Circulating fluidized bed boiler denitration control method and device

Abstract

The invention provides a denitration control method and device for a circulating fluidized bed boiler, and relates to the technical field of denitration control, and the method comprises the steps: taking a first deviation value between an original flue gas NOx concentration measurement value and a corresponding set value as the input of a PID controller, and generating a first sub-control signal; determining a second sub-control signal according to a matching result of the first deviation value and a deviation threshold value; a third sub-control signal is generated according to the matching result of the original flue gas NOx concentration measurement value and the corresponding set value; generating a fourth sub-control signal based on a matching result of a urea dilution solution concentration measurement value and a corresponding set value; an original flue gas NOx concentration prediction value is determined, and a fifth sub-control signal is generated based on a matching result of the original flue gas NOx concentration prediction value and a corresponding set value; and performing summation and amplitude limiting processing on the sub-control signals to obtain a urea solution frequency control signal. The control effect of the NOx concentration of the raw flue gas of the circulating fluidized bed boiler can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of denitrification control, and particularly to a denitrification control method for a circulating fluidized bed boiler and a denitrification control device for a circulating fluidized bed boiler. Background Art

[0002] Circulating fluidized bed (CFB) combustion is an efficient and low-pollution clean coal technology developed from bubbling bed combustion technology. At present, the installed capacity of CFB boiler units in China is nearly 100 million kilowatts, playing an important role in the clean and efficient utilization of coal resources and the consumption of new energy. The combustion temperature of CFB units is low, usually not exceeding 950 °C. At the same time, there are a large number of reducing materials in the furnace, having the advantage of original low NO x emissions. After adopting combustion adjustment and selective non-catalytic reduction (SNCR) denitrification, ultra-low emissions of NO x can be achieved (NO x emission concentration ≤ 50 mg / m 3 ). Among them, in the SNCR denitrification process, a 20% concentration urea solution is diluted to form a 10%-20% concentration urea dilution solution and sprayed into the furnace for selective reaction with NO x . Its spray guns are installed on the top surface and side walls of the inlet flue of the high-temperature cyclone separator at the furnace outlet of the CFB boiler.

[0003] Currently, the SNCR denitrification control of CFB units usually adopts manual control or feedback control methods. However, with the large-scale grid connection of new energy power generation, CFB units need to operate with frequent load changes. During peak load regulation with load changes, the combustion atmosphere in the furnace changes greatly, the furnace temperature distribution is uneven, the generation and reduction characteristics of NO x change, the SNCR inlet NO x concentration and denitrification efficiency fluctuate frequently. It is difficult for operators to perform manual control based on experience and the operation amount is extremely large. The feedback control only adjusts the flow rate of the urea solution according to the NO x concentration deviation. However, due to the large delay in NO x concentration measurement, phenomena such as untimely adjustment are likely to occur. Eventually, the instantaneous value of the NO x emission concentration of the actual operating CFB unit exceeds the standard frequently or the ammonia escape is serious, unable to meet the ultra-low emission standard, affecting the load change performance of the unit. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a denitrification control method for a circulating fluidized bed boiler and a denitrification control device for a circulating fluidized bed boiler to solve the above problems.

[0005] To achieve the above object, a first aspect of the present application provides a denitration control method for a circulating fluidized bed boiler, including:

[0006] Obtaining the measured value of the NO in the raw flue gas of the circulating fluidized bed boiler and the measured value of the concentration of the urea dilution solution after diluting the urea solution; x Concentration measurement value and the concentration measurement value of the urea dilution solution after diluting the urea solution;

[0007] Determining a first deviation value between the measured value of the NO in the raw flue gas and a preset set value of the NO in the raw flue gas, using the first deviation value as the input of a PID controller, and adjusting the first deviation value through the PID controller to generate a first sub-control signal; x Concentration measurement value and the preset set value of the NO in the raw flue gas x Concentration set value, using the first deviation value as the input of a PID controller, and adjusting the first deviation value through the PID controller to generate a first sub-control signal;

[0008] Determining an initial second sub-control signal according to the matching result between the first deviation value and a preset deviation threshold, and performing amplitude limiting processing on the initial second sub-control signal through a first amplitude limiting model to obtain a second sub-control signal;

[0009] Generating a third sub-control signal according to the matching result between the measured value of the NO in the raw flue gas and the set value of the NO in the raw flue gas; x Concentration measurement value and the NO in the raw flue gas x Concentration set value;

[0010] Obtaining the target load of the circulating fluidized bed boiler, determining the set value of the concentration of the urea dilution solution according to the matching result between the target load and a preset rated load, and generating a fourth sub-control signal based on the matching result between the measured value of the concentration of the urea dilution solution and the set value of the concentration of the urea dilution solution;

[0011] Obtaining the operating parameters of the circulating fluidized bed boiler, using the operating parameters as the input, and outputting the predicted value of the NO concentration in the raw flue gas of the circulating fluidized bed boiler through a pre-constructed NO concentration prediction model in the raw flue gas, and generating a fifth sub-control signal based on the matching result between the predicted value of the NO concentration in the raw flue gas and the set value of the NO concentration in the raw flue gas; x Concentration prediction model to output the predicted value of the NO concentration in the raw flue gas of the circulating fluidized bed boiler x Based on the predicted value of the NO concentration in the raw flue gas x Concentration prediction value and the NO in the raw flue gas x Concentration set value;

[0012] Summing and performing amplitude limiting processing on the first sub-control signal, the second sub-control signal, the third sub-control signal, the fourth sub-control signal and the fifth sub-control signal to obtain a urea solution frequency control signal, and controlling the operating frequency of the urea solution delivery pump with the urea solution frequency control signal.

[0013] Optionally, determining the initial second sub-control signal according to the matching result between the first deviation value and a preset deviation threshold includes:

[0014] Taking the matching result of the first deviation value and a preset deviation threshold as an input, an initial second sub-control signal is determined through a first selection model, and the first selection model includes:

[0015]

[0016] where e(t) represents the first deviation value, and f 21 (x) represents the initial second sub-control signal.

[0017] Optionally, the initial second sub-control signal is subjected to a clipping process through a first clipping model to obtain a second sub-control signal, including:

[0018] Determine a first proportionality coefficient, and use the product of the first proportionality coefficient and the initial second sub-control signal as the input of the first clipping model, and output the second sub-control signal through the first clipping model;

[0019] The first clipping model includes:

[0020]

[0021] where f 22 (x) represents the second sub-control signal, x represents the signal corresponding to the product of the first proportionality coefficient and the initial second sub-control signal, and y represents the operating frequency adjustment range of the urea solution delivery pump.

[0022] Optionally, a third sub-control signal is generated based on the matching result of the measured value of the NO in the raw flue gas x and the set value of the NO in the raw flue gas x , including:

[0023] Taking the measured value of the NO in the raw flue gas x and the set value of the NO in the raw flue gas x as inputs, output an initial third sub-control signal through a preset dead zone model;

[0024] Determine the operating frequency adjustment range of the urea solution delivery pump, use the operating frequency adjustment range of the urea solution delivery pump as a second proportionality coefficient, and use the product of the second proportionality coefficient and the third sub-control signal as the third sub-control signal;

[0025] where the second proportionality coefficient is the operating frequency adjustment range of the urea solution delivery pump, and the dead zone model includes:

[0026]

[0027] where x represents the measured value of the NO in the raw flue gas x and Indicates the original flue gas NO x concentration set value.

[0028] Optionally, determining the urea dilution solution concentration set value according to the matching result between the target load and the preset rated load includes:

[0029] Taking the target load and the rated load as inputs, and outputting the urea dilution solution concentration set value through a preset urea dilution solution concentration set value model;

[0030] Among them, the urea dilution solution concentration set value model includes:

[0031]

[0032] Among them, x 0 is the ratio of the target load to the rated load, and f(x 0 ) represents the urea dilution solution concentration set value, %.

[0033] Generating a fourth sub-control signal based on the matching result between the urea dilution solution concentration measurement value and the urea dilution solution concentration set value includes:

[0034] Taking the urea dilution solution concentration measurement value and the urea dilution solution concentration set value as inputs, and outputting an initial fourth sub-control signal through a preset second selection model;

[0035] Determining a third proportionality coefficient, and taking the product of the third proportionality coefficient and the initial fourth sub-control signal as the fourth sub-control signal;

[0036] The second selection model includes:

[0037]

[0038] Among them, x represents the urea dilution solution concentration measurement value, represents the original flue gas NO x concentration measurement value, represents the original flue gas NO x concentration set value;

[0039] Determining the third proportionality coefficient includes:

[0040] Determining the operating frequency adjustment range of the urea solution delivery pump, and taking the product of a first preset ratio and the operating frequency adjustment range of the urea solution delivery pump as the third proportionality coefficient.

[0041] Optionally, the operating parameters of the circulating fluidized bed boiler include:

[0042] The current load, coal feeding amount, total air volume, bed temperature, furnace outlet temperature of the circulating fluidized bed boiler, and the operating frequency of the urea solution delivery pump;

[0043] The raw flue gas NO x concentration prediction model, including:

[0044] C NO,p = k NO,f C NO,f M NO

[0045] Wherein, C NO,p represents the predicted value of the raw flue gas NO x concentration of the circulating fluidized bed boiler, C NO,f represents the average molar concentration of NO in the SNCR system x M NO represents the molar mass of nitric oxide, k NO,f is the concentration proportionality coefficient;

[0046] The average molar concentration of NO in the SNCR system x is calculated by the following formula:

[0047]

[0048] Wherein, V 2 is the volume of the cyclone separator for spraying urea dilution solution, k s is the conversion coefficient of the NH 3 oxidation reaction, k SNCR is the SNCR denitration reaction rate constant, T f is the furnace outlet temperature of the circulating fluidized bed boiler, u Air is the total air volume, is the average concentration of NH 3 at the cyclone separator, C NO represents the average concentration of NO x in the furnace of the circulating fluidized bed boiler;

[0049] Wherein, the concentration proportionality coefficient is determined by a preset concentration proportionality coefficient curve, and the concentration proportionality coefficient curve at least includes the concentration proportionality coefficients corresponding to different loads of the circulating fluidized bed boiler.

[0050] Optionally, the average concentration of NH 3 at the cyclone separator is calculated by the following formula:

[0051]

[0052] Wherein, k NH3is the ammonia slip correction factor for the circulating fluidized bed boiler, is the molar rate of generating NH 3 from the urea dilution solution, wherein, is the density of the 20% concentration urea solution, is the molar mass of urea, Q CO(NH2)2 is the flow rate of the 20% concentration urea solution, wherein, u Hz is the operating frequency of the urea solution delivery pump;

[0053] The average concentration of NO in the furnace of the circulating fluidized bed boiler is calculated by the following formula: x

[0054]

[0055] wherein, k NO represents the reaction rate constant of NO and CO, G NO represents the generation rate of NO in the furnace of the circulating fluidized bed boiler, R x NO represents the reduction rate of NO in the furnace of the circulating fluidized bed boiler, C x CO represents the average concentration of CO in the furnace, d c is the fuel particle size, ρ c is the fuel density, m B CO is the in-furnace residual carbon content of the circulating fluidized bed boiler;

[0056]

[0057] wherein, C CO is calculated by the following formula:

[0057]

[0058] wherein, is the mechanical factor of carbon combustion, represents the reaction rate of CO oxidized to CO 2 is the CO oxidation rate constant, is the average oxygen concentration in the furnace of the circulating fluidized bed boiler, R c is the residual carbon combustion rate in the furnace of the circulating fluidized bed boiler.

[0059] Optionally, the calculation formula of is:

[0060]

[0061] R c The calculation formula of is:

[0062]

[0063] Among them, M c , k c are respectively the molar mass of carbon and the combustion rate constant, where k c = 0.513T b exp(-9160 / T b ), T b is the bed temperature of the circulating fluidized bed boiler, R loss is the carbon mass flow rate in fly ash and bottom slag, V 1 is the furnace volume of the circulating fluidized bed boiler, k q is the conversion coefficient of air volume and molar amount. Among them, the carbon mass flow rate in fly ash and bottom slag is determined by a preset carbon mass flow rate curve, and the carbon mass flow rate curve at least includes the carbon mass flow rate in fly ash and bottom slag corresponding to different loads of the circulating fluidized bed boiler;

[0064] G NO The calculation formula of is:

[0065] G NO = 1000η N [u c V ar N ar + R c (1 - V ar )N ar / X c / M NO

[0066] Among them, η N is the fuel nitrogen conversion rate, u c is the coal feeding amount, V ar is the mass fraction of volatile matter, N ar is the mass fraction of nitrogen element, X c is the mass fraction of fixed carbon on the as-received basis.

[0067] Optionally, a fifth sub-control signal is generated based on the matching result between the predicted value of the raw flue gas NO x concentration and the set value of the raw flue gas NO x concentration, including:

[0068] Taking the predicted value of the raw flue gas NO x concentration and the set value of the raw flue gas NO x concentration as inputs, and outputting an initial fifth sub-control signal through a preset third selection model;

[0069] Determine the fourth proportionality coefficient, and use the product of the fourth proportionality coefficient and the initial fifth sub-control signal as the fifth sub-control signal;

[0070] The third selection model includes:

[0071]

[0072] Among them, C NO,p represents the predicted value of the NO in the raw flue gas of the circulating fluidized bed boiler x concentration, represents the set value of the NO x concentration in the raw flue gas;

[0073] Determining the fourth proportionality coefficient includes:

[0074] Determine the operating frequency adjustment range of the urea solution delivery pump, and use the product of the second preset ratio and the operating frequency adjustment range of the urea solution delivery pump as the fourth proportionality coefficient.

[0075] In the second aspect of the present application, a denitration control device for a circulating fluidized bed boiler is provided, including:

[0076] A data acquisition module configured to acquire the measured value of the NO concentration in the raw flue gas of the circulating fluidized bed boiler and the measured value of the concentration of the urea dilution solution after diluting the urea solution; x Concentration measurement value and the measured value of the concentration of the urea dilution solution after diluting the urea solution;

[0077] A first sub-control signal generation module configured to determine a first deviation value between the measured value of the NO concentration in the raw flue gas and a preset set value of the NO concentration in the raw flue gas, use the first deviation value as the input of a PID controller, and adjust the first deviation value through the PID controller to generate a first sub-control signal; x Concentration measurement value and the preset set value of the NO concentration in the raw flue gas, x Concentration set value, use the first deviation value as the input of the PID controller, and adjust the first deviation value through the PID controller to generate a first sub-control signal;

[0078] A second sub-control signal generation module configured to determine an initial second sub-control signal based on the matching result between the first deviation value and a preset deviation threshold, and perform a limiting process on the initial second sub-control signal through a first limiting model to obtain a second sub-control signal;

[0079] A third sub-control signal generation module configured to generate a third sub-control signal based on the matching result between the measured value of the NO concentration in the raw flue gas and the set value of the NO concentration in the raw flue gas; x Concentration measurement value and the NO x Concentration set value of the raw flue gas to generate a third sub-control signal;

[0080] The fourth sub-control signal generation module is configured to obtain the target load of the circulating fluidized bed boiler, determine the set value of the urea dilution solution concentration according to the matching result between the target load and the preset rated load, and generate a fourth sub-control signal based on the matching result between the measured value of the urea dilution solution concentration and the set value of the urea dilution solution concentration;

[0081] The fifth sub-control signal generation module is configured to obtain the operating parameters of the circulating fluidized bed boiler, take the operating parameters as inputs, and output the predicted value of the NO concentration in the raw flue gas of the circulating fluidized bed boiler through a pre-constructed prediction model of the NO concentration in the raw flue gas, and generate a fifth sub-control signal based on the matching result between the predicted value of the NO concentration in the raw flue gas and the set value of the NO concentration in the raw flue gas; x concentration prediction value of the circulating fluidized bed boiler, and generate a fifth sub-control signal based on the matching result between the predicted value of the NO concentration in the raw flue gas and the set value of the NO concentration in the raw flue gas; x Based on the predicted value of the NO concentration in the raw flue gas x and the matching result between the predicted value of the NO concentration in the raw flue gas x and the set value of the NO concentration in the raw flue gas;

[0082] The urea solution frequency control module is configured to sum and limit the first sub-control signal, the second sub-control signal, the third sub-control signal, the fourth sub-control signal and the fifth sub-control signal to obtain a urea solution frequency control signal, and control the operating frequency of the urea solution delivery pump with the urea solution frequency control signal.

[0083] In the third aspect of the present application, a computer-readable storage medium is provided, storing a computer program which, when executed by a processor, causes the processor to execute the denitration control method of the circulating fluidized bed boiler as described above.

[0084] In the fourth aspect of the present application, a terminal device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, the denitration control method of the circulating fluidized bed boiler as described above is implemented.

[0085] The embodiments provided in the present application have the following beneficial effects:

[0086] In the present application, a control feedforward signal is constructed with the predicted signal of the NO concentration in the raw flue gas of the CFB unit and its differential signal, etc., to control the frequency of the urea solution delivery pump in advance, and timely adjust the urea solution flow rate at the current moment, which is beneficial to overcoming the problems of unknown NO concentration fluctuation at the inlet of the SNCR system of the CFB unit and large delay in the measurement of the NO concentration in the raw flue gas; at the same time, the present application can realize the automatic control of the SNCR denitration system during the rapid load change process of the CFB unit, can significantly improve the control effect of the NO concentration in the raw flue gas, ensure that the NO emission concentration does not exceed the standard, reduce the amount of manual operation, reduce the consumption of urea, and prevent the occurrence of serious ammonia slip phenomenon. x concentration prediction signal and its differential signal, etc., to control the frequency of the urea solution delivery pump in advance, and timely adjust the urea solution flow rate at the current moment, which is beneficial to overcoming the problems of unknown NO concentration fluctuation at the inlet of the SNCR system of the CFB unit and large delay in the measurement of the NO concentration in the raw flue gas; at the same time, the present application can realize the automatic control of the SNCR denitration system during the rapid load change process of the CFB unit, can significantly improve the control effect of the NO concentration in the raw flue gas, ensure that the NO emission concentration does not exceed the standard, reduce the amount of manual operation, reduce the consumption of urea, and prevent the occurrence of serious ammonia slip phenomenon. x concentration fluctuation, unknown NO concentration in the raw flue gas x concentration measurement large delay problem; at the same time, the present application can realize the automatic control of the SNCR denitration system during the rapid load change process of the CFB unit, can significantly improve the control effect of the NO concentration in the raw flue gas, ensure that the NO emission concentration does not exceed the standard, reduce the amount of manual operation, reduce the consumption of urea, and prevent the occurrence of serious ammonia slip phenomenon. x concentration control effect, ensure that the NO x emission concentration does not exceed the standard, reduce the amount of manual operation, reduce the consumption of urea, and prevent the occurrence of serious ammonia slip phenomenon.

[0087] Other features and advantages of the embodiments or implementations of the present application will be described in detail in the subsequent specific implementation section. Description of the Drawings

[0088] The drawings are used to provide a further understanding of the embodiments of the present application, and constitute a part of the specification. Together with the following specific implementation, they are used to explain the embodiments of the present application, but do not constitute a limitation to the embodiments of the present application. In the drawings:

[0089] Figure 1 Schematically shows the method flow chart of the denitration control method of the circulating fluidized bed boiler according to the implementation manner of the present application;

[0090] Figure 2 Schematically shows the schematic diagram of the control logic according to the implementation manner of the present application;

[0091] Figure 3 Schematically shows the schematic block diagram of the denitration control device of the circulating fluidized bed boiler according to the implementation manner of the present application;

[0092] Figure 4 Schematically shows the schematic diagram of the structure of a terminal device according to the implementation manner of the present application.

[0093] Description of the Reference Numerals

[0094] 10 - Terminal device, 100 - Processor, 101 - Memory, 102 - Computer program. Specific Implementation

[0095] The following will describe in detail the specific implementation of the embodiments of the present application with reference to the drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiments of the present application, and does not limit the embodiments of the present application.

[0096] As Figure 1 shown, the first aspect of the present application provides a denitration control method for a circulating fluidized bed boiler, including:

[0097] S100. Obtain the measured value of the original flue gas NO x concentration of the circulating fluidized bed boiler and the measured value of the urea dilution solution concentration after diluting the urea solution;

[0098] S200. Determine the first deviation value between the measured value of the original flue gas NO x concentration and the preset set value of the original flue gas NO x concentration. Take the first deviation value as the input of the PID controller, and adjust the first deviation value through the PID controller to generate a first sub-control signal;

[0099] S300. Determine an initial second sub-control signal based on the matching result between the first deviation value and a preset deviation threshold, and perform a limiting process on the initial second sub-control signal through a first limiting model to obtain the second sub-control signal;

[0100] S400. Generate a third sub-control signal based on the matching result between the measured value of the NO concentration in the raw flue gas and the set value of the NO concentration in the raw flue gas; x concentration measurement value and the NO x concentration set value in the raw flue gas;

[0101] S500. Obtain the target load of the circulating fluidized bed boiler, determine the set value of the urea dilution solution concentration based on the matching result between the target load and a preset rated load, and generate a fourth sub-control signal based on the matching result between the measured value of the urea dilution solution concentration and the set value of the urea dilution solution concentration;

[0102] S600. Obtain the operating parameters of the circulating fluidized bed boiler, use the operating parameters as inputs, and output the predicted value of the NO concentration in the raw flue gas of the circulating fluidized bed boiler through a pre-constructed prediction model of the NO concentration in the raw flue gas. Based on the matching result between the predicted value of the NO concentration in the raw flue gas and the set value of the NO concentration in the raw flue gas, generate a fifth sub-control signal; x concentration prediction model, and output the predicted value of the NO concentration in the raw flue gas of the circulating fluidized bed boiler. Based on the matching result between the predicted value of the NO concentration in the raw flue gas and the set value of the NO concentration in the raw flue gas, generate a fifth sub-control signal; x Based on the predicted value of the NO concentration in the raw flue gas x and the matching result between the predicted value of the NO concentration in the raw flue gas and the set value of the NO concentration in the raw flue gas x generate a fifth sub-control signal;

[0103] S700. Sum and perform a limiting process on the first sub-control signal, the second sub-control signal, the third sub-control signal, the fourth sub-control signal, and the fifth sub-control signal to obtain a urea solution frequency control signal, and use the urea solution frequency control signal to control the operating frequency of the urea solution delivery pump.

[0104] In this way, this application constructs a control feedforward signal with the predicted signal of the NO concentration in the raw flue gas of the CFB unit and its differential signal, etc., to control the frequency of the urea solution delivery pump in advance, and timely adjust the urea solution flow at the current moment, which is beneficial to overcoming the problems of unknown NO concentration fluctuations at the inlet of the SNCR system of the CFB unit and large delay in the measurement of the NO concentration in the raw flue gas. At the same time, this application can realize the automatic control of the SNCR denitration system during the rapid load change process of the CFB unit, can significantly improve the control effect of the NO concentration in the raw flue gas, ensure that the NO x emission concentration does not exceed the standard, reduce the amount of manual operation, reduce the consumption of urea, and prevent serious ammonia escape. x concentration fluctuations are unknown, and the large delay in the measurement of the NO concentration in the raw flue gas; at the same time, this application can realize the automatic control of the SNCR denitration system during the rapid load change process of the CFB unit, can significantly improve the control effect of the NO concentration in the raw flue gas, ensure that the NO x concentration in the raw flue gas, ensure that the NO x concentration control effect, ensure that the NO x emission concentration does not exceed the standard, reduce the amount of manual operation, reduce the consumption of urea, and prevent serious ammonia escape.

[0105] It can be understood that the existing denitration systems of circulating fluidized bed power plants usually use selective non-catalytic reduction (SNCR) to remove NO xTechnology, which sprays the diluted urea solution into the upper part of the furnace on the boiler side, the separator, and the corresponding areas of the flue gas duct, and reacts with NO in the flue gas x to produce a reduction reaction to generate N 2 and H 2 O, thereby achieving the purpose of denitrification. The specific process flow is as follows: Prepare urea solution in the urea solution preparation tank. For example, prepare a 20% concentration urea solution, which is discharged into the urea solution storage tank by the urea solution transfer pump, and is diluted to 10%-20% by the urea solution dilution system, and is sprayed into the corresponding area of the boiler by the spray gun installed at the inlet flue of the high-temperature cyclone separator at the furnace outlet of the CFB boiler to remove NO x .

[0106] In step S100, the measured value of the original flue gas NO x concentration and the measured value of the urea dilution solution concentration of the circulating fluidized bed boiler can be directly collected through an existing data acquisition system, such as the DCS system of the circulating fluidized bed boiler, or can be collected by adding additional sensors, and this is not limited here.

[0107] As Figure 2 shown, in step S200, according to the measured value of the original flue gas NO x concentration and the set value of the original flue gas NO x concentration during the rapid load change of the CFB unit, a deviation value e(t) is calculated, that is, the first deviation value, and the deviation value is input into the PID controller to adjust the deviation, and the output of the PID controller is the first sub-control signal a 1 . It can be understood that when calculating, the measured value of the original flue gas NO x concentration needs to be converted to the NO x concentration under the condition of the reference oxygen content of 6%. Among them, the conversion of the original flue gas NO x concentration is an existing technology, and this is not limited here; at the same time, the set value of the original flue gas NO x concentration can be preset by the operator in combination with the required emission index and the average hourly NO x emission value at the current moment, and is pre-input into the distributed control system (DCS) of the CFB boiler for calling during calculation. It can be understood that the PID controller (proportional-integral-derivative controller) is a common feedback loop component in industrial control applications, which is composed of a proportional unit P, an integral unit I, and a differential unit D. In this application, the PID controller adopts the proportional unit P and the integral unit I, and does not adopt the differential unit D. The P and I parameters are determined by the engineering tuning method. To prevent the integral link from being oversaturated, when the calculated absolute value of the deviation |e(t)| is greater than the original flue gas NO xWhen it is 1 / 2 of the concentration set value, the feedback value of the PID controller tracks the set value. Among them, the calculation process of the PID controller is the prior art, and no limitation is made here.

[0108] When the absolute value of the deviation |e(t)| is large, it is necessary to quickly adjust the frequency of the urea solution delivery pump. When the absolute value of the deviation |e(t)| is small, in order to avoid frequent adjustment of the delivery pump frequency, a dead zone needs to be set. Therefore, in step S200, determining the initial second sub-control signal according to the matching result between the first deviation value and the preset deviation threshold includes: using the matching result between the first deviation value and the preset deviation threshold as the input, and determining the initial second sub-control signal through the first selection model. The first selection model includes:

[0109]

[0110] Among them, e(t) represents the first deviation value, and f 21 (x) represents the initial second sub-control signal. It can be understood that the first selection model can be deployed in a pre-constructed selection module. When performing calculations, the first selection model can be called through the selection module to calculate the second sub-control signal a 2 for calculation.

[0111] In this application, the initial second sub-control signal is limited through the first limiting model to obtain the second sub-control signal, including: determining the first proportional coefficient, using the product of the first proportional coefficient and the initial second sub-control signal as the input of the first limiting model, and outputting the second sub-control signal through the first limiting model;

[0112] The first limiting model includes:

[0113]

[0114] Among them, f 22 (x) represents the second sub-control signal, x represents the signal corresponding to the product of the first proportional coefficient and the initial second sub-control signal, and y represents the operating frequency adjustment range of the urea solution delivery pump. Among them, the operating frequency adjustment range of the urea solution delivery pump is the adjustable range of the urea solution delivery pump frequency.

[0115] Among them, the first proportional coefficient k 2 is the ratio of the order of magnitude of the urea solution delivery pump frequency to the rate of change of the absolute value of the first deviation |e(t)|. Among them, engineering tuning can be performed according to the priority of the differential signal of the deviation value e(t). In this application, the proportional coefficient k 2 can be set to 0.0005, and the amplitude of the limiting function f 22 (x) can be set to 1 / 5 of the adjustable range of the urea solution delivery pump frequency. The adjustable range of the delivery pump frequency can be determined in advance according to the delivery pump frequency-flow characteristic test.

[0116] When the measured value of the NO concentration in the raw flue gas is much lower or much higher than the set value of the NO concentration in the raw flue gas, the frequency of the urea solution delivery pump should be adjusted to the minimum or maximum value. Therefore, the present application also sets a dead zone function f x (x). In step S300, according to the matching result between the measured value of the NO concentration in the raw flue gas and the set value of the NO concentration in the raw flue gas, a third sub-control signal a x is generated, including: taking the measured value of the NO concentration in the raw flue gas and the set value of the NO concentration in the raw flue gas as inputs, and outputting an initial third sub-control signal through a preset dead zone model; determining the operating frequency adjustment range of the urea solution delivery pump, taking the operating frequency adjustment range of the urea solution delivery pump as the second proportional coefficient, and taking the product of the second proportional coefficient and the third sub-control signal as the third sub-control signal; wherein, the second proportional coefficient is the operating frequency adjustment range of the urea solution delivery pump, that is, the second proportional coefficient k 3 (x), step S300, according to the measured value of the NO concentration in the raw flue gas and the NO in the raw flue gas x concentration measurement value and the NO in the raw flue gas x The matching result of the concentration set value generates a third sub-control signal a 3 , including: taking the measured value of the NO concentration in the raw flue gas and the NO in the raw flue gas x concentration measurement value and the NO in the raw flue gas x The concentration set value is input, and an initial third sub-control signal is output through a preset dead zone model; determining the operating frequency adjustment range of the urea solution delivery pump, taking the operating frequency adjustment range of the urea solution delivery pump as the second proportional coefficient, and taking the product of the second proportional coefficient and the third sub-control signal as the third sub-control signal; wherein, the second proportional coefficient is the operating frequency adjustment range of the urea solution delivery pump, that is, the second proportional coefficient k 3 is the adjustable range of the urea solution delivery pump frequency, that is, k 3 =y. The dead zone model of the present application includes:

[0117]

[0118] wherein, x represents the measured value of the NO concentration in the raw flue gas x represents the set value of the NO concentration in the raw flue gas x .

[0119] In step S500, the target load of the circulating fluidized bed boiler can be determined by the load command of the unit. According to the matching result between the target load and the preset rated load, the set value of the urea dilution solution concentration is determined, including: taking the target load and the rated load as inputs, and outputting the set value of the urea dilution solution concentration through a preset urea dilution solution concentration set value model; wherein, the urea dilution solution concentration set value model includes:

[0120]

[0121] wherein, x 0 is the ratio of the target load to the rated load, that is, the unit load command N e,sp and the rated load N e0 ratio, f(x 0 ) represents the set value of the urea dilution solution concentration, %.

[0122] ​Generate a fourth sub-control signal based on the matching result between the measured value and the set value of the urea dilution solution concentration, including: taking the measured value and the set value of the urea dilution solution concentration as inputs, and outputting an initial fourth sub-control signal through a preset second selection model, where the second selection model can be deployed in a selection module; determining a third proportionality coefficient, and using the product of the third proportionality coefficient and the initial fourth sub-control signal as the fourth sub-control signal;

[0123] When the measured value of the NO in the raw flue gas x is less than the set value and the measured value of the urea dilution solution concentration is greater than the set value, to prevent the NO x emission concentration from being too low or the ammonia slip from being serious, it is necessary to reduce the frequency of the urea delivery pump. Therefore, this application is also configured with a second selection model. The set value of the urea dilution solution concentration is automatically generated through the second selection model according to the CFB unit load command. The second selection model includes:

[0124]

[0125] where x represents the measured value of the urea dilution solution concentration, represents the measured value of the NO in the raw flue gas x concentration, represents the set value of the NO in the raw flue gas x concentration;

[0126] Determining the third proportionality coefficient includes: determining the operating frequency adjustment range of the urea solution delivery pump, and using the product of the first preset ratio and the operating frequency adjustment range of the urea solution delivery pump as the third proportionality coefficient. Among them, the third proportionality coefficient k 4 can be tuned according to the priority of this feedforward signal and can be set to 1 / 5 of the adjustable range of the urea solution delivery pump frequency, that is, k 4 = 1 / 5y. The deviation value calculated from the set value and the measured value of the urea dilution solution concentration in the CFB boiler SNCR system is output as 0 or -1 after passing through the selection module f 4 (x), and then multiplied by the proportionality coefficient k 4 to obtain the sub-control signal a 4 .

[0127] In step S600, the operating parameters of the circulating fluidized bed boiler include: the current load of the circulating fluidized bed boiler, the coal feeding amount, the total air volume, the bed temperature, the furnace outlet temperature, and the operating frequency of the urea solution delivery pump. In this application, the principle of constructing the NO x concentration prediction model in the raw flue gas is: taking the furnace of the circulating fluidized bed boiler as a whole, establishing a lumped parameter model of the NO x concentration in the furnace, where the predicted value of the NO x concentration in the raw flue gas and the NO in the SNCR systemx is proportional to the average concentration and can be calculated by establishing a lumped parameter model of NO concentration in the furnace and an average concentration model of the SNCR system. In this application, the original flue gas NO concentration prediction model includes: x concentration, and the average concentration model of the SNCR system NO x The average concentration of the original flue gas NO in this application can be calculated by establishing a lumped parameter model of NO concentration in the furnace and an average concentration model of the SNCR system. The original flue gas NO concentration prediction model in this application includes: x concentration prediction model, including:

[0128] C NO,p = k NO,f C NO,f M NO

[0129] Among them, C NO,p represents the predicted value of the original flue gas NO concentration of the circulating fluidized bed boiler, C x represents the average molar concentration of NO in the SNCR system, M NO,f represents the molar mass of nitric oxide, and k x is the concentration proportionality coefficient. NO represents the molar mass of nitric oxide, and k NO,f is the concentration proportionality coefficient.

[0130] NO at the furnace outlet of the CFB unit reacts with NH x generated by the urea dilution solution sprayed into the cyclone separator of the SNCR system. Part of the NO 3 is reduced. Then, the average molar concentration of NO in the SNCR system can be calculated by the following formula: x is reduced, then the average molar concentration of NO in the SNCR system can be calculated by the following formula: x The average molar concentration of NO in the SNCR system can be calculated by the following formula:

[0131]

[0132] Among them, V 2 is the volume of the cyclone separator, which is used to spray the urea dilution solution. k s is the conversion coefficient of the NH 3 oxidation reaction, which can be taken as 0.95. k SNCR is the SNCR denitration reaction rate constant. T f is the furnace outlet temperature of the circulating fluidized bed boiler, u Air is the total air volume. is the average concentration of NH 3 at the cyclone separator, and C NO represents the average concentration of NO in the furnace of the circulating fluidized bed boiler. Among them, the concentration proportionality coefficient k x is related to the measured value N NO,f of the unit load. It can be pre-determined through the operation data under various typical steady-state load conditions, and the coefficient and N e are fitted by using a piecewise function and the least squares method. eThe relational expression is that the concentration ratio coefficient can be determined by a preset concentration ratio coefficient curve, and the concentration ratio coefficient curve includes at least the concentration ratio coefficients corresponding to different loads of the circulating fluidized bed boiler.

[0133] Among them, the average concentration of NH at the cyclone separator 3 is calculated by the following formula:

[0134]

[0135] Among them, k NH3 is the ammonia slip correction coefficient of the circulating fluidized bed boiler, is the molar rate of generating NH from the urea dilution solution 3 , Among them, is the density of the 20% concentration urea solution, is the molar mass of urea, is the flow rate of the 20% concentration urea solution, Among them, u Hz is the operating frequency of the urea solution delivery pump.

[0136] According to the NO generation rate G x and the reduction rate R NO in the furnace, the average concentration of NO in the furnace can be calculated. The average concentration of NO in the furnace of the circulating fluidized bed boiler can be calculated by the following formula: NO x x NO NO x

[0137]

[0138]

[0139] Among them, k NO represents the reaction rate constant of NO and CO, G NO represents the NO generation rate in the furnace of the circulating fluidized bed boiler x , R NO represents the NO reduction rate in the furnace of the circulating fluidized bed boiler x , C CO represents the average concentration of CO in the furnace, d c is the fuel particle size, ρ c is the fuel density, m B is the in-furnace residual carbon content of the circulating fluidized bed boiler. Among them, the fuel particle size and fuel density can be determined in advance.

[0140] Among them, the NO that can be reduced and generated by CO in the furnace x , the average concentration C of CO in the furnace CO is calculated by the following formula:

[0141]

[0142] Among them, is the mechanical factor of carbon combustion, T b is the bed temperature of the circulating fluidized bed boiler, represents the reaction rate of CO oxidation to CO 2 of. is the CO oxidation rate constant, is the average oxygen concentration in the furnace of the circulating fluidized bed boiler, R c is the residual carbon combustion rate in the furnace of the circulating fluidized bed boiler.

[0143] Among them, The calculation formula of is:

[0144]

[0145] R c The calculation formula of is:

[0146]

[0147] Among them, the amount of residual carbon in the furnace of the circulating fluidized bed boiler M c , k c are the molar mass of carbon and the combustion rate constant respectively, k c = 0.513T b exp(-9160 / T b ), T b is the bed temperature of the circulating fluidized bed boiler, R loss is the carbon mass flow rate in fly ash and bottom slag, V 1 is the furnace volume of the circulating fluidized bed boiler, k q is the conversion coefficient of air volume to molar amount. Among them, the carbon mass flow rate in fly ash and bottom slag can be obtained by fitting the linear relationship between load and R c using the least squares method based on the test data of carbon content in fly ash and bottom slag under steady-state load conditions, that is, the carbon mass flow rate in fly ash and bottom slag can be determined by a preset carbon mass flow rate curve, and the carbon mass flow rate curve includes at least the carbon mass flow rate in fly ash and bottom slag corresponding to different loads of the circulating fluidized bed boiler.

[0148] Among them, the generation rate G x of NO in the furnace of the CFB unit NO The calculation formula of can be expressed as:

[0149] G NO = 1000η N [uc V ar N ar +R c (1 - V ar )N ar / X c / M NO

[0150] Among them, η N is the fuel nitrogen conversion rate, u c is the coal feeding amount, V ar is the mass fraction of volatile matter, N ar is the mass fraction of nitrogen element, X c is the mass fraction of fixed carbon on as - received basis.

[0151] This application constructs a feed - forward control signal by using the original flue gas NO x concentration prediction model, which helps to adjust the frequency of the urea solution delivery pump in advance and improve the NO x emission control performance during the rapid load change of the CFB unit. However, to avoid frequent adjustment of the delivery pump frequency caused by this feed - forward control signal, this application adjusts the control signal by constructing a third selection model. Then, in step S600, based on the matching result between the predicted value of the original flue gas NO x concentration and the set value of the original flue gas NO x concentration, a fifth sub - control signal is generated, including: taking the predicted value of the original flue gas NO x concentration and the set value of the original flue gas NO x concentration as inputs, and outputting an initial fifth sub - control signal through a preset third selection model; determining a fourth proportionality coefficient, and taking the product of the fourth proportionality coefficient and the initial fifth sub - control signal as the fifth sub - control signal.

[0152] Among them, the third selection model can be deployed in the selection module. The third selection model includes:

[0153]

[0154] Among them, C NO,p represents the predicted value of the original flue gas NO x concentration of the circulating fluidized bed boiler, represents the set value of the original flue gas NO x concentration.

[0155] Determining the fourth proportionality coefficient includes: determining the operating frequency adjustment range of the urea solution delivery pump, and taking the product of the second preset ratio and the operating frequency adjustment range of the urea solution delivery pump as the fourth proportionality coefficient. Specifically, the fourth proportionality coefficient k 5Engineering tuning can be performed according to the priority of the feedforward signal constructed by the prediction model. To avoid the influence of the decrease in the accuracy of the prediction model on the stability of the control system, it can be set to 1 / 6 of the adjustable range of the frequency of the urea solution delivery pump.

[0156] This application constructs a CFB boiler raw flue gas NO x concentration prediction model using parameters such as coal feeding amount, total air volume, frequency of urea solution delivery pump, bed temperature, and furnace outlet temperature. The deviation between the predicted value and the set value of the raw flue gas NO x concentration passes through the selection model f 5 (x) and then outputs either zero or the differential signal of the predicted value, which is then multiplied by the proportionality coefficient k 5 to obtain the sub-control signal a 5 ; among them, the input of the CFB unit raw flue gas NO x concentration prediction model is the real-time measured values of the CFB unit load, coal feeding amount, total air volume, frequency of urea solution delivery pump, bed temperature, and furnace outlet temperature, and the output is the mass concentration of the raw flue gas NO x , which can achieve more than 180 s ahead of the measured value of the raw flue gas NO x concentration.

[0157] In step S700, the control sub-signals a 1 , a 2 , a 3 , a 4 , a 5 are summed up, and after passing through the limiter function f 6 (x), the control signal of the urea solution delivery pump frequency command is obtained. Among them, the control signal of the urea solution delivery pump frequency command should not exceed the adjustable range of the pump frequency. Therefore, the upper and lower limits of the limiter function f 6 (x) of this application can be determined as the adjustable range of the pump frequency.

[0158] Figure 2 As shown, this application can build the control logic based on the DCS control system of the CFB unit, calculate and generate the urea solution delivery pump frequency command and send it to the execution device; or, the control logic can also be built in the server of the external system. The measured values in the DCS control system are transmitted to the server of the external system, the urea solution delivery pump frequency command is calculated and generated, and then transmitted to the DCS control system through the communication cable. The DCS control system sends this command to the execution device, and no limitation is made here. The control principle of this application is as follows:

[0159] First, use the built-in function modules in the DCS system of the CFB unit to build the SNCR denitration control loop logic. The function modules in the DCS system to be applied include: trigger module, addition module, function module, multiplication module, differential module, integral module, selection module, amplitude limiting module, and PID controller module.

[0160] The input of the control loop is the original flue gas NO x concentration set value The original flue gas NO x concentration measured value C NOx,m , unit load command N e,sp , unit load measured value N e , unit rated load N e0 , coal feed rate measured value u c , total air volume measured value u Air , urea solution transfer pump frequency measured value u Hz , lower furnace bed temperature measured value T b , furnace outlet temperature measured value T f , and the output is the urea solution transfer pump frequency command; among them, the original flue gas NO x concentration set value is input into the DCS system by the operator according to the design capacity of the SNCR system of the CFB unit and the environmental protection requirement emission value. The unit rated load is input into the DCS system by the operator according to the CFB unit design parameters. The unit load command is automatically set by the DCS system according to the grid load command; the measured values are transmitted to the DCS system by the on-site instruments through the signal transmission network; the urea solution flow rate can be calculated and generated by the DCS system according to the urea solution transfer pump frequency measured value; the urea solution transfer pump frequency command is sent by the DCS system to the on-site actuator to change the transfer pump frequency.

[0161] According to the calculation principle of the lumped parameter prediction model of the original flue gas NO x concentration, build an original flue gas NO x concentration prediction module in the DCS system. The function modules of the DCS control system include addition module, function module, multiplication module, integral module, etc. The measured values of coal feed rate, total air volume, urea solution transfer pump frequency, bed temperature, and furnace outlet temperature are used to predict the original flue gas NO x concentration, so as to effectively overcome the on-site disturbance signals and improve the accuracy of model prediction.

[0162] At the same time, pre-tune the P and I parameters in the PID module in the DCS system, connect the signal lines of each module, and complete the commissioning test. According to the real-time measured value data of the CFB unit, the DCS system calculates the urea solution transfer pump frequency command in real time and sends it to the on-site actuator, so as to realize the automatic control optimization of the SNCR denitration system when the circulating fluidized bed unit quickly changes load.

[0163] As Figure 3 shown, in the second aspect of the present application, there is provided a denitration control device for a circulating fluidized bed boiler, including:

[0164] A data acquisition module configured to acquire the measured value of the NO concentration in the raw flue gas of the circulating fluidized bed boiler and the measured value of the concentration of the urea dilution solution after diluting the urea solution; x The measured value of the concentration of the urea dilution solution after diluting the urea solution;

[0165] A first sub-control signal generation module configured to determine a first deviation value between the measured value of the NO concentration in the raw flue gas and a preset NO concentration set value in the raw flue gas, use the first deviation value as the input of a PID controller, and adjust the first deviation value through the PID controller to generate a first sub-control signal; x The measured value of the NO concentration in the raw flue gas and a preset NO concentration set value in the raw flue gas; x The measured value of the NO concentration in the raw flue gas and a preset NO concentration set value in the raw flue gas;

[0166] A second sub-control signal generation module configured to determine an initial second sub-control signal according to the matching result between the first deviation value and a preset deviation threshold value, and perform a limiting process on the initial second sub-control signal through a first limiting model to obtain a second sub-control signal;

[0167] A third sub-control signal generation module configured to generate a third sub-control signal according to the matching result between the measured value of the NO concentration in the raw flue gas and the NO concentration set value in the raw flue gas; x The measured value of the NO concentration in the raw flue gas and the NO concentration set value in the raw flue gas; x The measured value of the NO concentration in the raw flue gas and the NO concentration set value in the raw flue gas;

[0168] A fourth sub-control signal generation module configured to obtain the target load of the circulating fluidized bed boiler, determine the urea dilution solution concentration set value according to the matching result between the target load and a preset rated load, and generate a fourth sub-control signal based on the matching result between the measured value of the urea dilution solution concentration and the urea dilution solution concentration set value;

[0169] A fifth sub-control signal generation module configured to obtain the operating parameters of the circulating fluidized bed boiler, use the operating parameters as the input, output the predicted value of the NO concentration in the raw flue gas of the circulating fluidized bed boiler through a pre-constructed NO concentration prediction model in the raw flue gas, and generate a fifth sub-control signal based on the matching result between the predicted value of the NO concentration in the raw flue gas and the NO concentration set value in the raw flue gas; x The predicted value of the NO concentration in the raw flue gas of the circulating fluidized bed boiler; x The predicted value of the NO concentration in the raw flue gas and the NO concentration set value in the raw flue gas; x The predicted value of the NO concentration in the raw flue gas and the NO concentration set value in the raw flue gas; x The predicted value of the NO concentration in the raw flue gas and the NO concentration set value in the raw flue gas;

[0170] A urea solution frequency control module configured to sum and limit the first sub-control signal, the second sub-control signal, the third sub-control signal, the fourth sub-control signal and the fifth sub-control signal to obtain a urea solution frequency control signal, and control the operating frequency of the urea solution delivery pump with the urea solution frequency control signal.

[0171] Those skilled in the art can clearly understand that, for the convenience and conciseness of description, only the above-mentioned division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules as needed, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of this application. The specific working processes of the units and modules in the above system can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0172] In the third aspect of this application, a computer-readable storage medium is provided, storing a computer program that, when executed by a processor, causes the processor to execute the circulating fluidized bed boiler denitration control method as described above.

[0173] In the fourth aspect of this application, a terminal device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the circulating fluidized bed boiler denitration control method as described above is implemented.

[0174] As Figure 4 shown is a schematic diagram of the terminal device provided by the embodiment of this application. As Figure 4 shown, the terminal device 10 of this embodiment includes: a processor 100, a memory 101, and a computer program 102 stored in the memory 101 and executable on the processor 100. When the processor 100 executes the computer program 102, the steps in the foregoing method embodiment are implemented. Alternatively, when the processor 100 executes the computer program 102, the functions of each module / unit in the foregoing device embodiments are implemented.

[0175] Exemplarily, the computer program 102 can be divided into one or more modules / units. One or more modules / units are stored in the memory 101 and executed by the processor 100 to complete this application. One or more modules / units can be a series of computer program instruction segments capable of completing specific functions, and the instruction segments are used to describe the execution process of the computer program 102 in the terminal device 10.

[0176] The terminal device 10 can be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The terminal device 10 may include, but is not limited to, a processor 100 and a memory 101. Those skilled in the art can understand thatFigure 4 These are merely examples of the terminal device 10 and do not constitute a limitation thereto. It may include more or fewer components than those shown in the figure, or combine certain components, or have different components. For example, the terminal device may also include input / output devices, network access devices, buses, etc.

[0177] The processor 100 may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0178] The memory 101 may be an internal storage unit of the terminal device 10, such as the hard disk or memory of the terminal device 10. The memory 101 may also be an external storage device of the terminal device 10, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc. equipped on the terminal device 10. Further, the memory 101 may also include both the internal storage unit and the external storage device of the terminal device 10. The memory 101 is used to store computer programs and other programs and data required by the terminal device 10. The memory 101 may also be used to temporarily store data that has been output or is to be output.

[0179] In summary, in this application, the deviation value between the measured value of the original flue gas NO x concentration of the CFB unit and the set value is calculated by a PID controller to obtain a sub-control signal a 1 ; the deviation value is passed through a selection module, a proportional and limiting function to obtain a sub-control signal a 2 ; the measured value of the original flue gas NO x is passed through a dead zone, a proportional function to obtain a sub-control signal a 3 ; the deviation value of the original flue gas NO x concentration and the deviation value of the urea dilution solution concentration are passed through a selection module, a proportional function to obtain a sub-control signal a 4 ; the constructed predicted signal of the original flue gas NO x concentration is passed through a selection module, a proportional function to obtain a sub-control signal a 5, to adjust the frequency of the urea solution delivery pump in advance; and to control the sub-signal a 1 、a 2 、a 3 、a 4 、a 5 After summation and passing through a clipping function, the frequency of the urea solution delivery pump is obtained, which can effectively overcome the large delay problem in NO x concentration measurement, realize the automatic control of SNCR denitration during rapid load change of CFB units, reduce the operation volume of operators, and improve the NO x emission concentration control performance.

[0180] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0181] It should also be noted that the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, commodity or device including the element.

[0182] The above are only the embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A circulating fluidized bed boiler denitration control method, characterized in that: include: Obtaining the original flue gas NO of circulating fluidized bed boiler x The concentration measurement value and the concentration measurement value of the diluted urea solution after diluting the urea solution; Determine the original flue gas NO x The concentration measurement value is consistent with the preset original flue gas NO x a first deviation value of the concentration setting value, taking the first deviation value as an input of a PID controller, and adjusting the first deviation value by the PID controller to generate a first sub-control signal; Determining an initial second sub-control signal according to a matching result between the first deviation value and a preset deviation threshold, and performing a limiting process on the initial second sub-control signal through a first limiting model to obtain a second sub-control signal; According to the original flue gas NO x The concentration measurement value is consistent with the original flue gas NO x The matching result of the concentration setting value generates a third sub-control signal; Acquiring a target load of the circulating fluidized bed boiler, determining a urea dilution solution concentration setting value according to a matching result between the target load and a preset rated load, and generating a fourth sub-control signal based on a matching result between the urea dilution solution concentration measurement value and the urea dilution solution concentration setting value; The operating parameters of the circulating fluidized bed boiler are obtained, and the operating parameters are used as input to obtain the original flue gas NO x The concentration prediction model outputs the raw flue gas NO of the circulating fluidized bed boiler x Concentration prediction value, based on the original flue gas NO x The predicted concentration value is consistent with the original flue gas NO x The matching result of the concentration setting value generates a fifth sub-control signal; The first sub-control signal, the second sub-control signal, the third sub-control signal, the fourth sub-control signal and the fifth sub-control signal are summed and limited to obtain a urea solution frequency control signal, and the operating frequency of the urea solution delivery pump is controlled by the urea solution frequency control signal.

2. The circulating fluidized bed boiler denitration control method according to claim 1, characterized in that: Determining an initial second sub-control signal according to a matching result between the first deviation value and a preset deviation threshold value includes: Taking the matching result between the first deviation value and the preset deviation threshold as input, an initial second sub-control signal is determined through a first selection model, wherein the first selection model includes: Where, e(t) represents the first deviation value, f 21 (x) represents the initial second sub-control signal.

3. The circulating fluidized bed boiler denitration control method according to claim 1, characterized in that: The initial second sub-control signal is subjected to a limiting process by using a first limiting model to obtain a second sub-control signal, including: Determine a first proportionality coefficient, use the product of the first proportionality coefficient and the initial second sub-control signal as the input of the first limiting model, and output the second sub-control signal through the first limiting model; The first limiting model comprises: Among them, f 22 (x) represents the second sub-control signal, x represents the signal corresponding to the product of the first proportional coefficient and the initial second sub-control signal, and y represents the operating frequency adjustment range of the urea solution delivery pump.

4. The circulating fluidized bed boiler denitration control method according to claim 1, characterized in that: According to the original flue gas NO x The concentration measurement value is consistent with the original flue gas NO x The matching result of the concentration setting value generates a third sub-control signal, including: The original flue gas NO x The concentration measurement value is consistent with the original flue gas NO x The concentration setting value is input, and the initial third sub-control signal is output through the preset dead zone model; determining an operating frequency adjustment range of the urea solution delivery pump, taking the operating frequency adjustment range of the urea solution delivery pump as a second proportional coefficient, and taking a product of the second proportional coefficient and the third sub-control signal as a third sub-control signal; Wherein, the second proportional coefficient is the operating frequency adjustment range of the urea solution delivery pump, and the dead zone model includes: Where x represents the original flue gas NO x Concentration measurement Indicates the original flue gas NO x Concentration setting value.

5. The circulating fluidized bed boiler denitration control method according to claim 1, characterized in that: Determining a set value of the concentration of the urea dilution solution according to a matching result between the target load and a preset rated load includes: Taking the target load and the rated load as input, outputting a urea dilution solution concentration setting value through a preset urea dilution solution concentration setting value model; Wherein, the urea dilution solution concentration setting value model includes: Wherein, x0 is the ratio of the target load to the rated load, and f(x0) represents the set value of the concentration of the urea dilution solution, %; Generating a fourth sub-control signal based on a matching result between the measured concentration value of the urea dilution solution and the set concentration value of the urea dilution solution includes: Taking the measured value of the concentration of the urea dilution solution and the set value of the concentration of the urea dilution solution as input, outputting an initial fourth sub-control signal through a preset second selection model; Determine a third proportional coefficient, and use the product of the third proportional coefficient and the initial fourth sub-control signal as the fourth sub-control signal; The second selection model includes: Where x represents the measured value of the urea dilution solution concentration, Indicates the original flue gas NO x Concentration measurement value, Indicates the original flue gas NO x Concentration setting value; Determine the third proportionality factor, including: The operating frequency adjustment range of the urea solution delivery pump is determined, and the product of the first preset ratio and the operating frequency adjustment range of the urea solution delivery pump is used as a third proportional coefficient.

6. The circulating fluidized bed boiler denitration control method according to claim 1, characterized in that: The operating parameters of the circulating fluidized bed boiler include: The current load, coal feed rate, total air volume, bed temperature, furnace outlet temperature of the circulating fluidized bed boiler and the operating frequency of the urea solution delivery pump; The original flue gas NO x Concentration prediction models, including: C NO,p =k NO,f C NO,f M NO Among them, C NO,p The original flue gas NO of the circulating fluidized bed boiler x Concentration prediction, C NO,f Indicates SNCR system NO x The average molar concentration, M NO represents the molar mass of nitric oxide, k NO,f is the concentration proportionality coefficient; The SNCR system NO x The average molar concentration is calculated by the following formula: Wherein, V2 is the volume of the cyclone separator, and the cyclone separator is used to spray the urea dilution solution, k s is the NH3 oxidation reaction conversion coefficient, k SNCR is the SNCR denitrification reaction rate constant, T f is the furnace outlet temperature of the circulating fluidized bed boiler, u Air is the total air volume, is the average concentration of NH3 at the cyclone separator, C NO Indicates the NO in the furnace of the circulating fluidized bed boiler x Average concentration; Wherein, the concentration ratio coefficient k NO,f It is determined by a preset concentration proportional coefficient curve, wherein the concentration proportional coefficient curve at least includes concentration proportional coefficients corresponding to different loads of the circulating fluidized bed boiler.

7. The circulating fluidized bed boiler denitration control method according to claim 6, characterized in that: The average concentration of NH3 at the cyclone separator is calculated by the following formula: Among them, k NH3 is the ammonia slip correction coefficient of the circulating fluidized bed boiler, is the molar rate of NH3 generation from urea dilute solution, in, The density of urea solution with a concentration of 20% is is the molar mass of urea, The flow rate of urea solution with a concentration of 20%, Among them, u Hz is the operating frequency of the urea solution delivery pump; The NO in the furnace of the circulating fluidized bed boiler x The average concentration was calculated using the following formula: Among them, k NO represents the reaction rate constant of NO and CO, G NO Indicates the NO in the furnace of the circulating fluidized bed boiler x Generation rate, R NO Indicates the NO in the furnace of the circulating fluidized bed boiler x Reduction rate, C CO Indicates the average concentration of CO in the furnace, d c is the fuel particle size, ρ c is the fuel density, m B is the amount of residual carbon in the furnace of the circulating fluidized bed boiler; Among them, C CO Calculated by the following formula: in, is the mechanical factor of carbon combustion, represents the reaction rate of CO oxidation to CO2, is the CO oxidation rate constant, is the average oxygen concentration in the furnace of the circulating fluidized bed boiler, R c is the residual carbon combustion rate in the furnace of the circulating fluidized bed boiler.

8. The circulating fluidized bed boiler denitration control method according to claim 7, characterized in that: The calculation formula is: R c The calculation formula is: in, M c , k c are the molar mass of carbon and the combustion rate constant, k c =0.513T b exp(-9160 / T b ), T b is the bed temperature of circulating fluidized bed boiler, R loss is the carbon mass flow rate in fly ash and bottom ash, V1 is the furnace volume of the circulating fluidized bed boiler, k q is the air volume to molar amount conversion coefficient, wherein the carbon mass flow rate in the fly ash and bottom ash is determined by a preset carbon mass flow rate curve, and the carbon mass flow rate curve at least includes the carbon mass flow rate in the fly ash and bottom ash corresponding to different loads of the circulating fluidized bed boiler; G NO The calculation formula is: G NO =1000η N [u c V ar N ar +R c (1-V ar )N ar / X c ] / M NO Among them, η N is the fuel nitrogen conversion rate, u c is the coal feeding amount, V ar is the mass fraction of volatile matter, N ar is the mass fraction of nitrogen, X c is the mass fraction of fixed carbon on the received basis.

9. The circulating fluidized bed boiler denitration control method according to claim 1, characterized in that: Based on the original flue gas NO x The predicted concentration value is consistent with the original flue gas NO x The matching result of the concentration setting value generates a fifth sub-control signal, including: The original flue gas NO x The predicted concentration value is consistent with the original flue gas NO x The concentration setting value is input, and the initial fifth sub-control signal is output through the preset third selection model; determining a fourth proportionality coefficient, and taking the product of the fourth proportionality coefficient and the initial fifth sub-control signal as the fifth sub-control signal; The third selection model includes: Among them, C NO,p The original flue gas NO of the circulating fluidized bed boiler x Concentration prediction value, Indicates the original flue gas NO x Concentration setting value; Determining a fourth proportionality factor includes: The operating frequency adjustment range of the urea solution delivery pump is determined, and the product of the second preset ratio and the operating frequency adjustment range of the urea solution delivery pump is used as a fourth proportional coefficient.

10. A circulating fluidized bed boiler denitration control device, characterized in that: include: The data acquisition module is configured to obtain the original flue gas NO x The concentration measurement value and the concentration measurement value of the diluted urea solution after diluting the urea solution; The first sub-control signal generating module is configured to determine the original flue gas NO x The concentration measurement value is consistent with the preset original flue gas NO x a first deviation value of the concentration setting value, taking the first deviation value as an input of a PID controller, and adjusting the first deviation value by the PID controller to generate a first sub-control signal; a second sub-control signal generating module, configured to determine an initial second sub-control signal according to a matching result between the first deviation value and a preset deviation threshold, and perform a limiting process on the initial second sub-control signal through a first limiting model to obtain a second sub-control signal; The third sub-control signal generating module is configured to generate a signal according to the original flue gas NO x The concentration measurement value is consistent with the original flue gas NO x The matching result of the concentration setting value generates a third sub-control signal; a fourth sub-control signal generating module, configured to obtain a target load of the circulating fluidized bed boiler, determine a urea dilution solution concentration setting value according to a matching result between the target load and a preset rated load, and generate a fourth sub-control signal based on a matching result between the urea dilution solution concentration measurement value and the urea dilution solution concentration setting value; The fifth sub-control signal generating module is configured to obtain the operating parameters of the circulating fluidized bed boiler, take the operating parameters as input, and generate a pre-constructed raw flue gas NO x The concentration prediction model outputs the raw flue gas NO of the circulating fluidized bed boiler x Concentration prediction value, based on the original flue gas NO x The predicted concentration value is consistent with the original flue gas NO x The matching result of the concentration setting value generates a fifth sub-control signal; The urea solution frequency control module is configured to obtain a urea solution frequency control signal after summing and limiting the first sub-control signal, the second sub-control signal, the third sub-control signal, the fourth sub-control signal and the fifth sub-control signal, and control the operating frequency of the urea solution delivery pump with the urea solution frequency control signal.

Images