KR20230058336A - System and Method for inspection to prevent demage of tube caused by high temperature - Google Patents

Abstract

An inspection system capable of optimally designing an inspection to prevent high-temperature damage to a boiler tube is disclosed. The inspection system generates a current inspection result using a sensor system that senses a tube to generate sensing information, a data collector that collects the sensing information, and the sensing information obtained by being connected to the data collector through a communication network, It characterized in that it comprises a computer for generating maintenance plan information by evaluating the state of the tube according to the current inspection result.
By using the operation information of the tube, the damage of the tube is evaluated, and by using the failure history and previous inspection results, whether or not to inspect and replace the tube is determined before establishing the overhaul plan, and it is reflected when establishing the overhaul plan, so that the maintenance manager can properly It is possible to secure the replacement quantity and easily establish an inspection plan.

Description

Inspection system and method for preventing damage of tube high temperature {System and Method for inspection to prevent demage of tube caused by high temperature}

The present invention relates to a tube inspection technology, and more particularly, to a system and method for optimally designing an inspection to prevent high-temperature damage to a boiler tube.

Boiler tubes are the most frequently broken boiler components, and many difficulties arise in inspection and diagnosis due to the huge number of thousands or more and the long length of 30 ~ 50m per tube.

In addition, as boilers increase in capacity and increase in efficiency, problems such as economic loss and unstable power supply and demand due to breakdown damage occur. Various technologies and systems are applied to prevent this, but they are not effective.

To elaborate, a technology is proposed that enables users to intuitively find the tube position through boiler tube 3D CAD modeling and easily input/inquire inspection information. However, in this case, there is a problem in that it is impossible to provide an appropriate inspection time/position and replacement time/position of the tube, and continuous efforts are required to manage various and vast inspection information.

In addition, a technique for providing an alarm when an abnormal pattern occurs by learning the correlation between the boiler tube-related sensors (power output, excess air ratio, each tube outlet temperature sensor, steam pressure, etc.) and normal operation patterns has been proposed. In this case, the severity and failure information (location/type) of the alarm is not provided, so it is difficult to establish preventive maintenance measures. there is.

In addition, in order to perform the inspection during the overhaul period, the replacement part and the inspection part/method are determined at least six months before the overhaul, and the supply and demand of the replacement quantity and the inspection contract can be concluded. However, all conventional technologies always perform inspections on the same parts despite aging and environmental changes, and since the amount of replacement is determined after inspection, the person in charge of boiler maintenance has no choice but to prepare insufficient or excessive amounts of equipment. It is impeding the stable operation of maintenance and efficient execution of maintenance budget.

In general, tube modules exposed to high temperature damage such as boiler superheaters and reheaters vary depending on capacity, but about 1,000 tubes are installed per tube module, and about 15 to 30 tubes are gathered to form a bank (bank or Panel), and about 20 to 80 banks are gathered to become one superheater and reheater.

Typical high-temperature damages that occur in superheaters and reheaters exposed to high temperatures include long-term creep, short-term creep, and high-temperature corrosion damage. The only way to come out is to perform non-destructive testing during shutdown.

On the other hand, the non-destructive inspection method for inspecting the damage of the boiler tube and its advantages and disadvantages are as follows.

High-temperature damage to the tube grows into microcracks after creep pores (long-term/short-term creep damage) occur, and when microcracks (μm) are created, it is very likely to be damaged in a short period of time, so the tube is usually replaced when creep pores occur.

In the case of high-temperature corrosion, after the first micro-corrosion pit (μm unit) occurs, it grows into a micro crack, and when a micro crack (μm unit) is created, it is very likely to be damaged in a short period of time. Usually, the tube is replaced when the corrosion pit grows more than mm or when micro cracks occur.

Therefore, penetrant/ultrasonic/magnetic particle inspection can be inspected only right before the tube is damaged due to sufficient growth of the crack, so it is very limited in preventing tube rupture because it is generally possible to inspect only when performing boiler inspection (overhaul) every 2 years.

Among the above inspection methods, the metal structure replication and hardness measurement can detect and manage progress from the initial defect occurrence stage of the tube. It is mainly used by supplementing the tissue cloning result.

The metal structure replication method can detect various defects and cracks, but it is very expensive and takes a long time to detect. Considering the limited overhaul period and budget, the most vulnerable part of the boiler tube should be inspected. It is inefficient in preventing breakdowns because the inspection is performed by setting up an area that is easy to inspect due to the accident site or site conditions.

In addition, in order to perform the inspection during the overhaul period, the replacement part and the inspection part/method are determined at least six months before the overhaul, and the supply and demand of the replacement quantity and the inspection contract can be concluded. However, all conventional technologies always perform inspections on the same parts despite aging and environmental changes, and since the amount of replacement is determined after inspection, the person in charge of boiler maintenance has no choice but to prepare insufficient or excessive amounts of equipment. It is impeding the stable operation of maintenance and efficient execution of maintenance budget.

1. Korea Patent Publication No. 10-2013-0088557

The present invention has been proposed to solve the problems caused by the above background art, and an object of the present invention is to provide an inspection system and method capable of optimally designing an inspection to prevent high-temperature damage to a boiler tube.

In addition, the present invention evaluates the damage of the tube using the operation information of the tube, uses the failure history and previous inspection results to determine whether to inspect and replace the tube before establishing an overhaul plan, and establishes an overhaul plan By reflecting it at the time of inspection, the person in charge of maintenance can secure an appropriate replacement quantity and easily establish an inspection plan. Another object is to provide an inspection system and method.

In addition, the present invention improves the accuracy of tube condition diagnosis to effectively perform preventive maintenance of the tube and to execute optimal inspection and replacement costs. Another object is to provide an inspection system and method.

In order to achieve the object presented above, the present invention provides an inspection system capable of optimally designing an inspection for preventing high-temperature damage to a boiler tube.

The inspection system,

A sensor system for generating sensing information by sensing the boiler and the tube;

a data collector collecting the sensing information; and

and a computer that is connected to the data collector through a communication network to generate a current inspection result using the obtained sensing information and to evaluate a tube state according to the current inspection result to generate maintenance plan information.

In addition, the sensing information is characterized in that it includes operation information of the boiler and the tube.

In addition, the computer may include an acquisition module for acquiring the sensing information including the driving information; an analysis module for evaluating a degree of damage to the tube using the operation information; a calculation module for determining whether to inspect and replace the tube before establishing an overhaul plan by using the current inspection result and the failure history and previous inspection results previously stored in a database; and a notification information generation module configured to generate the maintenance plan information according to the determination as notification information.

Further, the evaluation is any one of the first stage indicating inspection omission, the second stage indicating inspection review, the third stage indicating inspection, the fourth stage indicating inspection and replacement review, and the fifth stage indicating replacement. to be characterized

In addition, the evaluation of the degree of damage of the tube is performed using creep damage, tissue replication test, and hardness measurement information, and is evaluated using the creep damage relational expression obtained from the creep failure test of the material and the operation information that is subjected to creep damage. characterized by

In addition, the operation information is characterized in that the operation information before the design of the current planned preventive maintenance work after the previous planned preventive maintenance work.

In addition, the tissue replication test and hardness measurement information uses the previous test results, and in this test, creep voids are detected or the tissue deterioration grade is E or F and the hardness is lowered by 30% or more of the design strength conversion value In this case, the tube is determined to be defective.

In addition, the creep damage relational expression is calculated using the temperature of the tube and the stress of the tube, and the calculation of the temperature of the tube is characterized in that it is performed using the flow rate of the tube flowing through the tube.

In addition, the flow rate of the tube is calculated by calculating the flow rate distribution of each tube constituting a boiler tube model composed of an inlet header, an outlet header, and a plurality of tube banks, and the tube bank is characterized in that it consists of a plurality of tubes .

In addition, the stress of the tube is calculated using the allowable temperature calculation formula of the outlet design steam temperature of the entire tube module or the median value of the outlet operating steam temperature calculated from the operating history of the preset period and the standard deviation. Characterized in that it is an allowable stress at temperature.

In addition, the inspection position of the tube is characterized in that any one of a bend part, a welded part, and a thickness change part at the tube outlet selected using the creep damage relational expression and the operation history.

In addition, when the thickness variation part or the welding part is present in the middle part of the tube, it is characterized in that it is selected as the inspection position.

In addition, the part replaced as the cause of the defect was found to be creep in the previous construction is selected as the above inspection location during the first planned preventive maintenance work after replacement. to be characterized

On the other hand, another embodiment of the present invention, (a) generating sensing information by sensing the tube by the sensor system; (b) collecting the sensing information by a data collector; and (c) generating a current inspection result using the obtained sensing information by a computer connected to the data collector through a communication network and generating maintenance plan information by evaluating a tube state according to the current inspection result. It provides an inspection method for preventing high-temperature damage to the tube, characterized in that.

On the other hand, another embodiment of the present invention, (a) a computer using a database having real-time operation state information of the tube to calculate the flow rate distribution for each tube; (b) calculating, by the computer, the temperature stress for each tube using the flow rate distribution for each tube; (c) calculating, by the computer, an instantaneous damage value for each tube using the temperature stress for each tube; (d) The computer calculates a plurality of instantaneous damages through the stress-temperature-life relationship obtained from the instantaneous average operating value of the tube and the creep failure test data for the tube material, and accumulates a plurality of the instantaneous damage values for each tube Calculating a cumulative damage value; and (e) selecting, by the computer, a specific condition evaluation index and a tube to be replaced using the inspection result and maintenance history inspected in the previous maintenance using the cumulative damage value for each tube for a certain period of time. Provides an inspection method for preventing high-temperature damage to a tube characterized by

According to the present invention, the damage of the tube is evaluated using the operation information of the tube, and the inspection and replacement of the tube is determined before the establishment of the overhaul plan using the failure history and the previous inspection result, and is reflected in the establishment of the overhaul plan. By doing so, the person in charge of maintenance can secure an appropriate replacement quantity and easily establish an inspection plan.

In addition, another effect of the present invention is that it is possible to effectively perform preventive maintenance of the tube by improving the accuracy of tube condition diagnosis and to execute the optimal inspection and replacement cost.

In addition, another effect of the present invention is that a remote monitoring/diagnosing business is possible with only on-site sensors and driving data.

1 is a block diagram of an inspection system according to an embodiment of the present invention.
FIG. 2 is a detailed block diagram of the computer shown in FIG. 1 .
FIG. 3 is a detailed block diagram of the controller shown in FIG. 2 .
4 is a flowchart showing a maintenance process for preventing high-temperature damage to a tube according to an embodiment of the present invention.
5 is a creep damage relationship table according to an embodiment of the present invention.
6 is an example of a model for calculating the flow rate distribution of each tube bank according to an operating condition according to an embodiment of the present invention.
7 is a graph showing the result of comparing errors between experiments and calculations for mass flow rate according to an embodiment of the present invention.
8 is a graph showing the result of comparing errors of experiments and calculations for static pressure according to an embodiment of the present invention.
9 is a graph of general tube operating temperature fluctuation characteristics.
10 is a conceptual diagram of an inspection using a temperature sensor according to an embodiment of the present invention.
11 is an example of a screen taken by enlarging a cross section of a general target tube.
12 is a flowchart showing a maintenance process for preventing high-temperature damage to a tube according to another embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them, will become clear with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, only the present embodiments make the disclosure of the present invention complete, and those skilled in the art in the art to which the present invention belongs It is provided to fully inform the person of the scope of the invention, and the invention is only defined by the scope of the claims. The sizes and relative sizes of components shown in the drawings may be exaggerated for clarity of explanation.

Like reference numbers throughout the specification indicate like elements, and “and/or” includes each and every combination of one or more of the recited items.

Terms used in this specification are for describing embodiments and are not intended to limit the present invention. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. The referenced elements, steps, operations and/or elements that “comprise” and/or “comprise” as used in the specification do not exclude the presence or addition of one or more other elements, steps, operations and/or elements. .

Although used to describe various components such as first and second, these components are not limited to these terms, of course. These terms are only used to distinguish one component from another. Accordingly, it goes without saying that the first component mentioned below may also be the second component within the technical spirit of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used in a meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless explicitly specifically defined.

Hereinafter, an inspection system and method for preventing high-temperature damage to a tube according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an inspection system 100 according to an embodiment of the present invention. Referring to FIG. 1, the inspection system 100 includes a sensor system 110 that senses a boiler and/or a tube to generate sensing information, a data collector 120 that collects sensing information, a communication network 130, and a communication network 130. ) It may be configured to include a computer 140 that generates inspection results using the collected sensing information and generates maintenance plan information by evaluating tube conditions according to the inspection results.

The sensor system 110 may include a first measuring device 111 , a second measuring device 112 , a differential pressure gauge 113 , a sensor 114 , and the like. The first meter 111 may be an inlet header flow meter, the second meter 112 may be a tube flow meter, and the differential pressure gauge 113 may be a header and tube bank differential pressure meter. The sensor 114 is a sensor installed in a boiler and/or a tube and may be a temperature sensor or the like.

In general, tube modules exposed to high temperature damage such as boiler superheaters and reheaters vary depending on capacity, but about 1,000 tubes are installed per tube module, and about 15 to 30 tubes are gathered to form a bank (bank or Panel), and about 20 to 80 banks are gathered to become one superheater and reheater.

Typical high-temperature damages that occur in superheaters and reheaters exposed to high temperatures include long-term creep, short-term creep, and high-temperature corrosion damage. The only way to come out is to perform non-destructive testing during shutdown.

Therefore, in one embodiment of the present invention, the damage of the tube is evaluated using the operation information of the tube, and whether or not to inspect and replace the tube is determined before establishing the overhaul plan using the failure history and previous inspection results, and this is reflected when establishing the overhaul plan. By doing so, the person in charge of maintenance of the boiler secures an appropriate amount of replacement, easily establishes an inspection plan, improves the accuracy of tube condition diagnosis, effectively performs preventive maintenance of the tube, and executes the optimal inspection and replacement cost.

Still referring to FIG. 1 , the data collector 120 collects sensing information generated from the sensor system 110 and transmits it to the computer 140 through the communication network 130 . The data collector 120 may be a data acquisition device. The data collector 120 may include a communication module for connection with the communication network 130 . In addition, the data collector 120 may be connected to the operation controller 101 that controls the boiler (not shown) to obtain operation information of the boiler and/or the tube. The operation controller 101 may include a microprocessor, a microprocessor, a switching circuit element, and the like.

The communication network 130 means a connection structure capable of exchanging information between each node, such as a plurality of terminals and servers, such as a public switched telephone network (PSTN), a public switched data network (PSDN), and an integrated information communication network (ISDN: Integrated Services Digital Networks), Broadband ISDN (BISDN), Local Area Network (LAN), Metropolitan Area Network (MAN), Wide LAN (WLAN), etc. However, the present invention is not limited thereto, and the wireless communication network CDMA (Code Division Multiple Access), WCDMA (Wideband Code Division Multiple Access), Wibro (Wireless Broadband), WiFi (Wireless Fidelity), HSDPA (High Speed Downlink) A packet access) network, a Bluetooth network, a near field communication (NFC) network, a satellite broadcasting network, an analog broadcasting network, a digital multimedia broadcasting (DMB) network, and the like. Alternatively, it may be a combination of these wired communication networks and wireless communication networks.

The computer 140 performs a function of generating inspection results using sensing information and generating maintenance plan information by evaluating tube conditions according to the inspection results. In other words, the computer 140 evaluates the damage of the tube using the operation information of the tube, and determines whether to inspect and replace the tube using the failure history and previous inspection results before establishing an overhaul plan, and checks it ( Overhaul), it is reflected in the establishment of the plan so that the person in charge of maintenance of the boiler secures an appropriate amount of replacement and easily establishes an inspection plan, improves the accuracy of tube condition diagnosis, effectively performs preventive maintenance of tubes, and executes optimal inspection and replacement costs. make it possible

The computer 140 may be a personal computer (PC) or a server. A database 141 may be built in the computer 140 . The database 141 may also store sensing information, identification information on boilers, tubes, and the like.

FIG. 2 is a detailed block diagram of the computer 140 shown in FIG. 1 . Referring to FIG. 2 , the computer 140 is connected to the controller 210 and the communication network 130 for generating inspection results using sensing information and evaluating tube conditions according to the inspection results to generate maintenance plan information. A communication unit 220 that obtains information, a storage unit 230 that stores sensing information obtained through the communication unit 220, a power unit 240 that supplies power to components, and an input unit 250 that inputs user commands. ), an output unit 260 for outputting maintenance plan information, and the like.

The controller 210 performs a function of generating inspection results using sensing information and generating maintenance plan information by evaluating tube conditions according to the inspection results. To this end, it exchanges signals with the components and performs control.

The communication unit 220 performs a communication connection with the communication network 130 and performs a function of connecting communication between the data collector 120 and the computer 140 . To this end, the communication unit 220 may include a wired or wireless modem, a LAN card, a microprocessor, and the like.

The storage unit 230 performs a function of storing the database 141 . In addition, the storage unit 230 stores programs, software, data, etc. having an algorithm for generating test results using sensing information and generating maintenance plan information by evaluating tube conditions according to the test results.

To this end, the storage unit 230 may be a flash memory type, a hard disk type, a multimedia card micro type, or a card type memory (eg SD (Secure Digital)). or XD (eXtreme Digital) memory, etc.), RAM (Random Access Memory, RAM), SRAM (Static Random Access Memory), ROM (Read Only Memory, ROM), EEPROM (Electrically Erasable Programmable Read Only Memory), PROM (Programmable Read Only Memory) Only Memory), a magnetic memory, a magnetic disk, and an optical disk may include at least one type of storage medium. In addition, it may operate in relation to a web storage and a cloud server that perform a storage function on the Internet.

The power supply unit 240 serves to supply power to components. To this end, it may include a power supply, a regulator, an alternating current (AC)-direct current (DC) converter, and the like.

The input unit 250 performs a function of inputting a user's command. Therefore, it may be configured to include a mouse, keyboard, microphone, and the like.

The output unit 260 performs a function of outputting a setting screen, a processing information screen, and the like. To this end, the output unit 260 includes a liquid crystal display (LCD), a light emitting diode (LED) display, a plasma display panel (PDP), an organic LED (OLED) display, a touch screen, a cathode ray tube (CRT), and a flexible display. , micro LED, mini LED, etc. In the case of a touch screen, it can be used as an input means. Also, the output unit 260 may include a sound system.

FIG. 3 is a detailed block diagram of the controller 210 shown in FIG. 2 . Referring to FIG. 3 , the controller 210 includes an acquisition module 310 for obtaining sensing information including operation information of the tube, an analysis module 320 for evaluating the degree of damage to the tube using the operation information, and a failure history. A calculation module 330 that determines whether or not to inspect and replace the tube before establishing an overhaul plan using the results of the previous inspection, and a notification information generation module 340 that generates maintenance plan information according to the decision as notification information can be configured to include

The analysis module 320 performs a function of evaluating the damage of the tube using the operation information of the tube.

The calculation module 330 determines whether or not to inspect and replace the tube before establishing an overhaul plan using the failure history and previous inspection results stored in the database in advance, and has a function to reflect this when establishing an overhaul plan. carry out

The notification information generation module 340 performs a function of generating notification information so that a boiler maintenance manager secures an appropriate replacement quantity and easily establishes an inspection plan. Therefore, it is possible to effectively perform preventive maintenance of the tube by improving the accuracy of tube condition diagnosis and to execute the optimal inspection and replacement cost.

The "acquisition module", "analysis module", "calculation module", notification information generation module", etc. shown in FIG. 3 refer to units that process at least one function or operation, which may be implemented in software and/or hardware. In hardware implementation, ASIC (application specific integrated circuit), DSP (digital signal processing), PLD (programmable logic device), FPGA (field programmable gate array), processor, and microcontroller designed to perform the above functions It can be implemented as a processor, other electronic unit or a combination thereof In software implementation, software component (element), object-oriented software component, class component and task component, process, function, property, procedure, sub may include routines, segments of program code, drivers, firmware, microcode, data, databases, data structures, tables, arrays and variables Software, data, etc. may be stored in memory and executed by a processor. The memory or processor may employ various means well known to those skilled in the art.

4 is a flowchart showing a maintenance process for preventing high-temperature damage to a tube according to an embodiment of the present invention. Referring to FIG. 4 , the process proceeds cyclically from the tube state evaluation and replacement quantity prediction step (S410) to the operating state analysis step (S481), which is differentiated from the conventional system which is linear and one-off.

In the tube condition evaluation and replacement quantity prediction step (S410), defect cause analysis information according to past tube defect cause analysis (S460), inspection results and maintenance history information according to inspection results and maintenance history (S471), and planned preventive maintenance work After that, the condition of the tube is evaluated on a scale of 1 to 5 (i.e., stage) by integrating the driving condition analysis information according to the driving condition analysis (S481) using the driving history up to now, and among them, the 5th stage with the most serious condition It is recommended to replace the tube, and for the 4th stage, it is recommended to replace it when the 5th stage is reached before the next planned preventive maintenance period arrives (4 years later). Here's a look at the 5 stages:

stage One 2 3 4 5 even matters omission inspection review test inspection and
replacement review substitute

In the table above, it is okay to omit the inspection for the 1st stage during this planned preventive maintenance construction, and for the 2nd stage, the inspection can be conducted or postponed to the next inspection depending on the construction period and budget. The 3rd and 4th stages must be inspected as essential in this planned preventive maintenance work, and in the case of the 4th stage, replacement may be required depending on the inspection results. If construction is scheduled, replacement can be delayed for one year. In the case of stage 5, replacement quantity must be secured and inspection can be performed if data collection is required. Accurate results can be obtained only by integrating, but in the case where steps S461 and S471 have not been performed in the past, the information generated by step S481 must be obtained before evaluation can be performed. Usually, when a new boiler tube high-temperature damage preventive maintenance technique is applied or a system is installed, information according to steps S461 and S471 cannot be obtained, but information according to step S481 is acquired by sensors installed in most boilers, so tube condition evaluation is impossible. cases are difficult to find.

Tube condition evaluation is determined by the following evaluation procedure. Creep damage can be evaluated using operation information from the previous planned preventive maintenance work to the current planned preventive maintenance work design and the creep damage relational expression obtained from the creep failure test of the material such as the Larson-Miller parameter. Tissue replication test and hardness measurement generally use the previous test result (S400), and if Creep Void is detected in this test or the tissue deterioration grade is E or F and the hardness is reduced by more than 30% of the design strength conversion value, it is judged as a defect. (SS460), replacement is recommended.

Steps S461, S471, and S481 provide information necessary for performing step S410. Step S461 reflects past defect locations when selecting an inspection location, and step S471 provides inspection results for tube condition evaluation and tube maintenance history. Information necessary for tube temperature calculation, such as usage time and past oxide scale thickness, is provided, and step S481 provides key operation information for tube creep damage evaluation. Operation information such as pressure may be included.

In addition, step S420 is a step of reflecting the result of step S410 to the site, providing information such as inspection location, location, method, and scaffolding / scaffolding installation location for inspection to the planned preventive maintenance work design, and tubes with a high possibility of damage This is the stage to ensure that there are no disruptions to the construction by selecting, calculating the replacement quantity, and placing an order before construction.

Meanwhile, the procedures from step S410 to step S471 are generally performed step by step independently, but all or part of the steps can be processed by a computer system, and additional work is required to automatically link steps to steps. In particular, since the data processed in step S471 is time-series data and is a value continuously recorded over time, a special database is required to manage it, and it may be difficult to utilize when using a general relational database.

Real-time database is a special database for managing time-series data. There are commercialized products, and various interfaces are supported to support complex calculations at the S410 stage. However, in the case of open source real-time databases, interface support is very limited, so it is difficult for users to develop, so they are rarely used.

5 is a creep damage relationship table according to an embodiment of the present invention. Referring to FIG. 5 , the degree of creep damage is calculated by steps S410 and S481, the tissue replication test is calculated by steps S461 and S471, and the hardness measurement information is calculated by steps S461 and S471. * shown in FIG. 5 indicates that creep destruction experiments are performed by performing additional inspections or extracts as a result of specific inspections, and ** indicates that short-term overheating is suspected, so additional inspections are performed or extractions are performed to perform creep destruction experiments.

6 is an example of a model for calculating the flow rate distribution of each tube bank according to an operating condition according to an embodiment of the present invention. In general, the creep damage evaluation result among the condition evaluation factors of the boiler tube is determined by the accuracy of input data and the appropriateness of the evaluation method. It is difficult to trust, etc., and the improvement method to solve this is as follows.

The tube condition evaluation method follows the traditional creep damage evaluation technique, but the step of calculating the temperature of the tube and the step of calculating the tube stress are significantly different from the conventional method. The conventional method of calculating the temperature of a tube assumes that the flow rate flowing through each tube is the same and the value is an average value to calculate the temperature of the tube, but the actual tube is The flow rate of each tube is determined by the connection type of the header. In general, the process of calculating the flow rate of a tube is very important because the difference between the maximum flow rate and the minimum flow rate of a tube represents a difference of 10 to 20%.

A theoretical method for calculating the flow rate of a complex pipe network such as a boiler tube can be a flow network analysis method or similar commercial software. The process of calculating the flow rate of these tubes is as follows.

①. Using the pressure loss coefficient formula or graph for the components of one tube flow path, calculate the pressure loss coefficient formula or graph for the entire flow path for possible operating conditions such as temperature, pressure, and flow range. The general form of the pressure loss coefficient in the pipe is as follows.

Here, f: coefficient of friction, L: pipe length, D: pipe diameter. The coefficient of friction is:

That is, Filonenko's equation for turbulent flow.

Here, Re: Reynolds number of pipe flow. Re is equal to the following equation.

Here, μ: viscosity coefficient of the fluid, ρ: density of the fluid, v: velocity of the fluid, D: diameter of the pipe.

②. For a tube bank (or panel, bundle) composed of multiple tubes using commercial software that performs flow network analysis or similar functions, the pressure loss coefficient formula or diagram of each flow path calculated in procedure ① and possible operating conditions Calculate the pressure loss coefficient formula or diagram and the flow distribution of each tube passage by

③. For the boiler tube model composed of inlet and outlet headers and a number of tube banks using flow network analysis or commercial software that performs similar functions, the pressure loss coefficient equation or diagram of the tube bank obtained in step ② and possible operating conditions Calculate the flow distribution of each tube bank by

④. Calculate the flow rate distribution of each tube constituting the boiler tube model using the flow rate distribution of each tube bank in step 3 and the flow rate distribution of each tube in the bank in procedure ②.

6 shows examples of the above procedures ① to ③. Procedures ① and ② calculate the pressure loss coefficient of a single tube flow path and tube bank using Flowmaster, a commercial flow path design software, and process ③ is a flow network analysis method was calculated using It consists of a tube passage pressure loss calculation step (S610), a tube bank pressure loss calculation step (S620), and a tube module flow rate distribution calculation step (S630).

7 is a graph showing the result of comparing errors between experiments and calculations for mass flow rate according to an embodiment of the present invention. Referring to FIG. 7 , a mass flow rate 710 at the divide header outlet and a mass flow rate 720 at the combine header outlet are concentrated at the boundary between experiment and calculation. That is, as a result of comparing the errors of experiment and calculation, good flow rate results are shown.

8 is a graph showing the result of comparing errors of experiments and calculations for static pressure according to an embodiment of the present invention. Referring to Fig. 8, the static pressure 810 at the outlet of the distribution header and the static pressure 820 at the outlet of the coupling header are concentrated at the boundary between experiment and calculation. That is, as a result of comparing the errors of experiment and calculation, good static pressure results are shown.

9 is a graph of operating temperature fluctuation characteristics of a general tube. Referring to FIG. 9, in general, the conventional methods of calculating the stress acting on the tube for evaluating the creep damage of the tube are the method of calculating the hoop stress using the pressure of the steam flowing inside the tube and the allowable stress using the operating temperature. A method for calculating is presented. The former method is presented in industry standard codes such as ASME (American Society of Mechanical Engineers) and KEPIC (Korea Electric Power Industry Code, KEPIC), but has the disadvantage that the value of calculated damage is too small to discriminate between tubes. As shown in FIG. 9, the method has a disadvantage in that it is difficult to apply in practice because the fluctuation characteristics of the outlet tube metal temp are too large. In addition, even if a larger value is selected by comparing these two values, there is a difficulty in that the stress for evaluating damage does not maintain consistency and does not match the actual driving phenomenon.

In order to solve the above problems, the stress of the tube is calculated through the following procedure based on the allowable temperature calculation method presented by the international pressure vessel code TRD 300 and IBR (Indian Boiler Regulation).

①. Calculate the median value and standard deviation of the outlet operating steam temperature from the outlet design steam temperature of the entire tube module or from the operating history of more than one year (considering the operating characteristics of the boiler according to seasonal changes).

②. When the outlet design steam temperature is obtained, the allowable temperature of the tube is calculated using the allowable temperature calculation formula of TRD300, or when the median value and standard deviation of the outlet operating steam temperature are calculated. To ensure discrimination and stability of maintenance decision-making, the lower of the two allowable temperatures is determined as the allowable temperature.

The outlet design steam temperature and outlet operating steam temperature conditions are as follows.

와

이며 T_mx는 예상되는 최대증기온도이다. The original expression of IBR is

and

and T _mx is the expected maximum steam temperature.

In the above formula, _Td is the outlet design steam temperature, T _m is the median outlet operating steam temperature, T _sd is the outlet operating steam temperature standard deviation, and n is a value determined by the boiler type and tube module position, which is 1, 1.5, or 2. select one value The default value is 1.5, and the closer the radiant superheater is to the boiler furnace outlet, the larger the value, and the farther away the convection superheater is.

In general, the outlet design steam temperature of the boiler is given only for the final superheater and final reheater, and not for the primary and secondary superheaters and reheater, so the outlet operating steam temperature condition must be applied.

③. Determine the allowable stress at the allowable temperature of the tube calculated in procedure ② as the stress acting on the tube. This determination method is conceptually consistent with the method for determining the lifespan of tubes by boiler manufacturers, and even if the outlet design steam temperature is not secured, it is reasonably evaluated through international codes related to pressure vessels, operation history, and statistical methods to determine the reliability of various tube modules. damage assessment is possible.

On the other hand, the conventional tube inspection location selection method was collectively determined based on past accident cases and boiler tube maintenance guidelines to inspect only the same location without considering the operation history and characteristics of the boiler. However, there are many cases in which the accident location of the actual boiler tube does not coincide with the location determined collectively, and the problems of the conventional method are recognized, but no improved method has been presented.

An embodiment of the present invention proposes an improved tube inspection position selection concept. The new tube inspection location selection method is selected according to the following procedure in consideration of the improved tube creep damage technique and the weak parts presented in the boiler tube maintenance guideline.

①.Evaluate the degree of damage of the tube where the sensor is installed using the improved tube creep damage technique and operation history.

*②. Among the tubes without sensors installed, if the state of the nearby tube is evaluated as 3 or more stages, the tube with the sensor installed in the same bank is evaluated as 3 or more stages, or the tube with the sensor installed in the same column position of the neighboring bank If is one of the two cases where is evaluated as 3 or more stages, both are included in the test subject.

③. In procedure ②, if there are tubes without sensors installed in the same bank as the tubes with 3 or more stages of condition evaluation, the tube with the smallest flow rate among the target tubes and is sensitive to the temperature change of the combustion gas, so it is most likely to be exposed to high temperatures. is selected as the subject of inspection.

④.Select the bent pipe part, welding part, and thickness change part of the tube outlet selected in procedure ① ~ procedure ③ as inspection targets. Select the inspection location. If there is only a straight tube part at the tube outlet, the highest temperature part is selected as the inspection part and the high temperature part is determined. The method for determining the hot area is as follows.

10 is a conceptual diagram of an inspection using a temperature sensor according to an embodiment of the present invention. Referring to FIG. 10, the upper enclosure (1031) is installed at 10 cm intervals centered on the 3/4 Run part of the longest heat tube outlet on the steam inlet header 1011 and steam outlet header 1012 where temperature sensors 1021 and 1022 are installed. ) and the lower enclosure 1032 by measuring 10 or more oxide scales according to the combustion gas flow 1001 to select the area with the thickest oxide scale as the position for inspection (tissue replication and hardness measurement), and a temperature sensor Select the same position as the inspection position for the target tube where is not installed.

⑤.If there is a thickness change part or a welding part in the middle of the tube selected in Procedure ① ~ Procedure ③, select it as an inspection position.

⑥.In the previous construction, the cause of the defect was found to be creep, and the replaced part is selected as the inspection site for the first planned preventive maintenance work after replacement, and if the inspection result and creep damage evaluation result are good, it is excluded from inspection for up to 4 years.

On the other hand, the inspection is performed through the steps of procedure 1 to procedure 4, and if a defect is found as a result of the inspection, an additional inspection location is selected in the same way as in procedure 3 around the defective part.

11 is an example of a screen taken by enlarging a cross section of a general target tube. Referring to FIG. 11, since the condition evaluation index of the tube can detect not only damage caused by creep but also damage caused by high-temperature corrosion, preventive maintenance is possible using the same method. The high-temperature corrosion of the tube has different activation temperatures for each steel type, but in common, the range of corrosion damage and the probability of occurrence of defects increase in proportion to the temperature of the tube. However, in order to check the corrosion damage, the target tube should be extracted and the cross section should be enlarged and observed. 11 shows a cross section 1110 of a healthy part and a cross section 1120 of a damaged part. The end face 1110 of the intact part has a smooth pretreated surface, and the end face 1120 of the damaged part has a pit on the pretreated surface.

In order to evaluate high-temperature corrosion, the creep damage index and the observation information of the excerpt tube cross section are required, whereas the tube surface tissue replication and hardness measurement are unnecessary. However, high-temperature corrosion and creep tend to occur at the same time and interact with each other to reduce the time to breakage. Therefore, if the tube condition evaluation index corresponds to the 4th stage, some tubes are extracted, surface inspection is performed, and holes ( If defects such as pits or grooves are found, it may be recommended to replace the tube in the current planned preventive maintenance work or at least the next preventive maintenance work.

Therefore, even in the case of preventing damage due to high temperature corrosion, there is no need to change the original index, and it is possible to determine maintenance by performing an additional tube extraction test. The result of the tube extraction test should recommend immediate replacement if there is corrosion damage. However, since the extraction test period takes more than several days, if the replacement period is not secured, replacement should be recommended at the next simple maintenance or the next planned preventive maintenance work. .

In order to reduce inspection costs, in the case of thermal power plants in the Middle East or Southeast Asia, where tissue replication testing is not smooth due to the low level of domestic IPP (Industry Professional Practice) or inspection technology, only hardness is measured or neither tissue replication test nor hardness is performed. Instead, PT (Liquid Penetration Test) / MT (Magnetic Particle Testing) / UT (Ultrasonic Testing) may be performed. In this case, since the condition evaluation of the tube is determined by the degree of creep damage, there is a difference that the inspection range and inspection location depend only on the degree of creep damage, but the overall preventive maintenance method follows the existing method and procedure, and the difference from the existing method is that As follows.

12 is a flowchart showing a maintenance process for preventing high-temperature damage to a tube according to another embodiment of the present invention. Referring to FIG. 12, steps S1210 and S1220 are steps for calculating the flow distribution for each tube by the method described above, and step S1230 calculates the tube stress by a new stress calculation method based on the concept of TRD 300 and the IBR code and calculates the energy. Calculate the temperature using

In step S1240, damage is calculated through the stress-temperature-life relationship obtained from the instantaneous (1 hour to 2 hour) average operating value and the creep failure test data for the tube material. In step S1250, the instantaneous damage values of the tubes are stored for each operation time, and the cumulative damage value is obtained by summing up the instantaneous damage values for each tube, and is also stored for each operation time.

In step S1260, cumulative damage (creep damage) for each tube six months before the maintenance is inquired, and then the latest condition evaluation index and the tube to be replaced are selected using the inspection result and maintenance history information inspected in the previous maintenance. In step S1270, the inspection position of the tube is selected using the past defect location and cause analysis information and the tube condition evaluation index in step S1260. The results of steps S1260 and S1270 are combined to establish a non-destructive inspection and maintenance plan for step S1280.

Meanwhile, it is possible to develop a system capable of monitoring the damage of the tube in real time through the steps from S1220 to S1250. In addition, when constructing the S1201, S1202, S1210, and S1280 steps as a system, it shows the linkage and detailed function execution procedures for each step. Developed programs and data can be linked.

In addition, the steps of a method or algorithm described in connection with the embodiments disclosed herein are implemented in the form of program instructions that can be executed through various computer means such as a microprocessor, processor, CPU (Central Processing Unit), etc. It can be recorded on any available medium. The computer readable medium may include program (instruction) codes, data files, data structures, etc. alone or in combination.

The program (command) code recorded on the medium may be specially designed and configured for the present invention, or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs, DVDs, and Blu-rays, and ROMs and RAMs ( A semiconductor storage element specially configured to store and execute program (instruction) codes such as RAM), flash memory, or the like may be included.

Here, examples of the program (command) code include high-level language codes that can be executed by a computer using an interpreter, as well as machine language codes such as those produced by a compiler. The hardware devices described above may be configured to act as one or more software modules to perform the operations of the present invention, and vice versa.

*100: inspection system
110: sensor system 120: data collector
130: communication network 140: computer
310: acquisition module 320: analysis module
330: calculation module 340: information notification generation module
1011 Steam inlet header 1012 Steam outlet header
1021, 1022: temperature sensor
1031: top enclosure
1032: lower enclosure

Claims (1)

(a) generating sensing information by sensing the boiler and the tube by the sensor system 110;
(b) collecting the sensing information by a data collector 120; and
(c) The computer 140 connected to the data collector 120 through the communication network 130 creates a current inspection result using the obtained sensing information and evaluates the tube state according to the current inspection result to plan a maintenance plan. Generating information; including,
The sensing information includes operation information of the boiler and the tube,
In step (c),
acquiring the sensing information by an acquisition module 310;
Evaluating, by the analysis module 320, a degree of damage to the tube using the operation information; and
The calculation module 330 determines whether to inspect and replace the tube by using the current inspection result, the failure history and the previous inspection result previously stored in the database 141 before establishing an overhaul plan. do,
Evaluation of the degree of damage of the tube is the degree of creep damage,
The creep damage degree is an inspection method for preventing high-temperature damage to the tube, characterized in that evaluated using the operation information and the creep damage relational expression obtained from the creep failure test of the material.

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