Oxygen-free oxygenation monitoring system and method for high-temperature section of thermal power plant

Abstract

The invention provides a thermal power plant high-temperature section oxygen-free oxygen adding monitoring system and method, and relates to the technical field of oxygen content monitoring, an error prediction model is constructed according to monitoring errors of oxygen content monitoring equipment at different accumulative flows, and therefore the real oxygen content in feed water is obtained; then oxygen is injected, a magnetic intensity curve of the high-temperature steam pipeline is obtained, the corresponding relation between the thickness of ferroferric oxide and the magnetic intensity is obtained through a laboratory, a pH value curve of discharged steam is obtained, and the oxygen content condition of the steam is judged and regulated; according to the oxygen regulation and control amount and the intensity curve, the modification amount at different accumulative flows is obtained, the monitoring error is modified, the system comprises a water supply oxygen content obtaining module, a rear-end monitoring module, an oxygen content analysis module and a modification module, and smooth generation of the ferroferric oxide oxidation layer is guaranteed in the mode that monitoring is conducted from the front end and the rear end respectively.

Description

Technical Field

[0001] The present invention relates to the technical field of oxygen content monitoring, and particularly to an oxygen addition monitoring system and method for the high-temperature section of a thermal power plant without oxygen. Background Technique

[0002] In the high-temperature section of a thermal power plant, due to the high-pressure and high-temperature condition of the high-temperature steam in the pipeline, it will cause certain corrosion to the pipeline. After deoxygenating the feed water and then adding a small amount of oxygen, controlling the oxygen content of the feed water at a certain level can make the feed water alkaline. When the high-pressure and high-temperature steam is transported in the pipeline, a dense oxide layer of magnetite will be formed on the inner wall of the pipeline. Although the oxide layer of magnetite is not thick, it has extremely strong anti-corrosion effect, greatly increasing the service life of the pipeline. However, when there is a deviation in the oxygen content of the feed water, whether the oxygen content is too high or too low, it will cause the oxide layer of magnetite to decrease and fall off, and may also generate particulate matter, affecting the life of the steam turbine. It is also possible that the oxygen injection amount meets the requirements, but in subsequent operations, due to reasons such as fluid model or insufficient oxygen dissolution, the formation process of the magnetite oxide layer is not smooth. Therefore, it is of great significance to monitor the oxygen content.

[0003] In the prior art, the publication number CN118113008A discloses an oxygen addition monitoring system and method for the high-temperature section of a thermal power plant without oxygen, including a sampling rack assembly for sampling at the inlet and outlet of the water wall; the data processing and evaluation unit includes a data extraction layer, a data processing layer, and an expert system layer; the data extraction layer is used to update the unit load data, feed water flow data, dissolved oxygen content, conductivity, and hydrogen conductivity data at the inlet of the economizer, as well as the dissolved oxygen content data at the inlet and outlet of the water wall in real time; the data processing layer is used to store the data in the data extraction layer, and use mathematical algorithms to compare with preset values and pre-alarm; at the same time, the data processing layer controls the automatic sewage discharge of the sampling rack assembly and the oxygen addition and ammonia addition of the feed water oxygen addition path under set working conditions; the expert system layer is respectively connected to the oxygen addition control platform and the data processing layer, and is used to comprehensively evaluate the corrosion situation of the thermal power plant unit, as well as the oxygen addition control accuracy and effect, and display the evaluation results on the oxygen addition control platform.

[0004] Although the disclosed technical document realizes the monitoring of the oxygen addition process, its monitoring of the oxygen addition process mainly focuses on the front-end monitoring, without considering the role of the added oxygen in the subsequent process, and cannot correct the monitoring error of the feed water oxygen content according to the actual effect of the magnetite oxide layer.

[0005] The above information disclosed in the background section is only used to enhance the understanding of the background of the present disclosure, so it may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0006] The object of the present invention is to provide a system and method for monitoring oxygenation in a high-temperature section of a thermal power plant without oxygen, so as to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: A method for monitoring oxygen addition in a high-temperature section of a thermal power plant without oxygen, comprising the following steps: Obtain the oxygen content error at different cumulative flow rates in the pipeline, form a training set and input it into the linear regression model to obtain the error prediction model, obtain the cumulative flow rate in the pipeline, input it into the error prediction model, and obtain the monitoring error of the oxygen content; Obtain the required oxygen content range and injected oxygen amount, obtain the magnetic strength curve of the high-temperature steam pipeline, obtain the corresponding relationship between the thickness of the ferroferric oxide layer and the magnetic strength through the laboratory, obtain the pH value curve of the exhaust steam, and calibrate the normal magnetic strength range and pH value change threshold; The thickness of the ferroferric oxide layer is determined by the magnetic intensity curve, and the change in the oxygen content of the steam is determined by combining the pH value curve. The amount of oxygen added is then regulated to obtain the oxygen control amount. The water supply volume in the pipeline is obtained, where the water supply volume is the water supply volume in the pipeline from the oxygen content data acquisition point to the magnetic data acquisition point. The monitoring error and the definition domain interval that cause the magnetic change are obtained. The modification amount at different cumulative flow rates is obtained according to the oxygen control amount and the magnetic intensity curve. The monitoring error is modified by the modification amount, and the modified monitoring error replaces the monitoring error before modification and is applied in subsequent monitoring.

[0008] Furthermore, the oxygen content acquisition device was tested in the experiment. When the experimental water with a fixed oxygen content passed through the pipe before the oxygenation section, the oxygen content data at different cumulative flow rates were measured, and the monitoring error at different cumulative flow rates was calculated based on the following formula: ; in, Indicates that the cumulative flow is The monitoring error is The oxygen content reading of the oxygen monitoring device, is the oxygen content of the experimental water with a fixed oxygen content; The accumulated traffic is aggregated to form a training set, and the monitoring error corresponding to the accumulated traffic is used as a label for training in a linear regression model. The trained model is calibrated as an error prediction model.

[0009] Further, obtain the oxygen content reading and the cumulative flow rate through an oxygen content monitoring device and a flow rate monitoring device respectively. The cumulative flow rate is the cumulative flow rate when the oxygen content monitoring device is overhauled. Input the cumulative flow rate into an error prediction model to obtain the monitoring error of the oxygen content, and plot the monitoring error of the oxygen content as a curve with the cumulative flow rate on the horizontal axis and the monitoring error of the oxygen content on the vertical axis. Obtain the true oxygen content at the end of the feed water system, and the basis formula is as follows: ; Wherein, is the true oxygen content at the end of the feed water system, is the monitoring error, is the oxygen content reading of the oxygen content monitoring device.

[0010] Further, inject oxygen to obtain the required oxygen content range. The required oxygen content range is the oxygen content range that the feed water is required to reach. Obtain the pipeline pressure, and according to the true oxygen content, obtain the injected oxygen amount. The basis formula is as follows: ; Wherein, is the injected oxygen amount, is the flow rate, is the pipeline pressure, is the molar mass of oxygen, is the ideal gas constant, is the lower limit of the required oxygen content range, is the upper limit of the required oxygen content range; Further, obtain the magnetic intensity of the high-temperature steam pipeline. The magnetic intensity is obtained through a magnetic monitoring device, and establish the corresponding relationship between the thickness of the magnetite oxide layer and the magnetic intensity. The basis formula is as follows: ; Wherein, is the magnetic intensity, is the thickness, is the corresponding function between the thickness and the magnetic intensity; Calibrate the normal thickness range of the magnetite oxide layer and the corresponding normal magnetic intensity range in the laboratory; Obtain the magnetic intensity curve of the pipeline at the back end of the superheater. The abscissa of the magnetic intensity curve is the cumulative flow rate, and the ordinate is the magnetic intensity; Obtain the pH value curve of the discharged steam. The pH value curve is obtained through the fiber optic pH sensor at the end, and the abscissa of the pH value curve is the cumulative flow rate, and the ordinate is the pH value.

[0011] Further, analyze the magnetic curve, set the change threshold of the pH value, and the analysis logic is as follows: When the magnetic intensity is lower than the normal magnetic intensity range, the pH value is judged. If the change amount of the pH value exceeds the change threshold, it means that the oxygen content in the high-temperature section steam is insufficient. If the change amount of the pH value is lower than the change threshold, it means that the oxygen content in the high-temperature section steam exceeds the standard. Obtain the cumulative flow range in the magnetic intensity decline interval and the decline rate curve in the magnetic intensity decline interval. The basis formula is as follows: ; Among them, represents the decline rate when the cumulative flow is , is the magnetic intensity, is the cumulative flow; When the oxygen content in the high-temperature steam is insufficient, oxygen is injected. When the oxygen content in the steam exceeds the standard, the oxygen injection amount is reduced until the magnetic intensity returns to the middle value of the normal magnetic intensity range, and the regulation amount of oxygen is recorded.

[0012] Furthermore, obtain the feed water volume in the pipeline through design data. The feed water volume is the feed water volume in the pipeline from the oxygen content data acquisition point to the magnetic data acquisition point. Obtain the monitoring error causing magnetic change. The acquisition logic is as follows: The flow rate and oxygen content are obtained at the front end of the feed water pump, so as to obtain the monitoring error in the current state. The true oxygen content is obtained based on the current monitoring error. Oxygen is injected according to the current true oxygen content. According to the data obtained by the magnetoresistive sensor, it is the part of the feed water injected with oxygen at that time that reaches the magnetic data acquisition point, so that the change in the thickness of the magnetite oxide layer is monitored. The monitoring error causing magnetic change is the current monitoring error; Obtain the domain interval of the monitoring error causing magnetic change. The basis formula is as follows: ; Among them, is the starting point of the domain interval, is the starting point of the cumulative flow range in the magnetic intensity decline interval, is the volume of the feed water from the feed water pump to the magnetoresistive sensor, is the end point of the domain interval, is the end point of the cumulative flow range in the magnetic intensity decline interval, .

[0013] Furthermore, modify the monitoring error within the domain interval, set the modification amount at different cumulative flows. The horizontal axis of the modification amount is the cumulative flow, and the vertical axis is the modification amount value. The basis formula is as follows: ; Among them, , represents the modification amount when the cumulative flow is , The oxygen regulation amount recorded for the PID control system is the flow rate is the pipeline pressure is the molar mass of oxygen is the ideal gas constant; Meanwhile, the modification amount within the domain interval also satisfies the formula: ; wherein represents the modification amount when the cumulative flow rate is ; represents the decreasing rate when the cumulative flow rate is ; In MATLAB, solve for the modification amount within the domain interval .

[0014] Furthermore, modify the monitoring error within the domain interval according to the modification amount, and the basis formula is as follows: ; wherein is the monitoring error before adjustment is the monitoring error after adjustment is the modification amount; Replace the monitoring error before adjustment with the monitoring error after adjustment and apply it to subsequent monitoring. When the magnetic strength is lower than the normal magnetic strength range again during subsequent monitoring, adjust the monitoring error of the corresponding domain interval again.

[0015] The present invention also includes an oxygen addition monitoring system for the oxygen-free high-temperature section of a thermal power plant, which is used to execute the above-mentioned oxygen addition monitoring method for the oxygen-free high-temperature section of a thermal power plant, including: A feed water oxygen content acquisition module, which is used to acquire the oxygen content error at different cumulative flow rates in the pipeline, form a training set and input it into a linear regression model to obtain an error prediction model, acquire the cumulative flow rate in the pipeline, input it into the error prediction model, and obtain the monitoring error of the oxygen content; A backend monitoring module, which is used to acquire the required oxygen content interval and the injected oxygen amount, acquire the magnetic strength curve of the high-temperature steam pipeline, obtain the corresponding relationship between the thickness of the magnetite oxide layer and the magnetic strength through the laboratory, acquire the pH value curve of the discharged steam, and calibrate the normal magnetic strength range and the change threshold of the pH value; An oxygen content analysis module, which is used to judge the thickness of the magnetite oxide layer through the magnetic strength curve, combine the pH value curve to judge the change of the oxygen content in the steam, and regulate the injected oxygen amount to obtain the oxygen regulation amount; A modification module is used to obtain the volume of feed water in the pipeline. The volume of feed water is the volume of feed water in the pipeline from the oxygen content data acquisition point to the magnetic data acquisition point. It obtains the monitoring error and the domain interval that cause magnetic changes, and obtains the modification amount at different cumulative flow rates according to the oxygen regulation amount and the magnetic intensity curve. The monitoring error is modified by the modification amount, and the modified monitoring error is used to replace the monitoring error before modification and applied to subsequent monitoring.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention constructs an error prediction model through experimental methods, obtains the monitoring error and the true oxygen content of the oxygen content according to the actual cumulative flow rate, and injects oxygen. It judges the oxygen content according to the changes in the thickness of the magnetite oxide layer and the pH value during the actual process, and obtains the modification amount for the monitoring error. By modifying the monitoring error, the stability of the final magnetite oxide layer is ensured. The present invention ensures the control of the feed water oxygen content through the prediction model, and further optimizes the monitoring of the feed water oxygen content through the actual changes in the oxide layer, ensuring the smooth formation of the magnetite oxide layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall method flow of the present invention; Figure 2 It is a schematic diagram of the system composition of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the following further details the present invention with reference to specific embodiments.

[0019] It should be noted that unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meaning understood by those with ordinary skills in the field to which the present invention belongs. The "first", "second", and similar terms used in the present invention do not indicate any order, quantity, or importance, but are only used to distinguish different components. The terms such as "including" or "comprising" mean that the elements or objects appearing before this term cover the elements or objects listed after this term and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0020] Embodiment:

[0021] Please refer to Figure 1 , the present invention provides a technical solution: A method for monitoring oxygen addition in a high-temperature section of a thermal power plant without oxygen, comprising the following steps: Step 1: Obtain the oxygen content error at different cumulative flow rates in the pipeline, form a training set and input it into the linear regression model to obtain the error prediction model. Obtain the cumulative flow rate in the pipeline, input it into the error prediction model, and obtain the monitoring error of the oxygen content. The step 1 includes the following: Step 101: The oxygen content acquisition device is tested in an experiment. When experimental water with a fixed oxygen content passes through the pipe before the oxygenation section, the oxygen content data at different cumulative flow rates through the pipe are measured, and the monitoring error at different cumulative flow rates is calculated based on the following formula: ; in, Indicates that the cumulative flow is The monitoring error is The oxygen content reading of the oxygen monitoring device, is the oxygen content of the experimental water with a fixed oxygen content; Among them, under different cumulative flow conditions, due to the continuous aging of the oxygen content monitoring equipment sensor, the monitoring error of the oxygen content of the accumulated water may become larger and larger. The monitoring error of the electrochemical sensor is obtained by subtracting the oxygen content of the experimental water itself from the oxygen content reading.

[0022] The accumulated traffic is aggregated to form a training set, and the monitoring error corresponding to the accumulated traffic is used as a label for training in a linear regression model. The trained model is calibrated as an error prediction model.

[0023] By simulating the error of oxygen monitoring equipment at different cumulative flow rates in the laboratory, a linear relationship model between error and cumulative flow rate was established. This model can predict the reading deviation caused by long-term use (such as diaphragm aging and electrolyte depletion) in actual operation of oxygen monitoring equipment, providing basic data for subsequent real-time correction. This process effectively solves the problem of traditional oxygen monitoring equipment gradually losing accuracy with increasing cumulative flow rate, ensures the dynamic adaptability of the error prediction model, and thus improves the long-term reliability of oxygen monitoring.

[0024] Step 102: Obtain oxygen content readings and cumulative flow rates through the oxygen content monitoring device and the flow rate monitoring device, respectively. The cumulative flow rate is the cumulative flow rate when the oxygen content monitoring device is under maintenance. The cumulative flow rate is input into the error prediction model to obtain the oxygen content monitoring error. The oxygen content monitoring error is plotted as a curve with the cumulative flow rate on the horizontal axis and the oxygen content monitoring error on the vertical axis. The actual oxygen content at the end of the water supply system is obtained based on the following formula: ; in, is the actual oxygen content at the end of the water supply system, For monitoring errors, is the oxygen content reading of the oxygen content monitoring device.

[0025] Combining the oxygen content reading of the oxygen content monitoring device and the cumulative flow in real time, and dynamically calculating the true oxygen content using the error prediction model. Reset the cumulative flow each time the electrolyte or diaphragm is replaced to avoid interference from historical error data with the working state of new components.

[0026] Step 2: Obtain the required oxygen content range and the injected oxygen volume, obtain the magnetic intensity curve of the high-temperature steam pipeline, obtain the corresponding relationship between the thickness of the magnetite oxide layer and the magnetic intensity through the laboratory, obtain the pH value curve of the discharged steam, and calibrate the normal magnetic intensity range and the change threshold of the pH value; The said Step 2 includes the following contents: Step 201: Inject oxygen and obtain the required oxygen content range. The required oxygen content range is the oxygen content range that the feed water is required to reach. Obtain the pipeline pressure, and obtain the injected oxygen volume according to the true oxygen content. The formula is as follows: ; Among them, is the injected oxygen volume, is the flow rate, is the pipeline pressure, is the molar mass of oxygen, is the ideal gas constant, is the lower limit of the required oxygen content range, is the upper limit of the required oxygen content range; Among them, the oxygen content in the feed water is constructed through the gas dissolution model. The greater the pressure, the higher the dissolution rate of the injected oxygen, which is reflected as a higher oxygen content in the feed water. The greater the flow rate, the more solvent, which is reflected as a lower oxygen content in the feed water. And this oxygen content is the theoretical oxygen content. The feed water may not be able to fully dissolve oxygen during subsequent operation, resulting in the actual oxygen content of the feed water not reaching the required oxygen content range, leaving a hidden danger for the formation of the magnetite oxide layer in the future.[[ID=q34]]

[0027] Dynamically adjust the oxygen injection volume based on the true oxygen content to ensure that the oxygen content of the feed water is always within the range required by the process. By calculating the injection volume formulaically, the system can accurately control the oxygen addition, avoiding pipeline corrosion caused by excessive oxygen addition or abnormal formation of the oxide layer due to insufficient oxygen content. The injected water is fully mixed by a static mixer and then forms uniform superheated steam through a superheater.

[0028] Step 202: Obtain the magnetic intensity of the high-temperature steam pipeline. The magnetic intensity is obtained through a magnetic monitoring device, and the corresponding relationship between the thickness of the magnetite oxide layer and the magnetic intensity is constructed. The formula is as follows: ; Among them, is the magnetic strength, is the thickness, is the corresponding function of the thickness and the magnetic strength; Calibrate the normal thickness range of the magnetite oxide layer and the corresponding normal magnetic strength range in the laboratory; Obtain the magnetic strength curve of the pipeline at the back end of the superheater, where the abscissa of the magnetic strength curve is the cumulative flow rate and the ordinate is the magnetic strength; Obtain the pH value curve of the discharged steam, which is obtained by the fiber optic pH sensor at the end. The abscissa of the pH value curve is the cumulative flow rate and the ordinate is the pH value.

[0029] Establish the corresponding relationship between the thickness of the magnetite oxide layer and the magnetic strength of the pipeline through experiments, providing a direct basis for real-time monitoring of the oxide layer state. The magnetoresistive sensor continuously collects the magnetic data of the pipeline. Combining with the normal magnetic strength range calibrated in the laboratory, the system can quickly identify abnormal thickness of the oxide layer (such as too thin or too thick). At the same time, the fiber optic pH sensor monitors the pH value curve of the discharged steam, forming a two-parameter feedback of magnetic strength and pH value, enhancing the indirect judgment ability of the oxygen content change in the high-temperature section steam, and realizing early warning.

[0030] Step 3: Judge the thickness of the magnetite oxide layer through the magnetic strength curve, combine with the pH value curve to judge the change of the oxygen content in the steam, and adjust the oxygen injection amount to obtain the oxygen regulation amount; The said Step 3 includes the following contents: Step 301: Analyze the magnetic curve, set the change threshold of the pH value, and the analysis logic is as follows: When the magnetic strength is lower than the normal magnetic strength range, judge the pH value. If the change amount of the pH value exceeds the change threshold, it means that the oxygen content in the high-temperature section steam is insufficient. If the change amount of the pH value is lower than the change threshold, it means that the oxygen content in the high-temperature section steam exceeds the standard; Obtain the cumulative flow rate range in the magnetic strength decline interval and the decline rate curve in the magnetic strength decline interval. The basis formula is as follows: ; Among them, represents the decline rate when the cumulative flow rate is , is the magnetic strength, is the cumulative flow rate; The rate of the magnetic strength decline curve in the decline interval reflects the deviation of the oxygen content in the feed water. The greater the deviation of the oxygen content in the feed water from the required oxygen content interval, the faster the magnetite oxide layer is damaged, which is reflected as a smaller value of the decline rate.

[0031] When the oxygen content in the high-temperature steam is insufficient, oxygen is injected. When the oxygen content in the steam exceeds the standard, the oxygen injection amount is reduced until the magnetic strength returns to the middle value of the normal magnetic strength range, and the regulation amount of oxygen is recorded.

[0032] Combined with the magnetic strength curve and the pH value change threshold, the oxygen content state of the steam can be judged. When the magnetic strength is lower than the normal range and the pH value change exceeds the threshold, it is judged that the oxygen content is insufficient, and the PID control system is immediately started to increase the oxygen injection; if the magnetic strength is abnormal but the pH value change does not exceed the threshold, it is judged that the oxygen content exceeds the standard, and the oxygen injection is reduced. By analyzing the magnetic decline rate, the control parameters are dynamically adjusted to ensure that the oxygen content in the high-temperature section of the steam quickly returns to the equilibrium state and reduce the risk of equipment loss.

[0033] Step 4: Obtain the feed water volume in the pipeline. The feed water volume is the feed water volume in the pipeline from the oxygen content data acquisition point to the magnetic data acquisition point. Obtain the monitoring error and the domain interval that cause the magnetic change. According to the oxygen regulation amount and the magnetic strength curve, obtain the modification amount at different cumulative flow rates. Modify the monitoring error with the modification amount, and replace the modified monitoring error with the unmodified one for subsequent monitoring.

[0034] The said Step 4 includes the following contents: Step 401: Obtain the feed water volume in the pipeline through design data. The feed water volume is the feed water volume in the pipeline from the oxygen content data acquisition point to the magnetic data acquisition point. Obtain the monitoring error that causes the magnetic change. The obtaining logic is as follows: The flow rate and the oxygen content are obtained, so as to obtain the monitoring error in the current state. Based on the current monitoring error, the true oxygen content is obtained. Oxygen is injected according to the current true oxygen content. According to the data obtained by the magnetoresistive sensor, it is the part of the feed water where oxygen is injected at that time that reaches the magnetic data acquisition point, so that the change in the thickness of the magnetite oxide layer is monitored. The monitoring error that causes the magnetic change is the current monitoring error; Obtain the domain interval of the monitoring error that causes the magnetic change. The formula is as follows: ; Among them, is the starting point of the domain interval, is the starting point of the cumulative flow rate range of the magnetic strength decline interval, is the volume of the feed water from the feed water pump to the magnetoresistive sensor, is the end point of the domain interval, is the end point of the cumulative flow rate range of the magnetic strength decline interval, .

[0035] The pipes involved in obtaining the feed water volume data include the pipes for high-temperature steam. Although the volume of high-temperature steam needs to be converted to obtain the corresponding accumulated water volume, the conversion method can be obtained from the design log of thermal power. Through the calculation of the feed water volume and the backtracking of the cumulative flow rate, accurately locate the historical time period corresponding to the monitoring error that causes the magnetic change. This step correlates the abnormal oxide layer detected by the magnetoresistive sensor with the previous monitoring error data, clarifies the range of the cumulative flow rate that needs to be corrected, provides an accurate time window and data source for subsequent error adjustment, and avoids the waste of resources for global correction.

[0036] Step 402: Modify the monitoring error within the defined domain interval, and set the modification amount at different cumulative flow rates. The horizontal axis of the modification amount is the cumulative flow rate, and the vertical axis is the modification amount value. The formula is as follows: ; Where, , represents the modification amount when the cumulative flow rate is , is the oxygen regulation amount recorded by the PID control system, is the flow rate, is the pipe pressure, is the molar mass of oxygen, is the ideal gas constant; The feed water may have inaccurate oxygen injection amount at the feed pump due to the excessive reading deviation of the oxygen content monitoring equipment, or it may be due to insufficient oxygen dissolution during the subsequent operation of the feed water. However, these reasons do cause the oxygen content deviation in the final link of the feed water. The amount of oxygen adjustment required for the deviated oxygen content is reflected by the oxygen regulation amount recorded by the PID control system. Converting the oxygen regulation amount into the oxygen content can represent the oxygen content deviation of the feed water caused by various reasons. Feedback this converted oxygen content to the prediction deviation, and adjust the oxygen injection amount at the feed pump from the prediction deviation link to ensure that the oxygen content in the high-temperature section meets the standard directly without relying on the PID control system during the subsequent operation of the feed water. The greater the oxygen regulation amount, the greater the total amount of the modification amount.

[0037] At the same time, the modification amount within the defined domain interval also satisfies the formula: ; Where, represents the modification amount when the cumulative flow rate is , represents the decline rate when the cumulative flow rate is ; After determining the total amount of the modification, it is necessary to distribute the total amount within the domain interval. Since the decline rate represents the deviation of the oxygen content in the feed water, and the derivative of the decline rate represents the change of the deviation, and the change of the deviation is the derivative of the modification curve with respect to the cumulative flow. By comparing the change of the decline rate and the deviation, the distribution of the modification is realized. The faster the decline rate changes, the faster the deviation modification amount should increase. Whether the deviation modification amount is positive or negative has been determined by the oxygen adjustment amount, so only the absolute value is used to reflect the change rate here.

[0038] For the modification amount in MATLAB within the domain interval to solve.

[0039] Taking the two formulas related to the modification amount in this step as the limiting conditions, setting the modification amount as a linear combination of basis functions, and solving by the least squares method to obtain the specific modification curve.

[0040] Based on the oxygen regulation amount and the magnetic decline rate recorded by PID regulation, through integral constraint and differential constraint, solve the modification amount of the monitoring error within the domain interval. This process uses a mathematical model to ensure that the corrected error completely matches the actual magnetic change, eliminates the subjectivity of empirical adjustment, makes the correction result conform to physical laws, and can effectively offset the influence of historical errors on subsequent monitoring.

[0041] Step 403: Modify the monitoring error within the domain interval according to the modification amount, and the basis formula is as follows: ; Among them, is the monitoring error before adjustment, is the monitoring error after adjustment, is the modification amount; Replace the monitoring error before adjustment with the monitoring error after adjustment and apply it to subsequent monitoring. When the magnetic strength is lower than the normal magnetic strength range again during subsequent monitoring, adjust the monitoring error of the corresponding domain interval again.

[0042] Dynamically update the error prediction model, replace the original error data with the corrected monitoring error, and form a closed-loop feedback. When the magnetic strength is abnormal again during subsequent monitoring, the system automatically triggers a new round of correction to continuously optimize the model accuracy. This mechanism enables the system to adapt to interference factors such as sensor aging and water quality changes during long-term operation, significantly improves the stability and anti-interference ability of the monitoring model, and ensures the long-term effectiveness of the oxygen addition monitoring in the high-temperature section of the thermal power plant. Please refer to Figure 2 : The present invention further includes an oxygen addition monitoring system for the high-temperature section without oxygen in a thermal power plant, which is used to execute the above-mentioned oxygen addition monitoring method for the high-temperature section without oxygen in a thermal power plant, including: The feed water oxygen content acquisition module is used to acquire the oxygen content error at different cumulative flow rates in the pipeline, form a training set and input it into a linear regression model to obtain an error prediction model, acquire the cumulative flow rate in the pipeline, input it into the error prediction model, and obtain the monitoring error of the oxygen content; The backend monitoring module is used to acquire the required oxygen content range and the injected oxygen volume, acquire the magnetic intensity curve of the high-temperature steam pipeline, obtain the corresponding relationship between the thickness of the magnetite oxide layer and the magnetic intensity through the laboratory, acquire the pH value curve of the discharged steam, and calibrate the normal magnetic intensity range and the change threshold of the pH value; The oxygen content analysis module is used to judge the thickness of the magnetite oxide layer through the magnetic intensity curve, combine the pH value curve to judge the change of the oxygen content in the steam, and adjust the injected oxygen volume to obtain the oxygen regulation amount; The modification module is used to acquire the feed water volume in the pipeline, where the feed water volume is the feed water volume in the pipeline from the oxygen content data acquisition point to the magnetic data acquisition point, acquire the monitoring error and the domain interval that cause magnetic changes, obtain the modification amount at different cumulative flow rates according to the oxygen regulation amount and the magnetic intensity curve, modify the monitoring error through the modification amount, and replace the modified monitoring error with the unmodified one for subsequent monitoring.

[0043] The above formulas are all dimensionless and take their numerical values for calculation. The formula is obtained by collecting a large amount of data and performing software simulation to get a formula that is closest to the actual situation. The preset parameters in the formula are set by those skilled in the art according to the actual situation.

[0044] The above embodiments can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. Those skilled in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or by the combination of computer software and electronic hardware. Whether these functions are executed by hardware or software methods depends on the specific application and design constraints of the technical solution.

[0045] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units. They can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0046] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application.

Claims

1. An oxygen addition monitoring method for the high-temperature section of a thermal power plant without oxygen, characterized in that, The specific steps include: Obtain the oxygen content monitoring errors at different cumulative flows in the pipeline, form a training set and input it into a linear regression model to obtain an error prediction model. Obtain the cumulative flow in the pipeline, input it into the error prediction model to obtain the monitoring error of the oxygen content. Obtain the magnetic intensity curve of the high-temperature steam pipeline, obtain the corresponding relationship between the thickness of the magnetite oxide layer and the magnetic intensity, obtain the pH value curve of the discharged steam, and calibrate the normal magnetic intensity range and the change threshold of the pH value. Judge the thickness of the magnetite oxide layer through the magnetic intensity curve, combine the pH value curve to judge the change of the oxygen content in the steam, and adjust the oxygen injection amount to obtain the oxygen adjustment amount. Obtain the feed water volume in the pipeline. The feed water volume is the feed water volume in the pipeline from the oxygen content data acquisition point to the magnetic data acquisition point. Obtain the monitoring error and the domain interval that cause the magnetic change. According to the oxygen adjustment amount and the magnetic intensity curve, obtain the modification amount at different cumulative flows, modify the monitoring error through the modification amount, and replace the modified monitoring error with the unmodified one for subsequent monitoring.

2. The oxygen addition monitoring method for the high-temperature section of a thermal power plant without oxygen according to claim 1, characterized in that: The oxygen content acquisition device is experimented in the experiment. When the experimental water with a fixed oxygen content passes through the pipeline before the oxygen addition section, the oxygen content data when different cumulative flows pass through the pipeline are measured respectively, and the monitoring errors at different cumulative flows are calculated. The basis formula is as follows: ; Among them, represents the monitoring error at the cumulative flow rate of ; is the measured oxygen content reading, is the oxygen content of the experimental water with a fixed oxygen content; Summarize the cumulative flow to form a training set, use the monitoring error corresponding to the cumulative flow as a label, and train it in a linear regression model. Calibrate the trained model as an error prediction model.

3. The oxygen addition monitoring method for the high-temperature section without oxygen in a thermal power plant according to claim 2, characterized in that: Obtain the oxygen content reading and the cumulative flow rate through an oxygen content monitoring device and a flow rate monitoring device respectively. The cumulative flow rate is the cumulative flow rate through the pipeline before the oxygen addition section since the overhaul of the oxygen content monitoring device. Input the cumulative flow rate into an error prediction model to obtain the monitoring error of the oxygen content, and plot the monitoring error of the oxygen content as a curve with the cumulative flow rate on the horizontal axis and the monitoring error of the oxygen content on the vertical axis. Obtain the true oxygen content at the end of the feed water system, and the basis formula is as follows: ; Among them, is the true oxygen content at the end of the water supply system, is the monitoring error, is the oxygen content reading of the oxygen content monitoring device.

4. A method for monitoring oxygen addition in the high-temperature section of a thermal power plant without oxygen, characterized in that: Inject oxygen to obtain the required oxygen content range, where the required oxygen content range is the oxygen content range that the feed water is required to reach. Obtain the pipeline pressure and, based on the actual oxygen content, obtain the injected oxygen amount. The formula is as follows: ; Among them, is the amount of oxygen injected, is the flow rate, is the pipeline pressure, is the molar mass of oxygen, is the ideal gas constant, is the lower limit of the required oxygen content range, is the upper limit of the required oxygen content range.

5. The oxygen addition monitoring method for the high-temperature section of a thermal power plant without oxygen according to claim 4, characterized in that: Obtain the magnetic strength of the high-temperature steam pipeline, which is obtained by a magnetic monitoring device, and establish the corresponding relationship between the thickness of the magnetite oxide layer and the magnetic strength. The basis formula is as follows: ; Among them, is the magnetic strength, is the thickness, is the corresponding function of the thickness and the magnetic strength; Calibrate the normal thickness range of the magnetite oxide layer and the corresponding normal magnetic intensity range in the laboratory. Obtain the magnetic intensity curve of the pipeline at the back end of the superheater. The abscissa of the magnetic intensity curve is the cumulative flow, and the ordinate is the magnetic intensity. Obtain the pH value curve of the discharged steam. The pH value curve is obtained by the fiber optic pH sensor at the end. The abscissa of the pH value curve is the cumulative flow, and the ordinate is the pH value.

6. The oxygen addition monitoring method for the high-temperature section without oxygen in a thermal power plant according to claim 5, characterized in that: Analyze the magnetic curve, set the change threshold of the pH value, and the analysis logic is as follows: When the magnetic intensity is lower than the normal magnetic intensity range, judge the pH value. If the change amount of the pH value exceeds the change threshold, it means that the oxygen content in the high-temperature section steam is insufficient. If the change amount of the pH value is lower than the change threshold, it means that the oxygen content in the high-temperature section steam exceeds the standard. Obtain the cumulative flow range in the magnetic strength decline interval and the decline rate curve within the magnetic strength decline interval. The formulas are as follows: ; Among them, represents the decline rate when the cumulative flow rate is , is the magnetic strength, is the cumulative flow rate; Inject oxygen when the oxygen content in the high-temperature steam is insufficient, and reduce the oxygen injection amount when the oxygen content in the steam exceeds the standard until the magnetic intensity returns to the middle value of the normal magnetic intensity range, and record the oxygen adjustment amount.

7. A method for monitoring oxygen addition in the high-temperature section of a thermal power plant without oxygen, according to claim 6, characterized in that: Obtain the feed water volume in the pipeline through design data. The feed water volume is the feed water volume in the pipeline from the oxygen content data acquisition point to the magnetic data acquisition point. Obtain the monitoring error that causes the magnetic change. The acquisition logic is as follows: The flow rate and oxygen content are obtained at the front end of the feed water pump, so as to obtain the monitoring error in the current state. Obtain the true oxygen content based on the current monitoring error, inject oxygen according to the current true oxygen content. According to the data obtained by the magnetoresistive sensor, it is the part of the feed water that was injected with oxygen at that time that reaches the magnetic data acquisition point, so that the change in the thickness of the magnetite oxide layer is monitored. The monitoring error that causes the magnetic change is the current monitoring error. To obtain the domain interval of the monitoring error that causes magnetic changes, the formula is as follows: ; Among them, is the starting point of the domain interval, is the starting point of the cumulative flow range of the magnetic strength decline interval, is the volume of the feed water from the feed water pump to the magnetoresistive sensor, is the ending point of the domain interval, is the ending point of the cumulative flow range of the magnetic strength decline interval, .

8. A method for monitoring oxygen addition in the high-temperature section of a thermal power plant without oxygen, characterized in that: Modify the monitoring error within the defined domain interval, and set the modification amount at different cumulative flows. The horizontal axis of the modification amount is the cumulative flow, and the vertical axis is the modification amount value. The formula is as follows: ; Among them, , represents the modification amount at the cumulative flow rate of , is the oxygen regulation amount recorded by the PID control system, is the flow rate, is the pipeline pressure, is the molar mass of oxygen, is the ideal gas constant; Meanwhile, the modification amount within the domain interval also satisfies the formula: ; Among them, represents the modification amount at the cumulative flow rate of , represents the decreasing rate at the cumulative flow rate of . Solve for the modification amount in MATLAB in the domain interval for the solution.

9. The oxygen addition monitoring method for the high-temperature section without oxygen in a thermal power plant according to claim 8, characterized in that: Modify the monitoring error within the domain interval according to the modification amount. The formula is as follows: ； Among them, is the monitoring error before adjustment, is the monitoring error after adjustment, is the modification amount; Replace the monitoring error before adjustment with the adjusted monitoring error and apply it to subsequent monitoring. When the magnetic strength is lower than the normal magnetic strength range again during subsequent monitoring, adjust the monitoring error of the corresponding domain interval again.

10. An oxygen addition monitoring system for the high-temperature section of a thermal power plant without oxygen, the system being used to execute an oxygen addition monitoring method for the high-temperature section of a thermal power plant without oxygen according to any one of claims 1-9, characterized in that, Including: An oxygen content acquisition module, which is used to acquire the oxygen content error at different cumulative flow rates in the pipeline, form a training set and input it into a linear regression model to obtain an error prediction model, acquire the cumulative flow rate in the pipeline, input it into the error prediction model, and obtain the monitoring error of the oxygen content. A back-end monitoring module, which is used to acquire the required oxygen content interval and the oxygen injection amount, acquire the magnetic strength curve of the high-temperature steam pipeline, obtain the corresponding relationship between the thickness of the magnetite oxide layer and the magnetic strength through the laboratory, acquire the pH value curve of the discharged steam, and calibrate the normal magnetic strength range and the change threshold of the pH value. An oxygen content analysis module, which is used to judge the thickness of the magnetite oxide layer through the magnetic strength curve, combine the pH value curve to judge the change of the oxygen content in the steam, and adjust the oxygen injection amount to obtain the oxygen regulation amount. A modification module, which is used to acquire the feed water volume in the pipeline. The feed water volume is the feed water volume in the pipeline from the oxygen content data acquisition point to the magnetic data acquisition point, acquire the monitoring error and the domain interval that cause magnetic changes, obtain the modification amount at different cumulative flow rates according to the oxygen regulation amount and the magnetic strength curve, modify the monitoring error through the modification amount, and replace the monitoring error before modification with the modified monitoring error and apply it to subsequent monitoring.

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