Experimental device and method for flow field characteristics of pulverized coal reverse injection swirling burner

Abstract

The invention discloses a pulverized coal reverse spraying turbulent burner flow field characteristic experiment device and method, the experiment device comprises a burner body, a first measurement assembly and a second measurement assembly, the first measurement assembly comprises a constant temperature hot wire anemometer and a three-dimensional hot film probe, the three-dimensional hot film probe is located in a flow field, and the burner body is located in the burner body. The first measuring assembly comprises a first measuring assembly and a second measuring assembly to measure three-dimensional average velocity distribution and three-dimensional pulsation velocity distribution of the flow field, the second measuring assembly comprises a net-shaped coordinate frame and a plurality of ribbons bound on the net-shaped coordinate frame, and the primary air pipe penetrates through the net-shaped coordinate frame so that the shape and area of a backflow area of the flow field of the combustor body can be measured in the airflow direction traced by the ribbons. According to the experimental method, the flow field change of pulverized coal in the combustor in the actual combustion process is simulated through the flow field of air in the combustor in the normal temperature state, the flow field characteristics under different working conditions are researched through a ribbon method and constant-temperature hot-wire speed measurement, and the reverse jet flow coupling rotational flow stable combustion mechanism is explored; therefore, deep and flexible peak regulation transformation of the coal power unit can be better served.

Description

Technical Field

[0001] The invention relates to the technical field of combustion performance testing, and in particular to a flow field characteristic experimental device and method for a coal powder reverse injection swirl burner. Background Art

[0002] As the proportion of new energy sources such as wind energy and solar energy in the energy structure continues to increase, the flexible peak-shaving capacity of coal-fired power units faces greater challenges, and the proportion of difficult-to-burn coal types in coal-fired power units continues to increase. Therefore, the stable combustion of the boiler combustion side under low load is crucial. The reverse jet swirl burner is a high-efficiency, low-nitrogen pulverized coal burner that integrates reverse jet combustion technology and swirl combustion technology. It has the advantages of low ignition heat, rapid ignition, and short start-up and shutdown time. It has been used in the flexible peak-shaving upgrade and transformation of 300MW four-corner tangential pulverized coal boilers in power plants. In summary, by studying the flow field law in 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 to achieve safe and stable operation of coal-fired power units at low loads. Summary of the invention

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

[0004] To this end, an embodiment of the present invention proposes a flow field characteristic experimental device for a pulverized coal reverse jet swirl burner to solve the problem of stable combustion of a reverse jet swirl burner when burning low-volatile low-quality bituminous coal.

[0005] The flow field characteristics experimental device of the pulverized coal reverse injection swirl burner according to the embodiment of the present invention comprises:

[0006] A burner body, the burner body comprising a primary air duct, an inner secondary air duct and an outer secondary air duct spaced from the inside to the outside, the nozzle of the inner secondary air duct is flush with the nozzle of the outer secondary air duct, the nozzle of the primary air duct is located downstream of the nozzle of the inner secondary air duct, and a return cap is provided at the nozzle of the primary air duct, so that the airflow reversely ejected through the primary air duct and the airflow ejected from the inner secondary air duct and the outer secondary air duct establish a flow field of the burner body;

[0007] a first measuring assembly, the first measuring assembly comprising 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 being located in 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 measuring component includes a grid coordinate frame and a plurality of ribbons tied to the grid coordinate frame, and the primary air duct runs through the grid 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.

[0009] The pulverized coal reverse jet swirl burner flow field characteristics experimental device of the embodiment of the present invention measures the three-dimensional average velocity distribution, the three-dimensional pulsating velocity distribution and the recirculation zone boundary in the reverse jet swirl burner flow field, calculates the turbulence in the flow field and the recirculation zone area, and can deeply study the influence of influencing factors such as reverse primary air volume, combustion load, and burner structural parameters on the flow field characteristics of the reverse jet swirl burner, clarify the coupled stable combustion characteristics between the reverse primary air and the secondary air in the swirl, optimize the structure and operating parameters of the reverse jet swirl burner when burning low-volatile inferior coal powder, and better serve the deep and flexible peak-shaving transformation of coal-fired power units.

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

[0011] E 2 =A+BU 0.5

[0012] Among them, E is the voltage across the hot wire, U is the speed of the wind flow perpendicular to the hot wire, and A and B are fixed constants related to the hot wire.

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

[0014]

[0015] Among them, U i is the pulsation speed of the measuring point, U is the average speed of the measuring point, and n is the number of measurements at the measuring point.

[0016] In some embodiments, an air supply assembly is also included, which includes a blower and a bellows connected in sequence, the bellows is connected to each air duct of the burner body through a pipeline, and a flow meter and a valve are provided on the pipeline between the bellows and the burner body.

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

[0018] In some embodiments, the first measurement component further includes a temperature probe, the temperature probe is connected to the constant temperature hot wire anemometer, the temperature probe is located in the flow field of the burner body, and the temperature probe is used to measure the experimental environment temperature.

[0019] An embodiment of the present invention further provides a method for testing flow field characteristics of a pulverized coal reverse injection swirl burner. The method is used in the device for testing flow field characteristics of a pulverized coal reverse injection swirl burner described in any one of the above embodiments.

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

[0021] The flow field of the wind at normal temperature in the burner is used to simulate the flow field of the pulverized coal in the actual combustion process in the burner;

[0022] The ribbon method is used to measure the shape and area of ​​the recirculation zone in the burner flow field;

[0023] The three-dimensional average velocity distribution and three-dimensional pulsating velocity distribution in the burner flow field are measured by the constant temperature hot wire velocimetry method. The RMS velocity distribution is calculated based on the measurement results, and the RMS velocity is used to characterize the turbulence 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 a ribbon is placed on different sections of 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 outer secondary air duct, the negative direction of the ribbon direction X is the recirculation zone, all grid areas in the negative direction are the boundaries of the recirculation zone, and the area of ​​the grid area is the area of ​​the recirculation zone.

[0026] In some embodiments, the measuring probe is calibrated before measuring the wind speed of the flow field, and a relationship between the output voltage and the fluid velocity is established when the experimental measurement conditions are the same as the calibration conditions. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 2 4 is a second schematic diagram of the experimental device according to an embodiment of the present invention.

[0029] Reference numerals:

[0030] 1-burner 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-grid coordinate frame, 5-ribbon, 6-bellows, 7-flow meter, 8-valve, 9-converter, 10-computer, 11-temperature probe. DETAILED DESCRIPTION

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

[0033] The following describes the flow field characteristics experimental device of the pulverized coal reverse injection swirl burner according to the embodiment of the present invention in conjunction with the accompanying drawings.

[0034] like Figure 1 and Figure 2 As shown, the flow field characteristic experimental device of the pulverized coal reverse injection swirl burner according to the embodiment of the present invention comprises: 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 nozzle of the inner secondary air duct 102 is flush with the nozzle of the outer secondary air duct 103. The nozzle of the primary air duct 101 is located downstream of the nozzle of the inner secondary air duct 102. A reflux 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 reversely sprayed from the primary air duct 101 and the airflow sprayed from the inner secondary air duct 102 and the outer secondary air duct 103. That is, the experimental device of the embodiment of the present invention is suitable for measuring the flow field characteristics of a swirl burner with a reverse-spraying primary air duct 101, and the flow field changes of coal powder in the actual combustion process in the burner are simulated by the flow field of the wind at normal temperature in the burner.

[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 . The three-dimensional hot film probe 3 is located in the flow field of the burner body 1 .

[0038] It is understandable that the core part of the constant temperature hot wire anemometer 2 is a heated hot wire (usually a platinum wire or a nickel wire), and the hot wire (that is, the three-dimensional hot film probe 3) is placed in the airflow to be measured. When the airflow flows through the hot wire, the airflow will take away the heat of the hot wire, causing the temperature of the hot wire to decrease. By measuring the temperature change of the hot wire, the speed of the airflow can be determined.

[0039] In the constant temperature hot wire anemometer 2, the circuit adjusts the current through the hot wire to keep the temperature of the hot wire constant. Therefore, when the airflow speed changes, the circuit automatically adjusts the current to keep the temperature of the hot wire constant. The change in current is inversely proportional to the airflow speed, so the wind speed can be accurately measured.

[0040] Therefore, the experimental device of the embodiment of the present invention uses the constant temperature hot wire anemometer 2 to measure the three-dimensional average velocity distribution and the 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 in the flow field of the burner body 1 and is used to measure the experimental environment temperature.

[0043] The probe holder is used to fix and support the probe to ensure its stability during measurement. The holder design should take into account the installation position and angle of the probe to obtain the best measurement effect.

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

[0045] The data processing software workstation is used to collect, store, analyze and visualize the measured data. The software workstation usually has functions such as calibration, data correction, calculation of wind speed and turbulence parameters, etc.

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

[0047] In other words, the experimental device of the embodiment of the present invention adopts the ribbon method, and the airflow direction is displayed by a coordinate frame tied with a red gauze ribbon 5 with a length of 2 cm. The distance between adjacent grids is 3 cm. The airflow direction traced by the ribbon 5 is used to draw the boundary of the recirculation zone, and then the area of ​​the recirculation zone is calculated.

[0048] The pulverized coal reverse jet swirl burner flow field characteristics experimental device of the embodiment of the present invention measures the three-dimensional average velocity distribution, the three-dimensional pulsating velocity distribution and the recirculation zone boundary in the reverse jet swirl burner flow field, calculates the turbulence in the flow field and the recirculation zone area, and can deeply study the influence of influencing factors such as reverse primary air volume, combustion load, and burner structural parameters on the flow field characteristics of the reverse jet swirl burner, clarify the coupled stable combustion characteristics between the reverse primary air and the secondary air in the swirl, optimize the structure and operating parameters of the reverse jet swirl burner when burning low-volatile inferior coal powder, and better serve the deep and flexible peak-shaving transformation of coal-fired power units.

[0049] In some embodiments, 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 is used to ensure that the temperature of the hot wire remains unchanged, and 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, thereby establishing a correspondence between the electrical signal and the speed in the feedback circuit.

[0050] E 2 =A+BU 0.5

[0051] Among them, E is the voltage across the hot wire, U is the speed of the wind flow perpendicular to the hot wire, and A and B are fixed constants related to the hot wire.

[0052] For example, the sampling frequency of the measuring points of the experimental device in the embodiment of the present invention 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 pulsating velocity measured by the constant temperature hot wire anemometer 2, and the RMS velocity is used to characterize the turbulence, satisfying the relationship:

[0054]

[0055] Among them, U i is the pulsation velocity of the measuring point, m / s; U is the average velocity of the measuring point, m / s; n is the number of measurements at the measuring point.

[0056] like Figure 1 As shown, the experimental device of the embodiment of the present invention further includes an air supply component, which includes a blower and a bellows 6 connected in sequence.

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

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

[0059] The following describes a method for experimenting on flow field characteristics of a pulverized coal reverse injection swirl burner according to an embodiment of the present invention. The method is used for an experiment device for experimenting on flow field characteristics of a pulverized coal reverse injection swirl burner in any of the above embodiments.

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

[0061] Open each pipeline valve 8 in the experimental device, turn on the blower frequency to 20 Hz, use a leak detection liquid to check the sealing of the experimental device, manually adjust each pipeline valve 8 when there is no air leakage, and use each pipeline mass flow meter 7 to display the air volume required for the experimental working conditions.

[0062] The experimental device includes the momentum of pulverized coal carried by the primary air into the momentum of the primary air, and considers the influence of the wind temperature of each burner nozzle on the momentum during the actual combustion process, ensuring that the momentum ratio of each burner nozzle is equal to the momentum ratio of each nozzle during the actual combustion process, and uses the flow field of the wind at normal temperature in the burner to simulate the flow field of pulverized coal in the actual combustion process in the burner.

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

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

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

[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, the temperature needs to be corrected. In this experimental environment, the temperature deviation from the calibration temperature does not exceed 5°C. Therefore, the 90P10 temperature probe 11 is selected to measure the ambient temperature in real time, realizing the temperature correction of data restoration and ensuring the accuracy of data restoration.

[0067] In summary, the experimental method of the embodiment of the present invention utilizes the flow field of wind at normal temperature in the burner to simulate the flow field change law of coal powder in the actual combustion process in the burner, and uses the ribbon method and the constant temperature hot wire anemometer 2 to measure the flow field characteristics under different influencing factors, thereby providing data support for the optimization and improvement of the burner, and can propose an effective way to quickly ignite, stably burn, and improve combustion efficiency when burning low-volatile low-quality bituminous coal. At the same time, it also provides a simple, fast and accurate way for the design and development process of the reverse jet swirl burner, saving a lot of manpower and material resources.

[0068] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0069] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0070] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0071] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0072] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0073] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A pulverized coal reverse injection swirl burner flow field characteristics experimental device, characterized in that: include: A burner body, the burner body comprising a primary air duct, an inner secondary air duct and an outer secondary air duct spaced from the inside to the outside, the nozzle of the inner secondary air duct is flush with the nozzle of the outer secondary air duct, the nozzle of the primary air duct is located downstream of the nozzle of the inner secondary air duct, and a return cap is provided at the nozzle of the primary air duct, so that the airflow reversely ejected through the primary air duct and the airflow ejected from the inner secondary air duct and the outer secondary air duct establish a flow field of the burner body; a first measuring assembly, the first measuring assembly comprising 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 being located in 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 measuring component includes a grid coordinate frame and a plurality of ribbons tied to the grid coordinate frame, and the primary air duct runs through the grid 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.

2. The flow field characteristics experimental device of the pulverized coal reverse injection swirl burner according to claim 1 is characterized in that: The heating wire of the three-dimensional thermal film probe is used to connect to the circuit for heating, so as to establish a corresponding relationship between the electrical signal and the flow field wind speed in the circuit, satisfying the relationship: AND 2 =A+BU 0.5 Among them, E is the voltage across the hot wire, U is the speed of the wind flow perpendicular to the hot wire, and A and B are fixed constants related to the hot wire.

3. The flow field characteristics experimental device of the pulverized coal reverse injection swirl burner according to claim 2 is characterized in that: The RMS speed is calculated based on the average speed and pulsating speed measured by the constant temperature hot wire anemometer, satisfying the relationship: Among them, U i is the pulsation speed of the measuring point, U is the average speed of the measuring point, and n is the number of measurements at the measuring point.

4. The flow field characteristics experimental device of coal powder reverse injection swirl burner according to claim 1 is characterized in that: It also includes an air supply component, which includes a blower and a bellows connected in sequence. The bellows is connected to each air duct of the burner body through a pipeline. A flow meter and a valve are provided on the pipeline between the bellows and the burner body.

5. The pulverized coal reverse injection swirl burner flow field characteristics experimental device according to claim 1 is characterized in that: The first measurement component also includes a calibrator, which is connected to the constant temperature hot wire anemometer and is used to calibrate the three-dimensional hot film probe.

6. The flow field characteristics experimental device of the pulverized coal reverse injection swirl burner according to claim 5 is characterized in that: The first measurement component also includes a temperature probe, which is connected to the constant temperature hot wire anemometer. The temperature probe is located in the flow field of the burner body and is used to measure the experimental environment temperature.

7. A method for testing the flow field characteristics of a pulverized coal reverse injection swirl burner, characterized in that: The experimental method is used for the flow field characteristics experimental device of the pulverized coal reverse injection swirl burner according to any one of claims 1 to 6, and the experimental method comprises: The flow field of the wind at normal temperature in the burner is used to simulate the flow field of the pulverized coal in the actual combustion process in the burner; The ribbon method is used to measure the shape and area of ​​the recirculation zone in the burner flow field; The three-dimensional average velocity distribution and three-dimensional pulsating velocity distribution in the burner flow field are measured by the constant temperature hot wire velocimetry method. The RMS velocity distribution is calculated based on the measurement results, and the RMS velocity is used to characterize the turbulence of the flow field.

8. The flow field characteristics experimental method of the pulverized coal reverse injection swirl burner according to claim 7 is characterized in that: 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 burner nozzle is equal to the momentum ratio of each nozzle in the actual combustion process.

9. The flow field characteristics experimental method of the pulverized coal reverse injection swirl burner according to claim 7, characterized in that: In the process of measuring the recirculation zone of the flow field, the grid coordinate frame tied with ribbons is placed on different sections of 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, the negative direction of the ribbon direction X is the recirculation zone, all grid areas in the negative direction are the boundaries of the recirculation zone, and the area of ​​the grid area is the area of ​​the recirculation zone.

10. The flow field characteristics experimental method of a pulverized coal reverse injection swirl burner according to claim 7, characterized in that: Before measuring the wind speed in the flow field, the measuring probe is calibrated to establish the relationship between the output voltage and the fluid velocity when the experimental measurement conditions are the same as the calibration conditions.

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