SCR (Selective Catalytic Reduction) denitration system of corner tangential coal-fired boiler and ammonia injection grid zoning control method thereof

Abstract

The embodiment of the invention provides a corner tangential coal-fired boiler SCR denitration system and an ammonia injection grid partition control method thereof, and the method comprises the steps that an ammonia injection grid is divided into a plurality of independently-controlled large areas based on the combustion characteristics and flue gas flow characteristics of a coal-fired boiler, and each large area is internally provided with a plurality of ammonia injection grid injection points; a manual valve and an automatic adjusting valve are arranged in each large area, the ammonia spraying amount of a spraying point of a single ammonia spraying grid is adjusted through the manual valve, and the total ammonia spraying amount of the whole large area is dynamically adjusted through the automatic adjusting valve; and the NOx concentration and the ammonia escape concentration corresponding to each large area are monitored in real time, and the ammonia spraying amount of each large area is dynamically optimized through a control algorithm based on the boiler operation load change, so that the ammonia spraying distribution of each large area is matched with the NOx concentration distribution.

Description

Technical Field

[0001] This document relates to the field of coal-fired power plant technology, and in particular to a four-corner tangential circle coal-fired boiler SCR denitrification system and its ammonia injection grid zone control method. Background Technology

[0002] Against the backdrop of increasingly severe environmental protection issues, emission standards for coal-fired power units have become increasingly stringent in recent years, particularly regarding NOx. x Emissions restrictions have been further tightened. NO x As one of the main pollutants generated during the combustion process of coal-fired boilers, controlling its emissions is of great significance for improving air quality and protecting human health. Therefore, in most cases, coal-fired power units need to adopt efficient denitrification technologies to reduce NOx emissions. x Emissions.

[0003] Selective catalytic reduction (SCR) is a widely used denitrification technology. SCR technology involves installing an ammonia injection grid at the tail end of the economizer in a coal-fired power plant, injecting a reducing agent (usually ammonia or urea) into the flue gas to react with NO in the flue gas. x A chemical reaction occurs. Simultaneously, a catalyst is installed between the economizer and the air preheater. The catalyst's role is to accelerate the SCR denitrification reaction and improve denitrification efficiency. Under the action of the catalyst, NO... x It is reduced to harmless nitrogen (N2) and water (H2O), thus achieving NO reduction in coal-fired power units. x Effective control of emissions.

[0004] However, in practical applications, the operation of SCR denitrification systems often faces numerous challenges due to the complexity of the combustion characteristics and flue gas flow characteristics of coal-fired boilers. Among these challenges, the uniformity and accuracy of the ammonia injection grid are key factors affecting the SCR denitrification effect. Uneven distribution of ammonia injection in the grid will lead to an imbalance in the ammonia-nitrogen molar ratio within the catalyst bed, thereby affecting denitrification efficiency and potentially causing problems such as ammonia slip.

[0005] With increasingly stringent national environmental protection requirements, NOx emissions from coal-fired power plants are becoming more stringent. x Emission control has become a crucial task. This is especially true for the large-scale, high-parameter tangential coal-fired boilers that my country has been vigorously developing in recent years, particularly their NOx emissions. x Emissions have become a major concern. To effectively address this issue, these coal-fired boilers have generally been equipped with denitrification devices to control NOx emissions. x Effective control.

[0006] In recent years, with the comprehensive advancement of ultra-low emission retrofitting of coal-fired power units, NO x Emission standards are also becoming increasingly stringent. In many regions, coal-fired power units are facing higher NOx emissions.x Emission requirements are already below 50 mg / m³ 3 (Standard condition, dry basis, 15% O2), and some key regions have proposed even stricter emission standards. For example, Hebei Province explicitly requires coal-fired power units to meet NO2 standards. x Emissions must be below 20 mg / m³ 3 (Standard condition, dry basis, 15% O2). Faced with such stringent emission standards, relying solely on traditional ammonia injection control technology is no longer sufficient to meet the requirements. For tangential coal-fired boilers, using an SCR denitrification system with ammonia injection grid zone control has become an effective solution. The core of this solution lies in adjusting the boiler's operating conditions and NO levels accordingly. x Based on the distribution pattern, the ammonia injection grid is divided into zones for zoned control to achieve the desired ammonia injection rate and NO content. x Precise matching of concentrations.

[0007] In addition, the denitrification flue of the tangential boiler is relatively long, leading to higher NO levels. x The distribution along the length direction is uneven. If a traditional ammonia injection grid with a static mixer is used, it is difficult to achieve a consistent ammonia injection rate and NO distribution within the area. x Uniform concentration matching is essential. Therefore, ammonia injection grids with shorter mixing distances should be selected, and automatic zone adjustment should be implemented according to changes in operating conditions.

[0008] The key to solving this problem is how to rationally divide the area into zones. Therefore, there is an urgent need to design a zone control method for the ammonia injection grid in a four-corner tangential circular coal-fired boiler SCR denitrification system to solve the zone problem of the ammonia injection grid. Summary of the Invention

[0009] The purpose of this invention is to provide a four-corner tangential coal-fired boiler SCR denitrification system and its ammonia injection grid zone control method, aiming to solve the above-mentioned problems in the prior art.

[0010] This invention provides a method for zoned control of ammonia injection grid in a tangentially circular SCR denitrification system of a coal-fired boiler, comprising: Based on the combustion characteristics and flue gas flow characteristics of coal-fired boilers, the ammonia injection grid is divided into multiple independently controlled large areas, and each large area is equipped with several ammonia injection grid injection points. Manual valves and automatic regulating valves are configured in each region. The manual valves are used to adjust the amount of ammonia injected at a single ammonia injection grid injection point, while the automatic regulating valves are used to dynamically adjust the total amount of ammonia injected in the entire region. Real-time monitoring of NO corresponding to each region x Ammonia concentration and ammonia slip concentration are dynamically optimized in each boiler zone based on boiler operating load changes using a control algorithm, ensuring that the ammonia injection distribution in each zone is in line with NO concentration. x The concentration distributions match.

[0011] This invention provides a tangentially circular SCR denitrification system for a coal-fired boiler, and a method for zoned control of the ammonia injection grid in the aforementioned tangentially circular SCR denitrification system for a coal-fired boiler, comprising: Ammonia injection grids are used to divide the area into multiple independently controlled zones, each zone containing several ammonia injection grid injection points. Manual valves, located in each major area, are used to adjust the ammonia injection rate at individual ammonia injection grid injection points. Automatic regulating valves are installed in each major area to dynamically adjust the total ammonia injection volume of the entire major area; NO x Concentration monitoring devices are installed at corresponding locations in each zone of the SCR reactor outlet section to monitor NO concentration in real time across each zone. x concentration; Ammonia slip monitoring devices are installed at corresponding locations in each zone of the SCR reactor outlet section to monitor the ammonia slip concentration in each zone in real time. The control system is used to divide the ammonia injection grid into multiple independently controllable zones based on the combustion characteristics and flue gas flow characteristics of a coal-fired boiler, and to set the ammonia injection points within each zone; it controls the manual valves to adjust the ammonia injection rate at individual injection points, and controls the automatic regulating valves to dynamically adjust the total ammonia injection rate for the entire zone; and it adjusts the ammonia injection rate based on the real-time monitored NO levels for each zone. x Ammonia concentration and ammonia slip concentration are dynamically optimized in each boiler zone based on boiler operating load changes using a control algorithm, ensuring that the ammonia injection distribution in each zone is in line with NO concentration. x The concentration distributions match.

[0012] By employing the embodiments of the present invention, the ammonia injection rate in each zone can be more precisely controlled, thereby optimizing the denitrification effect and reducing NO. x emission. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in one or more embodiments of this specification or in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a flowchart of the ammonia injection grid zone control method for a four-corner tangential circular coal-fired boiler SCR denitrification system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the ammonia injection grid partitioning according to an embodiment of the present invention; Figure 3This is a schematic diagram of a four-corner tangential coal-fired boiler SCR denitrification system according to an embodiment of the present invention. Detailed Implementation

[0015] To enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this document.

[0016] Method Implementation Examples According to an embodiment of the present invention, a method for zoned control of ammonia injection grid in a tangentially circular SCR denitrification system of a coal-fired boiler is provided. Figure 1 This is a flowchart of the ammonia injection grid zone control method for a four-corner tangential circular coal-fired boiler SCR denitrification system according to an embodiment of the present invention, as shown below. Figure 1 As shown, the ammonia injection grid zone control method for a four-corner tangential circular coal-fired boiler SCR denitrification system according to an embodiment of the present invention specifically includes: Step S101, based on the combustion characteristics and flue gas flow characteristics of the coal-fired boiler, divides the ammonia injection grid into multiple independently controlled large zones, with several ammonia injection grid injection points set in each large zone; specifically including: According to the flue cross-sectional dimensions, NO x The uneven distribution and the range of boiler load variations require adaptive adjustments to the number of large areas and the number of ammonia injection grid injection points.

[0017] Preferably, in one embodiment, based on the combustion characteristics and flue gas flow characteristics of the coal-fired boiler, the ammonia injection grid is divided into four large zones, each zone is evenly distributed along the flue section, and each zone is provided with 16 ammonia injection grid injection points, which are arranged in a matrix. The ammonia injection grid adopts a short mixing distance design.

[0018] Step S102 involves configuring manual valves and automatic regulating valves within each large area. The manual valves adjust the ammonia injection rate at individual ammonia injection points, while the automatic regulating valves dynamically adjust the total ammonia injection volume for the entire large area. Specifically, this includes: The initial ammonia injection volume at each ammonia injection grid injection point is finely adjusted using the manual valve during the commissioning phase. The manual valve is an adjustable butterfly valve or a needle valve. The automatic regulating valve is connected to the DCS control system to realize real-time closed-loop control of dynamic adjustment of the total ammonia injection volume in the entire area. The automatic regulating valve is an electric or pneumatic regulating valve.

[0019] Step S103: Real-time monitoring of the corresponding NO in each major region. x Ammonia concentration and ammonia slip concentration are dynamically optimized in each boiler zone based on boiler operating load changes using a control algorithm, ensuring that the ammonia injection distribution in each zone is in line with NO concentration. x The concentration distribution is matched. Specifically, this includes: Hot commissioning was conducted on the boiler under different load conditions, using multi-point NO₂ systems located at corresponding positions in each zone of the SCR reactor outlet section. x Concentration monitoring devices and ammonia slip monitoring devices monitor NO concentration in real time in various regions. x Concentration and ammonia slip concentration, based on ammonia injection strategy, establish the relationship between regional ammonia injection amount and NO. x A correlation model for removal efficiency; based on the correlation model, combined with real-time monitoring of NO... x The concentration distribution data is used to dynamically adjust the opening of the automatic regulating valves in each region using PID control or fuzzy control algorithms, so that the ammonia injection rate in each region is in line with the NO concentration. x The concentration distribution remains optimally matched.

[0020] The technical solution of this invention further includes: predicting NO based on the load change trend when the boiler is operating under variable load. x The system monitors changes in concentration distribution and adjusts ammonia injection rates in advance for each zone. It also optimizes the control parameters of the automatic regulating valves using historical operating data. Furthermore, it communicates with the boiler's DCS system to adjust the ammonia injection strategy in real time based on unit load, combustion conditions, and flue gas parameters.

[0021] The technical solutions of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0022] This invention provides a zoned control method for ammonia injection grids in a tangentially circular SCR denitrification system of a coal-fired boiler. This method allows for more precise control of the ammonia injection rate in each zone, thereby optimizing the denitrification effect and reducing NO₂ levels. x emission.

[0023] First, such as Figure 2 As shown in the diagram, this embodiment of the invention provides a zoning diagram for the flue gas flow cross-section inside a denitrification vertical flue boiler. The injection points of the ammonia injection grids inside the denitrification tail flue are finely divided into four large zones, each containing 16 injection points of the ammonia injection grids. This zoning design allows for more precise control of the ammonia injection amount in each zone to meet the needs of different operating conditions.

[0024] In this embodiment of the invention, different numbers of manual valves are installed at the injection points of the 16 ammonia injection grids as needed. These manual valves can flexibly control the ammonia injection rate at each injection point to meet different adjustment requirements. Simultaneously, each zone is also equipped with an automatic regulating valve, which can automatically adjust the ammonia injection rate within that zone according to the actual operating conditions of the unit.

[0025] In practical applications, embodiments of the present invention can be adapted based on the cross-sectional dimensions of the boiler flue and NO. x The distribution of the components allows for flexible adjustment of the number of zones and the number of injection points within each zone. This makes the invention more widely applicable and flexible, enabling it to adapt to coal-fired boilers of different sizes and operating conditions.

[0026] After the denitrification device for the four-corner tangential coal-fired boiler was installed, this embodiment of the invention underwent a series of hot-state commissioning operations. These commissioning conditions covered the lowest to highest loads that the unit could achieve in actual operation, to ensure that the denitrification system could operate stably and achieve the expected denitrification effect under various loads.

[0027] During the hot commissioning process, this embodiment of the invention first opens all manual valves at the ammonia-air mixer injection points within all zones. Then, through on-site testing and measurement, the NO levels at the corresponding large zones of each ammonia injection grid after the SCR catalyst under various loads are obtained. x Concentration and ammonia slip concentration. By comparing and analyzing these data, embodiments of the present invention can obtain NO concentrations between large zones. x The difference is used to determine the adjustment difference between the control valves.

[0028] In actual operation, the regulating valves of the large-area units will automatically adjust according to changes in the unit's load. Simultaneously, this embodiment of the invention will also adjust based on the NO emissions from the total discharge port. x The numerical values ​​are used to correct the adjustment of the regulating valve in real time to ensure the accuracy and stability of the denitrification effect. This precise adjustment gives the present invention significant advantages and effects in the SCR denitrification system of a tangential coal-fired boiler.

[0029] The specific processing steps are explained in detail below.

[0030] This invention provides a method for zoned control of ammonia injection grid in a tangentially circular SCR denitrification system of a coal-fired boiler, comprising the following steps: Based on the combustion characteristics and flue gas flow characteristics of coal-fired boilers, the ammonia injection grid is divided into multiple independently controlled large areas, and several ammonia injection grid injection points are set in each large area. Each region is equipped with manual valves and automatic regulating valves, wherein the manual valves are used to regulate the amount of ammonia injected at a single injection point, and the automatic regulating valves are used to dynamically adjust the total amount of ammonia injected throughout the entire region. Real-time monitoring of the NO corresponding to each partition x The concentration and ammonia slip concentration, combined with changes in boiler operating load, are used to dynamically optimize the ammonia injection rate in each zone through a control algorithm, so that the ammonia injection distribution is in line with NO levels. x The concentration distribution is matched to improve denitrification efficiency and reduce ammonia slip.

[0031] The ammonia injection grid is divided into four large zones, each evenly distributed along the flue cross-section, and each zone contains 16 ammonia injection points arranged in a matrix. The manual valves are adjustable butterfly valves or needle valves, used for fine adjustment of the initial ammonia injection volume at each injection point during the commissioning phase; the automatic regulating valves are electric or pneumatic regulating valves, connected to the DCS control system to achieve real-time closed-loop control.

[0032] The method for dynamically optimizing ammonia injection includes: conducting hot-state commissioning under different boiler load conditions and measuring the NO corresponding to each zone. x Concentration and ammonia slip concentration, establishing the relationship between ammonia injection rate and NO in different zones. x A model relating removal efficiency; based on this model, combined with real-time monitoring of NO... x Based on the distributed data, the opening degree of the automatic regulating valves in each zone is dynamically adjusted using PID control algorithms or fuzzy control algorithms to ensure that the ammonia injection quantity is in line with the NO injection quantity. x The concentration distribution remains optimally matched.

[0033] The real-time monitoring adopts a multi-point NO... x Concentration analyzers and ammonia slip monitors are installed at corresponding locations in each section of the SCR reactor outlet section to ensure the accuracy of data acquisition.

[0034] The number of zones and injection points can be determined based on the flue cross-sectional dimensions and NO. x The distribution unevenness and boiler load variation range are adaptively adjusted to meet the denitrification requirements of different units.

[0035] When the boiler is operating under varying loads, NO is predicted based on the load change trend. x Changes in concentration distribution were monitored, and the ammonia injection rate in each zone was adjusted in advance to reduce the impact of ammonia injection lag on denitrification efficiency. Control parameters were optimized using historical operating data to improve the response speed and stability of zone control.

[0036] The ammonia injection grid is divided into multiple independently controlled zones, each zone containing several ammonia injection points; manual valves and automatic regulating valves are used to adjust the ammonia injection rate at individual injection points and for the entire zone, respectively; NO x Concentration monitoring devices and ammonia slip monitoring devices are used to collect emission data from each zone in real time.

[0037] The ammonia injection grid adopts a short mixing distance design to reduce the mixing time of ammonia and flue gas and improve the uniformity of ammonia injection distribution.

[0038] The control system is connected to the boiler DCS system and can adjust the ammonia injection strategy in real time according to the unit load, combustion conditions and flue gas parameters to ensure that the denitrification system operates efficiently and stably across all operating conditions. like Figure 2 As shown in the diagram, this embodiment of the invention provides a zoning diagram for the flue gas flow cross-section inside a denitrification vertical flue boiler. The injection points of the ammonia injection grids inside the denitrification tail flue are finely divided into four large zones, each containing 16 injection points of the ammonia injection grids. This zoning design allows for more precise control of the ammonia injection rate in each zone to meet the needs of different operating conditions. Within these 16 ammonia injection points, this embodiment of the invention incorporates a varying number of manual valves as needed. These manual valves can flexibly control the ammonia injection rate at each injection point to meet different adjustment requirements. Simultaneously, each zone is also equipped with an automatic regulating valve, which can automatically adjust the ammonia injection rate within that zone according to the actual operating conditions of the unit.

[0039] In summary, this invention provides a zonal control method for the ammonia injection grid in a tangentially circular SCR denitrification system of a coal-fired boiler. Through precise zonal design and flexible adjustment methods, we can achieve accurate control of the ammonia injection quantity in the denitrification system, thereby optimizing the denitrification effect and reducing NO₂ levels. x Emissions. This method has wide applicability and flexibility, and is of great significance for improving the environmental performance and economic benefits of coal-fired boilers. Compared with the prior art, the beneficial effects of the embodiments of the present invention are: 1. This zoning control method enables automatic zoning adjustment of the SCR denitrification system in a four-corner tangential coal-fired boiler. Through advanced control algorithms and precise sensor monitoring, the system can automatically determine the NO levels in different zones. x The system monitors emissions and adjusts the ammonia injection rate of the ammonia injection grid accordingly. This significantly reduces the workload of operators, lowers the complexity and error rate of manual operation, and improves work efficiency.

[0040] 2. This zoned control method can significantly improve the NO content at the outlet cross-section of the SCR denitrification system in a four-corner tangential coal-fired boiler. x Uniformity of NO distribution. Through zoned control, the system can precisely adjust to the characteristics of each zone, ensuring uniform NO distribution across the entire outlet cross-section. x Emission concentrations are more uniform. This not only helps reduce NO... xIt reduces environmental pollution, improves denitrification efficiency, and reduces ammonia consumption. Furthermore, the fully automated adjustment feature minimizes the need for human intervention, making the entire system more stable and reliable.

[0041] 3. In the case of a tangential coal-fired boiler operating under varying conditions, this zone control method can automatically adjust the ammonia injection rate. Because boiler operating conditions fluctuate with changes in operating conditions, traditional denitrification systems often struggle to adapt to these changes, leading to ammonia slip and increased ammonia consumption. This zone control method, however, can adjust the ammonia injection rate in real time according to changes in operating conditions, ensuring NO₂ levels are maintained. x Emissions are always kept within a reasonable range, while reducing ammonia escape and ammonia consumption, thus saving operating costs.

[0042] In conclusion, the ammonia injection grid zoning control method for SCR denitrification systems in four-corner tangential-circle coal-fired boilers is a feasible, advanced, and highly effective environmental protection technology. It not only improves the environmental performance of coal-fired boilers but also reduces NOx emissions. x The environmental impact of emissions also contributes positively to the sustainable development of enterprises by reducing the workload of operators, improving denitrification efficiency, and saving operating costs.

[0043] System Implementation Examples According to an embodiment of the present invention, a tangential circular SCR denitrification system for a coal-fired boiler is provided, and a method for zoned control of the ammonia injection grid in the tangential circular SCR denitrification system for the coal-fired boiler is provided. Figure 3 This is a schematic diagram of a four-corner tangential coal-fired boiler SCR denitrification system according to an embodiment of the present invention, as shown below. Figure 3 As shown, the SCR denitrification system for a tangentially circular coal-fired boiler according to an embodiment of the present invention specifically includes: The ammonia injection grid 10 is used to divide the area into multiple independently controlled zones, each zone having several ammonia injection points. The ammonia injection grid is divided into four zones, each zone being evenly distributed along the flue section, and each zone having 16 ammonia injection points arranged in a matrix. The ammonia injection grid adopts a short mixing distance design.

[0044] Manual valves 11 are installed in each major area to adjust the ammonia injection rate at individual ammonia injection grid injection points. Automatic regulating valves 12 are installed in each major area to dynamically adjust the total amount of ammonia injected into the entire major area; NOx concentration monitoring devices 13 are respectively installed at corresponding positions in each zone of the SCR reactor outlet section to monitor the NOx concentration in each zone in real time. x concentration; Ammonia slip monitoring devices 14 are installed at corresponding positions in each zone of the SCR reactor outlet section to monitor the ammonia slip concentration in each zone in real time. Control system 15 is used to divide the ammonia injection grid into multiple independently controllable zones based on the combustion characteristics and flue gas flow characteristics of the coal-fired boiler, and to set the ammonia injection points within each zone; to control the manual valves to adjust the ammonia injection rate at a single ammonia injection point, and to control the automatic regulating valves to dynamically adjust the total ammonia injection rate for the entire zone; and to adjust the ammonia injection rate based on the real-time monitored NO levels of each zone. x Ammonia concentration and ammonia slip concentration are dynamically optimized in each boiler zone based on boiler operating load changes using a control algorithm, ensuring that the ammonia injection distribution in each zone is in line with NO concentration. x The concentration distribution is matched. The control system is specifically used for: According to the flue cross-sectional dimensions, NO x The uneven distribution and the range of boiler load changes require adaptive adjustments to the number of large areas and the number of ammonia injection grid injection points; During the commissioning phase, the manual valve is controlled to finely adjust the initial ammonia injection amount at each ammonia injection grid injection point. The automatic regulating valve is connected to the DCS control system to realize real-time closed-loop control of dynamic adjustment of the total ammonia injection amount in the entire area. Hot-state commissioning was performed on the boiler under different load conditions to control NO. x Concentration monitoring devices and ammonia slip monitoring devices monitor NO concentration in real time in various regions. x Concentration and ammonia slip concentration, based on ammonia injection strategy, establish the relationship between regional ammonia injection amount and NO. x A correlation model for removal efficiency; based on the correlation model, combined with real-time monitoring of NO... x The concentration distribution data is used to dynamically adjust the opening of the automatic regulating valves in each region using PID control or fuzzy control algorithms, so that the ammonia injection rate in each region is in line with the NO concentration. x The concentration distribution remains optimally matched.

[0045] The control system is further used for: When the boiler is operating under varying loads, NO is predicted based on the load change trend. x The concentration distribution changes, and the ammonia injection volume of each region is adjusted in advance. The control parameters of the automatic regulating valve are optimized by using historical operating data of the automatic regulating valve. The system is connected to the boiler DCS system to adjust the ammonia injection strategy in real time according to the unit load, combustion conditions and flue gas parameters.

[0046] The embodiments of the present invention are system embodiments corresponding to the above method embodiments. The specific operation of each module can be understood by referring to the description of the method embodiments, and will not be repeated here.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for zoning control of ammonia injection grid of SCR denitration system of a tangentially fired coal-fired boiler, characterized in that, The method comprises the following steps: Based on the combustion characteristics and flue gas flow characteristics of the coal-fired boiler, the ammonia injection grid is divided into multiple independently controlled large areas, and a plurality of ammonia injection grid injection points are arranged in each large area; A manual valve and an automatic adjusting valve are respectively arranged in each large area, the ammonia injection amount of a single ammonia injection grid injection point is adjusted through the manual valve, and the total ammonia injection amount of the entire large area is dynamically adjusted through the automatic adjusting valve; Real-time monitoring of the corresponding NO x Concentration and ammonia escape concentration, based on the change of boiler load, through control algorithm dynamic optimization of each zone of ammonia injection amount, so that the ammonia injection distribution of each zone matches the NO x Concentration distribution.

2. The method of claim 1, wherein, Based on the combustion characteristics and flue gas flow characteristics of the coal-fired boiler, the ammonia injection grid is divided into multiple independently controlled large areas, and a plurality of ammonia injection grid injection points are arranged in each large area, which specifically comprises: According to the flue cross-sectional size, NO x The uneven distribution and the boiler load variation range adaptively adjust the number of large areas and the number of ammonia grid injection points.

3. The method according to claim 1 or 2, characterized in that, Based on the combustion characteristics and flue gas flow characteristics of the coal-fired boiler, the ammonia injection grid is divided into multiple independently controlled large areas, and a plurality of ammonia injection grid injection points are arranged in each large area, which specifically comprises: Based on the combustion characteristics and flue gas flow characteristics of the coal-fired boiler, the ammonia injection grid is divided into four large areas, each large area is uniformly distributed along the flue cross section, and 16 ammonia injection grid injection points are arranged in each large area, and each ammonia injection grid injection point is arranged in a matrix, wherein the ammonia injection grid adopts a short mixing distance design.

4. The method of claim 1, wherein, The ammonia injection amount of a single ammonia injection grid injection point is adjusted through the manual valve, and the total ammonia injection amount of the entire large area is dynamically adjusted through the automatic adjusting valve, which specifically comprises: The initial ammonia injection amount of each ammonia injection grid injection point is finely adjusted through the manual valve in the debugging stage, wherein the manual valve is an adjustable butterfly valve or a needle valve; The automatic adjusting valve is connected with the DCS control system to realize real-time closed-loop control of dynamic adjustment of the total ammonia injection amount of the entire large area, wherein the automatic adjusting valve is an electric or pneumatic adjusting valve.

5. The method of claim 1, wherein, Real-time monitoring of the corresponding NO x Concentration and ammonia escape concentration, based on the change of boiler operating load, through control algorithm dynamic optimization of the amount of ammonia injection of each district, so that the ammonia injection distribution of each district matches the NO x Concentration distribution specifically includes: The boiler is tested under different load conditions, and the multi-point NO x concentration monitoring device and ammonia escape monitoring device monitor the corresponding NO x concentration and ammonia escape concentration of each zone in real time, establish the corresponding relationship model of zone ammonia injection amount and NO x removal efficiency based on ammonia injection strategy; based on the corresponding relationship model, combined with the distribution data of real-time monitored NO x concentration, the opening of the automatic adjusting valve of each zone is dynamically adjusted by using PID control algorithm or fuzzy control algorithm, so that the ammonia injection amount of each zone and NO x concentration distribution keeps the best match.

6. The method according to claim 1 or 5, characterized in that, The method further comprises: When the boiler is running under variable load, the NO x Concentration distribution changes, and the ammonia injection amount of each zone is adjusted in advance, and the control parameters of the automatic adjusting valve are optimized through historical operation data of the automatic adjusting valve.

7. In communication with the boiler DCS system, the ammonia injection strategy is adjusted in real time according to the unit load, combustion condition and flue gas parameters.

8. A tangentially fired coal-fired boiler SCR denitration system, characterized in that, The four-corner tangential coal-fired boiler SCR denitration system ammonia injection grid zoning control method of any one of claims 1 to 6, the system specifically comprises: An ammonia injection grid is divided into multiple independently controlled large areas, wherein a plurality of ammonia injection grid injection points are arranged in each large area; A manual valve is arranged in each large area to adjust the ammonia injection amount of a single ammonia injection grid injection point, An automatic adjusting valve is arranged in each large area to dynamically adjust the total ammonia injection amount of the entire large area; NO x Concentration monitoring devices are arranged at the corresponding positions of each sub-zone of the outlet cross-section of the SCR reactor to monitor the NOx concentration of each sub-zone in real time. x Concentration monitoring devices are arranged at the corresponding positions of each sub-zone of the outlet cross-section of the SCR reactor to monitor the NOx concentration of each sub-zone in real time. An ammonia escape monitoring device is arranged at the corresponding position of each partition of the SCR reactor outlet cross section to monitor the ammonia escape concentration of each large area in real time. The control system is used for dividing the ammonia injection grid into multiple independently controlled zones based on the combustion characteristics and flue gas flow characteristics of the coal-fired boiler, and setting the ammonia injection grid injection points in each zone; the manual valve is used for controlling the ammonia injection amount of the single ammonia injection grid injection point, and the automatic adjusting valve is used for dynamically adjusting the total ammonia injection amount of the whole zone; according to the real-time monitored NO x Concentration of each zone and the ammonia escape concentration, based on the change of the boiler operation load, the ammonia injection amount of each zone is dynamically optimized through the control algorithm, so that the ammonia injection distribution of each zone matches the NO x Concentration distribution.

9. The system of claim 7, wherein, The ammonia injection grid is divided into four large areas, each large area is uniformly distributed along the flue cross section, and 16 ammonia injection grid injection points are arranged in each large area, and each ammonia injection grid injection point is arranged in a matrix, wherein the ammonia injection grid adopts a short mixing distance design.

10. The system of claim 7, wherein, The control system is specifically used for: According to the flue cross-sectional size, NO x The uneven distribution and the boiler load variation range adaptively adjust the number of large areas and the number of ammonia grid injection points. Controlling the manual valve to finely adjust the initial ammonia injection amount of each ammonia injection grid injection point in the debugging stage, and controlling the automatic adjusting valve to be connected with the DCS control system to realize real-time closed-loop control of dynamic adjustment of the total ammonia injection amount of the entire large area; The boiler is tested under different load conditions, and the NO x Concentration monitoring device and ammonia escape monitoring device, real-time monitoring of each large area corresponding to the NO x Concentration and ammonia escape concentration, based on ammonia injection strategy, establish the corresponding relationship model of large area ammonia injection amount and NO x Removal efficiency; based on the corresponding relationship model, combined with the distribution data of real-time monitoring NO x Concentration, using PID control algorithm or fuzzy control algorithm to dynamically adjust the opening of the automatic adjusting valve of each large area, so that the ammonia injection amount of each large area and NO x Concentration distribution keeps the best match.

11. The system of claim 7, wherein, The control system is further used for: When the boiler is running at variable load, the NO x The concentration distribution changes, and the ammonia injection amount of each large area is adjusted in advance, and the control parameters of the automatic adjusting valve are optimized through the historical operation data of the automatic adjusting valve; and the boiler DCS system is communicated and connected, and the ammonia injection strategy is adjusted in real time according to the unit load, combustion condition and flue gas parameters.

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