A method and device for monitoring real-time pulverized coal entering a boiler of a thermal power plant

Abstract

The application discloses a kind of real-time monitoring method and device of coal powder into furnace of thermal power plant, it is related to thermal power fuel detection technical field, wherein method includes: real-time monitoring coal powder pipeline airflow state, dynamic adjustment sampling flow realizes isokinetic sampling, and automatic purging probe;Gas-solid mixed sample is separated, homogenized and quantitatively transported, four types of signals of microwave, optics, capacitance, light scattering are simultaneously obtained in analysis area, according to which coal powder moisture, ash content, concentration, flow rate and particle size distribution are detected, and then heat value is calculated, six-dimensional monitoring data are generated and uploaded to control system to optimize combustion.The application can realize the real-time monitoring of multiple parameters of coal powder into furnace, unmanned operation, improve the representativeness and measurement accuracy of the sample, solve the problem of traditional monitoring lag and single parameter, provide data support for combustion optimization, improve the efficiency of the boiler and reduce the operation and maintenance cost.

Description

Technical Field

[0001] This invention relates to the field of thermal power generation fuel detection technology, and in particular to a method and device for real-time monitoring of pulverized coal entering the furnace of a thermal power plant. Background Technology

[0002] Against the backdrop of the "dual-carbon" strategy and energy structure transformation, thermal power plants need to undertake deep peak-shaving tasks to adapt to the fluctuating output of new energy sources such as wind power and photovoltaics. At the same time, in order to control fuel costs, they often adopt a multi-coal blending mode. These two trends lead to drastic fluctuations in the parameters of pulverized coal fed into the boiler (concentration, flow rate, particle size distribution, moisture, ash content, calorific value, coal quality characteristics), and the parameters of pulverized coal directly determine the boiler combustion efficiency and operational safety.

[0003] Currently, the mainstream method for pulverized coal monitoring in the industry is still "manual sampling + offline analysis." This method suffers from significant lag (analysis cycles are typically 2-4 hours), making it impossible to capture real-time dynamic changes in pulverized coal parameters. Excessive pulverized coal concentration can easily lead to furnace slagging and excessive NOx emissions; excessively low concentrations may cause fire extinguishing or explosions; uneven flow rates can cause air distribution imbalances in burners, exacerbating wear on heating surfaces; excessively large particle size, abnormal moisture / ash content, or sudden changes in coal quality can lead to incomplete combustion and a decrease in boiler efficiency (typically 1%-3%). According to industry statistics, unplanned shutdowns caused by uncontrolled pulverized coal parameters occur an average of 0.5-1 times per unit per year, with single shutdown losses exceeding 2 million yuan. Furthermore, NOx emission violations account for more than 40% of all environmental violations, severely restricting the economic efficiency, safety, and environmental impact of power plants. In addition, traditional manual sampling suffers from poor representativeness and high labor intensity, failing to meet the needs of refined combustion optimization. Summary of the Invention

[0004] The main objective of this invention is to provide a method for real-time monitoring of pulverized coal fed into a thermal power plant.

[0005] Another objective of this invention is to provide a real-time monitoring device for pulverized coal entering the furnace of a thermal power plant.

[0006] The third objective of this invention is to provide an electronic device.

[0007] A fourth objective of this invention is to provide a non-transitory computer-readable storage medium.

[0008] To achieve the above objectives, a first aspect of the present invention provides a method for real-time monitoring of pulverized coal fed into a thermal power plant, comprising:

[0009] S1 monitors the airflow status in the pulverized coal conveying pipeline in real time, dynamically adjusts the sampling flow rate, performs isokinetic sampling, and automatically purges and cleans the sampling probe after sampling is completed. S2, the collected gas-solid mixture sample is subjected to gas-solid separation processing, the separated solid coal powder sample is homogenized, and the homogenized coal powder sample is quantitatively transported to the analysis area; S3, simultaneously acquires microwave response signal, optical attenuation signal, capacitance delay signal and light scattering signal of coal powder sample in the analysis area, and determines the moisture content, ash content, concentration parameter, flow rate parameter and particle size distribution characteristics of coal powder based on the four signals respectively; S4 calculates the calorific value parameters of pulverized coal based on the determined moisture and ash content, generates six-dimensional monitoring data including concentration, flow rate, particle size distribution, moisture, ash and calorific value, and transmits the six-dimensional monitoring data to the control system to support combustion optimization and adjustment.

[0010] Optionally, the airflow status in the pulverized coal conveying pipeline is monitored in real time, the sampling flow rate is dynamically adjusted, isokinetic sampling is performed, and the sampling probe is automatically purged and cleaned after sampling, including: The total pressure and static pressure data in the pipeline are collected in real time by a differential pressure transmitter. The actual flow velocity of the pulverized coal gas in the pipeline is calculated based on Bernoulli's equation, and the actual flow velocity of the pulverized coal gas in the pipeline is input as a feedback signal to the PLC control system. The PLC control system calculates the target isokinetic sampling volume flow rate based on the actual flow velocity of the coal powder airflow in the pipeline and the total cross-sectional area of ​​the sampling probe, and outputs frequency conversion control commands to drive the pump with the built-in ejector to adjust the working frequency so that the deviation between the flow velocity at the sampling probe inlet and the actual flow velocity of the coal powder airflow in the pipeline is controlled within 3% to complete the isokinetic sampling operation. After a single sampling cycle is completed, the PLC control system automatically activates the reverse pulse purging system, injecting dry compressed air at a pressure of 0.6MPa to 0.8MPa into the sampling probe and purging continuously for 10 seconds to remove residual coal powder particles from the sampling hole.

[0011] Optionally, the collected gas-solid mixture sample undergoes gas-solid separation processing, the separated solid coal powder sample is homogenized, and the homogenized coal powder sample is quantitatively transported to the analysis area, including: The gas-solid mixture sample is controlled to enter the cyclone separator tangentially at a speed of 15 m / s to 20 m / s, and centrifugal force is used to separate particles with a diameter greater than 5 mm. The coal powder particles are thrown against the wall of the device and fall into the micro buffer chamber. The separation efficiency is controlled at over 98%. The clean air after separation is purified by the top filter before being discharged. Start the micro stirrer installed in the micro buffer chamber and stir the coal powder falling into the chamber at a speed of 60 r / min to eliminate the uneven particle size and composition distribution of the sample and make the homogenization degree of the coal powder sample reach more than 90%. A precision screw feeder driven by a servo motor adjusts the screw speed within the range of 0.5 g / s to 5 g / s according to the preset feed rate, and stably delivers the homogenized coal powder sample to the quartz sample cell of the online analysis unit with a feed accuracy of ±2%.

[0012] Optionally, microwave response signals, optical attenuation signals, capacitance delay signals, and light scattering signals of the coal powder sample are simultaneously acquired within the analysis area. Based on these four signals, the moisture content, ash content, concentration parameters, flow rate parameters, and particle size distribution characteristics of the coal powder are determined, including: A microwave transmitter emits microwaves at a frequency of 2.45 GHz through a thin layer of coal powder with a constant thickness of 5 mm. A receiver then collects the attenuation of the microwave signal. With phase shift The moisture content of pulverized coal on an air-dried basis is calculated by substituting the values ​​into the following formulas. Ash content of pulverized coal air-dried basis :

[0013]

[0014] in, , This is the moisture calibration coefficient. , This is the ash content calibration coefficient; A laser emitter emits a 650nm wavelength laser beam that passes through a coal powder gas flow within a sampling tube, and a receiver collects the light intensity after the beam has passed through the coal powder. Combined with the intensity of the incident laser light Extinction coefficient of pulverized coal and optical path length The mass concentration of pulverized coal is calculated using a formula. :

[0015] in, The extinction coefficient of pulverized coal; The sampling tube is installed with a distance of 1 meter between its upstream and downstream sides. The characteristic signals generated by the two sets of capacitive sensors at the location are used to calculate the time delay of the two sets of signals through a cross-correlation algorithm. The flow rate of pulverized coal in the sampling tube was calculated. The formula is:

[0016] A laser with a wavelength of 532 nm was controlled to pass through a coal powder gas flow. The intensity of the scattered light at different angles was measured using eight photodetectors within a scattering angle range of 10° to 170°. Based on the Mie scattering theory, the particle size distribution characteristics of the coal powder were calculated. .

[0017] Optionally, based on the determined moisture and ash content, the calorific value parameters of pulverized coal are calculated, generating six-dimensional monitoring data including concentration, flow rate, particle size distribution, moisture, ash content, and calorific value. This six-dimensional monitoring data is then transmitted to the control system to support combustion optimization and adjustment, including: Obtain air-dried basis moisture Air-dried ash content And the total sulfur content on an air-dried basis obtained from the power plant's desulfurization system. Combined with local coal type correction coefficient The calculated lower heating value of pulverized coal is as follows: :

[0018] The calculated lower heating value of pulverized coal is used as a basis. The data is integrated with real-time monitored concentration parameters, flow rate parameters, particle size distribution characteristics, moisture content and ash content to generate six-dimensional monitoring data, which is then transmitted to the distributed control device at a frequency of 1 time / second through the DCS interface. Receive boiler load and air volume data from the distributed control unit, and calculate the optimized primary air volume based on the measured pulverized coal moisture content and measured calorific value. It also generates combustion optimization instructions and pushes them to the distributed control unit for execution.

[0019] in, Based on the primary air volume, This is the moisture correction factor. To measure the moisture content of the pulverized coal, Moisture content of pulverized coal as a reference. This is the calorific value correction factor. As the reference calorific value, This is the measured calorific value.

[0020] To achieve the above objectives, a second aspect of the present invention provides a real-time monitoring device for pulverized coal fed into a thermal power plant, comprising: The monitoring module is used to monitor the airflow status in the pulverized coal conveying pipeline in real time, dynamically adjust the sampling flow rate, perform isokinetic sampling, and automatically purge and clean the sampling probe after sampling is completed. The preprocessing module is used to perform gas-solid separation processing on the collected gas-solid mixed sample, perform homogenization processing on the separated solid coal powder sample, and quantitatively deliver the homogenized coal powder sample to the analysis area. The feature acquisition module is used to simultaneously acquire the microwave response signal, optical attenuation signal, capacitance delay signal and light scattering signal of the coal powder sample in the analysis area, and determine the moisture content, ash content, concentration parameters, flow rate parameters and particle size distribution characteristics of the coal powder based on the four signals respectively. The optimization module is used to calculate the calorific value parameters of pulverized coal based on the determined moisture and ash content, generate six-dimensional monitoring data including concentration, flow rate, particle size distribution, moisture, ash and calorific value, and transmit the six-dimensional monitoring data to the control system to support combustion optimization and adjustment.

[0021] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0022] To achieve the above objectives, a third aspect of this application provides an electronic device, including a processor and a memory; wherein the processor reads executable program code stored in the memory to run a program corresponding to the executable program code, for implementing the real-time monitoring method for pulverized coal fed into a thermal power plant as described in the first aspect embodiment.

[0023] To achieve the above objectives, the fourth aspect of this application provides a non-transitory computer-readable storage medium storing a computer program that, when executed by a processor, implements the real-time monitoring method for pulverized coal fed into a thermal power plant as described in the first aspect embodiment.

[0024] The embodiments of the present invention have the following beneficial effects: This invention enables simultaneous real-time monitoring of six parameters of pulverized coal entering the furnace and unattended operation throughout the entire process, significantly improving sample representativeness and measurement accuracy; it effectively solves the problems of traditional monitoring lag and single parameters, providing data support for automatic combustion optimization, thereby improving boiler efficiency and reducing operation and maintenance costs. Attached Figure Description

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 A flowchart of a real-time monitoring method for pulverized coal fed into a thermal power plant, provided as an embodiment of the present invention; Figure 2 A structural diagram of a real-time monitoring device for pulverized coal entering a thermal power plant, provided in an embodiment of the present invention; Figure 3This is a structural diagram of another real-time monitoring device for pulverized coal entering the furnace of a thermal power plant, provided as an embodiment of the present invention. Detailed Implementation

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0028] The following describes, with reference to the accompanying drawings, a method and apparatus for real-time monitoring of pulverized coal fed into a thermal power plant according to an embodiment of the present invention.

[0029] Example 1 This invention provides a method for real-time monitoring of pulverized coal fed into a thermal power plant, such as... Figure 1 As shown, the method includes the following steps: S1 monitors the airflow status in the pulverized coal conveying pipeline in real time, dynamically adjusts the sampling flow rate, performs isokinetic sampling, and automatically purges and cleans the sampling probe after sampling is completed.

[0030] To achieve accurate, stable, and fully automated coal powder sampling, this application utilizes a distributed deployment of intelligent sampling units. By designing core components and incorporating relevant calculation formulas, it accomplishes isokinetic sampling, flow rate monitoring, and probe anti-clogging, ensuring sampling accuracy and continuity.

[0031] In this embodiment, the application implements this step through an intelligent sampling unit. This unit, as the core of fully automatic sampling, is deployed in a distributed manner at key points of the pulverizing or combustion device. The sampling requirements for each monitoring point are clearly defined, specifically: the sampling frequency at the coal mill outlet is once every 3 minutes, with a pipeline flow velocity range of 15-25 m / s, and the core objective is to monitor the output of the pulverizing system and the initial state of the pulverized coal; the sampling frequency before the primary air duct branch is once every 4 minutes, with a pipeline flow velocity range of 12-20 m / s, and the core objective is to provide a benchmark for pulverized coal distribution leveling in each burner; the sampling frequency at the burner inlet branch is once every 2 minutes, with a pipeline flow velocity range of 8-15 m / s, and the core objective is to monitor the uniformity of pulverized coal distribution in each burner.

[0032] The core components of this intelligent sampling unit include an isokinetic sampling probe, a differential pressure transmitter, and a flow control module. The isokinetic sampling probe is made of tungsten carbide wear-resistant steel (hardness HRC60 or higher), which is suitable for high dust scouring environments. It adopts a back-to-back design with four symmetrical sampling holes (8mm in diameter) on the head, which can reduce particle size deviation caused by airflow disturbance. The probe has a built-in temperature sensor (measurement range 0-300℃), which can monitor the temperature of coal powder in the pipeline in real time.

[0033] To achieve accurate isokinetic sampling, this application installs a differential pressure transmitter (accuracy ±0.1 kPa) near the probe to monitor the total pressure and static pressure inside the pipeline in real time. The actual flow velocity of the pulverized coal gas in the pipeline is calculated using Bernoulli's equation, as shown in the following formula:

[0034] in, The total pressure of the airflow inside the pipeline, in Pa; The static pressure of the airflow inside the pipeline, in Pa; The density of the pulverized coal gas mixture is expressed in kg / m³. ; For air density, take 1.293 kg / m³ (under standard conditions); The true density of pulverized coal is taken as 1350~1500 kg / m³ (adjusted according to the type of coal). The volume fraction of pulverized coal is dimensionless.

[0035] Based on the calculated airflow velocity, the PLC adjusts the pumping flow rate of the probe's built-in ejector via frequency conversion to ensure that the flow velocity at the sampling probe inlet deviates from the pipe flow velocity by ≤3%, achieving isokinetic sampling. Simultaneously, the isokinetic sampling flow rate is calculated using the following formula:

[0036] in, The volumetric flow rate is the constant velocity sampling rate, in m³ / h. The actual velocity of the pulverized coal gas flow in the pipeline is expressed in m / s. This represents the total cross-sectional area of ​​the sampling probe, in m². ; The number of sampling holes is set to 4 for this device; The diameter of a single sampling hole is 8 mm (0.008 m) for this device.

[0037] To prevent the sampling probe from becoming clogged, the probe is equipped with a reverse pulse purging system, which uses 0.6-0.8MPa dry compressed air (dew point ≤ -40℃). It automatically purges for 10 seconds after each sampling cycle (2-4 minutes). The purging pressure can be adaptively adjusted according to the dust concentration in the pipeline to ensure that there is no residual coal dust in the sampling hole.

[0038] The differential pressure transmitter uses a capacitive differential pressure sensor with a measurement range of -10kPa to +10kPa, an accuracy of ±0.1%FS, and a vibration resistance level of ≥5g (10-2000Hz), making it suitable for high-vibration environments in power plants. The flow control module has a built-in variable frequency air pump (flow adjustment range 0-50L / min) and an electromagnetic flow meter (accuracy ±1%). The PLC dynamically adjusts the pump frequency according to the differential pressure signal to achieve precise control of the sampling flow (control accuracy ±2%), further ensuring the stability and accuracy of isokinetic sampling.

[0039] In this embodiment, by deploying intelligent sampling units in a distributed manner, an isokinetic sampling probe, a differential pressure transmitter, and a flow control module are designed. Combined with flow velocity and flow rate calculation formulas and equipped with a probe anti-clogging system, accurate and fully automatic isokinetic sampling of coal powder is achieved, ensuring sampling stability and accuracy.

[0040] S2, the collected gas-solid mixture sample is subjected to gas-solid separation processing, the separated solid coal powder sample is homogenized, and the homogenized coal powder sample is quantitatively transported to the analysis area.

[0041] To achieve efficient gas-solid separation, homogenization, and stable quantitative delivery of pulverized coal samples, this application designs a sample processing and delivery unit to avoid sample residue and contamination, and to ensure the accuracy of subsequent analysis.

[0042] In this embodiment, the sample processing and conveying unit is used to implement this step. This unit serves as the core for sample homogenization and stable conveying. Core components include a cyclone separator, a micro-buffer silo and homogenization device, and a precision screw feeder. The gas-solid separation process is completed by the cyclone separator, which adopts a tangential air inlet design with a diameter of 150mm and a separation cone angle of 15°, ensuring a gas-solid separation efficiency of ≥98%. Its working principle is as follows: the sampled gas-powder mixture enters the separator tangentially at a speed of 15-20m / s. Under centrifugal force, the coal powder particles (particle size >5) are separated. The air is thrown against the wall and falls along the wall into the next buffer chamber; the separated clean air (containing a small amount of particles <5) Powdered coal) passes through a top filter (filtration accuracy 1). After purification, the waste is discharged through an exhaust valve to avoid environmental pollution.

[0043] To prevent coal powder from sticking to the walls, the inner wall of the separator is coated with polytetrafluoroethylene (coefficient of friction <0.05) and equipped with a bottom vibrator (vibration frequency 50Hz, amplitude 0.5mm), vibrating once every 10 seconds to ensure that the coal powder falls completely into the buffer chamber without residue (residue <0.1g). The separated solid coal powder sample enters a micro buffer chamber with a volume of 500mL, made of stainless steel, and equipped with a level sensor (ultrasonic, accuracy ±1mm) to monitor the material level in the chamber in real time, preventing overflow due to excessively high material levels or interruption of feeding due to excessively low material levels.

[0044] A micro stirrer (60 r / min, 80 mm diameter) is installed in the buffer chamber to homogenize the coal powder (homogeneity ≥ 90%), eliminating the influence of uneven sample particle size and composition distribution on the analysis results; the stirrer is made of soft silicone to avoid wear and tear that could cause metal impurities to contaminate the sample.

[0045] The homogenized coal powder sample is quantitatively fed to the online analysis unit via a precision screw feeder. The screw of the precision screw feeder has a diameter of 30mm and a pitch of 10mm, and is made of wear-resistant nylon to avoid metal wear and contamination of the sample. Driven by a servo motor (control accuracy ±0.1r / min), the feeding rate can be adjusted within the range of 0.5-5g / s, with a feeding accuracy of ±2%, ensuring stable delivery of the sample to the online analysis unit and avoiding analysis errors caused by sample flow fluctuations (error ≤0.3%). A torque sensor (measurement range 0-10N·m) is equipped at the end of the screw. When the torque exceeds the threshold (8N·m), it is judged as a blockage. The PLC automatically reverses the screw for 3 seconds to clear the blockage, ensuring the continuity of sample delivery and ensuring that a stable and uniform coal powder sample can be obtained in the analysis area.

[0046] In this embodiment, by setting up a cyclone separator, a buffer homogenization device, and a precision screw feeder, the gas-solid separation, homogenization, and stable transport of the coal powder sample are completed, avoiding sample residue, blockage, and contamination, and providing a uniform and reliable sample for subsequent online analysis.

[0047] S3 simultaneously acquires the microwave response signal, optical attenuation signal, capacitance delay signal and light scattering signal of the coal powder sample within the analysis area, and determines the moisture content, ash content, concentration parameters, flow rate parameters and particle size distribution characteristics of the coal powder based on the four signals.

[0048] To achieve simultaneous and accurate detection of multiple parameters of pulverized coal, this application adopts an online analysis unit that integrates multiple technologies, and completes the measurement of moisture, ash content, concentration, flow rate and particle size distribution based on multiple signals and corresponding formulas.

[0049] In this embodiment, this application implements this step through an online analysis unit. This unit, as the core of multi-parameter precise analysis, adopts a "multi-technology fusion" strategy to simultaneously monitor six parameters: concentration, flow rate, particle size distribution, moisture, ash content, and calorific value. The acquisition and analysis of the four signals are completed by corresponding modules. The design and working principle of each module are as follows: The microwave response signal is acquired by the microwave moisture / ash analysis module. The principle of this module is as follows: The dielectric constants of moisture (dielectric constant ≈ 80) and ash (dielectric constant ≈ 6) in coal powder are significantly different from those of pure coal (dielectric constant ≈ 2). When microwaves (frequency 2.45 GHz) pass through a thin layer of coal powder with a constant thickness (5 mm), moisture will cause microwave signal attenuation (the amount of attenuation is proportional to the moisture content), and ash will cause microwave signal phase shift (the amount of phase shift is proportional to the ash content). By establishing a calibration model of attenuation-moisture and phase shift-ash (based on training data of 1000+ coal samples), the moisture and ash content can be calculated simultaneously.

[0050] This module employs a through-type microwave resonant cavity structure, with a quartz sample well (5mm thick to ensure constant sample thickness) installed inside. The microwave transmitter and receiver are located on opposite sides of the cavity. A weighing sensor (accuracy ±0.01g) is installed below the sample well to monitor sample mass in real time, ensuring the sample quantity meets analytical requirements (2-3g). Its performance specifications are: moisture measurement range 0-20%, error ≤0.5%; ash measurement range 5%-40%, error ≤0.5%; analysis time <60 seconds; and automatic calibration function (automatic calibration once a week using standard coal samples) to ensure long-term measurement accuracy. The specific calculation formulas for moisture and ash are as follows:

[0051]

[0052] in, Moisture content of pulverized coal (air-dried basis), in % (%) Ash content of pulverized coal on an air-dried basis, in % (%) This represents the microwave signal attenuation, expressed in dB. The phase shift of the microwave signal is expressed in degrees (°). 、 The moisture calibration coefficient was obtained by fitting data from over 1000 coal samples. =0.085, =0.02; 、 The ash content calibration coefficient was obtained by fitting data from over 1000 coal samples. =0.12, =0.15.

[0053] The optical attenuation signal is acquired by the concentration measurement unit in the optical / capacitive composite concentration / flow rate analysis module. Its principle is based on the Lambert-Beer law. A laser emitter (wavelength 650nm) and a receiver are installed on both sides of the sampling tube (diameter 20mm). When the laser passes through the coal powder gas flow, its light intensity attenuation is proportional to the coal powder concentration. By measuring the attenuated light intensity and combining it with the calibration curve (based on tests of coal samples with different concentrations), the instantaneous concentration is calculated.

[0054] The concentration measurement unit has the following structure: a laser emitter with a power of 5mW and a receiver sensitivity of 10. -6 W, the sampling tube is made of transparent quartz material (transmittance ≥95%) and equipped with an air purging device, which purges the tube every 5 minutes to prevent powder accumulation on the tube wall from affecting the transmittance; performance indicators are: concentration measurement range 0-1000g / m³, error ≤5%; response time <100ms, and the specific formula for calculating coal powder concentration is as follows:

[0055] in, This refers to the mass concentration of pulverized coal, expressed in g / m³. The intensity of the laser light after passing through the coal powder, expressed in W; The intensity of the incident laser light is expressed in W. The extinction coefficient of pulverized coal is taken as 0.012 m² / g (adjusted according to coal type). The optical path length is 0.02m (sampling tube diameter) for this device.

[0056] The capacitance delay signal is acquired by the flow rate measurement unit in the optical / capacitive composite concentration / flow rate analysis module. The principle is as follows: a set of capacitance sensors (electrode spacing 5mm) are installed 100mm upstream and 100mm downstream of the laser concentration measuring device. When coal powder particles flow past the upstream sensor, they cause a slight change in capacitance, forming a characteristic signal. This signal experiences a time delay when it flows past the downstream sensor. The time delay between the two signals is calculated using a cross-correlation algorithm (accuracy ±0.1ms), and combined with the sensor spacing (200mm), the flow rate is calculated (flow rate = spacing / time delay). The performance indicators of this flow rate measurement unit are: flow rate measurement range 0-30m / s, error ≤3%; response time <200ms. The specific calculation formula for the coal powder flow rate is as follows:

[0057] in, The velocity of pulverized coal in the sampling tube is expressed in m / s. The spacing between the upstream and downstream capacitive sensors is 0.2m in this device; The signal propagation time delay is expressed in seconds (s).

[0058] Simultaneously, the instantaneous mass flow rate is calculated by multiplying the concentration by the flow rate and the cross-sectional area of ​​the sampling tube. This calculation is used to verify the isokinetic sampling system (when the calculated flow rate deviates from the set sampling flow rate by more than 5%, the PLC automatically adjusts the sampling pump frequency) and to evaluate the total amount of pulverized coal entering the furnace. The formula for calculating the pulverized coal mass flow rate is as follows:

[0059] in, This refers to the mass flow rate of pulverized coal, expressed in kg / h. This refers to the mass concentration of pulverized coal, expressed in g / m³. The velocity of pulverized coal in the sampling tube is expressed in m / s. The cross-sectional area of ​​the sampling tube is in m², and for this device it is 3.14 × 10⁻⁶. -4 m² (diameter 20mm).

[0060] The light scattering signal was acquired by the optical pulsation method particle size analysis module. Its principle is based on Fraunhofer diffraction theory. When the laser (wavelength 532nm) passes through the coal powder gas flow, particles of different sizes will produce scattered light at different angles (small particles have a large scattering angle, and large particles have a small scattering angle). Eight photodetectors were installed in the scattering angle range of 10°-170° to measure the intensity of scattered light at different angles. The particle size distribution (R10, R50, R90) and average particle size of the coal powder were calculated by the inversion algorithm (based on Mie scattering theory).

[0061] The module's structure includes: a 10mW laser emitter, a detector array response time of <10μs, a guide plate installed inside the sampling tube to ensure stable coal powder gas flow through the measurement area, and an automatic cleaning brush to prevent powder accumulation on the detector lens. Its performance specifications include a particle size measurement range of 1-200 mm. With an error ≤3% and an analysis time <120 seconds, the formula for calculating the characteristic value of coal powder particle size distribution is as follows:

[0062] in, This refers to the mass percentage of coal powder with a particle size smaller than d, such as R10, R50, and R90. The particle size of the i-th level coal powder is expressed in μm. The mass of the i-th grade pulverized coal is expressed in grams. The particle size index is 3 (Rossing-Lammler distribution).

[0063] In this embodiment, an online analysis unit integrating multiple technologies combines various detection principles and corresponding calculation formulas to achieve simultaneous and accurate measurement of coal powder moisture, ash content, concentration, flow rate, and particle size distribution.

[0064] S4 calculates the calorific value parameters of pulverized coal based on the determined moisture and ash content, generates six-dimensional monitoring data including concentration, flow rate, particle size distribution, moisture, ash and calorific value, and transmits the six-dimensional monitoring data to the control system to support combustion optimization and adjustment.

[0065] In order to complete the calculation of pulverized coal calorific value, achieve intelligent control of the entire process and zero waste discharge, this application combines relevant calculation formulas to generate six-dimensional monitoring data and support boiler combustion optimization and adjustment.

[0066] In this embodiment, the calorific value parameter of pulverized coal is obtained through the calorific value calculation module in the online analysis unit. The principle of this module is as follows: the received basis lower heating value of coal is strongly correlated with moisture and ash content. Based on the Mendeleev formula and combined with the local coal type correction coefficient, the calorific value is calculated in real time. The specific calculation formula is as follows:

[0067] in, The lower heating value of pulverized coal is given as received, in kJ / kg. Moisture content is on an air-dried basis, expressed in % (%). Ash content is on an air-dried basis, in % %. Total sulfur content on an air-dried basis, in % (taken from power plant desulfurization system). This is a correction factor for local coal types, ranging from -200 to +300 kJ / kg.

[0068] The performance indicators of this calorific value calculation module are: calorific value measurement range 10-30 MJ / kg, error ≤0.2 MJ / kg; calculation time <10 seconds. After the six-dimensional monitoring data is generated, it is transmitted to the application layer. This application layer is built on a PLC local control plus cloud platform remote management architecture, and has fully automatic operation control, data processing, visualization display, and external integration functions. Its core modules include a PLC central control module, a data storage and management module, an intelligent analysis engine module, a visualization interface module, and an external interface module.

[0069] The PLC central control module adopts a Siemens S7-1200 series PLC, equipped with a touch screen, supporting touch operation and shortcut key control. It can realize the fully automated operation of sampling, gas-solid separation, homogenization, feeding, multi-parameter analysis, waste sample recovery, and probe purging without manual intervention. Parameters such as sampling frequency and purging pressure can be set. It has built-in fault handling logic. When problems such as probe blockage, feeder jamming, and microwave module failure are detected, the handling process is automatically executed. If it cannot be handled automatically, an audible and visual alarm is immediately triggered and a text message is sent to the maintenance personnel.

[0070] The data storage and management module uses an SD card to store real-time data for the past three months, supports data protection during power outages, and builds a time-series database based on a cloud platform to store historical data, supports fast querying, and ensures data consistency between local and cloud.

[0071] The intelligent analysis engine module, based on a case-based reasoning algorithm, stores common fault cases. When an abnormal signal is detected, it matches similar cases within 10 seconds, locates the cause of the fault, and provides handling suggestions. Simultaneously, based on real-time monitored moisture, ash, and calorific value data, combined with boiler load, it generates combustion optimization instructions and pushes them to the DCS system. The local interface of the visualization module includes a process monitoring interface, a real-time data interface, and a fault alarm interface. The process monitoring interface displays the entire system's operating status in a dynamic flowchart format, using color coding to identify equipment status. The real-time data interface displays the real-time values ​​of six parameters in tabular form, showing the measurement error range. The fault alarm interface displays the current fault in list form, including the fault cause, handling suggestions, and a handling countdown.

[0072] The external interface module includes a DCS interface and a SIS interface. The DCS interface transmits real-time data of six parameters and combustion optimization instructions to the DCS, and receives data such as boiler load and air volume issued by the DCS. The SIS interface pushes historical data to the SIS system for plant-wide performance calculations.

[0073] After analysis, the waste samples are processed through a waste sample recovery system. This system uses pneumatic conveying to return the waste samples from the online analysis to the main coal powder pipeline via a negative pressure pipeline, achieving zero sample discharge and eliminating the need for manual waste sample handling. The system includes a 1L waste sample collection bin with a pneumatic unloading valve at the bottom. The negative pressure generated by the Roots blower draws the waste samples into the conveying pipeline, ensuring no residue remains. The control logic is as follows: after each analysis, the PLC automatically opens the unloading valve and the Roots blower to convey the waste samples to the main pipeline, and automatically shuts down the equipment after conveying. It is equipped with a material level monitoring function. When the material level in the waste sample bin exceeds 80%, the conveying process is automatically started to prevent overflow due to excessive material level.

[0074] The working modes of this application include fully automatic operation mode, manual control mode, and emergency mode. The process of fully automatic operation mode is as follows: the PLC automatically starts isokinetic sampling according to the set sampling frequency, the sample enters the cyclone separator for gas-solid separation, the coal powder falls into the buffer bin for homogenization, the screw feeder quantitatively conveys it to the online analysis unit, the microwave module measures moisture and ash content, the optical capacitance module measures concentration and flow rate, the optical pulse module measures particle size, the calorific value module calculates the calorific value, after the analysis is completed, the waste sample recovery system returns the waste sample to the main pipeline, the probe is automatically pulse-purged, and the data is uploaded to the application layer and pushed to the DCS. The manual control mode allows operation and maintenance personnel to manually control the start and stop of each unit, modify parameters, and perform calibration through the touch screen. The emergency mode automatically switches when a serious fault is detected, stops the sampling and analysis process, shuts down all motor equipment, and pushes the fault information to the DCS and operation and maintenance personnel.

[0075] To support combustion optimization and regulation, this application also provides calculation formulas related to combustion optimization, including formulas for calculating boiler thermal efficiency and optimal primary air volume, wherein the boiler thermal efficiency calculation formula is as follows:

[0076] in, Boiler thermal efficiency, in % %. For flue gas heat loss, the unit is %. ; Heat loss due to incomplete combustion, expressed in % (%) Heat loss due to incomplete combustion of machinery, expressed in % (%) For heat dissipation loss, in units of % The physical heat loss of ash and slag is expressed in percentage (%). The exhaust heat loss coefficient is taken as 0.85; The exhaust gas temperature is expressed in °C. The air inlet temperature is expressed in °C.

[0077] The formula for calculating the optimal primary air volume is as follows:

[0078] in, The optimized primary air volume is expressed in m³ / h. For the baseline primary air volume, 120,000 m³ / h is used for the 300MW unit; The moisture correction factor is set to 0.08. The moisture content of the pulverized coal is measured, in % (%). The moisture content of the pulverized coal is taken as 10% (in percentage). The calorific value correction factor is set to 0.005. The reference calorific value is expressed in kJ / kg, and is taken as 22000 kJ / kg. The measured calorific value is expressed in kJ / kg.

[0079] Through all the above designs, this application achieves accurate and real-time monitoring of multiple parameters of pulverized coal. The transmission and application of the generated six-dimensional monitoring data can effectively support boiler combustion optimization and adjustment, improve combustion efficiency, and reduce energy consumption and pollutant emissions.

[0080] Example 2 This invention provides a real-time monitoring device 10 for pulverized coal fed into a thermal power plant, such as... Figure 3 As shown, the device includes: The monitoring module 100 is used to monitor the airflow status in the pulverized coal conveying pipeline in real time, dynamically adjust the sampling flow rate, perform isokinetic sampling operation, and automatically purge and clean the sampling probe after sampling is completed. The preprocessing module 200 is used to perform gas-solid separation processing on the collected gas-solid mixed sample, perform homogenization processing on the separated solid coal powder sample, and quantitatively transport the homogenized coal powder sample to the analysis area. The feature acquisition module 300 is used to simultaneously acquire the microwave response signal, optical attenuation signal, capacitance delay signal and light scattering signal of the coal powder sample in the analysis area, and determine the moisture content, ash content, concentration parameters, flow rate parameters and particle size distribution characteristics of the coal powder based on the four signals respectively. The optimization module 400 is used to calculate the calorific value parameters of pulverized coal based on the determined moisture and ash content, generate six-dimensional monitoring data including concentration, flow rate, particle size distribution, moisture, ash and calorific value, and transmit the six-dimensional monitoring data to the control system to support combustion optimization and adjustment.

[0081] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0082] Example 3 To implement the methods of the above embodiments, the present invention also provides an electronic device, which includes a memory and a processor; wherein the processor reads executable program code stored in the memory to run a program corresponding to the executable program code, so as to implement the various steps of the methods described above.

[0083] Example 4 To implement the above embodiments, this application also proposes a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the method described in the foregoing embodiments.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0085] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0086] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

Claims

1. A method for real-time monitoring of pulverized coal fed into a thermal power plant, characterized in that, include: S1 monitors the airflow status in the pulverized coal conveying pipeline in real time, dynamically adjusts the sampling flow rate, performs isokinetic sampling, and automatically purges and cleans the sampling probe after sampling is completed. S2, the collected gas-solid mixture sample is subjected to gas-solid separation processing, the separated solid coal powder sample is homogenized, and the homogenized coal powder sample is quantitatively transported to the analysis area; S3, simultaneously acquires microwave response signal, optical attenuation signal, capacitance delay signal and light scattering signal of coal powder sample in the analysis area, and determines the moisture content, ash content, concentration parameter, flow rate parameter and particle size distribution characteristics of coal powder based on the four signals respectively; S4 calculates the calorific value parameters of pulverized coal based on the determined moisture and ash content, generates six-dimensional monitoring data including concentration, flow rate, particle size distribution, moisture, ash and calorific value, and transmits the six-dimensional monitoring data to the control system to support combustion optimization and adjustment.

2. The method according to claim 1, characterized in that, The system monitors the airflow state within the pulverized coal conveying pipeline in real time, dynamically adjusts the sampling flow rate, performs isokinetic sampling, and automatically purges and cleans the sampling probe after sampling, including: The total pressure and static pressure data in the pipeline are collected in real time by a differential pressure transmitter. The actual flow velocity of the pulverized coal gas in the pipeline is calculated based on Bernoulli's equation, and the actual flow velocity of the pulverized coal gas in the pipeline is input as a feedback signal to the PLC control system. The PLC control system calculates the target isokinetic sampling volume flow rate based on the actual flow velocity of the coal powder airflow in the pipeline and the total cross-sectional area of ​​the sampling probe, and outputs frequency conversion control commands to drive the pump with the built-in ejector to adjust the working frequency so that the deviation between the flow velocity at the sampling probe inlet and the actual flow velocity of the coal powder airflow in the pipeline is controlled within 3% to complete the isokinetic sampling operation. After a single sampling cycle is completed, the PLC control system automatically activates the reverse pulse purging system, injecting dry compressed air at a pressure of 0.6MPa to 0.8MPa into the sampling probe and purging continuously for 10 seconds to remove residual coal powder particles from the sampling hole.

3. The method according to claim 1, characterized in that, The process of performing gas-solid separation on the collected gas-solid mixed sample, homogenizing the separated solid coal powder sample, and quantitatively delivering the homogenized coal powder sample to the analysis area includes: The gas-solid mixture sample is controlled to enter the cyclone separator tangentially at a speed of 15 m / s to 20 m / s, and centrifugal force is used to separate particles with a diameter greater than 5 mm. The coal powder particles are thrown against the wall of the device and fall into the micro buffer chamber. The separation efficiency is controlled at over 98%. The clean air after separation is purified by the top filter and then discharged. Start the micro stirrer installed in the micro buffer chamber and stir the coal powder falling into the chamber at a speed of 60 r / min to eliminate the uneven particle size and composition distribution of the sample and make the homogenization degree of the coal powder sample reach more than 90%. A precision screw feeder driven by a servo motor adjusts the screw speed within the range of 0.5 g / s to 5 g / s according to the preset feed rate, and stably delivers the homogenized coal powder sample to the quartz sample cell of the online analysis unit with a feed accuracy of ±2%.

4. The method according to claim 1, characterized in that, The process involves simultaneously acquiring microwave response signals, optical attenuation signals, capacitance delay signals, and light scattering signals of pulverized coal samples within the analysis area. Based on these four signals, the moisture content, ash content, concentration parameters, flow rate parameters, and particle size distribution characteristics of the pulverized coal are determined, including: A microwave transmitter emits microwaves at a frequency of 2.45 GHz through a thin layer of coal powder with a constant thickness of 5 mm. A receiver then collects the attenuation of the microwave signal. With phase shift The moisture content of pulverized coal on an air-dried basis is calculated by substituting the values ​​into the following formulas. Ash content of air-dried coal powder : in, , This is the moisture calibration coefficient. , This is the ash content calibration coefficient; A laser emitter emits a 650nm wavelength laser beam that passes through a coal powder gas flow within a sampling tube, and a receiver collects the light intensity after the beam has passed through the coal powder. Combined with the intensity of the incident laser light Extinction coefficient of pulverized coal and optical path length The mass concentration of pulverized coal is calculated using a formula. : in, The extinction coefficient of pulverized coal; The sampling tube is installed with a distance of 1 meter between its upstream and downstream sides. The characteristic signals generated by the two sets of capacitive sensors at the location are used to calculate the time delay of the two sets of signals through a cross-correlation algorithm. The flow rate of pulverized coal in the sampling tube was calculated. The formula is: A laser with a wavelength of 532 nm was controlled to pass through a coal powder gas flow. The intensity of the scattered light at different angles was measured using eight photodetectors within a scattering angle range of 10° to 170°. Based on the Mie scattering theory, the particle size distribution characteristics of the coal powder were calculated. .

5. The method according to claim 1, characterized in that, The calculation of pulverized coal calorific value parameters based on determined moisture and ash content generates six-dimensional monitoring data including concentration, flow rate, particle size distribution, moisture, ash content, and calorific value. This six-dimensional monitoring data is then transmitted to the control system to support combustion optimization and adjustment, including: Obtain air-dried basis moisture Air-dried ash content And the total sulfur content on an air-dried basis obtained from the power plant's desulfurization system. Combined with local coal type correction coefficient The calculated lower heating value of pulverized coal is as follows: : The calculated lower heating value of pulverized coal is used as a basis. The data is integrated with real-time monitored concentration parameters, flow rate parameters, particle size distribution characteristics, moisture content and ash content to generate six-dimensional monitoring data, which is then transmitted to the distributed control device at a frequency of 1 time / second through the DCS interface. Receive boiler load and air volume data from the distributed control unit, and calculate the optimized primary air volume based on the measured pulverized coal moisture content and measured calorific value. It also generates combustion optimization instructions and pushes them to the distributed control unit for execution. in, Based on the primary air volume, This is the moisture correction factor. To measure the moisture content of the pulverized coal, Moisture content of pulverized coal as a reference. This is the calorific value correction factor. As the reference calorific value, This is the measured calorific value.

6. A real-time monitoring device for pulverized coal fed into a thermal power plant, characterized in that, include: The monitoring module is used to monitor the airflow status in the pulverized coal conveying pipeline in real time, dynamically adjust the sampling flow rate, perform isokinetic sampling, and automatically purge and clean the sampling probe after sampling is completed. The preprocessing module is used to perform gas-solid separation processing on the collected gas-solid mixed sample, perform homogenization processing on the separated solid coal powder sample, and quantitatively deliver the homogenized coal powder sample to the analysis area. The feature acquisition module is used to simultaneously acquire the microwave response signal, optical attenuation signal, capacitance delay signal and light scattering signal of the coal powder sample in the analysis area, and determine the moisture content, ash content, concentration parameters, flow rate parameters and particle size distribution characteristics of the coal powder based on the four signals respectively. The optimization module is used to calculate the calorific value parameters of pulverized coal based on the determined moisture and ash content, generate six-dimensional monitoring data including concentration, flow rate, particle size distribution, moisture, ash and calorific value, and transmit the six-dimensional monitoring data to the control system to support combustion optimization and adjustment.

7. An electronic device, characterized in that, Including processor and memory; The processor reads executable program code stored in the memory to run a program corresponding to the executable program code, so as to implement the method as described in any one of claims 1-5.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-5.

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