Online particulate matter diluting, sampling and measuring system and method

Abstract

The invention relates to the field of particulate matter detection, and discloses a particulate matter online diluting, sampling and measuring system and method.The particulate matter online diluting, sampling and measuring system comprises a particulate matter pre-separation module used for conducting particle size grading on sampled flue gas; the multi-stage dilution module is connected with the particulate matter pre-separation module and is used for carrying out at least two-stage dilution on the graded flue gas; the ionization and online measurement module is connected with the multi-stage dilution module and is used for charging particulate matters in the diluted flue gas and measuring the concentration of the particulate matters in real time; the particulate matter filtering module is connected with the ionization and on-line measurement module and is used for capturing particulate matters flowing through the ionization and on-line measurement module; the gas source and distribution module is used for generating and distributing multiple paths of clean gas flows and respectively providing the clean gas flows to the multi-stage dilution module and the ionization and online measurement module; the online real-time accurate measurement of the particulate matter concentration is realized, and the hysteresis problem of traditional offline sampling is thoroughly solved.

Description

Technical Field

[0001] This invention relates to the field of particulate matter detection, and in particular to an online dilution sampling and measurement system and method for particulate matter. Background Technology

[0002] Accurate sampling and detection of particulate matter in flue gas is crucial for studying pollutant formation mechanisms, evaluating the performance of control technologies, and conducting atmospheric source apportionment. Currently, particulate matter is classified into trappable and condensable particles. Domestic mainstream sampling and measurement methods primarily rely on the aerodynamic or filtration characteristics of particulate matter, essentially operating on an "online sampling, offline analysis" model. While widely used, this method has inherent limitations: it cannot acquire concentration data in real time, making it difficult to promptly detect and correct sampling errors caused by uneven flue gas concentration distribution and isokinetic sampling bias. This non-real-time limitation is particularly pronounced for coal-fired power units aiming for ultra-low emissions, where particulate matter concentrations in the tail gas are extremely low and operating conditions are prone to fluctuation. Existing technologies have not yet solved the problem of real-time measurement, resulting in a heavy sampling workload and a high risk of missing optimal sampling opportunities when unit loads are unstable, ultimately leading to measurement results that do not accurately reflect actual emission levels. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is that the existing particulate matter sampling and measurement technology system cannot achieve real-time, online feedback and control of concentration under complex working conditions, resulting in lag in the measurement process and risk of deviation in the results.

[0004] The above-mentioned technical problems are solved by the following technical solution: This invention proposes an online particulate matter dilution sampling and measurement system, which includes, The particulate matter pre-separation module is used to classify the sampled flue gas by particle size. A multi-stage dilution module, connected to the particulate pre-separation module, is used to dilute the graded flue gas in at least two stages. An ionization and online measurement module, connected to the multi-stage dilution module, is used to charge the particulate matter in the diluted flue gas and measure its concentration in real time. A particulate matter filtration module, connected to the ionization and online measurement module, is used to capture flowing particulate matter; The gas source and distribution module is used to generate and distribute multiple clean airflows to the multi-stage dilution module and the ionization and online measurement module, respectively. Specifically, the sampled flue gas first enters the particulate pre-separation module for particle size classification to remove large, interfering particles. The pre-treated flue gas then enters the multi-stage dilution module, where at least two dilution processes are required to simulate the state of the flue gas after it is discharged into the atmosphere, achieving cooling and concentration regulation. The fully diluted flue gas then enters the ionization and online measurement module, where the particles are charged and generate electrical signals that can be measured in real time. After the measurement is completed, the flue gas is finally captured by the particulate filtration module. Throughout the entire process, the gas source and distribution module continuously provides the system with multiple clean and stable dilution gas flows and ionization gas.

[0005] In a preferred embodiment of the online particulate matter dilution sampling and measurement system of the present invention: the particulate matter pre-separation module includes PM 10 Cyclone cutter, PM 2.5 Cyclone cutter and sampling airflow meter; the PM 10 The inlet of the cyclone cutter is used to receive the sampled flue gas, and its outlet is connected to the PM. 2.5 The air inlet of the cyclone cutter; the PM 2.5 The air outlet of the cyclone cutter is connected to the flue gas inlet of the multi-stage dilution module via a pipeline, and the sampling airflow meter is installed on the pipeline connected to the multi-stage dilution module; Specifically, the flue gas first passes through the PM 10 The cyclone cutter uses centrifugal force to separate and collect particles larger than 10 micrometers. The preliminarily purified flue gas then enters the PM2.5 system. 2.5 In the cyclone cutter, particles of 2.5 to 10 micrometers are further separated and collected. This pre-separation process can effectively remove coarse particles that may clog subsequent pipelines or interfere with measurements; while the sampling airflow meter monitors the flow rate of flue gas entering the dilution module in real time.

[0006] In a preferred embodiment of the particulate matter online dilution sampling and measurement system of the present invention: the multi-stage dilution module includes a primary diluent and a secondary diluent; the PM 2.5 The outlet of the cyclone cutter is connected to the flue gas inlet of the first-stage diluent via the sampling airflow meter; the mixed flue gas outlet of the first-stage diluent is connected to the sampling airflow inlet pipe of the second-stage diluent; the second-stage dilution airflow outlet of the first-stage diluent is connected to the second-stage dilution airflow inlet pipe of the second-stage diluent, and a second-stage dilution airflow pressure gauge is installed at the second-stage dilution airflow outlet of the first-stage diluent. Specifically, the pre-separated flue gas first enters the primary diluent for initial dilution and cooling. Then, the initially diluted mixed flue gas and a portion of the secondary dilution gas flow from the primary diluent are introduced into the secondary diluent through pipelines for secondary mixing and deep dilution. The secondary dilution gas flow pressure gauge is used to monitor the pressure status of the gas path in real time, and combined with the flow rate data, provides accurate data for the total dilution ratio.

[0007] In a preferred embodiment of the particulate matter online dilution sampling and measurement system of the present invention: the primary diluent is a concentric four-layer cylindrical structure, with the first to fourth layers of cylinders arranged from the inside to the outside; The first cylindrical shell has a fully enclosed microporous stainless steel wall, with a flue gas inlet and a mixed flue gas outlet at each end. The second-layer cylinder has a fully enclosed stainless steel wall and a primary dilution airflow inlet at the end. The third-layer cylinder has a semi-enclosed stainless steel wall and is equipped with the secondary dilution gas outlet at its end; The fourth-layer cylinder has a fully enclosed stainless steel wall and a secondary dilution airflow inlet at the end; Specifically, the innermost first cylinder, with its microporous wall, allows the primary dilution airflow to penetrate evenly and mix thoroughly and gently with the sampling flue gas flowing through the center, avoiding particulate matter loss caused by turbulence. The second, third, and fourth cylinders respectively constitute the cavity for the primary dilution airflow, the outlet channel for the secondary dilution airflow, and the inlet cavity for the secondary dilution airflow. This multi-layered opposing flow structure not only achieves preliminary mixing of the airflow but also significantly improves the overall cooling efficiency of the system through interlayer heat exchange.

[0008] In a preferred embodiment of the particulate matter online dilution sampling and measurement system of the present invention: the air inlet of the secondary diluent is divided into a sampling airflow inlet pipe and a secondary dilution airflow inlet pipe; the end of the sampling airflow inlet pipe is a conical structure, and the conical structure is located at the center of the internal cavity inlet of the secondary diluent and perpendicularly intersects with the secondary dilution airflow inlet pipe; the sampling airflow inlet pipe and the internal cavity inlet of the secondary diluent form a gradually narrowing and expanding nozzle-shaped airflow channel; Specifically, the end of the sampling airflow inlet pipe of the secondary diluter is designed as a cone located in the center of the cavity. When the high-speed secondary dilution airflow flows vertically through the cone, a low-pressure zone is formed behind it. The ejector effect generated by this low-pressure zone can actively and uniformly draw the flue gas from the primary diluter into the mainstream and mix it with it in a violent turbulent manner, thereby ensuring the uniformity and efficiency of the secondary dilution without the need for additional power.

[0009] In a preferred embodiment of the particulate matter online dilution sampling and measurement system of the present invention: the ionization and online measurement module includes a dry clean gas flow ionization device, a charged particle measurement device, and a data processor; the outlet of the secondary diluter is connected to the junction of the dry clean gas flow ionization device and the charged particle measurement device; the dry clean gas flow ionization device adopts a corona needle tip discharge structure; the inlet end of the charged particle measurement device and the outlet end of the dry clean gas flow ionization device are arranged opposite to each other to form a tapered nozzle structure, the internal cavity of which adopts an ion trap structure and is equipped with a current measurement device; the data processor is communicatively connected to the current measurement device; Specifically, the diluted flue gas from the secondary diluter converges at the converging nozzle formed by the dry clean gas ionization device and the charged particle measuring device. The high concentration of positive ions generated by the dry clean gas ionization device mixes thoroughly with the flue gas, causing the particles to rapidly become charged. The charged particles then enter the ion trap of the charged particle measuring device with the airflow, generating an induced current through the Faraday cup effect. Once this current signal is captured, the data processor calculates and directly outputs the particle concentration value in real time, thereby achieving continuous online measurement.

[0010] In a preferred embodiment of the particulate matter online dilution sampling and measurement system of the present invention: the particulate matter filtration module includes a particulate matter filter, a flue gas flow meter, a flue gas flow control valve and a sampling pump connected in sequence through pipelines; the air inlet of the particulate matter filter is connected to the outlet end of the charged particle measuring device; Specifically, the flue gas after concentration measurement enters the particulate filter, where residual particulate matter is completely captured by the high-efficiency filter membrane, ensuring the integrity of the sampling process and preserving samples for offline comparative analysis. Subsequently, the flue gas flows sequentially through the flue gas flow meter and the airflow control valve to monitor the total exhaust flow of the system to verify the operating status, and to accurately control and maintain the sampling flow required by the system. The sampling pump provides constant suction power for the entire system, ensuring stable airflow.

[0011] In a preferred embodiment of the particulate matter online dilution sampling and measurement system of the present invention: the air source and distribution module includes an air compressor, a compressed air buffer and processing device, and a compressed air control valve; the compressed air control valve is installed on the pipeline connecting the air compressor and the compressed air buffer and processing device; The outlet of the compressed air buffer and processing device is divided into a dry and clean airflow path, a primary dilution airflow path, and a secondary dilution airflow path. A dry and clean airflow control valve and a dry and clean airflow flow meter are installed on the dry and clean airflow path. A primary dilution airflow control valve and a primary dilution airflow flow meter are installed on the primary dilution airflow path. A secondary dilution airflow control valve and a secondary dilution airflow flow meter are installed on the secondary dilution airflow path. Specifically, the compressed air provided by the air compressor is purified and dried by the compressed air buffer and treatment device, and the total flow rate is regulated by the compressed air control valve located on the pipeline. The clean air is then distributed to three independent branches: a dry clean airflow, a primary dilution airflow, and a secondary dilution airflow. Each branch is independently and precisely regulated by its own control valve and flow meter, thereby ensuring that each part of the system receives a stable and accurate airflow supply.

[0012] The present invention also provides an online dilution sampling and measurement method for particulate matter, including the aforementioned online dilution sampling and measurement system for particulate matter, and further comprising the following steps: Particulate matter pre-separation is performed on the sampled flue gas to remove large-diameter particles; The pre-separated sampled flue gas was diluted and cooled step by step using a multi-stage dilution device; The diluted sampled flue gas is mixed with a stream of charged ions generated by ionization to charge the particulate matter, and the charge signal is measured to obtain concentration information. The flue gas, after concentration measurement, is filtered and collected before being discharged.

[0013] In a preferred embodiment of the particulate matter online dilution sampling and measurement method of the present invention: in the dilution step, the flow rate of the primary dilution airflow is controlled to be 1.5 times the flow rate of the sampling flue gas; by monitoring the pressure of the secondary dilution airflow and adjusting its flow rate, the total dilution ratio of the system is controlled to be greater than 20 times; at the same time, the total residence time of the sampling flue gas from entering the system to completing the dilution is controlled to be greater than 10 seconds, and the temperature of the diluted flue gas is kept below 42°C. Specifically, in the dilution step, a stable and reliable primary dilution ratio was established by controlling the flow rate of the primary dilution gas to 1.5 times that of the sampling flue gas. By monitoring the pressure of the secondary dilution gas and adjusting its flow rate, the total dilution ratio of the system was precisely controlled and maintained above 20 times. High-ratio dilution ensures that condensable particulate matter is fully formed and avoids overlapping interference between particles. At the same time, the total residence time of the sampling flue gas during the entire dilution process was controlled to be greater than 10 seconds and the temperature to be lower than 42°C. These two parameters ensure that the gaseous precursors have sufficient time and suitable conditions to complete condensation and growth, thereby ensuring that the final measurement results can truly reflect the potential emission level of condensable particulate matter.

[0014] The beneficial effects of this invention are: through PM10 Cyclone Cutter and PM 2.5 The system employs a cyclone cutter for pre-separation, a primary diluent and a secondary diluent for controlled dilution and cooling, a dry and clean airflow ionization device and a charged particle measurement device for particle charging and real-time measurement, a data processor for instant concentration feedback, and a particulate filter for final collection. This system achieves accurate online real-time measurement of particulate matter concentration, completely overcoming the lag problem of traditional offline sampling. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0016] Figure 1 A schematic diagram of the overall process of the present invention is shown. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0018] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0019] Reference Figure 1 This embodiment provides an online particulate matter dilution sampling and measurement system, which includes: Particulate matter pre-separation module 1 is used to classify the sampled flue gas by particle size. The multi-stage dilution module 2 is connected to the particulate pre-separation module 1 and is used to dilute the graded flue gas in at least two stages. The ionization and online measurement module 3 is connected to the multi-stage dilution module 2 and is used to charge the particulate matter in the diluted flue gas and measure its concentration in real time. The particulate matter filtration module 4 is connected to the ionization and online measurement module 3 and is used to capture the flowing particulate matter. The gas source and distribution module 5 is used to generate and distribute multiple clean airflows, which are respectively provided to the multi-stage dilution module 2 and the ionization and online measurement module 3; Specifically, the sampled flue gas first enters the particulate pre-separation module 1 for particle size classification to remove large interfering particles. The pre-treated flue gas then enters the multi-stage dilution module 2, where at least two dilution processes are required to simulate the state of the flue gas after it is discharged into the atmosphere, achieving cooling and concentration regulation. The fully diluted flue gas then enters the ionization and online measurement module 3, where the particles are charged and generate electrical signals that can be measured in real time. After the measurement is completed, the flue gas passes through the particulate filter module 4 for final collection. Throughout the entire process, the gas source and distribution module 5 continuously provides the system with multiple clean and stable dilution gas flows and ionization gas.

[0020] Particulate matter pre-separation module 1 includes PM 10 Cyclone Cutter 11, PM 2.5 Cyclone cutter 12 and sampling airflow meter 13; PM 10 The inlet of the cyclone cutter 11 is used to receive the sampled flue gas, and its outlet is connected to PM. 2.5 The air inlet of the cyclone cutter 12; PM 2.5 The outlet of the cyclone cutter 12 is connected to the flue gas inlet of the multi-stage dilution module 2 via a pipeline, and the sampling flow meter 13 is installed on the pipeline connected to the multi-stage dilution module 2. Specifically, the flue gas first passes through PM2.5 10 Cyclone cutter 11 uses centrifugal force to separate and collect particles larger than 10 micrometers. The preliminarily purified flue gas then enters the PM2.5 system. 2.5 In the cyclone cutter 12, particles of 2.5 to 10 micrometers are further separated and collected. This pre-separation process can effectively remove coarse particles that may clog subsequent pipelines or interfere with measurements; while the sampling airflow meter 13 monitors the flue gas flow rate entering the dilution module in real time.

[0021] Multi-stage dilution module 2 includes a primary diluent 21 and a secondary diluent 22; PM 2.5 The outlet of the cyclone cutter 12 is connected to the flue gas inlet of the first-stage diluter 21 via a sampling airflow meter 13; the mixed flue gas outlet of the first-stage diluter 21 is connected to the sampling airflow inlet pipe of the second-stage diluter 22; the secondary dilution airflow outlet of the first-stage diluter 21 is connected to the secondary dilution airflow inlet pipe of the second-stage diluter 22, and a secondary dilution airflow pressure gauge 23 is installed at the secondary dilution airflow outlet of the first-stage diluter 21. Specifically, the pre-separated flue gas first enters the primary diluent 21 for initial dilution and cooling. Then, the mixed flue gas after initial dilution and part of the secondary dilution gas flow from the primary diluent 21 are introduced into the secondary diluent 22 through pipelines for secondary mixing and deep dilution. The secondary dilution gas flow pressure gauge 23 is used to monitor the pressure status of the gas path in real time and, combined with the flow data, provide accurate data for the total dilution ratio.

[0022] The primary diluent 21 has a concentric four-layer cylindrical structure, with the first to fourth layers of cylinders arranged from the inside out. The first cylindrical shell has a fully enclosed microporous stainless steel wall, with a flue gas inlet and a mixed flue gas outlet at each end. The second-layer cylinder has a fully enclosed stainless steel wall and a primary dilution airflow inlet at the end. The third-layer cylinder has a semi-enclosed stainless steel wall and a secondary dilution gas outlet at the end. The fourth-layer cylinder has a fully enclosed stainless steel wall and a secondary dilution airflow inlet at the end; Specifically, the innermost first cylinder, with its microporous wall, allows the primary dilution airflow to penetrate evenly and mix thoroughly and gently with the sampling flue gas flowing through the center, avoiding particulate matter loss caused by turbulence. The second, third, and fourth cylinders respectively constitute the cavity for the primary dilution airflow, the outlet channel for the secondary dilution airflow, and the inlet cavity for the secondary dilution airflow. This multi-layered opposing flow structure not only achieves preliminary mixing of the airflow but also significantly improves the overall cooling efficiency of the system through interlayer heat exchange.

[0023] The air inlet of the secondary diluter 22 is divided into a sampling airflow inlet pipe and a secondary dilution airflow inlet pipe. The end of the sampling airflow inlet pipe is a conical structure, and the conical structure is located in the center of the internal cavity inlet of the secondary diluter 22 and intersects the secondary dilution airflow inlet pipe perpendicularly. The sampling airflow inlet pipe and the internal cavity inlet of the secondary diluter 22 form an airflow channel in the form of a gradually narrowing and expanding nozzle. Specifically, the end of the sampling airflow inlet pipe of the secondary diluter 22 is designed as a cone located in the center of the cavity. When the high-speed secondary dilution airflow flows vertically through the cone, a low-pressure zone is formed behind it. The ejector effect generated by this low-pressure zone can actively and uniformly draw the flue gas from the primary diluter 21 into the mainstream and mix it with it in a violent turbulent manner, thereby ensuring the uniformity and efficiency of the secondary dilution without the need for additional power.

[0024] The ionization and online measurement module 3 includes a dry clean gas flow ionization device 31, a charged particle measuring device 32, and a data processor 33; the outlet of the secondary diluter 22 is connected to the junction of the dry clean gas flow ionization device 31 and the charged particle measuring device 32; the dry clean gas flow ionization device 31 adopts a corona needle tip discharge structure; the inlet end of the charged particle measuring device 32 and the outlet end of the dry clean gas flow ionization device 31 are arranged opposite to each other to form a gradually narrowing nozzle structure, and its internal cavity adopts an ion trap structure and is equipped with a current measuring device; the data processor 33 is communicatively connected to the current measuring device. Specifically, the diluted flue gas from the secondary diluter 22 converges at the converging nozzle formed by the dry clean gas ionization device 31 and the charged particle measuring device 32. The high concentration of positive ions generated by the dry clean gas ionization device 31 mixes thoroughly with the flue gas here, causing the particles in it to quickly become charged. The charged particles enter the ion trap of the charged particle measuring device 32 with the airflow, and generate an induced current through the Faraday cup effect. After the current signal is captured, the data processor 33 calculates and directly outputs the particle concentration value in real time, thereby realizing continuous online measurement.

[0025] The particulate matter filtration module 4 includes a particulate matter filter 41, a flue gas flow meter 42, a flue gas flow control valve 43, and a sampling pump 44 connected in sequence through pipelines; the inlet of the particulate matter filter 41 is connected to the outlet of the charged particle measuring device 32. Specifically, the flue gas after concentration measurement enters the particulate filter 41, where residual particulate matter is completely captured by the high-efficiency filter membrane, ensuring the integrity of the sampling process and preserving the sample for offline comparative analysis. Subsequently, the flue gas flows sequentially through the flue gas flow meter 42 and the airflow control valve 43 to monitor the total exhaust flow of the system to verify the operating status, and to accurately control and maintain the sampling flow required by the system. Meanwhile, the sampling pump 44 provides constant suction power for the entire system, ensuring stable airflow.

[0026] The air source and distribution module 5 includes an air compressor 51, a compressed air buffer and processing device 52, and a compressed air control valve 53; the compressed air control valve 53 is installed on the pipeline connecting the air compressor 51 and the compressed air buffer and processing device 52. The outlet of the compressed air buffer and processing device 52 is divided into a dry and clean airflow path, a primary dilution airflow path, and a secondary dilution airflow path. A dry and clean airflow control valve 54 and a dry and clean airflow flow meter 55 are installed on the dry and clean airflow path. A primary dilution airflow control valve 56 and a primary dilution airflow flow meter 57 are installed on the primary dilution airflow path. A secondary dilution airflow control valve 58 and a secondary dilution airflow flow meter 59 are installed on the secondary dilution airflow path. Specifically, the compressed air provided by the air compressor 51 is purified and dried by the compressed air buffer and treatment device 52, and the total flow rate is regulated by the compressed air control valve 53 located on the pipeline. The clean air is then distributed to three independent branches: the dry clean airflow, the primary dilution airflow, and the secondary dilution airflow. Each branch is independently and precisely regulated by its own control valve and flow meter, thereby ensuring that each part of the system receives a stable and accurate airflow supply.

[0027] As one embodiment provided, such as Figure 1 A method for online dilution sampling and measurement of particulate matter is provided, including an online dilution sampling and measurement system for particulate matter, and further comprising the following steps: Particulate matter pre-separation is performed on the sampled flue gas to remove large-diameter particles; The pre-separated sampled flue gas was diluted and cooled step by step using a multi-stage dilution device; The diluted sampled flue gas is mixed with a stream of charged ions generated by ionization to charge the particulate matter, and the charge signal is measured to obtain concentration information. The flue gas, after concentration measurement, is filtered and collected before being discharged.

[0028] In a preferred embodiment of the particulate matter online dilution sampling and measurement method of the present invention: in the dilution step, the flow rate of the primary dilution airflow is controlled to be 1.5 times the flow rate of the sampling flue gas; by monitoring the pressure of the secondary dilution airflow and adjusting its flow rate, the total dilution ratio of the system is controlled to be greater than 20 times; at the same time, the total residence time of the sampling flue gas from entering the system to completing the dilution is controlled to be greater than 10 seconds, and the temperature of the diluted flue gas is kept below 42°C. Specifically, in the dilution step, a stable and reliable primary dilution ratio was established by controlling the flow rate of the primary dilution gas to 1.5 times that of the sampling flue gas. By monitoring the pressure of the secondary dilution gas and adjusting its flow rate, the total dilution ratio of the system was precisely controlled and maintained above 20 times. High-ratio dilution ensures that condensable particulate matter is fully formed and avoids overlapping interference between particles. At the same time, the total residence time of the sampling flue gas during the entire dilution process was controlled to be greater than 10 seconds and the temperature to be lower than 42°C. These two parameters ensure that the gaseous precursors have sufficient time and suitable conditions to complete condensation and growth, thereby ensuring that the final measurement results can truly reflect the potential emission level of condensable particulate matter.

[0029] In summary, the sampled flue gas first flows through PM 10 Cyclone Cutter 11 and PM 2.5Cyclone cutter 12 performs series pre-separation, effectively removing large-diameter particles and avoiding subsequent pipeline blockage and measurement interference. The pre-treated flue gas is supplied by air compressor 51 and purified by compressed air buffer and treatment device 52. The clean airflow then enters the primary diluter 21. Subsequently, the initially diluted mixed flue gas and the secondary dilution airflow enter the secondary diluter 22. The conical structure at the end of the sampling airflow inlet pipe and the tapered nozzle channel utilize the Venturi effect to generate a low-pressure zone, passively entraining the flue gas and causing violent turbulent mixing with the secondary dilution airflow to achieve deep and uniform dilution. This process is monitored by secondary dilution airflow pressure gauge 23 to ensure that the total dilution ratio is greater than 20 times, the residence time is greater than 10 seconds, and the temperature is below 42°C, thereby effectively simulating the atmospheric environment. This process promotes the formation of condensable particulate matter. The fully diluted flue gas converges at the converging nozzle formed by the dry clean gas ionization device 31 and the charged particle measuring device 32. The dry clean gas ionization device 31 rapidly charges the particulate matter with high-concentration positive ions generated by corona discharge. The charged particles enter the ion trap of the charged particle measuring device 32 with the airflow, generating an induced current based on the Faraday cup effect. This signal is captured and the data processor 33 calculates and outputs the particulate matter concentration in real time, achieving online instantaneous measurement and feedback of the concentration. After measurement, the flue gas is finally captured by the particulate filter 41, ensuring sampling integrity and providing samples for offline analysis. The flue gas flow meter 42, flue gas flow control valve 43, and sampling pump 44 work together to maintain system flow stability. Throughout the process, independent and precise control of multiple airflows is achieved through control valves and flow meters on each branch. Through these steps, efficient and stable online measurement of collectable and condensable particulate matter is achieved, effectively overcoming the lag problem of traditional offline sampling, and the measurement results are accurate and reliable.

[0030] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. An online dilution sampling and measurement system for particulate matter, characterized in that: include, Particulate matter pre-separation module (1) is used to classify the sampled flue gas by particle size; A multi-stage dilution module (2) is connected to the particulate matter pre-separation module (1) and is used to dilute the graded flue gas in at least two stages. The ionization and online measurement module (3) is connected to the multi-stage dilution module (2) and is used to charge the particulate matter in the diluted flue gas and measure its concentration in real time. The particulate matter filtration module (4) is connected to the ionization and online measurement module (3) and is used to capture the flowing particulate matter; The gas source and distribution module (5) is used to generate and distribute multiple clean airflows to the multi-stage dilution module (2) and the ionization and online measurement module (3), respectively.

2. The particulate matter online dilution sampling and measurement system according to claim 1, characterized in that: The particulate matter pre-separation module (1) includes PM 10 Cyclone Cutter (11), PM 2.5 Cyclone cutter (12) and sampling airflow meter (13); the PM 10 The inlet of the cyclone cutter (11) is used to access the sampled flue gas, and its outlet is connected to the PM. 2.5 The air inlet of the cyclone cutter (12); the PM 2.5 The outlet of the cyclone cutter (12) is connected to the flue gas inlet of the multi-stage dilution module (2) via a pipeline, and the sampling flow meter (13) is installed on the pipeline connected to the multi-stage dilution module (2).

3. The particulate matter online dilution sampling and measurement system according to claim 2, characterized in that: The multi-stage dilution module (2) includes a primary diluent (21) and a secondary diluent (22); the PM 2.5 The outlet of the cyclone cutter (12) is connected to the flue gas inlet of the first-stage diluent (21) through the sampling airflow meter (13); the mixed flue gas outlet of the first-stage diluent (21) is connected to the sampling airflow inlet pipe of the second-stage diluent (22); the second-stage dilution airflow outlet of the first-stage diluent (21) is connected to the second-stage dilution airflow inlet pipe of the second-stage diluent (22), and a second-stage dilution airflow pressure gauge (23) is installed at the second-stage dilution airflow outlet of the first-stage diluent (21).

4. The particulate matter online dilution sampling and measurement system according to claim 3, characterized in that: The primary diluent (21) is a concentric four-layer cylindrical structure, consisting of the first to fourth layers of cylinders from the inside out; The first cylindrical shell has a fully enclosed microporous stainless steel wall, with a flue gas inlet and a mixed flue gas outlet at each end. The second-layer cylinder has a fully enclosed stainless steel wall and a primary dilution airflow inlet at the end. The third-layer cylinder has a semi-enclosed stainless steel wall and is equipped with the secondary dilution gas outlet at its end; The fourth-layer cylinder has a fully enclosed stainless steel wall and a secondary dilution airflow inlet at its end.

5. The particulate matter online dilution sampling and measurement system according to claim 3 or 4, characterized in that: The air inlet of the secondary diluter (22) is divided into a sampling airflow inlet pipe and a secondary dilution airflow inlet pipe. The end of the sampling airflow inlet pipe is a conical structure, and the conical structure is located in the center of the internal cavity inlet of the secondary diluter (22) and intersects the secondary dilution airflow inlet pipe perpendicularly. The sampling airflow inlet pipe and the internal cavity inlet of the secondary diluter (22) form a gradually narrowing nozzle-shaped airflow channel.

6. The particulate matter online dilution sampling and measurement system according to claim 5, characterized in that: The ionization and online measurement module (3) includes a dry clean gas flow ionization device (31), a charged particle measuring device (32), and a data processor (33); the outlet of the secondary diluter (22) is connected to the junction of the dry clean gas flow ionization device (31) and the charged particle measuring device (32); the dry clean gas flow ionization device (31) adopts a corona needle tip discharge structure; the inlet end of the charged particle measuring device (32) and the outlet end of the dry clean gas flow ionization device (31) are arranged opposite to each other to form a gradually expanding nozzle structure, and its internal cavity adopts an ion trap structure and is equipped with a current measuring device; the data processor (33) is communicatively connected to the current measuring device.

7. The particulate matter online dilution sampling and measurement system according to claim 6, characterized in that: The particulate matter filtration module (4) includes a particulate matter filter (41), a flue gas flow meter (42), a flue gas flow control valve (43), and a sampling pump (44) connected in sequence through pipelines; the air inlet of the particulate matter filter (41) is connected to the outlet of the charged particle measuring device (32).

8. The particulate matter online dilution sampling and measurement system according to claim 6 or 7, characterized in that: The air source and distribution module (5) includes an air compressor (51), a compressed air buffer and processing device (52), and a compressed air control valve (53); the compressed air control valve (53) is installed on the pipeline connecting the air compressor (51) and the compressed air buffer and processing device (52); The compressed air buffer and processing device (52) has an outlet end divided into a dry and clean airflow path, a primary dilution airflow path and a secondary dilution airflow path. A dry and clean airflow control valve (54) and a dry and clean airflow flow meter (55) are installed on the dry and clean airflow path. A primary dilution airflow control valve (56) and a primary dilution airflow flow meter (57) are installed on the primary dilution airflow path. A secondary dilution airflow control valve (58) and a secondary dilution airflow flow meter (59) are installed on the secondary dilution airflow path.

9. A method for online dilution sampling and measurement of particulate matter, characterized in that: The particulate matter online dilution sampling and measurement system according to any one of claims 1 to 8 further includes the following steps: Particulate matter pre-separation is performed on the sampled flue gas to remove large-diameter particles; The pre-separated sampled flue gas was diluted and cooled step by step using a multi-stage dilution device; The diluted sampled flue gas is mixed with a stream of charged ions generated by ionization to charge the particulate matter, and the charge signal is measured to obtain concentration information. The flue gas, after concentration measurement, is filtered and collected before being discharged.

10. The online dilution sampling and measurement method for particulate matter according to claim 9, characterized in that: In the dilution step, the flow rate of the primary dilution gas is controlled to be 1.5 times the flow rate of the sampled flue gas; by monitoring the pressure of the secondary dilution gas and adjusting its flow rate, the total dilution ratio of the system is controlled to be greater than 20 times; at the same time, the total residence time of the sampled flue gas from entering the system to the completion of dilution is controlled to be greater than 10 seconds, and the temperature of the diluted flue gas is kept below 42°C.

Images