Selective catalytic reduction (SCR) denitration ammonia spraying system optimization control method and system adapting to composite hot water recycling technology under deep peak regulation

Abstract

The invention discloses a selective catalytic reduction (SCR) denitration ammonia spraying system optimization control method and system suitable for a composite hot water recycling technology under deep peak regulation, and the method comprises the steps: collecting the deep peak regulation operation data of a unit, constructing a state space model of a composite hot water recycling system, and designing a model prediction controller; the bypass flow of the economizer is regulated and controlled to increase and stabilize the SCR inlet smoke temperature; meanwhile, the inlet smoke temperature, the NOx concentration of a hearth outlet and the ammonia concentration of the outlet serve as feed-forward quantities, and system fluctuation is compensated; and an SCR ammonia spraying system model prediction controller is constructed in combination with the NOx concentration of the outlet and the ammonia spraying amount, the ammonia spraying amount is dynamically optimized, and accurate control over NOx emission is achieved. The system comprises a data acquisition module, a composite hot water recirculation module, a feed-forward compensation module and an SCR denitration ammonia spraying module. By means of hot water recirculation and feedforward cooperative control, the ammonia spraying precision and the anti-interference capacity under the low load are effectively improved, ammonia escape is reduced, and it is guaranteed that pollutants are discharged after reaching the standard.

Description

Technical Field

[0001] This invention relates to the field of energy system control design technology, specifically to an optimized control method and system for an SCR denitrification ammonia injection system adapted to deep peak shaving and composite hot water recirculation technology. Background Technology

[0002] In recent years, renewable energy generation has accounted for an increasingly larger proportion of the power grid, posing challenges to the safe and stable operation of the grid. Traditional thermal power units are undertaking more and more peak-shaving and frequency regulation tasks, transforming from a basic energy source to a regulatory energy source. Coal-fired power plants need to have deeper peak-shaving capabilities. On the other hand, to adapt to the problems of excessive nitrogen oxide emissions, limited heating capacity, and combustion stability that arise under the new deep peak-shaving conditions, large thermal power units are increasingly undergoing flexibility retrofits. Among these, wide-load denitrification retrofitting is the most important part. Currently, the vast majority of generating units in China use Selective Catalytic Reduction (SCR) denitrification technology. The SCR process reacts ammonia with NO in the flue gas... x The reaction produces nitrogen and water, reducing the concentration of nitrogen oxides in the flue gas and achieving flue gas denitrification. When the unit load fluctuates, NO reduction is often achieved by increasing the ammonia injection rate. x While emissions are within a reasonable range, excessive ammonia injection can lead to unreacted NH3 entering downstream equipment, causing air preheater blockage, corrosion, or secondary pollution. Therefore, precise control of ammonia injection is necessary to manage NO emissions under significant load fluctuations. x The removal.

[0003] Under deep peak shaving conditions, ultracritical (supercritical) units operate at low loads for extended periods, leading to load fluctuations, reduced economizer outlet flue gas temperature, decreased inlet flue gas temperature of the denitrification system, and reduced catalyst activity or even malfunction in the SCR denitrification system, resulting in NO2 emissions. x Fluctuations in emissions and increased ammonia injection volume lead to ammonia escape.

[0004] Current research on the optimization control of SCR denitrification ammonia injection systems is mostly based on scenarios under normal unit operating conditions, with little research on ammonia injection strategies under low-load operating conditions during deep peak shaving. Under deep peak shaving conditions, the inlet flue gas temperature of the SCR denitrification ammonia injection system cannot meet the temperature range for normal catalyst operation. Traditional ammonia injection control strategies may, due to system inertia and delay characteristics, continue to increase the ammonia injection rate on the injection system side to compensate for the increased local nitrogen oxide emissions, thereby causing excessive ammonia escape and NOx emissions. xFurther fluctuations can cause components in the flue gas to react with excess ammonia, clogging catalyst channels and downstream equipment, leading to the inability of the denitrification unit to operate normally. Existing research mostly focuses on the technical modification of denitrification systems with wide-load flexibility, but there is little research on control strategies for ammonia injection systems after such modifications. Summary of the Invention

[0005] The purpose of this invention is to provide an optimized control method and system for an SCR denitrification ammonia injection system adapted to the composite hot water recirculation technology under deep peak shaving, so as to solve the problem that the SCR denitrification ammonia injection system after the flexibility technology transformation under deep peak shaving cannot accurately inject ammonia and automatically regulate it.

[0006] To achieve the above objectives, the present invention provides an optimized control method for an SCR denitrification ammonia injection system adapted to deep peak shaving and composite hot water recirculation technology, comprising the following steps: Step 1: Obtain the boiler type parameters of the ultra-supercritical unit and the normal operating temperature range of the denitrification catalyst in the SCR denitrification ammonia injection system; obtain the threshold value of the economizer outlet subcooling during safe operation of the ultra-supercritical unit and the actual operating range of the ammonia injection rate in the SCR denitrification ammonia injection system; obtain the operating data under deep peak shaving of the boiler, including: the actual operating temperature of the flue gas at the inlet of the SCR denitrification ammonia injection system, the actual operating subcooling at the economizer outlet, and the NO at the boiler furnace outlet. x Actual operating concentration, actual operating concentration of NH3 at the outlet of the SCR denitrification ammonia injection system, and NO at the outlet of the SCR denitrification ammonia injection system. x Actual operating concentration, circulating water bypass flow rate, and simple water bypass flow rate; Step 2: Based on the operating data of the boiler under deep peak shaving, construct the state-space model of the composite hot water recirculation system, design its model predictive controller, define the optimization objective function and constraints, and output the inlet flue gas temperature of the SCR denitrification ammonia injection system and the subcooling degree of the economizer outlet. Step 3: Calculate the inlet flue gas temperature of the SCR denitrification ammonia injection system and the boiler furnace outlet NO2 output from Step 2. x The actual operating concentration and the actual operating concentration of NH3 at the outlet of the SCR denitrification ammonia injection system are processed through a mapping relationship to generate a feedforward control quantity, which is then sent to the SCR denitrification ammonia injection system to correct fluctuations in relevant thermodynamic parameters of the SCR denitrification ammonia injection system. Step 4: Combine the NO at the outlet of the SCR denitrification ammonia injection system under deep peak shaving of the boiler. x Based on the actual operating concentration and the actual ammonia injection rate of the SCR denitrification ammonia injection system, a state-space model of the SCR denitrification ammonia injection system is constructed. Its model predictive controller is designed, and the optimization objective function and constraints are defined to output the NO output of the SCR denitrification ammonia injection system at the outlet. x concentration.

[0007] To optimize the above technical solutions, the specific measures taken also include: In step 1, the normal operating temperature range of the SCR denitration ammonia injection system catalyst is specifically:

[0008] Among them, is the minimum temperature at which the denitration catalyst can be put into reaction; is the maximum temperature at which the denitration catalyst can be put into reaction; is the actual temperature of the denitration catalyst during operation.

[0009] In step 2, the specific process of constructing a state space model of the composite hot water recirculation system according to the operation data under the deep peak regulation of the boiler and designing a model predictive controller thereof is: According to the operation data under the deep peak regulation of the boiler, the state space model of the composite hot water recirculation system is obtained by using the subspace identification method, and a model predictive controller thereof is designed. Based on the model predictive controller, the space model is augmented to an incremental extended state space model containing the state variables and output of the composite hot water recirculation system.

[0010] Further, in step 2, the optimization objective function of the composite hot water recirculation system model predictive controller J 1 The expression is:

[0011] Among them, denotes the set value matrix of the controlled quantity; is the output value sequence under the prediction step; denotes the input increment sequence; denotes the error weight matrix; is the control weight matrix; T is the transpose symbol; The optimization objective function of the composite hot water recirculation system model predictive controller is constrained by the bypass water flow and the circulating loop water flow, the SCR denitration ammonia injection system inlet flue gas temperature and the economizer outlet supercooling degree.

[0012] Further, in step 3, the feedforward control quantity is determined by the following formula:

[0013] Among them, denotes the feedforward control quantity of the SCR denitration ammonia injection system model predictive controller; F denotes the SCR denitration ammonia injection system inlet flue gas temperature, boiler furnace outlet NO x Actual operating concentration and SCR denitration ammonia injection system outlet NH3 Actual operating concentration and the mapping relationship of the feedforward control quantity; denotes the SCR denitration ammonia injection system inlet flue gas temperature output in step 2; denotes the boiler furnace outlet NO x Actual operation concentration; denotes the actual operation concentration of NH3 at the outlet of the SCR denitration ammonia injection system.

[0014] In step 4, the specific process for constructing the state space model of the SCR denitration ammonia injection system and designing the model predictive controller thereof is as follows: According to the ammonia injection amount of the SCR denitration ammonia injection system And the actual operation concentration of NO x Concentration at the outlet of the SCR denitration ammonia injection system, the state space model of the SCR denitration ammonia injection system is obtained by using the subspace identification method, and the model predictive controller thereof is designed, and based on the model predictive controller, the space model is augmented into an incremental extended state space model containing the state variables and output of the SCR denitration ammonia injection system.

[0015] Further, in step 4, the definition of the optimization objective function of the SCR denitration ammonia injection system model predictive controller J 2 is as follows:

[0016] Wherein, denotes the set value matrix of the controlled variable; is the output value sequence under the prediction step; denotes the input increment sequence; denotes the error weight matrix; is the control weight matrix; The optimization objective function of the SCR denitration ammonia injection system model predictive controller dynamically constrains the actual ammonia injection amount in the SCR denitration ammonia injection system and the actual operation concentration of NO x At the outlet of the SCR denitration ammonia injection system.

[0017] As another important technical scheme, the application also provides an SCR denitration ammonia injection system optimization control system adapted to the composite hot water recirculation technology under deep peak regulation, comprising: An operation data acquisition module is used to acquire the furnace type parameters of the ultra-supercritical unit and the normal operation temperature range of the denitration catalyst in the SCR denitration ammonia injection system; acquire the threshold of the outlet supercooling degree of the economizer when the ultra-supercritical unit is safely operated and the actual operation range of the ammonia injection amount in the SCR denitration ammonia injection system; and acquire the operation data under the deep peak regulation of the boiler, including: the actual operation temperature of the SCR denitration ammonia injection system inlet flue gas, the actual operation supercooling degree of the economizer outlet, the actual operation concentration of NO x At the boiler furnace outlet, the actual operation concentration of NH3 at the outlet of the SCR denitration ammonia injection system, and the actual operation concentration of NOx Actual operation concentration, circulating water bypass water flow and simple water bypass flow; The composite hot water recirculation system module is used for constructing a state space model of the composite hot water recirculation system according to operation data under boiler deep peak regulation, designing a model predictive controller thereof, defining an optimization objective function and a constraint condition, and outputting the SCR denitration ammonia injection system inlet flue gas temperature and the coal economizer outlet supercooling degree. The feedforward compensation and cooperation module is used for outputting the SCR denitration ammonia injection system inlet flue gas temperature, the boiler furnace outlet NOx concentration and the SCR denitration ammonia injection system outlet NH3 concentration in step 2. x The actual operation concentration and the SCR denitration ammonia injection system outlet NH3 actual operation concentration are processed through a mapping relationship to generate a feedforward control amount which is delivered to the SCR denitration ammonia injection system to correct the fluctuation of the relevant thermodynamic parameters of the SCR denitration ammonia injection system. The SCR denitration ammonia injection system module is used for combining the SCR denitration ammonia injection system outlet NOx concentration and the SCR denitration ammonia injection system actual ammonia injection amount under boiler deep peak regulation, constructing a state space model of the SCR denitration ammonia injection system, designing a model predictive controller thereof, defining an optimization objective function and a constraint condition, and outputting the SCR denitration ammonia injection system outlet NOx concentration. x The actual operation concentration and the SCR denitration ammonia injection system actual ammonia injection amount are processed through a mapping relationship to generate a feedforward control amount which is delivered to the SCR denitration ammonia injection system to correct the fluctuation of the relevant thermodynamic parameters of the SCR denitration ammonia injection system. x Concentration.

[0018] The application further provides an electronic device, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the SCR denitration ammonia injection system optimization control method for the composite hot water recirculation technology under deep peak regulation when executing the computer program.

[0019] The application further provides a computer readable storage medium, which stores a computer program, and the computer program enables a computer to execute the SCR denitration ammonia injection system optimization control method for the composite hot water recirculation technology under deep peak regulation.

[0020] Compared with the prior art, the application has the following beneficial effects: The application constructs the SCR denitration ammonia injection system optimization control strategy for the composite hot water recirculation flexible denitration under the deep peak regulation of the ultra-supercritical unit, adopts the hot water recirculation and the simple water bypass to cooperatively control the SCR denitration ammonia injection system inlet temperature by considering the wide load denitration composite hot water recirculation flexible modification technology, improves the wide load denitration capacity of the unit under low load, feeds forward the SCR denitration ammonia injection system inlet temperature, combines the boiler furnace outlet flue gas NOx concentration and the SCR denitration ammonia injection system outlet NH3 concentration, and generates a feedforward control amount which is delivered to the SCR denitration ammonia injection system to correct the fluctuation of the relevant thermodynamic parameters of the SCR denitration ammonia injection system. xThe concentration and the ammonia gas concentration measurable disturbance signal at the outlet of the ammonia injection system are jointly used as the feedforward control quantity to act on the denitration ammonia injection system model predictive controller to correct the fluctuation of the state quantity of the denitration ammonia injection system under the low load deep regulation condition, improve the accurate control of the wide load denitration ammonia injection quantity under the deep regulation condition, and meet the emission requirements of pollutants when the actual power plant is operated under the deep regulation condition. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 : Schematic diagram of the composite hot water recirculation flexible reconstruction technology coupled with the ammonia injection system of the application.

[0022] Figure 2 : Schematic diagram of the wide load denitration reconstruction ammonia injection optimization control strategy under the deep regulation condition of the application. DETAILED DESCRIPTION

[0023] The above content of the application will be further described in the form of specific embodiments, but this should not be understood as limiting the scope of the above subject matter of the application to the following examples. Any technology realized based on the above content of the application belongs to the scope of the application.

[0024] The application provides an SCR denitration ammonia injection system optimization control method suitable for the composite hot water recirculation technology under deep peak regulation, which comprises the following steps: Step 1, obtaining the furnace type parameters of the ultra-supercritical unit and the normal operation temperature interval of the denitration catalyst in the SCR denitration ammonia injection system:

[0025] Among them, is the minimum temperature at which the denitration catalyst can be put into reaction; is the maximum temperature at which the denitration catalyst can be put into reaction; is the actual temperature of the denitration catalyst during operation.

[0026] The threshold of the supercooling degree at the outlet of the economizer during the safe operation of the ultra-supercritical unit and the operation interval of the ammonia injection quantity in the denitration ammonia injection system are obtained to ensure that there is a certain safety margin for the operating parameters at the economizer side in the actual control process and set the upper and lower limit constraints of the ammonia injection quantity of the SCR denitration ammonia injection system.

[0027]

[0028]

[0029] Among them, is the minimum value of the supercooling degree at the outlet of the economizer; is the maximum value of the supercooling degree at the outlet of the economizer; is the value of the supercooling degree at the outlet of the economizer during actual operation. It is the minimum ammonia injection rate of the SCR denitrification ammonia injection system; This is the maximum ammonia injection rate of the SCR denitrification ammonia injection system; It is the amount of ammonia injected into the SCR denitrification ammonia injection system during actual operation.

[0030] Obtain operating data of the boiler under low-load deep-adjustment conditions, including: Actual operating temperature of inlet flue gas in SCR denitrification ammonia injection system under low load deep adjustment condition of boiler Ignoring temperature changes in the flue gas within the catalyst, the inlet temperature of the SCR denitrification ammonia injection system is the actual operating temperature of the SCR denitrification catalyst; the actual operating subcooling at the economizer outlet... Boiler furnace outlet NO x Actual operating concentration Actual operating concentration of NH3 at the outlet of the SCR denitrification ammonia injection system SCR denitrification ammonia injection system outlet NO x Actual operating concentration Circulating water bypass flow rate and simple water bypass flow ; Step 2: Based on the obtained operating data of the boiler under low-load deep-adjustment conditions, the bypass flow rate of the composite hot water recirculation system and the bypass flow rate of the simple water are used as input variables, and the actual operating subcooling at the economizer outlet and the actual operating temperature of the flue gas at the inlet of the SCR denitrification ammonia injection system are used as output variables. The state-space model of the composite hot water recirculation system is then constructed using the subspace identification method.

[0031] in, The state variable represents the internal state of the composite hot water recirculation wide-load SCR denitrification ammonia injection system at a certain moment, and has no actual physical meaning. This represents the system's input variable, specifically the circulating water bypass flow rate in this invention. and simple water bypass flow ; This represents the system's output variable, specifically the inlet flue gas temperature of the SCR denitrification ammonia injection system. and economizer outlet subcooling Coefficients A, B, and C represent the characteristic matrix of the composite hot water recirculation system. A represents the state matrix of the composite hot water recirculation system, B represents the control matrix of the composite hot water recirculation system, and C represents the output matrix of the composite hot water recirculation system. The values ​​of the characteristic matrices are related to the system itself. k represents the current moment. Preferably, based on the model predictive controller and combined with the state-space model of the composite hot water recirculation system, an incremental extended state-space model is established: The incremental model formula is obtained by increment transformation of the above formula:

[0032] wherein, and satisfy the following formula:

[0033] In order to obtain better tracking effect, the above formula, the incremental model formula and the composite hot water recirculation characteristic matrix coefficients A, B and C are reorganized to obtain an augmented model formula:

[0034] Let the prediction step in the model predictive controller be p, and the control step be m, and satisfy: .

[0035] As preferred, the composite hot water recirculation system state variable and output value are obtained:

[0036] Optimization objective function J 1expression is:

[0037] wherein, denotes the controlled quantity set value matrix; is the output value sequence under the prediction step; denotes the input increment sequence; denotes the error weight matrix; is the control weight matrix; T is the transpose symbol.

[0038] In some embodiments, due to the limitation of the circulating water flow and the bypass water flow valve opening degree in the actual operation process, it is necessary to constrain the bypass water flow and the circulating water flow in the control quantity, as well as the SCR denitration ammonia injection system inlet flue gas temperature and the supercooling degree to ensure that the system is in safe operation in the control process.

[0039]

[0040] wherein, denotes the control quantity, including the circulating water flow and the bypass water flow; denotes the controlled quantity, indicating the SCR denitration ammonia injection system inlet flue gas temperature and the supercooling degree.

[0041] For each sampling time, the constraint condition formula is solved in the optimization objective J 1to obtain the optimal control sequence It also exerts control over the composite hot water recirculation system, continuously performs rolling optimization, and completes the regulation of the inlet temperature of the SCR denitrification ammonia injection system and the subcooling of the economizer outlet.

[0042] Step 3: The output of the composite hot water recirculation system, i.e., the inlet flue gas temperature of the SCR denitrification ammonia injection system output in Step 2, is recorded. Combined with the NO at the boiler furnace outlet x Actual operating data of concentration and the NH at the outlet of the SCR denitrification ammonia injection system 3实际运行 Concentration data After mapping relationship F The feedforward control quantity is obtained after the action. The data is then fed into the model predictive controller of the SCR denitrification ammonia injection system to correct for fluctuations in relevant thermodynamic parameters under low load conditions during deep peak shaving.

[0043]

[0044] in, This represents the feedforward control quantity of the model predictive controller for the SCR denitrification ammonia injection system; F This indicates the output of step 2: SCR denitrification ammonia injection system inlet flue gas temperature and boiler furnace outlet NO. x Mapping relationship between actual operating concentration and actual operating concentration of NH3 at the outlet of SCR denitrification ammonia injection system and feedforward control quantity; This indicates the inlet flue gas temperature of the SCR denitrification ammonia injection system output in step 2; Indicates the boiler furnace outlet NO x Actual operating concentration; This indicates the actual operating concentration of NH3 at the outlet of the SCR denitrification ammonia injection system.

[0045] Step 4: Combine the NO outlet of the SCR denitrification ammonia injection system under deep peak shaving x Actual operating concentration The actual ammonia injection volume of the SCR denitrification ammonia injection system The amount of ammonia injected As an input variable, the NO at the outlet of the SCR denitrification ammonia injection system under deep peak shaving will be... x Concentration data As the output variable, the state-space model of the SCR denitrification ammonia injection system is constructed using the subspace identification method:

[0046] in, This represents the state variable of the ammonia injection system at a certain moment, and is an internal state variable of the ammonia injection system with no actual physical meaning. Input variable of the system, which is specifically represented as the actual ammonia injection amount of the SCR ammonia injection system in the model predictive controller of the SCR ammonia injection system ; Output variable of the system, which is specifically represented as the NOx concentration at the outlet of the SCR ammonia injection system x ; Complex disturbance at time k; coefficients A * , B * , C * , and D represent the characteristic matrix of the SCR ammonia injection system, A * represents the state matrix of the SCR ammonia injection system, B * represents the control matrix of the SCR ammonia injection system, C * represents the output matrix of the SCR ammonia injection system, and D represents the disturbance matrix of the SCR ammonia injection system; the numerical value of the characteristic matrix is related to the SCR ammonia injection system itself; k represents the current time; As preferred, based on the model predictive controller, an incremental extended state space model is established in combination with the state space model of the SCR ammonia injection system: An incremental model formula is obtained by performing incremental transformation on the above formula:

[0047] Wherein, , and satisfy:

[0048] In order to obtain better tracking effect, the above formula is reorganized to obtain an augmented model formula of the SCR ammonia injection system:

[0049] The prediction step in the model predictive controller of the SCR ammonia injection system is taken as , and the control step is taken as , wherein the prediction step and the control step satisfy: .

[0050] The state variable and the output value of the SCR ammonia injection system can be obtained as follows:

[0051] A rolling target optimization function is defined as follows: J 2:

[0052] Wherein, represents the set value matrix of the controlled variable ​to predict the output value sequence under the step length; denotes an input increment sequence; denotes an error weight matrix; is a control weight matrix; In some embodiments, considering the control stability of the actual unit during low load operation, dynamic constraints are considered for the input and output of the SCR denitration ammonia injection system:

[0053] At each time, the minimum value of the objective function subject to the constraints is calculated to obtain the optimal control sequence , which is applied to the control system, and the rolling optimization is performed at the next time to complete the construction of the SCR denitration ammonia injection system model predictive control strategy.

[0054] In another embodiment of the present application, an SCR denitration ammonia injection system optimization control system suitable for composite hot water recirculation technology under deep peak regulation is provided, comprising: An operation data acquisition module is used to obtain the furnace type parameters of the ultra-supercritical unit and the normal operation temperature range of the denitration catalyst in the SCR denitration ammonia injection system; obtain the threshold of the supercooled degree at the outlet of the coal economizer during safe operation of the ultra-supercritical unit and the actual operation range of the ammonia injection amount in the SCR denitration ammonia injection system; obtain the operation data under deep peak regulation of the boiler, including: the actual operation temperature of the flue gas at the inlet of the SCR denitration ammonia injection system, the actual operation supercooled degree at the outlet of the coal economizer, the actual operation concentration of NO x at the outlet of the boiler furnace, the actual operation concentration of NH3 at the outlet of the SCR denitration ammonia injection system, the actual operation concentration of NO x at the outlet of the SCR denitration ammonia injection system, the bypass water flow of the circulating water, and the simple bypass flow; A composite hot water recirculation system module is used to construct a state space model of the composite hot water recirculation system according to the operation data under deep peak regulation of the boiler, design a model predictive controller thereof, and define an optimization objective function and constraint conditions, and output the flue gas temperature at the inlet of the SCR denitration ammonia injection system and the supercooled degree at the outlet of the coal economizer; A feedforward compensation and cooperation module is used to process the flue gas temperature at the inlet of the SCR denitration ammonia injection system, the actual operation concentration of NO x at the outlet of the boiler furnace, and the actual operation concentration of NH3 at the outlet of the SCR denitration ammonia injection system output in step 2 through a mapping relationship to generate a feedforward control amount and deliver it to the SCR denitration ammonia injection system to correct the fluctuations of the related thermodynamic parameters of the SCR denitration ammonia injection system; An SCR denitration ammonia injection system module is used to combine the actual operation concentration of NO xActual operation concentration, actual ammonia injection amount of the SCR denitration ammonia injection system, construction of the state space model of the SCR denitration ammonia injection system, design of the model predictive controller thereof, definition of the optimization objective function and constraint condition, and output of the NO x Concentration.

[0055] In another embodiment, the application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and when the processor executes the computer program, a method for optimizing control of an SCR denitration ammonia injection system adapted to composite hot water recirculation technology under deep peak shaving is implemented.

[0056] In another embodiment, the application provides a computer readable storage medium, which stores a computer program, and the computer program causes a computer to execute a method for optimizing control of an SCR denitration ammonia injection system adapted to composite hot water recirculation technology under deep peak shaving.

[0057] In the embodiments disclosed in the present application, the computer storage medium can be a tangible medium, which can contain or store programs for use by or in connection with an instruction execution system, apparatus or device. The computer storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses or devices, or any suitable combination of the above. More specific examples of computer storage media can include one or more wires, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), optical fibers, portable compact disk read-only memories (CD-ROMs), optical storage devices, magnetic storage devices, or any suitable combination of the above.

[0058] In some embodiments, as Figure 1 As shown in the figure, the figure shows the overall process flow diagram of the composite hot water recirculation technology adapted to deep peak shaving and the SCR denitration ammonia injection system working in cooperation. The working process starts from boiler feed water, the working medium first enters the economizer to absorb the waste heat of the tail flue gas, and then flows to the water-cooled wall to be heated by the high-temperature flue gas in the furnace, to generate a steam-water mixture that rises to the steam-water separator for separation, the saturated steam enters the superheater for further heating to become superheated steam, and the separated saturated water is divided into two paths: the main path working medium normally participates in the cycle, and the key branch is used as the water source of the composite hot water recirculation system, by extracting a part of the circulating water bypass water flow and sending it back to the economizer inlet, and the simple water bypass flow mixing; the hot water stream increases the temperature of the working medium at the inlet of the economizer, thereby reducing the heat absorbed by the economizer from the flue gas, effectively raising the flue gas temperature out of the economizer, and ensuring that the temperature of the low-temperature flue gas entering the SCR denitration device meets the catalyst activity requirement; at the same time, the ammonia injection system injects ammonia NH3 into the flue according to the control instruction, and the ammonia NH3 reacts with the nitrogen oxides in the flue gas in the SCR device to achieve the standard emission of pollutants C NOx The core of the whole process is to adjust the heat exchange process of the economizer through the composite hot water recirculation system and to solve the key problem of excessively low SCR inlet flue gas temperature under deep peak shaving and low load conditions, thereby creating necessary conditions for subsequent precise ammonia injection denitration.

[0059] In some embodiments, the ammonia injection system optimization control strategy under the whole wide load denitration composite hot water recirculation modification is as shown in the accompanying drawings of the specification. Figure 2 The composite hot water recirculation system control loop takes the supercooling degree at the outlet of the economizer as the core controlled variable. The set value is first compared with the actual measurement value of the superheating degree at the outlet of the economizer, and the deviation is sent to the model predictive controller of the composite hot water recirculation system. The model predictive controller has a state space model identified from system operation data built-in, which can predict the system behavior under different control actions. The model predictive controller aims to minimize the supercooling degree deviation and suppress the drastic changes of the control amount and system constraints according to the optimization objective function J1, and calculates a set of optimal recirculation loop water flow and economizer bypass water flow instructions through rolling optimization. The two flow rates are applied to the composite hot water recirculation system as control variables, and the core control target is to adjust the flue gas temperature and water temperature at the outlet of the economizer, and finally output the SCR denitration ammonia injection system inlet flue gas temperature and the actual supercooling degree at the outlet of the economizer. The supercooling degree is fed back to form a closed loop control, which ensures that the economizer operates within a safe range, and at the same time, adjusts the flow rate to raise and stabilize the SCR denitration ammonia injection system inlet flue gas temperature in the high-efficiency activity interval required by the denitration catalyst.

[0060] The denitration ammonia injection system control loop takes the NO x concentration at the outlet of the SCR denitration ammonia injection system as the core controlled variable. The set value (set according to environmental protection emission requirements) is compared with the actual measurement value of the NO x concentration, and the deviation is sent to the model predictive controller of the SCR denitration ammonia injection system. The model predictive controller is also based on the dynamic model of the ammonia injection system, and calculates the optimal ammonia injection amount instruction by optimizing the objective function J2, which aims to accurately track the NO x set value and avoid excessive ammonia injection, and acts on the denitration ammonia injection system, thereby changing the chemical reaction intensity in the SCR reactor, ultimately affecting the NO x concentration at the outlet of the SCR denitration ammonia injection system, forming a closed loop control, and ensuring that the NOx Emission compliance.

[0061] Through the highly coordinated feedforward mechanism, the SCR denitration ammonia injection system inlet flue gas temperature generated by the composite hot water recirculation system control loop is directly introduced into the denitration ammonia injection system model predictive controller of the denitration ammonia injection system control loop as a key feedforward signal. This is because the change of the inlet flue gas temperature will significantly affect the catalyst reaction efficiency, and is a main disturbance of the ammonia injection control. Through feedforward compensation, the denitration ammonia injection system model predictive controller can predict in advance the influence of the change of the flue gas temperature on the denitration effect, and adjust the ammonia injection amount accordingly, so as to overcome the large inertia of the system and the hysteresis of the pure feedback control, greatly improve the accuracy and anti-interference ability of the control, effectively inhibit the ammonia escape and NO x Emission fluctuation.

[0062] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any skilled person in the art, without departing from the technical solution of the present application, according to the technical essence of the present application, any simple modification, equivalent replacement and improvement of the above embodiment, etc. still belongs to the protection scope of the technical solution of the present application.

Claims

1. An SCR denitration ammonia injection system optimization control method suitable for a composite hot water recirculation technology under deep peak shaving, characterized in that, The method comprises the following steps: Step 1, obtaining the furnace type parameters of the ultra-supercritical unit and the normal operation temperature range of the denitration catalyst in the SCR denitration ammonia injection system; obtaining the threshold of the supercooled degree at the outlet of the coal economizer and the actual operation range of the ammonia injection amount in the SCR denitration ammonia injection system when the ultra-supercritical unit is safely operated; Obtain operating data for boilers under deep peak shaving conditions, including: actual operating temperature of flue gas at the inlet of the SCR denitrification and ammonia injection system, actual operating subcooling at the economizer outlet, and NO at the boiler furnace outlet. x Actual operating concentration, actual operating concentration of NH3 at the outlet of the SCR denitrification ammonia injection system, and NO at the outlet of the SCR denitrification ammonia injection system. x Actual operating concentration, circulating water bypass flow rate, and simple water bypass flow rate; Step 2, constructing a state space model of the composite hot water recirculation system according to the operation data under the deep peak regulation of the boiler, designing a model predictive controller thereof, defining an optimization objective function and a constraint condition, and outputting the inlet flue gas temperature of the SCR denitration ammonia injection system and the supercooled degree at the outlet of the coal economizer; Step 3, the boiler furnace outlet NO x The actual operation concentration, the actual operation concentration of the SCR denitration ammonia injection system outlet NH3, and the flue gas temperature at the inlet of the SCR denitration ammonia injection system output in step 2 are processed through a mapping relationship to generate a feedforward control quantity, which is delivered to the SCR denitration ammonia injection system to correct the fluctuations of the related thermodynamic parameters of the SCR denitration ammonia injection system. Step 4, the actual concentration of NO in the outlet of the SCR denitration ammonia injection system under the deep peak shaving of the boiler x The actual concentration of NO in the outlet of the SCR denitration ammonia injection system under the deep peak shaving of the boiler x The actual concentration of NO in the outlet of the SCR denitration ammonia injection system under the deep peak shaving of the boiler 2. The SCR denitration ammonia injection system optimization control method suitable for the composite hot water recirculation technology under deep peak shaving adaptation according to claim 1, characterized in that: In step 2, the specific process of constructing a state space model of the composite hot water recirculation system according to the operation data under the deep peak regulation of the boiler and designing a model predictive controller thereof is as follows: According to the operation data under the deep peak regulation of the boiler, the state space model of the composite hot water recirculation system is obtained by using the subspace identification method, and the model predictive controller thereof is designed, and the space model is augmented into an incremental extended state space model containing the state variables and output of the composite hot water recirculation system based on the model predictive controller.

3. The SCR denitration ammonia injection system optimization control method suitable for the composite hot water recirculation technology under deep peak shaving adaptation according to claim 2, characterized in that: In step 2, the optimization objective function of the composite hot water recirculation system model predictive controller J 1The expression is: wherein, denotes a controlled variable setpoint matrix; is the output value sequence for the prediction step; denotes an input increment sequence; denotes an error weight matrix; is the control weight matrix; T is the transpose symbol; The optimization objective function of the model predictive controller of the composite hot water recirculation system is constrained by the bypass water flow, the circulating loop water flow, the inlet flue gas temperature of the SCR denitration ammonia injection system and the supercooled degree at the outlet of the coal economizer.

4. The SCR denitration ammonia injection system optimization control method suitable for the composite hot water recirculation technology under deep peak shaving adaptation according to claim 1, characterized in that: In step 3, the feedforward control amount is determined by the following formula: wherein, represents the feedforward control amount of the SCR denitration ammonia injection system model predictive controller; F represents the SCR denitration ammonia injection system inlet flue gas temperature, boiler furnace outlet NO x actual operating concentration and the mapping relationship between the SCR denitration ammonia injection system outlet NH3 actual operating concentration and the feedforward control amount; represents the SCR denitration ammonia injection system inlet flue gas temperature output in step 2; represents the boiler furnace outlet NO x actual operating concentration; represents the SCR denitration ammonia injection system outlet NH3 actual operating concentration.

5. The SCR denitration ammonia injection system optimization control method suitable for the composite hot water recirculation technology under deep peak shaving adaptation according to claim 1, characterized in that: In step 4, the specific process of constructing a state space model of the SCR denitration ammonia injection system and designing a model predictive controller thereof is as follows: According to the SCR denitration ammonia injection system ammonia injection amount And the actual operation process of SCR denitration ammonia injection system outlet NO x Concentration, the state space model of SCR denitration ammonia injection system is obtained by using subspace identification method, and its model predictive controller is designed, and based on the model predictive controller, the space model is extended to an incremental extended state space model containing the state variables and output of the SCR denitration ammonia injection system.

6. The SCR denitration ammonia injection system optimization control method suitable for the composite hot water recirculation technology under deep peak shaving adaptation according to claim 5, characterized in that: In step 4, the definition of the optimization objective function of the SCR denitration ammonia injection system model predictive controller J 2The expression is: wherein, denotes a controlled variable setpoint matrix; is an output value sequence for a prediction step; denotes an input increment sequence; denotes an error weight matrix; is a control weight matrix; The optimization objective function of the SCR denitration ammonia injection system model predictive controller dynamically constrains the actual ammonia injection amount in the SCR denitration ammonia injection system and the outlet NOx concentration of the SCR denitration ammonia injection system according to the actual operation concentration. x actual operation concentration.

7. An SCR denitration ammonia injection system optimization control system adapted to a composite hot water recirculation technology under deep peak shaving, characterized in that, It comprises: An operation data acquisition module for obtaining the furnace type parameters of the ultra-supercritical unit and the normal operation temperature range of the denitration catalyst in the SCR denitration ammonia injection system; Obtaining the threshold of the supercooled degree at the outlet of the coal economizer and the actual operation range of the ammonia injection amount in the SCR denitration ammonia injection system when the ultra-supercritical unit is safely operated; Obtain the operation data under the boiler deep peak shaving, including: the actual operation temperature of the SCR denitration ammonia injection system inlet flue gas, the actual operation supercooling degree of the economizer outlet, the actual operation concentration of the boiler furnace outlet NO x , the actual operation concentration of the SCR denitration ammonia injection system outlet NH3, the actual operation concentration of the SCR denitration ammonia injection system outlet NO x , the circulating water bypass water flow and the simple water bypass flow. A composite hot water recirculation system module for constructing a state space model of the composite hot water recirculation system according to the operation data under the deep peak regulation of the boiler, designing a model predictive controller thereof, defining an optimization objective function and a constraint condition, and outputting the inlet flue gas temperature of the SCR denitration ammonia injection system and the supercooled degree at the outlet of the coal economizer; A feedforward compensation and cooperation module is used for the SCR denitration ammonia injection system inlet flue gas temperature, boiler furnace outlet NO x The actual operation concentration, the SCR denitration ammonia injection system outlet NH3 actual operation concentration is processed through a mapping relationship to generate a feedforward control quantity which is delivered to the SCR denitration ammonia injection system to correct the fluctuation of the relevant thermodynamic parameters of the SCR denitration ammonia injection system. SCR denitration ammonia injection system module for combining the boiler deep peak shaving SCR denitration ammonia injection system outlet NO x Actual operation concentration, the actual ammonia injection amount of the SCR denitration ammonia injection system, the state space model of the SCR denitration ammonia injection system is constructed, the model predictive controller thereof is designed, and the optimization objective function and the constraint condition are defined, and the outlet NO x Concentration.

8. An electronic device, comprising: It comprises: A memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for optimizing control of the SCR denitration ammonia injection system adapted to the composite hot water recirculation technology under the deep peak regulation is realized.

9. A computer readable storage medium having stored thereon a computer program, characterized in that: The computer program enables the computer to execute the method for optimizing control of the SCR denitration ammonia injection system adapted to the composite hot water recirculation technology under the deep peak regulation.

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