Method and device for evaluating creep residual life of high-temperature pressure-containing header

Abstract

Embodiments of the present application disclose a high-temperature pressure-containing header creep residual life evaluation method and device. The method comprises: obtaining working condition data of a header to be evaluated and creep test data of a main steam pipeline in the same batch; fitting a creep curve of the main steam pipeline based on the creep test data, and establishing a parameter mapping of a theta parameter set and working condition variables; calculating an internal pressure reduced stress at a thinnest hole bridge position, and substituting the working condition data into the mapping to obtain a corresponding theta parameter, and then obtaining a creep curve equation under the working condition; calculating the creep residual life of the header to be evaluated according to the creep curve equation, the working condition data and the creep test data; and the device is composed of data acquisition, fitting and mapping, stress calculation, parameter migration and life evaluation units. Through curve migration and life evaluation of the same batch test data and working condition data, the consistency and traceability of the evaluation results are improved, and the stress correction for the weakest part further improves the result accuracy.

Description

Technical Field

[0001] This application relates to the field of power equipment assessment, and in particular to a method and apparatus for assessing the creep remaining life of a high-temperature pressure-bearing header. Background Technology

[0002] As a critical pressure-bearing boundary, the high-temperature header of a power plant boiler operates under the combined effects of high temperature and internal pressure for extended periods. Start-up, shutdown, and deep peak shaving intensify temperature and stress cycles. Due to its complex structure and critical location, it is difficult to directly sample the header body for creep testing while it is in service. This has long presented engineering challenges in data acquisition and standardized data collection for assessing its remaining service life. Furthermore, the area near the perforated bridge at the connection between the header and branch pipes is prone to localized peak stress, and engineering assessments typically need to focus on these vulnerable areas.

[0003] Existing solutions typically follow two paths: one is to calculate fatigue and creep losses by type and use the total loss value to drive life assessment. For example, after determining the reference temperature, fatigue and creep loss analysis is performed on the assessment points, and the remaining life is derived from the total loss value for quantitative processing of the container's in-service assessment. The other is to establish a creep damage model at the material level, measuring damage by the relationship between strain and material ductility parameters, and even using a finite element platform to perform numerical integration and field coupling simulation through user subroutines. The former has a clear process, but it still relies on assumptions regarding local equivalent stress, temperature range, and data consistency; the latter can cover the entire creep process, but it has many model parameters, high equation rigidity and coupling strength, and is difficult to identify parameters and implement in engineering.

[0004] Furthermore, for headers made of materials such as P122, the allowable stress has been lowered multiple times, and existing assessment methods have not incorporated changes in material properties in a timely manner, further affecting the reliability of lifetime assessments. Therefore, there is an urgent need for a method for assessing the remaining creep life of headers that can accurately calculate the effects of stress and temperature and is easy to implement in engineering projects. Summary of the Invention

[0005] The embodiments of this application provide a method and apparatus for assessing the creep remaining life of a high-temperature pressure-bearing header, so as to accurately calculate the impact of the operating conditions of the high-temperature pressure-bearing header on the creep remaining life.

[0006] To address the aforementioned technical problems, embodiments of this application disclose the following technical solutions: A first aspect provides a method for assessing the remaining creep life of a high-temperature pressure-bearing header, comprising: acquiring operating condition data of the header to be assessed and creep test data of a main steam pipeline from the same batch as the header to be assessed; fitting a creep curve of the main steam pipeline based on the creep test data, establishing a parameter mapping relationship between a set of θ parameters and operating condition variables, and calculating the internal pressure equivalent stress at the weakest orifice bridge location of the header to be assessed; obtaining the θ parameters corresponding to the header to be assessed based on the internal pressure equivalent stress, the operating condition data, and the parameter mapping relationship; obtaining the creep curve equation of the header to be assessed under operating conditions based on the θ parameters corresponding to the header to be assessed; calculating the remaining creep life of the header to be assessed based on the creep curve equation and the creep test data; wherein, the operating condition data includes at least the material parameters, structural parameters, temperature parameters, steam pressure, and operating time of the header to be assessed; and the creep test data at least characterizes the creep of the main steam pipeline as a function of stress, temperature, and operating time.

[0007] Furthermore, the calculation of the internal pressure equivalent stress includes: obtaining the minimum hole bridge weakening coefficient based on the geometry of the weakest hole bridge location; performing equal strength correction on the structural parameters and / or steam pressure according to the minimum hole bridge weakening coefficient; calculating the internal pressure equivalent stress based on the structural parameters and / or steam pressure with the minimum hole bridge weakening coefficient introduced; wherein, the structural parameters include at least the outer diameter of the cylinder and the cylinder wall thickness of the header to be evaluated.

[0008] Furthermore, the establishment of the parameter mapping relationship includes: fitting the creep curve of the main steam pipeline based on the creep test data of the main steam pipeline under different temperatures and stresses, and obtaining the fitting equation; and determining the θ parameter values ​​under different temperatures and stresses based on the fitting equation.

[0009] Furthermore, the θ parameter set includes at least θ1, θ2, θ3, θ4 and θ5, wherein θ1 and θ2 are used to characterize the fitting to the first creep stage, θ3 is used to characterize the fitting to the second creep stage, and θ4 and θ5 are used to characterize the fitting to the third creep stage.

[0010] Furthermore, the calculation of the remaining creep life includes: determining the total life of the main steam pipeline under its own operating conditions based on the creep curve of the main steam pipeline and the creep test data; determining the proportion of its consumed life under its own operating conditions based on the operating time of the main steam pipeline and the total life of the main steam pipeline under its own operating conditions; determining the remaining creep life of the main steam pipeline under the operating conditions of the header to be evaluated based on the creep curve equation; using the ratio of the remaining creep life of the main steam pipeline under the operating conditions of the header to be evaluated to the total life of the header to be evaluated under its own operating conditions as the proportion of unconsumed life of materials with the same material parameters operating under different operating conditions; establishing an equation based on the linear damage accumulation rule, where the sum of the proportion of consumed life and the proportion of unconsumed life is 1, to calculate the total life of the header to be evaluated under its own operating conditions; and calculating the remaining creep life of the header to be evaluated based on the operating time of the header to be evaluated and the total life of the header to be evaluated under its own operating conditions.

[0011] Furthermore, the remaining creep life of the main steam pipeline under the operating condition of the header to be evaluated is determined by the inflection points of the second creep stage and the third creep stage of the creep curve equation, wherein the time axis of the creep curve equation takes the moment when the creep curve of the main steam pipeline migrates to the operating condition of the header to be evaluated as the origin.

[0012] Furthermore, the calculation of the remaining creep life also includes: obtaining the total life of the header to be evaluated under the design conditions based on the parameter mapping relationship; using the Larsen-Miller parameter method, based on the total life of the header to be evaluated under the design conditions and the material parameters, performing a temperature correction on the total life of the header to be evaluated under its own operating conditions; the calculation of the remaining creep life is based on the corrected total life of the header to be evaluated under its own operating conditions.

[0013] Furthermore, it also includes: when the allowable stress of the material of the header to be evaluated is reduced or creep test data of the newly added main steam pipeline of the same batch is connected, the operating condition data of the header to be evaluated is updated, and the parameter mapping relationship is incrementally updated.

[0014] The second aspect provides a creep remaining life assessment device for a high-temperature pressure-bearing header, comprising: a data acquisition unit for acquiring operating condition data of the header to be assessed and creep test data of the main steam pipeline in the same batch as the header to be assessed, wherein the operating condition data includes at least material parameters, structural parameters, temperature parameters, steam pressure, and operating time, and the creep test data at least characterizes the creep of the main steam pipeline with stress, temperature, and operating time; a fitting and mapping unit for fitting creep curves of the main steam pipeline under different operating conditions based on the creep test data, and constructing a parameter mapping relationship between the θ parameter set and the operating condition variables; and a stress calculation unit for determining the creep remaining life of the header to be assessed. The system identifies the weakest point of the header and calculates the equivalent internal pressure stress at that point. A parameter migration unit is used to substitute the equivalent internal pressure stress and the temperature parameter into the parameter mapping relationship to obtain the θ parameter corresponding to the operating condition of the header to be evaluated, and to generate the creep curve equation for the header to be evaluated. A life assessment unit is used to obtain the remaining creep life of the main steam pipeline under the operating condition of the header to be evaluated based on the creep curve equation, and to obtain the total life of the main steam pipeline under its own operating condition based on the creep curve of the main steam pipeline. It also uses the linear damage accumulation rule to calculate the remaining creep life of the header to be evaluated based on the operating time of the main steam pipeline.

[0015] Furthermore, it also includes: a dynamic update unit, used to detect the allowable stress reduction of the material of the header to be evaluated or to access the creep test data of newly added main steam pipelines of the same batch, and to update the operating condition data and incrementally update the parameter mapping relationship.

[0016] The above-mentioned technical solutions have at least the following beneficial effects: life assessment is carried out based on data from the same batch of materials as the container to be assessed, avoiding systematic biases caused by different batches or general databases, and improving the consistency and traceability of assessment results; stress correction is performed on the weakest part to reflect the impact of geometric weakening on bearing capacity, which can more realistically reflect structural weaknesses and reduce the risk of underestimation compared to the practice of using nominal stress as a substitute.

[0017] The above technical solution also has the following advantages: it adopts a parameterized curve that can describe the entire creep process, unifies the caliber of the initial, steady-state, and accelerated stages, and directly reads the remaining life by aligning the time origin with the current moment, which is convenient for connection with maintenance decisions; it supports segmented processing of the multi-condition history of in-service equipment, and uses the Larssen-Miller equivalent method to unify temperature differences according to the additive cumulative life ratio of linear damage accumulation, thereby improving the applicability in temperature and load fluctuation scenarios; it has the ability to dynamically update parameters, and when the allowable stress is adjusted or new batches of data are added, the relationship between relevant material constants and parameters can be incrementally updated and verified, so that the evaluation results converge to more conservative and realistic conclusions in a timely manner with long-term service knowledge; it can be expanded to multiple assessment points for parallel evaluation and control of unfavorable points, and is applicable to common high-temperature martensitic steels such as P92 and P122 and similar materials.

[0018] The above-mentioned overall technical solution has a clear implementation path and controllable input. It does not rely on complex field coupling or a large number of difficult-to-obtain material parameters. Necessary coefficients can be obtained by looking up tables or empirical graphs, or they can be calibrated on-site using finite element method, which facilitates rapid implementation and application. Attached Figure Description

[0019] The technical solution and its beneficial effects will become apparent from the following detailed description of specific embodiments of this application, in conjunction with the accompanying drawings.

[0020] Figure 1 Flowchart of the creep remaining life assessment method provided in this application; Figure 2 A schematic diagram of the creep remaining life assessment device 10 provided in this application; Figure 3 A schematic diagram of the creep curve fitted for example P92 provided in this application; Figure 4 A schematic diagram of the creep curve fitted for the P122 example provided in this application.

[0021] Explanation of reference numerals in the attached figures: 10. Creep Remaining Life Assessment Device; 11. Data Acquisition Unit; 12. Fitting and Mapping Unit; 13. Stress Calculation Unit; 14. Parameter Transfer Unit; 15. Life Assessment Unit. Detailed Implementation

[0022] To make the objectives, technical solutions, and beneficial effects of this application clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates this application. It should be understood that the specific embodiments described in this specification are merely for explaining this application and are not intended to limit it.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "first," "second," "third," etc., are used only to distinguish objects and do not limit their quantity, order, or importance. The terms "including / contains / has," etc., are open-ended terms, indicating the presence of, but not limited to, the listed elements; the term "at least" should be understood as "one or more" or "one or more". The term "and / or" indicates any or all combinations in a parallel relationship. Unless otherwise specified, numerical ranges include endpoints. The term "based on" should be understood as "at least partially based on."

[0024] Furthermore, in the description of this application, the engineering term "high-temperature pressure-bearing header" refers to a collective cylindrical pressure-bearing component in a power plant boiler or similar system that bears high-temperature steam pressure; "main steam pipeline" refers to a main steam pipeline of the same batch as the header to be evaluated, made of the same material and from the same source, used to provide comparable creep test data and material parameters. "Same batch" is used to indicate the consistency of material source, smelting / heat treatment batch, etc., to improve the traceability of material properties and the consistency of evaluation criteria. When there is no ambiguity, it can be understood as "material data with the same material source, composition, and heat treatment process and inspected in the same batch". "Bridge" refers to the metal connection between adjacent openings on the header cylinder; "weakest bridge location" refers to the bridge location with the most unfavorable strength under the combined action of geometry and stress; "minimum bridge weakening coefficient" is a dimensionless coefficient reflecting the decrease in local pressure-bearing capacity caused by the opening of the bridge, which can be obtained by looking up geometric parameters in tables, empirical charts, and / or finite element calibration, and is used to make strength equivalent corrections to the nominal pressure conditions. "Nominal stress" refers to the average stress calculated using an idealized stress model and a reference section or membrane stress, excluding the amplification effect of local stress concentrations such as holes / notches. "Operating condition / operating condition data" refers to the set of operating and structural conditions used for life assessment, typically including at least material parameters, structural parameters (such as outer diameter and wall thickness), temperature parameters, steam pressure, and operating time. "Design condition" refers to the allowable temperature / pressure conditions given in the design documents. "Actual condition / self-condition" refers to the actual temperature / pressure conditions under which the equipment operates in the field. "Target condition" in this context may refer to the assessment condition at the header bridge to be assessed. Furthermore, in the description of this application, the mathematical terms "θ function / θ parameter / θ parameter set" refer to the parameterized curve model and its parameter set used to characterize the entire creep process of materials; "θ parameter extrapolation" and "transfer" refer to the process of reading or estimating the corresponding θ parameter values ​​at the operating condition variables (at least including stress and temperature) established based on the same batch of test data; to avoid ambiguity, this application does not limit the specific function form or fitting method. "Creep curve equation" refers to the parameterized relationship with time as the independent variable and creep strain as the dependent variable. The "linear damage accumulation rule" refers to the criterion of summing the cumulative damage value by taking the ratio of the actual duration of each segment of the material to the total life under that segment's operating conditions under multiple operating conditions. The ratio is used as the fractional life, and the summation is based on the additivity principle. When the cumulative damage value reaches the failure threshold (usually 1), it is considered to have reached the life criterion. "Temperature-Time Equivalent Parameter / Larsen-Miller Parameter (LMP)" refers to the time-temperature parameter method used for equivalent life conversion at different temperatures. The specific values ​​of material constants (such as C value) can be determined based on data from the same batch of materials. This application does not limit the specific logarithmic base and parameter fitting method. "Material parameters (P92 / P122, etc.)" and "Allowable stress" refer to the material grade and its allowable engineering stress at a given temperature, respectively. When industry standards or long-term service data lead to adjustments in allowable stress, the relevant material constants or parameter relationships can be updated without changing the meaning of the terms in this application.

[0025] "Parameter mapping relationship" refers to the functional or equivalent relationship between the θ parameter set and the operating condition variables (stress and / or temperature), used to determine parameter values ​​under the target operating condition; "fitting / identification / determination" all refer to the process of establishing the above relationship and / or creep curve based on experimental data, and unless otherwise specified, no specific algorithm or function form is limited.

[0026] In the description of this application, terms such as "module / unit / device / system / processor / storage medium / computer program" can be implemented by software, hardware, or a combination of both; terms such as "acquire / collect / read / receive / calculate / determine / output / generate" are used interchangeably without causing ambiguity, referring to routine data processing operations performed by the system / device / program. Those skilled in the art can reasonably understand the above terms based on the specific context and make equivalent substitutions for their specific implementations without departing from the spirit and scope of this application.

[0027] During the operation and in-service evaluation of high-temperature pressure headers in power plant boilers, the temperature and pressure fluctuations caused by start-up, shutdown, and deep adjustment can easily make the area near the openings, such as the perforation bridge, the most unfavorable local location. At the same time, it is difficult to directly sample and conduct creep tests on the header body in its in-service state. Engineering evaluation often relies on data from different batches or common materials and repeatedly establishes calculation calibers under different operating conditions. This results in long evaluation cycles, strong reliance on manual labor, and difficulty in achieving consistent results across operating conditions. Furthermore, there is insufficient uniform treatment of the local equivalent stress and temperature differences caused by the geometric weakening of the perforation bridge, which affects the stability of the simulation and the engineering credibility of the conclusions.

[0028] To address this, this application proposes a method and apparatus for assessing the remaining creep life of a high-temperature pressure-bearing header. Based on creep test data and header operating condition data from the same batch of materials as the header to be assessed, a parameter mapping relationship is established between the θ parameter set and operating condition variables. The weakest point of the pore bridge on the header is located, and a pore bridge weakening coefficient is introduced to calculate the internal pressure equivalent stress. The equivalent stress and temperature are then substituted into the parameter mapping to obtain the θ parameters under the target operating condition, thereby obtaining the creep curve of the header to be assessed. Without limiting specific formulas, the remaining life is obtained using a unified criterion time for the curve. If necessary, the Larssen-Miller parameter method is combined for temperature equivalence conversion, and the additive assessment of multiple operating conditions is achieved according to the linear damage accumulation rule.

[0029] Figure 1 A flowchart illustrating the creep remaining life assessment method provided in this application. Figure 1 As shown, the exemplary method includes the following steps: S1, acquiring the operating condition data of the header to be evaluated and the creep test data of the main steam pipeline in the same batch as the header to be evaluated; S2, fitting the creep curve of the main steam pipeline based on the creep test data, and establishing a parameter mapping relationship between the θ parameter set and the operating condition variables; S3, calculating the internal pressure equivalent stress at the weakest orifice bridge location of the header to be evaluated; S4, obtaining the θ parameters corresponding to the header to be evaluated based on the calculated internal pressure equivalent stress, the operating condition data of the header to be evaluated, and the parameter mapping relationship; S5, obtaining the creep curve equation under the operating condition of the header to be evaluated based on the θ parameters corresponding to the header to be evaluated; S6, calculating the remaining creep life of the header to be evaluated based on the creep curve equation under the operating condition of the header to be evaluated and the creep test data of the same batch; wherein, the operating condition data includes at least the material parameters, structural parameters, temperature parameters, steam pressure, and operating time of the header to be evaluated; the creep test data at least characterizes the creep of the main steam pipeline with stress, temperature, and operating time. In the above steps, the order of S2 and S3 is not limited.

[0030] Figure 2 A schematic diagram of the creep remaining life assessment device 10 provided in this application. Figure 2As shown, the exemplary device includes the following units: a data acquisition unit 11, used to acquire operating condition data of the header to be evaluated and creep test data of the main steam pipeline in the same batch as the header to be evaluated, wherein the operating condition data includes at least material parameters, structural parameters, temperature parameters, steam pressure and running time, and the creep test data at least characterizes the creep of the main steam pipeline with stress, temperature and running time; a fitting and mapping unit 12, used to fit the creep curve of the main steam pipeline under different operating conditions based on the creep test data output by the data acquisition unit 11, and construct the parameter mapping relationship between the θ parameter set and the operating condition variables; and a stress calculation unit 13, used to determine the location of the weakest hole bridge in the header to be evaluated and calculate the stress. The internal pressure equivalent stress at the location; parameter migration unit 14, used to substitute the internal pressure equivalent stress output by stress calculation unit 13 and temperature parameters output by data acquisition unit 11 into the parameter mapping relationship constructed by fitting and mapping unit 12, output the θ parameter corresponding to the working condition of the header to be evaluated, and generate the creep curve equation of the header to be evaluated; life evaluation unit 15, used to obtain the creep remaining life of the main steam pipeline under the working condition of the header to be evaluated according to the creep curve equation generated by parameter migration unit 14, and used to obtain the total life of the main steam pipeline under its own working condition according to the creep curve of the main steam pipeline, and used to calculate the creep remaining life of the header to be evaluated based on the running time of the main steam pipeline using the linear damage accumulation rule.

[0031] The following is combined with Figure 1 and Figure 2 Exemplary examples are provided to illustrate each step of the above exemplary embodiments in detail.

[0032] In step S1 above, the acquisition and organization of operating condition data and creep test data of the same batch of main steam pipelines are used to provide a unified data standard and traceable source for parameter identification, stress calculation, and life calculation in subsequent steps S2 to S6. Unless otherwise stated, temperature is in K or °C, pressure and stress are in MPa, and time is in h.

[0033] In the embodiments of this application, the operating condition data may cover the following: Equipment and material identification may include unit / boiler / header identification, location and orientation, commissioning date, material grade (e.g., P92, P122), heat treatment status, quality certificate number, and batch information (furnace number / batch number). Structural parameters include at least the header's cylinder geometry (outer diameter and inner diameter or outer diameter and wall thickness), nozzle opening parameters (e.g., hole diameter, hole spacing, hole arrangement, reinforcement type), and the geometry of the weakest hole bridge (minimum hole bridge width, hole bridge location and orientation). If necessary, the weld type and heat-affected zone range are recorded for the internal pressure equivalent stress calculation and the determination of the minimum hole bridge weakening coefficient φ in step S3. Operating parameters include design temperature and design pressure, actual operating temperature and pressure, start-up and shutdown statistics (number of start-ups and shutdowns, residence time at each load segment), accumulated operating time (cumulative hours), and recent periodic temperature and pressure fluctuation records for stress and temperature lookup and linear damage accumulation in steps S4 to S6.

[0034] In the embodiments of this application, the creep test data of the main steam pipeline in the same batch includes the following basic fields: temperature T, stress σ, time t, strain ε, and whether it has reached fracture. In addition, derived data may also be included, such as minimum steady-state creep rate, elongation after fracture, and reduction of area. The creep test should be conducted at multiple stress points under the same temperature, or at multiple temperatures and stresses using a gridded distribution of test points, to cover as much as possible the vicinity of the operating conditions of the header to be evaluated; each (T, σ) combination provides complete (ε-t) data for subsequent θ parameter identification and mapping relationship establishment.

[0035] In step S2 above, specifically, based on the creep test data of the same batch of main steam pipelines obtained in step S1, for each set of operating conditions (T, σ), the corresponding (ε-t) is fitted using a parameterized θ function method (the specific formula form is not limited). The θ parameter set for that operating condition is identified through conventional nonlinear least squares solving. Curves without an accelerated creep segment can have weak constraints applied to the final parameters or be fitted piecewise. The fitting results for each operating condition are summarized into a sample table {σ, T, θ}. i For each θ parameter, establish a parameter mapping relationship between "θ parameter - operating condition variable". The function form is not limited; monotonic or piecewise monotonic relationships (such as logarithmic, exponential, power exponential, etc.) can be used to ensure physical rationality and engineering usability. Simultaneously, record the applicable interval and boundary extrapolation strategy of the mapping. The mapping relationship can be output as an equation or a lookup table, with standardized units. To facilitate subsequent calls in step S4, save the mapping expression (or lookup table data), applicable interval, and necessary confidence intervals or dispersion for each θ parameter, ensuring that the stress definition used in the mapping is consistent with subsequent life assessment calls. Through the above fitting and mapping, step S4 can directly read the corresponding θ parameters at the operating condition of the container to be evaluated.

[0036] In the above-described exemplary creep remaining life assessment device, the fitting and mapping unit 12 fits the creep curve of the main steam pipeline based on the creep test data of the same batch of main steam pipelines obtained by the data acquisition unit 11, using the following fitting equation: .

[0037] In the above fitting equation, the set of θ parameters that can be established includes elements θ1, θ2, θ3, θ4, and θ5. θ1 and θ2 are used to characterize the fitting for the first creep stage, θ3 for the second creep stage, and θ4 and θ5 for the third creep stage. Typically, the first creep stage is the initial creep stage, where the creep rate gradually decreases; the second creep stage is the steady-state stage, where the creep rate is approximately constant; and the third creep stage is a three-stage acceleration stage, where creep accelerates until fracture. By fitting the creep curve with five θ parameters, the required degrees of freedom to characterize the three creep stages can be met, resulting in higher fitting accuracy. The above fitting equation is only an optional formula and is not intended to limit the scope of protection of the independent claims of this application.

[0038] In the above exemplary method, one specific implementation of step S3 is as follows: Obtain the minimum bridge weakening coefficient based on the geometry of the weakest bridge section. And the structural parameters and / or steam pressure are calculated based on the minimum hole bridge weakening coefficient. Perform equal strength correction. For example, according to the formula... =P(D h) / (2h× Calculate the equivalent stress of internal pressure. Where P is the steam pressure, which can be obtained in real time through the operation monitoring system of the header to be evaluated, or by referring to the operation record data provided by the power plant, ensuring the accuracy and timeliness of the data; D is the outer diameter of the header shell to be evaluated, which comes from the design drawings of the header to be evaluated. The data in the drawings must be carefully checked before conducting the life assessment to avoid calculation errors due to drawing errors; h is the shell thickness, which can be confirmed by referring to the design drawings and combining periodic non-destructive testing data to account for possible wall thinning during operation. Minimum bridge weakening coefficient. The value can be obtained by consulting relevant industry standards (such as design specifications for power plant boiler headers) or by conducting specialized tests. For common header structures, the value can generally be taken from the standard. However, for headers with special structures or modifications, the value needs to be re-determined through precise calculations or tests.

[0039] In step S5 above, specifically, the parameter migration unit 14 searches for the θ parameters corresponding to the temperature of the header to be evaluated collected by the data acquisition unit 11 and the internal pressure equivalent stress output by the stress calculation unit 13, based on the parameter mapping relationship between the θ parameter set and the operating condition variables. It then generates the creep curve equation of the main steam pipeline in the same batch under the operating condition of the header to be evaluated. The time origin of this equation is aligned to the current moment of the main steam pipeline to facilitate the subsequent calculation of linear damage accumulation and unused life under the target operating condition.

[0040] In the above exemplary creep remaining life assessment method, step S6 specifically includes the following steps: determining the total life t of the main steam pipeline under its own operating conditions based on the creep curve and creep test data of the main steam pipeline. r1 Based on the operating time Δt1 of the main steam pipeline and the total lifespan t of the main steam pipeline under its own operating conditions. r1 Determine the percentage of its consumed lifespan Δt1 / t under its own operating conditions. r1 The creep remaining life t' of the main steam pipeline under the operating conditions of the header to be evaluated is determined based on the creep curve equation. r2 The remaining creep life t' of the main steam pipeline under the operating conditions of the header to be evaluated. r2 The total lifespan t of the container under its own operating conditions and the container to be evaluated r2 The ratio t' r2 / t r2 The percentage of unused lifespan for materials with the same material properties under different operating conditions; based on the linear damage accumulation law, the percentage of used lifespan Δt1 / t is established. r1 The percentage of unconsumed lifespan t' r2 / t r2 Equations that sum to 1, i.e., Δt1 / t r1 + t' r2 / t r2 =1, to calculate the total lifespan t of the container under its own operating conditions. r2 Based on the operating time Δt2 of the container to be evaluated and the total lifespan t of the container under its own operating conditions... r2 Calculate the remaining creep life of the header to be evaluated.

[0041] In the above steps, since the origin of the creep curve equation is aligned to the current time of the main steam pipeline, the creep curve corresponding to this creep curve equation can be directly used as the remaining creep life t' of the main steam pipeline under the operating conditions of the header to be evaluated, based on the time corresponding to the inflection points of the second and third creep stages. r2 It should be understood that using this time point as a life criterion is only one option. The fracture point can also be used as a life criterion, as long as the life criterion in the above steps is the same.

[0042] In the above steps, the total lifespan t of the container under its own operating conditions can be further evaluated. r2 Temperature correction is performed, and the specific implementation process is as follows. If the actual temperature T of the container to be evaluated is... a Higher than the design temperature T b (Units are all in K), then we have: T a (C+logt) a )=T b (C+logt) b ), where t a t b Here, represents the creep life at the corresponding temperature, and C is a material constant (20 for P92 and P122). Since the actual operating conditions of the header under evaluation may differ from the design temperature, the above formula is often used to calculate the total life t of the header under evaluation under its own operating conditions. r2 As t b This is incorporated to correct the total lifetime at the actual temperature.

[0043] Based on the above-described exemplary creep remaining life assessment method and apparatus, this application also provides a calculation example for headers P92 and P122 in a power plant.

[0044] The following is an example of P92 calculation: Taking the four outlet headers of the power plant as an example, its basic parameters include: outer diameter of cylinder 559mm, cylinder wall thickness 135mm, steam pressure 27.46MPa, design temperature 605℃, and operating time 81846h. The total service life of the same batch of P92 main steam pipelines at 67.30MPa is 346846h.

[0045] Taking the minimum bridge span reduction coefficient φ=0.68 as an example, substituting it into the formula in step S3 above, we get σ=27.46×(559-135) / (2×135×0.68)=66.51MPa.

[0046] Based on the θ parameter and stress mapping relationship of the P92 pipeline (taking θ1=-3.35197+0.02405σ as an example, the other θ parameters are similar and will not be elaborated), the θ parameters at 66.51MPa are obtained (θ1=0.01768, θ2=0.00234, the other θ parameters will not be elaborated), and the following table is obtained.

[0047]

[0048] Table 1 Table 1 shows the θ parameters and stress mapping of P92 material within the boiler area under operating conditions of 605℃ and 66.51MPa.

[0049] Figure 3A schematic diagram of the creep curve fitting for the P92 example provided in this application is shown. The creep curve of the main steam pipeline is fitted based on the data in Table 1 above. (See table below for details.) Figure 3 As shown, based on the creep curve, the remaining creep life at 605℃ and 66.51MPa is approximately 278,000 hours (with the inflection point between the second and third creep stages as the corresponding lifetime criterion).

[0050] When the P92 main steam pipeline within the boiler area first serves for 81,846 hours at 605℃ and 67.30MPa, and then for 278,000 hours at 605℃ and 66.51MPa, its creep life ends. According to the linear damage accumulation rule in step S6 above, we have: 81846 / 346846+278000 / tr2=1, solving for tr2(605℃)=363874h. Then, according to the Larssen-Miller parameter method, after temperature correction, due to temperature fluctuations in the header to be evaluated, the actual service parameters are evaluated at 610℃ and 66.51MPa, resulting in 878×(20+lg363874)=883×(20+lgtr2), solving for tr2(610℃)=260741h. Finally, based on 260741-81846=178895h, the actual creep remaining life of the P92 header cylinder in this example is 178895 hours.

[0051] The following is an example of P122 calculation: Taking the four outlet headers of the power plant as an example, its basic parameters include: outer diameter of cylinder 559mm, cylinder wall thickness 126mm, steam pressure 27.46MPa, design temperature 605℃, and operating time 81846h. The total service life of the P122 main steam pipeline of the same batch at 61.74MPa is 329846h.

[0052] Based on the θ parameter and stress mapping relationship of pipe P122 (taking θ1=-0.87367+0.0031σ as an example, the other θ parameters are similar and will not be elaborated), the θ parameters at 72.77MPa are obtained (θ1=0.2249, θ2=0.6079, the other θ parameters will not be elaborated), and the following table is obtained.

[0053]

[0054] Table 2 Table 2 shows the θ parameters and stress mapping of P122 material within the boiler area under operating conditions of 605℃ and 72.77MPa.

[0055] Figure 4 A schematic diagram of the creep curve fitting for the P122 example provided in this application is shown. The creep curve of the main steam pipeline is fitted based on the data in Table 2 above. Figure 4As shown, based on the creep curve, the remaining creep life at 605℃ and 72.77MPa is approximately 104,000 hours (with the inflection point between the second and third creep stages as the corresponding lifetime criterion).

[0056] When the P122 main steam pipeline within the boiler area first serves for 81,846 hours at 605℃ and 61.74MPa, and then for 104,000 hours at 605℃ and 72.77MPa, its creep life ends. According to the linear damage accumulation rule in step S6 above, we have: 81846 / 329846 + 104000 / tr2 = 1, solving for tr2 (605℃) = 138297h. Then, according to the Larssen-Miller parameter method, after temperature correction, due to temperature fluctuations in the header to be evaluated, the actual service parameters are evaluated at 610℃ and 72.77MPa, resulting in 878 × (20 + lg138297) = 883 × (20 + lgtr2), solving for tr2 (610℃) = 99643h. Finally, based on 99643-81846=17797h, the actual creep remaining life of the P122 header cylinder in this example is 17797 hours.

[0057] Based on the above exemplary embodiments, an update step can be added to the creep remaining life assessment method: when a decrease in the allowable stress of the material of the header to be assessed is detected, or when newly added creep test data from the same batch of main steam pipelines is introduced, the operating condition data of the header to be assessed is updated, and the parameter mapping relationship is incrementally updated. Correspondingly, a dynamic update unit is added to the creep remaining life assessment device to detect a decrease in the allowable stress of the material of the header to be assessed, or the introduction of newly added creep test data from the same batch of main steam pipelines, and to update the operating condition data and the parameter mapping relationship incrementally.

[0058] In summary, the creep remaining life assessment method and apparatus for high-temperature pressure-bearing headers proposed in this application uses creep test data of the main steam pipeline from the same batch as the header to be assessed as the calibration source. First, the test curve is fitted and a parameter mapping between the θ parameter set and the operating condition variables is established. The internal pressure equivalent stress is calculated at the weakest point of the bridge on the structural side. The equivalent stress and temperature are substituted into the parameter mapping relationship to obtain the θ parameters under the target operating condition, and the creep curve under the target operating condition is generated. Under the condition that the time origin is aligned with the current moment, a unified criterion is used to directly read the remaining life. If necessary, the calculated life can be corrected for temperature differences, and the multi-condition working segments can be segmented and evaluated according to linear damage accumulation. The apparatus implements the above process by units such as data acquisition, fitting and mapping, stress calculation, parameter migration and life assessment, and supports dynamic updating of material parameters. The above technical solution ensures material consistency and traceability of results without the need to sample the container body; it reduces the introduced equivalent stress by using a perforated bridge to accurately reflect the local load-bearing level; it forms a unified lifespan caliber and stable and comparable evaluation results under multiple temperature and operating conditions; it achieves a clear path, controllable input, and easy and rapid implementation, and is applicable to in-service container lifespan assessment and maintenance decision support for materials such as P92 and P122.

[0059] The above embodiments are provided only to help understand the methods, structures, and core ideas of this application. Those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A method for assessing the remaining creep life of a high-temperature pressure-bearing header, characterized in that, include: Obtain the operating condition data of the header to be evaluated and the creep test data of the main steam pipeline in the same batch as the header to be evaluated; Based on the creep test data, the creep curve of the main steam pipeline is fitted, and the parameter mapping relationship between the θ parameter set and the operating condition variables is established, as well as the internal pressure equivalent stress at the weakest hole bridge position of the header to be evaluated is calculated. The θ parameter corresponding to the header to be evaluated is obtained based on the internal pressure equivalent stress, the working condition data and the parameter mapping relationship; The creep curve equation of the header under the working condition is obtained based on the θ parameter corresponding to the header to be evaluated. The creep remaining life of the container to be evaluated is calculated based on the creep curve equation and the creep test data. The operating data includes at least the material parameters, structural parameters, temperature parameters, steam pressure, and operating time of the container to be evaluated. The creep test data at least characterizes the creep of the main steam pipeline as a function of stress, temperature and operating time.

2. The method for assessing the remaining creep life of a high-temperature pressure-bearing header as described in claim 1, characterized in that, The calculation of the internal pressure equivalent stress includes: The minimum bridge weakening coefficient is obtained based on the geometry of the weakest bridge location; The structural parameters and / or steam pressure are corrected to the same strength according to the minimum hole bridge weakening coefficient; The internal pressure equivalent stress is calculated based on the structural parameters and / or steam pressure, which incorporate the minimum hole bridge weakening coefficient. The structural parameters include at least the outer diameter of the cylinder and the thickness of the cylinder wall of the header to be evaluated.

3. The method for assessing the remaining creep life of a high-temperature pressure-bearing header as described in claim 1, characterized in that, The establishment of the parameter mapping relationship includes: Based on the creep test data of the main steam pipeline under different temperatures and stresses, the creep curve of the main steam pipeline was fitted, and the fitting equation was obtained. The θ parameter values ​​under different temperatures and stresses are determined based on the fitted equation.

4. The method for assessing the remaining creep life of a high-temperature pressure-bearing header as described in claim 3, characterized in that, The θ parameter set includes at least θ1, θ2, θ3, θ4 and θ5, where θ1 and θ2 are used to characterize the fit to the first creep stage, θ3 is used to characterize the fit to the second creep stage, and θ4 and θ5 are used to characterize the fit to the third creep stage.

5. The method for assessing the remaining creep life of a high-temperature pressure-bearing header as described in claim 1, characterized in that, The calculation of the remaining creep lifetime includes: The total lifespan of the main steam pipeline under its own operating conditions is determined based on the creep curve of the main steam pipeline and the creep test data. The percentage of the main steam pipeline's lifespan consumed under its own operating conditions is determined based on the pipeline's operating time and its total lifespan under its own operating conditions. The creep remaining life of the main steam pipeline under the operating conditions of the header to be evaluated is determined based on the creep curve equation. The ratio of the remaining creep life of the main steam pipeline under the working conditions of the header to be evaluated to the total life of the header to be evaluated under its own working conditions is used as the proportion of the unconsumed life of materials with the same material parameters under different working conditions. Based on the linear damage accumulation rule, an equation is established in which the sum of the consumed life percentage and the unconsumed life percentage is 1, so as to calculate the total life of the container to be evaluated under its own working conditions. The creep remaining life of the container to be evaluated is calculated based on the operating time of the container to be evaluated and the total life of the container to be evaluated under its own operating conditions.

6. The method for assessing the remaining creep life of a high-temperature pressure-bearing header as described in claim 5, characterized in that, The remaining creep life of the main steam pipeline under the operating condition of the header to be evaluated is determined by the inflection points of the second creep stage and the third creep stage of the creep curve equation, wherein the time axis of the creep curve equation takes the moment when the creep curve of the main steam pipeline migrates to the operating condition of the header to be evaluated as the origin.

7. The method for assessing the remaining creep life of a high-temperature pressure-bearing header as described in claim 5, characterized in that, The calculation of the remaining creep lifetime also includes: Based on the parameter mapping relationship, the total lifespan of the container to be evaluated under the design conditions is obtained; The Larsen-Miller parameter method is used to perform temperature correction on the total life of the container under its own operating conditions based on the total life of the container under design conditions and the material parameters. The calculation of the creep remaining life is based on the modified total life of the header to be evaluated under its own operating conditions.

8. The method for assessing the remaining creep life of a high-temperature pressure-bearing header as described in any one of claims 1-7, characterized in that, Also includes: When a decrease in the allowable stress of the material of the header to be evaluated is detected, or when creep test data of newly added main steam pipelines from the same batch are connected, the operating condition data of the header to be evaluated is updated, and the parameter mapping relationship is incrementally updated.

9. A device for assessing the remaining creep life of a high-temperature pressure-bearing header, characterized in that, include: The data acquisition unit is used to acquire the operating condition data of the header to be evaluated and the creep test data of the main steam pipeline in the same batch as the header to be evaluated. The operating condition data includes at least material parameters, structural parameters, temperature parameters, steam pressure and running time. The creep test data at least characterizes the creep of the main steam pipeline with stress, temperature and running time. The fitting and mapping unit is used to fit the creep curves of the main steam pipeline under different operating conditions based on the creep test data, and to construct the parameter mapping relationship between the θ parameter set and the operating condition variables. The stress calculation unit is used to determine the location of the weakest hole bridge in the header to be evaluated and to calculate the internal pressure equivalent stress at that location. The parameter migration unit is used to substitute the internal pressure equivalent stress and the temperature parameter into the parameter mapping relationship to obtain the θ parameter corresponding to the working condition of the header to be evaluated, and to generate the creep curve equation of the header to be evaluated. as well as The life assessment unit is used to obtain the remaining creep life of the main steam pipeline under the operating conditions of the header to be assessed according to the creep curve equation, and to obtain the total life of the main steam pipeline under its own operating conditions according to the creep curve of the main steam pipeline, and to calculate the remaining creep life of the header to be assessed based on the operating time of the main steam pipeline using the linear damage accumulation rule.

10. The creep remaining life assessment device for high-temperature pressure-bearing headers as described in claim 9, characterized in that, Also includes: The dynamic update unit is used to detect the allowable stress reduction of the material of the header to be evaluated or to access the creep test data of the newly added main steam pipeline of the same batch, and to update the operating condition data and incrementally update the parameter mapping relationship.

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