Online prediction method for the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress.

Abstract

This invention belongs to the field of life prediction technology, specifically relating to an online prediction method for the remaining life (RUL) of a chlorine-rich high-temperature environment coupled with stress in a system. The method includes the following steps: acquiring linear polarization data measured by electrochemical methods; calculating the corrosion current density using the linear polarization method and converting the instantaneous thickness loss rate and cumulative thickness loss according to Faraday's law; mapping the cumulative thickness loss to the evolution of the load-bearing section, thereby obtaining the stress evolving over time; determining the instantaneous creep strain rate; describing the damage evolution; determining the failure time based on the minimum safe thickness and / or damage threshold, and outputting the RUL and early warning; and introducing a risk index and dynamic threshold for post-prediction risk control. This invention enables the measurement of thermally stress-induced high-temperature ash corrosion through multi-source fusion and introduces a risk index and damage tolerance criteria to achieve early warning, significantly improving the accuracy and real-time performance of life assessment under complex operating conditions.

Description

Technical Field

[0001] This invention belongs to the field of lifetime prediction technology, specifically relating to an online method for predicting the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system. Background Technology

[0002] Under chlorine-rich high-temperature conditions, metal / alloy components are prone to selective oxidation, chlorination-oxidation cycles, and oxide scale peeling; simultaneously, significant creep occurs under long-term constant loads. Corrosion reduces the effective load-bearing cross-section, increasing effective stress and thus significantly accelerating creep and damage evolution. Existing assessments often separate corrosion and creep, and lack real-time online coupled assessment and early warning methods.

[0003] In the harsh environment of high-temperature, chlorine-rich conditions, metal and alloy components face multiple threats of damage. Selective oxidation causes more reactive elements in the alloy to preferentially combine with oxygen, disrupting the original compositional homogeneity. For example, chromium alloys easily form chromium oxides in this environment, leading to a decrease in matrix strength. The chlorination-oxidation cycle is even more complex. Chlorine first reacts with the metal to form volatile chlorides, which then react with oxygen to regenerate oxides and release chlorine, forming a cycle of corrosion, volatilization, and re-oxidation that continuously erodes the interior of the component. Oxide scale peeling further exacerbates the damage. The oxide protective layer formed at high temperatures is prone to cracking and peeling off under temperature fluctuations or external forces due to the difference in thermal expansion coefficients between the oxide layer and the matrix, exposing the fresh metal surface to the corrosive environment. At the same time, components also undergo significant creep under long-term constant loads, meaning that the material slowly undergoes plastic deformation under high temperature and continuous stress. Over time, the deformation accumulates, gradually weakening the structural stability of the component.

[0004] Corrosion causes a continuous reduction in the effective load-bearing cross-section of metal components, leading to an increase in the effective stress borne by the component under constant load. According to creep theory, increased stress significantly accelerates the creep process, making internal cracks in the material more likely to initiate and propagate, thereby accelerating the overall damage evolution. This creates a vicious cycle where corrosion exacerbates stress, stress accelerates creep, and creep amplifies damage, drastically shortening the service life of the component.

[0005] However, current damage assessment methods for such components have significant shortcomings. Existing methods often treat corrosion and creep as independent processes and assess them separately, ignoring their coupling relationship. This leads to discrepancies between the assessment results and the actual damage, making it difficult to accurately reflect the true safety status of the components. More importantly, there is a lack of technical means to monitor the coupling effect of corrosion and creep in real time, making it impossible to capture the dynamic evolution of component damage in a timely manner and providing timely early warnings for equipment operation and maintenance. This poses a serious safety hazard in fields such as chemical engineering and energy that rely on equipment in high-temperature, chlorine-rich environments. Future research urgently needs to develop coupled assessment technologies and online early warning systems to provide more reliable guarantees for the safe service of metal components.

[0006] Existing patents, such as the Chinese invention patent application with publication number CN120671513A entitled "A Method for Predicting Wear of Four-Tube Boiler Tubes Based on Big Data Algorithms," disclose a method for predicting wear of four-tube boiler tubes based on big data algorithms, comprising the following steps: constructing a three-dimensional digital model of the four boiler tubes and spatially binding design parameters, historical operation and maintenance records, and real-time monitoring data to form a multi-source associated database; constructing a tube wall temperature prediction model using a heat conduction mechanism model and a neural network algorithm, and outputting the wall temperature distribution data of the entire heated surface; inputting this data into a wear, creep, and corrosion model, and combining it with historical tube rupture cases to calculate the remaining life and generate a life map; using a leakage risk probability algorithm and a coupled risk coefficient model to generate a three-dimensional risk thermal distribution map; and overlaying the thermal map onto the three-dimensional digital model and displaying the risk level based on color gradient mapping.

[0007] The life prediction model in the aforementioned patent is based on wall temperature distribution data. Its three aspects—wear prediction, high-temperature creep model, and corrosion rate prediction—are all obtained indirectly through temperature data input, querying related databases, or using temperature-related kinetic models. The entire process does not involve direct measurement of the corrosion rate. The patent uses the Larson-Miller relationship, which converts temperature-time to fracture data into a time-temperature parameter for creep fracture life assessment and extrapolation. It does not delve into the relationship between stress and corrosion, focusing primarily on temperature. The real-time monitoring dataset in the patent uses an acoustic emission monitoring device for corrosion rate measurement. Acoustic emission monitoring devices are difficult to quantify corrosion rates due to the lack of universal conversion; they are highly susceptible to variations in material, stress, damage mechanism, and propagation path, requiring extensive calibration. Furthermore, mechanical vibration, flow turbulence, cavitation, particle erosion, leakage, and valve operation all generate sound, necessitating complex filtering and feature extraction in acoustic emission monitoring, leading to a high risk of false alarms / missed alarms in the field. Summary of the Invention

[0008] To address the aforementioned problems in existing technologies, this invention provides an online prediction method for the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system.

[0009] To achieve the above effects, the technical solution adopted by the present invention is as follows: A method for online prediction of the remaining lifetime of a system coupled with stress in a chlorine-rich high-temperature environment includes the following steps: Step S1: Collect linear polarization data for electrochemical measurements; Step S2: Calculate the corrosion current density using the linear polarization method, and convert the instantaneous thickness loss rate and cumulative thickness loss c(t) according to Faraday's law; Step S3: Map the cumulative thickness loss c(t) to the evolution of the bearing section A(t), and then obtain the stress that evolves over time; Step S4: Use the Norton-Bailey creep relation to determine the instantaneous creep strain rate; Step S5: Describe the damage evolution using the Kachanov-Rabotnoy model; Step S6, based on minimum safety thickness h min When the damage threshold determination fails, output RUL and warning; Step S7: Introduce risk index and dynamic threshold for risk control after prediction.

[0010] Furthermore, in step S1, the linear polarization data measured by electrochemical methods is the polarization resistance. .

[0011] Furthermore, the corrosion rate is calculated. :

[0012] In the formula Here, t represents time, and A represents the effective corrosion area. It is the density of the metal; in , in the formula is the Faraday constant, M is the molar mass of the metal used, and n is the number of electrons transferred.

[0013] Furthermore, in step S2, the specific calculation process for the corrosion current density is as follows: First, the linear polarization resistance that changes over time is obtained. The polarization resistance at each moment :

[0014] in, It is the change in voltage. It is the change in current; Then calculate the corrosion current density :

[0015] In the formula, B is the Stern–Geary constant, and the corrosion rate is... That is, the instantaneous thickness loss rate Then the cumulative thickness loss for:

[0016] Furthermore, B is determined by the Tafel slope. , calculate,

[0017] In the formula The Tafel slope is the anode slope. The cathode Tafel slope; Furthermore, in step S3, the effective thickness at time t for:

[0018] In the formula This is the initial thickness; For any small positive number; Material width at time t for:

[0019] In the above formula This is the initial width; bearing section at time t for:

[0020] Furthermore, the degradation coefficient for:

[0021] The value range is 0 < ≤1; For damage variables in Kachanov-Rabotnov; This is the damage intensity reduction factor. Under a constant load F, the actual stress for:

[0022] In the formula The applied force is set by the testing machine / loading device, and the effective stress is... for:

[0023] In the formula ∈(0,1).

[0024] Furthermore, considering the localized stress concentration caused by pitting corrosion, the effective stress considering pitting corrosion is obtained. for:

[0025] in It is the effective gap coefficient, and ≥1, where To account for the actual stress in the presence of pitting.

[0026] Furthermore, Due to pure elastic geometric effects Notch sensitivity calibration of materials:

[0027] In the formula , ∈[0,1], Because the pit is deep, The radius of curvature is the pit opening / bottom.

[0028] Furthermore, in step S4, the instantaneous creep strain rate under the current temperature and stress... for:

[0029] Considering the instantaneous creep strain rate of pitting corrosion for:

[0030] In the formula , For material constants, The equivalent activation energy is given by R, where R is the gas constant. Absolute temperature Let RT be the product of RT and RT at time t.

[0031] Furthermore, a coupled damage model is constructed to provide a damage index for early warning. for:

[0032] in the formula , , These are weighting coefficients. This represents the power spectral density characteristics of electrochemical noise.

[0033] Furthermore, a failure determination is triggered by a geometric limit or a comprehensive damage threshold.

[0034]

[0035] In the formula For minimum safe thickness, Alarm thresholds are determined based on experience or historical data. This refers to a failure event.

[0036] Furthermore, in step S5, the Kachanov-Rabotnov creep damage is as follows:

[0037]

[0038] Bundle , Substitute the Kachanov-Rabotnov equations and integrate to obtain the damage variable. ∈[0,1), using damage variables →1 Determine the time of failure , , , , is a material constant.

[0039] Furthermore, in step S6, the remaining lifetime is set as the failure criterion. ,exist

[0040]

[0041] Refers to the future time The damage index is a critical threshold; failure is determined when the threshold is reached or exceeded. Defined as Then the comparison and judgment of damage indicators is transformed into the direct output of failure events. The above formula can be simplified to:

[0042]

[0043] In the formula The moment when any threshold is first met. As a future time variable, used in a set Iterate through all possible future moments. For at any time The event that causes failure, where T represents the current time. Let be the remaining lifetime at time t. The moment when any threshold is first met, i.e., the failure moment.

[0044] Furthermore, in step 7, the risk index for:

[0045] , , The weighting coefficients are selected based on the validation set. Determined through logistic regression / Bayesian optimization based on historical events; Dynamic threshold Adaptive to different operating conditions

[0046]

[0047] , ,: Historical baseline mean and standard deviation; Quantitative coefficients; This is a working condition correction factor; The higher the number, the higher the risk. Used to trigger an alert; Reflecting temperature With atmospheric components The impact on the threshold.

[0048] The technical effects achieved by this invention are as follows: This invention discloses an online prediction method and system for residual lifetime (RUL) in chlorine-rich high-temperature environments coupled with creep stress. This method is based on polarization resistance (LPR) corrosion rates obtained from online electrochemical monitoring and integrates high-temperature strain data from the same point and temperature. By establishing a state-space model of corrosion-creep coupled damage variables and degradation rates, it achieves a joint characterization of material cross-sectional loss, mechanical property degradation, and creep damage, predicting the residual lifetime of components and providing certain maintenance suggestions. Unlike existing methods that only monitor weight loss or a single electrochemical rate, this invention achieves the measurement of thermal stress-induced high-temperature ash corrosion through multi-source fusion and introduces risk indices and damage tolerance criteria to achieve early warning, significantly improving the accuracy and real-time performance of lifetime assessment under complex operating conditions; it can seamlessly integrate with the applicant's existing online monitoring devices.

[0049] This application uses an electrochemical method for online measurement, which can actually measure the current corrosion rate, rather than being a deduction or a model judgment.

[0050] This application uses the Norton-Bailey creep relation, which differs from the creep failure relation used in this application. The Norton-Bailey relation provides a constitutive law for strain (or steady-state strain rate)-stress-time-temperature, used for calculating the strain evolution throughout the entire process. This application employs an online electrochemical measurement method, which can directly provide... Quantitative analysis is more direct using parameters such as Rp, membrane resistance / capacitance, etc. Attached Figure Description

[0051] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0053] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0054] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0055] In the description of this application, it should be noted that the terms "upper," "vertical," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0056] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0057] Example 1 like Figure 1 As shown, an online prediction method for the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system includes the following steps: Step S1: Acquire linear polarization (LPR) data from electrochemical measurements; Step S2: Calculate the corrosion current density using the linear polarization method, and convert the instantaneous thickness loss rate and cumulative thickness loss c(t) according to Faraday's law; Step S3: Map the cumulative thickness loss c(t) to the evolution of the bearing section A(t), and then obtain the stress that evolves over time; Step S4: Use the Norton-Bailey creep relation to determine the instantaneous creep strain rate; Step S5: Describe the damage evolution using the Kachanov-Rabotnoy model; Step S6, based on minimum safety thickness h min When the damage threshold determination fails, output RUL and warning; Step S7: Introduce risk index and dynamic threshold for risk control after prediction.

[0058] This invention discloses an online prediction method and system for residual lifetime (RUL) in chlorine-rich high-temperature environments coupled with creep stress. This method is based on polarization resistance (LPR) corrosion rates obtained from online electrochemical monitoring and integrates high-temperature strain data from the same point and temperature. By establishing a state-space model of corrosion-creep coupled damage variables and degradation rates, it achieves a joint characterization of material cross-sectional loss, mechanical property degradation, and creep damage, predicting the residual lifetime of components and providing certain maintenance suggestions. Unlike existing methods that only monitor weight loss or a single electrochemical rate, this invention achieves the measurement of thermal stress-induced high-temperature ash corrosion through multi-source fusion and introduces risk indices and damage tolerance criteria to achieve early warning, significantly improving the accuracy and real-time performance of lifetime assessment under complex operating conditions; it can seamlessly integrate with the applicant's existing online monitoring devices.

[0059] Example 2 like Figure 1 As shown, an online prediction method for the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system includes the following steps: Step S1: Acquire linear polarization (LPR) data from electrochemical measurements; Step S2: Calculate the corrosion current density using the linear polarization method, and convert the instantaneous thickness loss rate and cumulative thickness loss c(t) according to Faraday's law; Step S3: Map the cumulative thickness loss c(t) to the evolution of the bearing section A(t), and then obtain the stress that evolves over time; Step S4: Use the Norton-Bailey creep relation to determine the instantaneous creep strain rate; Step S5: Describe the damage evolution using the Kachanov-Rabotnoy model; Step S6, based on minimum safety thickness h minWhen the damage threshold determination fails, output RUL and warning; Step S7: Introduce risk index and dynamic threshold for risk control after prediction.

[0060] In step S1, the linear polarization method (LPR) data measured by electrochemical methods is the polarization resistance. ,pass The corrosion rate was calculated. .

[0061] Calculate corrosion rate :

[0062] In the formula Here, t represents time, and A represents the effective corrosion area. It is the density of the metal; in , in the formula Let n be the Faraday constant, M be the molar mass of the metal used, and n be the number of electrons transferred. Taking Fe as an example, M is 56 mol / kg. Fe 2+ n is 2.

[0063] In step S2, the specific calculation process for the corrosion current density is as follows: First, the linear polarization resistance that changes over time is obtained. Since the polarization resistance changes over time, the polarization resistance at each moment... different;

[0064] in, It is the change in voltage. It is the change in current; the linear polarization method involves applying a small voltage to the system and then measuring the change in current. The ratio of the two is the polarization resistance.

[0065] Then calculate the corrosion current density :

[0066] In the formula, B is the Stern–Geary constant, and the corrosion rate is... That is, the instantaneous thickness loss rate Then the cumulative thickness loss for:

[0067] B is determined by the slope of Tafel. , Computational or experimental fitting,

[0068] In the formula The Tafel slope is the anode slope. The cathode Tafel slope is determined by the Tafel polarization experiment. In step S3, corrosion thinning is converted into a change in cross-sectional area over time, and the effective thickness at time t is... for:

[0069] In the formula Initial thickness (mm); For any small positive number (such as 10) -6 mm), to prevent numerical algorithms from dividing by zero or producing negative thickness; Material width at time t for:

[0070] In the above formula Initial width (mm); The load-bearing cross section (mm²) at time t. for:

[0071] Degradation coefficient for:

[0072] The value range is 0 < ≤1; =1: Indicates that the material retains its initial load-bearing capacity (no degradation); <1: Indicates a decrease (degradation) in load-bearing capacity due to high temperature, corrosion, tissue evolution, etc. For the damage variable in Kachanov-Rabotnov (KR); This is the damage intensity reduction factor (dimensionless).

[0073] True stress and effective stress (dead load tension) Under a constant load F, corrosion causes A(t) to decrease, and the true stress... It will increase over time, true stress for:

[0074] In the formula The loading force (N) is set and recorded by the testing machine / loading device; True stress (MPa) is recommended for creep constitutive models, converting material mechanical degradation into equivalent stress; the more the material deteriorates, the higher the stress level. The smaller, The larger the effective stress, the greater the effective stress. for:

[0075] In the formula ∈(0,1]: Intensity degradation coefficient, 1 indicates no degradation, the smaller the value, the weaker the degradation. Considering the localized stress concentration caused by pitting corrosion, the effective stress considering pitting corrosion is obtained. for:

[0076] in This is the effective notch coefficient (the amplification effect of pitting / notch), and ≥1, multiplied by the effective gap coefficient if necessary. Make localized conservatives, among which To account for the actual stress in the presence of pitting, these two formulas for calculating effective stress are essentially the same, except that one does not consider pitting corrosion while the other does.

[0077] Often caused by purely elastic geometric effects Notch sensitivity calibration of materials:

[0078] In the formula , ∈[0,1] is calibrated by comparative experiments. A single surface pitting is approximated as a U-shaped groove / elliptical notch; a commonly used engineering approximation under uniaxial tension is: , The pit depth (mm) can be measured by metallography / white light interference / confocal microscopy or a needle gauge; The radius of curvature (mm) of the pit opening / bottom can be obtained by fitting the contour curve.

[0079] In step S4, the instantaneous creep strain rate under the current temperature and stress is... for:

[0080] Considering the instantaneous creep strain rate of pitting corrosion for:

[0081] In the formula , For material constants, R is the equivalent activation energy (J / mol) and R is the gas constant. , The product of the two is the absolute temperature. The dimension of energy is per mole. Let RT be the product of RT and RT at time t.

[0082] Bundle , Substituting Norton–Bailey, we get This can be used to: directly integrate the cumulative creep strain; or as a rate term in the coupled damage index. Its physical meaning is: the higher the temperature, the greater the effective stress, and the faster the creep.

[0083] A coupled damage model is constructed, in which creep accumulation, corrosion accumulation, and local activation (EN) are weighted and integrated into a 0-1 index, which serves as the damage index for early warning. for:

[0084] in the formula , , The weighting coefficients (dimensionless) are set / fitted according to the mechanism and data quality you want to emphasize.

[0085] This represents the electrochemical noise power spectral density characteristics (reflecting film rupture / local pitting activity). This is a dimensionless damage index (between 0 and 1), used for early warning. Its physical meaning can be understood as: when... The system is in a healthy state; when : Approaching the failure threshold (e.g., pitting / cracking).

[0086] Failure / downtime criteria; providing geometric limits or comprehensive damage thresholds to trigger failure determination.

[0087]

[0088] In the formula Minimum safe thickness (as specified in the standard / design). Alarm thresholds are determined based on experience or historical data (e.g., 0.6–0.8). This refers to a failure event.

[0089] In step S5, the Kachanov-Rabotnov creep damage (mechanistic type) is as follows: Classical creep damage evolution; ω→1 approaches failure.

[0090]

[0091] Bundle , Substitute the Kachanov-Rabotnov equations and integrate to obtain the damage variable. ∈[0,1), using damage variables →1 (or threshold) to determine the failure time , , , , These are material constants and require experimental fitting (constant temperature and constant load / graded load data can be used).

[0092] In step S6, the remaining lifetime The minimum safe thickness in this step is based on the calculation in step S4, and the purpose is to... Determine the failure event (represented by a Boolean value), and then use... This formula. Step S5 mentions damage threshold determination; the damage model determination method uses the model for calculating D(t) established in step S4. Therefore, it is related to the damage index D(t) in step S4, and the failure criterion is set as... ,exist

[0093]

[0094] Refers to the future time The damage index is dimensionless and can be calculated from S4. This is a critical threshold (dimensionless); reaching or exceeding it determines failure. Defined as Then the comparison and judgment of damage indicators is transformed into the direct output of failure events. The above formula can be simplified to:

[0095]

[0096] In the formula The moment when any threshold is first met. As a future time variable, used in a set Iterate through all possible future moments. For at any time The event that causes failure (which can be represented by a Boolean value), where T represents the current moment, i.e., now, and RUL stands for RUL. Remaining Useful Life It means remaining lifespan. Let Inf be the remaining lifetime at time t. Inf stands for infimum, meaning the infimum or minimum lower bound. In the formula, it takes all values ​​that satisfy the condition. The earliest minimum value in the middle; The moment when any threshold is first met is the failure moment. If failure has already occurred at this moment, then... If it never expires within the observation window, theoretically... .

[0097] In step 7, a risk index and a dynamic threshold are used to score and determine the current risk in real time; the higher the value, the higher the risk. for:

[0098] , , The weighted coefficients (which can be normalized to a sum of 1) are selected from the validation set. Determining the outcome through logistic regression / Bayesian optimization based on historical events (hazards / maintenance). Dynamic threshold It adapts to different operating conditions; the threshold value changes as temperature, atmosphere, or load changes.

[0099]

[0100]

[0101] , ,: Historical baseline mean and standard deviation; This is the quantile coefficient (e.g., 1.96 corresponds to 95%). This is a working condition correction factor (e.g., the threshold is lowered slightly at high temperatures for a more conservative approach). The higher the number, the higher the risk. Used to trigger an alert; Reflecting temperature With atmospheric components The influence of factors such as O2 / CO2 / HCl / Cl2 on the threshold. If the environment is more severe (high temperature, chlorine-rich) → The threshold is lowered for a more conservative approach; if the environment is relatively mild → The threshold was raised to reduce false alarms.

[0102] Step S6 has given the RUL, but in order to perform risk control during operation, step S7, "Risk Index and Dynamic Threshold," is still required: This involves setting the current corrosion intensity (…). ), creep rate ( ) and damage accumulation ( The results are combined into a real-time score RI(t) and compared with a threshold that adapts to different operating conditions. ;When RI(t)≥ Immediately triggering a yellow / red alert and providing suggestions for actions such as cooling, load reduction, and dust removal. Step S7 can provide early warnings for short-term anomalies such as temperature surges, sudden increases in chlorine richness, or pitting activation, maintaining consistent alarm standards across different temperatures / atmospheres / loads, reducing false alarms and missed alarms, and converting continuous diagnostic results into actionable controls; it also serves as a second layer of protection for RUL calculations, preventing risk accumulation from causing a sudden drop in lifespan assessment later. Therefore, step S6 focuses on lifespan planning, while step S7 focuses on online safety and operational decision-making, and the two complement each other.

Claims

1. A method for online prediction of the remaining lifetime of a system coupled with a chlorine-rich high-temperature environment and stress, characterized in that, Includes the following steps: Step S1: Collect linear polarization data for electrochemical measurements; Step S2: Calculate the corrosion current density using the linear polarization method, and convert the instantaneous thickness loss rate and cumulative thickness loss c(t) according to Faraday's law; Step S3: Map the cumulative thickness loss c(t) to the evolution of the bearing section A(t), and then obtain the stress that evolves over time; Step S4: Use the Norton-Bailey creep relation to determine the instantaneous creep strain rate; Step S5: Describe the damage evolution using the Kachanov-Rabotnoy model; Step S6, based on minimum safety thickness h min When the damage threshold determination fails, output RUL and warning; Step S7: Introduce risk index and dynamic threshold for risk control after prediction.

2. The method for online prediction of the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system according to claim 1, characterized in that, In step S1, the linear polarization data measured by electrochemical methods is the polarization resistance. ; Calculate corrosion rate : In the formula Here, t represents time, and A represents the effective corrosion area. It is the density of the metal; in , in the formula is the Faraday constant, M is the molar mass of the metal used, and n is the number of electrons transferred.

3. The method for online prediction of the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system according to claim 1, characterized in that, In step S2, the specific calculation process for the corrosion current density is as follows: First, the linear polarization resistance that changes over time is obtained. The polarization resistance at each moment : in, It is the change in voltage. It is the change in current; Then calculate the corrosion current density : In the formula, B is the Stern–Geary constant, and the corrosion rate is... That is, the instantaneous thickness loss rate Then the cumulative thickness loss for: The B is determined by the Tafel slope. , calculate, In the formula The Tafel slope is the anode slope. The cathode Tafel slope.

4. The method for online prediction of the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system according to claim 1, characterized in that, In step S3, the effective thickness at time t for: In the formula This is the initial thickness; For any small positive number; Material width at time t for: In the above formula This is the initial width; bearing section at time t for: Degradation coefficient for: The value range is 0 < ≤1; For damage variables in Kachanov-Rabotnov; This is the damage intensity reduction factor. Under a constant load F, the actual stress for: In the formula The applied force is set by the testing machine / loading device, and the effective stress is... for: In the formula ∈(0,1).

5. The method for online prediction of the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system according to claim 4, characterized in that, Considering the localized stress concentration caused by pitting corrosion, the effective stress considering pitting corrosion is obtained. for: in It is the effective gap coefficient, and ≥1, where To account for the actual stress in the presence of pitting; Due to pure elastic geometric effects Notch sensitivity calibration of materials: In the formula , ∈[0,1], Because the pit is deep, The radius of curvature is the pit opening / bottom.

6. The method for online prediction of the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system according to claim 1, characterized in that, In step S4, the instantaneous creep strain rate under the current temperature and stress is... for: Considering the instantaneous creep strain rate of pitting corrosion for: In the formula , For material constants, The equivalent activation energy is given by R, where R is the gas constant. Absolute temperature Let RT be the product of RT and RT at time t.

7. The method for online prediction of the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system according to claim 6, characterized in that, Constructing a coupled damage model for damage index early warning for: in the formula , , These are weighting coefficients. Characteristics of electrochemical noise power spectral density; Given a geometric limit or a comprehensive damage threshold to trigger failure determination, In the formula For minimum safe thickness, Alarm thresholds are determined based on experience or historical data. This refers to a failure event.

8. The method for online prediction of the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system according to claim 1, characterized in that, In step S5, the Kachanov-Rabotnov creep damage is as follows: Bundle , Substitute the Kachanov-Rabotnov equations and integrate to obtain the damage variable. ∈[0,1), using damage variables →1 Determine the time of failure , , , , is a material constant.

9. The method for online prediction of the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system according to claim 1, characterized in that, In step S6, the remaining lifetime is set as the failure criterion. ,exist Refers to the future time The damage index is a critical threshold; failure is determined when the threshold is reached or exceeded. Defined as Then the comparison and judgment of damage indicators is transformed into the direct output of failure events. The above formula can be simplified to: In the formula The moment when any threshold is first met. As a future time variable, used in a set Iterate through all possible future moments. For at any time The event that causes failure, where T represents the current time. Let be the remaining lifetime at time t. The moment when any threshold is first met, i.e., the failure moment.

10. The method for online prediction of the remaining lifetime of a chlorine-rich high-temperature environment coupled with stress system according to claim 1, characterized in that, In step 7, the risk index for: , , The weighting coefficients are selected based on the validation set. Determined through logistic regression / Bayesian optimization based on historical events; Dynamic threshold Adaptive to different operating conditions , ,: Historical baseline mean and standard deviation; Quantitative coefficients; This is a working condition correction factor; The higher the number, the higher the risk. Used to trigger an alert; Reflecting temperature With atmospheric components The impact on the threshold.

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