SCAL type indirect air cooling system iron and aluminum corrosion monitoring system and method

Abstract

The invention belongs to the technical field of indirect air cooling system equipment corrosion monitoring, and relates to an SCAL type indirect air cooling system iron and aluminum corrosion monitoring system and method. By acquiring the water quality data of the circulating water, the damage data of the aluminum oxide film on the metal surface of the aluminum cooling pipeline and the damage data of the iron oxide film on the metal surface of the iron circulating water pipeline in real time, various key water quality index conditions influencing iron and aluminum corrosion in the circulating water can be mastered in real time; and abundant and timely basic data is provided for accurately evaluating the iron and aluminum corrosion risk. Acquiring linear polarization resistance according to the water quality data of the circulating water, the aluminum oxide film damage data and the iron oxide film damage data; iron and aluminum corrosion risk assessment is performed according to the linear polarization resistance and the water quality data in combination with the corrosion risk assessment model, various factors affecting iron and aluminum corrosion and interaction of the factors are fully considered, and the reliability and accuracy of a monitoring result are improved.

Description

Technical Field

[0001] This invention belongs to the field of corrosion monitoring technology for indirect air-cooled system equipment, and relates to a SCAL-type indirect air-cooled system iron-aluminum corrosion monitoring system and method. Background Technology

[0002] In the power industry, SCAL-type indirect air-cooled systems are a key component of power plant cooling systems. In surface-type indirect air-cooled systems, iron and aluminum metals are the core materials for the air-cooled radiators (such as aluminum finned tubes), circulating water pipes, and auxiliary equipment. During system operation, circulating water (usually demineralized water or water with low conductivity) flows within steel or aluminum heat exchange tubes, exchanging heat with the outside air through the tube walls. However, iron and aluminum metals are prone to electrochemical corrosion under specific water quality conditions, specifically manifested as follows: Aluminum corrosion: Although aluminum surfaces easily form dense corrosion... An oxide film (approximately 5-10 nm thick) is formed, but in alkaline environments with pH > 9.0, the oxide film will react with... The reaction produces soluble aluminate ( ), leading to membrane damage; in or When the concentration of chloride exceeds the standard, the coordination effect of chloride ions will accelerate the local dissolution of the oxide film, causing pitting or crevice corrosion.

[0003] Iron corrosion: In the presence of dissolved oxygen, iron undergoes oxygen absorption corrosion, with the anodic reaction being Fe → + The cathode reaction is +2 + → Corrosion products Further oxidation to a loose texture rust eventually forms. n ), thus, an effective protective film cannot be formed.

[0004] Currently, there are many shortcomings in the monitoring methods for iron and aluminum corrosion in SCAL-type indirect air-cooled systems.

[0005] The traditional weightless suspension test is a common corrosion monitoring method. This method involves suspending iron or aluminum test pieces of a specific size in circulating water, removing them after a period of time, and calculating the corrosion rate by measuring the weight loss of the test pieces. However, this method has significant drawbacks. First, the weightless suspension test is an offline monitoring method and cannot reflect the real-time corrosion status of iron and aluminum in the system. Severe corrosion may have already occurred during the suspension period without being detected in time. Second, the placement of the suspension piece significantly affects the results; an improperly chosen location cannot represent the overall corrosion status of the system. Furthermore, this method is cumbersome, requiring periodic removal of the test pieces for cleaning and weighing, consuming considerable manpower and resources.

[0006] Besides the weightless plate method, traditional monitoring methods mostly rely on manual periodic sampling. This method cannot achieve real-time monitoring and cannot capture the instantaneous occurrence of corrosion or changes in the corrosion rate. Moreover, the number of samples collected manually is limited, which cannot comprehensively reflect the corrosion status of iron and aluminum in the entire system, resulting in a large monitoring blind spot.

[0007] From the perspective of monitoring the thickness of oxide films on metal surfaces, although some existing non-real-time monitoring technologies can measure the thickness of oxide films, they are complicated to operate and require the metal components to be disassembled from the system for testing. This not only affects the normal operation of the system, but also greatly reduces the accuracy of the measurement results due to the difference between the testing environment and the actual operating environment.

[0008] In monitoring circulating water quality indicators, existing methods often focus on single-indicator detection, such as pH value or chloride ion concentration, lacking comprehensive analysis of multiple water quality indicators. However, iron and aluminum corrosion is the result of the combined effects of various water quality factors, and monitoring a single indicator cannot accurately assess corrosion risk. Furthermore, traditional water quality monitoring equipment is mostly offline, requiring manual water sample collection and laboratory analysis, which is time-consuming and cannot meet the needs of real-time monitoring.

[0009] Furthermore, existing monitoring technologies generally lack the ability to accurately assess the risk level of iron-aluminum corrosion and provide timely alerts. Even if some signs of corrosion are detected, it is difficult to quickly determine the degree of harm to system operation, failing to provide maintenance personnel with clear decision-making basis. This makes it difficult for maintenance personnel to take effective protective measures in a timely manner, further exacerbating the damage caused by iron-aluminum corrosion to the system.

[0010] In summary, existing methods for monitoring iron-aluminum corrosion in SCAL-type indirect air-cooled systems suffer from problems such as insufficient real-time monitoring, incomplete monitoring, low monitoring accuracy, lack of risk assessment, and inability to issue timely risk warnings. Summary of the Invention

[0011] The purpose of this invention is to provide a monitoring system and method for iron-aluminum corrosion in SCAL-type indirect air-cooled systems, in order to solve the technical problems existing in the monitoring methods for iron-aluminum corrosion in SCAL-type indirect air-cooled systems, such as insufficient real-time monitoring, incomplete monitoring, low monitoring accuracy, lack of risk assessment, and inability to provide timely risk warnings.

[0012] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides an SCAL type indirect air-cooled system iron-aluminum corrosion monitoring system, comprising an electrochemical workstation, several water quality monitoring and analysis units, a data processing and alarm unit, several aluminum three-electrode units and several iron three-electrode units, wherein several aluminum three-electrode units and several iron three-electrode units are connected to the electrochemical workstation, and the electrochemical workstation and several water quality monitoring and analysis units are connected to the data processing and alarm unit. The water quality monitoring and analysis unit is used to acquire water samples from the iron circulating water pipeline in real time and obtain water quality data of the circulating water based on the water samples. The aluminum three-electrode unit is used to acquire data on the damage of the aluminum oxide film on the metal surface of the aluminum cooling pipe in real time. The iron tri-electrode unit is used to acquire data on the damage of the iron oxide film on the metal surface of the iron circulating water pipe in real time. The electrochemical workstation is used to control the aluminum three-electrode unit and the iron three-electrode unit to perform real-time detection, and to obtain the linear polarization resistance based on the aluminum oxide film damage data and the iron oxide film damage data; The data processing and alarm unit performs an iron-aluminum corrosion risk assessment based on linear polarization resistance and water quality data, and issues an alarm based on the iron-aluminum corrosion risk assessment results.

[0013] Furthermore, the aluminum three-electrode unit includes an aluminum working electrode, an insulating sealing part, a first reference electrode, and a first auxiliary electrode. The insulating sealing part seals and fixes the aluminum working electrode inside the aluminum cooling pipe. The aluminum working electrode, the insulating sealing part, the first reference electrode, and the first auxiliary electrode are all connected to the electrochemical workstation. The iron triple electrode unit includes a clamp, an iron working electrode, a second reference electrode, and a second auxiliary electrode. The iron working electrode is fixed inside an iron circulating water pipe by the clamp. The clamp, the iron working electrode, the second reference electrode, and the second auxiliary electrode are all connected to the electrochemical workstation.

[0014] Furthermore, the electrochemical workstation applies a DC voltage signal to the aluminum cooling pipe through the aluminum working electrode and simultaneously measures the polarization current flowing between the aluminum working electrode and the first auxiliary electrode; The electrochemical workstation applies a DC voltage signal to the iron circulating water pipeline through the iron working electrode and simultaneously measures the polarization current flowing between the iron working electrode and the first auxiliary electrode. According to Ohm's law, the linear polarization resistance can be obtained in real time by measuring the polarization current and the applied DC voltage signal.

[0015] Furthermore, the water quality monitoring and analysis unit is connected to the interior of the aluminum cooling pipe and the iron circulating water pipe respectively through stainless steel sampling tubes.

[0016] Secondly, this invention provides a method for monitoring iron-aluminum corrosion in a SCAL-type indirect air-cooled system, based on an SCAL-type indirect air-cooled system iron-aluminum corrosion monitoring system, comprising the following steps: Real-time acquisition of circulating water quality data, aluminum oxide film damage data on the metal surface of aluminum cooling pipes, and iron oxide film damage data on the metal surface of iron circulating water pipes; The linear polarization resistance is obtained based on the water quality data of the circulating water, the damage data of the aluminum oxide film, and the damage data of the iron oxide film. The risk assessment of iron-aluminum corrosion is conducted based on linear polarization resistance and water quality data combined with a corrosion risk assessment model, and an alarm is triggered based on the results of the iron-aluminum corrosion risk assessment.

[0017] Furthermore, the water quality data includes the pH value, iron and aluminum ion concentration, dissolved oxygen, chloride ion concentration, and conductivity of the circulating water.

[0018] Furthermore, the corrosion risk assessment model is as follows:

[0019] in, As a corrosion risk index, This is the weighting coefficient for the linearly polarized resistance. The weighting coefficients for iron and aluminum ion concentrations are: The weighting factor for pH value, This is the weighting coefficient for chloride ion concentration. The weighting coefficients are the normalized values ​​of conductivity. This is the linear polarization resistance value. This refers to the concentration of iron and aluminum ions. pH value Chloride ion concentration, This is the normalized value of conductivity.

[0020] Furthermore, the method for obtaining the corrosion risk assessment model is as follows: Acquire historical data, including historical circulating water quality data, historical aluminum oxide film damage data, and historical iron oxide film damage data; The historical data is preprocessed to obtain preprocessed historical data; The corrosion risk assessment model was obtained by fitting the preprocessed historical data using the least squares method.

[0021] Furthermore, it also includes the following steps: The corrosion risk assessment model was evaluated using k-fold cross-validation to obtain the prediction error; The prediction error includes mean square error and mean absolute error; The formula for calculating the mean square error is:

[0022] The formula for calculating the mean absolute error is:

[0023] Among them, the For the predicted value, the The actual observed values, the The mean square error is... For the mean absolute error, the This represents the number of samples.

[0024] Furthermore, the historical data is preprocessed to obtain preprocessed historical data, as detailed below: Obtain the standard deviation and mean of the historical data; Outlier data was identified using the 3σ criterion based on statistical methods, using standard deviation and mean. Linear interpolation can be used to fill in outliers or outliers can be estimated based on the characteristics of neighboring data points.

[0025] Compared with the prior art, the present invention has the following beneficial effects: The water quality monitoring and analysis unit of this invention is used to acquire water samples from iron circulating water pipes in real time and obtain water quality data of the circulating water based on the water samples for real-time monitoring of multiple water quality indicators. The aluminum three-electrode unit is used to acquire data on the damage to the aluminum oxide film on the metal surface of the aluminum cooling pipes in real time. Real-time monitoring of the state of the aluminum oxide film improves the accuracy and timeliness of the measurement results. The iron three-electrode unit is used to acquire data on the damage to the iron oxide film on the metal surface of the iron circulating water pipes in real time, enabling real-time monitoring of the state of the iron oxide film and providing real-time data for accurately assessing iron corrosion. The electrochemical workstation is used to control the aluminum and iron three-electrode units to perform real-time detection, and obtains linear polarization resistance based on the aluminum and iron oxide film damage data, realizing real-time monitoring and quantitative analysis of iron-aluminum metal corrosion, providing key data support for subsequent corrosion risk assessment. The data processing and alarm unit performs iron-aluminum corrosion risk assessment based on the linear polarization resistance and water quality data, and issues an alarm based on the iron-aluminum corrosion risk assessment results. This invention enables accurate assessment and timely alerts of the risk level of iron-aluminum corrosion, providing maintenance personnel with clear decision-making support. By controlling the aluminum and iron triple-electrode units through an electrochemical workstation to monitor iron-aluminum oxide film damage data in real time, and by acquiring water quality data in real time through a water quality monitoring and analysis unit, this invention achieves real-time monitoring of the iron-aluminum corrosion status and water quality throughout the system. This avoids the drawbacks of traditional offline monitoring or periodic manual sampling, which cannot reflect problems in real time. It comprehensively considers various factors affecting iron-aluminum corrosion, overcoming the problems of incomplete monitoring and blind spots in traditional methods, thus improving monitoring accuracy.

[0026] This invention acquires real-time data on circulating water quality, aluminum oxide film damage on the metal surface of aluminum cooling pipes, and iron oxide film damage on the metal surface of iron circulating water pipes. This facilitates real-time monitoring of various key water quality indicators affecting iron-aluminum corrosion in the circulating water, providing rich and timely basic data for accurate assessment of iron-aluminum corrosion risk. Linear polarization resistance is obtained based on the circulating water quality data, aluminum oxide film damage data, and iron oxide film damage data. Iron-aluminum corrosion risk is assessed by combining the linear polarization resistance and water quality data with a corrosion risk assessment model, fully considering various factors affecting iron-aluminum corrosion and their interactions. This invention achieves real-time monitoring of iron-aluminum corrosion in the entire SCAL indirect air-cooled system by acquiring real-time water quality data, aluminum oxide film damage data, and iron oxide film damage data, and conducting subsequent analysis and assessment based on this real-time data. Simultaneously, by comprehensively considering water quality factors and metal surface conditions, it comprehensively covers various factors affecting iron-aluminum corrosion, overcoming the shortcomings of traditional monitoring methods in terms of real-time performance and incomplete monitoring, and improving the reliability and accuracy of monitoring results. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the installation of the three-electrode system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a circulating water quality monitoring system according to an embodiment of the present invention; Figure 3 This is a flowchart of a method according to an embodiment of the present invention.

[0028] The components include: 1. Electrochemical workstation; 2. Aluminum working electrode; 3. Insulating sealing part; 4. First reference electrode; 5. First auxiliary electrode; 6. Fixture; 7. Iron working electrode; 8. Insulated wire; 9. Aluminum radiator; 10. Aluminum cooling pipe; 11. Iron circulating water pipe; 12. Stainless steel sampling tube; 13. Water quality monitoring and analysis unit; 14. Data processing and alarm unit; 15. Aluminum three-electrode unit; 16. Iron three-electrode unit; 17. Second reference electrode; 18. Second auxiliary electrode. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first," "second," etc., in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1 and Figure 2This invention discloses an SCAL-type indirect air-cooled system iron-aluminum corrosion monitoring system, including an electrochemical workstation 1, several water quality monitoring and analysis units 13, a data processing and alarm unit 14, several aluminum three-electrode units 15 and several iron three-electrode units 16. The several aluminum three-electrode units 15 and several iron three-electrode units 16 are connected to the electrochemical workstation 1, and the electrochemical workstation 1 and the several water quality monitoring and analysis units 13 are connected to the data processing and alarm unit 14. The water quality monitoring and analysis unit 13 is used to acquire water samples in the iron circulating water pipeline 11 in real time, and to acquire water quality data of the circulating water based on the water samples, for real-time monitoring of multiple water quality indicators.

[0032] In this embodiment of the invention, the water quality monitoring and analysis unit 13 is connected to the interior of the aluminum cooling pipe 10 and the iron circulating water pipe 11 respectively through the stainless steel sampling tube 12.

[0033] The aluminum three-electrode unit 15 is used to acquire data on the damage of the aluminum oxide film on the metal surface of the aluminum cooling pipe 10 in real time. Real-time monitoring of the aluminum oxide film's condition, compared to traditional non-real-time monitoring technologies, eliminates the need to disassemble metal components, does not affect normal system operation, and ensures the detection environment matches the actual operating environment, thus improving the accuracy of the measurement results.

[0034] The iron tri-electrode unit 16 is used to acquire real-time data on the damage to the iron oxide film on the metal surface of the iron circulating water pipe 11. It can monitor the state of the iron oxide film in real time, overcoming the shortcomings of traditional monitoring methods and providing real-time data for accurately assessing iron corrosion.

[0035] The electrochemical workstation 1 is used to control the aluminum three-electrode unit 15 and the iron three-electrode unit 16 to perform real-time detection. Based on the aluminum oxide film damage data and the iron oxide film damage data, the linear polarization resistance is obtained, realizing real-time monitoring and quantitative analysis of the corrosion status of iron and aluminum metals, and providing key data support for subsequent corrosion risk assessment.

[0036] In this embodiment of the invention, see Figure 1 The aluminum three-electrode unit 15 includes an aluminum working electrode 2, an insulating sealing part 3, a first reference electrode 4, and a first auxiliary electrode 5. The insulating sealing part 3 seals and fixes the aluminum working electrode 2 inside the aluminum cooling pipe 10. The aluminum working electrode 2, the insulating sealing part 3, the first reference electrode 4, and the first auxiliary electrode 5 are all connected to the electrochemical workstation 1. See Figure 1The iron triple electrode unit 16 includes a clamp 6, an iron working electrode 7, a second reference electrode 17, and a second auxiliary electrode 18. The iron working electrode 7 is fixed inside the iron circulating water pipe 11 by the clamp 6. The clamp 6, the iron working electrode 7, the second reference electrode 17, and the second auxiliary electrode 18 are all connected to the electrochemical workstation 1.

[0037] In this embodiment of the invention, the electrochemical workstation 1 applies a DC voltage signal to the aluminum cooling pipe 10 through the aluminum working electrode 2, and simultaneously measures the polarization current flowing between the aluminum working electrode 2 and the first auxiliary electrode 5; The electrochemical workstation 1 applies a DC voltage signal to the iron circulating water pipe 11 through the iron working electrode 7, and simultaneously measures the polarization current flowing between the iron working electrode 7 and the first auxiliary electrode 5. According to Ohm's law, the linear polarization resistance can be obtained in real time by measuring the polarization current and the applied DC voltage signal.

[0038] The data processing and alarm unit 14 performs an iron-aluminum corrosion risk assessment based on linear polarization resistance and water quality data, and issues an alarm based on the assessment results. This enables accurate judgment and timely alarm of the iron-aluminum corrosion risk level, providing maintenance personnel with a clear decision-making basis and solving the problems of existing monitoring technologies lacking risk assessment and timely risk alarm.

[0039] This invention utilizes an electrochemical workstation 1 to control the aluminum three-electrode unit 15 and the iron three-electrode unit 16 to detect iron-aluminum oxide film damage data in real time, and a water quality monitoring and analysis unit 13 to acquire water quality data in real time. This achieves real-time monitoring of the iron-aluminum corrosion status and water quality throughout the entire system, avoiding the drawbacks of traditional offline monitoring or manual periodic sampling methods that cannot reflect problems in real time. It comprehensively considers various factors affecting iron-aluminum corrosion, overcoming the problems of incomplete monitoring and blind spots in traditional methods, thus improving monitoring accuracy.

[0040] Based on the above system, this invention also discloses a method for monitoring iron-aluminum corrosion in an SCAL-type indirect air-cooled system, see [link to relevant documentation]. Figure 3 This includes the following steps: S1 acquires real-time water quality data of circulating water, data on aluminum oxide film damage on the metal surface of aluminum cooling pipe 10, and data on iron oxide film damage on the metal surface of iron circulating water pipe 11. This facilitates real-time monitoring of various key water quality indicators affecting iron and aluminum corrosion in circulating water, providing rich and timely basic data for accurately assessing the risk of iron and aluminum corrosion.

[0041] In this embodiment of the invention, the water quality data includes the pH value, iron and aluminum ion concentration, dissolved oxygen, chloride ion concentration, and conductivity of the circulating water.

[0042] S2, obtain the linear polarization resistance based on the water quality data of the circulating water, the damage data of the aluminum oxide film, and the damage data of the iron oxide film; S3 assesses the risk of iron-aluminum corrosion based on linear polarization resistance and water quality data combined with a corrosion risk assessment model. This comprehensive approach considers various factors influencing iron-aluminum corrosion and their interactions, improving the accuracy of the prediction results. Alarms are triggered based on the iron-aluminum corrosion risk assessment results to promptly communicate the degree of danger of iron-aluminum corrosion in the system to maintenance personnel.

[0043] In this embodiment of the invention, the corrosion risk assessment model is specifically as follows:

[0044] in, As a corrosion risk index, This is the weighting coefficient for the linearly polarized resistance. The weighting coefficients for iron and aluminum ion concentrations are: The weighting factor for pH value, This is the weighting coefficient for chloride ion concentration. The weighting coefficients are the normalized values ​​of conductivity. This is the linear polarization resistance value. This refers to the concentration of iron and aluminum ions. pH value Chloride ion concentration, This is the normalized value of conductivity.

[0045] In this embodiment of the invention, the method for obtaining the corrosion risk assessment model is as follows: Acquire historical data, including historical circulating water quality data, historical aluminum oxide film damage data, and historical iron oxide film damage data; The historical data is preprocessed to obtain preprocessed historical data, as follows: Obtain the standard deviation and mean of the historical data; Outlier data was identified using the 3σ criterion based on statistical methods, using standard deviation and mean. Linear interpolation can be used to fill in outliers or outliers can be estimated based on the characteristics of neighboring data points.

[0046] The corrosion risk assessment model was obtained by fitting the preprocessed historical data using the least squares method.

[0047] In this embodiment of the invention, the following steps are also included: The corrosion risk assessment model was evaluated using k-fold cross-validation to obtain the prediction error; The prediction error includes mean square error and mean absolute error; The formula for calculating the mean square error is:

[0048] The formula for calculating the mean absolute error is:

[0049] Among them, the For the predicted value, the The actual observed values, the The mean square error is... For the mean absolute error, the This represents the number of samples.

[0050] This invention achieves real-time monitoring of iron and aluminum corrosion in the entire SCAL indirect air-cooled system by acquiring real-time water quality data, aluminum oxide film damage data, and iron oxide film damage data, and then performing subsequent analysis and evaluation based on this real-time data. Simultaneously, it comprehensively considers various factors such as water quality and metal surface condition, fully covering all factors affecting iron and aluminum corrosion, overcoming the shortcomings of traditional monitoring methods in terms of real-time performance and incomplete monitoring, and improving the reliability and accuracy of the monitoring results.

[0051] Example 2: See Figure 3 This embodiment aims to provide a method for monitoring iron-aluminum corrosion in a SCAL-type indirect air-cooled system. It can monitor the damage of the oxide film on the iron and aluminum metal surface in real time, comprehensively consider the changes in the conductivity, pH, chloride ion concentration, iron and aluminum ion concentration, and dissolved oxygen of the circulating water, construct a corrosion risk assessment model, accurately calculate the corrosion risk level, promptly detect potential corrosion risks, and effectively determine the risk level and issue alarms, providing a scientific basis for the maintenance and management of the system.

[0052] S1, see S1 Figure 1 The electrochemical linear polarization resistance method was used to monitor the damage of oxide films on the surface of iron and aluminum metals in real time.

[0053] Principle of Linear Polarization Resistance Method: The electrochemical linear polarization resistance method (LPR) is based on the principle of electrode kinetics. When a small DC potential is applied to an iron-aluminum metal electrode immersed in an electrolyte solution (i.e., circulating water), the linear polarization resistance method is applied. When a step voltage is applied (typically within a range of +5mV to -5mV), a minute polarization occurs on the electrode surface. Within this minute polarization region, according to Faraday's law and Ohm's law, the polarization current density... With polarization potential It exhibits a linear relationship, that is ,in It is a linearly polarized resistor.

[0054] In circulating water, iron and aluminum metals typically form an oxide film on their surface, which provides some protection. When the oxide film is intact, the resistance to ions crossing it for electrochemical reactions is significant, manifested as polarization resistance. At higher values, the corrosion rate of iron and aluminum metals is relatively low. However, when the oxide film is damaged due to various factors, the resistance to ion transport decreases, and the polarization resistance... As the polarization resistance decreases, the corrosion reaction of iron and aluminum metals accelerates. Therefore, real-time monitoring of polarization resistance is crucial. The dynamic changes can sensitively reflect the damage to the oxide film on the surface of iron and aluminum metals and the extent of corrosion reaction.

[0055] Electrode arrangement and system setup: Electrodes are arranged on the surfaces of key iron and aluminum components (such as circulating water pipes and heat exchange tubes) of the SCAL type indirect air cooling system using special processes and materials.

[0056] For both the aluminum working electrode 2 and the iron working electrode 7, the same material as the monitored iron and aluminum components is used to ensure that their electrochemical behavior is consistent with that of the actual components. The size design of the working electrodes needs to comprehensively consider the measurement accuracy and the impact on the system's hydrodynamics, with an area exposed to the circulating water of 1~5 cm². 2 .

[0057] The reference electrode is a saturated calomel electrode (SCE) because it has a stable electrode potential and can provide a reliable potential reference for the measurement.

[0058] The auxiliary electrode is a platinum electrode. Platinum has good conductivity and chemical stability, which can effectively promote electron transfer and ensure the smooth progress of the electrochemical reaction.

[0059] A complete three-electrode measurement system is formed by connecting the working electrode, reference electrode, and auxiliary electrode to a high-precision electrochemical workstation using insulated and corrosion-resistant wires. The electrode placement is carefully planned, taking into full account the flow characteristics of the circulating water within the system, such as velocity distribution and turbulence levels. For example, working electrodes are evenly distributed at different locations, including the inlet, outlet, and intermediate sections of the circulating water pipes and heat exchange tubes, to comprehensively capture corrosion information from different areas. Simultaneously, it is ensured that the electrodes are in close contact with the surfaces of iron and aluminum components without interfering with the normal flow of circulating water, avoiding any additional impact on system operation due to electrode installation.

[0060] Measurement process and data acquisition: Start electrochemical workstation 1 and set the applied DC potential. The step voltage is typically set within an amplitude range of +5mV to -5mV. Electrochemical workstation 1 applies a DC voltage signal to the iron-aluminum metal surface via the working electrode and simultaneously measures the polarization current flowing between the working and auxiliary electrodes. Based on Ohm's law, the linear polarization resistance is calculated in real time using the measured polarization current and the applied alternating voltage signal. .

[0061] The data acquisition system continuously acquires the polarization resistance calculated by the electrochemical workstation at one-minute intervals. Data. The collected data first undergoes preliminary filtering using digital filtering algorithms (such as mean filtering and median filtering) to remove outliers caused by environmental interference, measurement noise, and other factors, ensuring data reliability and stability. The filtered data is then stored in a local database in time-series format and simultaneously uploaded to a remote server for backup, facilitating subsequent in-depth analysis and long-term data tracking.

[0062] S2, see S2. Figure 2 In terms of monitoring circulating water quality indicators, we are no longer limited to the detection of a single indicator, but have built a multi-parameter comprehensive monitoring system to accurately monitor pH value, iron and aluminum ion concentration, dissolved oxygen, chloride ion and conductivity.

[0063] pH monitoring: pH is measured using the glass electrode method. A glass electrode is an indicator electrode that selectively responds to hydrogen ions. It forms a galvanic cell with a reference electrode (such as a calomel electrode). When the electrode is immersed in a circulating water sample, the membrane potential of the glass electrode changes with the hydrogen ion activity in the water sample. By measuring the electromotive force of this galvanic cell and applying the Nernst equation, the pH value of the circulating water can be accurately calculated. Modern pH meters typically integrate high-precision potential measurement circuits and automatic temperature compensation functions, enabling rapid and accurate display of measurement results and real-time online monitoring.

[0064] Iron and aluminum ion concentration monitoring: Inductively coupled plasma mass spectrometry (ICP-MS) is used. The sample is introduced into the inductively coupled plasma to ionize the elements in the sample. Then, the water quality monitoring and analysis unit 13 separates and detects the ions. It has extremely high sensitivity and resolution and can accurately measure the concentration of multiple trace elements at the same time. It is of great significance for the accurate determination of iron and aluminum ion concentration in circulating water. In this embodiment, the water quality monitoring and analysis unit 13 uses a mass spectrometer.

[0065] Dissolved oxygen monitoring: An electrochemical probe method is used, which utilizes two different metal electrodes to form a galvanic cell in an electrolyte. Dissolved oxygen is reduced at the cathode, generating a current that is linearly related to the dissolved oxygen concentration, thus enabling the measurement of dissolved oxygen. This type of probe can respond rapidly to changes in dissolved oxygen concentration, meeting the needs of real-time monitoring.

[0066] Chloride ion monitoring: Using the ion-selective electrode method, the concentration of specific ions in the solution is determined by measuring the electrode potential. It can quickly and accurately determine the concentration of chloride ions and other anions, and is especially suitable for the precise analysis of chloride ions in complex water samples.

[0067] Conductivity monitoring: Measurements are performed using a conductivity meter. It features automatic temperature compensation to eliminate the influence of temperature on conductivity measurements, ensuring the accuracy and stability of the results.

[0068] These parameters are collected in real time using the aforementioned sensor technology, and multi-source data are comprehensively analyzed through data fusion algorithms to fully assess the corrosion of iron and aluminum by circulating water. Compared with traditional single-indicator monitoring, multi-parameter comprehensive monitoring can more comprehensively and accurately reflect the impact of water quality on iron and aluminum corrosion. Furthermore, based on the aforementioned monitoring data on oxide film damage and real-time monitoring data of circulating water quality indicators, this invention establishes a scientific corrosion risk assessment model. This model, based on the iron and aluminum corrosion mechanism and combined with extensive experimental data and practical operating experience, determines the quantitative relationship between different monitoring parameters and corrosion risk levels.

[0069] Through dynamic analysis of real-time monitoring data, the model can calculate the corrosion risk level of iron and aluminum in real time, such as low risk, medium risk, and high risk. Finally, an alarm system is developed to complement this. When the risk assessment model determines that iron and aluminum are at a medium risk level or above, the intelligent alarm system is immediately activated, sending alarm information to maintenance personnel through various means (such as audible and visual alarms, SMS notifications, etc.) to inform them of the current corrosion risk status of iron and aluminum and the possible impact on the system. This allows maintenance personnel to take appropriate protective measures in a timely manner, such as adjusting water quality or replacing components, effectively avoiding system failures caused by accelerated iron and aluminum corrosion.

[0070] This invention enables real-time, comprehensive, and accurate monitoring of iron-aluminum corrosion in SCAL-type indirect air-cooling systems, accurately assesses corrosion risk levels, and issues timely alarms, providing maintenance personnel with a scientific and effective basis for decision-making and ensuring the safe and stable operation of the indirect air-cooling system.

[0071] In this embodiment, the electrodes for oxide film monitoring are installed at key locations on the inner walls of the aluminum cooling pipe 10 and the iron circulating water pipe 11. See also... Figure 2 This is a schematic diagram of a circulating water quality monitoring system. The aluminum radiator 9 includes several aluminum cooling pipes 10.

[0072] For aluminum metal, aluminum foil that has undergone rigorous degreasing, alkali washing, and acid washing pretreatment is selected as the aluminum working electrode 2. It is evenly adhered to the surface of the aluminum cooling pipe 10, and an insulating sealing part 3 is used to seal and fix the aluminum working electrode 2 around its perimeter. The insulating sealing part 3 uses a high-performance insulating sealing material to ensure full contact between the electrode and the aluminum substrate while maintaining insulation from the external environment. A saturated calomel electrode is used as the reference electrode, connected to the circulating water environment where the working electrode is located via a salt bridge. The salt bridge is filled with a high-purity saturated potassium chloride solution to maintain ion conduction. Platinum wire is selected as the auxiliary electrode, and to increase the contact area with the solution, the platinum wire is carefully made into a spiral structure. It is installed at an appropriate distance from the working electrode to ensure a smooth and effective current loop throughout the electrochemical measurement process, guaranteeing the accuracy and stability of the measurement.

[0073] For ferrous metal, an iron working electrode 7, made from an iron disc with a purity of up to 99.9%, was carefully designed with a diameter of 5 mm. Before installation, the surface of the iron disc was mechanically polished using sandpaper of different grits until the surface roughness reached below Ra 0.1 μm. Electrochemical polishing was then performed to further improve surface uniformity. A custom-designed clamp 6 securely mounted the electrode to the critical ferrous metal component of the SCAL indirect air-cooling system, ensuring a good electrical connection between the electrode and the iron substrate. The electrode was connected to the electrochemical workstation 1 via insulated wires 8.

[0074] Signal Application and Acquisition: A high-precision electrochemical workstation 1 applies a DC potential step ΔE to the working electrode, typically with an amplitude range of +5mV to -5mV. The electrochemical workstation 1 applies a DC voltage signal to the working electrode according to the set parameters and measures the polarization current between the working electrode and the auxiliary electrode in real time. Based on Ohm's law, the workstation's built-in algorithm calculates the linear polarization resistance in real time. The measurements were recorded at intervals of one second. Value. To ensure the accuracy and integrity of the data, the data acquisition system simultaneously records the time of each measurement, accurate to the millisecond level.

[0075] The acquired raw polarization resistance data first undergoes preliminary filtering, employing a digital low-pass filter algorithm to remove high-frequency noise interference. Simultaneously, a moving average filtering method is used to smooth the data, reducing random fluctuations during the measurement process. Specifically, a sliding window containing n consecutive measurement values ​​is set, typically n=10. The average value of the data within each window is calculated as the filtered output value. As new data is continuously acquired, the sliding window moves forward sequentially, resulting in a smoothed polarization resistance data sequence. The preprocessed data is then efficiently transmitted to the data processing and alarm unit 14 in the form of a digital signal.

[0076] Data processing and thickness calculation: Data processing and alarm unit 14 according to Value changes, if A higher value and a smaller trend in change indicate that the corrosion rate of iron and aluminum metals is relatively low, and the oxide film is intact; if As the value continues to decrease, the corrosion rate of iron and aluminum metals is relatively high, and the oxide film is damaged.

[0077] For circulating water quality monitoring, a stainless steel sampling tube 12 is connected to the circulating water pipeline, and the stainless steel sampling tube 12 is connected to the water quality monitoring and analysis unit 13 to monitor the pH value, iron and aluminum ion concentration, dissolved oxygen, chloride ion concentration and conductivity of the circulating water in real time.

[0078] Comprehensive analysis and risk assessment data integration: Data processing and alarm unit 14 integrates linear polarization resistors. The system comprehensively integrates a large amount of data from various water quality indicators monitoring to construct a massive dataset containing multi-dimensional, high-precision information. For each monitoring parameter, not only are real-time measurements recorded in detail, but data over a period of time is also deeply stored and comprehensively statistically analyzed. By employing advanced data analysis algorithms, rich statistical characteristics such as data trends, averages, standard deviations, and coefficients of variation are obtained, providing a solid data foundation for subsequent risk assessment and establishing assessment models.

[0079] First, a comprehensive collection of historical monitoring data for the SCAL type indirect air-cooled system under different operating stages and conditions was conducted, covering linear polarization resistance. The system monitors several key parameters, including pH, iron and aluminum ion concentrations, chloride ion concentrations, and conductivity. These data are derived from real-time monitoring records, periodic testing reports, and experimental research data accumulated during long-term system operation, ensuring the completeness and representativeness of the data.

[0080] Data preprocessing: A large amount of historical data is carefully screened and preprocessed to remove outliers and noise interference, ensuring high data quality and reliability.

[0081] Outlier data was identified using the 3σ criterion, a statistical method. For each monitored parameter, its mean μ and standard deviation σ were calculated. If a data point deviated from the mean by more than three times the standard deviation (i.e., [X-μ]>3σ), the data point was determined to be an outlier. For outlier handling, based on the time series characteristics of the data, if the data before and after the outlier was relatively stable, linear interpolation was used for imputation; if the outlier was located in a range of large data fluctuations, a reasonable value for the outlier was estimated based on the characteristics of neighboring data points.

[0082] Digital filtering techniques are used to remove noise interference from the data. For linearly polarized resistors... For parameters such as electrical conductivity and other values ​​that change continuously over time, a moving average filtering method is employed. A suitable window size is set (e.g., a window containing 10 consecutive data points). The average value of the data within the window is calculated each time as the filtered output value. As new data is continuously acquired, the sliding window moves forward sequentially, thus smoothing the data and reducing the impact of random noise. For discrete measurement data (such as iron and aluminum ion concentrations, which are discrete values ​​in each detection), noise data caused by measurement errors or random factors is removed by comparing multiple measurement results and analyzing them in conjunction with system operating conditions. After the above processing, the high quality and reliability of the data are ensured, providing a solid foundation for subsequent modeling.

[0083] Model Construction and Weight Determination: Based on the study of the corrosion mechanism of iron and aluminum in circulating water and extensive experimental verification, the linear polarization resistance value was determined. Several key monitoring parameters, including iron and aluminum ion concentration, pH value, chloride ion concentration, and conductivity, were incorporated as independent variables into the corrosion risk assessment model. For each independent variable, its weight range was initially determined based on its mechanism of action and degree of influence in the iron-aluminum corrosion process. For example, linear polarization resistance... The pH value directly reflects the damage to the oxide film on the surface of iron and aluminum metals and the ease of corrosion reaction, and has a significant impact on corrosion risk assessment. Its initial weight range is set at 0.3-0.5. Iron and aluminum ion concentration is a direct product of iron and aluminum corrosion, and its concentration change directly reflects the degree of corrosion; its weight range is set at 0.2-0.3. pH value has a significant impact on the corrosion behavior of iron and aluminum; excessive acidity or alkalinity will accelerate corrosion; its weight range is set at 0.1-0.2. Chloride ions are highly corrosive and can destroy the oxide film on the surface of iron and aluminum; its weight range is set at 0.1-0.2. Conductivity reflects the overall concentration and migration ability of ions in circulating water, indirectly affecting the corrosion process; its weight range is set at 0.05-0.15. Determining these weight ranges provides a reasonable initial range for subsequent accurate weight calculations.

[0084] Least squares fitting: The least squares method is used to fit the preprocessed historical data. Let the corrosion risk assessment model be:

[0085] in As a corrosion risk index, These are the weighting coefficients for each parameter. Values ​​range from 1 to 5. , , , and These are the normalized values ​​of linear polarization resistance, iron and aluminum ion concentration, pH value, chloride ion concentration, and conductivity, respectively. The core objective of the least squares method is to adjust the weighting coefficients... This makes the model's predicted values Compared with actual observed values Sum of squared errors between To reach the minimum. The weight coefficients are calculated iteratively by solving the normal equation system. This continues until the sum of squared errors converges to a minimum value, thus obtaining the optimal combination of weight coefficients.

[0086] Model Evaluation and Validation: The model is evaluated using k-fold cross-validation (typically k=5 or k=10). Historical data is randomly divided into k subsets. One subset is selected as the test set each time, and the remaining k-1 subsets are used as the training set. For example, when k=5, the data is divided into five subsets. One subset is selected sequentially as the test set, and the model is trained using data from the remaining four subsets. The model is then tested on the test set to obtain its prediction results.

[0087] Performance metrics calculation: Through multiple cross-validations, the prediction error of the model on different test sets is calculated. The mean squared error (MSE) and mean absolute error (MAE) are used to evaluate the model's generalization ability. The formula for calculating the mean squared error is as follows: It reflects the squared mean of the error between the predicted and actual values, and is more sensitive to larger errors; the formula for calculating the mean absolute error is... It measures the average absolute error between predicted and actual values, providing a more intuitive reflection of the magnitude of the prediction error. By calculating these metrics, the prediction accuracy and stability of the model on different subsets of data can be comprehensively evaluated.

[0088] Model Validation and Optimization: Set acceptable error thresholds, for example, mean squared error (MSE) < 0.05 and mean absolute error (MAE) < 0.03. If the model's prediction error in multiple cross-validations is within acceptable limits, it indicates that the model has high accuracy and stability and can be effectively used for practical corrosion risk assessment. If the model's error exceeds the threshold, analyze the causes of the error, which may include inadequate data preprocessing, unreasonable selection of independent variables, or defects in the model structure. To address these issues, further optimize the data preprocessing methods, adjust the independent variables, or improve the model structure, and retrain and validate the model until its performance meets the requirements.

[0089] Through the rigorous calculation of the above indicators, the predictive accuracy of the model can be evaluated. The smaller the values ​​of MSE and MAE, the closer the model's predicted values ​​are to the actual observed values, and the better the model's performance. In corrosion risk assessment, by continuously adjusting model parameters (such as weighting coefficients) and optimizing the model structure, the values ​​of MSE and MAE can be minimized, thereby improving the reliability and effectiveness of the model in practical applications.

[0090] Real-time acquisition of linear polarization resistance The value is relatively stable under real-time monitoring of the undamaged iron and aluminum oxide film. The value is recorded, and its changing trend is observed. If the linear polarization resistance... The value is low, less than Rp1, and tends to decrease rapidly, strongly indicating that the oxide film is currently undergoing rapid damage, suggesting that the corrosion process of iron and aluminum metals may be accelerating; if the polarization resistance Values ​​lower than equal The trend is relatively stable, indicating that the oxide film is not damaged and the corrosion rate of iron and aluminum metals is low.

[0091] Current polarization resistor The values ​​are significantly lower than the historical average and show a continuous downward trend, which further strongly indicates that the corrosion risk of iron and aluminum metals is increasing significantly. Meanwhile, based on the system's design parameters and long-term operating experience, the normal operating range for iron ion concentration is determined to be 0-[M] mg / L, and the normal operating range for aluminum ion concentration is 0-[N] mg / L. When the iron or aluminum ion concentration exceeds this normal range, it indicates that iron and aluminum metals may have experienced severe corrosion and dissolution in the circulating water. pH value has a crucial impact on iron and aluminum corrosion. Under acidic conditions (pH<7), iron corrosion is accelerated; while under alkaline conditions (pH>7), aluminum corrosion is more detrimental. Through statistical analysis of system operating data, the normal pH range of the circulating water in this system is determined to be 7.0-9.0. When the pH value deviates from this normal range, it means that the corrosion environment has changed, and the corrosion risk of iron and aluminum increases accordingly. Increased dissolved oxygen content usually greatly promotes oxygen-absorbing corrosion of iron and aluminum. The upper limit of dissolved oxygen concentration is set at [O] mg / L. If the dissolved oxygen concentration exceeds this upper limit, it indicates that the dissolved oxygen content in the circulating water is too high, which will significantly increase the corrosion risk of iron and aluminum. Chloride ions, being highly corrosive, have a strong destructive effect on the oxide film on the surface of iron and aluminum. The chloride ion concentration threshold is defined as [Cl] mg / L. When the chloride ion concentration exceeds this threshold, chloride ions preferentially adsorb onto defects in the oxide film on the iron and aluminum surface, destroying the integrity of the oxide film and thus accelerating the corrosion process. Conductivity directly reflects the overall concentration of ions in circulating water. An abnormally high conductivity likely indicates an increase in the concentration of corrosive ions in the water, leading to an increased risk of corrosion of iron and aluminum. By analyzing historical data, the normal fluctuation range of conductivity is determined. When conductivity exceeds this range, it is considered an important warning signal of increased corrosion risk.

[0092] Comprehensive evaluation: Polarization resistor The detailed analysis results of value changes and various water quality indicators are precisely input into a carefully constructed corrosion risk assessment model. Based on quantitative relationships pre-determined through fitting a large amount of data, the model calculates the current corrosion risk level of iron and aluminum in real time. The corrosion risk level is divided into three levels: low risk, medium risk, and high risk.

[0093] Low risk indicates that the current corrosion state of iron and aluminum is relatively stable, with minimal potential impact on system operation; Medium risk means that the corrosion of iron and aluminum needs attention and some preventive measures may need to be taken; A high risk indicates that the corrosion of iron and aluminum is already quite severe, and effective countermeasures must be taken immediately to avoid serious damage to the SCAL type indirect air-cooling system.

[0094] When the corrosion risk assessment model determines that iron and aluminum are at a medium or higher risk level, the alarm system will promptly issue alarms through the following methods: audible and visual alarms, SMS messages, and APP push notifications.

[0095] Through the above specific implementation methods, real-time, comprehensive, and accurate monitoring of iron-aluminum corrosion in the SCAL type indirect air-cooled system can be achieved, the corrosion risk level can be accurately determined, and alarms can be issued in a timely manner.

[0096] From a real-time monitoring perspective, this invention uses the linear polarization resistance method to measure the linear polarization resistance value of iron and aluminum metal surfaces. Real-time monitoring can reflect the oxidation state of iron and aluminum metal surfaces; and by using various advanced sensors to collect real-time data on water quality indicators such as pH, iron and aluminum ion concentration, dissolved oxygen, chloride ions, and conductivity of circulating water, it can capture subtle changes in iron and aluminum corrosion in the first instance. Compared with traditional periodic sampling and offline monitoring methods, this method can grasp the corrosion dynamics of iron and aluminum in the system at any time, greatly improving the timeliness of monitoring. This invention has significant advantages in terms of comprehensiveness and accuracy. On the one hand, the oxide film state monitoring combines precise electrochemical principles and advanced data processing algorithms, which can accurately monitor whether the oxide film is damaged, and can also detect changes through linear polarization resistance. By analyzing the changing trends of these values, we can gain a deeper understanding of the iron-aluminum corrosion process. On the other hand, the constructed multi-parameter circulating water quality comprehensive monitoring system covers several key indicators closely related to iron-aluminum corrosion, overcoming the limitations of traditional single-indicator monitoring. Through comprehensive analysis of these indicators, we can more comprehensively and accurately assess the corrosive tendency of circulating water towards iron and aluminum.

[0097] This invention presents a corrosion risk assessment model based on real-time, comprehensive, and accurate monitoring data, capable of scientifically determining the corrosion risk level of iron and aluminum. Based on the iron-aluminum corrosion mechanism and validated through extensive experimental data and practical operational experience, the model demonstrates high accuracy and reliability. By inputting monitoring data in real time, the model can output an accurate risk level, providing maintenance personnel with a clear basis for decision-making. Compared to traditional monitoring technologies that lack effective risk assessment, this invention enables maintenance personnel to clearly understand the extent of the harm caused by iron-aluminum corrosion to system operation, thereby allowing for the rational arrangement of maintenance plans and resource allocation.

[0098] In addition, the implementation of this invention also has certain economic benefits. By timely and accurately monitoring the corrosion of iron and aluminum, it avoids equipment damage and replacement caused by corrosion, extends the service life of the equipment, and reduces equipment maintenance and replacement costs.

[0099] In summary, the SCAL-type indirect air-cooled system iron-aluminum corrosion monitoring method of the present invention has significant advantages in terms of real-time performance, accuracy, risk assessment, and alarm, and can provide strong protection for the safe and stable operation of the power system's indirect air-cooled system. It has broad application prospects and important practical significance.

[0100] Example 3: This embodiment uses a SCAL-type indirect air-cooled system of a 600MW thermal power plant as an example to illustrate the specific implementation and effects of the present invention.

[0101] Oxide film condition monitoring electrode installation: On the surface of the iron circulating water pipes and aluminum cooling pipes of the indirect air-cooling system, select a flat area and install the iron and aluminum working electrodes 2. The iron working electrode 7 is a 5mm diameter high-purity iron disc, which is ground and polished to a surface roughness Ra of 0.1μm, and then tightly fixed to the pipe using a special clamp to ensure good electrical connection with the pipe. The aluminum working electrode is made of aluminum foil that has undergone strict degreasing, alkali washing, and acid washing pretreatment. It is evenly attached to the surface of the aluminum component and sealed around the perimeter with high-performance insulating sealing material to ensure full contact between the electrode and the aluminum substrate and insulation from the external environment.

[0102] A saturated calomel reference electrode is connected to circulating water in a cooling pipe via a salt bridge. The salt bridge is filled with a saturated potassium chloride solution to provide a stable potential reference for the working electrode. A spiral-shaped platinum wire auxiliary electrode is installed near the working electrode to construct a complete three-electrode system.

[0103] A DC voltage signal is applied to the working electrode. The electrochemical workstation applies the DC voltage signal to the working electrode according to the set parameters and measures the polarization current through the working electrode and the auxiliary electrode in real time. Based on Ohm's law, the workstation's built-in algorithm calculates the linear polarization resistance in real time. The measurements were recorded at intervals of one second. Values. To ensure data accuracy and completeness, the data acquisition system simultaneously records the time of each measurement. Through continuous monitoring, the linear polarization resistance at different time points is recorded. The data acquisition system continuously collects the polarization resistance calculated by the electrochemical workstation at one-minute intervals. Data. The collected data first undergoes preliminary filtering to remove outliers caused by environmental interference, measurement noise, and other factors, ensuring the reliability and stability of the data. The value changes. If A higher value and a smaller trend indicate a relatively low corrosion rate for iron and aluminum, with an intact oxide film, suggesting a low corrosion rate for iron and aluminum; if The value continues to decrease, indicating that the corrosion rate of iron and aluminum metals is relatively high, and the oxide film is damaged, which indicates that the corrosion rate of iron and aluminum is accelerating.

[0104] Meanwhile, sampling pipes are installed in the circulating water pipeline to monitor the pH value, iron ion concentration, dissolved oxygen, chloride ion concentration, and conductivity of the circulating water in real time.

[0105] At a certain moment, the pH meter showed that the circulating water pH was 7.5, within the normal range of 6.5-8.5; the iron ion concentration was 50 mg / L and the aluminum ion concentration was 20 mg / L, both within the normal operating range (iron ion 0-100 mg / L, aluminum ion 0-100 mg / L); the dissolved oxygen concentration was 6 mg / L, not exceeding the set upper limit of 30 mg / L; the chloride ion concentration was 50 mg / L, not exceeding the threshold of 100 mg / L; and the conductivity was 1.5 μS / cm, within the normal fluctuation range.

[0106] Comprehensive Analysis and Risk Assessment Data Integration: The central data processing system integrates the aforementioned oxide film status and various water quality index data to form a multi-dimensional dataset. Based on a large amount of historical operating data and experimental data from the power plant's indirect air-cooling system, a corrosion risk assessment model is established using a multiple linear regression algorithm. Real-time Assessment: Real-time monitoring data is input into the assessment model to calculate the corrosion risk level. Assuming that within a certain time period, the linear polarization resistance value... The levels are relatively high and show no significant change; the iron ion concentration is 50 mg / L, the aluminum ion concentration is 20 mg / L, the pH value is 7.5, the dissolved oxygen concentration is 6 mg / L, the chloride ion concentration is 50 mg / L, and the conductivity is 1.5 μS / cm. Model calculations indicate a low corrosion risk level. However, over time, if the linear polarization resistance value... Significantly decreasing and trending towards a sustained decrease; rising iron and aluminum ion concentrations, etc., may cause the model to recalculate the risk level to medium or high risk. Alarm: When the risk assessment model determines a risk level of medium or higher, the alarm system is activated. For example, if the model calculates a high risk level at a certain moment, the audible and visual alarm in the control room will immediately emit a strong audible and visual signal; simultaneously, the SMS sending module will send an SMS message to the maintenance personnel's mobile phones containing the current corrosion risk status and recommended measures, such as "The SCAL type indirect air-cooled system has reached a high level of iron corrosion risk, with abnormally high iron ion concentration and damaged oxide film. It is recommended to immediately check the water quality and consider replacing pipe components." The maintenance personnel's mobile APP will also receive a push notification, which can be clicked to view detailed monitoring data and risk assessment reports so that timely countermeasures can be taken.

[0107] As can be seen from this embodiment, the present invention can monitor the iron and aluminum corrosion in the SCAL type indirect air-cooling system in real time, comprehensively and accurately, accurately determine the risk level and issue timely alarms, and effectively ensure the safe and stable operation of the system.

[0108] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A monitoring system for iron and aluminum corrosion in an indirect air-cooled system of the SCAL type, characterized in that, It includes an electrochemical workstation (1), several water quality monitoring and analysis units (13), a data processing and alarm unit (14), several aluminum three-electrode units (15) and several iron three-electrode units (16), several aluminum three-electrode units (15) and several iron three-electrode units (16) are connected to the electrochemical workstation (1), and the electrochemical workstation (1) and several water quality monitoring and analysis units (13) are connected to the data processing and alarm unit (14). The water quality monitoring and analysis unit (13) is used to acquire water samples in the iron circulating water pipeline (11) in real time and to acquire water quality data of the circulating water based on the water samples. The aluminum three-electrode unit (15) is used to acquire data on the damage of the aluminum oxide film on the metal surface of the aluminum cooling pipe (10) in real time; The iron tri-electrode unit (16) is used to acquire data on the damage of the iron oxide film on the metal surface of the iron circulating water pipe (11) in real time. The electrochemical workstation (1) is used to control the aluminum three-electrode unit (15) and the iron three-electrode unit (16) to perform real-time detection and obtain the linear polarization resistance based on the aluminum oxide film damage data and the iron oxide film damage data. The data processing and alarm unit (14) performs an iron-aluminum corrosion risk assessment based on the linear polarization resistance and water quality data, and issues an alarm based on the iron-aluminum corrosion risk assessment results.

2. The SCAL-type indirect air-cooled system iron-aluminum corrosion monitoring system according to claim 1, characterized in that, The aluminum three-electrode unit (15) includes an aluminum working electrode (2), an insulating sealing part (3), a first reference electrode (4), and a first auxiliary electrode (5). The insulating sealing part (3) seals and fixes the aluminum working electrode (2) inside the aluminum cooling pipe (10). The aluminum working electrode (2), the insulating sealing part (3), the first reference electrode (4), and the first auxiliary electrode (5) are all connected to the electrochemical workstation (1). The iron triple electrode unit (16) includes a clamp (6), an iron working electrode (7), a second reference electrode (17), and a second auxiliary electrode (18). The iron working electrode (7) is fixed in the iron circulating water pipe (11) by the clamp (6). The clamp (6), the iron working electrode (7), the second reference electrode (17), and the second auxiliary electrode (18) are all connected to the electrochemical workstation (1).

3. The SCAL-type indirect air-cooled system iron-aluminum corrosion monitoring system according to claim 2, characterized in that, The electrochemical workstation (1) applies a DC voltage signal to the aluminum cooling pipe (10) through the aluminum working electrode (2) and simultaneously measures the polarization current flowing between the aluminum working electrode (2) and the first auxiliary electrode (5); The electrochemical workstation (1) applies a DC voltage signal to the iron circulating water pipe (11) through the iron working electrode (7) and simultaneously measures the polarization current flowing between the iron working electrode (7) and the first auxiliary electrode (5); According to Ohm's law, the linear polarization resistance can be obtained in real time by measuring the polarization current and the applied DC voltage signal.

4. The SCAL-type indirect air-cooled system iron-aluminum corrosion monitoring system according to claim 1, characterized in that, The water quality monitoring and analysis unit (13) is connected to the interior of the aluminum cooling pipe (10) and the iron circulating water pipe (11) respectively through the stainless steel sampling tube (12).

5. A method for monitoring iron-aluminum corrosion in a SCAL-type indirect air-cooled system, based on the SCAL-type indirect air-cooled system iron-aluminum corrosion monitoring system according to any one of claims 1 to 4, characterized in that, Includes the following steps: Real-time acquisition of water quality data of circulating water, data on aluminum oxide film damage on the metal surface of aluminum cooling pipe (10), and data on iron oxide film damage on the metal surface of iron circulating water pipe (11); The linear polarization resistance is obtained based on the water quality data of the circulating water, the damage data of the aluminum oxide film, and the damage data of the iron oxide film. The risk assessment of iron-aluminum corrosion is conducted based on linear polarization resistance and water quality data combined with a corrosion risk assessment model, and an alarm is triggered based on the results of the iron-aluminum corrosion risk assessment.

6. The SCAL-type indirect air-cooled system iron-aluminum corrosion monitoring system according to claim 5, characterized in that, The water quality data includes the pH value, iron and aluminum ion concentration, dissolved oxygen, chloride ion concentration, and conductivity of the circulating water.

7. The method for monitoring iron-aluminum corrosion in a SCAL-type indirect air-cooled system according to claim 5, characterized in that, The corrosion risk assessment model is as follows: in, As a corrosion risk index, This is the weighting coefficient for the linearly polarized resistance. The weighting coefficients for iron and aluminum ion concentrations are: The weighting factor for pH value, This is the weighting coefficient for chloride ion concentration. The weighting coefficients are the normalized values ​​of conductivity. This is the linear polarization resistance value. This refers to the concentration of iron and aluminum ions. pH value Chloride ion concentration, This is the normalized value of conductivity.

8. The method for monitoring iron-aluminum corrosion in a SCAL-type indirect air-cooled system according to claim 5, characterized in that, The corrosion risk assessment model was obtained using the following method: Acquire historical data, including historical circulating water quality data, historical aluminum oxide film damage data, and historical iron oxide film damage data; The historical data is preprocessed to obtain preprocessed historical data; The corrosion risk assessment model was obtained by fitting the preprocessed historical data using the least squares method.

9. The method for monitoring iron-aluminum corrosion in a SCAL-type indirect air-cooled system according to claim 8, characterized in that, It also includes the following steps: The corrosion risk assessment model was evaluated using k-fold cross-validation to obtain the prediction error; The prediction error includes mean square error and mean absolute error; The formula for calculating the mean square error is: The formula for calculating the mean absolute error is: Among them, the For the predicted value, the The actual observed values, the The mean square error is... For the mean absolute error, the This represents the number of samples.

10. The method for monitoring iron-aluminum corrosion in a SCAL-type indirect air-cooled system according to claim 8, characterized in that, The historical data is preprocessed to obtain preprocessed historical data, as follows: Obtain the standard deviation and mean of the historical data; Outlier data was identified using the 3σ criterion based on statistical methods, using standard deviation and mean. Linear interpolation can be used to fill in outliers or outliers can be estimated based on the characteristics of neighboring data points.

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