Multi-dimensional coupling coal-fired boiler flow field reconstruction method and system thereof

Abstract

This application relates to the field of coal-fired power unit technology, and in particular to a multi-dimensional coupled flow field reconstruction method and system for coal-fired boilers, including: high-fidelity, high-quality data acquisition; simulation experiments, constructing a full-process flow field distribution model of the coal-fired boiler system under laboratory conditions through computational fluid dynamics numerical simulation technology and laboratory simulated flue gas detection tests; evaluation experiments, obtaining the flow field distribution of the coal-fired boiler system under actual operating conditions through cold-state flow field diagnostic experiments and full-condition multi-coal-quality hot-state flow field evaluation experiments; and data fusion and reconstruction, comparing and analyzing simulation test data and evaluation test data and combining them with online historical data, achieving multi-dimensional reconstruction and rapid inference of the full-process flow field of the coal-fired boiler under all operating conditions through data fusion and model training. This solves the problem that existing coal-fired boiler flow field designs deviate from the actual operating conditions of the unit, failing to achieve a true representation and accurate optimization of the flow field, resulting in poor flow field optimization effects.

Description

Technical Field

[0001] This application relates to the field of coal-fired power unit technology, and in particular to a multi-dimensional coupled flow field reconstruction method and system for coal-fired boilers. Background Technology

[0002] Under the dual-carbon context, the functional positioning and operation mode of coal-fired power units in the industry have undergone profound changes. With the situation of deep peak shaving and changes in coal quality, the flow field characteristics in the boiler furnace have changed significantly. The uniformity and stability of the gas-solid two-phase flow in the furnace have decreased, and phenomena such as uneven flow field distribution, intensified airflow scouring, and changes in nitrogen oxide generation characteristics are prone to occur, which seriously restrict the stable and safe operation of the unit and the efficient and economical control of pollutants.

[0003] How to achieve rapid reasoning and accurate optimization of the flow field state of a coal-fired boiler under all operating conditions and throughout the entire process is a technical problem that urgently needs to be solved.

[0004] Currently, there are two main approaches in academia to solve this type of problem. The most widely used approach is computational fluid dynamics (CFD). This method builds a simulation model by solving the Navier-Stokes equations. However, the models developed by this method are relatively simple and the research is mainly based on mechanistic theory, which cannot fit the actual engineering situation and is prone to distortion, leading to deviations from the actual operation of the unit.

[0005] Another approach is based on machine learning methods such as artificial intelligence. However, purely data-driven fluid dynamics methods also have obvious limitations: due to the scarcity of high-quality data, the learned black-box models often lack clear physical meaning and mechanistic interpretability. Summary of the Invention

[0006] The purpose of this application is to provide a multi-dimensional coupled flow field reconstruction method and system for coal-fired boilers, in order to solve the problem that the existing flow field design of coal-fired boilers deviates from the actual operation of the unit under the current situation of complex and variable coal quality for deep peak shaving, and thus cannot achieve true characterization and accurate optimization of the flow field, resulting in poor flow field optimization and transformation effect.

[0007] Firstly, this application provides a multidimensional coupled flow field reconstruction method for coal-fired boilers, comprising: S10, high-fidelity, high-quality data acquisition, including cold-state measured data acquisition, hot-state measured data acquisition, and online historical data acquisition; S20. Simulation test: Through computational fluid dynamics numerical simulation technology and laboratory simulated flue gas detection test, a full-process flow field distribution model of the coal-fired boiler system under laboratory conditions is constructed. S30. Evaluation test: The flow field distribution of the coal-fired boiler system under actual operating conditions is obtained through cold flow field diagnosis test and full-condition multi-coal quality hot flow field evaluation test. S40. Data fusion and reconstruction: The simulation test data obtained in step S20 is compared and analyzed with the evaluation test data obtained in step S30. Combined with online historical data, through data fusion and model training, the multi-dimensional reconstruction and rapid reasoning of the flow field of the coal-fired boiler under all operating conditions and throughout the entire process are realized.

[0008] Furthermore, in step S10, the cold-state measured data acquisition is performed based on the principles of geometric similarity, cold-state self-modeling, and boundary similarity.

[0009] Furthermore, in step S10, the cold-state measured data acquisition includes on-site testing of the coal-fired boiler under cold-state conditions using experimental instruments when the coal-fired unit is shut down, including: S111. Inspection of burner installation and burner tilt angle, including: The structural condition and installation angle of the burner, primary air nozzle, and secondary air nozzle are inspected and measured, and the area of ​​the burner, primary air nozzle, and secondary air nozzle is measured. The burner tilt angle is measured using an angle gauge to measure the tilt angle of each nozzle. Under the same tilt angle, the deviation between the actual tilt angles of each nozzle is controlled within ±1.5°. S112, Large air box, secondary air damper opening verification and DCS command consistency verification; S113. Burner nozzle velocity measurement, including velocity measurement of primary air nozzle, secondary air nozzle and SOFA air nozzle; S114. Wall-mounted wind speed measurement: Primary and secondary air are introduced according to the principle of equal momentum ratio. The tangential and axial velocities at different elevations in the furnace wall at a distance of 0.1 to 0.2 m from the wall are measured, and a measurement point is selected every 0.5 to 1 m. S115. In-furnace dynamic field tracing test: use ribbons or ribbon nets to observe airflow distribution.

[0010] Furthermore, in step S30, the cold flow field diagnostic test includes: S311. Conduct internal inspections while the coal-fired boiler system is shut down; S312. Under the air distribution conditions, the flue gas velocity is simultaneously tested at each test section of the furnace and flow section of the coal-fired boiler to determine whether the distribution trend of the cold flow field is consistent with the distribution trend of the flow field in the simulation experiment. If they are consistent, the simulation experiment results can be used for flow field analysis. If they are inconsistent, the simulation experiment model is adjusted.

[0011] Furthermore, in step S10, the hot-state measured data acquisition involves on-site testing using experimental instruments at different heights below the flame deflector along the boiler furnace outlet under different loads and coal qualities during the startup and operation of the coal-fired unit. This includes: S121. Along the furnace outlet below the flame deflector, at heights of 0.2~0.5m, conduct NO testing on the entire cross-section at the same height. x The concentration field, velocity field, temperature field, and pressure field of SO2, CO, and O2 in the flue gas were measured. These measurements were conducted at the inlet flue of the SCR denitrification unit, the inlet flue of the air preheater, and the outlet flue of the air preheater. The test grid arrangement method was used for the test, and the actual thermal data of each single point, single-layer section, and multi-layer section were generated. S122. Sampling and analysis, including sampling raw coal at the pulverizer inlet, pulverized coal between the pulverizer outlet and the furnace pulverized coal inlet, slag at the furnace bottom bin, and fly ash at the air preheater outlet, and performing sampling and analysis.

[0012] Furthermore, in step S30, the full-condition multi-coal thermal flow field evaluation test includes: S321. With the coal-fired boiler system in the start-up state, test the NO at each test section. x Concentrations of SO2, CO, and O2; flue gas velocity; temperature and pressure distribution; S322. Sampling and analysis are performed at different measuring points under various working conditions to determine whether the distribution trend of the hot flow field is consistent with the distribution trend of the cold flow field. S323. Compare and analyze the flow field distribution trend in the simulation experiment with the flow field distribution trend under hot working conditions. Determine whether the distribution trend of the hot flow field is consistent with the flow field distribution trend in the simulation experiment. If they are consistent, the simulation experiment results can be used for flow field analysis. If they are inconsistent, adjust the simulation experiment model.

[0013] Furthermore, in step S10, the online historical data acquisition includes: selecting boiler load, furnace negative pressure, reheat steam pressure, reheat steam temperature, feedwater flow rate, feedwater temperature, total fuel quantity, primary air volume of coal mill, hot air temperature of coal mill, pulverized coal temperature in coal mill, CCOFA air volume, SOFA, primary air cooling air flow rate, secondary air temperature, oxygen concentration of flue gas, coal feed rate of coal feeder, and oscillation angle of burner main nozzle.

[0014] Furthermore, in step S20, during the simulation calculation of the computational fluid dynamics numerical simulation technology, the flue gas is regarded as an incompressible fluid with steady flow. The various components in the flue gas are represented by component transport equations, and the governing equations consist of mass conservation equations, momentum conservation equations, and energy conservation equations. The influence of device leakage is ignored, and the components in the flue gas diffuse without chemical reaction.

[0015] Secondly, this application provides a multidimensional coupled coal-fired boiler flow field reconstruction system, which applies the multidimensional coupled coal-fired boiler flow field reconstruction method described in any one of the preceding statements. The system includes: The data acquisition module is used for cold-state measured data acquisition, hot-state measured data acquisition, and online historical data acquisition; The numerical simulation module is used to construct a full-process flow field distribution model of a coal-fired boiler under laboratory conditions. The test evaluation module is used to conduct cold-state diagnostic tests and full-condition multi-coal-quality hot-state evaluation tests to obtain the actual flow field distribution. The data fusion and reconstruction module is used to fuse simulation test data, evaluation test data and online historical data for model training, so as to realize multi-dimensional reconstruction and rapid inference of the flow field of coal-fired boiler under all operating conditions and in the whole process.

[0016] Furthermore, the coal-fired boiler includes a furnace and a circulation section connected in series, and a coal mill is provided outside the furnace. The circulation section includes a flame deflector flue, an SCR denitrification device and an air preheater arranged sequentially at intervals. A first test section is set at the outlet of the flame deflector flue, a second test section is set at the inlet flue of the SCR denitrification unit, a third test section is set at the inlet of the air preheater, and a fourth test section is set at the outlet of the air preheater.

[0017] Compared with existing technologies, the multidimensional coupled flow field reconstruction method and system for coal-fired boilers provided in this application acquires sufficient high-fidelity, high-quality measured fluid dynamics data under cold, hot, and prior historical data conditions, obtaining ample effective data support. This effective data is used for training and verification feedback. The full-process flow field distribution model under laboratory conditions, constructed through computational fluid dynamics numerical simulation theory and laboratory simulated flue gas detection tests, is combined with the flow field distribution under actual operating conditions obtained through cold-state flow field diagnostic tests and full-condition coal-fired boiler system hot-state flow field evaluation tests. These are mutually validated and coupled, ensuring the correctness and accuracy of the detection, thus realizing multidimensional coupled flow field reconstruction of coal-fired boilers. This effectively guides the formulation of subsequent optimization design schemes. Furthermore, this method has the advantages of being systematic, accurate, and highly operable, ensuring the stable, reliable, and economical operation of coal-fired boiler systems, and possessing good environmental, safety, and economic benefits, with broad application prospects. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating the multidimensional coupled flow field reconstruction method for a coal-fired boiler provided in an embodiment of this application; Figure 2 This is a schematic diagram of the layout of a coal-fired boiler system provided in an embodiment of this application; Figure 3 This is a schematic diagram of the laboratory simulated flue gas detection and testing device provided in the embodiments of this application.

[0020] Figure label: 10-Furnace; 11-Furnace bottom chamber; 12-Flame deflector flue; 13-Flame deflector; 20-SCR denitrification device; 30-Air preheater; 40-Coal mill; 50-Coal feeder; 61-Raw coal sampling point; 62-Pulverized coal sampling point; 63-Slag sampling point; 64-Fly ash sampling point; 71-First test section; 72-Second test section; 73-Third test section; 74-Fourth test section; 81-Flue gas simulation system; 82-Catalytic reaction system; 83-Tail gas treatment system. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0026] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0027] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] like Figures 1 to 3 As shown, this application provides a multidimensional coupled coal-fired boiler flow field reconstruction method and a multidimensional coupled coal-fired boiler flow field reconstruction system using the multidimensional coupled coal-fired boiler flow field reconstruction method. The coal-fired boiler includes a furnace 10 and a flow section connected in series. A coal mill 40 is provided outside the furnace 10. The flow section is provided with a flame deflector flue 12, an SCR denitrification device 20 and an air preheater 30 in sequence at intervals.

[0029] like Figure 1 As shown, the multidimensional coupled flow field reconstruction method for coal-fired boilers provided in this embodiment includes the following steps: S10, high-fidelity, high-quality data acquisition, including cold-state measured data acquisition, hot-state measured data acquisition, and online historical data acquisition; S20. Simulation test: Through computational fluid dynamics numerical simulation technology and laboratory simulated flue gas detection test, a full-process flow field distribution model of the coal-fired boiler system under laboratory conditions is constructed. S30. Evaluation test: The flow field distribution of the coal-fired boiler system under actual operating conditions is obtained through cold flow field diagnosis test and full-condition multi-coal quality hot flow field evaluation test. S40. Data fusion and reconstruction: The simulation test data obtained in step S20 is compared and analyzed with the evaluation test data obtained in step S30. Combined with online historical data, through data fusion and model training, the multi-dimensional reconstruction and rapid reasoning of the flow field of the coal-fired boiler under all operating conditions and throughout the entire process are realized.

[0030] This multidimensional coupled coal-fired boiler flow field reconstruction system includes: a data acquisition module for acquiring cold-state measured data, hot-state measured data, and online historical data; a numerical simulation module for constructing a full-process flow field distribution model of a coal-fired boiler under laboratory conditions; an experimental evaluation module for conducting cold-state diagnostic tests and full-condition multi-coal quality hot-state evaluation tests to obtain the actual flow field distribution; and a data fusion and reconstruction module for fusing simulation test data, evaluation test data, and online historical data and training the model to achieve multidimensional reconstruction and rapid inference of the full-process flow field of a coal-fired boiler under all operating conditions.

[0031] Compared with existing technologies, the multi-dimensional coupled flow field reconstruction method and system for coal-fired boilers provided in this application acquires sufficient high-fidelity, high-quality measured fluid dynamics data under cold, hot, and prior historical data conditions. This provides ample effective data support, which is then used for training and verification feedback. The system combines a full-process flow field distribution model under laboratory conditions, constructed through computational fluid dynamics numerical simulation theory and laboratory simulated flue gas testing, with the flow field distribution under actual operating conditions obtained through cold-state flow field diagnostic tests and full-condition coal-fired boiler system hot-state flow field evaluation tests. These are mutually validated and coupled, ensuring the correctness and accuracy of the detection, thus achieving multi-dimensional coupled flow field reconstruction for coal-fired boilers. This effectively guides subsequent optimization design schemes. Furthermore, this method has the advantages of being systematic, accurate, and highly operable, ensuring stable, reliable, and economical operation of coal-fired boiler systems, and offering good environmental, safety, and economic benefits, with broad application prospects.

[0032] Furthermore, in step S10, the cold-state measured data acquisition is carried out based on the principles of geometric similarity, cold-state self-modeling, and boundary similarity.

[0033] Among them, the principle of geometric similarity: since the cold test and the hot operation are carried out on the same furnace, the principle of geometric similarity is satisfied.

[0034] Cold-state self-simulation principle: Based on the similarity of airflow motion states, i.e., the Euler criterion equality principle: when the Reynolds number (Re) exceeds a certain value, the Euler number remains constant, and the flow state will exhibit characteristics that no longer change with the increase of the Re number. When the airflow velocity and Re increase further, only the absolute value of the velocity at each point in space increases proportionally, while the distribution pattern of the Euler number and velocity no longer changes. Therefore, as long as the Re number used under cold-state test conditions exceeds the critical Re number for entering the self-simulation zone or is equal to the Re number in the hot state, the similarity between the cold state and the hot state can be achieved, satisfying the cold-state self-simulation principle. Furthermore, when the Re number reaches or exceeds 1×10⁵, the flow field of furnace 10 and burner outlet can meet the conditions for entering the self-simulation zone.

[0035] Boundary condition similarity principle: The main consideration is to satisfy the similarity of the burner outlet jet. First, it is necessary to ensure that the air volume distribution method of the burner is similar to that in the hot state. Second, it is required that the Re number of each jet in the cold state is equal to that in the hot state or has entered the self-modeling region. It is also necessary to maintain that the inertial force of each jet in the cold test and the hot operation is equal, that is, the momentum ratio is equal.

[0036] Furthermore, when the coal-fired unit is shut down, on-site testing of the coal-fired boiler under cold conditions is conducted using experimental instruments to ensure high-fidelity and high-quality test data. The test content and procedures include: S111. Inspection of burner installation and burner tilt angle, including: The structural condition and installation angle of the burner, primary air nozzle, and secondary air nozzle are inspected and measured. The area of ​​the burner, primary air nozzle, and secondary air nozzle is measured, and it is ensured that there is no serious deformation of each nozzle, otherwise the movement state of the outlet airflow will be disturbed.

[0037] The burner tilt angle is measured using an angle gauge to measure the tilt angle of each nozzle. Under the same tilt angle, the deviation between the actual tilt angles of each nozzle is controlled within ±1.5°. Nozzles that exceed this deviation range should be adjusted. S112, Large air box, secondary damper opening verification and DCS command consistency verification, including: Perform operational tests on the large air box, secondary air damper, etc., to confirm that the scale on the baffle shaft end is consistent with the actual opening of the baffle, that the scale on the shaft end is consistent with the local indication, that the local indication is consistent with the DCS command, and check the feedback signal at the same time.

[0038] The damper opening can be measured locally using an angle gauge. The measurement results and the feedback value displayed by the DCS are then checked. Through inspection, verification, and adjustment, the opening of the small damper displayed by the DCS is kept consistent with the actual opening. The deviation between the damper openings of the burners on the same floor should be controlled within ±5%.

[0039] S113. Burner nozzle velocity measurement, including velocity measurement of primary air nozzle, secondary air nozzle and SOFA air nozzle; Preferably, when measuring the wind speed at the boiler perimeter, in order to ensure the accuracy of the measurement data, an anemometer can be used to measure four to five sets of wind speeds at different positions around the perimeter air nozzle, and the average value can be taken as the final data, as shown in Table 1.

[0040] The wind speed at the primary air nozzle, secondary air nozzle, and SOFA air nozzle can also be measured using an anemometer at the primary air nozzle and secondary air nozzle. Take 4 to 5 representative points at the burner nozzle to measure the wind speed, and take the average value as the final result, as shown in Table 1.

[0041] S114. Wall-mounted wind speed measurement: When measuring the wall-mounted wind speed inside the furnace, primary and secondary air are introduced according to the principle of equal momentum ratio. The airflow motion state is as close to the hot state as possible. The tangential and axial velocities at different elevations of the furnace 10 at a distance of 0.1~0.2m from the wall are measured. A measurement point is selected every 0.5~1m, as shown in Table 1.

[0042] S115. For the in-furnace dynamic field tracing test, ribbons or ribbon nets are used to observe the airflow distribution. Specifically, during ribbon tracing, long ribbons can be used to indicate the direction of airflow, while short ribbons can be used to determine the extent of the light wind zone, recirculation zone, and vortex zone. A ribbon net can be used to observe the overall airflow conditions at a specific cross-section. Before the test, positioning coordinate lines should be drawn at different heights in the furnace, generally with a central crosshair drawn at the height of each burner layer to facilitate recording the ribbon trajectory.

[0043] Furthermore, in step S10, hot-state measured data is collected during the startup and operation of the coal-fired unit. This data is collected at different heights below the flame deflector angle 13 at the outlet of the furnace 10 of the combustion boiler under different loads and coal qualities (e.g.,...). Figure 2 The locations H1, H2, H3, and H4 in the test were tested on-site using experimental instruments. The different loads included at least the minimum load for deep peak shaving, minimum stable combustion load, conventional low load, conventional medium load, conventional high load, rated evaporation load, and maximum continuous evaporation load. The different coal qualities included at least the designed coal type, the actual coal type, and typical blended coal types. The test content and procedures included: S121a, NOx, SO2, CO, O2 concentration field measurement: Along the furnace 10 outlet below the flame deflector angle 13, at heights of 0.2~0.5m, the concentration field of NOx, SO2, CO, and O2 in the flue gas is measured across the entire cross-section at the same height. Flue gas concentration field measurements are also conducted at the inlet flue of the SCR denitrification unit 20, the inlet flue of the air preheater 30 (or the outlet flue of the SCR denitrification unit 20), and the outlet flue of the air preheater 30. A test grid layout method is used for testing. The flue gas concentration is measured at each measuring point, and the arithmetic mean of the flue gas concentrations at each grid point is calculated. The result is the actual flue gas concentration value under the current conditions for that cross-section, thus obtaining the actual thermal data for each single point, single-layer cross-section, and multi-layer cross-section. It is preferable to use a calibration measuring instrument with high-purity qualified standard gas. The measuring instrument is calibrated with standard gas during the measurement period, at least once before and after the test.

[0044] S121b, Flue Gas Velocity Field Measurement: Along the furnace 10 outlet below the flame deflector angle 13, flue gas velocity field measurements were conducted at the same height for the entire cross-section at intervals of 0.2~0.5m. Flue gas velocity field measurements were also conducted at the inlet flue of the SCR denitrification unit 20, the inlet flue of the air preheater 30 (or the outlet flue of the SCR denitrification unit 20), and the outlet flue of the air preheater 30. High-temperature resistant Pitot tubes were used, and a test grid arrangement method was employed for testing. Flue gas velocity was measured at each measuring point, and the arithmetic mean of the flue gas velocity at each grid point was calculated. The result is the actual flue gas velocity value under the current conditions for that cross-section, thus obtaining the actual thermal data for each single point, single-layer cross-section, and multi-layer cross-section.

[0045] S121c, Flue Gas Temperature Field Measurement: Along the furnace 10 outlet below the flame deflector angle 13, flue gas temperature field measurements were conducted at the same height for the entire cross-section at intervals of 0.2~0.5m. Flue gas temperature field measurements were also conducted at the inlet flue of the SCR denitrification unit 20, the inlet flue of the air preheater 30 (or the outlet flue of the SCR denitrification unit 20), and the outlet flue of the air preheater 30. Fast-response temperature probe thermocouples were used, and a test grid arrangement method was employed for testing. Flue gas temperature was measured at each measuring point, and the arithmetic mean of the flue gas temperatures at each grid point was calculated. The result represents the actual flue gas temperature value at that cross-section, thus obtaining the actual thermal data for each single point, single-layer cross-section, and multi-layer cross-section.

[0046] S121d, flue gas pressure field measurement: Along the furnace 10 outlet below the flame deflector angle 13, flue gas pressure field measurements were conducted at the same height for the entire cross-section at intervals of 0.2~0.5m. Flue gas pressure field measurements were also conducted at the inlet flue of the SCR denitrification unit 20, the inlet flue of the air preheater 30 (or the outlet flue of the SCR denitrification unit 20), and the outlet flue of the air preheater 30. High-temperature resistant micro-manometers were used, and a test grid arrangement method was employed for testing. Flue gas pressure was measured at each measuring point, and the arithmetic mean of the flue gas pressures at each grid point was calculated. The result is the actual flue gas pressure value under the current conditions for that cross-section, thus obtaining the actual thermal data for each single point, single-layer cross-section, and multi-layer cross-section.

[0047] S122, Sampling analysis, such as Figure 2 As shown, it includes: Raw coal samples were taken at the raw coal sampling point 61 at the inlet of the coal mill 40. The specific sampling location was on the coal drop pipe of each coal feeder 50. During the test, all operating coal mills 40 were sampled in turn, with a sampling interval of 30 minutes between each round. The samples were promptly placed in sealed containers and required to undergo elemental analysis, industrial analysis, and calorific value testing. Coal powder sampling was carried out at sampling point 62 between the coal mill outlet 40 and the furnace inlet 10. The coal powder sampling adopted the flat-head isokinetic sampling method and the sampling time was 5 minutes. The coal powder screening process was carried out in accordance with DL / T 567.5, using two types of sieves: 90μm and 200μm. Slag samples are taken at slag sampling point 63 in the bottom chamber 11 of the furnace, with each sampling interval being 30 minutes. Slag combustible analysis is required, and the results are used as the basis for calculating boiler thermal efficiency. Fly ash samples were taken at sampling point 64 at the outlet of air preheater 30. Samples were taken according to the specific number of times under the test conditions. Combustible matter analysis of the fly ash was required, and the results were used as the basis for calculating the boiler thermal efficiency.

[0048] Furthermore, in step S10, as shown in Table 1 below, the online historical data collection includes: boiler load, furnace negative pressure, reheat steam pressure, reheat steam temperature, feedwater flow rate, feedwater temperature, total fuel quantity, primary air volume of coal mill, hot air temperature of coal mill, pulverized coal temperature in coal mill, CCOFA air volume, SOFA, primary air cooling air flow rate, secondary air temperature, oxygen concentration of flue gas, coal feed rate of coal feeder, and oscillation angle of burner main nozzle.

[0049] This may include parameter measurements of multiple sets of coal mills and multiple sets of coal feeders, such as coal mill A, coal mill B and coal mill C, coal feeder A and coal feeder B. Multiple measurements can also be performed to obtain multiple parameters to ensure accuracy.

[0050] Online historical data should cover a period of at least 6 months (excluding downtime). Based on the actual situation of the unit, data points should be selected at intervals of 30 seconds to 5 minutes. Parameter selection examples are shown in Table 1 below. Table 1. Correspondence Table of Combustion Boiler Parameters

[0051] Furthermore, in step S20, during the simulation calculation of computational fluid dynamics numerical simulation technology, the flue gas is regarded as an incompressible fluid with steady flow. The various components in the flue gas are represented by component transport equations, and the governing equations consist of mass conservation equations, momentum conservation equations, and energy conservation equations. The influence of air leakage in the device is ignored, and the components in the flue gas diffuse without chemical reaction.

[0052] like Figure 3 As shown, the laboratory simulated flue gas detection device is used to detect the flow field characteristics of the SCR denitrification device 20, including a flue gas simulation system 81, a catalytic reaction system 82, a flue gas analysis system, a tail gas treatment system 83, and an electrical control system.

[0053] Furthermore, in step S30, the cold flow field diagnostic test includes: S311. Conduct internal inspections while the coal-fired boiler system is shut down. This may include checking the burner installation and burner tilt angle, verifying the opening of the large air box and secondary dampers, and verifying the consistency of DCS commands. Further details will not be provided.

[0054] S312. Under the air distribution conditions, the flue gas velocity is simultaneously tested at each test section (including the first test section 71, the second test section 72, the third test section 73 and the fourth test section 74) of the furnace 10 and the flow section of the coal-fired boiler. It is determined whether the distribution trend of the cold flow field is consistent with the distribution trend of the flow field in the simulation experiment. If they are consistent, the simulation experiment results can be used for flow field analysis. If they are inconsistent, the simulation experiment model is adjusted.

[0055] Among them, such as Figure 2 As shown, the first test section 71 can be set at the outlet position of the flame deflector flue 12, the second test section 72 can be set at the inlet flue position of the SCR denitrification device 20, the third test section 73 can be set at the inlet position of the air preheater 30, and the fourth test section 74 can be set at the outlet position of the air preheater 30.

[0056] In step S30, the full-condition multi-coal thermal flow field evaluation test includes the following steps: S321. With the coal-fired boiler system in the start-up state, test the NO at each test section (including the first test section 71, the second test section 72, the third test section 73, and the fourth test section 74). x The concentrations of SO2, CO, and O2, flue gas velocity, temperature, and pressure distribution are preferably measured by a flue gas analyzer, flue gas velocity by a Pitot tube, temperature by a thermocouple, and pressure by a micromanometer.

[0057] S322. Sampling and analysis are performed at different measuring points under various working conditions to determine whether the distribution trend of the hot flow field is consistent with the distribution trend of the cold flow field.

[0058] S323. Compare and analyze the data from the simulation experiment with the data from the evaluation experiment. First, compare and analyze the flow field distribution trend of the simulation experiment with the flow field distribution trend under hot conditions. Determine whether the distribution trend of the hot flow field is consistent with the flow field distribution trend of the simulation experiment. If they are consistent, the simulation experiment results can be used for flow field analysis. If they are inconsistent, adjust the simulation experiment model.

[0059] Based on simulation experiments and cold-state conditions, the flow field distribution under hot-state conditions is further verified. On the one hand, this can further verify the correctness and accuracy of the numerical simulation results. On the other hand, it can also provide feedback optimization for the numerical simulation calculations, realizing the real reconstruction of the multi-dimensional coupled flow field of the coal-fired boiler. This can effectively guide the formulation of subsequent optimization design schemes and optimize the flow field modification effect.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for reconstructing the flow field of a coal-fired boiler with multi-dimensional coupling, characterized in that, include: S10, high-fidelity, high-quality data acquisition, including cold-state measured data acquisition, hot-state measured data acquisition, and online historical data acquisition; S20. Simulation test: Through computational fluid dynamics numerical simulation technology and laboratory simulated flue gas detection test, a full-process flow field distribution model of the coal-fired boiler system under laboratory conditions is constructed. S30. Evaluation test: The flow field distribution of the coal-fired boiler system under actual operating conditions is obtained through cold flow field diagnosis test and full-condition multi-coal quality hot flow field evaluation test. S40. Data fusion and reconstruction: The simulation test data obtained in step S20 is compared and analyzed with the evaluation test data obtained in step S30. Combined with online historical data, through data fusion and model training, the multi-dimensional reconstruction and rapid reasoning of the flow field of the coal-fired boiler under all operating conditions and throughout the entire process are realized.

2. The method of multi-dimensional coupled reconstruction of flow field in a coal-fired boiler of claim 1, wherein, In step S10, the cold-state measured data acquisition is carried out based on the principles of geometric similarity, cold-state self-modeling, and boundary similarity.

3. The method of multi-dimensional coupled reconstruction of flow field in a coal-fired boiler of claim 2, wherein, In step S10, the cold-state measured data acquisition includes on-site testing of the coal-fired boiler under cold-state conditions using experimental instruments when the coal-fired unit is shut down, including: S111. Inspection of burner installation and burner tilt angle, including: The structural condition and installation angle of the burner, primary air nozzle, and secondary air nozzle are inspected and measured, and the area of ​​the burner, primary air nozzle, and secondary air nozzle is measured. The burner tilt angle is measured using an angle gauge to measure the tilt angle of each nozzle. Under the same tilt angle, the deviation between the actual tilt angles of each nozzle is controlled within ±1.5°. S112, Large air box, secondary air damper opening verification and DCS command consistency verification; S113. Burner nozzle velocity measurement, including velocity measurement of primary air nozzle, secondary air nozzle and SOFA air nozzle; S114. Wall-mounted wind speed measurement: Primary and secondary air are introduced according to the principle of equal momentum ratio. The tangential and axial velocities at different elevations in the furnace wall at a distance of 0.1 to 0.2 m from the wall are measured, and a measurement point is selected every 0.5 to 1 m. S115. In-furnace dynamic field tracing test: use ribbons or ribbon nets to observe airflow distribution.

4. The method of multi-dimensional coupled reconstruction of flow field in a coal-fired boiler of claim 3, wherein, In step S30, the cold flow field diagnostic test includes: S311. Conduct internal inspections while the coal-fired boiler system is shut down; S312. Under the air distribution conditions, the flue gas velocity is simultaneously tested at each test section of the furnace and flow section of the coal-fired boiler to determine whether the distribution trend of the cold flow field is consistent with the distribution trend of the flow field in the simulation experiment. If they are consistent, the simulation experiment results can be used for flow field analysis. If they are inconsistent, the simulation experiment model is adjusted.

5. The method for reconstructing the flow field of a multidimensional coupled coal-fired boiler according to claim 1, characterized in that, In step S10, the hot-state measured data acquisition involves on-site testing using experimental instruments at different heights below the flame deflector along the boiler furnace outlet under different loads and coal qualities during the startup and operation of the coal-fired unit. This includes: S121, at the furnace outlet under the angle, every 0.2-0.5m height, the same height full section to carry out NO x , SO2, CO, O2, flue gas composition concentration field measurement, flue gas velocity field measurement, flue gas temperature field measurement and flue gas pressure field measurement, and flue gas composition concentration field measurement, flue gas velocity field measurement, flue gas temperature field measurement and flue gas pressure field measurement are carried out at the SCR denitration device inlet flue, the air preheater inlet flue and the air preheater outlet flue position, and the test grid arrangement method is used for testing, and the thermal actual data of each single point, single layer section, multi-layer section is formed; S122. Sampling and analysis, including sampling raw coal at the pulverizer inlet, pulverized coal between the pulverizer outlet and the furnace pulverized coal inlet, slag at the furnace bottom bin, and fly ash at the air preheater outlet, and performing sampling and analysis.

6. The method for reconstructing the flow field of a multidimensional coupled coal-fired boiler according to claim 5, characterized in that, In step S30, the full-condition multi-coal thermal flow field evaluation test includes: S321、in the coal-fired boiler system start-up state, test the concentration of NO x , SO2, CO, O2, flue gas flow rate, temperature and pressure distribution of each test section; S322. Sampling and analysis are performed at different measuring points under various working conditions to determine whether the distribution trend of the hot flow field is consistent with the distribution trend of the cold flow field. S323. Compare and analyze the flow field distribution trend in the simulation experiment with the flow field distribution trend under hot working conditions. Determine whether the distribution trend of the hot flow field is consistent with the flow field distribution trend in the simulation experiment. If they are consistent, the simulation experiment results can be used for flow field analysis. If they are inconsistent, adjust the simulation experiment model.

7. The method for reconstructing the flow field of a multidimensional coupled coal-fired boiler according to claim 1, characterized in that, In step S10, the online historical data acquisition includes: selecting boiler load, furnace negative pressure, reheat steam pressure, reheat steam temperature, feedwater flow rate, feedwater temperature, total fuel quantity, primary air volume of coal mill, hot air temperature of coal mill, pulverized coal temperature in coal mill, CCOFA air volume, SOFA, primary air cooling air flow rate, secondary air temperature, oxygen concentration of flue gas, coal feed rate of coal feeder, and oscillation angle of burner main nozzle.

8. The method for reconstructing the flow field of a multidimensional coupled coal-fired boiler according to claim 1, characterized in that, In step S20, during the simulation calculation of the computational fluid dynamics numerical simulation technology, the flue gas is regarded as an incompressible fluid with steady flow. The various components in the flue gas are represented by component transport equations. The governing equations consist of mass conservation equations, momentum conservation equations, and energy conservation equations. The influence of air leakage in the device is ignored. The components in the flue gas diffuse and do not undergo chemical reactions.

9. A multidimensional coupled flow field reconfiguration system for a coal-fired boiler, characterized in that, The system employing the multidimensional coupling flow field reconstruction method for coal-fired boilers according to any one of claims 1 to 8 comprises: The data acquisition module is used for cold-state measured data acquisition, hot-state measured data acquisition, and online historical data acquisition; The numerical simulation module is used to construct a full-process flow field distribution model of a coal-fired boiler under laboratory conditions. The test evaluation module is used to conduct cold-state diagnostic tests and full-condition multi-coal-quality hot-state evaluation tests to obtain the actual flow field distribution. The data fusion and reconstruction module is used to fuse simulation test data, evaluation test data and online historical data for model training, so as to realize multi-dimensional reconstruction and rapid inference of the flow field of coal-fired boiler under all operating conditions and in the whole process.

10. The multidimensional coupled flow field reconstruction system for a coal-fired boiler according to claim 9, characterized in that, The coal-fired boiler includes a furnace and a circulation section connected in series, and a coal mill is provided outside the furnace. The circulation section includes a flame deflector flue, an SCR denitrification device and an air preheater arranged sequentially at intervals. A first test section is set at the outlet of the flame deflector flue, a second test section is set at the inlet flue of the SCR denitrification unit, a third test section is set at the inlet of the air preheater, and a fourth test section is set at the outlet of the air preheater.

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