Method and device for measuring concentration of pulverized coal particle flow

Abstract

The invention relates to the technical field of pulverized coal concentration measurement, in particular to a pulverized coal particle flow concentration measurement method and device. The measuring method comprises the following steps: arranging the pulverized coal particle flow concentration measuring device on a fluid pipeline to be measured; enabling a feed loop antenna on the side surface of the coaxial cavity to access a microwave signal and feed the microwave signal into the coaxial cavity to generate resonance; under the action of an opening in the lower end of the coaxial cavity and the inner wave guide column, part of the electromagnetic field in the coaxial cavity is strayed into a fluid pipeline of pulverized coal particles through the stray cavity; the pulverized coal fluid disturbs the electromagnetic field and changes the resonant frequency when passing through the electromagnetic field strayed into the fluid pipeline; the disturbed microwave signal is received by another feed loop antenna on the side surface of the coaxial cavity, and resonant frequency offset before and after disturbance is determined through a signal processing circuit; the pulverized coal concentration is determined according to the resonant frequency offset based on the pre-fitted relational expression between the resonant frequency offset and the pulverized coal concentration, so that the measurement precision is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pulverized coal concentration measurement, and particularly relates to a method and device for measuring the concentration of pulverized coal particle flow. Background Art

[0002] At present, there are the following several methods for measuring the concentration of pulverized coal particle flow in the primary air powder feeding link of power plant boilers:

[0003] (1) Heat balance method

[0004] The heat balance method calculates the pulverized coal concentration by using the heat conservation of hot air, pulverized coal, and their mixture. A section of distance in the pneumatic conveying pipeline is selected as the measurement pipe section. Before the air and pulverized coal are mixed, the temperatures of the air and pulverized coal are measured respectively, and then the temperature after their mixture is detected. The temperatures of the pulverized coal and air before and after mixing will change accordingly. From the change in temperature, there is a heat balance equation (Equation (1)):

[0005]

[0006] In the formula, C w1 、C w3 、C c2 、C c3 are the specific heats of the air and pulverized coal before and after mixing.

[0007] Problem analysis of the heat balance method: This method can only be used to measure the pulverized coal concentration in the intermediate storage pulverized coal preparation system with hot air powder feeding. For the lean gas powder feeding and direct firing pulverized coal preparation systems, there is no energy balance process available for measurement and calculation during the air-powder mixing process. Therefore, the concentration of primary air pulverized coal cannot be measured.

[0008] (2) Electrostatic (charge induction) method

[0009] The essence of electrostatic measurement is that when pulverized coal particles move in the pipeline with the air flow, due to the collision, friction, and separation between the particles and the pipe wall, and between the particles, charge transfer is caused, resulting in the accumulation of static charges on the particles. The static charges contain a large amount of information such as particle velocity, concentration, and particle size. An electrostatic sensor is used to measure the static charges of the pulverized coal particles, and then a relationship expression between the output voltage of the electrostatic sensor and the pulverized coal concentration is established through a mathematical modeling method to obtain the pulverized coal concentration.

[0010] Many researchers, represented by the University of Kent in the UK, have conducted a large number of studies on the model and characteristics of electrostatic sensors. After ignoring factors such as two-phase flow pattern changes, pulverized coal fineness, pipe shape, and charge transfer, a model based on electrostatic induction is obtained:

[0011] E = f(C, v)

[0012] Where: E is the charge induction signal strength, C is the pulverized coal concentration, and v is the pulverized coal flow rate.

[0013] In actual working conditions, there are many application limitations in measuring pulverized coal concentration by the electrostatic method, mainly including:

[0014] ① Most of the measured media are media with low conductivity, such as ash powder, limestone, etc., while the conductivity of pulverized coal is relatively high, and it is difficult to stably maintain static charges. ② Due to the phenomenon of charge saturation, it is more suitable for application in extremely dilute phases and low-flow-rate occasions. ③ The sensor itself cannot overcome the interference caused by charge transfer. ④ The original output signal of the sensor has a large randomness, which is related to factors such as primary air velocity, pulverized coal quality, pulverized coal fineness, pulverized coal humidity, primary air temperature, the direction and shape of the primary air pipeline, and the shape of the sensor itself, making it difficult to accurately obtain concentration information. ⑤ The sensor itself deforms under the erosion of primary air, and the charge induced by the sensor will also change under the same working conditions, and the calibration coefficient will inevitably change accordingly. It is impossible to conduct experimental calibration frequently during application.

[0015] Therefore, in actual applications, the accuracy of measuring pulverized coal concentration by the electrostatic method is relatively low. At most, it can only give the relative values of the pulverized coal concentration in the primary air of each coal mill. The pulverized coal concentrations in the primary air of different coal mills are not comparable. In some sites, there may even be situations where detection is impossible.

[0016] (3) Ultrasonic method, optical method, capacitance method

[0017] Ultrasonic waves are mechanical waves, and their propagation depends very much on the medium. Therefore, their measurement will be affected by many factors in the air-powder mixed medium, including pulverized coal velocity, temperature, fineness, flow state, uneven local porosity, etc. The optical method is relatively high in cost. Its essence is to detect parameters such as light intensity through the propagation and reflection of light. Placing it in a pulverized coal pipeline with an average particle diameter not exceeding 100 microns and sometimes containing moisture, it is very easy to stick the probe and cannot guarantee the optical signal path. Different from the electrostatic method, the capacitance method is an active detection technology and is suitable for measuring the flow of non-conductive or low-conductive particles. When measuring by the capacitance method, it is easily affected by the charges accumulated on the pulverized coal particles, and it is very easy to generate temperature drift in the hardware, affecting the measurement stability and thus the measurement accuracy.

[0018] (4) Microwave method

[0019] When detecting the pulverized coal concentration in the primary air pipeline in a thermal power plant, it mainly utilizes the absorption, scattering, and resonance of pulverized coal to microwaves, thereby changing parameters such as the amplitude, phase, and resonance frequency of microwaves. By detecting the intensity and frequency shift of microwave signals, the pulverized coal concentration in the primary air is obtained. Yingnaz Zheng, a scholar from the University of Birmingham in the UK, detailedly reviewed and analyzed the methods for process parameters of gas-solid two-phase flows of existing technologies and existing products, and believed that among these methods, microwave technology is considered to be one of the most promising technologies for on-site applications.

[0020] At present, the research and development in the field of microwave detection has had a relatively good foundation. The mainstream detection methods are as follows: Free space reflection method: The sensor emits low-energy microwave signals into the metal pipeline for transporting pulverized coal. When the microwave encounters the pulverized coal, reflection occurs. This method reflects the density of the pulverized coal by measuring the reflected energy of the microwave. Free space attenuation method: It adopts the method of installing microwave transmitting antennas and microwave receiving antennas at an angle greater than 90 degrees to the flowing direction of the pulverized coal (similar to the ultrasonic method). These antennas are usually truncated cone horn antennas. After the microwave interacts with the pulverized coal, attenuation occurs, and the degree of attenuation depends on the mass concentration of the pulverized coal. Waveguide method: Regarding the primary air pipeline as a waveguide, by measuring the change in microwave transmission parameters, the change in the dielectric characteristics of the gas-solid two-phase flow is detected, thereby obtaining the concentration of the measured object.

[0021] In summary, for current concentration measurement, among the existing measurement methods, the most widely used for direct measurement is the thermal equilibrium method. However, due to the large problem of effective heat calculation, the measurement results are unreliable. Among the indirect measurement methods, ultrasonic, optical, and capacitance methods have large applicability problems, making it almost impossible to apply them in industrial fields at present. The electrostatic method is widely used in the field. However, from the perspective of measurement results, although it claims a high measurement accuracy (5%), and the measurement is accurate through calibration, due to the instability of the cumulative charge amount of the pulverized coal, the measurement error often exceeds 10%. The microwave method is also actually applied in the field. However, from the perspective of the measurement electronic circuit, the measurement accuracy based on the attenuation amplitude is much lower than that of frequency measurement. Summary of the Invention

[0022] The sensor provided by the present invention has a principle different from any sensor applied in the field and a structure under this principle. This sensor is applied to the industrial process of pneumatic conveying of particles, such as the primary air powder feeding of a power plant boiler. It mainly solves the problem that the concentration of solid particles in this process cannot be accurately measured.

[0023] To solve the above problems, the present invention adopts the following technical solutions:

[0024] In a first aspect, the present invention provides a device for measuring the concentration of pulverized coal particle flow, which includes:

[0025] A sensor structure,

[0026] A coaxial cavity formed on the sensor structure. The lower end of the coaxial cavity is open and blocked by a dust cover. An inner waveguide column is coaxially arranged in the coaxial cavity. Two oppositely arranged feeding holes for installing feeding loop antennas are opened on the side surface of the coaxial cavity;

[0027] A base for welding on the fluid pipeline to be measured, and the lower end of the coaxial cavity is welded to the base;

[0028] A stray cavity is formed on the sensor structure. One end of the stray cavity forms a hinge platform for mounting and connecting with the base, and the other end can be embedded into the fluid pipeline through a through hole opened on the fluid pipeline. The bottom end of the inner waveguide column can pass through the dust cover and the stray cavity and be flush with the inner wall of the fluid pipeline.

[0029] As a preferred embodiment, the dust cover is an organic glass dust cover and is bonded to the lower end of the coaxial cavity.

[0030] As a preferred embodiment, a bolt hole is opened at the center of the inner diameter of the upper end of the coaxial cavity, and the inner waveguide column is installed at the bolt hole by threading.

[0031] As a preferred embodiment, the bottom end of the base is arc-shaped for fitting with the outer wall of the fluid pipeline.

[0032] As a preferred embodiment, one end of the stray cavity embedded in the fluid pipeline is cut into an arc shape and is flush with the inner wall surface of the fluid pipeline. The outer diameter of the stray cavity is the same as the aperture of the through hole opened on the fluid pipeline.

[0033] As a preferred embodiment, the inner diameter of the inner waveguide column is not greater than a preset value, and the preset value is positively correlated with the inner diameter of the fluid pipeline to be measured.

[0034] As a preferred embodiment, the inner diameter of the antenna loop of the feed ring antenna is not greater than the corresponding preset value; microwave signals are fed into the coaxial cavity through the feed ring antenna, and the microwave operates at 550 - 650 MHz and is excited in a swept-frequency working mode.

[0035] In a second aspect, the present invention provides a method for measuring the concentration of pulverized coal particle flow, which is realized by using the above-mentioned device for measuring the concentration of pulverized coal particle flow. The measurement method includes:

[0036] Arrange the device for measuring the concentration of pulverized coal particle flow on the fluid pipeline to be measured;

[0037] Connect one feed ring antenna on the side of the coaxial cavity to a microwave signal and feed it into the coaxial cavity to generate resonance;

[0038] Under the action of the opening at the lower end of the coaxial cavity and the inner waveguide column, part of the electromagnetic field in the coaxial cavity is scattered into the fluid pipeline of the pulverized coal particles through the stray cavity;

[0039] When the pulverized coal fluid passes through the electromagnetic field scattered into the fluid pipeline, it disturbs the electromagnetic field and changes the resonance frequency;

[0040] The disturbed microwave signal is received by another feed ring antenna on the side of the coaxial cavity, and the signal processing circuit is used to determine the resonance frequency offset before and after the disturbance.

[0041] Based on the relational expression between the resonant frequency offset and the pulverized coal concentration obtained by pre-fitting, the pulverized coal concentration is determined according to the resonant frequency offset.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] From the simulation results, when the pulverized coal in the pipeline is fully developed and evenly distributed, the sensor of the present invention can accurately measure the pulverized coal concentration, and the measurement frequency resolution is 0.8MHz / 1% on average between 20% and 70%. From the sensor end, it is very easy to achieve a frequency resolution of 0.8MHz, and an ordinary hardware frequency resolution can reach 1KHz. The measurement accuracy of market products is generally 5%. From the simulation, the measurement device of the present invention can reach a resolution of 1%. Description of the Drawings

[0044] Figure 1 It is a schematic structural diagram of the measuring device in Embodiment 1;

[0045] Figure 2 It is a physical picture of the measuring device in Embodiment 1;

[0046] Figure 3 It is a magnetic field distribution diagram of resonance generated in the coaxial cavity in Embodiment 1;

[0047] Figure 4 It is an electric field distribution diagram of resonance generated in the coaxial cavity in Embodiment 1;

[0048] Figure 5 It is an electromagnetic field distribution diagram of the stray into the fluid pipeline after resonance is generated in the coaxial cavity;

[0049] Figure 6 It is a mixed dielectric constant model diagram in Embodiment 1;

[0050] Figure 7 It is a simulation curve obtained with the pulverized coal concentration of 20% - 80% as a variable;

[0051] Figure 8 It is the S11 and S21 curves measured by the fluid field and electromagnetic field coupling simulation experiment when the pulverized coal concentration is 50%; Detailed Embodiments

[0052] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more. In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0053] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0054] Embodiment 1

[0055] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0056] Combined with Figure 1 - Figure 2, this embodiment provides a device for measuring the concentration of pulverized coal particle flow. The measuring device includes a sensor structure. A coaxial cavity 2 and a stray cavity are formed in the sensor structure. The lower end of the coaxial cavity 2 is open and sealed with a dust cover 5. In a specific embodiment, the lower end of the coaxial cavity 2 is bonded to the cavity with an acrylic dust cover 5 to seal the opening of the coaxial cavity 2. An inner waveguide post 3 is coaxially arranged in the coaxial cavity 2. A bolt hole is opened at the center of the inner diameter of the upper end of the coaxial cavity 2. The inner waveguide post 3 is installed at the bolt hole by threading. Two feeding holes for installing feeding loop antennas 4 are oppositely arranged on the side of the coaxial cavity 2, and the two feeding holes are 180°. The sensor structure further includes a base 1, and the base 1 is used for welding on the fluid pipeline 6 to be measured. In this embodiment, the base is a square steel plate, and the lower surface is designed to be arc-shaped to fit the pipeline for tight fitting and welding. The lower end of the coaxial cavity 2 is welded to the base 1.

[0057] One end of the stray cavity (the main body is cylindrical) forms a hinge platform for installing and connecting with the base 1. Specifically, a circular steel bar is welded on the outer wall of the stray cavity to form a hinge platform, and a hole is drilled in its center, and it is connected to the base 1 with bolts; the other end can pass through a through hole opened on the fluid pipeline 6 and be embedded into the fluid pipeline 6. The bottom end of the inner waveguide post can pass through the stray cavity and be flush with the inner wall of the fluid pipeline. Specifically, in order to achieve a non-invasive design in this embodiment, a through hole is opened on the fluid pipeline 6, and the aperture of the through hole is the same as the outer diameter of the stray cavity. The part of the stray cavity embedded in the fluid pipeline 6 is cut into an arc shape and is flush with the inner wall surface of the pipeline.

[0058] The working principle of the measuring device is as follows: Arrange the device for measuring the concentration of pulverized coal particle flow on the fluid pipeline 6 to be measured; connect one feeding loop antenna 4 on the side of the coaxial cavity 2 to a microwave signal and feed it into the coaxial cavity 2 to generate resonance. In this embodiment, the microwave signal is fed through the feeding loop antenna 4, and the microwave is at 550 - 650 MHz and is excited in a swept-frequency working mode. The electric field lines and magnetic field lines at resonance are as follows Figure 3 and Figure 4 shown; Part of the electromagnetic field in the coaxial cavity 2 is scattered into the fluid pipeline 6 of pulverized coal particles through the stray cavity, and the electromagnetic field distribution in the fluid pipeline 6 is as Figure 5 shown; Under the action of the open lower end of the coaxial cavity 2 and the inner waveguide post 3, when the pulverized coal fluid passes through the electromagnetic field scattered into the fluid pipeline 6, it disturbs the electromagnetic field and changes the resonance frequency; the disturbed microwave signal is received by another feeding loop antenna 4 on the side of the coaxial cavity 2, and the signal processing circuit determines the resonance frequency offset before and after the disturbance; based on the relationship between the resonance frequency offset and the pulverized coal concentration obtained by pre-fitting, the pulverized coal concentration is determined according to the resonance frequency offset.

[0059] The diameter of the inner waveguide column 3, the diameter of the feeding loop antenna 4, the inner diameter of the antenna loop, and the connection method between the antenna, the feeding plug, and the antenna in this embodiment are all optimized designs. During actual use, to adapt to different fluid pipes 6, the length of the inner waveguide column is generally not less than 94 mm and not more than 114 mm. The inner diameter of the inner waveguide column 3 is not greater than a preset value, and the preset value is positively correlated with the inner diameter of the fluid pipe 6 to be measured. Taking a specific example for illustration, when the measuring device is applied to a fluid pipe 6 with an inner diameter of 500 mm, the corresponding parameter settings are as follows: the diameter of the inner waveguide column 3 is not greater than 12 mm; the inner diameter of the antenna loop is not greater than 26 mm. Correspondingly, when the measuring device is applied to fluid pipes 6 with other inner diameters, the parameter settings for the fluid pipe 6 with an inner diameter of 500 mm can be used as a reference and set according to a preset ratio. For example, when applied to a fluid pipe 6 with an inner diameter of 600 mm, all parameters need to be enlarged by 1.1 times adaptively to ensure measurement accuracy.

[0060] In addition, the inner diameter of the antenna loop of the feeding loop antenna 4 is not greater than 26 mm; the external thread of the RF adapter is hinged to the internal thread of the antenna, and the microwave signal is fed into the antenna through the feeding loop antenna 4. The microwave operates at 550 - 650 MHz and is excited in a frequency-sweeping working mode.

[0061] Combined with Figure 6 , the specific principle for determining the pulverized coal concentration according to the resonant frequency offset in this embodiment is as follows: The resonant cavity perturbation method can be used to obtain the relationship between the change in resonant frequency and the dielectric constant of the mixture medium in the pipeline. Since the concentration of the medium inside the original resonant cavity changes, it causes changes in the magnitude and structure of the electromagnetic field, etc., thereby resulting in the resonant frequency inside the resonant cavity.

[0062] By deriving the Maxwell's equations, the relationship between the dielectric constant ε and the resonant frequency f can be obtained:

[0063]

[0064] Furthermore, let Δε = ε mix - ε0 (where ε mix is the dielectric constant of the air and pulverized coal mixture after perturbation, and ε0 is the dielectric constant of the mixture before perturbation), then the above formula can be simplified to:

[0065]

[0066] In the formula, C is a coefficient to be determined, calibrated through experiments, f is the measurement frequency, and f0 is the cavity resonance frequency.

[0067] Use the mixture dielectric constant model (Formula 3) to calculate the pulverized coal particle concentration: ε mixis the mixed dielectric constant, which is related to the dielectric constants of air and measured particles and the ratio of air to coal powder. The dielectric constants of air and coal powder are known, so the mixed dielectric constant model can be used to calculate the coal powder concentration m c calculate.

[0068]

[0069] In the formula, ε c and ε a is the dielectric constant of the medium obtained in advance, which is a universal constant and can be taken as 2.7 and 1 as typical values.

[0070] Finally, the relationship between the measured resonant frequency and the concentration to be measured is derived as formula (4):

[0071]

[0072] In the formula, f r and f ro They are respectively the real-time measured resonance frequency and the cavity resonance frequency measured in advance; f r and f ro The difference is the resonant frequency offset, and the prototype in the relationship is a*m c 3 +b*m c 2 +c*m c +d, where a / b / c / d are fitted to obtain the actual values, which is formula (4).

[0073] As for the relationship between the resonant frequency offset and the coal powder concentration, the simulation curve is obtained with the coal powder concentration of 20% to 80% as the variable. Figure 7 As shown in the figure, the S11 curves from right to left are black 20% to yellow 80%, and the horizontal axis corresponding to the valley value is the resonance frequency. It can be seen that with the increase of concentration, the resonance frequency decreases monotonically. When the concentration is 50%, the S11 and S21 curves measured by the simulation experiment of the flow field and electromagnetic field coupling are as follows Figure 8 shown.

[0074] According to the simulation results, the sensor of this embodiment is significantly improved compared with the existing measurement methods. This is due to the principle of the resonant cavity. The resonant cavity produces high-frequency microwave resonance, has high energy concentration, and is sensitive to coal powder. It is also due to the fact that the inner conductor column can guide the electromagnetic field into the pipeline. It is difficult to perform high-precision measurements on pipelines of more than 500 mm in the prior art. This embodiment adopts a quasi-non-invasive design, does not destroy the internal coal powder flow field, and the measurement results are accurate. In addition, the model in this embodiment adopts the medium perturbation method. After derivation, the formula (2) and formula (3) are combined to obtain the model form. The model can be obtained by nonlinear fitting of direct empirical formulas. The data comes from simulation and experimental mutual verification.

[0075] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A device for measuring the concentration of pulverized coal particle flow, characterized in that, The measurement device includes: A sensor structure, A coaxial cavity formed on the sensor structure. The lower end of the coaxial cavity is open and sealed with a dust-proof cover. An inner waveguide post is coaxially arranged in the coaxial cavity. Two oppositely arranged feed holes for installing feed loop antennas are provided on the side surface of the coaxial cavity; A base for welding on the fluid pipeline to be measured. The lower end of the coaxial cavity is welded to the base; A stray cavity formed on the sensor structure. One end of the stray cavity forms a hinge platform for mounting and connecting with the base, and the other end can be embedded into the fluid pipeline through a through hole opened on the fluid pipeline. The bottom end of the inner waveguide post can pass through the dust-proof cover and the stray cavity to be flush with the inner wall of the fluid pipeline.

2. The pulverized coal particle flow concentration measuring device according to claim 1, wherein The dust-proof cover is adhesively bonded to the lower end of the coaxial cavity using an organic glass dust-proof cover.

3. The pulverized coal particle flow concentration measuring device according to claim 1, characterized in that, A bolt hole is provided at the center of the inner diameter of the upper end of the coaxial cavity, and the inner waveguide post is installed at the bolt hole by threading.

4. A pulverized coal particle flow concentration measuring device according to claim 1, characterized in that, The bottom end of the base is arc-shaped for fitting with the outer wall of the fluid pipeline.

5. The pulverized coal particle flow concentration measuring device according to claim 1, characterized in that, One end of the stray cavity embedded in the fluid pipeline is cut into an arc shape to be flush with the inner wall curved surface of the fluid pipeline, and the outer diameter of the stray cavity is the same as the aperture of the through hole opened on the fluid pipeline.

6. The pulverized coal particle flow concentration measuring device according to claim 1, wherein The inner diameter of the inner waveguide post is not greater than a preset value, and the preset value is positively correlated with the inner diameter of the fluid pipeline to be measured.

7. A pulverized coal particle flow concentration measuring device according to claim 1, characterized in that, The inner diameter of the antenna loop of the feed loop antenna is not greater than the corresponding preset value; the microwave signal is fed into through the feed loop antenna, and the microwave is at 550 - 650 MHz and is excited in a swept-frequency working mode.

8. A method for measuring the concentration of pulverized coal particle flow, characterized in that, It is realized by using the pulverized coal particle flow concentration measurement device according to any one of claims 1 - 7. The measurement method includes: Arranging the pulverized coal particle flow concentration measurement device on the fluid pipeline to be measured; Connecting one feed loop antenna on the side surface of the coaxial cavity to a microwave signal and feeding it into the coaxial cavity to generate resonance; Under the action of the open lower end of the coaxial cavity and the inner waveguide post, part of the electromagnetic field in the coaxial cavity is scattered into the fluid pipeline of the pulverized coal particles through the stray cavity; When the pulverized coal fluid passes through the electromagnetic field scattered into the fluid pipeline, it disturbs the electromagnetic field and changes the resonance frequency; The disturbed microwave signal is received by the other feed loop antenna on the side surface of the coaxial cavity, and the signal processing circuit determines the resonance frequency offset before and after the disturbance; Based on the pre-fitted relationship between the resonance frequency offset and the pulverized coal concentration, the pulverized coal concentration is determined according to the resonance frequency offset.

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