JP2019148440A - Maintenance management menu determination method and plant maintenance management method - Google Patents

Abstract

To prolong the life of a maintenance target element in a plant for a predetermined period.SOLUTION: A maintenance management menu determination method according to at least one embodiment of the present invention is a plant maintenance management menu determination method including the steps of: predicting the remaining life of a maintenance target element on the basis of a flaw detection inspection result of the maintenance target element in contact with a fluid in the plant; re-predicting the remaining life when input factor values used for the remaining life evaluation of the maintenance target element are changed by a life extension measure of the maintenance target element if the predicted remaining life is shorter than an allowable period; and planning a maintenance management menu for the plant including the life extension measure when it is confirmed that the re-predicted remaining life is longer than the allowable period.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a maintenance management menu determination method and a plant maintenance management method.

  For example, in a boiler pipe that is used for a long time in a high-temperature and high-pressure environment, creep damage may occur in a welded part such as a pipe. Since creep damage progresses, it is necessary to evaluate the remaining life according to the degree of progress of creep damage and repair the welded part in a timely manner. Accordingly, the remaining life is evaluated by measuring the degree of progress of creep damage in the welded portion (see Patent Document 1).

Japanese Patent No. 5086615

In the remaining life evaluation method disclosed in Patent Document 1, if it is determined that the estimated remaining life is equal to or shorter than a predetermined time, that is, a time corresponding to a period until the next inspection, for example, an inspection object is required until the next inspection. Some measures are taken because there is a high possibility of breakage.
However, for example, when replacing an inspection object, if a replacement is not immediately available, the plant must be started and then the plant must be shut down again to replace the inspection object before the next inspection. . For this reason, there are costs associated with the stoppage of the plant after it has been once operated and the restarting operation after the replacement of the inspection object, and the lost profit when the plant is stopped after being once operated. In this way, it may be required to extend the remaining life of the inspection target for a predetermined period (for example, an allowable period).

  In view of the above circumstances, at least one embodiment of the present invention aims to prolong the life of a maintenance target part of a plant for a predetermined period.

(1) A maintenance management menu determination method according to at least one embodiment of the present invention includes:
A method for determining a maintenance menu for a plant,
Predicting the remaining life of the maintenance target part based on the inspection result of the maintenance target part in contact with the fluid in the plant;
If the predicted remaining life is shorter than the allowable period, re-predicting the remaining life when the input factor value used for the remaining life evaluation of the maintenance target portion is changed by the life extension measure of the maintenance target portion;
When it is confirmed that the re-predicted remaining life is longer than the allowable period, planning a maintenance management menu for the plant including the life extension measure; and
It is characterized by providing.

  According to the above method (1), after confirming that the remaining life after adopting the life extension measure is longer than the allowable period, the maintenance management menu including the life extension measure is formulated. The remaining life can be made longer than the allowable period.

(2) In some embodiments, in the method of (1), the life extension measure is an operation condition relaxation measure that reduces a load on the maintenance target site by changing an operation condition of the plant, or It includes at least one of local measures to be implemented for the maintenance target part.

  According to the above method (2), by performing the operation condition relaxation measure, it is possible to reduce the load on the maintenance target parts at a plurality of locations within the range affected by the change of the operation condition of the plant. In addition, by performing local countermeasures to be performed on the maintenance target part, it is possible to limit a range that is affected by the implementation of the countermeasures.

(3) In some embodiments, in the method of (2), the step of re-predicting the remaining life includes the input factor value changed by the operating condition mitigation measure or the local measure. And re-predicting the remaining life based on the determined input factor value.

  According to the method of (3) above, the input factor value that is changed by the operating condition mitigation measure or the local measure is obtained. Therefore, the obtained input factor value becomes valid, and the obtained input factor value is obtained. The accuracy of the remaining life re-predicted based on the value is improved.

(4) In some embodiments, in the method of (2) or (3), the life extension measure is a measure that combines the operating condition relaxation measure and the local measure.

  According to the method of (4) above, by combining the operating condition mitigation measure and the local measure, the amount of change in the operating condition of the plant can be suppressed, and the influence on the operation of the plant can be suppressed. Simple measures can be simplified.

(5) In some embodiments, in the method of the above (4), the life extension measure is a lost profit and a loss advantage as compared with a case where each of the operating condition mitigation measure and the local measure are implemented alone. This is a combination of the operating condition mitigation measure selected so as to reduce the sum of the increased costs and the local measure.

  For example, in the operating condition alleviation measure, since the operating condition of the plant is changed, the operating efficiency of the plant may be reduced and a lost profit may occur. In general, the greater the change in plant operating conditions, the lower the plant operating efficiency and the greater the lost profit. Further, in the local countermeasure, generally, the cost required for the countermeasure tends to increase as the effect of the countermeasure increases. Thus, for example, a combination of an operation condition mitigation measure and a local countermeasure causes a lost profit due to a change in the operation condition of the plant, but an increase in cost due to the implementation of the local countermeasure can be suppressed. In other words, by combining the operating condition mitigation measure and the local countermeasure, the cost due to the implementation of the local countermeasure is generated, but the lost profit due to the change of the operating condition of the plant can be reduced. Therefore, according to the method of (5) above, the sum of lost profit and increased cost can be suppressed by appropriately selecting and combining the driving condition mitigation measure and the local measure.

(6) In some embodiments, in any one of the above methods (2) to (5), the operation condition alleviation measure is a measure for reducing the temperature of the fluid in contact with the maintenance target site, or Including at least one of pressure reduction measures.

  According to the method (6), the load applied to the maintenance target part can be reduced, so that the remaining life of the maintenance target part can be extended.

(7) In some embodiments, in any one of the above methods (2) to (6), the local countermeasure includes local cooling for locally cooling the maintenance target site, and the maintenance target site. It includes at least one of a stress relaxation measure for relaxing stress and a damage recovery measure for recovering damage at the maintenance target site.

  According to the method (7), the remaining life of the maintenance target site can be extended by at least one of local cooling, stress relaxation measures, and damage recovery measures.

(8) In some embodiments, in the method according to any one of (2) to (7), the local countermeasure is the maintenance target part as a stress relaxation measure for reducing stress in the maintenance target part. Or at least one of changes in restraint conditions in the maintenance target part.

  According to the method (8), the remaining life of the maintenance target part can be extended by relieving the stress in the maintenance target part by at least one of reinforcing the maintenance target part or changing the constraint condition in the maintenance target part.

(9) In some embodiments, in any one of the above methods (2) to (8), the local countermeasure is a damage recovery measure for recovering damage in the maintenance target site. Includes at least repair welding.

  According to the above method (9), the remaining life of the maintenance target part can be extended by recovering the damage in the maintenance target part by a damage recovery measure including at least repair welding of the maintenance target part.

(10) In some embodiments, in the method of any one of the above (1) to (9), the step of planning the maintenance management menu includes a plurality of life extension measures that can extend the remaining life to the allowable period. In some cases, the effect of applying at least one of the plurality of life extension measures is converted into a monetary amount, and the maintenance management menu is determined in consideration of the monetary conversion result.

  According to the method (10), the remaining life of the maintenance target part can be made longer than the allowable period while suppressing economic loss due to the implementation of the life extension measure.

(11) In some embodiments, in the method of any one of (1) to (10) above, in the step of re-predicting the remaining life, the allowable period is reviewed or the input factor value is reviewed. After performing at least one, the remaining life is re-predicted.

  According to the above method (11), it is required to extend the life expectancy by, for example, a life extension measure by re-estimating the remaining life after reviewing the allowable period or at least one of the input factor values. If the required period can be shortened, it becomes possible to suppress the change range of the operating condition of the plant by the operating condition relaxation measure and to simplify the local countermeasure to be implemented for the maintenance target part.

(12) In some embodiments, in any of the above methods (1) to (11),
The plant is a power plant,
The fluid is steam.

  According to the above method (12), as described in (1) above, after confirming that the remaining life after adopting the life extension measure is longer than the allowable period, maintenance management including the life extension measure is performed. Since the menu is planned, the remaining life of the maintenance target part in contact with the steam in the power plant can be made longer than the allowable period.

(13) A plant maintenance management method according to at least one embodiment of the present invention includes:
Determining the maintenance management menu of the plant by the maintenance management menu determination method of any one of (1) to (12) above;
Performing maintenance management of the maintenance target part according to the maintenance management menu;
After the maintenance management, monitoring the maintenance target part;
Is provided.

  According to the above method (13), the remaining life of the maintenance target part can be made longer than the allowable period by implementing the life extension measure, and the state of the maintenance target part during the operation of the plant thereafter is grasped. it can.

(14) In some embodiments, in the method of (13), in the step of monitoring the maintenance target part, an item that affects the input factor value used when re-predicting the remaining life is selected. Monitoring and re-predicting whether the remaining life deviates from the allowable range of the item to be satisfied in order to become longer than the allowable period.

  According to the above method (14), since it can be determined whether or not the remaining life of the maintenance target part can be shorter than the permissible period, a life extension measure is added as necessary, etc. Further measures can be taken to make it longer than the permissible period.

(15) In some embodiments, in the method of (14) above,
When it is determined in the step of monitoring the maintenance target part that the value of the item is out of the allowable range, a new remaining life when the input factor value is changed by a new life extension measure of the maintenance target part Predicting
When it is confirmed that the new remaining life is longer than an allowable period, planning a maintenance management menu for the plant including the new life extension measure; and
Is further provided.
According to the above method (15), after confirming that the new remaining life after the adoption of the new life extension measure becomes longer than the allowable period, the maintenance management menu including the new life extension measure is formulated. Therefore, the remaining life of the maintenance target part can be made longer than the allowable period.

  According to at least one embodiment of the present invention, it is possible to extend the life of a maintenance target part of a plant for a predetermined period.

It is a figure which shows each process in the maintenance management method of the plant using the maintenance management menu determination method which concerns on some embodiment. It is the graph which took the temperature of the maintenance object part on the horizontal axis, and took the stress of the maintenance object part on the vertical axis. It is a table | surface for demonstrating the combination pattern and fall temperature amount of a lifetime extension measure.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions representing shapes such as quadrangular shapes and cylindrical shapes represent not only geometrically strict shapes such as quadrangular shapes and cylindrical shapes, but also irregularities and chamfers as long as the same effects can be obtained. A shape including a part or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

First, an overview of a maintenance management menu determination method and a plant maintenance management method according to some embodiments will be described with reference to FIG.
Drawing 1 is a figure showing each process in a maintenance management method of a plant using a maintenance management menu decision method concerning some embodiments. The plant maintenance management method according to some embodiments includes a step S1 for selecting a maintenance target part, a step S2 for inspecting the maintenance target part, a step S3 for determining a maintenance management menu, and a maintenance of the maintenance target part. It includes step S7 for performing management and step S8 for performing monitoring of the maintenance target part.
The maintenance management menu determination method according to some embodiments includes step S3 of determining a maintenance management menu.
A maintenance management menu determination method and a plant maintenance management method according to some embodiments are a maintenance management menu determination method applied to maintenance management of a metal member used for a long time in an environment where a high load is applied at a high temperature. And a maintenance management method for a plant, for example, applied to maintenance management of a welded portion such as a steam pipe connecting a boiler and a steam turbine in a thermal power generation facility.
A welded portion such as a steam pipe includes a heat affected zone caused by welding. The following creep damage occurs in the heat affected zone. That is, creep voids are generated in the heat affected zone due to use at a high temperature for a long period of time. The number of creep voids increases with long-term use, and adjacent creep voids are connected to form a crack. The crack gradually grows and eventually penetrates the welded portion in the thickness direction, causing internal fluid leakage. For this reason, in operation of a boiler etc., it is necessary to maintain maintenance of welding parts, such as steam piping, appropriately.

Hereinafter, the outline of each process in the maintenance management method of the plant concerning some embodiments is explained.
In addition, each process in the plant maintenance management method according to some embodiments is not necessarily performed sequentially in the order shown in FIG. 1, and there may be a process that is not performed, as will be described later. There may be steps that are performed in an order different from the order in which they are performed, or there may be steps that are performed repeatedly.

(Step S1 for selecting a maintenance target part)
Step S1 for selecting a maintenance target site is a step of selecting a maintenance target site for maintenance management from a plurality of welds such as steam pipes existing in the plant.

(Step S2 for inspecting the maintenance target part)
Step S2 for inspecting the maintenance target part is a step for performing a flaw detection inspection on the maintenance target part selected in step S1 for selecting the maintenance target part. For the flaw detection inspection performed in step S2 for inspecting the maintenance target part, for example, a phased array method, a UT method, an aperture synthesis method, a high-frequency UT method, or an ultrasonic noise method can be used. Here, the high-frequency UT method indicates a flaw detection inspection using ultrasonic waves having a frequency of 20 MHz or higher.
Step S2 for inspecting the maintenance target part is performed when the plant is stopped, for example, periodic inspection of the plant. In the following description, it is assumed that the step S2 for inspecting the maintenance target part is performed during the periodic inspection of the plant, and the periodic inspection at the time of the execution of the step S2 for inspecting the maintenance target part is as follows. This is called periodic inspection. The periodic inspection scheduled after the current periodic inspection is referred to as the next periodic inspection, and the periodic inspection performed after the next periodic inspection is referred to as the subsequent periodic inspection.

(Step S3 for determining a maintenance management menu)
The step S3 for determining the maintenance management menu includes a step S4 for predicting the remaining life of the maintenance target part, which will be described below, a step S5 for re-predicting the remaining life, and a step S6 for planning the maintenance management menu. Yes.

(Step S4 for predicting the remaining life of the maintenance target part)
Step S4 for predicting the remaining life of the maintenance target part is a step of predicting the remaining life of the maintenance target part based on the inspection result of the maintenance target part performed in step S2 for inspecting the maintenance target part.
The remaining life is the time from the current time until the maintenance target part breaks due to creep damage.
For the prediction of the remaining life, for example, crack propagation calculation, FEM, damage mechanics evaluation, void simulation method or structure simulation method can be used.

(Step S5 for re-predicting the remaining life)
Step S5 for re-predicting the remaining life is a step performed when the remaining life predicted in step S4 for predicting the remaining life of the maintenance target part is shorter than the allowable period or when there is little margin for the allowable period. Here, the allowable period is a period up to a time when the remaining life of the maintenance target part is expected to exceed, for example, a period until the next periodic inspection.
In step S5 for re-predicting the remaining life, the input factor value used for the remaining life evaluation (predicting the remaining life) of the maintenance target part is reviewed and the remaining life is predicted again. In step S5 for re-predicting the remaining life, the allowable period may be reviewed.

  In reviewing the input factor value, it may be possible to review the input factor value by reviewing the margin on the safe side that the input factor value had.

As an example of reviewing the input factor value by reviewing the margin on the safe side that was given to the input factor value, for example, the input factor used when first predicting the remaining life is the equipment related to the maintenance target part In the case of the design value, it is conceivable to use the actual measurement value as the input factor value after review.
That is, generally, the design value is often given a margin and is often set to a value that is harsher than the actual value. For example, it is considered that the design values of stress and temperature acting on the maintenance target part are often larger than the stress and temperature actually acting on the maintenance target part.
Therefore, it is expected that the remaining life re-predicted will be longer than the allowable period by using the actual measurement value as the input factor value after review.
Note that an estimated value may be used instead of using the actually measured value as the input factor value after review. For example, when it is difficult to measure an actual measurement value, an estimated value in the maintenance target part can be calculated from plant operating conditions, an actual measurement value in the vicinity of the maintenance target part, or the like. For example, if the maintenance target part is a welded portion in the steam pipe, the temperature and stress values in the maintenance target part can be estimated by obtaining the temperature and pressure of the steam flowing in the steam pipe from the operation data of the plant.

  Further, in reviewing the input factor value, it is conceivable to change the input factor value by a life extension measure for the maintenance target part described later. That is, the input factor value is changed on the assumption that a measure for changing the input factor value (life extension measure) is implemented so that the remaining life is extended. In step S6 for planning a maintenance management menu to be described later, step S5 for re-predicting the remaining life is performed in the process of considering the life extension measure for the maintenance target part, and the input factor value after the change by the life extension measure is performed. The remaining life may be re-predicted.

As an example of reviewing the permissible period, for example, if the permissible period before the review is, for example, a period up to the next periodic inspection among regular inspections conducted every two years, that is, four years, the permissible period after the review Is considered to be two years, the period until the next periodic inspection. Moreover, depending on the case, it is good also considering the period to the time different from the time which performs a periodic inspection like the temporary plant stop as the allowable period after review.
In step S5 for re-predicting the remaining life, either the review of the input factor value or the review of the allowable period may be performed, or both may be performed.

  That is, in some embodiments, in step S5 for re-estimating the remaining life, the remaining life is re-predicted after at least one of reviewing the allowable period and / or reviewing the input factor value. By re-predicting the remaining life after reviewing the allowable period or at least one of the input factor values, for example, if the period required to be extended by the life extension measure can be shortened, the operating condition relaxation measure Therefore, it is possible to suppress the change range of the operation condition of the plant by simplification and to simplify the local countermeasures to be implemented for the maintenance target part.

(Step S6 for planning a maintenance management menu)
Step S6 for planning a maintenance management menu is a step for planning a maintenance management menu for a plant including a life extension measure. For example, in step S6 for planning a maintenance management menu, when the remaining life re-predicted in step S5 for re-predicting the remaining life is shorter than the allowable period, a life extension measure is created. Specifically, a life extension measure is drafted as follows.

FIG. 2 is a graph in which the horizontal axis represents the temperature of the maintenance target site and the vertical axis represents the stress of the maintenance target site.
In the graph of FIG. 2, the solid line plot P0 is a plot showing the temperature and stress acting on the maintenance target site during operation of the plant, and is the one before reviewing the input factor value in step S5 for re-predicting the remaining life. is there.
In the graph of FIG. 2, the broken line plot P1 is a plot showing the temperature and stress acting on the maintenance target site during operation of the plant, and is after the input factor value has been reviewed in step S5 for re-predicting the remaining life. It is.
In the graph of FIG. 2, the solid line is a life expectancy line L <b> 0 representing the temperature and stress conditions at which the remaining life of the maintenance target part becomes equal to the allowable period. The life expectancy line L0 is a life expectancy line before reviewing the input factor value and the allowable period in step S5 for re-predicting the remaining life.
In the graph of FIG. 2, a broken straight line L1 is a life expectancy line L1 representing a temperature and stress condition in which the remaining life of the maintenance target part becomes equal to the allowable period. The life expectancy line L1 is a life expectancy line after reviewing the input factor value and the allowable period in step S5 for re-predicting the remaining life.
A broken line L2 in the graph of FIG. 2 will be described later.

  When the plant is restarted after this periodic inspection, if the temperature and stress acting on the maintenance target part are the temperature and stress corresponding to the region on the left side of the life expectancy line L0, the remaining life of the maintenance target part Is longer than the permissible period before the review, and if the temperature and stress correspond to the region on the right side of the isolife line L0, the remaining life of the maintenance target part becomes shorter than the permissible period before the review. Similarly, when the plant is restarted after the current periodic inspection, if the temperature and stress acting on the maintenance target part are the temperature and stress corresponding to the region on the left side of the life span L1, the maintenance target part The remaining life of the maintenance target part is longer than the allowable period after review, and if the temperature and stress correspond to the region on the right side of the isolife line L1, the remaining life of the maintenance target part is shorter than the allowable period after review. .

  When the remaining life re-predicted in step S5 for re-predicting the remaining life is shorter than the allowable period, the broken line plot P1 is located in the region on the right side of the life expectancy line L1, as shown in FIG. It will be. Therefore, when the plant is restarted after the current periodic inspection, the temperature of the maintenance target part is such that the temperature and stress conditions of the maintenance target part are at least located in the region on the left side of the isolife line L1. Or by changing at least one of the stresses, it is possible to make the remaining life of the maintenance target part longer than the allowable period.

  The following measures can be cited as measures (life extension measures) for changing the input factor value, that is, the temperature or stress of the maintenance target part so that the remaining life is extended.

(1) Operation condition alleviation measure The operation condition alleviation measure is a life extension measure that reduces the load on the maintenance target part by changing the operation condition of the plant.
For example, if the maintenance target part is a welded portion in the steam pipe, the temperature of the maintenance target part can be lowered by reducing the temperature of the steam flowing through the steam pipe, as shown by a broken line plot P2, for example.
Further, for example, if the maintenance target part is a welded portion in the steam pipe, the stress of the maintenance target part can be reduced by reducing the pressure of the steam flowing through the steam pipe, for example, as indicated by a dashed line P3. .
Further, for example, if the maintenance target part is a welded portion in the steam pipe, the temperature and stress of the maintenance target part can be reduced by lowering the temperature and pressure of the steam flowing through the steam pipe, for example, as indicated by a dashed line P4. Can be lowered.

In the operating condition relaxation measure, as described above, the operating condition of the plant is changed. Therefore, it is possible to extend the remaining life by reducing the load on the maintenance target parts at a plurality of locations within the range affected by the change of the operating condition of the plant. .
In addition, since the operating condition mitigation measures include at least one of a temperature reduction measure for the fluid in contact with the maintenance target portion and a pressure reduction measure for the fluid, the load applied to the maintenance target portion can be reduced. The remaining life can be extended.
In the operating condition relaxation measure, as described above, since the operating condition of the plant is changed, it is necessary to consider that it affects the operation of the plant. For example, it is necessary to consider that there is a possibility that the operation efficiency in the plant may be reduced by reducing the temperature and pressure of the steam.

(2) Local Measures Implemented on Maintenance Target Parts Local countermeasures implemented on maintenance target parts are life extension measures implemented locally on the maintenance target parts. In the following description, the local countermeasures performed on the maintenance target part are also simply referred to as local countermeasures.
Examples of local countermeasures include stress relaxation measures that relieve stress in the maintenance target site, local cooling that locally cools the maintenance target site, and damage recovery measures that recover damage in the maintenance target site. it can.

(2-1) Stress relaxation measure The stress relaxation measure is a measure to relieve stress of the maintenance target part by performing at least one of reinforcement of the maintenance target part or change of the constraint condition in the maintenance target part. .

Reinforcement of the maintenance target part is, for example, a measure to wind a wire of a material that is heat resistant and has the same linear expansion coefficient as the pipe with a pressing force applied to the pipe in the maintenance target part of the pipe and the surrounding area. It is. By performing the reinforcement of the maintenance target part, for example, as shown by a broken line plot P3, the stress acting on the maintenance target part can be lowered.
Further, the maintenance target part may be reinforced by increasing the thickness of the maintenance target part by performing build-up welding on the maintenance target part.

  The change of the constraint condition in the maintenance target part gives a restraining force to the pipe from the support structure of the pipe including the maintenance target part, for example, so that the stress acting on the maintenance target part is reduced during operation of the plant. It is a countermeasure. For example, if the maintenance target part is a circumferential welded part that connects pipes, a pressing force in the pipe axis direction is applied to the pipe so that the circumferential welded part is compressed in the pipe axis direction of the pipe. By changing the constraint condition in the maintenance target part, for example, as shown by a broken line plot P3, the stress acting on the maintenance target part can be reduced.

  As described above, in some embodiments, the stress relaxation measure includes at least one of reinforcement of a maintenance target part or change of a constraint condition in the maintenance target part. Therefore, reinforcement of the maintenance target part or maintenance target is included. The remaining life of the maintenance target part can be extended by relieving the stress in the maintenance target part by at least one of the change of the constraint condition in the part.

(2-2) Local cooling Local cooling is a measure for lowering the temperature of the maintenance target site by locally cooling the maintenance target site.
For example, if the maintenance target part is a welded part in a steam pipe, the temperature of the maintenance target part is lowered by blowing steam or air having a temperature lower than the temperature of the steam flowing through the steam pipe around the maintenance target part. Can do. As a result, for example, as shown by a broken line plot P5, the temperature acting on the maintenance target site can be lowered. Note that when local cooling is performed, the temperature around the maintenance target part decreases and the maintenance target part shrinks, so the stress acting on the maintenance target part is greater than before the local cooling is performed. There is. Therefore, it is necessary to set the amount of temperature decrease in the maintenance target part in consideration of a change in stress acting on the maintenance target part.

(2-3) Damage recovery measure The damage recovery measure is a measure for recovering damage in the maintenance target site by performing repair welding on the maintenance target site, for example.
In addition, as a damage recovery measure, for example, by heating the maintenance target part in a state where thermal expansion of the maintenance target part is constrained, even if a creep void or crack of the maintenance target part is pressed and repaired using thermal stress, Good.
Thus, by implementing the damage recovery measure, for example, the position of the life expectancy line moves like the life expectancy line L2 indicated by the broken straight line L2.

  Thus, in some embodiments, the local countermeasure includes at least repair welding of the maintenance target site as a damage recovery measure for recovering damage in the maintenance target site. Therefore, the remaining life of the maintenance target part can be extended by recovering the damage in the maintenance target part by a damage recovery measure including at least repair welding of the maintenance target part.

  As described above, in some embodiments, the local countermeasure includes local cooling that locally cools the maintenance target site, stress relaxation measures that relieve stress in the maintenance target site, or damage in the maintenance target site. Includes at least one damage recovery measure to heal. Thereby, the remaining life of the maintenance target part can be extended by at least one of local cooling, stress relaxation measures, and damage recovery measures.

(Calculation of input factor value)
Since the input factor value is changed by each of the above operating condition relaxation measures and local measures, for example, the changed input factor value is obtained as follows.
For example, when the temperature of the steam flowing through the steam pipe is changed as the operating condition of the plant, if the pipe has a high steam flow rate and is kept warm, the temperature of the maintenance target part in the pipe is equal to the steam temperature. Can be considered.
For example, if the pipe where the maintenance target part exists is a branch pipe or the like, and the steam flow rate is lower than the main pipe through which the steam flows, or if the pipe is not kept warm, the temperature of the maintenance target part is The case where it cannot be considered that it is equal to the temperature of the steam which flows through main piping is considered. In such a case, if the temperature of the maintenance target part cannot be directly measured, it is necessary to estimate the temperature of the maintenance target part by some method. For example, if the temperature of the branch pipe or the temperature of the steam flowing through the branch pipe can be acquired downstream of the maintenance target part in the branch pipe, the maintenance target part is interpolated based on the acquired temperature and the temperature of the steam flowing through the main pipe. The temperature may be estimated.
In estimating the temperature of the maintenance target part, it is desirable to consider heat dissipation and heat absorption in the surrounding piping including the maintenance target part.

  In addition, when the pressure of the steam flowing through the steam pipe is changed as the operation condition of the plant, referring to the above pressure value as the operation condition, the shape of the pipe including the maintenance target part, the pressure loss of the steam, the support state of the pipe The stress in the maintenance target part may be estimated by taking the above into consideration.

  For example, when a local countermeasure is implemented, the temperature and stress at the maintenance target site may be estimated by estimating how much temperature reduction or stress reduction is expected by the local countermeasure.

Thus, since the input factor value is changed by each of the above operating condition relaxation measures and local measures, the step of re-predicting the remaining life in the process of planning the maintenance management menu in step S6 of planning the maintenance management menu Returning to S5, the remaining life is re-predicted based on the changed input factor value obtained as described above.
That is, step S5 of re-predicting the remaining life is a step of obtaining an input factor value that is changed by the operating condition relaxation measure or the local measure, and re-predicting the remaining life based on the obtained input factor value. including.
Thus, since the input factor value changed by the driving condition relaxation measure or the local measure is obtained, the obtained input factor value becomes appropriate, and re-prediction based on the obtained input factor value. The accuracy of the remaining lifetime is improved.

  In some embodiments, as described above, in step S6 of planning the maintenance management menu, a life extension measure candidate is listed, and the remaining life when the life extension measure candidate is implemented is re-predicted by the remaining life. The process of re-predicting in S5 and determining whether or not the re-predicted remaining life is longer than the allowable period is repeated as appropriate. In step S6 for planning a maintenance management menu, a life extension measure for which it has been confirmed that the re-predicted remaining life is longer than the permissible period is set as a life extension measure.

As described above, the maintenance management menu determination method according to some embodiments is a plant maintenance management menu determination method, which is based on a flaw detection inspection result of a maintenance target portion in contact with a fluid in the plant. Step S4 for predicting the remaining life is provided. In the maintenance management menu determination method according to some embodiments, when the predicted remaining life is shorter than the allowable period, the input factor value used for the remaining life evaluation of the maintenance target part is changed by the life extension measure of the maintenance target part. Step S5 for re-predicting the remaining lifetime of The maintenance management menu determination method according to some embodiments includes a step of planning a maintenance management menu for a plant including a life extension measure when it is confirmed that the re-predicted remaining life is longer than the allowable period. Is provided.
As a result, after confirming that the remaining life after the adoption of the life extension measure is longer than the allowable period, a maintenance management menu including the life extension measure is drawn up. Can be long.

  If the plant is a power plant and the fluid flowing in the pipe is steam, as described above, the remaining life after adopting the life extension measure is confirmed to be longer than the allowable period, and then the life extension is performed. By designing a maintenance management menu including measures, it is possible to make the remaining life of the maintenance target part in contact with the steam longer than the allowable period in the power plant.

The life extension measure to be performed may be one of the plurality of life extension measures described above, or a combination of a plurality of life extension measures.
For example, as a result of examining with reference to FIG. 2, if it is determined that the temperature at the maintenance target part needs to be lowered by T ° C. in order to extend the remaining life beyond the allowable period, The temperature at the maintenance target site may be lowered by T ° C by one of them. In addition, the temperature at the maintenance target site is lowered by t1 ° C. by one measure out of the plurality of life extension measures described above, and the temperature at the maintenance target site is lowered by t2 ° C. by another measure. You may make it a sum become more than T degreeC. The same concept applies to the reduction of stress at the maintenance target site.

When combining a plurality of life extension measures, as described above, a steam temperature reduction measure and a steam pressure reduction measure which are operating condition relaxation measures may be combined. Further, when combining a plurality of life extension measures, a plurality of measures may be combined with local measures such as a combination of stress relaxation measures and local cooling, which are local measures.
Furthermore, when combining a plurality of life extension measures, an operation condition mitigation measure and a local measure may be combined. By combining the operating condition mitigation measure and the local countermeasure, the amount of change in the operating condition of the plant can be suppressed, the influence on the operation of the plant can be suppressed, and the local countermeasure can be simplified.

In implementing life extension measures, it may be possible to generate lost profits and increase costs. Therefore, it is desirable to calculate in advance how much the lost profit and the cost increase will be due to the implementation of the life extension measure.
For example, when the operating temperature in the plant is lowered by reducing the temperature and pressure of the steam by the operating condition mitigation measure, a lost profit including the degree of decrease in the operating efficiency and the implementation period of the operating condition mitigation measure as parameters occurs.
Further, for example, in order to take a local countermeasure, a cost for implementing the countermeasure is incurred. The cost includes a cost for preparing equipment and the like necessary for implementing the countermeasure and a construction cost for implementing the countermeasure. In addition, if the plant stop period is extended to implement the countermeasure, a lost profit of the plant due to the extension of the stop period occurs.

  In step S6 for planning the maintenance management menu described above, when there are a plurality of life extension measures that can extend the remaining life to the allowable period, the influence of applying at least one of the plurality of life extension measures is taken into consideration. Then, the maintenance management menu is determined in consideration of the result of the monetary conversion. Thereby, the remaining life of a maintenance object part can be made longer than an allowable period, suppressing the economic loss by implementation of a life extension measure.

For example, a life extension measure is an operation condition mitigation measure and a local measure that are selected so that the sum of lost profits and increased costs is less than when each of the operation condition mitigation measures and local measures are implemented alone. Can be combined with various measures.
That is, for example, in the operating condition relaxation measure, since the operating condition of the plant is changed, as described above, the operating efficiency of the plant may be reduced and a lost profit may occur. In general, the greater the change in plant operating conditions, the lower the plant operating efficiency and the greater the lost profit. Further, in the local countermeasure, generally, the cost required for the countermeasure tends to increase as the effect of the countermeasure increases. Thus, for example, a combination of an operation condition mitigation measure and a local countermeasure causes a lost profit due to a change in the operation condition of the plant, but an increase in cost due to the implementation of the local countermeasure can be suppressed. In other words, by combining the operating condition mitigation measure and the local countermeasure, the cost due to the implementation of the local countermeasure is generated, but the lost profit due to the change of the operating condition of the plant can be reduced. Therefore, the sum of lost profits and increased costs can be suppressed by appropriately selecting and combining the operating condition mitigation measures and the local measures.

Combining operating condition mitigation measures with local measures is particularly effective when life extension measures are required at multiple locations.
For example, let us consider a case where three places where the remaining lifetime is shorter than the allowable period are found. Here, when it is attempted to cope with these three locations by reducing the temperature of the operating condition relaxation measure, it is determined that the temperature reduction is required to be −100 ° C. for position A, −50 ° C. for position B, and −30 ° C. for position C. Suppose that Moreover, the following means (1)-(3) shall be possible as a life extension measure.
Means (1) is means for lowering the steam temperature, which is the operating condition of the plant. In means (1), it is assumed that the amount of decrease in steam temperature is -50 ° C. In the means (1), a lost profit corresponding to the amount of decrease in the temperature of the steam is continuously generated during the implementation period of the means (1).
The means (2) is a first means for locally lowering the temperature. In the means (2), it is assumed that the temperature decrease amount is -50 ° C. The means (2) has a smaller temperature decrease than the means (3) described later, but the initial cost is small, and the maintenance cost for continuously implementing the means (2) can be ignored. Shall.
The means (3) is a second means for locally lowering the temperature. In the means (3), it is assumed that the temperature decrease amount is -100 ° C. The means (3) has a large amount of temperature decrease compared to the means (2), but the initial cost is high, and the maintenance cost for continuously implementing the means (3) can be ignored. Shall.
FIG. 3 illustrates a table summarizing the combination patterns of the life extension measures and the amount of decrease in temperature under these conditions. Pattern 1 in FIG. 3 is a case where the maximum means (1) is utilized, pattern 3 is a case where means (1) is not used, and pattern (2) is an intermediate case. Means (1) is a change in the operating conditions of the plant, and is effective for all positions A to C. Means (2) and (3) are local countermeasures and are effective only at the respective positions where countermeasures are taken.

Specifically, in the pattern 1, the temperature at the positions A to C is reduced by 50 ° C. by means (1), and the temperature at the position A is further reduced by 50 ° C. by means (2). As a result, the temperature is lowered by 100 ° C. at the position A, and the temperature is lowered by 50 ° C. at the positions B and C, respectively.
In pattern 2, the temperature at each position A to C is lowered by 30 ° C. by means (1), the temperature at position B is further lowered by 20 ° C. by means (2), and the temperature at position A is further reduced by means (3). Reduce by 70 ° C. As a result, the temperature is lowered by 100 ° C. at the position A, the temperature is lowered by 50 ° C. at the position B, and the temperature is lowered by 30 degrees at the position C.
In pattern 3, the temperature at position B is lowered by 50 ° C. by means (2), the temperature at position C is lowered by 30 ° by means (2), and the temperature at position A is lowered by 100 ° C. by means (3). As a result, the temperature is lowered by 100 ° C. at the position A, the temperature is lowered by 50 ° C. at the position B, and the temperature is lowered by 30 degrees at the position C.

  Which combination pattern is good is determined by adding the lost profit by means (1) and the increased cost by means (2) and (3) for each pattern, and comparing the addition results to determine the optimum combination pattern. be able to.

(About monitoring contents)
In addition, in order to secure the remaining life extended by the life extension measure devised as described above, the plant is monitored in step S8 for monitoring a maintenance target part, which will be described later, as necessary. In order to guarantee the remaining life extended by the life extension measure as described above, the monitoring items and monitoring methods are suitable for the life extension measures that are planned among the following monitoring items and monitoring methods. Is done.
Therefore, in step S6 for planning the maintenance management menu, monitoring items and monitoring methods suitable for the planned life extension measures are selected.
Note that the monitoring includes monitoring performed during operation of the plant and monitoring performed when the plant is stopped.

In monitoring performed during operation of the plant, monitoring items may include temperature, pressure, deformation (strain), crack progress, and the like of the maintenance target site.
Examples of the temperature monitoring method include temperature measurement using a thermocouple, radiation thermometer, infrared camera, and the like, and temperature measurement using an optical fiber. The temperature measurement using the optical fiber is a temperature measurement using the temperature dependence of the Raman scattered light intensity in the optical fiber.

For the pressure monitoring method, for example, a pressure gauge installed in the plant can be used.
Deformation (strain) monitoring methods include, for example, measurement with a strain gauge, measurement with a laser speckle strain meter, displacement meter side by image correlation method, measurement with a creep button, laser distance meter, displacement measurement with an optical fiber displacement meter, etc. Can be mentioned. Here, the creep button is a method in which a measurement point is determined in advance in order to measure the creep strain generated during operation. The button indicates the shape of the measurement point. Specifically, it is a means for providing projections on both sides with a weld line in between, measuring the distance between the projections as an initial value, and tracking changes over time of the distance.

  Examples of crack growth monitoring methods include acoustic emission detection, a potential difference method for detecting a change in electrical resistance value due to crack progress, a method for detecting a change in magnetic properties due to crack progress, and strain measurement. be able to.

In the monitoring performed while the plant is stopped, the monitoring items include temperature, deformation (strain), crack development, and the like of the maintenance target part.
As a temperature monitoring method, for example, a method of estimating a temperature history by tissue observation of a maintenance target site by a replica method, a method of estimating a temperature history from a small amount of sample obtained, a method of estimating a temperature history by observing an aging tissue And a method of estimating the temperature history from the formation state of the steam oxidation scale and the formation state of the precipitate.

  The method for monitoring deformation (distortion) is as described above.

  Examples of the method for monitoring the progress of cracks include magnetic particle inspection, penetration inspection, MT transfer inspection, eddy current inspection, and the like as long as the surface of the maintenance target site. Also, if it is inside the maintenance target part, ultrasonic inspection by conventional UT method, ultrasonic inspection by TOFD method, ultrasonic inspection by guide wave, ultrasonic inspection by phased array method, ultrasonic inspection by aperture synthesis method, high frequency Examples thereof include an ultrasonic inspection by the UT method, an ultrasonic inspection by an ultrasonic noise method, and a radiation inspection.

(Step S7 for performing maintenance management of the maintenance target part)
In step S7 for performing maintenance management of the maintenance target part, the maintenance management menu determined in step S3 for determining the maintenance management menu, that is, the maintenance management including the life extension measure, which is planned in step S6 for planning the maintenance management menu. This is a step for performing maintenance management of the maintenance target part according to the menu.

(Step S8 for monitoring the maintenance target part)
In step S8 for monitoring the maintenance target part, the maintenance target part is monitored after the maintenance management performed in step S7 for performing maintenance management of the maintenance target part.
In the monitoring performed in step S8 for monitoring the maintenance target part, the maintenance target part is monitored by the monitoring item and the monitoring method selected in step S6 for planning the maintenance management menu.

That is, in step S8 for monitoring the maintenance target part, items that affect the input factor value used when re-predicting the remaining life are monitored, and this is satisfied because the re-predicted remaining life is longer than the allowable period. Judge whether to deviate from the permissible range of monitoring items.
This makes it possible to determine whether the remaining life of the maintenance target part can be shorter than the permissible period, so that it is longer than the permissible period, such as by adding a life extension measure if necessary. Further support is possible.

As described above, the plant maintenance management method according to some embodiments includes the step S3 of determining the plant maintenance management menu, the step S7 of performing maintenance management of the maintenance target portion according to the maintenance management menu, and the post-maintenance management. In step S8, the maintenance target part is monitored.
Thereby, by implementing the life extension measure, the remaining life of the maintenance target part can be made longer than the allowable period, and the state of the maintenance target part during the operation of the plant thereafter can be grasped.

When it is determined that the value of the monitoring item is out of the allowable range, the above-described step S5 for re-predicting the remaining life and step S6 for designing the maintenance management menu are performed again, thereby providing a new life extension measure. Make a plan.
That is, in some embodiments, when it is determined in the step of monitoring the maintenance target part that the value of the monitoring item deviates from the allowable range, the input factor value is changed by a new life extension measure for the maintenance target part. The step of predicting the new remaining life of the second, that is, the step S5 of re-predicting the remaining life is provided. Also, in some embodiments, when it is confirmed that the new remaining life is longer than the allowable period, a step of planning a maintenance management menu for the plant including a new life extension measure, that is, the maintenance management menu Step S6 is prepared.
Thus, after confirming that the new remaining life after the adoption of the new life extension measure is longer than the allowable period, the maintenance management menu including the new life extension measure is formulated. The remaining life can be made longer than the allowable period.

The present invention is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.
For example, in some embodiments described above, the maintenance target portion is a welded portion in a plurality of steam pipes connecting between a boiler and a steam turbine in a thermal power generation facility, but the maintenance target welded portion is a boiler. The maintenance management menu determination method and the plant maintenance management method according to the present invention can be applied to various welded parts exposed to high temperature and high pressure and parts other than the welded parts. .

L0, L1, L2 life span

Claims (15)

A method for determining a maintenance menu for a plant,
Predicting the remaining life of the maintenance target part based on the inspection result of the maintenance target part in contact with the fluid in the plant;
If the predicted remaining life is shorter than the allowable period, re-predicting the remaining life when the input factor value used for the remaining life evaluation of the maintenance target portion is changed by the life extension measure of the maintenance target portion;
When it is confirmed that the re-predicted remaining life is longer than the allowable period, planning a maintenance management menu for the plant including the life extension measure; and
A maintenance management menu determination method characterized by comprising: The life extension measure includes at least one of an operation condition mitigation measure for reducing a load on the maintenance target site by changing an operation condition of the plant, or a local measure to be implemented for the maintenance target site. The maintenance management menu determination method according to claim 1. The step of re-predicting the remaining life obtains the input factor value changed by the operating condition relaxation measure or the local countermeasure, and re-predicts the remaining life based on the obtained input factor value. The maintenance management menu determination method according to claim 2, further comprising the step of: The maintenance management menu determination method according to claim 2 or 3, wherein the life extension measure is a measure obtained by combining the operation condition mitigation measure and the local measure. The life extension measure is the operation condition alleviation measure selected so that the sum of lost profit and increased cost is less than when the operation condition alleviation measure and the local measure are each implemented alone. The maintenance management menu determination method according to claim 4, which is a combination with the local countermeasure. The maintenance management menu according to any one of claims 2 to 5, wherein the operation condition mitigation measure includes at least one of a temperature reduction measure for a fluid that is in contact with the maintenance target part and a pressure reduction measure for the fluid. Decision method. The local countermeasure is at least one of local cooling that locally cools the maintenance target site, a stress relaxation measure that relieves stress in the maintenance target site, or a damage recovery measure that recovers damage in the maintenance target site. The maintenance management menu determination method according to any one of claims 2 to 6, including one. The local countermeasure includes at least one of reinforcement of the maintenance target part or change of a constraint condition in the maintenance target part as a stress relaxation measure for relaxing stress in the maintenance target part. The maintenance management menu determination method according to any one of the above. The maintenance management menu determination method according to any one of claims 2 to 8, wherein the local countermeasure includes at least repair welding of the maintenance target part as a damage recovery measure for recovering damage in the maintenance target part. In the step of planning the maintenance management menu, when there are a plurality of the life extension measures that can extend the remaining life to the permissible period, the effect when applying at least one of the plurality of the life extension measures is converted into a monetary amount. The maintenance management menu determination method according to any one of claims 1 to 9, wherein the maintenance management menu is determined in consideration of the converted result. The step of re-predicting the remaining life re-predicts the remaining life after performing at least one of the review of the permissible period and the review of the input factor value. The maintenance management menu determination method described in 1. The plant is a power plant,
12. The maintenance management menu determination method according to claim 1, wherein the fluid is steam. Determining the maintenance management menu of the plant by the maintenance management menu determination method according to any one of claims 1 to 12;
Performing maintenance management of the maintenance target part according to the maintenance management menu;
After the maintenance management, monitoring the maintenance target part;
A maintenance management method for a plant, comprising: In the step of monitoring the maintenance target part, an item that affects the input factor value used when re-predicting the remaining life is monitored, and the re-predicted remaining life is longer than the allowable period. The plant maintenance management method according to claim 13, wherein it is determined whether or not the allowable range of the item to be satisfied is deviated. When it is determined in the step of monitoring the maintenance target part that the value of the item is out of the allowable range, a new remaining life when the input factor value is changed by a new life extension measure of the maintenance target part Predicting
When it is confirmed that the new remaining life is longer than an allowable period, planning a maintenance management menu for the plant including the new life extension measure; and
The plant maintenance management method according to claim 14, further comprising:

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