Ammonia spraying amount control method for SCR (Selective Catalytic Reduction) flue gas denitration system of iron and steel plant

Abstract

The invention relates to an ammonia spraying amount control method for a steel plant SCR flue gas denitration system, and belongs to the technical field of ammonia spraying amount control. The method comprises the following steps: acquiring various working condition load data and reactor gas concentration data of a target boiler unit, and calculating the simulated ammonia spraying amount of the SCR flue gas denitration system at the current moment; obtaining the fuzzy control ammonia spraying amount at the current moment according to the gas concentration data of the reactor and the simulated ammonia spraying amount, and obtaining a working condition state value according to the various working condition load data; and obtaining the actual control ammonia injection amount according to the working condition state value, and applying the actual control ammonia injection amount to the system. The ammonia spraying amount can be adjusted and actually controlled in a self-adaptive mode according to changes of different working conditions, and the control precision of the SCR flue gas denitration system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ammonia injection amount control system, and particularly relates to an ammonia injection amount control method for an SCR flue gas denitration system of a steel plant. BACKGROUND

[0002] Coal smoke contains a large amount of NO x If the NO x emission is excessive, acid rain will be caused, resulting in environmental pollution. The NO x emission and ammonia injection amount in the denitration system are important objects of attention. The SCR flue gas denitration technology has become mature in recent years. The SCR flue gas denitration system based on the technology can effectively solve the NO x emission and ammonia escape amount in flue gas. At present, the technology has been widely applied in large steel plants.

[0003] The difficulty of the SCR flue gas denitration system control lies in the control of the ammonia injection amount. When the ammonia injection amount of the SCR flue gas denitration system is controlled, the proportional coefficient, integral time and differential time of experience are usually given, and the PID controller is used to adjust the ammonia injection amount of the SCR flue gas denitration system until the ammonia injection amount flow is stable, so that the gas concentration at the outlet of the reactor of the SCR flue gas denitration system reaches the requirement.

[0004] However, in a complex industrial environment, the SCR flue gas denitration system will be disturbed by various working condition state parameters, such as furnace temperature change, gas flow rate change and flue gas flow. The traditional PID controller relies on fixed parameters (proportional coefficient, integral time and differential time) to control the ammonia injection amount. The adaptability to the above working condition state parameter disturbance is poor, resulting in poor control result precision. Moreover, since the relationship between the ammonia injection amount and the reactor outlet gas concentration is usually nonlinear, the ammonia injection amount cannot be accurately controlled by the PID controller. SUMMARY

[0005] To solve the above technical problems, the present application provides an ammonia injection amount control method for an SCR flue gas denitration system of a steel plant. The technical scheme of the present application is as follows: An ammonia injection amount control method for an SCR flue gas denitration system of a steel plant, comprising: S1, acquiring in real time multiple working condition load data, reactor inlet gas concentration data and reactor outlet gas concentration data of a target boiler unit at the current time; S2, calculating the simulated ammonia injection amount of the SCR flue gas denitration system at the current time according to the multiple working condition load data, the reactor inlet gas concentration data and the reactor outlet gas concentration data; S3, according to the reactor outlet gas concentration data and the simulated ammonia injection amount, the ammonia injection amount of the target boiler unit is controlled by fuzzy control, and the fuzzy control ammonia injection amount of the SCR flue gas denitration system at the current time is obtained; S4, according to the multiple working condition load data and the reactor outlet gas concentration data, the working condition state value of the target boiler unit at the current time is obtained; S5, according to the working condition state value at the current time, the fuzzy control ammonia injection amount is corrected to obtain the actual control ammonia injection amount, and the actual control ammonia injection amount is applied to the SCR flue gas denitration system.

[0006] Preferably, the S1 comprises: S11, according to the real-time acquisition of the sensor pre-installed in the target boiler unit, the gas original data of the reactor and the multiple working condition load original data of the target boiler unit at the current time are collected, wherein the gas species of the gas original data of the reactor includes NO x and O2; S12, the multiple working condition load original data of the target boiler unit is standardized to obtain the multiple working condition load data of the target boiler unit at the current time; S13, the original gas concentration of NO x in the reactor gas original data is converted into standard dry state 6% O2, and the reactor gas data including NO x gas concentration data is obtained; S14, the reactor gas data is divided according to the collection position to obtain the reactor inlet gas concentration data and the reactor outlet gas concentration data at the current time.

[0007] Preferably, the S2 comprises: According to the multiple working condition load data, the reactor inlet gas concentration data and the NO x gas concentration data in the reactor outlet gas concentration data, the simulated ammonia injection amount R of the SCR flue gas denitration system at the current time is calculated by formula (1) and formula (2): (1); (2); In formula (1), Q represents the flue gas flow in the working condition load data of the target boiler unit at the current time, represents the NO x gas concentration in the reactor outlet gas concentration data, represents the NO x gas concentration in the reactor inlet gas concentration data, and eff represents the denitration efficiency and ks represents the preset ammonia molar ratio; In formula (2), represents the NO xthe original gas concentration of NOx, the NOx concentration data of the reactor inlet gas, x the original gas concentration of NOx.

[0008] Preferably, the S3 comprises: S31, fuzzy processing the reactor outlet gas concentration data and the simulated ammonia injection amount to obtain fuzzy gas concentration data and fuzzy simulated ammonia injection amount; S32, defining respective fuzzy ranges for the fuzzy gas concentration data and the fuzzy simulated ammonia injection amount according to a preset rule base, combining the fuzzy gas concentration data and the fuzzy simulated ammonia injection amount and their respective fuzzy ranges to obtain a fuzzy set; S33, determining an ammonia injection membership function according to the fuzzy set and the preset rule base, inputting the fuzzy set into the ammonia injection membership function, and outputting a fuzzy output set from the ammonia injection membership function; S34, defuzzifying the fuzzy output set to obtain an adjusted ammonia injection amount, and superimposing the adjusted ammonia injection amount on the simulated ammonia injection amount to obtain the fuzzy control ammonia injection amount of the SCR flue gas denitrification system at the current time.

[0009] Preferably, the S31 comprises: S311, calculating the single gas concentration absolute deviation value between each outlet gas in the reactor outlet gas concentration data and its corresponding preset emission standard value, and calculating the sum of the single gas concentration absolute deviation values of all outlet gases in the reactor outlet gas concentration data to obtain the outlet gas concentration absolute deviation value; and calculating the ammonia injection amount absolute deviation value between the simulated ammonia injection amount and the standard ammonia injection amount; S312, mapping the outlet gas concentration absolute deviation value and the ammonia injection amount absolute deviation value to the standard domain of fuzzy control to obtain the fuzzy gas concentration data and the fuzzy simulated ammonia injection amount.

[0010] Preferably, the S4 comprises: S41, obtaining the standard load value corresponding to each load data and the standard outlet gas concentration value corresponding to each outlet gas in the reactor outlet gas concentration data; S42, calculating the load condition distance according to each load data and the corresponding standard load value, and calculating the gas concentration condition distance according to the reactor outlet gas concentration data of each outlet gas and the corresponding standard outlet gas concentration value; S43, calculating the condition state value of the target boiler unit at the current time according to the load condition distance and the gas concentration condition distance.

[0011] Preferably, the S42 comprises: S421, respectively taking each standard load value and each standard outlet gas concentration value as a clustering center; S422, calculate the load distance between each operating condition load data 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, according to the preset load weight coefficient of each operating condition load data, the load distances of all operating condition load data are weighted and calculated to obtain the load condition distance; according to the preset outlet gas weight of each outlet gas, the gas concentration distances of all outlet gases are weighted and calculated to obtain the gas concentration condition distance.

[0012] Preferably, the S5 comprises: S51, obtaining the operating condition state value of each time node in a preset time interval with the current time as the terminal point; S52, calculating the operating condition gain degree of the current time according to the operating condition state values of all time nodes; S53, superimposing the operating condition gain degree of the current time to the fuzzy control ammonia injection amount to obtain the actual control ammonia injection amount, and applying the actual control ammonia injection amount to the SCR flue gas denitrification system.

[0013] Preferably, the S52 comprises: S521, fitting the operating condition state values of all time nodes to obtain the operating condition change curve; S522, calculating the gradient of the operating condition change curve at the current time according to the operating condition change curve, and taking the gradient of the operating condition change curve at the current time as the operating condition gain degree at the current time.

[0014] All the optional technical solutions described above can be combined arbitrarily, and the application does not describe the structures after one-by-one combination in detail.

[0015] Through the above scheme, the application has the following beneficial effects: After obtaining the current time load data of various working conditions of the target boiler unit, the reactor inlet gas concentration data and the reactor outlet gas concentration data in real time, and calculating the simulated ammonia injection amount of the SCR flue gas denitration system at the current time based on the obtained data, the ammonia injection amount of the target boiler unit is controlled according to the simulated ammonia injection amount. The fuzzy control is applied to the SCR flue gas denitration system, and the nonlinear change relationship between the ammonia injection amount and the reactor outlet gas concentration data can be better handled through the fuzzy control, thereby providing an accurate control basis for subsequent ammonia injection amount adjustment. The working condition state value of the target boiler unit at the current time is obtained according to the load data of various working conditions and the reactor outlet gas concentration data, and the fuzzy control ammonia injection amount is corrected according to the working condition state value at the current time to obtain the actual control ammonia injection amount, so as to correct the fuzzy control ammonia injection amount according to the real-time working condition state of the target boiler unit, solve the problem of poor adaptability of the SCR flue gas denitration system to working condition disturbance, and realize self-adaptive adjustment of the actual control ammonia injection amount according to different working condition changes, so that the SCR flue gas denitration system can maintain high control precision in a complex environment, and the ammonia injection amount can be accurately controlled to make the gas concentration at the reactor outlet meet the requirements.

[0016] The above description is only a summary of the technical scheme of the present application. In order to more clearly understand the technical means of the present application and can be implemented according to the content of the description, the following will be described in detail with the preferred embodiments of the present application and with the help of the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a flowchart of a method for controlling the ammonia injection amount of the SCR flue gas denitration system of a steel plant provided by an embodiment of the present application.

[0018] Figure 2 It is a framework diagram for calculating the simulated ammonia injection amount based on the main control loop and the feedback control loop of the SCR flue gas denitration system provided by an embodiment of the present application. DETAILED DESCRIPTION

[0019] The specific embodiments of the present application will be further described in detail below in combination with the drawings and embodiments. The following embodiments are used to illustrate the present application, but not to limit the scope of the present application.

[0020] As shown in Figure 1 , the present application provides a method for controlling the ammonia injection amount of the SCR flue gas denitration system of a steel plant, which includes the following steps S1 to S5: S1, obtaining the load data of various working conditions, the reactor inlet gas concentration data and the reactor outlet gas concentration data of the target boiler unit at the current time in real time.

[0021] Specifically, the target boiler unit refers to a boiler system that needs to control the amount of ammonia injection by the method provided in the embodiments of the present application, including a furnace, an air preheater, a combustion device, a heat exchange device, and a flue gas treatment device. The reactor belongs to a part of the flue gas treatment device, which is used for deamination treatment of flue gas generated by the combustion device to reduce emission pollution. The types of gas parameters at the inlet and outlet of the reactor generally include oxygen, nitrogen oxides (NO x ) and sulfides, and only oxygen and nitrogen oxides are the research objects in the embodiments of the present application. The types of working condition load data include boiler evaporation capacity, flue gas flow, boiler heat load, and flue gas outlet temperature, etc.

[0022] In a specific embodiment, the S1 includes: S11, collecting, in real time, gas original data of the reactor and a plurality of working condition load original data of the target boiler unit at the current time according to sensors pre-installed in the target boiler unit, wherein the types of gas of the gas original data of the reactor include NO x and O2.

[0023] Specifically, the sensors include temperature sensors, gas flow sensors, and gas concentration sensors, etc., and the collection frequencies of all the sensors are the same.

[0024] S12, standardizing the plurality of working condition load original data of the target boiler unit to obtain a plurality of working condition load data of the target boiler unit at the current time.

[0025] Specifically, when the plurality of working condition load original data is standardized, the plurality of working condition load original data is uniformly standardized by a standard deviation standardization method to obtain the plurality of working condition load data.

[0026] S13, converting the original gas concentration of NO x in the gas original data of the reactor into a standard dry state 6% O2 to obtain reactor gas data including NO x gas concentration data.

[0027] Specifically, the standard dry state 6% O2 means that the dry concentration of O2 is limited to 6% under standard temperature and pressure; when the original gas concentration of NO x is converted into the standard dry state 6% O2, it is realized by formula (3): (3); In formula (3), represents the converted NO x gas concentration data, represents the original gas concentration of NO x , and act(O2) represents the original gas concentration of O2, represents the proportion of nitric oxide or nitrogen dioxide in the original gas concentration of NO x . Since the original gas of NO x contains nitric oxide and nitrogen dioxide, the conversion of nitric oxide and nitrogen dioxide is required when the standard dry 6% O2 conversion is performed. According to empirical data, the proportion of nitric oxide in the original gas concentration of NO x is 0.95, so when the standard dry 6% O2 conversion of nitric oxide is performed, is 0.95, and the corresponding of nitrogen dioxide is 0.05. The converted NO x gas concentration data is obtained by adding the nitric oxide gas concentration data and the nitrogen dioxide gas concentration data after the standard dry 6% O2 conversion.

[0028] S14, the reactor gas data is divided according to the collection position to obtain the reactor inlet gas concentration data and the reactor outlet gas concentration data at the current time.

[0029] Specifically, the reactor gas data is divided according to the collection position according to the collection position identifier in the reactor gas data, and the reactor gas data with collection position identifier of “inlet” and “outlet” is selected from the divided reactor gas data as the reactor inlet gas concentration data and the reactor outlet gas concentration data.

[0030] S2, the simulated ammonia injection amount of the SCR flue gas denitration system at the current time is calculated according to the multiple working condition load data, the reactor inlet gas concentration data and the reactor outlet gas concentration data.

[0031] Specifically, the SCR flue gas denitration system is a system commonly used to reduce the emission of nitrogen oxides in industrial waste gas. The simulated ammonia injection amount refers to the amount of ammonia that should be theoretically injected into the reactor.

[0032] In one specific embodiment, the S2 comprises: According to the NO x gas concentration data in the multiple working condition load data, the reactor inlet gas concentration data and the reactor outlet gas concentration data, the simulated ammonia injection amount R of the SCR flue gas denitration system at the current time is calculated through formula (1) and formula (2): (1); (2); In formula (1), Q represents the flue gas flow (unit: m 3 / h) in the working condition load data of the target boiler unit at the current time, represents the NO xGas concentration (unit: mg / m 3 ), represents the original gas concentration of NO x Gas concentration (unit: mg / m 3 ), eff represents the denitration efficiency, and ks represents the preset ammonia molar ratio; In formula (2), represents the original gas concentration of NO x in the reactor outlet gas concentration data, represents the original gas concentration of NO x in the reactor inlet gas concentration data.

[0033] Specifically, formula (1) completes the calculation of the simulated ammonia injection amount of the SCR flue gas denitration system at the current moment based on the chemical principle and material balance of SCR denitration, 10 -6 The purpose is to convert the unit of the calculation result from mg / h to kg / h; the preset ammonia molar ratio is a ratio of NO x gas concentration to ammonia concentration obtained according to an empirical value, which is usually taken as 0.38065 in the embodiment of the present application.

[0034] Specifically, the principle of calculating the simulated ammonia injection amount R of the SCR flue gas denitration system at the current moment by formula (1) and formula (2) is as follows: as shown in Figure 2 , the SCR flue gas denitration system includes a main control loop and a feedback control loop. The main control loop is a feedforward control loop of the SCR flue gas denitration system, the input of the main control loop is the NO x gas concentration in the reactor inlet gas concentration data and the flue gas flow, and the output is the total amount of NO x gas that needs to be denitrified. However, in actual production, ammonia escape phenomenon may occur in the denitration reaction, resulting in incomplete denitration reaction of NO x gas, so the embodiment of the present application feeds back and adjusts the total amount of NO x gas that needs to be denitrified according to the reactor outlet gas concentration data through the feedback control loop. The feedback control loop is realized by PID control, which feeds back and adjusts the total amount of NO x gas that needs to be denitrified output by the main control loop through the reactor outlet gas concentration data, and the output of the feedback control loop is the ammonia injection amount feedback adjustment coefficient. The calculation method of the simulated ammonia injection amount is that the total amount of NO x gas that needs to be denitrified is multiplied by the ammonia injection amount feedback adjustment coefficient output by the feedback control loop and the preset ammonia molar ratio.

[0035] The total amount of NO x gas that needs to be denitrified is the product of the NO x gas concentration in the reactor inlet gas concentration data and the flue gas flow , multiplied by the denitration efficiency , namely . The feedback adjustment coefficient of the ammonia injection amount output by the feedback control loop is . Therefore, the calculation method of the simulation ammonia injection amount is: the total amount of NOx x gas that needs to be denitrified , multiplied by the feedback adjustment coefficient of the ammonia injection amount output by the feedback control loop , and the preset ammonia molar ratio . Wherein, is the PID set value of the feedback control loop, divided by the reactor outlet gas concentration data to obtain the feedback adjustment coefficient of the ammonia injection amount, which ranges from 0.7 to 1.3. The reason for multiplying the preset ammonia molar ratio is that the embodiment of the present application calculates the ammonia injection amount by NOx x , and the conversion coefficient of the preset ammonia molar ratio is converted from NOx x to ammonia.

[0036] By feeding back the total amount of NOx x gas that needs to be denitrified calculated by the main control loop according to the feedback adjustment coefficient of the ammonia injection amount output by the feedback control loop, the accurate value of the simulation ammonia injection amount can be scientifically calculated.

[0037] S3, according to the reactor outlet gas concentration data and the simulation ammonia injection amount, carries out fuzzy control on the ammonia injection amount of the target boiler unit to obtain the fuzzy control ammonia injection amount of the SCR flue gas denitrification system at the current moment.

[0038] Specifically, fuzzy control is a control method based on fuzzy logic. The embodiment of the present application carries out fuzzy reasoning after fuzzy processing the reactor outlet gas concentration data and the simulation ammonia injection amount, and then de-fuzzies to output the fuzzy control ammonia injection amount.

[0039] In a specific embodiment, the S3 comprises: S31, fuzzy processing the reactor outlet gas concentration data and the simulation ammonia injection amount to obtain fuzzy gas concentration data and fuzzy simulation ammonia injection amount.

[0040] Specifically, the fuzzy processing is to convert the reactor outlet gas concentration data and the simulation ammonia injection amount from accurate values to fuzzy values in the standard domain. For example, the fuzzy processing result of the NOx x gas concentration data of 55% in the reactor outlet gas concentration data is 100 in the standard domain.

[0041] In a specific embodiment, the S31 comprises: S311, calculate the single gas concentration absolute deviation value between each outlet gas in the reactor outlet gas concentration data and its corresponding preset emission standard value, and calculate the sum of the single gas concentration absolute deviation values of all outlet gases in the reactor outlet gas concentration data to obtain the outlet gas concentration absolute deviation value; calculate the absolute deviation value of the simulated ammonia injection amount and the standard ammonia injection amount.

[0042] Specifically, the preset emission standard value is the specified emission concentration value of each outlet gas after the reactor outlet obtained through historical experience data and national standards. The standard ammonia injection amount is the numerical value of the ammonia injection amount of the reactor determined according to the experience value.

[0043] S312, map the outlet gas concentration absolute deviation value and the ammonia injection amount absolute deviation value to the standard domain of fuzzy control to obtain fuzzy gas concentration data and fuzzy simulated ammonia injection amount.

[0044] Specifically, the standard domain is a concept used to define the range of input and output variables in fuzzy control, and after mapping, it represents the possible values of the reactor outlet gas concentration absolute deviation value and the ammonia injection amount absolute deviation value; the general range of the standard domain is [-100, 100]. Mapping refers to converting the precise outlet gas concentration absolute deviation value and the ammonia injection amount absolute deviation value into specific fuzzy gas concentration data and fuzzy simulated ammonia injection amount in a fuzzy domain. For example, if the ammonia injection amount absolute deviation value is 50 L / min, then after mapping to the standard domain ([−100, 100]), the calculation fuzzy factor is 50 divided by 200, which is equal to 0.25, and the fuzzy simulated ammonia injection amount obtained according to the fuzzy factor is 50 multiplied by 0.25, which is equal to 12.5.

[0045] S32, define the respective fuzzy ranges for the fuzzy gas concentration data and the fuzzy simulated ammonia injection amount according to the preset rule base, combine the fuzzy gas concentration data and the fuzzy simulated ammonia injection amount and their respective fuzzy ranges to obtain a fuzzy set.

[0046] Specifically, the preset rule base is a table containing the relationship between the fuzzy gas concentration data and the fuzzy simulated ammonia injection amount and their corresponding fuzzy ranges determined by historical experience and expert knowledge; the preset rule base can match the fuzzy range 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.

[0047]

[0048] Specifically, when combining the fuzzy gas concentration data and the fuzzy simulated ammonia injection amount and their respective fuzzy ranges to obtain a fuzzy set, a set including all fuzzy gas concentration data and all fuzzy simulated ammonia injection amount and their respective fuzzy ranges is constructed, and the set is the fuzzy set.

[0049] S33, determining the ammonia injection membership function according to the fuzzy set and the preset rule base, inputting the fuzzy set into the ammonia injection membership function, and outputting a fuzzy output set from the ammonia injection membership function.

[0050] Specifically, the ammonia injection membership function is a function for describing the fuzzy set, and is specifically used for representing the membership degree of the fuzzy set. The types include a triangular membership function, a trapezoidal membership function, a Gaussian membership function, and a Bell membership function. In the embodiment of the present application, when the ammonia injection membership function is determined according to the fuzzy set and the preset rule base, the preset rule base is intuitively and simply divided, and the parameter types of the fuzzy set are not complex, so the type of the ammonia injection membership function is selected as the triangular membership function.

[0051] The fuzzy set includes the membership degrees of each fuzzy gas concentration data and fuzzy simulated ammonia injection amount and their respective fuzzy ranges. The fuzzy output set is obtained by combining each fuzzy gas concentration data and fuzzy simulated ammonia injection amount and their respective membership degrees.

[0052] S34, defuzzifying the fuzzy output set to obtain an adjusted ammonia injection amount, and superimposing the adjusted ammonia injection amount on the simulated ammonia injection amount to obtain a fuzzy control ammonia injection amount of the SCR flue gas denitrification system at the current time.

[0053] Specifically, defuzzification is to convert the fuzzy output set into an accurate numerical value. In the embodiment of the present application, the gravity method is used to defuzzify the fuzzy output set through formula (4) to obtain the adjusted ammonia injection amount K: (4); In formula (4), xi represents the membership degree of the i th fuzzy gas concentration data in the fuzzy output set, O represents the average value 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.

[0054] S4, obtaining a working condition state value of the target boiler unit at the current time according to the plurality of working condition load data and the reactor outlet gas concentration data.

[0055] Specifically, the working condition state value is an index for describing the running state of the target boiler unit at the current time.

[0056] In one specific embodiment, the S4 includes: S41, obtaining a standard load value corresponding to each working condition load data and a standard outlet gas concentration value corresponding to each outlet gas in the reactor outlet gas concentration data.

[0057] Specifically, for any kind of operating condition load data, the corresponding standard load value is the operating condition load standard value determined according to historical experience value. For any kind of reactor outlet gas, the corresponding standard outlet gas concentration value is the standard value of the outlet concentration of the outlet gas determined according to historical experience data.

[0058] S42, calculate the load condition distance according to each operating condition load data and the corresponding standard load value, and calculate the gas concentration condition distance according to the reactor outlet gas concentration data of each outlet gas and the corresponding standard outlet gas concentration value.

[0059] Specifically, the load condition distance is the cumulative value of the deviation degree between all operating condition load data and the corresponding standard load value; and the gas concentration condition distance is the cumulative value of the deviation degree between the reactor outlet gas concentration data of all outlet gases and the corresponding standard outlet gas concentration value.

[0060] In a specific embodiment, the S42 comprises: S421, respectively take each standard load value and each standard outlet gas concentration value as a clustering center.

[0061] Specifically, the clustering center refers to taking each standard load value and each standard outlet gas concentration value as a "data representative" for calculating the distance between them and the corresponding operating condition load data and reactor outlet gas concentration data.

[0062] S422, calculate the load distance between each operating condition load data and its corresponding clustering center, and calculate the gas concentration distance between the reactor outlet gas concentration data of each outlet gas and its corresponding clustering center.

[0063] Specifically, by calculating the absolute value of the difference between the operating condition load data and its corresponding clustering center, the load distance between the operating condition load data and its corresponding clustering center is obtained. By calculating the absolute value of the difference between the reactor outlet gas concentration data of the outlet gas and its corresponding clustering center, the gas concentration distance between the reactor outlet gas concentration data of the outlet gas and its corresponding clustering center is obtained.

[0064] S423, weight all operating condition load data according to the preset load weight coefficient of each operating condition load data to obtain the load condition distance; and weight all outlet gas according to the preset outlet gas weight of each outlet gas to obtain the gas concentration condition distance.

[0065] Specifically, the preset load weight coefficient of each load condition data is a value determined by an experience value and representing an influence degree of each load condition data on the load condition distance; and the preset outlet gas weight of each outlet gas is a value determined by an experience value and representing an influence degree of each outlet gas on the gas concentration condition distance.

[0066] S43, calculating a condition state value of the target boiler unit at the current time according to the load condition distance and the gas concentration condition distance.

[0067] Specifically, a superposition value is obtained by superimposing the load condition distance and the gas concentration condition distance, and the superposition value is multiplied by 100 to obtain the condition state value of the target boiler unit at the current time.

[0068] S5, correcting the fuzzy control ammonia injection amount according to the condition state value at the current time to obtain an actual control ammonia injection amount, and applying the actual control ammonia injection amount to the SCR flue gas denitration system.

[0069] Specifically, the condition state value at the current time is superimposed on the fuzzy control ammonia injection amount to obtain the actual control ammonia injection amount.

[0070] In one specific embodiment, the S5 comprises: S51, obtaining a condition state value of each time node in a preset time interval with the current time as the terminal point.

[0071] Specifically, the preset time interval is generally 30 min. The adjacent time nodes are generally spaced 1 s apart. The preset time interval generally has 1800 time nodes.

[0072] S52, calculating a condition gain degree at the current time according to the condition state values of all the time nodes.

[0073] Specifically, the condition gain degree refers to a change degree of the condition at the current time.

[0074] In one specific embodiment, the S52 comprises: S521, fitting the condition state values of all the time nodes to obtain a condition change curve.

[0075] Specifically, the condition state values of all the time nodes are input into a preset polynomial function, and then the best parameters of the preset polynomial function are calculated by the least square method, and the best parameters are configured to the preset polynomial function to obtain the condition change curve. The preset polynomial generally adopts a cubic polynomial.

[0076] S522, calculating a gradient of the condition change curve at the current time according to the condition change curve, and taking the gradient of the condition change curve at the current time as the condition gain degree at the current time.

[0077] Specifically, the first derivative of the working condition change curve with respect to time is calculated to obtain the gradient of the working condition change curve at the current time.

[0078] S53, superimpose the working condition gain degree of the current time on the fuzzy control ammonia injection amount to obtain the actual control ammonia injection amount, and apply the actual control ammonia injection amount to the SCR flue gas denitrification system.

[0079] Specifically, the actual control ammonia injection amount is used as the ammonia injection amount control amount of the SCR flue gas denitrification system, and ammonia is injected into the reactor through the SCR flue gas denitrification system.

[0080] Based on all the above embodiments, the ammonia injection amount control method for the SCR flue gas denitrification system of a steel plant provided by the embodiments has the following beneficial effects: By obtaining the multiple working condition load data, reactor inlet gas concentration data, and reactor outlet gas concentration data of the target boiler unit at the current time, and calculating the simulated ammonia injection amount of the SCR flue gas denitrification system at the current time, a basic value for controlling the ammonia injection amount of the SCR flue gas denitrification system at the current time is provided. The simulated ammonia injection amount is determined based on the multiple working condition load data and the inlet and outlet gas concentration data of the reactor, and is related to the current operating state of the SCR flue gas denitrification system, so that the determined simulated ammonia injection amount can adapt to the working condition state parameter disturbance in combination with the real-time operating condition.

[0081] By fuzzy controlling the ammonia injection amount of the target boiler unit according to the reactor outlet gas concentration data and the simulated ammonia injection amount, the fuzzy control ammonia injection amount of the SCR flue gas denitrification system at the current time is obtained. The fuzzy control theory is applied to the SCR flue gas denitrification system, and the fuzzy control can better handle the nonlinear change relationship between the ammonia injection amount and the reactor outlet gas concentration data, so that the fuzzy control ammonia injection amount can provide an accurate control basis for subsequent ammonia injection amount adjustment.

[0082] By obtaining the working condition state value of the target boiler unit at the current time according to the multiple working condition load data and the reactor outlet gas concentration data, and correcting the fuzzy control ammonia injection amount to obtain the actual control ammonia injection amount, the fuzzy control ammonia injection amount is corrected in combination with the working condition state value at the current time, so as to ensure that more accurate, stable and efficient ammonia injection amount can be provided, and the denitrification efficiency is maximized, energy consumption is reduced, and environmental pollution is reduced.

[0083] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. It should be noted that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should also be considered as within the scope of protection of the present application.

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; 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 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.

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 2, characterized in that, S2 includes: 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): （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 that NO in the reactor inlet gas concentration data x The original gas concentration.

4. 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.

5. The method for controlling ammonia injection quantity in an SCR flue gas denitrification system of a steel plant according to claim 4, 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.

6. 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.

7. The method for controlling ammonia injection quantity in an SCR flue gas denitrification system of a steel plant according to claim 6, 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.

8. 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, 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.

9. A method for controlling ammonia injection quantity in an SCR flue gas denitrification system of a steel plant according to claim 8, 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.

Images