machine temperature obtained by the first means.

[Embodiments of the invention]

FIG. 1 is a block diagram showing an embodiment of a remaining life diagnosing device for a prime mover according to the present invention. This embodiment shows a case in which the present invention is applied to a device for diagnosing the remaining life of a turbine rotor.

For convenience of explanation, FIG. 1 shows the same turbine unit; a turbine unit 6 in operation with a casing cover attached; and a turbine unit 1 in an open state with the casing cover removed during a periodic inspection. Shown separately. The turbine unit 6 in operation is equipped with a tachometer, a pressure gauge, a temperature measuring device, a dynamometer, etc. in the casing, etc. in order to obtain operation history data indicating start, stop, and usage conditions during steady operation. installed on stationary parts. The figure shows the inner surface of the casing 7 as a means of obtaining data during operation.
The temperature of the vehicle is measured by the temperature measuring device 8 and taken into the operating state recording device 9. At this time, the steady operation time is measured with the time when the turbine rotational speed, fluid pressure, and load reached the rated values obtained as the measurement results of the tachometer, pressure gauge, or dynamometer attached to the turbine unit as the point at which steady operation starts. . Further, when the next startup is performed after the turbine is stopped, it is counted as one startup/stop. The temperature data, steady operation time, number of starts and stops, rotational speed, and pressure thus obtained are stored in the operating state recording device 9 as operating history data.

On the other hand, finite element division data and an analysis program necessary for calculating temperature, stress, damage, and life consumption are stored in the storage device 5 in advance. The temperature of the inner surface of the casing measured by the temperature measuring device 8 is sent to the operating state recorder 9 and the condition setting device 10, and the stress limit conditions for calculation by the finite element method are sent to the arithmetic processing device through the condition setting device 10. introduced in 11. The arithmetic processing unit 11 calculates the distribution of temperature, stress, damage, and life consumption of each part of the turbine rotor according to the analysis program called from the storage device 5, and the results of these calculations are displayed as a distribution figure on the display device 12. Ru. At the same time, areas on the rotor surface that have suffered little fatigue damage and only creep damage are selected, but the selected area will be displayed to determine whether or not cracks will occur by the time of the next periodic inspection. The timing of turbine shutdown and open inspection is determined.

During an open inspection of the turbine unit, hardness is measured using the hardness measuring device 3 at the creep-damaged site of the rotor 2 in order to measure changes in the metal structure corresponding to the operating history of the rotor 2 of the turbine unit 1 in the open state. be exposed. The hardness data 4 of the relevant part obtained by this measurement is combined with stress and operating time data in the storage device 5, and converted into temperature conditions by the temperature estimation device 13. This temperature condition is inputted into the condition setting device 10 again. The arithmetic processing unit 11 uses the temperature conditions from the temperature estimation device 13 that are input via the condition setting device 10 and the data set from the operating state recording device 9 to perform life analysis with higher accuracy. Become.

FIG. 2 is a flowchart showing the life analysis processing procedure executed by the arithmetic processing unit 11 in the steam turbine remaining life diagnosis system having the configuration shown in FIG. 1. Explain the operation of the device.

It is now assumed that the operating history of the turbine unit plant 6 which is currently in operation and an estimated value of the temperature inside the turbine during operation are given. At this time, the arithmetic processing unit 11 uses these values as boundary conditions to perform a finite element analysis of the target member using an analysis unit 14 that performs analysis regarding temperature, stress, damage, and life.

In the analysis unit 14, first, for the unsteady state, the temperature distribution analysis unit 15 obtains a temperature distribution solution at the time when the maximum thermal stress is generated in the member. This method is a commonly used method that uses simple cylindrical simulation calculations. This temperature solution is an estimated solution based on estimated temperature conditions.

Next, the unsteady stress analysis section 16 determines the distribution of thermal stress and unsteady centrifugal stress. Since such analysis programs are well-known and generalized, they can be used. Since unsteady thermal stress depends on temperature, this solution is also an estimated solution.

Next, the fatigue damage analysis unit 17 calculates the fatigue damage distribution of the target member from the unsteady stress and the driving history data. The fatigue damage rate φ _f is expressed as the linear sum of the number of repetitions N _i of the activation pattern i that induces the unsteady stress σ _i and the ratio of the fatigue life N _fi (σ _i ) of the material to the unsteady stress σ _i , as expressed by the following equation. calculated.

φ _f = 〓 ⁱ {N _i /N _fi (σ _i )} ...(1) On the other hand, regarding the steady state, the steady stress analysis section 1
8 to obtain the steady centrifugal stress distribution or internal pressure stress distribution, and calculate the casing of this stress distribution and the temperature distribution data 1 obtained by the temperature distribution analysis section 15.
The creep damage distribution is determined in the creep damage analysis section 20 using the software 9. At this time, since the steady stress calculation value is relatively independent of temperature conditions, highly accurate creep damage distribution calculation results can be obtained. The creep damage rate φ _c is the creep rupture life
t _r and the related time is t _pp , it is expressed as φ _c = t _pp / t _r (2), and it is assumed that the operating state of steady stress σ _ci continues for t _i time, and the stress The creep life at σ _ci and temperature T _i is t _r (σ _ci ,
T _i ), it can be calculated as φ _c = 〓 ⁱ {t _i /t _r (σ _ci , T _i )}...(3). From the fatigue damage rate φ _f and the creep damage rate φ _c obtained as described above, the life consumption determination unit 21 calculates the life consumption using the limit damage characteristic curve 22 shown in FIG. In addition, Fig. 3 shows that when the marginal damage rate is (φ _fp , φ _cp ) assuming that the same operating pattern will continue in the future, the current life consumption is (φ _c /φ _cp )·(φ _f /φ _fp ). It is also clear that the remaining life will vary depending on the predicted future operating pattern.

On the other hand, fatigue damage distribution data 23 obtained by the fatigue damage analysis section 17, creep damage analysis section 20
Creep damage distribution data 24 obtained by
The life consumption data 25 obtained by the life consumption determination section 21 is used by the determination section 26 to select the open inspection timing of the turbine unit 6 and to determine the hardness measurement position. The open inspection timing is selected based on lifetime consumption data and predicted data of future operating patterns so as not to reach the crack initiation lifetime.

Further, the hardness measurement position is determined by the following procedure.

The determination unit 26 compares the fatigue damage distribution obtained by the fatigue damage analysis unit 17 and the creep damage distribution obtained by the creep damage analysis unit 20, and determines the hardness of the part where the creep damage is large and the fatigue damage is small. It is determined as the measurement position. The hardness of the material at the hardness measurement position determined in this manner is measured with the prime mover stopped during the open inspection period.

FIG. 4 shows a fatigue damage distribution diagram in a cross section of the turbine rotor 2. It can be seen that the fatigue damage concentration area 27 is mostly located at the bottom of the heat groove 28 and is hardly seen in other areas.

On the other hand, FIG. 5 shows a creep damage distribution map. From Figure 5, creep damage concentration area 29
It can be seen that this is seen on the rotor center hole surface 30 and the wheel root portion 31.

In this example, when exposed to high temperature and high stress for a long time and subjected to stress changes due to starting and stopping, the metallographic structure of the constituent materials changes, and this appears as, for example, a change in the hardness of the material. Based on the experimental result that the hardness of the material corresponds well to creep damage, we will focus on the location where creep damage is concentrated, for example in the wheel root portion 31. Since there is almost no fatigue damage in this area and only creep damage is concentrated, the location where the hardness should be measured using the hardness measuring device 3 can be known from the creep damage distribution diagram shown in FIG. The above procedure is interactively processed by the display section 32 using the display device 12.

The creep damage concentration area 29 (for example, the wheel root portion 31) and the fatigue damage concentration area 27 (heat group bottom 28) are located close to each other, but are slightly shifted from each other. Since the hardness of the material is measured at the creep damage concentration area 29, it corresponds to creep damage. The operating temperature is corrected from the hardness measurement results at the creep damage concentration area 29, and based on this, the temperature used for unsteady fatigue damage calculation is corrected. Temperature correction cannot be performed from the hardness measurement results at the fatigue damage concentration region 27.

The continuous usable period data of the turbine rotor 2 obtained by the determination unit 26 is passed to the command unit 33. The command unit 33 determines when and how to stop the turbine unit next time. In the next open inspection, the hardness is measured with the hardness measuring device 3 for the pre-designated area, and the data is stored in the storage section 34 using the storage device 5.
Store it in. This hardness data is used by the actual machine temperature estimation section 3.
5 (corresponding to the temperature estimation device 13 in FIG. 1) is converted into temperature data. This actual machine temperature estimation section 35
For data conversion, that is, estimation of actual machine temperature, the relationship between hardness H _v and creep damage rate φ _c shown in Fig. 6,
And the creep rupture characteristics, ie, the relationship between stress σ and temperature/time parameter P, shown in FIG. 7 are used.

The amount of decrease in hardness _Hv increases as the applied stress increases, and is expressed by a curve as shown in FIG. 6 using stresses σ ₁ , σ ₂ , σ ₃ , and σ ₄ as parameters. The actual machine temperature estimator 35 incorporates the relationship between hardness H _v and creep damage rate φ _c shown in FIG. 6 in the form of a table using stresses σ ₁ , σ ₂ , σ ₃ , and σ ₄ as parameters; for example, Assuming that a measurement result of hardness H _vl is obtained at stress σ ₁ , the corresponding creep damage rate φ _c is obtained as φ _c =φ _cl .

Furthermore, the actual machine temperature estimating unit 35 also incorporates a table showing the relationship between the stress σ and the temperature/time parameter P shown in FIG. 7 as material data, and the value of the temperature/time parameter P corresponding to the stress σ ₁ is ,
It is obtained as P=P ₁ . Here, the parameter P
is expressed as t _r =t _pp /φ _c P=T(C+log t _r ) (4) where t _r is the creep rupture life, T is the absolute temperature, and C is the constant. Therefore, since T=P/(C+log t _r )...(5), using the creep rupture life t _r (=t _pp /φ _c ) derived based on equation (2),
Substituting the creep damage rate φ _c =φ _cl obtained in FIG. 6 and the parameter P=P ₁ obtained in FIG. 7,
Furthermore, the creep rupture life t _r = t _rl and the temperature T
is calculated as T=P ₁ /(C+log t _pp /φ _cl ) (6). The temperature T obtained in this way is outputted as the estimated temperature of the relevant part by the actual machine temperature estimating section 35.

Here, the operation time t _pp is the operation data setting section 36
Set by.

The temperature data obtained in the above manner is used in the analysis section 1 in order to obtain more accurate life estimation results.
Feedback is given to 4. Driving commands obtained from measurement results during driving are basically based on estimation and include errors. On the other hand, by adding correction based on the hardness measurement while the operation is stopped, the commands during the subsequent operation will be accurate and corrected to eliminate errors. The above feedback is performed for the above correction. As a result, based on the data obtained by the analysis section 14, the determination section 26 and the command section 33 issue driving instructions until the next inspection. At this time, since the fatigue damage distribution and creep damage distribution of all parts are given by the analysis, if any part has already reached the crack initiation life, the command unit 33 issues a warning instruction. As a result, defects and cracks can be inspected with particular attention to the designated dangerous parts, and by making appropriate repairs, the safety of the equipment can be guaranteed.

The present invention is not limited to the above-mentioned embodiments, but can be effectively used in cases where creep damage is significant in rotating parts and stationary equipment of other high-temperature, high-pressure steam motors. Regarding the actual measurement method, when focusing on creep damage, other methods that capture microscopic changes in the metal structure, such as the replica method, can also be used.

〔Effect of the invention〕

As described above, according to the present invention, when analyzing the life of actual machine parts, the life estimated based on the temperature of the stationary part of the actual machine during operation is calculated based on the life expectancy of the material at the time of periodic opening when the machine is stopped. Changes in the structure, that is, changes in the metallographic structure of a material that occur due to long-term exposure to high temperatures and high stress, are measured based on the surface hardness of the material measured by non-destructive measurement, and based on the measurement results. By correcting the above-mentioned temperature for life estimation based on the temperature conditions of the actual equipment estimated by can be performed more accurately. Moreover, the remaining life diagnosing device of the present invention can also diagnose the remaining life of rotating parts with high accuracy.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an apparatus for diagnosing the remaining life of a prime mover according to an embodiment of the present invention, Fig. 2 is a functional flow diagram showing internal processing procedures in the apparatus of Fig. 1, and Fig. 3 is a creep limit of the turbine rotor material. Characteristic diagram showing the relationship between damage and fatigue limit damage, Figure 4 is a fatigue damage distribution diagram of a turbine rotor cross section, Figure 5 is a creep damage distribution diagram of a turbine rotor cross section, and Figure 6 is a diagram showing the relationship between hardness and creep damage. Characteristic diagram shown,
FIG. 7 is a diagram showing creep rupture characteristics. 1...Turbine unit in operation stop open state, 2
... Turbine rotor, 3... Hardness measuring device, 5... Storage device, 8... Temperature measuring device, 9... Operating state recording device,
10... Condition setter, 11... Arithmetic processing unit, 12...
Display device, 13...Temperature estimation device, 14...
Analysis section, 15... Temperature distribution analysis section, 16... Unsteady stress analysis section, 17... Fatigue damage analysis section, 18... Steady stress analysis section, 20... Creep damage analysis section, 21... Life consumption judgment section, 26... Judgment section , 32...Display device, 33...Command section, 34...Storage section, 35...Actual machine temperature estimation section, 36...Operation data setting section.

Claims (1)

[Claims] 1. Temperature distribution and temperature distribution of the prime mover material based on operating condition data including the temperature and pressure, rotation speed, and load of the component to be diagnosed in the operating prime mover or a portion close to it measured at a stationary portion. a first means for determining the stress distribution by numerical analysis; a second means for determining the fatigue damage distribution from the ratio of the number of times the prime mover is started and the fatigue life of the material determined from the temperature distribution; and an operating time of the prime mover. a third means for determining a creep damage distribution from a ratio to the creep life of the material determined from the temperature distribution and stress distribution; and a fourth means for determining the life consumption of the prime mover based on the fatigue damage distribution and the creep damage distribution. and a fifth means for comparing the fatigue damage distribution and the creep damage distribution to determine a portion where the creep damage is large and the fatigue damage is small; and the metal of the portion where the creep damage is large determined by the fifth means. a sixth means for directly measuring the state of change that the tissue has undergone due to creep damage when the prime mover is stopped; and a sixth means using the measurement results obtained by the sixth means and the operating history of the prime mover. seventh means for estimating the actual machine temperature; and a seventh means for estimating the actual machine temperature obtained by the seventh means to correct the fatigue life, creep life, and life consumption through correction of the temperature distribution. and eighth means for providing feedback to the means. 2. The remaining life diagnostic device according to claim 1, wherein the sixth means comprises a hardness measuring device. 3. The remaining life diagnostic device according to claim 1, wherein the sixth means measures by a replica method.