Denitration spraying control system of thermal power plant

Abstract

The invention relates to the technical field of denitration spraying, in particular to a thermal power plant denitration spraying control system which comprises an SCR reactor and an ammonia spraying module and is used for rapidly responding to unit load changes so as to avoid large fluctuation of NOx concentration, rapidly adjusting the ammonia spraying amount and achieving control over the NOx concentration. The NOx monitoring module is used for providing real-time data of the concentration of NOx in flue gas at an outlet and is used for accurate control; the oxygen content monitoring module is used for providing data of the oxygen content in the inlet flue gas and assisting accurate control; the air volume monitoring module provides data of the total air volume of the boiler and assists in accurate control; and the control unit module carries out accurate adjustment according to the deviation between the actual measurement value and the set value of NOx, the NOx control precision and the response speed can be improved, the use of a reducing agent is optimized, the stability and the environmental protection performance of the system can be enhanced, and the economic benefit and the market competitiveness of enterprises are improved.

Description

Technical Field

[0001] The invention relates to the technical field of denitration spraying, and in particular to a denitration spraying control system for a thermal power plant. Background Art

[0002] Traditional thermal power plants mainly rely on selective catalytic reduction (SCR) technology in flue gas denitrification. The core of SCR technology is to use catalysts to react ammonia (NH3) with nitrogen oxides (NOx) in flue gas at appropriate temperatures to generate harmless nitrogen (N2) and water (H2O). This process is usually carried out in a specific reactor in the boiler or flue, and the amount of ammonia injection needs to be precisely controlled to achieve the best denitrification effect.

[0003] When the unit load changes, the NOx concentration in the flue gas will change rapidly, and the traditional control system has a time delay in adjusting the amount of ammonia injection, resulting in fluctuations in NOx emission concentration. Due to insufficient control accuracy, the system may inject excessive ammonia, which not only causes waste of reducing agent, but also may cause ammonia escape problems, affecting the operation of subsequent equipment. As environmental regulations on NOx emission limits become increasingly stringent, traditional denitrification systems are increasingly difficult to meet emission requirements, resulting in environmental fines and increased operating costs. Excessive NOx or ammonia causes corrosion and blockage to SCR reactors and downstream equipment (such as air preheaters), increasing maintenance costs. Summary of the invention

[0004] In view of the above-mentioned existing NOx concentration in the flue gas will change rapidly when the unit load changes, and there is a time delay in the traditional control system to adjust the ammonia injection amount, resulting in fluctuations in NOx emission concentration. Due to insufficient control accuracy, the system may inject excessive ammonia, which not only causes waste of reducing agent, but also may cause ammonia escape problems, affecting the operation of subsequent equipment. As environmental protection regulations on NOx emission limits become increasingly stringent, traditional denitrification systems are increasingly difficult to meet emission requirements, resulting in environmental fines and increased operating costs. Excessive NOx or ammonia causes corrosion and blockage to the SCR reactor and downstream equipment (such as air preheaters), increasing maintenance costs. The present invention is proposed.

[0005] Therefore, the object of the present invention is to provide a denitration spray control system for a thermal power plant.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a denitration spray control system for a thermal power plant, comprising:

[0007] The SCR reactor and ammonia injection module are used to quickly respond to changes in unit load to avoid large fluctuations in NOx concentration and to quickly adjust the amount of ammonia injection to achieve NOx concentration control;

[0008] NOx monitoring module, providing real-time data of NOx concentration in outlet flue gas for precise control;

[0009] Oxygen monitoring module, providing data on oxygen content in inlet flue gas to assist in precise control;

[0010] Air volume monitoring module, which provides data on the total air volume of the boiler to assist in precise control; and

[0011] The control unit module makes precise adjustments based on the deviation between the actual measured value of NOx and the set value.

[0012] As a preferred solution of a denitration spray control system for a thermal power plant of the present invention, the SCR reactor is the main denitration equipment, which is equipped with a catalyst inside to reduce NOx into nitrogen and water. The catalyst inside is a substance that promotes the NOx reduction reaction and is usually composed of metals or metal oxides.

[0013] As a preferred solution of a denitrification spray control system for a thermal power plant of the present invention, the ammonia spray module includes an ammonia water storage tank for storing ammonia water for denitrification, and a conveying pipeline for conveying ammonia water from the storage tank to a nozzle, and the nozzle is a device for spraying ammonia water into the SCR reactor.

[0014] As a preferred solution of a denitrification spray control system for a thermal power plant of the present invention, the NOx detection module includes a NOx sensor for real-time monitoring of the NOx concentration in the flue gas, and a data acquisition system for collecting data from the NOx sensor and transmitting it to the control unit.

[0015] As a preferred solution of a denitrification spray control system for a thermal power plant of the present invention, the oxygen detection module includes an oxygen sensor for monitoring the oxygen content in the flue gas, and a data acquisition system for collecting data from the oxygen sensor and transmitting it to the control unit.

[0016] As a preferred solution of a denitrification spray control system for a thermal power plant of the present invention, the air volume detection module includes an air volume sensor for monitoring the total air volume of the boiler, and a data acquisition system for collecting data from the air volume sensor and transmitting it to the control unit.

[0017] As a preferred solution of a denitrification spray control system for a thermal power plant of the present invention, the control unit module includes a processor for executing a control algorithm and calculating the amount of ammonia sprayed according to input data, a memory for storing the control algorithm and historical data, a user interface for allowing an operator to monitor the system status and adjust parameters, and a communication interface for exchanging data with each monitoring module and the ammonia spray system.

[0018] As a preferred solution of a denitration spray control system for a thermal power plant of the present invention, the SCR reactor and the ammonia spray module also include a part of the control unit module for primary regulation, and the primary regulation is used to quickly respond to changes in unit load and quickly adjust the amount of ammonia spray, thereby achieving control of NOx concentration. The specific control algorithm is as follows:

[0019]

[0020] Among them, ΔNH 3 (1) is the amount of ammonia that needs to be adjusted for the first-stage regulation, ΔLoad is the change in unit load, ΔNOx is the change in NOx concentration, Δt is the time interval, and k 1 and k 2 is the coefficient.

[0021] As a preferred solution of a denitrification spray control system for a thermal power plant of the present invention, the NOx monitoring module, the oxygen monitoring module, the air volume monitoring module and the control unit module are two-level adjustments, and the two-level adjustment is used to accurately control the NOx concentration. The specific control algorithm is as follows:

[0022] ΔNH 3 (2) = k 3 ×(NOx set -NOx measured )+k 4 ×O 2 +k 5 ×ΔNH 3 (1)

[0023] Among them, ΔNH 3 (2) is the amount of ammonia that needs to be adjusted for secondary regulation, NOx set is the set NOx concentration, NOx measured is the actual measured NOx concentration, O 2 is the inlet oxygen content, k 3 , k 4 and k 5 is the coefficient of the secondary regulation, where k 5 In the control system, it is used to adjust the influence of the primary regulation output on the secondary regulation.

[0024] As a preferred solution of a denitration spray control system for a thermal power plant of the present invention, the control unit can switch from primary regulation to secondary regulation and perform from rapid regulation to precise regulation when the following conditions are met:

[0025] NOx measured ≤NOx limit ×C 1

[0026] NOx measured ≥NOxlimit ×C 2

[0027] Among them, NOx limit is the NOx emission limit required by environmental protection, C 1 is the maximum multiple of the NOx emission limit, C 2 The minimum multiple of the NOx emission limit;

[0028] When the actual measured NOx concentration is lower than or equal to the NOx emission limit required by environmental protection, 1 times, the system believes that the NOx concentration is within the acceptable upper limit. In this case, the system may switch from primary regulation to secondary regulation because the NOx concentration has approached or reached the environmental protection requirements and requires more precise control to maintain stability.

[0029] When the actual measured NOx concentration is higher than or equal to the NOx emission limit required by environmental protection, 2 times, the system considers that the NOx concentration is within the acceptable lower limit. In this case, the system may also switch from primary regulation to secondary regulation because the NOx concentration is low enough and does not require rapid and drastic adjustments of the primary regulation.

[0030] The beneficial effects of the present invention are as follows: the present invention can not only improve the accuracy and response speed of NOx control and optimize the use of reducing agents, but also enhance the stability and environmental performance of the system, improve the economic benefits and the market competitiveness of enterprises, and jointly constitute a continuous control process through the first-level regulation and the second-level regulation. The first-level regulation quickly responds to load changes, and the second-level regulation is fine-tuned on this basis to achieve more precise control. The first-level regulation provides initial conditions for the second-level regulation, and the second-level regulation is optimized on the basis of the first-level regulation. This coordination ensures that the system can remain stable and efficient throughout the entire operation process.

[0031] The detailed effects are as follows:

[0032] 1. Improve NOx control accuracy

[0033] Precise control: Secondary regulation can be precisely adjusted according to real-time NOx concentration data to ensure that NOx emissions are stable within the environmental protection requirements.

[0034] Fast response: The first-stage regulation can quickly respond to load changes, reduce fluctuations in NOx concentration, and improve the response speed of the system.

[0035] 2. Optimize the use of reducing agents

[0036] Reduce waste: By precisely controlling the amount of ammonia sprayed, the excessive use of ammonia water and the waste of reducing agent are reduced.

[0037] Cost saving: reduce the cost of reducing agent and improve economy.

[0038] 3. Enhance system stability and reliability

[0039] Reduce fluctuations: The control system can reduce the fluctuations of NOx emissions and improve the stability of the system.

[0040] Extend equipment life: Reduce equipment loss due to corrosion and blockage, and extend the service life of equipment.

[0041] 4. Improve environmental performance

[0042] Meeting regulations: Ensure that NOx emissions continue to meet increasingly stringent environmental regulations.

[0043] Reduce pollution: Reduce the impact of NOx emissions on the environment and reduce the formation of acid rain and photochemical smog.

[0044] 5. Improve economic benefits

[0045] Reduce fines: Avoid fines due to non-compliance with environmental emission standards.

[0046] Energy saving and consumption reduction: Optimize the denitrification process to reduce energy consumption and operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0048] Figure 1 The present invention is a schematic diagram of the overall structure of a denitration spray control system for a thermal power plant.

[0049] Figure 2 The present invention is a schematic flow diagram of a denitration spray control system for a thermal power plant. DETAILED DESCRIPTION

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0051] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0052] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0053] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0054] Example 1

[0055] Reference Figure 1 - Figure 2 , which is the first embodiment of the present invention, provides a denitrification spray control system for a thermal power plant. The system includes an SCR reactor and an ammonia spray module, which is used to quickly respond to changes in unit load to avoid large fluctuations in NOx concentration and to quickly adjust the amount of ammonia sprayed, thereby achieving control of NOx concentration.

[0056] Specifically, the SCR reactor is the main denitrification equipment, which is equipped with a catalyst inside to reduce NOx into nitrogen and water. The catalyst inside is a substance that promotes the NOx reduction reaction and is usually composed of metals or metal oxides.

[0057] Furthermore, the ammonia injection module includes an ammonia water storage tank for storing ammonia water for denitrification, and a delivery pipeline for delivering the ammonia water from the storage tank to a nozzle, which is a device for injecting ammonia water into the SCR reactor.

[0058] Furthermore, the SCR reactor and the ammonia injection module also include a part of the control unit module for the first-level regulation, which is used to quickly respond to changes in unit load and quickly adjust the amount of ammonia injection to achieve NOx concentration control. The specific control algorithm is as follows:

[0059]

[0060] Among them, ΔNH 3 (1) is the amount of ammonia that needs to be adjusted for the first-stage regulation, ΔLoad is the change in unit load, ΔNOx is the change in NOx concentration, Δt is the time interval, and k 1 and k 2 is the coefficient.

[0061] Furthermore, we should determine k 1 and k 2 Values:

[0062] Step 1: System Identification

[0063] Data collection: Operate the denitrification system under different operating conditions and collect data such as NOx concentration, ammonia injection amount, unit load, inlet oxygen amount and total boiler air volume.

[0064] Model building: Based on the collected data, a preliminary mathematical model is established to describe the relationship between NOx concentration and ammonia injection amount. This model can be linear or nonlinear, depending on the actual dynamics of the system.

[0065] Parameter estimation: Use least squares, maximum likelihood estimation, or other statistical methods to estimate preliminary k from the model. 1 and k 2 value.

[0066] Step 2: Optimize Technology

[0067] Define the objective function: Set a performance indicator, such as the control accuracy of NOx concentration, the efficiency of ammonia injection, or the response time of the system, as the objective function for optimization.

[0068] Optimization algorithm selection: Select a suitable optimization algorithm, such as genetic algorithm, particle swarm optimization (PSO), or gradient descent, to search for the optimal k 1 and k 2 value.

[0069] Optimization process: Use optimization algorithm to adjust k 1 and k 2 The value of and evaluates the objective function in each iteration. Record the k that makes the objective function reach the minimum or maximum value 1 and k 2 value.

[0070] Step 3: Experimental verification

[0071] Experimental design: Based on the optimization results, a series of experiments are designed to verify k 1 and k 2 actual effect.

[0072] Experimental execution: Applying the optimized k in the actual denitrification system 1 and k 2 values ​​and collect experimental data.

[0073] Result analysis: Analyze experimental data and evaluate k 1 and k 2 Check whether the actual effect meets expectations. If the effect is not satisfactory, return to step 2 for further optimization.

[0074] Step 4: Iterate and improve

[0075] Feedback adjustment: According to the experimental verification results, k 1 and k 2 Perform fine-tuning to improve system performance.

[0076] Iteration loop: Repeat steps 2 and 3 until a satisfactory k is found 1 and k 2 , so that the system performance is optimized.

[0077] Step 5: Implementation and Monitoring

[0078] System implementation: The final k 1 and k 2 The value is applied to the denitrification control system.

[0079] Performance monitoring: Continuously monitor system performance to ensure 1 and k 2 The values ​​are still valid under different working and environmental conditions.

[0080] Through the above steps, k can be systematically determined 1 and k 2 value, ensuring that the denitrification control system achieves optimal economy and operating efficiency while meeting environmental protection requirements.

[0081] The control unit receives the load change signal of the unit, and then the control unit quickly calculates the ammonia injection amount adjustment value according to the load change amount and change rate. Finally, the ammonia injection system adjusts the ammonia injection amount according to the instruction of the control unit.

[0082] Example 2

[0083] Reference Figure 1 - Figure 2 , which is the first embodiment of the present invention, provides a denitrification spray control system for a thermal power plant, the system includes a NOx monitoring module, which provides real-time data of NOx concentration in the outlet flue gas for precise control; an oxygen monitoring module, which provides data of oxygen content in the inlet flue gas to assist precise control; an air volume monitoring module, which provides data of the total air volume of the boiler to assist precise control; and a control unit module that performs precise adjustment according to the deviation between the actual measured value of NOx and the set value.

[0084] Specifically, the NOx detection module includes a NOx sensor for real-time monitoring of NOx concentration in flue gas, and a data acquisition system for collecting data from the NOx sensor and transmitting the data to the control unit.

[0085] Furthermore, the oxygen detection module includes an oxygen sensor for monitoring the oxygen content in the flue gas, and a data acquisition system for collecting data from the oxygen sensor and transmitting the data to the control unit.

[0086] Furthermore, the air volume detection module includes an air volume sensor for monitoring the total air volume of the boiler, and a data acquisition system for collecting data from the air volume sensor and transmitting it to the control unit.

[0087] Furthermore, the control unit module includes a processor for executing the control algorithm and calculating the ammonia injection amount based on the input data, a memory for storing the control algorithm and historical data, a user interface for allowing the operator to monitor the system status and adjust parameters, and a communication interface for exchanging data with each monitoring module and the ammonia injection system.

[0088] Furthermore, the control unit can switch from primary regulation to secondary regulation, from fast regulation to precise regulation, when the following conditions are met:

[0089] NOx measured ≤NOx limit ×C 1

[0090] NOx measured ≥NOx limit ×C 2

[0091] Among them, NOx limit is the NOx emission limit required by environmental protection, C 1 is the maximum multiple of the NOx emission limit, C 2 The minimum multiple of the NOx emission limit;

[0092] When the actual measured NOx concentration is lower than or equal to the NOx emission limit required by environmental protection, 1 times, the system believes that the NOx concentration is within the acceptable upper limit. In this case, the system may switch from primary regulation to secondary regulation because the NOx concentration has approached or reached the environmental protection requirements and requires more precise control to maintain stability.

[0093] When the actual measured NOx concentration is higher than or equal to the NOx emission limit required by environmental protection, 2 When the NOx concentration is less than 20%, the system considers that the NOx concentration is within the acceptable lower limit. In this case, the system may also switch from the first-level regulation to the second-level regulation because the NOx concentration is low enough and does not require rapid and drastic adjustments of the first-level regulation.

[0094] Furthermore, the NOx monitoring module, oxygen monitoring module, air volume monitoring module and control unit module are two-level adjustments, which are used to accurately control the NOx concentration. The specific control algorithm is as follows:

[0095] ΔNH 3 92) = k 3 ×(NOx set -NOxmeasured )+k 4 ×O 2 +k 5 ×ΔNH 3 (1)

[0096] Among them, ΔNH 3 (2) is the amount of ammonia that needs to be adjusted for secondary regulation, NOx set is the set NOx concentration, NOx measured is the actual measured NOx concentration, O 2 is the inlet oxygen content, k 3 , k 4 and k 5 is the coefficient of the secondary regulation, where k 5 In the control system, it is used to adjust the influence of the primary regulation output on the secondary regulation.

[0097] Among them, k 3 , k 4 and k 5 The coefficient of the secondary regulation can be determined by 1 and k 2 This can save time and resources while ensuring accuracy and consistency.

[0098] Among them, the data of the NOx monitoring module, the oxygen monitoring module and the air volume monitoring module are received by the control unit. The control unit calculates the precise adjustment value of the ammonia injection amount according to the deviation between the actual measured value and the set value of NOx, as well as the inlet oxygen content and the total air volume of the boiler. The ammonia injection system further adjusts the ammonia injection amount according to the precise adjustment instructions of the control unit.

[0099] The data collected by the monitoring module flows to the control unit module, which processes the data and outputs control signals to the ammonia injection module. The control unit module dynamically adjusts the ammonia injection amount according to the monitoring data and the preset control strategy to achieve precise control of NOx concentration. By monitoring the denitration effect through NOx, a closed-loop control is formed to ensure stable operation of the system and achieve the expected denitration effect.

[0100] The primary regulation and the secondary regulation together constitute a continuous control process. The primary regulation responds quickly to load changes, and the secondary regulation makes fine adjustments on this basis to achieve more precise control. The primary regulation provides initial conditions for the secondary regulation, and the secondary regulation is optimized based on the primary regulation. This coordination ensures that the system remains stable and efficient throughout the entire operation process.

[0101] Example 3

[0102] Reference Figure 1 - Figure 2, which is the first embodiment of the present invention, provides a denitration spray control system for a thermal power plant. This system is different from the previous two embodiments. This embodiment ensures that the first-level regulation can smoothly transition to the second-level regulation, and the second-level regulation can meet environmental protection requirements, including the following contents:

[0103] 1. The primary regulation is mainly to quickly respond to changes in unit load and avoid large fluctuations in NOx concentration. After the primary regulation, we need to ensure that the NOx concentration has stabilized within a certain range before entering the secondary regulation. This range can be set to ±10% of the NOx emission limit required by environmental protection.

[0104] Conditional formula:

[0105] NOx limit ×0.9≤NOxT≤NOx limit ×1.1

[0106] Among them, NOxT is the actual measured NOx value, NOx limit It is the NOx emission limit required by environmental protection.

[0107] 2. Secondary regulation meets the environmental protection requirements

[0108] The purpose of secondary regulation is to accurately control NOx emissions to meet environmental protection requirements. Therefore, secondary regulation needs to ensure that the NOx concentration is stable within the limit required by environmental protection.

[0109] Conditional formula:

[0110] NOxT≤NOxlimit

[0111] Among them, NOxT is the actual measured NOx value, NOx limit It is the NOx emission limit required by environmental protection;

[0112] To ensure a smooth transition of NOx concentration from primary regulation to secondary regulation, the following adjustments can be made: To ensure a smooth transition of NOx concentration.

[0113] Conditional formula:

[0114]

[0115] Among them, k 6 is the smoothing factor. Through a series of experiments and adjustments, by observing the system's response to different smoothing factor values, a value that makes the system respond most smoothly can be selected.

[0116] The following adjustments can be made in the secondary regulation to ensure accurate control of NOx concentration.

[0117] Conditional formula:

[0118] ΔNH 3 (2) = k 3 ×(NOx set -NOx measured )+k 4 ×O 2 +k 5 ×ΔNH 3 (1)+k 7 ×NOx feedback

[0119] where k 7 is the feedback control coefficient, NOx set is the set NOx concentration, NOx measured is the actual measured NOx concentration, O 2 is the inlet oxygen content, NOx feedback It is the feedback value of NOx concentration.

[0120] Among them, the coefficient can be dynamically adjusted according to the actual operation data of the system, the conditional formula is:

[0121] f(NOx measured , NOx set , O 2 , Load)

[0122] Among them, f is the adaptive control function, and Load is the amount of unit load.

[0123] Through this, we can determine the adaptive control function f, so that it can dynamically adjust the coefficient according to the actual operating data of the system, thereby improving the performance and adaptability of the denitrification control system. It can also ensure that the first-level regulation and the second-level regulation can have a smooth transition to maintain the NOx emission concentration near the set value, minimize the use of ammonia injection and improve the response speed and stability of the system, and the second-level regulation can meet environmental protection requirements.

[0124] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, as well as parameter values, mounting arrangements, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, improvements, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0125] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A denitrification spray control system for a thermal power plant, characterized in that: include, The SCR reactor and ammonia injection module are used to quickly respond to changes in unit load to avoid large fluctuations in NOx concentration and to quickly adjust the amount of ammonia injection to achieve NOx concentration control; NOx monitoring module, providing real-time data of NOx concentration in outlet flue gas for precise control; Oxygen monitoring module, providing data on oxygen content in inlet flue gas to assist in precise control; Air volume monitoring module, which provides data on the total air volume of the boiler to assist in precise control; as well as, The control unit module makes precise adjustments based on the deviation between the actual measured value of NOx and the set value.

2. The denitration spray control system for a thermal power plant according to claim 1, characterized in that: The SCR reactor is the main denitrification equipment, which is equipped with a catalyst to reduce NOx into nitrogen and water. It contains a catalyst, a substance that promotes the NOx reduction reaction, usually composed of metals or metal oxides.

3. The denitration spray control system for a thermal power plant according to claim 2 is characterized in that: The ammonia injection module includes an ammonia storage tank for storing ammonia for denitrification, and a delivery pipeline for delivering ammonia from the storage tank to a nozzle, which is a device for injecting ammonia into the SCR reactor.

4. The denitration spray control system for a thermal power plant according to claim 3 is characterized in that: The NOx detection module includes a NOx sensor for real-time monitoring of the NOx concentration in the flue gas, and a data acquisition system for collecting data from the NOx sensor and transmitting it to the control unit.

5. The denitration spray control system for a thermal power plant according to claim 4, characterized in that: The oxygen detection module includes an oxygen sensor for monitoring the oxygen content in the flue gas, and a data acquisition system for collecting data from the oxygen sensor and transmitting it to the control unit.

6. The denitration spray control system for a thermal power plant according to claim 5, characterized in that: The air volume detection module includes an air volume sensor for monitoring the total air volume of the boiler, and a data acquisition system for collecting data from the air volume sensor and transmitting it to the control unit.

7. The denitration spray control system for a thermal power plant according to claim 6, characterized in that: The control unit module includes a processor for executing the control algorithm and calculating the ammonia injection amount based on the input data, a memory for storing the control algorithm and historical data, a user interface for allowing the operator to monitor the system status and adjust parameters, and a communication interface for exchanging data with each monitoring module and the ammonia injection system.

8. The denitration spray control system for a thermal power plant according to claim 7, characterized in that: The SCR reactor and ammonia injection module also include some control unit modules for the first-level regulation, which is used to quickly respond to changes in unit load and quickly adjust the amount of ammonia injection to achieve NOx concentration control. The specific control algorithm is as follows: Where ΔNH3(1) is the amount of ammonia that needs to be adjusted for the first-stage regulation, ΔLoad is the change in unit load, ΔNOx is the change in NOx concentration, Δt is the time interval, and k1 and k2 are coefficients.

9. The denitration spray control system for a thermal power plant according to claim 8, characterized in that: The NOx monitoring module, oxygen monitoring module, air volume monitoring module and control unit module are two-level adjustments, which are used to accurately control the NOx concentration. The specific control algorithm is as follows: ΔNH3(2)=k3×(NOx set -NOx measured )+k4×O2+k5×ΔNH3(1) Among them, ΔNH3(2) is the amount of ammonia that needs to be adjusted for the secondary regulation, and NOx set is the set NOx concentration, NOx measured is the actual measured NOx concentration, O2 is the inlet oxygen content, k3, k4 and k5 are the coefficients of the secondary regulation, among which k5 is used in the control system to adjust the influence of the primary regulation output on the secondary regulation.

10. The denitration spray control system for a thermal power plant according to claim 9, characterized in that: The control unit can switch from primary regulation to secondary regulation, from fast regulation to precise regulation, when the following conditions are met: NOx measured ≤NOx limit ×C1 NOx measured ≥NOx limit ×C2 Among them, NOx limit It is the NOx emission limit required by environmental protection, C1 is the maximum multiple of the NOx emission limit, and C2 is the minimum multiple of the NOx emission limit; When the actual measured NOx concentration is lower than or equal to C1 times the NOx emission limit required by environmental protection, the system considers that the NOx concentration is within the acceptable upper limit. In this case, the system may switch from primary regulation to secondary regulation because the NOx concentration has approached or reached the environmental protection requirement and requires more precise control to maintain stability. When the actual measured NOx concentration is higher than or equal to C2 times the NOx emission limit required by environmental protection, the system considers that the NOx concentration is within the acceptable lower limit. In this case, the system may also switch from primary regulation to secondary regulation because the NOx concentration is low enough and does not require rapid and drastic adjustments of primary regulation.

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