Coal dust reverse injection swirl burner flow field characteristic experiment device and method

Abstract

The application discloses a kind of experimental device and method of flow field characteristics of coal powder reverse spray cyclone burner, the experimental device includes burner body, first measurement component and second measurement component, first measurement component includes constant temperature hot wire anemometer and three-dimensional hot film probe, three-dimensional hot film probe is located in flow field, to measure the three-dimensional average velocity distribution and three-dimensional fluctuation velocity distribution of flow field, second measurement component includes net coordinate frame and multiple streamers bundled on net coordinate frame, primary air pipe is through net coordinate frame, to make the backflow area shape and area of flow field of burner body by the airflow direction measurement of streamer tracer. The experimental method simulates the flow field change in actual combustion process of coal powder in burner by the flow field of wind in normal temperature state in burner, uses streamer method and constant temperature hot wire speed research to study the flow field characteristics under different conditions, explores reverse jet coupling cyclone flame stabilization mechanism, to better serve coal power unit depth flexible peak shaving reconstruction.

Description

Technical Field

[0001] This invention relates to the field of combustion performance testing technology, and in particular to an experimental apparatus and method for the flow field characteristics of a pulverized coal reverse-jet swirl burner. Background Technology

[0002] With the increasing proportion of new energy sources such as wind and solar power in the energy structure, the flexible peak-shaving capability of coal-fired power units faces greater challenges. Furthermore, the proportion of difficult-to-burn coals blended in coal-fired power units is constantly increasing. Therefore, stable combustion on the boiler combustion side under low load is crucial. The reverse-jet swirl burner is a high-efficiency, low-NOx pulverized coal burner that integrates reverse-jet combustion technology and swirl combustion technology. It has advantages such as low ignition heat, rapid ignition, and short start-up and shutdown times. It has already been applied in the flexible peak-shaving upgrade and renovation of a 300MW four-corner tangential pulverized coal boiler in a power plant. In summary, by studying the flow field characteristics within the reverse-jet swirl burner when burning low-volatile, low-quality bituminous coal, and exploring its reverse-jet coupled swirl stable combustion mechanism, it is of great significance for achieving safe and stable operation of coal-fired power units under low load. Summary of the Invention

[0003] The present invention aims to at least partially solve one of the technical problems in the related art.

[0004] To address this issue, embodiments of the present invention propose an experimental device for the flow field characteristics of a pulverized coal reverse-jet swirl burner, which solves the problem of stable combustion of the reverse-jet swirl burner when burning low-volatile, low-quality bituminous coal.

[0005] The experimental apparatus for the flow field characteristics of a pulverized coal reverse-injection swirl burner according to an embodiment of the present invention includes:

[0006] The burner body includes a primary air duct, an inner secondary air duct, and an outer secondary air duct that are spaced apart from the inside to the outside. The nozzles of the inner secondary air duct and the outer secondary air duct are flush. The nozzle of the primary air duct is located downstream of the nozzle of the inner secondary air duct. A backflow cap is provided at the nozzle of the primary air duct so that the airflow ejected in reverse through the primary air duct and the airflow ejected through the inner and outer secondary air ducts can establish the flow field of the burner body.

[0007] The first measurement component includes a constant-temperature hot-wire anemometer and a three-dimensional hot-film probe connected to the constant-temperature hot-wire anemometer. The three-dimensional hot-film probe is located within the flow field of the burner body, so that the constant-temperature hot-wire anemometer measures the three-dimensional average velocity distribution and the three-dimensional pulsating velocity distribution of the flow field of the burner body.

[0008] The second measurement component includes a mesh coordinate frame and multiple ribbons tied to the mesh coordinate frame. The primary air duct passes through the mesh coordinate frame to measure the shape and area of ​​the recirculation zone of the flow field of the burner body by means of the airflow direction traced by the ribbons.

[0009] The experimental device for the flow field characteristics of a pulverized coal reverse-jet swirl burner in this invention measures the three-dimensional average velocity distribution, three-dimensional pulsating velocity distribution, and recirculation zone boundary in the flow field of the reverse-jet swirl burner. It calculates the turbulence intensity and recirculation zone area in the flow field, and can conduct in-depth research on the influence characteristics of factors such as reverse primary air volume, combustion load, and burner structural parameters on the flow field characteristics of the reverse-jet swirl burner. It clarifies the coupling and stable combustion characteristics between the reverse primary air and the secondary air in the swirl, optimizes the structure and operating parameters of the reverse-jet swirl burner when burning low-volatile, inferior pulverized coal, and better serves the deep and flexible peak-shaving retrofit of coal-fired power units.

[0010] In some embodiments, the hot wire of the three-dimensional thermal film probe is used to connect to a circuit for heating, so as to establish a correspondence between the electrical signal and the flow field wind speed in the circuit, satisfying the following relationship:

[0011] E 2 =A+BU 0.5

[0012] Where E is the voltage across the hot wire, U is the velocity of the airflow perpendicular to the hot wire, and A and B are fixed constants related to the hot wire.

[0013] In some embodiments, the RMS velocity is calculated based on the average velocity and pulsating velocity measured by the constant-temperature hot-wire anemometer, satisfying the following relationship:

[0014]

[0015] Among them, U i Let U be the pulsating velocity of the measurement point, U be the average velocity of the measurement point, and n be the number of measurements taken at the measurement point.

[0016] In some embodiments, the system further includes an air supply assembly, which includes a blower and an air box connected in sequence. The air box is connected to various air ducts of the burner body via a pipeline, and a flow meter and a valve are provided on the pipeline between the air box and the burner body.

[0017] In some embodiments, the first measuring component further includes a calibrator connected to the constant temperature hot wire anemometer, the calibrator being used to calibrate the three-dimensional hot film probe.

[0018] In some embodiments, the first measuring component further includes a temperature probe connected to the constant temperature hot-wire anemometer, the temperature probe being located within the flow field of the burner body, and the temperature probe being used to measure the experimental ambient temperature.

[0019] The embodiments of the present invention also propose an experimental method for the flow field characteristics of a pulverized coal reverse-injection swirl burner, the experimental method being used in the pulverized coal reverse-injection swirl burner flow field characteristic experimental apparatus described in any of the above embodiments.

[0020] The experimental method for the flow field characteristics of a pulverized coal reverse-injection swirl burner according to embodiments of the present invention includes:

[0021] The flow field of air under normal temperature conditions inside the burner is used to simulate the flow field of pulverized coal during actual combustion in the burner.

[0022] The shape and area of ​​the recirculation zone in the burner flow field were measured using the ribbon method.

[0023] The three-dimensional average velocity distribution and three-dimensional pulsating velocity distribution in the burner flow field were measured using the constant temperature hot wire velocimetry method. The RMS velocity distribution was calculated based on the measurement results, and the RMS velocity was used to characterize the turbulence intensity of the flow field.

[0024] In some embodiments, during the experiment, the momentum of the pulverized coal carried by the primary air is included in the momentum of the primary air, and the momentum ratio of each nozzle of the burner is equal to the momentum ratio of each nozzle during the actual combustion process.

[0025] In some embodiments, during the measurement of the recirculation zone of the flow field, a mesh coordinate frame with ribbons attached is placed on different cross sections with X / D = 0.17, 0.3, 0.4, 0.6, 0.8, 1, 1.2, 1.6, 2, 2.3, and 2.6, where X represents the axial direction of the burner, D is the inner diameter of the external secondary air duct, the direction of the ribbon is the negative direction of X, the recirculation zone is the grid area in all negative directions, the boundary of the recirculation zone is the grid area, and the area of ​​the grid area is the area of ​​the recirculation zone.

[0026] In some embodiments, the probe used for measurement is calibrated before measuring the wind speed in the flow field, and the relationship between the output voltage and the fluid velocity is established under the same experimental measurement conditions and calibration conditions. Attached Figure Description

[0027] Figure 1 This is a first schematic diagram of the experimental apparatus according to an embodiment of the present invention.

[0028] Figure 2 This is a second schematic diagram of the experimental apparatus according to an embodiment of the present invention.

[0029] Figure label:

[0030] 1-Burn body, 101-Primary air duct, 102-Inner secondary air duct, 103-Outer secondary air duct, 104-Return cap,

[0031] 2-Constant temperature hot wire anemometer, 3-Three-dimensional hot film probe, 4-Mesh coordinate frame, 5-Ribbon, 6-Blowbox, 7-Flow meter, 8-Valve, 9-Converter, 10-Computer, 11-Temperature probe. Detailed Implementation

[0032] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0033] The experimental apparatus for the flow field characteristics of a pulverized coal reverse-jet swirl burner according to an embodiment of the present invention is described below with reference to the accompanying drawings.

[0034] like Figure 1 and Figure 2 As shown, the experimental device for the flow field characteristics of a pulverized coal reverse-jet swirl burner according to an embodiment of the present invention includes: a burner body 1, a first measuring component, and a second measuring component.

[0035] The burner body 1 includes a primary air duct 101, an inner secondary air duct 102, and an outer secondary air duct 103, which are spaced apart from the inside to the outside. The nozzles of the inner secondary air duct 102 and the outer secondary air duct 103 are flush. The nozzle of the primary air duct 101 is located downstream of the nozzle of the inner secondary air duct 102. A return cap 104 is provided at the nozzle of the primary air duct 101.

[0036] The flow field of the burner body 1 is established by the airflow ejected from the primary air duct 101 in reverse and the airflow ejected from the inner secondary air duct 102 and the outer secondary air duct 103. That is, the experimental device of this embodiment is suitable for measuring the flow field characteristics of a swirl burner with a reverse-jet primary air duct 101. The flow field changes of pulverized coal in the actual combustion process are simulated by the airflow field of the burner under normal temperature conditions.

[0037] The first measuring component includes a constant-temperature hot-wire anemometer 2 and a three-dimensional hot-film probe 3. The three-dimensional hot-film probe 3 is connected to the constant-temperature hot-wire anemometer 2 and is located in the flow field of the burner body 1.

[0038] Understandably, the core component of the constant-temperature hot-wire anemometer 2 is a heated wire (usually platinum or nickel wire), which (i.e., the three-dimensional hot-film probe 3) is placed in the airflow to be measured. When the airflow passes over the hot wire, it carries away the heat from the wire, causing its temperature to drop. By measuring the temperature change of the hot wire, the airflow velocity can be determined.

[0039] In the constant-temperature hot-wire anemometer 2, the circuit regulates the current passing through the hot wire to maintain a constant temperature. Therefore, when the airflow speed changes, the circuit automatically adjusts the current to keep the hot wire temperature constant. The change in current is inversely proportional to the airflow speed, thus allowing for accurate wind speed measurement.

[0040] Therefore, the experimental apparatus of this embodiment of the invention uses a constant-temperature hot-wire anemometer 2 to measure the three-dimensional average velocity distribution and three-dimensional pulsating velocity distribution of the flow field in the burner.

[0041] In addition, the first measurement component also includes a calibrator, a temperature probe 11, a probe holder, an A / D converter 9, and a data processing software workstation (computer 10).

[0042] The calibrator is connected to the constant-temperature hot-wire anemometer 2 and is used to calibrate the three-dimensional hot-film probe 3. The temperature probe 11 is connected to the constant-temperature hot-wire anemometer 2 and is located within the flow field of the burner body 1. The temperature probe 11 is used to measure the ambient temperature of the experiment.

[0043] The probe holder is used to fix and support the probe, ensuring its stability during the measurement process. The holder design must take into account the probe's installation position and angle to obtain optimal measurement results.

[0044] Converter 9 is used to convert the analog wind speed signal measured by the probe into a digital signal for subsequent data processing and analysis. The accuracy and speed of A / D converter 9 are crucial to the overall performance of the device.

[0045] Data processing software workstations are used to collect, store, analyze, and visualize measured data. Software workstations typically have functions such as calibration, data correction, and calculation of wind speed and turbulence parameters.

[0046] The second measuring component includes a mesh coordinate frame 4 and multiple ribbons 5 tied to the mesh coordinate frame 4. The primary air duct 101 passes through the mesh coordinate frame 4 so that the shape and area of ​​the recirculation zone of the flow field of the burner body 1 can be measured by the direction of the airflow traced by the ribbons 5.

[0047] In other words, the experimental apparatus of this invention uses the ribbon method, which displays the airflow direction through a coordinate frame with a red gauze ribbon 5 that is 2cm long. The distance between adjacent grids is 3cm. The boundary of the recirculation zone is drawn by tracking the airflow direction through the ribbon 5, and then the area of ​​the recirculation zone is calculated.

[0048] The experimental device for the flow field characteristics of a pulverized coal reverse-jet swirl burner in this invention measures the three-dimensional average velocity distribution, three-dimensional pulsating velocity distribution, and recirculation zone boundary in the flow field of the reverse-jet swirl burner. It calculates the turbulence intensity and recirculation zone area in the flow field, and can conduct in-depth research on the influence characteristics of factors such as reverse primary air volume, combustion load, and burner structural parameters on the flow field characteristics of the reverse-jet swirl burner. It clarifies the coupling and stable combustion characteristics between the reverse primary air and the secondary air in the swirl, optimizes the structure and operating parameters of the reverse-jet swirl burner when burning low-volatile, inferior pulverized coal, and better serves the deep and flexible peak-shaving retrofit of coal-fired power units.

[0049] In some embodiments, the temperature of the hot wire is kept constant by the correspondence between the heat exchange and speed of the hot wire of the three-dimensional hot film probe 3 placed in the flow field. The hot wire is connected to a feedback circuit based on a Wheatstone bridge for heating. When the speed changes, the heating power to the hot wire changes accordingly. Therefore, a correspondence between the electrical signal and the speed is established in the feedback circuit.

[0050] E 2 =A+BU 0.5

[0051] Where E is the voltage across the hot wire, U is the velocity of the airflow perpendicular to the hot wire, and A and B are fixed constants related to the hot wire.

[0052] For example, in this embodiment of the invention, the sampling frequency of the experimental device is set to 2kHz, the number of sampling points is 2048, and the speed measurement error is within ±0.03m / s.

[0053] Furthermore, the RMS velocity is calculated based on the average velocity and fluctuating velocity measured by the constant-temperature hot-wire anemometer 2. The RMS velocity is used to characterize the turbulence intensity, satisfying the following relationship:

[0054]

[0055] Among them, U i U is the pulsating velocity of the measurement point, in m / s; U is the average velocity of the measurement point, in m / s; n is the number of measurements taken at the measurement point.

[0056] like Figure 1 As shown, the experimental apparatus of this embodiment of the invention also includes an air supply assembly, which includes a blower and a bellows 6 connected in sequence.

[0057] The blower is a Roots blower (not shown in the figure). The air box 6 is connected to each air duct of the burner body 1 through a pipeline. A flow meter 7 and a valve 8 are installed on the pipeline between the air box 6 and the burner body 1.

[0058] During the experiment, the blower sends air into the air box 6. By adjusting the valves 8 on each pipe, the air in the air box 6 is sent into the burner's reverse injection primary air pipe 101, swirl internal secondary air pipe 102, and direct external secondary air pipe 103. The air volume in each pipe is measured by the mass flow meter 7.

[0059] The following describes an experimental method for the flow field characteristics of a pulverized coal reverse-jet swirl burner according to an embodiment of the present invention. This experimental method is used in the experimental apparatus for the flow field characteristics of a pulverized coal reverse-jet swirl burner in any of the above embodiments.

[0060] The experimental method for the flow field characteristics of a pulverized coal reverse-injection swirl burner according to embodiments of the present invention includes:

[0061] Open all pipe valves 8 in the experimental setup, turn on the blower frequency to 20 Hz, check the sealing of the experimental setup with leak detection fluid, and manually adjust all pipe valves 8 if there is no air leakage. Use the mass flow meter 7 of each pipe to display the required air volume for the experimental conditions.

[0062] The experimental setup includes the momentum of the pulverized coal carried by the primary air in the primary air momentum, and also considers the influence of the air temperature of each nozzle of the burner on the momentum during the actual combustion process. It ensures that the momentum ratio of each nozzle of the burner is equal to the momentum ratio of each nozzle during the actual combustion process, and uses the air flow field under normal temperature conditions inside the burner to simulate the flow field of pulverized coal during the actual combustion process inside the burner.

[0063] The boundary of the recirculation zone in the burner flow field is measured using the ribbon method. A mesh coordinate frame 4 with ribbons 5 attached is passed through the primary air duct 101 at different cross-sections with X / D = 0.17, 0.3, 0.4, 0.6, 0.8, 1, 1.2, 1.6, 2, 2.3, and 2.6. X represents the axial direction of the burner, and D is the inner diameter of the outer secondary air duct 103 (D = 300 mm). The direction of the ribbon 5 is the negative direction of X, which is the recirculation zone. All mesh areas in the negative direction are the boundaries of the recirculation zone, and the area of ​​the mesh area is the area of ​​the recirculation zone. The measurement error of the recirculation zone boundary is within ±0.03 m.

[0064] The three-dimensional average velocity distribution and three-dimensional pulsating velocity distribution in the burner flow field were measured using the constant temperature hot wire velocimetry method. The RMS velocity distribution was calculated based on the measurement results, and the RMS velocity was used to characterize the turbulence intensity of the flow field.

[0065] The experimental setup used a 55R95 three-dimensional hot film probe 3 for flow field measurement. Before measuring the flow field wind speed, the three-dimensional hot film probe 3 was calibrated to establish the relationship between the output voltage and the fluid velocity under the same experimental measurement and calibration conditions. A 54H10 two-point calibrator was used for calibration, and the probe's velocity and direction were calibrated in the 2Stream Ware Basic software of the constant temperature hot wire anemometer.

[0066] In the actual measurement process, in order to eliminate the difference between the flow field temperature and the air temperature at the calibrator outlet, temperature correction is required. In this experiment, the temperature deviation from the calibration temperature does not exceed 5℃. Therefore, the 90P10 temperature probe was selected to measure the ambient temperature in real time, which achieved temperature correction for data restoration and ensured the accuracy of data restoration.

[0067] In summary, the experimental method of this invention uses the airflow field under normal temperature conditions inside the burner to simulate the flow field change law of pulverized coal during actual combustion. It uses the ribbon method and constant temperature hot wire anemometer 2 to study the flow field characteristics under different influencing factors, providing data support for the optimization and improvement of the burner. It can propose an effective way to achieve rapid ignition, stable combustion, and improved combustion efficiency when burning low volatile matter low-quality bituminous coal. At the same time, it provides a simple, fast, and accurate way for the design and development of reverse-jet swirl burners, saving a lot of manpower and resources.

[0068] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0069] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0070] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0071] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0072] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0073] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. An experimental apparatus for the flow field characteristics of a pulverized coal counter-current swirl burner, characterized in that, include: The burner body includes a primary air duct, an inner secondary air duct, and an outer secondary air duct that are spaced apart from the inside to the outside. The nozzles of the inner secondary air duct and the outer secondary air duct are flush. The nozzle of the primary air duct is located downstream of the nozzle of the inner secondary air duct. A backflow cap is provided at the nozzle of the primary air duct so that the airflow ejected in reverse through the primary air duct and the airflow ejected through the inner and outer secondary air ducts can establish the flow field of the burner body. The first measurement component includes a constant-temperature hot-wire anemometer and a three-dimensional hot-film probe connected to the constant-temperature hot-wire anemometer. The three-dimensional hot-film probe is located within the flow field of the burner body, so that the constant-temperature hot-wire anemometer measures the three-dimensional average velocity distribution and the three-dimensional pulsating velocity distribution of the flow field of the burner body. The second measurement component includes a mesh coordinate frame and multiple ribbons tied to the mesh coordinate frame. The primary air duct passes through the mesh coordinate frame so that the shape and area of ​​the recirculation zone of the flow field of the burner body can be measured by the airflow direction traced by the ribbons. The first measurement component also includes a calibrator connected to the constant temperature hot wire anemometer, which is used to calibrate the three-dimensional hot film probe. The first measuring component also includes a temperature probe, which is connected to the constant temperature hot wire anemometer. The temperature probe is located within the flow field of the burner body and is used to measure the experimental ambient temperature.

2. The experimental apparatus for the flow field characteristics of a pulverized coal counter-current swirl burner according to claim 1, characterized in that, The hot wire of the three-dimensional thermal film probe is used to connect to the circuit for heating, so as to establish a correspondence between the electrical signal and the flow field wind speed in the circuit, satisfying the following relationship: Where E is the voltage across the hot wire, U is the velocity of the airflow perpendicular to the hot wire, and A and B are fixed constants related to the hot wire.

3. The experimental apparatus for the flow field characteristics of a pulverized coal counter-current swirl burner according to claim 2, characterized in that, The RMS velocity is calculated based on the average velocity and pulsating velocity measured by the constant-temperature hot-wire anemometer, satisfying the following relationship: Among them, U i Let U be the pulsating velocity of the measurement point, U be the average velocity of the measurement point, and n be the number of measurements taken at the measurement point.

4. The experimental apparatus for the flow field characteristics of a pulverized coal counter-current swirl burner according to claim 1, characterized in that, It also includes an air supply assembly, which includes a blower and an air box connected in sequence. The air box is connected to each air duct of the burner body via a pipeline. A flow meter and a valve are provided on the pipeline between the air box and the burner body.

5. An experimental method for the flow field characteristics of a pulverized coal counter-current swirl burner, characterized in that, The experimental method is used in the experimental apparatus for the flow field characteristics of a pulverized coal reverse-jet swirl burner according to any one of claims 1-4, and the experimental method includes: The flow field of air under normal temperature conditions inside the burner is used to simulate the flow field of pulverized coal during actual combustion in the burner. The shape and area of ​​the recirculation zone in the burner flow field were measured using the ribbon method. The three-dimensional average velocity distribution and three-dimensional pulsating velocity distribution in the burner flow field were measured using the constant temperature hot wire velocimetry method. The RMS velocity distribution was calculated based on the measurement results, and the RMS velocity was used to characterize the turbulence intensity of the flow field.

6. The experimental method for the flow field characteristics of a pulverized coal counter-current swirl burner according to claim 5, characterized in that, During the experiment, the momentum of the pulverized coal carried by the primary air was included in the momentum of the primary air, and the momentum ratio of each nozzle of the burner was equal to the momentum ratio of each nozzle during the actual combustion process.

7. The experimental method for the flow field characteristics of a pulverized coal reverse-jet swirl burner according to claim 5, characterized in that, During the measurement of the recirculation zone of the flow field, a mesh coordinate frame with ribbons attached is placed on different cross sections with X / D = 0.17, 0.3, 0.4, 0.6, 0.8, 1, 1.2, 1.6, 2, 2.3, and 2.

6. X represents the axial direction of the burner, D is the inner diameter of the external secondary air duct, and the direction of the ribbons is the negative direction of X, which is the recirculation zone. All mesh areas in the negative direction are the boundaries of the recirculation zone, and the area of ​​the mesh area is the area of ​​the recirculation zone.

8. The experimental method for the flow field characteristics of a pulverized coal reverse-jet swirl burner according to claim 5, characterized in that, Before measuring the wind speed in the flow field, the probe used for measurement is calibrated to establish the relationship between the output voltage and the fluid velocity under the same experimental measurement conditions and calibration conditions.

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