A system and method for monitoring oxygen addition in a high-temperature section of a thermal power plant without oxygen

Abstract

The present invention provides an oxygen-free oxygenation monitoring system and method for a high-temperature section of a thermal power plant, relating to the technical field of oxygen content monitoring. An error prediction model is constructed based on the monitoring error of an oxygen content monitoring device at different cumulative flow rates, thereby obtaining the actual oxygen content in the feed water. Oxygen is then added and a magnetic strength curve of a high-temperature steam pipeline is obtained. The corresponding relationship between the thickness and magnetic strength of ferroferric oxide is obtained in a laboratory, a pH value curve of the discharged steam is obtained, the oxygen content of the steam is judged and regulated, and a modification amount at different cumulative flow rates is obtained based on the oxygen regulation amount and this strength curve, and the monitoring error is modified. The system includes a feed water oxygen content acquisition module, a back-end monitoring module, an oxygen content analysis module, and a modification module. The present invention ensures the smooth formation of a ferroferric oxide oxide layer by monitoring the front and back ends separately.

Description

Technical Field

[0001] The present invention relates to the technical field of oxygen content monitoring, in particular to an oxygen-free oxygenation monitoring system and method for a high-temperature section of a thermal power plant. Background Art

[0002] In the high-temperature section of a thermal power plant, the high-temperature steam in the pipeline is under high pressure and high temperature, which will cause certain corrosion to the pipeline. After deoxygenation, a small amount of oxygen is added to the feed water to control the oxygen content of the feed water at a certain level, which can make the feed water alkaline. When the high-temperature and high-pressure steam is transported in the pipeline, a dense oxide layer of ferroferric oxide will be formed on the inner wall of the pipeline. Although the oxide layer of ferroferric oxide is not thick, it has a strong anti-corrosion effect and greatly increases the service life of the pipeline. However, when the oxygen content in the feed water deviates, whether the oxygen content is too high or too low, the oxide layer of ferroferric oxide will decrease and fall off, and particulate matter may be generated to affect the life of the turbine. It is also possible that the oxygen injection amount meets the requirements, but in subsequent operation, the fluid model or insufficient oxygen dissolution will cause the formation process of the ferroferric oxide layer to be not smooth. Therefore, it is of great significance to monitor the oxygen content.

[0003] In the prior art, publication number CN118113008A discloses a system and method for monitoring oxygenation in the high-temperature section of a thermal power plant without oxygen. The system comprises a sampling rack assembly for sampling at the inlet and outlet of a water-cooled wall; a data processing and evaluation unit comprising a data extraction layer, a data processing layer, and an expert system layer; the data extraction layer is used to update in real time the load data of the thermal power plant units, feed water flow data, dissolved oxygen content, conductivity, and hydrogen conductivity data at the economizer inlet, and dissolved oxygen content data at the water-cooled wall inlet and outlet; the data processing layer is used to store the data in the data extraction layer and compare it with preset values ​​using mathematical algorithms and issue pre-alarms; the data processing layer also controls the automatic drainage of the sampling rack assembly and the addition of oxygen and ammonia to the feed water oxygenation passage under set operating conditions; the expert system layer is connected to the oxygenation control platform and the data processing layer, respectively, and is used to comprehensively evaluate the corrosion status of the thermal power plant units and the accuracy and effectiveness of oxygenation control, and to display the evaluation results on the oxygenation control platform.

[0004] Although the public technical documents have achieved monitoring of the oxygenation process, their monitoring of the oxygenation process mainly focuses on front-end monitoring. They do not take into account the role of the added oxygen in subsequent processes, and cannot correct the monitoring error of the oxygen content in the water supply based on the actual effect of the ferroferric oxide layer.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person 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:

[0008] A method for monitoring oxygen addition in a high-temperature section of a thermal power plant without oxygen, comprising the following steps:

[0009] 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;

[0010] 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;

[0011] 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.

[0012] 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.

[0013] 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: ;

[0014] 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;

[0015] 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.

[0016] Furthermore, oxygen content readings and cumulative flow rates are obtained 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 overhauled. 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 into a curve with the horizontal axis being the cumulative flow rate and the vertical axis being the oxygen content monitoring error. The actual oxygen content at the end of the water supply system is obtained based on the following formula: ;

[0017] in, is the actual oxygen content at the end of the water supply system, To monitor the error, This is the oxygen content reading from the oxygen monitoring device.

[0018] Furthermore, oxygen is added to obtain the required oxygen content range, which is the oxygen content range required for the water supply. The pipeline pressure is obtained, and the injected oxygen amount is obtained according to the actual oxygen content. The formula is as follows:

[0019] ;

[0020] in, The amount of oxygen injected, For traffic, 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, The upper limit of the required oxygen content range;

[0021] Furthermore, the magnetic strength of the high-temperature steam pipe is obtained by a magnetic monitoring device, and a corresponding relationship between the thickness of the ferroferric oxide layer and the magnetic strength is established according to the following formula: ;

[0022] in, is the magnetic strength, is the thickness, is the corresponding function of thickness and magnetic strength;

[0023] The normal thickness range of the ferroferric oxide layer and the corresponding normal magnetic intensity range are calibrated in the laboratory;

[0024] Obtain a magnetic intensity curve of the pipeline at the rear end of the superheater, wherein the horizontal axis of the magnetic intensity curve represents the accumulated flow rate and the vertical axis represents the magnetic intensity;

[0025] The pH value curve of the discharged steam is obtained by the optical fiber pH sensor at the end. The horizontal axis of the pH value curve is the accumulated flow rate, and the vertical axis is the pH value.

[0026] Furthermore, the magnetic curve is analyzed and the pH value change threshold is set. The analysis logic is as follows:

[0027] When the magnetic strength is lower than the normal magnetic strength range, the pH value is judged. If the pH value change exceeds the change threshold, it means that the oxygen content of the high-temperature steam is insufficient. If the pH value change is lower than the change threshold, it means that the oxygen content of the high-temperature steam exceeds the standard.

[0028] The cumulative flow range in the magnetic intensity decrease interval and the decrease rate curve in the magnetic intensity decrease interval are obtained based on the following formula: ;

[0029] in, Indicates the cumulative flow rate is The rate of descent, is the magnetic strength, is the cumulative flow;

[0030] When the oxygen content of high-temperature steam is insufficient, add oxygen; when the oxygen content of steam exceeds the standard, reduce the amount of oxygen injected until the magnetic strength returns to the middle value of the normal magnetic strength range, and record the oxygen control amount.

[0031] Furthermore, the water supply volume in the pipeline is obtained through the design data. The water supply volume is the water supply volume in the pipeline from the point where the oxygen content data is obtained to the point where the magnetic data is obtained. The monitoring error that causes the magnetic change is obtained. The acquisition logic is as follows:

[0032] The flow rate and oxygen content are obtained at the front end of the water pump, thereby obtaining the monitoring error at the time. The actual oxygen content is obtained based on the monitoring error at the time, and oxygen is added based on the actual oxygen content at the time. According to the data obtained by the magnetoresistive sensor, it can be seen that it is the part of the water added with oxygen at the time that reaches the magnetic data acquisition point, causing the change in the thickness of the ferroferric oxide layer to be monitored. The monitoring error that causes the magnetic change is the monitoring error at the time.

[0033] The domain interval of the monitoring error that causes magnetic changes is obtained based on the following formula: ;

[0034] in, is the starting point of the domain interval, is the starting point of the cumulative flow range in the magnetic intensity decrease interval, is the volume of water reaching the magnetoresistive sensor from the water pump, is the end point of the domain interval, is the end point of the cumulative flow range in the magnetic intensity decrease interval, .

[0035] Furthermore, the monitoring error within the definition domain is modified, and the modification amount is set 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:

[0036] ;

[0037] in, , Indicates that the cumulative flow is The amount of modification when The oxygen control amount recorded by the PID control system, For traffic, is the pipeline pressure, is the molar mass of oxygen, is the ideal gas constant;

[0038] At the same time, the modification amount within the domain interval also satisfies the formula: ;

[0039] in, Indicates that the cumulative flow is The amount of modification when Indicates the cumulative flow rate is The rate of descent when

[0040] Modify the amount in MATLAB In the domain interval Solve in .

[0041] Furthermore, the monitoring error within the domain interval is modified according to the modification amount, and the formula is as follows: ;

[0042] in, is the monitoring error before adjustment, is the adjusted monitoring error, is the modification amount;

[0043] The adjusted monitoring error replaces the monitoring error before adjustment and is applied in subsequent monitoring. When the magnetic intensity is lower than the normal magnetic intensity range again in the subsequent monitoring process, the monitoring error of the corresponding definition domain interval is adjusted again.

[0044] The present invention also includes a thermal power plant high-temperature section oxygenation monitoring system for performing the above-mentioned thermal power plant high-temperature section oxygenation monitoring method, comprising:

[0045] The water oxygen content acquisition module is used to 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;

[0046] The back-end monitoring module is used to obtain the required oxygen content range and the amount of oxygen injected, 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;

[0047] The oxygen content analysis module is used to determine the thickness of the ferroferric oxide layer through the magnetic intensity curve, and to determine the change in the oxygen content of the steam in combination with the pH value curve, and to regulate the amount of oxygen added to obtain the oxygen control amount;

[0048] The modification module is used to obtain the water supply volume in the pipeline, 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, obtain the monitoring error and definition domain interval that cause the magnetic change, obtain the modification amount at different cumulative flow rates based on the oxygen control amount and the magnetic intensity curve, modify the monitoring error according to the modification amount, and replace the monitoring error before modification with the modified monitoring error for application in subsequent monitoring.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The present invention constructs an error prediction model through an experimental method, obtains the monitoring error and the actual oxygen content of the oxygen content according to the actual cumulative flow, and injects oxygen. The oxygen content is judged according to the change in the thickness of the ferroferric oxide layer and the change in the pH value during the actual process, and a correction amount for the monitoring error is obtained. The stability of the final ferroferric oxide layer is ensured by modifying the monitoring error. The present invention ensures the control of the oxygen content of the water feed through the prediction model, and further optimizes the monitoring of the water feed oxygen content through the actual change of the oxide layer, thereby ensuring the smooth generation of the ferroferric oxide layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Schematic diagram of the overall method flow of the present invention;

[0052] Figure 2 Schematic diagram of the system composition of the present invention. DETAILED DESCRIPTION

[0053] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0054] It should be noted that, unless otherwise defined, the technical or scientific terms used in the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0055] Example:

[0056] See also Figure 1 , the present invention provides a technical solution:

[0057] A method for monitoring oxygen addition in a high-temperature section of a thermal power plant without oxygen, comprising the following steps:

[0058] 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.

[0059] The step 1 includes the following:

[0060] 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: ;

[0061] 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;

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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: ;

[0066] in, is the actual oxygen content at the end of the water supply system, To monitor the error, This is the oxygen content reading from the oxygen monitoring device.

[0067] The real-time oxygen content is dynamically calculated using an error prediction model, combining oxygen monitoring device readings and accumulated flow. The accumulated flow is reset each time the electrolyte or membrane is replaced to prevent historical error data from interfering with the working status of the new component.

[0068] Step 2: 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;

[0069] The step 2 includes the following:

[0070] Step 201: Add oxygen and obtain the required oxygen content range. The required oxygen content range is the oxygen content range required for the water supply. Obtain the pipeline pressure and obtain the injected oxygen amount based on the actual oxygen content. The formula is as follows:

[0071] ;

[0072] in, The amount of oxygen injected, For traffic, 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, The upper limit of the required oxygen content range;

[0073] Among them, the oxygen content in the feed water is constructed through the gas dissolution model. The greater the pressure, the higher the solubility rate of the injected oxygen, which is reflected in the higher oxygen content in the feed water. The greater the flow rate and the more solvents, the lower the oxygen content in the feed water. This oxygen content is the theoretical oxygen content. The feed water may not be able to fully dissolve oxygen in subsequent operations, resulting in the actual oxygen content of the feed water not reaching the required oxygen content range, leaving hidden dangers for the subsequent formation of the ferroferric oxide oxide layer.

[0074] The oxygen injection rate is dynamically adjusted based on the actual oxygen content, ensuring that the feedwater oxygen content remains within the process requirements. By formulating the injection rate, the system precisely controls oxygen addition, preventing excessive oxygenation from causing pipeline corrosion or insufficient oxygen from causing abnormal oxide layer formation. The injected water is thoroughly mixed in a static mixer before passing through a superheater to form uniform superheated steam.

[0075] Step 202: Obtain the magnetic strength of the high-temperature steam pipe. The magnetic strength is obtained by a magnetic monitoring device, and a corresponding relationship between the thickness of the ferroferric oxide layer and the magnetic strength is established based on the following formula: ;

[0076] in, is the magnetic strength, is the thickness, is the corresponding function of thickness and magnetic strength;

[0077] The normal thickness range of the ferroferric oxide layer and the corresponding normal magnetic intensity range are calibrated in the laboratory;

[0078] Obtain a magnetic intensity curve of the pipeline at the rear end of the superheater, wherein the horizontal axis of the magnetic intensity curve represents the accumulated flow rate and the vertical axis represents the magnetic intensity;

[0079] The pH value curve of the discharged steam is obtained by the optical fiber pH sensor at the end. The horizontal axis of the pH value curve is the accumulated flow rate, and the vertical axis is the pH value.

[0080] Experiments have established a correlation between the thickness of the ferroferric oxide layer and the magnetic strength of the pipeline, providing a direct basis for real-time monitoring of the oxide layer's status. A magnetoresistive sensor continuously collects pipeline magnetic data. Combined with the normal magnetic strength range calibrated in the laboratory, the system can quickly identify abnormal oxide layer thickness (such as too thin or too thick). Simultaneously, a fiber optic pH sensor monitors the pH curve of the exhaust steam, providing dual-parameter feedback of magnetic strength and pH, enhancing indirect assessment of changes in oxygen content in high-temperature steam and enabling early warning.

[0081] Step 3: Determine the thickness of the ferroferric oxide layer through the magnetic intensity curve, determine the change in the oxygen content of the steam based on the pH value curve, and adjust the amount of oxygen added to obtain the oxygen control amount;

[0082] The step 3 includes the following:

[0083] Step 301: Analyze the magnetic curve and set the pH value change threshold. The analysis logic is as follows:

[0084] When the magnetic strength is lower than the normal magnetic strength range, the pH value is judged. If the pH value change exceeds the change threshold, it means that the oxygen content of the high-temperature steam is insufficient. If the pH value change is lower than the change threshold, it means that the oxygen content of the high-temperature steam exceeds the standard.

[0085] The cumulative flow range in the magnetic intensity decrease interval and the decrease rate curve in the magnetic intensity decrease interval are obtained based on the following formula: ;

[0086] in, Indicates the cumulative flow rate is The rate of descent, is the magnetic strength, is the cumulative flow;

[0087] The rate of magnetic intensity decrease curve in the decrease range reflects the deviation of oxygen content in the feed water. The greater the deviation of oxygen content in the feed water relative to the required oxygen content range, the faster the ferroferric oxide layer is destroyed, which is reflected in the smaller the value of the decrease rate.

[0088] When the oxygen content of high-temperature steam is insufficient, add oxygen; when the oxygen content of steam exceeds the standard, reduce the amount of oxygen injected until the magnetic strength returns to the middle value of the normal magnetic strength range, and record the oxygen control amount.

[0089] The magnetic strength curve and pH change threshold can be combined to determine the oxygen content of the steam. When the magnetic strength falls below the normal range and the pH value exceeds the threshold, the oxygen content is determined to be insufficient, and the PID control system is immediately activated to increase oxygen injection. If the magnetic strength is abnormal but the pH value does not exceed the threshold, the oxygen content is determined to be excessive, and oxygen injection is reduced. By analyzing the magnetic drop rate and dynamically adjusting the control parameters, the oxygen content in the high-temperature steam section quickly returns to equilibrium, reducing the risk of equipment loss.

[0090] Step 4: Obtain the water supply volume in the pipeline, which is the water supply volume in the pipeline from the oxygen content data acquisition point to the magnetic data acquisition point, obtain the monitoring error and definition domain interval that cause the magnetic change, and obtain the modification amount at different cumulative flow rates based on the oxygen control amount and the magnetic intensity curve. Modify the monitoring error according to the modification amount, and replace the monitoring error before modification with the modified monitoring error for subsequent monitoring.

[0091] The step 4 includes the following contents:

[0092] Step 401: Obtain the water supply volume in the pipeline from the design data. The water supply volume is the water supply volume in the pipeline from the point where the oxygen content data is obtained to the point where the magnetic data is obtained. Obtain the monitoring error that causes the magnetic change. The acquisition logic is as follows:

[0093] The flow rate and oxygen content are obtained, thereby obtaining the monitoring error at the time. The actual oxygen content is obtained based on the monitoring error at the time, and oxygen is added based on the actual oxygen content at the time. According to the data obtained by the magnetoresistive sensor, it can be seen that it is the part of the feed water added with oxygen at the time that reaches the magnetic data acquisition point, causing the change in the thickness of the ferroferric oxide layer to be monitored. The monitoring error that causes the magnetic change is the monitoring error at the time.

[0094] The domain interval of the monitoring error that causes magnetic changes is obtained based on the following formula: ;

[0095] in, is the starting point of the domain interval, is the starting point of the cumulative flow range in the magnetic intensity decrease interval, is the volume of water reaching the magnetoresistive sensor from the water pump, is the end point of the domain interval, is the end point of the cumulative flow range in the magnetic intensity decrease interval, .

[0096] The pipelines involved in obtaining feedwater volume data include those for high-temperature steam. Although the volume of high-temperature steam requires conversion to obtain the corresponding accumulated water volume, the conversion method can be obtained from the thermal power plant's design log. By calculating the feedwater volume and tracing back the accumulated flow rate, the historical time period corresponding to the monitoring error that caused the magnetic change can be accurately located. This step correlates the oxide layer anomalies detected by the magnetoresistive sensor with previous monitoring error data, clearly defining the accumulated flow range that requires correction. This provides a precise time window and data source for subsequent error adjustments, avoiding the waste of resources required for global corrections.

[0097] Step 402: Modify the monitoring error within the 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:

[0098] ;

[0099] in, , Indicates that the cumulative flow is The amount of modification when The oxygen control amount recorded by the PID control system, For traffic, is the pipeline pressure, is the molar mass of oxygen, is the ideal gas constant;

[0100] The oxygen content in the water supply may be too far away from the reading of the oxygen content monitoring equipment, resulting in inaccurate oxygen injection in the water supply pump link. It may also be due to insufficient oxygen dissolution in the subsequent operation of the water supply. However, these reasons do lead to oxygen content deviation in the water supply in the final link. The amount of oxygen adjustment required for the deviation is reflected by the oxygen control amount recorded by the PID control system. Converting the oxygen control amount into oxygen content can represent the oxygen content deviation caused by various reasons in the water supply. Feedback this part of the converted oxygen content to the predicted deviation, and adjust the oxygen injection amount at the water supply pump from the predicted deviation link to ensure that the water supply does not rely on the PID control system in subsequent operation, and directly make the oxygen content in the high-temperature section meet the standard. The larger the oxygen control amount, the greater the total amount of modification.

[0101] At the same time, the modification amount within the domain interval also satisfies the formula: ;

[0102] in, Indicates that the cumulative flow is The amount of modification when Indicates the cumulative flow rate is The rate of descent when

[0103] After determining the total amount of modification, it is necessary to distribute the total amount within the domain of definition, because the descent rate represents the deviation of the oxygen content in the feed water, and the derivative of the descent rate represents the change of the deviation. The change of the deviation is the derivative of the modification curve relative to the cumulative flow rate. The distribution of the modification is achieved by comparing the changes in the descent rate and the deviation. The faster the descent rate changes, the faster the deviation modification should increase. Whether the deviation modification is positive or negative has been determined by the oxygen adjustment amount, so the change rate is only reflected by the absolute value here.

[0104] Modify the amount in MATLAB In the domain interval Solve in .

[0105] Taking the two formulas related to the modification amount in this step as the restriction conditions, the modification amount is set as the linear combination of the basis functions, and the least squares method is used to solve it to obtain the specific modification amount curve.

[0106] Based on the oxygen control amount and magnetic drop rate recorded by PID control, the correction amount of the monitoring error is solved within the domain of definition through integral and differential constraints. This process uses mathematical models to ensure that the corrected error fully matches the actual magnetic change, eliminating the subjectivity of empirical adjustments. The correction results are both consistent with physical laws and can effectively offset the impact of historical errors on subsequent monitoring.

[0107] Step 403: Modify the monitoring error within the domain interval according to the modification amount, based on the following formula: ;

[0108] in, is the monitoring error before adjustment, is the adjusted monitoring error, is the modification amount;

[0109] The adjusted monitoring error replaces the monitoring error before adjustment and is applied in subsequent monitoring. When the magnetic intensity is lower than the normal magnetic intensity range again in the subsequent monitoring process, the monitoring error of the corresponding definition domain interval is adjusted again.

[0110] The error prediction model is dynamically updated, and the corrected monitoring error replaces the original error data, forming a closed-loop feedback loop. When the magnetic intensity abnormality appears again in subsequent monitoring, the system automatically triggers a new round of corrections to continuously optimize the model accuracy. This mechanism enables the system to adapt to interference factors such as sensor aging and water quality changes in long-term operation, significantly improving the stability and anti-interference ability of the monitoring model, and ensuring the long-term effectiveness of oxygen-free and oxygen-added monitoring in the high-temperature section of thermal power plants.

[0111] Please refer to Figure 2The present invention also includes a thermal power plant high temperature section oxygen-free oxygenation monitoring system for executing the above thermal power plant high temperature section oxygen-free oxygenation monitoring method, comprising:

[0112] The water oxygen content acquisition module is used to 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;

[0113] The back-end monitoring module is used to obtain the required oxygen content range and the amount of oxygen injected, 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;

[0114] The oxygen content analysis module is used to determine the thickness of the ferroferric oxide layer through the magnetic intensity curve, and to determine the change in the oxygen content of the steam in combination with the pH value curve, and to regulate the amount of oxygen added to obtain the oxygen control amount;

[0115] The modification module is used to obtain the water supply volume in the pipeline, 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, obtain the monitoring error and definition domain interval that cause the magnetic change, obtain the modification amount at different cumulative flow rates based on the oxygen control amount and the magnetic intensity curve, modify the monitoring error according to the modification amount, and replace the monitoring error before modification with the modified monitoring error for application in subsequent monitoring.

[0116] The above formulas are all dimensionless and numerical calculations. The formulas are obtained by collecting a large amount of data and performing software simulation to obtain the most recent real situation. The preset parameters in the formulas are set by technicians in this field according to actual conditions.

[0117] The above embodiments can be implemented in whole or in part by software, hardware, firmware, or any other combination thereof. 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 will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software depends on the specific application and design constraints of the technical solution.

[0118] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, and may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment as needed.

[0119] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

Claims

1. A method for monitoring oxygenation in a high-temperature section of a thermal power plant, characterized in that: The specific steps include: Obtain the oxygen content monitoring error at different cumulative flow rates in the pipeline, form a training set to input into the linear regression model, obtain the error prediction model, obtain the cumulative flow rate in the pipeline, input into the error prediction model, and obtain the oxygen content monitoring error; 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 is the measured oxygen content reading, is the oxygen content of the experimental water with a fixed oxygen content; The accumulated flow is aggregated to form a training set, and the monitoring error corresponding to the accumulated flow is used as a label for training in a linear regression model. The trained model is calibrated as an error prediction model. Obtain the magnetic intensity curve of the high-temperature steam pipeline, obtain the corresponding relationship between the thickness of the ferroferric oxide layer and the magnetic intensity, obtain the pH value curve of the exhaust steam, and calibrate the normal magnetic intensity 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.

2. The method for monitoring oxygenation in a high-temperature section of a thermal power plant without oxygen according to claim 1, wherein: The oxygen content reading and cumulative flow rate are obtained by the oxygen content monitoring device and the flow monitoring device respectively. The cumulative flow rate is the cumulative flow rate flowing through the pipeline before the oxygenation section since the oxygen content monitoring device was repaired. 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 into a curve with the horizontal axis being the cumulative flow rate and the vertical axis being the oxygen content monitoring error. 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, To monitor the error, This is the oxygen content reading from the oxygen monitoring device.

3. The method for monitoring oxygenation in a high-temperature section of a thermal power plant without oxygen according to claim 2, wherein: Add oxygen and obtain the required oxygen content range. The required oxygen content range is the oxygen content range required for the water supply. Obtain the pipeline pressure and obtain the injected oxygen amount based on the actual oxygen content. The formula is as follows: ； in, The amount of oxygen injected, For traffic, 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, The upper limit of the required oxygen content range.

4. The method for monitoring oxygenation in a high-temperature section of a thermal power plant without oxygen according to claim 3, wherein: The magnetic strength of the high-temperature steam pipe is obtained by a magnetic monitoring device, and the corresponding relationship between the thickness of the ferroferric oxide layer and the magnetic strength is established based on the following formula: ; in, is the magnetic strength, is the thickness, is the corresponding function of thickness and magnetic strength; The normal thickness range of the ferroferric oxide layer and the corresponding normal magnetic intensity range are calibrated in the laboratory; Obtain a magnetic intensity curve of the pipeline at the rear end of the superheater, wherein the horizontal axis of the magnetic intensity curve represents the accumulated flow rate and the vertical axis represents the magnetic intensity; The pH value curve of the discharged steam is obtained by the optical fiber pH sensor at the end. The horizontal axis of the pH value curve is the accumulated flow rate, and the vertical axis is the pH value.

5. The method for monitoring oxygenation in a high-temperature section of a thermal power plant without oxygen according to claim 4, characterized in that: Analyze the magnetic curve and set the pH value change threshold. The analysis logic is as follows: When the magnetic strength is lower than the normal magnetic strength range, the pH value is judged. If the pH value change exceeds the change threshold, it means that the oxygen content of the high-temperature steam is insufficient. If the pH value change is lower than the change threshold, it means that the oxygen content of the high-temperature steam exceeds the standard. The cumulative flow range in the magnetic intensity decrease interval and the decrease rate curve in the magnetic intensity decrease interval are obtained based on the following formula: ; in, Indicates the cumulative flow rate is The rate of descent, is the magnetic strength, is the cumulative flow; When the oxygen content of high-temperature steam is insufficient, add oxygen; when the oxygen content of steam exceeds the standard, reduce the amount of oxygen injected until the magnetic strength returns to the middle value of the normal magnetic strength range, and record the oxygen control amount.

6. The method for monitoring oxygenation in a high-temperature section of a thermal power plant without oxygen according to claim 5, characterized in that: The water supply volume in the pipeline is obtained from the design data. 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 that causes the magnetic change is obtained. The acquisition logic is as follows: The flow rate and oxygen content are obtained at the front end of the water pump, thereby obtaining the monitoring error at the time. The actual oxygen content is obtained based on the monitoring error at the time, and oxygen is added based on the actual oxygen content at the time. According to the data obtained by the magnetoresistive sensor, it can be seen that it is the part of the water added with oxygen at the time that reaches the magnetic data acquisition point, causing the change in the thickness of the ferroferric oxide layer to be monitored. The monitoring error that causes the magnetic change is the monitoring error at the time. The domain interval of the monitoring error that causes magnetic changes is obtained based on the following formula: ; in, is the starting point of the domain interval, is the starting point of the cumulative flow range in the magnetic intensity decrease interval, is the volume of water reaching the magnetoresistive sensor from the water pump, is the end point of the domain interval, is the end point of the cumulative flow range in the magnetic intensity decrease interval, .

7. The method for monitoring oxygenation in a high-temperature section of a thermal power plant without oxygen according to claim 6, characterized in that: Modify the monitoring error within the definition 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 value. The formula is as follows: ; in, , Indicates that the cumulative flow is The amount of modification when It is the oxygen control amount recorded by the PID control system. For traffic, is the pipeline pressure, is the molar mass of oxygen, is the ideal gas constant; At the same time, the modification amount within the domain interval also satisfies the formula: ; in, Indicates that the cumulative flow is The amount of modification when Indicates the cumulative flow rate is The rate of descent when Modify the amount in MATLAB In the domain interval Solve in .

8. The method for monitoring oxygenation in a high-temperature section of a thermal power plant without oxygen according to claim 7, characterized in that: The monitoring error within the domain interval is modified according to the modification amount, and the formula is as follows: ； in, is the monitoring error before adjustment, is the adjusted monitoring error, is the modification amount; The adjusted monitoring error replaces the monitoring error before adjustment and is applied in subsequent monitoring. When the magnetic intensity is lower than the normal magnetic intensity range again in the subsequent monitoring process, the monitoring error of the corresponding definition domain interval is adjusted again.

9. A system for monitoring oxygenation in a high-temperature section of a thermal power plant without oxygen, the system being used to implement a method for monitoring oxygenation in a high-temperature section of a thermal power plant without oxygen according to any one of claims 1 to 8, characterized in that: include: The water oxygen content acquisition module is used to 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 back-end monitoring module is used to obtain the required oxygen content range and the amount of oxygen injected, 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 oxygen content analysis module is used to determine the thickness of the ferroferric oxide layer through the magnetic intensity curve, and to determine the change in the oxygen content of the steam in combination with the pH value curve, and to regulate the amount of oxygen added to obtain the oxygen control amount; The modification module is used to obtain the water supply volume in the pipeline, 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, obtain the monitoring error and definition domain interval that cause the magnetic change, obtain the modification amount at different cumulative flow rates based on the oxygen control amount and the magnetic intensity curve, modify the monitoring error according to the modification amount, and replace the monitoring error before modification with the modified monitoring error for application in subsequent monitoring.

Images