A double-reheat unit flue damper zoning regulation system and method

Abstract

This invention discloses a flue gas damper zoning adjustment system and method for a double reheat unit, solving the problem of dynamic steam temperature exceeding or failing to meet standards due to uneven distribution of flue gas parameters at the tail-end three-flue section and deviation of damper adjustment effect from design conditions. The system includes: grid-type damper blades, comprising a flue gas damper with m*n blades, all blades in each row rotating around the same central axis, each blade rotating independently; a tail-end three-flue flow simulation system, which optimizes the opening of the grid-type damper blades and verifies the flue gas flow distribution based on the real-time reheat steam temperature requirement of the load, and transmits the blade opening combination result to the command output system; the command output system converts the blade opening combination result into blade rotation action for damper zoning adjustment. This prevents local overheating of the heating surface or failure of the reheat steam temperature to meet standards, improving the unit's operational stability.

Description

Technical Field

[0001] This invention relates to the field of industrial automation technology, and in particular to a zoned adjustment system and method for flue dampers in a secondary reheat unit. Background Technology

[0002] Supercritical double reheat units represent a significant upgrade in thermal power technology, increasing main steam pressure to over 25 MPa and temperature to over 560℃. Existing double reheat boilers with a three-flue tail section typically have three flues at the tail end, housing primary low-temperature reheat, secondary low-temperature reheat, and superheated surfaces respectively, with a set of flue gas dampers at each flue outlet. These three sets of dampers usually operate independently, adjusting the damper opening to change the flue gas flow and achieve the set primary and secondary reheat steam temperatures. Currently, by introducing double reheat technology, steam re-enters the boiler's three flues at the tail end after performing work in the ultra-high-pressure cylinder and high-pressure cylinder, undergoing reheating in the boiler (primary and secondary reheat), thus forming a more efficient working fluid cycle. This significantly improves thermal efficiency, achieving energy savings and reducing carbon dioxide emissions.

[0003] For example, CN115076679A, a method for controlling the reheat steam temperature in a three-flue secondary reheat boiler, proposes segmented control logic for the reheat steam outlet temperature and the low-temperature section temperature, which can improve the response speed of the reheat steam temperature during transient processes. However, because the control model does not use real physical mechanisms, it cannot capture the problem of uneven distribution of flue gas parameters on the flue cross-section causing the heat distribution ratio to deviate from the ideal state. This patent is also merely a manual disassembly of traditional control logic and does not discuss solutions for actual operational problems such as partial combustion that lead to unsatisfactory flue gas flow distribution. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of dynamic steam temperature exceeding or failing to meet standards caused by uneven distribution of flue gas parameters at the three flue sections at the tail end and deviations from the design conditions when a secondary reheat boiler in a coal-fired power plant operates under varying loads or other conditions deviating from the design conditions. This invention provides a flue damper zone adjustment system and method for secondary reheat units, which effectively realizes the precise proportional distribution of flue gas flow in the flue, achieves precise adjustment of reheat steam temperature, improves the unit's adaptability to changes in operating conditions, and significantly enhances the overall operational stability of the unit.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A secondary reheat unit flue damper zone regulation system includes: The grid-type baffle blade includes a flue baffle, wherein the flue baffle includes m*n blades, and all blades in each column rotate around the same central axis, with each blade rotating independently. The tail-end three-flue flow simulation system optimizes the opening of the grid-type baffle blades and verifies the flue gas flow distribution based on the reheat steam temperature requirements of the real-time load. After completion, the blade opening combination results are transmitted to the command output system. The command output system converts the blade opening combination results into blade rotation actions for baffle zone adjustment.

[0006] The flue gas duct damper zone adjustment system provided by the present invention achieves zone adjustment by setting grid-type damper blades. Each blade can rotate independently according to a set opening degree, which can effectively realize the precise proportional distribution of flue gas flow in the flue.

[0007] As a preferred embodiment, it includes: a tail-end three-channel inlet flue gas temperature and velocity testing device, which obtains flue gas velocity and temperature distribution information on the flue gas cross-section through inverse convolution.

[0008] A method for zoned adjustment of flue dampers in a double reheat unit includes the following steps: S1: Real-time measurement or CFD simulation calculation is used to obtain the real-time results of flue gas parameter distribution at the inlet interface of the three tail flues; S2: Calculate the required heat exchange in each area of ​​the heating surface based on the temperature measurement results of each heating surface in the three flues and the monitoring results of the reheat steam parameters; S3: Convert the heat exchange required in each area of ​​the heated surface into flue gas flow rate, obtain the expected opening of each blade of the grid baffle based on the flow resistance characteristics, and solve the optimal opening through a multi-objective optimization algorithm. S4: Convert the optimal opening of the baffle blades into the rotation direction and amplitude of each blade, and adjust the baffle accordingly.

[0009] The present invention provides a method for zoned adjustment of flue dampers in a secondary reheat unit. It uses measurement / CFD calculation method to obtain detailed distribution of flue gas parameters on the inlet section of the three tail flues. Therefore, compared with other methods (assuming uniform distribution of flue gas parameters), it can obtain more accurate local heat transfer conditions of each heat-receiving surface in the flue.

[0010] Because it possesses the real distribution of flue gas parameters, fine-tuning methods for grid-type adjustment, and the heat requirement of each heating surface (determined based on the target values ​​of primary / secondary reheat steam temperature), it can obtain the appropriate resistance of each blade corresponding to the flow channel under the target heat distribution result through a series of CFD calculations. In other words, it can effectively sense the heat transfer rate of the local heating surface under real-time flue gas parameters and heat transfer conditions, thereby effectively preventing the phenomenon of local overheating of the heating surface or the reheat steam temperature not meeting the standard.

[0011] Preferably, the optimization objectives of the multi-objective optimization algorithm include satisfying the target value for heat exchange in each flue, minimizing the total flow resistance loss, and minimizing the rate of change of the baffle opening; the constraints include the range of the baffle opening, the proportion of flue gas flow distribution, and the wall temperature of the heat exchange surface being less than or equal to the allowable temperature of the material; in the multi-objective optimization process, a CFD simulation model is used to evaluate each candidate solution, calculate the objective function value, and obtain the Pareto optimal solution set through iterative updates, and select the optimal combination of blade openings from the optimal solution set.

[0012] Preferably, the flow resistance characteristic analysis includes: establishing a geometric model of the baffle through CFD simulation, simulating the flow field distribution under different opening degrees, extracting the pressure difference before and after the baffle, calculating the drag coefficient in combination with the flow rate, and obtaining the fitting curve of the baffle opening degree and the drag coefficient.

[0013] Preferably, step S4 includes: determining whether the opening calibration of the baffle actuator is accurate; if there is a calibration deviation, correcting it; recording the actual opening of each blade; calculating the difference between the target opening and the current opening; determining the adjustment range and direction of movement for each blade; converting the blade adjustment range and direction of movement into action commands for the baffle actuator; after the action command is sent, collecting the feedback signal of the actuator in real time; if the deviation between the feedback opening and the target opening exceeds a threshold, issuing a fine-tuning command for correction; if a fault signal occurs, immediately stopping the adjustment action and sending an alarm signal.

[0014] Preferably, S2 includes: establishing a CFD simulation model of the three tail flues, using the real-time results of the flue gas parameter distribution as the inlet boundary conditions, calculating the radiative heat transfer between the flue gas and the pipe wall, and between the pipe wall and the working fluid, and using the in-pipe flow heat transfer model to calculate the temperature change and heat absorption of the working fluid in the heat transfer surface; obtaining the actual heat transfer of the working fluid in the heat transfer surface based on the coupled heat exchange between the flue gas side and the working fluid side; comparing the reheat temperature with the target value, and if there is a deviation, changing the heat transfer of each flue by changing the flue gas flow distribution.

[0015] Preferably, in S1, when performing CFD simulation calculations, a geometric model consistent with the actual boiler structure is constructed, the constructed geometric model is simplified, and the simplified geometric model is meshed, with the mesh of the furnace and burner areas being fined and the mesh of the tail flue area being enlarged.

[0016] As a preferred approach, after solving for the optimal opening degree using a multi-objective optimization algorithm, the optimal opening degree is input into the CFD model as the boundary condition of the baffle. The flow field and temperature field of the three tail flues are recalculated to verify whether the heat distribution of the flue gas under the optimized opening degree meets the objective conditions. If the verification result does not meet the requirements, the weight of the objective function or the optimization conditions are adjusted, and multi-objective optimization is performed again until the verification result meets the requirements.

[0017] Preferably, whether the flue gas heat distribution under the optimized opening meets the target conditions includes: whether the heat exchange of each heat exchange surface reaches the target value, whether the deviation between the calculated value of the primary / secondary reheat steam temperature and the target value is within the allowable range, whether there is any abnormality in the flue gas flow rate, and whether the resistance loss after the damper adjustment meets the constraint requirements.

[0018] Therefore, this invention has the following beneficial effects: It designs a grid-type three-flue outlet baffle structure and corresponding adjustment technology. Each small blade in the novel grid structure can swing independently, enabling adjustment of the opening and flow resistance of the corresponding flow channel region, and distributing reasonable flue gas flow and heat to each region. This effectively improves the problem of severely uneven heat exchange distribution on the tube bundles of the heating surface, prevents local overheating of the heating surface or substandard reheat steam temperature, and significantly improves the overall operational stability of the unit. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the steps of the secondary reheat unit flue damper zone adjustment method in this invention.

[0020] Figure 2 This is a schematic diagram of a flue gas damper structure in the prior art.

[0021] Figure 3 This is a schematic diagram of the flue gas baffle structure in this invention.

[0022] Figure 4 This is a schematic diagram showing the velocity distribution at the outlet of a conventional baffle when the unit is operating at 50% load.

[0023] Figure 5 This is a schematic diagram showing the velocity distribution at the outlet of the grid-type partitioned baffle when the unit is operating at 50% load.

[0024] Figure 6 This is a schematic diagram showing the velocity distribution at the outlet of a conventional baffle when the unit is operating at 75% load.

[0025] Figure 7 This is a schematic diagram showing the velocity distribution at the outlet of the grid-type partitioned baffle when the unit is operating at 75% load. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Example 1: This embodiment provides a method for zoned adjustment of flue dampers in a secondary reheat unit, such as... Figure 1As shown, the operation process is as follows: Step 1, real-time measurement or CFD simulation calculation is used to obtain the real-time results of the flue gas parameter distribution at the inlet interface of the three flues at the tail end; Step 2, based on the temperature measurement results of each heating surface of the three flues and the monitoring results of the reheat steam parameters, the required heat exchange of each area of ​​the heating surface is calculated; Step 3, the required heat exchange of each area of ​​the heating surface is converted into flue gas flow rate, and the expected opening of each blade of the grid baffle is obtained based on the flow resistance characteristics analysis, and the optimal opening is solved by a multi-objective optimization algorithm; Step 4, the optimal opening of the baffle blade is converted into the rotation direction and amplitude of each blade, and the baffle is adjusted in zones.

[0027] This embodiment provides a method for zoned adjustment of flue gas dampers in a double reheat unit. It features accurate distribution of flue gas parameters, fine-tuning of the grid, and the heat requirement of each heating surface (determined based on the target values ​​of primary / secondary reheat steam temperature). Therefore, it can obtain the appropriate resistance of each blade's corresponding flow channel under the target heat distribution result through a series of CFD calculations. This effectively senses the heat exchange rate of local heating surfaces under real-time flue gas parameters and heat exchange conditions, thereby effectively preventing local overheating of heating surfaces or substandard reheat steam temperature, and significantly improving the overall operational stability of the unit.

[0028] The following examples and specific application scenarios further illustrate the technical solution and effects of the present invention. The following examples are explanations of the present invention, but the present invention is not limited to the following examples.

[0029] Double reheat coal-fired power units have significant thermal inertia, leading to frequent fluctuations in key parameters such as steam temperature during transient operations under varying loads. Therefore, regulating the reheat steam temperature becomes crucial for ensuring the safe and stable operation of the unit. Generally, coarse adjustments are made by controlling the ratio of coal to water feed, followed by fine adjustments using reheat steam temperature regulation technology on the flow field side.

[0030] The reheat steam temperature regulation technology on the flow field side mainly includes the tail three flue baffle regulation technology. By changing the opening of the flue gas baffles in each of the three flues at the tail, the resistance of the airflow through each flue is changed, so that the amount of flue gas passing through different flues changes, thereby changing the heat absorption ratio of each heating surface and realizing the regulation of reheat steam temperature.

[0031] Generally, louvered baffles are used, and their top view is as follows: Figure 2 As shown: The three flue ducts at the rear are separated by two partition walls. Each flue duct is equipped with i, j, and k blades forming a flue gas damper. Each blade can rotate around its central axis (the dotted line in the diagram) to a set opening degree. Generally, the rotation angle (opening degree) of a group of flue gas damper blades is the same, and they do not rotate independently. There are also control methods that use multiple actuators to control a group of dampers; in this case, the blade opening degrees of different sections within a group of dampers can be different. This is a flue gas damper structure widely used in power plants.

[0032] Currently, there are several optimization methods for adjusting the tail-end three-channel baffle: (1) Optimize the arrangement of flue and baffle: By proposing a new three-flue heating surface arrangement and flue gas baffle installation method, the flow channel structure is optimized so that the flue gas can exchange heat with the heating surface in the expected proportion as much as possible during the flow of the tail flue.

[0033] Because optimizing the flue layout is generally based on the boiler's operating history or experience to determine the required heat ratio of each heating surface and to optimize and modify the layout; on the other hand, the uneven distribution of flue gas parameters on the cross-section of the three flues at the tail end is caused by factors such as uneven combustion in the furnace and changes in the flue gas flow direction. When the air-coal boundary or operating conditions change, the regularity of this uneven distribution will also change. Therefore, specific flue layout optimization strategies cannot solve the flow distribution problem of the three flues under more operating conditions.

[0034] Because optimizing the baffle arrangement is generally used to solve the actual control logic problem of flue gas flow under the complex flow resistance characteristics of three flues, it is also based on the ideal situation of uniform distribution of incoming flue gas parameters. At the application level, it can be used as an adjustment idea for baffle blades, but it still cannot predict or solve the problem of uneven distribution of flue gas parameters in the flue section causing the operating effect to deviate from the ideal adjustment state.

[0035] At this time, the flue gas temperature or flow rate is low in some areas, resulting in poor heat exchange. The heating surfaces are not heating enough for the reheat steam, and the reheat steam may not meet the parameters. At the same time, other heating surfaces are at risk of local dynamic overheating due to heat exchange with high temperature or excessive flue gas.

[0036] (2) Advanced control technology guides the damper adjustment: The key measurement parameters of the three flues at the tail end (such as reheat steam temperature, boiler load, water-coal ratio, etc.) are used as inputs, and the opening value or movement of each damper is used as outputs. Based on the knowledge of control science or computer science, the correlation between input and output parameters is established to achieve the adjustment of damper opening with the goal of reheat steam regulation.

[0037] Because the input parameters for control science are generally derived from actual measurement points or other operational data in power plants, the modeling of the controlled system lacks guidance from physical mechanisms. Furthermore, since control modeling does not use real physical mechanisms, it cannot capture the problem of uneven distribution of flue gas parameters on the flue cross-section causing the heat distribution ratio to deviate from the ideal state (on the one hand, it is impossible to install an infinite number of measurement points on the flue, and on the other hand, uneven distribution of flue gas parameters is greatly affected by the combustion conditions on the furnace side, making it difficult to achieve direct control and prediction through data analysis).

[0038] (3) Simulation-guided baffle adjustment: Generally, based on the knowledge of flow resistance characteristics in engineering fluid mechanics or the knowledge of three-dimensional flow and heat transfer simulation in computational fluid mechanics, the true shape of flue gas flow and temperature distribution in the furnace is calculated. Based on this, the optimal opening value of the flue gas baffle is calculated according to the required flue gas heat in different areas.

[0039] Because the common louvered baffle blade structure is a single piece design, and the distribution of incoming flue gas parameters is extremely uneven, no matter how detailed the flue gas parameter distribution is obtained through simulation, it is impossible to achieve the expected flue gas heat distribution purpose by using a single piece of "extensive" adjustment.

[0040] In summary, in view of the deficiencies in the prior art, this embodiment provides a method for zoned adjustment of flue dampers in a secondary reheat unit, which is mainly used to solve the problem of local overheating of the heating surface in the three flues at the tail end and the risk of parameters not meeting the standards.

[0041] like Figure 1 As shown, a method for zoned adjustment of flue dampers in a secondary reheat unit specifically includes the following steps: Step 1: Obtain the real-time distribution of flue gas parameters at the inlet interface of the three tail flues through CFD simulation calculation.

[0042] In the process of flue damper zone adjustment, the first step is the basic data acquisition step, and its accuracy directly determines the reliability of subsequent adjustments. Its core objective is to obtain detailed distribution of flue gas parameters on the cross section, including key indicators such as temperature, velocity, and component concentration, so as to provide data support for subsequent heat exchange calculation and damper adjustment.

[0043] When obtaining the real-time distribution of flue gas parameters at the inlet interface of the three tail flues using CFD simulation, the pulverized coal combustion flow state at the burner should be calculated according to the actual air-coal boundary to complete the full-process simulation calculation of flue gas flowing from the furnace to the three tail flues.

[0044] Specifically, this includes: First, constructing a geometric model consistent with the actual boiler structure, including key components such as the furnace, burner, flue, and heat exchange surface. Geometric simplification should retain the core structures that affect the flow field (such as guide vanes, flue gas deflectors, and tube bundle arrangements). When meshing the computational domain (i.e., the simplified geometric model), structured or unstructured meshes should be used. The mesh in the furnace and burner areas should be finer (e.g., mesh size ≤ 50 mm), while the mesh in the tail flue area can be appropriately enlarged (e.g., mesh size ≤ 100 mm). Ensure that the mesh quality meets the computational convergence requirements (e.g., twist rate < 0.8, orthogonality > 0.3).

[0045] Boundary conditions should be set according to the actual air and coal operation parameters. The flow rate, temperature, and pressure of primary and secondary air should be input according to the real-time operation data of the boiler. Parameters such as coal particle size distribution, coal feed rate, and volatile matter content should be set according to the coal type analysis report.

[0046] The CFD solution process can be viewed as solving for the values ​​of unknown variables based on known boundary conditions. For example, given a line segment on a coordinate axis, with the starting point A having coordinates of (0, 0) [boundary condition] and the ending point B having coordinates of (1, 1) [boundary condition], and the algebraic expression of the line segment being y=x [governing equation], the coordinate values ​​of any point on the line segment [unknown variables] can be solved.

[0047] This simulation utilizes a high-precision DNS model combined with a combustion model, a PDF model, a component transport model (EDM, etc.), or a flame surface model, considering the volatile matter release of pulverized coal, coke combustion, and radiative heat transfer processes. The computational domain covers the entire flow of flue gas from the furnace outlet to the three-channel tail outlet. The calculation step size is set according to the flow field change rate. The iteration convergence criterion can be set to a residual of less than 1e-6, and the fluctuation limits of the average temperature and velocity values ​​at key sections can be added (e.g., less than 2%). After the simulation is completed, the calculation results need to be verified by comparing them with real-time measured data to ensure the accuracy and reliability of the CFD model. Specific indicators include: temperature deviation controlled within ±5% and velocity deviation controlled within ±10%.

[0048] Step 2: Based on the temperature measurement results of each heating surface in the three flues and the monitoring results of reheat steam parameters, calculate the heat exchange required for each area of ​​the heating surface.

[0049] The second step is a crucial link between basic data and regulation strategies. It aims to accurately calculate the required heat transfer for each heat exchange surface in the three tail flues using CFD simulation methods, based on operating conditions such as real-time boiler load, air-to-coal ratio, water-to-coal ratio, primary / secondary reheat steam temperature measurements, and target values. This provides a target basis for subsequent damper opening optimization. The core of the heat transfer calculation is establishing a heat exchange model between the flue gas side and the working fluid side, dynamically adjusting the calculation boundary based on real-time operating parameters to ensure a high degree of match between the results and actual operating conditions. The second step provides a method for calculating heat transfer; the third step, based on the method provided in the second step, calculates the heat transfer under different blade openings.

[0050] Specifically, it includes: Step (1): Define the input parameters required for calculation, including the boiler real-time load (expressed as a percentage of rated load), air-coal ratio (the ratio of primary air to secondary air flow rates), water-coal ratio (the ratio of feedwater flow rate to coal feed rate), and the measured and target values ​​of primary and secondary reheat steam temperatures. These parameters need to be collected in real time from the boiler DCS system, with the collection frequency consistent with step S1 (not less than 1Hz) to ensure time synchronization of the parameters. Among them, the target values ​​of primary / secondary reheat steam temperatures are set according to the unit operation procedures and can be dynamically adjusted according to the grid load demand and steam quality requirements.

[0051] Step (2): The flue gas parameter distribution obtained in real time in the first step is used as the inlet boundary condition and input into the heat exchange surface model (i.e., CFD simulation model) of the three flue gas ducts at the tail.

[0052] The heat transfer surface model needs to accurately simulate the arrangement of the tube bundle (such as in-line or staggered), tube diameter, tube spacing, fin structure and other geometric parameters. The wall function method is used to handle the convective heat transfer between flue gas and tube wall, and the radiative heat transfer model (such as discrete coordinate method) is combined to calculate the radiative heat transfer between flue gas and tube wall, and between tube wall and working fluid.

[0053] On the working fluid side, an in-pipe flow heat transfer model is used. Based on parameters such as the flow rate, pressure, and temperature of the feedwater or steam, the temperature change and heat absorption of the working fluid within the heat exchange surface are calculated. By coupling the heat exchange processes on the flue gas side and the working fluid side, the actual heat transfer of each flue heat exchange surface can be obtained. The calculated reheat steam temperature is compared with the target value. If there is a deviation, the heat transfer of each flue is changed by adjusting the flue gas flow distribution (i.e., the opening of the subsequent dampers) to bring the reheat steam temperature to the target value.

[0054] For example, when the measured reheat steam temperature is lower than the target value, the flue gas flow rate of the corresponding flue needs to be increased to improve the heat exchange capacity of that flue; conversely, the flue gas flow rate should be reduced. During the heat exchange calculation, the influence of flue gas components (such as CO2, H2O, O2, etc.) on radiative heat exchange must be considered, and gray-body or non-gray-body radiation models should be used for correction to ensure the accuracy of the heat exchange calculation. Simultaneously, sensitivity analysis of the heat exchange under different load conditions is required to clarify the impact of load changes on the heat exchange distribution of each flue, providing a basis for the adaptive design of damper regulation.

[0055] Step 3: Convert the heat exchange required for each area of ​​the heated surface into flue gas flow rate, back-calculate the expected opening of each blade of the grid baffle, and perform optimization and heat distribution verification.

[0056] The third step is the core decision-making process for flue gas damper adjustment. The expected opening of each damper blade is initially determined using the flow resistance characteristic analysis method. The multi-objective optimization problem of adjusting the damper opening to meet the heat exchange distribution requirements is solved. After the optimization is completed, the flue gas heat distribution under the optimized opening is simulated and verified to ensure that the damper adjustment can not only meet the heat exchange distribution requirements, but also take into account the objectives of minimizing flow resistance loss and maximizing operational stability.

[0057] Specifically, it includes: Flow resistance characteristic analysis is the foundation for initially determining the expected damper opening. The damper's resistance characteristics are related to factors such as blade angle, flue structure, and flue gas flow rate. The relationship curve between damper opening and drag coefficient needs to be established through experiments or CFD simulations. Experimental methods can be conducted in a cold wind tunnel, measuring flow rate and pressure loss at different damper openings to calculate the drag coefficient.

[0058] The CFD simulation method involves constructing a detailed geometric model of the baffle, simulating the flow field distribution at different opening angles (0°-90°, in 5° increments), extracting the pressure difference before and after the baffle, and calculating the drag coefficient based on the flow rate. Through data analysis, a fitting formula for the relationship between the baffle opening and the drag coefficient is obtained, providing a basis for initial opening setting. For example, when increasing the flue gas flow rate in a certain flue, the initial baffle opening is set to 60°-70°, corresponding to a smaller drag coefficient, which facilitates flue gas flow; if a reduction in flow rate is required, the opening is set to 20°-30°, achieving flow rate adjustment by increasing the drag.

[0059] Solving multi-objective optimization problems requires clearly defining the optimization objectives and constraints. In this embodiment, the optimization objectives mainly include: first, ensuring that the heat exchange of each flue meets the target value (e.g., ensuring that the deviation between the primary / secondary reheat steam temperature and the target value is ≤ ±2℃); second, minimizing the total flow resistance loss (e.g., ensuring that the total pressure drop increment after baffle adjustment is ≤ 50Pa); and third, minimizing the rate of change of baffle opening (to avoid wear of the mechanism due to frequent adjustments). Constraints include the baffle opening range (0°-90°), the flue gas flow distribution ratio (e.g., ensuring that the flow rate of each flue is not less than 30% of the design value), and the heat exchange surface wall temperature not exceeding the material's allowable temperature (generally 650℃).

[0060] The optimization algorithm can be either the non-dominated sorting genetic algorithm (NSGA-II) or the particle swarm optimization algorithm. The opening degree of each baffle is used as the optimization variable, and the heat exchange deviation, resistance loss and opening change rate are used as the objective functions to perform multi-objective optimization.

[0061] During the optimization process, the CFD simulation model (i.e. the heat transfer surface model in the second step) needs to be called to evaluate each candidate solution, calculate the objective function value, and obtain the Pareto optimal solution set through iterative updates. Then, the optimal opening combination is selected from the set according to the actual engineering requirements (such as prioritizing the stability of steam temperature). The optimal opening combination includes the opening of each blade.

[0062] After optimization, a simulation verification of flue gas heat distribution under the optimized opening degree is performed. Specifically, this includes: inputting the optimal opening degree as the baffle boundary condition into the CFD model, recalculating the flow and temperature fields of the three tail flues, verifying whether the heat transfer of each heat exchange surface reaches the target value, whether the deviation between the calculated primary / secondary reheat steam temperature and the target value is within the allowable range, and checking for abnormalities such as eddies or flow deviations in the flue gas flow, and whether the resistance loss after baffle adjustment meets the constraint requirements. If the verification results do not meet the requirements, the process must return to the optimization stage, adjust the objective function weights or constraint conditions, and re-optimize until the results are satisfactory. The time step of the simulation verification must match the actual operating conditions to ensure that the dynamic response characteristics of the verification results conform to the actual adjustment process.

[0063] The third step is the core decision-making process for flue gas damper adjustment. The expected opening of the damper is determined by analyzing the flow resistance characteristics, and then the optimal opening is solved by a multi-objective optimization algorithm. Simulation verification is then performed to ensure that the damper adjustment can meet the heat exchange distribution requirements while minimizing flow resistance loss and maximizing operational stability.

[0064] Step 4: Send the baffle blade movement command to adjust the baffle.

[0065] The fourth step is the final execution stage of flue gas damper adjustment. It is responsible for converting the target damper blade opening value verified in the third step into the rotational direction and amplitude of each blade, and sending this information to the reheat steam conditioning system to achieve precise damper adjustment and complete the entire control loop. This step requires resolving the mapping relationship between the "target opening" and the "mechanical action," ensuring the accuracy of the direction and amplitude of the action, while also considering the response speed and stability of the conditioning system.

[0066] Specifically, it includes: Step (4.1): Analysis of the target value of the baffle blade opening.

[0067] The regulating baffle at the tail end of the three flues typically consists of multiple blades (grid-type partitioned baffles, determined according to the flue width). Each blade needs to be adjusted synchronously to ensure uniform flow distribution. Therefore, the target opening value for each blade (consistent with the optimization results) must be clearly defined. The opening value is defined as 0° when the blade is fully closed and 90° when it is fully open. It is necessary to confirm whether the opening calibration of the baffle actuator is accurate. If there is a calibration deviation, it needs to be corrected using a calibration formula. For example, the actual opening is equal to the product of the target opening and the correction coefficient (the correction coefficient is calibrated experimentally and is generally between 0.98 and 1.02). At the same time, the actual opening of each blade needs to be recorded (collected by position sensors), and the difference between the target opening and the current opening needs to be calculated to determine the adjustment range of each blade (e.g., if the current opening is 40° and the target opening is 60°, the adjustment range is +20°, i.e., a 20° clockwise rotation; if the current opening is 70° and the target opening is 50°, the adjustment range is -20°, i.e., a 20° counterclockwise rotation).

[0068] Step (4.2): Conversion of movement direction and amplitude.

[0069] The conversion of the direction and amplitude of motion needs to be considered in conjunction with the structural characteristics of the baffle actuator. Baffle actuators typically employ electric or pneumatic actuators. Electric actuators use a motor to drive a reducer, which in turn rotates the blades. Pneumatic actuators use a cylinder to push a linkage mechanism to achieve the motion. For electric actuators, the adjustment amplitude needs to be converted into the number of motor rotations or pulses. For example, if the actuator's reduction ratio is 1:100, a 1° blade rotation corresponds to a 100° motor rotation (1 / 3.6 of a rotation). Therefore, a 20° adjustment amplitude corresponds to a 2000° motor rotation (approximately 5.56 rotations). The number of rotations is then converted into control pulse signals using a pulse encoder (e.g., 1000 pulses per rotation, so 5.56 rotations correspond to 5560 pulses). The direction of motion is achieved through the motor's forward and reverse rotation control. Clockwise rotation corresponds to forward motor rotation, and counter-clockwise rotation corresponds to reverse motor rotation. The direction logic must be clearly defined in the control program to avoid adjustment failure due to incorrect direction. For pneumatic actuators, the adjustment range needs to be converted into the extension and retraction of the cylinder. The cylinder's operating speed is controlled by adjusting the air pressure to ensure smooth blade rotation and avoid impact.

[0070] Step (4.3): Generation and sending of action instructions.

[0071] The generation and transmission of action commands must adhere to the communication protocol of the reheat steam regulating system. The regulating system typically uses a DCS (Distributed Control System) or PLC (Programmable Logic Controller) as its control core. Damper action commands must be encapsulated according to the system's defined communication format (such as Modbus or Profibus protocols), including information such as device address, command type (regulation command), blade number, target opening, and action speed. The action speed setting must balance regulation efficiency and system stability; generally, the blade rotation speed is controlled between 5° and 10° / s to avoid excessive speed causing drastic flow field fluctuations, or excessive speed affecting the regulation response time. After the command is sent, feedback signals from the actuator (including current opening, action status, fault signals, etc.) must be collected in real time for closed-loop monitoring. If the deviation between the feedback opening and the target opening exceeds ±1°, a fine-tuning command is issued for correction. If fault signals such as jamming or overcurrent occur, the regulation action must be stopped immediately, an alarm signal issued, and maintenance personnel notified for handling.

[0072] After adjustment, the adjustment effect needs to be confirmed. Using real-time measurement or CFD simulation from the first step, the flue gas parameter distribution and reheat steam temperature values ​​of the three tail flues are collected again to check if the target requirements are met (e.g., as mentioned earlier, the deviation between the primary / secondary reheat steam temperature and the target value is ≤ ±2℃). If the requirements are met, the adjustment is complete; if not, the reasons for the deviation need to be analyzed (e.g., actuator lag, flow field changes exceeding expectations, etc.). Return to the third step to recalculate the optimization, adjust the damper opening target value, and execute the fourth step again until the adjustment effect is satisfactory. The entire adjustment process needs to be recorded, including the input parameters, calculation results, action commands, and feedback signals for each step, providing data support for subsequent adjustment strategy optimization and fault diagnosis.

[0073] This embodiment also provides a secondary reheat unit flue damper zone adjustment system, including: The tail-end three-channel inlet flue gas temperature and velocity testing device obtains the flue gas velocity and temperature distribution information on the cross section by inverse convolution; The tail-end three-flue flow simulation system optimizes the opening of the grid-type baffle blades and verifies the flue gas flow distribution based on the reheat steam temperature requirements of the real-time load. After completion, the blade opening combination results are transmitted to the command output system. The command output system converts the blade opening combination result into blade rotation action for blade adjustment.

[0074] To achieve the purpose of zoning control, such as Figure 3As shown, the grid-type baffle blades include flue baffles, which consist of m*n blades (i.e., a single louver-type baffle blade is cut into m pieces). All blades in each row rotate around the same central axis and can each be set with an independent opening degree, meaning each blade can rotate independently. Unlike traditional louver-type blades, each small blade in the new grid structure can swing independently, enabling adjustment of the opening degree and flow resistance in the corresponding flow channel area, and distributing reasonable flue gas flow and heat to each area. Compared with existing technologies, this new structure and adjustment technology can effectively improve the problem of severely uneven heat exchange distribution on the tube bundles of the heating surface, prevent local overheating of the heating surface or substandard reheat steam temperature, and significantly improve the overall operational stability of the unit.

[0075] The method and system for zoned adjustment of flue dampers in a double reheat unit provided in this embodiment have the following beneficial effects: 1. It adopts a baffle structure design with grid-type blades, and each blade can rotate independently according to a set opening degree, which can effectively realize the precise proportional distribution of flue gas flow in the flue.

[0076] 2. CFD calculation method was used to obtain detailed distribution of flue gas parameters on the inlet section of the three tail flues. Compared with other methods (assuming uniform distribution of flue gas parameters), it can obtain more accurate local heat transfer conditions of each heat-receiving surface in the flue.

[0077] 3. It possesses real-time flue gas parameter distribution, fine-tuning grid-type adjustment methods, and heat requirements for each heating surface (determined based on primary / secondary reheat steam temperature target values). It can obtain the appropriate resistance of each blade's corresponding flow channel under the target heat distribution results through a series of CFD calculations. It can effectively sense the heat exchange rate of local heating surfaces under real-time flue gas parameters and heat exchange conditions, thereby effectively preventing local overheating of heating surfaces or substandard reheat steam temperature, and significantly improving the overall operational stability of the unit.

[0078] Example 2: This embodiment, based on Embodiment 1, uses real-time measurement instead of CFD simulation to obtain the real-time results of the flue gas parameter distribution at the inlet section of the three tail flues in the first step. It also provides specific data to illustrate the technical effectiveness of the secondary reheat unit flue damper zoning adjustment method of Embodiment 1.

[0079] When using real-time measurements, at least four temperature and velocity measurement points should be set up to ensure that the distribution of cross-sectional flue gas parameters obtained by deconvolution is not excessively distorted.

[0080] Specifically: When using real-time measurement methods, the principle of "multiple points evenly distributed, covering key areas" should be followed. Based on the boiler flue cross-sectional dimensions and flow field distribution characteristics, at least four temperature and velocity measurement points should be arranged. If the cross-sectional dimensions are large (e.g., width or height exceeding 3 meters), the area should be divided into grids, with 1-2 measurement points in each grid, ensuring the total number of measurement points meets the flow field reconstruction requirements. Temperature measurement typically uses armored thermocouples, whose measurement range must cover normal flue gas temperatures (generally 300-1200℃), with an accuracy class of no less than 0.5. Velocity measurement often uses Pitot tubes or hot-wire anemometers. Pitot tubes require simultaneous acquisition of dynamic and static pressure, and the flow velocity is calculated based on the flue gas density. Hot-wire anemometers are suitable for low-velocity conditions (velocity < 5 m / s), and attention should be paid to wear-resistant and anti-clogging designs. When arranging measuring points, locations with flow field distortions, such as flue corners and vortex zones, should be avoided. Priority should be given to straight sections with relatively uniform velocity distribution (generally within a range of 5-10 times the flue diameter). The data acquisition frequency should be no less than 1 Hz, with continuous acquisition time of no less than 5 minutes. After removing outliers, the average value should be taken as the representative value for that measuring point. Using multi-point measurement data, interpolation methods (such as Kriging interpolation or linear interpolation) can be used to reconstruct the parameter distribution of the entire cross-section, avoiding excessive distortion during deconvolution calculations due to insufficient measuring points, and ensuring that the spatial resolution of the flow field distribution meets the requirements of subsequent calculations. Tikhonov regularization is used to address the ill-conditioned problem of deconvolution. Input measuring point data, output 100×50 grid (or other higher resolution) temperature and velocity distributions. The calculation method is: the product of the mapping matrix from the measuring point to the grid and the data on the grid, minus the difference in the input measuring point data, the minimum square of the norm of the resulting difference, plus the sum of the product of the square of the norm of the data on the grid and the regularization parameter.

[0081] Specific implementation plan: Upgrade and renovate the tail-end three-flue flue gas damper and control system of a 1000MW ultra-supercritical double reheat unit in a power plant.

[0082] (1) Grille-type flue gas damper zone adjustment system.

[0083] In this embodiment, the zoned regulation system mainly consists of the following four parts: a tail-end three-duct inlet flue gas temperature and velocity testing system, a power plant data acquisition system, a tail-end three-duct flow simulation system, and a command output system.

[0084] Among them, the tail three flue inlet flue temperature and velocity testing system needs to arrange more than 4 measuring points at the tail three flue inlet cross section for deconvolution to obtain flue gas velocity and temperature distribution information on the cross section; (the real-time measurement function of the tail three flue inlet flue temperature and velocity testing system can be replaced by furnace side combustion and flue gas flow simulation, which can also obtain the flue gas parameter distribution on the cross section).

[0085] The tail-end three-flue inlet flue gas temperature and velocity testing system is connected to the power plant data acquisition system. The power plant data acquisition system synchronously transmits the measured and target values ​​of primary and secondary reheat steam temperatures, real-time boiler load, air-coal ratio, water-coal ratio, and other operating conditions, along with the results of the tail-end three-flue inlet flue gas temperature and velocity testing system, to the tail-end three-flue flow simulation system.

[0086] The tail-end three-duct flow simulation system performs optimization of the opening of the grid-type baffle blades and verification of flue gas flow distribution based on the reheat steam temperature requirements of the real-time load and the data transmitted from the power plant data acquisition system. After completion, the blade opening combination results are transmitted to the command output system.

[0087] The command output system converts the combined opening information transmitted from the tail three-channel flow simulation system into blade rotation motion, which is then executed by the reheat steam temperature control system.

[0088] (2) Evaluation method for flow field uniformity (uniformity of outlet flue gas velocity distribution).

[0089] The coefficient of variation, also known as the standard deviation or unit risk, can eliminate the influence of measurement scale and dimensions to some extent. It can be used to quantitatively analyze the dispersion of a set of data and is often used to measure the uniformity of the distribution of a variable across a cross-section. The larger the coefficient of variation value, the stronger the non-uniformity. The coefficient of variation is the ratio of the standard deviation to the mean of the variable of interest.

[0090] (3) Comparison of flow field uniformity before and after implementation.

[0091] (3.1) When the unit operates at 50% load (500MW), the velocity distribution at the damper outlet is as follows: Figure 4 , Figure 5 As shown, where: Figure 4 The result before modification (ordinary baffle). Figure 5 The result after modification (grid-type partition baffle).

[0092] It can be seen that the flow velocity is more uniform after the modification, and the high flow velocity region is significantly reduced.

[0093] Analysis of the coefficient of variation of velocity distribution: Before the modification, the coefficient of variation of velocity distribution at the outlet section was 0.797775, and after the modification, it was 0.724539. The coefficient of variation decreased by 9.18% after the modification, and the uniformity of the flow field distribution was significantly improved.

[0094] (3.2) When the unit operates at 75% load (750MW), the velocity distribution at the damper outlet is as follows: Figure 6 , Figure 7 As shown, where: Figure 6 The result before modification (ordinary baffle). Figure 7 The result after modification (grid-type partition baffle).

[0095] It is evident that: Firstly, with Figure 4 , Figure 5 In comparison, the flue gas flow distribution is more uniform under this operating condition (high load).

[0096] Statistical calculations show that the coefficient of variation of the velocity distribution at the outlet section was 0.764540 before the modification and 0.718400 after the modification. The coefficient of variation decreased by 6.04% after the modification, and the uniformity of the flow field distribution was significantly improved.

[0097] (4) The effect of the renovation plan.

[0098] (4.1) The accuracy of reheat steam temperature control is significantly improved.

[0099] After the upgrade, the grid-type flue gas damper zone control system achieves precise regulation of reheat steam temperature through a closed-loop control logic of "real-time parameter sensing - dynamic simulation optimization - precise command execution". Within the unit's variable operating range of 30%-100% rated load, the deviation is ≤±2℃, a 60% reduction compared to the ±5℃ deviation range before the upgrade.

[0100] In typical load variation scenarios, such as when the unit increases from 60% to 100% of its rated load, the maximum fluctuation in the primary reheat steam temperature before the modification reached 8°C, requiring manual intervention. After the modification, the heat exchange demand was predicted in advance by the flow simulation system, and the damper opening was dynamically adjusted synchronously, reducing the steam temperature fluctuation to 3°C without manual intervention. In addition, under coal type switching conditions (switching from the design coal type to the verification coal type with a 10% deviation in calorific value), the zone control system rapidly iterates and optimizes the damper opening by collecting parameters such as air-coal ratio and water-coal ratio in real time, significantly improving the unit's adaptability to changes in operating conditions.

[0101] (4.2) The uniformity of the flow field in the tail flue is greatly improved.

[0102] Measured data based on the coefficient of variation (Cv) evaluation method show that the uniformity of flue gas velocity distribution at the outlet cross-section of the three flues at the tail end is significantly improved after the modification. Before the modification, the average velocity at the outlet cross-section of the three flues was 8.2 m / s with a standard deviation of 2.5 m / s, and the calculated Cv = 0.305, indicating poor velocity uniformity. After the modification, through optimization and adjustment of the grid-type baffle and improvement of the flow guiding structure, the average velocity at the outlet cross-section is 8.5 m / s with a standard deviation of 1.45 m / s and a Cv = 0.171, indicating a significant improvement in velocity uniformity.

[0103] Looking at the details of the velocity distribution in each flue, before the modification, the velocity in the area near the wall of flue A reached a maximum of 11.8 m / s, while the velocity in the middle of flue C was the lowest at only 5.3 m / s, with a velocity difference of 6.5 m / s. After the modification, the velocity difference between the areas was reduced to 2.8 m / s (maximum 9.6 m / s, minimum 6.8 m / s). The improvement in flow field uniformity also directly improved the performance of downstream equipment, such as simultaneously improving the uniformity of ammonia concentration distribution at the inlet of the denitrification reactor, significantly reducing ammonia slip rate, and stabilizing denitrification efficiency.

[0104] (4.3) The economic efficiency of unit operation has been significantly improved. In terms of energy consumption indicators, the total flow resistance loss of the three flue gas ducts at the tail end was significantly reduced after the modification. Before the modification, the average increase in total pressure drop during the damper adjustment process was 125 Pa. After the modification, the total pressure drop increase was reduced to 72 Pa by optimizing the damper opening combination through a multi-objective optimization algorithm, and the pressure drop loss was reduced by 42.4%. Based on the annual operating hours of the unit of 6000h, flue gas flow rate of 1.2×106m3 / h, and induced draft fan efficiency of 0.9, the annual power consumption of the induced draft fan can be saved as follows: ΔP×Q×t / (3600×η)=(125-72)×1.2×106×6000 / (3600×0.9)≈1.06×108kWh. Calculated at the plant electricity price of 0.3 yuan / kWh, the annual electricity cost savings are approximately 318,000 yuan.

[0105] Regarding equipment wear and tear, the improved flow field uniformity and significantly reduced wall wear rate after the upgrade extended the maintenance cycle and substantially reduced annual maintenance costs. Simultaneously, the improved reheat steam temperature stability reduced thermal stress fluctuations on the heating surface, and the lifespan of the heat exchanger tubes is expected to be extended by 5-8 years, further reducing equipment replacement costs.

[0106] (4.4) Improved system reliability and intelligence level.

[0107] The upgraded grid-type flue gas damper zoning system adopts a dual-redundancy design, with key equipment (data acquisition server and actuator power supply) equipped with a master / slave switching mechanism, ensuring a system availability rate of over 99%. The system's intelligence level is significantly improved, achieving an "unattended, automatic adjustment" operation mode. Through seamless integration with the power plant's DCS system, key parameters such as damper opening, steam temperature deviation, and flow field variation coefficient are uploaded to the monitoring screen in real time, allowing maintenance personnel to remotely monitor the system's operating status. Simultaneously, the zoning system possesses self-diagnostic capabilities, monitoring actuator current and blade opening feedback signals in real time. When faults such as jamming or overcurrent occur, it automatically issues alarms and records fault logs, achieving a fault diagnosis accuracy rate of over 95%. This significantly reduces fault handling time for maintenance personnel, greatly improving equipment management efficiency.

[0108] (4.5) Environmental emission indicators have been consistently and stably met.

[0109] After the upgrade, thanks to precise control of reheat steam temperature and optimization of flow field uniformity, the unit's environmental emission indicators have been further improved. Regarding NOx emission control, the improved flow field uniformity at the denitrification reactor inlet makes ammonia injection more uniform, avoiding secondary pollution caused by localized excessive ammonia. Regarding sulfur dioxide emission control, the stable reheat steam temperature significantly improves the stability of the flue gas temperature at the desulfurization system inlet, reducing excessive emissions and earning the power plant a good environmental reputation.

[0110] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A double reheat unit boiler damper zoning system, characterized by, include: The grid-type baffle blade includes a flue baffle, wherein the flue baffle includes m*n blades, and all blades in each column rotate around the same central axis, with each blade rotating independently. The tail-end three-flue flow simulation system optimizes the opening of the grid-type baffle blades and verifies the flue gas flow distribution based on the reheat steam temperature requirements of the real-time load. After completion, the blade opening combination results are transmitted to the command output system. The command output system converts the blade opening combination results into blade rotation actions for baffle zone adjustment.

2. The secondary reheat unit flue damper zone regulation system according to claim 1, characterized in that, include: The tail section three flue inlet flue temperature and velocity testing device obtains flue gas velocity and temperature distribution information on the flue cross section through inverse convolution.

3. A method for zoned adjustment of flue dampers in a double reheat unit, applied to the zoned adjustment system for flue dampers in a double reheat unit as described in any one of claims 1-2, characterized in that, include: S1: Real-time measurement or CFD simulation calculation is used to obtain the real-time results of flue gas parameter distribution at the inlet interface of the three tail flues; S2: Calculate the required heat exchange in each area of ​​the heating surface based on the temperature measurement results of each heating surface in the three flues and the monitoring results of the reheat steam parameters; S3: Convert the heat exchange required in each area of ​​the heated surface into flue gas flow rate, obtain the expected opening of each blade of the grid baffle based on the flow resistance characteristics, and solve the optimal opening through a multi-objective optimization algorithm. S4: Convert the optimal opening of the baffle blades into the rotation direction and amplitude of each blade, and adjust the baffle accordingly.

4. The method for zoned adjustment of flue dampers in a secondary reheat unit according to claim 3, characterized in that, The optimization objectives of the multi-objective optimization algorithm include meeting the target value for heat exchange in each flue, minimizing the total flow resistance loss, and minimizing the rate of change of the baffle opening; the constraints include the range of the baffle opening, the proportion of flue gas flow distribution, and the wall temperature of the heat exchange surface being less than or equal to the allowable temperature of the material. In the multi-objective optimization process, a CFD simulation model is used to evaluate each candidate solution, calculate the objective function value, and obtain the Pareto optimal solution set through iterative updates. The optimal blade opening combination is then selected from the optimal solution set.

5. A method for zoned adjustment of flue dampers in a secondary reheat unit according to claim 3 or 4, characterized in that, The flow resistance characteristic analysis includes: establishing a geometric model of the baffle through CFD simulation, simulating the flow field distribution under different opening degrees, extracting the pressure difference before and after the baffle, calculating the drag coefficient in combination with the flow rate, and obtaining the fitting curve of the baffle opening degree and the drag coefficient.

6. A method for zoned adjustment of flue dampers in a secondary reheat unit according to claim 3 or 4, characterized in that, S4 includes: determining whether the opening calibration of the baffle actuator is accurate; if there is a calibration deviation, correcting it; recording the actual opening of each blade; calculating the difference between the target opening and the current opening; determining the adjustment range and direction of movement for each blade; converting the blade adjustment range and direction of movement into action commands for the baffle actuator; after the action command is sent, collecting the feedback signal of the actuator in real time; if the deviation between the feedback opening and the target opening exceeds a threshold, sending a fine-tuning command for correction; if a fault signal occurs, immediately stopping the adjustment action and sending an alarm signal.

7. The method for zoned adjustment of flue dampers in a secondary reheat unit according to claim 3, characterized in that, S2 includes: establishing a CFD simulation model of the three tail flues; using the real-time results of the flue gas parameter distribution as the inlet boundary conditions; calculating the radiative heat transfer between the flue gas and the pipe wall, and between the pipe wall and the working fluid; using the in-pipe flow heat transfer model to calculate the temperature change and heat absorption of the working fluid in the heat transfer surface; obtaining the actual heat transfer of the working fluid in the heat transfer surface based on the coupled heat exchange between the flue gas side and the working fluid side; comparing the reheat temperature with the target value, and if there is a deviation, changing the heat transfer of each flue by changing the flue gas flow distribution.

8. A method for zoned adjustment of flue dampers in a secondary reheat unit according to claim 3, 4, or 7, characterized in that, In S1, when performing CFD simulation calculations, a geometric model consistent with the actual boiler structure is constructed. The constructed geometric model is simplified, and the simplified geometric model is meshed. The mesh of the furnace and burner areas is refined, and the mesh of the tail flue area is enlarged.

9. A method for zoned adjustment of flue dampers in a secondary reheat unit according to claim 3, 4, or 7, characterized in that, After solving for the optimal opening degree using the multi-objective optimization algorithm, the optimal opening degree is used as the boundary condition of the baffle and input into the CFD model. The flow field and temperature field of the three tail flues are recalculated to verify whether the heat distribution of flue gas under the optimized opening degree meets the objective conditions. If the verification result does not meet the requirements, the objective function weights or optimization conditions are adjusted, and multi-objective optimization is performed again until the verification result meets the requirements.

10. A method for zoned adjustment of flue dampers in a secondary reheat unit according to claim 9, characterized in that, Whether the flue gas heat distribution under the optimized opening meets the target conditions includes: whether the heat exchange of each heat exchange surface reaches the target value, whether the deviation between the calculated value of the primary / secondary reheat steam temperature and the target value is within the allowable range, whether there is any abnormality in the flue gas flow rate, and whether the resistance loss after the damper adjustment meets the constraint requirements.

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