Multi-branch pulverized coal particle size monitoring integrated system and control method thereof

Abstract

The invention belongs to a monitoring method, and provides a multi-branch pulverized coal granularity monitoring integrated system and a control method thereof in order to solve the technical problems that an existing pulverized coal fineness monitoring method is insufficient in real-time performance, poor in sample representativeness, prone to abrasion and failure of a sensor, high in cost and prone to sample cross interference and data distortion. The time sequence is cooperatively controlled through in-situ blocking and pulse back flushing, so that the risk of cross contamination is effectively eliminated, and the accuracy of a pulverized coal particle size measurement result is ensured. And a closed-loop feedback mechanism based on the real-time shading rate is adopted, so that self-adaptive cleaning is realized, the purging efficiency is optimized, and the energy consumption of compressed air is reduced. Through a one-control-multiple architecture of multi-path parallel sample introduction and single-path series detection, hardware investment is reduced, the monitoring coverage rate is remarkably improved, and the operation cost of a power plant is reduced. The whole system improves the precision and economical efficiency of pulverized coal particle size monitoring, and is suitable for efficient pulverized coal monitoring of a coal-fired power plant.

Description

Technical Field

[0001] This application pertains to a monitoring method, specifically relating to a multi-branch coal powder particle size monitoring integrated system and its control method. Background Technology

[0002] In the current power generation system, coal-fired units frequently participate in deep peak shaving under the background of energy structure adjustment and changes in power system operation mode. The fineness of pulverized coal has a significant impact on boiler combustion stability, burnout degree and pollutant emissions. However, existing methods are difficult to achieve timely, accurate and stable monitoring of pulverized coal particle size under rapidly changing operating conditions. Existing pulverized coal fineness monitoring methods mainly include offline sieving and online monitoring methods. Offline sieving involves manual periodic sampling followed by drying, sieving and weighing. Online monitoring methods include fixed single-point sampling, "one pipe, one machine" configuration, and integrated schemes with multiple points sharing the same detector.

[0003] Among the above solutions, offline sieving has time lag and is easily affected by human operation, resulting in poor sample representativeness and consistency; fixed single-point sampling is difficult to obtain representative samples reflecting the full cross-sectional characteristics in a high-speed gas-solid two-phase flow environment, resulting in large measurement deviations, and the sensor is prone to wear and failure due to long-term exposure to high-speed dust; the "one pipe, one machine" approach has high initial installation and maintenance costs; the multi-point shared detector solution also suffers from sample cross-interference and data tailing distortion caused by coal dust deposition and insufficient purification control in the common pipeline, affecting the accuracy and reliability of monitoring results. Summary of the Invention

[0004] This application addresses the technical problems of existing coal powder fineness monitoring methods, such as insufficient real-time performance, poor sample representativeness, easy sensor wear and failure, high cost, and susceptibility to sample cross-interference and data distortion. It proposes a multi-branch coal powder particle size monitoring integrated system and its control method.

[0005] To achieve the above objectives, this application adopts the following technical solution: In the first aspect, this application proposes a multi-branch coal powder particle size monitoring integrated system, including a main control unit, and a central manifold valve group, a gas-solid separation unit, a three-way reversing unit, a particle size detection unit, a purging power unit, the main control unit, and multiple sampling branches that are electrically connected to the main control unit respectively. The input ends of the multiple sets of sampling branches are each connected to an external primary air duct, and the output ends of the multiple sets of sampling branches are connected to the corresponding multiple inlets of the central manifold valve group; the total outlet of the central manifold valve group is connected to the input end of the gas-solid separation unit. The first channel of the three-way reversing unit is connected to the output end of the gas-solid separation unit, the second channel is connected to the purging power unit, and the third channel is connected to the particle size detection unit.

[0006] Furthermore, each of the multiple sampling branches includes a sampling device installed on the primary air duct, and a delivery pipeline connecting the sampling device to the sampling inlet of the central manifold valve group.

[0007] Furthermore, each inlet of the central manifold valve assembly is equipped with an electromagnetic on / off valve independently controlled by the main control unit.

[0008] Furthermore, the top of the gas-solid separation unit is connected to a waste gas return pipeline, and the end of the waste gas return pipeline is led back to the external primary air duct. The bottom ash collection hopper of the gas-solid separation unit is equipped with an ash discharge valve controlled by the main control unit.

[0009] Furthermore, the three-way reversing unit is a reversing valve controlled by the main control unit, used to switch the sample feeding conduction state between the particle size detection unit and the gas-solid separation unit, or to switch the purging conduction state between the purging power unit and the common pipeline.

[0010] Secondly, this application proposes a control method for a multi-branch coal powder particle size monitoring integrated system, applied to the aforementioned multi-branch coal powder particle size monitoring integrated system, comprising: S1, the main control unit opens the sampling branch with the specified sequence number and the corresponding central manifold valve group inlet, so that the coal powder enters the particle size detection unit after passing through the gas-solid separation unit for particle size data acquisition. S2, the main control unit closes the sample inlet corresponding to the central manifold valve group; S3, through the main control unit, controls the three-way reversing unit to connect to the purging power unit and start the purging power unit to purge the front side of the particle size detection unit, and at the same time separates the exhaust gas and residual powder from the gas-solid separation unit and discharges them back into the corresponding primary air duct. S4, the main control unit continuously determines whether the conditions for opening the next set of sampling branches are met within the common path, and completes the cross-branch switching; the common path includes the flow path between the central manifold valve group and the particle size detection unit.

[0011] Furthermore, prior to step S1, the procedure also includes: The main control unit retrieves the real-time shading rate data of the particle size detection unit. If the shading rate is higher than the preset background threshold, the purging power unit is activated to purge the front end of the particle size detection unit until the shading rate drops to less than or equal to the preset background threshold.

[0012] Furthermore, the method for separating exhaust gas and residual powder from the gas-solid separation unit includes: discharging the separated exhaust gas and residual powder back into the primary air duct by opening the ash discharge valve at the bottom of the gas-solid separation unit.

[0013] Further, in step S4, the activation conditions include: If no residual particulate matter signal is detected in the common path and the shading rate is reset, then the next set of sampling branches can be opened.

[0014] Furthermore, the particle size detection unit employs full-range laser diffraction and Mie light scattering theory for measurement.

[0015] Compared with the prior art, this application has the following beneficial effects: This application provides an integrated system for monitoring the particle size of pulverized coal in multiple branches. First, through physical topology optimization, the system achieves the goal of zero dead zone contamination prevention. It employs a coordinated control sequence of in-situ blocking and pulse backflushing, immediately and rapidly trunculating the physical path at the end of each measurement task, simultaneously triggering a forced cleaning action in the common pipeline. This completely eliminates the physical interference of residual pulverized coal in the common measurement path to subsequent samples, fundamentally preventing the risk of cross-contamination that may occur when switching between branches. Therefore, the system can ensure accurate and independent particle size measurement results for each pulverized coal pipeline, avoiding common contamination problems during measurement. Second, this application adopts a closed-loop adaptive cleaning method based on a feedback mechanism. Unlike traditional timed blind blowing, this application extracts real-time shading rate data from the particle size detection unit and dynamically adjusts the cleaning duration to form an adaptive cleaning mechanism. When insufficient cleanliness is detected in the pipeline, the system automatically starts the cleaning process until the shading rate returns to the preset standard. This approach not only ensures that the system always starts measurement tasks in a clean environment but also significantly improves purging efficiency and reduces waste of plant compressed air, thereby enhancing the system's energy-saving performance. Finally, this application achieves high economic efficiency and broad monitoring coverage through architectural integration. The system adopts a multi-channel parallel sampling and single-channel series detection architecture, enabling automated cyclic monitoring of the entire coal mill's primary air pulverized coal pipeline through a single high-precision particle size detection unit. This highly integrated design not only increases monitoring coverage but also significantly reduces power plant investment in hardware procurement, spare parts turnover, and daily maintenance, thereby significantly reducing operating costs and improving the overall system's economic efficiency. Furthermore, the automated control system makes the pulverized coal monitoring process more efficient and convenient, further reducing the need for manual intervention. In summary, this application's multi-channel pulverized coal particle size monitoring integrated system, through innovative design and intelligent control, successfully improves the accuracy and efficiency of pulverized coal particle size monitoring while significantly reducing system complexity, operating costs, and energy consumption, providing coal-fired power plants with an efficient, reliable, and economical online pulverized coal particle size monitoring solution. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a multi-branch coal powder particle size monitoring integrated system of this application; Figure 2 This is a flowchart illustrating a control method for the multi-branch coal powder particle size monitoring integrated system of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0020] Coal-fired power units are a crucial component of thermal power generation systems, supplying base loads while increasingly participating in grid regulation. With continuous adjustments to the energy structure and evolving power system operation modes, these units frequently engage in deep peak shaving within low and wide load ranges. Deep peak shaving refers to the regulation method where generating units significantly reduce output to adapt to fluctuations in power load. During this process, pulverized coal fineness, i.e., the size of pulverized coal particles, directly affects the stability of boiler combustion, the complete combustion of pulverized coal, and pollutant emission levels. Therefore, pulverized coal fineness has become a key monitoring parameter for the safe and economical operation of boilers. In current operating scenarios, the pulverized coal transportation and combustion processes experience rapid changes and numerous disturbances. The particle size of pulverized coal often fluctuates with changes in load, air volume, and pulverizing conditions, making monitoring highly challenging. Especially inside pulverized coal pipelines, pulverized coal is typically transported in a high-speed gas-solid two-phase flow. This gas-solid two-phase flow refers to a state where gas and solid particles flow simultaneously. In this state, uneven particle distribution and a complex flow field make it difficult to reflect pulverized coal fineness in a timely and accurate manner. If stable and reliable particle size information cannot be obtained, it will not only affect the targeting of combustion adjustments, but also weaken the effective judgment of burnout and emission status.

[0021] To address the aforementioned issues, existing methods for monitoring the fineness of pulverized coal can be broadly categorized into two types: offline sieving and online monitoring. Offline sieving typically involves manual, periodic sampling followed by drying, sieving, and weighing to calculate the particle size distribution. Online monitoring methods further include fixed-point sampling, a "one pipe, one device" configuration, and integrated solutions using a multi-point shared detector. Fixed-point sampling involves obtaining and testing samples at fixed locations along the pulverized coal pipeline; a "one pipe, one device" configuration means each pipeline is equipped with an independent testing device; and a multi-point shared detector solution connects multiple testing points to the same device through switching between different sampling points for centralized monitoring. However, these solutions still have significant shortcomings in practical applications. Offline sieving, which involves manual sampling and experimental processing, suffers from delayed result feedback, significant susceptibility to operational processes, and insufficient sample representativeness and consistency. While fixed single-point sampling is an online detection method, its sampling locations are limited. Under high-speed gas-solid two-phase flow conditions, it is difficult to obtain representative samples that can characterize the full cross-sectional features, which can easily lead to large measurement deviations. Furthermore, the sensor is prone to wear and failure due to long-term exposure to high-speed dust. A "one pipe, one instrument" configuration allows for independent testing of each pipe, but the large number of devices results in high initial construction and subsequent maintenance costs. While a multi-point shared detector solution addresses the need for multi-point measurement and compact equipment configuration, coal dust deposition is prone to occur in the shared pipeline, and insufficient purification control can cause sample cross-interference and data tailing distortion, thus affecting the accuracy and reliability of the monitoring results.

[0022] Based on the above problems, this application proposes a multi-branch coal powder particle size monitoring integrated system and its control method, which will be further described in detail below with reference to embodiments and accompanying drawings.

[0023] Example 1 like Figure 1 The diagram shown is a schematic of a multi-branch coal powder particle size monitoring integrated system of this application, including multiple sampling branches 1, a central manifold valve group 2, a gas-solid separation unit 3, a three-way reversing unit 4, a particle size detection unit 5, a purging power unit 6, and a main control unit 7.

[0024] The multiple sampling branches 1 are the sampling units of the system, responsible for collecting coal powder samples from multiple coal powder pipelines and transporting them to the subsequent processing units. Each sampling branch 1 includes a sampling device installed on the primary air duct and a delivery pipeline connecting the device to the inlet of the central manifold valve group 2. As an example, in this embodiment, the system is configured with 16 sampling branches 1, installed on 16 coal powder pipelines of two coal mills. The input end of each sampling branch 1 is connected to the external primary air duct, and the output end is connected to multiple inlets of the central manifold valve group 2 through the delivery pipeline. The sampling branches 1 use high-temperature resistant and corrosion-resistant polytetrafluoroethylene (PTFE) flexible hoses, which are antistatic and non-stick, ensuring the flow stability in the coal powder pipelines.

[0025] The main function of the central manifold valve group 2 is to collect and transfer coal powder samples from multiple sampling branches 1 to the gas-solid separation unit 3. Each inlet is equipped with an electromagnetic on / off valve controlled by the main control unit 7 to ensure independent control of each sampling branch 1. By controlling the electromagnetic valves of the valve group 2, the main control unit 7 can precisely select which sampling branch to open, so that the coal powder samples can be guided to the subsequent units of the system according to the preset timing.

[0026] The central manifold valve assembly 2 includes 16 independent sampling ports, each connected to a corresponding sampling branch 1 via a solenoid valve. The main control unit 7 controls the solenoid valves to open and close the corresponding sampling ports, enabling independent sampling of multiple branches and reducing cross-contamination between different pulverized coal pipelines. The central manifold valve assembly 2 can employ a dead-angle-free flow channel design, enabling a pressure resistance of 1MPa and ensuring stable operation under high loads.

[0027] The main function of the gas-solid separation unit 3 is to separate solid particles and gas in the pulverized coal sample to ensure the accuracy of pulverized coal particle size measurement. The gas-solid separation unit 3 employs a highly efficient cyclone separation structure with a separation efficiency greater than 98%. The pulverized coal sample flows into the gas-solid separation unit 3 from the central manifold valve group 2. After cyclone separation, the pulverized coal particles and gas are effectively separated. The separated pulverized coal sample is then sent to the particle size detection unit 5 for particle size analysis.

[0028] In addition, the top of the gas-solid separation unit 3 is connected to a waste gas return pipeline, which is used to guide the separated gas back into the primary air duct through the return pipeline, thereby maintaining the pressure balance of the system and avoiding local pressure anomalies from affecting the stability of the coal powder sample. The bottom ash collection hopper of the gas-solid separation unit 3 is equipped with an ash discharge valve, which is controlled by the main control unit 7 to ensure that residual powder is cleaned up in a timely manner during system operation.

[0029] The three-way reversing unit 4 is used to switch the sample injection connection status between the particle size detection unit 5 and the gas-solid separation unit 3, or to switch the purging connection status between the purging power unit 6 and the common pipeline. The three-way reversing unit 4 is controlled by the main control unit 7, switching between different functions according to measurement and cleaning needs. During measurement, the three-way reversing unit 4 connects the gas-solid separation unit 3 and the particle size detection unit 5; during cleaning, it switches to the purging connection status, connecting the purging power unit 6 to the common pipeline for backflushing cleaning.

[0030] The particle size detection unit 5 is the core component of the system, responsible for measuring the particle size distribution of the coal powder sample. Using full-range laser diffraction and Mie light scattering theory, the particle size detection unit 5 can accurately measure the particle size of coal powder ranging from 0.5 μm to 3000 μm. The equipment employs a 16-bit sample resolution, with measurement accuracy controlled within ±2%, ensuring high precision of the particle size data.

[0031] The purging power unit 6 is used to clean the pipelines in the system, ensuring that the coal powder sample is not contaminated by residues after each measurement. The purging power unit 6 uses clean compressed air conforming to ISO 8573 standards to clean the coal powder pipelines through pulse purging, minimizing cross-contamination. The purging power unit 6 provides 4-6 bar of clean compressed air to purge the common path between the gas-solid separation unit 3 and the particle size detection unit 5 after each measurement, removing residual coal powder and particles.

[0032] The main control unit 7 is the core control unit of the system, responsible for coordinating and controlling the operation of various modules. Through a tablet-type industrial computer with configuration software, the main control unit 7 achieves automated control of all equipment and interacts with each device in real time via a fieldbus electrical connection. The main control unit 7 can precisely schedule the 16 sampling branches 1, the central manifold valve group 2, the gas-solid separation unit 3, the three-way reversing unit 4, the particle size detection unit 5, and the purging power unit 6 according to preset timing control logic. The system supports automated sampling, measurement, cleaning, and switching functions, effectively improving the efficiency and accuracy of coal powder particle size monitoring.

[0033] The particle size monitoring of pulverized coal pipelines in this application enables fully automatic, periodic, and cross-contamination-free online detection. It can be widely used in coal-fired power plants to improve the precision adjustment of boiler combustion, optimize the operating status of coal mills, and enhance the combustion efficiency and environmental friendliness of pulverized coal.

[0034] Example 2 In this embodiment, each inlet of the central manifold valve assembly 2 is equipped with an electromagnetic on / off valve independently controlled by the main control unit 7. The central manifold valve assembly 2 has 16 independent inlets, each corresponding to one of the 16 sampling branches 1. Each inlet is equipped with an electromagnetic on / off valve, and the main control unit 7 independently issues opening or closing control commands to achieve the individual conduction of designated sampling branches 1 and the isolation and closure of non-designated sampling branches 1.

[0035] Specifically, the central manifold valve assembly 2 adopts a dead-angle-free flow channel design and has a pressure-bearing capacity of 1MPa. In this embodiment, the main control unit 7 controls the electromagnetic opening and closing valve of the central manifold valve assembly 2 to open only the designated sampling branch inlet, allowing the pulverized coal sample to pass through the gas-solid separation unit 3 according to a preset time sequence before entering the particle size detection unit 5 for particle size measurement. This design ensures the independence of each pulverized coal pipeline sample, thereby improving the accuracy of the data.

[0036] To further improve system reliability, the solenoid valves of the central manifold 2 can also have a redundant design to avoid system downtime caused by the failure of a single solenoid valve. Each solenoid valve at the injection port is independently monitored and controlled by the main control unit 7, ensuring that the control signals for each injection port are accurate and timely during the sampling process.

[0037] Example 3 In this embodiment, the top of the gas-solid separation unit 3 is connected to a waste gas return pipeline, and the end of the waste gas return pipeline is led back to the external primary air duct to maintain system pressure balance and avoid local pressure imbalance caused by coal powder sample extraction. The bottom ash collection hopper of the gas-solid separation unit 3 is equipped with an ash discharge valve controlled by the main control unit 7.

[0038] The gas-solid separation unit 3 adopts a high-efficiency cyclone separation structure with a separation efficiency greater than 98%. Coal powder samples are collected by the central manifold valve group 2 and then enter the gas-solid separation unit 3, where solid particles are separated from the carrying airflow. The ash discharge valve is controlled by the main control unit 7 to open or close, releasing the separated residual powder during purging or residual discharge processes.

[0039] Furthermore, after the measurement is completed, the gas-solid separation unit 3 releases the residual powder in a timely manner by opening the ash discharge valve, and guides the returned gas back to the primary air duct through the exhaust gas return pipeline. This not only helps maintain the pressure balance of the system, but also reduces the energy loss of the system and improves the stability and reliability of the system operation.

[0040] In some embodiments of this application, the three-way reversing unit 4 is a reversing valve controlled by the main control unit 7, used to switch the sample injection conduction state between the particle size detection unit 5 and the gas-solid separation unit 3, or to switch the purging conduction state between the purging power unit 6 and the common pipeline. The output end of the gas-solid separation unit 3 is connected to the three-way reversing unit 4, and the particle size detection unit 5 and the purging power unit 6 are also connected to the three-way reversing unit 4 respectively. The three-way reversing unit 4 can be switched to two working states: (1) Measurement conduction state: In this state, the gas-solid separation unit 3 and the particle size detection unit 5 are connected. After the sample passes through the gas-solid separation, it enters the particle size detection unit 5 for particle size measurement.

[0041] (2) Purging and conduction state: In this state, the purging power unit 6 is connected to the common pipeline, the compressed gas is introduced into the common path, and the relevant flow path is back-flushed and cleaned.

[0042] During this process, the purging power unit 6 uses clean compressed air that meets ISO 8573 standards, with the pressure maintained between 4 and 6 Bar. The main control unit 7 switches the working state of the three-way reversing unit 4 through preset timing control logic, thereby achieving smooth switching between measurement and cleaning functions and ensuring long-term stable operation of the system.

[0043] Example 4 like Figure 2 The diagram shown is a flowchart illustrating a control method for a multi-branch coal powder particle size monitoring integrated system according to this application. This embodiment provides a control method for a multi-branch coal powder particle size monitoring integrated system, applied to the multi-branch coal powder particle size monitoring integrated system of this application. The method includes the following steps: Step S1: The main control unit 7 opens the sampling branch 1 with the specified sequence number and the corresponding central manifold valve group 2 inlet, so that the coal powder enters the particle size detection unit 5 after passing through the gas-solid separation unit 3 for particle size data acquisition.

[0044] Step S2: The main control unit 7 closes the sample inlet corresponding to the central manifold valve group 2 to complete the particle size measurement of the current branch.

[0045] In step S3, the main control unit 7 controls the three-way reversing unit 4 to connect to the purging power unit 6 and turn on the purging power unit 6 to purge the front side of the particle size detection unit 5. At the same time, the exhaust gas and residual powder are separated from the gas-solid separation unit 3 and discharged back into the corresponding primary air duct.

[0046] Step S4: The main control unit 7 continuously determines whether the conditions for opening the next set of sampling branches 1 are met within the common path, and completes the cross-branch switching.

[0047] It should be noted that in some embodiments of the control method of the multi-branch coal powder particle size monitoring integrated system of this application, before step S1, the method further includes: retrieving the real-time shading rate data of the particle size detection unit 5 through the main control unit 7; if the shading rate is higher than the preset background threshold, then starting the purging power unit 6 to purge the front end of the particle size detection unit until the shading rate drops to less than or equal to the preset background threshold.

[0048] In this step, the background occlusion rate Db of the particle size detection unit 5 is monitored in real time, and the main control unit 7 compares Db with the preset background threshold D0. When Db>D0, it indicates that there are residual particles in the system and the preset cleaning standard has not been met. At this time, the main control unit 7 will instruct the purging power unit 6 to perform global pulse purging until Db≤D0.

[0049] In addition, the method for separating exhaust gas and residual powder from gas-solid separation unit 3 includes: discharging the separated exhaust gas and residual powder back into the primary air duct by opening the ash discharge valve at the bottom of gas-solid separation unit 3.

[0050] By opening the ash discharge valve, the main control unit 7 controls the timely discharge of the separated residual powder, and sends the exhaust gas back to the primary air duct through the return pipeline. This avoids the risk of sample contamination and improves the economy and stability of the system.

[0051] In some embodiments of this application, the activation condition in step S4 may include: whether a particulate matter residual signal is detected in the common path; if there is no particulate matter residual signal and the shading rate is reset, then the next set of sampling branches 1 is allowed to be activated.

[0052] The main control unit 7 monitors the cleanliness of the common path in real time, and determines whether the opening conditions are met by using shading rate data and particulate matter residue signals, ensuring that the common path is completely clean when switching across branches, so as to ensure the accuracy of subsequent measurements.

[0053] The particle size detection unit 5 employs full-range laser diffraction and Mie light scattering theory for measurement. By combining these two technologies, the particle size detection unit 5 can perform full-range particle size measurement on coal powder samples, with measurement accuracy controlled within ±2%. The equipment has a 16-bit sample resolution, meeting the detection requirements for coal powder particle sizes ranging from 0.5 μm to 3000 μm.

[0054] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A multi-branch coal powder particle size monitoring integrated system, characterized in that: It includes a main control unit (7), and a central manifold valve group (2), a gas-solid separation unit (3), a three-way reversing unit (4), a particle size detection unit (5), a purging power unit (6), a main control unit (7), and multiple sampling branches (1) that are electrically connected to the main control unit (7); The input ends of the multiple sampling branches (1) are respectively connected to an external primary air duct, and the output ends of the multiple sampling branches (1) are respectively connected to the multiple inlets of the central manifold valve group (2); the total outlet of the central manifold valve group (2) is connected to the input end of the gas-solid separation unit (3). The first channel of the three-way reversing unit is connected to the output end of the gas-solid separation unit (3), the second channel is connected to the purging power unit (6), and the third channel is connected to the particle size detection unit.

2. The multi-branch coal powder particle size monitoring integrated system according to claim 1, characterized in that: Each of the multiple sampling branches (1) includes a sampling device installed on the primary air duct, and a delivery pipeline connecting the sampling device to the inlet of the central manifold valve group (2).

3. The multi-branch coal powder particle size monitoring integrated system according to claim 1, characterized in that: Each inlet of the central manifold valve group (2) is equipped with an electromagnetic on / off valve that is independently controlled by the main control unit (7).

4. The multi-branch coal powder particle size monitoring integrated system according to claim 1, characterized in that: The top of the gas-solid separation unit (3) is connected to a waste gas return pipeline, and the end of the waste gas return pipeline is led back to the external primary air duct. The bottom ash collection hopper of the gas-solid separation unit (3) is equipped with an ash storage and unloading valve controlled by the main control unit (7).

5. The multi-branch coal powder particle size monitoring integrated system according to claim 1, characterized in that: The three-way reversing unit (4) is a reversing valve controlled by the main control unit (7), used to switch the sample feeding conduction state between the particle size detection unit (5) and the gas-solid separation unit (3), or to switch the purging conduction state between the purging power unit (6) and the common pipeline.

6. A control method for a multi-branch coal powder particle size monitoring integrated system, applied to the multi-branch coal powder particle size monitoring integrated system according to any one of claims 1 to 5, characterized in that, include: S1, the sampling branch (1) with the specified sequence number and the corresponding central manifold valve group (2) inlet are opened by the main control unit (7) so that the coal powder enters the particle size detection unit (5) after passing through the gas-solid separation unit (3) to collect particle size data. S2, the main control unit (7) closes the injection port corresponding to the central manifold valve group (2); S3, through the main control unit (7) control the three-way reversing unit (4) to connect to the purging power unit (6) and turn on the purging power unit (6) to purge the front side of the particle size detection unit (5), and at the same time separate the exhaust gas and residual powder from the gas-solid separation unit (3) and discharge them back into the corresponding primary air duct; S4, the main control unit (7) continuously determines whether the conditions for opening the next set of sampling branches (1) are met in the common path, and completes the cross-branch switching; the common path includes the flow path between the central manifold valve group (2) and the particle size detection unit (5).

7. The control method of the multi-branch coal powder particle size monitoring integrated system according to claim 6, characterized in that, Before step S1, the method further includes: The main control unit (7) retrieves the real-time shading rate data of the particle size detection unit (5). If the shading rate is higher than the preset background threshold, the purging power unit (6) is started to purge the front end of the particle size detection unit until the shading rate drops to less than or equal to the preset background threshold.

8. The control method of the multi-branch coal powder particle size monitoring integrated system according to claim 6, characterized in that, The method for separating exhaust gas and residual powder from the gas-solid separation unit (3) includes: discharging the separated exhaust gas and residual powder back into the primary air duct by opening the ash discharge valve at the bottom of the gas-solid separation unit (3).

9. The control method of the multi-branch coal powder particle size monitoring integrated system according to claim 6, characterized in that, In step S4, the activation conditions include: If no residual particulate matter signal is detected in the common path and the shading rate is reset, then the next set of sampling branches can be opened (1).

10. The control method of the multi-branch coal powder particle size monitoring integrated system according to claim 6, characterized in that, The particle size detection unit (5) uses full-range laser diffraction and Mie light scattering theory for measurement.

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