An industrial boiler SNCR denitrification control system and control method

Abstract

The present invention discloses a control system and method for SNCR denitrification of industrial boilers. The system comprises an execution layer, a perception layer, a conversion layer, a control layer, and a management layer. The perception layer includes a flue gas volume dynamic measurement module for collecting first information on the NO and O2 content within the furnace. The conversion layer is configured to obtain NOx concentration based on the first content information and calculate second information on the NH3 content based on the NOx concentration. The control layer is configured to generate control instructions based on the second content information and control the operating states of the spray gun, air compressor, and ammonia injection regulating valve according to the control instructions, so that the spray gun injects a reducing agent into the furnace. The present invention monitors the nitrogen oxide content within the furnace in real time and then controls the amount of reducing agent based on the nitrogen oxide content, thereby avoiding insufficient or wasted reducing agent, improving control stability and quality, and achieving intelligent control. The system can be widely applied in the field of flue gas denitrification technology.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial automation control and flue gas denitration, and in particular to an industrial boiler SNCR denitration control system and a control method. Background Art

[0002] With my country's accelerating urbanization, according to the 2019 China Statistical Yearbook, 228 million tons of domestic waste were collected and transported in 2018. 1,091 harmless treatment plants handled 226 million tons, including 331 incineration plants, which processed 102 million tons. Urban waste generation is growing at a rate of approximately 10%, with growth rates exceeding 15% in Beijing, Shanghai, Shenzhen, and Guangzhou. The introduction of urban waste sorting and the implementation of "Zero Waste City" initiatives are further promoting the principles of harmless, volume-reducing, and resource-based waste treatment. Incineration is currently one of the most relevant technologies for waste management, capable of reducing the weight of solid waste by 80% and the volume by over 90%. It has been widely promoted and applied in large and medium-sized cities. However, due to the relatively complex combustion process and technology of waste incinerators, and the large differences in performance parameters such as the calorific value and industrial elements of the fuel, the existing combustion process control system and flue gas treatment system are difficult to meet the requirements of stable and harmless incineration of waste. Exploring process control technologies and methods that can ensure stable combustion and coordinated and efficient denitrification is one of the key contents of studying waste incineration technology.

[0003] The Selective Non-Catalytic Reduction (SNCR) system is a post-combustion flue gas denitrification technology that removes NOx through a chemical reaction process by injecting an appropriate amount of reducing agent into appropriate locations within thermal power generation boilers, waste incinerators, cement kilns, or other industrial boilers. SNCR denitrification equipment typically uses a reductant of a defined concentration, stored in liquid form in tanks and transported by tank trucks. This reductant is then distributed to each spray gun via a metering module and injected into the furnace, where it selectively reacts with NOx without the use of a catalyst. Unlike the SCR process, fuel types such as coal, biomass, and waste have minimal impact on SNCR performance.

[0004] Currently, most SNCR denitrification systems utilize the Foxboro IA DCS system for distributed control. Its automated control schemes include fixed-flow dosing and boiler load calculation. Manual switching is performed under different operating conditions, but actual use has shown that these two methods cannot achieve stable control of nitrogen oxides. They can only rely on excessive dosing of urea or ammonia solution, which causes ammonia slip, corrosion to the equipment, and waste of reducing agent. Existing SNCR denitrification systems suffer from poor system integration, a single reducing agent ratio that cannot be automatically adjusted or has poor adjustability, low levels of intelligent control, and poor overall system planning. Summary of the Invention

[0005] In order to solve one of the above technical problems, the purpose of the present invention is to provide an industrial boiler SNCR denitrification control system and control method, which collects the nitrogen oxide content in the furnace in real time and adjusts the injection amount of the reducing agent according to the collected parameters to achieve intelligent monitoring.

[0006] A technical solution adopted by the present invention is:

[0007] An industrial boiler SNCR denitrification control system includes an execution layer, a perception layer, a conversion layer, a control layer and a management layer;

[0008] The execution layer includes a spray gun, an air compressor and an ammonia spray regulating valve;

[0009] The sensing layer includes a flue gas volume dynamic measurement module, which is used to collect first content information of NO and O2 in the furnace;

[0010] The conversion layer is used to obtain the NOx concentration according to the first content information and calculate the second NH3 content information according to the NOx concentration;

[0011] The control layer is used to generate a control instruction according to the second content information, and control the working state of the spray gun, the air compressor and the ammonia injection regulating valve according to the control instruction, so that the spray gun sprays the reducing agent into the furnace;

[0012] The management layer is used to store control instructions to generate operation history data.

[0013] Furthermore, the NOx concentration is calculated using the following formula:

[0014]

[0015] Furthermore, the sensing layer also includes a pressure measurement module, a temperature detection module, a limit control denitrification module, a multi-component gas analyzer, and a CEMS detector;

[0016] The pressure measurement module is arranged at the primary air inlet, secondary air inlet and flue gas outlet of the furnace, and is used to measure the change in flue gas volume and flue gas flow velocity parameters;

[0017] The temperature detection module includes a plurality of wireless temperature detection sensor arrays, which are arranged in three layers between the secondary air inlet of the furnace and the first flue interface of the furnace to measure the temperature distribution in the furnace;

[0018] The limit control denitration module is arranged at the first flue outlet of the furnace or at the inlet of the SCR denitration device, and is used to measure the content of nitrogen oxides in the flue gas;

[0019] The multi-component gas analyzer is used to collect the nitrogen oxide concentration, oxygen content and sulfide content in the flue of the furnace. The sampling components of the multi-component gas analyzer are arranged on both sides of the furnace and between the secondary air inlet and the spray gun;

[0020] The dynamic measurement module for flue gas volume includes a flow meter, a temperature sensor, and a pressure sensor. The collection point of the dynamic measurement module for flue gas volume is set between the secondary air inlet and the first flue inlet of the furnace;

[0021] The CEMS detector is arranged at the first flue inlet and the flue gas outlet of the furnace, and is used to measure the raw material physical properties and pollutant emission parameters of the flue gas.

[0022] Furthermore, the wireless temperature detection sensor array is composed of a plurality of wireless temperature sensor nodes, which are used to collect the temperature information of the furnace and send the temperature information through LoRa or NB-IoT communication.

[0023] Furthermore, the conversion layer includes a reducing agent dosage calculation module, a flue gas volume correction module, and an ammonia escape processing module;

[0024] The smoke volume correction module is used to calibrate and correct the first content information collected by the smoke volume dynamic measurement module;

[0025] The reducing dose calculation module is provided with a reducing dose calculation model and an optimal ammonia nitrogen ratio, and is used to obtain the NOx concentration based on the first content information, and calculate the second NH3 content information in combination with the NOx concentration reducing dose calculation model and the optimal ammonia nitrogen ratio;

[0026] The ammonia escape processing module is used to detect NH3 that does not participate in the reduction reaction, the volume ratio of the total flue gas, and the size of the reducing agent particles.

[0027] Furthermore, the ammonia escape processing module detects the reducing agent particle size by the following method:

[0028] Based on the principle of digital holographic measurement, the reducing agent sprayed from the spray gun is sampled and the particle size of the reducing agent is obtained by combining the scalar diffraction theory.

[0029] Furthermore, the execution layer also includes an electromagnetic flowmeter, which is installed on the delivery pipeline of the spray gun and the compressed air pipeline of the air compressor. The control layer includes an operation load adjustment module, a reducing dosage control module, and a working temperature field numerical simulation module;

[0030] The operation load adjustment module is used to adjust the flue gas, fuel and steam in the furnace;

[0031] The reducing dosage control module is used to control the electromagnetic flowmeter, the size and angle of the spray gun nozzle, and the air compressor;

[0032] The operating temperature field numerical simulation module is used to perform process simulation according to the operating parameters of the furnace, providing a calculation data basis for the control of the reducing agent.

[0033] Furthermore, the electromagnetic flowmeter has a remote wireless transmission and receiving function, and configures the ratio of the reducing agent according to the instructions of the reducing agent dosage control module.

[0034] Furthermore, the management layer includes an operation history database, a numerical calculation database and a process visualization module;

[0035] The operation history database stores the operation data of the furnace and the operation history data of furnaces of the same type, and shares data with the numerical calculation database and the process visualization module;

[0036] The numerical calculation database stores simulation data of the same type of furnaces and numerical simulation data of the operating temperature field, and outputs the stored data to the visualization module for comparison and analysis with the operation history data, or with the data collected by the perception layer;

[0037] The process visualization module includes a data processing microcomputer system and an LED display screen.

[0038] Another technical solution adopted in the present invention is:

[0039] An industrial boiler SNCR denitrification control method comprises the following steps:

[0040] Collecting first content information of NO and O2 in the furnace;

[0041] Obtaining a NOx concentration based on the first content information, and calculating second NH3 content information based on the NOx concentration;

[0042] A control instruction is generated according to the second content information, and the working states of the spray gun, the air compressor and the ammonia injection regulating valve are controlled according to the control instruction so that the spray gun sprays the reducing agent into the furnace.

[0043] The beneficial effects of the present invention are as follows: the present invention monitors the content of nitrogen oxides in the furnace in real time, and then controls the amount of reducing agent according to the content of nitrogen oxides, thereby avoiding insufficient or wasted reducing agent, improving the stability and quality of control, and realizing intelligent control. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a structural block diagram of an industrial boiler SNCR denitrification control system according to an embodiment of the present invention;

[0045] Figure 2This is a schematic diagram of the association of various modules of an industrial boiler SNCR denitrification control system according to an embodiment of the present invention;

[0046] Figure 3 2 is a schematic structural diagram of a furnace in an embodiment of the present invention;

[0047] Figure 4 This is a communication diagram of an industrial boiler SNCR denitrification control system equipment in an embodiment of the present invention;

[0048] Figure 5 is a flow chart of a method for controlling according to limit indicators in an embodiment of the present invention;

[0049] Figure 6 This is a flowchart of the steps of an industrial boiler SNCR denitrification control method according to an embodiment of the present invention;

[0050] Figure 3 Reference numerals: 1, primary air inlet; 2, first flue inlet; 3, secondary air inlet; 4, first flue outlet; 5, flue gas outlet; 6, spray gun. DETAILED DESCRIPTION

[0051] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0052] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0053] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0054] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0055] like Figure 1 and Figure 2 As shown, this embodiment provides an industrial boiler SNCR denitrification control system, including an execution layer, a perception layer, a conversion layer, a control layer, and a management layer;

[0056] The execution layer includes an ammonia injection regulating valve, an electromagnetic flowmeter, a spray gun, and an air compressor. The data basis for its judgment and execution mainly comes from the reducing dosage control module in the control layer.

[0057] The perception layer includes a pressure measurement module, a temperature detection module, a limit control denitrification module, a multi-component gas analyzer, a flue gas volume dynamic measurement module, and a CEMS detector. The output data will serve as the data basis for the reduction dose calculation module in the conversion layer.

[0058] The conversion layer includes a reducing dose calculation module, a flue gas volume correction module, and an ammonia escape processing module. The calculation data basis mainly comes from the perception layer, and the output data will serve as the calculation basis for the reducing dose control module.

[0059] The control layer includes an operating load adjustment module, a reducing dosage control module, and an operating temperature field numerical simulation module. Its calculation data is based on the perception layer and the conversion layer and is combined with the instructions of the management layer to generate new instructions to act on the execution layer and form historical data at the management layer.

[0060] The management layer includes operation history data, numerical calculation database and process visualization module; data between modules are interconnected, and feedback data comes from the control layer.

[0061] Reference Figure 3 As an optional real-time method, in the perception layer, the pressure measurement module is set at the fuel, the primary air inlet 1 in the furnace, the secondary air inlet 3 execution layer and the flue gas outlet 5, for measuring the flue gas volume and the change in the flue gas flow velocity parameters.

[0062] The temperature detection module includes a plurality of wireless temperature detection sensor arrays, which are arranged in three layers between the furnace secondary air inlet 3 and the first flue outlet 4 to measure the temperature distribution in the furnace. Figure 4 The wireless temperature detection sensor array is composed of multiple wireless temperature sensor nodes, which are arranged around the incinerator to collect the furnace temperature and calculate the spatial distribution of the furnace temperature through weighted average calculation. The data is input into the working condition temperature field numerical simulation module as the basic working condition data, combined with the historical operation data to form the furnace temperature field distribution data; the furnace temperature field distribution data is used as the basic data for the operation load adjustment module and the reducing dosage control module; the wireless temperature sensor nodes are connected via LoRa or NB-IoT, and can be expanded to multiple nodes and compatible with other similar devices in the system.

[0063] The limit control denitrification module is arranged at the first flue outlet 4 or the inlet of the SCR denitrification device, and is used to detect whether the nitrogen oxides in the flue gas meet the standards and adjust the limit according to the emission standards.

[0064] The multi-component gas analyzer collects the nitrogen oxide concentration, oxygen content, and sulfide content in the flue. The sampling components are arranged on both sides of the furnace and are located between the secondary air inlet 3 and the spray gun 6. Specifically, the spray gun is provided with three layers of nozzles, namely the first layer of nozzles, the second layer of nozzles, and the third layer of nozzles, which are distributed in sequence in the longitudinal position. Among them, the first layer of nozzles is located at the top, closest to the first flue port 4; the second layer of nozzles is in the middle; the third layer of nozzles is at the bottom, closest to the secondary air inlet 3. The multi-component gas analyzer is located between the secondary air inlet 3 and the third layer of nozzles.

[0065] The dynamic measurement module for flue gas volume includes a flow meter, a temperature sensor and a pressure sensor, and the collection point is set between the secondary air inlet 3 and the first flue inlet 4; the NO and O2 contents are collected, and the flue gas volume output by the dynamic measurement module for flue gas volume is used as the basis for calculating the amount of reduced gas sprayed.

[0066] The CEMS detector includes modules for online monitoring of gaseous pollutants such as SO2, NOx, CO, CO2, and O2, as well as solid pollutants, as well as temperature, pressure, humidity, and flow. It collects and processes exhaust gas data and generates maps. It is installed at the first flue inlet 2 and the flue gas outlet 5 to measure the raw material physical properties of the flue gas and pollutant emission parameters.

[0067] As an optional real-time method, in the conversion layer, the reducing dose calculation module includes a reducing dose calculation model, an optimal ammonia nitrogen ratio, and the content of other components, and is calculated according to the NOx concentration in the flue gas: Determine the NH3 content and the quality of the reducing agent; the output data serves as the basis for the reducing agent dosage control module of the control layer;

[0068] The flue gas volume correction module includes a method for calculating the flue gas flow rate through the flow rate, pressure and temperature signals of the measured working medium through classical heat balance calculation and performing regular calibration and correction; the flue gas volume output by the flue gas volume correction module is used as the basis for calculating the ammonia injection amount;

[0069] The ammonia escape processing module is used to detect the volume percentage of NH3 that does not participate in the reduction reaction, the total amount of flue gas, and the size of the reducing agent particle size, and its output data serves as the calculation basis for the reducing agent dosage control module. The ammonia escape processing module has two sampling points, one is set at the spray gun (first sampling point), and the other is set at the first flue outlet (second sampling point); the reducing agent particle size is detected through the first sampling point; the volume percentage of NH3 that does not participate in the reduction reaction and the total amount of flue gas is detected through the second sampling point. Specifically, the ammonia escape processing module is used to process the measurement and comparison of the NH3 content at the flue gas outlet. If the NH3 content exceeds the standard, partial flue gas reflux combustion will be selected; the specific proportion is determined according to the online real-time simulation data.

[0070] As an optional real-time method, the ammonia escape processing module detects the reducing agent particle size in the following manner: adopting the digital holographic measurement principle, based on scalar diffraction theory, and reconstructing the virtual image according to the scalar diffraction theory and the wavelet transform algorithm, the reducing agent particle size is detected online.

[0071] The reducing agent is pressurized with air and then sprayed into the furnace in the form of droplets. The size of the particle size is mainly related to its evaporation time. Small particles evaporate quickly, which may cause the reducing agent to evaporate and convert into NH3 to react with NOx as soon as it enters the furnace. Excess NH3 or NH3 that does not have time to react will flow away with the flue gas, missing the suitable temperature window for SNCR, which will also lead to an increase in ammonia slip. Therefore, the control of particle size is also particularly important. It needs to be coordinated with the injection speed so that the droplets can reach the center of the flue and evaporate and react, and the reducing agent can be distributed as evenly as possible in the flue. Therefore, in this embodiment, the reducing agent particle size is detected online by the ammonia slip processing module and fed back to the control layer.

[0072] The ammonia slip treatment module measures the NH3 content at the flue gas outlet to determine whether the added reducing agent flow rate is too high or too low. To improve denitrification effectiveness, practical applications and experimental results have shown that the NSR (ammonia-nitrogen ratio) should be between 1-2 as a reasonable range, and 1.5-1.6 as an optimal range. This means that even after the reducing agent and NOx react 100% completely, some residual reducing agent will still be converted into NH3 and discharged from the flue gas. Due to changes in operating parameters and the ever-changing combustion conditions in the furnace, the NOx content generated in the flue gas is constantly changing. Changes in the temperature and flow fields also affect the denitrification effect. Therefore, a fixed reducing agent addition rate is clearly inefficient. Based on the amount of ammonia slip in the flue gas outlet, it is possible to dynamically determine whether the current reducing agent addition rate is consistent with the amount of NOx generated in the furnace. Dynamic real-time adjustment can be made, adjusting the amount by increasing or decreasing the amount, thereby ensuring that flue gas emissions meet emission standards.

[0073] Among them, the digital holographic measurement principle is:

[0074] The numerical reconstruction of holograms is based on the scalar diffraction theory. According to the scalar diffraction theory, the object light wave O(x, y) can be expressed in the following complex form:

[0075] O(x,y)=o(x,y)exp(iφo(x,y)) (1)

[0076] In formula (1), the real part o(x, y) contains the light intensity information, and the imaginary part exp(iφo(x, y)) contains the phase information. Similarly, the complex number expression of the reference light R(x, y) is:

[0077] R(x,y)=r(x,y)exp(iφR(x,y)) (2)

[0078] The object light and the reference light interfere with each other on the holographic recording plane, and the formula for calculating the intensity of the interference light is:

[0079] I(x,y)=|O(x,y)+R(x,y)|2=(O(x,y)+R(x,y))(O(x,y)+R(x,y))*=R(x,y)R*(x,y)+

[0080] O(x,y)O*(x,y)+O(x,y)R*(x,y)+R(x,y)O*(x,y) (3)

[0081] In formula (3), * represents a conjugate complex number. The amplitude transfer function h(x, y) on the recording plane can be expressed as:

[0082] h(x,y)=h0+βτI(x,y) (4)

[0083] In equation (4), β is a constant term; τ is the exposure time; and h0 is the amplitude transfer function of the unexposed plane, which can be ignored in digital holography. h(x, y) is also called the holographic function.

[0084] Multiplying the holographic function by the complex reference light function gives the functional expression for holographic reconstruction:

[0085] R(x,y)h(x,y)=[h0+βτ(r2+O2)]R(x,y)+βτr2O(x,y)+βτR2(x,y)O*(x,y) (5)

[0086] In equation (5), the first term on the right side of the equal sign is the reference light multiplied by a factor, becoming a DC term, representing the light that passes through the hologram without diffraction; the second term is the reconstructed object light wave, forming a virtual image, and the factor βτr2 only affects the brightness of the image; the third term produces a distorted real image.

[0087] Based on the above principles, sampling ports are installed at high locations such as the reducing agent nozzle, and online testing is performed to detect the reducing agent particle size. Currently, the best results are in the range of 20 to 100 microns, but appropriate adjustments are required based on the results of elemental analysis of the fuel.

[0088] As an optional real-time method, in the control layer, the operating load regulation module includes a flue gas regulation system, a fuel regulation system and a steam regulation system, wherein the main parameters of the flue gas regulation system, the fuel regulation system and the steam regulation system are adjusted according to the operation history data, the numerical calculation database and the grid connection indicators, and the data are used as the calculation basis of the reducing dosage control module.

[0089] Reference Figure 4 The reducing agent dosage control module includes electromagnetic flowmeter control, spray gun nozzle size and angle control, and air compressor control. The electromagnetic flowmeter is installed on the reducing agent delivery pipeline and the compressed air pipeline, and has a remote wireless data transmission function and communicates with the control module through a LoRa gateway or NB-IoT. The spray gun can spray in a 135° conical shape and the nozzle can be adjusted according to the working conditions. The working conditions of the air compressor are adjusted according to the quality, flow rate and particle size of the sprayed reducing agent. The output gas is mixed with the reducing agent at the spray gun.

[0090] Reference Figure 4 The electromagnetic flowmeter has a remote wireless transmission and reception function, and configures the ratio of the reducing agent according to the instructions of the reducing agent dosage control module to achieve the preset parameter target; the electromagnetic flowmeter is connected through a LoRa gateway or NB-IoT base station, and can be expanded to multiple nodes and compatible with other similar devices in the system. The electromagnetic flowmeter updates the amount of reducing agent added based on the feedback information from the ammonia escape treatment module. The amount of compressed air added and the amount of reducing agent added are converted through a certain functional relationship. It is necessary to consider the reducing agent flow rate and particle size, and the required injection speed to adjust the compressed air pressure. The electromagnetic flowmeter mainly controls the ratio of reducing agent and compressed air through flow rate and time.

[0091] The operating temperature field numerical simulation module includes Flic and Fluent online simulation programs, which perform process simulation based on actual operating parameters. Its data is used for load adjustment prediction, verification and prediction of detection results of pressure measurement module and temperature detection module, and provides calculation data basis for reducing dosage control.

[0092] As an optional real-time method, in the management layer, the operation history database includes the operation data of the waste incinerator body and the operation history data of similar furnace types, and shares data with the numerical calculation database and the process visualization module.

[0093] The numerical calculation database includes simulation data of similar waste incinerators and numerical simulation data of operating temperature fields, which are output to the visualization module for comparative analysis with operation history data and test data of various devices in the perception layer.

[0094] The process visualization module includes a data processing microcomputer system and an LED display screen, and a dynamic display diagram of the position and function of each device in the SNCR denitrification system, which can perform data transmission operations.

[0095] In summary, the SNCR denitrification control system for a waste incinerator of this embodiment has at least the following beneficial effects compared to existing control systems:

[0096] (1) It can intelligently adjust and compare operating conditions with online simulation results and historical operating data in real time, predict the combustion characteristics of the incinerator and the nitrogen oxides in the flue gas, and reduce NOx emissions. It can also control the quality of the reducing agent and the ratio of compressed air, improve the denitrification efficiency, reduce ammonia escape, and thus reduce or avoid equipment corrosion caused by ammonia escape, while saving reducing agent and reducing production costs.

[0097] (2) To meet the requirements for harmful flue gas emissions caused by incomplete combustion due to different load conditions and different fuel calorific values. In the actual incinerator production process, the instability of the working conditions and fuel has a significant impact on the combustion characteristics and temperature field of the furnace. Maintaining a stable denitrification efficiency is a key factor in ensuring that flue gas emissions meet national standards. Compared with the existing DSC control, this design is more accurate, has a faster response speed, and is more efficient.

[0098] (3) Reduce labor intensity and reduce the emission of harmful gases during equipment maintenance and modification. Each device uses long-range wireless communication, which is easy to install, maintain, remotely control and upgrade online, and has strong timeliness.

[0099] like Figure 6 As shown, this embodiment also provides an industrial boiler SNCR denitrification control method, comprising the following steps:

[0100] S1, collecting first content information of NO and O2 in the furnace;

[0101] S2. Obtaining a NOx concentration based on the first content information, and calculating second NH3 content information based on the NOx concentration;

[0102] S3. Generate a control instruction according to the second content information, and control the working states of the spray gun, the air compressor, and the ammonia injection regulating valve according to the control instruction, so that the spray gun sprays the reducing agent into the furnace.

[0103] Reference Figure 5The limit-controlled denitrification module collects nitrogen oxides in the flue gas, and the detected data includes but is not limited to: NOX concentration, ammonia slip concentration, denitrification efficiency, flue gas denitrification system resistance, flue gas temperature drop, O2 concentration, etc. It is determined whether the concentration of nitrogen oxides is greater than the index value based on the limit index. If it is, the NH3 content needs to be adjusted. The reducing dosage calculation module calculates the NH3 content, and then controls the execution layer to output more NH3 through the reducing dosage control module. The limit-controlled denitrification module collects the nitrogen oxide content in the flue gas and is connected to the ammonia slip processing module; the ammonia slip processing module evaluates and processes the data collected by the limit-controlled denitrification module. If the collected result shows that the ammonia slip is greater than the set limit value, the ammonia slip processing module transmits the instruction to the reducing dosage control module of the control layer for feedback, and directly performs secondary denitrification treatment to reduce the amount of ammonia slip.

[0104] Among them, the restriction indicators can be the indicators set in relevant standards such as GB / T 16157 "Sampling of particulate matter and gaseous pollutants in exhaust gases from stationary pollution sources", HJ / T 42 "Determination of nitrogen oxides in exhaust gases from stationary pollution sources - Ultraviolet spectrophotometry", GB / T 18204.25-2000 "Determination of ammonia in air in public places" or HJ 693-2014 "Determination of nitrogen oxides in exhaust gases from stationary pollution sources - Constant potential electrolysis method".

[0105] The industrial boiler SNCR denitration control method of this embodiment has a one-to-one correspondence with the industrial boiler SNCR denitration control system provided in the above embodiment, and has the corresponding functions and beneficial effects of the system.

[0106] It is understood that all or some steps, systems in the disclosed method above can be implemented as software, firmware, hardware and appropriate combinations thereof. Some physical components or all physical components can be implemented as software by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application specific integrated circuit. Such software can be distributed on a computer-readable medium, and the computer-readable medium can include computer storage media (or non-transitory media) and communication media (or temporary media). As known to those of ordinary skill in the art, the term computer storage medium is included in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data) and is volatile and non-volatile, removable and non-removable media. Computer storage media includes but is not limited to RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassette, magnetic tape, disk storage or other magnetic storage device, or can be used to store desired information and any other medium that can be accessed by a computer. Furthermore, as is well known to those skilled in the art, communication media typically embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0107] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the spirit of the present invention.

Claims

1. An industrial boiler SNCR denitrification control system, characterized in that: Includes execution layer, perception layer, conversion layer, control layer and management layer; The execution layer includes a spray gun, an air compressor and an ammonia spray regulating valve; The sensing layer includes a flue gas volume dynamic measurement module, which is used to collect first content information of NO and O2 in the furnace; The conversion layer is used to obtain the NOx concentration according to the first content information and calculate the second NH3 content information according to the NOx concentration; The control layer is used to generate a control instruction according to the second content information, and control the working state of the spray gun, the air compressor and the ammonia injection regulating valve according to the control instruction, so that the spray gun sprays the reducing agent into the furnace; The management layer is used to store control instructions to generate operation history data; The conversion layer includes a reducing agent calculation module, a flue gas volume correction module, and an ammonia escape processing module; The smoke volume correction module is used to calibrate and correct the first content information collected by the smoke volume dynamic measurement module; The flue gas volume output by the flue gas volume correction module is used as the basis for calculating the ammonia injection volume; The reducing dose calculation module is provided with a reducing dose calculation model and an optimal ammonia nitrogen ratio, and is used to obtain the NOx concentration based on the first content information, and calculate the second NH3 content information in combination with the NOx concentration reducing dose calculation model and the optimal ammonia nitrogen ratio; the NOx concentration is calculated using the following formula: The ammonia escape treatment module is used to detect the NH3 that does not participate in the reduction reaction, the volume ratio of the total flue gas, and the size of the reducing agent particles; the ammonia escape treatment module has two sampling points, the first sampling point is set at the spray gun, and the second sampling point is set at the first flue outlet; The first sampling point is used to detect the particle size of the reducing agent; the second sampling point is used to detect the volume ratio of NH3 that does not participate in the reduction reaction and the total amount of flue gas; The ammonia escape processing module detects the reducing agent particle size in the following manner: Based on the principle of digital holographic measurement, the reducing agent sprayed from the spray gun is sampled and the particle size of the reducing agent is obtained by combining the scalar diffraction theory.

2. The SNCR denitrification control system for industrial boilers according to claim 1, characterized in that: The sensing layer also includes a pressure measurement module, a temperature detection module, a limit control denitrification module, a multi-component gas analyzer, and a CEMS detector; The pressure measurement module is arranged at the primary air inlet, secondary air inlet and flue gas outlet of the furnace, and is used to measure the change in flue gas volume and flue gas flow velocity parameters; The temperature detection module includes a plurality of wireless temperature detection sensor arrays, which are arranged in three layers between the secondary air inlet of the furnace and the first flue outlet of the furnace to measure the temperature distribution in the furnace; The limit control denitration module is arranged at the first flue outlet of the furnace or at the inlet of the SCR denitration device, and is used to measure the content of nitrogen oxides in the flue gas; The multi-component gas analyzer is used to collect the nitrogen oxide concentration, oxygen content and sulfide content in the flue of the furnace. The sampling components of the multi-component gas analyzer are arranged on both sides of the furnace and between the secondary air inlet and the spray gun; The dynamic measurement module for flue gas volume includes a flow meter, a temperature sensor, and a pressure sensor. The collection point of the dynamic measurement module for flue gas volume is set between the secondary air inlet and the first flue inlet of the furnace; The CEMS detector is arranged at the first flue inlet and the flue gas outlet of the furnace, and is used to measure the raw material physical properties and pollutant emission parameters of the flue gas.

3. The SNCR denitrification control system for industrial boilers according to claim 2, characterized in that: The wireless temperature detection sensor array is composed of multiple wireless temperature sensor nodes, which are used to collect the temperature information of the furnace and send the temperature information through LoRa or NB-IoT communication.

4. The SNCR denitrification control system for industrial boilers according to claim 1, characterized in that: The execution layer also includes an electromagnetic flowmeter, which is installed on the delivery pipeline of the spray gun and the compressed air pipeline of the air compressor. The control layer includes an operation load adjustment module, a reducing dosage control module, and a working temperature field numerical simulation module; The operation load adjustment module is used to adjust the flue gas, fuel and steam in the furnace; The reducing dosage control module is used to control the electromagnetic flowmeter, the size and angle of the spray gun nozzle, and the air compressor; The operating temperature field numerical simulation module is used to perform process simulation according to the operating parameters of the furnace, providing a calculation data basis for the control of the reducing agent.

5. The SNCR denitrification control system for industrial boilers according to claim 4, characterized in that: The electromagnetic flowmeter has a remote wireless transmission and receiving function, and configures the ratio of the reducing agent according to the instruction of the reducing agent dosage control module.

6. The SNCR denitrification control system for industrial boilers according to claim 1, characterized in that: The management layer includes an operation history database, a numerical calculation database and a process visualization module; The operation history database stores the operation data of the furnace and the operation history data of furnaces of the same type, and shares data with the numerical calculation database and the process visualization module; The numerical calculation database stores simulation data of the same type of furnaces and numerical simulation data of the operating temperature field, and outputs the stored data to the visualization module for comparison and analysis with the operation history data, or with the data collected by the perception layer; The process visualization module includes a data processing microcomputer system and an LED display screen.

7. An industrial boiler SNCR denitration control method, applied to the industrial boiler SNCR denitration control system according to any one of claims 1 to 6, characterized in that: The following steps are involved: Collecting first content information of NO and O2 in the furnace; Obtaining a NOx concentration based on the first content information, and calculating second NH3 content information based on the NOx concentration; A control instruction is generated according to the second content information, and the working states of the spray gun, the air compressor and the ammonia injection regulating valve are controlled according to the control instruction so that the spray gun sprays the reducing agent into the furnace.

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