Life extension method of member

Abstract

To prolong the life of a member included in a device to be maintained.SOLUTION: A method of extending the life of a member according to at least one embodiment of the present disclosure is a method of extending the life of a member included in a device to be maintained in a plant. The method for extending the life of the member according to at least one embodiment of the present disclosure includes the steps of: measuring a temperature of the member arranged in a plurality of preset regions in the device to be maintained; calculating the degree of thermal fatigue damage of the member in each of the plurality of regions based on the temperature measured in the step of measuring the temperature; and removing a surface of the member in the region where the degree of thermal fatigue damage calculated in the step of calculating the degree of thermal fatigue damage is equal to or greater than a first threshold value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for extending the life of a component. [Background technology]

[0002] For example, in a thermal power plant or the like, an industrial boiler, a gasification apparatus that partially combusts and gasifies a carbon-containing solid fuel such as coal, and the like are installed. For example, a furnace wall is provided in the boiler, and a water-cooled furnace wall is provided in the gasification furnace of the gasification apparatus. Hereinafter, the furnace wall or the furnace wall will be referred to as the wall portion. In order to suppress heating of the wall portion, the wall portion has a plurality of pipes through which a cooling medium passes and a plurality of fins provided between each of the pipes, and is formed by joining the pipes and the fins to each other by welding or the like (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6698933 Summary of the Invention [Problem to be solved by the invention]

[0004] The piping that constitutes the wall portion may develop damage such as cracks over the course of operation time of the boiler, gasification equipment, etc. In such a case, it is necessary to carry out repairs, for example, by cutting out a predetermined section including the crack, and attaching a repair pipe by welding to the wall portion from which the predetermined section was cut out.

[0005] In order to reduce the frequency of repairs of components included in equipment subject to maintenance, such as the piping that constitutes the walls of the boiler, gasification equipment, and the like, it is necessary to extend the life of the components.

[0006] In view of the above circumstances, at least one embodiment of the present disclosure aims to extend the life of components included in equipment that is subject to maintenance. [Means for solving the problem]

[0007] A method for extending the life of a component according to at least one embodiment of the present disclosure includes: A method for extending the life of a component included in a maintenance target device in a plant, comprising: measuring the temperature of the components arranged in each of a plurality of predetermined areas in the maintenance target device; calculating a thermal fatigue damage degree of the component for each of the plurality of regions based on the temperature measured in the temperature measurement step; removing a surface of the component from the region where the thermal fatigue damage degree calculated in the step of calculating the thermal fatigue damage degree is equal to or greater than a first threshold value; Equipped with. Effect of the Invention

[0008] According to at least one embodiment of the present disclosure, the life of components included in equipment subject to maintenance in a plant can be extended. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a schematic configuration of a boiler as an example of equipment to which a component life extension method according to some embodiments can be applied. [Diagram 2] FIG. 2 illustrates a portion of a furnace wall according to some embodiments. [Diagram 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] FIG. 2 is a diagram illustrating a furnace of a boiler according to some embodiments as a maintenance target device. [Diagram 5] FIG. 2 is a diagram showing a schematic diagram of equipment other than a boiler as equipment to be maintained. [Figure 6] 1 is a flowchart showing a procedure for measuring the temperature of a region in a component life extension method according to some embodiments. [Figure 7] 1 is a flowchart showing a processing procedure for implementing life extension treatment in a component life extension method according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such a configuration, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions excluding the presence of other elements.

[0011] (Overall boiler configuration) FIG. 1 is a diagram showing a schematic configuration of a boiler as an example of equipment to which a component life extension method according to some embodiments can be applied. As shown in FIG. 1, a boiler 10 according to some embodiments includes a furnace wall 12 in which a furnace 11 is formed, a combustion device 13, a superheater 15, a reheater 16, and a coal economizer 17.

[0012] A flue 14 is connected to the outlet of the furnace 11. A superheater 15 is provided in the upper part of the furnace 11. A reheater 16 and a coal economizer 17 are provided in the flue 14. The reheater 16 and the coal economizer 17 are provided in this order from the outlet side of the furnace 11 along the flow direction of the flue 14. In addition, a steam drum (not shown) is provided in the upper part of the furnace 11.

[0013] The furnace 11 has a cross-sectional shape in a horizontal plane that is, for example, rectangular, and extends in the vertical direction. Fig. 2 is a diagram showing a part of a furnace wall 12 according to some embodiments. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. The furnace wall 12 is equipped with a plurality of water tubes 19 extending vertically and fins 20 connecting adjacent water tubes 19. Water is supplied to each water tube 19 from a steam drum (not shown). In this manner, the water tubes 19 and the fins 20 form the furnace wall 12 on the inside of the furnace 11.

[0014] In some embodiments, the combustion device 13 is installed through the furnace wall 12 of the furnace 11 . In some embodiments of the boiler 10, the combustion devices 13 are provided near the four corners of the furnace 11, which has a rectangular cross-sectional shape, and are configured to perform swirling combustion in which the flame swirls within the furnace 11 when the furnace 11 is viewed from above. The combustion device 13 may be provided on either one surface of the furnace 11 except the ceiling surface and the furnace bottom surface, or on two opposing surfaces. The boiler 10 may be configured to perform opposed combustion instead of swirl combustion.

[0015] In some embodiments, the combustion device 13 has a plurality of compartments (not shown) arranged in a vertical direction. A burner nozzle 21, an air nozzle (not shown), and the like are arranged in each compartment. The combustion device 13 is supplied with a solid fuel such as pulverized coal as fuel.

[0016] The boiler 10 according to some embodiments includes a thermal fatigue damage degree calculation device 30. The thermal fatigue damage degree calculation device 30 is composed of, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, for example, and the CPU reads this program into the RAM or the like and executes information processing and arithmetic processing to realize various functions. The program may be installed in a ROM or other storage medium in advance, may be provided in a state stored in a computer-readable storage medium, or may be distributed via a wired or wireless communication means. The computer-readable storage medium may be a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. The thermal fatigue damage degree calculation device 30 is configured to be able to calculate the thermal fatigue damage degree as described below. The thermal fatigue damage degree calculation device 30 includes a storage unit (not shown) that stores the transition of the temperature measured by the temperature sensor 28 provided in each region R of the boiler 10 as described below.

[0017] The piping that constitutes the furnace wall 12, such as the water pipe 19, may develop damage such as cracks due to the operation time of the boiler 10, gasification equipment, etc. In such a case, it is necessary to carry out repairs such as, for example, removing a predetermined section including the cracks, and attaching a repair pipe by welding to the furnace wall 12 from which the predetermined section has been removed. Therefore, in some embodiments of the method for extending the life of a component, the following is done to reduce the frequency of repairs of components included in equipment subject to maintenance, such as piping that constitutes a furnace wall 12 in a boiler 10 or a gasification system.

[0018] As a result of careful investigations, the inventors discovered that by removing the surface of components contained in the equipment to be maintained before visible cracks appear on the components, even tiny cracks that are difficult to see with the naked eye that appear on the surface of the components can be removed, and therefore the thermal fatigue life of the components can be extended by approximately 1.5 to 2.5 times compared to when the surface of the components is not removed. In the method for extending the life of a component according to some embodiments, the temperature of the component included in the equipment to be maintained is measured, and the thermal fatigue damage level of the component is calculated based on the temperature measurement result, more specifically, the temperature history of the component. If the calculated thermal fatigue damage level is equal to or greater than a predetermined threshold, the surface of the component is removed. More specifically, the method is designed to extend the life of the component included in the equipment to be maintained as follows.

[0019] (Temperature measurement) FIG. 4 is a diagram illustrating a furnace 11 of a boiler 10 according to some embodiments as a maintenance target device. FIG. 5 is a diagram showing a schematic diagram of devices other than the boiler 10 as equipment to be maintained. Even for components included in one maintenance target device, the progress of thermal fatigue damage may differ depending on the location the component is located in. In other words, after a certain period of use has elapsed, a difference may occur between the thermal fatigue damage of components located in one area and the thermal fatigue damage of components located in another area among the components included in the maintenance target device. Such differences in the degree of thermal fatigue damage are mainly due to the temperature history that the components are subjected to during the use of the equipment under maintenance. However, it is not realistic to attach temperature sensors to all of the components that are the subject of maintenance and that are included in the equipment to be maintained.

[0020] Therefore, in some embodiments of the method for extending the life of a component, an area in which components to be maintained are located is divided into a plurality of areas, with an area in which the thermal fatigue life is similarly long and short being defined as one area R. Then, the temperature of each area is measured at at least one location in each area that can represent the temperature history of the area.

[0021] For example, if the combustion device 13 is arranged near the four corners of the furnace 11 having a rectangular cross-sectional shape, if the position along the circumferential direction centered on the axis AX1 is different, the distance from the combustion device 13 will be different, and it is thought that the temperature of the furnace wall 12 will also be different. Therefore, for example, when the above-mentioned boiler 10 is a maintenance target device in the component life extension method according to some embodiments, and the water tube 19 of the furnace wall 12 is a component to be maintained, it is advisable to set a plurality of regions R in advance for the furnace wall 12 so that their positions along the circumferential direction centered on the axis AX1 of the furnace 11 are different from each other, as shown in Fig. 4. Note that, in Fig. 4, the region R and the temperature sensor 28 described later are illustrated only for the furnace wall 12 located on the front side of the page, but it is assumed that a plurality of regions R are set and temperature sensors are provided for the other furnace walls 12 in the same manner.

[0022] Furthermore, in the boiler 10, since the combustion device 13 is provided in a relatively lower region, it is considered that the temperature of the furnace wall 12 varies depending on the vertical position, that is, the position along the axis AX1. Therefore, for example, when the above-mentioned boiler 10 is a maintenance target device in the component life extension method according to some embodiments, and the water tube 19 of the furnace wall 12 is a component to be maintained, it is advisable to pre-set a plurality of regions R on the furnace wall 12 so that their positions along the axis AX1 of the furnace 11 are different from each other, as shown in FIG. 4.

[0023] In addition, for example, in the case where the equipment to be maintained is device 25 having wall 26 having a cylindrical shape as shown in FIG. 5 and a high-temperature fluid is configured to move inside the device along axis AX2 of the cylindrical shape, it is considered that the difference in temperature of wall 26 due to differences in position along the circumferential direction centered on axis AX2 will be relatively small. Therefore, for example, when the above-mentioned device 25 is a maintenance target device in the life extension method of a component according to some embodiments, and the wall portion 26 is a component to be maintained, it is preferable to set a plurality of regions R in advance for the wall portion 26 so that the positions along the axis AX2 of the device 25 are different from each other, as shown in Fig. 5. Note that, when the wall portion 26 includes a pipe through which a fluid such as water can flow, such as the water pipe 19 of the furnace wall 12, the pipe may be a component to be maintained. An example of the device 25 shown in FIG. 5 is a gasification furnace in a gasification system that partially combusts and gasifies carbon-containing solid fuel such as coal.

[0024] Depending on the structure of the equipment to be maintained, the above-mentioned region R may be set such that the positions along the axis (e.g., axis AX1, AX2) of the walls (e.g., furnace wall 12, wall 26) defining a cylindrical internal space (e.g., internal space IS defined by furnace wall 12 and wall 26) are different from each other, or the positions along the circumferential direction around the axis are different from each other. Furthermore, the above-mentioned region R may be set such that a range in which the thermal fatigue life is similarly long or short is defined as one region R depending on the structure of the equipment to be maintained, or a plurality of regions R may be set.

[0025] At least one temperature sensor 28 is provided in each of the above-mentioned regions R, and can measure the temperature of the component to be maintained. The temperature sensor 28 is, for example, a thermocouple. The temperature sensor 28 may be provided in two or more locations in different positions in each of the above-mentioned regions R. In the case of the boiler 10 described above, a temperature sensor 28 is arranged so as to be able to measure the temperature of the water tube 19 on the furnace 11 side, for example.

[0026] 6 is a flowchart showing a procedure for measuring the temperature of region R in the component life extension method according to some embodiments. The component life extension method according to some embodiments includes step S101 of measuring the temperature and step S103 of storing the temperature.

[0027] Step S101 of measuring temperature is a step of measuring the temperature of the component to be maintained by each of the above-mentioned temperature sensors 28. In step S101 of measuring temperature, information on the temperature of the component to be maintained, measured by each of the above-mentioned temperature sensors 28, is input to the thermal fatigue damage degree calculation device 30.

[0028] The storing step S103 is a step of storing the temperature information measured in the temperature measuring step S101 in a storage unit (not shown). In the storing step S103, the thermal fatigue damage degree calculation device 30 stores the input temperature information together with the information on the time of measurement in a storage unit (not shown). As a result, the transition of the temperature measured by the temperature sensor 28 (temperature history) is stored in the storage unit (not shown).

[0029] 7 is a flow chart showing a procedure of a process for carrying out a life extension treatment in a method for extending a life of a component according to some embodiments. The method for extending a life of a component according to some embodiments includes step S1 of reading a temperature history, step S3 of calculating a thermal fatigue damage degree, step S5 of comparing the thermal fatigue damage degree with a threshold value, and step S7 of removing a surface of the component. The method for extending a life of a component according to some embodiments includes step S9 of inspecting for cracks, step S11 of determining a crack depth, step S13 of determining whether the component can withstand the next shutdown period, step S15 of removing the cracks, step S17 of performing a build-up weld repair, step S19 of determining whether a switchover repair is possible, and step S21 of performing the switchover repair.

[0030] Step S1 of reading the temperature history is a step of reading the temperature transition, i.e., the temperature history, in each region R stored in a storage unit (not shown). In step S1 of reading the temperature history, the thermal fatigue damage degree calculation device 30 reads the temperature transition, i.e., the temperature history, in each region R stored in a storage unit (not shown).

[0031] Step S3 of calculating the thermal fatigue damage degree is a step of calculating the thermal fatigue damage degree of components that are subject to maintenance in each region R, based on the temperature history in each region R. In step S3 of calculating the thermal fatigue damage degree, thermal fatigue damage degree calculation device 30 calculates the thermal fatigue damage degree of components that are subject to maintenance in each region R, based on the temperature history in each region R read in step S1 of reading the temperature history.

[0032] Step S5 of comparing the thermal fatigue damage degree with a threshold is a step of comparing the calculated thermal fatigue damage degree with a predetermined threshold. In step S5 of comparing the thermal fatigue damage degree with a threshold, the worker compares the thermal fatigue damage degree with the threshold as described below. Note that in step S5 of comparing the thermal fatigue damage degree with a threshold, the thermal fatigue damage degree calculation device 30 may compare the thermal fatigue damage degree with the threshold.

[0033] Step S7 of removing the surface of the component is a step of removing the surface of the component in region R where the thermal fatigue damage level has reached or exceeded a first threshold value Th1, which will be described later. In step S7 of removing the surface of the component, the worker removes the surface of the component in region R where the thermal fatigue damage level has reached or exceeded the first threshold value Th1, as will be described later.

[0034] Step S9 of performing crack inspection is a step of inspecting for the presence or absence of cracks for components that are the subject of maintenance in region R where the thermal fatigue damage level has reached or exceeded the second threshold value Th2, which will be described later. In step S9 of performing crack inspection, a worker inspects for the presence or absence of cracks for components that are the subject of maintenance in region R where the thermal fatigue damage level has reached or exceeded the second threshold value Th2, as will be described later.

[0035] The step S11 of determining the crack depth is a step of determining the crack depth based on the result of the inspection in the step S9 of performing the crack inspection. In the step S11 of determining the crack depth, the worker determines the crack depth based on the result of the inspection in the step S9 of performing the crack inspection.

[0036] Step S13 for determining whether a component can withstand the next shutdown is a step for determining whether a component in which a crack was found can withstand the next shutdown based on the result of the inspection in step S9 for performing the crack inspection. In step S13 for determining whether a component can withstand the next shutdown, an operator determines whether a component can withstand the next shutdown by, for example, having a computer perform a crack growth calculation for the crack found as a result of the inspection in step S9 for performing the crack inspection.

[0037] The crack removal step S15 is a step of removing cracks found as a result of the inspection in the crack inspection step S9 from the component. In the crack removal step S15, a worker removes the found cracks from the component as described below.

[0038] Step S17 of performing overlay welding repair is a step of performing overlay welding on the member after the crack removal after performing step S15 of removing the crack. In step S17 of performing overlay welding repair, a worker performs overlay welding on the member after the crack removal.

[0039] Step S19 for determining whether or not switchover repair is possible is a step for determining whether or not switchover repair is possible for a component in which a crack has been found, by cutting out an area R including the crack and installing a new component. In step S19 for determining whether or not switchover repair is possible, a worker determines whether or not switchover repair is possible as described below.

[0040] Step S21 of performing the switching repair is a step of performing the switching repair by removing the region R including the cracks, etc., and installing a new member. In step S21 of performing the switching repair, a worker performs the switching repair by removing the region R including the cracks, etc., and installing a new member.

[0041] Hereinafter, a component life extension method according to some embodiments will be described with reference to the flowchart of FIG.

[0042] (Calculation of thermal fatigue damage) In some embodiments of the component life extension method, a thermal fatigue damage degree of a component to be maintained is calculated based on a temperature measured by a temperature sensor 28. Specifically, a thermal fatigue damage degree calculation device 30 is configured to store the transition of the temperature measured by the temperature sensor 28 provided in each region R of the boiler 10 described above in a storage unit (not shown). Then, the thermal fatigue damage degree calculation device 30 performs step S1 of reading a temperature history, reads the transition of the temperature in each region R stored in the storage unit (not shown), i.e., the temperature history, and performs step S3 of calculating a thermal fatigue damage degree, thereby being able to calculate the thermal fatigue damage degree of the component to which the temperature sensor 28 is attached.

[0043] The thermal fatigue damage degree indicates the degree of thermal cycle fatigue calculated based on the temperature history of the component to be maintained and the history of the stress acting on the component. In some embodiments of the method for extending the life of a component, the thermal fatigue damage degree of the component is evaluated by setting the thermal fatigue damage degree at which the component is estimated to break as 100%. In the case of the boiler 10 described above, since the component to be maintained is the water tube 19, the thermal fatigue damage degree of the water tube 19 is evaluated by setting the thermal fatigue damage degree at which a crack is estimated to penetrate the water tube 19 in the thickness direction as 100%.

[0044] In some embodiments of the component life extension method, the thermal fatigue damage degree of a component calculated as described above is regarded as the thermal fatigue damage degree of the components in region R that includes the component. In some embodiments of the component life extension method, when multiple temperature sensors 28 are provided in one region R, the largest value among multiple thermal fatigue damage degrees calculated based on the transition of temperatures measured by the multiple temperature sensors 28 is regarded as the thermal fatigue damage degree of the components in the region R.

[0045] (Removal of surface of component) In some embodiments of the component life extension method, in step S5 of comparing the thermal fatigue damage level with a threshold value, an operator determines whether the thermal fatigue damage level calculated as described above is equal to or greater than the threshold value. In some embodiments of the component life extension method, when the thermal fatigue damage degree calculated as described above becomes equal to or greater than a threshold value (first threshold value Th1), the surfaces of all components in region R where the thermal fatigue damage degree becomes equal to or greater than the first threshold value Th1 are removed. That is, in step S5 of comparing the thermal fatigue damage degree with the threshold value, when the worker determines that the thermal fatigue damage degree calculated as described above is equal to or greater than the first threshold value Th1, step S7 of removing the surfaces of the components is performed, and the surfaces of all components in region R where the thermal fatigue damage degree becomes equal to or greater than the first threshold value Th1 are removed.

[0046] In the case of the boiler 10 described above, the surface of the water tube 19 facing the furnace 11, which is located within the region R where the thermal fatigue damage level is equal to or greater than the first threshold value Th1, i.e., the surface of the water tube 19 which is located inside the furnace 11 relative to the fins 20, is removed when the boiler 10 is shut down (e.g., during regular inspection). Specifically, workers remove part of the surface of water tube 19 by polishing with abrasive paper, blasting, grinding with a grinder, etc., thereby removing the surface of water tube 19 on the furnace 11 side by a depth of, for example, 0.1 mm to 0.3 mm. The method for removing a portion of the surface of the water pipe 19 is not limited to the above-mentioned method, as long as it is possible to remove a portion of the surface of the water pipe 19. The boundary between the removed portion and the unremoved portion of the surface of the water pipe 19 should be finished smoothly so that no clear step appears in the radial direction of the water pipe 19.

[0047] For the water pipes 19 in region R where the thermal fatigue damage level is less than the first threshold value Th1, no surface removal is performed and they are continued to be used. That is, in step S5 of comparing the thermal fatigue damage level with the threshold value, if the operator determines that the thermal fatigue damage level calculated as described above is less than the first threshold value Th1, he or she decides to continue using the water pipes 19 in region R where the thermal fatigue damage level is less than the first threshold value Th1.

[0048] Here, the first threshold value Th1 is a preset value that is, for example, 50% or less when the thermal fatigue damage degree at which the component to be maintained is estimated to break is 100%. In the component life extension method according to some embodiments, the first threshold value Th1 is, for example, 30%.

[0049] (Inspection and removal of cracks) In some embodiments of the component life extension method, when the thermal fatigue damage degree calculated as described above becomes equal to or greater than a second threshold value Th2 that is greater than the first threshold value Th1, the presence or absence of cracks on the surfaces of all components within region R where the thermal fatigue damage degree becomes equal to or greater than the second threshold value Th2 is inspected when the boiler 10 is stopped (e.g., during regular inspection). That is, when the operator determines in step S5 of comparing the thermal fatigue damage degree with the threshold value that the thermal fatigue damage degree calculated as described above is equal to or greater than the second threshold value Th2, step S9 of performing a crack inspection is performed to inspect for the presence or absence of cracks.

[0050] Here, the second threshold value Th2 is a preset value that is, for example, 90% or more when the thermal fatigue damage degree at which the component to be maintained is estimated to break is 100%. In the component life extension method according to some embodiments, the second threshold value Th2 is, for example, 100%.

[0051] Examples of inspections for the presence or absence of cracks include penetrant inspection, magnetic particle inspection, inspection using the MT transfer method, eddy current inspection, and ultrasonic inspection.

[0052] The worker determines the depth of the crack in step S11 of determining the crack depth based on the result of the inspection in step S9 of performing the crack inspection. If a crack is found whose depth is equal to or greater than the specified depth Thdp as a result of the inspection for cracks, that is, if the crack depth is determined to be equal to or greater than the specified depth Thdp in step S11 for determining the crack depth, the worker performs step S19 for determining whether or not switchover repair is possible. In step S19 for determining whether or not switchover repair is possible, the worker examines whether switchover repair is possible by removing the region R including the crack and installing a new member, that is, whether or not a new member is readily available. In the case of the boiler 10 described above, the worker examines whether or not a new water tube 19 for repairing the removal area is readily available. If switching repair is possible, i.e., if step S19 for determining whether switching repair is possible is judged to be positive, then during the shutdown of the boiler 10, an operator performs switching repair by carrying out step S21. If switchover repair is not possible, i.e., if a negative judgment is made in step S19 for judging whether switchover repair is possible, an operator performs step S15 for removing the cracks and step S17 for performing overlay welding repair during the shutdown of the boiler 10. That is, after removing the cracks with a grinder or the like in step S15 for removing the cracks, an operator performs repair by overlay welding in step S17 for performing overlay welding repair, and finishes the surface of the water tube 19 after overlay welding so that it is flush with the non-overlay portion.

[0053] If, as a result of checking for the presence or absence of cracks, the depth of the crack found is less than the specified depth Thdp, i.e., if it is determined in step S11 of determining the crack depth that the crack depth is less than the specified depth Thdp, an operator performs step S13 of determining whether the components can withstand the next shutdown period, and determines whether the water tube 19 can withstand the next regular inspection (the next shutdown period of the boiler 10) by, for example, having a computer perform a crack propagation calculation. If the crack propagation calculation shows that the water tube 19 can withstand the next regular inspection (the next time the boiler 10 is shut down), that is, if a positive judgment is made in step S13, which determines whether the component can withstand the next shutdown, the water tube 19 will continue to be used. If the crack propagation calculation shows that the water tube 19 cannot withstand the next regular inspection (the next time the boiler 10 is shut down), that is, if step S13, which determines whether the component can withstand the next shutdown, is judged negative, workers perform step S15 to remove the crack and step S17 to perform overlay welding repair.

[0054] If no cracks are found as a result of checking for the presence or absence of cracks, i.e., if it is determined in step S11 of determining the crack depth that there are no cracks, the worker performs step S7 of removing the surface of the components, and removes the surfaces of all components within area R, just as when the thermal fatigue damage level is equal to or greater than the first threshold value Th1.

[0055] (Multiple surface removals in the same area) In some embodiments of the component life extension method, the surface of a component that has had its surface removed as described above may be removed again in the same range as the previous surface removal range. When removing the surface again in the same range as the previous surface removal range, the necessity of removing the surface and the necessity of crack inspection (step S5) are judged based on the degree of thermal fatigue damage.

[0056] Therefore, when calculating the thermal fatigue damage degree for the same range as the previous surface removal range, i.e., for the region R where the surface of the component was previously removed, it is preferable that the above-mentioned first threshold value Th1 and second threshold value Th2 are set to values ​​larger than the first threshold value Th1 and second threshold value Th2 for the region R where the surface of the component was previously removed. In other words, by changing the first threshold value Th1 and the second threshold value Th2, the thermal fatigue damage degree for the component is not corrected even when the surface of the component is removed, and the thermal fatigue damage degree may be continued to be calculated even after the surface of the component is removed, and a determination may be made as to the timing of the next surface removal and the need for a crack inspection.

[0057] Furthermore, when calculating the thermal fatigue damage level for the same range as the previous surface removal range, i.e., for the region R where the surface of the component was previously removed, the thermal fatigue damage level for the component may be corrected to be smaller even if the surface of the component has been removed, and the thermal fatigue damage level after the surface removal of the component may be calculated. In this case, the first threshold value Th1 and the second threshold value Th2 described above do not need to be changed when determining the timing of the next surface removal or the need for a crack inspection.

[0058] The present disclosure is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications. For example, in the above-described embodiment, the boiler 10 has been described as an example of equipment to which the component life extension method according to some embodiments can be applied, but the equipment (apparatus 25) to which the component life extension method according to some embodiments can be applied is not limited to the boiler 10 and may be other equipment, such as a gasification device that partially combusts and gasifies carbon-containing solid fuel such as charcoal. The component whose life is to be extended by the component life extension method according to some embodiments may be any of the components (e.g., wall portion 26) used in these other equipment (apparatus 25).

[0059] The contents described in each of the above embodiments can be understood, for example, as follows. (1) A method for extending the life of a component according to at least one embodiment of the present disclosure is a method for extending the life of a component (water tube 19, wall section 26) included in a maintenance target device (boiler 10, device 25) in a plant. The method for extending the life of a component according to at least one embodiment of the present disclosure includes a step S101 of measuring the temperature of the component (water tube 19, wall section 26) arranged in each of a plurality of regions R set in advance in the maintenance target device (boiler 10, device 25), a step S3 of calculating the thermal fatigue damage degree of the component (water tube 19, wall section 26) in each of the plurality of regions R based on the temperature measured in the step S101 of measuring the temperature, and a step S7 of removing the surface of the component (water tube 19, wall section 26) in the region R where the thermal fatigue damage degree calculated in the step S3 of calculating the thermal fatigue damage degree is equal to or greater than a first threshold value Th1.

[0060] As a result of careful investigation by the inventors, it was found that by removing the surface of the above components (water pipes 19, wall portions 26) before relatively large damage such as visible cracks occurs in the above components (water pipes 19, wall portions 26), even tiny cracks that are difficult to see with the naked eye that have appeared on the surface of the above components (water pipes 19, wall portions 26) are removed, and therefore the thermal fatigue life can be extended by approximately 1.5 to 2.5 times compared to the case where the surface of the above components (water pipes 19, wall portions 26) is not removed. According to the above method (1), the life of the members (water tubes 19, wall portion 26) included in the equipment to be maintained (boiler 10, device 25) in the plant can be extended.

[0061] (2) In some embodiments, in the method of (1) above, the multiple regions R are regions set based on the length of the thermal fatigue life, and in step S101 of measuring the temperature, it is preferable to measure the temperature of some of the members (water pipes 19, wall section 26) within the multiple regions R for each of the multiple regions R. In step S3 of calculating the thermal fatigue damage degree, the thermal fatigue damage degree calculated based on the temperature measured in step S101 of measuring the temperature may be regarded as the thermal fatigue damage degree of all the members (water pipes 19, wall section 26) within the region R.

[0062] According to the method (2) above, by grouping ranges where the thermal fatigue life is similarly long as one of the multiple regions R, the thermal fatigue damage degree of each region R can be grasped by the thermal fatigue damage degree calculated based on the temperature of some of the components (water tubes 19, wall section 26) within the region R. This makes it possible to grasp the thermal fatigue damage degree of each region R without measuring the temperature of each of the components (water tubes 19, wall section 26) included in the equipment to be maintained (boiler 10, device 25), making it easy to grasp the thermal fatigue damage degree of each region R.

[0063] (3) In some embodiments, in the method of (1) or (2) above, the equipment to be maintained (boiler 10, device 25) may have a wall (furnace wall 12, wall 26) that defines a cylindrical internal space IS extending along an axis (axis AX1, axis AX2). In step S101 for measuring the temperature, the temperature of the components (water tube 19, wall 26) arranged in each of a plurality of regions R preset for the wall (furnace wall 12, wall 26) may be measured.

[0064] According to the above method (3), the degree of thermal fatigue damage can be grasped for each of a plurality of regions R that are set in advance for the wall portion (furnace wall 12, wall portion 26).

[0065] (4) In some embodiments, in the method of (3) above, in step S101 for measuring the temperature, temperature measurements may be made of components (water pipes 19, wall portion 26) arranged in a plurality of regions R that are preset on the wall portion (furnace wall 12, wall portion 26) so that the positions along the axis (axis AX1, axis AX2) are different from one another.

[0066] According to the method (4) above, when the thermal fatigue life tends to vary depending on the position in the direction of the axis (axis AX1, axis AX2), the range in which the thermal fatigue life is similar can be divided into multiple regions R at different positions in the direction of the axis (axis AX1, axis AX2).

[0067] (5) In some embodiments, in the method of (3) above, in the step of measuring the temperature, temperature measurements may be made of components arranged in a plurality of regions that are preset on the wall portion so that the regions are located at different positions along a circumferential direction about the axis.

[0068] According to the method (5) above, when the thermal fatigue life tends to vary depending on the circumferential position, the range in which the thermal fatigue life is similar can be divided into multiple regions R at different circumferential positions.

[0069] (6) In some embodiments, in any of the methods (1) to (5) above, the first threshold value Th1 may be a preset value that is equal to or less than 50% when the degree of thermal fatigue damage at which the components (water pipe 19, wall portion 26) are estimated to break is taken as 100%.

[0070] According to the method (6) above, the surface of the components (water pipe 19, wall portion 26) can be removed before relatively large damage occurs that would lead to the breakage of the components (water pipe 19, wall portion 26), thereby reducing the possibility of cracks progressing from relatively small damage, such as microcracks that are difficult to see with the naked eye.

[0071] (7) In some embodiments, in any of the above methods (1) to (6), in step S7 of removing the surface of the member (water pipe 19, wall portion 26), it is preferable to remove only the surface of the member (water pipe 19, wall portion 26) to a depth of 0.2 mm or less from the surface of the member (water pipe 19, wall portion 26).

[0072] According to the method (7) above, it is possible to remove relatively small damage, such as tiny cracks that are difficult to see with the naked eye, that appear on the surface of the components (water pipes 19, wall portions 26) while suppressing the amount of reduction in the thickness of the components (water pipes 19, wall portions 26).

[0073] (8) In some embodiments, in any of the above methods (1) to (7), the thermal fatigue damage degree may be a value where the thermal fatigue damage degree at which the components (water pipes 19, wall portions 26) are estimated to break is taken as 100%. In some embodiments, any of the above methods (1) to (7) may include a step of inspecting the components (water pipes 19, wall portions 26) for cracks (step S9 of inspecting for cracks) in a region R where the thermal fatigue damage degree calculated in step S3 of calculating the thermal fatigue damage degree is equal to or greater than a second threshold value Th2 that is greater than the first threshold value Th1, before performing step S7 of removing the surfaces of the components (water pipes 19, wall portions 26).

[0074] According to the method (8) above, the presence or absence of cracks is inspected for components (water pipes 19, wall portions 26) in region R where the possibility of the components (water pipes 19, wall portions 26) breaking is relatively high, so that inspection for the presence or absence of cracks can be carried out efficiently.

[0075] (9) In some embodiments, in the method (8) above, step S7 of removing the surface of the component (water pipe 19, wall portion 26) may be performed if no cracks are found in the component (water pipe 19, wall portion 26) in the step of inspecting for the presence or absence of cracks (step S9 of performing crack inspection).

[0076] According to the method (9) above, even if no cracks are found in the components (water pipe 19, wall portion 26) in the step of inspecting for the presence or absence of cracks (step S9 of performing crack inspection), relatively small damage such as microcracks that are difficult to detect with the naked eye and are difficult to detect in the inspection for the presence or absence of cracks (step S9 of performing crack inspection) can be removed from the surface of the components (water pipe 19, wall portion 26).

[0077] (10) In some embodiments, in the method of (8) above, if a crack is found in a component (water pipe 19, wall portion 26) in the step of inspecting for the presence or absence of cracks (step S9 of performing crack inspection), all components (water pipe 19, wall portion 26) in the above-mentioned region R including the component (water pipe 19, wall portion 26) in which the crack was found are replaced (step S21 of performing switchover repair is performed), or the crack is removed and then overlay welding is performed (step S17 of performing overlay welding repair is performed).

[0078] According to the method of (10) above, cracks found in the inspection for the presence or absence of cracks (performing step S9 for performing the crack inspection) can be repaired. [Explanation of symbols]

[0079] 10. Boiler 11 Furnace 12 Furnace wall 19 Water pipe 20. Finn 25 Equipment 26 Wall 28 Temperature Sensor 30. Thermal fatigue damage calculation device

Claims

1. A method for extending the life of a component included in a maintenance target device in a plant, comprising: measuring the temperature of the components arranged in each of a plurality of predetermined areas in the maintenance target device; calculating a thermal fatigue damage degree of the component for each of the plurality of regions based on the temperature measured in the temperature measurement step; removing a surface of the component from the region where the thermal fatigue damage degree calculated in the step of calculating the thermal fatigue damage degree is equal to or greater than a first threshold value; Equipped with How to extend the life of components.

2. The plurality of regions are regions set based on the length of a thermal fatigue life, In the step of measuring the temperature, a temperature of a part of the member in each of the plurality of regions is measured; In the step of calculating the thermal fatigue damage degree, the thermal fatigue damage degree calculated based on the temperature measured in the step of measuring the temperature is regarded as the thermal fatigue damage degree of all of the members in the region. The method for extending the life of a component according to claim 1.

3. The maintenance target device has a wall portion defining a cylindrical internal space extending along an axis, In the step of measuring the temperature, a temperature of the member disposed in each of the plurality of regions preset on the wall portion is measured. A method for extending the life of a component according to claim 1 or 2.

4. In the step of measuring the temperature, a temperature of the member disposed in each of the plurality of regions that are preset on the wall portion such that the positions along the axis are different from each other is measured. The method for extending the life of a component according to claim 3.

5. In the step of measuring the temperature, a temperature of the member disposed in each of the plurality of regions that are preset on the wall portion such that the positions along a circumferential direction around the axis are different from each other is measured. The method for extending the life of a component according to claim 3.

6. The first threshold is a preset value that is equal to or less than 50% when the thermal fatigue damage degree at which the member is estimated to break is set to 100%. A method for extending the life of a component according to claim 1 or 2.

7. In the step of removing the surface of the member, the surface of the member is removed to a depth of 0.3 mm or less from the surface of the member. A method for extending the life of a component according to claim 1 or 2.

8. The thermal fatigue damage degree is a value where the thermal fatigue damage degree at which the member is estimated to break is taken as 100%, a step of inspecting the component for the presence or absence of cracks in the region where the thermal fatigue damage degree calculated in the step of calculating the thermal fatigue damage degree is equal to or greater than a second threshold value that is greater than the first threshold value, before performing the step of removing the surface of the component; Equipped with A method for extending the life of a component according to claim 1 or 2.

9. The step of removing the surface of the component is performed if no cracks are found in the component in the step of inspecting for the presence or absence of cracks. The method for extending the life of a component according to claim 8.

10. If a crack is found in the member in the step of inspecting for the presence or absence of the crack, all members in the region including the member in which the crack was found are replaced, or the crack is removed and then build-up welding is performed. The method for extending the life of a component according to claim 8.

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