An SCR sub-region ammonia injection control method adaptive to wide load variation

Abstract

This application relates to the field of flue gas denitrification technology in coal-fired power plants, and particularly to a SCR zone ammonia injection control method adaptable to wide load variations. The method includes: acquiring boiler load signals; identifying the current load change pattern and current load mode of the boiler based on the load signals; determining a target full-load range control parameter preset table; determining the target control parameters for each ammonia injection zone from the target full-load range control parameter preset table based on the current load mode; determining the adjustment parameters for each ammonia injection zone based on the current load change pattern; and controlling the ammonia injection zone of the selective catalytic reduction denitrification system to inject ammonia according to the target control parameters and adjustment parameters for each ammonia injection zone. This solves the problem that current SCR zone ammonia injection control methods are difficult to adapt to rapid load changes in coal-fired power units and have poor hardware configuration matching, enabling the selective catalytic reduction denitrification system to adapt to the rapid load change requirements of coal-fired power units and has a wide range of applications.

Description

Technical Field

[0001] This application relates to the field of flue gas denitrification technology in coal-fired power plants, and in particular to a method for SCR zone ammonia injection control that adapts to wide load variations. Background Technology

[0002] With the increasing proportion of renewable energy power generation, coal-fired power units are undertaking increasingly important peak-shaving tasks. The operation of these units is characterized by a wide load range, frequent changes, and high rates of load increase and decrease, placing higher demands on the SCR denitrification ammonia injection control.

[0003] SCR denitrification systems inject ammonia into flue gas, where it reacts with nitrogen oxides under the action of a catalyst to produce nitrogen and water. Due to the uneven NOx distribution across the flue gas duct cross-section, modern large-scale units generally employ zoned ammonia injection grids, dividing the ammonia injection area into multiple independently controlled zones. Each zone has an independent regulating valve, allowing for independent adjustment of the ammonia injection rate based on the NOx concentration at the zone's outlet. This achieves uniform NOx distribution across the entire cross-section, reducing overall ammonia consumption and ammonia slip.

[0004] Currently, commonly used zoned ammonia injection control methods mainly include traditional PID feedback control and model predictive control. Traditional PID feedback control uses the outlet NOx concentration as the feedback signal, adjusts the total ammonia injection, and then distributes it to each zone in a fixed proportion. However, it suffers from response lag and difficulty in adapting to rapid load changes. Model predictive control, while offering higher accuracy, has complex algorithms and strong dependence on the model, making it difficult to implement in existing DCS systems.

[0005] Furthermore, on-site ammonia injection optimization tests are a standard technical method in power plants. By adjusting valve openings, the NOx distribution at the outlet is made more uniform, and the optimal valve position is obtained under different loads. However, the results of these tests are often only used for offline guidance and are not fully integrated into the automatic control logic. They also lack sufficient consideration for adaptability to different load change rates and lack specific handling for the special characteristics of low-load conditions.

[0006] Meanwhile, the hardware configurations of different power plants vary: some power plants have flow meters and pressure gauges installed on their ammonia injection branch pipes, enabling them to measure the actual ammonia injection volume in each zone; while most power plants only have regulating valves and no flow measurement devices. Therefore, an ammonia injection control method that can adapt to different hardware configurations, make full use of field test data, and is easy to implement is needed. Summary of the Invention

[0007] This application provides a zoned ammonia injection control method for SCR systems that adapts to wide load variations. This method addresses the problem that commonly used zoned ammonia injection control methods for SCR systems are difficult to adapt to rapid load changes in coal-fired power plants and have poor hardware configuration matching. Different ammonia injection control strategies are adopted according to load changes, enabling the selective catalytic reduction denitrification system to adapt to the rapid load change requirements of coal-fired power plants. Furthermore, this solution is compatible with different hardware configurations and has a wide range of applications.

[0008] The first aspect of this application provides a method for SCR zone ammonia injection control that adapts to wide load variations, comprising the following steps: acquiring a boiler load signal; identifying the current load change pattern and current load mode of the boiler based on the load signal; determining a target full load range control parameter preset table; determining target control parameters for each ammonia injection zone from the target full load range control parameter preset table based on the current load mode; and determining adjustment parameters for each ammonia injection zone based on the current load change pattern; and controlling the valves of each ammonia injection zone of the selective catalytic reduction denitrification system to inject ammonia based on the target control parameters and adjustment parameters of each ammonia injection zone.

[0009] A second aspect of this application provides an SCR zone ammonia injection control system adaptable to wide load variations, comprising: an identification module for acquiring boiler load signals and identifying the current load change pattern and current load mode of the boiler based on the load signals; a parameter determination module for determining a target full load range control parameter preset table, determining target control parameters for each ammonia injection zone from the target full load range control parameter preset table based on the current load mode, and determining adjustment parameters for each ammonia injection zone based on the current load change mode; and a control module for controlling the valves of each ammonia injection zone of the selective catalytic reduction denitrification system to inject ammonia based on the target control parameters and adjustment parameters of each ammonia injection zone.

[0010] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the SCR zone ammonia injection control method adapted to wide load variations as described in the above embodiments.

[0011] A fourth aspect of this application provides a computer program product having a computer program stored thereon, which is executed by a processor to implement the SCR zone ammonia injection control method adapted to wide load variations as described in the above embodiments.

[0012] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0013] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart of an SCR zone ammonia injection control method adapted to wide load variations provided in an embodiment of this application; Figure 2 This is a flowchart of an SCR zone ammonia injection control method adapted to wide load variations according to a specific embodiment of this application; Figure 3 This is an example diagram of an SCR zone ammonia injection control system adapted to wide load variations according to an embodiment of this application; Figure 4 This is a schematic diagram of the structure of an electronic device according to an embodiment of this application. Detailed Implementation

[0014] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0015] The following describes an embodiment of the SCR zone ammonia injection control method adaptable to wide load variations, with reference to the accompanying drawings. Addressing the problem mentioned in the background art that the currently commonly used zone ammonia injection control methods for SCR systems are difficult to adapt to rapid load changes in coal-fired power units and have low compatibility with power plant hardware configurations, this application provides a SCR zone ammonia injection control method adaptable to wide load variations. In this method, the boiler load signal is acquired, and the current load change pattern and current load mode of the boiler are identified based on the load signal; a target full-load range control parameter preset table is determined, and the target control parameters for each ammonia injection zone are determined from the target full-load range control parameter preset table according to the current load mode; and the adjustment parameters for each ammonia injection zone are determined according to the current load change pattern; and the valves of each ammonia injection zone of the selective catalytic reduction denitrification system are controlled to inject ammonia according to the target control parameters and adjustment parameters of each ammonia injection zone. This solves the problem that the commonly used zoned ammonia injection control method is difficult to adapt to the rapid load changes of coal-fired power units and the low matching degree of power plant hardware configuration. Different ammonia injection control strategies are adopted according to load changes, so that the selective catalytic reduction denitrification system can adapt to the rapid load change requirements of coal-fired power units. Moreover, this solution is compatible with different hardware configurations and has a wide range of applications.

[0016] Specifically, Figure 1 This is a schematic flowchart of an SCR zone ammonia injection control method adapted to wide load variations provided in an embodiment of this application.

[0017] like Figure 1 As shown, the SCR zone ammonia injection control method adaptable to wide load variations includes the following steps: In step S101, the boiler load signal is acquired, and the current load change mode and current load mode of the boiler are identified based on the load signal.

[0018] The distributed control system (DCS) collects the actual load signal of the boiler in real time, continuously acquires boiler load data at a fixed sampling period, and calculates the load change per unit time based on the continuously sampled load data to obtain the load change rate, which is used to characterize the speed of boiler load rise and fall.

[0019] The current load change patterns include regular load change pattern, rapid load change pattern, and frequent load change pattern. The current load patterns include minimum deep load adjustment pattern, low load pattern, medium load pattern, high load pattern, and full load pattern.

[0020] Among them, full-load mode refers to the boiler's maximum continuous output (BMCR) or economic continuous output (ECR), which is calibrated by the boiler manufacturer during the design stage according to the rated evaporation / thermal power, such as 100% BMCR; high-load mode refers to the operating range that is close to full load and has high efficiency, such as 70% to 100% BMCR; low-load mode refers to the range that is lower than the economic range but can still operate normally and stably, such as 40% to 70% BMCR; minimum deep-adjustment load mode refers to the minimum output that the boiler can maintain under the premise of no oil injection / minimal oil injection, long-term continuous operation, safety and stability, and compliance with environmental protection standards, usually 20% to 30% BMCR, which can be lower after modification.

[0021] In some embodiments, identifying the current load change pattern of the boiler based on the load signal includes: determining the load change rate of the boiler based on the load signal; if the load change rate is greater than a first threshold and less than or equal to a second threshold, determining that the current load change pattern is a regular load change pattern; if the load change rate is greater than the second threshold and less than or equal to a third threshold, determining that the current load change pattern is a rapid load change pattern; if the load change rate is greater than the third threshold, determining that the current load change pattern is a frequent load change pattern.

[0022] Specifically, this application pre-sets multi-level load change rate thresholds, including a first threshold, a second threshold, and a third threshold, wherein: the first threshold < the second threshold < the third threshold.

[0023] The boiler's load change rate, calculated in real time, is compared with multi-level thresholds to identify the current load mode of the boiler: if the boiler's load change rate is greater than the first threshold and less than or equal to the second threshold, the current load change mode is determined to be a normal load change mode; if the boiler's load change rate is greater than the second threshold and less than or equal to the third threshold, the current load change mode is determined to be a rapid load change mode; if the boiler's load change rate is greater than the third threshold, the current load change mode is determined to be a frequent load change mode.

[0024] In step S102, a target full load range control parameter preset table is determined, and the target control parameters for each ammonia injection zone are determined from the target full load range control parameter preset table according to the current load mode, and the adjustment parameters for each ammonia injection zone are determined according to the current load change mode. In some embodiments, if the selective catalytic reduction denitrification system is equipped with a zoned flow measurement device, the target full load range control parameter preset table is a distribution coefficient table; if the selective catalytic reduction denitrification system is not equipped with a zoned flow measurement device, the target full load range control parameter preset table is a valve opening table.

[0025] The target full-load range control parameter preset table includes two forms: a distribution coefficient table and a valve opening table. The specific form used depends on the on-site hardware configuration: If each ammonia injection branch of the SCR denitrification system is equipped with a flow meter (such as a thermal mass flow meter, orifice plate flow meter, etc.) and the actual ammonia injection rate of each zone can be measured online, then the conditions for implementing precise injection rate control are met. In this case, the target full-load range control parameter preset table should be a distribution coefficient table. If each ammonia injection branch is only equipped with an electric regulating valve and no flow measurement device is installed, and the actual ammonia injection rate of each zone cannot be known, then only a valve opening table can be selected, and the valve opening value obtained from the optimization test can be used for control.

[0026] In step S103, the valves of each ammonia injection zone of the selective catalytic reduction denitrification system are controlled to inject ammonia according to the target control parameters and adjustment parameters of each ammonia injection zone.

[0027] In this application, each ammonia injection zone corresponds to an independent ammonia injection branch pipe, and each branch pipe typically has only one main regulating valve installed. Therefore, each ammonia injection zone corresponds to a valve opening command, which directly controls the single regulating valve of that zone. If future technological advancements lead to multiple valves connected in series or parallel within a zone, then each valve should indeed have its own independent opening degree. However, under the current conventional configuration, following the principle of "one zone, one valve, one opening degree," the ammonia injection quantity of each valve is the ammonia injection quantity of that zone, and its relationship with the opening degree is determined by the characteristic curve of that valve.

[0028] In some embodiments, determining the target control parameters for each ammonia injection zone from the target full load range control parameter preset table according to the current load mode includes: if the target full load range control parameter preset table is an allocation coefficient table, then querying the target ammonia injection quantity for each ammonia injection zone from the allocation coefficient table according to the current load mode; if the target full load range control parameter preset table is a valve opening table, then querying the valve opening table according to the current load mode to obtain the target valve opening for each ammonia injection zone.

[0029] (1) If the target full load range control parameter preset table is an allocation coefficient table.

[0030] Query the allocation coefficient table based on the current load mode to obtain the target allocation coefficient for each ammonia injection zone under the current load mode.

[0031] The allocation coefficient is the proportion of ammonia injection volume in a single zone to the total ammonia injection volume, and the sum of the allocation coefficients of all ammonia injection zones is 1.

[0032] Simultaneously, the total ammonia injection rate output from the total quantity controller in the selective catalytic reduction (SCR) denitrification system is read, and the total ammonia injection rate is proportionally allocated according to the target allocation coefficient of each zone to calculate the target ammonia injection rate for each zone. Then, based on the flow characteristic curves of the valves in each zone, the target ammonia injection rate for the corresponding zone is converted into the corresponding valve opening command and output to the control mechanism corresponding to the valve.

[0033] (2) If the target full load range control parameter preset table is a valve opening table.

[0034] According to the current load mode, the valve opening table is queried to obtain the target opening of each ammonia injection zone valve under the current load mode. The target opening can be proportionally corrected by combining the total ammonia injection output of the total quantity controller. For example, when there is a deviation between the actual total ammonia injection and the historical total ammonia injection corresponding to the preset opening, the opening of all zones is adjusted proportionally.

[0035] In some embodiments, querying the target ammonia injection amount for each ammonia injection zone from the allocation coefficient table according to the current load mode includes: obtaining the target allocation coefficient for each ammonia injection zone under the current load mode from the allocation coefficient table, and reading the total ammonia injection amount output by the total quantity controller in the selective catalytic reduction denitrification system; allocating the total ammonia injection amount according to the target allocation coefficient of each ammonia injection zone to obtain the target ammonia injection amount for each ammonia injection zone.

[0036] The specific calculation scheme for the target ammonia injection volume in each zone is as follows: Step 1: Query the allocation coefficients. Based on the current load mode, look up the target allocation coefficients for each ammonia injection zone under the current load from the full load range control parameter preset table (or combine interpolation calculations). k i ,in,i Represents the partition number.

[0037] Step 2: Obtain the total ammonia injection command. Read the total ammonia injection command in real time from the total quantity controller of the SCR denitrification system (usually a main PID controller, using the total NOx at the SCR inlet, the NOx setpoint at the outlet, and the flue gas volume as inputs). Q total .

[0038] Step 3: Calculate the target ammonia injection amount for each zone. Allocate the total ammonia injection amount to each zone according to the allocation coefficient, and calculate the target ammonia injection amount for each zone. Q i : Q i = k i × Q total ; During system design, preset table types can be set through a simple soft switch or parameters in a configuration file to adapt to the actual conditions of different power plants.

[0039] The method for converting the target ammonia injection quantity of the corresponding ammonia injection zone into the corresponding valve opening command based on the flow-valve opening characteristic curve of each zone valve, and outputting it to the corresponding control mechanism of the valve, is as follows: The valve characteristic curve describes the valve opening degree ( O %) and the flow rate of the medium flowing through the valve ( Q The unit corresponds to the ammonia injection rate (e.g., kg / h or Nm³ / h). This curve is usually non-linear and needs to be obtained through on-site calibration or from the valve manufacturer's documentation. The steps to determine the valve opening command are as follows: Step 1: Obtain the characteristic curve.

[0040] Obtain the flow-valve opening characteristic curve for each zone control valve; this curve can be represented as a function. Q = f ( O ) or its inverse function O = f -1 ( Q In actual DCS systems, these functions are typically stored in the form of piecewise linear function tables.

[0041] Step 2: Calculate the valve opening.

[0042] The calculated target ammonia injection volume for this zone O i As input, substitute the inverse function characteristic curve of the valve in that zone (or consult the line graph table) to calculate the corresponding target valve opening command. Oi : O i = f 1 ( Q i ),or, O i = f i 1 ( O i ).

[0043] Step 3: Output the command.

[0044] The calculated target opening command O i The signal is sent to the electric actuator of the corresponding ammonia injection zone to adjust the ammonia injection volume.

[0045] To address the dynamic deviations that may result from large rate changes, the specific plan for overall trend correction of the preset parameters is as follows: Based on the real-time calculated load change trend (load increase or load decrease), the system superimposes a unified correction coefficient ΔΔ, which is related to the rate of change, onto the basic control parameters of each zone obtained from the preset table.

[0046] Load increase trend: As the unit releases stored heat and flue gas volume increases, NOx generation typically shows an increasing trend. To suppress NOx peaks in advance, the preset control parameters for each zone are adjusted towards "enhanced ammonia injection". For valve opening presets, the retrieved opening values ​​for each zone are uniformly increased by ΔΔ% (e.g., 1%). For allocation coefficient presets, the allocation coefficient remains unchanged, but a feedforward bias is added to the total ammonia injection command output by the total quantity controller, which is equivalent to overall enhanced ammonia injection.

[0047] Load reduction trend: Flue gas volume decreases, NOx generation decreases. To prevent over-injection, the preset control parameters for each zone are adjusted towards "reduced ammonia injection". For valve opening presets, the retrieved opening values ​​for each zone are uniformly reduced by ΔΔ%. For allocation coefficient presets, a negative bias is applied to the total ammonia injection command.

[0048] The magnitude of the correction factor ΔΔ is proportional to the load change rate. The larger the change rate, the larger ΔΔ is. Upper and lower limits can be set (e.g., 0.5%~2.0%). This factor can be adjusted through field tests.

[0049] In some embodiments, determining the adjustment parameters for each ammonia injection zone based on the current load change pattern includes: if the current load change pattern is a regular load change pattern, the adjustment parameters for each ammonia injection zone are a first adjustment step size and a first adjustment threshold; if the current load change pattern is a rapid load change pattern, the adjustment parameters for each ammonia injection zone are a second adjustment step size and a second adjustment threshold; if the current load change pattern is a frequent load change pattern, the adjustment parameters for each ammonia injection zone are a third adjustment step size and a third adjustment threshold; wherein the first adjustment step size is less than the second adjustment step size and less than the third adjustment step size, and the first adjustment threshold is less than the second adjustment threshold and less than the third adjustment threshold.

[0050] Once the system is in a stable state, initiate NOx concentration monitoring for each zone, sequentially collecting NOx concentration data at the outlet of each ammonia injection zone. Set differentiated adjustment step sizes and thresholds based on the current load variation pattern.

[0051] If the current load change mode is a regular load change mode, the adjustment parameters for each ammonia injection zone are the first adjustment step size and the first adjustment threshold. This can be understood as follows: under the regular load change mode, if the load change rate reaches the first adjustment threshold, the ammonia injection will be adjusted with the first adjustment step size. If the current load change mode is a rapid load change mode, the adjustment parameters for each ammonia injection zone are the second adjustment step size and the second adjustment threshold. This can be understood as follows: under the rapid load change mode, if the load change rate reaches the second adjustment threshold, the ammonia injection will be adjusted with the second adjustment step size. If the current load change mode is a frequent load change mode, the adjustment parameters for each ammonia injection zone are the third adjustment step size and the third adjustment threshold. This can be understood as follows: under the frequent load change mode, if the load change rate reaches the third adjustment threshold, the ammonia injection will be adjusted with the third adjustment step size.

[0052] Among them, the first adjustment step size < the second adjustment step size < the third adjustment step size, and the first adjustment threshold size < the second adjustment threshold size < the third adjustment threshold size. For regular load changes, a smaller adjustment step size and adjustment threshold size are used to ensure smooth adjustment. For rapid load changes, a larger adjustment step size and adjustment threshold size are used to improve response speed and suppress NOx fluctuations. For frequent load changes, a larger step size is used in conjunction with an extended lockout time to reduce frequent valve actions and achieve anti-shaking control.

[0053] The determination of whether the system has entered a stable state is a comprehensive logical judgment process involving multiple parameters and partitions, as detailed below: Step 1: Collect the rate of change of key parameters. Calculate and monitor the rate of change of three key parameters—boiler load, coal feed rate, and main steam pressure—within a certain time window in real time.

[0054] Step 2: Determine the current load mode and retrieve the preset stability criterion parameters for that current load mode. These parameters include: Load change rate (e.g., load change rate <0.3% / min under low load mode, load change rate <0.5% / min under medium load mode, load change rate <0.8% / min under high load mode). Coal feed rate change rate (e.g., coal feed rate change rate <0.8% / min under low load mode, coal feed rate change rate <1.2% / min under medium load mode, and coal feed rate change rate <1.5% / min under high load mode). Main steam pressure change rate (e.g., main steam pressure change rate under low load mode <0.15MPa / min, main steam pressure change rate under medium load mode <0.2MPa / min, main steam pressure change rate under high load mode <0.25MPa / min).

[0055] Duration (e.g., 20 minutes in low load mode, 15 minutes in medium load mode, and 10 minutes in high load mode).

[0056] When the load change rate, coal feed rate change rate, main steam pressure change rate, and duration of the current load mode meet the above conditions, it is determined that the system has entered a stable state and issues a step size for adjusting ammonia injection according to the current load change mode. If any parameter exceeds the threshold within the duration, the timer will be reset to zero and restart the timing.

[0057] Furthermore, while continuing to execute rapid load change presets (obtaining target control parameters from a table, outputting valve opening commands, and allowing small-range PID corrections), the system simultaneously adds three enhancement measures: (1) Relax the PID correction range When the load changes rapidly, expand the upper and lower limits of the allowable adjustment of the PID (e.g., relax it to ±4% to ±5%).

[0058] Objective: To give the PID controller a larger adjustment margin, to quickly suppress NOx spikes, to prevent it from being blocked by the limiting mechanism, and to ensure rapid correction capability.

[0059] (2) Shorten the time for determining stability after setting. When the load changes rapidly, shorten the stability judgment time and speed up the control rhythm so that the system can enter a new round of adjustment more quickly and keep up with the speed of the rapid load change.

[0060] (3) Adjust the preset control parameters according to the load trend. While continuing to implement frequent load shifting presets, the system will simultaneously add enhancement measures: (1) Automatically extend the preset lock time.

[0061] Under normal operating conditions, after the valve performs a preset adjustment, it will enter a locking period (e.g., 30 seconds), during which no new fine-tuning commands will be accepted.

[0062] After entering the frequent load stabilization mode, the lock time will be automatically extended proportionally (e.g., extended by 50% to 100%, becoming 60s, 90s or longer, which can be configured).

[0063] (2) Frequent adjustments are prohibited during the lockout period.

[0064] During the extended lockout period, even if there are slight fluctuations in load or minor deviations in NOx, the system will not perform any new preset or fine-tuning actions on the valves, maintaining the current opening degree. Therefore, by extending the preset locking time and prohibiting frequent adjustments under frequent load changes, the frequency of valve operation is reduced, repeated opening and closing, oscillation and wear of the valve are avoided, control loop oscillation is suppressed, system operation stability is improved, and the service life of the ammonia injection regulating valve is extended.

[0065] In some embodiments, when controlling the valves of each ammonia injection zone to inject ammonia according to the target control parameters and adjustment parameters of each ammonia injection zone, the method includes: if a first target zone is determined to have a nitrogen oxide concentration greater than a first preset concentration value within a preset time period, then the valve opening of the first target zone is increased by a fourth adjustment step; if a second target zone is determined to have a nitrogen oxide concentration less than a second preset concentration value within a preset time period, then the valve opening of the second target zone is decreased by a fifth adjustment step.

[0066] Specifically, after obtaining the target control parameters and corresponding adjustment parameters for each zone, the system monitors the NOx concentration at the outlet of each ammonia injection zone in real time and performs fine-tuning control: If the NOx concentration in a certain ammonia injection zone is continuously greater than the first preset concentration value within a preset time period, the zone is determined to be the first target zone, indicating insufficient ammonia injection; then the valve opening of the zone is increased by the fourth adjustment step to increase the ammonia injection amount.

[0067] If the NOx concentration in a certain ammonia injection zone is continuously lower than the second preset concentration value within a preset time period, the zone is determined to be the second target zone, indicating that ammonia injection is excessive; then the valve opening of the zone is reduced by the fifth adjustment step to reduce the amount of ammonia injected.

[0068] In some embodiments, adjusting the first target partition or adjusting the second target partition includes: if the nitrogen oxide concentration of the first target partition is still greater than a first preset concentration value within a preset time period, then triggering a first audible and visual alarm action; or, if the nitrogen oxide concentration of the second target partition is still less than a second preset concentration value within a preset time period, then triggering a second audible and visual alarm action.

[0069] Specifically, after performing adjustment operations on the first or second target zone, the system continues to monitor the NOx concentration in that zone: If the NOx concentration in the first target zone remains higher than the first preset concentration value within a preset time after the valve opening is increased, and there is no obvious trend of improvement, the first audible and visual alarm will be triggered to remind the operators that there may be problems such as measurement point failure, abnormal flow field or valve jamming in the zone. If the NOx concentration in the second target zone remains below the second preset concentration value for a preset period of time after the valve opening is reduced, and there is no obvious trend of improvement, then the second audible and visual alarm will be triggered to remind the operators to check the measuring device, valve actuator, or flow field distribution.

[0070] Once data is collected from each partition, it is added to the real-time analysis queue. The system first identifies and handles outliers: if a partition experiences a sudden increase or decrease in NOx concentration, and deviates from the average value of the currently measured partitions by more than a preset percentage (e.g., 50%), it is identified as an extreme anomaly. The system immediately highlights the data at that measurement point in red on the DCS screen and triggers an alarm to alert operators.

[0071] For outliers, it is necessary to combine the results of multiple consecutive measurements to determine whether they represent the actual operating conditions. If the NOx concentration measured in this zone is significantly higher or lower than normal in multiple consecutive measurements, it is confirmed as the actual operating condition and can be used in subsequent adjustment decisions. If the outlier is an occasional spike or trough, it may be a measurement disturbance and will not be included in the adjustment for the time being, but will be continuously monitored.

[0072] Once the abnormal value is confirmed to be a true operating condition, the system adjusts the ammonia injection zone's adjustment step size according to the current load change pattern. If the NOx concentration in the same zone remains abnormal after multiple adjustments (e.g., no improvement trend for one hour), the system triggers an audible and visual alarm, prompting operators to contact thermal control personnel to check the measuring device or local equipment, and to intervene manually if necessary.

[0073] In some embodiments, before determining the target control parameters for each ammonia injection zone from the target full load range control parameter preset table according to the current load mode, the process includes: selecting multiple typical load points of the coal-fired power unit; stabilizing the coal-fired power unit at each load point, measuring the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system, adjusting the valve opening of each ammonia injection zone until the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system reaches a uniform state; recording the valve opening value of each ammonia injection zone at each load point when the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system reaches a uniform state, and obtaining a valve opening table.

[0074] Before determining the target control parameters for each ammonia injection zone, a preset table of control parameters for the entire load range needs to be established in advance. The steps for establishing the valve opening table are as follows: Select multiple typical load points covering all operating conditions of the unit. The typical load points include the deepest load reduction point, low load point, medium load point and high load point, and the number of typical load points shall not be less than 8. To ensure the stable operation of coal-fired power units at each selected typical load point; At each typical load point, the NOx concentration distribution at the outlet section of the selective catalytic reduction denitrification system was measured using the grid method. Adjust the valve opening of each ammonia injection zone one by one until the NOx concentration distribution at the outlet section reaches the most uniform state. Record the valve opening value corresponding to each ammonia injection zone at this time, as the optimal opening value under this load point; Repeat the above steps for all typical load points to create a valve opening table covering the entire load range; For intermediate load points that have not been tested, the corresponding valve opening is calculated using a piecewise linear interpolation method.

[0075] In some embodiments, before determining the target control parameters for each ammonia injection zone from the target full-load range control parameter preset table according to the current load mode, the method further includes: selecting multiple typical load points of the coal-fired power unit; stabilizing the coal-fired power unit at each load point, measuring the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system, adjusting the ammonia injection rate of each ammonia injection zone until the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system reaches a uniform state; recording the actual ammonia injection flow rate and total ammonia injection flow rate of each ammonia injection zone at each load point when the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system reaches a uniform state; calculating the allocation coefficient for each ammonia injection zone, where the allocation coefficient is the ratio of the actual ammonia injection flow rate to the total ammonia injection flow rate of the corresponding zone, and obtaining an allocation coefficient table.

[0076] The steps to establish the allocation coefficient table are as follows: Similarly, select multiple typical load points covering all operating conditions. The typical load points include the deepest load point, low load point, medium load point and high load point, and the number of typical load points shall not be less than 8. To ensure the stable operation of coal-fired power units at each typical load point; The grid method was used to measure the NOx concentration distribution at the outlet of the denitrification system, and the ammonia injection rate of each ammonia injection zone was adjusted to make the NOx concentration distribution at the outlet most uniform. Record the actual ammonia injection flow rate of each ammonia injection zone and the total ammonia injection flow rate of the system at this time; Calculate the allocation coefficient for each ammonia injection zone: Allocation coefficient = Actual ammonia injection flow rate of the corresponding zone ÷ Total ammonia injection flow rate; The allocation coefficients corresponding to each load point are stored in a table to form an allocation coefficient table; for intermediate load points, the corresponding allocation coefficients are calculated using a piecewise linear interpolation method.

[0077] During ammonia injection regulation, after each ammonia injection adjustment based on the regulation threshold and step size, the load value and the adjusted control parameters for each zone are recorded after the system stabilizes again. When the average control parameter of multiple adjustments at the same load point deviates from the original preset value beyond the update threshold, the control parameter values ​​for the corresponding load point and zone in the preset table are updated using this average value. After the high-load zone data is updated a certain number of times, a low-load rapid verification test is automatically triggered to verify and correct the low-load preset values.

[0078] Furthermore, the following special handling is added for deep adjustment low-load mode: Enhanced Measurement: Extend the measurement time for each zone and use multiple measurements to take the average; Dead Zone Control: When the valve opening is small, the actual adjustment step size is halved; Priority Locking: Appropriately extend the locking time and reduce the adjustment frequency; Outlier Tolerance Handling: Appropriately relax the criteria for judging outliers.

[0079] In this application, the valve opening table is shown in Table 1, and the allocation coefficient table is shown in Table 2.

[0080] Table 1

[0081] Table 2

[0082] This embodiment uses the SCR denitrification system of a 660MW coal-fired power unit as an example. This unit participates in deep peak shaving, with a minimum stable combustion load of 30% and a maximum load of 100%, experiencing frequent load changes at a rate of up to 2.5% / min. The system has 12 independent ammonia injection zones, each equipped with an electric regulating valve. Each zone outlet has a NOx measuring point. Specific steps are as follows... Figure 2 As shown.

[0083] Step 1: Establish a preset table of control parameters for the entire load range After unit maintenance, an ammonia injection optimization test was conducted. Several typical load points covering low, medium, and high loads (such as minimum deep load, 50% load, 75% load, full load, etc., with a total of no less than 8 points) were selected. The unit was operated stably at each load point, and the NOx distribution at the SCR outlet was measured using the grid method. The outlet NOx distribution was made most uniform by adjusting the valves in each zone. The optimal control parameters of the 12 zone valves at each load point were recorded to form a preset table.

[0084] Depending on the on-site hardware configuration, one of the following two options can be selected: Form 1 (Distribution Coefficient): If a zone flow measurement device is installed on site, the distribution coefficient can be calculated based on the actual ammonia injection rate of each zone. The distribution coefficient of each zone that makes the NOx distribution at the outlet most uniform under each load point is recorded, and the sum of all zone distribution coefficients is 1. For intermediate load points, linear interpolation is used to calculate the distribution coefficient.

[0085] Format 2 (Valve Opening): If no flow measurement device is installed on site, directly record the valve opening values ​​of each zone that result in the most uniform NOx distribution at each load point. For intermediate load points, use linear interpolation to calculate the valve opening.

[0086] This embodiment uses Form 2 as an example for illustration, directly recording the optimal opening value of each zone valve under each load point.

[0087] Step 2: Parameter Settings The load change rate is set to a low threshold of 0.8% / min and a high threshold of 2.0% / min, with a change amplitude threshold of 2.5%. The stability criteria are set differently according to the load range: under low load mode, the load change rate is <0.3% / min, coal quantity is <0.8% / min, pressure is <0.15MPa / min, and the duration is 20 minutes; the criteria are relaxed accordingly under medium load mode; and further relaxed under high load mode.

[0088] Ammonia injection adjustment threshold: 8 mg / m³ in low load mode, 10 mg / m³ in medium load mode, and 12 mg / m³ in high load mode.

[0089] Adjustment step size: 1% for normal load changes, 2% for rapid load changes, and 3% for frequent load changes. Locking time is dynamically set according to the step size. The outlier criterion is a deviation of more than 50% from the average value; when such an extreme value occurs, the DCS screen will display a red alarm. If there is no improvement after one hour of continuous adjustment in the same zone, an audible and visual alarm will be triggered. Special handling for low loads: Measurement time is extended to 60 seconds; when the opening is <30%, the step size is halved; the locking time is extended by 50%; and the outlier criterion is relaxed to 80%.

[0090] Step 3: Tiered load handling The target control parameters for each zone are obtained by querying the preset table based on the current load pattern.

[0091] Depending on the format of the preset table, the instructions are generated in the following ways: If the allocation coefficient is used, the target allocation coefficient of each zone is obtained by querying the current load mode (low, medium and high load), and the target ammonia injection amount of each zone is calculated by combining the total ammonia injection amount output by the total controller. Then, the valve characteristic curve is used to convert it into an opening command. If valve opening is used, the target opening command for each zone is obtained by querying the current load mode (low, medium, high load). At the same time, the total ammonia injection output by the total quantity controller can be used to make overall corrections to the preset opening. For example, when there is a deviation between the actual total ammonia injection and the historical total ammonia injection corresponding to the preset opening, the opening of all zones is adjusted proportionally.

[0092] For example, by using valve opening form, the target opening of each zone can be directly obtained, allowing PID ±2% correction.

[0093] Rapid load change: When the load rapidly increases from 400MW to 550MW at a rate of 3.2% / min, the system performs rapid preset, relaxes the correction range to ±4%, shortens the stability judgment time, and increases the overall trend correction by 1%.

[0094] Frequent load change anti-shake: If the same load segment is crossed 4 times within 30 minutes, the system will automatically extend the subsequent lock time by 50%.

[0095] Step 4: Differential Stability Judgment After the rapid load change ends, the load stabilizes at 550MW (>80%), and all indicators meet the standards within 10 minutes. The system judges that it has entered a stable state and then makes fine adjustments according to the current load change pattern.

[0096] Step 5: Differentiated Steady-State Survey and Fine-Tuning Initiate zoned NOx monitoring using high-load zone parameters. After measuring zones 1 and 2, the range was within acceptable limits. After measuring zone 3 (55 mg / m³), the range 17 > 12, triggering adjustment. The average NOx was 45 mg / m³. Zone 3 had the largest deviation and was above average, so a valve reduction operation was performed (45% → 42%), and the range was locked for 40 minutes.

[0097] During subsequent monitoring, zone 7 recorded 82 mg / m³, deviating from the current average by approximately 82%. The system immediately highlighted this measurement point in red and displayed an alarm on the DCS screen. After inspection, the measuring device was found to be normal. Monitoring continued; if three consecutive measurements were consistently high, the system was confirmed as a genuine operating condition and adjustments were initiated. If the readings were intermittent, no action was taken. Assuming three consecutive high readings, the system initiated ammonia injection (by opening the valve wider). If the NOx level in zone 7 did not improve within one hour after adjustment, the system triggered an audible and visual alarm, prompting operators to contact the thermal control department for inspection.

[0098] Step 6: Special treatment for low load When the unit is deeply adjusted to 30% load, special low-load handling is initiated: the measurement time is extended to 60 seconds, and the average of three measurements is taken; when the opening of zone 8 is 28% and adjustment is required, the step size is set to 0.5%; the locking time is extended to 30 minutes; and the abnormal value judgment standard is relaxed to 80%.

[0099] Step 7: Adaptive update of control parameter preset table After multiple runs, the average opening of partition 7 at 90% load point was 61.5% (previously preset to 60%), with a deviation of 2.5% (<3%), so it will not be updated for now. If the allocation coefficient method is used, the average allocation coefficient will be recorded and a similar judgment will be made.

[0100] After the data in the high-load area has been updated a total of 10 times, the system will automatically trigger a 30% low-load rapid verification test to verify and correct the low-load preset value.

[0101] The above technical solution can achieve the following technical effects: (1) By providing two preset tables, namely the allocation coefficient table and the valve opening table, flexible adaptation to different on-site hardware configurations is achieved, which improves the engineering practicality of the solution.

[0102] (2) The data in the preset table comes from the on-site ammonia injection optimization test. It directly records the valve opening or ammonia injection distribution coefficient that makes the outlet NOx concentration uniform at each load point. The data is accurate and reliable, avoiding the problem of theoretical calculation being out of sync with the actual on-site working conditions. It ensures that the expected control effect can be achieved quickly after the scheme is implemented, reducing the difficulty of debugging.

[0103] (3) By collecting boiler load signals and calculating load change rate, the three load change modes of conventional load change, rapid load change and frequent load change and low, medium and high load mode are accurately identified. Based on the load change mode and low, medium and high load mode, the corresponding ammonia injection preset strategy, adjustment parameters and anti-shaking strategy are matched to achieve full coverage control of the entire load range, perfectly adapt to the wide load operation requirements of deep peak shaving unit, and solve the problem of control failure of traditional control scheme when the load changes drastically.

[0104] (4) Differentiated adjustment thresholds and adjustment steps are set for different load change modes, so that the adjustment parameters are accurately matched with the engineering characteristics of each load range. During normal load changes, the adjustment is stable, the response speed is improved and NOx fluctuations are suppressed during rapid load changes, and the valves are reduced during frequent load changes. This achieves refined control for different scenarios and improves the control stability across the entire load range.

[0105] (5) In the rapid load change mode, by widening the PID correction range, shortening the stability judgment time, and making overall trend correction of the preset parameters according to the load trend, the system can quickly respond to load changes, suppress NOx peaks in advance or prevent excessive ammonia injection, effectively reduce the fluctuation range of NOx concentration during the rapid load change process, and ensure that NOx emissions meet the standards stably.

[0106] (5) Special handling for low load mode: By automatically extending the preset locking time and prohibiting frequent adjustment during the locking period, the frequency of ammonia injection regulating valve operation is effectively reduced, avoiding repeated opening and closing, oscillation and wear of the valve, suppressing control loop oscillation, improving system operation stability, extending the service life of ammonia injection regulating valve, and reducing equipment maintenance and replacement costs.

[0107] (6) Combining the rate of change and duration of the three key parameters of boiler load, coal feed rate and main steam pressure, we ensure that ammonia injection is adjusted only after the system is truly stable, based on the adjustment threshold and adjustment step size. This avoids control disorder caused by blind adjustment when the operating conditions are unstable, and further improves the reliability of system operation.

[0108] (7) Extreme abnormal points that rise or fall suddenly or deviate too much from the average value are marked in red and alarmed to distinguish between occasional disturbances and actual operating conditions, so as to avoid misadjustment or loss of control due to measurement disturbances; for zones where the NOx concentration remains abnormal after multiple adjustments, an audible and visual alarm is triggered to prompt operators to check the measuring points, valves, flow fields and other issues in a timely manner, so as to realize early detection and early handling of abnormal operating conditions and reduce the risk of system loss of control.

[0109] (8) By controlling the ammonia injection in a specific area, the NOx concentration at the SCR outlet is evenly distributed, avoiding NOx exceeding the standard due to insufficient local ammonia injection and ammonia escape due to excessive local ammonia injection, thus reducing ammonia waste. Especially during the deep adjustment and low load period, ammonia consumption is significantly reduced, which significantly reduces the denitrification operating cost.

[0110] (9) The solution does not require any new hardware equipment and can be directly adapted to the existing system, resulting in low implementation costs. At the same time, by extending the service life of the equipment, reducing manual intervention, and reducing ammonia consumption, the overall operating cost of the unit is further reduced, thereby improving the economic efficiency and promotion value of the solution.

[0111] (10) By dynamically updating the preset table through fine adjustment results, the system can automatically optimize control parameters according to changes in coal quality, catalyst aging and other operating conditions, without the need for frequent manual adjustments, ensuring that the scheme maintains good control effect in the long term, and improving the system's adaptability and long-term operational stability.

[0112] Next, referring to the accompanying drawings, an SCR zoned ammonia injection control system adapted to wide load variations is described according to an embodiment of this application.

[0113] Figure 3 This is a block diagram of an SCR zone ammonia injection control system adapted to wide load variations according to an embodiment of this application.

[0114] like Figure 3As shown, the SCR zone ammonia injection control system 10, which adapts to wide load variations, includes: an identification module 100, a parameter determination module 200, and a control module 300.

[0115] The system includes: an identification module 100 for acquiring boiler load signals and identifying the current load change pattern and current load mode; a parameter determination module 200 for determining a target full load range control parameter preset table, determining the target control parameters for each ammonia injection zone from the target full load range control parameter preset table based on the current load mode, and determining the adjustment parameters for each ammonia injection zone based on the current load change pattern; and a control module 300 for controlling the valves of each ammonia injection zone of the selective catalytic reduction denitrification system to inject ammonia based on the target control parameters and adjustment parameters for each ammonia injection zone.

[0116] In some embodiments, the identification module 100 is configured to: determine the load change rate of the boiler based on the load signal; if the load change rate is greater than a first threshold and less than or equal to a second threshold, determine that the current load change mode is a normal load change mode; if the load change rate is greater than the second threshold and less than or equal to a third threshold, determine that the current load change mode is a rapid load change mode; if the load change rate is greater than the third threshold, determine that the current load change mode is a frequent load change mode.

[0117] In some embodiments, the parameter determination module 200 is used to: if the target full load range control parameter preset table is an allocation coefficient table, then query the target ammonia injection quantity of each ammonia injection zone from the allocation coefficient table according to the current load mode; if the target full load range control parameter preset table is a valve opening table, then query the valve opening table according to the current load mode to obtain the target valve opening of each ammonia injection zone.

[0118] In some embodiments, the parameter determination module 200 is configured to: obtain the target allocation coefficient of each ammonia injection zone under the current load mode from the allocation coefficient table, and read the total ammonia injection amount output by the total quantity controller in the selective catalytic reduction denitrification system; allocate the total ammonia injection amount according to the target allocation coefficient of each ammonia injection zone to obtain the target ammonia injection amount of each ammonia injection zone.

[0119] In some embodiments, the parameter determination module 200 is configured to: if the current load change mode is a regular load change mode, then the adjustment parameters for each ammonia injection zone are a first adjustment step size and a first adjustment threshold; if the current load change mode is a rapid load change mode, then the adjustment parameters for each ammonia injection zone are a second adjustment step size and a second adjustment threshold; if the current load change mode is a frequent load change mode, then the adjustment parameters for each ammonia injection zone are a third adjustment step size and a third adjustment threshold; wherein the first adjustment step size is less than the second adjustment step size and less than the third adjustment step size, and the first adjustment threshold is less than the second adjustment threshold and less than the third adjustment threshold.

[0120] In some embodiments, the control module 300 is configured to: determine a first target zone where the nitrogen oxide concentration is greater than a first preset concentration value within a preset time period, and then increase the valve opening of the first target zone by a fourth adjustment step; determine a second target zone where the nitrogen oxide concentration is less than a second preset concentration value within a preset time period, and then decrease the valve opening of the second target zone by a fifth adjustment step.

[0121] In some embodiments, the control module 300 is configured to: trigger a first audible and visual alarm action if the nitrogen oxide concentration in the first target zone is still greater than a first preset concentration value within a preset time period; or trigger a second audible and visual alarm action if the nitrogen oxide concentration in the second target zone is still less than a second preset concentration value within a preset time period.

[0122] In some embodiments, before determining the target control parameters for each ammonia injection zone from the target full load range control parameter preset table according to the current load mode, the parameter determination module 200 is used to: select multiple typical load points of the coal-fired power unit; stably operate the coal-fired power unit at each load point, measure the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system, adjust the valve opening of each ammonia injection zone until the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system reaches a uniform state; record the valve opening value of each ammonia injection zone at each load point when the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system reaches a uniform state, and obtain a valve opening table.

[0123] In some embodiments, before determining the target control parameters for each ammonia injection zone from the target full load range control parameter preset table according to the current load mode, the parameter determination module 200 is further configured to: select multiple typical load points of the coal-fired power unit; stably operate the coal-fired power unit at each load point, measure the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system, adjust the ammonia injection rate of each ammonia injection zone until the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system reaches a uniform state; record the actual ammonia injection flow rate and total ammonia injection flow rate of each ammonia injection zone at each load point when the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system reaches a uniform state; calculate the allocation coefficient of each ammonia injection zone, the allocation coefficient being the ratio of the actual ammonia injection flow rate of the corresponding zone to the total ammonia injection flow rate, and obtain an allocation coefficient table.

[0124] In some embodiments, if the selective catalytic reduction denitrification system is equipped with a zoned flow measurement device, the target full load range control parameter preset table is a distribution coefficient table; if the selective catalytic reduction denitrification system is not equipped with a zoned flow measurement device, the target full load range control parameter preset table is a valve opening table.

[0125] It should be noted that the foregoing explanation of the SCR zone ammonia injection control method embodiment for adapting to wide load variations also applies to the SCR zone ammonia injection control system for adapting to wide load variations in this embodiment, and will not be repeated here.

[0126] The SCR zone ammonia injection control system adapted to wide load variations proposed in this application collects boiler load signals, identifies the current load change pattern and current load mode based on the load signals, determines a target full-load range control parameter preset table, and determines the target control parameters for each ammonia injection zone from the target full-load range control parameter preset table according to the current load mode, and determines the adjustment parameters for each ammonia injection zone according to the current load change pattern; and controls the valves of each ammonia injection zone of the selective catalytic reduction denitrification system to inject ammonia according to the target control parameters and adjustment parameters of each ammonia injection zone. This solves the problems of current SCR zone ammonia injection control methods adapted to wide load variations being unable to adapt to rapid load changes in coal-fired power units and having low hardware configuration matching, enabling the selective catalytic reduction denitrification system to adapt to the rapid load change requirements of coal-fired power units, and has a wide range of applications.

[0127] Figure 4 A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include: The memory 401, the processor 402, and the computer program stored on the memory 401 and capable of running on the processor 402.

[0128] When the processor 402 executes the program, it implements the SCR zone ammonia injection control method adapted to wide load variations provided in the above embodiments.

[0129] Furthermore, electronic devices also include: Communication interface 403 is used for communication between memory 401 and processor 402.

[0130] The memory 401 is used to store computer programs that can run on the processor 402.

[0131] Memory 401 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0132] If the memory 401, processor 402, and communication interface 403 are implemented independently, then the communication interface 403, memory 401, and processor 402 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized into address buses, data buses, control buses, etc. For ease of representation, Figure 4 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0133] Optionally, in a specific implementation, if the memory 401, processor 402, and communication interface 403 are integrated on a single chip, then the memory 401, processor 402, and communication interface 403 can communicate with each other through an internal interface.

[0134] Processor 402 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0135] This application also provides a computer program product on which a computer program is stored, which, when executed by a processor, implements the above-described SCR zone ammonia injection control method adapting to wide load variations.

[0136] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0137] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0138] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0139] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequential list of executable instructions for implementing logical functions, and can be specifically implemented in any computer program product for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer program product" can be any means that can contain, store, communicate, propagate, or transmit a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples of computer program products (a non-exhaustive list) include the following: an electrical connection having one or N wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic device, and portable optical disc read-only memory (CDROM). Furthermore, the computer program product can even be paper or other suitable medium on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0140] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0141] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer program product, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0142] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer program product.

[0143] The computer program product mentioned above may be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. An SCR zoned-ammonia-injection control method that accommodates wide load variations, characterized by, Includes the following steps: Collect the load signal of the boiler, and identify the current load change pattern and current load mode of the boiler based on the load signal; A target full-load range control parameter preset table is determined, and the target control parameters for each ammonia injection zone are determined from the target full-load range control parameter preset table according to the current load mode, and the adjustment parameters for each ammonia injection zone are determined according to the current load change mode. The valves of each ammonia injection zone in the selective catalytic reduction denitrification system are controlled to inject ammonia according to the target control parameters and adjustment parameters of each ammonia injection zone.

2. The method of claim 1, wherein, The step of identifying the current load change pattern of the boiler based on the load signal includes: The load change rate of the boiler is determined based on the load signal; If the load change rate is greater than the first threshold and less than or equal to the second threshold, the current load change mode is determined to be a normal load change mode; If the load change rate is greater than the second threshold and less than or equal to the third threshold, the current load change mode is determined to be a rapid load change mode. If the load change rate is greater than the third threshold, the current load change mode is determined to be a frequent load change mode.

3. The method of claim 1, wherein, The step of determining the target control parameters for each ammonia injection zone from the target full-load range control parameter preset table based on the current load mode includes: If the target full load range control parameter preset table is an allocation coefficient table, then the target ammonia injection quantity for each ammonia injection zone is queried from the allocation coefficient table according to the current load mode; If the target full load range control parameter preset table is a valve opening table, then the target valve opening for each ammonia injection zone is obtained by querying the valve opening table according to the current load mode.

4. The method of claim 3, wherein, Based on the current load pattern, the target ammonia injection quantity for each ammonia injection zone is queried from the allocation coefficient table, including: Obtain the target allocation coefficient for each ammonia injection zone under the current load mode from the allocation coefficient table, and read the total ammonia injection amount output by the total quantity controller in the selective catalytic reduction denitrification system; The total ammonia injection amount is allocated according to the target allocation coefficient of each ammonia injection zone to obtain the target ammonia injection amount for each ammonia injection zone.

5. The method of claim 1, wherein, The adjustment parameters for each ammonia injection zone are determined based on the current load change pattern, including: If the current load change mode is a conventional variable load mode, then the adjustment parameters for each ammonia injection zone are the first adjustment step size and the first adjustment threshold. If the current load change mode is a rapid load change mode, then the adjustment parameters for each ammonia injection zone are the second adjustment step size and the second adjustment threshold. If the current load change mode is a frequent load change mode, then the adjustment parameters for each ammonia injection zone are the third adjustment step size and the third adjustment threshold. Wherein, the first adjustment step size is less than the second adjustment step size, which is less than the third adjustment step size, and the first adjustment threshold is less than the second adjustment threshold, which is less than the third adjustment threshold.

6. The method of claim 1, wherein, When controlling the valves of each ammonia injection zone to inject ammonia according to the target control parameters and adjustment parameters of each ammonia injection zone, the following is included: If a first target zone is determined to have a nitrogen oxide concentration greater than a first preset concentration value within a preset time period, then the valve opening of the first target zone is increased by a fourth adjustment step. If a second target zone is determined to have a nitrogen oxide concentration that is less than a second preset concentration value within a preset time period, then the valve opening of the second target zone is reduced by a fifth adjustment step.

7. The method of claim 6, wherein, When adjusting the first target partition or adjusting the second target partition, the following are included: If the nitrogen oxide concentration in the first target zone is still greater than the first preset concentration value within a preset time period, the first audible and visual alarm action is triggered. Alternatively, if the nitrogen oxide concentration in the second target zone remains lower than the second preset concentration value within a preset time period, then the second audible and visual alarm action is triggered.

8. The method of claim 3, wherein, Before determining the target control parameters for each ammonia injection zone from the target full-load range control parameter preset table based on the current load mode, the process includes: Select several typical load points of coal-fired power units; The coal-fired power unit was operated stably at each load point. The concentration of nitrogen oxides at the outlet of the selective catalytic reduction denitrification system was measured. The valve opening of each ammonia injection zone was adjusted until the concentration of nitrogen oxides at the outlet of the selective catalytic reduction denitrification system reached a uniform state. Record the valve opening value of each ammonia injection zone at each load point to achieve a uniform nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system, and obtain the valve opening table.

9. The method of claim 3, wherein, Before determining the target control parameters for each ammonia injection zone from the target full-load range control parameter preset table based on the current load mode, the method further includes: Select several typical load points of coal-fired power units; The coal-fired power unit was operated stably at each load point. The concentration of nitrogen oxides at the outlet of the selective catalytic reduction denitrification system was measured. The ammonia injection rate of each ammonia injection zone was adjusted until the concentration of nitrogen oxides at the outlet of the selective catalytic reduction denitrification system reached a uniform state. Record the actual ammonia injection flow rate and total ammonia injection flow rate of each ammonia injection zone at each load point when the nitrogen oxide concentration at the outlet of the selective catalytic reduction denitrification system reaches a uniform state. Calculate the allocation coefficient for each ammonia injection zone, where the allocation coefficient is the ratio of the actual ammonia injection flow rate to the total ammonia injection flow rate for the corresponding zone, and obtain the allocation coefficient table.

10. The method of claim 3, wherein, If the selective catalytic reduction denitrification system is equipped with a zoned flow measurement device, then the target full load range control parameter preset table is a distribution coefficient table; if the selective catalytic reduction denitrification system is not equipped with a zoned flow measurement device, then the target full load range control parameter preset table is a valve opening table.

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