Pulverized coal particle size distribution dynamic monitoring and burn-off rate optimizing method

Abstract

The invention relates to a pulverized coal particle size distribution dynamic monitoring and burn-off rate optimizing method. The pulverized coal particle size distribution dynamic monitoring method comprises the following steps: acquiring a voltage signal collected based on an electrostatic coupling acoustic emission technology; the voltage signals comprise electrostatic signals and acoustic emission signals, monitored in real time, of different pipelines; the pulverized coal flow velocity is calculated according to the electrostatic signals of the two adjacent groups of electrodes; on the basis of the linear relation between the voltage value and the pulverized coal impact momentum, the pulverized coal particle size distribution and the pulverized coal fineness are obtained in combination with the acoustic emission signal and the pulverized coal flow speed; and on the basis of the acoustic emission signal, the pulverized coal concentration is obtained through the positive correlation between the pulverized coal concentration and the electrostatic signal. By adopting the method, the real-time performance and the accuracy of pulverized coal monitoring can be improved, and the stability and the high efficiency of the combustion process can be guaranteed.

Description

Technical Field

[0001] The invention belongs to the field of detection and automation technology, and in particular relates to a method for dynamically monitoring coal powder particle size distribution and optimizing burnout rate. Background Art

[0002] With the development of the energy industry and industrial automation technology, coal powder particle size distribution monitoring technology has emerged. By obtaining the number or mass proportion of particles of different particle sizes in coal powder, it can effectively improve combustion efficiency, reduce energy consumption, and ensure stable operation of equipment.

[0003] In traditional technology, the particle size distribution of coal powder is monitored by a laser particle size analyzer. The laser particle size analyzer uses the principle of laser scattering to irradiate a laser beam onto coal powder particles to generate scattered light. By detecting the angle and intensity distribution of the scattered light, the particle size distribution of the coal powder is calculated through a complex algorithm.

[0004] However, because the sampling and measurement processes in this method aren't performed in real time, the resulting coal pulverized coal particle size distribution data is subject to significant time delays, failing to accurately reflect changes in coal pulverized coal particle size during production. This delay prevents operators from adjusting equipment parameters in a timely manner when production conditions fluctuate frequently, impacting combustion efficiency and production stability. Summary of the Invention

[0005] Based on this, it is necessary to provide a method for dynamic monitoring of coal powder particle size distribution and burnout rate optimization that can dynamically monitor the particle size distribution of coal powder in real time to address the above technical problems.

[0006] In a first aspect, the present application provides a method for dynamically monitoring the particle size distribution of pulverized coal, comprising:

[0007] Obtain voltage signals collected based on electrostatic coupled acoustic emission technology; the voltage signals include electrostatic signals and acoustic emission signals of different pipelines monitored in real time;

[0008] The coal powder flow velocity is calculated based on the electrostatic signals of two adjacent groups of electrodes;

[0009] Based on the linear relationship between voltage value and coal impact momentum, combined with acoustic emission signal and coal flow velocity, the coal particle size distribution and coal fineness are obtained.

[0010] Based on the acoustic emission signal, the coal powder concentration is obtained through the positive correlation between the coal powder concentration and the electrostatic signal.

[0011] In one embodiment, the pulverized coal flow velocity is calculated based on the electrostatic signals of two adjacent groups of electrodes, including:

[0012] Obtaining the timestamps of the electrostatic signals of two adjacent groups of electrodes;

[0013] The time difference is calculated based on the timestamps of the electrostatic signals of two adjacent groups of electrodes;

[0014] Based on the fixed distance between two adjacent sets of electrodes, the pulverized coal flow velocity is calculated according to the time difference.

[0015] In one embodiment, based on the linear relationship between the voltage value and the impact momentum of the pulverized coal, combined with the acoustic emission signal and the flow velocity of the pulverized coal, the pulverized coal particle size distribution and the pulverized coal fineness are obtained, including:

[0016] A calibration curve is established based on the linear relationship between voltage value and coal powder impact momentum; the calibration curve is used to reflect the linear relationship between voltage, impact momentum and particle mass;

[0017] According to the calibration curve, the acoustic emission signal is converted into the mass of a single coal powder particle;

[0018] The particle size of the corresponding coal powder particles is calculated based on the mass of a single coal powder particle;

[0019] The particle size distribution of the plurality of pulverized coal particles is obtained by calculating the mass of the individual pulverized coal particles and the corresponding particle size based on a statistical method;

[0020] The fineness of the coal powder is obtained based on the particle size distribution.

[0021] In one embodiment, the particle size of the pulverized coal particles is obtained by the following formula:

[0022]

[0023] Where m is the mass of a single pulverized coal particle; ρ is the density of pulverized coal; and r is the particle size of the pulverized coal particle.

[0024] In one embodiment, the coal powder concentration is obtained based on the acoustic emission signal and the positive correlation between the coal powder concentration and the electrostatic signal, including:

[0025] Convert electrostatic signals into electromotive force signals;

[0026] The pulverized coal concentration ratio between different pipelines is calculated through the electromotive force signals of different pipelines;

[0027] The pulverized coal concentration ratio is corrected based on the pulverized coal mass flow rate obtained based on the acoustic emission signal to obtain the pulverized coal concentration.

[0028] In one embodiment, the coal powder mass flow rate is obtained by the following method:

[0029] Calculate the mass and flow rate of pulverized coal passing through a set interface in a pipeline per unit time based on the mass of a single pulverized coal particle, the particle size, the particle size distribution, and the flow velocity of the pulverized coal;

[0030] The pulverized coal mass flow rate is obtained based on the pulverized coal mass and the pulverized coal flow rate.

[0031] In a second aspect, the present application also provides a method for optimizing the burnout rate of pulverized coal, comprising:

[0032] Obtain the combustible content of fly ash and the real-time coal powder fineness and coal powder flow rate of each pipeline; the coal powder fineness and coal powder flow rate are obtained based on the dynamic monitoring method of coal powder particle size distribution;

[0033] The optimal fineness range of pulverized coal is obtained according to the combustible content of fly ash and the fineness of pulverized coal;

[0034] Adjust the coal mill operating parameters according to the coal fineness, coal flow rate and the optimal fineness range of the coal; the coal mill operating parameters include the shrinkage parameters, coal separation ratio parameters, separator speed parameters and hydraulic loading force adjustment parameters;

[0035] Obtain the real-time parameters of the coal mill after it operates according to the coal mill operating parameters; the real-time parameters include coal powder fineness, coal powder flow rate, fly ash combustible content and air-coal ratio;

[0036] The operating parameters of the burner are adjusted according to real-time parameters; the operating parameters include the burner wind speed, the burner ignition distance and the burner nozzle temperature.

[0037] In one embodiment, adjusting the coal mill operating parameters according to the coal pulverized fineness, coal pulverized flow velocity, and the optimal coal pulverized fineness range includes:

[0038] Based on the minimum pulverized coal rate and pipeline coordinated control strategy, the shrinkage parameters and coal distribution ratio parameters of each pipeline are obtained according to the pulverized coal flow velocity of each pipeline; the pipeline coordinated control strategy includes the target flow rate range and deviation tolerance;

[0039] According to the coal powder fineness and the optimal coal powder fineness range, the separator speed parameter is obtained;

[0040] According to the dynamic change of coal powder fineness, the adjustment parameters of the hydraulic loading force are obtained.

[0041] In one embodiment, adjusting the operating parameters of the burner according to the real-time parameters includes:

[0042] Adjust the burner air speed according to the coal powder fineness and coal powder flow speed;

[0043] Adjust the burner ignition distance according to the pulverized coal flow rate and air-coal ratio;

[0044] Adjust the burner nozzle temperature according to the combustible content of fly ash, coal powder fineness and air-coal ratio.

[0045] In a third aspect, the present application further provides a device for dynamically monitoring the particle size distribution of pulverized coal, comprising:

[0046] A data acquisition module is used to obtain voltage signals collected based on electrostatic coupled acoustic emission technology;

[0047] A flow rate calculation module is used to calculate the flow rate of pulverized coal based on the electrostatic signals of two adjacent groups of electrodes;

[0048] The particle size calculation module is used to obtain the particle size distribution and fineness of the pulverized coal based on the linear relationship between the voltage value and the impact momentum of the pulverized coal, combined with the acoustic emission signal and the flow velocity of the pulverized coal;

[0049] The concentration calculation module is used to obtain the coal powder concentration based on the acoustic emission signal and the positive correlation between the coal powder concentration and the electrostatic signal.

[0050] This method for dynamically monitoring pulverized coal particle size distribution and optimizing burnout rate utilizes voltage signals collected using electrostatically coupled acoustic emission technology to monitor the electrostatic and acoustic emission signals of different pipelines in real time, providing a timely reflection of the flow state of pulverized coal within the pipelines. By calculating the pulverized coal flow velocity using the electrostatic signals from two adjacent sets of electrodes and combining them with acoustic emission signals to determine the pulverized coal particle size distribution, fineness, and concentration, key parameters of the pulverized coal can be accurately determined. This allows operators to understand the dynamic changes in pulverized coal in real time, providing an accurate basis for subsequent equipment adjustments and combustion optimization. Compared to traditional monitoring methods, this method significantly improves the real-time and accuracy of monitoring, helping to ensure the stability and efficiency of the combustion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0052] Figure 1 Schematic diagram of the process of the method for dynamic monitoring of coal powder particle size distribution of the present invention;

[0053] Figure 2 Schematic diagram of the step-by-step process of step S103;

[0054] Figure 3 Schematic diagram of the process of the method for optimizing the burnout rate of pulverized coal according to the present invention;

[0055] Figure 4 This is a structural diagram of the composition of the method for dynamically monitoring the particle size distribution of pulverized coal according to the present invention. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0057] In one embodiment, Figure 1 As shown, a method for dynamic monitoring of coal powder particle size distribution is provided. This embodiment uses the method applied to a terminal as an example for illustration. It is understandable that the method can also be applied to a server, or to a system including a terminal and a server, and implemented through interaction between the terminal and the server. In this embodiment, the method includes the following steps:

[0058] S101. Acquire voltage signals collected based on electrostatic coupled acoustic emission technology; the voltage signals include electrostatic signals and acoustic emission signals of different pipelines monitored in real time.

[0059] A sensor based on electrostatically coupled acoustic emission technology is used to acquire voltage signals. Schematically, an electrostatically coupled acoustic wave sensor is used to collect voltage signals. When electrostatically charged coal particles pass through the electrode group of the electrostatic sensor, the coal pulverized particles rub against the electrode group, generating static charge. The electrostatic sensor senses the static charge and generates an AC charge. Furthermore, a signal conditioning circuit converts the AC charge into an AC voltage signal, i.e., an electrostatic signal. The acoustic emission sensor includes a waveguide rod. The coal particles strike the waveguide rod, generating mechanical vibration waves. The waveguide rod transmits these vibration waves to the acoustic wave transmission sensor, which converts the mechanical vibration waves into a voltage signal, i.e., an acoustic emission signal.

[0060] For example, an electrostatically coupled acoustic wave sensor is installed on each straight section of the pipeline after the air-powder mixture at the mill outlet. During the actual operation of the power plant, when the coal powder flows in the pipeline, the electrode group of the electrostatic sensor senses the static charge generated by the friction of the coal powder particles. Specifically, at a specific moment, the AC charge generated by a group of electrodes is converted by the signal conditioning circuit to obtain an AC voltage signal with an amplitude of 200mV, and the AC signal is determined to be an electrostatic signal; at the same time, the coal powder particles hit the acoustic emission waveguide rod, and the acoustic wave conduction sensor converts the mechanical vibration into a voltage signal, obtaining an acoustic emission signal with an amplitude of 150mV.

[0061] S102. Calculate the flow velocity of the pulverized coal based on the electrostatic signals of two adjacent groups of electrodes.

[0062] Schematically, the electrical signal of the pulverized coal flow is captured and recorded when it passes through each set of electrodes. By analyzing the time difference between the AC voltage signals of two adjacent sets of electrodes, that is, the time it takes for the pulverized coal to flow through the two sets of electrodes, and since the distance between the electrodes is fixed and known, the flow velocity of the pulverized coal is calculated according to the distance-time formula.

[0063] S103. Based on the linear relationship between the voltage value and the impact momentum of the coal powder, combined with the acoustic emission signal and the flow velocity of the coal powder, the coal powder particle size distribution and the coal powder fineness are obtained.

[0064] When coal dust strikes an acoustic emission waveguide, it generates an acoustic emission signal, the voltage of which is linearly related to the momentum of the impacting coal dust. Schematically, through calibration, the voltage and momentum values can be mapped one-to-one, yielding the mass of the particle, and thus its diameter. Furthermore, since the mass and size information of thousands of particles can be acquired per second, statistical methods can be used to classify particles of different sizes into different size ranges, thereby determining the particle size distribution of the coal dust. Based on this particle size distribution, the percentage of the mass of coal dust particles of a certain size relative to the total coal dust can be calculated, thereby determining the fineness of the coal dust.

[0065] S104 : Based on the acoustic emission signal, the coal powder concentration is obtained through the positive correlation between the coal powder concentration and the electrostatic signal.

[0066] The concentration of pulverized coal is proportional to the static electricity it generates. The electrostatic sensor converts the measured static electricity signal into an electromotive force signal. By comparing the electromotive force signals of different pipelines and displaying them as percentages, a preliminary calculation of the pulverized coal concentration ratio between pipelines can be made. Furthermore, the static electricity signal generated by pulverized coal is affected by the water vapor concentration and ash content within the pulverized coal pipe. Therefore, the pulverized coal mass flow rate signal, measured using acoustic emission signals, is used to correct this signal. Specifically, the acoustic emission signal reflects the impact of pulverized coal particles, which can be used to infer the pulverized coal mass flow rate. The concentration ratio derived from the electrostatic signal is adjusted based on the mass flow rate, resulting in a more accurate pulverized coal concentration.

[0067] In the above-mentioned dynamic monitoring method for pulverized coal particle size distribution, electrostatically coupled acoustic wave sensors are used to collect electrostatic and acoustic emission signals from different pipelines, providing real-time information on the flow of pulverized coal within each pipeline. Sensors located on each straight section of the pipeline continuously operate, promptly detecting changes in the pulverized coal flow state and enabling comprehensive monitoring of the entire pulverized coal conveying system. The electrostatic and acoustic emission sensors work together to perceive pulverized coal characteristics from different angles. Their combination yields a richer picture of pulverized coal flow characteristics, providing multi-dimensional data support for the subsequent accurate calculation of pulverized coal flow velocity, particle size distribution, and concentration. Calculating pulverized coal flow velocity using electrostatic signals from two adjacent sets of electrodes eliminates direct contact with the pulverized coal, preventing interference with the flow and ensuring measurement accuracy. Calculating pulverized coal particle size distribution and fineness based on the linear relationship between voltage and pulverized coal impact momentum accurately reflects the particle composition of the pulverized coal. This is crucial for optimizing the combustion process. Appropriate pulverized coal fineness ensures thorough mixing of the pulverized coal with air, improving combustion efficiency, reducing the combustible content of fly ash, and lowering fuel consumption. Accurate pulverized coal particle size distribution and fineness data provide a scientific basis for adjusting parameters of equipment such as coal mills. By utilizing the positive correlation between coal powder concentration and electrostatic signal and combining it with the coal powder mass flow signal measured by acoustic emission signal for correction, the interference of factors such as water vapor concentration and ash content in the powder pipe on the electrostatic method of measuring coal powder concentration is effectively overcome, and the measurement accuracy of coal powder concentration is significantly improved.

[0068] In one embodiment, the pulverized coal flow velocity is calculated based on the electrostatic signals of two adjacent groups of electrodes, including:

[0069] S21. Obtaining timestamps of electrostatic signals of two adjacent groups of electrodes.

[0070] When the pulverized coal particles generate an AC charge signal through the electrode group, the precise time when the signal is generated, i.e. the timestamp, is recorded synchronously.

[0071] S22. Calculate a time difference based on the timestamps of the electrostatic signals of two adjacent groups of electrodes.

[0072] After obtaining the time stamps of the electrostatic signals of two adjacent groups of electrodes, the time difference experienced by the coal powder particles moving from the first group of electrodes to the second group of electrodes is obtained by subtracting the two time stamps.

[0073] S23. Based on the fixed distance between two adjacent groups of electrodes, the pulverized coal flow velocity is calculated according to the time difference.

[0074] According to the speed formula The pulverized coal flow velocity is calculated, where v represents the pulverized coal flow velocity, s represents the fixed distance between two adjacent sets of electrodes, and t represents the time difference.

[0075] In one embodiment, based on the linear relationship between the voltage value and the impact momentum of the pulverized coal, combined with the acoustic emission signal and the flow velocity of the pulverized coal, the pulverized coal particle size distribution and the pulverized coal fineness are obtained, including:

[0076] S201. Establish a calibration curve based on the linear relationship between the voltage value and the impact momentum of the coal powder; the calibration curve is used to reflect the linear relationship between the voltage, the impact momentum and the particle mass.

[0077] Schematically, using a standard coal powder sample, in a laboratory environment, the coal powder is controlled to impact the acoustic emission waveguide rod at different speeds, generating acoustic emission signals of different intensities, which are converted into corresponding voltage values. At the same time, the momentum of each impact can be obtained through theoretical calculation or other high-precision measurement methods, and according to the formula The corresponding particle mass is calculated. Furthermore, a scatter plot is drawn with the voltage value as the horizontal axis and the impact momentum and particle mass as the vertical axis. A calibration curve can be obtained by linear regression analysis and fitting to determine the quantitative linear relationship between the voltage value, impact momentum, and particle mass.

[0078] For example, a batch of standard coal powder samples with a known density of ρ = 1000 kg / m3 were selected, and coal powders of different particle size ranges were screened. In a laboratory wind tunnel device, according to the particle mass formula The particle mass corresponding to each particle size of coal powder was calculated. Furthermore, the coal powder was allowed to impact the acoustic emission waveguide at different speeds, such as 10 m / s, 20 m / s, and 30 m / s. At a speed of 10 m / s, the voltage converted from the acoustic emission signal was U1 = 100 mV. Using the momentum calculation formula p = mv, where m is the mass of the coal powder particle and v is the flow velocity, the impact momentum p1 and particle mass m1 were calculated. After repeating the experiment multiple times and acquiring multiple sets of data, a scatter plot was plotted with voltage U as the horizontal axis and impact momentum p and particle mass m as the vertical axis. Linear regression analysis revealed the calibration curve equation: p = 0.05U + 1 for the impact momentum and voltage relationship, and m = 0.001U + 0.02 for the particle mass and voltage relationship, derived from p = mv.

[0079] S202. Convert the acoustic emission signal into the mass of a single pulverized coal particle according to the calibration curve.

[0080] In schematic form, the voltage signal value converted from the acoustic emission signal generated by the coal powder particles hitting the waveguide rod received by the acoustic emission sensor is substituted into the established calibration curve equation to obtain the corresponding single coal powder particle mass.

[0081] S203. Calculate the particle size of the corresponding pulverized coal particles based on the mass of the single pulverized coal particles.

[0082] Indicatively, according to the formula When the mass m of a single pulverized coal particle is known, the particle size r of the corresponding pulverized coal particle is obtained, where the pulverized coal density ρ is basically a fixed constant.

[0083] S204: Count the mass of individual coal powder particles and the corresponding particle sizes of the plurality of coal powder particles based on a statistical method to obtain a particle size distribution.

[0084] Schematically, over a period of time, the acoustic emission sensor continuously receives signals generated by the impact of a large number of pulverized coal particles. This acoustic emission signal is then converted into the mass of a single pulverized coal particle, and the corresponding particle size is calculated. Furthermore, using statistical grouping methods, the particle size is divided into multiple intervals, such as 0-20μm, 20-40μm, and 40-60μm. The proportion of the number or mass of pulverized coal particles in each interval to the total number or mass of particles is calculated to determine the particle size distribution of the pulverized coal particles.

[0085] For example, within a certain time period, the acoustic emission sensor receives 1,000 impact signals from coal dust particles. After calculating the particle size of each particle, the data is grouped and counted. The results show that 200 particles fall within the 0-20 μm range, accounting for 20% of the total; 350 fall within the 20-40 μm range, accounting for 35%; 300 fall within the 40-60 μm range, accounting for 30%; and 150 exceed 60 μm, accounting for 15%. This provides the particle size distribution of the coal dust batch.

[0086] S205. Obtain the fineness of the pulverized coal according to the particle size distribution.

[0087] For example, the fineness of coal powder can be expressed by the sieve residue of a specific sieve, R 90 It indicates the percentage of the 90μm sieve residue of pulverized coal to the total pulverized coal mass. According to the particle size distribution data obtained above, the mass of pulverized coal particles with a particle size greater than 90μm is calculated as the proportion of the total pulverized coal mass. This proportion is the value of pulverized coal fineness R90. Specifically, the total pulverized coal mass is M, and the mass of pulverized coal particles with a particle size greater than 90μm is m >90 , then the fineness of coal powder If we calculate m >90 Accounting for 12% of M, the fineness of the coal powder R 90 It is 12%.

[0088] In one embodiment, the particle size of the pulverized coal particles is obtained by the following formula:

[0089]

[0090] Where m is the mass of a single pulverized coal particle; ρ is the density of pulverized coal; and r is the particle size of the pulverized coal particle.

[0091] In one embodiment, the coal powder concentration is obtained based on the acoustic emission signal and the positive correlation between the coal powder concentration and the electrostatic signal, including:

[0092] S31. Convert the electrostatic signal into an electromotive force signal.

[0093] As shown schematically, when pulverized coal flows, the electrostatic sensor's electrode assembly senses the static charge generated by the friction of the pulverized coal particles, generating an AC charge signal. The signal conditioning circuit processes this AC charge signal through amplification, filtering, and conversion. Amplification enhances the weak charge signal to a level sufficient for subsequent processing; filtering removes noise and interference to ensure signal purity; and conversion converts the AC charge signal into an electromotive force signal.

[0094] S32. Calculate the pulverized coal concentration ratio between different pipelines through the electromotive force signals of different pipelines.

[0095] There's a direct proportional relationship between pulverized coal concentration and the amount of static electricity generated. When pulverized coal flows through different pipes, the concentrations within each pipe vary, and the static charge sensed by the electrostatic sensor also varies. This results in variations in the electromotive force signal generated through signal conversion. By comparing the amplitudes of the electromotive force signals across different pipes, we can preliminarily calculate the pulverized coal concentration ratios between them.

[0096] For example, the power plant has three pulverized coal pipelines, A, B, and C. Electrostatic sensors measure the electromotive force signal amplitudes of each of these pipelines: EA = 300 mV for pipeline A, EB = 200 mV for pipeline B, and EC = 150 mV for pipeline C. Using pipeline A as a reference, the calculated pulverized coal concentration ratio in pipelines B to A is EA:EB = 300:200 ≈ 0.67, meaning the pulverized coal concentration in pipeline B is approximately 67% of that in pipeline A. The pulverized coal concentration ratio in pipeline C to pipeline A is EA:EC = 300:150 = 0.5, meaning the pulverized coal concentration in pipeline C is 50% of that in pipeline A.

[0097] S33. Correct the pulverized coal concentration ratio based on the pulverized coal mass flow rate obtained from the acoustic emission signal to obtain the pulverized coal concentration.

[0098] While the electrostatic signal can roughly reflect the proportional relationship of pulverized coal concentration, it is affected by factors such as water vapor concentration and ash content within the pulverized coal pipe, resulting in inaccurate measurement results. The acoustic emission signal, however, is related to the impact of pulverized coal particles. By analyzing the acoustic emission signal, the pulverized coal mass flow rate can be determined. Using the pulverized coal mass flow rate signal measured by the acoustic emission signal to correct the concentration ratio derived from the electrostatic signal can eliminate interference from factors such as water vapor concentration and ash content, resulting in a more accurate determination of the pulverized coal concentration in each pipeline.

[0099] For example, taking the three pulverized coal pipelines of the power plant as an example, the pulverized coal mass flow rate of pipeline A is Q measured by acoustic emission signal. A =5kg / s, the coal powder mass flow rate in pipeline B is Q B =3kg / s, the coal powder mass flow rate in pipeline C is Q C =2kg / s. Based on the electrostatic signal, the coal powder concentration ratio of pipeline B to pipeline A is 0.67, and the coal powder concentration ratio of pipeline C to pipeline A is 0.5. Taking into account the mass flow rate obtained by the acoustic emission signal, the ratio is corrected. Assuming that the correction factor is the ratio of mass flow rates, the coal powder concentration in pipeline B after correction is Pulverized coal concentration C in pipeline A A ,Right now The pulverized coal concentration in pipeline C is

[0100] In one embodiment, the coal powder mass flow rate is obtained by the following method:

[0101] S41. Calculate the mass and flow rate of the pulverized coal passing through the set interface of the pipeline per unit time based on the mass of a single pulverized coal particle, the particle size of the pulverized coal particle, the particle size distribution, and the flow velocity of the pulverized coal.

[0102] Schematically, given the particle size distribution, the percentage of pulverized coal particles within different size ranges is determined. Furthermore, the number of pulverized coal particles per unit time that pass through the defined interface of the pipeline in each size range is calculated, taking into account the cross-sectional area of the pipeline and the flow rate of the pulverized coal. For each size range, given the mass of a single pulverized coal particle, the number of particles within that range is multiplied by the mass of the single particle to obtain the mass of the pulverized coal in that range. By summing the masses of the pulverized coal for all size ranges, the total mass of pulverized coal that passes through the defined interface of the pipeline per unit time is calculated.

[0103] Pulverized coal flow rate refers to the volume of pulverized coal that passes through a specific section of a pipeline per unit time. The volume of pulverized coal flowing per unit time, or the pulverized coal flow rate, can be calculated based on the pulverized coal flow velocity and the cross-sectional area of the pipeline.

[0104] S42. Obtain the pulverized coal mass flow rate according to the pulverized coal mass and the pulverized coal flow rate.

[0105] Pulverized coal mass flow is defined as the mass and flow rate of pulverized coal passing through a specific pipe section per unit time. Given the mass and flow rate of pulverized coal passing through a given pipe section per unit time, the mass flow rate can be calculated by integrating them.

[0106] In one embodiment, Figure 3As shown, a method for optimizing the burnout rate of pulverized coal is provided. This embodiment uses the same application environment as the method for dynamic monitoring of pulverized coal particle size distribution as an example, and includes the following steps:

[0107] S301. Obtain the combustible content of fly ash and the real-time coal powder fineness and coal powder flow velocity of each pipeline; wherein the coal powder fineness and coal powder flow velocity are obtained based on a dynamic monitoring method for coal powder particle size distribution.

[0108] Using electrostatically coupled acoustic emission technology to dynamically monitor the pulverized coal particle size distribution, we can determine the flow velocity and fineness of the pulverized coal. For example, a fly ash combustible content monitoring device can be installed at the boiler fly ash discharge point to measure the unburned carbon content in the fly ash in real time, providing real-time information on the combustible content, pulverized coal fineness, and flow velocity of the fly ash.

[0109] S302. Obtain an optimal fineness range of the pulverized coal according to the combustible content of the fly ash and the fineness of the pulverized coal.

[0110] The combustible content of fly ash reflects the degree of burnout during the pulverized coal combustion process, and pulverized coal fineness affects combustion performance. By collecting a large amount of data on the combustible content of fly ash at different pulverized coal finenesses, a relationship model was established. A high combustible content in fly ash indicates incomplete pulverized coal combustion, possibly due to the pulverized coal being too coarse and requiring refinement. A low combustible content in fly ash, but high pulverizing energy consumption, suggests the pulverized coal is too fine and requires an appropriate increase in particle size. Using this model, combined with factors such as energy consumption and efficiency in actual production, the optimal fineness range (i.e., the optimal fineness range) was determined to maximize the pulverized coal burnout rate and minimize overall costs under different operating conditions.

[0111] S303, adjusting the coal mill operating parameters according to the coal powder fineness, coal powder flow velocity and the optimal fineness range of the coal powder; the coal mill operating parameters include shrinkage parameters, coal separation ratio parameters, separator speed parameters and hydraulic loading force adjustment parameters.

[0112] Based on the pulverized coal flow rate, pulverized coal fineness, and the optimal pulverized coal fineness range, adjustments were made to the pulverizer's dynamic separator speed, air-to-coal ratio curve, and hydraulic loading force, exploring methods for achieving dynamic equilibrium conditions for the pulverizer's output, fineness, and power consumption. Specifically, by obtaining the pulverized coal flow rate and fineness at specific operating parameters, a pulverized coal flow rate, fineness, and energy consumption balance model was established. The pulverized coal operating parameters were automatically or manually adjusted based on dynamic data, achieving the lowest energy consumption while maintaining the economic fineness of the pulverized coal and safe operation of the pulverizer under dynamic equilibrium conditions.

[0113] S304, obtaining real-time parameters of the coal mill after it operates according to the coal mill operating parameters; the real-time parameters include coal powder fineness, coal powder flow velocity, fly ash combustible content and air-coal ratio.

[0114] The real-time parameters of the coal mill after it operates according to the coal mill operating parameters are obtained again to ensure that the working parameters of the burner are further guided under the optimal working effect of the coal mill.

[0115] S305. Adjust the operating parameters of the burner according to the real-time parameters; the operating parameters include the burner wind speed, the burner ignition distance and the burner nozzle temperature.

[0116] The burner was further modified to allow the burner and pulverizer to work together to achieve optimal burnout.

[0117] In one embodiment, adjusting the coal mill operating parameters according to the coal pulverized fineness, coal pulverized flow velocity, and the optimal coal pulverized fineness range includes:

[0118] S51. Based on the minimum pulverized coal rate and pipeline coordinated control strategy, the shrinkage parameters and coal distribution ratio parameters of each pipeline are obtained according to the pulverized coal flow velocity of each pipeline; the pipeline coordinated control strategy includes a target flow rate range and a deviation tolerance.

[0119] A minimum pulverized coal settling velocity test is conducted based on the pulverized coal flow velocity to obtain the minimum pulverized coal flow velocity of each pipeline. Furthermore, a target flow velocity range and deviation tolerance are set according to the pulverized coal flow velocity of each pipeline to ensure that the pulverized coal flow velocity of each pipeline is consistent.

[0120] For example, uneven pulverized coal flow can affect combustion. Based on pulverized coal flow rate monitoring data, when the pulverized coal flow rate in some pipelines is low, the shrinkage holes in those pipelines are reduced, the air velocity is increased, and the pulverized coal flow rate is increased. When the pulverized coal flow rate in some pipelines is high, the shrinkage holes are appropriately enlarged and the air velocity is reduced to achieve a uniform pulverized coal flow rate across all pipelines. The coal distribution ratio is adjusted based on the pulverized coal fineness and flow rate in each pipeline to ensure that each burner receives the appropriate pulverized coal quantity and fineness, thereby ensuring uniform combustion.

[0121] S52. Obtain a separator rotation speed parameter according to the pulverized coal fineness and the optimal pulverized coal fineness range.

[0122] If the coal powder fineness is greater than the upper limit of the optimal fineness range, that is, the coal powder is too coarse, increase the separator speed to allow finer coal powder to pass through the separator, and increase the amount of coarse coal powder remaining in the pulverizer for further grinding, thereby refining the coal powder; if the coal powder fineness is less than the lower limit of the optimal fineness range, that is, the coal powder is too fine, reduce the separator speed to reduce the production of excessively fine coal powder.

[0123] S53. According to the dynamic change of the coal powder fineness, the adjustment parameters of the hydraulic loading force are obtained.

[0124] When the coal powder is too coarse, increase the hydraulic loading force of the pulverizer to improve the grinding capacity of the pulverizer and make the coal powder finer; when the coal powder is appropriate or too fine, reduce the loading force to reduce energy consumption and equipment wear.

[0125] In one embodiment, adjusting the operating parameters of the burner according to the real-time parameters includes:

[0126] S61. Adjust the burner wind speed according to the coal powder fineness and coal powder flow rate.

[0127] The fineness and flow rate of coal powder will affect the combustion effect. When the coal powder is too coarse, increase the primary wind speed to fully mix the coal powder with air and speed up the combustion speed. When the coal powder is too fine, reduce the primary wind speed to prevent the coal powder from being quickly carried out of the combustion area and ensure that the coal powder is fully burned in the burner.

[0128] S62. Adjust the burner ignition distance according to the coal powder flow rate and the air-coal ratio.

[0129] When the pulverized coal flow rate is too high, shorten the ignition distance to make the pulverized coal ignite and burn as soon as possible; when the pulverized coal flow rate is too low, extend the ignition distance to prevent the pulverized coal from igniting prematurely in the burner and damaging the burner.

[0130] S63. Adjust the burner nozzle temperature according to the combustible content of fly ash, coal powder fineness and air-coal ratio.

[0131] Adjust the nozzle temperature based on the combustible content of the fly ash and the air-to-coal ratio. A high combustible content in the fly ash indicates incomplete combustion, so the nozzle temperature should be appropriately increased to enhance combustion. When the air-to-coal ratio is inappropriate, adjust the nozzle temperature accordingly to ensure that the pulverized coal burns at the appropriate temperature.

[0132] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0133] Based on the same inventive concept, embodiments of the present application also provide a device for dynamically monitoring the distribution of pulverized coal particle size, for implementing the aforementioned method for dynamically monitoring the distribution of pulverized coal particle size. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more embodiments of the device for dynamically monitoring the distribution of pulverized coal particle size provided below can be found in the aforementioned definition of the method for dynamically monitoring the distribution of pulverized coal particle size, and will not be further elaborated here.

[0134] In an exemplary embodiment, Figure 4 As shown, a device for dynamic monitoring of coal powder particle size distribution is provided, comprising:

[0135] A data acquisition module is used to obtain voltage signals collected based on electrostatic coupled acoustic emission technology;

[0136] A flow rate calculation module is used to calculate the flow rate of pulverized coal based on the electrostatic signals of two adjacent groups of electrodes;

[0137] The particle size calculation module is used to obtain the particle size distribution and fineness of the pulverized coal based on the linear relationship between the voltage value and the impact momentum of the pulverized coal, combined with the acoustic emission signal and the flow velocity of the pulverized coal;

[0138] The concentration calculation module is used to obtain the coal powder concentration based on the acoustic emission signal and the positive correlation between the coal powder concentration and the electrostatic signal.

[0139] In one embodiment, the data acquisition module is further configured to acquire time stamps of electrostatic signals of two adjacent groups of electrodes;

[0140] The flow rate calculation module is also used to calculate the coal powder flow rate based on the time difference based on the fixed distance between two adjacent sets of electrodes;

[0141] The method further comprises a data module for calculating a time difference based on the time stamps of the electrostatic signals of two adjacent groups of electrodes.

[0142] In one embodiment, a mass calculation module is further included, which is used to convert the acoustic emission signal into the mass of a single coal powder particle according to a calibration curve.

[0143] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0144] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0145] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to the partial description of the method embodiments. The device embodiments described above are merely illustrative, wherein the components described as separate parts may or may not be physically separated, and the parts displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the disclosed solution. A person of ordinary skill in the art can understand and implement it without expending creative work.

[0146] The above-described embodiments merely represent several implementation methods of the embodiments of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the concept of the embodiments of the present application, and these modifications and improvements fall within the scope of protection of the embodiments of the present application.

Claims

1. A method for dynamic monitoring of coal powder particle size distribution, characterized in that: The method comprises: Acquiring voltage signals collected based on electrostatic coupled acoustic emission technology; the voltage signals include electrostatic signals and acoustic emission signals of different pipelines monitored in real time; Calculating the coal powder flow velocity based on the electrostatic signals of two adjacent groups of electrodes; Based on the linear relationship between the voltage value and the impact momentum of the coal powder, the coal powder particle size distribution and the coal powder fineness are obtained in combination with the acoustic emission signal and the coal powder flow velocity; Based on the acoustic emission signal, the coal powder concentration is obtained through the positive correlation between the coal powder concentration and the electrostatic signal.

2. The method according to claim 1, characterized in that The calculating the pulverized coal flow velocity according to the electrostatic signals of two adjacent groups of electrodes includes: Obtaining timestamps of the electrostatic signals of two adjacent groups of electrodes; Calculating a time difference based on the timestamps of the electrostatic signals of two adjacent groups of electrodes; Based on a fixed distance between two adjacent groups of electrodes, the pulverized coal flow velocity is calculated according to the time difference.

3. The method according to claim 1, characterized in that The method of obtaining the particle size distribution and fineness of the pulverized coal based on the linear relationship between the voltage value and the impact momentum of the pulverized coal and combining the acoustic emission signal and the flow velocity of the pulverized coal comprises: A calibration curve is established based on the linear relationship between the voltage value and the impact momentum of the coal powder; the calibration curve is used to reflect the linear relationship between the voltage, the impact momentum and the particle mass; converting the acoustic emission signal into the mass of a single coal powder particle according to the calibration curve; Calculating the particle size of the corresponding coal powder particles according to the mass of the single coal powder particles; Counting the mass and corresponding particle size of the single coal powder particles of the plurality of coal powder particles based on a statistical method to obtain a particle size distribution; The fineness of the coal powder is obtained according to the particle size distribution.

4. The method according to claim 3, wherein: The particle size of the pulverized coal particles is obtained by the following formula: Wherein, m is the mass of the single coal powder particle; ρ is the coal powder density; and r is the particle size of the coal powder particle.

5. The method according to claim 3, characterized in that The method of obtaining the pulverized coal concentration based on the acoustic emission signal and the positive correlation between the pulverized coal concentration and the electrostatic signal includes: converting the electrostatic signal into an electromotive force signal; Calculating the pulverized coal concentration ratio between different pipelines through the electromotive force signals of different pipelines; The pulverized coal concentration ratio is corrected based on the pulverized coal mass flow rate obtained from the acoustic emission signal to obtain the pulverized coal concentration.

6. The method according to claim 5, characterized in that The pulverized coal mass flow rate is obtained by the following method: Calculating the mass and flow rate of pulverized coal passing through a set interface of a pipeline per unit time based on the mass of the single pulverized coal particle, the particle size of the pulverized coal particle, the particle size distribution, and the flow velocity of the pulverized coal; The pulverized coal mass flow rate is obtained according to the pulverized coal mass and the pulverized coal flow rate.

7. A method for optimizing the burnout rate of pulverized coal, characterized in that: The method comprises: Obtaining the combustible content of fly ash and the real-time coal powder fineness and coal powder flow velocity of each pipeline; wherein the coal powder fineness and the coal powder flow velocity are obtained according to the method for dynamic monitoring of coal powder particle size distribution according to claim 1; Obtaining an optimal fineness range of the pulverized coal according to the combustible content of the fly ash and the fineness of the pulverized coal; adjusting the coal mill operating parameters according to the coal powder fineness, the coal powder flow rate and the optimal fineness range of the coal powder; the coal mill operating parameters include shrinkage parameters, coal separation ratio parameters, separator speed parameters and hydraulic loading force adjustment parameters; Acquiring real-time parameters of the coal mill after it operates according to the coal mill operating parameters; the real-time parameters include coal powder fineness, coal powder flow velocity, fly ash combustible content, and air-coal ratio; The operating parameters of the burner are adjusted according to the real-time parameters; the operating parameters include the burner wind speed, the burner ignition distance and the burner nozzle temperature.

8. The method according to claim 7, characterized in that The adjusting of the coal mill operating parameters according to the coal powder fineness, the coal powder flow velocity and the optimal fineness range of the coal powder includes: Based on the minimum pulverized coal rate and pipeline coordinated control strategy, the shrinkage parameters and coal distribution ratio parameters of each pipeline are obtained according to the pulverized coal flow velocity of each pipeline; the pipeline coordinated control strategy includes a target flow rate range and a deviation tolerance; Obtaining a separator rotation speed parameter according to the coal powder fineness and the optimal fineness range of the coal powder; According to the dynamic change of the coal powder fineness, the adjustment parameter of the hydraulic loading force is obtained.

9. The method according to claim 7, characterized in that The step of adjusting the operating parameters of the burner according to the real-time parameters includes: Adjusting the burner wind speed according to the coal powder fineness and the coal powder flow speed; adjusting the burner ignition distance according to the pulverized coal flow rate and the air-coal ratio; The nozzle temperature of the burner is adjusted according to the combustible content of the fly ash, the fineness of the coal powder and the air-coal ratio.

10. A device for dynamic monitoring of coal powder particle size distribution, characterized in that: The device comprises: A data acquisition module is used to obtain voltage signals collected based on electrostatic coupled acoustic emission technology; A flow rate calculation module, configured to calculate the flow rate of pulverized coal based on the electrostatic signals of two adjacent groups of electrodes; a particle size calculation module for obtaining the particle size distribution and fineness of the pulverized coal based on a linear relationship between the voltage value and the impact momentum of the pulverized coal, in combination with the acoustic emission signal and the flow velocity of the pulverized coal; The concentration calculation module is used to obtain the coal powder concentration based on the acoustic emission signal and the positive correlation between the coal powder concentration and the electrostatic signal.

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