A method for controlling ammonia injection rate in an SCR flue gas denitrification system of a steel plant

Abstract

This invention relates to a method for controlling ammonia injection in an SCR flue gas denitrification system in a steel plant, belonging to the field of ammonia injection control technology. The system includes: acquiring load data under various operating conditions of the target boiler unit and reactor gas concentration data, and calculating the simulated ammonia injection rate of the SCR flue gas denitrification system at the current moment; obtaining the fuzzy control ammonia injection rate at the current moment based on the reactor gas concentration data and the simulated ammonia injection rate, and obtaining the operating condition status value based on the various load data; obtaining the actual control ammonia injection rate based on the operating condition status value, and applying it to the system. This invention can adaptively adjust the actual control ammonia injection rate according to changes in different operating conditions, improving the control accuracy of the SCR flue gas denitrification system.

Description

Technical Field

[0001] This invention relates to the field of ammonia injection quantity control system technology, and in particular to a method for controlling the ammonia injection quantity in an SCR flue gas denitrification system for steel plants. Background Technology

[0002] Coal dust contains a large amount of NO x , if NO x Excessive emissions can lead to acid rain and environmental pollution. NO in denitrification systems... x Emissions and ammonia injection rates are key concerns. Selective catalytic reduction (SCR) flue gas denitrification technology has matured significantly in recent years, and SCR flue gas denitrification systems built upon this technology can effectively address NOx emissions in flue gas. x The technology, which measures emissions and ammonia slip, is now widely used in major steel plants.

[0003] The difficulty in controlling the SCR flue gas denitrification system lies in controlling the ammonia injection rate. Currently, when controlling the ammonia injection rate of the SCR flue gas denitrification system, the ammonia injection rate is usually adjusted by giving empirical proportional coefficients, integral time, and derivative time, and using a PID controller until the ammonia injection rate stabilizes and the gas concentration at the reactor outlet of the SCR flue gas denitrification system meets the requirements.

[0004] However, in complex industrial environments, SCR flue gas denitrification systems are subject to various disturbances from operating parameters, such as furnace temperature changes, gas velocity changes, and flue gas flow rate. Traditional PID controllers rely on fixed parameters (proportional coefficient, integral time, and derivative time) to control the ammonia injection rate, which is poorly adaptable to disturbances in the aforementioned operating parameters, resulting in poor control accuracy. Moreover, since the relationship between the ammonia injection rate and the reactor outlet gas concentration is usually non-linear, the ammonia injection rate cannot be accurately controlled by a PID controller alone. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for controlling ammonia injection volume in an SCR flue gas denitrification system of a steel plant. The technical solution of this invention is as follows:

[0006] A method for controlling ammonia injection rate in an SCR flue gas denitrification system of a steel plant, comprising:

[0007] S1, real-time acquisition of various operating load data, reactor inlet gas concentration data, and reactor outlet gas concentration data of the target boiler unit at the current moment;

[0008] S2, calculate the simulated ammonia injection rate of the SCR flue gas denitrification system at the current moment based on various operating load data, reactor inlet gas concentration data and reactor outlet gas concentration data;

[0009] S3, based on the reactor outlet gas concentration data and the simulated ammonia injection rate, perform fuzzy control on the ammonia injection rate of the target boiler unit to obtain the fuzzy control ammonia injection rate of the SCR flue gas denitrification system at the current moment.

[0010] S4, obtain the current operating status value of the target boiler unit based on various operating load data and reactor outlet gas concentration data;

[0011] S5 corrects the fuzzy control ammonia injection amount based on the current operating condition value to obtain the actual control ammonia injection amount, and applies the actual control ammonia injection amount to the SCR flue gas denitrification system.

[0012] Preferably, S1 includes:

[0013] S11, Real-time acquisition of raw gas data and various operating load data of the reactor at the current moment from sensors pre-installed in the target boiler unit. The gas types in the reactor's raw gas data include NO. x and O2;

[0014] S12, standardize the original data of various operating conditions of the target boiler unit to obtain the current load data of various operating conditions of the target boiler unit;

[0015] S13, remove NO from the reactor's raw gas data. x The original gas concentration was converted to standard dry 6% O2, yielding NO. x Reactor gas data containing gas concentration data;

[0016] S14: Divide the reactor gas data according to the collection location to obtain the reactor inlet gas concentration data and reactor outlet gas concentration data at the current moment.

[0017] Preferably, S2 includes:

[0018] Based on NO content from various operating load data, reactor inlet gas concentration data, and reactor outlet gas concentration data... x The gas concentration data is used to calculate the simulated ammonia injection rate R of the SCR flue gas denitrification system at the current moment using formulas (1) and (2):

[0019] (1);

[0020] (2);

[0021] In formula (1), Q represents the flue gas flow rate in the current operating load data of the target boiler unit. This indicates the NO concentration in the reactor outlet gas concentration data. xGas concentration, This indicates the NO concentration in the reactor inlet gas concentration data. x Gas concentration, eff represents denitrification efficiency, and ks represents preset ammonia molar ratio;

[0022] In formula (2), This indicates the NO concentration in the reactor outlet gas data. x The original gas concentration, This indicates that NO in the reactor inlet gas concentration data x The original gas concentration.

[0023] Preferably, S3 includes:

[0024] S31, Fuzzy process the reactor outlet gas concentration data and the simulated ammonia injection rate to obtain fuzzy gas concentration data and fuzzy simulated ammonia injection rate;

[0025] S32, Define the fuzzy ranges for the fuzzy gas concentration data and the fuzzy simulated ammonia injection amount according to the preset rule base, and combine the fuzzy gas concentration data, the fuzzy simulated ammonia injection amount and their respective fuzzy ranges to obtain a fuzzy set;

[0026] S33, determine the ammonia injection membership function based on the fuzzy set and the preset rule base, input the fuzzy set into the ammonia injection membership function, and output the fuzzy output set from the ammonia injection membership function;

[0027] S34, defuzzify the fuzzy output set to obtain the adjusted ammonia injection rate, and superimpose the adjusted ammonia injection rate onto the simulated ammonia injection rate to obtain the fuzzy control ammonia injection rate of the SCR flue gas denitrification system at the current moment.

[0028] Preferably, S31 includes:

[0029] S311, calculate the absolute deviation of the single gas concentration between each outlet gas and its corresponding preset emission standard value in the reactor outlet gas concentration data, and calculate the sum of the absolute deviations of the single gas concentration of all outlet gases in the reactor outlet gas concentration data to obtain the absolute deviation of the outlet gas concentration; calculate the absolute deviation of the ammonia injection rate between the simulated ammonia injection rate and the standard ammonia injection rate.

[0030] S312 maps the absolute deviation of the outlet gas concentration and the absolute deviation of the ammonia injection rate to the standard domain of fuzzy control to obtain fuzzy gas concentration data and fuzzy simulated ammonia injection rate.

[0031] Preferably, S4 includes:

[0032] S41, obtain the standard load value corresponding to each type of operating condition load data and the standard outlet gas concentration value corresponding to each type of outlet gas in the reactor outlet gas concentration data;

[0033] S42, calculate the load condition distance based on the load data of each operating condition and the corresponding standard load value, and calculate the gas concentration condition distance based on the reactor outlet gas concentration data of each outlet gas and the corresponding standard outlet gas concentration value.

[0034] S43, calculate the current operating status value of the target boiler unit based on the load operating condition distance and the gas concentration operating condition distance.

[0035] Preferably, S42 includes:

[0036] S421, each standard load value and each standard outlet gas concentration value are respectively used as a cluster center;

[0037] S422, calculate the load distance between the load data of each operating condition and its corresponding cluster center, and calculate the gas concentration distance between the reactor outlet gas concentration data of each outlet gas and its corresponding cluster center;

[0038] S423, calculate the load distance of all load data based on the preset load weight coefficient of each load condition to obtain the load condition distance; calculate the gas concentration distance of all outlet gases based on the preset outlet gas weight of each outlet gas to obtain the gas concentration condition distance.

[0039] Preferably, S5 includes:

[0040] S51, obtain the working status value of each time node within a preset time interval with the current time as the endpoint;

[0041] S52, calculate the current condition gain based on the condition status values ​​of all time points;

[0042] S53 adds the current operating condition gain to the fuzzy control ammonia injection quantity to obtain the actual control ammonia injection quantity, and applies the actual control ammonia injection quantity to the SCR flue gas denitrification system.

[0043] Preferably, S52 includes:

[0044] S521, fit the operating condition values ​​at all time points to obtain the operating condition change curve;

[0045] S522, calculate the gradient of the operating condition change curve at the current moment based on the operating condition change curve, and use the gradient of the operating condition change curve at the current moment as the operating condition gain degree at the current moment.

[0046] All of the above-mentioned optional technical solutions can be combined arbitrarily, and the present invention will not provide a detailed description of the structure after each combination.

[0047] By means of the above solution, the beneficial effects of the present invention are as follows:

[0048] By acquiring real-time load data, reactor inlet gas concentration data, and reactor outlet gas concentration data of the target boiler unit under various operating conditions, and calculating the simulated ammonia injection rate of the SCR flue gas denitrification system based on the acquired data, fuzzy control is applied to the ammonia injection rate of the target boiler unit according to the simulated ammonia injection rate. Applying fuzzy control to the SCR flue gas denitrification system allows for better handling of the nonlinear relationship between the ammonia injection rate and the reactor outlet gas concentration data, providing an accurate control basis for subsequent ammonia injection rate adjustment. Furthermore, by obtaining the current operating condition status value of the target boiler unit based on various load data and reactor outlet gas concentration data, and correcting the fuzzy control ammonia injection rate based on this value, the actual controlled ammonia injection rate is obtained. This achieves the correction of the fuzzy control ammonia injection rate based on the real-time operating condition status of the target boiler unit, solving the problem of poor adaptability of the SCR flue gas denitrification system to operating condition disturbances. It enables adaptive adjustment of the actual controlled ammonia injection rate according to different operating condition changes, allowing the SCR flue gas denitrification system to maintain high control accuracy in complex environments and accurately control the ammonia injection rate to ensure the required gas concentration at the reactor outlet.

[0049] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0050] Figure 1 This is a schematic flowchart of a method for controlling the ammonia injection rate in an SCR flue gas denitrification system of a steel plant, provided by an embodiment of the present invention.

[0051] Figure 2 This is a framework diagram of the main control loop and feedback control loop of the SCR flue gas denitrification system for calculating and simulating ammonia injection quantity, provided in an embodiment of the present invention. Detailed Implementation

[0052] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0053] like Figure 1 As shown, this embodiment of the invention provides a method for controlling the ammonia injection rate in an SCR flue gas denitrification system of a steel plant, comprising the following steps S1 to S5:

[0054] S1 acquires real-time load data, reactor inlet gas concentration data, and reactor outlet gas concentration data for various operating conditions of the target boiler unit at the current moment.

[0055] Specifically, the target boiler unit refers to a boiler system that requires ammonia injection control using the method provided in this embodiment of the invention, including a furnace, air preheater, combustion equipment, heat exchange equipment, and flue gas treatment equipment. The reactor, being part of the flue gas treatment equipment, is used to remove ammonia from the flue gas generated by the combustion equipment to reduce emissions. The gas parameters at the reactor inlet and outlet generally include oxygen and nitrogen oxides (NOx). x In this invention, the focus is solely on oxygen and nitrogen oxides, in addition to sulfides. The types of operating load data include boiler evaporation rate, flue gas flow rate, boiler heat load, and flue gas temperature.

[0056] In one specific embodiment, S1 includes:

[0057] S11, Real-time acquisition of raw gas data and various operating load data of the reactor at the current moment from sensors pre-installed in the target boiler unit. The gas types in the reactor's raw gas data include NO. x And O2.

[0058] Specifically, the sensors include temperature sensors, gas flow sensors, and gas concentration sensors, and all sensors have the same acquisition frequency.

[0059] S12, standardize the original data of various operating conditions of the target boiler unit to obtain the current load data of various operating conditions of the target boiler unit.

[0060] Specifically, when standardizing the raw data of various operating conditions, the standard deviation standardization method is used to uniformly standardize the raw data of various operating conditions to obtain various operating condition load data.

[0061] S13, remove NO from the reactor's raw gas data. x The original gas concentration was converted to standard dry 6% O2, yielding NO. x Reactor gas data containing gas concentration data.

[0062] Specifically, 6% O2 in standard dry state refers to O2 dried at standard temperature and pressure with a concentration limited to 6%; when NO is dried... x When the original gas concentration is converted to 6% O2 in standard dry state, it is achieved through formula (3):

[0063] (3);

[0064] In formula (3), Indicates the converted NO x Gas concentration data, Indicates NO xThe original gas concentration, act(O2) represents the original gas concentration of O2. This indicates that nitric oxide or nitrogen dioxide is present in NO. x The proportion of the original gas concentration. Among them, due to NO x The original gas contains nitric oxide and nitrogen dioxide. When performing standard dry 6% O2 conversion, nitric oxide and nitrogen dioxide need to be converted separately. According to empirical data, nitric oxide in NO... x The proportion of nitric oxide in the original gas concentration is 0.95, so when converting nitric oxide to standard dry 6% O2, The value is 0.95. Similarly, the value corresponding to nitrogen dioxide can be obtained. The value is 0.05. The nitrogen monoxide concentration data after standard dry 6% O2 conversion and the nitrogen dioxide concentration data are added together to obtain the converted NO. x Gas concentration data.

[0065] S14: Divide the reactor gas data according to the collection location to obtain the reactor inlet gas concentration data and reactor outlet gas concentration data at the current moment.

[0066] Specifically, the reactor gas data is divided according to the collection location identifier in the reactor gas data. The reactor gas data with the collection location identifiers "inlet" and "outlet" are selected from the divided reactor gas data as the reactor inlet gas concentration data and reactor outlet gas concentration data.

[0067] S2 calculates the simulated ammonia injection rate of the SCR flue gas denitrification system at the current moment based on various operating load data, reactor inlet gas concentration data, and reactor outlet gas concentration data.

[0068] Specifically, the SCR flue gas denitrification system is a commonly used system for reducing nitrogen oxide emissions in industrial waste gas. The simulated ammonia injection rate refers to the theoretically required amount of ammonia to be injected into the reactor.

[0069] In one specific embodiment, S2 includes:

[0070] Based on NO content from various operating load data, reactor inlet gas concentration data, and reactor outlet gas concentration data... x The gas concentration data is used to calculate the simulated ammonia injection rate R of the SCR flue gas denitrification system at the current moment using formulas (1) and (2):

[0071] (1);

[0072] (2);

[0073] In formula (1), Q represents the flue gas flow rate (unit: m³) in the current operating load data of the target boiler unit. 3 / h), This indicates the NO concentration in the reactor outlet gas concentration data. x Gas concentration (unit: mg / m³) 3 ), This indicates the NO concentration in the reactor inlet gas concentration data. x Gas concentration (unit: mg / m³) 3 ),eff represents the denitrification efficiency, andks represents the preset ammonia molar ratio;

[0074] In formula (2), This indicates the NO concentration in the reactor outlet gas data. x The original gas concentration, This indicates that NO in the reactor inlet gas concentration data x The original gas concentration.

[0075] Specifically, formula (1), based on the chemical principles and material balance of SCR denitrification, calculated the simulated ammonia injection rate of the SCR flue gas denitrification system at the current moment. -6 The purpose is to convert the units of the calculation results from mg / h to the engineering standard units kg / h; the preset ammonia molar ratio is a NO value obtained based on experience. x The ratio of gas concentration to ammonia concentration is typically taken as 0.38065 in this embodiment of the invention.

[0076] Specifically, the principle for calculating the simulated ammonia injection rate R of the SCR flue gas denitrification system at the current moment using formulas (1) and (2) is as follows: Figure 2 As shown, the SCR flue gas denitrification system includes a main control loop and a feedback control loop. The main control loop is the feedforward control loop of the SCR flue gas denitrification system, and the input of the main control loop is the NO concentration data from the reactor inlet gas concentration. x The gas concentration and flue gas flow rate are output as NO that needs to be denitrified. x Total gas volume. However, in actual production, ammonia escape can occur during the denitrification reaction, leading to NO... x Since the gas denitrification reaction is incomplete, this embodiment of the invention uses a feedback control loop based on the reactor outlet gas concentration data to control the NO that needs to be denitrified. x The total gas volume is regulated by feedback. The feedback control loop is implemented through PID control, which adjusts the NO concentration output of the main control loop based on the reactor outlet gas concentration data to control the amount of NO to be denitrated. x The total gas volume is used as the output of the feedback control loop, which serves as the ammonia injection rate feedback adjustment coefficient. The simulated ammonia injection rate is calculated based on the NO₂ required for denitrification. xThe total gas volume is multiplied by the ammonia injection rate adjustment coefficient output by the feedback control loop and the preset ammonia molar ratio.

[0077] Among them, NO that needs to be denitrified x The total gas volume is: NO in the reactor inlet gas concentration data. x The product of gas concentration and flue gas flow rate Multiply by the denitrification efficiency ,Right now The feedback adjustment coefficient for the ammonia injection quantity output by the feedback control loop is: Therefore, the calculation method for the simulated ammonia injection amount is as follows: the NO that needs to be denitrified... x Total gas volume Multiply by the ammonia injection quantity feedback adjustment coefficient output by the feedback control loop. and preset ammonia molar ratio .in, The PID setpoint of the feedback control loop is divided by the reactor outlet gas concentration data. The ammonia injection rate feedback adjustment coefficient is obtained, ranging from 0.7 to 1.3. The reason for multiplying by the preset ammonia molar ratio is... This is because the embodiments of the present invention use NO x The ammonia injection rate is calculated based on the preset ammonia molar ratio, which is determined by NO. x The conversion factor for ammonia.

[0078] The NO3- concentration required for denitrification is adjusted by feedback adjustment coefficient based on the ammonia injection rate output from the feedback control loop. x The total gas volume allows for the accurate calculation of the simulated ammonia injection amount.

[0079] S3. Based on the reactor outlet gas concentration data and the simulated ammonia injection rate, the ammonia injection rate of the target boiler unit is fuzzy controlled to obtain the fuzzy control ammonia injection rate of the SCR flue gas denitrification system up to the current moment.

[0080] Specifically, fuzzy control is a control method based on fuzzy logic. In this embodiment of the invention, the reactor outlet gas concentration data and the simulated ammonia injection amount are fuzzy processed and then fuzzy reasoned, and then defuzzified to output the fuzzy control ammonia injection amount.

[0081] In one specific embodiment, S3 includes:

[0082] S31, the reactor outlet gas concentration data and simulated ammonia injection amount are fuzzed to obtain fuzzy gas concentration data and fuzzy simulated ammonia injection amount.

[0083] Specifically, fuzzy processing converts the reactor outlet gas concentration data and simulated ammonia injection rate from precise numerical values ​​into fuzzy values ​​within the standard universe of discourse. For example, in the reactor outlet gas concentration data, NO...x The fuzzy processing result of gas concentration data of 55% is 100 in the standard universe of discourse.

[0084] In one specific embodiment, S31 includes:

[0085] S311, calculate the absolute deviation of the single gas concentration between each outlet gas and its corresponding preset emission standard value in the reactor outlet gas concentration data, and calculate the sum of the absolute deviations of the single gas concentration of all outlet gases in the reactor outlet gas concentration data to obtain the absolute deviation of the outlet gas concentration; calculate the absolute deviation of the ammonia injection rate between the simulated ammonia injection rate and the standard ammonia injection rate.

[0086] Specifically, the preset emission standard values ​​are the specified emission concentration values ​​for each type of outlet gas after the reactor outlet, obtained through historical experience data and national standards. The standard ammonia injection rate is the ammonia injection rate of the reactor determined based on empirical values.

[0087] S312 maps the absolute deviation of the outlet gas concentration and the absolute deviation of the ammonia injection rate to the standard domain of fuzzy control to obtain fuzzy gas concentration data and fuzzy simulated ammonia injection rate.

[0088] Specifically, the standard universe of discourse (COM) is a concept used in fuzzy control to define the range of input and output variables. After mapping, it represents the possible values ​​of the absolute deviation of the reactor outlet gas concentration and the absolute deviation of the ammonia injection rate. The standard COM typically ranges from -100 to 100. Mapping refers to converting the precise absolute deviation of the outlet gas concentration and the absolute deviation of the ammonia injection rate into specific fuzzy gas concentration data and fuzzy simulated ammonia injection rate within a fuzzy COM. For example, if the absolute deviation of the ammonia injection rate is 50 L / min, then after mapping to the standard COM ([-100, 100]), the fuzzification factor is calculated as 50 divided by 200, which equals 0.25. Based on the fuzzification factor, the fuzzy simulated ammonia injection rate is 50 multiplied by 0.25, which equals 12.5.

[0089] S32, define the fuzzy ranges for the fuzzy gas concentration data and the fuzzy simulated ammonia injection amount according to the preset rule base, and combine the fuzzy gas concentration data, the fuzzy simulated ammonia injection amount and their respective fuzzy ranges to obtain a fuzzy set.

[0090] Specifically, the preset rule base is a table containing fuzzy gas concentration data and fuzzy simulated ammonia injection amount and their corresponding fuzzy range relationships, determined by historical experience and expert knowledge. The preset rule base can match the fuzzy ranges corresponding to the fuzzy gas concentration data and the fuzzy simulated ammonia injection amount, as shown in Table 1, which is an example of a preset rule base.

[0091]

[0092] Specifically, when combining fuzzy gas concentration data and fuzzy simulated ammonia injection amounts and their respective fuzzy ranges to obtain a fuzzy set, a set including all fuzzy gas concentration data and all fuzzy simulated ammonia injection amounts and their respective fuzzy ranges is constructed, and this set is called a fuzzy set.

[0093] S33. Determine the ammonia injection membership function based on the fuzzy set and the preset rule base, input the fuzzy set into the ammonia injection membership function, and output the fuzzy output set from the ammonia injection membership function.

[0094] Specifically, the membership function for ammonia spraying is a function used to describe fuzzy sets, specifically representing the degree of membership of the fuzzy set. Types include triangular membership functions, trapezoidal membership functions, Gaussian membership functions, and Bell membership functions. In this embodiment of the invention, when determining the membership function for ammonia spraying based on the fuzzy set and the preset rule base, since the preset rule base is intuitive and simple to divide, and the types of parameters in the fuzzy set are not complex, the triangular membership function is selected as the membership function type for ammonia spraying.

[0095] The fuzzy set includes each fuzzy gas concentration data and the fuzzy simulated ammonia injection amount, as well as the membership degree of their respective fuzzy ranges. Combining each fuzzy gas concentration data and the fuzzy simulated ammonia injection amount, as well as their respective membership degrees, yields the fuzzy output set.

[0096] S34, defuzzify the fuzzy output set to obtain the adjusted ammonia injection rate, and superimpose the adjusted ammonia injection rate onto the simulated ammonia injection rate to obtain the fuzzy control ammonia injection rate of the SCR flue gas denitrification system at the current moment.

[0097] Specifically, defuzzification converts the fuzzy output set into a precise numerical value. In this embodiment of the invention, the centroid method is used to defuzzify the fuzzy output set using formula (4) to obtain the adjusted ammonia injection rate K:

[0098] (4);

[0099] In formula (4), xi represents the membership degree of the i-th fuzzy gas concentration data in the fuzzy output set, O represents the mean of the membership degrees of all fuzzy gas concentration data, U() represents the membership function, R represents the membership degree of the fuzzy simulated ammonia injection amount in the fuzzy output set, and n represents the number of fuzzy gas concentration data in the fuzzy output set.

[0100] S4 obtains the current operating status value of the target boiler unit based on various operating load data and reactor outlet gas concentration data.

[0101] Specifically, the operating status value is an indicator that describes the current operating status of the target boiler unit.

[0102] In one specific embodiment, S4 includes:

[0103] S41, obtain the standard load value corresponding to each type of operating load data and the standard outlet gas concentration value corresponding to each type of outlet gas in the reactor outlet gas concentration data.

[0104] Specifically, for any given operating load data, the corresponding standard load value is a standard value for the operating load determined based on historical experience. Similarly, for any given outlet gas from the reactor, the corresponding standard outlet gas concentration value is a standard value for the outlet concentration of that gas determined based on historical experience data.

[0105] S42, calculate the load condition distance based on the load data of each operating condition and the corresponding standard load value, and calculate the gas concentration condition distance based on the reactor outlet gas concentration data of each outlet gas and the corresponding standard outlet gas concentration value.

[0106] Specifically, the load condition distance is the cumulative value of the deviation between all load condition data and the corresponding standard load value; the gas concentration condition distance is the cumulative value of the deviation between all reactor outlet gas concentration data and the corresponding standard outlet gas concentration value.

[0107] In one specific embodiment, S42 includes:

[0108] S421, each standard load value and each standard outlet gas concentration value are respectively used as a cluster center.

[0109] Specifically, cluster centers refer to using each standard load value and each standard outlet gas concentration value as "data representatives" to calculate their distances from the corresponding multiple operating condition load data and reactor outlet gas concentration data.

[0110] S422, calculate the load distance between the load data of each operating condition and its corresponding cluster center, and calculate the gas concentration distance between the reactor outlet gas concentration data of each outlet gas and its corresponding cluster center.

[0111] Specifically, the absolute value of the difference between the load data for this operating condition and its corresponding cluster center is calculated as the load distance between the load data for this operating condition and its corresponding cluster center. Similarly, the absolute value of the difference between the reactor outlet gas concentration data for this type of outlet gas and its corresponding cluster center is calculated as the gas concentration distance between the reactor outlet gas concentration data for this type of outlet gas and its corresponding cluster center.

[0112] S423, calculate the load distance of all load data based on the preset load weight coefficient of each load condition to obtain the load condition distance; calculate the gas concentration distance of all outlet gases based on the preset outlet gas weight of each outlet gas to obtain the gas concentration condition distance.

[0113] Specifically, the preset load weight coefficient for each load condition is a value determined empirically to represent the degree of influence of each load condition on the load condition distance; the preset outlet gas weight for each outlet gas is a value determined empirically to represent the degree of influence of each outlet gas on the gas concentration condition distance.

[0114] S43, calculate the current operating status value of the target boiler unit based on the load operating condition distance and the gas concentration operating condition distance.

[0115] Specifically, the superimposed value is obtained by superimposing the load condition distance and the gas concentration condition distance, and the superimposed value is multiplied by 100 to obtain the current operating condition value of the target boiler unit.

[0116] S5 corrects the fuzzy control ammonia injection amount based on the current operating condition value to obtain the actual control ammonia injection amount, and applies the actual control ammonia injection amount to the SCR flue gas denitrification system.

[0117] Specifically, the current operating status value is superimposed on the fuzzy control ammonia injection quantity to obtain the actual controlled ammonia injection quantity.

[0118] In one specific embodiment, S5 includes:

[0119] S51, obtain the operating status value of each time node within a preset time interval with the current time as the endpoint.

[0120] Specifically, the preset time interval is generally 30 minutes. Adjacent time points are typically spaced 1 second apart. The preset time interval usually contains 1800 time points.

[0121] S52 calculates the current operating condition gain based on the operating condition status values ​​of all time points.

[0122] Specifically, operating condition gain refers to the degree of change in operating conditions at the current moment.

[0123] In one specific embodiment, S52 includes:

[0124] S521, fit the operating condition values ​​at all time points to obtain the operating condition change curve.

[0125] Specifically, the operating condition values ​​at all time points are input into a preset polynomial function. Then, the optimal parameters of the preset polynomial function are calculated using the least squares method. The optimal parameters are then configured into the preset polynomial function to obtain the operating condition change curve. The preset polynomial is usually a cubic polynomial.

[0126] S522, calculate the gradient of the operating condition change curve at the current moment based on the operating condition change curve, and use the gradient of the operating condition change curve at the current moment as the operating condition gain degree at the current moment.

[0127] Specifically, the first derivative of the operating condition change curve with respect to time is calculated to obtain the gradient of the operating condition change curve at the current moment.

[0128] S53 adds the current operating condition gain to the fuzzy control ammonia injection quantity to obtain the actual control ammonia injection quantity, and applies the actual control ammonia injection quantity to the SCR flue gas denitrification system.

[0129] Specifically, the actual controlled ammonia injection rate is used as the ammonia injection rate control rate of the SCR flue gas denitrification system, and ammonia is injected into the reactor through the SCR flue gas denitrification system.

[0130] Based on all the above embodiments, the ammonia injection quantity control method for an SCR flue gas denitrification system in a steel plant provided by this invention has the following beneficial effects:

[0131] By acquiring real-time load data, reactor inlet gas concentration data, and reactor outlet gas concentration data of the target boiler unit at various operating conditions, and calculating the simulated ammonia injection rate of the SCR flue gas denitrification system at the current moment, a basic value for controlling the ammonia injection rate of the SCR flue gas denitrification system at the current moment is provided. The simulated ammonia injection rate is determined based on various load data and reactor inlet and outlet gas concentration data, and is related to the current operating status of the SCR flue gas denitrification system. This allows the determined simulated ammonia injection rate to be combined with the real-time operating conditions and adapt to disturbances in the operating condition parameters.

[0132] By performing fuzzy control on the ammonia injection rate of the target boiler unit based on the reactor outlet gas concentration data and the simulated ammonia injection rate, the fuzzy control ammonia injection rate of the SCR flue gas denitrification system at the current moment is obtained. By applying fuzzy control theory to the SCR flue gas denitrification system, the nonlinear relationship between the ammonia injection rate and the reactor outlet gas concentration data can be better handled through fuzzy control, so that the fuzzy control ammonia injection rate can provide an accurate control basis for subsequent ammonia injection rate adjustment.

[0133] By obtaining the current operating status value of the target boiler unit based on various operating load data and reactor outlet gas concentration data, and correcting the fuzzy control ammonia injection amount based on the operating status value, the actual controlled ammonia injection amount is obtained. This achieves the correction of the fuzzy control ammonia injection amount by combining the current operating status value, ensuring that a more accurate, stable, and efficient ammonia injection amount can be provided, thereby maximizing denitrification efficiency, saving energy and reducing consumption, and minimizing environmental pollution.

[0134] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for controlling ammonia injection rate in an SCR flue gas denitrification system of a steel plant, characterized in that, include: S1, real-time acquisition of various operating load data, reactor inlet gas concentration data, and reactor outlet gas concentration data of the target boiler unit at the current moment; S2, calculate the simulated ammonia injection rate of the SCR flue gas denitrification system at the current moment based on various operating load data, reactor inlet gas concentration data and reactor outlet gas concentration data; S2 includes: According to the NOx in the various working condition load data, the reactor inlet gas concentration data and the reactor outlet gas concentration data x The gas concentration data, the simulated ammonia injection amount R of the SCR flue gas denitration system at the current moment is calculated by formula (1) and formula (2): （1）； （2）； In formula (1), Q represents the flue gas flow rate in the current operating load data of the target boiler unit. This indicates the NO concentration in the reactor outlet gas concentration data. x Gas concentration, This indicates the NO concentration in the reactor inlet gas concentration data. x Gas concentration, eff represents denitrification efficiency, and ks represents preset ammonia molar ratio; In formula (2), This indicates the NO concentration in the reactor outlet gas data. x The original gas concentration, This indicates the NO concentration in the reactor inlet gas data. x The original gas concentration; S3, based on the reactor outlet gas concentration data and the simulated ammonia injection rate, perform fuzzy control on the ammonia injection rate of the target boiler unit to obtain the fuzzy control ammonia injection rate of the SCR flue gas denitrification system at the current moment. S4, obtain the current operating status value of the target boiler unit based on various operating load data and reactor outlet gas concentration data; S5, correct the fuzzy control ammonia injection amount according to the current operating condition value, obtain the actual control ammonia injection amount, and apply the actual control ammonia injection amount to the SCR flue gas denitrification system. S5 includes: S51, obtain the working status value of each time node within a preset time interval with the current time as the endpoint; S52, calculate the current condition gain based on the condition status values ​​of all time points; S53 adds the current operating condition gain to the fuzzy control ammonia injection quantity to obtain the actual control ammonia injection quantity, and applies the actual control ammonia injection quantity to the SCR flue gas denitrification system.

2. The method for controlling ammonia injection quantity in an SCR flue gas denitrification system of a steel plant according to claim 1, characterized in that, S1 includes: S11, Real-time acquisition of raw gas data and various operating load data of the reactor at the current moment from sensors pre-installed in the target boiler unit. The gas types in the reactor's raw gas data include NO. x and O2; S12, standardize the original data of various operating conditions of the target boiler unit to obtain the current load data of various operating conditions of the target boiler unit; S13, remove NO from the reactor's raw gas data. x The original gas concentration was converted to standard dry 6% O2, yielding NO. x Reactor gas data containing gas concentration data; S14: Divide the reactor gas data according to the collection location to obtain the reactor inlet gas concentration data and reactor outlet gas concentration data at the current moment.

3. The method for controlling ammonia injection quantity in an SCR flue gas denitrification system of a steel plant according to claim 1, characterized in that, S3 includes: S31, Fuzzy process the reactor outlet gas concentration data and the simulated ammonia injection rate to obtain fuzzy gas concentration data and fuzzy simulated ammonia injection rate; S32, Define the fuzzy ranges for the fuzzy gas concentration data and the fuzzy simulated ammonia injection amount according to the preset rule base, and combine the fuzzy gas concentration data, the fuzzy simulated ammonia injection amount and their respective fuzzy ranges to obtain a fuzzy set; S33, determine the ammonia injection membership function based on the fuzzy set and the preset rule base, input the fuzzy set into the ammonia injection membership function, and output the fuzzy output set from the ammonia injection membership function; S34, defuzzify the fuzzy output set to obtain the adjusted ammonia injection rate, and superimpose the adjusted ammonia injection rate onto the simulated ammonia injection rate to obtain the fuzzy control ammonia injection rate of the SCR flue gas denitrification system at the current moment.

4. The method for controlling ammonia injection quantity in an SCR flue gas denitrification system of a steel plant according to claim 3, characterized in that, S31 includes: S311, calculate the absolute deviation of the single gas concentration between each outlet gas and its corresponding preset emission standard value in the reactor outlet gas concentration data, and calculate the sum of the absolute deviations of the single gas concentration of all outlet gases in the reactor outlet gas concentration data to obtain the absolute deviation of the outlet gas concentration; calculate the absolute deviation of the ammonia injection rate between the simulated ammonia injection rate and the standard ammonia injection rate. S312 maps the absolute deviation of the outlet gas concentration and the absolute deviation of the ammonia injection rate to the standard domain of fuzzy control to obtain fuzzy gas concentration data and fuzzy simulated ammonia injection rate.

5. The method for controlling ammonia injection quantity in an SCR flue gas denitrification system of a steel plant according to claim 1, characterized in that, S4 includes: S41, obtain the standard load value corresponding to each type of operating condition load data and the standard outlet gas concentration value corresponding to each type of outlet gas in the reactor outlet gas concentration data; S42, calculate the load condition distance based on the load data of each operating condition and the corresponding standard load value, and calculate the gas concentration condition distance based on the reactor outlet gas concentration data of each outlet gas and the corresponding standard outlet gas concentration value. S43, calculate the current operating status value of the target boiler unit based on the load operating condition distance and the gas concentration operating condition distance.

6. The method for controlling ammonia injection quantity in an SCR flue gas denitrification system of a steel plant according to claim 5, characterized in that, S42 includes: S421, each standard load value and each standard outlet gas concentration value are respectively used as a cluster center; S422, calculate the load distance between the load data of each operating condition and its corresponding cluster center, and calculate the gas concentration distance between the reactor outlet gas concentration data of each outlet gas and its corresponding cluster center; S423, calculate the load distance of all load data based on the preset load weight coefficient of each load condition to obtain the load condition distance; calculate the gas concentration distance of all outlet gases based on the preset outlet gas weight of each outlet gas to obtain the gas concentration condition distance.

7. The method for controlling ammonia injection quantity in an SCR flue gas denitrification system of a steel plant according to claim 1, characterized in that, S52 includes: S521, fit the operating condition values ​​at all time points to obtain the operating condition change curve; S522, calculate the gradient of the operating condition change curve at the current moment based on the operating condition change curve, and use the gradient of the operating condition change curve at the current moment as the operating condition gain degree at the current moment.

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