Biomass mixed combustion boiler low-nitrogen combustion system based on high-temperature ammonia injection and control method thereof

Abstract

The application provides a low-nitrogen combustion system of a biomass mixed combustion boiler based on high-temperature ammonia injection and a control method thereof. The system comprises a fuel supply assembly, an ammonia supply assembly, an oxygen supply assembly, and a boiler. The boiler is divided into a main combustion zone, a reduction zone, and a burnout zone in the height direction. The main combustion zone is provided with a burner, obtains fuel provided by the fuel supply assembly, and performs fuel-rich combustion through the burner. The reduction zone obtains ammonia provided by the ammonia supply assembly, and performs oxygen-poor combustion of compounds formed after fuel combustion in the main combustion zone and ammonia. The burnout zone obtains oxygen provided by the oxygen supply assembly and ammonia provided by the ammonia supply assembly, and performs oxygen-rich combustion of compounds formed after combustion in the reduction zone, ammonia, and oxygen. A detection unit is used for detecting the content of nitrogen oxide compounds in the burnout zone. A control unit is used for controlling the fuel supply assembly, the ammonia supply assembly, and the oxygen supply assembly according to the content of nitrogen oxide compounds in the burnout zone.

Description

Technical Field

[0001] This invention belongs to the field of fuel combustion, and particularly relates to a low-NOx combustion system for a biomass co-firing boiler based on high-temperature zone ammonia injection and its control method. Background Technology

[0002] Conventional Selective Non-Catalytic Reduction (SNCR) technology typically injects an ammonia reducing agent between 850°C and 1100°C to reduce nitrogen oxides to N2 and H2O. However, existing SNCR technologies still have shortcomings. Ammonia injection requires flue gas temperatures between 850°C and 1100°C, a relatively narrow temperature window, and the resulting high nitrogen oxide emissions at the outlet still lead to some ammonia slip. Summary of the Invention

[0003] This invention provides a low-NOx combustion system and control method for a biomass co-firing boiler based on ammonia injection in a high-temperature zone. This system can increase the ammonia injection temperature range, reduce the emission of nitrogen oxides at the outlet, and prevent ammonia escape.

[0004] On the one hand, a low-NOx combustion system for a biomass co-firing boiler based on high-temperature zone ammonia injection is provided, including:

[0005] Feeding assembly, used to supply fuel;

[0006] Ammonia supply assembly, used to supply ammonia;

[0007] Gas supply components, used to provide oxygen or air;

[0008] The boiler is divided into a main combustion zone, a reduction zone, and a burnout zone according to its height. The main combustion zone is equipped with a burner, which receives fuel from the fuel supply assembly and performs fuel-rich combustion. The reduction zone receives ammonia from the ammonia supply assembly and performs oxygen-deficient combustion of the flue gas and incompletely burned fuel from the main combustion zone with the ammonia. The burnout zone receives oxygen or air from the air supply assembly and ammonia from the ammonia supply assembly, and performs oxygen-rich combustion of the flue gas and incompletely burned fuel from the reduction zone with the ammonia, air, or oxygen.

[0009] The detection unit is used to detect the content of nitrogen oxides in the burnout zone;

[0010] The control unit is used to control the feeding assembly, ammonia supply assembly, and gas supply assembly based on the nitrogen oxide content in the burnout zone.

[0011] Optionally, the feeding assembly includes:

[0012] The pulverized coal feeding assembly and the biomass fuel feeding assembly are used to supply pulverized coal and biomass fuel, respectively;

[0013] The biomass fuel supply unit injects the biomass fuel into the reduction zone, where it is burned with the products formed after combustion in the main combustion zone.

[0014] The amount of biomass fuel supplied by the biomass fuel feeding assembly is determined based on 10% to 15% of the total fuel calorific value.

[0015] Optionally, the excess air coefficient of the main combustion zone is 0.85~0.95, and the excess air coefficient of the reduction zone is 0.75~0.85.

[0016] Optionally, the temperature range of ammonia injection in the reduction zone is 1000℃~1200℃, and the temperature range of ammonia injection in the combustion zone is 850℃~1100℃. The ammonia injection in the reduction zone is located below the biomass fuel feeding assembly, and the ammonia injection in the combustion zone is located below the gas supply assembly.

[0017] On the other hand, a control method for a low-NOx combustion system of a biomass co-firing boiler based on high-temperature zone ammonia injection is provided. This control method is applied to the low-NOx combustion system of the biomass co-firing boiler based on high-temperature zone ammonia injection as described in any of the preceding claims, and includes:

[0018] Historical operating data of the low-NOx combustion system of a biomass co-firing boiler based on ammonia injection in the high-temperature zone were obtained through periodic measurements.

[0019] A relational expression was constructed based on historical operating data to describe the relationship between inlet parameters and outlet nitrogen oxide content;

[0020] Obtain the content of nitrogen oxides at the outlet detected by the detection unit;

[0021] When the nitrogen oxide emissions at the outlet do not meet the requirements, the control unit generates control commands based on the relational formula to adjust the inlet parameters.

[0022] Optionally, a relation is constructed to describe the relationship between the inlet parameters and the amount of nitrogen oxides at the outlet, including:

[0023] The first relation is constructed based on historical operating data. This describes the relationship between ammonia injection rate in the reduction zone, ammonia injection rate in the burnout zone, biomass input rate, burnout air rate, biomass input ratio, boiler load, total air volume, and outlet nitrogen oxide emissions. , , , , , , and The raw data of ammonia injection in the reduction zone, ammonia injection in the burnout zone, biomass input, burnout air rate, biomass input ratio, boiler load, total air volume and outlet nitrogen oxide emissions were obtained by normalization.

[0024] Construct a second relation based on historical operating data. This is used to describe the relationship between biomass input amount, biomass input ratio, boiler load, and total air volume;

[0025] Construct a third relation based on historical operating data. This is used to describe the relationship between burnout air rate, boiler load, and total air volume.

[0026] Optionally, when the outlet nitrogen oxide emissions do not meet the requirements, the control unit generates control commands based on the relational formula to adjust the inlet parameters, including:

[0027] When the nitrogen oxide emissions at the export site do not meet the requirements, the ammonia injection rate in the reduction zone, the ammonia injection rate in the burnout zone, the biomass input rate, the burnout wind rate, and the biomass input ratio shall be adjusted according to the first to third relationships.

[0028] Optionally, the first relation is:

[0029] ,

[0030] In the formula, and Determined based on historical operational data, , .

[0031] Optionally, the second relation is:

[0032] ,

[0033] In the formula, and Determined based on historical operational data, , .

[0034] Optionally, the third relation is:

[0035] ,

[0036] In the formula, and Determined based on historical operational data, , .

[0037] The beneficial effects of the technical solutions provided in this disclosure are:

[0038] In this embodiment, a low-NOx combustion system for a biomass co-firing boiler based on high-temperature zone ammonia injection is provided. The low-NOx combustion system includes a main combustion zone, a reduction zone, and a burnout zone, and further includes a feed assembly, an ammonia supply assembly, and an ammonia supply component. The emission of nitrogen oxides at the outlet is detected by a detection unit. When the emission of nitrogen oxides at the outlet does not meet the requirements, the emission of nitrogen oxides at the outlet is reduced by adjusting the feed assembly, the ammonia supply assembly, and the gas supply assembly. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in this invention or 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 A schematic diagram of a low-NOx combustion system for a biomass co-firing boiler based on ammonia injection in a high-temperature zone is provided for an embodiment of this disclosure;

[0041] Figure 2 A flowchart illustrating a control method for a low-NOx combustion system in a biomass co-firing boiler based on ammonia injection in a high-temperature zone, provided in this embodiment of the disclosure;

[0042] Figure 3 This disclosure provides a set of historical operating data for a low-NOx combustion system of a biomass co-firing boiler based on ammonia injection in a high-temperature zone, which is provided for embodiments of this disclosure.

[0043] The attached figures are labeled as follows:

[0044] 1: Feeding assembly;

[0045] 2: Ammonia supply components;

[0046] 3: Gas supply components;

[0047] 4: Boiler; 41: Main combustion zone; 411: Burner; 42: Reduction zone; 43: Combustion zone;

[0048] 5: Detection unit;

[0049] 6: Control unit. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0051] Research indicates that high-temperature ammonia injection can replace the current SNCR technology. High-temperature reduction zone ammonia injection is a multi-zone ammonia injection technology based on air staging. An amino-based reducing agent is injected into the high-temperature, oxygen-deficient environment created in the furnace reduction zone, simultaneously injected below the burnout tuyeres to reduce NOx in the flue gas. Compared to conventional SNCR technology, this technology results in a lower outlet NOx concentration and eliminates ammonia escape.

[0052] The main factors affecting the denitrification efficiency of ammonia injection in the high-temperature reduction zone are the temperature and oxygen concentration at the injection point, which should generally be less than 0.5%. Due to the uneven oxygen concentration within the boiler, there are areas with high oxygen concentrations, leading to ammonia oxidation and reducing the denitrification efficiency of high-temperature ammonia injection. Therefore, this technology injects biomass into the reduction zone to lower the oxygen concentration, creating a more uniform reducing atmosphere and improving NOx reduction efficiency.

[0053] Figure 1 This is a schematic diagram of a low-NOx combustion system for a biomass co-firing boiler based on high-temperature zone ammonia injection, provided as an embodiment of this disclosure. See also... Figure 1 The system includes:

[0054] Feeding assembly 1 is used to provide fuel;

[0055] Ammonia supply component 2 is used to supply ammonia;

[0056] Gas supply component 3 is used to provide oxygen or air;

[0057] Boiler 4 is divided into a main combustion zone 41, a reduction zone 42, and a burnout zone 43 in sequence according to height. The main combustion zone 41 is equipped with a burner 411, which receives fuel from the feeding assembly 1 and performs fuel-rich combustion. The reduction zone 42 receives ammonia from the ammonia supply assembly 2 and performs oxygen-deficient combustion of the flue gas and unburned fuel formed after fuel combustion in the main combustion zone 41 with the ammonia. The burnout zone 43 receives oxygen or air from the air supply assembly 3 and ammonia from the ammonia supply assembly 2, and performs oxygen-rich combustion of the flue gas and unburned fuel formed after combustion in the reduction zone 42 with the ammonia, air, or oxygen.

[0058] Detection unit 5 is used to detect the content of nitrogen oxides in the burnout zone 43;

[0059] Control unit 6 is used to control the feeding assembly 1, ammonia supply assembly 2 and gas supply assembly 3 according to the content of nitrogen oxides in the burnout zone 43.

[0060] In this embodiment, a low-NOx combustion system for a biomass co-firing boiler based on high-temperature zone ammonia injection is provided. The low-NOx combustion system includes a main combustion zone, a reduction zone, and a burnout zone, and further includes a feed assembly, an ammonia supply assembly, and an ammonia supply component. The emission of nitrogen oxides at the outlet is detected by a detection unit. When the emission of nitrogen oxides at the outlet does not meet the requirements, the emission of nitrogen oxides at the outlet is reduced by adjusting the feed assembly, the ammonia supply assembly, and the gas supply assembly.

[0061] In this embodiment of the disclosure, the feeding assembly 1 includes:

[0062] The pulverized coal feeding assembly 11 and the biomass fuel feeding assembly 12 are used to supply pulverized coal and biomass fuel, respectively.

[0063] The biomass fuel feeding assembly 12 arranges the biomass fuel against the front and rear walls and injects it into the reduction zone in a swirling manner to burn with the products formed after combustion in the main combustion zone.

[0064] In this embodiment of the present disclosure, the biomass fuel feeding unit arranges the biomass fuel in a counter-current manner and injects it into the main combustion zone in a swirling manner. This facilitates the full mixing of biomass fuel and pulverized coal and can stabilize the combustion flame, thereby improving the combustion effect of the fuel.

[0065] In this embodiment of the disclosure, the biomass fuel feeding assembly 12 can spray biomass fuel through a biomass cyclone feeder, thereby realizing the injection of biomass fuel into the reduction zone in the form of a cyclone.

[0066] In this embodiment of the disclosure, the amount of biomass fuel delivered from the biomass fuel supply unit to the reduction zone is determined based on 10% to 15% of the total fuel calorific value in the main combustion zone.

[0067] In this embodiment of the disclosure, determining the amount of biomass fuel according to the above method can ensure that the reduction zone is maintained at a better combustion temperature, so that the fuel has a better combustion effect.

[0068] In this embodiment, the ammonia supply component 2 is disposed in the reduction zone 42 and the burnout zone 43. The ammonia supply component 2 can spray ammonia into the reduction zone 42 and the burnout zone 43 through the ammonia water nozzle spray gun.

[0069] In this embodiment, the gas supply component 3 is located in the burnout zone 43, and the gas supply component 3 can supply oxygen or gas through the SOFA air nozzle.

[0070] In this embodiment of the disclosure, the temperature range of ammonia injection in the reduction zone is 1000℃~1200℃, the temperature range of ammonia injection in the combustion zone is 850℃~1100℃, and the ammonia injection in the reduction zone is located below the biomass fuel feeding assembly, while the ammonia injection in the combustion zone is located below the gas supply assembly.

[0071] In this embodiment of the disclosure, the above-mentioned temperature is used so that the temperatures of the burnout zone and the reduction zone are within the optimal temperature range for the ammonia reduction reaction. Controlling the temperature of the reduction zone can reduce ammonia oxidation.

[0072] In this embodiment of the disclosure, the excess air coefficient of the main combustion zone is 0.85~0.95, and the excess air coefficient of the reduction zone is 0.75~0.85.

[0073] In this embodiment of the disclosure, it is clear that the excess air coefficient in the main combustion zone is different from that of the fuel for grading, and it is considered that the reduction of nitrogen oxides in the reduction zone requires reducing the oxygen content and reducing the ammonia oxidation reaction.

[0074] In this embodiment of the disclosure, the characteristics of the burnout zone need to be considered. Considering that biomass and NH3 are easy to burn out, the burnout wind rate can be reduced and controlled below 30%.

[0075] In this embodiment of the disclosure, the detection unit 5 includes NO x Detection probe.

[0076] In this embodiment, pulverized coal is injected into the furnace through burners 411 on the left and right sides of the main combustion zone for combustion. The burners are low-NOx burners, and the excess air coefficient of the main combustion zone is controlled at 0.85 to 0.95 to form fuel-rich combustion in the main combustion zone, with the temperature maintained at around 1300°C.

[0077] Swirling biomass sampling nozzles 412 are arranged on the front and rear sides of the furnace in the reduction zone. Biomass fuel is fed in the form of swirling flow. The calorific value of the biomass fuel fed into the furnace in the reduction zone accounts for 10% to 15% of the total calorific value of the boiler fuel, which is beneficial to reducing the formation of nitrogen-containing compounds after combustion in the reduction zone.

[0078] In this embodiment of the disclosure, the gaseous products generated in the main combustion zone 41 and the incompletely combusted solid products (such as solid coke and CO, HCN, NH4) i All gases (such as NO) enter the reduction zone 42 of the boiler, and the excess air coefficient in the reduction zone 42 is controlled at 0.75~0.85; a reducing atmosphere is formed in the reduction zone 42 due to oxygen deficiency, which can reduce NO. x Restored to N2.

[0079] In this embodiment, the reduction zone 42 is further equipped with an ammonia supply device to spray ammonia into the reduction zone (which is also a high-temperature zone) in atomized form at room temperature, which can further reduce NO in the flue gas. x It is reduced to N2. At the same time, the temperature of the reduction zone can be controlled at 900~1200℃ by injecting at room temperature, which reduces the oxidation of NH3 to NO by O2 at high temperature. By controlling the temperature, the oxidation of NH3 is reduced.

[0080] In this embodiment, the reduced flue gas and unreacted coke in the reduction zone 42 all enter the burnout zone 43. The burnout zone 43 is equipped with separate burnout air on the side wall of the furnace. At this time, the excess air coefficient of the burnout zone 43 is controlled at about 1.1, and the temperature is maintained at 850~1100℃, so that the reaction of NH3 and NOx is in the optimal reaction temperature range. The unburned and reacted flue gas and coke react completely in the burnout zone 43.

[0081] In this embodiment, the burnout zone 43 is also equipped with an ammonia supply component to further reduce the NOx that was not reduced in the reduction zone 42 and the burnout zone 43 to N2; the amount of ammonia injected into the burnout zone 43 is controlled according to the ammonia content at the tail end to reduce ammonia escape. The boiler can ultimately improve the denitrification efficiency to 75%~85%, which is higher than that of a pure coal combustion unit and a boiler that uses SNCR denitrification technology alone. While ensuring the boiler combustion efficiency, this embodiment can also solve the problem of poor SNCR denitrification performance during conventional load reduction operation.

[0082] Figure 2 A flowchart illustrating a control method for a low-NOx combustion system in a biomass co-firing boiler based on ammonia injection in a high-temperature zone, provided as an embodiment of this disclosure. See also... Figure 2 This method is used to control, such as Figure 1 The aforementioned low-NOx combustion system for a biomass co-firing boiler based on high-temperature zone ammonia injection includes:

[0083] S101. Historical operating data of the low-NOx combustion system of the biomass co-firing boiler based on ammonia injection in the high-temperature zone are obtained by periodic measurement.

[0084] Figure 3 This disclosure provides a set of historical operating data for a low-NOx combustion system of a biomass co-firing boiler based on ammonia injection in a high-temperature zone, which is provided for embodiments of this disclosure.

[0085] S102. Construct a relational expression based on historical operating data to describe the relationship between inlet parameters and outlet nitrogen oxide content.

[0086] In one example, step S102 includes:

[0087] The first step is to construct the first relation based on historical operational data. This describes the relationship between ammonia injection rate in the reduction zone, ammonia injection rate in the burnout zone, biomass input rate, burnout air rate, biomass input ratio, boiler load, total air volume, and outlet nitrogen oxide emissions. , , , , , , and The raw data for ammonia injection in the reduction zone, ammonia injection in the burnout zone, biomass input, burnout air rate, biomass input ratio, boiler load, total air volume, and outlet nitrogen oxide emissions were obtained by normalization.

[0088] In this embodiment of the disclosure, the first relation is:

[0089] ,

[0090] In the formula, and Determined based on historical operational data, , .

[0091] In this embodiment of the disclosure, by recording the specific values ​​of ammonia injection in the reduction zone, ammonia injection in the burnout zone, biomass input, burnout air rate, biomass input ratio, boiler load, total air volume and outlet nitrogen oxide emissions during boiler operation, a first relational expression is constructed by recording multiple sets of data and normalizing the data.

[0092] For example, the first relation is:

[0093] .

[0094] In this embodiment of the disclosure, the total air volume includes the burnout air volume and the primary and secondary air volumes, where the primary and secondary air volumes refer to the air that delivers pulverized coal into the burner.

[0095] In this embodiment of the disclosure, the burnout air rate is the ratio of burnout air volume to time, that is, the burnout air volume delivered per hour.

[0096] In this embodiment of the disclosure, considering the differences between different furnace detection devices in practical applications, and to avoid the influence of different dimensions and orders of magnitude between different parameters, a maximum-minimum normalization method is adopted, that is, all feature parameters are scaled to the [0,1] interval. The normalization method is as follows:

[0097] ,

[0098] in, Representative feature parameters, This represents the original value of the corresponding feature parameter. This represents the maximum value of the secondary feature parameter in the original data. This represents the minimum value of the secondary feature parameter in the original data. and middle The value range is 1 to 7.

[0099] The second step is to construct a second relation based on historical operational data. It is used to describe the relationship between biomass input amount, biomass input ratio, boiler load, and total air volume.

[0100] In this embodiment of the disclosure, the second relation is:

[0101] ,

[0102] In the formula, and Determined based on historical operational data, , .

[0103] In this embodiment, by recording the ammonia injection rate in the reduction zone, the ammonia injection rate in the burnout zone, the biomass input rate, the burnout air rate, the biomass input ratio, the boiler load, the total air volume, and the outlet nitrogen oxide emissions during boiler operation, the interaction relationship when the biomass input rate, biomass input ratio, boiler load, and total air volume change together is determined, thereby establishing a second relationship. By adjusting the biomass input rate, biomass input ratio, boiler load, and total air volume through the second relationship, the degree of change in the outlet nitrogen oxide content can be significantly determined.

[0104] For example, the second relation is:

[0105] .

[0106] The third step is to construct a third relation based on historical operational data. This is used to describe the relationship between burnout air rate, boiler load, and total air volume.

[0107] In this embodiment of the disclosure, the third relation is:

[0108] ,

[0109] In the formula, and Determined based on historical operational data, , .

[0110] For example, the third relation is

[0111] .

[0112] In this embodiment, by recording the values ​​of burnout air rate, boiler load, total air volume, and outlet nitrogen oxides during boiler operation, the interaction relationship when burnout air rate, boiler load, and total air volume change together is determined, thereby establishing a third relationship. By adjusting the burnout air rate, boiler load, and total air volume using this third relationship, it can be ensured that the change in outlet nitrogen oxide content is significant.

[0113] In this embodiment, the ammonia injection rate in the reduction zone, the ammonia injection rate in the burnout zone, the biomass input, the burnout air rate, the biomass input ratio, the boiler load, and the total air volume can all affect the outlet nitrogen oxide emissions. Individually, the ammonia injection rate in the reduction zone, the ammonia injection rate in the burnout zone, the biomass input, the burnout air rate, the biomass input ratio, the boiler load, and the total air volume will all change the outlet nitrogen oxide emissions to some extent. A first relationship is established between the ammonia injection rate in the reduction zone, the ammonia injection rate in the burnout zone, the biomass input, the burnout air rate, the biomass input ratio, the boiler load, and the total air volume. Individual changes in the biomass input, the biomass input ratio, the boiler load, and the total air volume can affect the outlet nitrogen oxide emissions. When the biomass input, the biomass input ratio, the boiler load, and the total air volume change together, the change in outlet nitrogen oxide emissions is greater. A second relationship is established to describe the interaction when the biomass input, the biomass input ratio, the boiler load, and the total air volume change together. Similarly, the change in nitrogen oxide emissions at the outlet will be greater when the burnout air rate, boiler load, and total air volume change together. A third relationship is constructed to describe the interaction of these factors when they change together. By clarifying the correlation between boiler combustion parameters through this relationship, automatic boiler control can be achieved, ensuring low nitrogen oxide emissions at the boiler outlet.

[0114] S103. Obtain the content of nitrogen oxides at the outlet detected by the detection unit.

[0115] S104. When the outlet nitrogen oxide emissions do not meet the requirements, the control unit generates control commands based on the relational formula to adjust the inlet parameters.

[0116] In one example, step S103 includes:

[0117] When the emission of nitrogen oxides at the export site does not meet the requirements, the ammonia injection rate in the reduction zone, the ammonia injection rate in the burnout zone, the biomass input rate, the burnout wind rate, and the biomass input ratio shall be adjusted according to the first to third relationship formulas.

[0118] In this embodiment of the disclosure, precise control of nitrogen oxide emissions at the boiler outlet can be achieved through the first to third relationships. When the nitrogen oxide emissions at the boiler outlet do not meet the requirements, the boiler's combustion parameters can be quickly adjusted to reduce the nitrogen oxide emissions at the boiler outlet.

[0119] 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method for a low-NOx combustion system in a biomass co-firing boiler based on high-temperature ammonia injection, characterized in that, The low-NOx combustion system of a biomass co-firing boiler based on high-temperature ammonia injection includes: Feeding assembly, used to supply fuel; Ammonia supply assembly, used to supply ammonia; Gas supply components, used to provide oxygen or air; The boiler is divided into a main combustion zone, a reduction zone, and a burnout zone according to its height. The main combustion zone is equipped with a burner, which receives fuel from the fuel supply assembly and performs fuel-rich combustion. The reduction zone receives ammonia from the ammonia supply assembly and performs oxygen-deficient combustion of the flue gas and incompletely burned fuel from the main combustion zone with the ammonia. The burnout zone receives oxygen or air from the air supply assembly and ammonia from the ammonia supply assembly, and performs oxygen-rich combustion of the flue gas and incompletely burned fuel from the reduction zone with the ammonia, air, or oxygen. The detection unit is used to detect the content of nitrogen oxides in the burnout zone; The control unit is used to control the feeding assembly, ammonia supply assembly, and gas supply assembly based on the content of nitrogen oxides in the burnout zone. The control methods for low-NOx combustion systems in biomass co-firing boilers based on high-temperature ammonia injection include: Historical operating data of the low-NOx combustion system of a biomass co-firing boiler based on ammonia injection in the high-temperature zone were obtained through periodic measurements. A relational expression was constructed based on historical operating data to describe the relationship between inlet parameters and outlet nitrogen oxide content; Obtain the content of nitrogen oxides at the outlet detected by the detection unit; When the nitrogen oxide emissions at the outlet do not meet the requirements, the control unit generates control commands based on the relational formula to adjust the inlet parameters; A relational expression is constructed to describe the relationship between inlet parameters and the amount of nitrogen oxides at the outlet, including: The first relation is constructed based on historical operating data. This describes the relationship between ammonia injection rate in the reduction zone, ammonia injection rate in the burnout zone, biomass input rate, burnout air rate, biomass input ratio, boiler load, total air volume, and outlet nitrogen oxide emissions. , , , , , , and The raw data of ammonia injection in the reduction zone, ammonia injection in the burnout zone, biomass input, burnout air rate, biomass input ratio, boiler load, total air volume and outlet nitrogen oxide emissions were obtained by normalization. Construct a second relation based on historical operating data. This is used to describe the relationship between biomass input amount, biomass input ratio, boiler load, and total air volume; Construct a third relation based on historical operating data. This is used to describe the relationship between burnout air rate, boiler load, and total air volume; When the outlet nitrogen oxide emissions do not meet the requirements, the control unit generates control commands based on the relational formula to adjust the inlet parameters, including: When the nitrogen oxide emissions at the export site do not meet the requirements, the ammonia injection rate in the reduction zone, the ammonia injection rate in the burnout zone, the biomass input rate, the burnout wind rate, and the biomass input ratio shall be adjusted according to the first to third relationships.

2. The control method for a low-NOx combustion system in a biomass co-firing boiler based on high-temperature ammonia injection according to claim 1, characterized in that, The feeding assembly includes: The pulverized coal feeding assembly and the biomass fuel feeding assembly are used to supply pulverized coal and biomass fuel, respectively; The biomass fuel supply unit injects the biomass fuel into the reduction zone, where it is burned with the products formed after combustion in the main combustion zone. The amount of biomass fuel supplied by the biomass fuel feeding assembly is determined based on 10% to 15% of the total fuel calorific value.

3. The control method for a low-NOx combustion system in a biomass co-firing boiler based on high-temperature ammonia injection according to claim 1, characterized in that, The excess air coefficient in the main combustion zone is 0.85~0.95, and the excess air coefficient in the reduction zone is 0.75~0.

85.

4. The control method for a low-NOx combustion system in a biomass co-firing boiler based on high-temperature ammonia injection according to claim 2, characterized in that, The temperature range for ammonia injection in the reduction zone is 1000℃~1200℃, and the temperature range for ammonia injection in the combustion zone is 850℃~1100℃. The ammonia injection in the reduction zone is located below the biomass fuel feeding assembly, and the ammonia injection in the combustion zone is located below the gas supply assembly.

5. The control method for a low-NOx combustion system in a biomass co-firing boiler based on high-temperature ammonia injection according to claim 1, characterized in that, The first relation is: ， In the formula, and Determined based on historical operational data, , .

6. The control method for a low-NOx combustion system in a biomass co-firing boiler based on high-temperature ammonia injection according to claim 1, characterized in that, The second relation is: ， In the formula, and Determined based on historical operational data, , .

7. The control method for a low-NOx combustion system in a biomass co-firing boiler based on high-temperature ammonia injection according to claim 1, characterized in that, The third relation is: ， In the formula, and Determined based on historical operational data, , .

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