Method for quickly adjusting ammonia injection concentration uniformity in SCR (Selective Catalytic Reduction) denitration

Abstract

The invention discloses an SCR denitration ammonia injection concentration uniformity rapid adjustment method, and relates to the technical field of thermal power unit SCR (selective catalytic reduction) flue gas denitration. The method comprises the following steps that S1, unit load intervals are divided, limiting parameters of all the load intervals are set, and the load intervals at least comprise the load interval 1 (20%-35%), the load interval 2 (35%-50%), the load interval 3 (50%-65%), the load interval 4 (65%-80%) and the load interval 5 (80%-100%); according to hardware, the double-row trapped vortex mixing system reduces flow field disturbance caused by flue diameter change by optimizing vortex plates and additionally arranging spoilers, and the smoke flow deviation of the left side and the right side is reduced by more than 40%; in software, a strategy is formulated according to the load in five intervals, for example, when the load fluctuation in the interval (50-65%) is smaller than 10 MW and is stabilized for 10 minutes, adjustment is conducted, the non-uniformity of the ammonia concentration of a catalyst inlet is smaller than 10%, and air pre-heater blockage and NOx standard exceeding are avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flue gas denitrification technology of SCR (selective catalytic reduction) of thermal power generating units, and particularly relates to a method for quickly adjusting the uniformity of ammonia injection concentration of SCR denitrification. BACKGROUND

[0002] As an important part of the power system, the SCR denitrification system of a thermal power generating unit is a key equipment for controlling NOx emission. With the increasing requirements of the state for environmental protection and the increasing demand for deep load regulation of the unit, the existing SCR denitrification system gradually exposes many problems. On the one hand, due to the design of the variable-diameter and the expansion-diameter of the denitrification inlet flue, the flue gas flow field distribution is uneven, which further causes insufficient mixing of ammonia and flue gas, large deviation of ammonia concentration distribution at the inlet of the catalyst, excessive ammonia injection in some areas, which causes the blockage of the air preheater and the increase of the power consumption of the induced draft fan, and insufficient ammonia injection in some areas, which causes the NOx emission to exceed the standard. On the other hand, the traditional single-point sampling method is not representative, and cannot accurately reflect the NOx concentration distribution at the outlet of the denitrification. Moreover, the control system lacks an effective feedforward regulation mechanism. When the load of the unit changes rapidly (such as AGC-R mode), the ammonia injection adjustment lags behind, it is difficult to maintain the uniformity of the ammonia injection concentration, which leads to high ammonia consumption and increased operating costs.

[0003] In the prior art, the accuracy of ammonia injection and the uniformity of the flow field of the denitrification system are significantly improved, but the existing system has the following problems: Uneven flue gas flow field: due to the design of the variable-diameter and the expansion-diameter of the denitrification inlet flue, the left and right side flue gas flow deviates, and the ammonia distribution deviation is further enlarged when the load of the unit fluctuates, which causes uneven ammonia concentration distribution in the catalyst region, excessive ammonia in some areas, and insufficient ammonia in some areas.

[0004] Poor sampling representativeness: the original CEMS at the outlet of the SCR uses single-point sampling, which cannot reflect the NOx concentration distribution of the whole cross section, which easily leads to lagging ammonia injection adjustment and causes ammonia over-injection or NOx exceeding the standard at the total discharge port.

[0005] Regulation response lag: the traditional ammonia injection control system relies on manual intervention. In the AGC-R mode (load change rate 7MW / min) of the unit and the coal switching condition, it cannot quickly match the condition change, which leads to high ammonia consumption (average ammonia consumption 750.5kg / h @ 227.9MW load before the transformation), and excessive ammonia injection causes the increase of the resistance of the air preheater, the increase of the power consumption of the induced draft fan, and other problems.

[0006] In order to solve the above problems, the existing technology mainly adopts single flow field optimization or ammonia injection grid transformation, but lacks a full-process adjustment scheme combined with the dynamic change of the load, and it is difficult to realize the quick and stable control of the uniformity of ammonia concentration under wide load conditions. Therefore, an integrated method combining load segmented control, accurate sampling monitoring and intelligent adjustment is urgently needed to realize the quick and dynamic optimization of the uniformity of ammonia injection concentration of the SCR denitrification. SUMMARY

[0007] To achieve the above object, the present application provides the following technical solution: A SCR denitration ammonia injection concentration uniformity rapid adjustment method, comprising the following steps: S1: Dividing the unit load range, setting the limit parameters of each load range, the load range at least includes load range 1: (20%-35%], load range 2: (35%-50%], load range 3: (50%-65%], load range 4: (65%-80%], load range 5: (80%-100%]; S2: In each load range, when the SCR outlet NOx concentration distribution deviation is <20%, the opening of each sub-zone ammonia injection branch valve in the inlet sub-zone ammonia injection adjustment module is calibrated, and the preset valve opening data corresponding to each load range is obtained; S3: Real-time monitoring of the current load B of the unit, judging whether to put into sub-zone variable load following adjustment; if put in, step 4 is entered; if not put in, the current ammonia injection adjustment state is maintained; S4: Identifying the target load range to which the current load B of the unit belongs, and when the load B is in the target load range for 5 minutes, the corresponding sub-zone adjustment subprogram is executed: If the target load range is load range 1: (20%-35%], the preset valve opening corresponding to the load range is transported to each valve opening command output end in the order of "from large to small", and the variable load rapid adjustment is completed; If the target load range is load range 2: (35%-50%], judging whether to put into sub-zone fine adjustment; if put in, step 5 is executed; if not put in, the current ammonia injection adjustment state is maintained; If the target load range is load range 3: (50%-65%], the load fluctuation is monitored, and when the load fluctuation is <10 MW and lasts for 10 minutes, step 5 is executed; If the target load range is load range 4: (65%-80%], the SCR outlet sub-zone NOx concentration monitoring is started, and step 5 is executed based on the monitoring data; If the target load range is load range 5: (80%-100%], the big data-artificial intelligence analysis is started, and step 5 is executed based on the analysis result; S5: In the sub-zone fine adjustment process, the SCR outlet NOx concentration distribution deviation is monitored in real time, and when the concentration distribution deviation is <20% or the number of back measurement adjustment reaches 5 times, the sub-zone adjustment subprogram is ended.

[0008] Preferably, the division of the load range in step S1 is based on historical operation data of the unit, denitration inlet flue gas parameters, and SCR reactor flow field characteristics, and the denitration inlet flue gas parameters include flue gas volume, flue gas temperature, NOx initial concentration, O2 volume fraction, and flue gas composition proportion.

[0009] Preferably, the inlet partition ammonia injection adjustment module in step S2 includes a double-row vortex mixing system, which realizes the staged multi-effect mixing of ammonia and flue gas by changing the vortex plate structure form, adding a vertical shaft flue top spoiler, and increasing the number of ammonia injection ports.

[0010] Preferably, the valve opening calibration in step S2 adopts a combination of CFD numerical simulation and field measurement, first obtains the theoretical valve opening corresponding to the uniform distribution of ammonia concentration in each load range through CFD simulation, and then corrects it by combining the multi-point sampling data at the SCR outlet full section to obtain the final preset valve opening.

[0011] Preferably, the SCR outlet partition NOx concentration monitoring in step S4 is realized by a full-section multi-point sampling device, which adopts a grid method to uniformly distribute not less than 8 sampling points on the measurement section, including a mixed sampling grid sampling device arranged at 27.9 meters in front of the denitration outlet flue and a patrol sampling device arranged at 34 meters behind the denitration reactor outlet, and the sampling device is provided with a timing anti-blocking backwashing system, and the backwashing gas source is high-temperature compressed air heated to above 250℃ through the flue wall.

[0012] Preferably, the sample gas transmission pipeline of the full-section multi-point sampling device is arranged close to the flue wall, and the high-temperature flue gas heat exchange is used to maintain the sample gas transmission temperature above 260℃, and after the sample gas enters the multi-component measuring device, the real-time measurement of NOx and O2 concentration is realized simultaneously.

[0013] Preferably, the big data-artificial intelligence analysis in step S4 constructs a weight matrix of input (ammonia injection branch valve opening) and output (partition NOx measurement concentration) based on historical operation data, inversely predicts the valve opening adjustment amount through the weight matrix, and realizes accurate control of the partition NOx concentration.

[0014] Preferably, it further includes a feedforward control optimization step: selecting parameters with high correlation with boiler operation as feedforward signals, the feedforward signals including boiler load change rate, coal consumption, received volatile matter, and low calorific value, and connecting the feedforward signals to the ammonia injection total amount control system after preprocessing, to adapt to the working condition demand of the load change rate of 7MW / min in the AGC-R mode of the unit.

[0015] Preferably, the return measurement adjustment in step S5 adopts a "monitoring-adjusting-remonitoring" cycle mechanism, and the SCR outlet NOx concentration distribution is re-measured 3-5 minutes after each adjustment until the concentration distribution deviation requirement is met or the maximum number of adjustments is reached.

[0016] Preferably, when the method is applied to the SCR denitration system of a 330 MW combined heat and power unit, the relative standard deviation of the flue gas inlet flow velocity distribution on the upper surface of the first layer of catalyst of the SCR reactor is not greater than 10%, the non-uniformity of the ammonia concentration distribution is less than 10%, the total amount of ammonia injection is reduced by more than 15% compared with before the transformation, and the total exhaust NOx concentration fluctuation is controlled within ±15mg / Nm 3 within 90% of the time under the AGC-R mode.

[0017] Beneficial effects: Compared with the prior art, the beneficial effects of the present application are: 1. On the hardware, the double-row vortex mixing system reduces the flow field disturbance caused by the flue diameter change by optimizing the vortex plate and adding the spoiler, and the left and right side flue gas flow deviation is reduced by more than 40%; on the software, the strategy is formulated according to 5 intervals of load, such as (50%-65%] interval, the load fluctuation is less than 10MW and stable for 10 minutes before adjustment, so that the non-uniformity of the catalyst inlet ammonia concentration is less than 10%, avoiding the air preheater blockage and NOx exceeding.

[0018] 2. The full cross-section grid method arranges ≥8 measuring points, the sample gas transmission pipe is attached to the flue wall, the NOx measurement error is reduced to ±5% (traditional ±15%), and the 10 measuring points of the 330 MW unit can accurately identify the concentration difference, providing reliable data for adjustment, and the NOx fluctuation is less than or equal to ±15mg / Nm 3 within 90% of the time under the AGC-R mode.

[0019] 3. The feedforward control responds to load and coal type changes 0.5-1 minutes in advance; the AI analysis in the high load interval predicts the valve opening within 10 seconds, which is 180-360 times faster than manual adjustment. The ammonia consumption of the 330 MW unit is reduced by 15%+ compared with before the transformation (750.5kg / h@227.9MW), saving 150,000 yuan per year, and reducing the induced draft fan power consumption.

[0020] 4. An integrated scheme of "segmentation-monitoring-adjustment-optimization" is constructed, covering 20%-100% load, synchronously solving three major pain points, and guaranteeing the system stability during deep peak shaving and coal type switching. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The software algorithm of the SCR denitration ammonia injection concentration uniformity rapid adjustment method of the present application is a partition variable load following adjustment and partition fine adjustment program flow chart.

[0022] Figure 2The figure is an improved layout of the structure related to the flow field optimization and ammonia injection control of the SCR denitration system in the ammonia injection concentration uniformity rapid adjustment method of the SCR denitration. DETAILED DESCRIPTION

[0023] The technical solutions of the patent will be further described in detail in combination with specific embodiments.

[0024] Embodiment 1 Please refer to the drawings in the specification, in the embodiment of the present application, an ammonia injection concentration uniformity rapid adjustment method of SCR denitration, comprising the following steps: 1. Load interval division and limit parameter setting (S1) The load interval is divided, and the limit parameters of each load interval are set. The load interval at least includes load interval 1: (20%-35%], load interval 2: (35%-50%], load interval 3: (50%-65%], load interval 4: (65%-80%], and load interval 5: (80%-100%].

[0025] The division of the load interval is based on the historical operation data of the unit, the denitration inlet flue gas parameters and the flow field characteristics of the SCR reactor. The denitration inlet flue gas parameters include flue gas volume, flue gas temperature, NOx initial concentration, O2 volume fraction and flue gas composition ratio. By combining the above multi-dimensional parameters to divide the load interval, the working condition characteristics in each interval can be ensured to be relatively stable, thereby providing accurate working condition basis for subsequent ammonia injection adjustment.

[0026] 2. Valve opening calibration (S2) In each load interval, when the SCR outlet NOx concentration distribution deviation is <20%, the opening of each sub-zone ammonia injection branch valve in the inlet sub-zone ammonia injection adjustment module is calibrated to obtain the preset valve opening data corresponding to each load interval.

[0027] The inlet sub-zone ammonia injection adjustment module includes a double-row vortex mixing system. The double-row vortex mixing system can realize the staged multi-effect mixing of ammonia and flue gas by changing the vortex plate structure form, adding a vertical shaft flue top disturbance plate and increasing the number of ammonia injection ports. Compared with the traditional single-row ammonia injection system, the double-row vortex mixing system can significantly improve the mixing efficiency of ammonia and flue gas and reduce the local ammonia concentration deviation.

[0028] The valve opening calibration method: the CFD numerical simulation and field measurement are combined. First, the theoretical valve opening corresponding to the ammonia concentration uniform distribution under each load interval is obtained by CFD simulation. Then, the final preset valve opening is obtained by combining the SCR outlet full-section multi-point sampling data for correction. This "simulation + measurement" calibration method can effectively make up for the deviation between pure theoretical calculation and actual working condition, and ensure the accuracy of the preset valve opening.

[0029] 3. Variable load following adjustment input judgment (S3) Real-time monitoring of the current load B of the unit, and judging whether to input the variable load following adjustment; if yes, go to step 4; if not, maintain the current ammonia injection adjustment state.

[0030] By setting the variable load following adjustment input judgment link, the adjustment mode can be flexibly selected according to the actual operation demand of the unit. For example, when the unit load is in a stable operation state and the NOx concentration distribution deviation meets the requirements, the variable load following adjustment can be temporarily not input to reduce unnecessary operation of the system; when the unit load fluctuates or the NOx concentration distribution deviation exceeds the standard, the adjustment is timely input to ensure the stable operation of the denitration system.

[0031] 4. Target load interval identification and subprogram execution of partition adjustment (S4) Identify the target load interval to which the current load B of the unit belongs, and when the load B is in the target load interval for 5 minutes, execute the corresponding subprogram of partition adjustment, as follows: Load interval 1: (20%-35%]: This load interval belongs to low load condition, and the flue gas volume is small, so the mixing of ammonia and flue gas is relatively low. Therefore, the pre-set valve opening corresponding to this load interval is delivered to each valve opening command output in the order of "from large to small", which can complete the variable load fast adjustment without additional fine adjustment steps, effectively improving the adjustment efficiency.

[0032] Load interval 2: (35%-50%]: Judgment whether to input the partition fine adjustment; if yes, execute step 5; if not, maintain the current ammonia injection adjustment state. The working condition of this load interval is relatively complex, and whether to perform fine adjustment needs to be flexibly selected according to the actual NOx concentration distribution to balance the adjustment accuracy and efficiency.

[0033] Load interval 3: (50%-65%]: Monitor the load fluctuation, and when the load fluctuation <10 MW and lasts for 10 minutes, execute step 5. In this load interval, the load fluctuation has a significant impact on the ammonia concentration distribution, so fine adjustment needs to be performed after ensuring the load stability to avoid poor adjustment effect due to load fluctuation.

[0034] Load interval 4: (65%-80%]: Start monitoring the NOx concentration at the outlet of the SCR, and execute step 5 based on the monitoring data. This load interval belongs to medium and high load condition, and the flue gas parameters change rapidly, so the NOx concentration distribution needs to be monitored in real time to provide data support for fine adjustment and ensure the accuracy of the adjustment.

[0035] The SCR outlet partition NOx concentration monitoring is realized by a full cross-section multi-point sampling device, the sampling device adopts a grid method to uniformly distribute no less than 8 sampling measuring points on the measuring cross-section, and can comprehensively and accurately reflect the distribution of the SCR outlet NOx concentration. Meanwhile, the sample gas transmission pipeline of the full cross-section multi-point sampling device is arranged close to the flue wall, which can effectively reduce the temperature loss and composition change of the sample gas in the transmission process, and further improve the accuracy of the monitoring data.

[0036] Load interval 5: (80%-100%]: Start big data-artificial intelligence analysis, and execute step 5 based on the analysis result. The load interval is a high load working condition, and the requirement for the denitration effect is the most stringent, and an intelligent analysis method needs to be used to realize accurate adjustment.

[0037] The big data-artificial intelligence analysis constructs a weight matrix of input (ammonia injection branch valve opening) and output (partition NOx measured concentration) based on historical operation data, inversely predicts the valve opening adjustment amount through the weight matrix, and realizes accurate control of the partition NOx concentration. This intelligent analysis method can fully tap the potential law in the historical operation data, quickly respond to working condition changes, and significantly improve the adjustment accuracy and speed.

[0038] 5. Partition fine adjustment (S5) In the partition fine adjustment process, the SCR outlet NOx concentration distribution deviation is monitored in real time, and when the concentration distribution deviation is <20% or the retest adjustment times reach 5 times, the partition adjustment subprogram is ended.

[0039] The retest adjustment adopts a "monitoring-adjustment-remonitoring" circulation mechanism, the SCR outlet NOx concentration distribution is retested after each adjustment for 3-5 minutes, until the concentration distribution deviation requirement is met or the maximum adjustment times are reached. The retest adjustment link is set, the adjustment effect can be verified in time, and secondary adjustment is carried out according to the retest result, so that the final ammonia concentration distribution deviation meets the requirement. At the same time, limiting the maximum adjustment times can avoid the adjustment process from being in infinite circulation due to system failure or other abnormal conditions, and improve the stability of the system.

[0040] 6. Feedforward control optimization step The present application also includes a feedforward control optimization step: selecting parameters with high correlation with boiler operation as feedforward signals, the feedforward signals include boiler load change rate, coal consumption, received base volatile matter and low calorific value, and the feedforward signals are pretreated and connected to the ammonia injection total amount control system.

[0041] By introducing feedforward control, the influence of boiler operating parameter changes on the SCR denitration system can be predicted in advance, and the total ammonia injection amount can be adjusted in time to avoid the problem of excessive or insufficient ammonia injection caused by parameter lag. For example, when the boiler load change rate increases, the feedforward signal can trigger the adjustment of the total ammonia injection amount in advance to ensure that the ammonia injection amount has been adjusted to an appropriate level before the flue gas parameters change, further improving the stability and response speed of the denitration system.

[0042] (I) Unit parameters and system configuration The 330 MW cogeneration unit boiler is a pulverized coal boiler, which is matched with a single reactor SCR denitration system. The inlet zoning ammonia injection adjustment module uses a double-row vortex mixing system, and 8 ammonia injection zones are set, each corresponding to one electric regulating valve. The SCR outlet is provided with a full-section multi-point sampling device, which uses a grid method to arrange 10 sampling measurement points, and the sample gas transmission pipeline is arranged close to the flue wall. The big data-artificial intelligence analysis system constructs a weight matrix based on the historical operation data of the unit in the past three years, including the ammonia injection valve opening and NOx concentration distribution data under different loads, different coal types, and different flue gas parameters.

[0043] (II) Implementation steps Load interval division and limit parameter setting: According to the historical operation data of the unit, the denitration inlet flue gas parameters (flue gas volume range: 800000-1500000 Nm 3 / h, flue gas temperature range: 300-400℃, NOx initial concentration range: 300-600 mg / Nm 3 ) and the SCR reactor flow field characteristics, the load interval is divided into: (20%-35%], (35%-50%], (50%-65%], (65%-80%], (80%-100%], and the flue gas parameter limit range of each interval is set.

[0044] Valve opening calibration: The theoretical valve opening corresponding to the uniform distribution of ammonia concentration under each load interval is obtained by CFD numerical simulation, for example, in the load interval (50%-65%], the theoretical calculation obtains the valve opening of each zone: zone 1 45%, zone 2 42%, zone 3 40%, zone 4 38%, zone 5 38%, zone 6 40%, zone 7 42%, zone 8 45%; combined with the sampling data of the 10 measurement points at the SCR outlet full-section, the final preset valve opening of this load interval is determined as: zone 1 43%, zone 2 40%, zone 3 39%, zone 4 37%, zone 5 37%, zone 6 39%, zone 7 40%, zone 8 43%.

[0045] Variable load following adjustment input: Real-time monitoring of the current load of the unit, when the load increases from 30% to 40%, the variable load following adjustment input zone is judged.

[0046] Target load interval identification and adjustment: After the unit load is stabilized at 40% (belonging to the load interval 2: (35%-50%]) for 5 minutes, it is judged to input the partition fine adjustment, and step 5 is executed.

[0047] Partition fine adjustment: Start the SCR outlet partition NOx concentration monitoring, and the current NOx concentration distribution deviation is measured to be 25%, which exceeds the required range. According to the cycle mechanism of "monitoring-adjusting-remonitoring", the valve opening of each partition is adjusted for the first time (for example, the valve opening of the 1st zone and the 8th zone with higher concentration is reduced by 2%, and the valve opening of the 4th zone and the 5th zone with lower concentration is increased by 2%), and the NOx concentration distribution deviation is reduced to 22% after 4 minutes of interval retesting. After the second adjustment and retesting, the deviation is reduced to 18%, which meets the requirement of concentration distribution deviation < 20%, and the partition adjustment subprogram is ended.

[0048] Feedforward control optimization: The boiler load change rate, coal consumption, received base volatile matter and low calorific value are selected as feedforward signals, and after the signals are filtered, normalized and pretreated, they are connected to the ammonia injection amount control system. When the boiler coal consumption increases from 120 t / h to 130 t / h, the feedforward signal triggers the ammonia injection amount adjustment in advance, avoiding the large fluctuation of NOx concentration.

[0049] (Three) Application effect After the 330 MW combined heat and power unit adopts the SCR denitration ammonia injection concentration uniformity rapid adjustment method of the application, the operation effect is significantly improved: The relative standard deviation of the flue gas inlet flow velocity distribution on the upper surface of the first layer of catalyst of the SCR reactor is controlled within 8%, and the ammonia concentration distribution non-uniformity is reduced to 9%, which is much better than the industry average level; The total ammonia injection amount is reduced by 16.5% compared with before the transformation, the ammonia water consumption is reduced by about 200 tons per year, and the operation cost is reduced by about 150,000 yuan per year; In the AGC-R mode, the total exhaust port NOx concentration fluctuation is controlled within ±12 mg / Nm 3 for more than 92% of the time, fully meeting the requirements of the national ultra-low emission standard, and no catalyst poisoning, air preheater blockage and other faults occur, and the system operation stability is greatly improved.

[0050] In summary, on the hardware, the double-row vortex mixing system reduces the flow field disturbance caused by the flue diameter change by optimizing the vortex plate and adding spoiler, and the left and right side flue gas flow deviation is reduced by more than 40%; on the software, the strategy is formulated according to 5 intervals according to the load, such as (50%-65%] interval, the load fluctuation is less than 10MW and stable for 10 minutes, then adjust, so that the ammonia concentration non-uniformity of the catalyst inlet is less than 10%, avoiding the air preheater blockage and NOx exceeding. The full cross-section grid method arranges ≥8 measuring points, the sample gas transmission pipe is attached to the flue wall, the NOx measurement error is reduced to ±5% (traditional ±15%), and the 10 measuring points of the 330MW unit can accurately identify the concentration difference, providing reliable data for adjustment, and the NOx fluctuation is less than or equal to ±15mg / Nm 90% of the time under AGC-R mode. 3 The feedforward control responds to load and coal variety changes in advance by 0.5-1 minutes; the AI analysis in the high load interval predicts the valve opening within 10 seconds, which is 180-360 times faster than manual adjustment. The ammonia consumption of the 330MW unit is reduced by 15%+ compared with that before the transformation (750.5kg / h@227.9MW), which saves 150,000 yuan per year, and reduces the induced draft fan power consumption. The "segmentation-monitoring-adjustment-optimization" integrated scheme is constructed, covering 20%-100% load, synchronously solving the three major pain points, and ensuring the system stability during deep peak shaving and coal variety switching.

[0051] The above is only the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the concept of the present application, can make several modifications and improvements, these should be considered as the protection scope of the present application, these will not affect the effect and practicality of the present application.

Claims

1. A method for rapidly adjusting the uniformity of ammonia concentration in SCR denitrification, characterized in that, Includes the following steps: S1: Divide the unit load range and set the limiting parameters for each load range. The load range shall include at least load range 1, load range 2, load range 3, load range 4, and load range 5. S2: In each load range, when the NOx concentration distribution deviation at the SCR outlet is <20%, the opening degree of the electric regulating valve of the ammonia injection branch pipe in each zone of the inlet zone ammonia injection regulating module is calibrated to obtain the preset valve opening degree data corresponding to each load range. S3: Real-time monitoring of the unit's current load B, determining whether to activate zoned load shifting adjustment; If ammonia is injected, proceed to step 4; if not, maintain the current ammonia injection adjustment status. S4: Identify the target load range to which the current load B of the unit belongs, and when load B remains within the target load range for 5 minutes, execute the corresponding zonal adjustment subroutine: If the target load range is load range 1, the preset valve openings corresponding to that load range are sent to the valve opening command output terminals in descending order to complete the rapid adjustment of variable load. If the target load range is load range 2, determine whether to implement zoned fine-tuning; If activated, proceed to step 5; if not activated, maintain the current ammonia injection adjustment status. If the target load range is load range 3, monitor the load fluctuation. When the load fluctuation is <10MW and lasts for 10 minutes, proceed to step 5. If the target load range is load range 4, start SCR outlet zone NOx concentration monitoring and execute step 5 based on the monitoring data; If the target load range is load range 5, initiate big data-artificial intelligence analysis and execute step 5 based on the analysis results; S5: During the fine-tuning of the zoning, monitor the NOx concentration distribution deviation at the SCR outlet in real time. When the concentration distribution deviation is <20% or the number of retest adjustments reaches 5, end the zoning adjustment subroutine.

2. The method for rapidly adjusting the uniformity of ammonia concentration in SCR denitrification according to claim 1, characterized in that: The division of the load range in step S1 is based on the unit's historical operating data, the denitrification inlet flue gas parameters, and the flow field characteristics of the SCR reactor. The denitrification inlet flue gas parameters include flue gas volume, flue gas temperature, initial NOx concentration, O2 volume fraction, and flue gas composition ratio.

3. The method for rapidly adjusting the uniformity of ammonia concentration in SCR denitrification according to claim 1, characterized in that: The inlet zone ammonia injection adjustment module mentioned in step S2 includes a dual-row vortex mixing system. The dual-row vortex mixing system achieves multi-stage mixing of ammonia and flue gas by changing the structure of the vortex plate, adding a baffle plate on the top of the vertical flue, and increasing the number of ammonia injection ports.

4. The method for rapidly adjusting the uniformity of ammonia concentration in SCR denitrification according to claim 1, characterized in that: The valve opening calibration in step S2 adopts a combination of CFD numerical simulation and field measurement. First, the theoretical valve opening corresponding to the uniform distribution of ammonia concentration under each load range is obtained through CFD simulation. Then, the valve opening is corrected by combining the multi-point sampling data of the full cross section of the SCR outlet to obtain the final preset valve opening.

5. The method for rapidly adjusting the uniformity of ammonia concentration in SCR denitrification according to claim 1, characterized in that: The NOx concentration monitoring of the SCR outlet zone in step S4 is achieved by a full-section multi-point sampling device, which uses a grid method to evenly distribute no less than 8 sampling points on the measurement section.

6. The method for rapidly adjusting the uniformity of ammonia concentration in SCR denitrification according to claim 2, characterized in that: The sample gas transmission pipeline of the full-section multi-point sampling device is arranged close to the flue wall.

7. The method for rapidly adjusting the uniformity of ammonia concentration in SCR denitrification according to claim 1, characterized in that: The big data-artificial intelligence analysis described in step S4 constructs a weight matrix of input (opening degree of ammonia injection branch pipe valve) and output (regional NOx measurement concentration) based on historical operating data. The valve opening adjustment amount is predicted in reverse through the weight matrix to achieve precise control of regional NOx concentration.

8. The method for rapidly adjusting the uniformity of ammonia concentration in SCR denitrification according to claim 1, characterized in that: It also includes a feedforward control optimization step: selecting parameters that are highly correlated with boiler operation as feedforward signals, including boiler load change rate, coal consumption, received volatile matter and lower heating value, and connecting the feedforward signals to the ammonia injection total control system after preprocessing.

9. The method for rapidly adjusting the uniformity of ammonia concentration in SCR denitrification according to claim 1, characterized in that: The retesting and adjustment described in step S5 adopts a "monitoring-adjustment-remonitoring" cyclic mechanism. After each adjustment, the NOx concentration distribution at the SCR outlet is retested every 3-5 minutes until the concentration distribution deviation requirement is met or the maximum number of adjustments is reached.

10. The method for rapidly adjusting the uniformity of ammonia concentration in SCR denitrification according to claim 1, characterized in that: When applied to the SCR denitrification system of a 330MW cogeneration unit, this method can ensure that the relative standard deviation of the flue gas inlet velocity distribution on the upper surface of the first catalyst layer of the SCR reactor is no more than 10%, the ammonia concentration non-uniformity is less than 10%, the total ammonia injection is reduced by more than 15% compared with before the modification, and the NOx concentration fluctuation at the total discharge outlet is controlled within ±15mg / Nm³ for more than 90% of the time under AGC-R mode. 3 Within.

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