Soft measurement method and system for content of nitric oxide in flue gas of gas-fired boiler

Abstract

The invention provides a soft measurement method and system for the content of nitric oxide in flue gas of a gas-fired boiler, and the method comprises the steps: building a nitric oxide generation model based on a generation mechanism of nitric oxide in the gas-fired boiler; the nitric oxide generation model is a double-path mathematical model of a thermal nitric oxide generation model and a fuel nitric oxide generation model; combustion process parameters are obtained; the combustion process parameters comprise hearth temperature, flue gas flow and oxygen content; processing the combustion process parameters through window mean or median filtering to obtain filtered combustion process parameters; and finally, substituting the filtered combustion process parameters into the nitrogen oxide generation model to obtain the nitrogen oxide content, so that soft measurement of the nitrogen oxide content in the boiler flue gas is realized, and the problem that measurement of the nitrogen oxide in the gas boiler flue gas has relatively large hysteresis is solved.

Description

Technical Field

[0001] The present application relates to the technical field of gas boiler flue gas measurement, and particularly relates to a soft measurement method and system for the content of nitrogen oxides in the flue gas of a gas boiler. Background Technique

[0002] With the increasingly strict industrial boiler emission standards, gas boilers, as clean energy equipment, are more and more widely used in industrial production. Nitrogen oxides (NOx) generated during the combustion process of gas boilers are one of the main sources of air pollution, and the real-time monitoring and precise control of their emission concentration have become the key links in environmental protection governance.

[0003] In the related art, the measurement of the nitrogen oxide content in gas boilers generally adopts the end-sampling detection method. A chemiluminescence method or an electrochemical sensor is installed at the chimney at the tail of the boiler, and the flue gas component data is collected in real time and fed back to the control system. When the detected NOx concentration deviates from the set value, the injection amount of the desulfurization and denitrification agent is automatically adjusted to achieve concentration balance.

[0004] However, the collection of flue gas component data by the end-sampling detection method has a large lag. Using the end flue gas inspection data to adjust the flue gas desulfurization and denitrification system is prone to large oscillations and fluctuations, and it is also easy for the flue gas components to exceed the standard. To avoid the instantaneous over-standard of the nitrogen oxide concentration, it is also necessary to adopt the method of over-spraying the desulfurization and denitrification agent to ensure that the flue gas components meet the standard. This method not only has a prominent waste of reducing agent, resulting in increased costs, but also causes secondary pollution of ammonia escape. Summary of the Invention

[0005] The present application provides a soft measurement method for the content of nitrogen oxides in the flue gas of a gas boiler to solve the problem of large lag in the measurement of nitrogen oxides in the flue gas of a gas boiler.

[0006] On the one hand, the present application provides a soft measurement method for the content of nitrogen oxides in the flue gas of a gas boiler, and the method includes:

[0007] Establish a nitrogen oxide generation model based on the generation mechanism of nitrogen oxides in the gas boiler, and the nitrogen oxide generation model is a dual-path mathematical model of a thermal nitrogen oxide generation model and a fuel nitrogen oxide generation model;

[0008] Obtain combustion process parameters; the combustion process parameters include furnace temperature, flue gas flow rate, and oxygen content;

[0009] Process the combustion process parameters through window mean or median filtering to obtain filtered combustion process parameters;

[0010] Substitute the filtered combustion process parameters into the nitrogen oxide generation model to obtain the nitrogen oxide content.

[0011] The soft measurement method for the nitrogen oxide content in the flue gas of the gas boiler constructs a dual-path mathematical model for the generation of thermal and fuel-type nitrogen oxides, and combines key parameters such as furnace temperature, flue gas flow rate, and oxygen content in the actual combustion process. After being processed by window mean or median filtering, it is substituted into the model to achieve accurate measurement of the nitrogen oxide content. This method not only improves the accuracy and reliability of the measurement, but also provides strong technical support for the low-nitrogen combustion control of the gas boiler, helps reduce pollutant emissions, improve environmental quality, and at the same time provides an important guarantee for the efficient operation, energy conservation and emission reduction of the boiler.

[0012] Optionally, the calculation formula for the nitrogen oxide content is:

[0013] W NO =W NO,hot +W NO，rl ;

[0014] Wherein, W NO,hot is the generation amount of thermal nitrogen oxides; W NO，rl is the generation amount of fuel-type nitrogen oxides.

[0015] The calculation formula for the nitrogen oxide content realizes the accurate calculation of the nitrogen oxide content in the flue gas of the gas boiler by clearly distinguishing the generation amounts of thermal and fuel-type nitrogen oxides and adding them together. This calculation method fully considers the different generation mechanisms of nitrogen oxides, making the measurement results more accurate and reliable.

[0016] Optionally, the thermal nitrogen oxide generation model includes:

[0017]

[0018] Wherein, is the thermal nitrogen oxide generation rate; k1 is the reaction rate constant; [O] is the oxygen concentration; [N2] is the nitrogen concentration; ρ is the gas phase density in the furnace; Y x is the mass percentage corresponding to x; t is the furnace temperature.

[0019] The thermal nitrogen oxide generation model constructs a mathematical model that accurately describes the thermal nitrogen oxide generation process by comprehensively considering key factors such as the gas phase density in the furnace, the mass percentages of each component, and the furnace temperature. This model can accurately reflect the complex chemical reactions and physical processes in the furnace and provide a scientific basis for calculating the generation amount of thermal nitrogen oxides.

[0020] Optionally, the calculation formula for the generation amount of thermal nitrogen oxides is:

[0021]

[0022] Among them, V yq is the flue gas flow rate.

[0023] The calculation formula for the generation amount of thermal NOx realizes the accurate quantification of the generation amount of thermal NOx by combining the generation rate of thermal NOx and the flue gas flow rate.

[0024] Optionally, the calculation formula for the generation amount of fuel NOx is:

[0025] W NO,rl = A NO,gq *V gq ;

[0026] Among them, A NO,gq is the concentration of NOx in blast furnace gas; V gq is the blast furnace gas flow rate.

[0027] The calculation formula for the generation amount of fuel NOx realizes the accurate calculation of the generation amount of fuel NOx by combining two key parameters: the concentration of NOx in blast furnace gas and the blast furnace gas flow rate. The concentration of NOx in blast furnace gas directly reflects the enrichment degree of NOx in the gas, while the blast furnace gas flow rate represents the flow rate of the gas during combustion. The result obtained by multiplying the two can accurately reflect the generation amount of fuel NOx, making the control of fuel NOx emissions from gas-fired boilers more precise.

[0028] Optionally, the steps of obtaining the filtered combustion process parameters by window mean or median filtering of the combustion process parameters include:

[0029] Preprocess the combustion process parameters to remove outliers or noise interference;

[0030] Set the rules for mean or median filtering according to the window size;

[0031] Perform a sliding window process on the preprocessed data to obtain the filtered combustion process parameters.

[0032] The steps of obtaining the filtered combustion process parameters by window mean or median filtering of the combustion process parameters effectively remove outliers and noise interference, ensuring the accuracy and reliability of the data. The rules for mean or median filtering set according to the window size make the data processing more flexible and adaptable to different working conditions. The sliding window process ensures that the filtered combustion process parameters can truly reflect the actual operating state of the gas-fired boiler. These series of steps not only improve the accuracy of NOx content calculation, but also enhance the robustness and practicality of the entire measurement method, providing strong support for the low-nitrogen combustion control and environmental protection operation of gas-fired boilers.

[0033] Optionally, the method for establishing the NOx generation model is:

[0034] Analyze the formation mechanism of nitrogen oxides in a gas boiler and divide the formation paths of nitrogen oxides; the formation paths of nitrogen oxides include: thermal, fuel, and prompt formation paths;

[0035] According to the formation paths of nitrogen oxides, calculate the superposition value of thermal nitrogen oxides and fuel nitrogen oxides to establish a dual-path mathematical model of the thermal nitrogen oxide formation model and the fuel nitrogen oxide formation model;

[0036] Modify the output of the dual-path mathematical model in real time according to the dynamic combustion process parameters.

[0037] The method for establishing the nitrogen oxide formation model comprehensively understands the nitrogen oxide formation process by deeply analyzing the formation mechanism of nitrogen oxides in a gas boiler and clearly dividing the formation paths such as thermal, fuel, and prompt. By calculating the superposition value of thermal nitrogen oxides and fuel nitrogen oxides, a dual-path mathematical model of the thermal and fuel nitrogen oxide formation models is constructed, which can more accurately describe the formation law of nitrogen oxides. At the same time, modifying the model output in real time according to the dynamic combustion process parameters enables the model to adapt to different operating conditions and improves the accuracy and reliability of the model.

[0038] The second aspect of this application provides a soft measurement system for the nitrogen oxide content in the flue gas of a gas boiler, which is applicable to the soft measurement method for the nitrogen oxide content in the flue gas of the gas boiler described in the first aspect. The system includes:

[0039] A model establishment unit for establishing a nitrogen oxide formation model based on the formation mechanism of nitrogen oxides in a gas boiler. The nitrogen oxide formation model is a dual-path mathematical model of a thermal nitrogen oxide formation model and a fuel nitrogen oxide formation model;

[0040] A sensor group for obtaining combustion process parameters; the combustion process parameters include furnace temperature, flue gas flow rate, and oxygen content;

[0041] A filtering unit for processing the combustion process parameters through window mean or median filtering to obtain filtered combustion process parameters;

[0042] A data processing unit for substituting the filtered combustion process parameters into the nitrogen oxide formation model to obtain the nitrogen oxide content.

[0043] The soft measurement system for the nitrogen oxide content in the flue gas of the gas boiler realizes comprehensive, accurate and real-time measurement of the nitrogen oxide content in the flue gas of the gas boiler by integrating a model establishment unit, a sensor group, a filtering unit and a data processing unit. The model establishment unit constructs a dual-path mathematical model based on the nitrogen oxide generation mechanism, providing a theoretical basis for accurate calculation; the sensor group collects key parameters such as furnace temperature, flue gas flow rate and oxygen content in real time to ensure the comprehensiveness and immediacy of the data; the filtering unit effectively removes outliers and noise interference through window mean or median filtering to improve the data quality; the data processing unit then substitutes the filtered data into the model to calculate the accurate nitrogen oxide content. This system not only improves the accuracy and reliability of nitrogen oxide measurement, but also provides strong technical support for the low-nitrogen combustion control of gas boilers, helps reduce pollutant emissions, and promotes the environmental protection development of gas boiler technology.

[0044] Optionally, the sensor group includes: a furnace temperature sensor, a flue gas flowmeter and an oxygen content analyzer;

[0045] The furnace temperature sensor is used to collect the furnace temperature in real time;

[0046] The flue gas flowmeter is used to collect the flue gas flow rate in real time;

[0047] The oxygen content analyzer is used to collect the oxygen content in real time.

[0048] The sensor group realizes comprehensive and real-time monitoring of key parameters in the combustion process of the gas boiler by integrating a furnace temperature sensor, a flue gas flowmeter and an oxygen content analyzer. The furnace temperature sensor ensures the immediate capture of furnace temperature changes, providing core data support for combustion control; the flue gas flowmeter accurately measures the flue gas flow rate, helping to evaluate combustion efficiency and emission levels; the oxygen content analyzer analyzes the oxygen content in the flue gas in real time to further optimize the air-fuel ratio and ensure full and efficient combustion. The coordinated work of this series of sensors not only improves the stability and safety of the combustion process, but also provides the necessary data basis for accurately calculating the nitrogen oxide content, thus effectively guiding the low-nitrogen combustion control strategy of the gas boiler.

[0049] As can be seen from the above technical solutions, the present application provides a soft measurement method and system for the nitrogen oxide content in the flue gas of a gas boiler. The method establishes a nitrogen oxide generation model based on the generation mechanism of nitrogen oxides in the gas boiler. The nitrogen oxide generation model is a dual-path mathematical model of a thermal-type nitrogen oxide generation model and a fuel-type nitrogen oxide generation model. Then, combustion process parameters are obtained. The combustion process parameters include furnace temperature, flue gas flow rate, and oxygen content. The combustion process parameters are processed by window mean or median filtering to obtain filtered combustion process parameters. Finally, the filtered combustion process parameters are substituted into the nitrogen oxide generation model to obtain the nitrogen oxide content, realizing the soft measurement of the nitrogen oxide content in the boiler flue gas, so as to solve the problem of large lag in the measurement of nitrogen oxides in the flue gas of gas boilers. Description of the Drawings

[0050] In order to more clearly illustrate the technical solutions of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0051] Figure 1 It is a schematic flowchart of the soft measurement method for the nitrogen oxide content in the flue gas of the gas boiler provided by the embodiment of the present application. Detailed Embodiments

[0052] The embodiments will be described in detail below, and the examples are shown in the drawings. When the following description involves the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following examples do not represent all embodiments consistent with the present application. They are only examples of systems and methods consistent with some aspects of the present application.

[0053] With the increasingly strict emission standards of industrial boilers, gas boilers, as clean energy equipment, are increasingly widely used in industrial production. Nitrogen oxides (NOx) generated during the combustion process of gas boilers are one of the main sources of air pollution, and the real-time monitoring and precise control of their emission concentration have become the key links in environmental protection governance.

[0054] In related embodiments, the measurement of the nitrogen oxide content in gas boilers generally adopts the end-sampling detection method. A chemiluminescence method or an electrochemical sensor is installed at the chimney at the tail of the boiler, and the flue gas component data is collected in real time and fed back to the control system. When the detected NOx concentration deviates from the set value, the injection amount of the desulfurization and denitrification agent is automatically adjusted to achieve concentration balance. However, the collection of flue gas component data by the end-sampling detection method has a large lag. Using the end-flue gas inspection data to adjust the flue gas desulfurization and denitrification system is prone to large fluctuations and oscillations, and the flue gas components are also prone to exceeding the standard. To avoid the instantaneous exceeding of the nitrogen oxide concentration, it is also necessary to adopt the method of over-spraying the desulfurization and denitrification agent to ensure that the flue gas components meet the standards. This method not only causes prominent waste of reducing agent and increases the cost, but also causes secondary pollution of ammonia escape.

[0055] To solve the problem that the measurement of nitrogen oxides in the flue gas of gas boilers has a large lag, refer to Figure 1 , some embodiments of the present application provide a soft measurement method for the nitrogen oxide content in the flue gas of a gas boiler, and the method includes:

[0056] S100: Establish a nitrogen oxide generation model based on the generation mechanism of nitrogen oxides in the gas boiler.

[0057] The nitrogen oxide generation model is a dual-path mathematical model of a thermal nitrogen oxide generation model and a fuel nitrogen oxide generation model.

[0058] S200: Obtain combustion process parameters.

[0059] The combustion process parameters include furnace temperature, flue gas flow rate, and oxygen content.

[0060] S300: Process the combustion process parameters through window mean or median filtering to obtain filtered combustion process parameters.

[0061] S400: Substitute the filtered combustion process parameters into the nitrogen oxide generation model to obtain the nitrogen oxide content.

[0062] It should be understood that the thermal nitrogen oxide generation model adopts the Arrhenius equation kinetic model, and the fuel nitrogen oxide generation model directly correlates the gas nitrogen oxide concentration with the flow rate.

[0063] The soft measurement method for the nitrogen oxide content in the flue gas of a gas boiler constructs a dual-path mathematical model for the generation of thermal and fuel-type nitrogen oxides, and combines key parameters such as furnace temperature, flue gas flow rate, and oxygen content in the actual combustion process. After being processed by window mean or median filtering, they are substituted into the model to achieve accurate measurement of the nitrogen oxide content. This method not only improves the accuracy and reliability of the measurement, but also provides strong technical support for the low-nitrogen combustion control of gas boilers, helps reduce pollutant emissions, improve environmental quality, and also provides an important guarantee for the efficient operation, energy conservation and emission reduction of boilers.

[0064] In some embodiments, the calculation formula for the nitrogen oxide content is:

[0065] W NO =W NO,hot +W NO，rl ;

[0066] where, W NO,hot is the generation amount of thermal nitrogen oxides; W NO，rl is the generation amount of fuel-type nitrogen oxides.

[0067] The calculation formula for the nitrogen oxide content realizes the precise calculation of the nitrogen oxide content in the flue gas of a gas boiler by clearly distinguishing the generation amounts of thermal and fuel-type nitrogen oxides and adding them to obtain the total nitrogen oxide content. This calculation method fully considers the different generation mechanisms of nitrogen oxides, making the measurement results more accurate and reliable.

[0068] In some embodiments, the thermal nitrogen oxide generation model includes:

[0069]

[0070] where, is the generation rate of thermal nitrogen oxides; k1 is the reaction rate constant; [O] is the oxygen concentration; [N2] is the nitrogen concentration; ρ is the gas phase density in the furnace; Y x is the mass percentage corresponding to x; t is the furnace temperature.

[0071] The thermal nitrogen oxide generation model constructs a mathematical model that accurately describes the generation process of thermal nitrogen oxides by comprehensively considering key factors such as the gas phase density in the furnace, the mass percentages of each component, and the furnace temperature. This model can accurately reflect the complex chemical reactions and physical processes in the furnace, providing a scientific basis for calculating the generation amount of thermal nitrogen oxides.

[0072] In some embodiments, the calculation formula for the generation amount of thermal nitrogen oxides is:

[0073]

[0074] Among them, V yq is the flue gas flow rate.

[0075] It should be understood that the flue gas flow rate, as a key variable, reflects the flue gas flow rate during the combustion process of the gas boiler and is an important factor affecting the generation amount of nitrogen oxides.

[0076] The calculation formula for the generation amount of thermal nitrogen oxides realizes the accurate quantification of the generation amount of thermal nitrogen oxides by combining the generation rate of thermal nitrogen oxides and the flue gas flow rate.

[0077] In some embodiments, the calculation formula for the generation amount of fuel-type nitrogen oxides is:

[0078] W NO,rl = A NO,gq *V gq ;

[0079] Among them, A NO,gq is the concentration content of nitrogen oxides in the blast furnace gas; V gq is the blast furnace gas flow rate.

[0080] The calculation formula for the generation amount of fuel-type nitrogen oxides realizes the accurate calculation of the generation amount of fuel-type nitrogen oxides by combining two key parameters, namely the concentration content of nitrogen oxides in the blast furnace gas and the blast furnace gas flow rate. The concentration content of nitrogen oxides in the blast furnace gas directly reflects the enrichment degree of nitrogen oxides in the gas, while the blast furnace gas flow rate represents the flow rate of the gas during the combustion process. The result obtained by multiplying the two can accurately reflect the generation amount of fuel-type nitrogen oxides, making the control of fuel-type nitrogen oxide emissions from gas boilers more precise.

[0081] In some embodiments, the steps of obtaining the filtered combustion process parameters by processing the combustion process parameters through window mean or median filtering include:

[0082] Preprocess the combustion process parameters to remove outliers or noise interference.

[0083] Set the rules for the mean or median mean according to the window size.

[0084] Perform a sliding window process on the preprocessed data to obtain the filtered combustion process parameters.

[0085] Specifically, if the mean filtering is used to process the combustion process parameters, the window parameters are first defined. The window shape can be selected as a square or a rectangle and adjusted according to the parameter change rate. The window size needs to balance noise suppression and detail preservation. For example, a small window is suitable for scenarios with less high-frequency noise and small parameter fluctuations, retaining more details. A large window is suitable for scenarios with strong noise or drastic parameter fluctuations, but may blur features. Then, traverse the parameter sequence, apply a sliding window to the combustion parameters at each moment, calculate the mean value within the window, and finally output the filtering result. Assign the mean value to the current moment to generate a smoothed parameter sequence. Mean filtering is suitable for Gaussian noise and has high computational efficiency.

[0086] If the median filtering is used to process the combustion process parameters, an odd-length window is first defined. Among them, the window length can be selected as a 3-, 5-, or 7-point window (preferably a 5-point window), covering the current point and the symmetric front and back sampling points. The 3-point window covers the current point and the previous and subsequent points. The 5-point window covers the current point and the previous two and subsequent two points. Then, extract the parameter values within the window. For the parameters at each moment, extract all the sampling values within the window. Finally, sort and take the median. Sort the values within the window in ascending order and take the middle value as the filtering result of the current point.

[0087] The steps of processing the combustion process parameters through window mean or median filtering effectively remove outliers and noise interference, ensuring the accuracy and reliability of the data. The mean or median filtering rules set according to the window size make the data processing more flexible and adaptable to different working conditions. The sliding window processing ensures that the filtered combustion process parameters can truly reflect the actual operating state of the gas boiler. This series of steps not only improves the accuracy of calculating the nitrogen oxide content but also enhances the robustness and practicability of the entire measurement method, providing strong support for the low-nitrogen combustion control and environmental protection operation of the gas boiler.

[0088] In some embodiments, the method for establishing the nitrogen oxide generation model is as follows:

[0089] Analyze the generation mechanism of nitrogen oxides in the gas boiler and divide the nitrogen oxide generation paths. The nitrogen oxide generation paths include: thermal, fuel, and prompt generation paths.

[0090] According to the nitrogen oxide generation paths, calculate the superposition value of thermal nitrogen oxides and fuel nitrogen oxides to establish a dual-path mathematical model for the thermal nitrogen oxide generation model and the fuel nitrogen oxide generation model.

[0091] Correct the output of the dual-path mathematical model in real time according to the dynamic combustion process parameters.

[0092] It should be understood that since the proportion of prompt NOx in flue gas is very small, prompt NOx can be ignored in actual engineering applications, and only the superposition value of thermal NOx and fuel NOx needs to be calculated.

[0093] The method for establishing the NOx generation model comprehensively understands the NOx generation process by deeply analyzing the NOx generation mechanism in a gas-fired boiler and clearly dividing the generation paths such as thermal, fuel, and prompt types. By calculating the superposition value of thermal NOx and fuel NOx, a dual-path mathematical model of thermal and fuel NOx generation models is constructed, which can more accurately describe the NOx generation law. At the same time, the model output is corrected in real time according to the dynamic combustion process parameters, enabling the model to adapt to different operating conditions and improving the accuracy and reliability of the model.

[0094] Some embodiments of this application also provide a soft measurement system for the NOx content in the flue gas of a gas-fired boiler, which is applicable to the soft measurement method for the NOx content in the flue gas of the gas-fired boiler described in the above embodiments. The system includes:

[0095] A model establishment unit for establishing a NOx generation model based on the NOx generation mechanism in a gas-fired boiler. The NOx generation model is a dual-path mathematical model of a thermal NOx generation model and a fuel NOx generation model.

[0096] A sensor group for acquiring combustion process parameters; the combustion process parameters include furnace temperature, flue gas flow rate, and oxygen content.

[0097] A filtering unit for processing the combustion process parameters through window mean or median filtering to obtain filtered combustion process parameters.

[0098] A data processing unit for substituting the filtered combustion process parameters into the NOx generation model to obtain the NOx content.

[0099] The soft measurement system for the nitrogen oxide content in the flue gas of a gas boiler realizes comprehensive, accurate and real-time measurement of the nitrogen oxide content in the flue gas of the gas boiler by integrating a model establishment unit, a sensor group, a filtering unit and a data processing unit. The model establishment unit constructs a two-path mathematical model based on the nitrogen oxide generation mechanism, providing a theoretical basis for accurate calculation; the sensor group collects key parameters such as furnace temperature, flue gas flow rate and oxygen content in real time to ensure the comprehensiveness and immediacy of the data; the filtering unit effectively removes outliers and noise interference through window mean or median filtering to improve the data quality; the data processing unit then substitutes the filtered data into the model to calculate the accurate nitrogen oxide content. This system not only improves the accuracy and reliability of nitrogen oxide measurement, but also provides strong technical support for the low-nitrogen combustion control of gas boilers, helps to reduce pollutant emissions, and promotes the environmental protection development of gas boiler technology.

[0100] In some embodiments, the sensor group includes: a furnace temperature sensor, a flue gas flow meter and an oxygen content analyzer; the furnace temperature sensor is used to collect the furnace temperature in real time; the flue gas flow meter is used to collect the flue gas flow rate in real time; the oxygen content analyzer is used to collect the oxygen content in real time.

[0101] It should be understood that the accuracy of the furnace temperature sensor can be ±1°C; the range of the flue gas flow meter needs to match the rated flow of the boiler; the oxygen content analyzer works based on the electrochemical principle or the zirconia principle and can accurately measure the oxygen content in the gas.

[0102] The sensor group realizes comprehensive real-time monitoring of key parameters during the combustion process of the gas boiler by integrating a furnace temperature sensor, a flue gas flow meter and an oxygen content analyzer. The furnace temperature sensor ensures the immediate capture of furnace temperature changes, providing core data support for combustion control; the flue gas flow meter accurately measures the flue gas flow rate, helping to evaluate the combustion efficiency and emission level; the oxygen content analyzer analyzes the oxygen content in the flue gas in real time to further optimize the air-fuel ratio and ensure full and efficient combustion. The coordinated work of this series of sensors not only improves the stability and safety of the combustion process, but also provides the necessary data basis for accurately calculating the nitrogen oxide content, thus effectively guiding the low-nitrogen combustion control strategy of gas boilers.

[0103] As can be seen from the above technical solutions, the embodiments of the present application provide a soft measurement method and system for the content of nitrogen oxides in the flue gas of a gas boiler. The method establishes a nitrogen oxide generation model based on the generation mechanism of nitrogen oxides in the gas boiler. The nitrogen oxide generation model is a two-path mathematical model of a thermal nitrogen oxide generation model and a fuel nitrogen oxide generation model. Then, combustion process parameters are obtained. The combustion process parameters include furnace temperature, flue gas flow rate, and oxygen content. The combustion process parameters are processed by window mean or median filtering to obtain filtered combustion process parameters. Finally, the filtered combustion process parameters are substituted into the nitrogen oxide generation model to obtain the content of nitrogen oxides, realizing the soft measurement of the content of nitrogen oxides in the boiler flue gas, so as to solve the problem of large lag in the measurement of nitrogen oxides in the flue gas of gas boilers.

[0104] For the similarities between the embodiments provided in the present application, reference can be made to each other. The specific embodiments provided above are only several examples under the general concept of the present application and do not constitute a limitation on the protection scope of the present application. For those skilled in the art, any other embodiments extended based on the solution of the present application without creative efforts belong to the protection scope of the present application.

Claims

1. A soft measurement method for the nitrogen oxide content in the flue gas of a gas boiler, characterized in that, The method includes: Establishing a nitrogen oxide generation model based on the generation mechanism of nitrogen oxides in a gas boiler, where the nitrogen oxide generation model is a dual-path mathematical model of a thermal nitrogen oxide generation model and a fuel nitrogen oxide generation model; Obtaining combustion process parameters; the combustion process parameters include furnace temperature, flue gas flow rate, and oxygen content; Processing the combustion process parameters through window mean or median filtering to obtain filtered combustion process parameters; Substituting the filtered combustion process parameters into the nitrogen oxide generation model to obtain the nitrogen oxide content.

2. The soft measurement method for the nitrogen oxide content in the flue gas of a gas boiler according to claim 1, characterized in that The calculation formula for the nitrogen oxide content is: W NO = W NO,hot + W NO，rl ; Among them, W NO,hot is the generation amount of thermal NOx; W NO，rl is the generation amount of fuel NOx.

3. The soft measurement method for the nitrogen oxide content in the flue gas of a gas boiler according to claim 2, characterized in that The thermal nitrogen oxide generation model includes: Among them, is the generation rate of thermal NOx; k1 is the reaction rate constant; [O] is the oxygen concentration; [N2] is the nitrogen concentration; ρ is the gas phase density in the furnace; Y x is the mass percentage corresponding to x; t is the furnace temperature.

4. The soft measurement method for the nitrogen oxide content in the flue gas of a gas boiler according to claim 3, characterized in that, The calculation formula for the generated amount of thermal nitrogen oxides is: Among them, V yq is the flue gas flow rate.

5. The soft measurement method for the nitrogen oxide content in the flue gas of a gas boiler according to claim 2, characterized in that, The calculation formula for the generated amount of fuel nitrogen oxides is: W NO,rl = A NO,gq * V gq ; Among them, A NO,gq is the concentration of nitrogen oxides in blast furnace gas; V gq is the flow rate of blast furnace gas.

6. The soft measurement method for the nitrogen oxide content in the flue gas of a gas boiler according to claim 1, characterized in that, The step of processing the combustion process parameters through window mean or median filtering to obtain filtered combustion process parameters includes: Preprocessing the combustion process parameters to remove outliers or noise interference; Setting the rules of mean or median filtering according to the window size; Performing a sliding window process on the preprocessed data to obtain filtered combustion process parameters.

7. The soft measurement method for the nitrogen oxide content in the flue gas of a gas boiler according to claim 1, characterized in that, The method for establishing the nitrogen oxide generation model is: Analyzing the generation mechanism of nitrogen oxides in a gas boiler and dividing the nitrogen oxide generation paths; the nitrogen oxide generation paths include: thermal, fuel, and prompt generation paths; Calculating the superposition value of thermal carbon oxides and fuel carbon oxides according to the nitrogen oxide generation paths to establish a dual-path mathematical model of a thermal nitrogen oxide generation model and a fuel nitrogen oxide generation model; Real-time correcting the output of the dual-path mathematical model according to dynamic combustion process parameters.

8. A soft measurement system for the nitrogen oxide content in the flue gas of a gas boiler, characterized in that, Applicable to the soft measurement method for the nitrogen oxide content in the flue gas of the gas boiler described in any one of claims 1-7, the system includes: A model establishment unit for establishing a nitrogen oxide generation model based on the generation mechanism of nitrogen oxides in a gas boiler, where the nitrogen oxide generation model is a dual-path mathematical model of a thermal nitrogen oxide generation model and a fuel nitrogen oxide generation model; A sensor group for obtaining combustion process parameters; the combustion process parameters include furnace temperature, flue gas flow rate, and oxygen content; A filtering unit for processing the combustion process parameters through window mean or median filtering to obtain filtered combustion process parameters; A data processing unit for substituting the filtered combustion process parameters into the nitrogen oxide generation model to obtain the nitrogen oxide content.

9. The soft measurement system for the nitrogen oxide content in the flue gas of a gas boiler according to claim 8, characterized in that, The sensor group includes: a furnace temperature sensor, a flue gas flow meter, and an oxygen content analyzer; The furnace temperature sensor is used to collect the furnace temperature in real time; The flue gas flow meter is used to collect the flue gas flow rate in real time; The oxygen content analyzer is used to collect the oxygen content in real time.

Images